US3394650A

US3394650A - Press unloader control system

Info

Publication number: US3394650A
Application number: US480983A
Authority: US
Inventors: Harlan R Cagle
Original assignee: SAHLIN ENG CO Inc
Current assignee: SAHLIN ENGR CO Inc; SAHLIN ENG CO Inc
Priority date: 1965-08-19
Filing date: 1965-08-19
Publication date: 1968-07-30
Anticipated expiration: 1985-07-30

Description

July 30, 1968 H. R. CAGLE 3,394,650

PRESS UNLOADER CONTROL SYSTEM Filed Aug 19, 1965 2 Sheets-Sheet 1 'I/ III/ A! L INVENTOR. BY Han 4 R Cay/e E- July 30, 1968 H. R. CAGLE 3,394,550

PRESS UNLOADER CONTROL SYSTEM Filed Aug. 19, 1965 l 2 Sheets-Sheet 2 United States Patent 3,394,650 PRESS UNLOADER CONTROL SYSTEM Harlan R. Cagle, Ciarkston, Mich., assignor to Sahlin Engineering Co., Inc., Troy, Mich., a corporation of Michigan Filed Aug. 19, 1965,Ser. No. 480,983 13 Claims. (Cl. 100-53) ABSTRACT OF THE DISCLOSURE There is herein disclosed a press unloader control system providing for varying modes of operation of the press unloader and having selection means for selecting the modes of operation.

This invention relates to a press unloader control system and more particularly to an electronic remote control system for press unloaders.

The primary object of the present invention is to provide a new and improved press unloader control system by which the operation of a swinging arm and a jaw attached thereto may be controlled in a new and improved manner.

It is a further object of the present invention to provide a control system for a press unloader having variable modes of operation in which the various movements of the press unloader and associated jaw means may be selectively caused manually and automatically.

Another object of the present invention is to provide a control system for a press unloader or the like in which the mode of operation of the device being controlled can be varied.

Still another object of the present invention is to provide a control system for a press unloader or the like, which is movable between positions in a predetermined sequence, in order to vary or reverse the sequence of movement.

Other objects and the many advantages of the present invention will be apparent to those skilled in the art to which this invention relates by reference to the following detailed descriptions of an illustrative embodiment of the inventive concepts as shown on the accompanying drawings in which:

FIGURE 1 is a schematic side elevational view of a press unloader and the controls associated therewith; and

FIGURE 2 is a circuit diagram of control apparatus for the press unloader shown in FIG. 1.

Referring now to FIGURE 1, an illustrative press unloader is shown to comprise a supporting frame portion adapted to be mounted on a press or the like by suitable means 12. A swinging arm 14 is movable between a lower ed position, as shown, and an upwardly outwardly located position as shown in phantom at 16. J aw means 18 on the lower end of the swinging arm are operable between open and closed positions to grip a workpiece in the press, hold the workpiece during travel of the swinging arm 14 upwardly away from the press, and release the workpiece at some point during the upward movement. A power cylinder means 20 is provided for actuating the swinging arm and a power cylinder means 22 is provided for actuating the jaw means 18. The operation of the jaw means 18 is conventional and well known in the art as illustrated, for example, by U.S. 2,609,776. The details of construction of the press unloader are conventional and may be, for example, of the type shown in US. 2,609,776.

In the illustrative embodiment, the operating devices 20, 22 are pneumatic and are operable by a source of high pressure air 26 such as commonly found in factories. The source of high pressure air is connected to the air cylin- 3,394,650 Patented July 30, 1968 ders 20, 22. through a filter 28, a pressure regulator 30, and a lubricating device 32 by which a mist of oil is introduced into the air for lubrication purposes. A branch line 34 is connected to the arm operating cylinder 20 through a motorized speed control valve 36, a line 37, a solenoid operated three-way control valve 38, and a line 40. Cylinder 20 may be a single acting cylinder which is positively moved upwardly from the lowered position, shown in phantom at 42, to move the swinging arm 14 from its lowered position to its upwardly outwardly located position 16. The arm v14 is connected to piston 42 in any suitable manner known in the art as illustrated, for example, in US. 2,609,776 and US. 3,206,040. Downward movement of the swinging arm 14 is effected by exhausting the cylinder through line 40, the valve 38, and an exhaust line 43 so that the weight of the arm 14 pulls the piston 42 to its lowered position. The rate of return movement is controlled by an oil cushion cylinder 46 which is connected to the swinging arm as is conventional as shown, for example, in US. 3,206,040.

