US3178977A

US3178977A - Stripping device

Info

Publication number: US3178977A
Authority: US
Inventors: Robert H Mitchell
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1962-10-23
Filing date: 1962-10-23
Publication date: 1965-04-20
Anticipated expiration: 1982-04-20

Description

April 20 1955 R. H. MITCHELL 3,178,977

STRIPPING DEVICE Filed oct. 25, 1962 L ,1.1, HJ. L1: fw www wml ,ahi/widen,

i; BY /Q ATTORNEY United States Patent O 3,178,977 STRIPPING DEVICE Robert H. Mitchell, Winston-Salem, N.C., asslgnor to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Oct. 23, 1962, Ser. No. 232,405 Claims. (Cl. 83-145) This invention relates to a stripping device land more particularly to a selectively positionable stripper device to be used in conjunction with various arrays of punches.

It is the conventional practice in the use of punch and die units to design the stripper to fit the contour of the punch and die itself, and, therefore, make the stripper applicable to only that conguration for which it was designed. The production of a large quantity of a single part to be made on a punch and die, makes this design feasible. However, where small quantities of the product are anticipated, such as in a job shop operation, the use of a punch and die made specifically for one part, becomes uneconomical. To overcome this problem, tool designers have devised punch and die units which, by various means well known in the industry, are capable of accepting an iniinite number of variations in the pattern of punches and dies. These punch and die units are commonly known as universal punch and die sets. Stripper arrangements used on these universal punch and die sets normally consist of a spring-type or stationary stripper which is integrally made with or attached to each individual punch or die member. This design has the disadvantages, among others, of limiting the closeness with which the punches and dies can be arranged with respect to one another, and is inherently costly since na separate stripper is required for each punch and die set.

An object of this invention is to provide a new and improved stripping apparatus which can be used with an inlinite number of punch and die arrangements.

Another object of this invention is to provide a stripping device, including stripper bars, which may be randomly inserted into spaces between the paths of movement of the punches.

Still another object of this invention resides in the provision of a work stripping device for use with a universal punch and die set utilizing an infinite number of variations in the arrangement of punches and dies wherein the stripper bars are randomly interspaced between the punch members and are held in place by locking devices.

With these and'other objects in view, the present invention contemplates a plurality of stripper bars to be placed randomly between the punches of a die set, and a pair of channel members mounted on the face of and along opposite edges of the die set, each of the channel members having transverse elongated slots formed in the channel sides to receive the stripper bars. Each channel member also has a pair of opposed guideways formed in the inner side walls of the channel into which are slidably mounted a plurality of locking members which are used for holding and locking down the stripper bars.

A complete understanding of this invention may be had by reference to the following detailed description when read in conjunction with the accompanying drawings illustrating a preferred embodiment thereof, wherein:

FIG. l is a plan view of a die set utilizing a stripping device of the present invention which shows a random arrangement oi stripper bars arrayed in spaced between paths of movement of punch members;

FIG. 2 is a side elevation showing a transverse slot of a channel member for receiving the stripper bars;

FiG. 3 is a front elevation view of the stripper device mounted on a die plate showing one channel member partially cut away, with a guideway in the inner side walls which receives locking members; and

b FIG. 4 is a detailed view of one of the locking memers.

Referring in general to FIGS. 1 and 2, a die unit, generally indicated by the reference numeral 11, is shown having a pair of channel members 12 and 13 mounted on each side of a die bed 14. The channel members are made up or machined to provide vertically extending sections 16 and -a horizontal bottom section 17 (FIG. 2). The channel members 12 and 13 are secured to the die bed 14 by bolts 19. Each of the side walls 16 has an elongated transverse slot 21 (FIG. 2) formed therein to receive stripper bars 22. Sliding within cruciform slots 23 (FIG. 3) formed in the walls 16 of the channel members are a plurality of clamps, generally indicated by the reference numeral 24. In cross section, the cruciform slot consists of grooves formed in side walls 16 and a vertical section which extends through members 12 and 13 and terminates at the slot 21. Screws 18 brace and prevent distortion in slot 21, arising from pressure of clamps 24 and withdrawal of punches 26 from a workpiece. Stripper bars 22 are shown extending crosswise through transverse slots 21 in the channel walls 16 and randomly into spaces between the paths of movement of individual punches 26 mounted on a punch platen 27.

