液中放電による硬質粉体の分散を利用した砥粒層の形成 （第１報）―絶緑体粉体の堆積層への分散―

Abstract

This paper deals with a fabrication method of an abrasive layer by electrical discharge machining (EDM). A grinding wheel should be frequently dressed and as a result its total life becomes shorter. When the total life of the grinding wheel has ended, the grinding wheel is disposed of even if its core is still usable. To extend the total life of the grinding wheel by recycling, a fabrication process of an abrasive layer by EDM is proposed. The layer deposited by EDM with a green compact electrode is porous due to the electrical conditions. The green compact electrode was made by compressing a mixture of WC, Co and an abrasive, which is generally an insulating material. The layer produced with the dispersed abrasive powders with a size of 20-100μm could be deposited on a plate. The grain size and the thermal conductivity mainly affect the layer properties. Each grain volume percentage was evaluated with a partial section analyzed by energy dispersive X-ray spectroscopy. The volume percentages of #150 and #400 SiC grains were 6% and 10%, respectively, when the volume ratio of the SiC grains in each electrode was 32%. These ratios are much smaller than that of conventional grinding wheels, 34-62% in nominal. The hardness of the WC-Co layer without abrasive was 102 HRRS, harder than a general vitrified bond wheel. Because the deposit of the WC-Co layer was very hard, tight gripping of grits can be also expected.