1. Field of the Invention
The present invention relates to a method of manufacturing sintered aluminum alloy parts using Al-Si series alloy powder as a raw material and, in particular, relates to a method of manufacturing sintered aluminum alloy parts incorporating an improved sintering method.
2. Description of Related Art
As examples of ferrous series metal materials such as cast iron and sintered iron were known as the material such as for scroll shaped revolving and stationary parts in a scroll type compressor. Further, as examples of non-ferrous series metal materials aluminum alloy (for example Al-Si alloy) as a light weight material was used and casting and die-casting methods were known therefor. Still further JP-A-62-96603 (1987) discloses a method of manufacturing sintered Al alloy parts.
JP-A-64-56806 (1989) discloses a manufacturing of scroll shaped parts wherein an Al alloy powder solidified via rapid cooling which is obtained by a gas atomizing method after melting an Al alloy is used, and after compression molding, in other words compacting, the Al alloy powder, the scroll shaped parts are manufactured via a hot extrusion, a hot forging after a hot extrusion or a hot forging. The Al-Si powder wherein Si is added to Al shows an advantage of reducing the thermal expansion coefficient of the product, however during the heating process at a high temperature the Al-Si powder is vigorously oxidized which extremely deteriorates the workability of the product so that such oxidation has to be prevented.
As explained above, when parts having a complex shape such as the scroll shaped parts were manufactured such as by processings of the hot forging and the extrusion after compression molding the alloy powder obtained by adding an effective element such as Si to the powder solidified via rapid cooling of the Al alloy according to the conventional method, the working of the product was rendered difficult because of the embrittlement thereof due to the oxidation at a high temperature, therefore a long manufacturing time was required therefor, further there were problems with regard to the mechanical strength and toughness of the product, still further there was a drawback that the product thus manufactured raised the production cost.