US3490621A

US3490621A - Workpiece distribution system

Info

Publication number: US3490621A
Application number: US698241A
Authority: US
Inventors: John W Cook
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1968-01-16
Filing date: 1968-01-16
Publication date: 1970-01-20
Anticipated expiration: 1987-01-20
Also published as: FR2000293A1; GB1262480A; SE358134B

Description

4 Sheets-Sheet 1 Jan. 20, 1970 J. w. cooK WORKPIECE DISTRIBUTION SYSTEM Filed Jan. 16, 1968 Jan. 20, 1970 J. w. cooK 3,490,621

woRxPIEcE DISTRIBUTION SYSTEM Filed Jan. 16, 1968 4 Sheets-Sheet 2 Q Q' u DCD@ wmuessss y INVENIOR mfw John w. Cook Jan. 2o, 1970 J. w. COOK WORKPIEGE DISTRIBUTION SYSTEM 4 Sheets-Sheet 5 Filed Jan. 16, 1968 Jan. 20, 1970 J. w. cooK WORKPIECE DISTRIBUTION SYSTEM 4 Sheets-Sheet 4 Filed Jan. 16, 1968 l ITO In l l f /f/r FIC-5.4.

United States Patent O 3,490,621 WORKPIECE DISTRIBUTION SYSTEM John W. Cook, Williamsville, N.Y., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Jan. 16, 1968, Ser. No. 698,241 Int. Cl. B65g 47/42 U.S. Cl. 214-23 10 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a system for accurately positioning workpieces or slabs that are to be disposed within a furnace of a hot strip rolling mill. The furnace into which the workpieces are to be disposed has a plurality of skids or support members upon which the workpieces are disposed and are directed through the furnace. Typically, the workpieces are slabs of steel in a variety of length ranges and must be disposed evenly within the furnace to provide even heating and to prevent damage to the skids. The workpiece handling system includes a furnace charging table with rollers and a motor for driving the rollers, and a plurality of position detectors disposed along the length of the furnace charging table to successively detect the position of the slabs as they are driven along the length of the table. Further, suitable control means including a storage facility for storing the length of the slabs to be handled is associated with the position detectors and with the drive means for the table to accurately position each of the slabs with respect to the skids and the furnace.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a workpiece handling system for accurately placing a plurality of workpieces or slabs, and more particularly to a system for accurately placing a plurality of slabs to be distributed evenly within a furnace of a hot strip rolling mill.

Description of the prior art In the typical hot strip steel mill, workpieces or slabs, which have been previously rolled from ingots or directly cast, are taken to the hot strip steel mill where they are converted from slabs to a coil of the steel strip. Typically, the slabs are taken to the hot strip steel mill in piles where they are sorted and arranged to be sent through a heating furnace in preparation to being rolled into a long strip. More specifically, the pile of slabs is first depiled and the slabs are sent singly to the furnaces along a series of tables.

In actual practice, the slabs come in a variety of ranges f lengths and are carefully positioned in accordance with their length before they are placed in the furnace. The furnaces include a plurality of burners disposed evenly throughout the furnace for heating the slabs to a temperature of approximately 2350 F. The heating process may require several hours to evenly heat each of the slabs throughout its thickness. It is desired to place the slabs evenly throughout the furnace so that the thermal load placed upon the burners by the slabs is approxi mately even to achieve the most eicient thermal exchange between the furnace and the slabs. It may be understood that if the slabs were not evenly spaced throughout the furnace, that portions of the slabs would not be heated enough whereas other slabs or portions thereof would be overheated. Further, the support members or skids upon which the slabs are slid through the furnaces are subject to warping at the high temperatures ICC of the furnaces if an even weight distribution is not placed on the skids.

In addition to the problem of presenting an even heat absorbing load to the furnaces, it is necessary to displace the ends of the slabs from the skids. Often in the processing of the slabs before they are positioned within the furnaces, the ends of the slabs are very rough and would have a tendency to cut or otherwise damage the furnace skids.

It has been typical of the prior art practice here for the operator to perform the desired positioning of the slabs into the furnace. The operator is normally not placed in a proximate position to the furnace charging tables and must view the placement through television monitors. The placement is achieved by the operator moving the slabs back and forth on the furnace charging table by driving the rollers in either direction. Such an operation is a time consuming one requiring .much of the operators time and attention.

