US3368383A

US3368383A - Adjustable stock lifter

Info

Publication number: US3368383A
Application number: US490611A
Authority: US
Inventors: Leonard E Marszal
Original assignee: Leonard E. Marszal
Current assignee: LEONARD E MARSZAL
Priority date: 1965-09-27
Filing date: 1965-09-27
Publication date: 1968-02-13
Anticipated expiration: 1985-02-13

Description

Feb. 13, 1968 E. MARSZAL ADJUSTABLE STOCK LIFTER 2 Sheets-Sheet 1 Filed Sept. 27, 1965 INVENTOR.

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WITNESS nv WWW/u W $11M 1 7 (a Leonard E. Murszol United States Patent "Ce 3,368,383 ADJUSTABLE STOCK LIFTER Leonard E. Marszal, 14200 Ironwood Drive NW., Grand Rapids, Mich. 49504 Filed Sept. 27, 1965, Ser. No. 490,611 Claims. (Cl. 72-361) This invention relates to the construction of a component of the so-called progressive dies used for mass production of pieces formed and cut from strip sheet metal. This type of die is used when a sequence of die operations is required to complete the piece, and when the production run is large enough to justify the cost of the multiple-stage die unit. The die itself is essentially a series of dies in accurately-spaced sequence, and the strip of sheet metal is moved through the die in increments so that the piece is indexed from one stage to the other as each operation is performed. A cup-shaped article, for example, might go through a series of operations such as the following:

(a) Blanking out portions of the strip to isolate the material to be used to form the finished part, leaving portions attached to the strip.

(b) A succession of drawing operations stretching the material from planar to cup-shaped configuration.

(c) Final trim, and severing of the part from the strip.

As the strip is moved through the die, it is necessary to provide a guide to position it when the die is open. The strip must be supported far enough above the lower die structure to eliminate interference as the drawn portions of the strip are moved ahead. The device used for guiding and lifting the stock to this position is known as a stock lifter, and is widely used in die construction. A particular die will frequently use a pair of these lifters between each station, and it is obvious from this that the number of these devices used in die making is tremendous. The present invention is an improvement in these devices, particularly with regard to the lateral positioning of the stock strip.

A troublesome problem in die making has been the tendency of the stock strip to narrow during the drawing operations as the metal is stretched and pulled out of the plane of the strip. The position of the stock lifters must be correspondingly altered if the strip is to be guided accurately. A skilled die maker will normally try out a particular draw to determine the amount of reduction of stock width, and he will then locate his lifters accordingly in the die blocks. The lifters themselves are usually cylindrical in outer configuration, and are received in suitable holes bored in the proper locations. Estimating the amount of deviation from a straight line which will be required in a row of stock lifters to accommodate reduction in stock width is essentially a trial-and-error procedure, and requires the ultimate in skill and experience on the part of the die maker and die designer. Even then, slight variations in hardness or thickness of material (not to mention variation in original Width) will inject variables that are very difficult to allow for in such a piece of guesswork. Rather than face the problem of having to re-locate the stock lifters, there will be a tendency on the part of the die maker to allow a little more freedom of movement of the stock strip than is desirable. The present invention eliminates the need for this allowance of excess freedom, and also eliminates the need for a carefully-controlled trial draw in order to determine the amount of stock width reduction. With the present invention, a skilled die maker will be able to determine from his past experience approximately the amount of reduction in strip width, and the lateral adjustability provided by the invention will enable the die maker to locate the strip accurately and maintain the adjusted position. The amount of work that this will save the die maker and die designer is 3,368,383 Patented Feb. 13, 1968 obvious, and it is also obvious that a completed die can be modified to accept a limited variation in stock width by a relatively minor adjustment. This lateral adjustability is provided without interfering with the projected cylindrical surface defining the periphery of the stock lifter, with the result that the lifter is able to reciprocate during the die movement without requiring the machining of clearance areas beyond that which is required for conventional stock lifters.

The several features of the invention will be analyzed in detail by a discussion of the particular embodiments illustrated in the accompanying drawings. In the drawings:

FIGURE 1 is a section on a horizontal plane taken between the upper and lower die members, as indicated at the plane shown in FIGURE 2.

FIGURE 2 is a sectional elevation on the plane 2-2 of FIGURE 1, on an enlarged scale.

FIGURE 3 is a view on an enlarged scale of the stock lifter shown at the lower right portion of FIGURE 1.

FIGURE 4 is a view on an enlarged scale showing the stock lifter at the lower left portion of FIGURE 1.

