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Publication numberUS2902364 A
Publication typeGrant
Publication dateSep 1, 1959
Filing dateSep 19, 1957
Priority dateSep 19, 1957
Publication numberUS 2902364 A, US 2902364A, US-A-2902364, US2902364 A, US2902364A
InventorsDeutsch Alexander T
Original AssigneeDeutsch Alexander T
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of forming particulate material
US 2902364 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

Se t. 1, 1959 I A. T. DEUTSCH 2,902,364

METHOD OF FORMING PARTICULATE MATERIAL Filed Sept. 19, 1957 2 Sheets-Sheet 1 & {NW

% r 5 T i 8 F? M w I V 11 I I Q A/exanaer raw/$6 l1 7 INVENTOR ATTORNEYj Sept. 1, 1959 A. 'r. DEUTSCH 2,902,364

METHOD OF FORMING PARTICULATE MATERIAL Filed Sept. 19, 1957 2 Sheets-Sheet 2 INVENTOR ATTORNEY5 United States atet 2,902,364 METHOD.OF FORMING PARTICULATE MATERIAL terials' which are in a powdered, particulate or generally subdivided state.

' During the past twenty years'the technology of powder metallurgy has undergone a rapid and increasingly accelerated growth until, at the present date, a large volume of metal parts is manufactured by powder metallurgy techniques. Sintering is undoubtedly the most widely used of these techniques and is based upon two basic phenomena. The first is that finely divided metal powders willbond together weakly when compounded at high pressure; and the second is that such compacted powders will bond together strongly when heated to relatively high temperatures under controlled conditions. '=-In a conventional sintering process of this type, the metal powders are blended ormixed in a tumbling barrel and then transferred to either a briquetting or a continuous extrusion press. ess; the powder is introduced into a die and is compacted therein at a pressure on the order of 30 tons *per square inch. The formed object is then removed -firom the press'more or less in a fragile state and is introduced into a'sintering furnace which may operate at t a temperature of around 2000 F. under a reducing atmosphere to reduce theoxides present in the compact as-well as preventtheir formation. In addition to being applicable to-metals, such. sintering processes are also useful with the so-calledcermets which are aggregate "structures of hard and refractory substances bonded with "metal.

In a typical impact press proc- A sinteringprocessofthe foregoing type is disclosed in United States Patent No. 2,289,787 which utilizes a combined compacting and extruding ram for forming a r solid, self-sustaining rod which is thence fed to some suitable-heating device for producing the desired sinter- 1 ing temperature.

shows :aprocess of asimilar typewherein the compacting and extruding pressures are separately applied.

United States Patent No. 2,447,129

T he density of the articles which can be produced by the foregoing sintering process is limited and any improvement in this density necessitates additional method --steps such as re-pressing or coining. Some metals, however, such as uranium, are not improved by these addi- --.-tional*steps and thus cannot be conveniently handled by sintering'processes of the foregoing general type.

I have now found that it is possible to produce improve'dmetal and ceramic objects from powders, pellets, chips or other particles without the aforementioned additio'nal steps in a basically different manner. According to my invention, the material particles are compacted or compressed in the same general manner as is customary P in-the conventional powdered metal forming and sintering processes, except that the extremely high pressures used in thoseprocesses are not necessary. That is to 1 say, my process does not depend upon the initial weak bond produced by the high pressures of previous processes, and I only desire to secure a reduction in volume of about /6 at this stage of my process. Instead of then extruding and/ or sintering, I subject the compacted particles in an unheated state to a forging or pounding action to cause a reduction or refinement of particle size.

Subsequent to the start of this particle reduction step, I

\ direct radiant energy, such as heat or high frequency radiation, into the mass of particles which causes diffusion to occur at the individual particle interfaces.

The

2 material then assumes an extremely dense, condition and may be extruded or molded to form metaland ceramic objects having qualities of a vastly improved nature. By diffusion I refer to the diffusion of atoms from one particle into its adjacent particle as that term is understood by those skilled in the art and as is explained, for example, in Scientific American,'May 1957, pages, l03110.

It is accordingly a primary object of the present invention to provide an improved process for producing metal or ceramic parts from subdivided or particulate materials.

