GB619145A - Screw-threading attachment for lathes - Google Patents

Abstract

619,145. Attachments for screwing; die-heads. HOGFORS, H. F. B., and LARSSON, E. V. U. Aug. 9, 1946, No. 23707. Convention date, Aug. 20, 1945. [Class 83 (iii)] A screw-threading attachment for a lathe has a die or tap holder 8 rotatably and slidably mounted on a support 1 fitted to the tailstock of a lathe, an adjustable rod 6 disposed to prevent the holder from rotating while permitting the latter to move longitudinally to effect the screw-thread cutting over a length determined by the setting of the rod, and a rod 14 movable into and out of an operative position in which it secures the holder against rotation and permits retraction of the die or tap. The work is rotated by the headstock spindle and the die is brought into contact with the work by movement of the tailstock. During the cutting operation, an arm 9 attached to the holder bears against the rod 6 which extends beyond a flange 2 fixed to the support by an amount equal to the desired length of thread. This arm traverses the rod 6 and on reaching the end of the latter, stops the cut by allowing the holder to rotate. To unscrew the die, the rotation of the headstock is reversed, and the rod 14 pushed forward until its head 15 contacts a stop 16 on the rod 6. The rod 14 now arrests the arm 9 so that the work is unscrewed from the die. To ensure that the rod 14 is returned to its inoperative position, a plate 17 frictionally pivoted on the arm 9 is provided. During the cut, this plate occupies the position shown in Fig. 2, so that it overlaps the end of the rod 14 during the unscrewing operation. The holder 8 is provided with an adaptor (not shown) for tapping.