US3319501A - Stamping or blanking die - Google Patents

Description

y 1957 J. D. RISHER 3,319,501

STAMPING OR BLANKING DIE Filed June 24, 1965 3 Sheets-Sheet 1 INVENTOR JOHN Dv RISHER 1967 J. D. RISHER 3,319,501

STAMPING OR BLANKING DIE Filed June 2-4, 1965 Y Y 3 Sheets-Sheet 2 FIG? I I I '1, 22 40 I fl Q Q y 1967 I J. D. RISHER 3,319,501

STAMPING 0R BLANKING DIE Filed June 24, 1965 3 Sheets-Sheet 3 INVENTOR JOHN D. RISHER BY r ATTORNEY! United States Patent 3,319,501 STAMPING 0R BLANKING DIE John D. Risher, 127 Bonnett St. SW., North Canton, Ohio 44720 Filed June 24, 1965, Ser. No. 466,674 3 Claims. (Cl. 83-698) The present invention generally appertains to blanking or stamping dies which are utilized to punch blanks from sheet material, and more particularly relates to a new and novel blanking die construction and to novel methods of making such blanking die.

In the prior art, it is known practice to provide a blanking die assembly, using a separate hardened rule with a cutting edge. Also, it is known to form a die assembly and a cooperating punch together in a manner so that the die can be made from less material and in a rather inexpensive manner. Another common method, in manufacturing a tool die, is to utilize suitable chemical, electrochemical or electrical means.

At present, in the art of making stamping or blanking dies used to stamp blanks of metal, plastic or other flat materials, a considerably thick piece of heat treatable tool steel is used. Such high carbon tool steel is considerably more expensive than the low carbon mild steels which are commercially available but which cannot be used as the stamping or cutting medium because of their material characteristics.

Such known die assemblies and methods of making the same, as disclosed in the prior art and as known in commercial practices, involve considerable material and labor costs because the die assembly is formed completely from expensive tool steel or from a substantially considerable amount of tool steel and because conventional methods require skilled labor involving a considerable number of man hours in forming the blanking or stamping die.

Having in mind the foregoing defects in the prior art and commercial practices, a primary object of the present invention is to provide an inexpensive but extremely durable and effective blanking die and to provide novel methods for forming such die, which methods result in substantial savings in labor and material costs in fabricating the die.

Another important object of the present invention is to provide a blanking or stamping die which is composed of a major back-up portion of inexpensive, mild steel and a very minor and thin portion of tool steel, which constitutes the working surface or stamping and blanking section of the die.

Still another important object of the present invention is to provide novel methods for temporarily securing the two portions together for initial treatment, primarily forming the die opening and then for permanently securing the two portions together for cooperation with a punch as a stamping die.

A further important object of the present invention is to provide allied forms of novel and inexpensive but extremely effective and durable stamping or blanking dies and to provide novel and inexpensive methods of fabricating such stamping dies without any danger of damaging the tool steel section and in a manner so that the tool steel section forms the working or punching surface of the die, while the mild steel base or back-up portion is used to provide the means for mounting the die on a die shoe.

Generally stated, the die of the present invention is formed from a major base portion, composed of lowcarbon of mild steel, and a facing or operating portion, which is relatively thin and is composed of substantial and durable hardened tool steel. The invention further resides in the method which comprises temporarily ho1d ing the two portions together while the tool steel is machined to form the die opening or blank. After the tool steel is machined, the two portions or parts are separated and the tool steel is heat treated. Then, the two parts are permanently secured together, utilizing the temporary securing means, which is mechanical, and a chemical means, which consists of a cement that is -firm but not brittle so that it will withstand the shock load of a stamping operation.

Thus, the base or back-up portion of the die is formed from inexpensive low-carbon steel and the facing or end of the die is formed from durable hardened tool steel. A very inexpensive mechanical anchoring means is provided to secure the two parts together while the tool steel is machined to size prior to heat treating. Such mechanical anchoring means, plus a cement, is utilized, thereafter, to form the final assembly, avoiding the use of conventional socket head screws and the like which require machining operations.

