US2078220A - Control system - Google Patents

Description

April 1937- G. A. CALDWELL ET AL 2,078,220

CONTROL SYSTEM Filed May 11, 1932 3 Sheets-Sheet l I N V E N TO RS 6/600 /1. Ca/a rvel/ rye/e5 WITNESSES: f. a 2% WW TTO April 27, 1937.

G. A. CALDWELL ET AL 78,220

CONTROL SYSTEM 3 Sheets-Sheet 2 Filed May 11, 1.932

Patented Apr. :27, 1937 UNITED STATES PATENT OFFICE CONTROL SYSTEM Application May 11, 1932, Serial No, 610,530

12 Claims.

invention relates, generally, to control systemS d pparatus and it has particular relation to elec rical systems for controlling the operation of mills for the rolling of sheet material.

The object of our invention, generally stated, is to provide control apparatus for rolling mills which shall be simple, reliable and efficient in operation an readily and economically manufactured and installed.

The principal object of our invention is to provide for automatically controlling the operation of sheet rolling mills.

Another object of our invention is to provide for reducing to a minimum the time required to traverse a complete cycle of operation in a sheet rolling mill.

A further object of our invention is to provide for insuring a complete automatic cycle of operation of the mill after a cycle of operation has been initiated,

A still further object of our invention is to provide for automatically reversing the feeding means in a sheet rolling mill to a forward direction prior to the completion of a cycle of operation and after the manual control means is moved to the ofi position.

Other objects of our invention will, in part, be obvious and, in part appear hereinafter.

Our invention, accordingly, is disclosed in the embodiment hereof shown in the accompanying drawings, and comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the application of which will 'be indicated in the appended claims.

For a more complete understanding of the nature and scope of our invention, reference may be had to the following detailed description taken in connection with the accompanying drawings, in which:

Figure 1 is a view, in side elevation, of a sheet rolling mill of the type for which the control system of our invention is suitable.

Fig. 2 is a view, in top elevation, of the mill shown in Fig. 1, and showing in addition, the control cabinet; and,

Fig. 3 is a diagrammatic view of the electrical circuits which may be used in practicing the invention.

In general, the invention comprises a two-high rolling mill provided with rolls continuously rotatable in one direction only and having on opposite sides thereof passer and catcher tables.

: The tables are each provided with endless cons veyors which are driven by reversible electric motors.

The sheet on which a rolling operation is to be performed is positioned on the passer table and is fed by the conveyor thereon through the rolls and to the conveyor on the catcher table, As soon as the trailing end of the sheet leaves the passer table and the leading end arrives at the catcher table, circuits are set up which cause the conveyors on both tables to reverse after a predetermined time to move the sheet back toward the passer table.

In order to position the tables so that the sheet may be returned without passing it between the rolls and thereby necessitating their reversal, the tables are hinged and are provided with motors which serve to elevate the ends of the tables adjacent the rolls to a position where the rolls are cleared and the sheet may be returned to the passer table. The operation of the elevator motor individual to the catcher table, is initiated a predetermined time after the sheet leaves the passer table and after it has arrived on the catcher table. When the catcher table has been moved to a predetermined position, the elevator 25 motor individual to the passer table is energized and the passer table is elevated to receive the sheet as it is returned from the catcher table.

As soon as the trailing end of the sheet leaves the catcher table and the leading end arrives back on the passer table, circuits are completed which, after a predetermined time, cause the conveyors on both tables to reverse to the forward feeding direction A The elevator motor individual to the catcher table is energized a predetermined time after the sheet leaves the catcher table and arrives on the passer table and it is thereby lowered to the initial position. After the catcher table has been moved downwardly to a predetermined position, the elevator motor individual to the passer table is energized and the passer table is thereby returned to the initial position and the cycle of operation is repeated.

Sui-table limit switches and brakes are provided in conjunction with the elevator mechanisms for stopping the movement of the tables at the upper and lower limits of travel.

In order to provide for initiating the functioning of the apparatus in accordance with the movement of the sheet from and to the tables, trigger switches are located at the ends of the tables adjacent the rolls. These switches are positioned in the path of the sheet and serve to complete control circuits as long as the sheet is in engagement therewith.

The functioning of the entire control equipment is initiated by manual control means after the sheet is moved on the passer table to the position where the trigger switch individual to that table is operated to the closed position. In order to insure that a complete cycle of operation will be performed, even if the manual control means is released, contact segments are provided on the limit switch individual to the passer table whereby the manual control means is rendered ineffective to arrest the automatic. functioning of the apparatus after the passertable has started up and until it is returned to the initial position.

In the event that it is desirable .to stop the automatic functioning of the apparatus at the end of a complete cycle of operation, it is also desirable to stop the conveyor on the passer table and actually reverse it to prevent coasting and to bring the sheet to a position where it may be inspected by the operator. This function is accomplished by the use of a plugging relay which completes circuits for plugging the conveyor mtors for a predetermined length of time after the control system has been de-energized.

