US3786824A

US3786824A - Chemical descaling apparatus for discontinuous automatic treatment of sheet metal

Info

Publication number: US3786824A
Application number: US00270061A
Authority: US
Inventors: B Lhenry
Original assignee: Creusot Loire SA
Current assignee: Creusot Loire SA
Priority date: 1972-07-10
Filing date: 1972-07-10
Publication date: 1974-01-22
Anticipated expiration: 1991-01-22

Abstract

Chemical descaling apparatus is provided for the automatic treatment of sheets of metal, including, a descaling pit and a rinsing pit, with introduction of the sheets into the descaling pit and for transferring them to the rinsing pit. The sheets are handled in a series of cradles by a transfer crane which is horizontally movable between the pits, and which has a vertically movable support bar which includes hooks for supporting the cradles. A runway is used for initially introducing sheets into the cradles.

Description

United States Patent 1191 Lhenry 1 Jan. 22, 1974 CHEMICAL DESCALING APPARATUS FOR 3,058,604 10/1962 Harper et a1 134/76 x DISCONTINUOUS AUTOMATIC 3,675,665 7/1972 Sadwith 134/62 X 2/1973 Tobias 134/83 x TREATMENT OF SHEET METAL Primary Examiner-Robert L. Bleutge 5 7 ABSTRACT Chemical descaling apparatus is provided for the auto- 10 Claims, 11 Drawing Figures PATENTED JAM 2 2 I974 sum 1 OF 7 FIG-,1

NQ I PATENTEDJAHZZ I914 3,788,824

SHEET 5 OF 7 FIG FIGZS PATENTEDJAHZZ I974 SHEET 7 [IF 7 CHEMICAL DESCALING APPARATUS FOR DISCONTINUOUS AUTOMATIC TREATMENT OF SHEET METAL This invention relates to chemical descaling appara' tus for the discontinuous automatic treatment of sheet metal.

The rolling and heat treatment of metal sheets produces a thick layer of scale which must be removed before every cold rolling operation. It is particularly important to obtain a product of suitable appearance before cold rolling in the case of certain types of steel, such as corrosion-resistant steels. Rolling would cause the traces of scale to become ingrained in the metal, giving a poor surface appearance and reducing the corrosion-resistance. Descaling is preferably carried out after mechanical descaling by shot-blasting, which enables the extent of subsequent acid descaling to be reduced, though not eliminated altogether. The chemical descaling of medium and thick sheet or plate has so far been carried out in primitive apparatus with little automation, for which the labour and running costs are very Apparatus embodying the invention enables this disadvantage to be overcome. andhigh productivity to be achieved during descaling. It can be usedfor descaling all types of steels in the form of medium or thick sheet.

According to the invention there is provided apparatus for-the chemical descaling of metal sheets, comprising means for moving the sheets, at least one pit filled with a descaling bath, a rinsing pit, a plurality of cradles in the form of elongate baskets, each intended to contain one sheet, and means for introducing the cradles successively one by one into the descaling pit and then into the rinsing pit, characterised in that means for moving. the sheets comprise a sheet runway provided along its path with means for automatically introducing each sheet separately into a cradle, the descaling and rinsing pits (are rectangular in cross-section and) adjoin one another along one long side parallel to the runway, level with the means for introducing the sheets into the cradles, and the means for introducing the eradles into the pits comprise a device for taking over the cradles, this device being vertically movable and mounted on a framework which can be moved at rightangles to the runway to bring it over the In order that the invention may be clearly understood, there will now be' described an embodiment thereof, given by way of example only, reference being had to the accompanying drawings, in which:

FIG. 1 is a side view of the apparatus;

FIG. 2 is a front elevation of the crane;

FIG. 3 shows part of the sheet guiding device with one of the conveyors which bring or remove the sheets;

FIG. 4 illustrates diagrammatically the operation of the apparatus;

FIGS. 5 to illustrate different phases during operation; and

FIG. 11 shows a variant of the apparatus.

