Patent GB-1071696-A (GB)
Title: Improvements relating to the vibratory finishing of workpieces
Inventor: BONIFACE FREDERICK GEORGE
IPC: B24B31/06
Filed: 1964-11-23
Abstract: 1,071,696. Screening materials. ROTOFINISH Ltd. Nov. 23, 1965 [Nov. 23, 1964; Aug. 27, 1965; Sept. 15, 1965], Nos. 47595/64, 37032/65 and 39486/65. Heading B2H. [Also in Division B3] Finishing apparatus comprises: (i) a resiliently mounted tub for receiving a mass of workpieces mixed with processing media, (ii) a rotary vibrator for imparting circular vibratory movement to the tub to produce the required abrasive finishing action on the workpieces and to cause the mass of material in the tub to circulate in an orbital path, and (iii) a screen adapted to allow the media to pass through it but to intercept the workpieces, the screen being so mounted in relation to the tub that in one relative position of the parts of the apparatus (finishing position) the part of the tub interior occupied by the circulating mass is left wholly unobstructed to allow the finishing action to proceed, the screen being then clear of the circulating mass, while in another relative position of the parts of the apparatus (separating position) the screen extends across the path of the circulating mass, so that it will intercept the workpieces while allowing the media to continue circulating in the tub. A tub 1 is supported by springs 2 on a frame 3 pivotally supported at 4 on a stationary frame 5. The frame 3 can be tilted by a hydraulic cylinder 6. A vibrator 7 secured to the tub comprises an eccentrically weighted rotary shaft and an electric motor driving the shaft. The vibrator runs in such a direction that the contents of the tub, comprising workpieces 10 and processing media 11, circulates clockwise and cascades from the upper edge 8 towards the lower edge 9. A separating screen 12 extending the full length of the tub is mounted on a support 13 secured to the stationary frame 5. The screen may be of mesh material; alternatively (Fig. 4) it may comprise radial rods (14), longitudinal rods (15) and a peripheral sheet metal member (16) of inverted channel section. The machine may be enclosed in a casing (18) having an opening giving access to the tub interior. During finishing the screen 12 is above and clear of the mass circulating in the tub. When finishing is complete, the cylinder 6 is operated to tilt the tub so that the screen 12 projects across the path of the mass as it cascades, the workpieces being retained on the screen while the media passes through the screen and continues to circulate in the tub. The workpieces collected on the screen may be picked off by hand, removed by conveyor means or cause to slide off the screen by inclining it. To ensure satisfactory separation, the operation of the cylinder 6 should raise the tub axis through a distance equal to about one quarter of the tub diameter. The length and diameter of the tub are approximately equal. In a modification (Fig. 5) the tub (1) is supported by springs (2) directly from the stationary frame (5). The screen (12) is mounted on the support (13) for movement between an inoperative position and an operative position, e.g. by a sliding movement in its own plane or by pivotal movement. A guide member may be placed along the tub axis while the screen is in its operative position. The guide member may be mounted upon the screen and have the form of a tube (17) of rounded triangular cross section. The guide member may be mounted separately from the screen but should be withdrawn clear of the mass of material in the tub except when separation is being effected. The guide member may be of screen construction so that media can pass through it. A guide member may also be provided in the tilting tub construction. In another modification (Fig. 6) the tub is directly supported from the stationary frame (5) and the screen (12) is fixed on the support (13). During finishing. the screen is clear of the surface of the orbitally circulating mass of workpieces and media: a baffle (19) carried on pivotally mounted arms (20) is raised clear of the mass. To effect separation the baffle is lowered to act as a weir diverting the upper cascading part of the mass onto the screen.