Patent GB-985552-A (GB)
Title: Improvements in or relating to the feeding of work-pieces for lapping machines
IPC: B24B37/34
Filed: 1960-10-10
Abstract: 985,552. Lapping. PAYNE PRODUCTS INTERNATIONAL Ltd., and J. A. LUCK. Jan. 10, 1962 [Oct. 10, 1960], No. 34695/60. Heading B3D. Apparatus for loading workpieces on to a lapping machine comprises a work-table beside the lapping plate and a rotatable work-feeder mounted to swing above the work-table close to the lapping plate and having at least one bracket-arm to engage a conditioning ring, the bracket-arm being long enough to move the conditioning ring across the table on to the lapping plate, when the work-feeder is swung towards the lapping plate so that the conditioning ring, with any work which it may contain, can be held in lapping position upon the lapping plate until lapping is completed. A lapping machine comprises a horizontal lapping plate 13 carried on a driving spindle supported by a vertical journal bearing in a base 11. On the latter is supported a substantially horizontal work-table 14 partly surrounding the lapping plate and fitted closely thereto at approximately the same level. A vertical spindle 15 journalled in the work-table has secured thereto a work-feeder 16 comprising bracket-arms 17, 18 of such length that their outer ends can, by rotation of the work-feeder, be brought to overlie the lapping plate. Each arm is cut out circularly to receive on its hollow side a conditioning ring 19 and carries a roller 20 to engage the periphery of the ring. When the work-feeder is swung into a position where one bracket-arm delivers a conditioning ring above the lapping plate then the other bracket-arm will hold a second conditioning ring above the work-table, so that while workpieces rotated in a work-holder within the conditioning ring above the lapping plate are being lapped, workpieces can be loaded into a work-holder located within the conditioning ring which is above the worktable. On the side whence conditioning rings are delivered to the lapping plate the worktable is slightly higher than the lapping plate surface and on the side where conditioning rings are delivered from the lapping plate the worktable is slightly lower than the lapping plate surface, the two levels of the table being joined by a ramp 21. The work-feeder 16 could be rotated by hand but preferably the spindle 15 is rotated at intervals by a gear-box 22 capable of rotating it through half a revolution at a time. The lapping machine has space for three conditioning rings to operate simultaneously upon the lapping plate so that to keep it fully occupied three rings must be in working position at a given time and other rings in preparation in loading position on the work-table. This could be effected (a) by having three independently operated work-feeders located equidistantly round the lapping plate, or (b) by having a single work-feeder with two arms each of which is shaped to engage three conditioning rings; in the latter case the lapping plate must have no central aperture 23 through which workpieces might drop or, if there is a central aperture, it must be filled up e.g. by a metal sheet set slightly below the level of the plate. Preferably, however, the work-feeder 16 delivers the rings 19 in turn to arms 24, 25, 26 which receive and hold the rings above the lapping plate. The arms 24, 25, 26 have adjustable portions 64, 65, 66 carrying rollers 67 for engaging the conditioning rings and are carried on a hub 27 mounted on a splined spindle 28 coaxial with the lapping plate and carried on an overhanging arm 29 supported by a column 30 from the base 11. The arms 24, 25, 26 are carried round one third of a revolution at a time by the drag of the lapping plate. At each movement a conditioning ring with its load of finished workpieces is discharged from the position 19a on to the worktable and then the work-feeder 16 is rotated through half a revolution to deliver a new conditioning ring with its load of workpieces to be lapped on to lapping plate. A gear 31 on the spindle 28 is geared in the ratio of 3 to 2 to a gear 32, on a spindle 33, carrying a crank 34 connected to the piston rod 35 of a dash-pot 36 pivoted at 37, the ends of the dash-pot being connected by pipes 38 to a regulating needle valve 39. A vertical rock shaft 43 carries a lever 44 connected to the core 45 of a solenoid 46 and acted on by a return spring 47. The rock shaft 43 carries a cam lever 49a which bears on a cam 49 on the spindle 28, the cam having three equidistant notches 50 into any of which the cam lever 49a can enter to prevent rotation of the spindle 28. When the solenoid 46 is energized the cam lever is disengaged from a notch and rotation ensues under the control of the dash pot. The spindle 33 rotates half a revolution for each one