It is another object of the invention to, provideqan improved process for producing metal or ,CQramicparts from subdivided or particulate materialsrwhich includes the steps of compacting the subdivided material, reducing the size of the particles of such material, and causing diffusion at the contacting interfaces of adjacent, particles of the material.

These and further objects and advantages of the invention will become more apparent upon referenceto the following specification and claims and appended drawings wherein:

Figure 1 is a vertical cross section showing one. embodiment of a device for performingthe process of the invention;

Figure 2 is a vertical section of another, embodiment of an apparatus for performing the process of the. invention;

Figure 3 is a vertical elevation of still another embodiment of an apparatus for performing the process of the invention;

Figure 4 is a photomicrograph of a compacted metal; and

Figure 5 is a photomicrograph of a metaLcompacted, forged and diffused according to the invention.

' The particles used in the. process of the invention may be particles of metals, mixtures of metals, ceramics, mixtures of ceramics or cermets, and may be in the form of fine powders, chips or pellets. The particles are cleaned in any suitable manner to remove oxidation or other impurities upon their surfaces and this may conveniently be accomplished with hydrogen at a temperature of about 1000 F. in a known manner. The particles are thereafter preferably maintained in a controlled atmosphere such as inert gases or a vacuum to prevent further oxidation as is understood by those skilled in the art. This controlled atmosphere may be advantageously maintained throughout the process. The compacting step is then carried out by a light hammering to produce a reduction in volume of about /6. The precise manner of pressure application and the specific pressures used are not critical so long as the initial reduction in volume of about /6 is obtained. This compaction causes the finely divided metal powders to bond together weakly in the same general manner as does the compaction step in conventional sintering processes and produces a structure illustrated in the photomicrograph shown in Figure 4. This photomicrograph is also illustrative of the type structure obtained in the compacting step of conventional sintering processes. It is to be noted that this. structure is relatively porous and, generally speaking, it is impossible to completely eliminate this porosity through the application of practical amounts of increased pressure.

According to the next step of the process of my invention, the crystals or particles are refined or subdivided along their glide lines and I have found that this may be efiectively accomplished by hammering. The desired refining or subdivision of the particles may be obtained by hammering the compacted material with a 250 lb. hammer with a face of about 1 square inch which achieves a maximum velocity of 30 ft. per second and is reciprocated at about 5-30 hammer strokes per minute. Each stroke produces a maximum energy of approximately 3460 ft.-lbs. and produces a new structure which is illustrated in the photomicrograph of Figure 5. It is to be noted that the particle size has been greatly reduced from that which existed in the compacted structure of Figure 4 and that the individual particles are in much more intimate and close contact with one another.

The temperature of the mass undergoing the hammering is now raised to a value several hundred degrees below the melting point of the powder having the lowest melting point in the material and the hammering continued. The heat causes an accelerated diflusion at the interfaces of the particles and the volume of the mass is reduced to about of its original volume. The heat may be applied through combustion, heated fluids, induction heating, or other radiated types of energy such as infra-red or ultrasonic sound. In its broadest aspect my invention comprehends the introduction of energy into the material to cause this accelerated diffusion regardless of the manner in which such energy is introduced or its precise nature. When the material reaches a volume about of its original volume, it is cooled to form a high quality dense product with excellent physical characteristics. The initial compaction and at least the beginning of the forging step are carried out with the material unheated. In order to prevent the material from welding to the die, the internal surface of the die may be coated with resin as shellac.

As one example of a metal extrusion produced according to the process of the invention, high quality steel parts have been formed having a yield strength of 200,000 p.s.i. These parts were formed using 37.5% Hoeganes W/428 sponge iron powder, Tyler mesh plus 62 to plus 200, density 2.8 gms. per cc.; 3% fine mesh copper; 1.5% oxygen absorbing aluminum, 20% nickel, 20% chromium, 18% cobalt. This material was compacted in a die under relatively light hammer blows until the volume of the material was reduced by /6. Hammering then was commenced at a rate of strokes per minute at approximately 3,000 ft. lbs. of energy per stroke. The temperature of the mass in the die was raised to 1100" F. through induction heating and the volume of the mass finally reduced to about of its original volume in between two and three minutes. The material was then air-cooled and removed from the die and exhibited a yield strength of 200,000 p.s.i.