As shown in FIG. 4, each clamp member 24 comprises a slide block 31 which slides within side grooves of the cruciform slot 23 to position the clamp member. Each slide block 31 is internally threaded to receive a threaded portion of an Allen head bolt 33. An unthreaded end 34 of the Allen head bolt 33 is rotatably positioned within a recess formed in the top of a cylindrical clamp block 36. Upon turning each bolt 33 within the slide block 31, the associated clamp block 36 is moved down to force and lock each stripper bar 22 against the bottom 17 of the channel members 12 and 13.

In the use of this device, referring first to FIG. 3, a punch platen 27, sliding on liner pins 28 and having individual punch members 26 extending therefrom,`is positioned Vover die plate 29. The punch platen is then brought down on the liner pins 28 so that the punch members are engaging the die plate 29. While the punch and die unit is in this closed position, the stripper bars are inserted into the elongated transverse slots 21 in the channel members 12 and 13 and through a slot formed in the bottom of clamp block 36 of the clamp member 24. The stripper bars are then extended into the spaces between and in close proximity to the punch members in a random fashion as shown in FIG. 1. Clamp block 36 is rotatably positioned on the unthreaded end of Allen bolt 33 so that the clamp blocks are rotatably adjustable to the random angle of insertion of stripper bar 22 into the space between the punch members 2-6. The clamp members with stripper bars inserted therethrough are positioned along the channel members by sliding them along the cruciform slots 23 formed in channel members 12 and 13. It is necessary to secure the stripper bars in their random positions to avoid subsequent interference with the punch members during the punching operation. In order to secure the stripper bars in place after positioning of the stripper bars over the die plate, the clamp members are tightened on the stripper bars by turning the Allen head bolt. This turning of the bolt 33 forces the internally threaded slide blocks 31, riding on the bolt 33, to push against the top of the cruciform slot 23 to consequently force the clamp block 36 downwardly on the stripper bar 22 which is pressed Vagainst the channel bottom section 17.

From the foregoing description, it will be seen that adjustment of the position of the stripper bars is a simple and fast operation. First the Allen head bolt is turned to loosen the clamp block 36 on the stripper bar and to loosen the slide block 31 in the cruciform slot 23. Subsemembers and the stripper bars held therebeneath are also movable longitudinally in the cruciform slot formed in the channel members as `a result of the freeing of slide block 31 by the loosening of the bolt 33.

In the operation of the die unit il, and after the stripper bars have been positioned as described in the foregoing description, the punch platen of the press is brought to the top of its stroke. A workpiece 41 such as thin metal or plastic sheet is then positioned on the die plate 29 and under the stripper bars 22. The punch platen is then brought down to commence the punching operation. The punch members penetrate the workpiece and travel into the die openings of the die plate 29. The punch platen then begins to travel upwardly removing the punch members from the workpiece. The stripper bars 22 which are positioned close to the punches, engage the workpiece v il at this point and strip it from the punch to prevent the workpiece from clinging to the punch members as the punch platen is brought to the top of its stroke. With the close positioning of the bars to the path of movement of the punches, the punches may be withdrawn from the sheet 41 without any tendency to tear or deform the sheet about one punched holes.

It is to be understood that the above-described arrangements are simply illustrative of the application of the principles of this invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

l. A stripping device to be used in a multiple punch and die unit comprising,

a stripper bar,

a member mounted on one side of the die andrprovided with a slot extending therethrough to receive the stripper bar for longitudinal, transverse and angular movement in a horizontal plane between the punches, and

a locking device slidably mounted on the member and projecting into the slot for locking the stripper bar in any or" a variety of longitudinal, transverse, and anguiar positions adjacent to the path of movement of the punch to hold a workpiece on the die upon removal of the punch from the workpiece.

