| 摘要 |
933,879. Tool holders; cutting tools. R. BREUNING. Nov. 25, 1960 [July 16, 1960; Aug. 20, 1960], No. 40549/60. Class 83 (3). A lathe tool holder 20, Figs. 3 and 4, is provided with an interchangeable hexagonal flat bit 28 fixed by means of a screw 16. The tool holder has a recess for the bit with a seating surface 40 inclined downwardly in the direction of the operative cutting edge 31. The bit is arranged with side faces at right angles to the upper and lower surfaces and has countersunk recesses 14 on both surfaces for the head of the fixing screw 15. Chip-guiding steps 29 are provided adjacent each cutting edge which give a positive rake angle. An intermediate plate 8, which may be of high speed steel, is advantageously interposed between the bit and its seating. The hexagonal bit 28, Fig. 3, is shaped from two equilateral triangles rotated relatively about a common centre by 25 degrees. This bit bears against the shoulders of the holder on three sides 41, 42, and 43 and clearance spaces 26 are provided at the corners of the shoulders. The chip-guiding steps are provided on three edges of the top face and on the three alternate edges of the lower face. |
