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EP0190458B1 - Process and apparatus for continuously manufacturing spheroidal graphite cast iron pipes with a controlled microstructure - Google Patents

Process and apparatus for continuously manufacturing spheroidal graphite cast iron pipes with a controlled microstructure Download PDF

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Publication number
EP0190458B1
EP0190458B1 EP85116525A EP85116525A EP0190458B1 EP 0190458 B1 EP0190458 B1 EP 0190458B1 EP 85116525 A EP85116525 A EP 85116525A EP 85116525 A EP85116525 A EP 85116525A EP 0190458 B1 EP0190458 B1 EP 0190458B1
Authority
EP
European Patent Office
Prior art keywords
tube
temperature
vat
die
cooled
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP85116525A
Other languages
German (de)
French (fr)
Other versions
EP0190458A1 (en
Inventor
Claude Bak
Rio Bellocci
Yves Gourmel
Michel Pierrel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pont a Mousson SA
Original Assignee
Pont a Mousson SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pont a Mousson SA filed Critical Pont a Mousson SA
Priority to AT85116525T priority Critical patent/ATE35291T1/en
Publication of EP0190458A1 publication Critical patent/EP0190458A1/en
Application granted granted Critical
Publication of EP0190458B1 publication Critical patent/EP0190458B1/en
Expired legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/14—Plants for continuous casting
    • B22D11/145—Plants for continuous casting for upward casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/006—Continuous casting of metals, i.e. casting in indefinite lengths of tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/4998—Combined manufacture including applying or shaping of fluent material
    • Y10T29/49988—Metal casting
    • Y10T29/49989—Followed by cutting or removing material

Definitions

  • the present invention relates to the production by continuous casting of spheroidal graphite cast iron pipes and to a heat treatment subsequent to this continuous casting, with a view to giving the pipes a structure suitable for use, for example, but not exclusively, a bainitic structure.
  • EP-A-0 151 723 discloses the manufacture by ascending vertical continuous casting of a metal tube made of cast iron, without the use of a core.
  • Patent FR-A-2 415 501 discloses the manufacture of a cast iron pipe by vertical downward continuous casting, with the use of a core to form the cavity of the barrel of the pipe.
  • patent FR-A-2522291 discloses the manufacture of a centrifugal tube made of spheroidal graphite cast iron with a bainitic structure by heat treatment subsequent to centrifugal casting.
  • the heat treatment is carried out very advantageously by starting the quenching phase directly in the centrifuge shell, which saves significant time and saves heating energy for the treatment.
  • thermal and on the other hand is obtained an advantageous bainitic structure compared to the usual ferritic structure of cast iron pipes.
  • the bainitic structure of the GS cast iron pipe makes it possible to appreciably improve the elastic limit and the breaking strength for the same elongation value and, if one wishes to produce cast iron tubes with the mechanical characteristics usually required, a significant reduction in thickness of the cast iron pipes with bainitic structure compared to known pipes with ferritic structure.
  • the known method of manufacturing cast iron pipes by centrifugal casting is a discontinuous manufacturing process. It has the advantage of allowing austenitic quenching in situ, that is to say inside the centrifuge shell, as shown in patent FR-A-2 522 291.
  • the Applicant has posed the problem of obtaining a spheroidal graphite cast iron tube having a determined structure, for example, but not exclusively bainitic, in manufacturing by continuous casting, and in particular a homogeneous structure over the entire wall of the tube, and this in an industrially reproducible manner, despite the poor quenchability of spheroidal graphite cast iron.
  • the subject of the invention is a process for the continuous production of a spheroidal graphite cast iron tube with a homogeneous and controlled structure, chosen from structures containing bainite, bainite and ferrite, or ferrite and perlite, this process of the type in which a tube is formed by a continuous casting process inside a cooled tubular die, from a cast iron having the following composition by weight: carbon, 2.5 to 4.0% - Silicon, 2 to 4%, Manganese, 0.1 to 0.6%, Molybdenum 0 to 0.5%, Nickel, 0 to 3.5%, Copper, 0 to 11%, Magnesium, 0 at 0.5%, Sulfur, 0.1% maximum, Phosphorus, 0.06% maximum, the rest being iron, this process being characterized in that at the outlet of the cooled tubular die, the cast iron tube which has just been generated through a fluidized bath of solid refractory particles cooled to a temperature substantially lower than the temperature at which the cast iron tube is at its birth at the outlet of the
  • the invention also relates to an installation for the implementation of this method, this installation of the type comprising means for continuous casting of a spheroidal graphite cast iron tube, being characterized in that it comprises downstream of the cooled continuous casting die a fluidization tank of solid refractory particles, said tank being provided with a tubular coil of water for cooling the fluidized bath in which the coil is embedded and said tank comprising at least one inlet or outlet of the tube to pass through the fluidized bath of said particles in the tank.
  • the cooling heat treatment undergone by the spheroidal graphite cast iron tube, continuously, at the outlet of the continuous die is perfectly uniform and reproducible, which makes it possible to obtain a structure of very precise and homogeneous tube.
  • the immediate monitoring of the casting of the cast iron pipe by the heat treatment in a fluidized bath of refractory particles makes it possible to obtain a hardenability of the cast iron much greater than that which would be obtained by allowing the cast pipe to cool and warming it up and then soaking it.
  • the invention in fact makes it possible to start directly from the structure not yet treated, that is to say virgin from the cast iron pipe leaving the casting die.
  • the invention is applied to the continuous upward casting of a cast iron tube T.
  • the installation of the invention comprises:
  • a siphon block 1 made of refractory material, for example of the silico-aluminous type, essentially comprises an L-shaped pouring duct with a funnel 2 at its upper part, constituting a supply of charge and, at its lower part, an orifice for flow 3, source, at the base of a tube T forming die.
  • a cooled tubular die or crucible comprising a graphite jacket 4 of axis XX whose internal diameter corresponds to the external diameter of the tube T to be obtained and an envelope 5, for example copper, with circulation of cooling water which enters via a pipe 6 and leaves via a pipe 7.
  • the graphite jacket 4 rests directly on the siphon block 1.
  • the cooling jacket 5 mounted around the jacket 4, in contact with the latter, over almost its entire height, is not in direct contact with the siphon block 1 but is separated from it by a refractory annular base 8 of spacing.
  • the upper part of the cooling jacket 5 is located above the upper edge of the graphite jacket 4. It is the jacket 4-jacket assembly 5 which constitutes the cooled crucible or the die.
  • a fluidization tank for immersing the tube T in a fluidized medium at controlled temperature
  • the fluidization tank is mounted in the axis XX of the die (4-5) and of the cast iron tube T to be obtained, above the die (4-5), therefore in downstream of it. It comprises a container 9 or tray open to the open air at its upper part, resting for example on the upper edge of the cooling jacket 5 or resting on a frame not shown.
  • the tank 9 has an annular bottom of axis XX having a circular opening 10 corresponding to the outside diameter of the cast iron tube T which passes through it freely. Above the annular opening bottom 10 and parallel to this bottom, is fixed a porous plate 11, spaced from said bottom so as to provide an air inlet chamber 12 under a given pressure, for example between 2 and 8 bar.
  • Pressurized air is admitted into the chamber 12 through a conduit 13 under the control of equipment 14 comprising for example a pressure regulator and a pressure gauge not shown.
  • equipment 14 comprising for example a pressure regulator and a pressure gauge not shown.
  • the fluidization chamber open to the air, which contains a certain quantity of solid particles, preferably refractory, to be fluidized, for example sand 15, or else silica or else alumina.
  • this fluidization chamber is disposed a number of tubular turns 16, wound helically to a diameter between the outside diameter of the tank 9 and that of the opening 10.
  • the tubular turns 16. are traversed by water from cooling entering via a pipe 17 and leaving via a pipe 18.
  • the chimney 33 envelops a sleeve 34 for insulation, for example consisting of a felt of mineral fibers. It is a chimney 33 to slow the natural cooling of the tube T. The cooling of the tube T is all the slower the thicker the insulation sleeve 34.
  • the height of the chimney 33 is at least equal to the length of tube T to be cut.
  • the chimney 33 internally comprises rollers or rollers 35 for guiding and supporting the tube T. These rollers 35, in internal protuberance with respect to the insulation sleeve 34, are aligned parallel generating the cylindrical chimney 33 of axis XX and those of the tube T. At least part of the rollers 35 are motorized to advance the tube T.
  • the chimney 33 and the heat-insulating sleeve 34 which it contains are mounted "Tilting".
  • the chimney 33 can tilt at an angle of 90 ° by carrying at the lower part, on the tilting side, an articulation ear 36 (Fig. 2-3). On the ear 36 is fixed integrally a horizontal pin 37 of axis YY orthogonal to the axis XX.
  • the chimney 33 carries above the ear 36 a tilting ear 38 on which is articulated the end of the rod 39 of a tilting jack 40 whose body is as known, articulated on a frame 41 at the opposite end of the piston rod 39 (Fig. 3).
  • the jack 40 is for example of the double-acting hydraulic type.
  • the chimney 33 in the extended position of the rod 39 (in solid lines) the chimney 33 is vertical (axis XX), and, in the retracted position of the rod 39 (in dashed lines), the chimney 33 is horizontal (axis X1-X1) in the extension of the inlet of the holding oven 44 described below.
  • the jack 40 therefore swings the chimney 33 along the arrow AR.
  • a tunnel oven 44 for maintaining the temperature of the tube T is provided in the extension of the sleeve 34 and the chimney 33 when the latter is lying along the axis X1 X1, but extends in a direction AR2 horizontal and perpendicular to the axis X1-X1 or to a direction AR1 parallel to X1-X1.
  • the tunnel oven 44 open at its two ends, has a lateral inlet opening 42 of axis X1-X1 and an outlet opening 43, of horizontal axis parallel to the direction AR2.
  • the tunnel oven 44 For its passage through each tube T, with a 90 ° change of direction between the axis X1-X1 (or the direction AR1) and the direction AR2, the tunnel oven 44 comprises the following means for supporting and advancing the tubes T successive: it comprises retractable rollers 45 for supporting and advancing the tube T along arrows AR1 parallel to the axis X1-X1.
  • the rollers 35 of the sleeve 34 and the rollers 45 of the oven 44 are motorized in a known manner and not shown.
  • the rollers 45 are carried by vertical cylinders 47 intended to retract them below the raceways 48 of direction AR2.
  • the raceways 48 which support the tubes T are perpendicular to the generatrices of each tube T entering the oven 44.
  • the tunnel oven 44 includes a number of burners 46 (for example with gas) internally creating a heating atmosphere for maintaining the temperature of the tube T.
  • a cutting device K known per se, represented symbolically by two opposite knives.
  • the cutting device K is, for example, interposed between the extractor 33a and the chimney 33 ( Figures 1,3).
  • a dummy or false tube (not shown) consisting of a tubular steel sleeve of the same outside diameter and the same thickness as the tube T to be obtained is introduced from the top of the die 4-5, through the fluidization and heat treatment tank 9, to a level below that of the upper end of the graphite jacket 4 . Then liquid iron is introduced along the arrow f into the pouring funnel 2 to a level N located slightly below the upper part of the jacket 4 of the die 4-5.
  • This liquid iron has the following composition by weight: Carbon 2.5 to 4.0%, Silicon 2 to 4%, Manganese 0.1 to 0.6%, Molybdenum 0 to 0.5%, Nickel 0 to 3.5 %, Copper 0 to 11%, Magnesium 0 to 0.5%, Sulfur 0.1% maximum, Phosphorus 0.06% maximum, the rest being iron.
  • the tank 9, initially empty of sand, before the introduction of the manikin is filled with sand at 15, in the fluidization chamber, as soon as the manikin is submerged below the level N. In fact, the manikin then offers the wall internal tubular which was missing to contain a mass of sand 15 which can then be introduced. Cooling water is admitted through the conduits 6 and 7 for the casing 5 and 17 and 18 for the tubular turns 16.
  • the cast iron cools in contact with the jacket 4 along a solidification front S of approximately frustoconical shape, and hangs on the dummy which is pulled upwards by the motorized rollers 35 of the chimney 33a, then the chimney 33 and drives, step by step, the part of cast iron solidified in the form of a priming tube T.
  • the fluidized sand bath 15 is at a temperature adjusted to the value necessary for obtaining the desired structure (for example between 100 and 200 ° C. for a bainitic structure) that the first phase of the heat treatment is carried out, which is a quenching of bainitization, without heating, taking advantage of the calories from the tube leaving the die 4-5.
  • This temperature of the sand bath between 100 and 200 ° C is kept constant by virtue of the circulation of water at a temperature of the order of 20 ° C. in the conduits 17 and 18.
  • the flow rate of fluidizing air entering through the conduit 13 and the speed of circulation of the water depends on the intensity of sand bath cooling 15.
  • the fluidization air flow and the water circulation speed are adjustable.
  • the temperature drop of the tube T is abrupt (from 850 ° C to about 500 ° C) and takes place in a very short time, during the crossing of the fluidization tank 9 where the tube T is licked over its entire surface by the fluidized sand bath 15 maintained by the coil 16 at a temperature of the order of 100 to 200 ° C. It is a hardening of bainitization.
  • the fluidized bath 15 therefore performs a true intense drainage of calories out of the tube T formed and this uniformly over the entire wall of the tube T immersed in the sand bath 15, so that each point of the tube T undergoes the same heat treatment .
  • the tube T enters the extractor 33a which, while protecting it against cooling, drives it by its motorized rollers 35 to the chimney 33 of natural and slow cooling which is in the position d vertical axis, through the cutting device K.
  • the entry into the chimney 33 corresponds to point d.
  • the interval of passage of the extractor 33a between the tank 9 and the chimney 33, where the cutting or cutting-off device K is located corresponds to the section of curve cd, with a slight drop in temperature of the outside wall of the tube T: point d is at a temperature close to 480 ° C.
  • the cooling of the tube T in this chimney 33 is slow due to the heat-insulating sleeve 34 of the chimney 33.
  • the tube T is at a temperature of the order of 350 ° C. .
  • the cutting of the tube T is carried out by means of the cutting device K, when the desired length of tube T is inside the chimney 33.
  • Second heat treatment phase - temperature maintenance (area between sections e1f1 and e2f2 of the curve in Fig. 5):
  • the cut T tube is transported inside the tunnel oven 44 by moving it in a direction AR1 parallel to the horizontal axis X1-X1 of the tilted chimney 33.
  • the jack 40 is actuated so as to tilt the chimney 33 and the tube T which it contains and supports, an angle of 90 ° in the direction of the arrow AR around the axis YY of the pin 37.
  • the chimney 33 rocks until the end of the rod 39 stroke of the jack 40 (portion in phantom in Fig. 3).
  • This change of direction is effected by as follows: the cylinders 47 retract the rollers 45 from below the rolling chimneys 48 so that the tube T is deposited on the chimneys 48 and the endless drive chains 49 which drive it in the new direction AR2 to the outlet 43 from the oven.
  • the tunnel oven 44 is heated by the gas burners 46 to a temperature such that the tube T advancing along the tunnel oven 44 at an adjustable speed (by adjusting the drive speed of the drive chains 49) is maintained at a constant isothermal temperature between two limits (two isotherms): on the one hand an upper limit (section e1f1 or isotherm of 450 ° C in Fig. 5) and on the other hand a lower limit (section e2f2 or isotherm of 250 ° VS).
  • the temperature maintenance of the tube T takes place along an intermediate or isothermal section ef, between 250 ° C and 450 ° C, (Fig. 5), it is in the chimney 33 that the tube T passes from the temperature d (entry of the chimney 33) to the temperature e (exit of the chimney 33 and entry into the oven 44) comprised between the temperatures e1 and e2, respectively 450 ° C and 250 ° C.
  • This heat treatment phase in the holding oven 44 ensures the stability of the bainite and possibly of the residual austenite in the matrix of the structure. Maintaining bainitization ensures a homogeneous bainitic or austenitic bainitic structure. Beyond the points f1 or f2, the tube T is cooled as described below in paragraph 4).
  • the tube T leaves the tunnel oven 44 at a temperature between 450 ° C and 250 ° C between the points f2 and f1 to be cooled in the third and last phase as described below in paragraph 4). It is therefore inside the hatched area of FIG. 5 between the sections e1f1 and e2f2 (section ef in broken lines) that is the maintenance at constant temperature of the tube T.
  • the bainitic or possibly bainitic-austenitic structure is homogeneous and offers the optimal mechanical characteristics indicated in patent FR-A 2 522,291.
  • the tube T cools in the open air to ordinary temperature, for example between 5 and 25 ° C, depending on the section flg, in a short time and, finally retains this temperature which is that of the outside air (gh section).
  • the T-tube in spheroidal graphite cast iron then has a bainitic structure or a mixed bainite-austenite structure.
  • Cast iron tubes preferably water supply tubes, with nominal diameters of 600 to 2,500 mm and more particularly from 1,000 to 1,600 mm can be formed and heat treated with thicknesses of between 5 and 20 mm. This method and this installation are therefore particularly advantageous for the manufacture of T-shaped tubes of large diameters and of relatively small thickness.
  • the first quenching phase begins at point b of the curve in FIG. 2 by taking advantage of the heat of the tube T without adding calories, to bring the tube T to the temperature of 800-850 ° C. approximately.
  • the quenching ability of the spheroidal graphite cast iron tube T is much higher than the quenching ability of a spheroidal graphite cast iron tube T than l 'We would have allowed to cool and then we would have reheated to a temperature of 800 to 850 ° C to carry out bainitic quenching.
  • the use of the tank 9 in a fluidized sand bath 15 ensures the temperature uniformity of the tube T over its entire length and over its entire cylindrical wall and ensures the fidelity, the reproducibility of the heat treatment.
  • the use of the fluidized sand bath 15, or any other suitable particles of a solid material as a means of evacuating or draining the calories from the tube T towards the outside, instead of cooling water, is a safety due to the proximity of the cast iron bath F.
  • the process and the installation for thermal treatment of the invention are applied to a continuous vertical downward casting of a cast iron tube T.
  • a pouring basin 19 at the upper part of the installation belongs to a low pressure casting ladle, not shown, or possibly to a reverberatory electric furnace, the capacity of which is subjected to the pressure of a neutral gas such as l 'nitrogen or argon.
  • the pouring basin 19 has at its lower part a pouring orifice 20 of axis XX.
  • the pouring orifice 20 is crossed axially by a graphite core 21 which gives the internal shape of the tube T to be obtained and by the head 22 of a die 23 also in graphite giving the external shape of the tube T to be obtained.
  • the core 21 is a hollow cylinder internally containing a heating device, for example an inductor 24 in the form of a water-cooled coil.
  • the die 23 provides with the core 21 an annular space 25 corresponding to the internal and external dimensions of the tube T to be obtained, the space inside which the cast iron F must gradually solidify along a solidification front from the wall of the die 23.
  • the die head 22 provides, with the pouring orifice 20, an annular space filled with an insulating refractory sleeve 26, the sleeve 26 being intended to obstruct possible cooling flows of the liquid iron leaving the basin 19.
  • the liquid metal casing 29 with a low melting point is supplied either from above by a conduit 30, or from below by a conduit 31 which is also used for the evacuation of liquid metal from re cold when necessary.
  • the jacket 27 is itself tightly wrapped by a hollow water-cooling cooling sleeve 32, the internal wall of which is in contact with the external wall of the jacket 27.
  • annular bottom fluidization tank having an opening 10 for the passage of the tube T and an annular porous plate 11 also having an opening for the passage of the tube T.
  • the tank 9 contains above the porous plate 11 a fluidized sand bath 15 cooled by a helical tubular coil with turns 16 cooled by water.
  • the fluidization tank 9 receives the tube T heat treated by its upper part instead of receiving it through its opening 10 as in the previous example.
  • the temperature evolution of the tube T takes place before and during the crossing of the fluidization tank 9 according to the same curve passing through the points a, b, c of FIG. 5 (bainitization quenching treatment).
  • a chimney 33 with a heat-insulating sleeve 34 follow the tank 9 and precede a gas-burner holding tunnel tunnel, not shown, but which does not is other than the oven 44 of Figs. 2 and 4.
  • a device K for cutting the tube T is interposed between the extractor 33b and the chimney 33.
  • the chimney comprises at its lower part an ear 36 and a pin 37 of YY tilting axis as well as an ear 38 and tilting means of an angle of 90 ° which are not shown.
  • the complete heat treatment according to the invention takes place under the same conditions as in the example of FIGS. 1, 2, 3, 4 and 5 according to the three phases illustrated in FIG. 5, that is to say the austenitization-bainitization quenching phase first along the section a, b between the die 23 and the fluidization tank 9, then along the section b, c of sudden drop in temperature for bainitization through the fluidization tank 9 and finally, after the tube T has been cut, along a horizontal section ef (or isothermal ef) located in the hatched zone between the upper isotherm e1f1 (450 ° C.) and l 'lower isotherm e2f2 (250 ° C) occurs a temperature stabilization inside the holding tunnel oven 44.
  • the heat treatment ends with the final phase f1 or f2, g, h of air cooling free from the tube T taken out of the bainitization maintenance oven 44.
  • the treatment of the invention allows it, faithfully and industrially reproducible.
  • the chimney 33 is eliminated.
  • the treatment of the invention makes it possible to reproduce a bainite + ferrite structure.
  • the temperature of the fluidized bath 15 must be between 100 and 200 ° C. as for the bainite alone.
  • the temperature of the fluidized bath 15 must be such that the cooling rate of the tube T passing through this bath 15 is constant.
  • the constant cooling rate of the tube T through a three-phase band atpha + gamma + graphite shown in hatching in the thermal diagram of FIG. 7 (the band a + y + G is so called because it illustrates the eutectoid transformation domain of cast iron where the three phases ferrite, austenite and graphite coexist from the ternary diagram "iron, carbon, silicon") gives rise to the proportions selected ferrite and perlite.
  • the constant and adjustable speed of passage of the tube T through the fluidized bath 15 generates a constant cooling speed through the three-phase strip (a + y + G) and therefore guarantees a constant and previously chosen proportion of each of the phases: ferrite and perlite.
  • the intensity of the cooling can be adjusted as in the case of bainitic quenching by the choice of the fluidization air flow (conduit 13) and the choice of the speed of circulation of water in the coil 16. If one wants to decrease the intensity of the cooling, one can suppress any circulation of water in the coil 16, or even replace the coil 16 by a heating means.
  • This heating means can be, for example, an electric heating resistor embedded in the fluidized bath 15 or enveloping the metal tank 9 or also arranged so as to heat the fluidizing air (conduit 13).
  • gas burners can also be used.
  • point a corresponds to the birth of the tube T outside of the die 4-5. It is the same as in the first example (Fig. 5): the temperature is 1100 ° C. At the inlet of the fluidized bath, the temperature of the tube T is 850 ° C. at point b, as in FIG. 5. At the outlet of the fluidized bath, at point c, the temperature of the tube T is lowered to a value greater than 600 ° C. It should be noted that the drop in temperature according to the diagram in FIG. 7 between points b and c is much less brutal and much more progressive than in the treatment according to the diagram in FIG. 5.
  • the three-phase strip (a + y + G) (eutectoid transformation zone of the cast iron) in a temperature range between 770 and 810 ° C where the cooling rate of the tube T is constant.
  • the strip (a + y + G) is hatched.
  • the tube T Opening into the open air at the outlet of the fluidized bath 15 and no longer having a chimney 33 to pass through, the tube T undergoes natural cooling in the open air illustrated by the section of curve ck.