It is therefore an object of this invention to provide a new and improved workpiece handling system for accurately positioning a series of 'workpieces or slabs in accordance with their length so they may be more advantageously distributed for processing.

SUMMARY OF THE INVENTION These and other objects are accomplished in accordance with the teachings of the present invention by providing a new and improved workpiece or slab handling system including a table with a plurality of rollers which are driven by a Suitable motor, a plurality of detectors for sensing the position of a slab as it is moved across the table, and a control means into which is fed data corresponding to the length of the slabs and which is responsive to the position detectors. In response to the input stored data, the control means directs the drive motor to decelerate and to bring a slab to a predetermined position on the table. The position detectors indicate those points at which the workpiece should be decelerated and provide a reference point with which the slabs should be placed. After a slab has been positioned, suitable means are provided for removing the slab from the table onto a plurality of skids which lead to the next processing area such as a furnace. The next slab is then positioned on the table in a manner dependent not only upon its length but also upon the previous position of the rst slab in order to provide a distributed load to the furnace.

DESCRIPTION OF THE DRAWINGS FIG. 4 is a plan view of the furnace charging table,l

showing the relative position of the position detectors and the slabs with regard to the skids; and

FIG. 5 is a schematic diagram of the control system which operatively interrelates the position detectors and the drive .motor in accordance with the teachings of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings and in particular to FIGS. '1A and 1B, there is shown an illustrative'embodi-' ment of a slab entry system in which the workpiece position distributing system of this invention is incorporated. A plurality of workpieces or slabs are brought as by a suitable overhead crane and disposed in a pile upon a slab receiving table 12. The slab receiving table 12 includes a plurality of rollers 16 which are driven through a suitable gearing by a drive motor 18, and a vplurality of slab lowering cradles 14 disposed between the rollers 16. The slab lowering cradles 14 are normally extended when the pile of slabs are brought down upon the slab receiving table 12 in order to prevent injury to the rollers 16. Next, the pile of slabs is conveyed to a depiler assembly 26 by suitable piler entry tables 20, which includes a plurality of rollers 22 driven by a drive motor 24. The depiler assembly 26 includes a depiler table 28 and a pusher assembly 34 for removing a single slab from the pile and displacing it onto a first furnace charging table 42. The depiler table 28 includes a plurality of rollers 30 which are driven by a suitable drive motor 32, and serves to receive the pile of slabs at a first level corresponding to that of the depiler entry tables 20 and to move the pile slabs through incremental steps corresponding to the thicknesses of the slabs so that the pusher assembly 34 may slide the topmost slab onto the rst furnace charging table 42.

The pusher assembly 34 includes a pair of pushers 36 which are driven in a reciprocal, rectilinear motion by a suitable drive motor 38. The pushers 36 displace the topmost slab onto a plurality of skids 40 disposed between the rollers 30 and the rst furnace charging table 42. The first furnace charging table 42 includes a plurality of rollers 46 and a suitable drive motor 44 geared thereto. As shown in FIG. 1A, the plurality of skids 40 are disposed between the rollers 46 and serve to prevent the slabs from pushing against the ends of the rollers 46 and also to allow the slabs to be gently lowered onto the table 42. For a further description of the structure and operation of the depiler assembly, reference is made to a copending application (W.E. 39,111) by the same inventor and assigned to the assignee of this invention and which is entitled Slab Handling Apparatus, Ser. No. 698,223 and filing date Ian. 16, 1968.

After the slabs have been depiled, they may be individually driven from the rst charging table 42 onto a second furnace charging table 54 including a plurality of rollers 56 driven through a suitable gearing by a drive motor 58. The exit of a slab from the rst charging table 42 is sensed by a position detector 48 illustratively including a radiation sensor 49 and a source 50 of radiation for emitting a beam across the second furnace charging table 54 onto vthe sensor 49. A second position detector 51 is disposed at the other end of the second furnace charging table 54 which initiates a signal, as will be explained later, to stop the drive motor 58 when the slab has reached this point. The second position detector 51 includes a radiation sensor 52 such as a photocell and a source 53 for directing a beam of radiation across the second furnace charging table S4 onto the radiation sensor 52.

