Patent GB-753960-A (GB)
Title: Improvements in machines for the manufacture of polishing buffs
IPC: B24D13/12
Filed: 1954-08-17
Abstract: 753,960. Making polishing buffs. TREVENNA, G. R. Aug. 17, 1954 [Aug. 19, 1953; Dec. 31, 1953], No. 23938/54. Class 60 A machine for assembling polishing buffs comprises means for picking up pieces of material from a magazine and depositing them successively on an assembly table so as to build up the buff thereon, and means for automatirally removing the buff from the table when the build-un is complete. T h e machine is described as applied to the building up of buffs similar to those as described in Specification 683 753 from superimposed layers of cloth, of which each laver consists of a plurality of non-overlapping pieces. The e pieces of material are  stacked in a series of compartmented magazines 34. Figs. 1 and 6, circularly arranged around the centre of two indexable turntables 22. 23 and a pick-up head 31, 32 is arranged above each turntable so as to pick up the uppermost layer of pieces in all the compartments of the associated magazine and transfer it to the assembly table 26; this table constantly reciprocates between a position under one head to a positon beneath the other so that while one head is depositing pieces thereon the other is picking up pieces from its magazine. Each magazine 34, Fig. 6, comprises a cylindrical container detachably mounted on the turntable and divided by a cylindrical partition 89 into inner and outer zones; radial partitions 92 subdivide the outer zone of all the magazines, and radial partitions 95 the inner zones of the magazines on the turntable 22 so as to form compartments in which the pieces of material are stacked on a false bottom and located by ribs 98 in the partitions. The mechanism for indexing each turntable comprises a fixed cam 68, Fig. 4, for projecting outwardly at a given point in the path of rotation of the turntable one of a series of radial rods 61 so that this rod is then in position for engagement by a corresponding plunger 74 or 75, Figs. 1 and 4, on a rod 69 reciprocated by a sprocket chain 71; this chain is reciprocated in timed relation with the operation of the two heads 31. 32 by mechanism operated by cams on a main cam shaft. The plungers are normally restrained in inoperative position but either can be projected downwardly for indexing operation on a projected rod 61 whenever any compartment in the corresponding magazine is empty or nearly so. contacts associated with the corresponding pick-up head then being closed to energize a solenoid .76 actuating the plunger. Each turntable is located in indexed position by a tongue carried by a swinging frame, the movements of which are controlled by the main cam shaft. The buff is assembled on an indexable container 62, Fig. 6. on a tray 35 carried by releasable means on the assembly table 26 which is reciprocated on guides 24. 25 between the two heads 31, 32; these guides are extended to support at the left in Fig. 6 an empty tray to replace the one then on the table and at the right a tray displaced from the table after the assembly of a buff thereon. The table is reciprocated by being connected to the lower run of a sprocket chain 39, Figs. 1 and 6, which is driven alternately in opposite directions from cams on the main cam shaft. During each reciprocation of the table, ratchet teeth 64 on the container 62 engage pawls 65 so that the container is indexed through a small angle to stagger the joints between successive layers of material built up thereon. The means for replacing an assembled tray on the table by an empty tray positioned on the guides consists of a bar 55, Fig. 1, which is connected to the upper run of the sprocket chain 39 so as to reciprocate oppositely to the table and carries two plungers 56, 57 for co-action, respectively, with the means connecting the operative tray to the table and a lug 61 on the empty tray at the left in Fig. 6. These plungers are only projected outwardly to operative positions when their control solenoids are energized by means signallng that the buff on the operative table has reached the prescribed thickness; on the next leftward movement of the table the non-operative plungers release and move the operative tray to the right and at the same time shift the empty tray on to the table. Both the table 26 and tray 35 thereon are locked in correct position when under both heads by tongues carried by the cam-controlled swinging frame referred to above. Each of the pick-up heads 31. 32 consists of a group of units 102, Fig. 13, disposed above the compartments of the associated magazines, each unit comprising a vertically-slidable tube 103 surrounding a relatively-slidable tube 104 which carries detachably at its lower end a device 105 for picking up the uppermost piece in the compartment; this device consists of a reel of adhesive tape 125 (to which the piece will adhere) intermittently fed throughout the machine cycle to an upper receiving reel. Each head also comprises two rings 135, 136, Fig. 13. for guiding and supporting the pieces of material during the pickup and depositing movements and a plate 131 for flattening the pieces after they have been deposited on the assembly table. The vertical movements of the tubes 103, 104, rings 135, 136 and plate 131 are effected in timed relation through tension members 109. 113 143. 134 from cams on the main cam shaft. The cycle of operations of. say, the head 31 starting with the full magazine under each head and the assembly table 26 under the head 32 consists in (a) downward movement followed by upward movement, of the tubes 103, 104 so that the adhesive surface of the tape 125 picks up the top piece of material in each compartment and lifts it over the rings 135, 136, (b) downward movement of the tubes 103, 104 while the rings 135, 136 move upwardly so that the pieces ride off the latter on to the table 26 which by this time has arrived under the head 31, (c) downward movement of the tubes 103 so that spring fingers thereon press on to the pieces while the tubes 104 rise to withdraw the adhesive tape, and (d) downward movement of the flattening plate 131 to flatten out the pieces on the table. Suction from a fan 158, Fig. 1, is applied through a funnel 156 mounted under each turntable to each magazine during the time of operation (a) so that only the top piece of material is lifted from each compartment. When the assembly table is receiving pieces from the head 31, the head 32 is of course picking up pieces from its magazine so that pieces are being constantly built up on the assembly table. The above arrangement may be modified by replacing the rings 135, 136 by suction nozzles for holding up the ends of the pieces at the appropriate times. If desired, the buffs may be built up directly on the assembly table, preferably on a disc of fabric; the buff when fully assembled is then automatically pushed off the table on the disc by means of a slidable pusher member. Reference has been directed by the Comptroller to Specification 683,753.