US3046815A

US3046815A - Blanking die and method of making the same

Info

Publication number: US3046815A
Application number: US670910A
Authority: US
Inventors: Frank R Moe
Original assignee: AO Smith Corp
Current assignee: AO Smith Corp
Priority date: 1957-07-10
Filing date: 1957-07-10
Publication date: 1962-07-31
Anticipated expiration: 1979-07-31

Description

July 31, 1962 F. R. MOE

BLANKING DIE AND METHOD OF MAKING THE SAME Filed July 10, 1957 2 Sheets-Sheet l INVENTOR.

lib. Lu m FRANKRMOE BY M, M

July 31, 1962 F. R. MOE 3,046,815

BLANKING DIE AND METHOD OFMAKING THE SAME Filed July 10, 1957 2 Sheets-Sheet 2 /-29 T g-. 6 1% v 1 f;

INVENTOR.

QMtornegs niteci t York Filed Euly 10, 1%5'7, Ser. No. 679,910 3 Claims. (Ci. 76-407) This invention relates to blanking die assemblies adapted to successively punch blanks from sheet material and particularly relates to a method of making the die assembly.

It has been known to employ a die assembly having a hardened rule with a cutting edge which moves relative to and cooperates with a punch member to punch out blanks from sheet metal or the like. The use of a separate hardened rule permits the use of relatively soft materials for the other components which may be easily formed.

In the above construction, me edges of the punch member preferably lie immediately within the perimeter of the rule such that when the members are telescoped into cutting relation, the edge surface. of the punch member is flush with the inner face of the rule. This action provides excellent blanks having clean and even edges. However, very accurate correspondence between the edge surface of the punch member and the rule is required.

It is presently known to form the rule into the desired configuration by cutting the configuration into a platelike member. The width of the cut is made to correspond substantially to the thickness of the rule such that the rule may be wedged within the cut. This requires very accurate cutting and subsequent machining of a punch member.

In accordance with the present invention, a plate-like die member is provided with an opening by removing a centerpiece having the general configuration of the blanks to be made, but which is somewhat larger all around than the final blank. The cut out centerpiece, which is subsequently employed as a punch pad, is assembled with a master pattern of the blank and with a punch member. The edges are then machined to the shape of the master pattern to simultaneously form precisely the same configuration of the punch and the punch pad. The cutting 4 rule is then secured to the perimeter of the punch pad and disposed within the opening formed in the die member. A viscous material which is capable of setting into a very hard mass is disposed within the space between e opening in the die member and the cutting rule. When this material hardens, it clamps the rule and connected punch pad within the opening. The die member and the punch member are then asssembled with a suitable operating mechanism with the rule accurately aligned with the punch member. Suitable stripping members, knockouts and the like, are normally provided to assist in ejecting the stamped and excess material from between the die member and the punch member.

The viscous material is preferably a suitable plastic which will adhesively bond to the die member and the cutting rule to adhesively support the members together.

* "ice mode presently contemplated by the inventor for carrying out the invention.

In the drawings:

FIGURE 1 is a cross sectional view of a punch and die assembly;

FIG. 2 is a plan view of the punch assembly taken on line 22 of FIG. 1;

FIG. 3 is an inverted plan view of the die assembly taken on line 3-3 of FIG. 1;

FIG. 4 is a perspective view of a completed stamping for purposes of illustration;

FIG. 5 is a plan view of a die ring in the first step in the forming of the die and punch assemblies;

FIG. 6 is a cross sectional view of a master pattern of the stamping of FIG. 4 assembled with various components which are to be machined to the configuration of the master pattern;

FIG. 7 is a cross sectional view of a die ring and a cutting rule showing the method of assembly; and

FIG. 8 is a fragmentary view in section of the punch and die assembly of FIG. 1 during a punching operation.

Referring to the drawings and particularly FIG. 1, blanking apparatus is shown comprising a lower punch assembly 1 secured to a punch plate support 2 and an upper die assembly 3 secured to a movable shoe or adapter plate 4 of a hardened material which in turn is secured to a ram or the like, not shown. The punch assembly 1 and die assembly 3 are shown in a relatively separated state with a metal sheet 4 disposed therebetween. A shear blade 6 in the upper die assembly 3 is adapted to cooperate with a punch 7 in the punch assembly 1 to cut out a metal blank 8 when the die assembly 3 is depressed or lowered.

The metal stamping 8 is shown perspectively in FIG. 4 and is shown as a generally rectangular member having relative rounded corners. This relatively simple configuration is shown for purposes of clarity of illustration only and the stamping may have a much more complicated configuration.

