US1751245A - Manipulator pusher head - Google Patents

Description

March 18, 1930.v P. McsHAN 1,751,245

MANIPULATOR PUSHER HEAD Filed Aug; 13, 1927 INVENTOR Phe/an- Mc Shane V evident from the following detailed descrip- Patented Mar. 18, 1930 res PHELAN MGSHANE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA MANIPULATOR PUSHER HEAD Application filed August 13, 1927. serial No. 212,619. 1

This invention relates generally to control systems and more particularly to control systems for manipulator pusher heads for rolling mills. I j

The object of the invention, generally stated, is the provision of a control system which shall be simple and efficient in operation, readily and economically manufactured and installed and in which provision'for improving the operation of this type of machine is made by reducing the abusive action imposed upon the motor.

A more specific object of the invention is to provide for utilizing the counter electromotive force developed in a motor to control the variation of resistance in the motor circuit, to assure that suflicient resistance is connected in series with the motor to protect it when it is stalled by the jamming of the pusher head.

Another object of the invention is to provide for the connecting ofa resistor in series with a pusher head actuating motor after it has been accelerated and before it is stalled by the jamming of the pusher head.

Other objects of the invention will become tion taken in conjunction-with the accompanying drawing, in which:

Figure 1 is a view inend elevation of a steel rolling mill of a type suitable for the application of the present control system.

Fig. 2 is a diagrammatic view of the main and auxiliary circuits of a control system connected in accordance with the invention.

Referring now to Fig. 1 of the drawing, the structure here shown comprises a wellknown type of rolling mill, provided with a roll table 5 having the usual stands or end supports 6 for the table rollers 7. As shown, the rollers are actuated by thebevel gear arrangement 8 which may be driven in any suitable manner (not shown).

In order to position stock such as ingots or billets, etc., on the table, a pusher head'9 and the required actuating mechanism 11 is provided. As shown, the pusher head 9 is carried by a horizontal beam 12 which is operated by means of a rack and pinion drive comprising m mbers 14 and 15. The movement'of the pusher head is in a plane pan allel to the top of the table 5, from thefull open position as shown to the full closed position near the opposite side of the roll table 5. As is the usual practice, an electric motor 16 is utilized for operating the rack and pinion A cam switch 22, here shown connected to the reduction gear train 17 is provided for the purpose of limiting the travel of the pusher head in either the forward or reverse directions and to control various other control circuits in a manner which will be described, hereinafter.

Referring to Fig. 2, the system shown comprises a, pusher head actuating motor 16 having a series field winding 23. The cam switch 22 is shown as geared directly to the motor shaft, although it is to be understood that this switch may also be operated from anyv shaft contained within, the gear case 17 or from any shaft which bears a definite relation to the position of the pusher head. As will be noted, the cam switch 22 comprises a plurality of cam members 24 to 27, inclusive, mounted upon a common shaft and disposed to operate a plurality of switches 28 to 31, inclusive. The gear arrangement which drives the camshaft is designed to effect one complete revolution of the cams as the pusher head travels from the open to the closed position, or'vice'versa, the

purpose being to complete at a predetermined time certain control. circuits which will be described hereinafter. V p

1 In the control system a pluralityof re Versing switches 32 to 35, inclusive, are provided and disposed to be employed to reverse the armature connections. of the motor 16.

A dynamic braking contactor 36 is also provided to establish a dynamic braking circuit ,for the motor 16 at the full open position of the pusher head. In addition, the operation of the contactor 36 effects the operation of a maincontactor 37 'wh1ch,'as Wlll beobserved, is connected 111 series relation to the res stor 38 and series field winding 23 and constitutes a means of effecting a final connection of the motor to" the negative power conductor 39 after'the proper reversing'contactors have are disposed mbebridgea by the movable segment 46, is provided for controlling the'op erationof the reversing contacto'rs 32- to 35, inclusive, and to establish various other control circuits" which will be described hereinafter.