The apparatus, of which FIG. 1 provides a general view, comprises a sheet guiding device 5 on to which the sheets are conveyed in order to enter or leave the apparatus. Cradles B1 to B4 are used for handling the sheets. A crane 3 carries out the various cradle transfer maneuvers, specifically be means of a vertically movable transverse beam 4. The cradles are transferred between vertical descaling and

water rinsing pits

1 and 2 respectively and between the guiding device 5 and these pits. The pit 1 contains the acid bath and the pit the crane 3, and which inclines slightly to the vertical,

bears a plurality of lateral rollers 7 which, with lower rollers 8 having horizontal axes, guide sheets such as T1. When the framework 6 is in the position illustrated, a cradle B1 is placed against the framework, on the axis of the conveyors which bring and remove the sheets. When the sheets T1 reaches the apparatus, therefore, it engages in the cradle B1. In the embodiment shown in FIG. 3 each conveyor such as 10 is formed of an assembly of

metal sections

11, 12 supporting

guide rollers

13, 14.

The cradles B1 to B4, FIG. 3 providing a partial front elevation of one, respectively comprise a metal cage formed of bars 15 bent into a U-shape, connected by bars 16 and joined to a cross-beam 17 having a shaft 18, whose bearing surfaces 19 to 22 are capable of cooperating with the various fastening (or suspending) means in the apparatus.

The cradle B1 adjoining the framework 6 is suspended by the bearing surfaces 22 from lifting hooks such as 23 keyed on a shaft 24.

Jacks 25, by means of their rods 26, operate levers 27 keyed on the shaft 24 and thereby rotate the lifting hooks 23.

The framework 6 is mounted so as to rock on two base members 28 about horizontal axes 29. Jacks 30 rock the framework by acting on buttresses 9 attached to the framework.

In the embodiment shown in FIGS. 1 and 2 the crane 3 consists chiefly of two vertical columns 31 assembled from sections, the tops of the columns being connected by a spacer cross-beam 32, also assembled from sections, and the bottoms of the columns being fixed to respective horizontal base members 33. Bracing beams 34 and gusset plates 35 ensure that the crane is rigid.

Each base member 33 bears runners 36 and guide rollers 37 to enable the crane to move along rails 38.

The lifting beam 4 slides along the vertical columns 31. It is formed of two carriages 42 guided by rollers 43 running along the strut bracing of the columns 31 and connected by a horizontal tube 44. Two pinions 45 mounted on a shaft 46 coaxial with the tube 44 engage, through openings in the horizontal tube 44, in two racks 47 on the columns 31. Two hydraulic motors 48 drive the shaft 46 and produce vertical movement of the lifting beam 4, while at the same time retaining beam 4.

The positioning of the crane 3 on the rails 38 is effected mainly by two

double jacks

49, 50 having common bodies, the rods of which extend in opposite directions and are respectively pivoted on the framework 6 (by means of a fork 51) and on the crane 3 (by means of a fork 52). As a result of successive or simultaneous operation of the

jacks

49, 50, therefore, the crane 3 can take up three positions relative to the framework 6, the positions being determined by the strokes of the jacks. Rocking of the framework 6 enables the crane 3 to be brought into six positions, to be specified below when the operation of the apparatus is described.-

The crane 3 comprises cradle suspending means in the form of receiving hooks 33 pivoted in forks 54 and capable of being withdrawn downwards about their axes 55 by jacks 56. The cradles are suspended from the receiving hooks 53 by way of the shaft bearing surfaces 20. i

The cradle suspending means on the lifting beam 4 are hooks 57 situated near the rinsing pit 2 and hooks 58 situated near the descaling pits l. The hooks 58 are pivoted on levers 59 by means of pins 40, the levers 59 being pivoted in turn by means of pins 60 on forks 62 attached to the tube 44. The rinsing books 57 are operated by jacks 63, so that they can be withdrawn as indicated by an arrow f1 on the side opposite the hooks 23 on the framework 6. The descaling hooks 58 are operated by way of the levers 59 by means of jacks 64, so that they withdraw, as indicated by an arrow f2, on the side opposite the receiving hooks 53. The cradles are suspended from these hooks by means of the bearing surfaces 20.

Above the descaling pit l the cradles are suspended by means of the end bearing surfaces 19 on the shaft 18, which bear on carriers such as 65, 66 (FIG. 4) provided on the side walls of the pits. The

cradles

65, 66 define two sites for receiving cradles such as B2 and B3. A carriage 67 moves between an initial position R and a final position R This carriage is formed of a frame 68 running on rails 69, by means of rollers 70, between twolimit position defined by abutments. It supports the cross-beam 17 of the cradle above the rinsing pit 2 and is pushed by the crane during part of the cycle, from R,, to R Lines 72 of means for spraying water under pressure are attached to the carriage frame 68 and are situated on each side of the cradle.

The operation of the apparatus will be illustrated with reference to FIGS. 4 and 5 to 10.

