US2454432A

US2454432A - Punch press stripper

Info

Publication number: US2454432A
Authority: US
Inventors: Theron T Crandall
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-11-22
Filing date: 1946-11-22
Publication date: 1948-11-23
Anticipated expiration: 1965-11-23

Description

Nov. 23, 1948. 'r. T. CRANDALL ,PUNCH PRESS STRIPPER Filed Nov. 22, 1946 2 SheecsSheet 1 INVENTOR. I THE/QU/V TOQA/VDALL w mk 'r. 11. CRANDALL PUNCH PRESS STRIPPER Nov. 23, 1948.

Filed Nov. 22, 1946 2 Sheets-Sheet 2 INVENTOR. v THERO/V 7' (RANDALL ATTD RN EYB Patented Nov. 23, 1948 I TED STAT E S I PATENT OFFICE PUNGH,:=PRESS STRIPPER Theron 1T. Crandall, Cano'galPark, Calif,

Application November 22, 1946, Serial No. 711,783

punch of the press to strip the work from the punch, and which is especially designed for use with quick-acting machines of the pneumatic or other power operated "and upright type.

As is well known, after the reciprocatingpunch on its working stroke passes through the work, 7

as a metal sheet, and into the die, frequently on the return stroke of the punch the work binds or sticks to the punch .andis lifted from the die. To remedy this objectionable condition time and labor are required in removing the work from I the punch and .in re-assemb'ling "the parts for subsequent operations.

The primary object :of .my invention is the -pro vision of a stripping mechanism for co iaction with the reciprocating punch, that is automatically actuated by the punch on its working stroke to hold down the work "on the die, and springoperated for following, after-a delay interval, the punch on its return or retracting stroke. The stripping mechanism includes a minimum number of parts that may "with facility be manufactured at low cost of production, and assembled; and installed with standard types of punching machines with conveniencefitoinsure -a :mechanism' that is simple in operation, reliable in the performance of its functions, and effective in use.

The invention consists in certain novel combinations and arrangements of parts as will hereinafter be described and more specifically set forth in my appended claim.

In the accompanying drawings I have illustrated one complete example of the physical embodiment of my invention wherein the parts are combined and arranged in accord with one mode I have devised for the practical application of the principles of the invention. It will be understood however, that changes and alterations are contemplated and may be made in these exemplifying drawings and mechanical structures, with in the scope of my claim, without departing from the principles of the invention.

Figure 1 is a view in side elevation showing so much of a punching machine as is necessary to illustrate the installation of the stripping mechanism, which is here shown in held down position with the work on the die; and Figure 2 is a front face view of the equipment shown in Fig. 1.

Figure 3 is a horizontal sectional view as at line 3-3 of Fig. 2; and Figure 4 is a similar view at line 44 of Fig. 2.

Figure 5 is a view similar to Fig. 1 but showing the punch uplifted, together with the stripper mechanism, in order to give access to the work for adjustment of the work on the die.

4 IClaim. (01164-410) In order that the general arrangement and utllityof parts may readily be understood I have shown .in the assembly drawings a portion of the machine frame F, including the die holder H, upon which the die D is mounted; and a metal sheet on which the pattern has previously been laid out by a template, is designated as the work W, andsupportedonthedie for punching according to the pattern.

The punch shaft S, which is power operated to reciprocate vertically in bearings of the frame F directly above the die is fashioned with a punch P and pilot point or nib N, and as indicated in the drawings, the lower end of the shaft S forms an annular shoulder A.

.In carrying out my invention the reciprocating shaft S is equipped with a vertically adjustable actuating lug or abutment in the form of a collar or ring I that is mounted on the shaft, and fixed in set position by means ofia set screw or set bolt 2 threaded through the collar against the shaft. This rigidly mountedactuating lug I travels with the shaft to automatically trip a holding-down .or latch device for the stripper at the end of its upward or return stroke and release the stripper as indicated by the position of parts of the mechanism .in Fig. 5.

