US2816461A - Punch and die assembly and method of making same - Google Patents

Description

'Dec. 17, 1957 R. M. CEFINGER 2,816,461

PUNCH AND DIE ASSEMBLY AND METHOD OF MAKING SAME Filed Dec. 29, 1954 2 Sheets-Sheet 1 F a INVENTOR g RAYMOND M. OEF/NGER ATTORNEY Dec. 17, 1957 R. M. OEFINGER 2,816,461

PUNCH AND DIE ASSEMBLY AND METHOD OF MAKING SAME Filed Dec. 29; 1954 I 2 Sheets-Sheet 2 A TTORNEV INVENTOR RAYMOND M OE 'INGER United States Patent PUNCH AND DIE ASSEMBLY METHOD OF MAKING SAME Raymond M. Oefinger, Bridgeport, Con'm, assignor to Underwood Corporation, New York, N. Y., a corporation of Delaware Application December 29, 1954, Serial'No. 478,392 3 Claims. (Cl. 76 107) This invention relates to punch and die assemblies and to a method of making same. With regard to certain more specific features thereof the invention relates to an improved low cost punch and die assembly as an article of manufacture for the accurate production of a relatively small quantity of stampings and to "a simple and extremely inexpensive method of producing such an assembly.

The conventional tools used, prior to the present invention, generally consist ofa die and punch, each having the contour of the parts to'be madaset inexact registrati'on in one of the many'typ'es of die sets provided commercially for use in the well known power press. The die is usually made first from a block of'high grade steel. The contour of thepart to be made is first scribed on the block, by using measuring tools such asthe -vernier height gage, size blocks and the like. The center, or unwanted portion of the block is then roughly sawed out and the contour is then brought to its exact conformation by filing-or other suitable means. The die is then set onto the lower portion of the die-set, usually termed the bolster, by means of dowels, and means is providedf'or firmly securing the die to the bolster, such as screws or bolts. The die is then'removed from the bolster and hardened, tempered and properly ground, after which it is reassembled with the bolster.

The die-set bolster 'is usually provided withtwo or more upstanding posts on which the upper portion of the die set, usually termed the'p'unch holder, slides to maintain the punch and diein exact registration.

The punch is formed'from a 'block of high. grade steel to a conformation slightly larger than thato'fthe'contour opening in the die. It is then doweled and secured to the punch holder of the die set and pressed into the hardened and tempered die. This is known asshea'ring the punch, to give it the exact conformation of the die. Itis then removed from the punch holder-arid backed off for filing to give the desired clearance in the die. The punch is then hardened, tempered and ground,-and reassembled to the punch holder. The tools as described above provide a means for-merely blanking astaniping from a sheetor strip of material-which may, possibly be subjected to further operations to produce the finished part.

When piercings are required in thefinishedpart the punch is usually secured to apunch plate in which the piercing punches also are set in spacedrelation with tlie punch and the assembled punch plate is secured to the punch holder. Suitable holes for receiving the piercing punches are provided in the die beforeit is hardened, tempered and ground. For this type of die the part made and piercing slugs are usually dropped through'the die and into receivers provided "therefor, and suitable means for stripping the'blanked strip "of material from which the parts are madefrom'the unchesis'provided. Also, some type of stop, :ither plain-- or-'autornatic, is provided forpositioning the material 'fr-orn' which the parts are made.

2,816,461" Patented Dec. 17, 1957 "ice It can be readily understood, therefore, that previously, to make such a die, the services of a highly trained and skilled artisan were required, utilizing a considerable length of time. Also, high grade materials mustbe used in the construction of the tools. The combination of these two factors produces a tool construction at such an expense that, when amortized in the cost of the production of a moderate number of parts, increases the cost of those parts to an extent that is undesirable.

The present invention has as one of its objects the provision of a die and punch assembly that is of such construction as to enable its being builtat low cost, which will efficiently produce accurate parts'a't a minimum of expense.

Another object of the present invention lies in the provision of an improved method of constructing a die and punch assembly which enables the building thereof at'vei'y low cost.

Still another object of the present invention is to provide a combination blanking and piercing die and punch assembly that can be used alone for producing a few parts, or in a standard commercially obtainable die set for producing several hundred parts, at a low cost of the production of either groups of parts.

With these and incidental objects in view, the invention consists in certain novel features of constructions and combinations of parts, the important elements of which are herein set forth inappencled claims and a preferred embodiment hereinafter described and shown in the drawings which accompany and form part of the specification.

in the drawings:

Fig. l is a front view in vertical elevation of a completely assembled die and punch for combined blanking and piercing operations, showing the parts in the positions they occupy just before pressure is applied, and a strip of the material from which the parts are made interposed'therebetween;

Fig. 2 is a fragmentary top plan view;

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2;

Fig. 4 illustrates a typical stamping produced by means ofthe present invention;

Fig. 5 shows a plain block of steel upon which the contour of the'part shown in Fig. 4 is scribed;

Fig. 6 illustrates a punch obtained upon the cutting of the block shown in Fig. 5 to conform with the line scribed thereon;

Fig. 7 illustrates one of the steps taken in the building of the :tools; and

Fig. 8 is an exploded perspective view showing the general assembly of the tools.

