US2862154A

US2862154A - Apparatus control systems

Info

Publication number: US2862154A
Authority: US
Inventors: Robert W Bradley
Original assignee: United Shoe Machinery Corp
Current assignee: United Shoe Machinery Corp
Priority date: 1956-02-09
Filing date: 1956-02-09
Publication date: 1958-11-25
Anticipated expiration: 1975-11-25
Also published as: DE1121180B

Description

Nov. 25, 1958 R. w. BRADLEY 2,862,154

APPARATUS CONTROL SYSTEMS Filed Feb. 9, 1956 [111/612 for Faber h/Br'ad/ey United States Patent Ofiice 2,862,154 Patented Nov. 25, 1958 APPARATUS CONTROL SYSTEMS Robert W. Bradley, Marblehead, Mass., assignor to United Shoe Machinery Corporation, Flemington, N J., a corporation of New Jersey Application February 9, 1956, Serial No. 564,504

7 Claims. (Cl. 317-149) Many types of apparatus employ a control organization including an element manually operable to initiate a power driven activity of the apparatus and control means for automatically modifying the aforesaid power driven activity upon the occurrence of a given event. In many cases the modifying action which the modifying control is depended upon to perform is so important that failure of the control to operate upon the occurrence of such an event, permitting unmodified power driven activity of the apparatus, may result in severe damage or even personal injury.

As an example, the invention is illustrated as embodied in a cutting press of the type disclosed in United States Patent No. 2,783,838, granted March 5, 1957, on an application filed in the names of Roy G. Ericson and Frank E. 511211011. i

In such apparatus, as disclosed in said application, the press comprises a work support upon which apiece of sheet material isplaced, with a cutting die superposed thereon, beneath a power driven platen. Means including a handle operated switch on the platen, is provided to initiate the operation of power means to move the platen toward the work support to press the die through the material. Both'the platen and the work support comprise conductive members which are electrically connected by the die upon cutting through the material to reduce the resistance between the platen member and the support member to a low value. Correct operation of the press depends upon the functioning of an electron tube relay control, sometimes designated a stroke terminating control, to modify the activity of the power means to terminate the cutting stroke in response to the reduction of such intermember resistance below a predetermined value. Failure of the electron tube relayto operate after initiation of a stroke could result in a stuck die or failure to stop the stroke upon contact of the platen with the operators hand.

In other types of apparatus, the control may have a function, other than modification of the operation of the power driven means, which is vital to the safety of the operator or to the proper operation of the machine and, accordingly, of such a nature that the power driven means of the machine should not be started if the control is incapable of exercising its control function. Such functions include, for example, the operation of warning signals and the operation of guard or release mechanisms.

Accordingly, an important object of the invention is the provision, in power driven apparatus having an automatic control, of means to prevent initiation of the power driven operation of the apparatus if the automatic control is not then capable of exercising its control function. To this end and in accordance with a feature of the invention there is provided in such apparatus, in combination with the power initiating means and the control,

means operative to disable the initiating means, means for temporarily transferring the control function of the control to control of said disabling means to causesaid means to disable the initiating means while the control is not exercising its control function, that is, when the control is not in the operating condition in which it should be in response to the establishment of a predetermined input condition, means for establishing said predetermined input condition of said control to cause said control to exercise its control function to terminate the op eration of the disabling means, whereby if said control is then capable of exercising its control function the initiating means is operative, and means operated by the initiating means for retransferring the control function of the control to its original function of controlling" the power means.

Another object of the invention is the provision of an improved control for power means which control will prevent the operation of the power means when an automatic relay control depended upon for proper or safe operation is inoperative.

To this end and in accordance with a feature of the invention, a relay control is provided having an operating control, power control means operable thereby to modify the transmission of power, relay means adapted to exercise a control function on a controlled element in response to the establishment of a predetermined input condition of said relay means, means normally establishing said predetermined input condition, means operable to disable operation of the power control means by the operating control, means temporarily transferring the control function of said relay means to said disabling means for preventing operation thereof when said relay means is exercising its control function,'and means operating in response to operation of said operating control in operating the power control means to discontinue the operation of said condition-establishing means and to retransfer the control function of the relay means for exercise on the controlled element.

Other features and advantages of the invention will best be understood from the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a diagrammatic representation of apparatus embodying the present invention; and

Fig. 2 is a'partial vertical section of a modification of an element similarly shown in Fig. 1.

