| Summary: | 碩士 === 華梵大學 === 機電工程學系 === 102 === ABSTRACT
The paper was to investigate the manufacturing processes for the porous metal matrix diamond grinding wheels. First of all, selecting some suitable bond design and sintering conditions fabricates into some porous metal matrix grinding tool specimens. The following analyses of these specimens were studied: (1) porosity and density, (2) hardness, (3) bending strength, and (4) microstructure. In addition, the annular shape of sintered body with a metal matrix diamond layer and metal base were together sintered into a cup wheel, and then was dressed. Finally, these wheels were used to perform a dry grinding tungsten carbide under a CNC machine, which analyzes the grinding force, grinding temperature and surface roughness.
The experiment results showed that the bronze matrix containing the different proportions of pore formers would obtain the variations of density, hardness and bending strength. When a lower porosity of a metal bond tool was obtained, the resulting hardness and bending strength showed a relatively higher. Pore former remained in the wheel after sintering would cause a lower porosity, thereby leading a poor heat dissipation and chip removal ability during grinding. The wheel with a too high porosity or most of the pores formed around the grit would cause poor diamond retention in the matrix, which results in a lot of grits pulled-out. This would make the metal matrix of wheel to create friction with tungsten carbide, hence grinding force becomes larger, and then grinding temperature would rise. When the porous metal matrix diamond wheel with an appropriate porosity of 14~18%, hardness and bending strength was employed in a dry grinding tungsten carbide, the lower axial grinding force and the relatively better surface roughness were obtained.
Keywords: Porous metal matrix diamond wheel, bending strength, grinding performance.
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