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  • Mechanical Engineering (AREA)
  • Engineering & Computer Science (AREA)
  • Heat Treatment Of Articles (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Continuous Casting (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Prostheses (AREA)
  • Rigid Pipes And Flexible Pipes (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Heat Treatment Of Steel (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Investigating And Analyzing Materials By Characteristic Methods (AREA)
  • Water Treatment By Sorption (AREA)
  • Cold Cathode And The Manufacture (AREA)
  • Details Of Garments (AREA)
  • Furnace Housings, Linings, Walls, And Ceilings (AREA)

Abstract

The invention concerns a method and apparatus for thermally treating cast-iron pipes formed in a continuous casting die. The pipe or tube undergoes tempering by passing through a vat which is located downstream from the continuous casting die. The vat contains a continuously cooled bath of fluidized sand or the like which lowers the temperature of the tube in a uniform manner and makes it possible to obtain a very precise and homogeneous tube structure.

Description

La présente invention est relative à la fabrication par coulée continue de tuyaux en fonte à graphite sphéroïdal et à un traitement thermique consécutif à cette coulée continue, en vue de donner aux tuyaux une structure appropriée à l'usage, par exemple, mais non exclusivement, une structure bainitique.The present invention relates to the production by continuous casting of spheroidal graphite cast iron pipes and to a heat treatment subsequent to this continuous casting, with a view to giving the pipes a structure suitable for use, for example, but not exclusively, a bainitic structure.

On connaît par la demande de brevet EP-A-0 151 723 la fabrication par coulée continue verticale ascendante d'un tube métallique en fonte, sans utilisation d'un noyau.The patent application EP-A-0 151 723 discloses the manufacture by ascending vertical continuous casting of a metal tube made of cast iron, without the use of a core.

