Patent GB-1183209-A (GB)
Title: Lapping Machine with Automatic Loading and Unloading Means
IPC: B24B37/34
Filed: 1967-03-15
Abstract: 1,183,209. Lapping. CRANE PACKING CO. 15 March, 1967 [21 March, 1966], No. 12262/67. Heading B3D. [Also in Division F2] Apparatus for loading a circular space with a plurality of substantially identical workpieces having a flat surface to be lapped, comprises: (i) means for supplying to a feed track a plurality of workpieces with their said flat surfaces uniformly oriented with respect to the track, (ii) a plate adjacent the track, said plate having a circular opening therein, (iii) a turntable concentric with said circular opening and adapted to support said plurality of oriented workpieces, (iv) means for rotating said turntable, and (v) means for transferring the workpieces from the track to the turntable. A lapping machine, e.g. for lapping the surface 10, Fig. 1, of sealing washers made of plastic, metal or ceramic and used in rotary mechanical seals, has an annular lap plate 12 rotatable about a vertical axis and formed with a flat upper surface 13 to which lapping compound is applied. The workpieces 14 are confined within a wear ring 15 which conditions the lap plate. A pressure plate 16 loosely fitting within ring 15 and resting upon the upper ends of workpieces 14 is rotatable on the end of a vertical guide bar 17 extending upwardly through a crosshead 18 slidably mounted in a horizontal guide 19. A pick-up rod 23 passes through crosshead 18 and a slot 22 in guide bar 17. One end of rod 23 is threaded into crosshead 18 and secured by a lock-nut 24; this end has secured to it a washer 26. The other end of rod 23 is formed with a head 25. Guide 19 and two other guides 27, 28 identical with it are welded, at 120 degrees spacing, to a drum 29 secured to the lower end of a shaft 34 rotatable in a post 36 forming part of the machine frame. The lower end of post 36 has a peripheral groove 37 partly closed by rings 38, 39 axially separated by a distance slightly greater than the diameter of rod 23 to form a slot through which rod 23 extends, head 25 being retained. In one location an opening 40 is formed large enough to allow head 25 to pass radially outwardly. Shaft 34 is rotated through 120 degrees three times during the lapping cycle so that each of guides 19, 27, 28 will successively register with opening 40, a wear ring 15 and its contained washers being then slid off the lap plate for removal of lapped workpieces and replacement by workpieces to be lapped. The fixed overhead structure 20 of the machine includes spaced vertical crossplates 49, 50, 51, 52 and a bottom plate 53; to the bottom of the latter arc-welded guide bars 56, 57, the adjacent faces of which have grooves 58, 59 in which circular cross-section crosshead 18 is received for sliding movement, this allowing the crosshead to rotate slightly to be selfadjusting during unloading/loading of a wear ring. Cross-plates 49, 50 and bottom plate 53 have slots 60, 61, 62 to permit passage of the upper portion of guide bar 17. The structure carries an hydraulic cylinder 64, the piston-rod 66 of which is secured to an adapter 67 restrained from rotating by a strap (68) secured thereto and extending downwardly between guide bars 56, 57; the strap carries an adjustable switch contact point (70). The free end of adapter 67 has a horizontal slot (71) to receive washer 26 of rod 23 when drum 29 is in one of its indexed positions. A casting (73) secured to the machine base (41) has secured thereto a rectangular base-plate 75 having circular openings 76, 77, 78. Slidable on base-plate 75 is a slide 79 having circular openings 80, 81 connected by a slot (190). Slide 79 is moved into either of two alternative positions by an hydraulic cylinder 88. Immediately above opening 77 in base-plate 75 is a vertically adjustable platform 92. A notch 194 in platform 92 accommodates a flipper plate 100 having a side 101 contoured to fit closely the circular edge of lap plate 12. Plate 100 is pivoted to platform 92 and is movable by a cylinder 103 between positions in which side 101 is above and below lap surface 13. Platform 92 has a circular opening 195 slightly larger in diameter than the internal diameter of a wear ring 15 and therefore larger than the diameter of a pressure plate 16. An elevator disc 105 concentric with openings 195, 77 is vertically movable by an hydraulic cylinder 181 between a position (Fig. 5) in which it is within opening 195 with its upper surface coplanar with the upper surface of platform 92 and a position (Fig. 7) in which it is within opening 77 with its upper surface coplanar with the upper surface of base-plate 75. A turntable 110 is disposed in opening 76 with its upper surface coplanar