When a sheet Tl arrives in the apparatus, the rocking framework 6 is upright (FIG. 10). The lifting hook 23 is up, the rod of the jack 25 being retracted. The rods of the

jacks

49, 50 are retracted, and the lifting beam 4 is at the bottom of the crane, at A on the diagram of the cycle A, B, C, D, E, F, G, shown in FIG. 4, the eradle B4 being in the initial rinsing position R To initiate the sequence AB in the working cycle of- The lifting levers 23 are then taken so that the crane can return to position I during the sequence BC, this translatory movement being due to pressure from the jack 50. The translatory movement of the crane 3 is combined with raising of the lifting beam 4. During raising of the beam 4, shown in FIG. 6, the spraying of water under pressure is begun so that the sheet in cradle B4 is uniformly rinsed as it goes past the spraying lines 72. At the end of the sequence BC, the lifting ok st r lised, @199?rl i lhfi lafi p -ts I The rinsing hooks 57 having been taken off, righting of the framework 6 then causes the crane 3 to withdraw from position I to position III and the lifting beam to be displaced from C to D (FIG. 7). The sheet T4 which has just been rinsed is then discharged from the apparatus.

During the next sequence the crane remains in position III, the lifting beam dropping from D to E. For this sequence see FIG. 8 in particular. The descaling hooks 58 having remained disengaged since the beginning of the cycle, the cradle B1 continues to wait on the receiving hooks 53 and the lifting beam 4 descends to E to take the descaled but unrinsed cradle B3. The hooks 57, operated by the jacks 63, engage on the bearing surfaces of the cradle B3.

During the sequence EF which follows (FIG. 9), the lifting beam rises to F with the cradle B3. After it has risen, the cradle B1 is transferred from the crane to the lifting beam, the receiving hooks 53 being withdrawn by the jacks 56, whose rods retract after the descaling hooks 58 have engaged on the bearing surfaces of the cradle Bl due to operation of the jacks 64. During the sequence FG the crane shifts from III to I, bringing the cradles B1 and B3 respectively from the waiting position A: to the descaling position D2 to the rinsing positionn R (FIG. 9).

During the last sequence of the cycle, in which the lifting beam 4 moves from G to A, the cradle B3 engages in the frame of the rinsing carriage which is in position R During the descent of the cradle B3 the pressure water spraying is begun so that the sheets are rinsed twice, once during their descent and once during raising.

When operating with a working cycle as just described, the apparatus circulates only three cradles, viz. cradles B1, B3 and B4, cradle B2 remaining stationary throughout the cycle. The apparatus can therefore operate with three cradles, all the cycles being identical. Alternatively, it can operate with four cradles. If so, at that point in the second cycle such as A, B, C, D, E, F, G when the lifting beam 4 approaches to withdraw a cradle from the descaling bath 1, the rinsing hook 57 must descend opposite cradle B2 instead of cradle B3, and cradle B3 will therefore remain stationary throughout the second cycle.

The short-stroke jack 49 can then be used to shift the crane 3 before the lifting beam 4 descends so that it withdraws alternate cradles from the descaling pit 1. The jack 49, whose stroke is equal to the distance between the

supports

65, 66 for the cradles B2 and B3, must then return to its initial position before the lifting beam drops (common sequence GA). Four-cradle operation'enables the sheet descaling times to be extended by suitable proportions. It should be noted that at the beginning of AB of the cycle the descaling hooks 58 taken off the cradle B2 can move out of the way when the cradle B3 passes, due to the pivotable connections at 40.

Operation of the apparatus as just described provides optimum utilization of the equipment, since a plurality of maneuvers can be carried out in a given lifting-beam or crane position. However, such operation requires the characteristics of the apparatus to be determined according to certain dimensional requirements.

For example, in the case of four-cradle operations, the stroke of the jack 49 must of course be equal to the distance between the

supports

65, 66 for the cradles B2, B3. The distance 1 between the cradle support and the cradle support on the rinsing pit (carriage 67) must be equal to the distance 1 between the cradle sup- .or the rinsing books 57, the, translatory movement AB must also be equal to DC P6 I.

In a variant illustrated in FIG. 11 the framework is stationary instead of rocking. The hooks 23 are mounted on carriages 71 which, by means of jacks (not shown), can be moved horizontally on rollers 72 running in a runway 73. The carriage 71 can then transfer cradles such as B1 on the receiving hooks 53. Two arrangements are then possible. In the first the crane takes up a position II for transferring new sheets T1 arriving for descaling and a position III for transferring rinsed sheets T4, and the hook 23 is not shiftedduring these two operations. The operating cycle in this case is similar to that described above. In the other arrangement the crane remains in position I-to transfer incoming sheets and rinsed sheets, the carriage 23 being shifted between the two transfer operations.

