US2364005A - Method of forming drawing dies and apparatus therefor - Google Patents

Description

Nov. 28 1944. u smjONs i 2,364,005

mania or towns mums DIES mm APPARATUS THEREFOR Filed Oct. .19, 1943 Patented Nov. 28, 1944 UNITED STATES PATENT OFFICE METHOD OF FORMING DRAWING DIES AND APPARATUS THEREFOR Morris Simons, Ridgefield, Comi. Application October 19, 1943, Serial No. 506,840

Claims. (c1. 76-107) This invention. relates to the manufacture of i that type of drawing die in which a very hard 1 nib is supported in a steel casing. The nib is usually formed of tungsten carbide or analogous material, which includes such metals as tungsten, tantalum, and the like, in combination with a binder. The insert, although extremely h'ard, has relatively low tensile strength, and as the use ofthe die in drawing operations exertsa very great outward pressure on the die, it is important that e the hard material hereinafter referred to as tungsten carbide, be externally supported by a strong,

tightly fitting casing. l e

Various methods have been proposed for forcing the metal of the casing into proper engagement with, and the necessary pressure against the nib orinsert of the tungsten carbide. One process which has proved satisfactory, in commercial use is that disclosed and claimed in my prior Patent 1,952,388, issued March 27, 1934. Other ;methods involve the casting of, the casing around Q the nib or the grinding of the outsideof the insert and the inside of the casing to allow a clear- --ance of about0.002 inch when the casing isheated sozlthatwhen thecasing cools andshrinks, it

firmlyengages and holds the insert.

The processof my prior patent above referred to eliminated a great deal of'the work and reinforced the insert more securely than did other priormethods, but the process is costly, 'slow, and requires the use of only those certain steels which can be properly forged. Furthermore, variations in the operation of the'percussion press resulted in varying degrees of strengthin the final product, as a low pressure exerted by the press, will not forge the casing against the nib withthe re quired pressure, and too great a pressure in the forging press develops stresses which weaken the die. The main objects of the present invention are to provide a process inwhich uniform results are insured; the desired inward pressure of the casing on the nib is obtained, and the speed of production is greatly increasedythereby lowering the which slightlytapersso that the casing of the die to be manufactured may be forced through this outer or forming die to force the metal of the casing inwardly against the nib soas toexert the desired pressure on the nib and independentof slight variations in the size of the chamber in the casing or the size of the nib inserted therein.

. As an important feature of the invention, the outer orforming dieis so constructed that a series of the dies to be manufactured may beforced through in succession and in superposed positions so that each one acts to force the preceding one on through the forming die. This extrusion method is .thus very simple, produces uniform results, and permits of high speed'production.

In the accompanying drawing, I have shown apparatus which may be employed in carrying out my improved process and have illustrated the parts in the successive positions which they occupy during the process.

Fig. 1 is a longitudinalsection through a portion of a forming die with the nib carrying casing of the die to be produced, loosely inserted therein.

Fig. 2 is a view of the same parts with the die forced part way through the forming die, and

Fig. 3 shows the formingdie with a series of the dies being manufactured and in positions they occupy in passage through the forming die.

In the apparatus illustrated, there is provided a forming die having a casing l0 formed of strong, hard alloy steel and having an inwardly extending flange H at the lower end and presenting a shoulder". Seated on this shoulder is a sleeve I3 of hard material such as tungsten carbide. The sleeve tightly fits within'the passage through the casing l0 and is strongly supported externally by said casing. The passage of the sleeve I3 tapers;

the internal diameter at its upperend being slightly greater than the external diameter of the sleeve. The sleeve l3 may be held'in place by a superposed sleeve or liner l5 which may be oi hard alloy steel and which'has apassage therethrough of an internal diameter which may be substantially the same as that of the upper end of the passage through the sleeve I 3.

