US2404980A - Machine control means - Google Patents

Description

ly 0 1 46- E. A MUNSCHAUER JR 2,4 ,980

MACHINE CONTROL MEANS Filed Feb. 16, 1944 38 ,35 A n. lf l/ fnv eniroz; EDWIN A. MUNSCHAUER UR.

Patented July 30, 1946 MACHINE CONTROL MEANS Edwin A. Munschauer, In, Buffalo, N. Y., assignor to Niagara Machine & Tool Works, Buffalo, N. Y.

Application February 16, 1944, Serial No. 522,678

8 Claims.

This invention relates to novel control circuits for single stroke machines such as punch presses and the like.

The electric control circuit arrangement set forth herein and shown in the accompanying drawing provides a greatly simplified electrical means for the provision of what is known in the art as two-hand control. In providing tripping means for punch presses, metal shears, and. similar machines, it is frequently desired to place a pair of push buttons in such relative position that the operator must use both hands to press both buttons to institute a cycle of operation. This is done for the obvious reason of insuring that the operators hands are on the buttons and not in a dangerous or unsafe position. It has been found that operators, heedless of the safety provisions so made, tape down or "stake one of the buttons in order to speed up or simplify their work.

The advantages of simplicity and security of operation inherent in the present novel circuit arrangement will be obvious to those skilled in the art from a perusal of the ensuing specification in conjunction with the accompanying drawing. While a particular adaptation is shown in detail herein by way of example, it is to be understood that the electrical control of the invention may be applied with like benefit to any kind of clutch or clutch tripping arrangement or, in fact, to any other machine controlling devices susceptible of control in an analogous manner. The principles of the present invention are not to be considered as limited in spirit or scope, otherwise than as defined in the appended claims.

In the drawing:

Fig. 1 is a fragmentary side elevational view of a punch press showing the crank shaft thereof and portions of the clutch tripping mechanism; and

Fig. 2 is a wiring diagram showing the novel electrical control circuits of the present invention.

In the drawing like characters of reference denote like parts throughout and the numeral i designates a punch press crank shaft having thereon a clutch l I. The details of the clutch are not shown since suitable single-revolution clutches are well known and may vary in detail. In common with most of the mechanical singlerevolution clutches in use at present, a throwout pin 12 is provided and, as is well known to those skilled in the art, the throwout pin is pulled away from the clutch, to the right as viewed in Fig. 1, to cause the clutch elements to engage axially and produce rotation of the crank shaft. The clutch elements are conventionally biased to engaging position by spring means, or otherwise. Upon release of the pulling impulse on the throwout pin, it is moved back to a position where it engages the clutch elements to cam the clutch elements to disengaged position so that the crank shaft is stopped at the end of a single rotation thereof.

From what has been said it will be seen that the throwout pin, after having been pulled, must be released substantially before the completion of a single rotation of the crank shaft if it is to declutch and stop the same at the end of a single revolution.

In the form illustrated by way of example, the clutch throwout pin I2 is pivotally attached to a rock arm M which has a central pivotal mounting i5 securing it to a punch press frame IS. The other arm of the rock arm i4 engages between a compression coil spring I? and the end of a piston rod l8 of a piston I9. A casing 23 provides a fluid chamber 2| in which the piston I9 is disposed for axial movement and also supports and houses the compression spring l1.

As shown in Fig. 1, the parts are in inactive position with the clutch released and spring l1 cts through the adjacent arm of rock arm Hi to retain piston I9 in its illustrated position. A conventional solenoid operated valve shown in outline at 22 in Fig. 1 is adapted when its operating circuit is energized, to connect a fluid pressure source 23 to chamber 2! through a conduit 24, which moves the piston i 9 to the left as viewed in Fig. 1 and pulls the clutch throwout pin, through rock arm l4. When the operating circuit of the solenoid valve is de-energized, the valve moves to close oil" the pressure source 23 and vent conduit 24, whereupon spring I! returns the piston Hi to its illustrated position and clutch throwout pin i2 is returned to a position for disengaging the clutch at the end of an operating cycle of the crank shaft.

