Patent GB-601030-A (GB)
Abstract: 601,030. Centreless grinding. LANDIS TOOL CO. June 26, 1945, No. 16224. Convention date, July 7, 1944. [Class 60] In a centreless grinder for grinding screwthreads, the work-rest is tilted relatively to the axis of the grinding-wheel at an angle substantially corresponding with the helix angle of the thread to be formed on the workpiece, and the control wheel axis is tilted relatively to the workpiece by an angle substantially equal to the said helix angle, and to the grinding-wheel axis by an angle of double the helix angle. As shown, the work 12 is supported in the throat between a grinding-wheel 15 and a control wheel 35 on the inclined rest 111, The grinding-wheel 15 is driven by a motor in the base 10 and is mounted in a carriage 11 which is adjustably slidable on the base 10 towards or away from the work. Adjustment is effected by a hand wheel 25 through worm, screw and other gearing, or by a handle 29 on a ring which is clamped to the hand wheel 25 by a bolt 30. The carriage may be slightly tilted, i.e. to raise the end of the axis of the wheel 15 remote from the wheel 25, to increase the range of helix angles which may be accommodated in the machine. The wheel 15 is formed with grooves and ridges which differ, as regards form and spacing, from the thread form to be made, this being necessitated by the axes of the work and the wheel 15 being displaced from parallelism by the angle of pitch. The control wheel 35 is driven through belting by a variable voltage motor 37 and may be angularly adjusted, by a screw 48, in a horizontal plane, about a pivot 46, for grinding tapered surfaces, or in a vertical plane through a double pitch angle for effecting an axial feed of the workpiece. The latter adjustment is effected by a screw 77 which bears on a hardened button 76 in a member 75 in a flat guide 66 and pivots the carriage 36, in which the wheel 35 is journalled, in a curved guide 65. The screw 77 is rotated by a socket end and is locked by a pin 83 wedged by a screw 81. The wheel 35 is moved towards and away from the work, along the guides 65, 66, by a hand wheel 88 and a worm connection 86 with a screwed adjusting-shaft 90. A piston 51 in a hydraulic cylinder 50 moves the wheel 35 axially. The wheel 35 may be smooth faced, but for large diameter workpieces it may be ridged and grooved to correspond with the wheel 15. The rest 111 has a work-engaging face which is downwardly inclined towards the wheel 35. The workpiece is held in position, before and after grinding, by guides 112 pivotally mounted on the base 110 and spring-pressed towards the work. The rest is tilted, relatively to the axis of the wheel 15, to the extent of the pitch angle, by screws 122. The wheel 15 is dressed by a crushing-wheel 113, having circular ridges and grooves corresponding to those of the wheel 15, driven at a low speed through a flexible connection by a motor. The wheel 15 may be driven by the crusher or may be independently driven, the surface speeds of the crusher and wheel being synchronized by rheostats. The crusher 113 is cleaned by a brush 240 and is mounted on a sleeve 105 having a keyway connection 106, 107 with a tubular housing 103 which is revolubly adjustable in an axially split housing bracket 102, bolts being arranged to close the split to clamp the housing 103. Adjustment of the housing 103 is effected by a handle inserted in radial holes in the housing head 104. Adjustment of the crusher towards or away from the wheel 15 is effected by a handle inserted in holes 118 in a graduated head 117 of a screw 115, backlash being prevented by a nut member 125 prevented from rotating by a pin 126 and spaced from the main nut 119 by a spring 128. The bracket 102 is adjustable, about a pivot 124, on the main bracket 100 and is clamped thereon by screws 109. Occassional dressing of the wheel 15 by passing a diamond across the surface of the wheel is permitted by mounting a diamond holder on a bracket projecting from the control wheel housing. A crushing tool 113 may by arranged to operate simultaneously on the wheels 15, 35 by arranging it to be positively rotated between the said wheels. A diamond dressing tool 123 for the wheel 35 is removably mounted on one of the guides 112. The electrical system comprises selector switches, rheostats and relays for controlling the individual and collective operation of motors for driving the wheel 15, an oil pump for operation of the cylinder piston 50, 51, a generator for driving the wheel 35, a coolant pump and the crusher. Specification 436,528 is referred to.