The three-way valve 38 is a conventional valve operable to a position connecting the inlet line 37 to the line 40 by a first solenoid 48 and being operable to the exhaust position by energizataion of a solenoid 50. The valve may include an air assist portion 52 which insures positive actuation of the valve and keeps the valve in the selected position.

The speed control valve 36 is motorized and the rate of flow of air through the line 34 is controlled by the position of the valve in the flow path. A motor means 54 is remotely operable to vary the position of the control valve, the rate of flow of high pressure air through the line 34, and hence the rate of movement of the arm 14 from the lowered position to the raised position.

The jaw actuating cylinder 22 is double acting and is operated through

air lines

56, 58 which are connected to a branch line 59 through a solenoid operated valve 60. Solenoid 62 is remotely operated to selectively connect one of the

lines

56, 58 to the high pressure source in line 59 while the other line is connected to exhaust as at 64. A spring return 65 is also provided.

In addition to the aforedescribed operating controls, the press unloader includes a solenoid operated arm lockup device 66 for positively locking the arm in the raised position. The details of the lockup device 66 are conventional, well known in the art, and disclosed in US. 3,204,783. A control switch 68 is conveniently mounted on the frame 10 for actuation by an actuating arm 70 engageable with the swinging arm 14 in the lowered position. It is to be understood that the details of the aforedescribed valves and controls may be varied as necessary or desirable.

Referring now to FIGURE 2, the various controls of the press unloader are operable remotely from a control panel in which a plurality of manually operable switches are provided to enable the unloader operation to be controlled and varied as desired. In general, the control circuitry comprises a conventional 115 volt source on input terminals 82 which are connectable to

input lines

84, 86 through an on-off switch 88. A circuit 90 for an on-oif indicating light 91 may be connected across the

input lines

84, 86. A motor circuit 92 is provided for the motor 54 of the motorized speed control valve 36. A manually operable control switch '93 is provided to selectively energize the coils 94, 95 of the motor for reversible actuation of the motor. An operation initiating relay circuit 96 connects an enabling relay 98 between the input terminals.

Solenoid circuits

100, 102, 104 and 106 are also connected across the input lines. The lockup assembly 66 includes a lockup solenoid 108 connectable to the source of potential through

lines

84, 86 and lines 110, 111. Jaw

cylinder valve control solenoid 62 in circuit 102 and arm cylinder valve control solenoid in circuit 104 are connected across the line and a line 113. The other arm cylinder valve control solenoid 48 in circuit 106 is connected across the line 110 and the line 111, as hereinafter described in detail, and is also directly connectable to the input line 86 through a manually operable switch 114 and a line 115.

Three

timing circuits

116, 117, 118 are provided in the control panel. The timing circuit 116 provides means for delaying energization of the arm up solenoid 50 until a predetermined time interval has elapsed sufficient to complete closing of the jaws 18. The timing circuit 117 provides means for controlling the time opening of the jaws 18 during the upward movement of the arm 14 from the lowered position to the upper position. The timing circuit 118 provides means for terminating upward movement of the arm and initiating downward movement a predetermined time interval after the jaws 18 have been opened. The latter length of time is sometimes referred to as over travel time. In general, each of the timing circuits includes a thyratron 120, 121, 122 which controls energization of control relays 123, 124, 125. Tube filament transformer circuitry 126 is provided to subject the filament of each tube to a charge of, for example, 6.3 volts and is connected across the input terminals by a line 127 and line 84. A cycle terminating disabling relay 128 may be connected across the input terminals by line 84 and a line 129.

