US2254659A - Work stopping device for blanking dies - Google Patents

Description

Sept. 2, 1941. A. KOWALSKI I WORK STOPPING DEVICE FOR BLANKING DIES Filed Sept. 17, 1940 INVENTOR.

Patented Sept. 2, 1941 WORK STOPPING IIDFE VICE FOR BLANKING ms Alexander Kowalski, Chicago, Ill.

Application September 17, 1940, Serial No.-357,143

2 Claims.

The present invention relates to punch presses and is more particularly directed to stop mechanism associated with the die of the press and operated by the action of the punch for gauging the intermittent movement of the stock as the latter is manually or automatically fed through the die for each successive punching operation. Also, said stop mechanism has been designed to. respond quickly and definitely to the action of the press and to accomplish its desired function of gauging the intermittent movement of the strip of stock through the press with a high degree of accuracy and dependability. Furthermore, the instant device can be finely adjusted to be extremely sensitive in its operation and may be used for delicate and intricate blanking dies as a result thereof. Other features and advantages of the stop mechanism shall appear in the following detailed description of a preferred form of the instant device as portrayed in the accompanying drawing.

In the drawing:

Figure 1 is a side elevation of a set of dies of a punch press which incorporate the stop mechanism of my invention;

Figure 2 is a plan section of the lower die and stop mechanism as viewed substantially alongthe line 22 of Figure 1;

Figure 3 is a sectional view of the stop pin or gauging member as taken substantially along the line 3-3 in Figure 2;

Figure 4 is similar to Figure 3 but shows the stop pin resting upon the stock strip as the latter moves through'the dies; and

Figures 5 and 6 are plan sections along lines 55 and li-Bin Figure 3, respectively.

To illustrate the invention, Figure 1 shows a set of dies of a punch press in general with the bed plate I supporting die 8 and stripper plate 9 in proper registry below the punch Ill which is connected with punch plate II. The punch and punch plate are guided for vertical movement by means of the pressguideway l2 and are reciprocated in the usual manner to perform the punching operation. A stock strip M is fed across the top surface of the die 8 and through the guide opening I5 in the stripper plate as shown in Figures 1 and 2.

It is the object of the present invention to provide a means for controlling the feed of the strip stock through the die to obtain complete blanks and to reduce the scrap to a minimum. This is accomplished by means of a suitably hardened stop pin l6 slidably positioned in a bored opening ll 'in the stripper plate 9. Obviously, the location of the hole I! in the stripper plate 9 is predetermined by the die maker and remains the same for each particular set of blanking dies. The stop pin i6 is grooved at l8 to accommodate a spring l9' therein which spring has one leg 20 thereof fastened to the pin i6 by being swedged in a slot in the top of the pin and the other leg 2! thereof is substantially the same length or slightly longer than the pin and the leg 2! is normally urgedoutwardly. of the groove l8 about an imaginary pivot point 22.

The main function of the pin is to drop into successive openings 24 of the strip stock l4 and to be engaged by some surface as 25 of the openings in the strip stock to limit the motion of the stock through the die and to place the same in proper positionfor the next blank to be punched out.

As each blank is punched out the stop pin must be raised out of the opening wherein it has just previously dropped into and this is done by means of a trip mechanism 26 that is so positioned and devised asto be operated by some part of the punch or by the punch plate itself as the case may be. The trip mechanism includes a bracket 21 rockably supporting'a forked lifter 28 upon the pivot pin 29. The bracket 2'! is suitably secured to the stripper plate or the die as desired by means of the screws 30. A stiiT spring member 3| is secured to thelifter 28 at 32 and has a screw 34 adjustably secured to its free end as by'means of the nuts 35 to position the screw 34 in a placewhere it will be engaged by the die plate H after a predetermined movement o-f the latter. Screw 34 and its associated parts 3| and 28 are held in the relation shown in Figure 1 by the coil spring 36 carried on the pivot pin 29 and coacting between the top of the stripper plate 9 and the underside of the lifter 28 to keep the forked end 31 of the lifter down upon the top of the stripper plate.