Fig. 2 schematically illustrates the control circuits for solenoid valve 22, which are so arranged that a separate manual two-hand push button pressing operation is required for each press cycle. That is, ibOth buttons must be released and re-depressed, after a cycle has been instituted by pressing both buttons and after the press cycle has been substantially completed, before a succeeding cycle can be begun. This positively prevents avoidance of the two-hand safety operation by tying down or staking one of the buttons. Means are further provided to prevent an operator from releasing both buttons and re-depressing them during a press cycle to re-withdraw the throwout pin and cause the machine to continue on into a second cycle of continuous operation. Further, the proposed circuit arrangement is such that all circuits are open between press operations.

Referring to Fig. 2, supply conductors are designated 3G and 3! and the numeral 32 denotes the winding of solenoid valve 22. A pair of push buttons are indicated at 3A and respectively, and it is to be understood that the push buttons are to be disposed at spaced points, such as at opposite sides of the front of the press frame, whereby an operator can depress both buttons only by employing both hands. Each button, when depressed, closes two switches, and the buttons are biased to return automatically to open position when manual pressure is removed. The button 3 5 controls switches 36 and 3'! and button con trols switches 33 and 39.

It will be noted that an independent energizing circuit for solenoid valve winding 32 is present. The winding 32 connects with supply conductor 36, a conductor 52, the switches 31 and as which are connected in series, and a conductor 43 leading to the opposite supply conductor 36 and containing a normally closed switch Mi.

A relay winding is connects with supply conductor 3! and has two parallel energizing circults, one designated 4'! and containing a normally open limit switch 48 and the other designated 5S and connecting in parallel with switches 35 and 38. A return conductor from the parallelconnected switches 35 and 3B is designated 5! and contains a normally open switch 52.

Both the normally closed switch il and the normally open switch 52 are under control of the relay winding 46. When winding 1% is de-energized the switches 44 and 52 are in closed and open positions, respectively. Energization of winding 65 opens switch M and closes switch '52 and they remain in those conditions until the winding is again de-energized,

Referring to Fig. l, a cam 55 is shown fixed to the crank shaft iii and the numeral 56 designates a casing which houses the limit switch indicated at 48 in the wiring diagram, Fig. 2. The cam 55 has a lobe 5? which is so located that it engages a push button 59 of limit switch casing 55 to momentarily close limit switch 13 in passing. The timing of cam 55 is such that the limit switch E8 is momentarily closed toward the end of a cycle of crank shaft operation, but a sufllcient distance from the end of the stroke to permit the throwout pin 12 to disengage the clutch by the end of a cycle of operation.

The operation of the foregoing control circuit arrangement will now be described. In the first place, it is essential that the operator depress both buttons 34 and 35 to close the series connected switches 31 and 39 to energize the winding 32 of the solenoid valve and pull the throwout pin I'Z to initiate a cycle of crank shaft operation.

When the limit switch 48 closes momentarily, which as has been stated is preferably close to the end of the stroke to prevent release and re-depres sion of the buttons 34 and 35 before the end of the stroke, it establishes a circuit through conductor il which energizes relay winding and opens normally closed switch 44 to break the solenoid valve winding circuit. The relay winding is simultaneously closes normally open switch 52 and if either of the parallel-connected switches 33 their natural or 38 is still closed by reason of failure of the operator to remove his hands from both buttons, or because he has already re-depressed one or both buttons, or because either button has been staked, a holding circuit for the relay winding 45 will be established through conductor 5c, whichever of the switches 36 or 38 is closed, return conductor 5|, and the holding circuit switch 52.

It is thus essential that both buttons 3 and 35 be released to open both switches 36 and 38 before it is possible to again close the solenoid valve winding circuit since this can be effected only through de-energization of relay winding 36 and consequent re-closure' of the normally closed switch as in the solenoid valve winding conductor 43.

It will be noted that when buttons as and 35 are released, they close no circuits and that all auxiliary circuits are likewise open at all times when the push buttons 3% and 35 are in released position.