According to another example of the process of the invention, a powder consisting of 35% electrolytic iron, aluminum, 30% nickel, 10% manganese, 5% copper and 5% zinc was subjected to the same process and also produced excellent specimens.

According to still another example, small chips produced in the milling of structural steel and aluminum were shaped into high density parts, having strengths equal to the original strengths of the material, at temperatures of 1100 F. and 800 F. respectively, the other steps in the process being the same as set out hereinbefore.

Referring to Figure 1 of the drawing, there is shown a vertical section of an extrusion press which may be used in carrying out the process of the invention. An extrusion press chamber 10 having a nozzle 12 at one end thereof is abutted by a movable stop plate or gate 14 having a suitable actuating rod 16. The stop plate or gate 14 is backed up by an aperture plate 18 which is stationarily mounted to hold the stop plate or gate against pressure created within the extrusion chamber. An inlet hopper 20 is provided at the top of the extrusion chamber and suitable heating passages 22 are provided within the chamber and nozzle walls. The extrusion chamber is mounted on a suitable standard 24 on a base 26.

The other end of the base 26 carries an extrusion cylinder 28 in which an extrusion piston 30 is received. The extrusion piston 30 is reciprocable in cylinder 28 and may be moved leftward by means of a suitable fluid introduced in the cylinder through an inlet aperture 32 at the right end of the cylinder. The left end of the extrusion piston is bored at 34 and receives a forging piston 36 which is mounted for reciprocation. Fluid passages 38 and 40 provide communication between the bore and a three-way valve 42 which connects these passages to a fluid supply 44. By suitable actuation of the valve 42 the piston 36 may be made to oscillate in a known manner. The outward end of the piston 34 carries a piston head 46 which may be made heavy enough to provide the hammering energy desired.

Mounted parallel to the extrusion piston 30 are a pair of return cylinders 48 and 50 which carry pistons'52 and 54 and which are connected to the extrusion piston 30 by means of piston rods 56 and 58 and cars 60 and 62. Suitable fluid connections for the return cylinders are provided at 64 and 66, 68 and 70.

The operation of this embodiment of the invention is as follows: The stop plate or gate 14 is closed and a clean powdered material such as powdered metal is introduced into the extrusion chamber 12 through the hopper 20. Fluid passage 40 leading to bore 34 in extrusion piston 30 is opened and fluid introduced into the extrusion cylinder 28 through the inlet 32. This causes the extrusion piston 30 to move to the left thereby compressing the powdered metal introduced through the hopper 20. The piston head 46 moves to the right until the rear end of the forging piston 36 strikes the end of the bore 34. Since the stop plate or gate 14 is closed it is possible to compact the powdered metal under the desired high pressure. After this has been accomplished, the extrusion piston 30 may be withdrawn to the right for a slight distance through actuation of cylinders 48 and 50 and fluid pressure applied to the back of forging piston 36. By repetitive actuation of the forging piston control valve 42, the piston head 46 is caused to strike repeated blows against the compacted powder. By controlling the weight of the piston head 46 and its piston 36 and the pressure of the fluid introduced into the forging piston bore 34, it is possible to obtain the desired energy in the impact of the hammer in order to reduce and refine the size of the particles of material.

After forging has been commenced heat is introduced into the extrusion chamber through the heating conduits 22 and the temperature of the mass raised until the diffusion occurs at the particle interfaces. After this state of the material has been reached, the stop plate or gate 14 may be raised and the material extruded through the nozzle 12 by introducing further fluid behind the extrusion piston 30. It will be understood that once the process has been performed the nozzle 12 will contain cold hard metal which will seal the press for the next compaction so that the gate 14 is thereafter unnecessary.

