Patent GB-1475840-A (GB)
Title: Lapping machine
IPC: B24B37/08
Filed: 1975-04-02
Abstract: 1475840 Lapping PRECISIONLAP Ltd 30 March 1976 [2 April 1975] 13556/75 Heading B3D A machine for lapping one or more workpieces comprises two generally parallel lap plates 6, 8, Fig. 1, means for moving at least one workpiece between the plates for lapping thereof, means 18 for separating the plates, and means formoving one of the separated plates generally parallel to the other to expose the workpieces for removal thereof from the machine. The lower lap plate 8 is secured by screws 9 to a support plate 10 and coaxially aligned by a locating ring 11, the support plate 10 being attached to a main frame 4. Workholders (not shown) in the form of flat discs having toothed peripheries are orbital between the discs by engagement of the discs with an outer, fixed, pin ring 13 and an inner pin ring 14 mounted on a shaft 16 rotated by a worm drive 17 and motor. The upper lap plate 6 is located by a ring 7 on an upper support plate 5 having an upstanding shaft 22 which extends through an aperture 25 in a lift arm 24 and has a lip 26 which engages the worm so that the upper lapping plate is lifted when the lift arm is raised by rotation of the handle 23 of a screw jack 18 on a post 19. The post is located in a cup 20 fixed to the frame 4 so that, after lapping and raising of the upper lap plate a short distance, e.g. 0�005 inch, the arm and upper lapping plate can be swung about the axis of the post to expose the workpieces for removal from the lower lapping plate. An abrasive slurry is applied, for example, through holes in the upper lapping plate, between the lapping plates during lapping and drains into a sump 29 for recirculation by a pump. A segment (30, Fig. 2, not shown) to which is attached a portion of the outer pin ring 13 is removable to permit insertion and removal of the workholders. Resurfacing rings may be inserted between the lapping plates to renovate the lapping surfaces. In another embodiment, the lower lapping plate 8 is mounted on a plate 31 keyed to the shaft 16 of the worm drive 17, the plate 31 also being adjustable secured by screws 36 to a plate 32 carrying the inner pin ring 14. A stub shaft 33 is secured to the plate 32 and has a transverse pin 35 for engagement with slots 49 in a drive boss 46 carrying the support plate 41 for the upper lapping plate 6 so that both the upper and lower lapping plates and the inner pin ring are rotated during lapping. The stub shaft 27 is rotatably mounted in the boss 46 and passes through the aperture in the lift arm 22, a spring 60 being disposed between the arm and flange 26 whereby adjustment of the height of the arm varies the pressure acting between the lapping plates. Abrasive slurry is supplied between the plates from a trough 50 and apertures 51 in the support plate 41. The outer pin ring 13 and plate 32 carrying the inner pin ring 14 and stub shaft 33 can be removed to enable the lapping plates to be disposed with their axes eccentric to one another and so that when the lapping surfaces are engaged with one another and the lower lapping plate rotated to impart rotation to the upper lapping plate the lapping surfaces are renovated by mutual abrasion.