PURPOSE: To abolish a tapping operation and to reduce the degreasing process of a cutting oil by a method wherein a screw hole is formed instead of a threaded hole in the mounting device of an apparatus.

CONSTITUTION: A screw hole 13 is made on a mounting-face part 12a on an apparatus outer enclosure 12, and a peripheral edge part 14 which is inclined to be a funnel-face shape at the peripheral edge of the screw receiver hole 13 and whose height is changed continuously to the peripheral direction so as to form a difference in level in an opposite part in the radial direction is formed.