FR2496508A1 - Continuous mfr. of finned metal tube, esp. for heat exchangers - where crenellated fins are attached to both sides of flat tube made by bending metal strip and welding edges together - Google Patents

Abstract

A metal strip (I) is fed over a rotating die equipped with a reciprocating punch so a continuous row of crenellations is formed in strip (I). Strip (I) is then attached to one side of another metal strip (II) which is bent longitudinally to make a flat tube with adjacent edges which are joined by welding. In a pref. mfg. plant, two metal strips (I) are each made into crenellated strips, which are both welded to the underside of strip (II). Strip (II) is then bent longitudinally between the two crenellated strips and made into a flat tube where the crenellations form fins on each main surface of the flat tube. The fins have a very large surface area for heat exchange.

Description

 The invention relates to a continuous manufacturing process of a metal tube with fins having a high concentration of the exchange surface.

 More particularly, the invention relates to a process for the continuous production of a metal tube with fins, consisting of shaping fins in the form of slots from a strip, assembling them on a second strip and then giving this second strip a form of tube flattened by folding, and welding of its two edges.

The invention also relates to a continuous forging device producing fins in the form of slots of a rigorous geometry
Such metal tubes with fins are generally used to produce heat exchangers, and the fins constitute exchange surfaces, for example between a fluid conveyed by the tube and the outside.

 The manufacturing method, according to which one forms fins in the form of slots from a strip and these slots are assembled on a second strip which is then given by bending and welding a flattened tube shape, is advantageously implemented. much simpler and less expensive than other methods of manufacturing prior finned tubes. These methods, in fact, consist of threading a tube into the plate orifices constituting the fins, and then assembling the fins to the tube.

 These previous methods only made it possible to produce determined lengths of tubes, whereas according to the present method, it is possible to manufacture indefinite lengths of finned tubes.

 A currently existing method consists in shaping from a strip of slots in the form of slots using a rectilinear matrix and a punch. However, this method requires stopping the advance of the strip each die-stamping, and therefore does not allow continuous stamping.

 Another currently existing method consists in shaping fins by passing the strip between the teeth of two gears of complementary shape. This method, however, does not make it possible to produce fins in the form of rectangular slots. Indeed, given the movement of the teeth of these two gears which mesh, it is only possible to obtain fins in the form of triangular or trapezoidal slots.

 Furthermore, according to these methods, the folding of the strip on which the fins are assembled is generally carried out continuously by passing it between a folding roller and a counter roller respectively having the external shape and the internal shape of the fold that we wish to give to the strip. Therefore, the folded area of this strip is free of fins, and therefore does not carry exchange surfaces. This folding method is imprecise, and. requires a large strip folding zone.

 One of the aims of the present invention is to provide a process which allows the continuous shaping of fins in the form of substantially rectangular slots, that is to say having substantially parallel sides. This form of slots, in fact, due to the parallelism of its sides, gives the tube a higher concentration of the exchange surface than fins in the form of triangular or trapezoidal slots.

 Another object of the present invention is to provide a method which makes it possible to fold the strip carrying the fins over a narrower width than the existing methods, which therefore makes it possible to increase the width of the fins and therefore the concentration of the surfaces. exchange.

 Another object of the present invention is to provide a die-stamping device, which makes it possible to produce fins in the form of slots with parallel flanks continuously.

 Other objects and advantages of the present invention will appear in the course of the description which follows, which is however only given for information, and which is not intended to limit it.

 The process for the continuous production of a metal tube with fins having a high concentration of the exchange surface is characterized by the fact that the fins are continuously formed in the form of slots with parallel sides by die-stamping of the strip in a cylindrical matrix of revolution, animated by a continuous movement of rotation and having at its periphery teeth oriented according to its generatrices, which are animated the punch with a back and forth movement in the between-teeth and an alternating rotational movement, part of which is a movement accompanying the rotation of the die, at least when the end of the punch is engaged between two teeth.

