Classifications

• • 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
  • B22F3/20—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by extruding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/01—Extruding metal; Impact extrusion starting from material of particular form or shape, e.g. mechanically pre-treated
• • 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
  • B22F8/00—Manufacture of articles from scrap or waste metal particles
• • 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
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling
• • 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
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
• • 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
• • 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
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49751—Scrap recovering or utilizing
  • Y10T29/49753—Metalworking to consolidate scrap

Definitions

• flake refers to particles having a width which is larger than the thickness and an extension at least as large as the width. Usually, however, the length of such a particle is considerably larger than the width.
• An example of flakes within this definition is, for example, metallic cuttings as they are produced during operations such as boring, drilling, planing, lathing, sawing or the like. Such flakes are created as a waste, particularly when compact or porous objects made of metal powder are worked in that matter.
• fiber is used here to denote particles having a length which is large in relation to its cross-sectional dimensions, whereby the cross section may be round, oval, square shaped, or the like.
• fibers within that definition are, for example, fine sawdust, sawmill waste, filings, or the like.
• fibers powder particles of elongated grain shape or wire cuttings are included.
• the surfaces of the flakes and fibers can be rough and cracked, i.e., smoothness is not a prerequisite for practicing the invention. All these types of particles together will, in the following, be collectively called shavings.
• the shavings are compressed, sintered and hot pressed.
• manufacturing of higher grade products such as rods, or pipes at nonporous compacted consistency has not been tried successfully prior to the present invention, and particularly shavings which contain chromium have been regarded as being essentially useless and impossible to be recompacted to form any high-grade nonporous workpieces.
• the shavings are compressed to form blocks or billets, preferably cylindrical billets, and the degree of compression is such that the relative density is about 60 to 80 percent of the solid material.
• the billets are heated and extruded at a temperature above the recrystallization temperature, whereby workpieces at the desired profiles are obtained.
• workpieces at the desired profiles are obtained.
• rods, tubes or the like can be extruded, whereby the final cross section should be not more than one-third of the original cross section. Heating and extrusion is carried out in an environment free from oxygen and the influx of oxygen is to be avoided.
• the products resulting from the extrusion are subsequently worked in a manner known, per se, to obtain, for example, wire or tubes having smaller dimensions.
• the steps outlined in the previous paragraph constitutes the basic method, however, in cases the following steps should be included.
• the compressed, but still porous billets are heat treated prior to extrusion.
• the particular material has oxides which are easily reducible, such as nickel, copper or soft iron; the billets are preferably annealed just in the presence of a reducing gas such as hydrogen.
• the shavings consist of or include a material the oxide of which is rather difficult to reduce, such as chromium
• the annealing is carried out essentially in a vacuum but in the presence of a reducing medium.
• the reducing medium is usually carbon and should be present in sufficient quantities in the compressed porous billets.
• the blocks can, for example, be recarbonized or nitrided.
• the different shavings In preparation for carrying out the principal steps in accordance with the invention, it is preferred to collect the different shavings separately as to quality.
• the collected shavings include nonmetallic impurities, such as sand, a cleaning process should precede the compression steps.
• the shavings are preferably cleaned in a liquid which also degreases them. Impurities and dirt particles sticking to the surface of the shavings are dissolved and/or separated and drop to the bottom of the tank containing the cleaning liquid.
• This cleaning process can be dispensed with if the impurities consist exclusively of substances which will vaporize or decompose at elevated temperatures within the range used for subsequent processing. This holds true particularly for grease and oil.
• anneal them in air so that they oxidize.
• steel shavings known as 18/8 chromium nickel steel are preferably annealed for 10 minutes in a temperature of 800l,000 C. It must be observed that during the work process, as the shavings were produced, the substance constituting the shavings was considerably hardened. This annealing step reverses, so to speak, that hardening, and thus facilitates further processing.
• the surface oxidation resulting from annealing the shavings in air has the following purpose. Subsequently, as the oxide layer is reduced, the shavings obtain surface contours which are highly susceptible to reaction and sintering.
• the composition of the final product can be controlled in that the shavings are mixed with a metal powder, whereby the relative powder content may go up to percent, preferably, however, a range of 20 to 60 percent is used.
• the powder should have a grain size smaller than 2 mm.
• Shavings and metal powder are preferably mixed by including a substance which inhibits separation.
• the substance should have a certain stickiness to provide some bonding between powder particles and shavings. For example, stearic acid, molasses, or the like, can be used.
• the powder may consist of the same material as the shavings, for example, copper, nickel, soft iron, or the like.