A slab will be brought, as explained above, from the slab receiving table 12 through the depiler assembly 26 to the end of the second furnace charging table 54, where itV is held until one of the

furnaces

110 or 112 may accept an additional slab. The slab upon command will bebrought from the second furnace charging table 54 onto a third furnace charging table 60 which includes a plurality of rollers 62 driven through a suitable gearing by a drive motor 64. If the furnace 110 disposed adjacent the third furnace charging table 60 is in need of additional slabs, the slab will be brought to its correct position upon the third furnace charging table 60 and will be slid by a pusher assembly 66 onto a plurality of support members or skids 101 to 106 associated with the furnace 110.

If it has been determined that furnace 110 is not to receive the next slab, the slab will be passed from the third table 114 having a plurality of rollers 116 which are driven by a motor 118. The fourth furnace charging table 114 will convey the slab to the fifth furnace charging table 124, where the slab may be positioned and slid into the second furnace 112. The fifth furnace charging table 124 includes a plurality of rollers 125 which are driven by motor 123. Similarly, the fifth furnace charging table 124 is associated with a pusher assembly 126 including a pair of pushers 128 which may be driven forward to slide the slab onto a plurality of skids 131 to 136 which are directed along the length of the furnace 112.

Referring now to FIG. 2, a side view of the pusher assembly 66 is shown. The pusher assembly 66 includes a pair of pushers 68 which are supported by a plurality of rollers to be driven in a reciprocal, rectilinear motion. Each of the pushers 68 include a rack 84 whose teeth mesh with a pinion gear 82. As shown in FIG. 4, the pinion gears 82 are connected to a drive shaft 70 which is driven by a pair of motors 72. As shown in FIGS. 2 and 4, the

pushers 68 have a head assembly 74 from which are suspended a plurality of teeth 76 by pins 78. A slab shown in FIG. 2 is disposed upon the table 60 and is designated by the numeral 162. When the pushers 68 are driven forward, the teeth 76 will abut against the slab 162 to slide the slab 162 onto skids 101 to 106. The pushers are now withdrawn to their initial position as shown in FIG. 2. It is noted that the teeth 76 are suspended upon the pins 78 to allow the teeth to rotate counterclockwise as shown in FIG. 2 if they strike an object such as another slab upon their retracting cycle.

Referring now to FIG. 4, there is shown the relative position of a plurality of

slab detectors

86, 96 and 98 with respect to the third furnace charging table 60. The first slab detector 86 is disposed in line with the skid 106, the second slab detector 96 is disposed centrally of the table 60 and between the

skids

103 and 104, and the detector 98 is disposed in line with the skid 101. As shown in FIG. 3, the slab detector 86 includes an insulating support member 88 from which are suspended a plurality of exible members or pigtails 92. The pigtails 92 are made of a suitable electrically conductive material such as a woven steel which will withstand the repeated contact -with the slabs 162. When the slab 162 is driven by the rollers 62 to contact the pigtails 92, an electrical circuit will be completed with a contact sensor 94, which in turn will provide a signal indicating that the slab 162 is now passing a particular point on the third furnace charging table 60. A first circuit is established with the contact sensor 94 through the pigtails 92, the slab 162 and the rollers 62. A second circuit is formed with the contact sensor 94 through a plurality of conductor rings 90, which are disposed upon the insulating support 88, and the pigtails 92. Thus, when the slab 162 strikes the pigtails 92, two parallel circuits will be closed, and the contact sensor 94 will provide an indication of the position of the slab 162.

Further, a second set of

slab detectors

138, 140 and 142 are disposed above the fifth furnace charging table 124 in a similar manner to that described above. More specifically, the slab detector 138 is aligned with the skid 136; the slab detector 140 is disposed centrally of the table 124 and the furnace 112; and the slab detector 142 iS aligned with the skid 131. Further, a third position detector is disposed at the end of the fourth furnace charging table 114 to control the entry of the slabs 162 onto the fifth furnace charging table 124. Illustratively, the position detector 120 may include a radiation sensor 121 and a source 122 for emitting a beam of radiation across the fourth furnace charging table 114 onto the sensor 121. It is noted that the

slab detectors

96, 98, 138,

and 142 are similar to the detector 86 shown and described with respect to FIG. 3.