 The device for continuous stamping of a strip in the form of notches with substantially parallel sides is characterized in that it comprises a cylindrical matrix of revolution, driven in a continuous rotational movement around its axis, having external teeth oriented according to generators and means for animating a punch of shape complementary to that of the between-teeth, taking into account the thickness of the strip, of a back-and-forth movement to introduce the said punch between two teeth and for the 'Extract, and with an alternating rotational movement, so that the punch substantially follows the rotational movement of the die at least when the end of the latter is engaged between two teeth.

 The invention will be better understood if reference is made to the description below, as well as to the appended drawings which form an integral part thereof.

 Figure 1 shows schematically, in illustration of the process, the essential phases of the manufacture of a fin tube according to the present invention.

 FIG. 2 shows by way of example, in perspective and in section, a fin tube according to the present invention, in a nonlimiting embodiment.

 Figure 3 shows schematically the matrixing device according to the present invention.

 Figures 4a to 4d illustrate the different phases of folding the strip on which the fins are assembled.

 The finned tube according to the present invention is produced from strips of which the reels at 2 and 3 are shown diagrammatically in FIG. 1. These reels are of a known type, and their support and drive means are within the reach of l 'Man of Art.

 The reel 2 unwinds a strip 4 which, as will appear later, is intended to produce the tubular part 5 of the finned tube 1.

 The reel 3 carries a strip 6 from which are made fins 7 in the form of slots.

 To produce a finned tube, as shown in FIG. 2, carrying fins on either side of the tube 5, two reels 3 are preferably mounted in parallel, and respectively unwind a strip intended to make each strip of fins.

 In the following description, only one strip of fins will be made. The manufacture of the two strips of fins is in fact substantially identical and takes place in parallel.

 The width of the strip strip 6 is slightly less than the half-width of the strip strip 4, as is evident from the finned tube shown in FIG. 2.

 In Figure 1, at 8 there is shown schematically a pre-treatment station of the strip 6, which can be a physical treatment or a chemical treatment appropriate to the nature of the strip, and to the subsequent operations which it undergoes.

 The strip 6 in the form of slots with parallel flanks, as shown in 7 in Figure 2 is carried out at the station shown schematically in 9. It should be noted that according to the invention, this shaping is carried out so continuous by means of a rotary die.

It makes it possible to produce slots with substantially parallel sides, that is to say substantially of the same shape as that which could be obtained by stamping in a rectilinear matrix. However, in the present case, the stamping is carried out continuously while rectilinear dies could not realize slots that in step by step. Furthermore, unlike the shaping of the slots by means of two gears, in the present case, the slots have substantially parallel sides.

 Figure 3 shows schematically the matrixing device according to the invention. This device comprises a matrix 10, cylindrical of revolution and mobile according to a continuous rotational movement around its axis 11.

This movement is shown diagrammatically by the arrow 12. The matrix 10 has teeth 13 on which its strip is formed in slots on its outer surface.

 To this end, the teeth are sized according to the shape of the slots which it is desired to obtain. In particular, their height is substantially equal to the height of the slots. The axes of the between teeth 14 are oriented convergently towards the axis 11 of the matrix. The lateral faces of the teeth may be parallel, however preferably it is the lateral faces of the between teeth which are parallel, which facilitates the production of the matrix. The upper surface 16 of the teeth and the lower surface 17 of the between teeth are substantially rectilinear or parallel to the curvature of the matrix at this level.

 Naturally, the diameter of the matrix is dimensioned according to the shape and the number of teeth.

 Furthermore, obviously, the perimeter of the outer circle is equal to a whole number of times the pitch of the toothing. The width of the matrix, more particularly at the level of its teeth, is at least equal to the width of the strip 6.

 The strip 6 is guided so as to present itself substantially tangentially to the matrix, preferably in the part where the teeth are driven in an upward movement, taking into account its direction of rotation, as shown in FIG. 3. strip is formed into slots by stamping in the teeth, using a punch 18.

 This punch 18 has a complementary shape between the teeth, taking into account the thickness of the strip; and has a useful surface corresponding to a toothing pitch.