What is claimed is:

1. Control means for a machine having a singlerevolution clutch including an element movable between clutch-engaging and clutch-disengaging positions, an electromagnet energizable to move said element to clutch-engaging position, means biasing said element to clutch-disengaging position, an energizing circuit for said electromagnet, a pair of switches connected in series in said circuit, a pair of spaced control elements manually movable to close said switches and energize said electromagnet, a relay and an energizing circuit therefor, a second pair of switches closable simultaneously with the first pair by manual movement of the control elements and connected in parallel in said relay circuit, a normally closed switch in said electromagnet circuit and a normally open switch in said relay circuit, said last two switches being movable by energization of said relay to open and closed position, respectively, a second normally open switch in series with said relay and in shunt with respect to said first normally open switch and means operable during the cycle of said single-revolution clutch to momentarily close said second normally open switch to energize said relay and establish a holding circuit therefor through said first normally open switch and either of said second pair of switches to de-energize the electromagnet through opening of the normally closed switch in its circuit in the event said circuit is then closed through said first pair of switches.

2. In a cyclic control for a machine having means movable between operating and non-operating positions, an electromagnet energizable to move said means to operating position, means biasing said means to non-operating position, an energizing circuit for said electromagnet, a pair of switches connected in series in said circuit, a pair of spaced control elements manually movable to close said switches and energize said electromagnet, a relay and anenergizing circuit therefor, a second pair of switches closable simultaneously with the first pair by manual movement of the control elements and connected in parallel in said relay circuit, a normally closed switch in said electromagnet circuit and a normally open switch in said relay circuit, said last two switches being movable by energization of said relay to open and closed position, respectively, a second normally open switch in series with said relay and in shunt with respect to said first normally open switch and means operable during the machine cycle to momentarily close said second normally open switch to energize said relay and establish aholding circuit therefor through said first normally open Switch and either of said second pair of switches to deenerg-iz'e the eIectrofna-g'net through opening of the normally closed switch in its circuit in the event said circuit is then closed through said first pair of switches.

3. Control means for a machine having a single-revolution clutch including an element movable between clutch engaging' 'an'd clutch-disengaging positions, an electromagnet energizable to move said element to clutch-engaging position, means biasing said element to clutch-disengaging position, an energizing circuit for said electromagnet, a pair of spaced manually movable control elements and a switch means manually closable by each, said two switch means engaging said energizing circuit in series to require inanual operation of both control elements to energize said electromagnet, a relay and an energizing circuit therefor, said two switch means being connected in parallel in said relay circuit, a normally closed switch in said electromagnet circuit and a normally open switch in said relay circuit, said last two switches being movable by energization of said relay to open and closed position, respectively, a second normally open switch in series with said relay and in shunt with respect to said first normally open switch and means operable during the cycle of said single-revolution clutch to momentarily close said second normally open switch to energize said relay and establish a holding circuit therefor through said first normally open switch and either of said switch means to deenergize the electromagnet through opening of the normally closed switch in its circuit in the event said circuit is then closed through said switch means.

4. In a cyclic control for a machine having means movable between operating and non-operating positions, an electromagnet energizable to move said means to operating position, means biasing said means to non-operating position, an energizing circuit for said electromagnet, a pair of spaced manually movable control elements and a switch means manually closable by each, said two switch means engaging said energizing circuit in series to require manual operation of both control elements to energize said electromagnet, a relay and an energizing circuit therefor, said two switch means being connected in parallel in said relay circuit, a normally closed switch in said electromagnet circuit and a normally open switch in said relay circuit, said last two switches being movable by energization of said relay to open and closed position, respectively, a second normally open switch in series with said relay and in shunt with respect to said first normally open switch and means operable during the machine cycle to momentarily close said. second normally open switch to energize said relay and establish a holding circuit therefor through said first normally open switch and either of said switch means to de-energize the electromagnet through opening of the normally closed switch in its circuit in the event said circuit is then closed through said switch means.

