US3566730A

US3566730A - Punch press having ram with stripping means

Info

Publication number: US3566730A
Authority: US
Inventors: James J Pancook
Original assignee: Houdaille Industries Inc
Current assignee: Strippit Di Acro Houdaille Inc
Priority date: 1969-02-25
Filing date: 1969-02-25
Publication date: 1971-03-02
Anticipated expiration: 1988-03-02

Abstract

A punch press has a frame receptive of a punch and stripper assembly and a die, and has a ram which includes a number of fluid-pressure biased pistons which act through force transmitting means on the stripper.

Description

United States Patent James J. Pancook Tonawanda, N.Y. 802,098

Feb. 25, 1969 Mar. 2, 1971 Houdaille Industries, Inc. Buffalo, N.Y.

Inventor Appl. No. Filed Patented Assignee PUNCH PRESS HAVING RAM WITH STRIPPING MEANS 9 Claims, 1 Drawing Fig.

U.S. Cl 83/137 Int. Cl. B26d 7/18 Field of Search 83/ 1 37 56] References Cited UNITED STATES PATENTS 2,586,695 2/1952 Mueller 83/137 2,642,138 6/1953 Macewka.... 83/137 3,107,567 10/1963 Lindner 83/137X 3,119,292 1/1964 Schmid 83/137X Primary Examiner-William S. Lawson AttorneyHil1, Sherman, Meroni, Gross and Simpson ABSTRACT: A punch press has a frame receptive of a punch and stripper assembly and a die, and has a ram which includes a number of fluid-pressure biased pistons which act through force transmitting means on the stripper.

PUNCH PRESS HAVING RAM WITH STRIPPING MEANS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to structure employed in a heavyduty punch press, and more specifically to such a press having a ram wherein fluid-pressure-biased pistons serve to control or operate stripping means for stripping a workpiece from a punch.

2. Prior Art Punching machines as known in the past, particularly those able to punch a substantial size hole in a workpiece of substantial thickness have relied on various mechanisms for stripping the workpiece from the punch. To some degree, such stripping mechanism is tailored to fit the job to be done, due consideration being given to punch size and the workpiece thickness. However, when interchangeability of tooling is provided in a punch press wherein standardized tools are provided that have a wide variety of punch size and that are capable of acting on a wide variety of material thicknesses, the stripping means have on occasion been found to be of inadequate strength, or have been found to be so rigid that they may even aid deforming the workpiece when deformation is not desired.

SUMMARY OF THE INVENTION The punch press of the present invention uses in the ram an annular piston within which is disposed a further number ofindependently operable pistons for acting through a number of transmitting means so located as to cooperate with tooling having a variation in envelope size.

Accordingly, it is an object of the present invention to provide means by which fluid power may be used to strip a workpiece from a punch.

Another object of the present invention is to provide a punch press especially adapted and arranged to strip a wide variety of workpiece thickness from a wide variety of punch size.

Many other advantages, novel features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheet of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.

ON THE DRAWINGS The single FIG. is a vertical cross-sectional view, partly in elevation, of a fragmentary portion of a punch press provided in accordance with the principles of the present invention.

AS SHOWN ON THE DRAWINGS The principles of this invention are particularly useful when embodied in a punch press or a punching machine such as is fragmentarily illustrated in the drawing, generally indicated by the numeral 10. The punch press 10 includes a frame 11 having a pair of spaced arms including an upper arm 12 and a lower arm 13, a reciprocably driven ram 14 located at the upper arm 12, and vertically stationary means 15 on the frame 11 for guiding and driving reciprocable punch and stripper means generally indicated at 16. The punch and stripper means 16 coacts with a die 17 which is supported on the lower arm 13.

The ram 14 includes a driving portion 18 and a lower section 19 which resembles an inverted cup. Within the lower section 19, there is secured a stem 20 which extends into the interior of the lower section 19 where it has a cylindrical enlargement 21 spaced from an inner wall 22 of the lower section 19 to define an annular chamber 23 within which there is slidably disposed and guided a fluid-pressure biased piston 24. Fluid pressure is admitted through a port 25 and communicates with the chamber 23. On application of fluid pressure to the chamber 23, the piston 24 is biased in a downward direction to a position limitedby a ram plate 26 which is secured to the enlarged portion 21 of the stem 20. The ram plate 26 has a T-head 27 integral therewith for detachably forming a coupling or connection with the punch and stripper assembly 16. The ram plate 26 has a first series of transmitting means 28 in the form of trapped plungers which have a head or snap ring that is received in a counterbore in the ram plate 26 by which such plungers 28 are trapped. For all practical purposes, the plungers 28 have an upper end that is substantially flush with the top surface of the ram plate 26 so that the annular piston 24 can engage either the top surface ofthe ram plate 26 or the upper ends of the trapped plungers or transmitting means 28.