Referring now to Figs. 1 and 2 of the drawings, the apparatus there shown comprises a two-high rolling mill shown generally at II), which is provided with rolls II and I2. The rolls II and I2 may be rotated constantly in one direction through shaft I3 by means of a suitable source of power, not shown. The mill I 0 is provided with uprights I4 and I5 for mounting the rolls II and I2 and a bed-plate I6, upon which the apparatus to be hereinafter described is located.

In order to feed a sheet on which a rolling operation is to be performed to the rolls II and I2, a passer table, shown generally at IT, is provided on the left-hand side of the mill, while a catcher table, shown generally at I8, is provided on the right-hand side, as illustrated. The passer and catcher tables I! and I8 comprise side-members I9, 28, 2|, and 22, which are pivoted on shafts 25 and 26 that are journalled in pedestal bearings 21 and 28. The ends of the side-members adjacent the rolls II and I2 are secured together by means of cross-members 29 and 39, as shown.

In order to convey the sheet to the rolls II and I2, and to carry it away from them, the passer table II is provided with chains 33 and the catcher table I8 is provided with chains 34, which are driven by sprocket wheels 35 and 36, which are secured to shafts 25 and 26, respectively, as by means of set screws 31 and 38. The chains 33 and 34 are positioned near the rolls II and I2 by means of additional sprocket wheels 39 and 49 which are secured to shafts 4| and 42, respectively, by means of set screws 43 and 44. It will be observed that the shafts 4| and 42 are journalled in the side-members I9, 28 and 2|, 22 at the ends adjacent the rolls II and I2.

The chains 33 and 34 are driven respectively, in this instance, by means of a polyphase squirrel-cage passer chain motor 45 and a polyphase squirrel-cage catcher chain motor 46. The motors 45 and 46 are mounted on the bed-plate I6 and serve to drive the shafts 25 and 26 through the agency of pinions 41 and 48 which mesh respectively with gear- wheels 49 and 59 that are keyed by suitable means to the shafts 25 and 26.

As shown diagrammatically in Fig. 3 of the drawings, the motors 45 and 46 comprise squirrel-cage rotors 53 and 54 and field windings 55 and 56.

In order to control the operation of the mill in accordance with the movement of the sheet on the tables I! and I8, trigger switches 57 and 5B are mounted respectively on the cross-members 29 and 39, as illustrated. The trigger switches 5! and 58 may be of any suitable type which serve to complete an electrical circuit when the sheet, on which the rolling operation is being performed, engages therewith. These switches are also of a type which complete the electrical circuit when engaged from either direction by means of the sheet.

After the sheet has once passed between the rolls II and I2 and is received on the catcher table I8, it is desirable to so position the tables II and I8 that the rolls II and I2 are cleared, thereby permitting the return of the sheet to the passer table II on reversal of the chains 33 and 34. In order to elevate the tables I1 and I8 to the dotted positions shown in Fig. 1, elevator mechanisms, shown generally at 59 and 60, are provided.

The elevator mechanisms 59 and 69 comprise a polyphase squirrel-cage passer elevator motor 63 and a similar catcher elevator motor 64 which serve to rotate gear- wheels 65 and 66 through the agency of pinions 61 and 68, which mesh therewith, as shown. The gear-wheels 65 and. 69 are provided with pins 69 and III which are eccentrically located relative to the axis of rotation of the gear- wheels 65 and 66. Connecting rods II and I2 serve to transmit the motion of the pins 69 and ID to the tables II and I8. The connecting rods II and I2 are pivotally connected to the side-members I9 and 2| by means of suitable bolts I3 and I4, as illustrated.

It will be observed that a complete revolution of the gear- wheels 65 and 66 causes the tables I! and I8 to be raised from the position shown to dotted position and back again to the position shown.

As shown more clearly in Fig. 3 of the drawings, the motors 63 and 64 comprise squirrel-cage rotors I5 and I6 and field windings I1 and I8.

In order to arrest further operation of the passer and catcher elevator motors 83 and 64 at the upper and lower limits of travel, limit switches BI and 82. are provided. In addition, brakes, shown generally at 83 and 84, are provided, for insuring the stopping of the elevator mechanisms when the electrical controls are deenergized. The brakes 83 and 84 are provided with compression springs 85 and 86 for applying the brakes and with solenoids 81 and 88 for releasing them.

The electrical control equipment for the mill may be housed in the controller, shown generally at 89, which is a convenient location from which the operator may observe the functioning of the mill, and at the same time, be in a position to gauge the thickness of the plate after a complete cycle of automatic operation has been performed.

Referring now particularly to Fig. 3 of the drawings, the functioning of the apparatus is initiated by means of a master control switch 9| which serves to apply control energy from the conductors 92 and 93 which are connected to a suitable source of direct current through switches 94 and 95 and emergency stop switch 96.