The foregoing and ancillary objects and advantages and features of merit are attained by the present invention, the preferred embodiments of which are set forth in the following description, succinctly pointed out in the appended claims and illustrated in the accompanying drawings, wherein;

FIGS. 1-6 are prespective views of a stamping or punching die according to the present invention and respectively illustrating steps in one method of forming the die,

FIGS. 7-11 are cross-sectional views of various forms of stamping dies, in accordance with the present invention, showing different mechanical means for joining the minor steel operating portion to the base or major back-up low-carbon or mild steel portion,

FIG. 12 is a perspective view of a die, in accordance with the present invention, where the die is formed to have a die cut on each side of the tool steel section, and

FIGS. 13-18 are perspective views of the stamping or punching die, ilustrating sequential steps in a modified method of forming the die.

Referring now more particularly to the accompanying drawings, and initially to FIGS. 1 6 for an understanding of one embodiment of the method provided, the blanking or stamping die is composed of a base or major portion of mild or low-carbon steel and a minor working portion of tool steel. It is intended that the low-carbon or mild steel and the tool steel will be provided in large lengths and sections can be cut or severed to provide the desired length of the die, as shown in FIG. 1, with only the ends of the sections to be finished. With more particular reference to FIG. 1, the die 10 is composed of a major base or back-up portion 12, which is formed from inexpensive low-carbon, mild steel, and a facing or working portion 14, which is relatively thin and which is formed from tool steel.

Thus, the die consists of a mild steel and a tool steel, bot-h of which are provided in long bar sections, with the sections being formed in a manner so that they can be severed into the lengths for producing a laminated or composite operating die. It is to be noted that the base or major portion 12 has a cut out section 16 in one face thereof, such cut out section 16 having a hat surface 18, normal to the directional movement of the die and in relation to a cooperating punch, and a right angularly related flat surface 20.

The latter is provided with a groove 22 that extends the full length of the base portion and which preferably is formed at the juncture between the surfaces 18 and 2G. The relatively thin working section 14 of tool steel is formed to complement the base portion and fill the cut out section 16, as shown in FIG. 2, and has a base surface 24 which is adapted to seat on the surface 18, and has a side surface 26 which is adapted to fit flush against the surface 20. The working section 14 is formed with a rib or tongue 28 at its lower inner edge, the tongue being shaped complemental to and adapted to fit in the groove 22.

In the method of forming the die, the elongated stocks of mild steel and tool steel are cut to the desired length to provide the desired length of the die, as shown in FIG. 1. The two sections are secured temporarily together by a clamping means 30, as shown in phantom lines in FIG. 2, and dowel holes 32 and 34 are drilled or reamed through the respective sections if such dowel holes have not previously been provided in the bars 12 and 14. The clamping means is then removed and the edges of the dowel holes 32 and 34 are countersunk, if desired.

Dowel pins 36 are then inserted into the dowel holes 32, 34 to securely hold the two sections together as a temporary measure with the interfitting mechanical engagement of the tongue 28 and groove 22 assisting in locating and maintaining the sections together. The two sections are then machined, in a suitable manner, so as to finish machine the die opening 39, resulting in the temporary die assembly of FIG. 3. The dowel pins 36 are then removed and the tool steel section 14 is heat treated to the desired hardness, in any suitable manner, FIG. 4.

As shown in FIG. 5, the two sections are reassembled with rib 28 fitting in the groove 22 and dowel pins 38, which are of a slightly smaller diameter than the dowel pins 36, inserted into the holes 32, 34. Prior to this step, a suitable amount of epoxy cement and hardener is applied in a thin layer 40 to the contacting surfaces of the major base or back-up portion 12 and the minor or work- 'ing portion 14, after such surfaces are thoroughly cleaned by using a cleaning agent, such as denatured alcohol. A cement that is suitable consists of five parts epoxy and three parts of a suitable polymer with a proper amount of hardening agent in respect to the amount of epoxy used. This provides a cement that is firm but not brittle and is resilient enough to withstand the shock load developed in stamping operations. One commercial type of cement that may be used is known as #RB-IZSO (Rem Plastics Inc., Lansing, Michigan) and a suitable polymer is T hiokol (Thiokol Chemical Corp., Trenton, NJ.). Such cement is, and should be, impervious to all types of lubricant used in blanking or stamping operations.