Referring particularly to FIGS. 1 and 2, the lower punch assembly 1 includes a base plate 9 which is substantially larger than the punch 7 which it carries. The base plate 9 is removably secured to the punch plate support 2 by a plurality of suitably spaced bolts 10. The punch 7 is secured to a filler plate 11 by a plurality of spaced bolts 12 and the filler plate is machined to the same outline as the punch 7. The connected punch 7 and filler plate 11 are secured to or rest upon the base plate 9 with a pair of dowels 13 accurately positioning them on the base plate. A pair of punch holes 14 are provided in the punch 7 to allow formation of a pair of openings 15 in the blank 8. The holes 14 are aligned with suitable enlarged openings 16 in the tiller plate 11 and the base pltae 9 to allow discharge of metal through Openings 17 in support 2 when forming openings 15 in the metal blank 8.

A stripper 18 encircles the punch 7 and is provided with four circumferentially spaced openings 19 which accommodate the heads 20 of four upstanding bearing bolts 21, which thread into the base plate 9'. A bearing surface 22'. is provided by the bolts between the plate 9 and the stripper 18. A cup-shaped member 23 has its upper edge secured to the undersurface of the stripper 18 at each opening 19 and is provided with openings in its lower surface corresponding to the diameter of the bearing surface 22 on bolts 21 to slidably support the stripper 1%. A resilient pad 24 is coextensively disposed beneath the stripper 18 with suitable openings for the bolts 21. The pad 24- resiliently urges the stripper 18 upwardly to dispose the upper surface of the stripper 18 and the punch 7 in the same horizontal plane with the pad in an unstressed state.

Patented July 31, 1962 area of the same sheet.

The resilient pad 24 may or the like, or any other suitable material which has the desired degree of resiliency and is not adversely afiected by surrounding foreign mattter. v When the die assembly'3 drops'to cut out the punch 8, the stripper 18 is forced downwardly. When the dieas- .sembly 3 retracts, the resilient member24 forcesthe stripper 18 back to its original position and strips the marginal portionof sheet 5 from the'punch 7 (to allow removal thereof and insertion of a new sheet or a new As the pad 24 is substantially coextensive with :the'stripper 18, an even stripping pressure is applied to the adjoiningrnetal sheet 5.

Referring particularly to FIGS. l and 3, the illustrated I die assembly 3 comprises a supporting die ring 25 which is secured to the adapter plate4'by a plurality of' spaced be formed of neoprene rubber When the die assembly 3 is depressed to cut out the stampbolts 26. Alignment dowels 27 are provided to initially v position the die ring 25 and the adapter plate '4. An opening 28 in the die ring 25 roughly corresponds to V the outline of the'punch 7 but is' somewhat larger. The

shear blade 6 is clamped within the opening 28 in pre- ,cise alignment with the punch 7 by a punch pad 29 and a plastic and sand filler 30 disposed between the edge 29 is formed precisely to the same outline as punch 7 "and, therefore, with the punch pad 29 :and the punch 7 precisely aligned in superposed relation, the inner surface of the shear blade 6 lies in the same plane as the edge of the punch 7 When the blade 6 is moved into .of the opening 28 and the shear blade 6. The punch pad The plastic andsand filler '30 which is disposed between the blade '6 and the adjacent surface of the ope ing 28 serves to clamp the blade, 6 :and pad 29 to the die ring 25 to form a unitary die assembly. The face of the uni- 'tary die assembly immediately adjoining the adapter plate '4 is machined to'prevent vibration of the parts.

The plastic is preferably of a variety to eifect a bond to the adjacent surface of the blade 6 and the die ring 25 to securelysupport the blade 6. The use of a sand and plastic mixture reduces the cost of the filler over a pure plastic, although the latter is otherwise entirely satisfactory.

A plurality of small screws 32 are shown securing the blade 6 to theipunch pad 29. The screws 32 are employed during the fabrication of the die assembly, as

more fully. described hereinafter.

The blade 6 is any suitable hardened steel or the like which can stand the wear of continuously punching out the blanks 8 from the sheet 5. Generally, a commercially available steel rule stock is entirely satisfactory.

The blade 6 protrudes outwardly from the opening 28 in the die ring and is provided with a beveled knife edge 33 for severing blanks 8. A pair of punches 34 are disposed within suitableopenings in the punchpad 29, and are aligned the punch I holes 14 in punch 7 to form the openings 15 in the completed blank 8. The punches each have an enlarged head 35 disposed Within correspondingly shaped recesses in the surface of the punch pad 29 immediately adjoining the adapter plate 4 to securely hold the punches 34 in place. 7

To remove the force of the stripper 18 from the blade 6, a plurality of pressure strips 36 encircle the blade 6 and are welded to the underside of the die ring 25 in outwardly spaced relation to the blade 6. The strips 36 have the same vertical depth as the extent of the protrusion of theblade 6 from the die ring 25 such that the lower surface of pressure strips 36 and the end of knife edge '33 of blade 6 are in the same horizontal plane.

stripper 18 through the interposed sheet 5 and remove the load from the blade 6.