The master switch 9!, in conjunction with the trigger switches 57 and 58, serves to energize a passer trigger relay 9I and a catcher trigger relay 99, depending upon the position .of the sheet in the mill.

The trigger relays 91 and 98 serve to energize respectively a chain-forward time-limit relay 99 and a chain-reverse time-limit relay I00, which in turn serve to energize respectively a chainforward motor relay IM and a chain-reverse motor relay I02.

It will be observed that the motor relays WI and I02 are arranged to connect the motors 45 and 46 to conductors I03, I04, and I05 in such manner that the energization of the motor relay I01 causes the motors 45 and 46 to rotate in one direction while the energization of the motor relay I02 energizes the motors to rotate in a reverse direction. The conductors I03, I04, and I05 may be connected by means of a switch I06 to a suitable source of three-phase alternating current.

The trigger relays 91 and 98 also serve to energize respectively a time-limit catcher elevator-up relay I01, and a time-limit catcher elevator-down relay I08 which in turn serve to energize respectively a catcher elevator brake relay I09 and a passer elevator brake relay I I0.

The brake relays I09 and H0 serve to energize the solenoids 81 and 88 respectively of the brakes 83 and 04, and at the same time, to energize respectively the passer elevator motor relay II I and the catcher elevator motor relay II2, which serve to connect their respective motors 63 and 64 to the conductors I03, I04, and I05.

As ,set forth hereinbefore, the upper and lower limits of travel of the tables I1 and I8 are controlled by means of the limit switches BI and 82. The limit switch III is provided with contact fingers II 3 through H8 and contact segments I I9, I20 and I 2I. The limit switch 82 is provided with contact fingers I22 through I29 and contact segments I30, I3I, I32, and I33. The functioning of the contact fingers and segments of the limit switches SI and 82 will be described in detail hereinafter.

In order to permit the plugging of the chain motors 45 and 46 to prevent coasting and to return the sheet to a position where it may be inspected after the master control switch 9I has been moved to the off position, a plugging timelimit relay I36 is provided, which serves to energize the motor relay IOI for a predetermined length of time after the switch 9'I has been operated to the off position.

The time-limit relays 99, I00, I01, I08, and I36 are of the type shown in Patent No. 1,753,983, issued to W. G. Cook, and assigned to the Westinghouse Electric and Manufacturing Company. These relays are each provided with a neutralizing coil I31 which may be connected in seriescircuit-relation and through a resistor I38 to the energized control conductors 92 and 93. The timing of each of the relays may be adjusted by means of rheostats I39, each of which serves to shunt the main winding I40 of the time-limit relays. Additional time-adjustment may also be secured by varying the tension of the springs I 4| by means of the nuts I42.

In order to illustrate the functioning of the apparatus described hereinbefore, a complete cycle of operation will be carried through in detail. It is assumed that a sheet is positioned on the passer table I1 and is in engagement with the trigger switch 51 and that the master control switch 0I has been depressed to the on position. The passer trigger relay 91 will then be energized.

The circuit for energizing the passer trigger relay 91 may be traced from the energized conductor 93 through conductor I43, contact members I44 of the master control switch SI, conductors I45 and I46, energizing Winding I41 of passer trigger relay 91, conductor I40, contact members I49 of the trigger switch 51 and conductors I and I5I to the energized conductor 92.

The energization of the passer trigger relay 9i causes the energization of chain forward timelimit relay 99 and time-limit catcher elevator-up relay I01, as set forth hereinbefore.

The circuit for energizing relay 99 may be traced from the energized conductor 93 through conductor I53, winding I40 of relay 99, conductor 154, contact members I55 of relay 91 and conductors I56 and I51 to the energized conductor 92.

The circuit for energizing relay I01 may be traced from. the energized conductor 93 through conductor I53, wind ng I40 of relay I01, conductor I58, contact members I59 of relay 91 and conductors I56 and I51 to energized conductor 92.

The energization of the chain-forward timelim-it relay 9.9 causes the energization of chainforward motor relay I 0I, which serves to connect the motors 45 and 46 to the conductors I 03, 404 and, I05 over obvious circuits, thereby causing the chains 33 and 34 to move in a forward direction.

The circuit for energizing motor relay I0! may be traced from the energized conductor 93 through conductors I53 and I60, contact members IGI of relay .99 which are now closed, conductors I62 and I63, winding l64 of relay I9I, conductor I05, closed contact members I66 of relay I00 and conductor I51 to energized conductor 92.

The energization of relay IOI serves to complete a holding circuit for itself which may be traced from the energized conductor 92, through conductor I61 and contact members J68 to conductor I53 and the circuit associated therewith, which has been previously traced. v

The sheet is then passed between the rolls ii and I2 and arrives on the catcher table IS, the leading end engaging the trigger switch 58 and the trailing end disengaging the trigger switch 51. The release of the trigger switch 51 de-energizes the passer trigger relay 91, which in turn causes the de-energization of the windings E40 of relays 99 and I01. However, the relays 99 and I01 do not permit their armatures to move to the de-energized position until the time has elapsed for which these relays are set.

