US3785038A - Process of working a sintered powder metal compact - Google Patents

Process of working a sintered powder metal compact Download PDF

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Publication number
US3785038A
US3785038A US00217510A US3785038DA US3785038A US 3785038 A US3785038 A US 3785038A US 00217510 A US00217510 A US 00217510A US 3785038D A US3785038D A US 3785038DA US 3785038 A US3785038 A US 3785038A
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United States
Prior art keywords
blank
article
press operation
sintered
density
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00217510A
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English (en)
Inventor
G Zapf
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Sintermetallwerk Krebsoege GmbH
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Sintermetallwerk Krebsoege GmbH
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/16—Both compacting and sintering in successive or repeated steps
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S29/00—Metal working
    • Y10S29/047—Extruding with other step

Definitions

  • ABSTRACT A process of manufacturing articles by means of powder metallurgy, including the conventional steps of forming a blank out of metal powder compressing the blank and sintering it.
  • an additional step is provided, wherein the sintered blank is subjected in a die to one or more further press operations in which the material of the blank is allowed to flow freely in the direction transverse to the direction in which pressure is applied. In this manner the density of the product is increased.
  • the article is sintered again or annealed after the further press operation or operations to provide it with the required strength characteristics.
  • the additional step is advantageously carried out at room temperature.
  • the invention relates to the manufacture of articles by powder metallurgy, wherein a blank is formed from metal powder, whereafter the blank is compressed and sintered.
  • Articles can be made using metal powders as a raw material by what is called the powder metallurgical process. This process is used in particular where other manufacturing processes such as casting, forging or machine cutting cannot be used, or only at high cost and under technical difficulties.
  • the principle involved in the powder metallurgical process of manufacture is that a metal powder, or a mixture of powders consisting of metals and non-metals, is formed into the shape of the product by compression in a die. The blank formed in this way is then sintered at a high temperature.
  • two punches can be used acting in opposite directions.
  • the densified intermediate product obtained in this way is a compressed blank whose shape and dimensions are determined by the shapes of the press tools used, and by the amount of pressure applied.
  • the compressed blank is then sintered at a high temperature so as to bond the particles together by a process of diffusion.
  • the sintering is usually conducted under a protective gas, or in a reducing atmosphere.
  • calibrating or sizing In order to improve the dimensional accuracy of the finished product it is known to subject the product, after sintering, to a second press operation called calibrating or sizing.
  • the sizing is done by subjecting the product to a second press operation in a completely closed die, to the effect that at the end of the sizing operation the product is a precise positive replica of the fully closed die, which can be regarded as the corresponding negative shape, or female mould.
  • the object of the present invention is to provide a simple process for producing products by powder metallurgy which have densities considerably higher than those hitherto obtainable.
  • an article is manufactured by powder metallurgy by a process in which, after a blank has been compressed and sintered, it is then subjected to one or more further press operations in a die in which the material of the blank is allowed to flow freely in the direction transverse to the direction in which pressure is applied.
  • This further press operation is advantageously performed at room temperature.
  • the process, in accordance with the invention for producing sintered articles is quite simple.
  • a measured quantity of a metal powder is compressed in a press to produce a compressed blank having a density between 50 and percent of the theoretical density.
  • the press tools can be of customary construction.
  • the pressed blank is sintered in the usual way, preferably under a protective gas.
  • the compressed and sintered blank is subjected to a second press operation using press tools arranged in such a way that the material can flow freely in the direction transverse to the direction in which pressure is applied, without being impeded by the press tools. This, of course, requires that there is sufficient space between the wall of the die and the blank.
  • the dimension of the die which is transverse to the pressure direction must be larger than the lateral dimension of the blank to be compressed so that the walls of the die do not form any resistance to the free flow of the material during the press operation.
  • the density of the product is increased to between 85 and 99.9 percent of the theoretical maximum density.
  • the re-densification of the product, or superdensification can, if desired, be repeated several times. The product is at the same time given a different shape by the re-densification press operation.
  • Products which have been re-densified in this way can often be used without further processing, provided that only tensile strengths are involved, that is to say, not elongation at rupture.
