US3895498A

US3895498A - Apparatus and method for cooling metal slabs with a unitary structure for depositing and grasping the slabs

Info

Publication number: US3895498A
Application number: US297470A
Authority: US
Inventors: Willi Manthey; Horst Deiwick
Original assignee: BWG Bergwerk und Walzwerk Maschinenbau GmbH
Current assignee: BWG Bergwerk und Walzwerk Maschinenbau GmbH
Priority date: 1970-01-20
Filing date: 1972-10-13
Publication date: 1975-07-22
Anticipated expiration: 1992-07-22
Also published as: FR2160797B2; NL144848B; BE784713A; US3680344A; FR2160797A2; NL7016049A; AT316780B; GB1371445A; JPS5033261B2; DE2158091B2; FR2074895A5; GB1301509A; BE756498A; JPS4912438A; DE2002272A1; DE2158091A1; AT300236B; NL7208792A

Abstract

An apparatus and method for transporting metal slabs into and from a cooling basin comprises, on a carriage movable longitudinally of the basin, a unitary slab grasping device including a plurality of grasping devices spaced apart transversely of the basin, each of which devices forms two sideby-side downwardly opening pockets for alternately receiving a slab and is provided with a retainer member for releasably latching a slab in either pocket. The carriage is moved to a slab feed station at one end of the basin, where a hot slab is fed into and grasped in one of the pockets; thence along the basin to a location where the grasping device is lowered into the basin and is operated both to deposit the hot slab into an empty compartment of the basin and grasp in the other pocket a cooled slab present in an adjacent compartment. The grasping device then is raised and the carriage is moved farther to discharge the cooled slab at the other end of the basin. The retainer may comprise for each grasping device a member movable to close the bottom of either pocket or a separate retainer member for each pocket.

Description

United States Patent [191 Manthey et al.

[451 July 22, 1975 APPARATUS AND METHOD FOR COOLING METAL SLABS WITH A UNITARY STRUCTURE FOR DEPOSITING AND GRASPING THE SLABS [75] Inventors: Willi Manthey, Duisburg; Horst Deiwick, Krefled, both of Germany [73] Assignee: BWG-Bergwerk-und Walzwerk Machinenbau G.m.b.H., Duisburg, Germany [22] Filed: Oct. 13, 1972 [21] Appl. No.: 297,470

[30] Foreign Application Priority Data Nov. 24, 1971 Germany 2158091 [52] U.S. Cl. 62/64; 72/201; 134/25 A; 134/76; 134/134; 214/658; 266/4 A; 294/67 [51] Int. Cl B66f 9/18; B65g 47/34 [58] Field of Search 134/25 A, 42, 76, 77, 133, 134/134, 140, 164; 266/4 A, 6 R; 72/201;

214/1 BC, 658; 198/33 AD; 148/153, 155,

157; 294/67 R, 87 R, 67 D, 26.5, 69 R; 62/64 Primary Examiner-S. Leon Bashore Assistant Examiner-M. Steven Alvo Attorney, Agent, or F irmAlbert C. Johnston [57] ABSTRACT An apparatus and method for transporting metal slabs into and from a cooling basin comprises, on a carriage movable longitudinally of the basin, a unitary slab grasping device including a plurality of grasping devices spaced apart transversely of the basin, each of which devices forms two side-by-side downwardly opening pockets for alternately receiving a slab and is provided with a retainer member for releasably latching a slab in either pocket. The carriage is moved to a slab feed station at one end of the basin, where a hot slab is fed into and grasped in one of the pockets; thence along the basin to a location where the grasping device is lowered into the basin and is operated both to deposit the hot slab into an empty compartment of the basin and grasp in the other pocket a cooled slab present in an adjacent compartment. The grasping device then is raised and the carriage is moved farther to discharge the cooled slab at the other end of the basin. The retainer may comprise for each grasping device a member movable to close the bottom of either pocket or a separate retainer member [56] References Cited f h k UNITED STATES PATENTS or eac 3,680,344 8/1972 Manthey et a1. 72/201 7 94 Drawing Figures 4 .9 /0 Q 7 B 3 H Li H i] l l s .11 ill! :i ll!- 21 1 eeee 96996 969 eeee g 30 PATENTEDJUL 22 ms .SHEET III tem for depositing the slabs into and removing them from an elongate cooling basin.

