GB390954A - Machine for grinding the threads of screw-cutting taps and the cutting edges and adjacent parts of other cutters - Google Patents

Abstract

390,954. Grinding screw-cutting taps &c. ATKINS, H. F., Old Fletton, Peterborough. April 19, 1932, No. 11124. [Class 60.] A machine for grinding the threads of screwcutting taps &c. wherein a rotating grinding wheel is automatically fed to the work while the tap is automatically rotated, the tap and wheel being relatively traversed, is distinguished by the provision of means for controlling the stop governing the grinding wheel consisting of a combination of levers co-operating with a relief cam and a cut cam. The tap a, Fig. 1 is held between a back centre c and a chuck d both carried in bearings, and both urged to the left by weighted cords c<4>, d<5> to hold a bearing ball d<8> on the chuck spindle in engagement with a cam e. The chuck spindle d<3> is rotated through variable speed gearing from a shaft g<2> driven by a hand-controlled expanding pulley g, and drives the cam e through two speed gearing including a gear wheel g<9>. The latter is fitted with a face cam i<7>, Fig. 5, which operates a lever i<6> actuating a pawl i4 to rotate a cam i<2> step by step. The cam i<2> is the cut cam and engages one end of a lever m, the other end of which is engaged by a stop o<2> actuated by a cam h on the end of the shaft g<2>, forming the relief cam. The lever m is centrally pivoted to the end of a lever n carrying the stop against which the pivoted or sliding carriage for the grinding wheel j abuts. At the end of each cut the wheel is moved out of operative position to allow the return of the tap for the next cut, by means of a cam-ended rod s operated through a lever t<2> by means of a cam t<5> on the face of the gear wheel g<9>, and the machine is stopped at the end of the complete operation by means of a cam v<3> on the face of the cut cam i2 engaging a retaining catch for the hand-lever v for operating the expanding pulley.