GB409907A - Improved self-opening screw-threading die - Google Patents

Abstract

409,907. Screwing die-heads. FILIERE UNICUM, 46, Rue de la Bienfaisance, Paris. May 31, 1933, No. 15732. Convention date, June 3, 1932. [Class 83 (iii).] A screw-cutting die-head having four chasers has at least two diametrically opposed chasers axially adjustable so that by adjusting these two chasers by half a pitch in opposite directions a die-head for cutting right-hand threads may be adapted for cutting left-hand threads, and vice versa, As applied to a transversely wedged die-head the chasers 67 are axially adjustable on their carriers 51-54, the carrier 51 being provided with a slot 62 engaging a lug 61 on a nut 55 threaded on a screw 63 rotatable within a bracket 56. The bracket is slidably guided between the two covers of the head by means of a pin 57 and by its cylindrical end 56<1>, and it is actuated to open and close the head through an eccentric 65 operated by a lever 34. Rotation of the screw 63 adjusts the cutting diameter of the head. In order to adapt the head for cutting either right or left hand threads, two diametrically opposed chasers are displaced axially in opposite directions by means of screws 70 whose ends engage the sides of recesses 69, Fig. 3, in the carriers and which screw into slides 68 on which the chasers are mounted. It is also necessary to reverse the die-head in the machine, and to reverse its direction of rotation in changing from one hand to the other, The lever 34 is rotated in the opposite direction to the rotation of the head in order to open the dies so that the head may be opened automatically by a fixed projection on the machine engaging this lever.