Title:
Safety device for presses and the like
United States Patent 2311441


Abstract:
This invention relates to imprpvements in safety devices for presses and the like, and has for a principal object the provision of a beam of light spanning the zone which the operator's hands traverse when putting material into and/or removing material from said press, and electronically controlled...



Inventors:
James, Lloyd D.
Application Number:
US41742541A
Publication Date:
02/16/1943
Filing Date:
11/01/1941
Assignee:
James, Lloyd D.
Primary Class:
Other Classes:
112/271, 112/277, 192/131H
International Classes:
F16P3/00
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Description:

This invention relates to imprpvements in safety devices for presses and the like, and has for a principal object the provision of a beam of light spanning the zone which the operator's hands traverse when putting material into and/or removing material from said press, and electronically controlled mechanism effective while said light beam is interrupted for preventing said press from operating.

Another object of the invention is the provision on a punch press or the like of a photo-electric cell, a beam of light impinging upon said cell and spanning the zone which the operator's hands traverse, an amplifier connected to said cell, and mechanism for disabling the clutch rod of said press under control of said amplifier when said beam is interrupted by the operator's hands.

A further object of the invention is the provision on a punch press, of a source of light spanning the operative zone of the press, a photoelectric cell amplifier unit adapted to receive said light, said light being adapted to be interrupted by the operator's hands, a relay controlled by said amplifier, and a solenoid the energization of which is controlled by said relay, means in the clutch rod of said press adapted when in one position to transmit motion from the said pedal to the clutch of said press, and adapted when in another position to move freely without transmitting the motion to said clutch, said solenoid being adapted to shift said means to said lastmentioned arrangement when said cell is deprived of light.

Yet another object of the invention is the provision in the solenoid circuit of a safety device for punch presses, of switching means associated with the clutch pedal of said press for enabling said solenoid circuit when said pedal is depressed. . Other objects and advantages of the invention will be apparent to those skilled in the art.

Referring now to the-drawings: Figure 1 is a side elevation of the mechanism interposed in the clutch rod of a punch press; Figure 2 is an elevation of said mechanism as seen along the line 2-2 of Figure 1; Figure 3 is a sectional view taken along the line 3-3 of Figure 1; Figure 4 is a front elevation of a punch press showing the application thereto of the new and improved safety device; Figure 5 is an end elevation of the press shown in Figure 4; Figure 6 is a side view of an over-riding control associated with the clutch pedal of the press; Figure 7 is an elevation of the arrangement shown in Figure 6, as seen along the line 7-7 therein; and Figure 8 is a circuit diagram of the electrical control of the safety device.

Referring first to Figures 4 and 5, the punch press 10 is provided with the usual clutch II and clutch pedal 12. The rod leading from the clutch pedal 12 to the clutch I is divided into a lower portion 13 and an upper portion 14. The clutch pedal 12 has its pivotal support 16 carried on the bracket 15, and the spring 17 urges the clutch pedal upwardly to its normal position.

The mechanism to be now described is interposed between the lower portion 13 of the clutch rod and the upper portion 14.

Referring now to Figure 1, the upper rod 14 has secured thereto a plate 18 by means of rivets 19 or any other suitable means. The plate 18 has formed therein an L-shaped slot, the long leg 20 of which is vertical and the short leg 21 of which is horizontal.

The lower rod 13 has secured to its upper end, plates 22 and 23. These plates may be secured to the rod 13 in any suitable manner, for example by means of rivets 24, and in order to position the plates in spaced relation to each other, the rod 13 may be interposed therebetween. A pivot pin 25 extends through the plates 22 and 23 and has pivotally mounted thereon a roller 26 which is positioned within the L-slot in the plate 18.

The roller 26 is normally positioned in the short leg 21 of the L-slot, due to the urge of the spring 27 which is secured to a collar clamp 48 on the lower rod 13 and to a fixed point 29 on the body of the press.

Also secured to the upper end of the rod 13 is a plate 30. This plate is preferably secured to the rod by means of the rivets 24 hereinbefore mentioned. A vertical slot 31 is formed in the plate 30, and positioned in this slot is a pin 32 carried by the yoked end 33 of the solenoid plunger 34. A solenoid winding 35 is associated with the plunger 34, and when the same is energized, in a manner to be hereinafter described, the plunger 34 is moved to the right as viewed in Figure 1, thereby moving the lower rod 13 and the members associated therewith to the position shown in dot-dash lines. This brings the roller 26 to the position 26a so that if the clutch pedal 12 is depressed, it is impossible to engage the clutch due to the fact that the motion, instead of being imparted to the upper rod 14, is taken up by the travel of the roller 26 in the vertical leg 20 of the L slot. As soon as the solenoid winding 35 is deenergized, the spring 27 urges the lower rod 13 to the left and the roller 26 assumes its normal position in the short leg 2 I of the slot, so that when the clutch pedal 12 is operated the motion will be transmitted to the clutch.

Referring again to Figures 4 and 5, an adjustable bracket 36 is secured to one side of the press, and a second adjustable bracket 37 is secured to the other side of the press. Adjustably mounted on the bracket 36 is a housing 38 which carries the exciting lamp 39. This housing includes suitable lenses for throwing a cencentrated beam of light across the zone which the operator's hands traverse in feeding material to and/or removing material from the dies.

Adjustably mounted on the bracket 37 is a housing 40 which may contain, in addition to the photo-electric cell 41, (Figure 8), an amplifier tube V, the necessary circuit constants and a relay 42 for controlling the supply of current to the solenoid winding 35.