with the upper surface of base-plate 75 and is driven by a motor 114. Workpieces are dumped indiscriminately into a vibrating feed hopper 116 by which they are oriented with the surface to be lapped lowermost and made to slide by gravity down a shoot 117 to a star wheel 118, driven by a motor 122. Star wheel 118 has curved notches 119, 120, is mounted above turntable 110 and slightly overlaps it; as star wheel 118 rotates workpieces are brought over, and drop on to turntable 110. To avoid excessive tipping of the workpieces, the track 137 along which they are pushed by star wheel 118 has at its exit end a downwardly sloping portion (138) followed by a downwardly sloping portion (139) of slide 79. A fixed deflector 140 moves workpieces already on the turntable radially inwardly to ensure a vacant space on the perimeter to receive the next workpiece. A counter 142 is provided in association with star wheel 118 and when a predetermined number of workpieces has been fed to turntable 110 rotation of star wheels 118 and turntable 110 stops. For indexing guides 19, 27, 28, shaft 34 has keyed thereto a gear 146, Fig. 11, adapted to mesh with a gear 147 slidably keyed on a shaft 148 oscillated by an hydraulic motor 150. Gear 147 is embraced by a plate 151 and retainer 155, both mounted on a rod 197 moved vertically by an hydraulic cylinder 154. Shaft 148 makes a forward movement of 240 degrees with gear 147 meshing with gear 146, whereby the latter is turned through 120 degrees. Rod 197 is then moved upwardly so that gear 147 is disengaged from gear 146 and teeth (161) on plate 151 which mesh with teeth (160) on a fixed rack 158 now also mesh with gear 146, whereby the latter is held against rotation while shaft 148 makes its reverse movement of 240 degrees. Adjustable stop screws ( 166, 167) co-operate with a pin (168) carried by gear 147 to provide limits for the oscillation. Switches 171, 172 are actuated by adjustable screws on an arm 170 on the shaft of the hydraulic motor. Limit switches 174, 175 are actuated by adjustable screws (178, 179) on an arm 176 secured to the piston-rod of hydraulic cylinder 154. Operation.-With workpieces in hopper 116 and shoot 117, motors 114, 122 are started to rotate star wheel 118 and turntable 110; when a predetermined number of workpieces have been loaded on to turntable 110, counter 142 causes motors 114, 122 to stop. When the timing cycle of a machine times is completed, the timer (a) stops lap plate 12, (b) energizes cylinder 103 to lower flipper plate 100 below lapping surface 13 and (c) energizes cylinder 64, whereby crosshead 18, guide bar 17 and pressure plate 16 are moved to the right (Fig. 5) to bring wear ring 15 and contained lapped workpieces on to plate 92; at the end of the movement, wear ring 15 is concentric with opening 195 in platform 92 with the workpieces resting on elevator plate 105 which is in its raised position in opening 195. Cylinder 181 is energized to lower elevator plate 105 into opening 77 in base-plate 75. Descent of pressure plate 16 is arrested when rod 23 contacts the upper end of slot 22 in guide bar 17. When elevator plate 105 reaches its lowered position, cylinder 88 is energized to move slide 79 to the left (Fig. 7). The workpieces in opening 81 in slide 79 are scraped from elevator plate 105 into opening 78 in base-plate 75 and fall on a dump trough 187; any workpieces adhering to pressure plate 16 are scraped off by a semicircular scraper 182 secured to slide 79 around opening 81. Unlapped workpieces in opening 80 of slide 79 are transferred from turntable 110 to elevator plate 105. At the end of movement of slide 79 to the left, cylinder 181 is energized to raise elevator plate 105. At the end of the raising movements (a) cylinder 88 is energized to return slide 79 to its right-hand position (Fig. 7), (b) cylinder 103 is energized to raise flipper plate 100 above the lapping surface 13 and (c) cylinder 64 is energized to move crosshead 18, guide bar 17 and pressure plate 16 to the left (Fig. 5) to bring wear ring 15 and contained unlapped workpieces on to lap plate 12; at the end of the stroke the next lapping cycle is started and hydraulic motor 150 is caused to make its forward stroke, at the end of which cylinder 154 is energized to raise rod 197, motor 150 is caused to make its return stroke. The parts are reset to repeat the indexing of guides 19, 27, 28 upon the reloading and placing of the next wear ring or lap plate 12. When slide 79 returned to its right-hand position it actuated a switch 192 to reset counter 142 and start motors 114, 122, whereby turntable 110 is reloaded. If an insufficient number of workpieces is available or any element fails to complete its movement, the apparatus is automatically disabled.