GB191118988A - Improvements in Screwing Machines. - Google Patents

Abstract

18,988. Maiden, L., and Maiden, J. Aug. 24. Screwing; screwing die-heads; turning.-In a machine for screwing vanishing threads, or tapered or partly parallel and p a r t l y tapered threads, the adjusting-cam, which is incapable of longitudinal movement and is cons t a n t l y pressed by springs to tend to open the dies, is held against an inclined stop which is carried by a sleeve slidably mounted on the die h e a d and is gradually withdrawn so as to allow the recession of the dies. The cam ring b, which is connected by a pair of coiled springs h, so as to admit of relative rotary motion to a ring q bolted to a flange on the rotary die head a, is surrounded by a brake strap m, which is tightened so as to retard the rotation of the cam relative to the die head for closing the dies by a lever r pivoted at p and operated on the withdrawal of the work-slide u by an arm t through a stop v on a rod s. The dies are held in their closed position by a stop k on the cam engaging a removable bevelled bar j clamped to a flange on a sleeve i which is pressed forward by a tension spring z' and lever o, and is retracted to give the tapering action on the forward motion of the work-slide by a lug on the latter engaging a stop z on a rod y connected to the lever o by a lever x and link w. The bar slides between guides l<1>, l<2> on the ring g, and the motion of the cam is stopped after retraction of the bar bv a stop k<1> contacting with the guide l<2>. The sleeve and brake may be operated by a hand lever q. As shown in Fig. 8, preliminary turning-tools are provided in slots in the front portion of the die head, and are adjusted by a hand-operated cam b<1> to the diameter required.