US 941726 A
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Description (OCR text may contain errors)
G. F. PFALZGRAP.
SAFETY TRIP DEVICE FOR POWER OPERATED MACHINES.
APPLICATION FILED OGT.15, 1907.
941 ,726. Patented Nov. 30, 1909. 2 SHEETSSHEET 1. it:
Enuenfoz Witnesses Gal/1M9 6m $2, I M W f attozlu af G. F. PPALZGRAF.
SAFETY TRIP DEVICE EOE POWER OPERATED MACHINES.
APPLICATION FILED 00T.15,190'I.
Patented Nov. 30, 1909.
W (a O 4 8/1? P 19 K1 951 (2 Q m 27 as 521 M W if: 57 f(7 w ihwooeo K6 j 1?? M, Aim 414 335 93mg? 7 ,,CHARLES F. PFALZGRAF, 0F BALTIMORE, MARYLAND.
SAFETY TRIP DEVICE FOR POWER-OPERATED MACHINES.
Specification of Letters Patent. Patented N 30, 1909.
Application filed October 15, 1907. Serial No. 897,592.
To all whom it may concern:
Be it known that I, CHARLES F. PFALZ- GRAF, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Safety Trip Devices for Power- Operated Machines, of which the following 1s a specification.
This invention relates to a safety trip device for power operated machines such as die presses or stamping machines and the object of the invention is to provide a device that will prevent the tripping of the machine mechanism to put the machine into operation so long as any part of the operators person is in position where it may be injured.
The injury to operators is a source of great annoyance and expense to manufacturers, no matter whether the injury occurs through carelessness on the part ofthe operator or not, and it is to avoid such injuries and the expense incident thereto that the present invention is designed.
The invention is applicable to various machines in which the mechanism is set in motion by a trip device that is actuated by the operator and the trip device may be readily attached to machines now in use.
The invention is illustrated in the accompanying drawings in which,--
Figure 1 shows a press the trip mechanism of which is provided with the improved safety device and also shows an operator whose arms are provided with the electric controlling devices. Fig. 2, illustrates a detail front elevation of the pivoted stop bar or armature and the magnet for operating the same. Fig. 3, shows a side elevation of the same. Fig. at, illustrates the electric controlling device and the clips for attaching the same to the arms of the operator. Fig. 5, shows a cross-sectional detail through the pivot-connection of the arm controlling device. Fig. 6, illustrates a detail ofthe arm position, and Fig. 7 shows a longitudinal section through the two arm-controlling devices and shows the electric connection between them.-
It is to be understood that the form and construction of the, machine is immaterial and may vary widely but for the purpose of illustration I have elected to show the improved safety device in connection with a 3 press or die stamping machine.
Referring to the drawings the numeral, 1, designates the base of the machine; 2, the bed; 3, the vertically-reciprocating die or punch and, 4, the clutch thereof. In the present instance the clutch device is operated through-the depression of a foot treadle, 5, 'which is pivotally connected to pivoted horizontal bars, 6, and, 7, by means of connecting rods, 8, and, 9. A spring, 10, serves to keep the treadle and the rods and bars connected therewith in the elevated position to engage'the clutch and normally hold the die, 3, elevated. I
In the machine shown, the depression of the treadle, 5, will cause the operation of the clutch so as to enable the die, 3, to make one punch and then stop, and then remain stationary until another depression of the treadle takes place. In order therefore to prevent the operation of the die while for example, the operators hands are between the die members, I provide a construction of safety device that will prevent the operation of the treadle or other trip device, so lon as the hands of the operator are in a position where they can be injured by the die. a
While the safety device may be attached to the machine at any one of several places I prefer to locate it adjacent the-horizontal bar, 6, as clearly shown in Fig. 1.