 To this end, as shown schematically by way of example in FIG. 3, it has a finger-shaped part 19, of thickness slightly less than the distance between two teeth, taking into account the thickness of the strip , of length substantially equal to the height of the teeth. It also includes a shoulder 20, located at the base of the part 19, substantially perpendicular to the axis of the finger and preferably located before the latter, taking into account the direction of rotation 12 of the matrix.

 The part 19 of the punch is intended to force the introduction of the strip 6 between two teeth, and to make it take the form of the intermesh. Furthermore, the shoulder 20 ensures at the top of a tooth the shaping of the strip and of the welding bosses which subsequently facilitate the welding of the strip 6 on the strip 4. A cycle of the punch 18 corresponds to a rotation d '' a tooth pitch of the matrix 10.

 The punch 18 is moved back and forth, corresponding to the penetration of the finger 19 between two teeth, and its removal, as well as a rotational movement, so as to follow the rotational movement of the matrix 10 at least when the end of the finger 19 is engaged between two teeth. This rotational movement is alternating, the return to the initial position being effected when the punch is completely disengaged from the teeth.

 Preferably, after the punch, taking into account the direction of rotation of the die, a spring presser 21 ensures during the stamping of a slot the maintenance of the slot previously formed. This presser has, for example, surfaces 22 and 23, on either side of a lug 24. During the stamping of a slot, the surfaces 22 and 23 maintain the slots previously formed on the tops of the teeth, and the lug 24 holds the strip between these two teeth.

 Preferably, the surfaces 22 and 23 come into contact with the strip when the finger 19 begins to penetrate between two teeth.

It then moves relatively to the punch substantially parallel to its axis, and is returned, for example by a spring 25.

 Naturally, the width of the punch and of the presser is substantially equal to the width of the slots which it is desired to form.

 In a preferred embodiment, the reciprocating movement of the punch, as well as its rotational movement are respectively carried out by means of two cams 26 and 27. These two cams 26 and 27 act respectively on rollers 28 and 29 integral with the support 30 of the punch.

 Appropriate guide means, not shown in FIG. 3, guide the support 30 of the punch during its reciprocating movement, due to the rotation of the cam 26. These guide means are articulated with respect to an axis constituting preferably by the axis 11 so as to ensure the alternating rotational movement of the support 30 of the punch, which is caused by the rotation of the cam 27. These guide means also comprise suitable return means, so as to maintain the casters 28 and 29 in contact with the cams.

 The cams 26 and 27 are coaxial and integral in their rotational movement. Preferably, the caster 28 is in contact with the cam 26 at the level of the axis 31 of the finger 19 of the punch. The caster 29 is in contact with the cam 27 at an axis approximately perpendicular to the axis 31.

 The shape of the cams will be easily determined by those skilled in the art, so as to make the reciprocating movement of the punch in the between-teeth, and its rotational movement synchronizes with that of the rotation of the die , at least that the end of the punch is engaged between two teeth. The cam 27 ensures the upward rotation of the punch at least when its end is engaged between two teeth.

 Furthermore, a rotation of one revolution for the cams 26 and 27 corresponds to a rotation of one step for the matrix 10.

The slots thus formed remain engaged on the teeth of the matrix, during part of its rotation, until a ramp 32 gradually removes them. This ramp is fixed and it is preferably located in the upper part of the matrix, at the level of a groove 33 produced in the central part of the latter. This ramp 32 therefore crosses the toothed area. The curvature of its upper surface 34 varies progressively from a zone 35 where it is situated below the level of the lower surface of the slots, to a zone 36 where it is situated above the upper surface of the teeth, and from which becomes substantially straight and preferably substantially horizontal
Thus, the ramp 32 gradually loosens the slots of the teeth of the matrix. It should be noted that due to the shape of the teeth, the axes of the slots were oriented in a convergent manner towards the axis 11 of the matrix, when they were engaged. on the teeth. By cons, after being released from the teeth by the ramp 32, these axes become substantially parallel.

In the next phase of manufacturing, shown diagrammatically at 37, the two strips of strip 6 in the form of slots are assembled to the strip 4. This assembly is preferably carried out by a clerical spot weld, this type of assembly is the range of the Man of 1'F
In addition, in order to allow the advance of the product after welding, at 15, two self-locking toothed wheels in a direction taking references in the slots of fins and driven by an alternating horizontal movement in correspondence with the pitch of the welded drive the straps to the following operations. These two self-locking toothed wheels therefore make it possible to index the movement of the strip on the pitch of the slots themselves.