Referring to Fig. 1, there is illustrated a cutting press organization which comprises a work support 10 including a conductive work support member 12, which may consist of conductive rubber, for supporting work pieces 14 of sheet material, such as leather fabric or the like to be operated upon by a freely movable die 16 to produce blanks. A platen or beam 18, including a'metallic striking plate 19 providing a conductive platen member, is mounted for swinging movement across the support 10 and for movement toward and away from the support to force the die 16 through the work piece. For safety reasons the plate 19 is insulated from the rest of the platen as disclosed in the above-mentioned Patent No. 2,783,838.

Power means for reciprocating the platen 18 are preferably fluid operated and are illustrated as comprising a piston 22 connected to the platen, as indicated by the broken line in Fig. 1, and slidablymounted in a cylinder 24, the cylinder and the piston providing a fluid-operated motor. Control of the fluid-operated motor is provided by a valve 26 having an axially movable valve element 28. When the valve element 28 is in its upper position, as shown, a lower port 30 in the cylinder 24 is connected to a supply pipe 32 and an upper port 34 is connected to an exhaust pipe 36 so that the piston 22 is urgedupwardly. When the valve element 28 is in its lowermost position, the connections to the ports are reversed so that the piston is urged downwardly. The valve element 28 is normally biased upwardly by a spring 38 so that in its normal or rest position, the platen is elevated. A solenoid 40 is arranged, by connection of its armature to the valve element 28, to move the element into its lowermost position. when the solenoid is energized. The hydraulic system ismore completely described in a copending United States application Serial No. 487,634, filed February 11, 1955, in the names of Frank E. Stratton and Fred T. MacKenzie, now Patent No. 2,818,922.

Stroke initiating means for controlling the fluid-operated motor to initiate a downward stroke of a platen 18 comprises a switch mechanism 42 having an operating handle 44 disposed at the front of the platen 18. When the initiating means is operative, downward movement of the handle 44 is effective to connect the solenoid 49 across

A. C. supply lines

46 and 48. The initiating circuit involves; four relays, 50, 52, 54 and 56. Operation of the initiating means begins by energizing the relay 50 through. a circuit beginning at line 46 through relay contacts 56a, switch 42, the coil of relay 50 and back to line 48. Energization of relay 56 causes a delayed energization of relay 52 from switch 42 through contacts 50a, the coil of relay 52 and back to the line 48. To provide delayed closure of relay 52, a condenser is shunted across its coil while a resistor and rectifier are inserted in series therewith as shown in Fig. 1. The reason for so delaying closure of relay 52 will become evident later. Upon energization of relay 52, a lock-in circuit for the relay 50 is formed which can be traced in Fig. 1 starting near the lower end of line 46 through contacts 54a, contacts 52d to the coil of relay 50 and back to line 48. At the same time, an energizing circuit for the solenoid 40 is completed starting from the same point on line 46 through contacts 541;, through contacts 52c to the solenoid and back to line 48.

A control for automatically modifying the operation of the power means in response to a given event comprises a stroketerminating control shown in the lower left-hand portion of Fig. 1. This control, more completely described in copending United States application Serial No. 487,553, filed February 11, 1955, in the name of Robert W. Bradley, now Patent No. 2,821,670, comprises two

thyratrons

60, 62 which are normally biased nonconductive but which are connected to be fired in sequence upon the establishment of a predetermined input condition of the control, that is, a value below the critical value of the bias voltage at the control grid 64 of tube 60, to energize the relay 54 from a power supply 68 through the. contacts 52b of the relay 52 or through the contacts 50c of the relay 50. Energization of the relay 54 opens the contacts 54a and 54b respectively, to interrupt both the lock-in circuit to the relay 50 and the energizing circuit to the solenoid 40, thus causing the power means to return the platen to its original position. The event chosen to produce this modification is the reduction of the electrical resistance between the conductive support member 12 and the striking plate 19 below a predetermined value, a value which may be selected to be reached at the instant at which the cutting die penetrates the work piece on the support member 12. The biasing circuit for the tube 60 comprises a source of direct current 70 in series with a relatively high value resistor 72 connected effectively between the grid 64 and the cathode 74 of tube 60 normally to bias the tube non-conductive. The

conductive members

12 and 19 of the press are connected in shunt with the resulting high impedance bias source so that the resistance between the press members controls the voltage at the grid 64. Penetration of the cutting die at the completion of a cut may thus be made effective to cause a drop in the grid bias voltage sufficient to fire the thyratron 60. The resulting positive wave of voltage at the cathode 74 is transmitted to the grid 76 of the thyratron 62 through a timed delay circuit 80 as described in application Serial No. 487,553, to fire the .prises the

relays

50 and 52.

