US2377191A - Drawing die - Google Patents

Description

F. E. TEACHOUT May 29, 1945.

DRAWING DIE Filed Dec. 4, 1942 /Nl/ENTO Few/(E. 775401007 A-r-rozA/E Y6 Patented May 29, .1945

UNITED STATES PATENT OFFICE DRAWING DIE Frank E. Teachout, Minneapolis, Minn. Application December 4, 1942, Serial No. 467,867

2 Claims.

This invention relates to new and useful improvements in drawing dies and particularly to a novel means for securing the die in its supporting member.

Dies used for drawingyarious forms and types of tubular articles, particularly articles of considerable length, such as bullet shells, must have their walls accurately machined, hardened and polished, whereby the shells may be accurately drawn therein with the assurance that the shell walls will be reduced to the required thickness. This is particularly true of the dies used for making the final draw, although it is to be understood that similar dies may be utilized for each of the preceding drawing operations.

Heretofore it has been more or less common practice to construct such dies in the ,form of an enlarged cylindrical body of a suitable metal such as tool steel, in which the usual die chamber or opening is provided. After the die chamber or opening has been substantially completely finished, the die body is hardened or tempered in accordance with well known methods, for the purpose of hardening the walls of the die chamber whereby they will resist wear. Because of the size of such die bodies and the lengths of the die chambers, it has been found exceedingly difiicult to uniformly harden the walls of the die chamber, the wall surfaces at the central portion of the die chamber frequently being insufliciently hardened, whereby such wall portions may wear more rapidly than the relatively harder end wall portions of the die chamber. The primary reason for such inaccurate hardening of the die chamber walls has been caused primarily because of the length of the die chamber and the thickness of the walls of the die body, it being understood that heretofore such dies have usually been constructed of a single unitary block of metal.

Because of the inability to adequately harden the walls of the central portion of the die chamher or bore, as above stated, considerable difficulty has heretofore been experienced in drawing the work or shells, frequently resulting in the work or shells becoming jammed in the die. Such jamming of the work in the die usually results in interruption of the manufacturing operation which may be extremely costly, as in such cases, it is usually necessary to replace the die. Imperfections in the walls of the dies may also result in the production of imperfect shells, which are usually rejected, and thus further adds to the cost of manufacturing the shells.

It is therefore highly desirable that a die be of the die chamber may be adequately tempered shells may readily be withdrawn or ejected from the die following each drawing operation.

An important feature of the present invention, therefore, is to provide a drawing die comprising a supporting member or jacket having a hardened insert or die sleeve mounted therein in fixed relation, and said die sleeve being constructed of a suitable fine grained metal which may readily be uniformly tempered and hardened so as to provide a highly polished wear-resisting surface, which will withstand wear for long intervals, whereby the diemay be used for quantity production work over long periods of time without requiring replacement.

A further object is to provide a two-piece drawing die comprising a die body of-conventional size, having an axial bore therein adapted to receive a tapered die sleeve which is fixedly secured in the die body or jacket by means of a tapered lock pin.

A further and more specific object of the invention is to provide a drawing die comprising an outer supporting member or jacket having a tapered bore therein terminating at its upperend in a conical seat, and an enlarged cylindrical bore extending upwardly from said conical seat to substantially the top of the die jacket, and a tapered die sleeve being fitted into said tapered bore and having a portion received in said cylindrical bore and engaging the conical seat, whereby the die sleeve may be supported in the supporting jacket without danger of relatively shifting its position therein, and a tapered lock pin being mounted in the jacket and engaging a portion of the die sleeve, thereby to secure the sleeve against removal from the supporting jacket.

Other objects of the invention reside in the novel arrangement of the conical seat provided in the bore of the die jacket for receiving a correspondingly shaped face provided on the die sleeve, and in the angle of said conical face whereby it will provide maximum support for the die sleeve; in the provision of the large cylindrical portion in the upper portion of the die sleeve and in the manner of mounting the tapered lock pin in the die jacket, whereby it will engage a notch or recess in the periphery of the cylindrical portion of the die sleeve; and in the provision'of a die sleeve whose walls are so proportioned that they may readily be uniformly tempered and hardened before the sleeve is inserted in the jacket and secured therein, after which the walls of the die chamber in the die sleeve may be completely finished and polished, before mounting in the die jacket in its supporting means in the punch press.

Other objects of the invention will appear from the following description and accompanying drawing and will be pointed out in'the annexed claims.

In the accompanying drawing there has been disclosed a structure designed to carry out the various objects of the invention, but it is to be understood that the invention is not confined to the exact features shown, as various changes may be made within the scope of the claims which follow.

In the drawing:

Figure 1 is a sectional elevation of my improved die, showing the general construction thereof Figure 2 is a top view of the complete die;

Figure 3 is a sectional plan view on the line 3-3 of Figure 1, showing the tapered lock pin;

Figure 4 is a side view of the die jacket without the die sleeve, partially broken away to more clearly illustrate the construction thereof;

Figure 5 is a vertical sectional view of the die sleeve removed from the jacket; and

Figure 6 is a view illustrating the shape of the shell produced by my improved drawing die.