• the composition of the added powder may well be quite different from the composition of the shavings. These differences may relate to the material in its entirety or merely as to alloying components and/or the relative content thereof.
• the powder may serve to establish particular proportions of the various components in the final product. This is particularly desirable if the final product is to consist of highalloy steel. Wire cuttings could be added to the shavings in lieu of powder but for the same purpose.
• shavings and powder may differ as to the proportion of the element components. whereby, for example, even minor relative differences in the proportion of various alloying components in shavings and powder permit rather accurate adjustment of the composition of the final product. lt was in shavings powder permit that. for example, high-alloy tubes or welding rods could be produced in this manner as very accurate metering of the constituents is permitted.
• the invention is not limited to making this type of product. Moreover, shavings and powder may have quite different composition. In the following, several different examples are outlined with particularity to show versatility of the principles of the invention.
• Flaky shavings were collected after rods had been sawed; the rods in particular consisted of 18/8 chromium nickel steel. The shavings were cleaned in a degreasing liquid and subsequently compressed to cylindrical billets of 58 mm. diameter and approximately 100 mm. in height. The billets were pressed in a steel mold. After compression the billets had a specific weight of 5.3 grams per cubic cm. and a relative density of 67 percent. These billets were lined and welded in a soft iron coating. The clad billets were extruded at 1,200 C. to produce rods with substantially no porosity.
• EXAMPLE 2 This example includes essentially all steps outlined above. Shavings resulting from lathing of 18/8 chromium nickel steel billets were collected and cleaned in a degreasing liquid. The shavings were subsequently annealed in air for l minutes at 900 C. to form an oxide coating. Independently therefrom a powder was produced by atomizing steel having 18 percent chromium and 8 percent nickel. The oxidized shavings and the powder were mixed at a ratio of 70 percent shavings to 30 percent powder. The carbon and oxygen contents of the mixture had a ratio of approximately 1 to 1.3 Next, this mixture was compressed in a steel form to produce cylindrical billets of 58 mm. diameter and approximately 100 mm. height.
• the billets had a specific weight of approximately 5.6 grams per cubic cm. and a relative density of approximately 31 percent. These billets were annealed in a vacuum furnace for about 10 hours at 1,250" C. at a pressure of approximately 10' torr. (mm. mercury). In order to protect the billets from oxidation, they were lined with a soft iron coating and welded. Finally, tubes were extruded from the billets at 1,200 C. The tubes had essentially no porosity and a carbon content of approximately 004 percent.
• EXAMPLE 3 The mixture employed consisted of 60 percent shavings of 18/8 chromium nickel steel and 40 percent steel powder having l5.5 percent chromium and 15.5 percent nickel. in accordance with these chosen proportions rods or tubes can be extruded having approximately 17 percent chromium and 11 percent nickel. As it is desirable to obtain extremely low carbon content the ratio or carbon to oxygen is adjusted so that after vacuum annealing the carbon content is approximately 0.005 percent.
• the shavings-powder mixture consists of 50 percent shavings of an unalloyed soft iron and 50 percent steel powder with 36 percent chromium and 16 percent nickel. Rods extruded from billets of such mixture exhibit hetergeneous structure of highly stretched ferrite and austenite grains, they are also quite ductile.
• EXAMPLE 5 The mixture employed consisted of 20 percent shavings of soft iron; 30 percent shavings of steel having 25 percent chromium and 20 percent nickel; 20 percent shavings of steel having 8 percent chromium, 23 percent steel powder with 36 percent chromium and 5 percent nickel powder. Extruded rods had a chromium content of approximately 18 percent and a nickel content of approximately 11 percent; the rods had hetergenic grain structure.
• the invention can also be employed by using shavings of nonferrous metal, for example, copper or nickel, or nonferrous alloys.
• the invention also permits production of products with uniformly distributed inclusions, for example, carbides, oxides, and nitrides.
• the invention is furthermore amenable to employment of those types of materials which include small portions of rather easily oxidizing metal such as aluminum.
• the inventive method can be used to extrude rods of a chromium aluminum steel to be used as heating element having 5 to 6 percent aluminum.
• the finely distributed aluminum oxide improves heat resistance and creeping strength.
• aluminum oxide inhibits formation of coarse grains.
• Method of making compacted, essentially nonporous workpieces such as rods or pipes of high density, comprising the steps of:
• metallic shavings including shavings containing a substantial amount of chromium
• the cleaning step including subjecting the shavings to a degreasing liquid.
• Method as in claim 13 comprising the providing of chromium nickel steel shavings, and annealing the shavings at a temperature of about 800 to l,000 C. prior to compression. to obtain oxide coating on the shavings.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Powder Metallurgy (AREA)

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Cited By (8)

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Citations (3)

• 1968
  • 1968-07-09 DE DE1752757A patent/DE1752757B2/de active Pending
• 1969
  • 1969-05-23 AT AT497369A patent/AT298943B/de not_active IP Right Cessation
  • 1969-06-16 GB GB1265406D patent/GB1265406A/en not_active Expired
  • 1969-06-30 SE SE930469A patent/SE341797B/xx unknown
  • 1969-07-03 US US3629929D patent/US3629929A/en not_active Expired - Lifetime
  • 1969-07-08 FR FR6923177A patent/FR2012565A1/fr not_active Withdrawn

Patent Citations (3)

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