US1993774A - Centrifugal casting of carbide and like materials - Google Patents

Description

' March 12, 1935.

, J. H. L. DE BATS CENTRIFUGAL CASTING 0F CARBIDE AND LIKE MATERIALS Filed Jan. 18, 19:52

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Patented Mar. 12, 1935 UNITED STATES PATENT OFFICE E MATERIALS Application January 18,

Jean Hubert Louis De Bats, East Orange, N. J.

1932, Serial No. 587,243

14 Claims. (01. 22-203) This invention relates to new and useful improvements in the methods of applying reacted or unreacted wear-resisting facing materials, such as tungsten carbide alloyed or bonded with cobalt, iron, nickel or like alloying or bonding metal or material, or wear-resisting alloys or compositions generally, sintered or not, to extrusion and forming dies, as well as to articles generally that require some portion thereof to be wear resistant or forming alloys in place. The invention also pertains to the improved articles so prepared and to the apparatus'for applyin a the wear-resistant materials.

. More specifically, the present invention relates and the alloying step completed by the subjection of same to a suitable temperature such as secured from an electric arc or by suitable resistance members, or yet again by high temperature gas flames such as oxyhydrogen, oxyacetylene and other like sources of high heat or temperature. The temperature and amount of heat imparted to the materials used may, as indicated, be sufficient to cause a true alloying of the materials such as tungsten carbide alloyed with the metal of the group comprising iron, nickel and cobalt, or the temperature may be held below the alloying point and suflicient to cause a sinterin or bonding of the materials due to the softening of the lowest melting component of the mix under the low heat and relatively high pressure used. Where desired the invention comprehends the carrying out of this treatment in the presence of an inert gaseous atmosphere to prevent undesirable oxidations, particularly where the reactions are carried out in the presence of and by the aid of the electric arc.

Hitherto it has been proposed to form .or manufacture extrusion or forming dies or other articles requiring a high wear-resistant surface in a variety of ways, among which may be mentioned the melting of materials composed of chromium, tungsten, cobalt. vanadium, molybdenum, nickel, or other such metals, in a crucible, casting to shape and hardening, by heat treatment; also casting such materials onto a block, the finished die surface being machined or ground to the appropriate size in both instances. Yet another prior method consists in casting such molten carbides centrifugally onto the surface of a die.

This application is a continuation in part of my prior application Serial No. 549,702, filed July 9, 1931.

It is an object of the present invention to provide an improved process for attaching a wearresistant facing material to' tools and dies or other articles, some of the wear-resistant materials being compositions high in carbide content, or being alloys or other compositions.

It is also an object of this invention to provide such an improved process in which the facing material is centrifugally forced onto a backing and to have the material heated while the process is being carried out.

Another object of this invention is the provision of an improved process in which a wearresisting surfacing material is applied to a die or tool in powdered form and then fused in place.

Yet another object of this invention is the provision of an improved process in which a wearre'sisting facing material is applied to a die or tool in powered form and then fused in place while centrifuging the articles treated, whereby to compact the facing.

A further object of this invention is the provision of an improved process in which a wearresisting facing material mixture is applied to a die or tool in powdered form and then fused in place while centrifuging the articles treated whereby to simultaneously cause alloying of the said components of the mix and a compacting of the so-formed facing material.

Another object of this invention is the provision of an improved process in which a wear-resisting facing material mixture is applied to a die or tool in powdered form and then heated in place while centrifuging the articles treated to a temperature at least sufficient to cause sintering of the mass.

A further object of this invention is the provision of an improved process in which a wearresisting facing material mixture is applied to a die or tool in powdered form and then heated to a temperature sufficient to cause the lowest melting component of the mix to be uniformly disparatus here shown, except as such limitations are clearly imposed by the appended claims.

compacted wear-resisting material in place, and

I showing the finished surface of the wear-resisting materials.

