GB147683A - Improvements in or relating to thread milling machines - Google Patents

Abstract

147,683. American Multigraph Co., (Assignees of Trundle, G. T.). Oct. 11, 1915, [Convention date]. Milling screws; chucks.-A thread-milling machine, particularly adapted to cut external threads on screw plugs &c. has two parallel work-spindles, and the cutter, which has a small longitudinal movement during the cutting operation is moved transversely from one spindle to the other to act in succession on the respective blanks. The hollow work spindles 20 are driven by worm gearing from a driving shaft 11, and each has a conical recess 28, Fig. 6, engaged by the head 31 of a collet 30. The collets are operated to clamp and unclamp the blanks by rods 32 controlled by levers rocked alternately by a cam on a longitudinal shaft 40 driven by a worm 29 on the driving-shaft. An abutment 155, rigidly fixed to the head 141 of each spindle and passing through a notch in the collet, ensures uniform positioning of the blanks. The cutter spindle 90 driven from a pulley 96 is mounted on a casing 81 sliding transversely on ways carried by a longitudinal slide 71.- The cutter spindle is moved longitudinally by an amount, depending on the pitch of the thread to be cut, by means of a grooved cam on the shaft 40 which co-acts with a roller 101 on a stud carried by the slide 71. The transverse movement of the cutter spindle is limited by abutments 130, and is controlled by a cam 110, the rollers 111 being positioned after the abutments have been adjusted to give the correct depth of cut. In operation, the cutter is moved longitudinally away from the head a of the rotating blank and the thread completed. The cam 110 then feeds the cutter towards the other spindle, and simultaneously the return longitudinal movement is effected, thus positioning the cutter to operate on the second blank. As soon as a blank is completed, it is released by the forward movement of its collet and a fresh blank is inserted by hand.