On connaît par le brevet FR-A-2 415 501 la fabrication d'un tuyau en fonte par coulée continue verticale descendante, avec utilisation d'un noyau pour former la cavité du fût du tuyau.Patent FR-A-2 415 501 discloses the manufacture of a cast iron pipe by vertical downward continuous casting, with the use of a core to form the cavity of the barrel of the pipe.

Par ailleurs, on connaît par le brevet FR-A-2522291 la fabrication d'un tube centrifugé en fonte à graphite sphéroïdal à structure bainitique par traitement thermique consécutif à la coulée centrifuge.Furthermore, patent FR-A-2522291 discloses the manufacture of a centrifugal tube made of spheroidal graphite cast iron with a bainitic structure by heat treatment subsequent to centrifugal casting.

Suivant ce brevet, d'une part le traitement thermique est réalisé de manière très avantageuse en commençant la phase de trempe directement en coquille de centrifugation, ce qui permet de gagner un temps important et d'économiser de l'énergie de chauffe pour le traitement thermique, et d'autre part est obtenue une structure bainitique avantageuse par rapport à la structure ferritique habituelle des tuyaux en fonte. En effet, la structure bainitique du tuyau en fonte GS permet d'améliorer notablement la limite élastique et la résistance à la rupture pour une même valeur d'allongement et, si l'on veut réaliser des tubes en fonte aux caractéristiques mécaniques habituellement exigibles, un allègement notable par réduction d'épaisseur des tuyaux en fonte à structure bainitique par rapport aux tuyaux connus à structure ferritique.According to this patent, on the one hand, the heat treatment is carried out very advantageously by starting the quenching phase directly in the centrifuge shell, which saves significant time and saves heating energy for the treatment. thermal, and on the other hand is obtained an advantageous bainitic structure compared to the usual ferritic structure of cast iron pipes. Indeed, the bainitic structure of the GS cast iron pipe makes it possible to appreciably improve the elastic limit and the breaking strength for the same elongation value and, if one wishes to produce cast iron tubes with the mechanical characteristics usually required, a significant reduction in thickness of the cast iron pipes with bainitic structure compared to known pipes with ferritic structure.

Le procédé connu de fabrication des tuyaux en fonte par coulée centrifuge est un procédé de fabrication discontinue. Il présente l'avantage de permettre la trempe austénitique in situ, c'est-à-dire à l'intérieur de la coquille de centrifugation, comme le montre le brevet FR-A-2 522 291.The known method of manufacturing cast iron pipes by centrifugal casting is a discontinuous manufacturing process. It has the advantage of allowing austenitic quenching in situ, that is to say inside the centrifuge shell, as shown in patent FR-A-2 522 291.

La Demanderesse s'est posé le problème d'obtenir un tube en fonte à graphite sphéroïdal ayant une structure déterminée, par exemple, mais non exclusivement bainitique, dans la fabrication par coulée continue, et notamment une structure homogène sur toute la paroi du tube, et ceci de manière industriellement reproductible, malgré la faible aptitude à la trempe de la fonte à graphite sphéroïdal.The Applicant has posed the problem of obtaining a spheroidal graphite cast iron tube having a determined structure, for example, but not exclusively bainitic, in manufacturing by continuous casting, and in particular a homogeneous structure over the entire wall of the tube, and this in an industrially reproducible manner, despite the poor quenchability of spheroidal graphite cast iron.

Ce problème est résolu par le procédé de l'invention.This problem is solved by the method of the invention.

L'invention a pour objet un procédé de fabrication en continu d'un tube en fonte à graphite sphéroïdal et à structure homogène et contrôlée, choisie parmi les structures contenant de la bainite, de la bainite et de la ferrite, ou de la ferrite et de la perlite, ce procédé du type dans lequel on forme un tube par un procédé de coulée continue à l'intérieur d'une filière tubulaire refroidie, à partir d'une fonte ayant la composition suivante en poids: carbone, 2,5 à 4,0% - Silicium, 2 à 4%, Manganèse, 0,1 à 0,6%, Molybdène 0 à 0,5%, Nickel, 0 à 3,5%, Cuivre, 0 à 11%, Magnésium, 0 à 0,5%, Soufre, 0,1% au maximum, Phosphore, 0,06% au maximum, le reste étant du fer, ce procédé étant caractérisé en ce que à la sortie de la filière tubulaire refroidie, on fait passer le tube en fonte qui vient d'être engendré à travers un bain fluidisé de particules réfractaires solides refroidies à une température sensiblement inférieure à la température à laquelle se trouve le tube en fonte à sa naissance à la sortie de la filière tubulaire refroidie.The subject of the invention is a process for the continuous production of a spheroidal graphite cast iron tube with a homogeneous and controlled structure, chosen from structures containing bainite, bainite and ferrite, or ferrite and perlite, this process of the type in which a tube is formed by a continuous casting process inside a cooled tubular die, from a cast iron having the following composition by weight: carbon, 2.5 to 4.0% - Silicon, 2 to 4%, Manganese, 0.1 to 0.6%, Molybdenum 0 to 0.5%, Nickel, 0 to 3.5%, Copper, 0 to 11%, Magnesium, 0 at 0.5%, Sulfur, 0.1% maximum, Phosphorus, 0.06% maximum, the rest being iron, this process being characterized in that at the outlet of the cooled tubular die, the cast iron tube which has just been generated through a fluidized bath of solid refractory particles cooled to a temperature substantially lower than the temperature at which the cast iron tube is at its birth at the outlet of the cooled tubular die.

L'invention a également pour objet une installation pour la mise en oeuvre de ce procédé, cette installation du type comportant des moyens de coulée continue d'un tube en fonte à graphite sphéroïdal, étant caractérisée en ce qu'elle comporte en aval de la filière refroidie de coulée continue un bac de fluidisation de particules réfractaires solides, ledit bac étant pourvu d'un serpentin tubulaire d'eau de refroidissement du bain fluidisé dans lequel est noyé le serpentin et ledit bac comportant au moins un orifice d'entrée ou de sortie du tube devant traverser le bain fluidisé desdites particules dans le bac.The invention also relates to an installation for the implementation of this method, this installation of the type comprising means for continuous casting of a spheroidal graphite cast iron tube, being characterized in that it comprises downstream of the cooled continuous casting die a fluidization tank of solid refractory particles, said tank being provided with a tubular coil of water for cooling the fluidized bath in which the coil is embedded and said tank comprising at least one inlet or outlet of the tube to pass through the fluidized bath of said particles in the tank.

Grâce à ce procédé et à cette installation, le traitement thermique de refroidissement subi par le tube en fonte à graphite sphéroïdal, en continu, à la sortie de la filière continue, est parfaitement uniforme et reproductible, ce qui permet d'obtenir une structure de tube bien précise et homogène. En particulier, le suivi immédiat de la coulée du tuyau en fonte par le traitement thermique en bain fluidisé de particules réfractaires permet d'obtenir une trempabilité de la fonte bien supérieure à celle que l'on aurait en laissant le tuyau coulé se refroidir et en le réchauffant pour le tremper ensuite. L'invention permet en effet de partir directement de la structure non encore traitée, c'est-à-dire vierge du tuyau de fonte sortant de la filière de coulée.Thanks to this process and this installation, the cooling heat treatment undergone by the spheroidal graphite cast iron tube, continuously, at the outlet of the continuous die, is perfectly uniform and reproducible, which makes it possible to obtain a structure of very precise and homogeneous tube. In particular, the immediate monitoring of the casting of the cast iron pipe by the heat treatment in a fluidized bath of refractory particles makes it possible to obtain a hardenability of the cast iron much greater than that which would be obtained by allowing the cast pipe to cool and warming it up and then soaking it. The invention in fact makes it possible to start directly from the structure not yet treated, that is to say virgin from the cast iron pipe leaving the casting die.

D'autres caractéristiques et avantages apparaîtront au cours de la description qui va suivre:

  • Au dessin annexé, donné uniquement à titre d'exemple,
  • - la Fig. 1 est une vue schématique en coupe d'une installation suivant l'invention à coulée continue ascendante, d'un tube sans emboîtement,
  • - la Fig. 2 est une vue schématique en coupe complémentaire de la Fig. 1 pour illustrer l'installation de traitement thermique de l'invention,
  • - la Fig. 3 est une vue schématique en élévation d'un détail mécanique de l'installation de traitement thermique de l'invention,
  • - la Fig. 4 est une vue schématique partielle en coupe suivant la ligne 4-4 de la Fig. 2 d'une partie de l'installation thermique,
  • - la Fig. 5 est un diagramme de traitement thermique portant la ligne d'évolution de température d'un tube en fonte, pendant le temps du traitement thermique, pour l'obtention d'une structure bainitique,
  • - la Fig. 6 est une vue schématique partielle en coupe, d'une variante d'installation de l'invention avec coulée continue descendante d'un tube en fonte sans emboîtement,
  • - la Fig. 7 est un diagramme analogue à celui de la Fig. 5 d'une variante de traitement thermique pour l'obtention d'une structure ferrito-perlitique.
Other characteristics and advantages will appear during the description which follows:
  • In the accompanying drawing, given solely by way of example,
  • - Fig. 1 is a schematic sectional view of an installation according to the invention with continuous ascending casting, of a tube without interlocking,
  • - Fig. 2 is a diagrammatic view in complementary section of FIG. 1 to illustrate the thermal treatment installation of the invention,
  • - Fig. 3 is a schematic elevational view of a mechanical detail of the thermal treatment installation of the invention,
  • - Fig. 4 is a partial schematic view in section along line 4-4 of FIG. 2 of a part of the thermal installation,
  • - Fig. 5 is a heat treatment diagram showing the temperature development line of a cast iron tube, during the heat treatment time, for obtaining a bainitic structure,
  • - Fig. 6 is a partial schematic sectional view of a variant installation of the invention with continuous downward casting of a cast iron tube without interlocking,
  • - Fig. 7 is a diagram similar to that of FIG. 5 of a variant of heat treatment for obtaining a ferrito-pearlitic structure.

Suivant l'exemple d'exécution illustré à la Fig. 1, l'invention est appliquée à la coulée continue ascendante d'un tube en fonte T.According to the example of execution illustrated in FIG. 1, the invention is applied to the continuous upward casting of a cast iron tube T.

L'installation de l'invention comporte:The installation of the invention comprises:

1°) Une alimentation en fonte liquide par bloc-siphon:1 °) A supply of liquid iron by siphon block:

un bloc-siphon 1, en matériau réfractaire, par exemple de type silico-alumineux comporte essentiellement un conduit de coulée en L à entonnoir de coulée 2 à sa partie supérieure, constituant une alimentation en charge et, à sa partie inférieure, un orifice de coulée 3, en source, à la base d'une filière de formation du tube T.a siphon block 1, made of refractory material, for example of the silico-aluminous type, essentially comprises an L-shaped pouring duct with a funnel 2 at its upper part, constituting a supply of charge and, at its lower part, an orifice for flow 3, source, at the base of a tube T forming die.

2°) Un creuset refroidi extérieurement ou filière:2 °) An externally cooled crucible or die:

Dans l'axe XX de l'orifice de coulée en source 3 est montée une filière tubulaire ou creuset refroidi comprenant une chemise 4 en graphite d'axe XX dont le diamètre intérieur correspond au diamètre extérieur du tube T à obtenir et une enveloppe 5, par exemple en cuivre, à circulation d'eau de refroidissement qui entre par un conduit 6 et sort par un conduit 7. La chemise 4 en graphite repose directement sur le bloc-siphon 1. L'enveloppe de refroidissement 5 montée autour de la chemise 4, en contact avec celle-ci, sur presque toute sa hauteur, n'est pas en contact direct avec le bloc-siphon 1 mais en est séparée par un socle annulaire réfractaire 8 d'espacement. La partie supérieure de l'enveloppe de refroidissement 5 est située au-dessus de la tranche supérieure de la chemise en graphite 4. C'est l'ensemble chemise 4-enveloppe 5 qui constitue le creuset refroidi ou la filière.In the axis XX of the source pouring orifice 3 is mounted a cooled tubular die or crucible comprising a graphite jacket 4 of axis XX whose internal diameter corresponds to the external diameter of the tube T to be obtained and an envelope 5, for example copper, with circulation of cooling water which enters via a pipe 6 and leaves via a pipe 7. The graphite jacket 4 rests directly on the siphon block 1. The cooling jacket 5 mounted around the jacket 4, in contact with the latter, over almost its entire height, is not in direct contact with the siphon block 1 but is separated from it by a refractory annular base 8 of spacing. The upper part of the cooling jacket 5 is located above the upper edge of the graphite jacket 4. It is the jacket 4-jacket assembly 5 which constitutes the cooled crucible or the die.