Referring now in detail to the drawings, a die it) is positioned above a punch 11, the die being constructed from an inexpensive low grade steel or other inexpensive metal or material. The punch 11 is formed first from a good grade of steel, such as commonly called tool steel, to the contour of the part or stamping to be made, as for example, to that of a typical part indicated by the numeral 16, Fig. 4. This may be done in various ways, that of the present instance being the scribing of the contour of the-parton a block of steel 14 as illustrated in dotted lines in Fig. 5. The block is then shaped to the contour by'any suitable means, as for example, by means of a'band saw or shaper, to produce a solid blanking punch 11, minus all provisions for piercing which may be desired, as shown in Fig. 6. The completed blanking punch 11 is now positioned between the die 10 and a punch block 13' as issh'own in Fig. 7, and the parts are subjected to a high pressure-which is sufiicient to'impress punch 11 approximately one sixty-fourth inch deep indie 10 and block 13, making-a recess in each i-n the 3 exact shape of its contour, as indicated by the numerals 17 and 19, Figs. 7 and 8.

To hold these members in registration during operation of the tools, posts 20 and 21, Figs. 1, 2 and 3, are secured in the punch block 13, on which die It) slides vertically. To save time in the construction of the tools and obtain a maximum of accuracy, holes for receiving posts 20 and 21 are bored while the members are clamped in registration.

The diell), after having been recessed as described, may be removed from the assembly and the punch 11 clamped in the recess 17 in the punch block 13, while holes 23a for rivets 23 are bored through both members and countersunk. The members are then separated. This construction eliminates the need for drilling, reaming and fitting of dowels by expert artisans which contributes to a substantial reduction in the cost of the tools.

Referring to Fig. 4, it is shown that it is desired to pierce two holes 24 and 26 in the part to be made.

using the holes bored in punch 11 as a bushing, transfer to and bore the holes through die 10, after which the holes in die are countersunk to receive a flared head 3% of punches I27 and 29. The members are then disassembled and the holes for receiving the piercing punches are bored in the usual manner. An alternate method of providing the holes for receiving the piercing punches is to dimensionally locate the holes by means of the well known jig borer and bore said holes entirely through the complete assembly immediately after impressing punch 11 in die 10 and punch block 13 and at the same time as boring the holes for receiving posts and 21.

The punch is now hardened in the required manner. Clearance holes 33 for the piercing slugs are then bored in punch block 13 and the punch 11 is set and riveted in its impression. The punch 11 and punch block 13 are then secured to a punch plate 34 in any suitable manner, said punch plate being provided with clearance holes 36.

Attention is now drawn to the construction of the die. Referring to Figs. 1, 3 and 8, it is seen that the present tools are of the inverted type, i. e., the part to be made is blanked upwardly and into the die by the punch. Therefore, the impression of punch 11 in die It) is routed, as indicated by the numeral 37, to a depth which leaves a substantial clearance 38 between the bottom of the recess and the part to be made when said part is pressed into the recess, as shown in Fig. 3. The die 10 is of sufficient thickness to leave a web 39, Fig. 3, which strengthens the die and prevents deformation thereof during any hardening process. After the routing operation the die is placed in registration with the punch and the punch is shear-d into the die to give the latter the exact contour of the punch. Suitable securing holes are provided in the die for securing same to a die plate ll Figs. 1 and 3. Since the die is constructed from inexpensive, low grade steel, it is hardened by the process of case hardening, or an equivalent thereto, at least in the region of recessed contour, to a substantial depth from its surfaces, and is not ground thereafter. The piercing punches 2i and 39 are then assembled in the die and the assembly is secured to the die plate 46 which, as seen in Fig. 3, backs up the piercing members.

The part to be made is usually blanked from a strip of material indicated by the numeral 42, Fig. 2. It is desirable to cut the scrap free of the strip at each blanking and piercing operation of the machine. For simplicity and economy of construction posts 20 and 21 are utilized as edge guides for the strip of material as it is positioned over punch 11. The posts 20 and 21 are therefore positioned so that punch 11 breaks through the edge of the strip, leaving an incomplete radius on the part made, as shown at 43, Fig. 2. To complete the severance of thescrap the strip of material is slightly wider than the overall length of the punch and extends onto a strip cutting blade 45 secured in punch block 13.

For practical purposes, the present invention as described above is built for the purpose of manufacturing three to four hundred parts. It is, therefore, usually set in a commercially obtainable die set, as shown in Fig. 1, comprising a bolster 46 having two or more upstanding posts 48 fixed therein, and on which said posts a punch holder 49 slides to hold registration of the punch 11 and die 10. The die plate 40 and punch plate 34 are secured to the die set punch holder 49 and bolster 46, respectively, by any suitable means. The punch holder 49 includes a shank 51 that is secured in the ram of a conventional power press, said ram being indicated by the numeral 52.