The engagement of the sheet with the trigger switch 58 causes the energization of catcher trigger relay 98, which in turn causes the energization of the time-limit catcher elevator-down relay I03 and the chain reverse time-limit relay E00, as set forth hereinbefore.

The circuit for energizing trigger relay 98 may be traced from the energized conductor 93 through conductor I43, contact members i of the master control switch 9!, conductors M35 and I46, winding I69 of trigger relay 98, conductor I19,

' contact members I1I of trigger switch 59 and conmay be through conducrelay conducconductor I53, winding I 40 of relay I00, conductor I16, contact members I11 of relay 98 and conductors I15 and 151 to the energized conductor 92.

The energization of relay I00 partly completes a circuit for energizing the chain motor relay I02 to operate the chains in a reverse direction but which circuit is not entirely completed until the de-energization of the chain-forward time-limit relay 99. As soon as the chain-forward time-limit relay 99 ole-energizes after the time for which it has been set, the relay I02 is energized, the chainmotors 45 and 48 are plugged and the chains are caused to move in a reverse direction.

The timing of relay 99 is so adjusted that the sheet on which the rolling operation is being performed'has been moved completely on to the catcher table I8 before the chains 33 and 34 are reversed. The timing of relay I00 is adjusted so that, even if the trailing end of the sheet moves to disengage the catcher trigger switch 58, it will again be engaged before the relay I00 is de-energized.

The circuit for energizing motor relay I02 may be traced from the energized conductor 92 through conductor I51, contact members I18, of relay I00 which are now closed, conductor I19, winding I ofrelay I02, conductor I8I, contact members I82 of relay 99, which are now closed, conductor I 60 and conductor I53 to energized conductor 93.

The energization of motor relay I02 completes a circuit for locking itself in Which may be traced from the energized conductor 93, through conductor I83, and contact members I84 of motor relay I02 to conductor I8I and over a circuit which has previously been traced to energized conductor 92.

The operation of the elevator mechanisms will now be set forth. It is desirable that the catcher table be elevated a predetermined time after the trailing end of the sheet leaves the passer table I 1 but which time may be difierent from that desired for causing the reversal of the chains 33 and 34. As set forth hereinbefore, the passer trigger switch 51 is moved to the open position as soon as the trailing end of the sheet leaves the passer table I1. The trigger relay 91 is immediately deenergized and a predetermined time thereafter the relay I01 is de-energized, the time depending upon the adjustment of the relay. The de-energization of the time-delay catcher elevator-up release the brake 84 and to energize the catcher elevator brake relay I I0, which in turn serves to release the brake 84 and to energize the catcher elevator motor relay I I2 to connect the catcher elevator motor 64 to the power source over an obvious circuit.

The circuit for energizing the catcher elevator brake relay I I 0 may be traced from the energized conductor 92 through conductor I51, contact members I85 of relay I01, which are closed a predetermined time after the sheet leaves the passer table I1, conductor I89, contact finger I22, contact segment I30 and contact finger I 23 of the limit switch 32, conductor I81, winding I88 of the catcher elevator brake relay H0 and conductor I89 to the energized conductor 93.

The circuit for energizing the catcher elevator brake may be traced from the energized conducto-r 92 through conductor I5I, contact members I 90 of relay I I 0, conductor I9I, solenoid 88 of the brake 84 and conductor I92 to energized conductor 93.

The circuit for energizing motor relay I I2 may be traced from the energized conductor 93 through conductors I 92 and I93, winding I 9 1 of relay II2, conductor I95, contact members I96 of brake relay IIO to conductor I91 and thence through a circuit which has previously been traced to the energized conductor 92.

The energization of the catcher elevator motor 64 causes the catcher table I8 to be elevated to a position to clear the rolls I2 and I3, as indicated by the dotted position. At the same time, the limit switch 82 is rotated in the direction indicated by the arrow, and contact segment I32 is moved after the catcher table I8 has been moved to a predetermined position to complete a circuit for energizing the passer elevator brake relay I09.

The energization of brake relay I09 causes the energization of the passer elevator motor relay III and in turn the energization of the passer elevator motor 63.

The circuit for energizing the passer elevator brake relay I09 may be traced from the energized conductor 92 through conductors I91 and I91, contact finger I21, contact segment I32, contact finger I26, conductor I98,'contact finger I13, contact segment II9, contact finger I14, conductor I99, winding 200 of relay I09, and conductor I92 to energized conductor 93.