third revolution of the spindle 28 and has secured thereto a bush 51 carrying circumferentially adjustable cams 52, 53 cooperating with microswitches 54, 55. The microswitch 55 de-energizes the solenoid 46 just before the termination of the one third revolution movement and the microswitch 54 energizes a control valve for cylinders 60 which determine the rise and fall of weights 40 for bearing on the workpieces in the conditioning rings, the weights being rotatably mounted on the rods of pistons in the cylinders. The cylinders 60 are mounted on radially adjustable slides 61. Prior to movement of the arms 24, 25, 26 the weights 40 are raised out of the conditioning rings by supplying pressure oil to the cylinders 60 through pipes 70; the release of the pressure is effective under the control of the microswitch 54. Mounted above the work-table 14 is an arm 71 carrying a roller 72 above the lapping plate at a position nearer the centre thereof than the centres of the conditioning rings upon the lapping plate. The arm 71 is secured on a shaft 74 extending through bearings 75, 76 in the machine base, a spring 77 yieldably maintaining the arm in the position shown. When a conditioning ring on the lapping plate comes into the position 19a and the spindle 28 begins to make a further part of its rotation, the ring will be deflected by the roller R on to the worktable. When the work-feeder 16 rotates the other side of the roller 72 will catch the ring which is delivered on to the lapping plate and tend to deflect it into the hollow space of that arm 24, 25 or 26 which is waiting to receive it. The work-table 14 is mounted on a box 86 supported by a box 81, the box 81 being adjustable on guides 80 on the base 11 by a screw operated by a hand wheel 85 so as to permit the work-table to be kept at the correct height relatively to the lapping plate as the latter wears. The gear-box 22 for driving the spindle 15 is carried in the box 81. The box 86 is divided into main chambers 88, 89. The portion 14a of the work-table from which rings are delivered on to the lapping plate has secured to its underside bushes 92, 93 sliding on columns 90, 91 secured to the bottom of the chamber 89. A gear 98 on the spindle 15 drives, through idler gear 97, a gear 96 to which is secured a face cam 99 rotating in contact with a cam 100 secured by a casting 102 to the underside of the worktable 14a. The face cams have four equally spaced lift portions and the gear ratio between the gear 98 and the gear 96 is 2: 1 so that the table portion will be lifted twice for each revolution of the spindle 15 and as the work-feeder 16 is operated once for each half revolution of the spindle 15 the table portion will be lifted each time the work-feeder is operated. Return of the table against the operation of the cam is effected by a spring 103. Lubrication is effected by a grease nipple 105 on the column 91, by a pipe 106 to the column 90 from a grease nipple 107 on the box 81, and by a pipe 108 on the casting 102 from a grease nipple (not shown). The gear 96 carries projections 110, 111 actuating micro-switches 114, 124. The timing of the cams 99, 100 is such that when the spindle 15 starts to rotate the work-feeder 16 to feed a conditioning ring 19 on to the lapping plate the table section 14a is lifted above the lapping surface, when the ring 19 is fully on the section 14a. When the ring has been partly fed on to the lapping plate 15 the extent that about half of the first of the workpieces which it contains projects above the lapping plate the table section 14a is lowered to be level with the lapping surface. In use, the operator actuates a push button initiating movement of the spindle 15 and feed of a conditioning ring on to the table. When the feeding movement is completed the microswitch 55 de-energizes solenoid 46. A time switch determines the period during which lapping proceeds with the parts in the positions thus reached. The time switch then operates the electromagnetically controlled valve causing pressure oil to be delivered to the pipes 70 so that the weights 40 are lifted. When the weights are lifted one of them operates a microswitch in casing 116 and re-energizes the solenoid 46 thus unlocking the cam 49 and allowing the condition ing rings with the spindle 28 to be rotated through one third of a revolution. Thereupon the weights are again lowered and when the operator is ready and again actuates the push button the further ring is fed on to the table and the cycle recommences. The micro-switches 114, 124 are included in the circuit controlling the weights 40 and ensure that they cannot be raised until the table section 14a has been lowered and cannot be lowered until the table section 14a has been raised. The work-table is partially surrounded with upstanding walls 117, 118.