US3389619A - Adjustable jig or die bushing - Google Patents

Description

June 25, 1968 G. P. DEL FARO ADJUSTABLE JIG OR DIE BUSHING Filed April 25, 1966 0. mm; m zmww N. w 2 2 2 United States Patent 3,389,619 ADJUSTABLE JIG OR DIE BUSHING Gordon P. Del Faro, 23529 Dolorosa, Woodland Hills, Calif. 91364 Filed Apr. 25, 1966, Ser. No. 545,139 1 Claim. (Cl. 76-107) ABSTRACT OF THE DISCLOSURE The present invention relates to improvements in stamping and other forms of dies and, more particularly,

to an improved method of locating and relocating the bushing within the die block.

In the design and construction of a die block for a stamping die, it is presently common practice to utilize cylindrical bushings and to mount the bushings in holes drilled into the material forming the die block. The die block is secured to a shoe and the sheet metal to be stamped is passed over the die block and under a punch holder. The punch holder carries a number of punches which pierce the sheet metal and pass into the holes in the bushings upon a closure of the punch holder against the die block.

Extreme care is taken in the layout and design of the die block to insure that the holes receiving the bushings are in the proper location for the particular parts to be stamped from the sheet metal. Despite this, small changes in the thickness and tensile characteristics of different quantities of the sheet metal result in the stamped holes being slightly displaced from their designed centers or elongated in undesired manners. When precision and high tolerance stamping is required, this results in the rejection and discarding of large quantities of parts, with the corresponding waste of material, time and monies to the manufacturer.

To compensate for changes in the thickness and tensile characteristics of the different batches of sheet metal, it is presently common practice to periodically check the stamped parts for proper hole alignments and if any of the holes are oil-center, to relocate the bushings within the die block.

The relocation of the bushings is presently accomplished by one of two methods. The first includes jig grinding and enlarging the holes for the offcenter bushings, especially forming bushings of increased outside diameter, and inserting the new bushings into the enlarged holes along the correct center lines. The second method includes annealing the die block and reboring the hole for the off-center bushing along the corrected center line.

Die blocks are usually formed of extremely hard and expensive metals. Such material is very difficult and costly to machine. Therefore, both of the foregoing methods of relocating bushings in a die block are extremely costly and time consuming.

Similar problems are presented by the relocating of cylindrical bushings in molding and other types of dies, and it is accordingly a general object of the present invention to provide a simple and economical solution to these problems.

A further object of the present invention is to provide 3,389,619 Patented June 25, 1968 an improved method of shifting the position of a bushing in a die block preferably utilizing the improved bushing construction of the present invention.

The foregoing as well as other objects and advantages of the present invention may be more clearly understood by reference to the following detailed description when taken with the drawing which, by Way of example only, illustrates one form of bushing construction and a die block assembly employing two such bushing constructions.

In the drawing:

FIGURE 1 is a perspective view of a preferred form of the bushing construction;

FIGURE 2 is a plan view of a die block incorporating bushings of the type illustrated in FIGURE 1; and

FIGURE 3 is a sectional view taken along the line 33 in FIGURE 2 illustrating a preferred manner in which the bushings are secured within the die block to a shoe supporting the die block.

In the drawing, the bushing construction is represented generally by the numeral 10. Rather than being cylindrical as is common for conventional bushings, the bushing construction 10 is formed from a block of metal and includes a plurality of flat, substantially vertical outer sidewalls 12 and a top hole 14. Preferably, the bushing 10 has a rectangular or square cross section and the hole 14 is a substantially cylindrical, slightly frusto-conical, vertically extending bore. The hole 14, however, may take various other forms depending upon the shape of the opening to be produced with the bushing construction 10 and the shape of the tool to be received thereby.

Two of the bushing constructions 10 are included in a die block 16 illustrated in FIGURES 2 and 3. In addition to the bushings 10, the die block 16 includes three fiat, substantially rectangular bodies 18, 20 and 22 arranged side-by-side on top of a flat shoe 24 supporting the die block. The bushings 10 are stationed in slots 26 and 28 in the inner sides of the bodies 18 and 22 and bear tightly against opposite sides of the body 20. Preferably, the bushings are also attached to the shoe 24 by screws 30 extending vertically through the shoe and. into threaded holes 32 in the bottom surface of the bushings.