The circuit for energizing the solenoid 81 of the passer elevator brake 83 may be traced from the energized conductor 92 through winding 81 of the brake 83, conductor 20I, contact members 202, of the passer elevator brake relay I09, and conductor I92 to the energized conductor 93.

The circuit for energizing the passer elevator motor relay I II may be traced from the energized conductor 93 through conductors I92 and 203, winding 204 of motor relay IIl, conductor 205, contact members 206 of brake relay I09, and through conductor I99 and over a circuit previously traced to the energized conductor 92.

Both elevator motors 63 and 94 are now energized and the tables I1 and I8 are elevated to the dotted positions shown in the drawings. After the upper limit of travel is reached, the contact segments II9 and I30 of the limit switches 81 and 82 respectively, open the circuits to brake relays I09 and H0, respectively, thereby de-energizing the motors 63 and 60 and applying the brakes 83 and 8 3. The contact fingers of limit switches 8I and 82 may now be considered to be in the position shown by the dotted lines A and B, respectively.

During the time when the tables I1 and it are being elevated the chain motors 45 and 05 are operating the chains 33 and 30 in the direction to return the sheet from the catcher table i 8 over the top of the roll I2 to the passer table I1. The operation of the chains 33 and 34 is so arranged that a minimum amount of time is utilized in returning the sheet to the passer table I1, and by the time the catcher table I8 is in the full up position, the sheet is partly over the roll I2.

The former trailing end of the sheet has now become the leading end and when it engages the passer trigger switch 51 and returns to the passer table I1, the passer trigger relay 91 is again energized, whereupon the chain-forward time-delay relay 99 and the time-limit catcher elevatorup relay I 01 are energized over circuits which have previously been traced.

The trailing end of the sheet on leaving the catcher table I8 releases the catcher trigger switch 58 and thereby de-energizes the catcher trigger relay 98. The de-energization of relay 98 initiates the de-energization of relays I08 and I00, which occurs after the time for which they have been set.

After a predetermined time, the chain-reverse time-limit relay I00 is de-energized, thereupon de-energizing chain-reverse motor relay I02 and completing a circuit for energizing chain-forward motor relay IOI which has previously been traced. The chains 33 and 34 thereupon reverse and again feed the sheet toward the rolls II and I2.

After the time has elapsed for which relay I08 has been set a circuit, which has previously been traced, will be completed for again energizing the catcher elevator brake relay IIO. Energization of brake relay IIO releases the brake 84 and causes the energization of catcher elevator motor relay II2 to energize the catcher elevator motor 64 and initiate the movement of the catcher table I8 to the downward position.

The circuit for again energizing relay IIO may be traced from the energized conductor 92 through conductor I51, contact members 201 of relay I08 which are now closed, conductor 208, contact finger I25, contact segment I3I, contact finger I24, conductor I81, winding I88 of relay III], and conductor I89 to the energized conductor 93.

The circuits for energizing the brake 84 and the motor relay IIZ have previously been traced and will not be repeated.

The downward movement of the catcher table I8 causes the movement of the limit switch 82 in the direction of the arrow, as previously set forth, so that at a predetermined position, the contact segment I33.bridges the contact fingers I20 and I29. A circuit is then completed for energizing the passer elevator brake relay I09 and thereby causing the release of the passer elevator brake 83 and the energization of passer elevator motor relay I I I to energize passer elevator motor 63. The passer table I1 is then caused to move in a downward direction.

The circuit for again energizing the passer elevator brake relay I09 may be traced from the energized conductor 92 through conductors I51 and I91, contact finger I28, contact segment I33, contact finger I29, conductor 209, contact finger IIG, contact segment I20, contact finger II5, conductor I99, winding 200 of relay I09 and conductor I92 to energized conductor 93.

The circuits for energizing the passer elevator brake 83 and the passer elevator motor relay III have been previously traced, and will not be repeated.

The passer and catcher tables I1 and I8 continue to move in a downward direction until further movement thereof is arrested on operation of their respective limit switches 8I and 82, whereupon the brakes 83 and 84 serve to stop the tables in the full downward position. Meanwhile, the chains 33 and 34 have been moved in a forward direction and the sheet is again passed between the rolls II and I2 and theforegoing operations are again repeated.

The timing of the relays 99, I00, I01 and I08, is so adjusted as to utilize a minimum time for carrying out a complete cycle of movement of the sheet from the passer table to the catcher table and back to the passer table. The timing may be so adjusted that the sheet barely clears the roll I2 as the tables are moved upwardly or downwardly so that after the central position of the roll is reached, the end of the sheet adjacent the roll follows, in general, the contour of the roll.

In the event that the operator wishes to gauge the thickness of the sheet, it is desirable that the sheet be returned to the initial position for convenience. In order to utilize a minimum time for the gauging operation it is desirable to operate the master control switch 9i to the off position while still continuing the automatic cycle of operation until the sheet is returned to the passer table H where it may readily be gauged. The operator may then leave his normal position after moving the master switch to the oif position and approach the passer table I1 to which the sheet will be returned and which will be lowered to the initial position.