This invention is particularly useful as an addition'to and improvement of a slab cooling system of the typedisclosed in US. Pat. No. 3,680,344, issued Aug. l,

1972, for an invention of Willi Manthey and Heinz Schmitter. In such a system, slabs or similar semi--' finished products of iron-works or the like are cooled by immersion in a cooling liquid such as water held in an elongate basin having a rectangular cross-section and provided with a shelf-like frame which forms bays or compartments therein to receive the slabs. Slabs are disposed in the cooling basin in an upright on-edge posture by means of a transporting device which extends transversely over and is movable along the basin and is equipped with a slab holder, or grasping means, movable vertically into and out of the cooling basin. The frame in the basin comprises longitudinal supports and vertical prongs which form compartmens lying transverse to the cooling basin. The transporting device is movable on rails longitudinally of the cooling basin between slab feeding and discharge stations at opposed ends of the basin. The slab grasping means comprises spaced apart grippers, or grasping devices, each of which has the form of a double-bar pocket opening downwardly'and provided with a retaining member for closing its bottom so as to latch a slab in the pocket. The retaining member is moved by a control rod into closed and open positions.

According to the disclosure of the aforementioned patent, the grasping means of the transporting device constitutes one slab retaining pocket. If only one transporting'device is used, the same grasping means must first lower and release a hot slab and then, by further" vertical and horizontal displacements of it, grasp and remove a cooled slab. Thus, only a relativelylow con-- veying frequency can be obtained. If, on the other hand, two transporting devices are used, their operating effectiveness is impaired because of an overlappingof the conveying distances.

This invention has as its object to provide a new and improved slab transporting system for an apparatus of the kind described, which enables rapid and troublefree conveyance for the lowering of hot slabs into and removing of cooled slabs from a cooling basin.

In accordance with this invention, the slab grasping means on thecarriage movable along the cooling basin constitute two downwardly opening pockets in parallel side-by-side relation and are provided with retaining means selectively operable upon each disposition of the grasping means in the basin to release a hot slab from one of the pockets into a vacant compartment of the basin and to latch in the other of the pockets a cooled slab present in a basin compartment adjacent to the previously vacant one. The slab grasping means constitute the two downwardly opening pockets in aunitary structure that is movable as a unit into andout of the basin by vertical movement of this structure'relative to the carriage.

them of the slab grasping means into and then out of the basin, lowera hot slab into a vacant compartment and grip and lift out of the basin a cooled slab present in the adjacent compartment. The removed slab can then be carried to the delivery station.

Thus, it becomes possible during each trip from the slab feeding station to the discharge station to lower or set downa hot slab and take out a cooled slab and carry it away; and an especially favorable transporting sequence can be achieved. Upon each working trip of the carriage along the cooling basin 'a hot slab may be placed in the pocket emptied during the preceding trip. As a consequence, the process of depositing in one compartment and emptying an adjacent compartment proceeds compartment by compartment over the entire length of the cooling basin, and each slab remains in its compartment for a period determined by the time taken for a cycle of the carriage movements and the number of compartments in the cooling basin, until it is removed in the regular sequence of operation.

The double pocketed grasping means of apparatus according to this invention can be provided with any of various means for releasably retaining a slab in either of the pockets. In one arrangement, the central vertical wall? separating the two pockets of each grasping unit' has' at' the bottom thereof a pivoted bearing connected in a substantially horizontal path of about to' and from either of two working positions. In one of these positions the retaining member extendsacross the bottom of and will hold a slab in one of the pockets, and in the other it functions similarly for the other pocket.

In another arrangement, a separate retaining member is provided for each pocket, as by hinging such a member at the bottom of each of the two outer bars which border the pockets. Each retaining member may be moved, as by a suitable control rod, to and away from alclos ed position in which it extends across the bottom of and will hold a slab in the related pocket. The bottom portion of the central bar in this arrangement may be provided with a recess to receive and a ledge to support an end portion of each retaining member.

The apparatus according to this invention may be givenl an even greater capacity by utilizing a cooling basirijl'iaving therein two slab positioning frames arranged side by side and along the basin so that two groups of slabs may be treated simultaneously. The earriage spanning the width of the basin is then provided with two sets of slab grippers,-or grasping devices, comprising at least four of these devies. Each of these grasping devices forms two pockets in parallel side-byside relation as above described. This design has the advantage that two slabs can be set down simultaneously with an end of one slab near to an end of the other, in a plane transverse to the longitudinal axis of the cooling basin; yet only onetransporting means is required. An apparatus given this doubled capacity can also be used for individual slabs which have up to twice the length of the slabs for which each slab positioning frame in the basin is designed.