  • the product is preferably subjected to a fourth stage of the process, in which it is either sintered or annealed, This gives the optimum tensile strength and elongation at rupture.
  • the product can be calibrated, hot or cold, stamped or embossed, or forged.
  • sintered products made by the process of the present invention are so tough that they can be used as initial blanks for cold forging, extrusion pressing or flow pressing to give final products of complex shape by deformation without cutting. Furthermore, due to their comparatively high densities, these sintered products can be used as initial blanks for precision forging. This amounts in practice to hardly more than a final calibration of the product at high temperature, and requires only comparatively moderate pressures. Sintered products made in accordance with the present invention have also been found suitable for use as initial blanks for cold embossing.
  • FIG. 1 is a side elevational view of a cylindrical, compressed sintered blank
  • FIG. 2 shows the blank of FIG. 1 after it has been shaped into an article by being subjected to an additional press operation in accordance with the invention
  • FIG. 3 shows the article of FIG. 2 which, after a heat treatment, has again been subjected to a press operation pursuant to the invention
  • FIG. 4 shows the finished article which has been obtained by subjecting the article of FIG. 3 to a further inventive press operation
  • FIG. 5 is a vertical section through a press arrangement suitable for carrying out the inventive procedure.
  • the cylindrical blank I of FIG. 1 has a diameter of 15.1 mm and a height of 14.8 mm, as well as a hardness HB 5/2.5 of 63 kp/mm
  • the blank was formed in customary manner from electrolytic iron powder which was cold-pressed and subsequently sintered for about 1 hour at 1250C in a cracked-gas atmosphere.
  • the sintered blank thus obtained was then shaped in accordance with the invention by subjecting it to an additional press operation. This was effected in the press arrangement of FIG. 5 having a die 4 which is sufficiently large so as to allow the material of the blank of rial of the blank flowed within the die in outward direcwhich thus corresponds substantially to a round disc;
  • the article 112 obtained according to FIG. 3 was finally subjected to a terminal cold-shaping in which the material of the article flowed freely in lateral direction, whereby the article of the final shape 10, shown in FIG. 4, was obtained.
  • the largest diameter of this article 10 was 27.8 mm while its height was 13 mm. It follows that the diameter increase from the original blank of FIG. 1 to the final article of FIG. 4 was more than 12 mm.
  • Powder (g-/ m-) (kit/mm?) /emf) (kn/mm?) (g./cm.) (kp./mm.'-') (glemfi) (kn/mm?) (g./em.'-) (kp./mm.'-)
  • the additional press operation in the press of FIG. 5 was carried out at oom temperature and at a pressure of2 Mp/cm During this additonal pressing, the mate
  • the data of the Table indicate that the inventive procedure results in a significant increase in the density. Such density increase cannot be obtained according to the prior art procedure, for example according to the customary double-press techniquefThis could be demonstrated by a comparison test wherein an electrolytic iron powder corresponding to the powder of the above test could be compacted to a density of 7.4 g/cm only.
  • the data of the Table indicate that the increase in the density causes also a significant increase in the hardness and thus also in the strength of the article.
  • the increase in the strength values is demonstrated by the fact that the starting blank of FIG. 1 has a tensile strength of 25 kp/mm while the final article of FIG. 4 has a tensile strength of 54 kp/mm
  • the pressing is preferable performed by press tools, as shown in FIG. 5, consisting of an upper punch 2, with an exchangeable punch tool 3, working in a die 4.
  • the redensified product 1a of FIG. 2 is introduced into the die 4 through an opening 5.
  • the die 4 rests on a pressure plate 6, which rests on a spacer ring 7 reposing on a base plate 8.
  • the spacer ring 7 contains a foot plate 9 of an ejector piston 10 which works in bores passing through the pressure plate 6 and the die 4.
  • An ejector pin 11 works in a bore in the base plate 8 and acts on the foot 9 of the ejector piston 10, so that when the pin 11 is lifted, the piston 10 pushes the deformed product 117 out of the die 4 through the upper opening 5.
  • the additional press operations may be performed in the same press arrangement by choosing suitable punch tools and die.
  • the die of course, has always to be sufficiently large so as to permit the free flow in transverse direction.
  • a process for manufacturing an article by powder metallurgy comprising the steps of forming a blank from metal powder, compressing said blank and sintering said blank, the improvement comprising the additional step of subjecting said compressed and sintered blank to a least one additional press operation in a die in which the material of said blank is allowed to flow freely in the direction transverse to the direction in which pressure is applied and carrying out theat least one-additional press operation at room temperature.
  • a process as claimed in claim 1, comprising the further step of sintering or annealing said blank after said further press operation.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Powder Metallurgy (AREA)
  • Forging (AREA)
US00217510A 1968-08-20 1972-01-13 Process of working a sintered powder metal compact Expired - Lifetime US3785038A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1758849A DE1758849B2 (de) 1968-08-20 1968-08-20 Verfahren zum pulvermetallurgischen Herstellen von Formteilen

