Abstract: Flame resistant acrylic fibers are produced by, in a solution polymerization of a mixture consisting of 30-80% by weight of acrylonitrile, 20-70% by weight of vinyl chloride or vinylidene chloride and 0-15% by weight of the other unsaturated monomer in a solvent of dimethylformamide, adding a polymer (referred to as blendmer) consisting of acrylonitrile, vinyl chloride or vinylidene chloride and an anionic monomer and zinc salt of an aromatic sulfonic acid prior to starting of the polymerization, subjecting the resulting mixture to the solution polymerization, removing unreacted monomers from the formed polymer solution, adding sulfur dioxide and adding water to adjust water content, spinning the thus formed spinning solution into an aqueous solution of dimethylformamide.

Abstract: In a tool-indexing apparatus, the apparatus comprises a member being moved in a linear direction, one set of ball screws which connects between the member and a tool-post, a stopper which restricts the linear movement of the tool-post, and two coil springs which resist against the linear movement of the tool-post and the member. During the operation of the apparatus, first, the member together with the tool-post are lifted, and after the tool-post has become abutted against the stopper via one of the two coil springs, the tool-post is revolved by means of one set of ball screws and by the other one of the coil springs for establishing the tool-indexing operation of the apparatus.

Abstract: A drilling machine with an automatic tool changer (A.T.C.) including a driving motor which drives a spindle head to traverse, upwards and downwards and a tool magazine which is rotatably supported by the spindle head and has a plurality of tools, wherein when one of the tools is to be interchanged with another of the tools, said tool magazine is rotated at predetermined angles by the driving motor by means of the spindle head and a link mechanism.

Abstract: A drilling machine with an automatic tool changer (A.T.C.) comprising a driving motor for a spindle head and a tool magazine rotatably supported by the spindle head and provided with a plurality of tool arbors for holding tools, one of the tools being interchanged with another of the tools by intermittent rotation of the tool magazine, and wherein the tool arbors are supported for swinging movement between a protrusion position and a retraction position so as not to obstruct the machining operation.