The forked end 31 of the lifter 28 engages within oppositely disposed slots 38 located near the top of the stop pin l6, said slots being properly cut away for the sake of clearance inasmuch as the pin moves vertically and the lifter 28 rocks 'about a pivot 29 as is apparent from the drawing. Fork 3'! also prevents rotation of pin l6 within the hole I! and thereby keeps the spring IS in the proper relation to the openings in the stock strip.

In the operation of the punch press the stock is continually urged through the die manually or automatically in the direction of the stop pin .said stock material.

In addition, it should be stated that although and against the latter. The moment when the punch'descends and stamps out a blank the stop pin is raised out of the opening oraway from the leading edge of the stock strip by means of the punch plate engaging the screw 34 of the trip mechanism 26 which has been described above. When the punch is down it holds the strip stock against movement and since the 'functiorr of the stop pin ceases to exist at that time, the stop has been Withdrawn from one of the openin s 24 of the strip stock M by the action of the punch plate engaging the trip mechanism.

' In order to prevent the stop pin from dropping back into the same opening when the punch Eis being withdrawn as the punch plate H rises, the 1 spring 19 comes into play at the very instant the pin is raised out of the strip stock' opening and above the top surface of the strip stock. The lower end of the leg 2| of the springis preferably slightly longer than the pin l6 although it may be of the same length. As the pin is withdrawn from the opening in the strip of stock the spring immediatelymoves out of the groove in the pin' and in a direction opposite to the normal motion of the stock strip and in a direction away from the opening in the stock as best shown in dotted lines in Figure 3. To

allow for this movement of the spring member, the stripper plate has been notched out as at -60 and the depth of the latter can be made to suit to limit the movement of the spring member f outwardly of the stop pin.

With this form'of stop pm the dies may be operated at relatively high speeds and very close j adjustments can be made.

The pin will never drop back into the same opening and will always be. ready to engage the next successive opening no matter how fast the dies or the strip stock may be actuated.

It should be noted that. the pin i6 is the actual gauging means and that the spring I9 does not interfere with that function of said pin inasmuch the spring nests completely'within the groove ofthe pin as the edge of an opening in the strip stock movesup against the pin. In other words,

the spring is held in the pin groove by the stock material during the punching operation and thereafter the spring will immediately snap out of the groove and ride onthe stock material at the instant that the stop the member 3| was described as a stiff spring member it may be considered as rigid for the normal operation of the device and is only of the pin is moved out of shape shown and somewhat resilient to prevent bending or breakage of the parts of the trip mechanism, etc., in the event that the stock should become jammed under which circumstance the stop pin and its trip mechanism would be kept in raised position by the failure of said stock to move and bring an opening beneath the stop pin.

It should ,iurther be noted that the drawing merely'illustrates a preferredjembodiment of the device of my invention and that I do not intend tobe limitedthereto specifically, but only in so far as shall be determined by the breadth and "scope of the appended claims.

What I claim is:

1 In combination, a punch, a die, a stripper plate associated with said die and having means j for guidin'g'said strip stock in a fixed path across said die, gauge means cooperating with the strip stock through the openings therein to halt the stock in successive predetermined positions upon said die,.trip means for holding said stop pin in operative engagement .within each successive opening in said strip stock during the punching operation, operative means associated with said punch to engage said strip means for moving 'said stop pin out of each successive opening in said strip stock, and resilient means connected with said stop pin and disposed for movement out of thesurface ofsaid pin in a direction opposite to the-movement of said stock'through said die, said resilient means coopearting with the strip stock to hold saidstop pin in inoperative raised position to allow movement of said stock to the L next successive punching position.

2. In combination, a punch, a die, a stripper plate associated with said die and having means for guiding stock in a fixed path across said die,

I and gauge means for interrupting the movement of said stock in successive predetermined locations upon said die, comprising a stop member for engaging within punched openings in the

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