By reference to Figs. 1, 2 and 3 it will be seen that the safety device comprises an angular base plate, 11, which is bolted to the vertical side of the machine. An electromagnet, 12, is secured in a horizontal position to the side of the base with its core, 13,
facing or pointingtoward the side of the machine. Above: the magnet the base, 11, carries a block, 14, which is provided with a horizontal slot, 15, and a stop bar or armature, 16, is mounted on a pin, 17, which projects through said slot and 1s secured in position by means of a nut, 18, at the rear of the base, 11. This stop bar or armature has a short arm or extension, 19,
which projects. above the pin, 17, and a rela- When in the vertical position the upper end of the short arm, 19,. of the armature, 16, will project beneath the horizontal pivoted bar, 6, as shown in Fig. 9., while the lower pendent arm, 20, will hang vertically from the pin and directly in front of the core, 13,
of the magnet. It will thus be seen that so long as the armature is in the vertical position, and it is always in that position when the magnet is deencrgizcd, the bar, 6, rod, 8, and treadle, 5, cannot be depressed and con sequently the clutch, 4, cannot be operated. The longer arm, 20, of the armature will insure that the upper end will remain in position beneath the bar, (3.
To permit the operation of the treadle and trip devices of the machine, the armature must be swung out of the vertical position and in the present instance 1 effect. this by energizing the magnet and thus attract ing the arm, 20, of the armature through devices now to be described. I
The circuit-controlling device in the present instance is preferably attached to the arms of the operator in such manner that the forward movement of the arms, such as would be necessary for the operator to place anything beneath the die, will cause a break in the circuit while a reverse movement of the arms will establish the circuit. This circuit-controlling device comprises two plates, 21, and, 22, of insulating material which are pivotally connected by a rivet or bolt, 23, so as to freely join them. The plate, 21, is provided with one or more spring clips, 24, which are designed to be clipped over the upper portion of the arm between the elbow and shoulder of the operator as shown in Fig. 1, while the plate, 21, is provided with a clip, 25, for engaging the forearm of the operator,the joint between the two plates being at the operators elbow.
The plate, 21, is provided with ahole or slot, 26, which extends entirely through it so as to open at the side of the overlapped end of plate, 22, as clearly seen in Fig. 7.
A metal plate, 27 such as brass or copper is secured to the outer side of the plate, 21, by means of ,a screw, 28, and said conductor plate is provided with a rectangular end block, 29, which projects through the hole or slot, 26, with its inner surface, 30, confronting the flat side surface of the end of plate, 22. A binding screw, 31, at the end of the conductor plate, 27, serves to connect a wire, 32, which electrically connects said contact plate with a binding screw, 33, on the electro-magnet on the safety device at the side of the machine. As it is necessary to provide protection for both hands of the operator two of the circuit-controlling devices of like construction are employed,one for each arm, and the wire, 32, extends from one of said devices while a wire, 34, extends from the device on the other arm and connects with a source of electrical energy which it is deemed unnecessary to show. A
third wire, 35, is connected to the other binding screw, 36, of the electro-magnet and this latter wire electrically connects said magnet with the source of electrical energy.
; wire, 32, to post, 33, of the magnet.
36, of the magnet the circuit e l-mac in so far as the electrical connections have been described the device is still inoperative as the circuit is incomplete,it being necessary to provide a connect-ionbetween the two controlling devices on the opposite arms. This connection will now be described, reference being made particularly to Figs. 4, (3 and The plates, 22, are also provided with holes or slots, 37, and metal contact plates, 38, are secured to these plates adjacent .the pivot, 23. These contact plates are also provided with a rectangular end or block, 39, which project through the slots or holes'and contact with the inner surface of the plates, 21. Binding screws, 40, on these plates, 38, serve to bind the ends of a loop wire, 41, so as to provide an electrical connection between the plates, 38, on the two forearm plates, 22.
When the connections have been made as described the operator will take position in front of the machine and will attach the two circuit-controlling devices on his arms as heretofore described. \Vhen the controlling devices are properly attached the loop wire, 41, from plate, 38, on one arm will extend around the back of the operator and connect with. the plate, 38, at the other arm and the device is in readiness for operation.
It will be understood that while the circuit-controlling devices are attached to the arms of the operator they do not hinder the free movement of the arms in performing the manual operationof handling the mate rials to be operated upon, nor do these controlling devices prevent the bending of the forearm.
