Patent GB-1040529-A (GB)
Title: Improvement in a center hole grinding apparatus
IPC: B24B5/14
Filed: 1965-04-22
Abstract: 1,040,529. Grinding. H. E. G. ARNESON. April 22, 1965, No. 17136/65. Heading B3D. A spherical centre hole lapping apparatus for generating a spherical zone in a workpiece centre hole comprises a lap member 60, Fig. 1, carried by a spindle 57 mounted in a supporting structure 12 so as to have its axis at an angle to the axis of a workpiece 40, the workpiece being rotatably carried on the supporting structure and being supported in a direction opposed to the spindle. The supporting structure consists of a column 12 upstanding from a base 10 and carrying at its lower end a table 14 which rotatably supports a turntable 31 driven by a belt drive 27 from a motor 23. The turntable has a spherical centre 35 for engaging a centre hole 40a in the workpieee and a clamp 37 transmits rotation from the turntable to the workpieee. The upper end of the workpiece is rotatably supported by a steady rest 42 vertically adjustable on the column 12. The spindle 57 carrying the lap member 60 is rotatably supported in a sleeve 55 universally mounted by gimbals and a ring 51 in the bifurcated end of an arm 18 adjustable longitudinally of an arm 17 mounted on the column, the arm 17 and the table 14 having extensions 17a, 14a engaged by a threaded spindle 20 whereby they are adjustable along the column 12. The spindle 57 carries a pulley 65 connected by a belt drive 66 to a motor 69 mounted on a bracket 70 secured to the ring 51, the bracket being connected by an adjustable spring 75 to the spindle to support its weight. An adjustable weight 82 counterbalances the weight of the motor 69. The lapping tool 60 has a spherical land 60a, Fig. 5 (not shown), and the axis of the spindle and tool can be set at an angle indicated by a pointer 79 secured to the ring 51 and moving over a scale 78 on the arm 18 so that a median line C of the land covers the upper and lower points A, B of the zone to be lapped, the adjustment being effected by moving the arm 18 relative to arm 17. The rotation of the tool effected by the motor 69 is opposite to the direction of rotation of the workpieee driven by the motor 23. In a modification for lapping a spherical centre hole at each end of the workpiece, a bed 90, Figs. 6 and 7 (not shown), carries a baseplate 93 which is adjustable about a pivot 104 and can be secured in position by a bolt 103 in an arcuate slot 102. A second base-plate 97 is similarly adjustable about a pivot 110 and can be secured in position by a bolt 109 in an arcuate slot 107. The pivot 110 and bolt 109 are adjustable along a slot 106 in the bed to vary the distance between the base-plates. A bracket 125 on the base-plate 93 supports a spindle 127 which carries a lapping tool 60, has a ball 129 bearing against a block 131 adjustable along a rod 130, and is connected by a belt drive 137 to the spindle 134 of a flexible drive 120 from a coupling 122 at one end of a motor 113. The coupling is supported in a frame member 116 having an aperture through which the tool 60 and spindle extend to engage the centre hole at one end of the workpiece. A bearing collar 138 in the aperture has a rim 138a serving as a bearing for a pulley 140 driven by a belt 163 from a pulley on the coupling 122, the bearing having driving members 147 engaging a collar 160 secured to one end of the workpiece to effect rotation thereof. The other end of the motor has a coupling 122<SP>1</SP> connected to a flexible drive 120<SP>1</SP> driving a shaft 184 which is connected by a belt drive 188 to a second spindle 167 which is mounted in a bracket 165 on the base-plate 97 and has a lapping tool 60<SP>1</SP> for the spherical centre hole at that end of the workpieee. The spindle 167 is axially movable in the bracket 165 and a weight 182 adjustably carried by a rod 180 acts through a member 178 on the end of the spindle 167 to urge the lapping tool 60<SP>1</SP> against the centre hole at its end of the workpiece, the centre hole at the other end of the workpiece being pressed against the lapping tool 60 on the spindle 127, the axial thrust of the spindle being taken by the ball 129 engaging the block 131. The motor 113 drives the workpiece in one direction of rotation and the lapping tools in the opposite direction.