It is desirable that a slight clearance be provided between the mating surfaces of the sections (for example, .002 to .003) to compensate for the thickness of the cement layer, but the offset interfitting arrangement and dowel pins can serve to squeeze thereby maintaining an accurate of cement between the sections without the need to utilize clamps or other external forces. However, flat shims may be interposed between the mating or adjacent surfaces of the two sections, during the initial operation, when the sections are clamped temporarily together and the holes for the dowel pins are being formed. This will provide a clearance between such mating surfaces, to be taken up by the fine layer of cement placed on such surfaces in the final stages of the method.

The dowel pins 38, constituting part or all of the mechanical means, which are used to permanently hold the sections together, along with the chemical means, which is constituted by the cement, are inserted at the cementing stage and will slip freely into the holes 32, 34' which are formed in the two sections 14, 12 and which mate together. The gap, between the undersized pins and the holes, will be filled with thesame cement used to bond the sections together. The slightly undersized dowel pins 38 are employed because th e holes may not quite line up after the cement is applied since the application of the cement will cause a slight mismatch of the holes drilled thickness (fine layer) out the surplus cement,

and reamed when the steel sections initially were in contiguous contact with no cement therebet'w'een.

After the cement is applied and the sections assembled together by driving in the dowel pins 38, which, of course, have been thoroughly cleaned, the cement is dried in any suitable manner. For example, the assembleddie may be subjected to a temperature up to F. for about two hours. Alternatively, it can be left under atrriospheric conditions until the cement has set, usually a period of about twelve hours, more or less. After the cement has set, the laminated or composite die is finished by a grind ing operation and holes 41, 42 are drilled and tapped into the base or back-up portion for mounting the die to a die shoe (not shown). It is important to note that the holes 41, 42 are formed in the mild steel base or back-up portion 12 which results in a savings in time and which eliminates any possibility of damage to the working steel section 14. The finished laminated or composite die 10 is shown in cross-section in FIG. 7.

While the foregoing describes a preferred form of mechanical or structural interfitting means between the two sections, other mechanical joints or interfitting means may be provided between the two sections. For example, as shown in FIG. 8, the two sections 12 and 14' can be in square abutting relation and held in place by the dowel pins 38, and the cement 40. In this form, it is to be noted that the holes 32 and 34' and the fitted dowel pins 38 are not perpendicular to the back-up section 12' and the working section 14' but, instead, are at an obtuse angle thereto. Thus, the dowel pins 38 are inclined toward the mating faces 26' and 20' of the two sections to force the sections into firm facial contact with the cementitious material interposed therebetween.

Alternative to the oifset rib 28 and groove 22 arrangement of FIG. 7, an angular shoulder arrangement, as shown in FIG. 9, can be utilized to advantage. As shown therein, the minor working section 14a has an angular face 26a which engages an undercut face 20a on the base or back-up portion 12a. This provides an angular shoulder locking arrangement. Of course, the dowel pins 38a are similar to the dowel pins 3-8 and 38 and the method of temporarily and permanently securing the two sections together is the same as hereinbefore described in connection with FIGS. 1-6.

Another mechanical interlocking or interengaging arrangement is shown in FIG. 10, wherein the working section 14b is formed on its inner face 26b with a groove 48 that receives a complemental projection 50 on the face or surface 2% of the section 12b. This provides a keyed joint midway of said faces instead of at their edge portions.

As shown in FIG. 11, the dowel holes 32c, 340 of the sections 14c and 12c may be angled to receive the dowel pins 38c (similar to FIG. =8), the rest of the mechanical interlocking arrangement being the same as that shown in FIG. 7. Obviously, such angular dowel pin arrangement can be used with any of the other interfitting mechanical forms.

It is important to note that in all modifications the two sections are complemental to each other and are formed with confronting surfaces which are mounted together in contiguous relation by the cement and positively secured by a mechanical interlocking or interfitting arrangement, such arrangement comprising the dowel pins and offset portions relative to said confronting surfaces providing the interengagin-g or interfitting locking means. V

In the instance wherein die cut is necessary on each side of the die, the arrangement as shown in FIG. 12 may be provided. The base or back-up portion 52 is formed from mild steel, similar to the base or back-up portion 12 and the minor working portion 54 of the die is formed from tool steel. The two portions or sections are temporarily and permanently secured together in the same manner as described in connection with FIGS. 1-6. The mechan i'cal interlocking arrangement 56 consists of a groove 58 in the upper face of the base or back-up section 52 and a depending interfitting rib 60 on the lower underface of the top or working section 54 with the cement between the mating faces of the sections.

