GB522837A - Improvements in machines for cutting threads and the like on work pieces - Google Patents

Abstract

522,837. Grinding &c. screw threads &c. SHEFFIELD GAGE CORPORATION. Dec. 19, 1938, No. 36909. Convention date, Jan. 15. [Class 60] [Also in Group XXII] A machine for cutting screw threads or other helical grooves comprises a frame 10 carrying a table 11 on which is mounted a slide 27 carrying a slide 15 having arcuate surfaces 16 thereon to support, in angularly adjustable position, a head 14 carrying a grinding-wheel 13. The wheel is driven by a belt 18 from a pulley 19, 20 carried by a bracket 23 adjustable to tension the belt, by a screw 24 pivoted at 25 to the slide 27. The work 30 is carried on a longitudinally movable slide 34, by a tailstock 32 and a headstock 36, the work-engaging centre 38 of which is carried by a shaft 43 running in antifriction bearings' 41, 42 and driven by an electric motor 53 through a coupling comprising a sleeve 48, driving through speed reducing gear 52 by the motor and having therein slots slidably engaged by lips 50 on a connection 46 carried by the shaft 43. In order to move the slide 34 at a speed corresponding to the lead of the thread being cut, the headstock has thereon transverse guides in which is slidable a carriage 57 having a horizontal wall 58 provided with supporting surfaces 68 and arcuate slots 69. The carriage 57 is moved in the guides by a rack 63 on the carriage driven through a pinion 64 and a wormwheel 65, by a worm 66 on the shaft 43. On the surfaces 68 a bar 73 rests, the bar being clamped in angularly adjusted position by studs engaging the slots 69, and having rectangular heads 71 fitting in slots 72 in the bar 73. The transverse movement of the bar 73 with the carriage 57 produces longitudinal movement of the slide 34 with the work thereon by the engagement of the bar 73 with a block 78 pivoted at 76 to an arm 75 secured to the slide carrying the motor 53 ; the block 78 has downwardly extending sides between which and the bar 73 are balls 82 carried by cages 83, and engaging grooves in the sides and the bar, the groove on one side being provided in a member adjustable to take up wear. The bar 73 is set to the desired angular position by gauge blocks inserted between posts 86 on the bar and surfaces 87 on the carriage 57. In order to grind threads on tapered work, the grinding-wheel 13 is moved slowly inwards as the work 30 moves axially past the wheel. This movement is produced as described in Specification 522,888.