US2939347A - Method of making steel rule blanking dies and punches - Google Patents

Description

R. J. TOBEY June 7, 1960 METHOD OF MAKING STEEL RULE BLANKING DIES AND PUNCHES Filed Feb. 17, 1958 ill FIG.

illll INVENTOR. RUSSELL J. TOBEY ATTORNEY marked by the die.

atent ice 2,939,347 Patented June 7, 1960 States This invention relates toblanking dies and punches and more specifically to a method of making steel rule blankingdies and punches for use therewith.

, years, effortshave been 'made to reduce the ex.-

' pense of making blanking'die's and punches. One of the results 'ofitheseeffortshas been the development of steel B A KI TG dies, which have substantially reduced the seamen-Se p'er'unitfor comparatively short production runs. Prior to the present invention, punches for use with such dies have been manually filed after being Successful forming of the punch has been dependent on human skills. To make a punch which will hold up even during comparatively short production runs of 50,000 to 100,000 has required the use of expensive tool steel. Because of high cost of tool steel, large-area punches have generally been formed in sections along the periphery of the pattern and the sections fitted together. It has also been necessary to make separate punches for different thicknesses of metal to be blanked.

It is a primary purpose of the present invention to provide a method of making steel rule blanking dies and punches which is inexpensive and not dependent on skilled diemakers in forming the punches. It is a further object of the present invention to provide a method of making such' dies and punches which will hold up during intermediate length production runs and which will permit the use of metal less extensive than tool steel in the punch. An additional purposeis to provide a method of making such dies and punches wherein the forming of the punch is not dependent on the thickness of the metal to be blanked. Other objects will be apparent from this specification.

Referring to the drawings:

Figure l is an exploded perspective illustrating the application of my invention to a die and punch set for blanking oval parts- The first step in my method is the forming of a template '10 to the shape of the part to be blanked. For a simple die and punch set, as contrasted to a compound die and punch set, this template will also be a template of the punch to be made. The punch template 10 may be formed of a wide variety of metals having various thicknesses, but is preferably formed of mild steel approximately thick because of the ease with which such sheet metal may be cut. The forming of the template may be accomplished by known methods, as by sawing to the desired shape.

A steel rule dies 17 is then shaped closely around punch template 10. This may be accomplished by placing punch template 10 on a die board 11, scribing a mark 12 along its edge, cutting a plurality of. slots 13 in die board 11 along the scribed mark 12, replacing template 10 on die board 11, and fitting a steel rule cutting blade 14 closely around template '10 and driving it into slots 13. The die board 11 may be made of maple approximately thick, or of any other material of suitable thickness now in use for such die boards.

I prefer to cut several slots through the die board, leaving the portion of the die board within the scribed mark 12 joined'to the balance of the die board by several bridging portions. This requiresthe cutting of notches 16 in thesteel' rule cutting 'blade'14 to fit the bridging portions between the slots 13. To obtain a tight driving fit,

it is preferable that s1ots'13 be. narrower than steel rule14. V

While any suitable steel rule. cutting blade may be used without departing fromjmy invention, I find that for most applications an ,8'or' 10 pointjrule, 1" or 1%" wide, is'desirable. It is usually advisable to shape steel rule cutting blade14 roughly to template 10 and temper it prior, to fitting it closely around template 10 and inserting it into slots 13 of. die b'oard'll. The steel rule 14 is driven into slots 13 soythat its cutting edge 15 projects from die board 11.. The cutting edge 15 of the steel rule, 14 j preferably tapers inward toward the template 10 and ordinarily is somewhat flatted, depend- 7 ing onthecornposition and thickness of the metalto be blanked. i i

*The'die 17 and punch template 10 are then removably secured in alignment with each other to opposing holders 18 and 19 of a die set, also called die and punch shoes; and a piece of metal 30 larger than template 10 is removably secured to the same die set member as template 10 so as to cover the outer surface of template 10 completely. Die set holders are customarily provided with means for aligned attachment to a punch press, not shown, and one of such holders is provided with aligning pins 20 and the other with corresponding bushings 21. The template 16 and die 17 are secured respectively to back-up plates 22 and 23 with screws 24 and 27; then the back-up plates 22 and 23 are secured to such holders 18 and 19 with bolts 25 and 28 and nuts 26 and 29.