By virtue of this arrangement, a transporting device 3 according to the invention can, by a single displace The above mentioned and other objects, features and advantages of the invention will be further apparent from the following detailed description and the accompanying drawings of illustrative embodiments thereof.

in the drawings:

FIG. 1 is a longitudinal sectional view of a preferred embodiment of a cooling system provided according to this invention;

FIG. 2 is a transverse cross-sectional view of the cooling basin, carriage and slab grasping means of the system of FIG. 1; I

FIG. 3 is an enlarged detailed vertical sectional view of a unit of the grasping means, taken in the longitudinal direction of the cooling basin; and

FIG. 4 is an enlarged detailed vertical sectional view of another embodiment of slab grasping means according to the invention.

The cooling system according to the embodiments illustrated makes use of an elongated cooling basin 6 having vertical end and side walls 7. The cooling basin may have a rectangular cross-section. Two slab positioning frames each consisting of longitudinal supports 8 and vertically extending prongs 9 are disposed within the basin 6. Each positioning frame may have at least two longitudinal supports 8 which define a shelf and to which the prongs 9 may be fastened. The prongs 9 are spaced apart in the longitudinal direction of the basin so that they form compartments to receive slabs disposed vertically between successive prongs ancl supported edgewise on the shelf defined by the supports. The shelves of both positioning frames are aligned relative to each other in the same, generally horizontal plane.

The cooling basin 6, as is well known in the art, may be filled with a cooling liquid such as water and have a circulation system (not shown). Two parallel rails 10 (FIG. 2) extend along the opposite longitudinal edges of the side walls 7 of the basin. A transporting device or carriage 11 is movably supported upon the rails 10. The carriage 11 comprises a frame 12 which extends over the full width of the cooling basin 6. On the frame 12 are mounted hoists 15. The hoists 15 comprise rack and pinion gears 15a for raising and lowering a traverse 13. Four doubly pocketed grasping devices 14 more fully described hereinafter, are mounted on the traverse 13. The carriage 11 is movable longitudinally of the cooling basin 6 on wheels which ride upon the rails 10.

Each slab grasping device 14 comprises three parallel vertical bars, or walls, 17, 18 and 19, respectively, which between them form two mutually parallel, downwardly opening pockets 16. The

walls

17, 18 and 19 have a heat insulating lining 24, preferably made of an asbestos plate material, over their inner surfaces. At the bottom of the pockets are retaining means operable to latch and support a slab releasably in either pocket.

In the embodiment of FIG. 3 the retaining means comprise a member 22 which is positioned by a rotatable control rod 20 arranged in the central bar 18. The control rod 20 is coupled to a bearing 21 pivoted in a bottom portion of the central bar 18 and a retaining member 22 is fitted in this pivoted bearing 21. The re-,

taining member 22 is formed with a shape and dimensions emabling it to extend across the bottom of either of the pockets l6 and thus securely to latch and support a slab in the pocket, and it is movable selectively into and away from this closed position with respect to either of the pockets. To that end, the bearing 21 has an opening in which the member 22 is hinged and from which member 22 extends horizontally so that it can be turned through a path of approximately 180 from the bottom of one pocket to the bottom of the other by rotation of the control rod 20. The two outer or side bars 17 and 19 of the grasping device each has a recess in registry with the bearing opening, and has a ledge 23 which forms a seat for the front end of the retaining member 22. The upper surface of the retaining member 22 .is provided with a heat insulating lining 24 which preferably is an asbestos plate material.

The rotatable control rod 20 may be connected through suitable gearing to a hydraulic or electric drive (not shown). The drive may be operated as a function of the particular work cycle desired and may dispose the retaining member 22 in the latching or closed position for either of the pockets 16 or in an intermediate open position.