It is to be understood that the press unloader has two basic modes of operation. One operational mode originates with the arm in the lowered position and comprises movement of the arm from the lowered position to the raised position and then back to the lowered position. Another operational mode originates with the arm in the raised position and comprises movement of the arm from the raised position to the lowered position and then back to the raised position. It is to be further understood, that the controls may be placed in one of two basic modes of control, i.e., an automatic or manual control mode.

The first described operational mode of the press unloader, sometimes referred to as down operation, will now be discussed. The circuitry and controls of FIG. 2 are shown in an automatic control mode. Manually operable control panel switches 130, 131, 132, 133, 134, and 136 are provided to variously connect input line 111 to the various control circuits. Switch 130 is manually operable from a closed position. in an automatic mode connecting line 111 to a line 137 to an open position in a manual mode. Simultaneously, operable switch 136 is connected in the solenoid circuit 104 to connect the arm up solenoid 50 to the input line 86 through a line 138. Switch 131 is manually operable from an automatic control mode position connecting line 137 to a line 139 to a manual mode disabling the other control circuitry. A simultaneously operable jaw control switch 142 in the circuit 102 of the jaw solenoid 62 is connected to the input line 86 by a line 143 to energize the solenoid 62 and actuate the jaws. The

switches

132, 133 are provided to select the mode of operation of the arm and, in the one position, connect

lines

144, 145 to lines 146, 129, for down operation. In the other position, the

switches

132, 133 connect

lines

144, 145 to lines 148, 149 for up operation. Switch 134 provides manually operable means for testing the

soelnoid circuits

102, 104 and the relay circuit 96.

Energization of the control circuitry through the

switches

132, 133 is further controlled by switches 150, 152. Switch 150 is actuated to the closed position by mechanism associated with the press and may be placed in the closed position after the press operation is completed prior to or at the beginning of opening movement of the press following a forming operation. Switch 152 is located on the unloading device at 68, as shown in FIG. 1,

and is closed when the swinging arm is in the lowered position.

At the beginning of down operation, with the switches in the positions shown in FIG. 2, enabling relay 98 is initially connected between

input lines

84 and 86 through line 111, switch 130, line 137, switch 131, line 139, press switch 150, line 144, switch 132, line 146, line 154, and line 113. Contacts 98a are closed when relay 98 is energized to provide a holding circuit between the input lines 84, 86, through normally closed contacts 125a. Line 113 will thereafter remain connected to the input line 86 regardless of the condition of the control. switches. Jaw solenoid 62 is energized through line 113, normally closed contacts 124a, and switch 142 in the jaw solenoid circuit 102 to close the jaws and grip a workpiece in the press.

At the same time, the timing circuit 116 is connected to the input line 86 through the control switches, lines 146, 149, a line 162 and a line 164. Conduction between line 164 and a line 166 connected in circuit therewith through the thyratron 120 is controlled by a potentiometer circuit 168 and a capacitor circuit 170 which control the rate of discharge of the control grid of the thyratron through line 172. The rate of discharge is controllable by a manually adjustable wiper 174 in the potentiometer circuit. These circuits are connected to the input line 86 by a line 176, a line 178, and a line 180. The control relay 16 is adapted to be energized a predetermined time interval after the press switch 150 is closed. The time interval is variably set by adjustment of the wiper 174 in the potentiometer circuit and, in general, is set to provide sufiicient time for the jaw means to close and grip the workpiece in the press. An illustrative jaw closing time may be, for example, approximately one second.

When the control grid of the thyratron tube has been discharged, lines 164 and 166 are connected across the thyratron 120 to energize arm up control relay 123. Normally, open contacts 123a of control relay 123, in the circuitry of arm up solenoid 50, are closed to energize the arm up solenoid 50 resulting in admission of high pressure air to the actuating cylinder 20 through the three-way valve 38. Consequently, the arm 14 is moved from the lowered position toward the raised position.

