Powder metallurgy processes – Forming articles by uniting randomly associated metal particles – Consolidation of powders
Patent
1994-09-26
1996-10-15
Jordan, Charles T.
Powder metallurgy processes
Forming articles by uniting randomly associated metal particles
Consolidation of powders
419 61, 425 78, 425352, 425354, B22F 302
Patent
active
055663737
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to sintered materials, a method for their manufacture and to press apparatus for putting the method into effect.
Articles produced by a powder metallurgy route, and having two distinct layers, either prior to sintering or after sintering are known. U.S. Pat. No. 4,485,147 describes the manufacture of valve seat inserts for internal combustion engines. The valve seat inserts are made by providing two powder mixes; one mix being of a ferrous-based base powder and the second mix being of a copper-based material for the purpose of infiltration of the ferrous-based powder. A powder compaction die is first charged with a layer of the ferrous-based powder and then with a layer of the copper-based powder; the two layers being simultaneously compacted to form a green body having a relatively diffuse interface. The compacted green body is then sintered at a temperature to cause the copper-based layer to melt and infiltrate the ferrous-based layer. A significant problem with this method is that the interface between the two layers prior to sintering is necessarily diffuse and ill-defined, leading to poor surface quality in the final sintered product and necessitating the removal of relatively large quantities of metal by post-sintering machining operations. Other two-layer articles have also been proposed. EP-A-0 283 464 describes a rocker arm for the actuation of valves in an internal combustion engine. The rocker arm comprises a hard wear resistant material layer produced by powder compaction and sintering and having a body of a second ferrous-based powder compacted and sintered thereon. This article is produced by a two-stage process in that the hard wear resistant material layer is first made and then placed in a die to allow the body to be formed thereon. Special measures are employed in the provision of grooves or indentations in the pre-formed wear resistant layer to provide for mechanical keying to the subsequently compacted body.
EP-A-0 130 604 describes the manufacture of a two-layer valve seat insert for an internal combustion engine. The valve seat insert comprising two layers of different ferrous-based powders to provide specified physical and mechanical properties, the powders being individually compacted one upon the other and then sintered together.
Heretofore, powder compaction of such composite bodies has been by pressing on hydraulic presses. Hydraulic presses having die and press-ram movements governed by sophisticated microprocessor control systems have allowed complex pressing operations to be performed with relative ease. However, such presses and control systems are both expensive and slow in operation.
Purely mechanical presses are rapid in operation and relatively inexpensive, but heretofore have been relatively inflexible for the manufacture of the complex double layer type of article described above.
It is known to combine the advantages of controllability of hydraulic operation with the advantage of rapid press cycling of the mechanical press, by using a female die-body mounted on an axially moveable press matrix plate, the die-body and matrix plate being moveable relative to a fixed lower press ram, and a mechanically operated top press ram. In this hybrid press, the advantages of both hydraulic operation and mechanical operation may be combined.
It is an object of the present invention to provide a press apparatus having the versatility and controllability of a hydraulic press with the cycling rapidity of a mechanical press.
It is a further object of the present invention to provide a method for the manufacture of multi-layer articles by a powder metallurgy route, the method being more economic than known methods.
According to a first aspect of the present invention there is provided a method for the manufacture of an article by a powder metallurgy route, the article having at least two distinct, and separately compacted layers prior to any sintering operation, the method comprising the steps of sequentially depositing metal powder into a die cavity, synchr
REFERENCES:
patent: 3733154 (1973-05-01), Smith et al.
patent: 4000231 (1976-12-01), Peterson
patent: 4325734 (1982-04-01), Burrage et al.
patent: 4443171 (1984-04-01), Dixon
patent: 4626407 (1986-12-01), Veltri et al.
patent: 5043123 (1991-08-01), Gormans et al.
patent: 5308232 (1994-05-01), Merzhanov et al.
patent: 5401153 (1995-03-01), Katagiri et al.
patent: 5409662 (1995-04-01), Harai
patent: 5498147 (1996-03-01), Katagiri
Baker Andrew R.
Seimetz Hans-Georg
Jenkins Daniel
Jordan Charles T.
Komage Gellner Maschinenfabrik GmbH
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