Patent GB-580741-A (GB)
Title: Apparatus for grinding or polishing worms of worm gearing
IPC: B23F13/04
Filed: 1943-08-10
Abstract: 580,741. Grinding and polishing worms. MICHIGAN TOOL CO. Aug. 10, 1943, No. 12910. Convention date, Feb. 22. [Class 60] The thread sides of an area contact type of worm are ground or polished by an endless belt, carried by a table rotatable about an axis coinciding with the axis of a worm wheel with which the worm is adapted to mesh, and pressed into contact with the side of the thread of the worm, which is rotated at a speed corresponding to the rotative movement of the table. The machine comprises a base 10 having a standard 12 provided with a guideway 16 on which are mounted adjustably a headstock 18 and a tailstock 20 for the spindle of the worm 22 to be treated. A standard 24 also is provided adjustable on ways 26 on the base to carry the grinding or polishing means 30, which is capable of oscillation with respect to the standard 24, and is mounted upon a, top table 32 having thereon two members 36, 34 for adjustment in perpendicular directions by screws 44, 40. The member 34 has an upstanding portion 46 terminating in a recess 48, which receives a, tubular post 50 on which slides a sleeve 52, urged upwardly by a spring 56 in the post 50, and adjustable by rack gearing 58, 60, 62 and lockable by a screw. On a bracket 64 on the sleeve 52 is pivoted a plate 66, carrying a motor 70, and pivoted at its free end to a toggle linkage 72, 76 pivoted at its lower end at 82 to the sleeve 52, the linkage being acted upon by tension springs 86, and operated by movement of link 72 to lower the plate 66 for exchanging the polishing belt ; the link 76 is of adjustable length. The motor 70 carries a pulley 88 receiving the abrading-belt 90, the lower end of which runs round a pulley 92 carried by a bracket 96 mounted by a split collar 98 and bolt 99 on a tubular member 102 secured to the standard 46. In the member 101 is mounted a cylindrical member 110 having at one end a recess to receive a removable pencil spindle 112 secured by a screw and having its outer end of reduced diameter to engage the inside of the belt 90 to press it against the worm ; the width of the belt and length of the reduced end of the spindle 112 are substantially the same as the face depth of the worm thread. The belt is guided at the correct helix angle by rollers 114, 116 respectively on opposite sides of the spindle 112 carried by a member 118 adjustable angularly on the member 101 and locked in position as determined by a scale on member 101 by a bolt 124 ; the rollers are set so that the entering and leaving portions of the belt are at a small angle to each other. The table 32 is mounted on and interconnected to a table 126 so as to oscillate therewith, but with allowance for movement relative thereto, the table 126 being rotatably mounted on the standard 24 and driven by a spindle 128, and the table 32 being mounted on table 126 by roller bearings 134. A resilient connection is provided between the tables 32, 126 comprising depending members 138 on the table 32 bored to contain springs 142, which press cup-shaped members 146 one on each side of an arm 150 carried by table 126. The relative movement between the tables 32, 126 is employed when treating worms having relieved portions, and may, for other worms, be put out of operation ; the movement is produced by a bell crank lever 160 pivoted to the member 150 and having one arm connected by a pin 164 and a block 166 to a member 167 secured beneath the table 32, the lever 160 being actuated at appropriate times by cam plates 172 which engage a roller 170 on the other arm of the lever 160. The plates 172 are rotatably adjustable by wormgearing operated by knobs 194 on base plates 174 adjustably fixed on the standard 24 by bolts 178 and a slot 176 in the standard, and may be set either to engage the roller or out of the path thereof. The worm 22, and the spindle 128 are driven in synchronism by a reversible and variable speed motor 150<1>, the drive to worm 22 being through a shaft 200 connected to the motor through change gears 210, 212, 214, 216, and the spindle 128 is driven through worm gearing 202, 204 by a shaft 206, which is driven through change and reduction gears 218, 220, 224, 226, 228, 230, and a gear 232 keyed to a shaft 234 in line with shaft 206. The shafts 234, 206 are connected through a differential gear 236 whereby the belt may be side fed to remove the desired amount from the worm ; the gear 236 includes gears 242, 244 with nearly the same number of teeth and an engaging gear 246 which moves round the shafts with a casing 240, such movement being effected by worm gearing 248, 250 and a shaft 252 driven, through worm gearing 254, 256, by a motor 152; hand drive may be effected, on disconnection of a clutch 258 in the shaft 252, by a wheel 260a. In operation, the tables 32, 126 are oscillated, the oscillation being controlled by a limit switch LS1 engaged by arms 260, 262 adjustably mounted on the table 126, the worm. 22 being rotated so that the abrading belt 90 moves forwards and backwards along the worm, rotation of the worm and belt being reversed at the ends of the movements of the tables. The extent of side feed is controlled by limit switches LS2, LS3, LS4, actuated by a nut 270 on a screw 272 driven by the motor 152<1> through gearing 274, 254, 256. Specifications 555,829 and 580,747, [both in Group XXIV], are referred to.