Referring now to FIG. 4, there will now be explained in detail the process of positioning a slab or workpiece upon the third furnace charging table 60, After a slab furnace charging tabl@ 60 t@ a .fourth furnace charging 75 has been positioned 1119911 the table 60, the pusher asf sembly 66 will be driven forward by the motors 72 to slide the slab from the table 60 onto the skids 101 to 106.

It is the relative position of the slab with respect to the skids 101 to 106 that is significant, and it is desired to position a series of slabs as shown in FIG. 4 to present an even heat distribution to the furnace 110 and to avoid pushing the roughened edges of the slabs along one of the skids 101 to 106. The slabs to be heated in the furnace 110 come in three ranges of length, listed as follows:

The desired distribution of the slabs upon the skids 101 to 106 is shown in FIG. 4 to provide the desired heat loading upon the furnace 110. The ranges of slab lengths as given above are typical of those that are normally used in practice. Slabs of a length in range A will be centered with respect to the furnace 110 and with respect to the third furnace charging table 60. Slabs of a length in range B will be staggered in the furnace with a fixed offset from the

skids

101 and 106. The short or double row slabs having a length in range C will be positioned in double rows and will be centered approximately on the quarter lines of the furnace 110 with a varying overhang on the

skids

101 and 106.

In order to handle the sla-bs as rapidly as possible, the slabs are transported by the first and second furnace charging tables 42 and 54 at a high rate of speed, illustratively 450 feet per minute (f.p.m.). The slabs conveyed by this system may weigh in the range of 4000 to 100,000 pounds. In order to minimize variations in the stopping distance due to variations in the wk2 and possible changes in the coefiicients of the friction between the slabs and the rollers 62, the final stop will be made from a relatively slow, constant speed. Illustratively, the slow speed from which the stop will be initiated will be 60 f.p.m. Assuming a deceleration rate of 240 f.p.m./sec., the stopping time required will be .25 second and the distance traveled will be 1.5 inches. Due to a delay in conveying the signal between the slab detectors and the drive motor 64, the

stopping distance required from the slow speed will be in the order of two inches. Thus, each of the slabs regardless of size will be conveyed at a high rate of speed and will be decelerated to a constant slow speed so that each of the slabs regardless of mass may beaccurately positioned with respect to the skids.

Illustratively, a first slab 163 having a length of 36 is to be positioned initially in the furnace 110, Referring to FIG. 4, it can be seen that the slab 163 is to be centered with respect to the centerline of the furnace 110. The slab 163 will be brought to the third furnace charging table 60 at full speed and will remain at this speed until the leading edge of the slab 163 is sensed by the slab detector 96. At this point the slab 163 will be decelerated to the slower, creep speed of 60 f.p.m. The slab 163 will proceed to the slab detector 98. When the slab detector 98 is contacted, a time delay will be provided between the contact and the initiating of the stopping action by the motor 64. In one illustrative embodiment of this invention, the skid 101 is spaced 372 from skid 106. As stated above, approximately two inches is required to stop a slab from a speed of approximately 60 feet per minute. In order to center the slab 163 having a length of 36', it is necessary to allow the slab 163 to overhang the

skids

101 and 106 by 32". Thus, the time delay must be of sufficient duration to allow 30" of the slab 163 to pass after the position detector 98 has been contacted; this delay period would take approximately 2.5 seconds. As the length of the slabs in the first range varies from 36' to 32'8", the overhang of

skids

101 and 106 Will vary from 32" to 12" and the time delay will vary from 2.5 seconds to .85 second. A second slab 164 having an illustrative length of 32'8" will be similarly positioned and would have an overhang of 12" corresponding to a delay of .85 second. A general equation for determining the time delay TD would be:

where L is slab length in inches and lies in the range Ibetween 432 inches and 392 inches.

