Patent GB-834037-A (GB)
Title: Flat surface grinding machine
IPC: B24B7/16
Filed: 1956-10-29
Abstract: 834,037. Grinding, dressing grinding wheels. MICROMATIC HONE CORPORATION. Oct. 29, 1956 [Nov. 28, 1955], No. 32971/56. Class 60. A flat surface grinding machine comprises means to advance a plurality of workpieces through a working gap, constituted either by a pair of abrading wheels with oppositely disposed working faces in substantially parallel planes or by a single abrading wheel having its working face substantially parallel with the face of a workpiece support, sensing means responsive to variations from a predetermined thickness of workpieces leaving the gap and adjustment means responsive to the sensing means for axially adjusting one of the wheels or the wheel to adjust the size of the gap. A shoot 21 feeds workpieces 23 into apertures 19 of a feed disc 17 which conveys them through the working gap between upper and lower abrading wheels 27, 29. As they leave the working gap the workpieces pass a sensing means, e.g. a thickness gauge 31, having normally open contacts. So long as these contacts are open, a gate 175 remains open so that workpiece can drop on to a take-off conveyer 33. Closure of the contacts by an oversize workpiece operates a fluidpressure cylinder 177 or a solenoid which closes the gate so that the workpiece again passes through the working gap. The wheels 27, 29 rotate in the same direction at slightly different speeds. The lower wheel 29 is carried by a member 53 rotated about a stationary post 65 by worm gearing 39, 41 from a shaft 37 driven through V-belts from a motor 35. The upper wheel 27 is carried by a shaft 67 driven through worm gearing 49, 51 by a shaft 47 belt driven from the shaft 37. The shaft 67 has a splined connection with the worm wheel 51 to permit vertical movement of the shaft. Coarse vertical adjustment, e.g. for replacing the wheels, for set-up to accommodate workpieces of different size for a new operation and for intial dressing, is effected by a pinion 73 meshing with a rack 75 on a sleeve 77 in which the shaft 67 rotates. The pinion 73 is rotated by a rack 79 connected to the piston rod 81 of a fluid-pressure cylinder 83. Fine vertical adjustment is effected by a wedge 87 on which ride rollers 85 on the lower end of the sleeve 77. The wedge is supported on rollers 89 and is movable by a screw 91. This can be rotated by handwheel 93 and is also rotated automatically by a motor 95 through gears 97, 99, magnetic clutch 105, and gears 101, 103. The magnetic clutch 105 is controlled by a switch 107 controlled by a cam 109 on the shaft of motor 95 and having an adjustable lobe 111 which during each revolution of the cam releases follower roll 113 to close the switch 107, so energizing the clutch. The switch 107 is in circuit with the sensing means 31, so that adjustment is responsive to the sensing means. The feed disc 17 is rotated intermittently by a Geneva movement including a cam wheel 117 on a shaft 119 driving, through gears 121, 123, the feed disc spindle 125. The wheel 117 is engaged by pin rollers 129 on a wheel 127 secured on a shaft 128 driven, through worm gearing 131, 133 from a shaft 135 driven through V-belts by a motor 137 including a variable speed drive ; the shaft 128 also drives the link chain conveyer 33 which carries away workpieces after ejection from the feed disc. The arrangement is such that no two workpieces occupy the same annular zone of abrasion ; this is stated to minimise the need for dressing the wheels. Alternatively, the feed disc may rotate continuously. The feed mechanism is vertically adjustable, being carried by a supporting block 149 engaged with an adjusting screw 145 disposed within a post 147. To minimise bending of the post 147, additional support is provided under the feed disc shaft 125 by a block 151 carried by a screw 153 driven from the screw 145 through gear 143, helical-toothed shaft 155 and gear 157. Vertical adjustment can be effected manually by an handwheel 181 (not shown) and is effected automatically, so as to maintain the feed disc 17 in mid-position between the abrading wheels, by a motor 139 operating the screw 145 through gears 141, 143. A follower roll 159 riding on the upper face of the lower abrading wheel 29 is rotatably carried by a housing 162 mounted on a base 161. The base 161 is floatably carried and partially counterbalanced on guide pins 163, 165. A member 167 secured to base 161 forms part of a circular track 176 mounted on the supporting block 149 and extending beneath the workpieces from the exit end to the entrance end of the working gap, the member 167 representing a break in the track just before the entrance end of the working gap and serving to retain workpieces in the apertures in the feed disc in their final travel toward the gap. As the member 167 moves downward in response to wheel wear a switch 169 carried thereby is closed, to energize the motor 139, by a trip arm 171 mounted on the track 176. The supporting block 149 thus moves down until the switch 169 opens whereupon adjustment ceases. The feed disc 17 can be withdrawn from the gap between the abrading wheels by swing- ing the supporting block 149 about the post 147, so permitting replacement of the abrading wheels and initial dressing. Initial dressing of the abrading wheels is performed by means 183 which can be swung into and out of operative position and comprises diamond tips 191 above and below a block 189 mounted on guide bars 185, 186 ; the means includes a motor 184.