Thus, it can be seen that there is provided a stamping or punching die which is of laminated or composite construction and which is composed of a section or portion of heat treatable tool steel, which is the working or punching surface and which is of minor cross sectional thickness, and a major base or back-up section or portion of low-carbon or mild steel. The two sections are preliminarily secured together ready to be machined to provide the proper outline of the die. After such outline is provided, the sections are separated and the tool steel section is heat-treated and then the two sections are rejoined and permanently secured together, utilizing the temporary mechanical means, as a permanent joining means, and a chemical means, namely, the disclosed cement or similar bonding agent. This will provide a pre-finished component that can then be treated by tapping and reaming holes in the mild steel section to anchor and position the die on a die shoe.

In FIGS. 13-18, -a slightly different, but, essentially similar, method of forming the die, such as the die 10', is illustrated. As shown therein the two sections 12 and 14' are formed in complemental fashion, identical to the sections 12 and 14 of FIG. 1.

However, in setting up the sections for the machining operation, a .004 (for example) flat shim 62 is interposed between the vertical adjoining surfaces and 26'. The tool steel section 14' and mild steel section 12' are in direct facial contact at their horizontal surfaces 18 and 24' with no shim being interposed therebetween.

The two sections 12' and 14' are clamped together (FIG. 14) by the temporary clamping means 30 and the desired size dowel holes 32 are drilled and reamed while the sections are held tightly together. Dowel pins 64 are forced into the holes 32 and other work, as set forth in the explanation of the method of FIGS. 1-6, is completed.

The two sections are separated (FIG. 16) and the shim is removed and the tool steel section 14 is subjected to heat treatment.

After heat treatment, the tool steel section 14' is placed on a surface grinder, or, in other conventional manner, the section 14' has its horizontal surface 24' treated so that, approximately, .005 to .008 inch is removed or ground off. This provides a good flat surface for mating with the complemental surface 18 of the section 12' and also provides a .005 to .008 inch (approximately) gap to be filled with the cement, of the type above described.

Using the same original dowel pins 64 and the interlocking arrangement 28' and 22, the sections are permanently fixed together (FIG. 18). The dowel pins 60 are forced back into the holes 32', after the adjoining surfaces of the two sections are covered with the cement. The forcing of the pins back into their original holes will secure the sections tightly together and will squeeze out all of the surplus cement from between the joint and the adjoining surfaces of the sections, leaving a slight layer 40a (.004) of cement between surfaces 20' and 26' and a slight layer 40b (.005) of cement between surfaces 18 and 24'.

The foregoing method is particularly advantageous because during the heat treatment of the tool steel section 14' (FIG. 16), such section may possibly become warped since it is so thin. The grinding of the surface 24', after heat treatment of the section 14' will remove any possible warp and will provide assurance of two more flat mating surfaces 16' and 24' for cementing.

Of course, this method may be used in connection with the employment of undersized dowel pins, in the final operation, as set forth in the method of FIGS. 1-6.

In any event, it is to be noted that the external surfaces of the sections of the dies, irrespective of the mechanical interlocking arrangement are coplanar.

Regardless of the mechanical interfitting means between the sections, one, the major back-up section of inexpensive, mild steel, and the other, the thin working or punching section of tool steel, it is to be understood that the contiguous faces of the sections are bonded together by the disclosed or other appropriate cement.

It can be appreciated that the die will be extremely inexpensive due to the fact that the section of tool steel employed is extremely small relative to the section of mild steel and, obviously, tool steel costs approximately five times more than the cost of mild steel, which constitutes the major base or back-up portion. Therefore, there results a considerable savings in material costs and, because of the disclosed method of making the die, it can be appreciated that there will be a considerable saving in labor costs. Also, there is no tapping or reaming in the tool steel to provide the holes for mounting the die on a die shoe, whereby there is no danger of cracking the tool steel section or creating any hazardous wear factor.