Relay 123 also closes normally open contacts 123b in line 182 of timing circuit -117 to enable connection of input line 84 to input line 86 through the thyratron (121. The thyratron control grid is discharged through the line 184 at a rate controlled by an adjustable potentiometer 186 and capacitory circuit 188. When the thyratron 121 becomes conductive, control relay 124 is energized resulting in closure of normally open contacts =124b in the timing circuitry 118 and in opening of normally closed contacts 124a in the jaw solenoid circuitry 102. When contacts 124a are open, the jaw solenoid 62 is de-energized which causes the jaws 18 to be opened and the part being carried upwardly to be released. The time interval from the closing of the jaw means and the initiation of upward movement of the arm to the opening of the jaw means is variably controllable by adjustment of the wiper in the potentiometer circuit 186 so that the workpiece may be released at a predetermined point in the upward movement of the arm.

At the same time, closure of contacts 124b begins determination of the amount of travel of the arm to take place after the part is released. Line 190 is connected between the input lines 84, 86 through thyratron 122 and a line 192 when the control grid of the thyratron has been discharged through line 194 at a rate determined by the manually adjustable potentiometer 196 and the capacitor 198. When the thyratron becomes conductive, control relay 125 is energized and normally open contacts 125a in line 129 are closed to connect cycle terminating disabling control relay 128 across the input lines 84, 86 which opens normally closed contacts 128a in a line 200.

Relay 125 also closes normally open contacts 125b in the line 200. When contacts -125b and 128a are closed, a holding circuit is provided for control relay 125 around the contacts 124b in line 190. When control relay 125 is energized, normally closed contacts 1250 in the hold circuit for control relay 98 are opened so that control relay circuit 96, the jaw solenoid circuit 102, and the arm up

solenoid circuits

104, 106 are de-energized resulting in de-energization of control relays 123 and 124.

The arm down control solenoid 48 is actuated by connection across

input lines

84, 86 through line 200, normally closed contacts 1240, and line 202. Simultaneously operable manual switches 204, 206 are in a closed position during down operation. When control relay 124 is energized, contacts 1240 are opened to prevent energization of the arm control solenoid 48 during the time delayed energization of relay 125 caused by closure of contacts 12%. When control relay 125 is energized, contacts 125a in line 129 are closed enabling relay 128. Contacts 12512 in line 200 are closed to provide a holding circuit for relay 125 and enabling the circuit for the arm control solenoid 48. At the same time, the contacts 1250 are opened disabling the circuitry for the control solenoids 123, 124, and 125. When control relay 124 is de-energized, the contacts 1240 are again closed to complete a circuit to the arm controlling solenoid 48. The three-way valve 38 is thus actuated to connect the arm actuating cylinder 20 to exhaust resulting in downward movement of arm 14 under the control of the oil cushion cylinder 46. Thus, the arm is returned to the down position and the down cycle of operation is completed when the arm 14 reaches the lowered position and actuates switch 152 through the actuating arm 70. When switch 152 is closed control relay 128 is energized and normally closed contacts 128a are opened to de-energize the holding circuit through line 200 for relay 125. Contacts 125a are opened and relay 128 is de-energized. When the press again closes switch 150, the cycle of operation will be repeated.

The second mode of operation may be referred to as the up mode. In order to condition the circuitry for the up mode of operation, the arm 14 is initially moved to the up' position indicated at 16 in FIG. 1. This may be accomplished by manual actuation of

switches

132, 133 to connect the arm up solenoid 50 to the line 86 through

lines

111, 137, 139, 145, 149, 154, 113, 104. The arm is moved to the up position and switch 152 will be opened when the arm 14 leaves the down position. In this manner, the arm will be raised and held in the up position until the down solenoid 48 is subsequently energized when switch 150 is closed by the press.

Switches

132, 133 are connected to lines 148, 149 and switches 204, 206 are manually positioned in the up mode operational position. Switches 130, 136 are in the automatic mode of operation.