Assumingthat it-is desired to effect the forward operation of the pusher head, the master switch 41 is actuated to the forward position, bridging the stationary contact members -42'and 43'with the movable contact segments, which establisheslan operating circuit'for thereversing'contactors '32 and 33, which extends'froi'nthe, positive conductor 7 47, conductor 48, contact member 42, conductor 49, cam switch contact member 28, which is closed,condu c tor 51, coil'52 of the reversing contactor 33, conductor'53, coil 54' of the contactor 32, conductor 55 to the negative conductor 39. 7

It will also be noted that. upon the operation of the master controller 41 a second energizing circuit is established to efi'ect the 3 operation of a contactor 56, and which extends from the positive conductor 47, conductor48, master switch contact member 42, conductor 49, limit switch contact member 28,

' conductors 51 and 57, coilI58 of contactor 56,

doctor 391 a Inthis instance the contact members of relay 56 are connected in parallel relation to the cam-operated contact members 31 which stand openwhe'n the pusher head is in its full open position, insuring that a control cir- (suit for effecting the forward operation of the pusher head can always'be obtained regard'less of theposition of the cam switch.

Theclosure of contactor 56 establishes a circuit which extends from the positive conductor 47, conductor 62," theclose'd' contact memberof contactor 56, conductor 63, operafting "coil- 64 of the dynamic braking con tactor 36to t hejnegative"oondiictorf39i* This a'fre'ctstheoperation'ofthedynamicbraking anteater 36 which opens contact members conductors59, 61 and to the negative conber 43.,conductor 68, contact member 67, conduotor 69., coir71Ofthemainicontactor 37,

to the negative conductor 39. p v The closure of the main contactor 37 closes the main motor circuit which was partially established by the operation of the reversing contactors 32 and 33 and which extend from thepositive conductor 47, through conductors 72 and 7 3, contactmember74' of there 'versing contacto'r 32, conductors 7 5' and 76 to the motor terminal designated as 77, through the armature winding, terminal 7.8, conductors 79 and 81,"switch 33, conductor 82,"series field winding 23, conductor 83, se ris'resister 38, main contactor 37 to the nega' tive conductor 39. V

In accelerating the'motor 16 provision is made for short-circuitinga portionbitthe resistor 38. In order that the acceleration may be automatically controlled when the motor is started, a relay '84 which is responsive to the counter ele ctromotive force devel oped in the motor is providedfor controlling th'ea'ctu'ating circuit of'relay85 which is disposed to' sho rtcircuit a portionof-the re sister 38. I

hen the motor is started, the actuating coil of the" relay 84 issubjecte'd-toa" voltage since it isdirectly connected across the armature. Iti's'well understood that thecounterelectromoti've force of direct current motor is developed gradually as the motorstarts tromiest and is accelerated to fullspee'd',

The actuating coil of the relay 84 whichfis disposed to respond to a low value ofcounter-electromotive 'force voltage and may be energized sufficiently toeffect the operation cf the relay and thus close the contact membore 36 which arenormally biased to their open nositionsby means of the spring 87 The closure of contact Inembers86' establishes an energizing circuit for theshort circuiting 'c'onta'ctor' 85, which extends from thepositive conductor 47, through co'nduo tors 62 and 88, Contact members 860i the counter el'e'ctromotiveforce relay 84, conductor 89, contact member 91 of relay 92, conductor 93, coil 94 ofshort-circuiting contactor 85', to the negative conductor 39. r

1 The closure of the short-circuiting contactor8'5 thereby short-circuits a portion of the resistor 38 and the motor 16 'acceleratesto fullsp'ee'd.

closed position to move any billet that may Damned by rolisi At a' 'predetermlind pb nt in the cycle'of operation fthe pusher head 9 is being actuated toward the sition the movement of the billetwill be sud-' denly stopped by the oppositely disposed pusher head 18, thus causingtheactuating motor 16 to be stalled. Unless provision has been made for limiting the currentdrawn by the actuating motor, before jamming of the pusher head 13 occurs, said current Will rise to an excessive and dangerous value in the motor circuit which would, unless interrupted quickly, have a destructive eflect upon the motor windings.

In order to protect the motor, .provisionis made for connecting a resistor in series with it. Therefore, before the jamming of the pusher head occurs, a resistor 38 is connected in the motor circuit.

It will be noted that a second relay 92 was utilized in establishing the energizing circuit for the short-circuiting contactor 85.