Publications (1)

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US3785038A true US3785038A (en) 1974-01-15

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US00217510A Expired - Lifetime US3785038A (en) 1968-08-20 1972-01-13 Process of working a sintered powder metal compact

Country Status (5)

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US (1) US3785038A (enrdf_load_stackoverflow)
JP (1) JPS4815764B1 (enrdf_load_stackoverflow)
DE (1) DE1758849B2 (enrdf_load_stackoverflow)
FR (1) FR2015955A1 (enrdf_load_stackoverflow)
GB (1) GB1256763A (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3832763A (en) * 1972-04-22 1974-09-03 Bluecher Wahlstatt Leichtmet Method of drop-forging sintered workpieces
US3864808A (en) * 1973-09-06 1975-02-11 Gen Electric Method of deforming sintered magnets without significantly reducing magnetic properties
US3866303A (en) * 1973-06-27 1975-02-18 Bethlehem Steel Corp Method of making cross-rolled powder metal discs
US3871200A (en) * 1973-02-06 1975-03-18 Sumitomo Electric Industries Method and apparatus for producing sintered metal product
US3874049A (en) * 1973-04-13 1975-04-01 Burdsall & Ward Co Method of making a powdered metal part having a bearing surface
EP0054404A1 (en) * 1980-12-16 1982-06-23 Kelsey-Hayes Company Method of forming an article
US4897117A (en) * 1986-03-25 1990-01-30 Teledyne Industries, Inc. Hardened penetrators
US5088554A (en) * 1990-10-22 1992-02-18 Otis Engineering Corporation Sintered metal sand screen
US5293935A (en) * 1990-10-22 1994-03-15 Halliburton Company Sintered metal substitute for prepack screen aggregate
US5339895A (en) * 1993-03-22 1994-08-23 Halliburton Company Sintered spherical plastic bead prepack screen aggregate
US5377750A (en) * 1992-07-29 1995-01-03 Halliburton Company Sand screen completion
US6454991B1 (en) * 2000-10-30 2002-09-24 Unisa Jecs Corporation Method of forging raw material for sintering and forging
US10046392B2 (en) 2015-03-04 2018-08-14 The Boeing Company Crack-free fabrication of near net shape powder-based metallic parts
CN113523277A (zh) * 2021-07-15 2021-10-22 山东宝元硬质合金有限公司 一种通过两次压制实现成型的成型方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1809780A (en) * 1929-02-04 1931-06-09 Ohio Instr Mfg Company Producing metallic articles
US2447434A (en) * 1944-06-06 1948-08-17 American Electro Metal Corp Method of compacting metal powder into complicated shapes
US2778064A (en) * 1951-10-20 1957-01-22 Thompson Prod Inc Coining method and apparatus
US3060560A (en) * 1959-01-12 1962-10-30 Int Harvester Co Method for cold extruding high density articles from ferrous metal powder
US3089189A (en) * 1959-08-07 1963-05-14 Westinghouse Electric Corp Apparatus and process for forming high density compacts
GB1001009A (en) * 1962-03-01 1965-08-11 L Esercizio Dell Istituto Sper Working aluminium
US3645728A (en) * 1970-06-03 1972-02-29 Gen Motors Corp Method for making spark plug shells

