US1930762A

US1930762A - Stripping device for punch presses and the like

Info

Publication number: US1930762A
Application number: US621943A
Authority: US
Inventors: George H Leland
Original assignee: Leland Electric Co
Current assignee: Leland Electric Co
Priority date: 1932-07-11
Filing date: 1932-07-11
Publication date: 1933-10-17
Anticipated expiration: 1950-10-17

Description

Oct. 17, 1933. LELAND 1930,762

STRI PP-ING DEVICE FOR PUNCH PRESSE S AND THE LIKE Filed July 11, 1932 2' Sheets-Sheet l Fig.1-

l/v VENTOR. GEO/P65 h. L [A AND. y

his ATTORNEY.

Oct. 17, 1933. G. H. LELAND STRIPPING DEVICE FOR PUNCH PRESSES AND THE LIKE Filed July 11, 1932 2 Sheets-Sheet 2 his ATT0RNY Patented Oct. 17, 1933 UNETEB STATES riiijh.

s'rniPPING DEVICE FOR PUNCH PBESSES AND THE LIKE George H. Leland, Dayton, Ohio, assignor of cne half to The Leland Electric Company,

Dayton, Ohio, a corporation of Ohio Application July 11, 1932. Serial No. 621,943

17 Claims.

This invention relates to a stripping device for punch presses and the like. In the operation of a punch press it frequently happens that the blank, or part which has been severed, will adhere to the face of the punch and be withvn from e die when the punch is retracted, this being particularly liable to happen when a liquid cutting compound is applied to the face of the material from which the blank is to be cut. Further, in many cases, and especially in the case of progressive die work, the punch is provided with a pilot, such as a stud or pin, adapted, to enter a previously formed opening in that part of the material which is to be severed, for the purpose of properly alining the same with the punch and die. Such a pilot necessarily fits snugly within the opening and has a tendency to withdraw the severed blank from the die when the punch is retracted. This withdrawal of the blank from the die is objectionable in any case but it is particularly objectionable in the case of automatic presses as it will usually clog the operation of the press and make it necessary to shut down the press and remove the displaced blank. In an effort to prevent the blank adhering to the punch or pilot it has been customary heretofore to utilize a stripping device comprising spring actuated plungers or pins mounted in the punch and adapted to be moved into the punch by engagement with the stock as the punch moves toward the stock and to be projected by the springs as the punch is retracted. In such a device the springs must be of sufficient strength to strip 1 the blank from the face of the punch and from the pilot but they must not be strong enough to istort the blank or'hold it so tightly against the die that the pilot will be unable to move it into alinernent without distorting the opening through which the pilot operates. This requires a nicely regulated tension on the spring which is difficult to secure and to maintain and as a result such spring actuated stripping devices have not been satisfactory in operation.

One object of the present invention is to provide a positive stripping device which will operate without the use of springs to strip the blank from the face of the punch and from the pilot.

A further object of the invention is to provide such a stripping device in which the plunger or plungers will be retracted before they engage the stock or material from which the blank is to be cut, thus avoiding any possible interference with the action of the pilot.

A further object of the. invention is to provide such a device in which the stripping plunger will be retracted duriru the initial portion of the downward movement of the punch and will be retained in its retracted position until the punch begins its upward movement and will then be positively caused to project beyond the face of the punch to hold the blank in the die while the punch and pilot strip themselves from the blank in receding.

A further object or" the invention is to provide such a device which will be simple in its construction and operation and which may be applied to a punch press without material modification in the construction thereof.

Other objects of the invention will appear as the device is described in detail.

In the accompanying drawings Fig. 1 is a vertical sectionalv View taken through a stripping device embodying my invention and showing the same applied to a punch press with the punch in a partly lowered position; Fig. 2 is a vertical section taken through the stripping device showing the position of the parts as the punch begins its upward movement; Fig. 3 is a section taken on the line 3-3 of Fig. 1; Fig. 4 is a section taken on the line -i=i of Fig. 1; Fig. 5 is a top plan view of the friction device; and Fig. 6 is a side elevation of the friction device.

In these drawings I have illustrated one embodiment of my invention and have shown the same as applied to a punch press of conventional construction but it will be'understood that the device may take various forms and may be applied to punch presses of various kinds without departing from the spirit of the invention.