Referring more specifically to the drawing, the centrally apertured die block 10 is provided on its inner surface with a plurality of channels or serrations 11 which are adapted to receive a molded wear-resisting facing material 12. This material may comprise a completely reacted alloy formed from tungsten carbide, in suitableamounts, and a metal of the group comprising iron, nickel or cobalt, or the material may be made up of the unreacted components of said alloy which is subsequently heated to an alloying temperature, or otherwise treated, as

, will be described more in detail hereinafter. The

forming or extrusion die block ispreferably machined to an inside diameter which will receive the amount or thickness of a facing 12 which may be of tungsten carbide alloyed or bonded with cobalt, iron, nickel or like alloying or bonds ing metal or material, or other wear-resisting materials, as may be desired. In the preparation of the finished die or valve seat or other article with a wear-resisting facing, as comprehended therein, preferably inhigh percentages, tungsten carbide alloyed with or bonded by cobalt,

iron, nickel or like alloying or bonding metal or material, tantalum, carbide, similarly alloyed or bonded, including metals and/or alloys, or other materials having high wear-resisting qualities, and is molded, in a suitable state of fineness, and compressed. into and upon the die block 10 in such manner as to present a substantially smooth'wearingsurface 13. The invention also comprehends, as above intimated, the use of completely reacted alloys of tungsten carbide with a metal of the group comprising iron, nickel and cobalt, which alloys may be prepared in a suitable state of fineness and applied to the tool or die surface inany desired manner and shape and thereafter remelted and compacted. It will alsobe appreciated that other high melting compsitlons,.such as alloys or compounds of tentalum, molybdenum, etc., may be applied in the msnnerand form designated. j I The die block with its adherent facing material 12 is inserted in a rotary mold comprising adishedcasingi4havingaflangel5adapted toreceive bolts 18 for attaching a cover 17 thereto. The cover is provided with a central aperture 18 inalignment with a similar aperture 19 in the bottom 20 of the casing. This bottom portion is provided with an integral, internally threaded boss 21 adapted to receive threaded shaft 22 mounted for rotation in bearing 23. A driving pulley 24 is secured to the shaft 22- and is provided with suitable driving means such as a belt 25 connected to a suitable source of power,

- not shown. The die block 10 is spaced from the walls of the mold 14 by any desirable insulating material, such' as blocks 26, of magnesia, which are cut to the requisite size toprovide a' support for the die block and to maintain it insulated from the mold casing, and also tohave its longitudinal axis coincide with that 01 the aligned apertures 18, 19 above described, as well as the aligned apertures 27, 28 formed in the magnesia blocks disposed at the top and bottom of the die block.

The facing material 12 is heated to adesired degree by means of an arc 29 fed by a current of suitable amperage and having a temperature of the order of 3000 to 3600 C., as formed between electrodes 30 and 31 passing through the apertures in the cover and the bottom of the mold, the bottom oi! electrode 31 also passing. through the hollow shaft of the centrifugal mold assembly. The electric arc may bemaintained close to the surface to be heated to insure maximum reaction temperatures, or it may be moved away from suchsurface to a desired distance to decrease the defective temperature at such surface. The details of the apparatus for obtaining these desired conditions will be described in detail hereinafter.

The operation is preferably carried out in the presence of hydrogen or other inert gases to prevent excess oxldization. The electrodes preferably are held in aligned relation by means of clamps 32,33 which are provided with arms 34,

35 adapted for sliding engagement in the clamps 36, 37, where they may be maintained in locked or fixed position by means of the nuts 38, 39 respectively. Suitable electrical conductors 40, 41 are secured. to the conductive clamps 32, 33 by means of rivets or bolts 42, and these conductors may be connected to any suitable source of power such as a generator, not shown. 1

To permit the adjustment of the arc in any direction with respect to the inner die face 12, the following apparatus may be made use of. A yoke 43 having side arms 44 and 45 is provided with connecting arms 46, 47 which form a substantially continuous member slit at its middle, the' said members respectively provided with racks 48 and 49 adapted to engage a pinion gear 50, the whole being mounted in a movable sheath member 51 and adapted for sliding movement therein, the amount and direction of such movement being controlled through the racks and pinion gear, which latter is in turn controlled by the hand-wheel or control member 52. The sheath-51 is provided with a rack 53 adapted to enmesh with and be moved by the gear 54 movable with shaft 55. The gear 54 and shaft 55ers mounted on a lug 56 connected to and integral with a yoke 57 which is provided at the extremities of its arms with. suitable bearings 58 with which the sections 46 and 4'1 0? yoke 43 are adapted to move. The bearings 53, together with the sleeve 51, form supports for the arms 46 and;