FIGURE 5 is a sectional elevation corresponding to FIGURE 2, with the die in the closed position.

FIGURE 6 is a perspective view showing the upper portion of the body of the stock lifter.

FIGURE 7 is a perspective view showing an inverted head of the stock lifter.

FIGURE 8 s a view of the body of a modified form of the invention.

FIGURE 9 is a sectional elevation showing the head construction used in conjunction with the FIGURE 8 modification.

FIGURE 10 is a perspective view of the upper portion of the body of a further modification of the invention.

FIGURE 11 is a sectional elevation showing the head construction used in conjunction with the FIGURE 10 modification.

FIGURE 12 is an exploded view showing the components of the form of stock lifter incorporated in FIG- URES 1 through 7.

Referring to FIGURES 1 through 7, and 12, the illustrated die construction includes the shoe 20 provided with a group of guide pins 21 engageable with the bearings 22 of the upper member 23 of the die set. A die block assembly is shown at 24, which is secured to the die shoe by a series of screws 25. It is conventional practice to use locating dowels in addition to these screws, but these are not shown on the drawings. The die block assembly 24 will normally be made up from a group of segments fastened individually to the shoe 20. Since this portion of the construction of the die forms no part of the present invention, these details are omitted here. The construction normally associated with the upper member 23 of the die set will include a group of punches as shown at 26, and also a stripper plate 26a having openings closely surrounding the punch 26. This plate serves to hold the marginal areas of the strip, and pulls the formed part 27 off the punch as the die moves to the open position shown in FIGURE 2. The stripper plate 26a will normally be provided with guide pins in the form of the bolts 28. These bolts have threaded engagement with the plate, and are mounted for reciprocating movement in the upper member 23 of the die set. Springs 29 surrounding the bolts 28 will bias the plate 26a to the position shown in FIGURE 2. This type of die construction is conventional.

As the die moves to the open position shown in FIG- URE 2, the strip 30 providing the material for the parts 27 is moved in the direction of the arrow appearing in FIGURE 1. As each piece 27 encounters the operating stations of the die, it is usual practice to first punch a locating hole as shown at 31. This will be used at subsequent stations to position the strip for the succeeding die operations more accurately than is possible with the stock lifters shown at 32. The latter function as guides to position the strip accurately enough so that the fianl positioning at the locating holes 31 can be accomplished. During the formation of the piece 27, the areas 33 are blanked out to isolate a portion of the strip from which the parts 27 are to be made. This isolation permits the metal to draw Without substantially effecting the length of the strip. The parts 27 are then drawn in successive stages to form a complete piece, and are fianlly trimmed and severed from the strip 30. During the shifting of the strip 30 for these successive operations, the stock lifters 32 will participate in a vertically-reciprocating motion in response to the movement of the upper section of the die. The open position of the die is shown on FIGURE 2, and the closed position in FIGURE 5.

During the successive drawing operations, the width of the strip 30 will decrease from right to left. The width of the strip between the lifters 34- and 35 is substantially less than between the

lifters

36 and 37. The amount of deviation from a straight line which the die maker will provide for the row of stock lifters along the edge of the strip can be determined approximately from his past experience, and the adjustability provided by the present invention will make it possible for the die maker to make final adjustments'to the lifters so that the stock strip 30 can be guided accurately as it moves through the die. This adjustability is provided by a rotatable mounting of the head 38 with respect to the body 39 of the lifter. A slot 40 in the side of the head receives the edge of the stock strip 30, and the base of the slot 40 is formed by a preferably cylindrical surface 40a which is eccentric to the axis of the mounting of the head 38 on the body 39. It is preferable that the cylindrical surface defining the periphery of the head 38 be defined by the same geometrical cylinder as that of the body portion 39, with the result that the head would be receivable in the bore in the die blocks 24 in the down position of the die shown in FIGURE 5. However, loosening of the screw 41 will permit the head 38 to be rotated with respect to the body 39, with the result that the eccentric surface 40a will bear against the stock strip 30 at variable positions from the axis of the body portion 19 of the lifter. This rotary adjustment can be continued until the correct bearing position has been obtained. The adjustment can then be secured by tightening the screw 41, which will engage the radial serrations 42 on the boss 43 with the corresponding serrations 44 in the inner extremity of the recess 45 of the head 38. This configuration is best shown in FIGURES 6, 7, and 12. The radial serrations are most conveniently formed by a process commonly referred to as coining, which is essentially a localized forging operation.