.4 thyratron 62 for energizing the relay 54. Since this arrangement is designed not only to reverse the movement of the platen upon the completion of a cut but also to reverse the platen in case a portion of the operators body should accidentally come between the platen and the work support during a cutting stroke, it is evident that it is extremely important for the modifying control to be capable of performing its control function of opening the contacts 54a and 54b in response to a signal of the type described.

To this end, means for disabling the initiating circuit unless the modifying control is capable of performing its control function comprises means for disabling the initiating means, the relay 56 whose contacts 56a are in series with the switch 42. Energization of the relay 56 opens the contacts 56a to interrupt the energizing circuit of the relay 5t and thus to paralyze the initiating means. An equivalent disabling means is shown in Fig. 2 where a solenoid 82 is shown as arranged to bar movement of the handle 44a when energized.

Means for temporarily transferring the control function of the modifying control to the disabling means com- When these relays are deenergized, their contacts are in the positions illustrated and if the relay 54 is not energized, the relay 56 will be energized through a circuit extending from the line 46 near the bottom through contacts 5412, through contacts 50a, to the coil of relay 56 and back to line 48.

At the same time, however, the relay 50 through its contacts 50b provides a means for establishing the predetermined input condition of the modifying control which should cause it to perform its control function and open the contacts 5412. Thus closure of the contacts 50b operates to shunt out all bias voltage by effectively connecting the grid 64 to the cathode 74 by grounding the negative side of the bias voltage supply. If the modifying control is then able to perform its function, the relay 56 (or alternatively the solenoid 82) will be deenergized and the initiating means will be operative to initiate a cutting stroke.

It will be seen that the

relays

50 and 52 provide a means, operating upon operation of the initiating means, to return the control function of the modifying control to the power means by re-connecting the contacts 54b in the energizing circuit to the solenoid valve 40 which circuit has been described above. At the same time the bias supply is ungrounded and the modifying control is returned to its normal operating conditions.

In operation, the initial condition of the circuits and control relays is as shown in Fig. 1. When the main switch MS is closed, the disabling circuit is immediately energized from line 46 through contacts 5412, 511d, through the cold relay 56 and back to line 48. This condition continues until the thyratrons 60 and 62 have fired, at which time the relay 54 will deenergize the disabling circuit and the operator may then proceed to use the machine. If at any subsequent time, tube or component failure should render the modifying control unable to function to energize the relay 54, the operator will be unable to initiate a cutting stroke. Otherwise, each time the operator presses down the handle 44, the relay 50 will be energized: (a) to energize a delayed energizing circuit for relay 52, (b) to unground the input grid of the modifying control, (c) to disconnect the plate voltage supply from the thyratrons to permit them to deionize, and (d) to interrupt the disabling circuit. Shortly thereafter the relay 52 pulls in to restore the plate voltage to the tubes, to complete the energizing circuit to the solenoid 40, and to complete a holding circuit for the relay 50, thus retransferring the control function of the modifying control to control of the power means. Energization of the relay 52 also closes the contacts 52a thus to reconnect one of the input leads of the modifying control to the striking plate 19. If desired, however, the striking plate 19 may be connected directly to this input lead, e. g. to the resistor 72, without the intervening contacts 52a.

As a further feature of safety, the power supply 68 includes a relay 90 having contacts 90a in series with the source of D. C. plate voltage which includes the rectifier 92. The solenoid of the relay is connected in series with the filaments of the

thyratrons

60 and 62 so that the relay is energized by a transformer 94 to provide pl-ate voltage to the thyratrons only if their filaments are intact. The filament relay 90, which immediately cuts off plate current in the event of filament failure, avoids the possibility of continued thermal emission after filament failure, preventing operation of the disabling circuit.

While I have described my invention as applied to a cutting press of the clicker type, it will be obvious that the invention has wide usage in many other applications. I therefore desire that my invention be not limited except in so far as is made necessary by the prior art and by the scope of the appended claims.

-I claim:

1. 'In apparatus having power driven operating means, means including a manually operated element for initiating the operation of said power driven means and a control operative automatically to perform a control function in response to the establishment of a predetermined input condition of said control, means for insuring that said control is capable of exercising its control function prior to initiating the operation of said power driven means comprising, in combination, means operative to disable the initiating means, means for temporarily transferring the control function of said control to control of said disabling means, means for establishing said predetermined input condition ad-apted to cause said control to exercise its control function and thereby to terminate the operation of said disabling means, and means operative upon operation of the initiating means for returning the control function of said control to its original control function.