 Referring to FIG. 4a, the two strips of strip 6 are assembled on the strip of strip 4 and spaced apart by a distance 3E which defines the zone of folding of the strip 4. Furthermore, the width of the fins is determined with respect to to the width of the strip 4 so as to leave it free at the side edges thereof widths 39 and 40.

 Schematically shown in Figure 1 the station 40 for shaping the edges of the strip 4 which later allows the assembly by welding of its two edges. This shaping is carried out in a traditional way by means of folding rollers and counter-rollers between which the strip 4 passes.

 At 41, the folding of the leaf area 4 is folded. According to the present invention, this folding is carried out by stamping and more precisely by progressive stamping. This folding mode makes it possible to reduce the width 38 of the strip folding zone 4 to a minimum, and therefore to increase the width of the fins at this level accordingly. The exchange surface is thus increased.

 The folding could be carried out by a plurality of dies and punches of suitable shape. However, the invention prefers to achieve it by means of a die and a long punch whose useful surfaces have an increasing concavity in the direction of advancement of the strip.

 Furthermore, the die 42 and its punch 43 are driven by an alternative translational movement, so as to follow the advance of the strip at least during the stamping phase. The amplitude of this reciprocating movement is a fraction of the length of the matrix, the reverse of this fraction being close to the number of stampings that each strip portion undergoes during its passage to the stamping station 41. Figures 4a to 4d schematize different sections of the die and the punch of increasing useful surface, as well as the corresponding folding obtained from the strip 4.

 The concavity of the useful surfaces can increase continuously, or by a succession of constant sections having a width close to the amplitude of the reciprocating translational movement of the matrix.

 Preferably, the punch 43 is articulated in rotation at 44 relative to the matrix 42, and actuated by means, for example, of two jacks 45 and 45, whose body and axis are respectively secured to the matrix and to its punch. At the end of the stamping, the strip 4 has approximately the shape shown diagrammatically in FIG. 4d. At the next station 47, the end of the flanges 48 and 49 of the strip 4 are engaged between two knurls 50 with axes perpendicular to the direction of advancement of the strip. These knobs continuously tighten the two flanges 48 and 49 and assemble them, preferably, by electrical welding according to a known method.

 It should be noted that in FIG. 1, only the essential phases of the manufacture of a finned tube according to the invention have been shown diagrammatically, and that those skilled in the art can add additional positions thereto, in particular cutting stations, possibly refocusing and indexing stations for the fins. Furthermore, the translational and rotational movements of the different stations where the various manufacturing phases are carried out are synchronized with the movement of the die 10, that is to say with the shaping of slots of the strip 6, or of the translational movement of the slots themselves after their shaping.

 The manufacturing process and the die-stamping device according to the present invention therefore make it possible to produce, by means of a matrix driven in continuous rotation, fins in the form of notches whose flanks are substantially parallel. Furthermore, the method makes it possible to reduce the width of the folding zone 38 of the strip 4, which consequently increases the width of the fins at this zone. The invention therefore makes it possible to manufacture tubes having a higher concentration of exchange surfaces than currently existing methods.

 Naturally, the manufacturing process and the stamping device have only been described for information, and other implementations of the present invention could be adopted without departing from the scope thereof.

 In particular, given the metallic nature of the strip 6, it could be gradually removed from the teeth by magnetic means operating by attraction of the strip without hampering its advance, due to the rotation of the matrix.