In the selected embodiment of the invention herein disclosed, there is illustrated in Figure 1, for purpose of disclosure, a portion of the frame of a conventional punch press, generally designated by numeral 2, which is shown having a supporting socket 3 therein for removably receiving the drawing die.

The novel drawing die herein disclosed is shown comprising an outer supporting member or jacket 4, which preferably is cylindrical in cross section, although it is to be understood that it may be otherwise shaped, if desired, without de arting from the scope of the invention. Suitable means, not shown, is provided for securing the jacket 4 in the socket 3, as is well known in the art.

A feature of the present invention resides in the provision of a suitable die sleeve or insert within the jacket 4. This die sleeve, generally designated by the numeral 5, is fitted into a tapered bore i provided in the jacket I. The bore 8 extends upwardly from the bottom of the jacket and terminates at its upper-end in a conical seat I. A cylindrical bore 8 is provided in the upper portion of the jacket 0, and extends upwardly from the conical seat 1 to a shallow counterbore 9 provided at the upper end of the jacket, as best shown in Figure 4.

The lower major portion of the die sleeve 5 is tapered, and is adapted to be fitted into the tapered bore 6 of the jacket, as clearly shown in Figure 1. The die sleeve has a cone-shaped face ll adapted to engage the conical seat I in the bore of the jacket. The sleeve further has a cylindrical portion l2 adapted to be fitted into the cylindrical bore 8 in the upper portion of the jacket.

To accurately locate the die sleeve 5 in the bore 6 and to prevent relative rotation thereof in said bore, the upper-most end of the sleeve is provided with an annular flange l3 adapted to be received in the shallow counterbore 8 provided in the upper end of the jacket.

when the die sleeve is fitted into the bore i of the jacket I, as shown in Figure 1, a small hole I is drilled into the top end of the jacket 4 in a manner to partially cut through the flange I: of the sleeve 5. Then when the die sleeve is inserted into the bore 6 of the jacket, 8. small pin I5 is driven into the hole I4, and this pin serves as a key to prevent relative rotation of the die sleeve in the jacket, as will readily be understoodbyreferenceto Figures 1and2. Theupper end of the pin I5 is preferably flush with the upperend of the jacket. as shown.

Another important feature of the invention resides in the novel means provided for fixedly securing the die sleeve in the bore 6 of the jacket, and whereby the die sleeve becomes, in effect, an integral part of the jacket.

The means provided for thus locking the die sleeve in the jacket is best shown in Figure 3, and comprises a tapered lock pin 16, received in a correspondingly tapered socket or aperture I! provided in the jacket I. The axis of the aperture I1 is preferably located substantially at the periphery of the enlarged cylindrical portion l2 of the die sleeve, as shown in Figure 3, whereby a semi-cylindrical notch or recess I8 is provided in the periphery of the cylindrical portion [2 of the sleeve, as best shown in Figure 5. By this arrangement, it will be noted by reference to Figures 1 and 3, that the body of the lock pin I6. because of being received in the notch l8 of the sleeve, provides a lock for the die sleeve whereby it cannot possibly be removed from the jacket 4, so long as the tapered pin I6 is positioned in the tapered aperture II, as shown in Figure 3.

To prevent the lock pin 16 from accidently working loose, or becoming detached from the jacket 4, the lock pin is preferably provided with a threaded head l9 which is received in threaded engagement with a threaded socket 2| provided in the jacket I. The head l9 may be provided with a suitable slot or socket 22, whereby the lock pin 16 may readily and conveniently be rotated by the application of a suitable instrument to the head IQ of the lock pin.

In some instances it may be found desirable to omit the screw threaded head l9 of the lock pin, and use an ordinary tapered pin. When utilizing such a tapered pin, it may be necessary, for all practical purposes, to drill the tapered aperture I! completely through the jacket 4, whereby the tapered pin may be removed, when desired, by applying a suitable instrument to the small end thereof and driving it out of the tapered aperture in the jacket, as will be understood. In some cases it may also be deemed more desirable to utilize an ordinary lock screw in lieu of the threaded head IQ of the lock pin. Such a lock screw may be screwed into the threaded socket 2| and into engagement with the adjacent end of the lock pin, as will readily be understood by reference to Figure 3.

Another feature of the invention resides in making the die sleeve 5 of an extremely hard fine grained metal'whose inherent characteristics are such that it may readil be uniformly tempered and hardened by well known processes, such as oil tempering. Paragon steel is such'a metal and it has proven very desirable in the manufacture of the sleeve 5. By reference to Figure 5, it will be noted that the thickness of the wall of the die sleeve is such that the metal will take a uniform temper and hardness clear through the wall, which is of utmost importance, in that the sleeve wall may thus be uniformly tempered and hardened throughout the entire length of the sleeve.

The configuration of the die chamber or bore 23 in the die sleeve 5, is made to correspond to the configuration of the particular work or article to be drawn, which, in the present instance, is shown as being bullet shells 24, shown in Figure 6. The outer surface of the wall of the finished shell 24, when the drawing operation has been completed will conform identically to the configuration or shape of the die chamber 23 in the die sleeve 5. The interior 25 of the shell 24 will conform identically to the configuration of the usual punch 26, carried by the usual ram 21 of the press.