2. In apparatus having power operating means, means including a manually operated element for initiating the operation of said power means, a modifying control operative automatically to modify the operation of said power means in response to the establishment of a predetermined input condition of said control, and means for establishing said condition in response to the occurrence of a given event, in combination therewith, means for preventing initiation of the operation of said power means unless said modifying control is then capable of performing its control function comprising, in combination, means operative to disable said initiating means, means for temporarily transferring the control function of said modifying control to control of said disabling means, means for establishing said predetermined input condition adapted to cause said control to exercise its control function and thereby to terminate the operation of said disabling means, and means for retransferring the control function of said modifying control to control of said power means upon operation of the initiating means.

3. In a machine for operating upon work pieces, said machine having an element movable to effect an operation on a work piece, power means for moving said element, means, including a manually operable element, to initiate the operation of said power means, modifying control means operative automatically to perform a control function operative to effect a predetermined modification in the operation of said power means in response to the establishment of a predetermined input condition of said control, and connections for controlling said condition in accordance with a condition in relation to which such modification is to be accomplished, in combination therewith, means operable to disable said initiating means, means for transferring the control function of said control between control of said power means and control of said disabling means, said transferring means normally 6 connecting said control to said disabling means for operation thereof in such manner as to prevent operation of said initiating means unless the output of said control would if retransferred to the power means efiect the aforesaid modification of its operation, means normally establishing said predetermined input condition of said control whereby if said control is operating properly said disabling means does not prevent the operation'of said initiating means, and means responsive to operation of said initiating means for discontinuing the operation of the establishing means and for retransferring the control function of said control to control of said power means.

4. In apparatus having power operating means, means, including a manually operated element, for initiating the operation of said power means and a relay operative in response to the establishment of a predetermined input condition for modifying the operation of said power means, means for preventing the initiating of the operation of said power means unless said relay is capable of exercising its control function in response to such establishment, comprising, in combination, disabling means connected to prevent operation of the initiating means when energized by electric energy, circuit means for connecting said disabling means to a source of electric energy, means for temporarily connecting the modifying control relay in said circuit means in such a manner that when said relay is energized the disabling circuit is interrupted, means for concomitantly establishing said predetermined input condition of said modifying control adapted to cause it to exercise its control function, and relay means operated by said initiating means to reconnect the modifying control for control of the power means.

5. In apparatus having power operating means, initiating means for said power means, including a manually operated switch, a modifying control operative automatically to modify the operation of said power means in response to the establishment of a predetermined input condition and connections for controlling said input condition in accordance with another condition for control in response to the occurrence of a given event, said modifying control comprising an electron tube and an electro-mechanical relay adapted to be energized through said tube in response to said establishment to effect its control function by effecting a predetermined switching operation, in combination therewith, means energizable to disable the operation of said initiating means, switch contact means normally closed to establish said predetermined condition of the input of said modifying control and to connect the contacts of the control relay into an energizing circuit for said disabling means so that said energizing circuit is interrupted by said relay when the relay is energized and its switching function is exercised, and relay means adapted upon operation of said initiating means to open said switch contact means and to reconnect the contacts of the control relay for control of said power means.

6. In apparatus having power operating means, initiating means for said power means including a manually operated switch, a modifying control operative automatically to modify the operation of said power means in response to the establishment of a predetermined input condition of said control, and connections for controlling said condition in accordance with another condition for control in response to the occurrence of a given event, said modifying control comprising at least one electron tube and an electro-mechanical relay adapted to be energized through said tube in response to said establishment to effect its control function by effecting a predetermined switching operation, in combination therewith means energizable to disable the operation of said initiating means, switch contact means normally closed to establish said predetermined condition of the input of said modifying control and to connect the contacts of the control relay into an energizing circuit for said disabling means so that said energizing circuit is interrupted by said relay when the relay is energized and its switching function is exercised, means for interrupting the energization of said control relay in response to interruption of the continuity of the filament of any electron tube in said modifying control, and relay means adapted upon operation of said initiating means to open said switch contact means and to reconnect the contacts of the control relay for control of said power means.

7. A relay control of the class described comprising, in combination, an operating control, power control means operable by said operating control for modifying the transmission of power, relay means adapted to exercise a control function on a controlled element in response to the establishment of a predetermined input 0 condition of said relay means, means normally establishing said predetermined input condition, means operable to disable the operation of said power control means by said operating control, means temporarily transferring the control function of said relay means to said disabling means for preventing operation thereof when said relay means is exercising its control function, and means operating in response to operation of said operating control in operating said power control means to discontinue the operation of said condition-establishing means and to retransfcr the control function of the relay means for exercise on the controlled element.

No references cited.