During the downward stroke of the said power press ram 52 to produce a part 16, the said part is forced by punch 11 into the sheared recess of die 10, and the strip cutting blade 45 cuts the scrap free as it contacts the lower surface or die 10. Simultaneously the piercing punches 27 and 29 pierce the required holes in said part, the slugs deriving therefrom dropping through the clearance holes 33 and 36 provided therefor. Attention is drawn here that when the present invention is used in connection with a commercially obtainable die set suitable clearance means are provided therefor in said die set. The punch 11 does not enter the recess of die 10, but merely severs the blank from the strip, thereby retaining the sharpness and evenness of the cutting edge of die 10. To prevent the entering of the punch 11 into die 10, blocks 54 and 55 are secured to the punch block 13 and are of exactly the same height above the top surface of punch block 13 as that of punch 11.

With the upward or return stroke of the press ram 52 and die 10, the part 16 is ejected from the recess in die 10 and stripped from the piercing punches 27 and 29. To do this a conventional ejecting means is used which will now be described. The punch holder 49 is provided with a cavity 57 in which sets loosely a knock-out disc 58 having a shank 60 which slides in shank 51 of punch holder 49 and extends upwardly therein to engage a knock-out bar 61. Bar 61 slides freely vertically in the press ram 52. Mounted for free vertical slidable movement in the punch holder 49 are knock-out pins 63 having heads 64 for preventing their falling out when the press ram is raised, said pins underlying the knock-out disc 58. The knock-out pins 63 extend beyond the cutting edge of die 10 at least the full thickness of the part to be made, so that during the blanking and piercing operations they are raised by the part as it is being blanked, and in turn raise the knock-out disc 58 and knock-out bar 61. Now, as the press ram ascends, the knock-out bar 61 engages stop screws 66 to force the knock-out disc 58 and knock-out pins 63 to move downwardly and remove the blanked and pierced part from the tool.

Under certain conditions, it may be required to make a substantially few parts of special shape which would be too expensive to make by hand with the necessary accuracy. In such a case, the die 10 and punch 11 assembled on their respective plates 40 and 34, assembled as shown in Fig. 3 and including guide posts 20 and 21 may, with the knock-out pins 63 removed, be placed as a unit under the ram of a press, or other pressure means, and the parts made therewith. The knock-0ut pins 63 may then be reinserted, and the part blanked and pierced may be easily removed from the die and piercing punches by means of the same press with the die portion of the assembly resting on suitable blocks which clear the routed recess 37 in die 10.

The above described punch and die assembly and method of producing its essential element is considerably less expensive than the conventional type, and will produce a moderate quantity of special parts, identical in shape and to the desired tolerances, at a substantial saving in cost.

Having thus described a preferred embodiment of the present invention, what is claimed is:

1. The method of making a punch and die assembly which consists of preparing essential elements by forming a metal punch to the contour of a desired stamping, placing it between a punch block and a die of material susceptible to recessing by pressure of the punch, applying pressure to the assembly to impress the contour of the punch in both of the other pieces, routing the die to a depth to receive the stamping, hardening the punch and hardening the die at the contour region, and securing the punch located in the recess in the punch block.

2. The method of making a punch and die assembly which consists of preparing essential elements by forming a metal punch to the contour of a desired stamping, placing it between a punch block and a die of material susceptible to recessing by pressure of the punch, applying pressure to the assembly to impress the contour of the punch in both of the other pieces, boring the assembly to provide aligned holes in the die and punch block for the reception of guide posts whereby relative movement may be obtained, routing the die to a depth to receive the stamping, hardening the punch and hardening the die at the contour region, and securing the punch located in the recess in the punch block.

3. The method of making a punch and die assembly which consists of preparing essential elements by forming a metal punch to the contour of a desired stamping, placing it between a punch block and a die, of material susceptible to recessing by pressure of the punch, applying pressure to the assembly to impress the contour of the punch in both of the other pieces, boring the assembly to provide aligned holes in the die and punch block for the reception of guide posts whereby relative movement may be obtained, boring the assembly to provide aligned holes in the die element and punch, inserting hardened piercing members in the holes opposite the punch element, routing the die to a depth to receive the stamping, hardening the punch and hardening the die at the contour region, and securing the punch located in the impression in the punch block.

References Cited in the file of this patent UNITED STATES PATENTS 2,222,860 Sedgwich et al Nov. 26, 1940 FOREIGN PATENTS 577,371 Great Britain May 15, 19 46 OTHER REFERENCES The Making, Shapings and Treating of Steel, by J. M. Camp and C. B. Francis, fourth edition, published by Carnegie Steel Co., Pittsburgh, Pa., June 1, 1925, pages 698 to 704, both inclusive.

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