The second or intermediate range B of slabs fall in the range between 30'10 and 2610. As shown in FIG. 4, the slabs in this range Will be staggered in the furnace with successive slabs having overhangs from one of the

skids

101 and 106. The overhang across

skids

101 and 106 will be a fixed value; in one illustrative embodiment, the fixed overhang may be 12". This will result in a fixed time delay between the actuation of either the slab detector 98 or the slab detector 86 and the deceleration of the slabs in this range; the delay will be approximately .85 second for an illustrative overhang of 12" assuming the stopping is from a speed of approximately 60 feet per minute. A first slab 165 of the intermediate length is to be positioned in the following manner. The slab will be conveyed from the second furnace charging table 54 to the third furnace charging table 60 at a high rate of speed to contact the slab detector 96. In response to the actuation of the slab detector 96, the drive motor 64 will be slowed down to convey the slab 165 at the slow rate of approximately 60 f.p.m. The slab 165 will proceed to the slab detector 98 and will be stopped after a time delay of .85 second with the edge approximately l2 beyond the skid 101. If a next slab 166 is also in the intermediate length, it will be positioned with an overhang from skid 106. In this case, the slab 166 will proceed to the detector 96 at a top speed. The slab 166 will be slowed to a half or slow speed until it contacts the slab detector 98 at which instant, the motor 64 will be reversed to convey the slab 166 in an opposite direction until it contacts the slab detector 86. Upon contact with the detector 86, a time delay of .85 second will be provided and the trailing edge of the sla-b 166 will be disposed with an overhang of approximately l2" from the skid 106. The rst slab in a series of intermediate range B Will desirably be positioned with an overhang from skid 101. As shown in FIG. 4, the next pair of

slabs

167 and 168 will be disposed with a fixed offset respectively from

skids

101 and 106. Next, the positioning of the short slabs that lie in the third range C of 136" to 17 will be explained. Slabs in range C will always be charged or distributed in double rows in the furnace 110 as shown in FIG. 4, and, will always be scheduled to the furnaces in pairs. It is not necessary that the pairs of slabs have the same length and thickness; however, it is important that the pairs be of approximately the same width. When short slabs of range C are to be positioned, a first short slab 169 will be conveyed from the second furnace charging table 54 onto the third furnace charging table 60 at top speed until it contacts slab detector 86, at which point the slab 169 will be slowed to a half speed of approximately 225 f.p.m. The slab 169 will proceed to the slab detector 96, where the slab 169 will be stopped and conveyed back to the slab detector 86. When the detector 86 is contacted for the second time, a time delay will be set which is a function of the slab length between the contacting of the detector 86 and the stopping of the drive motor 64. When the time delay is completed, the slab 168 will be stopped with the slab end properly positioned, i.e., the leading edge of the slab 169 will have an overhang from the skid 104 equal approximately to the overhang of the trailing edge from skid 106. As shown in FIG. 4, the overhang of the slab 169 having a length of 17 will ybe 32". The time delay TD will be a function of slab length and is defined by the following equation:

where L is the slab length inches and lies betweenn204 ichsaiid" l`62`iriclies', land theseparation between the skids 104 and 106 (101 and f.f103) is equal to 144 inches.

When the first shortslab 169 of the pair hasv been correctly positioned, the pusher assembly 66 will be activated'as by the operator to displace the slab 169 onto the'furnace skids in order to allow a second'short slabv 170 to" bebrought to the third furnace charging table 60 and positioneduAfter'the parking push `of the 'assembly 66 has been completedfia'nd the pushers 68 withdrawn, th`e second short slab 170` is brought to the 'third furnace chargn'gi'table V60 at' high speed. When the slab 170 activates the slab detector 96, 'the slab 170'will` be slowed to the slow speed ofappr'oirimately 60 fpm. and will proceed to the: slabv detector 98;`When the slab detector 98 has beenl contacted,`f an appropriate time delay will b'e set depending upon the length ofthe slab' 170.' After the time delay has been completed and the slab stopped, it will be4v in the positionwith approximately equal overhangs fror'r'is'kids 101'a'nd 103. As showri'inl FIG. 4, a second pair of "short Aslabs 171'and`1'7'2 rriay illustrative'ly then'be 'positioiied arid'pushe'd ontol` the' skids 10`1Qtol 106. 'fhe 'slabs' 171 and 172 are illu'strativelyof av length'136 and have an overhang of 11" from their skids.