47 and preventtheir non-linear movement. The yoke 57 is adapted to be moved laterally in or out and for this purpose a member 59 is secured thereto and. connected to a screw. 60 which .is provided with a control 61, the said screw being suitably mounted in a standard 52. Upon operation of the control 61 the yoke 57 is moved toward or" from the standard 62 which is of suit- .able size and strength to support the yoke 43 and associated apparatus. This inward and outward -movement of the combined yoke assembly will cause the electrode holders with the associated electrodes to move awayfromor toward the die is"? i and allowing the deposit of compacted material upon the inside face of the die to be made up to any desired thickness, while at the same time producing uniformity of the "deposited alloyed, bonded, sintered or cemented tungsten carbide compositions or other wear-resisting materials, and producing a wear-resisting facing which, at

the utmost, will require but slight grinding and polishing or lapping to acquire the exact size of. aperture desired.

The improved dies and.other articles having compacted cemented, sintered or fused wear-resisting facings resulting from this treatment not only have a longer life, but are more easily and .economically formed, due to the fact that sepform, as well as wear-resisting facings generally for other articles, which dies and other articles are characterized by certain novel features of construction adaptingthem for the more perfect carrying out of their useful functions and being, at the same time, endowed with a longer operative life and also being susceptible of formation at relatively low costs. In addition, there has been disclosed a novel apparatus for securing the desirable results of this invention.

While the invention herein is disclosed inone or more forms, it is to be understood that various changes and modifications may be made, but such changes or modifications come withinthe spirit and scope of the invention as defined in the claims hereof.

Reference is made to my co-pending applications Serial Nos. 587,244 and 587,245, Patent No. 1,939,768 of December 19, 1933, both cases being filed January 18, 1932, and which respectively cover the apparatus andarticle disclosed in this application.

What is'claimed is:

1. The method of applying high wear-resisting refractory materials in compacted form to extrusion and forming dies and like articles comprising directly heating'at a temperature of substantially 3400-3600 C., a mass of such materials in place on a die while rotating the latter at such speeds and in such manner as to cause centrifugal compacting of the said materials.

2. The method of applying high wear-resisting refractory materials in compacted form to extrusion and forming dies and like articles comon extrusion and formingdies, valve seats, and

other like apertured articles, comprising reacting a compacted alloyable mix of such materials in place on a die, while rotating the latter.

- 4;. .The method of applying tungsten carbide throughout the inside circumference of the die.

bonded by cobalt, iron; nickel, and like bonding metal or material and like wear-resisting, refractory materials in compacted form to extrusion and forming dies, valve seats, and other like articles, comprisingdirectly heating a mass of such carbide materials in place on a die to a sintering temperature while rotating the latter.

5. The method of applying tungsten carbide bonded by cobalt, iron, nickel, and like bonding metals and like wear-resisting, refractory materials, in compacted form, to extrusion and forming dies, comprising directly heating at a tem- .perature of substantially 3400-3600 C. a mass of such carbide materials in place on a metal die, while rotating the latter at high speed.

6. The method of applying tungsten carbide bonded by cobalt, iron, nickel, and like bonding metal and like wear-resisting, refractory materials to-extrusion and forming dies, .valve seats, and other like articles, comprising compressing a powdered mass of high carbide composition into a die, and rotating the die about its central axis while subjecting the said mass to direct radiant heat produced by radiation of an electric are operating at a temperature of about 3400-3600" 0., whereby to compact the sintered mass.

7. The method of applying tungsten carbide bonded by cobalt, iron, nickel, and like bonding metal and like wear-resisting, refractory materials as facings to extrusion and forming dies and the like, comprising compressing a powdered mass of said bonded carbide into a die, rotating the die about its central axis, and subjecting the said mass to the direct heat produced by the action of an electric are operating at a temperature of about 34003600 0., whereby. to compact the heated mass.

