| 摘要 |
1,231,828. Screwing; screw-cutting. PRONTOR-WERK A. GAUTHIER G.m.b.H. 13 Sept., 1968 [16 Sept., 1967], No. 43673/68. Headings B3N and B3T. An automatic screw-cutting machine has one or a plurality of tapping spindles 1, each of which is moved by a cam 6 operating through a lever 3, a safeguard against thread breakage is formed by a switch 13 connected to a scanning switch 17 which is actuated once every revolution of a control shaft 7, a charging magazine 12 automatically feeds the machine with a barstock 9, a switching device is provided in the circuit of the safeguard, the device being actuated forcibly with the insertion of each new workpiece and bridging the switching effect produced by the safeguard in the course of a first turning operation after insertion of the new barstock. The switching device operates by a switch 20, which is actuated by a lever 20a, transmitting an impulse to a stepping or meter mechanism 21 which stores the impulse and causes a contact switch 22 to be closed. Thus, at the end of the first turning operation when cam 18 operates the switch 17, the drive to the machine is maintained. This continues until cam 24 actuates a cancellation key 23 causing the stored impulse to be cancelled which causes the switch 22 to be opened. If two taps are operated in succession, the stepping mechanism 21 must be adjusted so that the switching impulse is cancelled after the operation of the second tap. |