The body 20 includes five parallel channels 33 for receiving louver punches held by a punch holder (not shown) above the die block 16. The punch holder is adapted to move against the die block 16 to cause the punches held thereby to pierce and form a length of sheet metal 34 introduced over the top of the die block. In addi tion to forming five parallel louvers in the sheet metal 34, the die block 16 and punches combine to punch openings through the sheet metal into the holes 14 in the bushings 10 and to crimp the marginal edges of the sheet metal by bending the edges into a rectangular, outwardly and downwardly inclined recess 36 formed in the three flat bodies 18, 20 and 22.

To form the die block 16 and to incorporate the bushings 10 therein, the slots 26 and 28 are first formed in the inner edges of the bodies 18 and 22. Rather than being cylindrical, as is the common practice in conventional die blocks, the slots 26 and 28 include a plurality of flat, substantially vertical inner sidewalls 38 corresponding to the flat outer sidewalls of the bushings 10. In the illustrated case, the slots 26 and 28 are rectangular to tightly engage the outside walls 12 of the bushings 10.

Next, the bodies 18, 20 and 22 are stationed side-byside and secured to the top of the shoe 24' by means not specifically shown. Then the bushings are pressure-fit into the openings formed by the slots 26 and 28 to complete the die block assembly.

In the manufacture of the die block 16, the initial location of the slots 26 and 28 is not critical since the nature of the bushings and the slots accommodate a relatively easy shifting of the position of the bushings within the die block. In particular, in the construction of the die block 16, the slots 26 and 28 may be formed at their approximate final locations and the bushings 10 inserted in the openings formed thereby. Then a test stamping may be made with the die block 16. By comparing the locations of the stamped holes formed with the bushings 10 with the designed locations, the exact positions for the centers of the holes 14 may be determined for the particular type and character of sheet metal being stamped. Once having determined the exact location for the bushings 10, it is a simple matter to mill or grind one or more of the fiat inner sidewalls 38 of the slots 26 and 28 to provide room for the bushings 10 to be relocated in the die block by moving against the milled side or sides of the slots.

The same operation is followed when it is desired to relocate the center of the holes 14 in the bushings 10 due to changes in the thickness or tensile characteristics of the sheet metal being stamped, to insure that the holes formed with the bushings 15) are always on the designed center lines.

In both cases, shims 40 are inserted into the spaces formed in the slots 26 and 28 by the milling or grinding of one or more of the vertical sidewalls of the slots. The shims 40 insure a continuous tight fit for the bushings 10 within the slots.

In FIGURES 2 and 3, the bushing 10 in the slot 28 was elf-center. T 0 correct this, two inner sidewalls 38 of the slots 28 were milled and shims 40 introduced in the spaces formed thereby to maintain the bushing 10 tightly against one of the milled walls of the slot and the outer edge of the body and accurately on the designed center.

While the foregoing description has been directed primarily to a stamping die, it is appreciated that the present invention solves similar problems for molding as well as other types of dies. Also, it is appreciated that changes and modifications may be made in the illustrated form of the bushing and die block without departing from the spirit of the invention. It is therefore intended that the present invention be limited in scope only by the terms of the following claim.

I claim: 1. A method of mounting and relocating a bushing within a die block comprising:

forming an opening in a bushing support plate, said openings having a plurality of flat, substantially vertical, inner sidewalls; inserting a bushing block in said opening, said bushing block having flat, substantially vertical outer sidewalls conforming to said flat, substantially vertical inner sidewalls of said opening; removing said bushing from said opening and grinding one of said inner sidewalls of said opening; reinserting said bushing in said opening with a flat outer sidewall engaging the ground inner sidewall of said opening; and inserting a shim into said opening to fill said opening and tightly hold said bushing within said opening.

References Cited UNITED STATES PATENTS 907,667 12/1908 Wood 83-690 X 956,434 4/ 1910 Schwartz 83690 2,801,696 8/1957 Banko 83-690 X 3,248,988 5/1966 Janczy 83700 X WILLIAM S. LAWSON, Primary Examiner.

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