Patent GB-275282-A (GB)
Title: Improvements in and relating to screw-cutting die heads
IPC: B23G5/12
Filed: 1926-03-02
Abstract: 275,282. Marks, E. C. R., (Landis Machine Co.). March 2, 1926. Screwing die-heads. - A screwing die-head comprises a front unit carrying pivoted chasers, a rear unit secured thereto, means for locking the chasers m adjusted position and means carried by the rear unit and movable relatively thereto for actuating the locking means. As applied to a rotary die-head the front unit comprises a body 40, Fig. 12, having parallel bores for the chaser-trunnions 47 and an integral flange 56 between which and a detachable flange 53 are rotatably mounted two rings 57, 58, the latter carrying a tangential worm engaging worm-teeth 63 on the body and the former carrying axially arranged pins 60, Fig. 2, engaging blocks 59 slidable in slots in the chaser carriers 48 to move them into and out of cutting position. The worm 64 is provided with a scale 66 for determining the adjusted position of the chasers and is maintained in position by the friction of an end nut 68 and a squareholed washer. The chasers 49, which are tangential, are secured in the carriers by clamping plates 50 and screws 51. A tangential spring 78 engages at one end on an abutment 79 secured to the ring 58 and at the other end on a plug 80 secured in a hole 80<1> in the ring 57. For cutting threads of opposite hand the chaser carriers are changed and the spring is moved to the opposite side of the abutment 79. The flange 53 is held to the body to keep the rings in place by four screws and a dowel pin, the arrangement being such that when part of the wormteeth 63 become worn the screws mav be removed and the dowel inserted in a hole 90‹ distant to engage the worm with new teeth on the body. The trunnions 47 are secured bv nuts 76, Fig. 12, which are locked by pointed screws 77 engaging the ends of the trunnions. One form of rear unit comprises a body 41, Fig. 12, having a recess to accommodate a spigot 52 on the front unit and attached thereto by four axial screws. A ring 84 is slidable on the body 41 and carries two locking pins 61 having conical ends for engaging hardened bushes 62 secured to the closing ring 57 on the front unit. When the cylindrical parts of the pins 61 engage the bushes 62 the chasers are locked in cutting position but when the pins are withdrawn by a yoke engaging recesses 88 in a ring 86 rotatably mounted on the ring 84 the ring 57 rotates under the influence of the spring 78 so as to open the head. The movements of the ring 84 are limited by the collar 48, the points of the pins 61 always remaining in engagement with the bushes 62 in order to reset the chasers when the ring 84 is moved forward again. in another form of rear unit the ring 84<1>, Fig. 20, is operated by radial pins 104 attached to a spider 99 which is adapted to be moved endwise by engagement with the end of the work. A square hole 99<1> in the spider is tapped for part of its length for engagement with a screwed sleeve 96 operated at 97 and acting in the square hole. A screwed spindle 94 operated at 95 engages a head 93 and serves to lock the parts in the adjusted position. Reamers.-The head is provided with internal and external teeth for reaming the end of a pipe and when the pipe engages the annular recess between the two sets of teeth the head is moved rearwards to open the head.