Although four-cradle operation as described is undoubtedly the operation which gives the highest productivity, in view of the duration of the individual operations and the time during which a sheet must remain in the descaling bath, it would be possible, if this time is particularly long, to work with more than four cradles, in which case the descaling tank would have further cradle suspending positions. Automation would be more difficult, however, and the apparatus would have to be controlled by an operator who'would move the crane into position for the various operations.

' A plurality of descaling tanks containing different liq-. uids could of course be used if necessary, in which case the apparatus would be a little more complicated.

The apparatus could be simplified, for example, by providing only one pair of cradle suspending hooks on the liftingbeam, but this simplification would reduce the productivity of the whole.

The conveyors for supplying and discharging sheets might be designed to convey the sheets horizontally, so that the tilting framework 6 would have to take up a horizontal position. However, the time required to take over and discharge the sheets would be considerably longer.

Although in the embodiments described the crane runs on rails situated beneath it, the crane might alternatively run on rails situated above it.

The cradle suspending members described in the apparatus could be of any other type and might, for example, be tongs.

I claim:

1. Apparatus for the chemical descaling of metal sheets, comprising means for moving the sheets, at least one pit filled with a descaling bath, a rinsing pit, a plurality of cradles in the form of elongate baskets, each intended to contain one sheet, and means for introducing the cradles successively one by one into the descaling pit and then into the rinsing pit, characterised in that the means for moving the sheets comprises a sheet runway provided along its path with means for automatically introducing each sheet separately into a cradle, the descaling and rinsing pits are rectangular in cross-section and adjoin one another along one long side parallel to the runway, level with the means for introducing the sheets into the cradles, and the means for introducing the cradles into the pits comprise a device for taking over the cradles,this device being vertically movable and mounted on a framework which can be moved at right-angles to the runway to bring it over the pits.

2. Descaling apparatus as claimed in claim 1, characterised in that the runway comprises a row of first rollers for supporting the sheets on edge, these rollers being equispaced, having substantially horizontal axes and being associated with a substantially vertical flat structure slightly inclined on the side nearer the pits and bearing a plurality of second rollers for supporting the sheets, these second rollers-having axes parallel to the plane of the structure and being equispaced in parallel rows along the structure.

3. Descaling apparatus as claimed in claim 2, characterised in that the cradles comprise U-shaped members connected at their tops to a cross-beam and equispaced at intervals equal to those between the first rollers, and

the means for introducing the sheets into the cradles comprises a first member for suspending a cradle along the structure of the runwayin a position in which the U-shaped members are between the rows of second rollers and the first rollers, the bottoms of the U-shaped members being at a lower level than the tops of the first rollers.

4. Descaling apparatus as claimed in claim 3, characterised in that the device for taking over the cradles is a lifting beam parallel to the runway, and the framework is a crane bridging the pits and having two vertical columns connected by an upper crossbeam and mounted respectively on two carriages running on rails perpendicular to the runway and situated on both sides of the pits, each end of the lifting beam comprising means for vertical movement along one upright of the crane, and the lifting beam being provided with at least one second member for suspending a cradle.

5. Descaling apparatus as claimed in claim 4, characterised in that the lifting beam comprises two second members for suspending cradles, one member being on the side nearer the runway and the other on the side near the cross-beam of the crane and both being capable of depositing the cradles on and of taking over the cradles from, in the case of said one second member, the suspending member of the runway, in the case of the other second member a third cradle suspending member mounted on the crane cross-beam, and in the case of both second members suspension sites provided above the rinsing pit, in different crane position.

6. Descaling apparatus as claimed in claim 5, characterised 'in that the first, second and third cradle suspending members are pairs of hooks pivotable mounted on the runway, lifting beam and crane respectively, each being pivotable about a horizontal axis parallel to the runway and capable of engaging on respective bearing surfaces provided on the cross-beam of each cradle, the runway, lifting beam and crane comprising respective means for rotating their respective hooks.