5. Control means for a machine having a single-revolution clutch including an element movable between clutch-engaging and clutchdisengaging positions, an electromagnet energizable to move said element to clutch-engaging position, means biasing said element to clutchdisengaging position, an energizing circuit for said electromagnet, a pair of switches connected in series in said circuit, a pair of spaced push buttons manually movable to close said switches and energize said electro-magnet, means yieldably biasing said push buttons to switch-open position, a relay and an energizing circuit therefor, 59, second pair of switches closable simultaneously with the first pair by manual movement of the push buttons and connected in parallel in said relay circuit, a normally closed switch in said electromagnet circuit and a normally open switch in said relay circuit, said last two switches being movable by energization of said relay to open and closed position, respectively, a second normally open switch in series with said relay and in shunt with respect to said first normally open switch and means operable during the cycle of said single-revolution clutch to momentarily close said second normally open switch to energize said reIay and establish a holding circuit therefor through said first normally open switch and either of said second pair of switches to (1 -'energize the ele'ctroinagnet through opening of the normally closed switch in its circuit in the event said circuit is then closed through said first pair of switches.

6. In a cyclic control for a machine having means movable between operating and non-operating positions, an electromagnet energizable to move said means to operating position, means biasing said means to non-operating position, an energizing circuit for said electromagnet, a pair of switches connected in series in said circuit, a pair of spaced push buttons manually movable to close said switches and energize said electromagnet, means yieldably biasing said push buttons to switch-open position, a relay and an energizing circuit therefor, a second pair of switches closable simultaneously with the first pair by manual movement of the push buttons and connected in parallel in said relay circuit, a normally closed switch in said electromagnet circuit and a normally open switch in aid relay circuit, said last two switches being movable by energization of said relay to open and closed position, respectively, a second normally open switch in series with said relay and in shunt with respect to said first normally open switch and means operable during the machine cycle to momentarily close said second normally open switch to energize said relay and establish a holding circuit therefor through said first normally open switch and either of said second pair of switches to de-energize the electromagnet through opening of the normally closed switch in its circuit in the event said circuit is then closed through said first pair of switches.

7. Control means for a machine having a single-revolution clutch including an element movable between clutch-engaging and clutchdisengaging positions, an electromagnet energizable to move said element to clutch-engaging position, means biasing said element to clutchdisengaging position, an energizing circuit for said electromagnet, a pair of switches connected in series in said circuit, a pair of spaced control elements manually movable to close said switches and energize said electromagnet, electromotive means and energizing circuit means therefor, a second pair of switches closable simultaneously with the first pair by manual movement of the control elements and connected in parallel in said electromotive circuit means, a normally closed switch in said electromagnet circuit and a normally open switch in said electromotive circuit means, said last two switches being movable by energization of said electromotive means to open and closed position, respectively, a second normally open switch in series with said electromotive means and in shunt with respect to said first normally open switch and means operable during the cycle of said single-revolution clutch to momentarily close said second normally open switch to energize said electromotive means and establish a holding circuit therefor through said first normally open switch and either of said second pair of switches to de-energize the electromagnet through opening of the normally closed switch in its circuit in the event said circuit is then closed through said first pair of switches.

8. In a cyclic control for a machine having means movable between operating and non-operating positions, an electromagnet energizable to move said means to operating position, means biasing said means to non-operating position, an energizing circuit for said electromagnet, a pair of switches connected in series in said circuit, a pair of spaced control elements manually movable to close said switches and energize said electromagnet, electromotive means and energizing circuit means therefor, a second pair of switches closable simultaneously with the first pair by manual movement of the control elements and connected in parallel in said electromotive circuit means, a normally closed switch in said electromagnet circuit and a normally open switch in said electromotive circuit means, and last two switches being movable by energization of said electromotive means to open and closed position, respectively, a second normally open switch in series with said electrornotive means and in shunt with respect to said first normally open switch and means operable during the machine cycle to momentarily close said second normally open switch to energize said electromotive means and establish a holding circuit therefor through said first normally open switch and either of said second pair of switches to deenergize the electromagnet through opening of the normally closed switch in its circuit in the event said circuit is then closed through said first pair of switches.

EDWIN A. MUNSCHAUER, JR.

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