During the manual operations the feeding and removal of material to and from the dies necessitates the movement of the arms 1 and the bending of the arms at the elbow. It is this natural and necessary bending of the arms at the elbow that I make use of in the carrying out of my invention, for eX- ample: \Vhen the arms are bent at the elbow as shown in Fig. 1, the plates, 21, and, 22, will turn on the pivot, 23, so as to assume a position substantially at right angles, see also Fig. 6. When in this position the arms are necessarily drawn away from the die or other machine and it is perfectly safe to trip the treadle, 5, and permit the die to descend. During this bent and retracted position of the arms the contact blocks, 29, and, 39 on the two plates of each arm will be in frictional and consequently electrical contact so that the circuit will. be as follows: from the source of energy through wire, 34, to plate, 27, block, 29; block, 39; plate, 38; wire, 41, to plate, 38, of the opposite arm then through blocks, 39, and, 29, and through the outer post, is by way of wire, 35, to the source of energy. Thus when the arms are bent the circuit is From complete and the electro-magnet is energized with the result that the lower armature arm, 20, is attracted and the upper arm, 19, thereof swung from beneath the pivoted bar, 6, so that the latter may be depressed. This condition,--that is, the shifting of the armature from beneath the bar, 6, will be maintained so long as the arms are in the bent position because the circuit will be complete and the magnet will continue to attract the armature. \Vhen however 'the arms are straightened out in reachingtoward the die or press, the circuit will be broken because the blocks, 29, and, 39, will be turned away from and out of contact with each other. The magnet then immediately becomes deenergized and the preponderance of weight of arm, 20, will cause the armature to assume the vertical position and thus the upper end or arm, 19, will again take position beneath the bar, (3, and prevent its depression. It will also be seen that before the magnet can be energized both arms of the operator must be retracted as the withdrawal of one arm only will not establish the circuit.
Having thus described my invention what I claim is,
1. A safety device for machinery comprising a clutch mechanism, a lock device to prevent the operation of the clutch mechanism and means including devices for attachment to and be carried by the arms of the operator for releasing the lock device.
2. A safety device for machinery comprising a treadle mechanism to startthe machine; a loclr'device forsaid treadle mechanism, and means for attachment to and to be carried by the arms of the operator for releasing the lock device.
3. A safety device for machinery comprising a mechanism to'start the machine, a lock device for said mechanism, an electrical de vice for operating said lock, and actuating means for engaging the operators arms and in electric connection with the said electrical device.
4. A safety device for machinery comprising a mechanism to start the machine, an electrically-operated lock for said mechanism, and pivoted clamping means for attach mentto the arms of the operator and in cir cuit with the lock operating device for estab lishing and breaking the circuit.
5. A safety device for machinery comprising a mechanism to start the machine, a lock device for said mechanism including an electrically-operated member, two clamping members for attachment to the arms of the operator and each member forming a part of and in circuit with the electrically-operated member of the lock.
6. A safety device for machinery comprising a mechanism to start the machine, a lock device for said mechanism, an electro-magnet for operating the lock, pivotally-connected plates, means for attaching said plates to the arms of the operator, and electric connections between said plates and magnet.
7. A s fety device for machinery comprising a me dhanism to start the machine, a lock device for said mechanism, an electro-magnet for operating the lock, plates for attach trical means operating between the two sets of plates and the lock device. a
9. A safety device for machinery comprlsing a trip mechanism, a look device to prevent operation of said mechanism; a plate for attachment to the forearm of the operator and another plate for attachment to the upper portion of the arm,said plates being pivotally connected, and elect-rlcal means operating between the plates and the lock device.
10. A safety device for machinery comprising a trip mechanism, a lock device to prevent operation of sald mechanism; two plates pivotally connected and each having means for securing them to the upper and lower portions of the arm of an operator, contacts on said plates and movable into and out of engagement by the swinging of the plates with respect to each other, and electrical means operating between the plates and the lock device,
In testimony whereof I afiix my signature in presence of two witnesses.
CHARLES F. PF ALZGRAF.
G. FERDINAND VOGT, CHARLES B. MANN, Jr.