PURPOSE: To obtain a hardwearing magnetic fixing device wherein thermal strain does not exist in base material and characteristics do not deteriorate, by providing a magnetic acting surface with a hardened region applying spray coating material of rigid ceramic material, cermet material or metallic material.
CONSTITUTION: The surface plate 14 of a chuck has slender hardened regions 32 specifying a magnetic acting surface 30 together with slender magnetic pole segments 24, 26 alternately arranged in parallel facing each other across a spacer 22 of non-magnetic material. The region 32 is formed by spray-coating rigid material of ceramic material Al2O3 and the like, cermet material WC-Co and the like, and metallic material Mo and the like, and stacking the coating films. Each hardened region 32 is arranged on the surface plate 14 except both sides in the width direction, in order to prevent it from exfoliating from a base material. In this constitution, a magnetic acting surface 30 is provided with the hardened region, so that the hardwearing properties are improved, and the hardened region is formed by spray coating, so that thermal influence on the surface plate 14 is extremely little as compared with heat-treating method. Therefore thermal strain does not occur in the inside, and the deterioration of characteristics is reduced.
UCHIKUNE MAMORU
NAKAJIMA TAKAHITO
NAKAJIMA EIJI
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