3°) Un dispositif de traitement thermique en trois parties:3 °) A thermal treatment device in three parts:

A) Un bac de fluidisation pour immerger le tube T dans un milieux fluidisé à température contrôlée,A) A fluidization tank for immersing the tube T in a fluidized medium at controlled temperature,

B) Un manchon de calorifugeage du tube T pour ralentir son refroidissement.B) A sleeve for insulating the tube T to slow its cooling.

C) Et comme connu en soi, un four-tunnel de maintien du tube T en température.C) And as known per se, a tunnel oven for maintaining the temperature of the tube T.

a) Conformément à l'invention, le bac de fluidisation est monté dans l'axe XX de la filière (4-5) et du tube T en fonte à obtenir, au-dessus de la filière (4-5), donc en aval de celle-ci. Il comporte un récipient 9 ou bac ouvert à l'air libre à sa partie supérieure, reposant par exemple sur la tranche supérieure de l'enveloppe de refroidissement 5 ou reposant sur un bâti non représenté. Le bac 9 a un fond annulaire d'axe XX présentant une ouverture circulaire 10 correspondant au diamètre extérieur du tube en fonte T qui la traverse librement. Au-dessus du fond annulaire à ouverture 10 et parallèlement à ce fond, est fixée une plaque poreuse 11, espacée dudit fond de manière à ménager une chambre d'entrée d'air 12 sous une pression donnée, par exemple comprise entre 2 et 8 bar. De l'air sous pression est admis dans la chambre 12 par un conduit 13 sous le contrôle d'un équipement 14 comprenant par exemple un détendeur et un manomètre non représentés. Au-dessus de la plaque poreuse 11 se trouve la chambre de fluidisation ouverte à l'air libre, qui contient une certaine quantité de particules solides de préférence réfractaires, à fluidiser, par exemple de sable 15, ou bien de silice ou bien d'alumine. Dans cette chambre de fluidisation est disposé un certain nombre de spires tubulaires 16, enroulées en hélice à un diamètre compris entre le diamètre extérieur du bac 9 et celui de l'ouverture 10. Les spires tubulaires 16. sont parcourues par de l'eau de refroidissement entrant par un conduit 17 et sortant par un conduit 18.a) In accordance with the invention, the fluidization tank is mounted in the axis XX of the die (4-5) and of the cast iron tube T to be obtained, above the die (4-5), therefore in downstream of it. It comprises a container 9 or tray open to the open air at its upper part, resting for example on the upper edge of the cooling jacket 5 or resting on a frame not shown. The tank 9 has an annular bottom of axis XX having a circular opening 10 corresponding to the outside diameter of the cast iron tube T which passes through it freely. Above the annular opening bottom 10 and parallel to this bottom, is fixed a porous plate 11, spaced from said bottom so as to provide an air inlet chamber 12 under a given pressure, for example between 2 and 8 bar. Pressurized air is admitted into the chamber 12 through a conduit 13 under the control of equipment 14 comprising for example a pressure regulator and a pressure gauge not shown. Above the porous plate 11 is the fluidization chamber open to the air, which contains a certain quantity of solid particles, preferably refractory, to be fluidized, for example sand 15, or else silica or else alumina. In this fluidization chamber is disposed a number of tubular turns 16, wound helically to a diameter between the outside diameter of the tank 9 and that of the opening 10. The tubular turns 16. are traversed by water from cooling entering via a pipe 17 and leaving via a pipe 18.

Au-dessus du bac 9, et dans le même axe X-X, est montée, conformément à l'invention, une cheminée 33 de diamètre intérieur 10 supérieur au diamètre extérieur du tube T à former. La cheminée 33 enveloppe un manchon 34 de calorifugeage, par exemple constitué d'un feutre de fibres minérales. Il s'agit d'une cheminée 33 pour ralentir le refroidissement naturel du tube T. Le refroidissement du tube T est d'autant plus lent que le manchon de calorifugeage 34 est plus épais. La hauteur de la cheminée 33 est au moins égale à la longueur de tube T à tronçonner.Above the tank 9, and in the same axis X-X, is mounted, according to the invention, a chimney 33 of internal diameter 10 greater than the external diameter of the tube T to be formed. The chimney 33 envelops a sleeve 34 for insulation, for example consisting of a felt of mineral fibers. It is a chimney 33 to slow the natural cooling of the tube T. The cooling of the tube T is all the slower the thicker the insulation sleeve 34. The height of the chimney 33 is at least equal to the length of tube T to be cut.

Conformément à l'invention, la cheminée 33 comporte intérieurement des galets ou rouleaux 35 de guidage et de support du tube T. Ces galets 35, en protubérance interne par rapport au manchon de calorifugeage 34, sont alignés parallèle- mentaux génératrices de la cheminée cylindrique 33 d'axe XX et à celles du tube T. Au moins une partie des galets 35 sont motorisés pour faire progresser le tube T. Conformément à l'invention également, la cheminée 33 et le manchon de calorifugeage 34 qu'elle contient sont montés «basculants». La cheminée 33 peut basculer d'un angle de 90° en portant à la partie inférieure, du côté du basculement, une oreille d'articulation 36 (Fig. 2-3). Sur l'oreille 36 est fixé solidairement un tourillon horizontal 37 d'axe YY orthogonal à l'axe XX. En vue de son basculement, la cheminée 33 porte au-dessus de l'oreille 36 une oreille de basculement 38 sur laquelle est articulée l'extrémité de la tige 39 d'un vérin 40 de basculement dont le corps est comme connu, articulé sur un bâti 41 à l'extrémité opposé de la tige de piston 39 (Fig. 3). Le vérin 40 est par exemple de type hydraulique à double effet. Sur cet exemple (Fig. 3), en position d'extension de la tige 39 (en trait plein) la cheminée 33 est verticale (axe X-X), et, en position de rétraction de la tige 39 (en trait mixte), la cheminée 33 est horizontale (axe X1-X1) dans le prolongement de l'entrée du four de maintien 44 décrit plus loin. Le vérin 40 fait donc basculer la cheminée 33 suivant la flèche AR.According to the invention, the chimney 33 internally comprises rollers or rollers 35 for guiding and supporting the tube T. These rollers 35, in internal protuberance with respect to the insulation sleeve 34, are aligned parallel generating the cylindrical chimney 33 of axis XX and those of the tube T. At least part of the rollers 35 are motorized to advance the tube T. According to the invention also, the chimney 33 and the heat-insulating sleeve 34 which it contains are mounted "Tilting". The chimney 33 can tilt at an angle of 90 ° by carrying at the lower part, on the tilting side, an articulation ear 36 (Fig. 2-3). On the ear 36 is fixed integrally a horizontal pin 37 of axis YY orthogonal to the axis XX. In view of its tilting, the chimney 33 carries above the ear 36 a tilting ear 38 on which is articulated the end of the rod 39 of a tilting jack 40 whose body is as known, articulated on a frame 41 at the opposite end of the piston rod 39 (Fig. 3). The jack 40 is for example of the double-acting hydraulic type. In this example (Fig. 3), in the extended position of the rod 39 (in solid lines) the chimney 33 is vertical (axis XX), and, in the retracted position of the rod 39 (in dashed lines), the chimney 33 is horizontal (axis X1-X1) in the extension of the inlet of the holding oven 44 described below. The jack 40 therefore swings the chimney 33 along the arrow AR.

c) Comme connu, un four-tunnel 44 (Fig. 2 et 4) de maintien en température du tube T est prévu dans le prolongement du manchon 34 et de la cheminée 33 lorsque celle-ci est couchée suivant l'axe X1 X1, mais s'étend suivant une direction AR2 horizontale et perpendiculaire à l'axe X1-X1 ou à une direction AR1 parallèle à X1-X1. Le four-tunnel 44, ouvert à ses deux extrémités, comporte une ouverture d'entrée 42 latérale d'axe X1-X1 et une ouverture 43 de sortie, d'axe horizontal parallèle à la direction AR2. Pour sa traversée par chaque tube T, avec changement de direction de 90° entre l'axe X1-X1 (ou la direction AR1) et la direction AR2, le four-tunnel 44 comporte les moyens suivants de support et d'avancement des tubes T successifs: il comporte des rouleaux 45 escamotables de support et d'avancement du tube T suivant des flèches AR1 parallèles à l'axe X1-X1. En vue de cet avancement, au moins une partie des galets 35 du manchon 34 et des rouleaux 45 du four 44 sont motorisés d'une manière connue et non représentée. Les rouleaux 45 sont portés par des vérins verticaux 47 destinés à les escamoter au-dessous des chemins de roulement48 de direction AR2. Les chemins de roulement 48 qui supportent les tubes T sont perpendiculaires aux génératrices de chaque tube T entrant dans le four 44. Pour faire avancer les tubes T successifs dans le four-tunnel 44 suivant la direction AR2 sont prévues deux chaînes sans fin jumelées 49 portées par des roues 50 motorisées de manière non représentée. Enfin le four-tunnel 44 comporte un certain nombre de brûleurs 46 (à gaz par exemple) créant intérieurement une atmosphère chauffante de maintien en température du tube T.c) As known, a tunnel oven 44 (FIGS. 2 and 4) for maintaining the temperature of the tube T is provided in the extension of the sleeve 34 and the chimney 33 when the latter is lying along the axis X1 X1, but extends in a direction AR2 horizontal and perpendicular to the axis X1-X1 or to a direction AR1 parallel to X1-X1. The tunnel oven 44, open at its two ends, has a lateral inlet opening 42 of axis X1-X1 and an outlet opening 43, of horizontal axis parallel to the direction AR2. For its passage through each tube T, with a 90 ° change of direction between the axis X1-X1 (or the direction AR1) and the direction AR2, the tunnel oven 44 comprises the following means for supporting and advancing the tubes T successive: it comprises retractable rollers 45 for supporting and advancing the tube T along arrows AR1 parallel to the axis X1-X1. For this advancement, at least a portion of the rollers 35 of the sleeve 34 and the rollers 45 of the oven 44 are motorized in a known manner and not shown. The rollers 45 are carried by vertical cylinders 47 intended to retract them below the raceways 48 of direction AR2. The raceways 48 which support the tubes T are perpendicular to the generatrices of each tube T entering the oven 44. To advance the successive tubes T in the tunnel oven 44 in the direction AR2 are provided two endless twin chains 49 carried by wheels 50 motorized in a manner not shown. Finally, the tunnel oven 44 includes a number of burners 46 (for example with gas) internally creating a heating atmosphere for maintaining the temperature of the tube T.

4°) Un extracteur du tube:4 °) A tube extractor:

il est disposé juste à la sortie du bac de fluidisation 9, mais à l'amont du dispositif de coupe K. Il est constitué par exemple par un tronçon de cheminée 33a à manchon de calorifugeage 34a (analogues à la cheminée 33 et au manchon 34) et il comporte sssentiellement des galets motorisés 35 d'entraînement du tube T vers le haut (figures 1, 3).it is arranged just at the outlet of the fluidization tank 9, but upstream of the cutting device K. It is constituted for example by a section of chimney 33a with insulation sleeve 34a (similar to the chimney 33 and to the sleeve 34 ) and it essentially comprises motorized rollers 35 for driving the tube T upwards (FIGS. 1, 3).

5°) Un dispositif de coupe du tube:5 °) A tube cutting device:

en aval du dispositif de fluidisation à bac 9 et de l'extracteur 33a est disposé un dispositif de coupe K connu en soi, représenté de manière symbolique par deux couteaux opposés. Le dispositif de coupe K est, par exemple, interposé entre l'extracteur 33a et la cheminée 33 (figures 1,3).downstream of the tank fluidization device 9 and of the extractor 33a is arranged a cutting device K known per se, represented symbolically by two opposite knives. The cutting device K is, for example, interposed between the extractor 33a and the chimney 33 (Figures 1,3).

FONCTIONNEMENT ET MISE EN OEUVRE DU TRAITEMENT THERMIQUE DE L'INVENTION (Fig. 1, 2 et 4).FUNCTIONING AND IMPLEMENTATION OF THE HEAT TREATMENT OF THE INVENTION (Fig. 1, 2 and 4).