lReferring now to FIG. 5, there is shown `a control system which is responsive to the plurality of slab detectors to control the drive motors associated with each of the fumace charging tables. As shown in FIG. 3, the slab detector 88 is associated with the contact sensor 94 which as shown in FIG. is connected to a computer 146. It may be understood that the

other detectors

96, 98, 138, 140 and 142 are likewise associated with similar contact sensors which are connected to the computer 146. An input is made to the computer 146 lby an input card reader 144. Typically, a card with dimension data of a slab is placed in the order of its processing into the card reader 144 which transfers an appropriate slab length information into a storage facility within the computer 146. The computer 146 controls the speed, and the deceleration of the slabs in accordance with their length. The computer 146 acts to control the speed of the drive motor 64 in order to decelerate or to stop a slab through a speed control circuit 148 which provides an output signal indicative of the desired speed to a power supply 150. Illustratively, the table of drive motor 64 could be of a variable voltage type whose speed is dependent upon the output signal of the power supply 150.

A speed detector 154 may be suitably connected to the drive motor 64 in order to provide an output signal which is a function of the speed at which the rollers 62 and therefore a slab is being dri-ven. The output of thespeed detector 154 is applied to the speed control circuit 148 to complete a control loop to thereby insure that the table drive motor 64 is being controlled accurately to the correct speed. In addition, a manual master switch 156 may be connected to the speed control circuit 148 whereby the operator may override the commands of the computer 146 or operate the device in a manual mode to position the slabs upon the tables. The slab control circuitry may be vsupplemented by a position controlcircuit 160 which wouldin turn provide avfeedback signal to the speed control circuit 148. In 'this alternative embodiment, a suitable position detector 158 lwould beconnected to either the drive motor 64 or the gearing associated with the rollers 62 in order to provide an output signal as a function of the number of revolutions or relative position of the rollers 62. This position indicating signal would be -fed back to the position control circuit 160 to accurately control the speed and therefore the position of the rollers drive by the motor 64. As shown in FIG. 5, the drive motor. 123 is also connected to the computer 146. It isY understood that a plurality of furnaces would normally be provided with corresponding furnace charging tables and pusher assemblies for positioning and distributing the slabs as described above, The computer 146 would also serve'to sense thev position of the :slabs and to control the drive motors associated with the furnace tables as described above. In order to control the entry of the slabs onto the furnace charging tables 60 and 124, respectively, position detectors 51 and 120-are disposed to detect the position of slabs on the previous:furnacel charging tables 54 and 1'14. It may be 'understood' that if the furnace charging tables 60 or 124 arel notfree ofl slabs, that the slabs approaching these tables will" bek detected and stopped beforethey arev able to gain access to these tables. V'As explained in the above identified application, the operation of the pusher assembly 26 is to furnish slabs, one at a time, to the second furnace charging table 54 to await further advancement onto the tables. When a slab reaches the sensor 51, the slab will be brought to a halt waiting further linstructions from the computer 146. The order of charging will start with the rstfurnace 110 and' will proceed with the' second furnace 112. Typically, there lmay beI a plurality of furnaces, andl the charging and the-'positioning of slabs will take place scquentially.l If first' the'furnace 110 is selected out of service, the sequence will start with 4the second ffurnace 1.12. Before the sequence of charging begins,l the computer 146 will retract each of the

pusher assemblies

66 and 120. In some instances, it may be necessary for the operator to manually retract the pushers in order to initiate the automatic operation. When theA lirst slab is brought to the second furnace charging table 54 and .the positiondetector 51 is actuated, the vcomputer 146will recognize that-the slab is presenton the second furnace charging table 54. This slab will -be advanced to the third furnace charging tba-ble and will be positioned vas`described above and then pushed into the furnace 110. For the purposes of this discussion, it will be assumed that the slabs are of such dimensions that they are disposed in single rows. More specifically, the first slab will proceed to the third furnace charging table 60 where it will be slowed by the detector 96 and will vproceed to actuate the detector 98. After a computer time delay provided lby the computer 146, the lirst vslab will be brought to rest in its appropriate positionwith regard to the skids 101 to 106.