A knockout plate 37 is operatively secured within the a confines of the blade 6 to prevent the completed blank 8 from rising upwardly with the blade 6. The punch pad V 29 is somewhat thinner than the die ring 25 to form a space within the blade 6to accommodate the plate. The

shape of plate 37 generally corresponds to the configuration of blank 8 and the outer edge of plate 37 is disposed in spaced relation to the blade 6. The plate 37 is secured in place by a pair of knockout pins 38, which extend upwardly throughsuitable aligned openings 39 and 40 in the punch pad 29' and the adapter plate 4 respeotively. The upper ends of the pins 38 are secured to a portion of the press assembly, not shown. Coil springs 41 encircle the pins 38 between the punch pad 29 and the knockout plate 37 and bias the pins 38 and attached knockout plate 37 outwardly into engagement with the sheet 5 or blank 8 which lies between the knockout plate 37 and the punch 7. Acoun-tersunk re-' cess 42 is provided in each of the openings 40 to re ceive a crosspin 43 which extends through the pin 38 and is adapted to engage punch pad 2?. The crosspins 43 support the pins 38 in the retracted die assembly position shown in 'FIG. 1. V j

The adapter plate 4 is provided with a plurality of the knockout pin openings 48 each having a countersunk recess 42 such that a variety of dilferent die forms can be selectively secured to a single adapter plate. The openings 40 which are not being used are each sealedby a small screw 44 which is adapted to thread intogthe correspondingly theraded openings 48,. The screws 44 are hardened and have a fiat head 45 which is formed to precisely the same dimensions as the countersunk recesses 42 and maintain a continuous hardened backing surface for the rule 6 and the punches '34. For example the screws 44 can be assemblied with the adapter plate '4 and simultaneously machined to a smooth continuous surface.

When the die assembly 3 is depressed to cut out the stamping 8, as shown in FIG. 8, the knockout plate 37 is brought into engagement with the upper surface of the blank 8. As the die assembly 3 continues to lower and cut out the blanks 8,-the springs 41 are compressed.

When the die assembly3 is retracted topermit removal of the blank 8, the springs 41 expand to maintain the stamping 8 against the upper surface of punch 7. At the uppermost position of the die assembly 3, the knockout plate 37 is lifted upwardly into spaced relation with the stamping 8 and allows removal thereof and insertion bf.

new material; V 7

Suitable openings 47 are provided in the knockout plate 37 to permit the punches 34 to pass therethron'gh and into the punch openings 16. An opening 48 is also provided to accommodate the head of the take'up bolt 31. In accordance with the presentyinvention, the punch 5' assembly l and the die assembly are made in the following manner.

Referring to FIG. 5 the die ring 25 is formed from a plate like member by disposing a master pattern '58 upon the member. The master pattern 58 corresponds to the configuration of the desired blank 8 and is traced. onto the unformed diering 25. The opening 28 is then formed in the die ring 25 in any suitable manner such as by burning out the central portion alongan outline 49 which is in slightly spaced relation to the outline formed by the master pattern 58. The spacing of outline 49 is somewhat the punch 7 which at this point are also uniormed. The master pattern 58 is secured in stacked relation therewith and the assembled stack held together by suitable dowels 50' disposed in suitable aligned openings which may be located to serve as cooperating openings for punches 34 or the like. The edges of the pad 29, filler plate 11 and punch 7 are then simultaneously machined to the configuration of the master pattern 58 to provide a final assembly as shown in FIG. 6. The punch 7, punch pad 29 and filler plate 11 may be of a relatively soft metal to allow easy machining of the edges. The punch 7 is then subsequently hardened to provide a durable punch.

As appears in FIG. 1, the punch pad 29 is thinner than the die ring 25 to accommodate the knockout plate 37 between the pad 29 and the punch 7. The punch pad 29 is machined to the required thickness either before or after machining its edge.

The filler plate 11 and the punch 7 are then bolted together and the punch holes 16 and 14, respectively, are formed therein by drilling or the like. The required openings 39 for the knockout pins 38 and the openings for punches 34 as well as for the takeup bolt 31 are drilled in the punch pad 29.

The rule or shear blade 6 is then formed and secured to the machined edge of the punch pad 29 by the small screws 32. The die ring 25 and the punch pad 29 are then disposed in an inverted position upon a machined supporting surface 51 with the punch pad 29 accurately centered within the opening 28 of the die ring 25 as shown in FIG. 7. The filler plate 11 is disposed within the perimeter of the blade 6 immediately adjacent the outer beveled blade end by a plurality of spacers 52 which are disposed between the plate 11 and the punch pad 29. The plastic and sand filler 38 is then poured into the opening 28 between the blade 6 and the die ring 25 in an uncured condition. The machined supporting surface 51 prevents the plastic from flowing beneath the surface of the die ring 25 and the punch pad 29. The plastic subsequently hardens to clamp the assembly together and bond both the die ring 25 and the blade 6 in place to securely connect the die ring and the punch pad.