By having the photo-electric cell housing 40 and the exciting lamp housing 38 adjustable on the body of the press, I am enabled to position these elements so that regardless of the size and height of the die, the beam of light may always be set to traverse the operative zone.

Referring now to Figures 6 and 7, it will be noted that the bracket 15, which carries the pivotal support 16 of the clutch pedal arm 12, also carries a switching device 43 which may be one of the type which operates on very slight movement of the operative button 44. This operative button is engaged when the clutch pedal 12 is in its upper or normal position, and is immediately disengaged when the clutch pedal 12 is depressed.

The switch 43 has its contacts normally open and these contacts included in the solenoid circuit enable same when the clutch pedal 12 moves a few thousandths of an inch. This, of course, is before the clutch can possibly engage, and the action of the solenoid Causes the roller 26 to shift to the position 26a and makes it impossible for the motion to be transmitted from the lower rod 13 to the upper rod 14. This, of course, is predicated upon the premise that the beam of light is interrupted by the operator's hand or hands, and since it is impossible to engage the clutch when the operator's hands are interrupting the beam of light, it is impossible for the operator to get his hands hurt or mangled.

Although I have herein shown and described by way of example a preferred embodiment of the invention, it is obvious that many changes can be made in the arrangement herein shown and described without departing from the spirit of the invention as set forth in the annexed claims.

What is claimed is: 1. In a safety devic for a press or the like, having a pedal and means controlled thereby, an operative rod therebetween including a member carrying an inverted L shaped slot and a second member having means projecting into said slot, normally lying in vhe horizontal leg thereof and fcrming a normally positive linkage adapted to transmit motion from said pedal to said means, electrically actuated means for shifting said second member to bring its means into the vertical leg of said slot, thereby introducing a lost motion in said linkage to prevent motion from being transmitted to said means from said pedal, a beam of light traversing the operative zone of said press, and control means including a photoelectric cell for energizing said electrically actuated means when said cell is deprived of light from said beam.

2. In a safety device for presses or the like each including a pedal and having means controlled thereby, an operative rod therebetween divided and having interposed between the parts thereof slot and pin means forming a normally positive linkage adapted to transmit motion from said pedal to said means, electrically actuated means for shifting the relative relation of said slot and pin means, thereby introducing a lost motion in said linkage to prevent motion from being transmitted to said means from said pedal, a photoelectric cell on one side of said press, a source of light positioned on the opposite side of said press and adapted to throw a beam crossing the operative zone of said press and impinging upon said cell, an amplifier connected to said cell, and a relay controlled by the output of said amplifier for connecting said electrically actuated means to a source of current when said cell is deprived of light from said beam.

3. In a safety device for a punch press including a pedal and a clutch to be controlled thereby, means connecting said pedal to said clutch including a positionable member having a lateral projection and a second member having a trackway therein embracing said projection, the latter normally lying in a horizontal portion of said trackway and forming a normally positive linkage adapted to transmit motion from said pedal to said clutch for actuating the latter, electrically actuated means for shifting said positionabl3 member and moving said projection to a nonhorizontal portion of said trackway and thereby rendering said positive linkage ineffective and preventing motion from being transmitted to said clutch when said pedal is depressed, means for throwing a beam of light across the front of said press cutting the operative zone of the latter, and control means including a light sensitive cell for energizing said electrically actuated means when said cell is deprived of light from said beam.

4. In a safety device for presses or the like each including a pedal and a clutch to be controlled thereby, a rod connected to said clutch and extending downwardly, a second rod connected to said pedal and extending upwardly, linkage means partly carried by said ilrst rod and partly carried by said second rod for normally causing said rods to move in unison when said pedal is .depressed, said linkage means including a positionable member associated with one of said rods and having a lateral projection and a second member having a trackway therein embracing said projection, the latter normally lying in a horizontal portion of said trackway, electrically actuated means for shifting said positionable member and moving said projection to a 6non-horizontal portion of said trackway and permitting said second rod to move without transmitting its motion to said first rod when said clutch pedal is depressed, an exciting lamp 6g for throwing a beam of light across the operative zone of said press, and photo- -lectric means normally receiving light from said beam and adapted when deprived of said light to control the supplying of energy to said electrically actuated means.

5. In a safety device for a punch press or the like including a pedal and a clutch to be controlled thereby, a rod connected to said clutch and extending downwardly, a second rod connected to said pedal and extending upwardly, linkage means comprised of a plate member having a vertical slot formed therein and a horizontal slot communicating therewith, said plate being carried by one of said rods, and a second member carried by the other of said rods and carrying a roller which is normally positioned in said horizontal slot, electrically actuated means for moving one of said members with respect to the other for bringing said roller in registration with said vertical slot and thereby preventing motion from being transmitted from the said pedal to said clutch, an exciting lamp for throwing a beam of light across the operative zone of said press, and photo-electric means normally receiving light from said beam and adapted when deprived of said light, to control the supplying of energy to said electrically actuated means.

6. In a safety device for a punch press or the like including a pedal and a clutch to be controlled thereby, linkage means between said pedal and said clutch comprised of a plate member having a slot formed therein and a second member carrying a roller positioned in said slot, said slot including a substantially horizontal portion and non-horizontal portions, said roller being normally positioned in said horizontal portion and adapted to be moved to said non-horizontal portion when controlled to prevent said clutch from being operated, electrically actuated means for effecting control, an exciting lamp for throwing a beam of light across the operative zone of said press, photo-electric means normally receiving light from said beam and adapted when deprived of said light to condition a circuit for supplying energy to said electrically actuated means, switching means included in said circuit and including an actuating member in contact with said pedal, said switch being normally open and adapted to close said circuit when said pedal is moved.

LLOYD D. JAMES.