After completion of the press operation such as at the beginning of the opening movement of the press, switch 150 will be closed and input line 86 will be connected through line 111, switch 130, line 137, switch 131, line 139, switch 150, line 144, switch 132, line 148, and solenoid circuit 106 to input line 84 causing energization of arm down solenoid 48. Operating cylinder 20 will be connected to exhaust through line 40 and the three-way valve 38. Arm 14 will be lowered and upon reaching the lowered position, will close switch 152 causing the enabling control relay circuitry 96 to be connected between input lines 84, 86- through lines 113, 154, 149, switch 133, line 145, switch 152, line 139', switch 131, line 137, switch 130, and line 111. Thereafter, the hereinbefore described operational sequence caused by successive energization of the relays 123, 124, .125 will be repeated. Accordingly, control relay 98 will be energized, contacts 98a will be closed to provide a holding circuit for the control relay, the jaw solenoid circuit 102 will be energized, the timing circuit 116 will be energized after the jaw has been closed, relay 123 in timing circuit 116 will be energized causing contacts 123]; to be closed, and the arm up solenoid circuitry 104 will be energized.

The arm will begin its upward travel and at the same time the timing circuit 117 controlling subsequent opening of the jaws will be energized by closure of the contacts 12% of the control relay 123. After a predetermined time interval, the control relay 124 in the timing circuit 117 will be energized and contacts 124a in the jaw solenoid circuitry 102 will be opened resulting in deenergization of the jaw solenoid 62 and opening of the jaws 18-. Simultaneously, the timing circuitry 118 will be energized by closure of contacts 124b of the control relay 124. After a preselected time interval, the control relay 125 will be energized to close contacts 125m, 12% and open contacts 125a. Switches 204, 206 are open to prevent energization of the arm down solenoid 48 upon energization of the control relay 125. Opening of contacts 1250 in the holding circuitry 96 causes the control relays 123, 124, 125 to be de-energized. Relay 128 is not utilized. The arm will remain up until the press switch is again closed when the cycle of up movement will be repeated.

In the up mode of operation, the arm 14 is held in the raised position by high pressure air in cylinder 20. It is possible for the control circuitry to be disabled by opening switch 88 with the arm in the up position. If there should be a failure in the high pressure air system, the arm might be subsequently unexpectedly lowered. Consequently, a safety lockup feature is provided by connecting the lockup solenoid 66 to input terminals 80, 82 through

lines

220, 222 whenever the main switch 88 is opened. A limit switch having switch contacts 226, 228 is positioned adjacent the lockup mechanism for actuati-on thereby. When the lockup coil 108 is energized, movement of the lockup is effected. The movement of the lockup opens switches 226, 228. A manually operable lockup switch 230 is provided in line 232 for selective energization of the lockup.

Thus, it will be readily apparent that a new and improved remote control system has been provided by which two modes of operation may be readily attained. It is contemplated that certain concepts of the invention may be applicable in other environments and may be otherwise variously embodied. Accordingly, it is intended that the scope of the appended claims be construed to include variations and modifications except as limited by the prior art.

What is claimed is:

1. A control system for a press unloading device movable between spaced positions and comprising: actuating means for moving said device between the spaced positions, control means for selectively operating said actuating means in a cyclic manner in one mode of operation causing movement of said device from one of said positions to the other of said positions and back to said one of said positions and in another mode of operation causing movement of said device from said other of said positions to said one of said positions and back to said other of said positions, and operating mode selection meas for selectin g a mode of operation.

2. A control system for a press unloading device movable between spaced positions and having jaw means operable between open and closed position carried thereby, comprising: device actuating means for moving said device between the spaced positions, jaw actuating means for opening and closing said jaw means, electrically operated device controlling means for operating said device actuating means, electrically operated ja'w controlling means for operating said jaw actuating means, circuit means for selectively energizing said device controlling means and said jaw controlling means to effect cyclic operation thereof, said circuit means being arranged to effect various modes of operation of said device, and mode section means for selecting the various modes of operation of said device.

