GB915286A - Improvements in or relating to tapping machines - Google Patents

Abstract

915,286. Screw-cutting. BRISTOL REPETITION Ltd., and ARENGO, C. G. April 27, 1959 [May 6, 1958], No. 14463/58. Class 83 (3). In a screwing-machine wherein the tool is advanced quickly to the work and the feed is then controlled, the drive-spindle and a coaxial sleeve are moved axially, the spindle is then rotated and the sleeve is held against rotation and further axial movement of the spindle is caused by a nut and screw on the spindle and sleeve, having the pitch of the thread to be cut. A drive-spindle 24 carrying a screw 23 is screwed into a rotatable and axially-slidable sleeve 15, and is splined in a pinion 27 rotated from an electric motor 13 through a geartrain 28. The end 26 of the spindle 24 is rotatable in a bridge 31 connected to a rod 29 which moves axially with the spindle. The sleeve 15 has an-annular groove 20 to engage rollers 19 on the forked-end 18 of a lever 16. The lever pivots at 17 and is spring-urged in the upward direction so that when the lever is depressed by hand, the sleeve 15, spindle 24 and rod 29 move downwardly until the bevelled face 35 on the sleeve 15 abuts a corresponding face on a bush 34 secured in a plate 32 which is non-rotatable but axially resiliently connected to a fixed bush 14 in the housing 11, due to a spring 33. In operation, as the tap or die connected to the shaft 24 at 25 is moved up to the work by the lever 16, a pin 36 in the bridge 31 actuates a switch 37 to start the motor 13 and the sleeve 15 and spindle 24 rotate. When the face 35 on the sleeve engages the bush 34, rotation of the sleeve ceases and the screw 23 on the spindle 24 moves in the nut 22, thus controlling the feed of the tap or die. A further slight pressure on the sleeve 15 when it engages the bush 34 compresses the spring 33 and a recess 38 in the lever 16 engages a pawl 39 to rock it about a pivot 40 against a spring 41 and cause it to lock the lever 16 and sleeve 15. At the end of the screwing operation a nut 42 on the rod 29 actuates a switch 43 which reverses the rotation of the motor, and the spindle 24 and rod 29 move upwardly until a cam 44 on the rod 29 releases the pawl 39 from engagement with the lever 16 and the spring- urged lever 16 moves the spindle 24, rod 29, and sleeve quickly to the starting position, and in so doing a switch 46 is actuated by the pin 36 to stop the motor 13. The switches 37, 46 operate only in one direction. The positions of the nut 42 and the cam 44 are adjustable.