Claims (17)

 1. A method of continuously manufacturing a metal tube with fins, having a high concentration of exchange surfaces, consisting in shaping the fins in the form of slots from a strip, assembling them on a second strip, then to give said second strip the form of a flattened tube by folding and welding its two edges, characterized in that the fins are continuously shaped in the form of slots having substantially parallel side flanks by stamping the strip in a matrix cylindrical of revolution, animated by a continuous movement of rotation, and having at its periphery teeth and between teeth whose axes are oriented substantially convergently towards the axis of the matrix, and that the we animate the punch with a back and forth movement in the between-teeth, and with an alternating movement of rotation of which a part is a movement of accompaniment of the rotation of the matrix, at least when the end - tee of the punch is engaged between two teeth.  2. Method according to claim 1, characterized in that a matrix is used whose lateral faces of each inter-tooth are substantially planar and oriented parallel to the axis of the entredent.  3. Method according to claim 1, characterized in that a matrix is used whose lateral faces of each tooth are substantially flat and oriented parallel to the axis of the tooth.  4. Method according to any one of claims 2 or 3, characterized in that the strip is extracted continuously from the matrix after shaping of the fins by sliding it along a ramp which strips off gradually the teeth of the matrix teeth.  5. Method according to any one of the preceding claims, characterized in that during the stamping of a slot, at least the previously stamped slot is held by pressing.  6. Method according to any one of the preceding claims, characterized in that the strip is folded on which the fins have been assembled in the form of slots with substantially parallel side flanks by a succession of stampings, by means of dies and punches having complementary useful surfaces, and of increasing concavity.  7. The method as claimed in claim 6, characterized in that a die and a long punch are used which respectively have an increasing concavity in the direction of advancement of the tube, each section of tube being stamped repeatedly between different annuities of the die and the punch.  8. Method according to any one of the preceding claims, characterized in that the movement of all the active means is synchronized, as well as the movement of movement of the bacon sheets with the movement of rotation of the matrix. of shaping the slots, or on the movement of advancement of the slots themselves after their shaping.  9. Device for continuous stamping of a strip in the form of slots with substantially parallel sides, characterized in that it comprises a cylindrical matrix of revolution, driven in a continuous rotational movement around its axis, having teeth on the outside and between-teeth whose axes are oriented substantially towards the axis of rotation of the die, and means for animating a punch of shape complementary to that of the between-teeth, taking into account the thickness of the strip, back and forth movement to introduce said punch between two teeth and to extract it, and with an alternating rotational movement so that the punch substantially follows the rotational movement of the die at least when the end of the punch is engaged between two teeth.  10. Forging device according to claim 9, charac terized in that it also comprises, during the forging of a niche, means for maintaining at least the niche previously formed in the teeth of the matrix.  11. Forging device according to claim 9, charac terized by the fact that said means comprise a punch movable in translation along guide means, in a direction oriented substantially towards the axis of rotation of the matrix, a cam movable in rotation and return means ensuring the back-and-forth movement of said punch between the teeth of the matrix, a turn of said cam corresponding to a rotation of a toothing pitch of the matrix.  12. Device according to claims 9 and 11, characterized in that said guide means are articulated in rotation substantially relative to the axis of rotation of the matrix, and that a cam, and return means ensure said movement alternating rotation of the guide means, one revolution of the cam corresponding to a rotation of one pitch of the teeth of the matrix.  13. Device according to claims 11 and 12, characterized in that the two cams are integral and coaxial, and that the support of the punch has in its rear part two rollers bearing respectively on each of the cams.  14. Device according to any one of claims 9 to 13, characterized in that the means for holding said previously formed niche comprise a spring-loaded presser which applies at least a part of said niche previously formed on the teeth of the matrix, at less during the penetration phase of the punch between two teeth.  15. Device according to any one of claims 9 to 14, characterized in that it also comprises a fixed ramp located behind the forming zone, taking into account the direction of rotation of the die, located in the part central of the matrix, and having a decreasing concavity from an area close to the forming area where its upper surface is below the lower surface of the niche, to an area where its upper surface is above the upper surface of the teeth, and where the ramp is substantially straight.  16. Device according to any one of claims 9 to 15, characterized in that it also comprises two self-locking toothed wheels in one direction, taking references in the slots of fins, and driven by an alternating horizontal movement in correspondence with the pitch of the weld, which indexes the movement of the strips after stamping and welding on the slots themselves.  17. Device according to any one of claims 9 to 14, characterized in that magnetic means exerts on the strip, after stamping, an attraction which gradually loosens it from the teeth of the matrix.