In order to insure that a complete cycle of operation will be performed after the passer elevator has moved upwardly, a predetermined distance, the contact segment IZI is provided on the limit switch BI. It will be observed that this contact segment completes a shunt circuit around the master switch 9! and renders it ineffective to de-energize the control apparatus until the catcher table I1 is again in the downward position.

The circuit which lay-passes the master control switch 9| may be traced from the energized conductor 93- through conductors I53 and 2I0, contact finger II8, contact segment IZI, contact finger II1, conductors 2, I46 and I45, to the contact members I44 of the master switch 9|.

It has been found that on the de-energization of control apparatus due to the movement of the master switch 9| to the off position in order to stop the automatic functioning of the mill, there is a tendency for the chains 33 and 34 to coast in the direction that carries the sheet away from the rolls II and I2. In order to prevent this coasting it is desirable to plug the chain motors 45 and 46 for a short interval of time and in some instances, to cause the actual reversal of the chains 33 and 34 to bring the sheet to a position where it may be readily inspected.

In order to accomplish the plugging operation, the plugging relay I36 is provided, as hereinbeiore set forth, and is energized on the energization of the chain-reverse time-limit relay I00.

The circuit for energizing relay I36 may be traced from the energized conductor 93 through conductor I53, winding I40 of relay I36, conductor I19, contact members I18 of relay I00 and conductor I51 to energized conductor 92.

The energization of the plugging relay I36 shunts the contact members ISI of relay 99 but causes no further operation until the de-energization of relay I00. On the de-energization of relay I00 and in the event that relay 99 is not energized, the relay I36 serves to plug or reverse the operation of the chain motors 45 and 46, depending on the time for which the relay I36 is set. It will be observed that during the normal operating cycle the relay I36 serves merely to shunt the contact members IGI which are already closed, and therefore, it does not effect the functioning of the system, except under the conditions previously set forth.

The circuit for shunting the contact members I6I may be traced from conductor I53 through contact members 2I2 of the plugging relay I36 and conductor 2I3 to conductor I62.

In the event that it is desired to operate the chain motors 45 and 46 in either a forward or a reverse direction, independent of the automatic control system, push-button switches 2M and 2I5 are provided.

The circuit for energizing motor relay IOI to operate the chains in a forward direction manually may be traced from energized conductor 93 through conductor I92, contact members 2H5 of switch 2M, conductor I63, winding I64 of relay IDI, conductor I65, contact members I66 of relay I99 and conductor I51 to energized conductor 92.

. The circuit for energizing motor relay I02 manually to operate the chains in a reverse direction may be traced from the energize-d conductor 92 through conductor I5I, contact members 2!! of switch 2I5, conductor I19, winding I89 of relay I92, conductor I8I, contact members I82 of relay 99 and conductor I53 to energized conductor 93.

In like manner the brake relays I99 and H0 may be manually controlled independently of the automatic control features to operate the elevator motors 63 and 64 as desired by means of push-button switches 2I9 and 229.

The push-button switch 2I9 controls the operation of the passer elevator brake relay I99 over a circuit which may be traced from energized conductor 92, contact members 22! of switch 2I9, winding 209 of relay I 09 and conductor I92 to energized conductor 93.

The switch 229 controls the operation of the catcher elevator brake relay IIO over a circuit which may be traced from energized conductor 92 through conductor I5I conductor 222, contact members 223 of switch 220, winding I88 of relay H0, and conductor I89 to the energized conductor 93.

Since certain further changes may be made in the above construction and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. In a control system for sheet rolling mills provided with a plurality of rolls, in combination, a passer table and a catcher table disposed on opposite sides of the rolls, motor-operated feeding means on the passer table for passing the sheet between the rolls, motor-operated receiving means on the catcher table for conveying the sheet away from the rolls after a rolling operation has been performed, motor-operated elevating means individual to each table for operating the tables to a raised position to clear the rolls, a trigger switch on each table disposed to be actuated by the sheet passing thereover, control means responsive to the trigger switches for effecting the reverse operation of the motoroperated feeding and receiving means and initiating the movement of the motor-operated elevating means individual to the catcher table to the clear position a predetermined time after the sheet leaves the passer table and after it arrives on the catcher table, and control means actuated by the motor-operated elevating means of the catcher table for initiating the functioning of the motor-operated elevating means individual to the passer table after the catcher table is moved a predetermined distance from either its initial or raised position, the first-named control means also being disposed to effect the forward operation of the feeding and receiving means and initiating the movement of the elevating means individual to the catcher table to the initial position a predetermined time after the sheet leaves the catcher table and after it arrives on the passer table.

