Patent GB-914406-A (GB)
IPC: F16F9/04
Abstract: 914,406. Vibratory mechanisms; variablespeed gear. PANGBORN CORPORATION. Jan. 23, 1961 [Jan. 27, 1960], No. 2575/61. Classes 80 (2) and 80 (4). [Also in Group XXIII] Apparatus for subjecting workpieces, e.g. of metal, to vibratory finishing treatment, e.g. deburring, descaling, cleaning, polishing, burnishing, rounding corners and edges &c., comprises a container for the workpieces and vibrating structure connected to vibrate the container, the container being supported by a mounting comprising air cushions that provide lateral stiffness and vertical resiliency. A trough-shaped container 10, Figs. 1 and 2, has a resilient liner 104, e.g. of natural or synthetc rubber vulcanized in place. Feet 16 secured, e.g. by welding, to the underside of the container are fastened by bolts to a table 12. The table is vibrated by a shaft 18 having an interchangeable eccentric weight 20 journalled between bearings 22 rigidly attached to the table by webs 24 welded to the underside of the table. Skirts 26 depending from the table are welded thereto and to the webs. Brackets 30 secured against the outer surfaces of the skirts 26 carry horizontally-extending pads 32 received between horizontal flanges 34, 36 of a supporting framework 38 encircling the table. Air cushions 40, 42 are interposed between the pads 32 and the flanges 34, 36. Each air cushion has upper and lower cups 90, 92, Fig. 3, of rigid material, e.g. metal, connected by a flexible open-end tube 94, e.g. of rubber or rubberimpregnated fabric. One cup has a fitting 96 providing a connection to the interior of the cushion and receiving an air line. An air supply 102 is connected by separate adjustable pressurereducing valves to conduits 98, 100 supplying the lower and upper sets of air cushions. The framework 38 comprises channels 44, 46 carrying opposed reinforced sheets 48 to which the flanges 34, 36 are welded. Stub shafts 50 at opposite ends of the framework are received in journals 52 carried by piers 54 directly secured to a floor, such as a rigid concrete slab, and tied together by a tubular brace 56. The framework can be tilted hydraulically, mechanically or electrically but is preferably tilted by a pneumatic cylinder 58, supplied from the air source 102, its piston-rod 62 being connected to a bellcrank 64 secured to a collar 66 keyed to one stub shaft 50. The container can be tilted in one direction for dumping the workpieces and in the opposite direction for rinsing the workpieces or the container. The shaft 18 is driven by an electric motor 68 horizontally adjustable on a box 70 depending from the framework 38 alongside the table 12. The motor is connected by a variable ratio pulley drive 72 with a jackshaft 71 journalled in bearings 76, 78 on a bracket 80. The jackshaft 71 is connected to the shaft 18 by a flexible coupling 82. The bracket 80 is vertically adjustable relatively to the box 70 by a jackscrew 106 so that any offset of the jackshaft 71 and shaft 18 is kept within the tolerance of the coupling 82. The workpieces are placed in the container together with abrasive elements of ceramic or metal. Liquid may be used, e.g. aqueous, containing dispersing agents with or without soaps ; burnishing ingredients may be added. Emulsions or solutions may be used and for descaling the liquid contains ingredients such as acids to dissolve the scale. For rough finishing, the eccentric weight and the air pressures in the cushions are selected to produce a gyration amplitude of at least 3/8 inch ; for fine polishing the amplitude is reduced to the order of <SP>1</SP>/ 16  inch. Frequency control is effected by adjustment of the ratio of the pulley drive 72. Alternatively the frequency of the electric supply to the motor may be varied, or a D.C. motor may be used with a separate motor generator set to supply variable voltage D.C. power. An air cushion 301, Fig. 7, may be fitted between the floor 303 and the bottom of each pier 54. The cushion is surrounded by an inner tube 305 standing up from the floor and carrying at its top a rubber bumper strip 307. An outer tube 309 depends from the bottom of the pier. The tubes reach the limit of their collapsed travel before the air cushion is completely deflected. In a modification, Fig. 12, a set of spaced lugs 311 is secured, e.g. by welding, to the outer tube and studs 313 extending through apertures in the lugs threadedly engage nuts 317 welded to a plate 315 to which the inner tube is fastened. Removable nuts 319 can be threaded on the studs and engaged against the upper faces of the lugs to clamp the tubes together for crating and shipping the apparatus. A resilient pad 321, e.g. of natural or synthetic rubber, is located under the plate 315 to make up for minor irregularities in the floor 322. For certain stages of the operation the container may be fitted with a cover 411, Fig. 9, having a screen portion 413 and a hose connection 415. A tapered mounting