Referring now to another emobodiment, there is shown in FIG. 4 a slab grasping device 14 having a separate retaining member 27 for each pocket 16. Each retainer 27 is hinged on a horizontal axis and has on its back end a lever arm pivotally secured to the lower end of a vertically movable control rod 26. By means of its control rod 26 each member 27 may be disposed in a closed position in which it extends across the bottom of its pocket and is supported at its front end by a laterally extending ledge 28 provided at the lower end of the central bar 18 below a recess in that bar. On the other hand, each member 27 can be pivoted upwardly to an open position, as shown in relation to bar 19 in FIG. 4, so that the pocket 16 is open to receive or release a slab 1 (shown by dot-dash lines in the closed pocket 16 in FIG. 4). The rods 26 are connected with a suitable hydraulic or electric driving means (not shown) which, in turn, is actuated as a function of the particular working cycle desired so as to dispose each of the retaining members 27 in either its closed or its open position.

As more fully described in the aforementioned patent, a pivotal hoist device 4 is provided at the slab feeding station at the front end of the cooling basin 6, and a pivotal unloading device 29 is provided at the slab discharge station at the other end of the basin. A hot slab to be cooled is rotated by the device 4 through from a flat-lying into an upright on-edge position.

Each cooled slab is re-positioned in reverse manner by the device 29. The hot slabs 1 may be conveyed to the feeding station by means of a conventional roll train 2. A pusher 3 pushes the slab 1 into the hoist device 4. The device 4 then is pivoted by hydraulic means 5 about an axis 5 so that the slab 1 is moved from a flat to an upright position so that it may be grasped in a pocket of the grasping devices 14 on carriage 11 at the feeding station. At the delivery end, on the other hand, a cooled slab 1 is inserted, by means of the grasping devices on the carriage 11, into the lowering device 29 which is then pivoted 90 about axis 30 to lay the slab flat in a horizontal position. The slab is then pushed by means of a pusher (not shown) onto a lowering platform 31 which then depositsthe slab on a conveying device such as a roll train (not shown). The

devices

4 and 29 may be arranged, in side-by-side pairs at the two ends of the cooling basin 6 so that two hot slabs may be simultaneously taken up by the carriage 11 and two cooled slabs simultaneously set down.

In operation, two hot slabs 1 are removed from roll train 2 and pushed into the hoist devices 4 by a pusher 3. Following that, the devices 4 are pivoted to place the slabs in a vertical posture. The carriage 11 now takes up the two slabs in a pocket 16 of the grasping devices 14, these devices being lowered by means of the rack and pinion 'drive and 15a to dispose an empty pocket 16 in each 'of them over one'of the slabs and the corresponding retaining member 22' theri'bein'g moved into its latching position by means of a control rod (see FIG. 3). Following that, the grasping devices are raised together with the latched-iii slabe 1. i

The carriage 11 is now moved along the cooling basin 6 to a location thereover where an empty'cooling compartment exists to receive the hot slabs" in the carriage. While the carriage is at this location, the grasping-devices 14 are lowered into thebasin so as to-placethe hot slabs in the empty compartment: i.e., each slab being disposed between two adjacent paris of prongs 9 and supported upon longitudinal supports 8. During this lowering, the bottom of the other, unoccupied pocket 16 of each grasping device .14 i's'open so that each of these vacant pockets is moved-over a slab present in a compartment of the basin adjacent tov thecompartment .into which a. hot slab is being deposited. When the hot slabs have been lowered onto the longitudinal supports 8, the grasping devices 14 are lowered below thesupports 8 sufficiently that their retaining members 22 (under the hot slabs), beingof the type shown in FIG. 3, may now be rotated 180 to a position underlying the cooled slabs in the pocket placed over them. Then, the grasping devices 14 are raised back up into the carriage with the cooled slabs latched therein, after which the carriage 11 is moved farther along the basin to the delivery station. The slabs are then lowered by the grasping means 14 and inserted into the unloading device 29.

After the slabs are released from the grasping means 14 and into the unloading device 29, that device is rotated 90 and the slabs are pushed onto the lowering platform 31. The carriage 11 now proceeds back to the feeding station for a repetition of the aforedescribed process. The new hot slab (s) is now deposited in the compartment (s) that was emptied in the preceding cycle. In this way, the location at which the grasping means deposit a hot slab and pick up a cooled slab progresses steadily from one end to the other of the cooling basin. A prerequisite is that at the start and end of each cycle there is an empty compartment.