2. In a control system for sheet rolling mills provided with a plurality of rolls, in combination, a passer table and a catcher table disposed on opposite sides of the rolls, feeding means on the passer table for passing the sheet between the rolls, receiving means on the catcher table for conveying the sheet away from the rolls after a rolling operation has been performed, elevating means individual to each table for operating the tables to a position to clear the rolls, control means for effecting the reverse operation of the feeding and receiving means a predetermined time after the sheet leaves the passer table, additional control means for initiating the operation of the elevating means a predetermined time after the sheet leaves the passer table, and switch means operable in accordance with the movement of the elevating means for arresting further movement thereof after a predetermined movement, the first-mentioned control means being disposed to effect the forward operation of the feeding and receiving means a predetermined time after the sheet leaves the catcher table and the second-named control means being disposed to initiate the movement of the tables to the initial position a predetermined time after the sheet leaves the catcher table.

3. A control system for sheet rolling mills provided with a plurality of rolls and passer and catcher conveyor tables on opposite sides of the rolls for handling the material comprising, motor-operated elevating means individual to each table, a motor for driving the conveyor on each table, control means including a trigger switch on each of the tables for the motor-operated elevating means and the conveyor motors operable when initiated into operation to effect a pre determined cycle of operation thereof which comprises operating the table conveyors in the same direction with the tables in one position to pass the material through the rolls, reversing the direction of operation of the conveyors and initiating the operation of the catcher table elevating means at the expiration of a predetermined time after the material leaves the passer table and arrives upon the catcher table, initiating the operation of the passer table elevating means after the catcher table has moved a predetermined distance, stopping both the catcher and passer tables in a different predetermined position to cause the material to be passed back to the passer table, again reversing the direction of operation of the conveyors and again initiating the operation of the catcher table elevating means at the expiration of a predetermined time after the material leaves the catcher table and arrives upon the passer table, initiating the operation of the passer table elevating means after the catcher table has moved a predetermined distance toward its original position and stopping both the passer and catcher tables in their original positions, and a manually-operable switch for initiating the operation of the control means.

4. In an automatic control system for a sheet rolling mill provided with a plurality of rolls in which a complete automatic cycle of operation comprises passing the sheet through the rolls and returning it to be passed through again, in combination, passer means and catcher means for feeding the sheet to and receiving it from the rolls, elevating means for positioning the passer and catcher means, control means operable to effect the sequential operation of the passer and catcher means and the elevating means to produce a complete automatic cycle of operation,

manually operable means for initiating the operation of the control means, and additional control means for rendering the manual means ineffective to arrest the cycle of operation until the sheet is returned to the initial position.

5. In a system for automatically controlling the operation of the feeding mechanism for a sheet rolling mill provided with a plurality of rolls, in combination, a passer table and a catcher table disposed on opposite sides of the rolls, feeding means on the passer table for passing the sheet between the rolls, receiving means on the catcher table for conveying the sheet away from the rolls after a rolling operation has been performed, elevating means individual to each table for operating the tables to a position to clear the rolls, adjustable timing means for initiating the functioning of the elevating means and of the feeding and receiving means in a reverse direction a predetermined time after the sheet leaves either of the tables and after it arrives on the other table, control means operable in accordance with the movement of the elevating means for arresting further movement of the elevating means after a predetermined movement thereof, manually-operable means for initiating the functioning of the timing means, and means for rendering the manual means ineffective to arrest the functioning of the feeding mechanism until after a predetermined cycle of operation has been performed.

6. In an automatic control system for sheet rolling mills provided with a plurality of rolls, in combination, a passer table and a catcher table disposed on opposite sides of the rolls, feeding means on the passer table for passing the sheet between the rolls, receiving means on the catcher table for conveying the sheet away from the rolls after a rolling operation has been performed, elevating means individual to each table for operating the tables to a position to clear the rolls, timing means for initiating the functioning of the elevating means and f the feeding and receiving means in a reverse direction a predetermined time after the sheet leaves either of the tables and after it arrives on the other table, control means operative in accordance with the movement of the elevating means for arresting further movement of the elevating means after a predetermined movement thereof, manually-operable means for initiating the functioning of the timing means, and automatic means for independently causing the operation of the feeding means to feed the sheet toward the rolls prior to completion of a cycle of operation and after the manually operable means has been operated to the initial position.

7. In an automatic control system for sheet rolling mills provided with a plurality of rolls, in combination, a passer table and a catcher table disposed on opposite sides of the rolls, feeding means on the passer table for passing the sheet between the rolls, receiving means on the catcher table for conveying the sheet away from the rolls after a rolling operation has been performed, elevating means individual to each table for operating the tables to a position to clear the rolls, timing means for initiating the functioning of the elevating means and of the feeding and receiving means in a reverse direction a predetermined time after the sheet leaves either of the tables, control means for arresting further movement of the elevating means after a predetermined movement thereof, manually-operable means for initiating the functioning of the timing means, means for rendering the manual means ineffective to arrest the functioning of the feeding mechanism until after a predetermined cycle of operation has been performed, and automatic means for independently causing the operation of the feeding means to feed the sheet toward the rolls prior to the completion of a cycle of operation and after the manuallyoperable means has been operated to the initiated position.