7. Descaling apparatus as claimed in claim 6, characterised in that it comprises means for advancing the first suspending hooks of the runway towards the crane until. the cradle is in a position clear of the runway and coinciding both with a position determined by the third hooks of the crane, in a first crane position, and with a position determined by the second or lifting-beam hooks, in a second crane position, the lifting beam in a raised position on-the crane.

two parallel, mutually spaced lines of spraying means between which the cradle containing the sheet to be rinsed can pass during a downward movement and an upward movement of the lifting beam.

10. Descaling apparatus as claimed in claim 9, characterised in that the lines of spraying means are mounted on a frame fixed to a carriage capable of moving perpendicularly to the longitudinal axis of the pits.

v I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,786,824 Dated January 22, 197

inventor- (sf ard Lhenry 7 It is eertified that error appears in the above-identified patent and that said Letters Patentare hereby corrected as shown below:

Ori the cover sheet the following should be added:

[5Q] oreign Application Priority Data Agg. 15, 1971 France '7l,297

Signed and sealed this 3rd day of September 1974.

(SEAL) A I Attest:

McCOY M. GIBSON,- JR. 0. MARSHALL DANNY Attesting Officer? Commissionerof Patents FORM po'wso (1M9) USCOMM-DC 60876 6 69 i "-5. GOVERNMENT PRINTING OFFICE I'll 0-Jli-3S4,

Claims

1. Apparatus for the chemical descaling of metal sheets, comprising means for moving the sheets, at least one pit filled with a descaling bath, a rinsing pit, a plurality of cradles in the form of elongate baskets, each intended to contain one sheet, and means for introducing the cradles successively one by one into the descaling pit and then into the rinsing pit, characterised in that the means for moving the sheets comprises a sheet runway provided along its path with means for automatically introducing each sheet separately into a cradle, the descaling and rinsing pits are rectangular in cross-section and adjoin one another along one long side parallel to the runway, level with the means for introducing the sheets into the cradles, and the means for introducing the cradles into the pits comprise a device for taking over the cradles, this device being vertically movable and mounted on a framework which can be moved at right-angles to the runway to bring it over the pits.

2. Descaling apparatus as claimed in claim 1, characterised in that the runway comprises a row of first rollers for supporting the sheets on edge, these rollers being equispaced, having substantially horizontal axes and being associated with a substantially vertical flat structure slightly inclined on the side nearer the pits and bearing a plurality of second rollers for supporting the sheets, these second rollers having axes parallel to the plane of the structure and being equispaced in parallel rows along the structure.

3. Descaling apparatus as claimed in claim 2, characterised in that the cradles comprise U-shaped members connected at their tops to a cross-beam and equispaced at intervals equal to those between the first rollers, and the means for introducing the sheets into the cradles comprises a first member for suspending a cradle along the structure of the runway in a position in which the U-shaped members are between the rows of second rollers and the first rollers, the bottoms of the U-shaped members being at a lower level than the tops of the first rollers.

4. Descaling apparatus as claimed in claim 3, characterised in that the device for taking over the cradles is a lifting beam parallel to the runway, and the framework is a crane bridging the pits and having two vertical columns connected by an upper cross-beam and mounted respectively on two carriages running on rails perpendicular to the runway and situated on both sides of the pits, each end of the lifting beam comprising means for vertical movement along one upright of the crane, and the lifting beam being provided with at least one second member for suspending a cradle.

6. Descaling apparatus as claimed in claim 5, characterised in that the first, second and third cradle suspending members are pairs of hooks pivotable mounted on the runway, lifting beam and crane respectively, each being pivotable about a horizontal axis parallel to the runway and capable of engaging on respective bearing surfaces provided on the cross-beam of each cradle, the runway, lifting beam and crane comprising respective means for rotating their respective hooks.

7. Descaling apparatus as claimed in claim 6, characterised in that it comprises means for advancing the first suspending hooks of the runway towards the crane until the cradle is in a position clear of the runway and coinciding both with a position determined by the third hooks of the crane, in a first crane position, and with a position determined by the second or lifting-beam hooks, in a second crane position, the lifting beam in a raised position on the crane.

8. Descaling apparatus as claimed in claim 3, characterised in that that portion of the runway structure which is level with the pits and which bears the first cradle suspending members is pivotable about an axis parallel to the plane of the structure and is connected to means for tilting this pivotable portion about the said axis in the direction of the pits.

9. Descaling apparatus as claimed in claim 1, characterised in that the rinsing pit is provided with at least two parallel, mutually spaced lines of spraying means between which the cradle containing the sheet to be rinsed can pass during a downward movement and an upward movement of the lifting beam.