The grasping devices 14 are operated as a function of the particular working cycle desired. When they are moved to the feeding station to take up a hot slab, their retaining

members

22 or 27 are in the open position. When then they are moved over the slab, and after encompassing it, the

respective members

22 or 27 are disposed in the locked position. At the same time, however, the adjacent pocket is in the open condition. Thus, as the hot slab is lowered into the basin, the vacant pocket being lowered with it can at one and the same time encompass a cooled slab. Then, after the hot slab is lowered, the

members

22 or 27 are removed from under the deposited hot slab and the same or like members are in turn brought into latching position underneath the cooled slab in the adjacent pocket 16. The

riage 11 can, instead of transporting two slabs at a time, i

move only one at a time, the length of which can be as great or as little as may be accommodated in the compartments of the cooling basin.

What is claimed isf lqIn apparatus for cooling metal slabs such as hot bars, bill'ets, blooms or ingots, comprising an elongate basin for a cooling liquid, slab feeding and slab discharge stations respectively at opposite ends of said basin, rneans forming in and longitudinally of said basin a succession of upwardly open compartments each extending transversely of said basin for supporting therein a slab placed vertically therein, a carriage disposed transversely 'over'said basin, means mounting said carriage for movement longitudinally of said basin between said stationsf slab grasping means on said carriageand means'for displacing said grasping means vertically relative to said'carriage so as to move slabs successively into and out of said compartments, the improvement wherein said slab grasping means includes a unitary structure movable as a unit into and out of said basin and constituting two downwardly opening pockets in parallel side-by-side relation, each for'receiving at least one of said slabs, and retaining means selectively operable upon a single disposition of said grasping means in said basin to release a hot slab from one of said pockets into a vacant one of said compartments and to latch in the other of said pockets a cooled slab present 'in one of said compartments adjacent to said vacant one.

2. Apparatus according to claim 1, said grasping means comprising a plurality of slab grasping devices spaced apart transversely of said basin, each of said devices comprising a central vertical bar and two outer vertical bars spaced horizontally from said central bar, said bars defining said pockets therebetween, said retaining means comprising on each of said outer bars a retaining member pivotally mounted for movement to and away from a closed position in which said member extends across the bottom of and will hold a slab in the related pocket.

3. Apparatus according to claim 2, said central bar having in the lower portion thereof a recess to receive and a ledge to support an end portion of each of said retaining members.

4. In apparatus for cooling metal slabs such as hot bars, billets, blooms or ingots, comprising an elongated basin for a cooling liquid, slab feeding and slab discharge stations respectively at opposite ends of said basin, means forming in and longitudinally of said basin a succession of upwardly open compartments each extending transversely of said basin for supporting therein a slab placed vertically therein, a carriage disposed transversely over said basin, means mounting said carriage for movement longitudinally of said basin between said stations, slab grasping means on said carriage and means for displacing said grasping means vertically relative to said carriage so as to move slabs successively into and out of said compartments, the improvement wherein said slab grasping means constitute two downwardly opening pockets in parallel side-byside relation, each for receiving at least one of said slabs, and retaining means selectively operable upon a single disposition of said grasping means in said basin to release a hot slab from one of said pockets into a vacant one of said compartments and to latch in the other of said pockets a cooled slab present in one of said compartments adjacent to said vacant one, said grasping means comprising a plurality of slab grasping devices spaced apart transversely of said basin, eahc of said devices comprising a central vertical bar and two outer vertical bars spaced horizontally from said central bar, said bars defining said pockets therebetween, said retaining means comprising a retaining member pivoted on an axis in said central bar for rotation selec tively to either of two working positions in one of which said member extends across the bottom of and will hold a slab in one of said pockets and in the other of which it extends across the bottom of and will hold a slab in the other of said pockets.

5.- Apparatus according to claim 4, said retaining member being rotatable about said axis in a substantially horizontal path of approximately 180 from one to the other of said positions, whereby a slab may be re leased from one of said pockets 'and another slab latched in the other of said pockets by a rotation of said member.