Referring to Figure 2, there is shown another embodiment of the invention in which the compacting and hammering or forging may be effected by means of the same piston. In this embodiment of the invention the extrusion chamber, nozzle, stop plate and hopper are the same as in the preceding embodiment of the invention and thus bear the same reference numerals. Induction heating may be used with this embodiment of the invention and thus the heating channel 22 of Figure 1 has been eliminated. According to this embodiment an extrusion piston cylinder 72 is connected to the extrusion chamber 10 by means of suitable flanges and bolts, indicated at 74, and carries a piston 76. The piston 76 is milled away at 78 to form a reduced diameter section and this communicates with a fluid supply conduit 80 through an aperture 81 in the piston cylinder wall. A second conduit 82 is connected to the back of the cylinder 72 through an aperture 84, and conduits 80 and 82 are connected to a suit- ;able control valve 86.

A further inlet 88 is provided at the rear of the cylinder 72 for supplying the fluid which applies the high compacting and extrusion pressure. A suitable guide rod 90 extends through the rear of the cylinder 72 through suitable packing means. It will be apparent to those skilled in the art that hydraulic fluid can enter the cylinder 72 through conduit 88 to force the piston 76 to the left to compact the powdered material; that this hydraulic fluid can then be exhausted from the cylinder by moving the piston to the right under control of fluid from conduit 80; and that the piston 76 can be oscillated or reciprocated through suitable actuation of the valve 86 to cause a hammering of the compacted material. Hydraulic fluid can then be reintroduced through conduit 88 to extrude the material from the extrusion compartment 10.

Referring to Figure 3, there is shown a further embodiment of the invention comprising a vertical press suitable for carrying out the process. According to this embodiment of the invention, the lower cylinder 96 is mounted in a stand 98 having an upper flange 100. The cylinder 96 carries a back-up piston 102 which extends through (the flange 100 into an extrusion die 104 and which is supported by fluid which enters through a port 105. The extrusion die 104 is secured to the flange 100 by means of a [flange 106 and contains an extrusion chamber 108 which receives the upper end of the piston 102. The die may be of the split type which is openable to permit removal of the piece formed therein. A suitable induction heating coil 110 is mounted about the extrusion die cavity and is connected to a suitable source of high frequency induction heating power. A smaller bore 112 extends out of the top of the extrusion die and receives the end of an upper piston 114. Suitable packing 116 and 118 is provided in the die in a conventional manner.

The upper piston 114 is carried by the upper piston assembly 120 which rests upon standards 118 on flange 100. Assembly 120 is mounted on standards 118 by means of a lower flange 122 through which a hollow ram 124 extends. The ram 124 passes through packing 126 in the flange 122 and through packing 128 at the upper end of a cylinder 130 which is mounted on the flange 122. A piston head 132 is provided about the ram 124 in the cylinder 130 for movement of the ram under the influence of fluids introduced into the cylinder 130 through apertures 134 and 135. A pair of return cylinders 136 and 138 are mounted at either side of the cylinder 130 and have pistons 130 and 132 mounted therein and connected to the ram by brackets 144. Apertures 145 in cylinders 136 and 138 provide hydraulic connections for raising the cam 124.

The upper piston 114 extends into the ram 124 and carries a stop flange 146 which abuts the lower end of the ram 124. The upper end of the piston 114 is connected to a piston head 148 which is received within a cylinder 150 mounted atop the upper piston assembly 120. Conduits 152 and 154 connect this piston to a valve 156 and fluid supply 158 for reciprocating the piston head 148 and piston 114.

The operation of this embodiment of the invention is as follows: A suitable powdered material is introduced into the split die 104 on top of the lower piston 102. The upper ram 124 is then moved downwardly by fluid pressure introduced in back of piston head 132 and this carries the piston 114 downwardly by reason of the abutment of flange 146 against the lower end of the ram 124. Compaction of the powdered material is carried out in this manner to the desired degree. The upper ram may then be maintained in this position by means of fluid pressure in cylinder 130, or other positive locking means, and the piston 114 caused to reciprocate by means of actuation of the valve 156. This creates the desired hammering or forging and heat may be introduced by the induction heating coil 110. When the forging step 1s completed, the piston 114 may be withdrawn from the die by appropriate actuation of valve 156, and the piece removed from the die.