I have illustrated only so rnuchof the punch press as is necessary for an explanation of the application of t e invention thereto and, as here shown, this press comprises a bed plate 6 on which is mounted a die 7. Mounted for vertical movement on the frame of the press is a ram 8 which may be operated in the usual or any suitable manner. Supported by this ram is a punch 9 which, in the present instance, is carried by a plate 10 which in turn is secured to the ram 8, the rain and the plate constituting the support for the punch. The punch is provided with a pilot ll projecting below the operative face thereof and adapted to enter an opening 12 previously formed in the part of the material which is to be severed, a group of severed blanks being shown in the die at 13 in Fig. 2.

The punch is provided with one or more, in the present instance three, guideways 14, which, ill) as here shown, comprise vertical bores having their upper portions enlarged, as shown at 15. Slidably mounted in the respective guideways are plungcrs or stripping pins 16 which are of such a length and so arranged that their lower ends may project below the lower or operative face 0:" the punch to strip the blank therefrom. In the present arrangement the supporting plate 1-? is provided with a recess 1'? arranged in line with the guideways in the punch and into which the up er ends of the plungers extend.

Connected with the plungers is a'suitable actuating device which, in the construction here shown, comprises a rod 18 which extends through the supporting plate 10 and ram 8 and is capable of vertical movement with relation thereto. The lower end of this rod extends into the recess 17 and is connected with the plungers 16. As here shown, the rod has rigidly secured to its lower end a head or spider the laterally extending parts of which are slotted to embrace the upper ends of the plungers 16, these plungers having enlarged upper ends provided with circumferential grooves 20 to receive the slotted portions of the spider. The grooves 2-3, are of a width substantially equal to the thickness of the d parts of the spider so that the plung- 0t" ers will move with the spider. The spider is of the depth of the recess a thickness less than 1'5, the upper part of the recess being preferably provided with extensions 21 to receive those parts of the plungers which project above the spider. at will be apparent, therefore, that the plunger-s and the punch are capable of relative movement, this relative movement being controll d by the contact of the spider 19 with the upper and lower walls of the recess 1'7, the lower wall of the recess being formed by the top of the punch 9. The amount of movement thus erinitted is such that when the spider 19 is in contact with the lower wall of the recess the plungers will project below the operative face of the punch far enough to strip the blank from the pilot 11, and when the spider is in engagement with the upper wall of the recess the plungers will be withdrawn into the guideways 14 and their lower ends will be either flush with or slightly above the operative face of the punch. he plungers are projected and retracted by holding the actuating rod 18 against movement with the punch during a portion of each movement of the latter. This is preferably accomplished by applying to the actuating rod a friction device which will retard its movement atthe beginning of each movement of the ram. Thus when the ram begins its downward movement the rod will be held against movement until the upper wall of the recess has engaged the spider 19, thus causing the plungers to be retracted and to be retained in their retracted positions as the rod is then moved downwardly by the ram against the action of the friction device. When the ram begins its upward movement the plungers will be held against movement, and in contact with the blank, until the spider has engaged the lower wall of the recess and will then be carried upward with the ram and the punch. The friction device may take various forms but it is preferably carried by a fixed part of the press arranged above the head of the ram. As here shown, the frictional device is carried by a frame member comprising two parallel bars 22 rigidly secured at their ends to other frame members 23 mounted on the press. The friction device itself comprises a hollow member 24, preferably substantially cylindrical in shape, which is arranged between the bars 22 and has at its upper end an integral plate 25 which overlaps the upper edges of the bars and supports the cylindrical member thereon.

Cross bars 26 engage the lower edges of the supporting bars 22 and are connected with the respective end portions of the plate 25 by bolts 27, thereby enabling the cylindrical member 24 to be rigidly clamped in position on the supporting bars 22. The cylind ical member 2-: is of an internal diameter substantially greater than the diameter of the actuating rod 18 and mounted in this cylindrical member and about the actuating rod is a series of friction elements 23, suitable frictional material 29 being preferably interposed between the friction elements and the rod. These friction elements have their upper and lower edges beveled, as shown at 30, and the cylindrical member 24 has at its lower end an inwardly extending flange 31, the upper surface of which is inclined inwar ly and downwardly to correspond to the inclination of the beveled lower edges of the friction element. A hollow nut 32 is screw threaded into the upper end of the cylindrical member 24, surrounding the rod 18, and has its lower edge inclined or beveled, as shown at 33, to engage the beveled upper edges of the friction el ments. It will be apparent therefore that the tightening down of the nut 32 will cause the triotion elements to be forced inwardly into firm engagement with the actuating rod 18, the amount of the frictional resistance offered to the move ment of the rod being regulated by the adjustment of the nut 32.

