Patent GB-535057-A (GB)
Title: Improvements in or relating to metal cutting machines
IPC: B23B9/02
Filed: 1939-08-15
Abstract: 535,057. Combined turning, drills, and screwing machines. BILLINGS & SPENCER CO. Aug. 15, 1939, No. 23543. Convention date, Aug. 23, 1938. [Class 83 (iii)] Screwing-die heads.-A lathe operating on bar stock has a number of work spindles each cooperating with a pair of similar tools located on opposite sides of the spindle and mounted on a single transverse slide which presents the two tools to the work by movement in opposite directions. In a two-spindle machine, the spindles 22 are mounted in a headstock 21 and are driven from a central shaft 41 through gears 39. The shaft 41 is enclosed by a tube 48 carrying a gear 47 which drives a cam shaft 45 carrying a cam drum 31 provided with two similar pairs of cams for actuating the feed fingers 28 and collet 27 of each spindle, the two stock bars being fed simultaneously. A transverse tool slide 23, actuated by a cam 51 on the shaft 45, carries tool posts 90 provided with a pair of similar adjustable tools 88, 89 for each spindle. The shaft 41 is driven from the motor driven pulley 54 of a gear box 20. In order to drive the tube 48 at low speed for the stock feed and other operations a sprocket driven from the pulley 54 is mounted on a spider carrying planet pinions engaging with a fixed gear and with a gear having a different number of teeth on the tube 48, the differential gearing thus imparting a slow rotation to the tube 48. The latter also carries a cam drum 63 provided with a cam 64 operating an axial tool slide 24. The stock feed is determined by a swinging stop lever 50 mounted on a sleeve 68 rotatable on the tube 48. The stop lever is rocked between operative and inoperative positions by a cam slot in a slide block 73 actuated through a connecting rod 75 from a cam on the drum 63. The slide block is guided in a member 74 secured to a stationery sleeve collinear with the tube 68. The axial tool slide carries a drill 84 and finish-turning tool 85 for each spindle. The carrier 24 reciprocates forward and back for each cycle while the slide 23 moves through a single stroke only, the tool 88 acting on one cycle and the tool 89 on the succeeding cycle. The tools 88, 89 may each be a combined forming and cutting- off tool as shown in Fig. 15, the extension 94 performing the cutting-off. The tooling is effected at two zones X and Y, Fig. 15. In starting the machine the work is first advanced to the Fig. 14 position and formed by the tool 89 the advance of the tools 84, 85 on this cycle being ineffective. At the next feed which brings the work against the stop 50 the work assumes the Fig. 15 position where the partly formed piece at Y is bored and finish turned and the piece at X formed by the tool 88 which finally cuts off the piece Y. This cycle is then continued, a piece being completed at each spindle for each single stroke of the transverse slide. The feed is timed to occur when the tools 88, 89, are both away from the work (mid position of the tool slide) and the tools 84, 85, are withdrawn. The tools 84, 85, may be omitted if boring and finish turning is not required. In a modification, particularly for producing threaded pieces a self opening die-head is employed. The die-head 100 may be adapted to produce double taper threads in making pipe nipples and replaces the tools 84, 85. Opening of the die is effected by a collar 101 engaged by a yoke 102 slidable over a threaded rod 103 supported by a cross head 104 carried by support 74. The die is advanced to the work by the carrier 24 and to open or 'close the die the yoke 102 coacts with nuts 105, 106 on the rod 103. As the yoke 102 engages stop 105 the die is opened. The tool carrier then moves backward, the die remaining open while the lost motion between stops 105, 106 is taken up. When the stop 106 is encountered the die head is again closed. For double taperthreading, a sleeve 108 on the die controlling the chasers carries a roll engaging a cam slot 110. Fig. 13, which is arranged so that the dies are gradually expanded to cut one taper and then gradually contracted to cut the reverse taper. Except that the die head replaces the tools 84, 85, the manner of operation is similar to that described above, a complete article, Fig. 17, being completed at each reciprocation of the axial tool slide corresponding to a single stroke of the transverse slide. U.S.A. Specification 1,892,239 is referred to.