8. The method of forming tungsten carbide alloyed with a metal of the group comprising cobalt, nickel, iron, as facings on extrusion and forming dies, valve seats, and like apertured articles, comprising compressing anunreacted mass of said carbide and auxiliary alloyable metal into a die, rotating the die about its central axis, and subjecting the said mass to the direct heat produced by the action of an electric arc, whereby to react the materials to form a wear-resisting alloy and to simultaneously compact theso-formed alloy.

9. The method of forming fused wear-resisting, refractory facings on extrusion and forming dies, comprising compressing a powdered mass of a material having the wear-resisting characteristics of tungsten carbide bonded by cobalt, iron, nickel, and like bonding metals into shape on a die block, mounting the so-surfaced block,

in a rotary machine adapted" to rotate at high speed, rotating the machine, and directly heating the material to a sintering temperature by means of a source of high heat positioned centrally of the die and adapted. to be varied longitudinally and eccentrically of the axis thereof.

10. The method of forming wear-resistant alloy facings on extrusion and forming dies and other apertured articles, comprising compressing an unreacted mix of tungsten carbide and an alloyable metal of the group comprising cobalt, iron, nickel, into a desired shape on a die block, mounting the so-surfaced block in a rotary machine adapted to rotate at high speed, rotating the machine, and progressively and directly heating the material to an alloying temperature by means of a source of high heat positioned interabove, imparts like movement to the electrode holders 36, 37 which are respectively secured to .the ends of the said arms 44 and 45 and which are so arranged as to maintain the carbons in aligned relation. The distance between the electrodes may be varied by unscrewing the nuts 38 and/or 39, and after adjusting the arc, securing them to permit of a fixed separation of the carbonswith the definite determined arc distance therebetween. The screws 38 and 39 may be replaced by suitable gears adapted to enmesh with suitable racks formed on members 34 and 35 to permit a desired adjustment of the length of the arc. The distance between the carbons may also be regulated by any other well known mechanisms not here shown. 7

It will be appreciated that the are 29 formed between the ends of the carbons may be raised or lowered within the mold by suitably rotating the gear 54 to effect upward or downward movement of the member 51, and in this manner the effective heat of ;the arc may be applied at any given height or position within: the 'mold. This feature, in conj unetion with thedateral movement of the are made available by proper adjustment of the control 61, permits the use of this device for large die and valve members as well as for small ones.

In the bonding, sintering, or alloying of a facing mix upon the die surfaces the requisite quantities of heat may be applied to such surfaces for the purposes desired by suitably adjusting the arc with respect to such surface and the condition of the surface material which is to be finally secured. This combination of apparatus features, as intimated above, permits the manufacture of large dies having wearing surfaces of any desired composition, which surfaces will be characterized by their substantially complete uniformity throughout their extent due to the unifo'rmity of treatment received by the materials from same.

In the operation of the improved apparatus herein shown, the mold 14 with the die 10 and the compressed facing material 12, mounted therein, are set in rotation at a desired speed, which may be varied substantially between 300-7200 R. P. M., as required for the particular article and the composition being alloyed, sintered, cemented or bonded thereto. An arc is then sprung between the electrodes, and the die-facing material is brought to a temperature to give it the desired consistency. By suitably spacing the are from the surface under treatment the materials may be heated to an alloying temperature, to a sintering temperature or to a still lower temperature at which the lower melting components of the mix are softened and compacted under the centrifugal pressures obtained.

It will be appreciated that by raising the facing material 12 to its softening or fusing point while rotating the mold at a relatively high speed, depending upon the thickness of the die facing,

the softened fused material will be reacted and.

the alloy formed will be forced into contact with the channels or grooves 11 of the die block, and

upon attainment of a sufficient degree of heat throughout the mass of the facing material, the reacted material will fuse to the said die block, and be compacted thereon. Due to the high centrifugal pressures, obtainable by suitably varying the speed of rotation of the die supports, the bonded or sintered materials will also be compacted in place without attaining a reacting temperature.

