| 摘要 |
305,950. Steinr³ck, H. Feb. 11, 1928, [Convention date]. Taps; dies; chasers.-Screw cutters such as taps, chasers, dies &c. with roughing and finishing teeth disposed for operation in alternation or sequence have the roughing teeth and finishing teeth similar in outline but formed on different core diameters, the mutilated tops of the two kinds of teeth being bounded by conical surfaces axially displaced. In the diagrammatic representation of the teeth of a tap, Fig. 1, the boundary of the core of the roughing teeth is shown by line a, a<1> and that of the core of the finishing teeth by line b, b<1>. The finishing teeth ribs begin at f, the portion f, g being formed as a reamer to clear material from a small size hole and the part f, a<1> serving as a non-cutting guide portion. The bounding surface of the roughing teeth faces is represented by the line d, a<1> and that of the finishing teeth by the line e, f. Fig. 3 shows a tap with six teeth ribs, 1, 3, 5 with roughing teeth and 2, 4, 6 with finishing teeth. Specification 246,105 is referred to. |