Thestripping mechanism includes a stripper or holding down arm 3 having a forked or bifur cated free end 4 that encompasses the punch P, and. this arm is pivoted or hinged at 5 to the lower end of a sectional, vertically adjustable bracket composed of a lower section B to which the stripper arm is connected by a helical spring I that tends to elevate the forked end of the stripper arm and cause it to follow the punch on its upward or return stroke. In addition to the lower section 6, this sectional bracket includes a fixed section 9 and these sections are adjustably connected by means of a pair of slots 1, l in the lower section and pairs of clamp bolts 8, 8 mounted on the fixed section, in order that the bracket may with facility be adapted to the dimensions of a punching press. The fixed section 9 of the bracket is fashioned with an angular flange 10 that is firmly secured in proper position by bolts I l which attach it to the frame F.

On the working stroke of the punch the stripper arm 3 is pressed down against tension of spring I by contact of the shoulder A with the forked end 4 of the arm 3, and as the punch P passes through the work W and into, die D the stripper is held down, by arm I9 and stop lug 23, in the position of Fig. 1, until it is tripped on the return or upper stroke-of the punch.

For releasing the holding down device of the stripper on the up stroke of the punch, the lug or collar l on the shaft S of the punch co-acts with an oscillatible trip lever having a short arm l2 and a right angular longer arm l3 and pivoted at M on a bracket arm l5 which is rigidly mounted, as by welding, on the attaching flange ill of the adjustable bracket 6-9.

The bracket arm I5 is provided with bearing holes, as 16 for the pivot pin 14 in order to permit accurate adjustment in the assembly of parts, and a cotter pin as H is employed to retain the pivot pin against displacement.

The actuating arm 12 of the trip lever is located above the lug or collar I and in the pathof movement of the reciprocating collar or lug, so that on its upstroke the lug will strike arm 12 and thereby swing the depending arm l3 of the lever inwardly toward the punch, The lower end it of the arm i3 is bifurcated to straddle an obliquely disposed locking link or spring latch l9 that is instrumental in holding down the stripper 34 on the work as the punch is being withdrawn therefrom. The bifurcated end I8 of the trip lever co-acts with a cross-pin 20 of the latch I9 to form a loose pin and slot connection between these parts that permits relative movement of the parts without actually disconnecting them.

The latch arm or locking link 19 is pivoted at 2! on the upper face of the stripper, and an aux- I iliary spring 22 forms a spring hinge that tends to swing the link l9 away from the punch and constantly in contact with the pin 20; and when free to act, spring 122 swings the link or latch l9 into position under an abutment 23 welded on bracket section 9.

With the parts in position of Fig. 5 ready access is had to adjust the work W on the die for a punching operation, and as the punch descends, it pushes the stripper 34 downward. v

The lug or collar I withdraws its support from the arm E2 of the trip lever leaving the lever dangling freely, and as the stripper is pressed down, the latch 18 under force of spring 22 is swung on its pivot sending its upper free end against the section 9 of the supporting, bracket and under the abutment 23 of the bracket; and the stripper is thus held down on the work W by the link 19 in engagement with its stop or abutment 23, as indicated in Fig. 1.

On the upstroke of the punch, the stripper holds down the work until the collar or lug l strikes the short arm I2 of the trip lever, and by positive action of the trip leveragainst pin 20 the link, l9, which is spring-held, is withdrawn from under the stop or abutment 23. Now the extended spring 1, by contraction, lifts the stripper to position of Fig. 5 to clear the work and die and permit adjustment of the work, and the stripper mechanism is again in position for operation under a succeeding working stroke of the punch.

The pin 20 rides or slides at all times in close contact with the depending arm or bifurcated end l8 of the arm l3 of the trip lever, and the springs 1 and 22 constantly tend to hold the pin against the arm.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

The combination with a reciprocating punch having an actuating lug, and a fixed frame, of an adjustable bracket and means-for fixing it on the frame, a stripper pivoted on the bracket and having a forked free end engaging the punch, a lifting spring connecting the stripper with the bracket, a spring-pressed link pivoted on the stripper and an'abutment on the frame for engagement by the free end of the spring-pressed link, an L-shaped trip lever having one arm in the path of said lug and pivoted on the frame, a second lever arm straddling the link, and a cross pin on the link in constant engagement with the straddling arm.

THERON T. CRANDALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 655,074 Graves July 31, 1900 1,933,465 Woodburn Oct. 31, 1933