Patent GB-237068-A (GB)
Title: Improved means for use in machining two oppositely tapering surfaces of a work piece and in screw threading such surfaces
IPC: B23G7/00
Filed: 1924-06-19
Abstract: 237,068. Richards Thread Milling Machine Co. (1918), Ltd., and Burt, L. N. June 19, 1924. Lathes ; milling screws. - In a machine for cutting and screwthreading tapered surfaces such as the interior of sockets for joining lengths of pipe, the workis rotated and acted upon at one setting, first by turning- tools carried in pivoted holders on an axiallv moving bar having a coaxial former which controls the tools, and then by a rotary tapered hob parallel to the work-axis. Screw-threading chasers controlled by the same former may precede the operation of the hob. The work B is mounted in a chuck A<3> rotated bv a worm-wheel drive and mounted on a slide adjustable transversely to the axis of rotation by a hand-wheel C<1> and a screw. The turning- tools I, I', are mounted in the pivoted holders J. J<1>. Fig. 3, in the bar H, so as to act on different parts of the work and are controlled by the former K which has longitudinal cam-slots x bevelled at the sides so that a rotation of the former can further control the cut. Springs L maintain the tools in their inner positions and serve to prevent cuttings from reaching the holders. The screwing-ohasers N, N<1> are slidably mounted in radial slots in holders L<2>, L<3> adjustably secured to the bar H, and the section of the cutting-teeth mav be parallel to the work axis or parallel to its inclined surface. The former K, Fig. 1, is secured to a shaft rotatably mounted in a racksleeve K<1> and is adjusted to position by a handwheel K<4> and is locked at K<5>. The shaft and sleeve each carry graduated flanges which determine the depth of cut for the tools I, N, governed by rotating the former, locking means being also provided. In operation, the bar H is fed through the rotating work by a self-acting feed F<1>, the free end of the bar sliding in a guide bush E and the former K remaining stationary while the bar is fed over it. When the operation of the tools I is complete the chasers N may be brought into operation by further movement of the bar, or the hob H<1>, H<2> may operate immediately. The hob is mounted on a rotary spindle G<1> driven by worm gearing Z<9>, Fig. 6, from a shaft Z<2> which also rotates the work and drives the self-acting. feed. Whilst the hob is being adjusted axially the work is maintained in a central position by means of a stop O<1>, and when the hob is in position for cutting, the work is fed laterally until an adjustable stop O is encountered, thus limiting the depth of thread. The hob is positioned axially by means of a stop P having two positions as determined by a handle P<1>, the difference between the two being an exact multiple of the pitch of the hob, and the width of the plain collar between the parts H<1>, H<2> of the hob being also a multiple of the pitch so as to ensure, that the thread cut by the two parts will be continuous throughout the work. In a modification of the apparatus the bar H carrying the turning and chasing tools is separate from the hob-spindle- and is mounted on a slide having an automatic. feed and taking the position of the bracket carrying the bush E. Chucks.-The chuck or collet A<3> has jaws adjustable by means of two scrolls y rotatable together through gearing. Specification 194,389 is referred to.