Patent GB-1212306-A (GB)
Title: Abrading apparatus
IPC: B24C7/00
Filed: 1969-02-27
Abstract: 1,212,306. Blasting. PENNSALT CHEMICALS CORP. 27 Feb., 1969 [21 March, 1968], No. 10545/69. Heading B3D. Apparatus for supplying gas-borne abrasive material to a plurality of nozzles in order to carry out abrading operations comprising (i) a pressure vessel which can be fed with pressurizing gas;  (ii) a reservoir for abrasive material within the vessel;  (iii) a container for abrasive material also within the vessel and which can be replenished from the reservoir; and  (iv) a conduit between the container and each nozzle along which the gas-borne abrasive material can be conveyed is characterized in that the container is angularly movable about a vertical axis and has outlets spaced around the axis, each outlet being located to supply abrasive material to an associated one of the conduits.  Abrading apparatus (e.g. for trimming, cutting, cleaning or deburring) permitting a particular abrading operation to be carried out simultaneously at a number of adjacent stations, e.g. on parallel assembly lines, with uniform results comprises a pressure vessel including a base 12 supporting a shell 14 provided with a lifting ring 16. Inside the vessel 10 a storage reservoir 18 for abrasive material is supported by a stand 20 in position to feed by gravity an abrasive distributer 22 as the contents of the distributer are metered and fed through funnels 23 into lines 24 each leading through a flexible tube 25 to a nozzle 21. The abrasive is carried through the lines 24 by streams of air or other gas admitted to the vessel 10 under pressure through an inlet 26 in the base 12. The abrasive is preferably alumina particles or glass beads; highly hygroscopic materials should be avoided; hygroscopic water can be eliminated by preheating the abrasive to above 212 F. and by using dry gas. Non-corrosive abrasives are preferred; stainless steel is preferred for the apparatus, particularly for those components directly contacted by abrasive. A compressor supplies air, e.g. at 80 p.s.i. when using alumina particles and at 225- 250 p.s.i. when using glass beads, through a pipe 28 to the inlet 26; a baffle 32 is provided in the vessel 10. A heater 34, e.g. electric, may be provided on the pipe to preheat the air to about 140 F. Flow is controlled by a manually operable valve 35. The shell 14 is secured to the base 12 by a bayonet connection comprising a ring 36 secured to the rim of the shell and having a sinuate periphery the crests 40 of which are engageable under the crests 44 of the sinuate periphery of a ring 38 secured to the base 12. The inner ring 36 carries a handle 48 to facilitate rotation of the ring and shell assembly, rotation being limited by diametrally opposed stop pins 46. A finger 54 mounted on the ring 36 co-operates with a switch 52 mounted on the ring 38 and controlling an electromagneticallyoperated valve 50 in the inlet pipe 28 so that air is supplied to the inlet 26 only when the vessel 14 and base 12 are in fully assembled position. The stand 20 supporting the reservoir 18 comprises tubular legs 56 braced by upper and lower rings 58, 60 containing plungers 64 biased upwardly by springs 66 to contact the bottom 62 of the reservoir. As the supply of abrasive in the reservoir is reduced the reservoir is raised so releasing the actuator 70 of a switch 72 which then closes to energize a warning lamp 74 and/or other devices. The distributer 22 comprises a bowl 76 mounted for angular movement about a vertical axis on a driving mechanism 78. The bowl has outlet tubes 80 disposed horizontally and tangential to the bowl wall; the bottom wall 82 slopes downwardly from the centre. The outer ends of the tubes are positioned above the funnels 23. The driving mechanism 78 is a rotary vibrator which vibrates the bowl in an inclined arcuate path about the axis; thus, the bowl is lifted and turned in one direction, increasing the force between the bottom wall 82 and the abrasive material, so discharging the latter through the tubes; the return stroke has little or no driving effect on the abrasive material. The tubes may be kept clear by loose wire members 84 inverted therein, the diameter of the member being selected to give the desired flow rate.  During start-up it may be desired to introduce air to the pressure vessel at a slow rate until the desired pressure is reached; to this end, the vavle 35 is by-passed by a smaller diameter pipe 86 containing a flow valve 88.