3. The invention as defined in claim 2 and wherein said circuit means comprises jaw opening and closing circuit means, jaw closing switch means in said jaw opening and closing circuit means operable in one position of said device for energizing said jaw opening and closing circuit means and energizing said electrically operated jaw controlling means to close said jaw means, jaw closing timing circuit means including said jaw closing switch means connected in circuit at the same time as said electrically operated jaw controlling means at the beginning of closing of said jaw means and being enabled a first predetermined time interval after closin of said jaw means, first electrical control means operably connected in said jaw closing timing circuit means and being operable after said first predetermined time interval to energize said electrically operated device controlling means and cause movement of said device from the one position, jaw opening timing circuit means including switch means operable by said first electrical control means connected in circuit when said first electrical control means is operated and being enabled a second predetermined time interval after energization of said electrically operated device controlling means after initiation of movement of the device from the one position, a second electrical control means operably connected in said jaw opening timing circuit means and being operable after said second predetermined time interval to energize said electrically operated jaw controlling means and cause opening of said jaw means, device movement controlling timing circuit means including switch means operable by said second electrical control mean-s connected in circuit when said second electrical control means is operated and being enabled a third predetermined time interval after cnergization of said electrically operated jaw controlling means after opening of said jaw means, and a third electrical control means operably connected in said device movement controlling timing circuit means and being operable after said third predetermined time interval to energize said electrically operated device controlling means and terminate movement of the device from the one position and cause the device to be returned to the one position.

4. A control system for a press unloader in the form of swinging arm means movable between raised and lowered positions and having jaw means operably between open and closed positions carried thereby and comprising: first power cylinder means operatively connected to said arm means to move said arm means between the raised and lowered positions, fiuid pressure delivery means actuably connected to said power cylinder means, first control valve means associated with said fiuid pressure delivery means and being operable to selectively supply and exhaust fluid under pressure to and from said power cylinder means to reversely move said arm means in one direction from the lowered position to the raised position and in the opposite direction from the raised position to the lowered position, first solenoid means operatively connected to said first control valve means and being operable to move said valve means between supply and exhaust positions, second power cylinder means operatively connected to said jaw means to move said jaw means between open and closed positions, second fluid pressure delivery means actuably connected to said second power cylinder means, second control valve means associated with said second fiuid pressure delivery means and being selectively operable to supply and exhaust fluid under pressure to and from said second power cylinder means to open and close said jaw means, second solenoid means operatively connected to said second control valve means and being operable to move said valve means between supply and exhaust positions, a first circuit means for selectively changing the condition of said first solenoid means, a second circuit means for selectively changing the condition of said second solenoid means, control circuit means connected to said first circuit means and said second circuit means for automatically changing the condition of said first and second solenoid means in a predetermined sequence, and mode selection means for selecting different modes of operation of said swinging arm including a mode of operation wherein said arm means moves from the lowered position to the raised position and back to the lowered position and a mode of operation wherein said arm means moves from the raised position to the lowered position and back to the raised position.

5. The invention as defined in claim 4 and wherein said control circuit means comprises first timing circuit means for changing the condition of said first solenoid means a predetermined time interval after the condition of said second solenoid means is changed to close said jaw means and causing upward movement of said arm means after said jaw means is closed, second timing circuit means for changing the condition of said second solenoid means a predetermined time interval after the condition of said first solenoid means is changed to begin upward movement of said arm means and causing opening movement of said jaw means after said arm means has traveled upwardly a predetermined distance, a third timing circuit means for changing the condition of said first solenoid means a predetermined time interval after the condition of said second solenoid means has been changed to open said jaw means and causing the upward movement of said arm means to be terminated and downward movement of said arm means to be begun, and said mode selection means being operative to vary the foregoing operational sequence depending upon the initial position of said arm means to return the arm means to the iniiial position.