Where the materials have been initially alloyed and then reduced to a suitable state of fineness and applied to the die surface, or where the alloyed components have been mixed in a ground condition and applied as a mix to the die surfaces and thereafter heated in place to an alloying temperature, the rotation causes the low melting alloy components to be extruded toward the supporting surfaces of the die blank and at the temperatures involved, to react therewith to a greater or less degree, thus providing an improved integral bond between the die blank and the novel die surfacing. The extent of this interaction of the facing and the die blank materials will depend upon the constitution of the low melting components of the wear-resisting alloy, which in turn will depend upon the relative percentages of the high melting carbides or like materials used with the alloying metals of the group comprising cobalt, iron and nickel. This low melting material extruded from the alloy composition under the combined influences of heat. and centrifugal pressure not only provides a desirable means for providing an intermediate cushioning metal which forms a bond between the surfaces of the die blank and the wear-resisting surface, but also permits the segregation or concentration of the high wearresisting component of the alloy at the wearresisting surface of the die when the alloy mass has finally attained normal temperature.

To avoid causing the fused mass to collect at the end of the block having the largest aperture diameter, the arc may be initially positioned at such diameter, whereby to cause the facing or wearing material to be fused and centrifugally compacted and bonded to the block. By thereafter lowering or moving the arc toward the aperture of lesser diameter, this progressive movement being so adjusted and carried out as to permit the progressive fusing of the intermediate portions of the facing material, while at the same time permitting a slight cooling of the already compacted mass, whether fused or merely softened, the latter is enabled to act as a dam for the successively fused or softened masses or quanta of compacted facing material.

This progressive softening or fusing of the facing material is particularly desirable where the mold is to be run or operated at relatively high speeds, while, with lower speeds the arc may be so positioned and operated as to accomplish a substantially uniform softening, semi-fusing or,

fusing of the entire mass 12 of the facing material, whereby to bond, cement, sinter, or alloy the material, as may-be desired.

The progressive fusing of the facing material may result in the formation of a series of interbonded rings of compacted wear-resisting sub' stances which act as mutual supports and which, 1

due to their laminated structure, would prevent the propagation of any surface cracks or fissures from one edge of the aperture directly through to the other edge.

This method includes, among other advantageous characteristics, that of permitting an equal distribution of wear-resisting material 11. The method of forming wear-resisting facings on extrusion and forming dies, valve seats and other like articles, comprising compressing a powdered mass of tungsten carbidebonded by cobalt, iron, nickel, and like bonding metals into shape on a die to form a desired facing therefor,

' mounting the so-surfaced die in a rotary machine adapted to rotate at substantially high speeds,

directly heating the said surface material to a sintering temperature by means of an electric are positioned within the die and adapted to be varied laterally and longitudinally thereof, and rotating the said die at a desired speed to compact the resulting cementedfacing material.

12. The method of forming wear-resisting a1- loy facings on extrusion and forming dies, valve seats and other like apertured articles, comprising compressing a powdered mass of tungsten carbide and an alloyable metal of the group comprising cobalt, iron, nickel, into shape on a die to form a desired facing therefor, mounting the so-surfaced die in a rotatory machine adapted torotate at substantially high speeds, progressively and directly. heating the said surface material to an alloying temperature by means of an electric are positioned within the di e and adapted to be varied both laterally and longitudinally thereof, and rotating thesaid die at adesired speed to simultaneously compact the soformed alloy facing material.

13. The method of forming fused wear-resisting facings on extrusion and other apertured forming dies, comprising compressing a finely divided mass of tungsten carbide to form a die facing, mounting the so-surfaced die in a machine, rotating the machine at a speed of from substantially 300-7200 R. P. M., and fusing the said facing material in situ.

,14. The method of forming fused wear-resisting facings on extrusion and forming dies, valve seats ,and other apertured articles, comprising compressing a .finely divided mass of tungsten carbide to form a die facing, mounting the sosu'rfaced die in a machine, rotating the machine at a speed of-300 to 7200 R. P. M., and progressively and directly heating the so-compacted mass-to a fusing temperature by means of an are positioned within the aperture and adapted to be varied both laterally and longitudinally thereof,

whereby to simultaneously fuse and compact the said carbide facing material. 1

JEAN HUBERT LOUIS DE BATS.

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