A separate punch supporting plate 10 is usually provided for each punch 9 and when punches are changed the supporting plate is removed with the punch. Likewise a separate stripping device is usually provided for each punch and in order that the same actuating rod 18 may be used with a plurality of different punches and their stripping devices I have shown that rod as formed in two parts, the major portion 18 of the rod being located normally in and above the ram 8 and a lower part 34 being secured to the spider l9 and located in the supporting plate 10. The parts 34 of the several stripping devices are identical in construction and of the same diameter as the upper part 18 of the actuating rod and are adapted to be rigidly secured thereto. As here shown, the abutting edges of the two parts of the rod are provided with tongue and groove, as shown at 35, to properly aline the same, and both parts of the rod are hollow. A bolt 35a extends through the upper portion 13 of the rod and has its lower portion screw threaded into the part 34 of the rod, and the head 36 of the bolt engages the upper end of the part 18 of the rod, so that by tightening down the bolt the two'parts of the rod may be rigidly connected one to the other so as to constitute in eiiect a single actuating device. 7 While I have shown and described one embodiment or my invention I wish it to be understood that I do not desire to be limited to the details th reof as various modifications may occur to a person skilled in the art.

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

1. In a punch press or the like comprising a ram an a punch carried thereby, a blank stripping plunger movably mounted in said punch and adapted to project beyond the lower face thereof, and means controlled by the movements l i-O of said ram to cause said plunger to be retracted when said ram begins its downward movement and to be projected when said ram begins its upward movement.

2. In a punch press or the like comprising a ram and a. punch carried thereby, a blank stripping. plunger movably mounted in said punch and adapted to project beyond the lower face thereof, and means. acting independently of the material on which said punch operates. to cause said plunger to be retained in its retracted position during the downward movement of said ram and to be projected during the initial upward movement of said ram.

3. In a punch press or the like comprising a punch and a die, and means for moving said punch toward and from said die, a plunger mounted in said punch and movable therewith, said punch and said plunger being capable of relative movement to cause said plunger to project beyond the operative face of said punch, and friction controlled means acting on said plunger to retard the movement of said plunger with said punch.

i. In a punch press or the like comprising a punch and a die, and means for moving said punch toward and from said die, a plunger mounted in said punch and movable therewith, said punch and said plunger being capable of relative movement to cause said plunger to project beyond the operative face of said punch to strip the blank therefrom, a device to control the position of said plunger with relation to said punch, and means acting on said device to cause said plunger to be projected during the initial movement of said punch from said die and to be retracted during the movement of said punch in the other direction and before said plunger engages the material to be punched.

5. In a punch press or the like comprising a punch and a die, and means for moving said punch toward and from said die, a plunger mounted in said punch and movable therewith, said punch and said plunger being capable of relative movement to cause said plunger to project beyond the operative face of said punch to strip the blank therefrom, a device to control the position of said plunger with relation to said punch, and means acting on said device to retard the movement of said plunger with said punch during the initial portion of the movement of said punch in either direction.

6. In a punch press or the like comprising a punch and a die, and means for moving said 'punch toward and from said die, a plunger mounted in said punch and movable therewith, said punch and said plunger being capable of relative movement to cause said plun er to project beyond the operative face of said punch to strip the blank therefrom, and means controlled by the movement of said ram to hold said plunger against movement with said punch during the initial portion of each movement of said punch and for causing said plunger to move with said punch during the remaining portion of each movement of said punch.

7. In a punch press or the like comprising a punch and a die, and means for moving said punch toward and from said die, a plunger mounted in said punch and movable therewith, said punch and said plunger being capable of relative movement to cause said plunger to project beyond the operative face of said punch, a device connected with said plunger for movement therewith, and friction means acting on said device to. retard the movement of said device during av portion of each movement of said punch.