The piece of metal 30 will be blanked to form a punch, as will be hereinafter more fully explained. It may be of various compositions and thicknesses, but -I have found that for most applications, an unannealed steel alloy, such as chrome molybdenum, of approximately /8" thickness, is suitable. The piece of sheet metal 30 has holes bored into or through it in alignment with screws 24, which project through template 10 and secure sheet metal 30 to back-up plate 22 so as to cover template 10.

After the die 17, template 10 and sheet metal 30 have been thus secured to the die set members 18 and 19, I strike sheet metal 30 with "the steel rule cutting blade 14, with sufficient force to blank sheet metal 30 between such steel rule cutting blade and template '10. I thus form a punch, not shown, having outer edges substantially coterminous with the inner edges of the cutting blade 14. The striking may be most readily accomplished by attaching holders 18 and 19 to a punch press in the usual manner and activating the punch press with adequate pressure. I find that the pressure required is slightly greater than would be required to blank sheet metal 30 with a standard steel rule blanking die and punch set.

After the punch has been blanked out of sheet metal 30, the punch and the template 10 are removed from back-up plate 22, template 10 is discarded or stored, and the punch resecured to back-up plate 22. The steel rule blanking die and punch set is then ready for use.

It will be recognized that the suitable ranges of the composition and thickness of sheet metal 30 and template 10, the thickness and width of steel rule cutting blade 14, and the dgeree of flatting of cutting edge 15 are determined by the strength and thickness of the material to be blanked. Generally as the strength and thickness of the metal to be blanked increases, the thickness and strength of the punch required increases, the thickness and degree of fiatting of the steel rule increases, and the a aryi h stee rule be w 7 h de ee flat n f t e t 'ec g appli t n f my i e sim e fi mpl i 34 R eh i "w ll o o f i d skjlll l ili fl 3X may. c d y 'adla l ei IQ mman a required thickness of the punch templateincreasess How ever," where the punch'template is made of A 'f rnild steel and the"pun ch of Ms chrome molybdenum steel,

most metals A" thick or. less can be accommodated by '7 1 have; nmsea "andae mfxe sets, without departing f rom fiiyiinv entidn. 7 H v g h s escr e my ent n, 1 claim; a

' Jand to b nati n b a ingmt plqrq t ri tii ipuu i" 1;; A method for ma ing a steel rule: blanking ie and punch set haying.substantiallg tcoterrn nous inner. die.1 5 edges and outerfpunch edges isaidgmethodcomprising thel steps of forming a punch template out of sheet metal,

n i i ste fi utt n ij'rblad ii to i -w d,

1 6 3 Qu' d' ai 9 mb emp e, i fi o' b ly an alignecll'y" securing 'saidj steel rule a cutting blade and said punch template to thejlopposed members of a die. set rem sf min rger l' etofi'sheet metal o we of; said. d e. t m nlier hi l s d p ch temp ate; nd

Bl k a Punc q t o aid a np b i i e metal with said steel rule cutting blade and punch template. a

2-. A m th q m ing.- uwq r le bl nk ng d e n 8 and Q nta cl ayy g 2 703,9 1 f 25 21731. 3 Bite j 2 821,871

scribing amark along the edge of said punch template on a die board,rcutting a*p1ura1ity of slots along said mark, fitting a steel rule cutting blade closely around said punch template into said slots, securing over said punch template 'to, a die set menalgegia: larger piece 'of thicker shee metalsmqunt ilg saidsteelmle u tiue ladetow he opl' dsiligfdieflsetkmerpbertalignedlygi i'espect'to said punch template, and'striking said-thicker pieceof sheet metalz'iyith Saidsteel rule cutting :Vblagle til-blank out a V punch." a

3. The methoddefined 111 alas; 1,?tgether with the further steps of removing the punch tengplate from the die set member to which "it was 'so secureiand'then securing the blanked-out punch directly thereto. J

R l exeucesCitqd in diefile g higr 1 A ES PATENTS 21 54.221 L'Ianj. 14;1950 anew .Ded- 2A 19.52

Mar. 1, 1955 May 3-19. 7 F b 7 3

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