6. Apparatus according to claim 4, each of said outer bars having a recess therein to receive, and forming a ledge to support, the outer end portion of said retaining member. I v

7. The method of transporting metal slabs into and from a cooling basin which comprises a. moving a carriage having slab grasping means thereon in steps from a slab feeding station at one end of an elongate cooling basin to the location of a vacant compartment and an adjacent slabcontaining compartment in a succession of slab cooling compartments provided in and along said basin, next from said location to a slab discharge station at the other end of said basin, and then back to said feeding station for a next series of such steps, said grasping means constituting two downwardly opening slab receiving pockets in parallel ,side-by-side relation; I i

b while said carriage is at said feedingstation placing and latching a hot slab in one only of said pockets;

c. while said carriage is at said location; lowering said grasping means into said basin so as to place said hot slab in said vacant compartment and to place the. other ofsaid pocketsin encompassing relation to a cooled slab in said slab-containing compartment, then releasing said hot ,slab from said one pocket and latching said cooled slab in said other I pocket, and then raising out of said basin said grasping means with only said cooled slab held leasing said cooled slab from saidother pocket.

Claims

1. In apparatus for cooling metal slabs such as hot bars, billets, blooms or ingots, comprising an elongate basin for a cooling liquid, slab feeding and slab discharge stations respectively at opposite ends of said basin, means forming in and longitudinally of said basin a succession of upwardly open compartments each extending transversely of said basin for supporting therein a slab placed vertically therein, a carriage disposed transversely over said basin, means mounting said carriage for movement longitudinally of said basin between said stations, slab grasping means on said carriage and means for displacing said grasping means vertically relative To said carriage so as to move slabs successively into and out of said compartments, the improvement wherein said slab grasping means includes a unitary structure movable as a unit into and out of said basin and constituting two downwardly opening pockets in parallel side-by-side relation, each for receiving at least one of said slabs, and retaining means selectively operable upon a single disposition of said grasping means in said basin to release a hot slab from one of said pockets into a vacant one of said compartments and to latch in the other of said pockets a cooled slab present in one of said compartments adjacent to said vacant one.

4. In apparatus for cooling metal slabs such as hot bars, billets, blooms or ingots, comprising an elongated basin for a cooling liquid, slab feeding and slab discharge stations respectively at opposite ends of said basin, means forming in and longitudinally of said basin a succession of upwardly open compartments each extending transversely of said basin for supporting therein a slab placed vertically therein, a carriage disposed transversely over said basin, means mounting said carriage for movement longitudinally of said basin between said stations, slab grasping means on said carriage and means for displacing said grasping means vertically relative to said carriage so as to move slabs successively into and out of said compartments, the improvement wherein said slab grasping means constitute two downwardly opening pockets in parallel side-by-side relation, each for receiving at least one of said slabs, and retaining means selectively operable upon a single disposition of said grasping means in said basin to release a hot slab from one of said pockets into a vacant one of said compartments and to latch in the other of said pockets a cooled slab present in one of said compartments adjacent to said vacant one, said grasping means comprising a plurality of slab grasping devices spaced apart transversely of said basin, eahc of said devices comprising a central vertical bar and two outer vertical bars spaced horizontally from said central bar, said bars defining said pockets therebetween, said retaining means comprising a retaining member pivoted on an axis in said central bar for rotation selectively to either of two working positions in one of which said member extends across the bottom of and will hold a slab in one of said pockets and in the other of which it extends across the bottom of and will hold a slab in the other of said pockets.

5. Apparatus according to claim 4, said retaining member being rotatable about said axis in a substantially horizontal path of approximately 180* from one to the other of said positions, whereby a slab may be released from one of said pockets and another slab latched in the other of said pockets by a rotation of said member.

6. Apparatus according to claim 4, each of said outer bars having a recess therein to receive, and forming a ledge to support, the outer end portion of said retaining member.

7. The method of transporting metal slabs into and from a cooling basin which comprises a. moving a carriage having slab grasping means thereon in steps from a slab feeding station at one end of an elongate cooling basin to the location of a vaCant compartment and an adjacent slab-containing compartment in a succession of slab cooling compartments provided in and along said basin, next from said location to a slab discharge station at the other end of said basin, and then back to said feeding station for a next series of such steps, said grasping means constituting two downwardly opening slab receiving pockets in parallel side-by-side relation; b. while said carriage is at said feeding station placing and latching a hot slab in one only of said pockets; c. while said carriage is at said location; lowering said grasping means into said basin so as to place said hot slab in said vacant compartment and to place the other of said pockets in encompassing relation to a cooled slab in said slabcontaining compartment, then releasing said hot slab from said one pocket and latching said cooled slab in said other pocket, and then raising out of said basin said grasping means with only said cooled slab held therein; and d. While said carriage is at said discharge station releasing said cooled slab from said other pocket.