8. In a punch press or the like comprising a reciprocatory ram and a punch carried by said ram, a plunger mounted in said punch, said plunger and said punch being capable of relative movement to cause said plunger to project beyond the operative face of said punch, a device connected with said plunger and having means for causing it to move with said ram during a portion of the movement of said ram, and a friction device mounted on a fixed part of said press and engaging the first mentioned device to retard the movement thereof with said ram.

9. In a punch press or the like comprising a reciprocatory rain and a punch carried by said ram, a plunger mounted in said punch, said plunger and said punchbeing capable of relative movement to cause said plunger to project beyond'the operative face ofsaid punch, a device connected with said plunger and having means for causing it to move with said ram duringa portion of the movement of said ram, a friction device mounted on a fixed part of said press and engaging the first mentioned device to retard the movement thereof with said ram, and means for adjusting said friction device to vary the frictional resistance offered thereby to the movement of said first mentioned device. 7

10. In a punch press or the like comprisinga die, a punch, a support for said punch, and means for moving said support toward andfrom said die, a plunger slidably mounted in said punch, said support having a recess in line with said plunger, a device having a part movably mounted in said recess and connected with said plunger, the movement of said support with relation to said device being limited by the Walls of said recess, and means for retarding the movement of said device with said support until a wall f said recess engages said part of said device.

11. In a punch press or the like comprising a die, a punch, a support for said punch and means for moving said support toward and from said die, a plunger slidably mounted in said punch, said support having a recess in line with said plunger, a device having a part movably mounted in said recess and connected with said plunger and having a second part extending upwardly beyond said support, the relative movements of said support and said device being limited by the opposed walls of said recess, and a friction device acting on said second part of the first mentioned device to resist its movement with said support.

12. In a punch press or the like comprising a die, a punch, a support for said. punch and means for moving said support toward and from said die, a plurality of plungers slidably mounted in said punch, said support having a recess in line with said plungers, an actuating rod slidably mounted in said sup-port, extending above the same and having laterally extending parts arranged for limited movement in said recess and connected with the respective plungers, and a friction device mounted on a fixed part of said press and acting on said rod to hold the same against movement with said support until said lateral parts engage a wall of said recess.

13. In a punch press or the like comprising a die, a punch, a support for said punch and means for moving said support toward and from said die, a plunger slidably mounted in said punch, an actuating device slidably mounted in said support, extending above the same, connected with said plunger and having means to limit the movement of said support with relation thereto, and a friction device carried by said press above said support and engaging said device to resist its movement with said support.

14. In a punch press or the like comprising a die, a punch, a support for said punch and means for moving said support toward and from said die, a plunger slidably mounted in said punch, an actuating device slidably mounted in said support, extending above the same, connected with said plunger and having means to limit the move ment of said support with relation thereto, a frame member carried by said press above said support, a hollow member mounted on said frame member and through which said actuating device extends, a frictional element mounted in said hollow member, and adjustable means for pressing said frictional element against said actuating device.

15. In a punch press or the like comprising a die, a punch, a support for said punch and means for moving saidsupport toward and from said die, a plunger slidably mounted in said punch, an actuating rod slidably mounted in said support, extending above the same, connected with said plunger and having means to limit the movement of said support with relation thereto, a frame member carried by said press above said support, a cylindrical member mounted on said frame member, and through which said actuating rod extends, a plurality of friction elements mounted in said cylindrical member about said rod and each having its upper and lower edges beveled, said cylindrical member having an inclined surface to engage the beveled lower edges of said friction elements, and a nut screw threaded into the upper portion of said cylindrical member and having an inclined surface to engage the upper beveled edges of said friction elements.

16. In a punch press or the like comprising a punch and a die, and means for moving said punch toward and from said die, a device mounted in said punch for movement therewith and adapted to be projected beyond the operative -face thereof to strip the blank from the punch, and means acting on said device to retain the same in its retracted position during the final portion of the movement of said punch toward said die and to hold said device against movement with said punch during the initial portion of the movement of said punch from said die and thus cause said device to hold the blank against movement with the punch.

17. In a punch press or the like comprising a punch and a die, and means for moving said punch toward and from said die,; a plunger mounted in said punch and movable therewith, said punch and said plunger being capable of relative movement to cause said plunger to project beyond the operative face of said punch, and means acting on said plunger to retard the movement thereof with said punch during the initial movement of said punch in both directions.

GEORGE E. LELAND.