Patent GB-683753-A (GB)
Title: Improvements in polishing buffs and a method and machines for making them
IPC: B24D13/12
Filed: 1951-05-08
Abstract: 683,753. Polishing buffs. TREVENNA, G. R. May 8, 1951 [May 17, 1950], No. 10833/51. Class 60. A polishing buff consists of layers of cloth, leather, plastic, stiff-paper on other material, each having a number of non-overlapping pieces forming an inner and an outer ring, interspersed with other layers having pieces which extend across the lines of meeting of the pieces of the first-mentioned layers. The inner rings of alternate layers may be formed by separate pieces and one-piece discs while the outer rings are formed from sector-shaped pieces. The circumferential joints between the inner and outer rings may be staggered or the pieces forming these rings may be arranged to make a splined or flanged joint so that the radially outer portion of the buff can be detached. The outer layers of the buff comprise complete discs and the whole is sewn together. The buff is held between a pair of clamping washers of fibre, leather, plastic or other material. The washers overly the circumferential joint between the inner and outer rings and are connected by pins which pass through the buff and are secured at one end by removable spring clips. A machine for making the buffs consists of two magazines A and B, Fig. 17, holding sets of pieces to form alternate layers of the buff, a pick-up head 52, Fig. 1, associated with each magazine to pick up a complete set of pieces and a table 18 on which the buff is assembled. The table 18 is oscillated or reciprocated pneumatically over each magazine in turn when a set of pieces previously picked up by the head 52 is deposited on it. At each oscillation the table is indexed by mechanism (not shown), to obtain the staggered relationship between the radial joints. Each pick-up head 52 is provided with feet such as 75, 76, 79 which project through a stripper plate 59 loaded by springs 65 and detachably secured to the head by a pneumatically or electrically operated latch 66. Each foot comprises a roll of adhesive material having one end secured to a drum 84 which is periodically rotated to bring fresh surfaces of adhesive material to operative position and each magazine is divided into compartments to hold the pieces which rest on a number of spring loaded plungers (not shown) carried by a pneumatic ram. A second and simultaneously operated ram lowers the pick up head so that the feet project into the magazine compartments to pick up a complete set of pieces. When the head has lifted the latter the table 18 is swung below them and the head then descends slowly to deposit them. During the descent a rod 56 operates a switch 11 on an arm carrying the table to release the latch 66 thus allowing the stripper plate 59 to drop and press the pieces down on to the partly assembled buff. The table 18 is now swung across to the other magazine where the process is repeated. The stripper plates 59 are raised and re-latched by their engagement with the magazine on the pick up stroke. At each reciprocation of a pick up head a spring-loaded member 99 co-acts with a fixed stop to rotate a ratchet wheel 96 driving a cam with a number of spaced lifts 95A. These lifts cause a switch 94 to close and energise a solenoid 93 which through a pawl and ratchet mechanism rotates the drum 84 to renew the abrasive surfaces on the pick up feet. After each layer is added to the buff, two caliper arms 157, 158, Fig. 14, are advanced pneumatically to gauge the buff thickness. A switch 164 stops the machine when the required thickness is attained. The caliper arms are retracted by the closing of a switch 170 and are biassed towards each other by a spring 161. A stop rod 162 keeps the arms sufficiently separated to enable them to embrace the stripper plate 59 and the table 18. The strips in the magazine compartments separate two electrical contacts so that when one or more of these compartments is emptied a circuit is closed to stop the machine. An alternative form of pick up foot consists of two levers 114, Fig. 9, connected to solenoids 119A and biassed by springs towards a bracket 110 from which they are pivotally supported. As the head moves down the levers are displaced outwardly by the solenoids and needles projecting from their ends penetrate the top layer of pieces in the magazine. The solenoids are now de-energised so that the levers are pulled inwardly by their springs to nip the layer of cloth between them and the bracket, whereupon the head is raised. To deposit the layer on the table the solenoids are again energised, no stripper plate being necessary. To prevent more than one strip being lifted from each magazine compartment, the walls of the latter may be fitted with rubber wedges which resist the upward movement of the strips or a vibrator may be connected to the head. In an alternative form of machine, two magazines 199, 200, Fig. 19, and a buff-assembly table 206 are arranged to be swung in sequence between a magazine ram and a single pick up head 197, while in a still further form of machine one or more buffassembly tables are traversed rectilinearly past a number of magazines and pick up heads each of which contributes one layer to the completed buff. With the latter form of machine the magazines may be positioned in suitable angular relation to each other to provide the required staggering of the radial joints, and a pick up head in fixed relation with the machine and in which the feet are mounted on spring- loaded rods may be employed.