When pressure is applied to the chamber 23, it in effect serves as a spring urging the piston 24 downwardly for acting through the transmitting means 28 and thus onto a number of transfer pins 29 which form part of the stripping member that is a part of the tooling carried in the punch press. Thus, a stripping force is made available for transfer to a stripping member. 4

The details of thepunch, die and stripper, which form a set, do not form an essential part of the punch press of this invention, and may vary a good deal. To that end, particularly where smaller tooling is employed, the stripper pins 29 may be located somewhat closer to the center, such as for engaging a second series of transmitting means or transfer plugs 30. The transmitting means 30 is substantially the same as the transmitting means 28 but is actually independently driven and used. To that end, the ram assembly 14 includes a further pair of independently movable fluid-pressure

biased pistons

31, 32 which are slidably disposed in a pair of

bores

33, 34 which are provided in the enlarged portion 21 of the stem 20. Each of the

pistons

24, 31,32 has a sliding seal so that the end thereof that acts on one ofthe transmitting means 28, 30 is a low pressure end, whereas the opposite end is the fluid-pressurized or high-pressure end. To that end, the

bores

33, 34 communicate with a passage 35 which leads to the chamber 23.

The piston 24 has a somewhat larger effective working area than either of the

pistons

31, 32 while the

pistons

31, 32 are here shown as being of the same size and disposed a uniform distance from the center of the ram 14. This structure enables the ram assembly 14 to be used with other punch and stripper assemblies 16 having a scaled-down dimension wherein the transfer pins 29 would be disposed in alignment with the transmitting means 30..

The vertically stationary means 15 on the frame 11 may comprise a turret which is locked in a selected position with the proper tooling in alignment with the ram 14, or it may constitute guide meansin a single station press. When a worki piece is admitted between the die 17 and a punch tip 36, the ram assembly 14 is actuated which positively and directly drives the punch tip 36 through the workpiece into the die 17. Before the punch tip 36 enters such die, a stripper plate 37 engages the upper surface of the workpiece and a reactive force is providedby the lower arm 13, through the die 17, the workpiece, the stripper plate 37, a stripping sleeve 38,'the transfer pins 29, the transmitting means 28 or 30, and the piston 24 or the pistons 31, 32which is opposed by fluid pressure in the chamber 23. However, as the chamber 23 decreases in size with the relative downward movement ofthe ram with respect to the arrested pistons, energy is stored by means ofsuch fluid, and as soon as the punch tip 36 breaks through the workpiece and the stroke of the ram reversed, the pressure in such chamber 35 continues to act through the

appropriate pistons

24, 31, 32 and the transfer pins 29 to hold the stripper plate 37 against the workpiece until the transmitting means 28 or 30 again reengages the upper side of the ram plate 26.

Although various minor modifications might be suggested or made by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon, all such embodiments as reasonably and properly come within the scope of the appended claims.

Iclaim: v l. A punch press comprising in combination: I

a. a frame having spaced arms with a reciprocable ram disposed at the upper arm;

b. vertically stationary means for being carried by said frame for reciprocably guiding punch and stripping means;

. means for supporting die means on said lower arm in position to coat with the punching means;

d. at least a pair of independently movable fluid pressure biased pistons slidably disposed in said ram; and

e. at least a pair of independently movable means respec tively coating with said pair of pistons for transmitting a stripping force from at least one of said pistons to said stripper means.

2. A punch press according to claim 1 wherein one of said pistons is annular and at least one other of said pistons is disposed within said one piston.

3. A punch press according to claim 2 wherein said pistons are spaced from each other for alternatively coating with punch and stripper means of differing size.

4. A punch press according tol claim 1 wherein one of said pistons has a somewhat larger working area than the other,

said pistons being connected to a common source of fluid pressure.

5. A punch press according to claim 1 in which one of said pistons is annular and two other of said pistons are disposed Within said one piston.

6. A punch press according to claim 2, including a ram plate secured to said arm and disposed at the low-pressure side of said pistons, and a series of said transmitting means trapped in and extending substantially through said ram plate near the outer periphery of said annular piston.

7. A punch press according to claim 6, including a further number of said transmitting means trapped in and extending substantially through said ram plate in alignment with the other of said pistons.

8. A punch press according to claim 1, in which said movable means are so shaped as to be retained within said ram in the absence of the punch and stripper means.

9. A punch press according to claim 1, in which said movable means have a length in the direction of ram travel which corresponds to the minimum spacing between said pistons and the punch and stripper means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, a D d March 2,

Inventor(s) James J- PaHCOOK It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 40, change "thickness" to --thicknesses--;

Col. 1, line 41, change "size" to --sizes--;

C01. 3, line 9, change "coat to --coact--;

C01. 3, line 13, change "coating" to --coac'ting-..;

C01. 3, line 20, change "coating" to --coacting--;

Signed and sealed this 23rd day of November 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTI'SCHALK Attesting Officer Acting Commissioner oi Pat

Claims

1. A punch press comprising in combination: a. a frame having spaced arms with a reciprocable ram disposed at the upper arm; b. vertically stationary means for being carried by said frame for reciprocably guiding punch and stripping means; c. means for supporting die means on said lower arm in position to coat with the punching means; d. at least a pair of independently movable fluid pressure biased pistons slidably disposed in said ram; and e. at least a pair of independently movable means respectively coating with said pair of pistons for transmitting a stripping force from at least one of said pistons to said stripper means.

4. A punch press according to claim 1 wherein one of said pistons has a somewhat larger working area than the other, said pistons being connected to a common source of fluid pressure.