2. A Work stripping device used in conjunction with a plurality of punches and a die member comprising,

a channel member mounted on one side of the die membei having a pair of aligned transverse slots formed in the sides and extending therethrough,

stripper bars interspaced and randomly extending through said slots for longitudinal, transverse, and angular movement in a horizontal plane between the punches, and

locking devices slidably mounted in the channel member for locking the stripper bars in any of a variety t of longitudinal, transverse, and angular positions to engage the work during a punching operation.

3. In a workpiece stripper to be used with a universal punch and die unit having a plurality of punches,

a plurality of elongated stripper bars placed in random angular positions between the punches,

a pair of oppositely disposed channel members mounted on opposed sides of the die and each having transverse slots formed in each wall to receive the stripper bars for longitudinal, transverse, and angular movement therethrough, and

locking devices slidably mounted in the channel members having depending rotatable ends for engaging and locking the stripper bars in said random positions to hold the workpiece in place.

4. In a hold-down device for use in punch and die apparatus wherein la plurality of punches are randomly mounted in a ram that is reciprocated into and out of a die mounted on a bed,

a pair of channel members mounted on the face of and along opposite edges of the bed, each of said channel members having Itransverse elongated slots formed in the channel sides,

a plurality of stripper bars extendingl through said transverse slots and into the spaces between the paths of movement of said punches for longitudinal, transverse, and angular movement therebetween,

each of said channel members having a pair of opposed guideways formed in the inner side walls, and

a plurality of locking members having sections slidably mounted in the guideways for holding the stripper bars in any of a variety of longitudinal, transverse, and angular positions.

5. In a work stripping device for use in a multiple punch and die unit having a plurality of punches and a die,

two pairs of parallel plates mounted on the face of and along opposite edges of the die unit, each of said parallel plates having an elongated horizontal slot formed therein, and having oppositely disposed and horizontally extending grooves formed in their inner sides,

a plurality of stripper bars extending through the elongated slots for longitudinal, transverse, and angular movement into spaces between the extending and randomly positioned punches when the punches are positioned within the die, and

a plurality of clamp members having rotatably mounted depending ends for holding the stripper bars in a variety of longitudinal, transverse, and angular positions and having lugs slidably supporting the clamp members inV the oppositely disposed grooves of the parallel plates for selectively positioning the depending ends in engagement with the stripper bars.

References Cited by the 'Examiner UNITED STATES PATENTS 475,549 5/ 92 Firnstein 83-146 1,383,673 7/21 Thomas 83-145 1,500,263 7/24 Perrault 83-146 1,646,851 l0/27 Campbell 83-146 ANDREWR. JUHASZ, Primary Examiner. HUNTER C. BOURNE, JR., Examiner.

Claims

1. A STRIPPING DEVICE TO BE USED IN A MULTIPLE PUNCH AND DIE UNIT COMPRISING, A STRIPPER BAR, A MEMBER MOUNTED ON ONE SIDE OF THE DIE AND PROVIDED WITH A SLOT EXTENDING THERETHROUGH TO RECEIVE THE STRIPPER BAR FOR LONGITUDINAL, TRANSVERSE AND ANGULAR MOVEMENT IN A HORIZONTAL PLANE BETWEEN THE PUNCHES, AND A LOCKING DEVICE SLIDABLY MOUNTED ON THE MEMBER AND PROJECTING INTO THE SLOT FOR LOCKING THE STRIPPER BAR IN ANY OF A VARIETY OF LONGITUDINAL, TRANSVERSE, AND ANGULAR POSITIONS ADJACENT TO THE PATH OF MOVEMENT OF THE PUNCH TO HOLD A WORKPIECE ON THE DIE UPON REMOVAL OF THE PUNCH FROM THE WORKPIECE.