The opening 28 need not be precisely formed because the location of the blade 6 is accurately provided for by the punch pad 29 and the plastic fills the space in the -die ring opening 28.

After the plastic 30 hardens, the filler plate 11 and spacers 52 are removed. The die ring 25 and punches 34 and knockout plate 37 are then assembled and attached to the adapter plate 4, as shown in FIG. 1.

The filler plate 11 and punch 7 are secured together by the bolts 12 and attached to the base plate 9, as shown in FIG. 1. The stripper 18 is secured to the base plate to complete the lower punch assembly.

The punch pad 29 and the punch 7 are precisely aligned and due to the simultaneous machining of their edges, as previously described,'the shear blade 6 moves downwardly into flush relationship with the edge of the punch 7 to form a clean and perfect stamping having a very smooth edge.

It the blade 6 should become Worn to an extent requiring replacement, the plastic filler 30 is easily removed and a new rule connected or assembled therewith.

The present invention provides a blanking device for forming precise and accurate blanks. The punching device is easily and rapidly made and employs ready available materials which may be conveniently obtained and formed.

Various modes of carrying out the invention are contemplated as being within the scope of the following 'claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim: 8

1. A method of making a blank forming device, which comprises burning out a centerpiece having an enlarged outline of the blank to be formed from a die block of easily machined metal to form a die ring, stacking the centerpiece and a punch with a master pattern, machining the edges of the centerpiece and the punch together to the outline of the master pattern, hardening the machined punch, reducing the thickness of the centerpiece, securing a cutting rule having a depth slightly greater than the depth of the die ring and centerpiece to the periphery of the centerpiece with the rule extending from only one surface of the centerpiece, reassembling the centerpiece centrally within the opening of the die block with the lower surfaces of the die ring and the centerpiece in the same horizontal plane, filling the space between the wall of the opening and the rule with a miX- ture of uncured plastic and sand, curing the plastic to a hardened mass, and operatively mounting said die ring and punch in opposed relation with said punch and said centerpiece in exact superposed relation.

2. A method of making a blank forming device, which comprises burning out a centerpiece having an enlarged outline of the blank to be formed from a die block of easily machined metal reducing the thickness of the centerpiece, stacking the centerpiece and a punch with a master pattern, machining the edges of the centerpiece and the punch together to the outline of the master pattern, hardening the machined punch, securing a cutting rule having a depth slightly greater than the depth of the die ring to the periphery of the centerpiece With the rule extending from only one surface of the centerpiece, reassembling the centerpiece centrally within the opening of the die block with the lower surfaces of the die ring and the centerpiece in the same horizontal plane, filling the space between the wall of he opening and the rule with a mixture of uncured plastic and sand, curing the plastic to a hardened mass, and operatively mounting said die ring and punch in opposed relation with said punch and said centerpiece in exact superposed relation.

3. A method of forming a metallic die assembly including a hardened punch assembly and a die assembly to form metallic blanks, which comprises the steps of removing a centerpiece from a plate member of a relative- 1y soft metal to define a centerpiece member and an opening in the plate member larger than the blank to be formed, assembling said centerpiece member and a metallic punch of soft metal larger than the blank to be formed in stacked relation, machining the edges of the centerpiece member and the punch to the precise outline of the blank to be formed, reducing the thickness of the centerpiece member, securing a hardened rule to the perimeter of the centerpiece member with the rule projecting perpendicularly from the plane of the centerpiece member, said rule having a thickness less than the spacing between the edge of the opening in the plate member and centerpiece member, and mounting the centerpiece member and the attached rule within the opening in the plate member.

References Cited in'the file of this patent UNITED STATES PATENTS 922,926 Lynch May 25, 1909 1,095,116 Kaven Apr. 28, 1914 1,095,117 Kaven Apr. 28, 1914 1,843,753 De Witt et a1. Feb. 2, 1932 2,212,886 Ruland Aug. 27, 1940 2,433,058 Mesaros Dec. 23, 1947 2,643,715 McClellan June 30, 1953 2,765,034 WilShaw Oct. 2, 1956 2,791,134 Bien May 7, 1957 2,821,871 Sarno Feb. 4, 1958 2,853,134 Deubel Sept. 23, 1958 2,885,913 Lescallette May 12, 1959 FOREIGN PATENTS 295,467 Great Britain Aug. 16, 1928