GB438549A - A new and improved screw-threading machine for forming taper threads - Google Patents

Abstract

438,549. Screwing; die-heads. KENDALL & GENT (1920), Ltd., and HALL, J. L., Victoria Works, Gorton, Manchester. Oct. 3, 1934, No. 28283. [Class 83 (iii)] In a screw-threading machine of the kind employing a rotary die-head which is opened and closed by a lever or yoke engaging a grooved sleeve thereon, the feed motion between the work and die-head is arranged to impart movement to the fulcrum of the yoke for the purpose of cutting a tapered screw-thread. The machine comprises a rotary die-head f and a work-holder a movable to and from the diehead along the bed e. A bracket b on the workholder is slidable on a rod c pivoted to a lever g mounted on a fixed pivot on the machine. The lever g is slotted and connected to a slotted lever h by means of a link i adjustable in length so that the movement of the lever g may be transmitted to the lever h in variable amounts for giving different tapers to the work, or may be reversed by slotting the lever h beyond its central pivot. A toothed segment l on the lever h engages a pinion m on a shaft n which carries a further pinion o, Fig. 3, engaging a rack on a sleeve p splined in the headstock casing x. A rod q is prevented from moving axially within the sleeve p by means of a collar q<1> and lock nuts q<2> and carries a transverse shaft r which is connected to a shaft u by links s, t. The shaft u forms the fulcrum about which oscillates the yoke v, Fig. 2, which operates the die-head f. When the bracket b engages an adjustable stop d on the rod c the rod is moved forwards with the work-holder and the yoke v is rocked to open the die-head slowly and cause a taper thread to be cut. On completion of the threading operation a bracket on the opposite side of the work-holder engages an adjustable stop on a rod pivoted to the hand lever which rocks the yoke v about the shaft u, thereby opening the die-head to disengage the chasers from the work. The cutting size of the die-head may be varied by rotating the rod q through a hand wheel 7, whereby the position of the shaft r on the screwed portion of the rod is adjusted to alter the location of the shaft u, a pointer on the shaft r being visible through an aperture in the headstock to indicate the size. The rod is locked within the sleeve p by means of a hand-operated set-screw 9. For cutting parallel threads, movement of the sleeve p is prevented by a pivoted stop 8 engaging a recess therein and the stop d is moved out of the path of the bracket b. The die-head may be opened at any time by rocking the yoke v about the shaft u by means of the hand lever (not shown), and the die-head may be fed instead of the work-holder.