US 2508758 A
Description (OCR text may contain errors)
y 1950 c. HOLLERITH 2,508,758
METHQD 0F PUNCHING OUT METAL I Filed Sept. 20, 1946 44 INVENTOR,
EH/JF1L E5HULLER/TH Patented May 23, 1950 UNITED STATES FPATENT OFFICE METHOD or our METAL 7 Charles Hollerith, Jackson, Mich. assignor to Hayes Industries, Inc,; Jackson, Mich., a cornotation of Michigan Application September 20, 1946, Serial No. 698,167
The present invention relates to improvements in metal stamping, being particularly concerned with the method whereby rounded edges are provided on both the blank and the perforated strip or sheet.
Heretofore it has been the practice in blanking and formin metal sheet and strip stock to complete the blanking, shearing, and punching operations with a single stroke of the pun-ch and from one side of the sheet or strip only. This standard method results in a rounded edge only on that side of the material on the opposite side of the material from which the punch operates.
According to the present invention, a method is provided for providin rounded edges on both sides of the blank as well as the perforated sheet or strip. This has been accomplished by employing two operations, the first operation being in the order of an embossing operation from one side of the sheet or strip with a second and final operation a complete blanking operation from the opposite side of the sheet or strip.
Thus one of the objects of the invention is to provide an improved method of obtaining round edge blanks and perforated sheet or strip.
Another object of the invention is to provide an improved method of metal sheet and strip blanking in which the blank and the perforated stock are both provided with round edges on each side.
Another object of the invention is to provide an improved method of stamping metal sheet end strip in which the perforation of the metal is partly completed in one direction with the perforating operation being completed from the opposite side.
A still further object of the invention is to provide an improved method of forming rounded edge blanks from sheet Or strip metal by employing a combination embossing and blanking operation progressively eflected on opposite sides of a sheet or strip.
These and other objects of the invention vrill more clearly appear from a consideration of the following specification and appended claims.
In the drawings,
Fig. I is a cross-sectional view through a suitable die for carrying out my improved method,
Fig. II is a perspective view of the metal strip upon which the operations of the die of Fig. I have been performed, and
Fig. III is a cross-sectional view of a blank showing the rounded edges.
In Fig. I of the drawings, one suitable die construction is illustrated capable of carrying out the principles of the present invention. As
shown, the upper and lower plates ill and 12 of a standard die cast set carries a lower die l4 and an upper punch it for performing the first operation which may be termed an embossing operation, with the upper die 18 and the lower punch 20 performing the second and final punching operation. Suitable pressure pads are indicated at 22, 24, 26 and 28.
The metal strip or sheet 30 is fed in the die shown in Fig. I from right to left. At the lefthand side of Fig. I the metal strip 30 is shown with perforations 32, having all of the edges 34 rounded, both top and bottom. The die is shown completely closed with the blank 36 completely sheared from the strip 30 by the punch 20. In the first operation, the punch 16 is shown having completed the embossment 38. This first operation rounds the edges 40 of the perforated strip as well as the lower edge 42 of the final blank.
With each stroke of the press, the embossment 38 is indexed from the first operation position into the inactive cavity 44 and upon the next index into alignment with the punch 20 where the final operation is provided upon theembossment 38. In this position, the blank 44 is completely sheared from the strip 30, with this final operation rounding the upper edges 46 of the blank and completing the rounding of the edges of the perforations 32. It will be understood that with the production die construction shown in Fig. I, that each stroke of the press after the second index will result in the formation of a blank 44 and a perforation 32 in the sheet or strip 30.
The method herein disclosed avoids for the most part any necessity for further operations to remove the sharp and torn edges conventionally resulting from punching and shearing metal. Also, it will materially reduce the formation of fissures and cracks in the edges of the blanks and perforated strips and sheets which cause failure of structure under operating loads especially in the case of fabricated parts subjected to violent vibration and fiexure. For example, it is anticipated that by employing the method herein disclosed many holes may be punched in aircraft structure which have heretofore been drilled in order to reduce structural failures.
Having thus described my invention, what I claim as new and desire to cover by Letters Patent is:
1. A method of forming blanks and perforated ing and shearing the protuberance out of the strip from the opposite side.
2. A method of forming blanks and perfora l7 tions with rounded edges from metal sheets strips and the like, comprising the step of first forming an embossment to provide a depression on one side of the strip and a protuberance on the opposite side of the strip, and as a final step the punching and shearing of the embossmentfrom the strip by punching the protuberance back through the stripand depression.
3. A method of punching sheet metal to provide blanks andperforations, comprising the step of partially punching out a blank from one side to form a depression on that side and a cor- 4 responding protuberance on the opposite side and then completing the punching out of the blank from the said opposite side.
4. A method of forming blanks and perforations in sheet metal in two operative steps, comprising the first step of partially punching a. blank from one side of the sheet to form a depression on that side and aprotuberance on the opposite side and followed by the second step of completing the separation of the blank from the i sheet by punching the protuberance back through the sheet and depression from the said opposite side of the sheet.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Name Date