While specific presses have been described herein, rt

be understood that this has been by way of illustration only and is not meant to be limiting in any respect. That is to say, the process of my invention may be carried out in conventional presses or may be carried out with the newer presses designed to handle the newer high temperature alloys. Since my process involves heating the material to within a few hundred degrees of its melting temperature, it is obvious that the presses utilized must be capable of withstanding such temperatures. Similarly while the process of the invention has been described in terms of forming specific articles, it is not limited to this but may be used for other purposes, such as forming a layer of one type of metal upon another, or similar uses. Again, while the injection of energy into the material in order to cause accelerated diflusion has been primarily discussed in terms of heat, it is to be understood that the invention also encompasses and includes the addition or injection of atomic or nuclear energy derived from radiative isotopes or other sources in order to accelerate difiusion. The acceleration of diflusion is one of the basic steps of my process and the invention comprehends all methods of energy addition or injection which have this effect.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

This application is a continuation in part of my copending application Ser. No. 603,421, filed August 10, 1956, now abandoned.

What is claimed and desired to be secured by United States Letters Patent is:

1. The method of forming particulate metallic material comprising compacting said material and performing on said compacted material the continuous sequential steps of impacting said material in a substantially cold state to cause a refining of the particle size, introducing into said material as said impacting continues controlled heat energy other than friction heat, and continuing said impacting and the introduction of said heat energy to cause accelerated solid diflusion at the interfaces of the refined particles and a reduction of the volume of the material, the introduction of said heat being controlled to maintain the temperature of the mass below the melting temperature.

2. The method of forming particulate material according to claim 1 including the additional continuous sequential steps of extruding said material.

3. The method of forming particulate material according to claim 1 wherein said impacting is carried out while said material is maintained in a confined space.

4. The method of forming particulate metallic material according to claim 3 including the additional continuous sequential step of extruding said material from said confined space.

5. The method of forming particulate metallic material according to claim 4 wherein said material is extruded through a die.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Goetzel: Treatise on Powder Metallurgy, vol. 1,

PP- 306-312, 459, 460. t

STATES PATENT OFFICE UNITED CERTIFICATE OF CORRECTION September 1, 1959 or appears in the prints d Letters certified that err ered patent requiring correction a d that the sai s corrected below.

It is hereby of the above numb Patent should read a line 72, for

Golinnn 1, line 25, for "impact" read compacting "particle read particles Signed and sealed this 19th day of Januaryil960,

\ (SEAL) Attest'.

) ROBERT c. WATSON 1 KARL H. .AXLINE Attesting Ofiicer Commissioner of Patents Patent No. 2,902,364

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION September 1, 1959 Alexander T, Deutsch It is herebfi certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Colinnn 1, line 25, for "impact" read compacting line '72, for "particle" read particles Signed and sealed this 19th day of Januaryll960.

(SEAL) Attest:

KARL Hm AXLINE Attesting Officer ROBERT C. WATSON Commissioner of Patents

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1989186 *Oct 5, 1932Jan 29, 1935De Bats Jean Hubert LouisMethod of forming rolls
US2343978 *Jul 1, 1940Mar 14, 1944David Jones WilliamManufacture of nonporous metal articles
US2358667 *Dec 3, 1941Sep 19, 1944Max SternMethod for the production of shaped articles such as tubes, rods, and profiles from magnesium and magnesium alloy scrap
US2372607 *Nov 23, 1940Mar 27, 1945American Electro Metal CorpMethod of making layered armors
US2386604 *Oct 30, 1943Oct 9, 1945American Electro Metal CorpMethod of molding under pressure metallic powders
GB716473A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6547550Jun 16, 2000Apr 15, 2003Ross GuentherApparatus for hot vacuum extrusion of ceramics
US7704907Aug 25, 2005Apr 27, 2010Ceramext, LlcSynthesized hybrid rock composition, method, and article formed by the method
US8216955Apr 26, 2010Jul 10, 2012Ceramext LlcSynthesized hybrid rock composition, method, and article formed by the method
US8901023Jun 1, 2012Dec 2, 2014Ceramext, LlcSynthesized hybrid rock composition, method, and article formed by the method
Classifications
U.S. Classification419/30, 419/41
International ClassificationB22F3/20
Cooperative ClassificationB22F3/20
European ClassificationB22F3/20