6. The invention as defined in claim 4 and wherein said mode selection means comprises switch means operable in one mode of operation to connect said control circuit means to said first solenoid means at the beginning of the operational cycle in one switch position and being operable in another mode of operation to connect said control circuit means to said second solenoid means at the beginning of the operational cycle in another switch position.

7. A control system for a swinging arm type press unloader movable between raised and lowered positions and having jaw means for removing a workpiece from a press operable between open and closed positions carried thereby, solenoid operated jaw opening and closing means, solenoid operated arm raising means, solenoid operated arm lowering means; in one mode of operation with the swinging arm initially in a raised position said system having operable in sequence, circuit means for operating the solenoid operated arm lowering means to move the swinging arm from the raised position to the lowered position, circuit means for operating the solenoid operated jaw opening and closing means in the lowered position to close the jaw means and grip a workpiece in the press, circuit means for operating the solenoid operated arm raising means after the jaw means are closed to raise the swinging arm and remove the workpiece from the press while gripped by the jaw means, circuit means for operating the solenoid operated jaw opening and closing means to open the jaw means in a raised position of the swinging arm and release the workpiece, and circuit means for maintaining the swinging arm in the raised position until said solenoid operated arm lowering means is again operated; and in another mode of operation with the swinging arm initially in the lowered position said system having operable in sequence, circuit means for operating said solenoid operated jaw opening and closing means to close the jaw means and grip a workpiece in the press, circuit means for operating said solenoid operated arm raising means to move said swinging arm from the lowered position to the raised position and remove the workpicce from the press while gripped by the jaw means, circuit means for operating the solenoid operated jaw opening and closing means to open the jaw means in a raised position of the swinging arm and release the workpiece, circuit means for operating the solenoid operated arm lowering means to lower the swinging arm, and circuit means for maintaining the swinging arm in the lowered position until said solenoid operated arm raising means is again operated.

8. The system as defined in claim 7 and having timing circuit means for controlling energization of said solenoid operated arm raising means in relation to jaw closing time, timing circuit means for controlling energization of said solenoid operated jaw opening and closing means in relation to the amount of upward movement of said swinging arm, and timing circuit means for controlling energization of said solenoid operated arm lowering means in relation to travel of said swinging arm beyond the point at which said solenoid operated jaw opening means is actuated.

9. The system as defined in claim 8 and having control relay means and relay energizing circuit means associated with each of said timing circuit means and adapted to be energized by the associated timing circuit and initiate operation of a subsequent timing circuit.