It is important also to note that once the working surface (i.e. the tool steel section) becomes unusable, due to considerable use, the two sections can be separated by heating the sections to approximately 400 F. which will soften the cement. The dowel pins then can be driven out and the minor tool steel section removed for replacement by another, in the same manner as the replaced one was secured originally to the base or back-up portion.

While the best known forms of the dies of the present invention have been illustrated and described herein and the best known manner of fabricating the laminated or composite dies has been shown and described herein, other forms may be realized and other methods may be practiced, as come within the scope and spirit of the appended claims.

What is claimed is:

1. A die assembly comprising, in combination, a length of mild steel stock forming the base portion of the die, said base portion having fiat, parallel upper and lower surfaces, the latter of which is adapted to rest upon a die shoe, and opposite side surfaces, said base portion also having an upwardly facing flat supporting surface extending inwardly from and completely along the length of one of said side surfaces and terminating short of the other side surface, said base portion also having a flat attaching surface forming an edge with said upper surface which is parallel with said side surfaces, and said attaching surface extending downwardly from such edge towards said supporting surface, a length of tool steel stock forming the working portion of the die, said working portion having a flat bottom surface and a flat side surface which are complemental to the supporting and attaching surfaces of said base portion respectively, said working portion also having an opposite side surface and a top surface which intersect to form the cutting edge of the die, a pair of upright dowel pins pinning said working portion to said base portion and establishing a predetermined parallel spacing between said fiat side surface of the working portion and said attaching surface of the base portion, and bonding means filling the gap between said flat side surface of the working portion and said attaching surface of the base portion, and interposed between and joining said flat bottom surface of the working portion and said supporting surface of the base portion.

2. The die assembly as defined in claim 1 wherein said working portion is provided with a tongue at the junction between said side surface and said bottom surface thereof and forming a continuation of the latter, said tongue having an upper surface parallel to the bottom surface of the working portion, said base portion being provided with a groove at a junction between its supporting and attaching surfaces for receiving said tongue, said upper surface of the tongue being seated Within said groove against said base portion and establishing a predetermined spacing between said bottom surface of the working portion and said supporting surface of the base por tion with said bonding means filling such space.

3. The die assembly as defined in claim 1 wherein said Working and base portions are provided with holes of predeter-mined diameter receiving said dowel pins, said dowel pins being of a diameter less than said prede- ,terrnined diameter of the "holes by an amount equal to '8 said spacing between a side surface of the Working portion and said attaching surface of the base portion.

References Cited by the Examiner UNITED STATES PATENTS 8/1964 Brearley et a1. 76107 FOREIGN PATENTS 102,526 12/1916 Great Britain.

10 ANDREW R. JUHASZ, Primary Examiner.

Claims (1)

1. A DIE ASSEMBLY COMPRISING, IN COMBINATION, A LENGTH OF MILD STEEL STOCK FORMING THE BASE PORTION OF THE DIE, SAID BASE PORTION HAVING FLAT, PARALLEL UPPER AND LOWER SURFACES, THE LATTER OF WHICH IS ADAPTED TO REST UPON A DIE SHOE, AND OPPOSITE SIDE SURFACES, SAID BASE PORTION ALSO HAVING AN UPWARDLY FACING FLAT SUPPORTING SURFACE EXTENDING INWARDLY FROM AND COMPLETELY ALONG THE LENGTH OF ONE OF SAID SIDE SURFACES AND TERMINATING SHORT OF THE OTHER SIDE SURFACE, SAID BASE PORTION ALSO HAVING A FLAT ATTACHING SURFACE FORMING AN EDGE WITH SAID UPPER SURFACE WHICH IS PARALLEL WITH SAID SIDE SURFACES, AND SAID ATTACHING SURFACE EXTENDING DOWNWARDLY FROM SUCH EDGE TOWARDS SAID SUPPORTING SURFACE, A LENGTH OF TOOL STEEL STOCK FORMING THE WORKING PORTION OF THE DIE, SAID WORKING PORTION HAVING A FLAT BOTTOM SURFACE AND A FLAT SIDE SURFACE WHICH ARE COMPLEMENTAL TO THE SUPPORTING AND ATTACHING SURFACES OF SAID BASE PORTION

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