US2589849A - Punching machine - Google Patents

Description

March 18, 1952 H. OETIKER PUNCHING MACHINE Filed Aug. 17, 1948 4 a Z I a M w {D W"/ z W Z m u m J m m u r m I INVENTOR #AIYS fifTI/(f/E ATTORNEY Patented Mar. 18, 1952 UNITED STATES PATENT OFFliGE Application August 17.1 948, serial No."44,739

In Switzerland August 1 8, .194?

Punching machines are known which are provided with a. puncher and die and an automatically operating device for feeding the "work piece into the machine. "These machines also "possess a device for the automatic ejection of the punched-out work piece from the die. "Correct and reliable operation of the ejecting device is, however, of great importance because there is danger that when a punched-out piece "remains stuck in the die, the machine 'is not capable of withstanding the increased pressure resulting from the next impact of the punching hammer and bursts. The puncherand die are, however, relativel expensive machine elements and ever ti'methey must be replaced it is necessary for the machine to be put out of operation for some time and this results in a loss in production. since disturbances of this kind occur frequently, the output of the machine and its efliciently are considerably reduced.

The object of the invention is to eliminate the danger of the machine being destroyed or dams aged when the ejection device does not operate and "thus enable the punchin speed to be increased and thereby raise the output of the machine. I

The invention concerns a punching machine with a .puncher and die and an automatically operating device for progressively ifeeding the work strip into the machine, as well as a device forautomatically ejecting the punched-out pieces from the die, a safety device being provided which, when the ejection device does not function, operates due to a change in the stroke of the ejecting elements produced by the work piece which is stuck in the die, whereby this safety device brings the punching machine to a standstill.

The punching machine according to the invention is thus so constructed that it protects itself against destruction. Once the machine has been stopped, it is an easy matter to remove the jammed work piece from the machine and to start up the latter again. The most important feature of the new machine is. however, that due to the automatic safety device the machine can be operated at a much higher speed than machines which do not have this self-protective device.

A constructional example of the invention is shown diagrammatically in the accompanying drawing, Figs. 1 to 3 illustrating various operas tional phases of a punching machine according to the invention.

The punching machine shown in the figures 2 Claims. (Cl. 164-10 5) 2 has .an ejecting device comprising an ejection piston I, an ejection pm 2. and a lever '3. 'Inaill three figure's, numeral '4 designates the punching hammer which is moved rhythmically up and down 'by the plunger 5. Numeral '6 designates a die fixed to the hammer 4. Numeral l designates apuncher mounted on a baseplate. The ejection piston '1 slides freely'inside'the die 6 and lever 3 pivo'tally supported at 8 serves as afstopifor the ejection pin. Numeral 3 designates (a "spring which presses the supporting :ring "In againstthe work strip H.

The work strip H "which is to be punched moves between guide rollers and "is moved gradually forward after each punching operation by a'feed mechanism not shown in the drawing.

At the end of lever 3 is a set screw I! which is in contact with the left-hand end of a beam 13 pivoted at M. The right-hand end of beam 13 rests on one end of a contact lever lipivdted at 1'6, the other end of this contact lever lying on the contact 11. Thepivots l4 and I6, as well as the contact l1 are mounted on the frameor arm 1'8 which is rigidly connected with the punching hammer 4. Contact lever .15 and contact H are connectedto an electric circuit which is supplied from a battery l9, the current from this circuit being. used to excite a magnet v20 whose armature 21 is attracted against the fierce of a spring 22. The armature 21 can swing about the fixed axis 23 and'is provided at its upper end, which .is bent atright angles. with a pawl which engages the-latch .2 4 that is pressed against the pawl by a spring 25. When the latch {is released, the rod which is connected with {it jumps to the right under the action of the spring 25 and .puts a conventional mechanism, -.not

shown in the -drawing,'into'operation thusbringing the punching machine very quickly to a f standstill. The movement 50f the actuating lever 3 in an upward direction is limited by a set screw 26 mounted on a stationary support.