Another feature of the invention herein disclosed resides in the angle a of the conical seat I of the jacket. This angle is such that the maximum portion of the pressure exerted on the die sleeve by the downward movement of the punch 25, during the drawing operation, is taken up by the seat 7. A portion of the pressure is, however, taken up by the accurate fit of the tapered end portion of the sleeve in the tapered bore 6.

By thus shaping the periphery of the die sleeve 5 and supporting it in the tapered bore 6 and on the conical seat 1, as hereinbefore stated, it will be noted by reference to Figure 1, that the sleeve is firmly supported around its entire circumference and substantially its entire length.

In the drawing I have shown the upper enlarged portion I2 of the die sleeve as being cylindrical in form. If added support for the die sleeve in the jacket is found necessary, the enlarged portion I! may be slightly tapered, in which case the socket 8 in the jacket 4 is correspondingly tapered, whereby the entire length of the sleeve may be firmly supported in the bores 6 and 8 of the jacket 4.

From practical experience I have found, however, that the enlarged portion l2 need not necessarily be tapered, whereby the operations of boring the jacket 4 and machining the exterior ofthe die sleeve, are somewhat facilitated.

A two-piece drawing die such as herein described, may be manufactured at low cost, as the die sleeve may be manufactured independently of the jacket 4, and in like manner the jackets may be manufactured independently of the die sleeves. When the die sleeves have been suitably tempered and hardened, they are fitted into and secured to their respective supporting jackets 4, after which the walls of the die chamber or bore 23 are finished and polished to the correct size, as hereinbefore stated.

From actual experience I have found that the supporting jackets 4 may be made from conventional drawing die bodies which may previously have been discarded because of inaccuracies found in the die chambers thereof. When such inaccuracies occur in conventional drawing dies, the entire die body may be rendered unfit for further use, whereby it is usually discarded or scrapped, and a new one substituted therefor. Conventional dies which may thus have been discarded, may be reclaimed and rendered fit for many more hours of use by reconditioning them in accordance with my invention, asherein disclosed.

By making the die sleeve 5 of a relatively hard fine grained metal, the walls of the die chamber or bore 23 may readily be accurately machined and polished, and because of the extreme hardness of the metal, the resultant die will stand up for long periods of use, which heretofore has been impossible with dies made from one solid piece of metal, regardless of the characteristics of the metal.

By mounting the die sleeve 5 in the jacket 4, as herein disclosed, should the sleeve become worn from long and continued use, it may readily be removed from the jacket 4, by removal of the lock pin I I, and a new die sleeve substituted therefore, thereby saving considerable expense in the upkeep and maintenance of the dies. The jacket 4 may be utilized indefinitely, as it is subjected to very little wear as a result of being non-movably supported in the press socket 3, while the dies are in use.

Also because of the exterior dimensions of the jacket being identical to dies of this general type now in common use, no alterations are required in the punch presses or other equipment where these dies may be employed, whereby my invention is readily applicable to all such apparatus. This, too, is an important feature of the invention.

From the foregoing, it will thus be seen that by the employment of my novel die, shells and various other tubular articles which require a drawing operation such as used in the manufacture of shells, may be manufactured in quantity production at a relatively lower cost than has heretofore been possible with standard equipment, primarily because my improved die may be continuously operated for long periods without interruptions, and with the assurance that every shell or piece of work will be accurately formed, thereby effecting a saving in time and material in the operation of each press equipped with the invention.

It will be apparent to those skilled in the art that I have accomplished at least the principal objects of my invention, and it will also be apparent to those skilled in the art that the embodiments herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described; hence it will be appreciated that the herein disclosed embodiments are illustrative only, and that my invention is not limited thereto.

I claim as my invention:

1. In a drawing die, an outer supporting jacket having a tapered bore therein terminating at its upper end in a conical seat, an enlarged cylindrical bore extending upwardly from said conical seat, a die sleeve having a tapered portion snugly fitting into said tapered bore and a cylindrical portion snugly fitting into said cylindrical bore, said cylindrical portion having a conical face engaging said seat and cooperating with the tapered portion of the die sleeve to support the die sleeve against relative downward movement in said jacket, and a lock pin for inseparably securing the sleeve in said aligned bores.

2. In a drawing die, an outer supporting jacket having a tapered bore therein terminating at its upper end in a conical seat, an enlarged cylindrical bore extending upwardly from said conical seat, a die sleeve having a tapered portion fitting into said tapered bore and having a cylindrical portion snugly fitting into said cylindrical bore, said cylindrical portion having a conical face engaging said conical seat and cooperating with the tapered portion of the die sleeve to support the die sleeve in the supporting jacket against relative downward movement therein, and a tapered lock pin mounted in the jacket and engaging the cylindrical portion of the sleeve for inseparably securing the sleeve in the jacket.

FRANK E. TEACHOUT.

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