- Asbsoon as the second furnace charge table is yopen as determined either by the voperator or the position detector 51, the second slab will be moved onto the second furnace charging table54. When the rst slab has been positioned upon the third furnace charging table 60, the pusher assembly 66 will be actuated to place the rst slab onto the skids 101 to 106. The second slab-will be conveyed from the second furnace charging table l54 upon the ables 60,114 to the fth furnace charging table 124 .to be positioned for pushing Onto the skids 131 to 136. As'soon as the second slab has contacted the slab detector 142, the third slab, which has. been brought up and positioned on the'second furnace charging table54, will ybe 4,conveyed to 'the fourth furnace charging table 114. As .soonv as `the second slab has been positioned-the pusher assembly 120 will' be actuated to' push the'- second slab. onto the skids associated with the second 'furnace 112--If theiifth furnace charging table"124 is not open to allow* thethirdslab to pass, the contacting ofthe' detector 86 kwill initiate a slow down of the third and fourth furnace charging tables to half speed. The third'slab will be stopped on the fourth furnace charging table 114 when it contacts the position detector to await the clearing 0f the fifth vfurnace charging table 124 so that the third slab may proceed to the third furnace. When the third slab has left the second furnace charging table 54, the

next slab will'be brought upl onto thesecond furnace charging table 54. If the thirdfurnace chargingv table 60 is .now open and the pusher assembly 664 has beenretracted, the fourth slab will now be positioned on the third vfurnace chargingtable 60. In this manner'a plurality-offurnaces may be charged with a minimum of effort and supervisionby the operator.- When 'the slabs have been positioned, the computer will either automatically initiate a pushing operation or provide indication to the operator who may thenvisually check the position upon the furnace charging table before actuating the pusher assembly.

Since numerous changes may be made in the above described apparatus and diierent embodiments of the invention may be made without departing from the spirit thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A workpiece handling system including rst support means for receiving a plurality of workpieces of assorted sizes, drive means associated with said support means for moving said workpieces'in either a forward or backward direction upon said support means, detection means for detecting the position of said workpieces with respect to various points upon said support means, and control means including a storage facility for at least one dimension of said workpieces, said control means being responsive to said detection means for automatically deaccelerating said workpieces for stopping said workpieces upon said support means at a prescribed distance from said points dependent upon said stored dimension of said workpiece. v

2. A workpiece handling system as claimed in claim 1, wherein said detection means senses the position of said workpiece with respect to at least rst and second points upon said support means, and said control means initiates a deceleration of said workpiece from a first to a second speed as said workpiece passes said first point and provides a time delay between the time when said workpiece passes said second point and the time when said control means causes said drive means to stop said workpiece at said prescribed distance from said second point.

3. A workpiece handling system as claimed in claim 2, wherein said control means is operative to control said drive means so that said second speed is less than said rst speed and is of such a magnitude that said workpieces may be stopped from said second speed within substantially the same predetermined distance regardless of the size of said workpieces.

4. A workpiece handling system as claimed in claim 1, further including second support means disposed adjacent said first support means, and displacement means for displacing said workpieces from said rst support means onto said second support means.

5. A workpiece handling system as claimed in claim 4, wherein said control means disposes a plurality of said workpieces on said irst support means in a. predetermined manner, said displacement means is operative to substantially evenly distribute said workpieces upon said second support means.

6. A workpiece handling system as claimed in claim 5, wherein there is further included a means for heating said workpieces, with said second support means being disposed in a heat transferring relationship with said means for heating. l

7. A workpiece handling system as claimed in claim 1, including second support means disposed Vadjacent said rst support means, with said detection means sensing said workpieces at least at two points along said first support means, said second support means including at least two support members disposed transversely to said rst support means adjacent said rst and second points.

8. A workpiece handling system as claimed in claim 7, with said control means being responsive to said detection means for providing a delay time before activating said drive means to stop said workpieces at said prescribed distance from said points.

9. A workpiece handling system as claimed in claim 7, wherein said prescribed distance Varies as a function of said dimension of said workpiece.

10. A workpiece handling system as claimed in claim 1, wherein said prescribed distance is a constant distance.

References Cited UNITED STATES PATENTS 2,397,339 3/1946A Crosby 214-23 2,984,366 5/1961 Greller 214-11 3,242,342 3/1966 Gabar 214-11 3,254,778 6/1966 Marland et al. 214-18 3,280,950 10/1966 Magloire 198-127 XR ROBERT G. SHERIDAN, Primary Examiner U.S. Cl. X.R.