Avant même d'introduire de la fonte liquide dans l'installation, pour amorcer la production d'un tube T, un mannequin ou faux tube (non représenté) constitué par un manchon tubulaire en acier de même diamètre extérieur et de même épaisseur que le tube T à obtenir est introduit par le haut de la filière 4-5, à travers le bac de fl uidisa- tion et de traitement thermique 9, jusqu'à un niveau inférieur à celui de l'extrémité supérieure de la chemise 4 en graphite. Puis de la fonte liquide est introduite suivant la flèche f dans l'entonnoir 2 de coulée jusqu'à un niveau N situé légèrement au-dessous de la partie supérieure de la chemise 4 de la filière 4-5. Cette fonte liquide a la composition suivante en poids: Carbone 2,5 à 4,0%, Silicium 2 à 4%, Manganèse 0,1 à 0,6%, Molybdène 0 à 0,5%, Nickel 0 à 3,5%, Cuivre 0 à 11 %, Magnésium 0 à 0,5%, Soufre 0,1% au maximum, Phosphore 0,06% au maximum, le reste étant du fer. Le bac 9, initialement vide de sable, avant l'introduction du mannequin est empli de sable en 15, dans la chambre de fluidisation, dès que le mannequin est immergé au-dessous du niveau N. En effet, le mannequin offre alors la paroi tubulaire interne qui manquait pour contenir une masse de sable 15 que l'on peut alors introduire. L'eau de refroidissement est admise à travers les conduits 6 et 7 pour l'enveloppe 5 et 17 et 18 pour les spires tubulaires 16.Before even introducing liquid cast iron into the installation, to initiate the production of a tube T, a dummy or false tube (not shown) consisting of a tubular steel sleeve of the same outside diameter and the same thickness as the tube T to be obtained is introduced from the top of the die 4-5, through the fluidization and heat treatment tank 9, to a level below that of the upper end of the graphite jacket 4 . Then liquid iron is introduced along the arrow f into the pouring funnel 2 to a level N located slightly below the upper part of the jacket 4 of the die 4-5. This liquid iron has the following composition by weight: Carbon 2.5 to 4.0%, Silicon 2 to 4%, Manganese 0.1 to 0.6%, Molybdenum 0 to 0.5%, Nickel 0 to 3.5 %, Copper 0 to 11%, Magnesium 0 to 0.5%, Sulfur 0.1% maximum, Phosphorus 0.06% maximum, the rest being iron. The tank 9, initially empty of sand, before the introduction of the manikin is filled with sand at 15, in the fluidization chamber, as soon as the manikin is submerged below the level N. In fact, the manikin then offers the wall internal tubular which was missing to contain a mass of sand 15 which can then be introduced. Cooling water is admitted through the conduits 6 and 7 for the casing 5 and 17 and 18 for the tubular turns 16.

Comme connu, la fonte se refroidit au contact de la chemise 4 suivant un front de solidification S de forme approximativement tronconique, et s'accroche au mannequin qui est tiré vers le haut par les galets motorisés 35 de la cheminée 33a, puis la cheminée 33 et entraîne, pas-à-pas, la partie de fonte solidifiée sous forme d'ume amorce de tube T.As known, the cast iron cools in contact with the jacket 4 along a solidification front S of approximately frustoconical shape, and hangs on the dummy which is pulled upwards by the motorized rollers 35 of the chimney 33a, then the chimney 33 and drives, step by step, the part of cast iron solidified in the form of a priming tube T.

Au plus tard, pendant que le mannequin traverse encore le bac 9 dans le sens de la flèche f1 de l'air ou de l'azote comprimé est admis par le conduit 13 dans la chambre 12 d'entrée de gaz de fluidisation. La masse de sable 15 est alors flui- disée tout autour des spires 16 qui sont noyées dans le bain de fluidisation 15, jusqu'à un niveau voisin du niveau supérieur du bac 9, donc sensiblement au-dessus du niveau de la masse de sable 15, avant fluidisation, lorsqu'elle est inerte. Lorsque c'est l'amorce de tube T qui remplace le mannequin à l'intérieur du bac de fluidisation 9, en montant suivant la flèche f1, le traitement thermique du tube T commence et se poursuit en continu au fur et à mesure de sa montée dans le sens de la flèche f1.At the latest, while the mannequin still crosses the tank 9 in the direction of the arrow f1, compressed air or nitrogen is admitted through the pipe 13 into the chamber 12 for the entry of fluidizing gas. The mass of sand 15 is then fluidized all around the turns 16 which are embedded in the fluidization bath 15, to a level close to the upper level of the tank 9, therefore substantially above the level of the mass of sand 15, before fluidization, when it is inert. When it is the primer of tube T which replaces the dummy inside the fluidization tank 9, while climbing according to arrow f1, the heat treatment of tube T begins and continues continuously as it is mounted in the direction of arrow f1.

Le traitement thermique de bainitisation du tube T est réalisé dans des conditions d'évolution de température illustrées à la Fig. 5 et décrites dans le brevet FR 2 522 291:

  • 1ère phase (abc) trempe de bainitisation.
The bainitization heat treatment of the tube T is carried out under conditions of temperature change illustrated in FIG. 5 and described in patent FR 2 522 291:
  • 1st phase (abc) bainitization quenching.

Sur la courbe de la Fig. 5, les températures (T °C) sont en ordonnées alors que les temps (t) sont en abscisses. La courbe a ... h de la Fig. 5 illustre l'évolution de la température d'un tube en fonte à graphite sphéroïdal dans le temps lorsqu'il subit le traitement thermique de l'invention.On the curve of Fig. 5, the temperatures (T ° C) are on the ordinate while the times (t) are on the abscissa. The curve a ... h of FIG. 5 illustrates the evolution of the temperature of a spheroidal graphite cast iron tube over time when it undergoes the heat treatment of the invention.

C'est dans le bac de fluidisation 9, où le bain de sable 15 fluidisé se trouve à une température réglée à la valeur nécessaire à l'obtention de la structure désirée (par exemple entre 100 et 200 °C pour une structure bainitique) que s'effectue la première phase du traitement thermique qui est une trempe de bainitisation, sans chauffage, en profitant des calories du tube sortant de la filière 4-5. Cette température du bain de sable 15 comprise entre 100 et 200°C est maintenue constante grâce à la circulation d'eau à une température de l'ordre de 20°C dans les conduits 17 et 18. Du débit d'air de fluidisation entrant par le conduit 13 et de la vitesse de circulation de l'eau dépend l'intensité du refroidissement du bain de sable 15. Le débit d'air de fluidisation et la vitesse de circulation d'eau sont réglables. On part donc d'un tube T qui vient d'être formé et solidifié et est encore à une température de 1100 °C au point a (sortie de la filière 4). Entre les points a et b (au niveau de la plaque poreuse 11, la température du tube T descend rapidement d'environ 1100°C à environ 850°C ou à une température légèrement supérieure. Aux points a et b la structure du tube T est austénitique.It is in the fluidization tank 9, where the fluidized sand bath 15 is at a temperature adjusted to the value necessary for obtaining the desired structure (for example between 100 and 200 ° C. for a bainitic structure) that the first phase of the heat treatment is carried out, which is a quenching of bainitization, without heating, taking advantage of the calories from the tube leaving the die 4-5. This temperature of the sand bath between 100 and 200 ° C is kept constant by virtue of the circulation of water at a temperature of the order of 20 ° C. in the conduits 17 and 18. The flow rate of fluidizing air entering through the conduit 13 and the speed of circulation of the water depends on the intensity of sand bath cooling 15. The fluidization air flow and the water circulation speed are adjustable. We therefore start from a tube T which has just been formed and solidified and is still at a temperature of 1100 ° C. at point a (outlet of the die 4). Between points a and b (at the porous plate 11, the temperature of the tube T drops rapidly from approximately 1100 ° C to approximately 850 ° C or a slightly higher temperature. At points a and b the structure of the tube T is austenitic.

Du point b (entrée dans le bain 15 de fluidisation) au point c (sortie du bain 15 de fluidisation), la chute de température du tube T est brutale (de 850°C à environ 500 °C) et s'effectue en un temps très court, pendant la traversée du bac de fluidisation 9 où le tube T est léché sur toute sa surface par le bain de sable fluidisé 15 maintenu par le serpentin 16 à une température de l'ordre de 100 à 200°C. C'est une trempe de bainitisation. Le bain fluidisé 15 effectue donc un véritable drainage intense de calories hors du tube T formé et ceci de manière uniforme sur toute la paroi du tube T immergé dans le bain de sable 15, de manière que chaque point du tube T subisse le même traitement thermique.From point b (entering the fluidization bath 15) to point c (leaving the fluidization bath 15), the temperature drop of the tube T is abrupt (from 850 ° C to about 500 ° C) and takes place in a very short time, during the crossing of the fluidization tank 9 where the tube T is licked over its entire surface by the fluidized sand bath 15 maintained by the coil 16 at a temperature of the order of 100 to 200 ° C. It is a hardening of bainitization. The fluidized bath 15 therefore performs a true intense drainage of calories out of the tube T formed and this uniformly over the entire wall of the tube T immersed in the sand bath 15, so that each point of the tube T undergoes the same heat treatment .

2°) Phase intermédiaire cde de sortie du bac 9 et de traversée de l'extracteur 33a et de la cheminée 33.2) Intermediate phase of exit from tank 9 and crossing of extractor 33a and chimney 33.

A peine sorti du bac de fluidisation 9 le tube T entre dans l'extracteur 33a qui tout en le protégeant contre le refroidissement, l'entraîne par ses rouleaux motorisés 35 vers la cheminée 33 de refroidissement naturel et lent qui se trouve dans la position d'axe vertical, à travers le dispositif de coupe K. Sur la courbe .des températures de la Fig. 5, l'entrée dans la cheminée 33 correspond au point d. Donc l'intervalle de traversée de l'extracteur 33a entre le bac 9 et la cheminée 33, où se situe le dispositif de coupe ou de tronçonnage K correspond au tronçon de courbe c d, avec une légère baisse de température de la paroi extérieure du tube T: le point d est à une température proche de 480°C. Le refroidissement du tube T dans cette cheminée 33 est lent en raison du manchon de calorifugeage 34 de la cheminée 33. A la sortie de la cheminée 33, au point e, le tube T est à une température de l'ordre de 350°C.As soon as it leaves the fluidization tank 9, the tube T enters the extractor 33a which, while protecting it against cooling, drives it by its motorized rollers 35 to the chimney 33 of natural and slow cooling which is in the position d vertical axis, through the cutting device K. On the temperature curve of FIG. 5, the entry into the chimney 33 corresponds to point d. So the interval of passage of the extractor 33a between the tank 9 and the chimney 33, where the cutting or cutting-off device K is located corresponds to the section of curve cd, with a slight drop in temperature of the outside wall of the tube T: point d is at a temperature close to 480 ° C. The cooling of the tube T in this chimney 33 is slow due to the heat-insulating sleeve 34 of the chimney 33. At the exit of the chimney 33, at point e, the tube T is at a temperature of the order of 350 ° C. .

Le tronçonnage du tube T est réalisé au moyen du dispositif de coupe K, quand la longueur voulue de tube T est à l'intérieur de la cheminée 33.The cutting of the tube T is carried out by means of the cutting device K, when the desired length of tube T is inside the chimney 33.

3°) Seconde phase de traitement thermique - maintien en température (zone comprise entre les tronçons e1f1 et e2f2 de la courbe de la Fig. 5):3 °) Second heat treatment phase - temperature maintenance (area between sections e1f1 and e2f2 of the curve in Fig. 5):