8. In an automatic control system for sheet rolling mills provided with a plurality of rolls, in combination, a passer table and a catcher table disposed on opposite sides of the rolls, feeding means on the passer table for passing the sheet between the rollareceivirlg means on the catcher table for conveying the sheet away from the rolls after a rolling operation has been performed, elevating means individual to each table for operating the tables to a position to clear the rolls, timing means for initiating the functioning of the elevating means and of the feeding and receiving means in a reverse direction a predetermined time after the sheet leaves either of the tables and. after it arrives on the other table, control means operative in accordance with the movement of the elevating means for arresting further movement of the elevating means after a predetermined movement thereof, manually-operable means for initiating the functioning of the timing means, means for rendering the manual means ineffective to arrest the functioning of the feeding mechanism until after a predetermined cycle of operation has been performed, and automatic means for independently causing the operation of the feeding means to feed the sheet toward the rolls prior to the completion of a cycle of operation and after the manually-operable means has been operated to the initial position.

9. In a control system for sheet rolling mills provided with a plurality of rolls and passer and. catcher conveyor tables on opposite sides of the rolls movable between lower and upper positions, a motor for driving the conveyor on each table, motor-operated elevating means for each table, a trigger switch on each table disposed to be actuated by the material passing thereover, timing means controlled by said trigger switches for reversing the direction of operation of the conveyor motors and initiating the operation of the elevating means on the catcher table at the expiration of a predetermined time interval after the material leaves either of the tables and arrives upon the opposite table, means actuated in accordance with a predetermined movement of the catcher table in either direction for initiating the operation of the elevating means on the passer table and for further controlling the motor-operated means on the catcher table to stop said table after a predetermined movement thereof in either direction, and switch means actuated in accordance with the movement of the passer table in either direction for further controlling its motoroperated elevating means to stop said table after a predetermined movement in either direction.

10. In a control system for sheet rolling mills provided with a plurality of rolls, in combination, a passer table and a catcher table disposed on opposite sides of the rolls, feeding means on the passer table for passing the sheet between the rolls, receiving means on the catcher table for conveying the sheet away from the rolls after a rolling operation has been performed, elevating means individual to each table for operating the tables to a position to clear the rolls, adjustable timing means for initiating the functioning of the elevating means individual to the catcher table and of the feeding and receiving means in a reverse direction a predetermined time after the sheet leaves either of the tables and after it arrives on the other table, and control means operable in accordance with the movement of the elevating means individual to the catcher table for initiating the functioning of the elevating means individual to the passer table and for arresting further movement of the elevating means individual to the catcher table after the catcher table is moved to a predetermined position.

11. In a control system for sheet rolling mills provided with a plurality of rolls, in combination, a passer table and a catcher table disposed on opposite sides of the rolls, feeding means on the passer table for passing the sheet between the rolls, receiving means on the catcher table for conveying the sheet away from the rolls after a rolling operation has been performed, independently-operable elevating means individual to each table for operating the tables to a position to clear the rolls, time delay control means for effecting the reverse operation of the feeding and receiving means and initiating the functioning of the elevating means of the catcher table a predetermined time after the sheet leaves the passer table and after it arrives on the catcher table, and control means actuated by the catcher table elevating means for initiating the operation of the passer table elevating means and for arresting further movement of the catcher table elevating means after the catcher table has moved a predetermined distance, control means actuated by the passer table elevating means for arresting further movement thereof after the passer table has moved a predetermined distance, the first-mentioned control means being adapted to again effect the forward operation of the feeding and receiving means and to initiate the movement of the catcher table elevating. means to the initial position a predetermined time after the sheet leaves the catcher table and after it arrives on the passer table, and the second-mentioned control means being adapted to again initiate the operation of the passer table elevating means to return it to the initial position.

12. In a system for automatically controlling the operation of the feeding mechanism for a sheet rolling mill provided with a plurality of rolls, in combination, a passer table and a catcher table disposed on opposite sides of the rolls, feeding means on the passer table for passing the sheet between the rolls, receiving means on the catcher table for conveying the sheet away from the rolls after a rolling operation has been performed, elevating means individual to each table for operating the tables toa position to clear the rolls, adjustable timing means for initiating the functioning of the elevating means and of the feeding and receiving means in a reverse direction a predetermined time after the sheet leaves either of the tables, control means for arresting further movement of the elevating means after a predetermined movement thereof, manually operable means for initiating the functioning of the timing means, and means for rendering the manual means ineffective to arrest the functioning of the feeding mechanism until after a predetermined cycle of operation has been performed.

GLENN A. CALDWELL. GEORGE R. SHAW.

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