Patent GB-431471-A (GB)
Title: Improvements in or relating to centreless lapping machines
IPC: B24B5/18
Filed: 1933-12-05
Abstract: 431,471. Grinding. CINCINNATI GRINDERS, Inc., 3058, South Street, Cincinnati, Ohio, U.S.A.-(Assignees of Theler, F. J., Johnston, G. V., and Peaslee, W.) Dec. 5, 1933, No. 34167. Convention date, Dec. 5, 1932. Addition to 416,165. [Class 60] A centreless grinding-machine for treating simultaneously a number of portions of a piece of work, for example, the bearings and a flange on a cam shaft, comprises two spindles, one carrying a number of grinding- wheels and the other a number of control-wheels, the spindles being spaced apart so that the peripheries of the grinding and control-wheels are a distance apart less than the diameter of the work, whereby this is supported by the peripheries of the wheels. The difference in speed between the surface of the work and that of the grinder is much lower than in usual grinding, whereby a lapped surface, substantially free from ridges and grooves is produced. The machine comprises a bed 15 upon which are mounted a lapping-head 18 and a control-head 19 carried by guides 23, 24 angularly adjustable about pivots 25, 26, the heads being adjustable along the guides by screws 33, and secured by clamps 39. The head 18 comprises a housing 40 having thereon a plate 41, a wheel carriage 42 being pivoted to the plate 41 by a pin 66, and adjustable thereabout by a screw 68 and adapted to be clamped in adjusted position by bolts and slots, whereby the axis of a spindle 44 carried in ball bearings 47, 48 in arms 45, 46 of the carriage 42 may be set at any desired angle to the horizontal. On the spindle 44 is a collet 49 carrying lapping-wheels 50-52, spaced by sleeves 53, 54 and clamped by a shoulder 55 and a nut 56. The controlling head 19 has a housing 70 provided with a plate 71 against which is mounted a carriage 72 in which is a groove 77 receiving a key 76 integral with a trunnion pin 75 engaging an aperture in the plate 71. The carriage 72 is clamped to the plate by bolts 93, 94 so arranged as to allow of angular adjustment of the carriage about the pin 75 by a screw 90, and lateral adjustment of the carriage across the plate by screws 103, 104. The carriage has arms 78, 79 carrying, in ball bearings 80, 81, a spindle 74 on which are mounted, in the same manner as the wheels 500-52, control wheels 83-85, located opposite to the wheels 50-52. The shaft being treated has thereon a flange 105 and this is lapped on one face by the edge 106 of the wheel 85, and on the other face by a wheel 108 carried by a collet 109 slidably keyed to the spindle 74 and moved to bring the wheel 108 into or out of action by a piston rod 118 carrying a piston 119 movable in a cylinder 120 by hydraulic pressure, spring plungers 112, 113 being interposed between the rod 118 and the collet 109. The plates 41, 71 are tied together, after the heads are adjusted, by rods 130, 131 having thereon nuts 132-134, so that the work rests on the peripheries of the wheels during lapping. The work is brought into contact with the wheels and removed therefrom by loading and ejecting mechanism, which comprises a bracket 138 adjustably secured to the machine bed and carrying a cylinder 140 in which is movable a piston 141, the rod 145 of which is secured to a carrier 146 having sleeves 147, 148 movable on posts 149, 150 on the bracket 138; the posts have therein adjustable screws 151, 152, forming stops for pins 153, 154 on a work engaging rest 155, to which are secured fingers 159, 160 which ensure that the work contacts first with the control-wheels. The work is held down, during lapping by rubber &c. covered rollers 165 carried by arms 163 pivoted to ears 161 on the sleeves 147, 148, springs 168 holding the arms down, and the arms are moved to carry the rollers away from the work, when the carrier 146 rises to work-receiving position, by engagement with stops on the carriage 72. In the bracket 138 is a by-pass valve 176 adapted to be lifted by a spring 186 and lowered by a boss 190 on the carrier 146 ; the valve serves in the lower position to connect the conduit 124 from a port 122 in the cylinder 120 with a port leading to the upper end of the cylinder 140, and when in the upper position to disconnect those ports. The hydraulic circuit of the machine is shown in Fig. 7, wherein 191 is a pump supplying oil to a reversing-valve 195, which is connected as shown to the cylinder 120 and by-pass valve 176, other connections from the cylinder 120 and valve 176 also being provided to cylinder 140. By operation of the valve 195, the wheel 108 is withdrawn from the work and the work is lifted to discharge position, when, by further operation of the valve 195, a new piece of work is lowered onto the wheels and the wheel 108 advanced to operative position. The valve is mounted in a casing 200 on the bed 15 and is moved by a lever 217 which moves an arm connected with the valve. The work is driven at a speed differing only slightly from that of the wheel, and is engaged by the lapping wheels along diagonal lines. In order to drive the spindle, 44, 74 at the required speeds, the spindle 44 is driven by belt and chain gearing 226, 228, 234s 235 from a motor 236 carried by a pivoted bracket 274, adjustable to tension the belts 235, and the spindle 74 is driven from the pulley 234 through a shaft 230 and variable speed gearing comprising double cones 237, 238 and 243, 244, and a chain 241. The cones are separated or approached by pairs of arms 248, 249 pivoted at 252, 253 and connected at their ends to the cones, and at one end also engaging nuts 257, 262 on opposite handed screws 258, 263 on a shaft 264 which may be rotated by a knob 265 or by a sprocket 266 operated through gearing by a handle 271 carrying a pointer 272. Fluid is supplied to the wheels by a pump 279 driven by a belt and mounted pivotally at 280 to tighten the belt.