The relay 92 is provided with an operating coil 95 which is also connected directly across the motor terminals, and is, therefore, disposed to be energized by the counter electromotive force of the motor. When the actuating motor 16 has reached approximately full speed and the developed counter-electromotive force has reached such a value as to effect the operation of the relay 92, thus opening the contact members'91 which were biased to the closed position by means of the spring 96. 7 Upon the operation of the relay 92 the energizing circuit of the short-circuiting contactor 85 is interrupted and it drops open, thereby inserting the total amount of the resistor 38 in the motor circuit before the motor is stalled.

It will readily be'seen that the amount of time occurring between the starting and stalling of the motor 16 is sufficient for the relay 92 to function in the manner described hereinbefore, thus insuring that a current limiting resistor is in the-motor circuit, which resistor has little effect until the motor is suddenly stalled.

The counter-electromotive force relays 84 and 92, when functioning in the proper manner, utilize a common resistor 38 for the purpose ofaccelerating the motor and for automatically protecting the motor when it is stalled.

After the motor is stalled, the operator either returns the controller to the off position or to the reverse position to either maintain the pusher head 9 in engagement with a billet or to return it to the full open' position.

Assuming that the pusher head is to be returned to the full open position, then the controller 41 is actuated to the reverse position, which action effects the bridging of contact members 44 and 45 of the master controller 41 by the movable segment 46 and establishes an operating circuit for the reversing contactors 34 and 35, which are disposed members 29 which are now in engagement,

conductor 98, Where aparallel circuit is es tablishechone branch extending through conductor 99, coil 101 of the contactor 35, conductor to the negative conductor 39. 1 The other branch extends from energized conductor 98 through conductor 102, coil 103 of the contactor 34, conductors-61 and 55 to the negative conductor 39. I

In this instance the limit switch contact members 31 are in' engagement having been closed by the cainmember 27 immediately after the pusher head 9 is moved from thej-full open position as described hereinbefore. I

Therefore the operating circuit for the dynamic braking contactor 36 Which was enengized before the reversing occurred, remains energized, thus the contact members 67 of the contactor 36 are maintained in the closed position. g y

As mentioned hereinbefore, the operating circuit for themain contactor 37 may be established only when the contact members 67 of therelay 36 are in engagement. Therefore, upon the actuation of the master controller 41 to the reverse position, the operating circuit for the'main contactor 37 is established, which extends from the positive conductor 47, through conductor 48; the movable segment 46 and contact finger 44, conductor 68, the closed contact members 67of the contactor 36, conductor 69, coil 71 of the main contactor 37 to the negative conductor 39.

Thus, the reversing contactors 34 and 35 and the main contactor 37 are closed simultaneously, which establishes the main motor circuit extending from the positive conductor 47, through conductor 72, contactor 34, conductor 79, armature terminals 78 and 77, conductors 76, 105 and 106, contactor 35, series field winding 23, conductor 83, resistor 38, main contactor 37 to the negative conductor39. The motor 16 operates in the reverse direction with the full amount of resistor 38 in the circuit. r

The counter-electromotive. force relays 84 and 92 again function in the manner described hereinbeforeto' short-circuit aportionof therresistor 38, thus quickly accel eratingthe motor to the full speed and again inserting the full amount of resistance in series with the motor-after it has reached full speed in the reverse direction.

When the pusher head is nearing the full U open position, it is desirable to slow the motor down to some extent, therefore, at a point near the tullopen position of the pusher head-the" cam switch contact members are closed by "the" action ofj the cam 26 which establishes an energizing circuit for the armature shunt slow down conta'ctor 108, which,

In this manner the speed of the motor isreduced automatically as the pusher head nears the full open position. At the full 7 Openassion the cam switch contacts'30 are again opened, which deenergizes the armature shunt slow-down contactor 108' and interrupts the armature shunt circuit.

In this embodiment of the invention to providefor quickly stopping the pusher head inthe full open position, dynamic'braking is resorted to; Therefore, a dynamic braking circuit is established by reason of the fact tliatthe cam switch 31 has opened and deenergized the operating coil 64: of the dynamicbi'aking contacto'r 36, permitting contact members65 and'66 to drop to their closed position. o

'As will be noted, thedyna mic braking circuit extends from terminal 77, or themotor 16, through conductors 7 6, 105 and 106, contact member 65 of the dynamic braking contactor 36, conductor 115, resistor 38, series cfieldiwinding'23, conductor 83, contact members 66, conductors116, 113 and 79 to'the terminal 7 8 of the motor 16.