10. A control system for controlling a press unloading cycle involving movement of a swinging unloading arm between raised and lowered positions relative to a press and movement of openable and closeable jaw means carried by the unloading arm between a closed position for gripping a workpiece in the press and carrying the workpiece away from the press and an open position for releasing the workpiece away from the press comprising: arm actuating cylinder means for selectively moving the arm between raised and lowered positions, arm raising solenoid means for causing operation of said arm actuating cylinder means resulting in raising movement of said arm, arm lowering solenoid means for causing operation of said arm actuating cylinder means resulting in lowering movement of said arm, jaw actuating cylinder means for selectively opening and closing said jaw means, jaw opening and closing solenoid means for causing operation of said jaw actuating cylinder means resulting in opening and closing movement of said jaw means, said system being selectively operable in one mode of operation from a lowered position of said arm to a raised position and back to the lowered position and in another mode of operation from a raised position of said arm to a lowered position and back to the raised position, press operated switch means operable in the one mode of operation to initiate a press unloading cycle being connected in circuit with said jaw opening and closing solenoid means and being operable when the press has completed an operation to energize said jaw closing solenoid means resulting in closing movement of said jaw means to grip a workpiece in the press, enabling relay means connected in circuit with the press operated switch means and being operable when the press has completed an operation to provide a holding circuit and enabling the arm raising solenoid means, arm raising movement initiating timing circuit means for controlling energization of said arm raising solenoid means connected in circuit with said press operated switch means and being energized upon actuation of said press operated switch means when the press has completed an operation and having a timing cycle sufiicient to enable said jaw means to close and grip the workpiece before said arm is raised, arm raising control relay means operatively connected in circuit with said arm raising timing circuit means and being operable upon completion of said timing cycle, said arm raising control relay means being controllably associated with said arm raising solenoid means and causing energization thereof upon completion of said arm raising timing cycle resulting in raising movement of said arm after said jaw means close and grip the workpiece, jaw opening movement initiating timing circuit means for controlling energization of said jaw opening solenoid means and having a timing cycle sufiicient to enable said arm to move upwardly to a predetermined workpiece release point, said arm raising control relay means being controllably associated with said jaw opening movement initiating timing circuit means and causing energization thereof upon completion of said arm raising movement initiating timing cycle, jaw opening control relay means connected in circuit with said jaw opening movement initiating timing means and being operable upon completion of said jaw opening movement initiating timing cycle, said jaw opening control relay means being operatively associated with said jaw opening solenoid means and being operable to actuate said jaw opening solenoid means causing opening movement of said jaw means to release the workpiece after the swinging arm has moved upwardly a predetermined distance from said lowered position, arm upward movement terminating timing circuit means for controlling energization of said arm lowering solenoid means and having a timing cycle suflicient to enable said arm to move upwardly beyond said release point a predetermined distance, said jaw opening control relay means being controllably associated with said arm upward movement terminating timing circuit means and causing energization thereof upon completion of said arm upward movement timing cycle, arm raising movement terminating and arm lowering movement initiating control relay means operatively connnec-ted to said arm raising movement terminating timing circuit means and being operable after the swinging arm has moved upwardly a predetermined distance beyond the release point, said arm raising movement terminating and arm lowering movement initiating control relay means being operatively associated with said arm lowering solenoid means to cause actuation of said arm lowering solenoid means resulting in lowering movement of said swinging arm upon completion of said arm upward movement terminating cycle, holding circuit means for said arm raising movement terminating and arm lowering movement initiating control relay means, disabling control relay means controllably associated with said last mentioned holding circuit means, device operated switch means connected in circuit with said disabling control relay means and being operable in the lowered position for disabling said last mentioned holding circuit means when said swinging arm moves from the raised position to the lowered position, said arm raising movement terminating and arm lowering movement initiating control relay means being associated with said holding circuit means of said enabling relay means to disable said holding circuit when the arm is in the lowered position, operating mode selection means for varying the mode of operation of said swinging arm between an operational mode in which the swinging arm moves from the lowered position to the raised position and back to the lowered position and another operational mode in which the swinging arm moves from the raised position to the lowered position and back to the raised position, and said operating mode selection means including mode selection switch means connecting said device operated switch means in circuit with said enabling relay means, said jaw closing solenoid means, and said arm upward movement initiating timing circuit means in the other operational mode.

11. The invention as defined in claim 10 and having safety means for maintaining said arm in the raised position in the other mode of operation.

12. The invention as defined in claim 11 and wherein said safety means comprises a main switch for disabling said control system, solenoid operated lockup means for locking said arm in the raised position, and circuit means connected to said solenoid operated lockup means for actuating said solenoid operated lockup means when said main switch disables said control system.

13. A control system for a swinging arm type press unloader movable between a raised position and a lowered position, operational control circuit means operable to control movement of said swinging arm between said positions, switch means in said operational control circuit means for disabling said operational control circuit means, solenoid operated lockup means for locking said swinging arm in the raised position, and lockup circuit means connected with said solenoid operated lockup means for actuation thereof to lock said swinging arm in the raised position, said switch means being operatively connected with said lockup circuit means to energize said lockup circuit means and actuate said solenoid operated lockup means when said operational control circuit means is disabled.

References Cited UNITED STATES PATENTS Sahlin 72-426 Miller 214-147 X Udal 214-147 Sahlin 2l4-1 Ridley 72-24 Armbrust 2141 Blatt 214-1 Tiffany 214-1 Melvin 2141 BILLY J. WILHITE, Primary Examiner.