The rotary position of the body 39 with respect to the remainder of the die structure is maintained through the engagement of the washer 46 with the recess 47 in the side of the body 39. The washers 46 are mounted in the die block assembly 24 in suitable counterbored areas as shown at 48, and are held in position with the screws 49. The engagement of the washers 46 with the shoulder 50 serves to retain the body 39 in engagement with the die structure. The stock lifter then is free to participate in the reciprocating vertical movement induced by the action of the upper die unit and the springs 51 which are installed in the lower die structure. These compression springs apply continuous biasing action tending to move the lifters to the position shown in'FIGURE 2.

FIGURE 8 shows a modified form of the invention with regard to the arrangement for locking the rotative position of the head with respect to the body. In this modification, the body 52 is provided with a projecting 4 boss 53 having a polygonal periphery formed by a series of flats as shown at 54. These flats may be formed either by a milling operation, or may be broached in a single pass if a clearance groove is provided at the base of the boss 53. The head 55 used with this modification of the invention may be provided with a set screw 56 which is engageable with one of the flats 54 to maintain the adjusted position of the head on the body. A hold-down screw 57 is also necessary, and this screw should be loosened prior to adjusting the position of the head 55. As an alternative to the set screw 56, a forging operation can be utilized which will produce a polygonal configuration in the head recess similar to that of the periphery of the boss 53, if desired.

The modification shown in FIGURES 10 and 11 provides another arrangement for locking the rotative position of the head with respect to the body of the lifter. The body 58 is provided with a group of depressions 59 in the shoulder 60, and the head 61 has a recess machined in the under surface 62 of a sufficient depth so that the ball 63 may be inserted with a portion projecting for engagement with the recesses 59. Loosening of the holddown screw 64 will permit the head 61 to be rotated to the selected adjustment. The recess 65 engages the boss 66 to position the head coaxially with the body 58.

The particular embodiments of the present invention which have been illustrated and discussed herein are for illustrative purposes only and are not to be considered as a limitation upon the scope of the appended claims. In these claims, it is my intent to claim the entire invention disclosed herein, except as I am limited by the prior art.

I claim:

1. A stock lifter for a die adapted to operate on strip material, said lifter comprising:

a body normally slideably received in a die block for reciprocating movement in response to relative movement of components of said die; and

a head having a transverse slot, said head being adjustably mounted on said body, to a plurality of angular positions with respect thereto about an axis substantially parallel to the axis of said body, the base of said slot being defined by a surface having portions thereof eccentric to the axis of the mounting of said head on said body; and

locking means releaseably securing the relative position of said head on said body.

2. A lifter as defined in claim 1, wherein said body and head have cylindrical peripheral surfaces coaxial with the axis of rotatable mounting of said head on said body.

3. A lifter as defined in claim 1, wherein the base of said slot is defined by a cylindrical surface eccentric to the axis of the mounting of said head on said body.

4. A lifter as defined in claim 1, wherein said body and head have axially interengaged bearing and journal portions, one of said portions being on said body and the other on said head, and said journal portion having end serrations engageable with the axially-opposite area associated with said bearing portion to lock the adjustment of said head on said body, said locking means including a screw traversing said head and said journal portion to hold said serrations in engagement.

5. A lifter as defined in claim 1, wherein said head and body have axially interengageable means at least at two spaced positions to determine the lateral and angular position of said head on said body.

References Cited UNITED STATES PATENTS RICHARD J. HERBST, Primary Examiner.

Claims

1. A STOCK LIFTER FOR A DIE ADAPTED TO OPERATE ON STRIP MATERIAL, SAID LIFTER COMPRISING: A BODY NORMALLY SLIDEABLY RECEIVED IN A DIE BLOCK FOR RECIPROCATING MOVEMENT IN RESPONSE TO RELATIVE MOVEMENT OF COMPONENTS OF SAID DIE; AND A HEAD HAVING A TRANSVERSE SLOT, SAID HEAD BEING ADJUSTABLY MOUNTED ON SAID BODY, TO A PLURALITY OF ANGULAR POSITIONS WITH RESPECT THERETO ABOUT AN AXIS SUBSTANTIALLY PARALLEL TO THE AXIS OF SAID BODY, THE BASE OF SAID SLOT BEING DEFINED BY A SURFACE HAVING PORTIONS THEREOF ECCENTRIC TO THE AXIS OF THE MOUNTING OF SAID HEAD ON SAID BODY; AND LOCKING MEANS RELEASEABLY SECURING THE RELATIVE POSITION OF SAID HEAD ON SAID BODY.