pour consolider ou fixer la structure bainitique précédemment obtenue, on transporte le tube T tronçonné à l'intérieur du four-tunnel 44 en le déplaçant suivant une direction AR1 parallèle à l'axe horizontal X1-X1 de la cheminée 33 basculée. Pour ce faire, (Fig. 2 et 3) après tronçonnage du tube T à longueur voulue par le dispositif K, le vérin 40 est actionné de manière à faire basculer la cheminée 33 et le tube T qu'elle contient et supporte, d'un angle de 90° dans le sens de la flèche AR autour de l'axe YY du tourillon 37. La cheminée 33 bascule jusqu'à fin de course de tige 39 du vérin 40 (portion en trait mixte à la Fig. 3). Elle passe ainsi delà position d'axe vertical XX à la position d'axe horizontal X1-X1 dans le prolongement et au voisinage de l'entrée 42 du four-tunnel 44. Le tube T, supporté par les galets 35 au cours de ce basculement ainsi que dans la nouvelle position X1-X1 se trouve ainsi prêt à entrer dans le four-tunnel 44. Les galets motorisés 35 puis les rouleaux motorisés 45 entraînés en rotation font entrer le tube T dans le four-tunnel 44. A l'intérieur du four 44, le tube T, tout en continuant sa progression horizontale, subit un changement de direction à 90° vers la nouvelle direction AR2 qui le mène jusqu'à la sortie 43 du four 44. Ce changement de direction s'effectue de la manière suivante: les vérins 47 escamotent les rouleaux 45 du dessous des cheminées de roulement 48 de sorte que le tube T est déposé sur les cheminées 48 et les chaînes sans fin motrices 49 qui l'entraînent dans la nouvelle direction AR2 jusqu'à la sortie 43 du four. Le four-tunnel 44 est chauffé par les brûleurs à gaz 46 à une température telle que le tube T avançant le long du four-tunnel 44 à une vitesse réglable (par réglage de vitesse d'entraînement des chaînes motrices 49) soit maintenu à une température constante isotherme comprise entre deux limites (deux isothermes): d'une part une limite supérieure (tronçon e1f1 ou isotherme de 450°C de la Fig. 5) et d'autre part une limite inférieure (tronçon e2f2 ou isotherme de 250°C). Entre les limites e1f1 et e2f2, le maintien en température du tube T s'effectue suivant un tronçon intermédiaire ou isotherme e f, compris entre 250 °C et 450 °C, (Fig. 5), c'est dans la cheminée 33 que le tube T passe de la température d (entrée de la cheminée 33) à la température e (sortie de la cheminée 33 et entrée dans le four 44) comprise entre les températures e1 et e2, respectivement de 450°C et 250 °C. Cette phase de traitement thermique en four de maintien 44 assure la stabilité de la bainite et éventuellement de l'austénite résiduelle dans la matrice de la structure. C'est le maintien de bainitisation qui assure une structure bainitique ou austénitique bainitique homogène. Au-delà des points f1 ou f2, le tube T est refroidi comme décrit plus loin au paragraphe 4°).to consolidate or fix the bainitic structure previously obtained, the cut T tube is transported inside the tunnel oven 44 by moving it in a direction AR1 parallel to the horizontal axis X1-X1 of the tilted chimney 33. To do this (Fig. 2 and 3) after cutting the tube T to the desired length by the device K, the jack 40 is actuated so as to tilt the chimney 33 and the tube T which it contains and supports, an angle of 90 ° in the direction of the arrow AR around the axis YY of the pin 37. The chimney 33 rocks until the end of the rod 39 stroke of the jack 40 (portion in phantom in Fig. 3). It thus passes beyond the vertical axis position XX to the horizontal axis position X1-X1 in the extension and in the vicinity of the inlet 42 of the tunnel oven 44. The tube T, supported by the rollers 35 during this tilting as well as in the new position X1-X1 is thus ready to enter the tunnel oven 44. The motorized rollers 35 then the motorized rollers 45 driven in rotation cause the tube T to enter the tunnel oven 44. At the inside the oven 44, the tube T, while continuing its horizontal progression, undergoes a change of direction at 90 ° towards the new direction AR2 which leads it to the exit 43 of the oven 44. This change of direction is effected by as follows: the cylinders 47 retract the rollers 45 from below the rolling chimneys 48 so that the tube T is deposited on the chimneys 48 and the endless drive chains 49 which drive it in the new direction AR2 to the outlet 43 from the oven. The tunnel oven 44 is heated by the gas burners 46 to a temperature such that the tube T advancing along the tunnel oven 44 at an adjustable speed (by adjusting the drive speed of the drive chains 49) is maintained at a constant isothermal temperature between two limits (two isotherms): on the one hand an upper limit (section e1f1 or isotherm of 450 ° C in Fig. 5) and on the other hand a lower limit (section e2f2 or isotherm of 250 ° VS). Between the limits e1f1 and e2f2, the temperature maintenance of the tube T takes place along an intermediate or isothermal section ef, between 250 ° C and 450 ° C, (Fig. 5), it is in the chimney 33 that the tube T passes from the temperature d (entry of the chimney 33) to the temperature e (exit of the chimney 33 and entry into the oven 44) comprised between the temperatures e1 and e2, respectively 450 ° C and 250 ° C. This heat treatment phase in the holding oven 44 ensures the stability of the bainite and possibly of the residual austenite in the matrix of the structure. Maintaining bainitization ensures a homogeneous bainitic or austenitic bainitic structure. Beyond the points f1 or f2, the tube T is cooled as described below in paragraph 4).

Le tube T sort du four-tunnel 44 à une température comprise entre 450°C et 250°C entre les points f2 et f1 pour être refroidi en troisième et dernière phase comme décrit plus loin au paragraphe 4°). C'est donc à l'intérieur de la zone hachurée de la Fig. 5 comprise entre les tronçons e1f1 et e2f2 (tronçon e f en trait interrompu) que se situe le maintien à température constante du tube T. La structure bainitique ou éventuellement bainitique-austénitique est homogène et offre les caractéristiques mécaniques optimales indiquées au brevet FR-A 2 522 291.The tube T leaves the tunnel oven 44 at a temperature between 450 ° C and 250 ° C between the points f2 and f1 to be cooled in the third and last phase as described below in paragraph 4). It is therefore inside the hatched area of FIG. 5 between the sections e1f1 and e2f2 (section ef in broken lines) that is the maintenance at constant temperature of the tube T. The bainitic or possibly bainitic-austenitic structure is homogeneous and offers the optimal mechanical characteristics indicated in patent FR-A 2 522,291.

4°) Troisième et dernière phase de refroidissement à l'air libre: (tronçon f1 gh ou f2 gh):4 °) Third and last phase of cooling in the open air: (section f1 gh or f2 gh):

à la sortie du four tunnel 44, le tube T se refroidit à l'air libre jusqu'à la température ordinaire, par exemple comprise entre 5 et 25 °C, suivant le tronçon flg, en peu de temps et, conserve finalement cette température qui est celle de l'air extérieur (tronçon gh). Le tube T en fonte à graphite sphéroïdal possède alors une structure bainitique ou une structure mixte bainite-austénite.at the outlet of the tunnel oven 44, the tube T cools in the open air to ordinary temperature, for example between 5 and 25 ° C, depending on the section flg, in a short time and, finally retains this temperature which is that of the outside air (gh section). The T-tube in spheroidal graphite cast iron then has a bainitic structure or a mixed bainite-austenite structure.

On peut former et traiter thermiquement ainsi des tubes en fonte, de préférence des tubes d'adduction d'eau, de diamètres nominaux de 600 à 2500 mm et plus particulièrement de 1000 à 1600 mm avec des épaisseurs comprises entre 5 et 20 mm. Ce procédé et cette installation sont donc particulièrement avantageux pour la fabrication de tubes en fonte T de grands diamètres et d'épaisseur relativement faible.Cast iron tubes, preferably water supply tubes, with nominal diameters of 600 to 2,500 mm and more particularly from 1,000 to 1,600 mm can be formed and heat treated with thicknesses of between 5 and 20 mm. This method and this installation are therefore particularly advantageous for the manufacture of T-shaped tubes of large diameters and of relatively small thickness.

AVANTAGESBENEFITS

La première phase de trempe débute au point b de la courbe de Fig. 2 en profitant de la chaleur du tube T sans apport de calories, pour amener le tube T à la température de 800-850 °C environ.The first quenching phase begins at point b of the curve in FIG. 2 by taking advantage of the heat of the tube T without adding calories, to bring the tube T to the temperature of 800-850 ° C. approximately.

Grâce à la combinaison «filière 4-5 + bac 9» on obtient une aptitude à la trempe du tube T de fonte à graphite sphéroïdal beaucoup plus élevée que l'aptitude à la trempe d'un tube en fonte à graphite sphéroïdal T que l'on aurait laissé se refroidir puis que l'on aurait réchauffé jusqu'à une température de 800 à 850°C pour réaliser une trempe bainitique.Thanks to the combination “die 4-5 + tank 9”, the quenching ability of the spheroidal graphite cast iron tube T is much higher than the quenching ability of a spheroidal graphite cast iron tube T than l 'We would have allowed to cool and then we would have reheated to a temperature of 800 to 850 ° C to carry out bainitic quenching.

L'utilisation du bac 9 à bain de sable fluidisé 15 assure l'uniformité de température du tube T sur toute sa longueur et sur toute sa paroi cylindrique et assure la fidélité, la reproductibilité du traitement thermique.The use of the tank 9 in a fluidized sand bath 15 ensures the temperature uniformity of the tube T over its entire length and over its entire cylindrical wall and ensures the fidelity, the reproducibility of the heat treatment.

En outre, l'utilisation du bain de sable fluidisé 15, ou de tout autres particules convenables d'un matériau solide comme moyen d'évacuation ou de drainage des calories du tube T vers l'extérieur, au lieu d'eau de refroidissement, est une sécurité en raison de la proximité du bain de fonte F.In addition, the use of the fluidized sand bath 15, or any other suitable particles of a solid material as a means of evacuating or draining the calories from the tube T towards the outside, instead of cooling water, is a safety due to the proximity of the cast iron bath F.

Comme on l'a vu au préambule, grâce à la succession immédiate ou à l'enchaînement de la filière (4-5) et du bac 9, c'est-à-dire grâce à la combinaison de la filière 4-5 et du bac 9 de fluidisation, permettant la trempe de bainitisation (tronçon b c de la Fig. 5) immédiatement à la naissance du tube T, c'est-à-dire à la sortie de la filière 4-5, on obtient une aptitude à la trempe beaucoup plus élevée que l'aptitude à la trempe d'un tube que l'on aurait laissé se refroidir jusqu'à une température inférieure à celle de l'eutectoïde (700 à 750°C), puis que l'on aurait réchauffé jusqu'à une température de 850°C pour réaliser ensuite une trempe bainitique. L'invention permet donc d'obtenir avec certitude la structure bainitique désirée.As we saw in the preamble, thanks to the immediate succession or to the chain of the chain (4-5) and the tank 9, that is to say thanks to the combination of the chain 4-5 and of the fluidization tank 9, allowing the bainitisation quenching (section bc of FIG. 5) immediately at the birth of the tube T, that is to say at the outlet of the die 4-5, an aptitude is obtained for the quenching is much higher than the quenchability of a tube that would have been allowed to cool to a temperature lower than that of the eutectoid (700 to 750 ° C), then that we would have reheated to a temperature of 850 ° C to then carry out bainitic quenching. The invention therefore makes it possible to obtain with certainty the desired bainitic structure.

Comme on le verra plus loin, elle permet également d'obtenir avec certitude d'autres structures dépendant de la température du bain de sable fluidisé 15. En raison de la facilité de réglage de température du bain fluidisé 15 (par réglage de la température et du débit d'eau circulant dans le serpentin 16) et en raison de l'uniformité de température du tube T par le bain de sable fluidisé 15, sur toute la longueur du tube T, ce traitement thermique est parfaitement fidèle et reproductible industriellement.As will be seen below, it also makes it possible to obtain with certainty other structures dependent on the temperature of the fluidized sand bath 15. Because of the ease of adjusting the temperature of the fluidized bath 15 (by adjusting the temperature and of the water flow circulating in the coil 16) and due to the temperature uniformity of the tube T through the fluidized sand bath 15, over the entire length of the tube T, this heat treatment is perfectly faithful and reproducible industrially.

VARIANTESVARIANTS

Suivant l'exemple d'exécution de la Fig. 6, le procédé et l'installation de traitement thermique de l'invention sont appliqués à une coulée verticale continue descendante d'un tube en fonte T.According to the embodiment of FIG. 6, the process and the installation for thermal treatment of the invention are applied to a continuous vertical downward casting of a cast iron tube T.

Une telle installation, du type décrit dans le brevet FR-A 2 415 501 est réalisée autour d'un axe XX de coulée continue. Elle comporte:

  • - une alimentation en fonte liquide
  • - des moyens de formage d'un tube en fonte
  • - une installation de traitement thermique du tube en fonte.
Such an installation, of the type described in patent FR-A 2 415 501 is produced around an axis XX of continuous casting. It involves:
  • - liquid iron supply
  • - means for forming a cast iron tube
  • - an installation for heat treatment of the cast iron tube.

1°) une alimentation en fonte liquide (partiellement représentée):1 °) a supply of liquid iron (partially shown):

un bassin de coulée 19 à la partie supérieure de l'installation appartient à une poche de coulée sous basse pression, non représentée, ou éventuellement à un four électrique réverbère, dont la capacité est soumise à la pression d'un gaz neutre tels que l'azote ou l'argon. Le bassin de coulée 19 comporte à sa partie inférieure un orifice de coulée 20 d'axe XX.a pouring basin 19 at the upper part of the installation belongs to a low pressure casting ladle, not shown, or possibly to a reverberatory electric furnace, the capacity of which is subjected to the pressure of a neutral gas such as l 'nitrogen or argon. The pouring basin 19 has at its lower part a pouring orifice 20 of axis XX.