The die to be formed includes a casing IB of. hard alloy steel witha central chamber l1 within which is placed the nib l8 to rest ona shoulder This insert I8 is shown as having a tapered passage 20 therethrough and the casing I6 is shown as having an aperture 2| in alignment with said passage 20, but these need not be formed until after the forging operation on the die casing.

In carrying out my process, the nib I8 is formed of such diameter that it may be slipped into the cavity I! when the casing It has been heated to bright cherry red or other suitable f-o-rgeable condition. The hot expanded casing, with its nib, is then dropped into the forging die and will slip through the .liner l5 and come to approximately the position shown in Fig. l with the lower end of the casing It engaging the upper tapered section of the tungsten carbide sleeve.

l3 at some distance abovethe point lIA. upper tapered section is primarily to properly center the die casing [6 within thesleeve1l3. hardened steel spacer is then droppedlthrough the liner above the assembly of nib l8 and die casing l6. This spacer is inthe form :of'adisc 22, the external diameter 'of which is such that it may pass "through the lower "smaller end of the sleeveil3. 1A pre'ssplunger 23 is then "moved downwardly "on to theidisc1-22 to force the latter andthe 'die -"casing l6 andits nib [8 downwardly partway "through thelower tapered portion ,of

the sleeve 13. The parts will then be in the position shown in'Fig. 2. 'In:thisoperation, the peripheral-Wall .of the .die .casing I B isfor ced "inwardlylbythe'taperedwall of the sleeve l'3and pressed *into'the desired firm pressure :contact "withtheinset ornib 1'8. "Thetaper'in the sleeve L3 is such that the metal Of the peripheral "wall "of the.:casing f6 will;bejforced inwardly'tofirmly grip the periphery of the nib, and the upper;

part above the nib wilLfiOwiinwardly toform, an annuarjiflangefl'l above .thenib 18, as shown in The exteriorof ithe casing 16,.as 'formedza'n'd inserted .to' the position' showninFigLL may vary slightly an'dflthe flowing of the metal "fromlthe peripheral wall inwardlyabove the ni-b'thustakes care of. slightexcess thickness of the original Wall of .the .cas'ing .l'6,- as well .asithe slight reduction of .such wall thickness during, the. .forcing .of the casing through the tapered sleeve 13.

.The disc. 22 .may lie. directly upon .the .top Qof .the: die casing L6, .but preferably this. disc. has a boss 25 fofla diameter somewhat smaller than the external. diameter of the .nib 18 z and of vsuch .thickness that :it .cQntacts-the top of the znib, leaving :the :bottom} of thedisc slightly .ahove the top :of the easingilfi. .During: .the \downward Tforcingrmovement, the; force .-is exerted :from the press I plunger through -;the disc 22-: and its boss .25 directly -.on to :th'e'mib :so-that :the -metal fOf the .top ;portion .of @the perip-her=al Wall .of ithe easing be zfree to" flow inwardly toward the "boss. i'lihus, the forging or drawing p-f the" easing 46-. of the dieis'by :downward pressure-applied 'onithe nib-*instead 'iof 011217118 casing,1and?by';the action-of the :taperrof ithessleeve d3 nonithecouter -surface of said casing.

of the newly inserted die casing and nib. The press plunger then descendsand the parts will be in the position-shown in Fig. 3. During the downward movement of the press plunger, the 'pressure is applied on the upper disc and transmitted therefrom to the nib' of the upper die and from the bottom of the upper 'die to the next disc and on to the lower die. When the plunger reaches thelower end of its stroke, the die which was first inserted, together with ,i.the disc resting thereon, drops out of the forming die. The drawing die is thus completed, as shown at the bot- "which may "vary in internal diameter. 'spacer'or 'disc '2'2 presentsa flat upper surface so tom ,of Fig. 3, and the disc 22 may be returned for or spacers 22 are required and the drawing dies :may :be:manufactured as rapidly as the press plunger can be ,reciprocated with the assemblies of casing'and-nib fed beneath the plunger when.