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1809780A (en) * 1929-02-04 1931-06-09 Ohio Instr Mfg Company Producing metallic articles
US2447434A (en) * 1944-06-06 1948-08-17 American Electro Metal Corp Method of compacting metal powder into complicated shapes
US2778064A (en) * 1951-10-20 1957-01-22 Thompson Prod Inc Coining method and apparatus
US3060560A (en) * 1959-01-12 1962-10-30 Int Harvester Co Method for cold extruding high density articles from ferrous metal powder
US3089189A (en) * 1959-08-07 1963-05-14 Westinghouse Electric Corp Apparatus and process for forming high density compacts
GB1001009A (en) * 1962-03-01 1965-08-11 L Esercizio Dell Istituto Sper Working aluminium
US3645728A (en) * 1970-06-03 1972-02-29 Gen Motors Corp Method for making spark plug shells

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3832763A (en) * 1972-04-22 1974-09-03 Bluecher Wahlstatt Leichtmet Method of drop-forging sintered workpieces
US3871200A (en) * 1973-02-06 1975-03-18 Sumitomo Electric Industries Method and apparatus for producing sintered metal product
US3874049A (en) * 1973-04-13 1975-04-01 Burdsall & Ward Co Method of making a powdered metal part having a bearing surface
US3866303A (en) * 1973-06-27 1975-02-18 Bethlehem Steel Corp Method of making cross-rolled powder metal discs
US3864808A (en) * 1973-09-06 1975-02-11 Gen Electric Method of deforming sintered magnets without significantly reducing magnetic properties
EP0054404A1 (en) * 1980-12-16 1982-06-23 Kelsey-Hayes Company Method of forming an article
US4897117A (en) * 1986-03-25 1990-01-30 Teledyne Industries, Inc. Hardened penetrators
US5088554A (en) * 1990-10-22 1992-02-18 Otis Engineering Corporation Sintered metal sand screen
US5293935A (en) * 1990-10-22 1994-03-15 Halliburton Company Sintered metal substitute for prepack screen aggregate
US5377750A (en) * 1992-07-29 1995-01-03 Halliburton Company Sand screen completion
US5339895A (en) * 1993-03-22 1994-08-23 Halliburton Company Sintered spherical plastic bead prepack screen aggregate
US6454991B1 (en) * 2000-10-30 2002-09-24 Unisa Jecs Corporation Method of forging raw material for sintering and forging
US10046392B2 (en) 2015-03-04 2018-08-14 The Boeing Company Crack-free fabrication of near net shape powder-based metallic parts
US11203063B2 (en) 2015-03-04 2021-12-21 The Boeing Company Crack-free fabrication of near net shape powder-based metallic parts
CN113523277A (zh) * 2021-07-15 2021-10-22 山东宝元硬质合金有限公司 一种通过两次压制实现成型的成型方法

Also Published As

Publication number Publication date
JPS4815764B1 (enrdf_load_stackoverflow) 1973-05-17
DE1758849A1 (de) 1974-04-04
DE1758849B2 (de) 1974-08-08
GB1256763A (enrdf_load_stackoverflow) 1971-12-15
FR2015955A1 (enrdf_load_stackoverflow) 1970-04-30

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