2°) Moyens de formage d'un tube en fonte:2) Means for forming a cast iron tube:

l'orifice de coulée 20 est traversé axialement par un noyau 21 en graphite qui donne la forme intérieure du tube T à obtenir et par la tête 22 d'une filière 23 également en graphite donnant la forme extérieure du tube T à obtenir. Le noyau 21 est un cylindre creux contenant intérieurement un dispositif de chauffage, par exemple un inducteur 24 en forme de serpentin refroidi par eau. La filière 23 ménage avec le noyau 21 un espace annulaire 25 correspondant aux dimensions intérieures et extérieures du tube T à obtenir, espace à l'intérieur duquel la fonte F doit se solidifier progressivement suivant un front de solidification à partir de la paroi de la filière 23. La tête de filière 22 ménage avec l'orifice de coulée 20 un espace annulaire comblé par un manchon réfractaire isolant 26, le manchon 26 étant destiné à faire obstacle à d'éventuels flux de refroidissement de la fonte liquide sortant du bassin 19. La filière tubulaire 23 dont la partie inférieure est située à la même hauteur que la partie inférieure du noyau 21, est entourée avec jeu annulaire par une chemise tubulaire 27 en métal ou alliage métallique bon conducteur de la chaleur tel que le cuivre, qui s'évase en bassin 28 à sa partie supérieure et qui sert de récipient à une enveloppe 29 de métal liquide à bas point de fusion (plomb ou étain par exemple) en contact intime avec la filière 23 sur toute la hauteur de celle-ci à l'exception de la tête 22. L'enveloppe de métal liquide 29 à bas point de fusion est alimentée soit par le haut par un conduit 30, soit par le bas par un conduit 31 qui sert également à l'évacuation du métal liquide de refroidissement 29 lorsque c'est nécessaire. La chemise 27 est elle-même enveloppée étroitement par un manchon creux 32 de refroidissement à circulation d'eau, dont la paroi interne est en contact avec la paroi externe de la chemise 27.the pouring orifice 20 is crossed axially by a graphite core 21 which gives the internal shape of the tube T to be obtained and by the head 22 of a die 23 also in graphite giving the external shape of the tube T to be obtained. The core 21 is a hollow cylinder internally containing a heating device, for example an inductor 24 in the form of a water-cooled coil. The die 23 provides with the core 21 an annular space 25 corresponding to the internal and external dimensions of the tube T to be obtained, the space inside which the cast iron F must gradually solidify along a solidification front from the wall of the die 23. The die head 22 provides, with the pouring orifice 20, an annular space filled with an insulating refractory sleeve 26, the sleeve 26 being intended to obstruct possible cooling flows of the liquid iron leaving the basin 19. The tubular die 23, the lower part of which is situated at the same height as the lower part of the core 21, is surrounded with annular clearance by a tubular jacket 27 of metal or metal alloy which is a good conductor of heat such as copper, which flares in a basin 28 at its upper part and which serves as a container for an envelope 29 of liquid metal with a low melting point (lead or tin for example) in intimate contact with the die 23 over the entire height thereof with the exception of the head 22. The liquid metal casing 29 with a low melting point is supplied either from above by a conduit 30, or from below by a conduit 31 which is also used for the evacuation of liquid metal from re cold when necessary. The jacket 27 is itself tightly wrapped by a hollow water-cooling cooling sleeve 32, the internal wall of which is in contact with the external wall of the jacket 27.

Comme connu, c'est juste à la sortie de l'espace annulaire 25 entre le noyau 21 et la filière 23 qu'un tube T est formé, solidifié complètement.As known, it is just at the exit of the annular space 25 between the core 21 and the die 23 that a tube T is formed, completely solidified.

3°) Installation de traitement thermique:3 °) Installation of heat treatment:

Au-dessous de la filière 23, dans l'axe XX de celle-ci, et à une distance appropriée de la partie inférieure de la filière 23, est monté un bac de fluidisation à fond annulaire présentant une ouverture 10 pour le passage du tube T et à plaque poreuse annulaire 11 présentant également une ouverture pour le passage du tube T. Le bac 9 contient au-dessus de la plaque poreuse 11 un bain de sable fluidisé 15 refroidi par un serpentin tubulaire hélicoïdal à spires 16 refroidies par eau. Le bac de fluidisation 9 reçoit le tube T traité thermiquement par sa partie supérieure au lieu de le recevoir par son ouverture 10 comme dans l'exemple précédent. Cependant, l'évolution de température du tube T s'effectue avant et pendant la traversée du bac 9 de fluidisation suivant la même courbe passant par les points a, b, c de la Fig. 5 (traitement de trempe de bainitisation). Un extracteur 33b à enveloppe de calorifugeage 34b et à rouleaux motorisés 35 d'entraînement puis une cheminée 33 à manchon de calorifugeage 34 font suite au bac 9 et précèdent un four-tunnel de maintien à brûleurs à gaz, non représenté, mais qui n'est autre que le four 44 des Fig. 2 et 4. Entre l'extracteur 33b et la cheminée 33 est interposé un dispositif de coupe K du tube T. Comme aux Fig. 1 à 3, la cheminée comporte à sa partie inférieure une oreille 36 et un tourillon 37 d'axe YY de basculement ainsi qu'une oreille 38 et des moyens de basculement d'un angle de 90° qui ne sont pas représentés.Below the die 23, in the axis XX thereof, and at an appropriate distance from the lower part of the die 23, is mounted an annular bottom fluidization tank having an opening 10 for the passage of the tube T and an annular porous plate 11 also having an opening for the passage of the tube T. The tank 9 contains above the porous plate 11 a fluidized sand bath 15 cooled by a helical tubular coil with turns 16 cooled by water. The fluidization tank 9 receives the tube T heat treated by its upper part instead of receiving it through its opening 10 as in the previous example. However, the temperature evolution of the tube T takes place before and during the crossing of the fluidization tank 9 according to the same curve passing through the points a, b, c of FIG. 5 (bainitization quenching treatment). An extractor 33b with a heat-insulating envelope 34b and with motorized rollers 35 for driving then a chimney 33 with a heat-insulating sleeve 34 follow the tank 9 and precede a gas-burner holding tunnel tunnel, not shown, but which does not is other than the oven 44 of Figs. 2 and 4. Between the extractor 33b and the chimney 33 is interposed a device K for cutting the tube T. As in FIGS. 1 to 3, the chimney comprises at its lower part an ear 36 and a pin 37 of YY tilting axis as well as an ear 38 and tilting means of an angle of 90 ° which are not shown.

Le traitement thermique complet suivant l'invention a lieu dans les mêmes conditions que dans l'exemple des Fig. 1, 2, 3, 4 et 5 suivant les trois phases illustrées à la Fig. 5, c'est-à-dire la phase de trempe d'austénitisation-bainitisation d'abord suivant le tronçon a, b entre la filière 23 et le bac de fluidisation 9, ensuite suivant le tronçon b, c de chute brutale de température pour la bainitisation à travers le bac 9 de fluidisation et enfin, après la coupe du tube T, suivant un tronçon ef horizontal (ou isotherme ef) situé dans la zone hachurée comprise entre l'isotherme supérieure e1f1 (de 450°C) et l'isotherme inférieure e2f2 (250°C) se produit une stabilisation de température à l'intérieur du four-tunnel de maintien 44. Le traitement thermique s'achève par la phase finale f1 ou f2, g, h de refroidissement à l'air libre du tube T sorti du four 44 de maintien de bainitisation.The complete heat treatment according to the invention takes place under the same conditions as in the example of FIGS. 1, 2, 3, 4 and 5 according to the three phases illustrated in FIG. 5, that is to say the austenitization-bainitization quenching phase first along the section a, b between the die 23 and the fluidization tank 9, then along the section b, c of sudden drop in temperature for bainitization through the fluidization tank 9 and finally, after the tube T has been cut, along a horizontal section ef (or isothermal ef) located in the hatched zone between the upper isotherm e1f1 (450 ° C.) and l 'lower isotherm e2f2 (250 ° C) occurs a temperature stabilization inside the holding tunnel oven 44. The heat treatment ends with the final phase f1 or f2, g, h of air cooling free from the tube T taken out of the bainitization maintenance oven 44.

Les avantages sont les mêmes que précédemment en ce qui concerne le traitement thermique, la seule différence avec l'exemple précédent résidant dans le mode de fabrication du tube T en utilisant le noyau 21, et en faisant progresser le tube T vers le bas suivant la flèche f2. Obtention d'une structure autre que bainitique:The advantages are the same as previously with regard to the heat treatment, the only difference with the previous example residing in the method of manufacturing the tube T using the core 21, and advancing the tube T downwards according to the arrow f2. Obtaining a structure other than bainitic:

Si l'on veut obtenir une structure autre que bainitique, par exemple une structure de bainite + perlite ou de ferrite + perlite à pourcentage de perlite parfaitement contrôlé, alors que les traitements thermiques antérieurs ne permettaient pas de reproduire le pourcentage de perlite d'un traitement à l'autre, ni même d'une extrémité de tube à l'autre, le traitement de l'invention le permet, de manière fidèle et industriellement reproductible. Dans le cas de la structure ferrite + perlite, la cheminée 33 est supprimée.If we want to obtain a structure other than bainitic, for example a bainite + perlite or ferrite + perlite structure with a perfectly controlled percentage of perlite, whereas previous heat treatments did not make it possible to reproduce the percentage of perlite of a treatment at the other, or even from one end of the tube to the other, the treatment of the invention allows it, faithfully and industrially reproducible. In the case of the ferrite + perlite structure, the chimney 33 is eliminated.

De même, le traitement de l'invention permet de reproduire une structure de bainite + ferrite.Similarly, the treatment of the invention makes it possible to reproduce a bainite + ferrite structure.

Pour une structure de bainite + ferrite, la température du bain fluidisé 15 doit être comprise entre 100 et200°C comme pour la bainite seule.For a bainite + ferrite structure, the temperature of the fluidized bath 15 must be between 100 and 200 ° C. as for the bainite alone.

Pour une structure de ferrite + perlite à pourcentages déterminés de chacune des phases ferrite et perlite, la température du bain fluidisé 15 doit être telle que la vitesse de refroidissement du tube T traversant ce bain 15 soit constante. En d'autres termes la vitesse de refroidissement constante du tube T à travers une bande triphasée atpha+gamma + graphite représentée en hachures au diagramme thermique de la Fig. 7 (la bande a + y + G est ainsi appelée parce qu'elle illustre le domaine de transformation eutectoïde de la fonte où coexistent les trois phases ferrite, austénite et graphite du diagramme ternaire «fer, carbone, silicium») donne naissance aux proportions choisies de ferrite et de perlite.For a ferrite + perlite structure with predetermined percentages of each of the ferrite and perlite phases, the temperature of the fluidized bath 15 must be such that the cooling rate of the tube T passing through this bath 15 is constant. In other words, the constant cooling rate of the tube T through a three-phase band atpha + gamma + graphite shown in hatching in the thermal diagram of FIG. 7 (the band a + y + G is so called because it illustrates the eutectoid transformation domain of cast iron where the three phases ferrite, austenite and graphite coexist from the ternary diagram "iron, carbon, silicon") gives rise to the proportions selected ferrite and perlite.

La vitesse constante et réglable de passage du tube T à travers le bain fluidisé 15 engendre une vitesse de refroidissement constante à travers la bande triphasée (a + y + G) et garantit donc une proportion constante et préalablement choisie de chacune des phases: ferrite et perlite. L'intensité du refroidissement peut être réglée comme dans le cas de la trempe bainitique par le choix du débit d'air de fluidisation (conduit 13) et le choix de la vitesse de circulation d'eau dans le serpentin 16. Si l'on veut diminuer l'intensité du refroidissement, on peut supprimer toute circulation d'eau dans le serpentin 16, ou même remplacer le serpentin 16 par un moyen de chauffage. Ce moyen de chauffage peut être par exemple une résistance électrique chauffante noyée dans le bain fluidisé 15 ou enveloppant le bac métallique 9 ou encore disposée de manière à chauffer l'air de fluidisation (conduit 13). Comme moyen de chauffage, on peut également employer des brûleurs à gaz.The constant and adjustable speed of passage of the tube T through the fluidized bath 15 generates a constant cooling speed through the three-phase strip (a + y + G) and therefore guarantees a constant and previously chosen proportion of each of the phases: ferrite and perlite. The intensity of the cooling can be adjusted as in the case of bainitic quenching by the choice of the fluidization air flow (conduit 13) and the choice of the speed of circulation of water in the coil 16. If one wants to decrease the intensity of the cooling, one can suppress any circulation of water in the coil 16, or even replace the coil 16 by a heating means. This heating means can be, for example, an electric heating resistor embedded in the fluidized bath 15 or enveloping the metal tank 9 or also arranged so as to heat the fluidizing air (conduit 13). As a heating medium, gas burners can also be used.

Pour obtenir cette structure de ferrite + perlite, on procède suivant le diagramme «température, temps» de la Fig. 7.To obtain this ferrite + perlite structure, we proceed according to the "temperature, time" diagram in FIG. 7.