the latter is at the upper end of its stroke and the finished drawing dies removed from beneath the forming die when the plunger is at" thelower end of its-stroke. Y

By means of my improved process, the speed of manufacture is greatly increased and uniform drawing dies are produced regardless "of any slightvariations in the spacing between 'the-ex- 'terio-r of the nib and-the interior of the casing 16 at'the time they areassem bled. "The taper of the sleeve l3 will'forcethe metal into leave 'will force it in to impart the desired pressure --against" the niband any-excess or-metal willffiow the casing m6 of uniformexternal diameter "and across the top of the nib to form a narrow'flange 'Ihe that during the "forging operation, the 'underside of the drawing die being manufactured'will re- "main fiat and Jany tendency "of this surface-mo rassembly itherebeneath, and means for forcing .-said spaced assemblies. through said vtapering;pas-

sage -to thereby reduce the .external' diameter eaof ;the i casing of the drawing die, force the ,inner .The lpress plunger 'has substantiallyreached bulge due to thei'nward "forcing of the peripheral wall of the casing -v'vil1 be*prevent:d;

Having thus described: my invention, TI

-cl'aim:as new "and desire to' secure byFLettersiBa'texit is:

1. An apparatus forforming'ilirawing iiiesrim rcluding a. hard sleeve having raitaperingxpassage .reeuse. 'Thus,-only'a small number of the discs therethrough, a :spacer movable "through :said

"passage -for ,separating-gsuperposedidrawing :die assemblies, .each -;consisting of 5a mib sand :apasing therefor; saidspacerengaging the: nib of the surface of said .last. mentioned casing into aholding .and 1 supporting engagement; with said nib and -:to discharge the vassembly from -.the smaller .end-of the passage.

.t .2. An apparatus. for .forming .drawing dieslin cluding a steel casing, a tungstencarbide sleeve .th.er.ein,,.and having a taperingpassage therethrough, .a .spacer .movable through said passage ior separating superposed idrawing Idie .assemblies,.each consisting oia nib'landacasingthere- .for, saidspacer-en iging ithe'lbottom .of. the easing of the superposed. assemblyand only thegtop of thelnib of .theassembly below,..and .a press plunger .for forcing said .spaced .asserriblies through said taperingpassage .to. reduce theexternal diameter of .the casing -of-said drawing dies duringmovement through thessmallenporjtion of said passage.

I 3. .An apparatus ,tor forming ,drawingwdies ineludin a steel casing, a'hardsleeve..therein,,5and having a tapering, passage 'therethrough, aspacer movable'through said passage for separatingsu perposed drawing die assemblies, eachconsisting of a nib and a casing therefor, said spacer having a boss for engaging thenib of the assembly therebeneath and a press plunger for forcing said spaced assemblies 1 through said tapering passage to thereby reduce the external diameter of the casing of the drawing die, force the inner surface of said last mentioned casing into firm holding and supporting engagement with said nib and to discharge the assembly from the smaller end of the passage;

4. The processof making a drawing die, which includes applying pressure against one end of a nib istheld firmly seated on said shoulder while the peripheral wall of said casing is being forced inwardly into firm engagement with the periphcry of the nib and while a portion of the Wall of the casing above the nib is free to flow inwardly above the first mentioned end of the nib.

5. The process of making a drawing die, which includes applying pressure against one end ofa tungsten carbide nib which has its opposite end tungsten carbide nib which has its opposite end seated on a shoulder in a tubular casing of high tensile strength, to thereby directly force the nib and cause the nib to force the casing through a tapered passage in a forming die, whereby the seated on a shoulder in atubular casing of high tensile strength, to thereby directly force the nib and cause the nib to force the casing through a tapered passage in a forming die, whereby the nib is held firmly seated on said shoulder while the peripheral wall of said casing is being forced inwardly into firm engagement with the periphery of the nib. y i

it MORRIS SIMONS. i

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