Abstract: An injection molding machine includes a sub-mold hollow structure defining a plurality of sub-mold hollows which are formed in at least one of a fixed-side base plate and a movable-side base plate with a keyway being formed in the base plate in which the sub-mold hollow structure is formed. A changeable sub-mold is detachably mounted in each of the sub-mold hollows, and a comb-shaped fixing key is detachably engaged in the keyway and fixes the changeable sub-molds when the comb-like fixing key is inserted into the keyway.

Abstract: A lead screw for moving, for example, a printing head or a magnetic head. The screw is molded from plastics by a split mold comprising a plurality of longitudinally extending sections. It has on its outer peripheral surface a helical groove satisfying the following relationship: ##EQU1## where P: pitch of the groove;R: radius of the screw;r: radius of the screw between its longitudinal axis and the bottom of the groove;.theta.: angle of division of the mold sections; andL: a half of the difference in width between the top and bottom of the groove. The bottom of the groove is smaller in width than the top thereof.

Abstract: An electrically less chargeable wool-polyester suiting woven or knitted mostly from a non-electroconductive yarn and partly from an electroconductive yarn of the type containing a carbon-black-coated mono-filament fiber. The suiting comprises 0.1% to 0.6% of the mono-filament fiber for obtaining a necessary anti-electrostatic effect. The monofilament fiber in the electroconductive yarn is covered by wool and other fibers having an aggregate amount by weight more than its fivefold amount and an average single-fiber finess less than its one-fifth finess, so that it is prevented from appearing streaky on the surface of the suiting. The electroconductive yarn in the suiting is protected from interruption both in production and in use by the non-electroconductive yarn including polyester multi-filament fibers.