Première phase (abc)First phase (abc)

Sur ce diagramme, le point a correspond à la naissance du tube T hors de la filière 4-5. Il est le même que dans le premier exemple (Fig. 5): la température est de 1100°C. A l'entrée du bain fluidisé, la température du tube T est de 850°C au point b, comme à la Fig. 5. A la sortie du bain fluidisé, au point c, la température du tube T est descendue à une valeur supérieure à 600 °C. Il est à noter que la baisse de température suivant le diagramme de la Fig. 7 entre les points b et c est beaucoup moins brutale et beaucoup plus progressive que dans le traitement suivant le diagramme de la Fig. 5.On this diagram, point a corresponds to the birth of the tube T outside of the die 4-5. It is the same as in the first example (Fig. 5): the temperature is 1100 ° C. At the inlet of the fluidized bath, the temperature of the tube T is 850 ° C. at point b, as in FIG. 5. At the outlet of the fluidized bath, at point c, the temperature of the tube T is lowered to a value greater than 600 ° C. It should be noted that the drop in temperature according to the diagram in FIG. 7 between points b and c is much less brutal and much more progressive than in the treatment according to the diagram in FIG. 5.

Entre les points b et c se situe la bande triphasée (a + y + G) (zone de transformation eutectoïde de la fonte) dans un intervalle de températures comprises entre 770 et 810 °C où la vitesse de refroidissement du tube T est constante. La bande (a + y + G) est hachurée.Between points b and c is located the three-phase strip (a + y + G) (eutectoid transformation zone of the cast iron) in a temperature range between 770 and 810 ° C where the cooling rate of the tube T is constant. The strip (a + y + G) is hatched.

Deuxième et dernière phase (ck).Second and last phase (ck).

Débouchant à l'air libre à la sortie du bain fluidisé 15 et n'ayant plus de cheminée 33 à traverser, le tube T subit un refroidissement naturel à l'air libre illustré par le tronçon de courbe ck.Opening into the open air at the outlet of the fluidized bath 15 and no longer having a chimney 33 to pass through, the tube T undergoes natural cooling in the open air illustrated by the section of curve ck.

Le traitement thermique en continu de l'invention permet un réglage précis du taux de chaque phase en présence (phase ferrite et phase perlite) du fait de la constance des paramètres suivants:

  • - vitesse d'extraction du tube T,
  • - vitesse de refroidissement du même tube,
  • - températures en tous les points de l'installation qui sont compris entre les points a (naissance du tube T hors de la filière 4-5) et c (sortie du tube T du bain fluidisé 15).
The continuous heat treatment of the invention allows precise adjustment of the rate of each phase present (ferrite phase and perlite phase) due to the consistency of the following parameters:
  • - tube T extraction speed,
  • - cooling rate of the same tube,
  • - temperatures at all points of the installation which are between points a (birth of tube T outside the die 4-5) and c (exit of tube T from the fluidized bath 15).

Claims (12)

1. Method for the continuous manufacture of pipes from spheroidal graphite cast-iron having a homogeneous and controlled structure chosen from structures containing bainite, bainite and ferrite or ferrite and perlite, of the type in which a tube is formed by a continuous casting method inside a cooled tubular die, from a cast-iron having the following composition by weight: carbon 2.5 to 4%, silicon 2 to 4%, manganese 0.1 to 0.6%, molybdenum 0 to 0.5%, nickel 0 to 3.5%, copper 0 to 11%, magnesium 0 to 0.5%, sulphur 0.01% maximum, phosphorous 0.06% maximum, the remainder being iron, this method being characterised in that, at the outlet of the cooled tubular die (4-5) the tube (T) which has just been produced is made to pass through a fluidized bath (15) of refractory particles cooled to a temperature substantially lower than that of the tube (T) as it emerges from the outlet of the cooled tubular die (4-5).
2. Method according to Claim 1, characterised in that in a first phase (a, b, c) one starts with a tube (T) emerging at the outlet of the die (4-5) at a temperature of the order of 1100°C and having an austenitic structure, the tube is left to cool to a temperature of the order of 850 °C (b) then the tube (T) is cooled forcefully and uniformly over its entire length by causing it to pass through a fluidized bath (15) of solid refractory particles in order to bring it rapidly to a temperature of approximately 500°C (c) (bainitisation tempering) in order to acquire a bainitic structure, then during an intermediate phase of slow cooling from 500°C to a value comprised between 250 °C and 450 °C (c, d, e), the tube is cut to a predetermined length, then, in a second phase (ef), so called maintaining bainitisation, the cut tube (T) is made to pass through a tunnel furnace for maintaining the tube (T) at an isothermal constant temperature (ef) comprised between the isothermal limits (e1f1) (450°C) and (e2f2) (250°C) in order to obtain a homogeneous bainitic or austenitic-bainitic structure, finally, in a last phase (f1 or f2 g h), the tube is left to cool in the atmosphere.
3. Method according to Claim 1, characterised in that, a temperature comprised between 100 °C and 200°C is maintained in the fluidized bath and at the end of this process one obtains a tube (T) having a structure at least partly of bainite.
4. Method according to Claim 1, characterised in that, in order to obtain a tube (T) having a structure of ferrite + perlite, in a first phase (a b c) one starts with a tube (T) emerging at the outlet of the die (4-5) at a temperature of the order of 1100°C (a), the tube (T) is left to cool to a temperature of the order of 850°C (b) then, between (b) and (c), the tube (T) is cooled uniformly and at a constant cooling speed over its entire length to a temperature greater than 600°C (c) by making it pass through a fluidized bath (15) of solid refractory particles, then, in a second and last phase (c k) the tube (T) is left to cool naturally in the atmosphere.
5. Method according to Claims 1 and 4, characterised in that, in order to obtain a structure of ferrite + perlite with pre-determined percentages of the ferrite and perlite phases, a temperature is maintained in the fluidized bath such that passing through the field of eutectoid transformation of the cast-iron (i.e. a so called "three-phase" band (a + y + G) where three phases, namely ferrite, austenite and graphite of the ternary diagram "iron, carbon, silicon" co-exist) takes place at a constant cooling speed.
6. Installation for carrying out the method of Claim 1, of the type comprising means for the supply of molten cast-iron and means having a cooled tubular die (4-5-21-23) for producing a tube (T) by a continuous method, characterised in that it comprises downstream of the cooled continuous casting die (4-5-21-23) a fluidization vat (9) of solid refractory particles, the said vat (9) being provided with a tubular coil (16) having a circulation of water which is embedded in the fluidized bath (15) and the said vat comprising at least one inlet or outlet orifice (10) for the tube (T) which has to pass through the fluidized bath (15) of the said particles in the vat (9).
7. Installation according to Claim 1, characterised in that in the case where the cooled tubular die (4-5-21-23) is on the vertical axis (X-X), the fluidization vat (9) comprises a single opening (10) on a vertical axis at its lower end and is open to the atmosphere at its upper end.
8. Installation according to Claim 7, characterised in that in the case where the cooled tubular die on a vertical axis (X-X) (4-5) is supplied with molten cast-iron from the bottom, the fluidization vat (9) is located above the cooled die (4-5) and the single opening (10) of the vat (9) is an inlet opening for the tube (T).
9. Installation according to Claim 6, characterised in that in the.case where the tubular die (23) on the vertical axis (X-X) is supplied with molten cast-iron from the top and is combined with a core (21), the fluidization vat (9) is located below the cooled die (29) and the single opening of the vat (9) is an outlet opening for the tube (T).
10. Installation according to Claim 6, characterised in that following the fluidization vat (9) and an extractor (33a, 33b) surrounding an insulating sleeve (34) intended to be traversed coaxially by the tube (T) with a view to finally obtaining a tube (T) having a structure which is at least partly bainitic.
11. Installation according to Claim 10, characterised in that the shaft (33) is provided on its inside with rollers (35) for guiding, supporting and entraining the tube (T) and is provided externally with a lug (36) for articulation about a horizontal axis (YY) with a view to pivoting the shaft (33) through 90° by tilting means (39-40) in order to pass from a position on a vertical axis (XX) to a horizontal position (X1 X1) coaxial with the inlet (42) of a tunnel furnace (44) on a horizontal axis (X1 X1) for maintaining the bainitisation temperature of the tube (T).
12. Installation according to Claim 6, characterised in that with a view to finally obtaining a tube (T) having a structure of ferrite + perlite, the tube (T) emerges directly into the atmosphere on leaving the fluidization vat (9), the installation not having a shaft (33).
EP85116525A 1985-01-04 1985-12-23 Process and apparatus for continuously manufacturing spheroidal graphite cast iron pipes with a controlled microstructure Expired EP0190458B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85116525T ATE35291T1 (en) 1985-01-04 1985-12-23 METHOD AND DEVICE FOR CONTINUOUS PRODUCTION OF NODUCTIVE IRON PIPES WITH CONTROLLED STRUCTURE.

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FR8500159A FR2575683B1 (en) 1985-01-04 1985-01-04 PROCESS AND PLANT FOR THE CONTINUOUS MANUFACTURE OF CAST IRON PIPES WITH SPHEROIDAL GRAPHITE WITH CONTROLLED STRUCTURE
FR8500159 1985-01-04

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EP0190458A1 EP0190458A1 (en) 1986-08-13
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FR2415501A1 (en) * 1978-01-27 1979-08-24 Pont A Mousson PROCESS AND PLANT FOR CONTINUOUS CASTING OF TUBULAR PRODUCTS
US4420029A (en) * 1979-04-27 1983-12-13 Nippon Steel Corporation Apparatus for blocking escape of heat in hot slabs manufactured on continuous casting machines
JPS569354A (en) * 1979-07-06 1981-01-30 Riken Corp Tough spherical graphitic cast iron for abrasion resistant part
JPS5613421A (en) * 1979-07-09 1981-02-09 Riken Corp Tough and hard spheroidal graphite cast iron and its manufacture
US4257472A (en) * 1979-07-30 1981-03-24 Concast Incorporated Continuous casting of hollow shapes
JPS5931415B2 (en) * 1980-06-16 1984-08-02 住友金属工業株式会社 Hollow tube manufacturing method and device
JPS57100846A (en) * 1980-12-12 1982-06-23 Pioneer Electronic Corp Manufacture of alloy thin plate having high magnetic permeability of iron-cobalt-silicon compound
JPS57194240A (en) * 1981-05-26 1982-11-29 Yanmar Diesel Engine Co Ltd High-strength ductile cast iron
EP0176660A1 (en) * 1981-06-10 1986-04-09 Olin Corporation An apparatus and process for cooling and solidifying continuous or semi-continuously cast material
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108526265A (en) * 2018-02-28 2018-09-14 重庆市铭鼎机械制造有限公司 The manufacturing equipment of heavy exhaust pipe for vehicle
CN108526265B (en) * 2018-02-28 2019-06-21 重庆市铭鼎机械制造有限公司 Manufacturing equipment for exhaust pipes for heavy vehicles

Also Published As

Publication number Publication date
UA5948A1 (en) 1994-12-29
ATE35291T1 (en) 1988-07-15
EG17408A (en) 1991-08-30
JPS61177324A (en) 1986-08-09
YU44943B (en) 1991-04-30
FI860009A (en) 1986-07-05
KR900001325B1 (en) 1990-03-08
ZA859748B (en) 1986-08-27
MY103668A (en) 1993-08-28
FR2575683A1 (en) 1986-07-11
SI8710516A8 (en) 1996-08-31
AU5146485A (en) 1986-07-17
ES550663A0 (en) 1987-05-01
BR8600005A (en) 1986-09-23
FI860009A0 (en) 1986-01-02
FI80621C (en) 1990-07-10
SU1450729A3 (en) 1989-01-07
HRP930748B1 (en) 1996-04-30
YU44536B (en) 1990-08-31
HRP930763B1 (en) 1996-02-29
ES8705285A1 (en) 1987-05-01
PL257172A1 (en) 1986-10-07
PL144856B1 (en) 1988-07-30
CA1277478C (en) 1990-12-11
AU564826B2 (en) 1987-08-27
KR860005666A (en) 1986-08-11
DE3563458D1 (en) 1988-07-28
RO93864B (en) 1988-04-01
GB8530723D0 (en) 1986-01-22
YU200685A (en) 1988-04-30
EP0190458A1 (en) 1986-08-13
GB2169230A (en) 1986-07-09
US4800949A (en) 1989-01-31
YU51687A (en) 1989-08-31
RO93864A (en) 1988-03-30
FI80621B (en) 1990-03-30
DD247621A5 (en) 1987-07-15
MX164846B (en) 1992-09-29
JPH0615693B2 (en) 1994-03-02
SI8512006A8 (en) 1996-04-30
TR22514A (en) 1987-09-16
GB2169230B (en) 1989-06-14
FR2575683B1 (en) 1987-01-30
IN166932B (en) 1990-08-11

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