Fig. 1 shows the position of the various elements of the machine before the commencement of a normal punching operation, the ejection elements being in their normal initial position. The ejection pin 2 and the piston I are in their lowest positions. If the punching hammer 4 is now moved downwards by the plunger 5, a piece Z'l'is punched out of the work 'stripll and pushed into the space inside the die 6, as shown in Fig. 2. The ejection pin 2 is now moved out of its initial position by an amount equal to the thickness of the punched-out piece 21,

but this displacement is not sufficient to displace thickness of the work strip.

. position by coming into contact with the stationary set screw or stop member 26. The lever 3 which acts as stop for the ejection pin therefore pushes the latter back into its initial position, whereupon the piece 21 is expelled from the die. By means of a blower which is not shown it is possible to remove the piece 21 entirely from the machine.

In practice, it frequently happens that the work piece is-not completely expelled and reains stuck in the, die, so that for the next punchlingoperation the ejection pin has a different starting position. This case is illustrated in Fig. Thepunching hammer when moving down has'punched out a further piece 28 and now the -twofpieces 21 and Bare stuck in the die one above the other. The ejection pin 3 is thus displaced upwards by an amount equal to the double accordance with the invention, the device is so constructed that the displaced ejection pin now turns the lever 3 about its pivot 8. This causes the set screw l2 on lever 3 to change the position of beam I3, whereupon contact lever l5 swings about'pivot 16, so that contact lever I5 is no longer in contact with contact [1. electric circuit of the battery I9 is therefore'interrupted by the opening of thes contacts. Holding magnet is now no longer excited and spring 22 pulls the armature 2| away from the magnet.

The armature revolves about the axis 23' and releases the latch member 24 'whose rod actuated by the spring 25 sets the conventional mechanism into operation which immediately stops the punching machine, so that the pieces 2'! and 28 which are stuck in the die can be removed.

In'the constructional example described above, "an electrical circuit is used which operates with a" continuous current. It is, however, also possible to utilize acircuit which is interrupted dur- -inglnormalservice-and closed when a disturbance occurs. Instead of an electric current it is also possible to use a-fiowingmedium, such as compressed air, oil-,- or the like, for actuating the mechanism which brings the machine to a stand still. 1 In a similar manner it is also possible to provide a purelymech'anical system such as a system of'levers actuated by springs. In "order that the machine should come to a standstill as soon as possible, it is expedient to The disconnect it from its driving motor and subject it to a braking action.

With punching machines where the punchedout pieces are conveyed away from the machine by air blasts from a blower, it is an advantage to provide means which, when the machine is brought to a standstill, at the same time out ofi the air supply, so that there is no waste of compressed air.

I claim: 1. A punching machine for punching substantially flat work pieces from strip-like work material, comprising means for continuously feeding the work material into the machine, a stationary puncher, a reciprocatingly movable punching hammer having a cavity receiving said puncher, piston means slidable in said cavity and displaceable by the punched work pieces resting on said puncher, a lever pivoted to said reciprocatingly movable punching hammer, a stationary abutment placed in the path of said lever to be abutted by said lever when said punching hammer approaches the end of its idle stroke,

said lever being swingable in a plane containing the longitudinal axis of said piston means and abutting against the latter upon abutment of said lever against said stationary abutment and tending topush said piston means out of said cavity during the rest of the idle stroke of said punching hammer to effect the ejection of a punched-out piece, an electric switch mounted on said punching hammer to move therewith and positioned relative to said lever to be actuated thereby upon abutment of said piston means against said lever upon improper displacement, due to the failure of a punched-out piece to be ejected by the action of the stationary abutment, of said piston in said cavity, and stop means for stopping the punching machine connected with and controlled by said switch.

2. A punching machine as defined in claim 1,

said stop means comprising a latch member, a

spring urging said latch member into position for :stopping the machine, and an electric circuit ineluding and being exclusively controlled by said REFERENCES CITED The following references are of record in th file ofthispatent: I

UNITED STATES PATENTS Number Name Date 2,134,933 Smith Nov. 1, 1938 2,200,886 Kuhn May 14,1940

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