GB913213A - Centrifugal blasting machines - Google Patents

Abstract

913,213. Blasting; tumbling. BELL INTERCONTINENTAL CORPORATION. March 26, 1959 [March 26, 1958], No. 10523/59. Class 60. A blasting machine wherein blasting medium is projected centrifugally by an impeller on to an article disposed within a chamber, spent medium being returned to the impeller, includes a closed circuit passageway for a stream of air, means producing a stream of air in the passageway. a duct forming part of the passageway and having the up-stream end adapted to receive spent medium, the duct conveying the medium in the stream of air to the impeller, and means intermediate the down-stream end of the duct and the impeller for diverting the stream of air away from the impeller and into the closed circuit passageway while permitting the medium to pass to the impeller for projection on to the article in the chamber. A blasting machine for the smoothing, cleaning or other surface treatment of articles, e.g. of plastic, has a blasting chamber 1 containing an endless conveyer belt 2 passing over rollers 3, 4, 5 and a pair of guide pulleys 6. A housing 11 opening directly into the chamber 1 contains an impeller 14 driven by a motor 13. Combined with the impeller is a blower fan 20 in a spiral housing 12 opening into a pressurereturn duct 30 surrounding a suction tube 31. Blasting medium is conveyed by air through suction tube 31, pipe bend 32 and suction tube 33. The air passes through the inner portions of the impeller 14 and then, after deflection through almost 180 degrees, laterally into the guiding channel 21 of the fan 20. The comparatively heavy particles of blasting medium cannot undergo this deflection and continue on into the impeller 14. The spent medium passes through holes in the conveyer belt 2 into a chamber 40 and thence through a flap 42 biased by counterweight 41 falls in a fire screen into a tank 50. A fan (not shown) draws air through a slot 52 and an opening 53. The air passes through the screen of medium, removing dust and broken medium into separator 55 and leaves through opening 54 which may be provided with filters. An inlet passage 60 for air is automatically opened when a door 61 is opened. A sight-glass 51 is kept clear by the air entering through slot 52. The suction tube 31 is provided with a humidifying device operated as a result of siphon action caused by the air stream.