| 摘要 |
<p>375,596. Drills. SCHEEREN, J., 1, Spreestrasse, Niedersch÷neweide, and STILLER, M., 1, Sturmvogelstrasse, Johannisthal, both in Berlin. Aug. 7, 1931, No. 22439. [Class 83 (iii).] The cylindrical shaft of a stone drill is closely surrounded by a helix of wire or the like to convey away the chips. The helix 5 is preferably of square or rectangular cross section having one flat side against the drill shaft 1 which consists of a tube into one end of which a plug 2 forming the drill head is inserted, a plug 3 forming the fixing part of the drill being inserted into the other end, the plugs being fixed by brazing. One end of the helix 5 is hooked at 6 into a corresponding hole in the drill head 2, while the other end provided with an upset thickening 7 is inserted in a hole 9 in a collar 8, which can be turned on the plug 3, by a hole 12, so as to tension the helix. The collar 8 is fixed in the desired position by a screw 10, Fig. 4, the point of which engages in a shallow bore 11. The cutter of the drill is formed of a hard metal plate 13 inserted axially in the head 2, the face 14 being hollow ground. The backs of the two cutting edges are supported by parts 15 of the drill head 2, and the cutter 13 is fixed in the head by welding, brazing, and the like.</p> |