,When the contact members 65 and66 of the dynamicbraking contactor 36 were closed,

contact member 67 was opened and the energlzlng circuit for the operating coil 71 of the mainline contactor 37 opened, which en-' tirely disconnects the motor from the line even though the control handle is still maintained in the reverse positionQ *Dynamic braking is thus automatically effected to stop the pusher head in the full open position irrespective of the position of the master controller 41.

It is not intended that the invention be restricted to the structural details, circuit connections or arrangement of parts herein shown and described, since it will be readily understood that various modificationsithere of may be made without departing fromthe spirit and scope of my invention.

I claim as my invention:

1. In a rolling mill, in combination, a manipulator pusher head, a motor for actuating the pusher head; a resistor disposed to" be connected in series with themotor, and means responsive ,to the counter-electromotive force of themotor for connecting the resistor in series withthe motor before it is stalled by the stopping of the pusher head.

* '2. In a rolling mill, in combination, a manipulator pusher head, a motor for actuating the pusher head, a resistor for controlling the current flowing in the motor, switches for short-circuiting the resistor, actuating coils for said switches, said actuating coils being connected across the motor and being responsive to the counter-electromotive force de- 1 veloped'by the motor, and adapted to operate the switches upon different voltages to'vary the resistance in series with the motor during starting and acceleration and to provide resistan'ce in series with the motor before it is trolling the coil energizing circuit, a plurality of operating coils for the relays, said operating 'coils being connected acrossthe motor armature windings and being responsive to the counter-electromotive force generated by the motor to operate said relays to control the switch coil energizing circuit to vary the resistance in series with the armature "and series field windings during the starting and acceleration periods, and to provide resistance in series with the armature andseries field windings before the motor is stalled by the jamming of the pusher head.

4. Ina rolling mill, in combination, a manipulator pusher head,a motor for actuating the pusher head, said motorhaving a series'field and armature winding, a resistor to control the current flowing in the series field and armature windings, a switch for short-circuiting a portion of the resistor, an actuating coil for said switch, an energizing circuit for the actuating coils and relays connected in series disposed for controlling said energizing circuit, an operating coilfor each relay, said operating coils being connected in parallel across the motor armature winding and being responsive to the counter-electroniotive forces developed by the motor and adapted to effect the functioning of the relays -which c,ontrol the energizing circuit of the resistor short-circuiting switch, one of said relays being disposed to effect the closure of the shor'tg-circuiting switch when a comparatively low counter-electromotive forceis developed to accelerate the motor, the other heing responsive to a higher connter-electromotive force to eifect the opening of the shortcircuiting switch when the motor operates at nearly rated speed and before the motor is stalled by the amming of the pusher head.

5. In a rolling mill, in combination, a manipulator pusher head, a motor for actuating the pusher head, a resistor for controlling the current flowing in the motor circuit, an electrically-operated switch for short-circuiting a portion of the resistor, a control circuit for the electrically-operated switch, and means responsive to the counter-electromotive force developed by the motor to deenergize the control circuit, before the motor becomes stalled, to connect the desired amount of resistance in series therewith.

6. In a control system for a manipulator pusher head, in combination, a motor for actuating the pusher head, a resistor for governing the speed of the motor, a switch for short-circuiting a portion of the resistor and means responsive to the counter electromotive force developed by the motor to actuate the switch to connect the resistor in series with the motor during the starting period and short-circuit a portion of the resistor during the accelerating period and to connect the resistor in series with the motor when said motor has been accelerated to full speed thereby to limit the inrush of current when the motor is stalled by the jamming of the pusher head.

7 In a rolling mill, in combination, a manipulator pusher head, a motor for actuating the pusher head, a resistor to control the current flowing in the motor, switches for short-circuiting a portion of the resistor, actuating coils for the switches, said actuating coils being connected across the armature of the motor and being responsive to the counterelectromotive force developed by the motor and adapted to operate the switches upon different voltages to vary the resistance in series with the armature during starting and acceleration and to provide resistance in series with the motor armature after it has reached full speed and before it is stalled by the jamming of the pusher head. In testimony whereof, I have hereunto subscribed my name this 3rd day of August, 1927.

PHELAN MGSHANE.

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