clip 417 formed at one edge of the cover engages a flanged edge of the container and the cover is held in place by toggle clamps 421. A fine screen 419 may be placed under the cover. In a modification, Figs. 13 and 14, a tilt framework 538 comprises a pair of transverse channel beams 502 connected by side sheets 504. The outer faces of the beams are covered by end panels 506. An intermediate panel 508 secured between the side sheets is reinforced by weldedon angles 510 and a bar 512 to support the driving motor and jackshaft. To each side sheet is secured a pair of shelves 514 extending short distances longitudinally and terminating in vertical flanges 516, 518. On the shelves are mounted lower air cushions upon which rests the work-table. This comprises a flat sheet 522 with reinforcing plates 531, 532, 533, 534 welded to its lower surface. Plates 533, 534 extend transversely and have central passageways receiving the bearings 524, 526 of the vibrator shaft. The bearings are supplied with lubricant from a reservoir, and a check of the bearing temperatures is provided by a thermocouple. The jackshaft is mounted in bearings 542 fastened to the underside of a mounting-plate 544 welded to the intermediate panel 508. Where upper air cushions are used these can be smaller than the lower ones and can be secured to the top of the table offset from the lower cushions in a longitudinal direction. Removable brackets are bolted to the side sheets 504 to hold down the upper cushions and permit them to be readily removed, e.g. when the table is to be replaced. For shipment, bolts are fitted through holes in the shelves 514 and threaded into the table with spacers between the shelves and the table. The container has strengthening ribs 548 welded to its external side surfaces and has its feet 550 strengthened by gusset plates 552 welded over the open ends of the feet, preferably in the plane of the ribs 548. Bosses 553 formed along the longitudinal centre of the container bottom have aligning pin openings matching up with aligning openings in the table top. To support the container when it is tilted to unloading position, mounting clips 554 are secured to the side sheets and each has two arms holding a resilient tube 556, e.g. of natural or synthetic rubber or plastic, slightly spaced from the side of the container. To protect the apparatus against spillage around the top of the container, a cover 560 is fitted over the entire top of the tilt frame. The cover has an opening 562 through which the container projects, the opening being smaller than the area covered by the lip of the container. The cover has a turned-up flange 563 surrounding the opening and turned-down margins fitting over the corresponding margins of the tilt frame. The cover is removably secured by a hook 572 pivoted to the panel 506 and operated by a handle 576. The cover is used as a height indicator for the container, an adjustable pointer 580 secured to cover flange 563 co-operating with a scale 582 fixed to the container so as to serve as a guide for adjusting the height of the vibrating shaft to match the position of the jackshaft. Automatic adjustment may be effected by a combination cushioninflating and cushion-deflating valve controlled by a pair of electrical switches positioned one above and one below the margin of the table so that upward movement of the table causes the lower cushions to deflate and downward movement of the table causes them to inflate. The container may have a resilient liner formed by vulcanizing rubber in situ, the interior of the container being first given a thin layer of brass. Plastics, with or without plasticizer, may be used instead of rubber. Vibration frequency is measured by a tachometer generator 573 coupled to a stub shaft extending from the jackshaft pulley. The vibration may be measured by a set of reeds mounted on the apparatus. A block 577 secured to the outer face of panel 506 co-operates with a switch 579 on the adjacent supporting pier so that when the container is upright the switch is closed to establish an electrical circuit used in energizing the vibrating drive, while for all other positions of the container the switch is open so that vibrations cannot be carried out. The air cushions may comprise piston-andcylinder devices; alternatively they may be hollow resilient balls, e.g. of rubber or plastic, mounted between spherical sockets on the table and tilt frame, the balls being cemented or vulcanized in their sockets or fastened therein by bolts. The air cushions can be used to suspend the container. Air cushions can be used in conjunction with spring supports, e.g. a container supported on a combination of coil and leafsprings may have a set of air cushions effectively above the container and holding it down with a controllable force, so that adjustment of the pressure in the cushions adjusts the height of the container. A through-flow machine comprises a container 210, Fig. 5, support