Patent GB-1432658-A (GB)
Title: Abrasive particle blasting apparatus
IPC: B24C3/00
Filed: 1973-10-18
Abstract: 1432658 Blasting ISHIKAWAJIMA - HARIMA JUKOGYO KK 18 Oct 1973 [27 June 1973 31 July 1973 48678/73 Heading B3D An abrasive particle blasting apparatus comprises a nozzle 2, Fig. 2, supplied with high pressure liquid to project particles on to a surface 9 to be treated, a collector 10 of discharged liquid and particles, and a re-circulating system for the collected particles and liquid including a wet-flow classifier 3. The classifier 3 is connected by a pipe 4 to a reservoir 1 of abrasive, such as sand, and by a pipe 5 to the nozzle 2. An anticorrosion agent is stored in a tank 6 which is connected by a pipe 7 and high pressure pump 8 to the nozzle, the agent acting to project the abrasive from the nozzle under the surface 9, such as steel strip, the abrasive being carried to the nozzle by water from the classifier 3. Used abrasive and liquid is collected in a tank 10 and returned by a pump 12 and pipe 11 to classifier where it is classified by a fluid bed therein. The anticorrosion agent is also fed from tank 6 by a pump 19 and line 18 to the collector tank 10 and to a tank 14 which also receives the overflow 13 from the classifier. The overflow consists of particles below a predetermined size which are entrained in a stream of anticorrosion agent supplied to the bottom of the classifier by a pump 15 and line 16 connected to the tank 14. The pressure from pump 15 is such that particles above a predetermined size fall down against the upward flow of the agent and are carried along pipe 5 to the nozzle. Smaller particles are carried by the upward flow and passed by the overflow 13 to the tank 14 where they are filtered out and discharged at 20. In an embodiment for cleaning steel strip 5, Fig. 4, prior to cold rolling, the strip is passed over rollers 21, 22, each roller being adjacent an array of nozzles 2 in a respective cleaning chamber 23, 24 filled with inert gas. The pressure of liquid projecting the abrasive is between 50 and 1000 Kg/cm<SP>2</SP>. A washing chamber 27 and drying chamber 29 are disposed downstream of the chamber 24. In another embodiment, the strip moves in a straight path between opposed arrays of nozzles which project the abrasive onto opposite surfaces of the strip. In a further embodiment, the nozzles 2 are carried at the end of a telescopic boom 45, Fig.6, having a part 46<SP>1</SP> guided in a second part 46 slidable in rollers 47 on a carriage 37. The carriage and parts 46, 46<SP>1</SP> are interconnected by cables 50 guided over pulleys 49 so that the parts 46, 46<SP>1</SP> move in unison during extension and retraction of the boom. The carriage 37 is vertically movable by a cable 41 and winch 43 along a frame 35 carried by a carriage 34 motor driven along rails 33. The nozzles 2 are carried by an assembly 54 connected to a flexible pipe 53 rotatable about its axis by a motor 55 to alter the angle of the nozzles with respect to the surface to be treated. The nozzles are connected by a manifold 51 to a hose 56 which passes over a drum 57 and is connected to a high pressure pump. A workpiece, such as steel sheet, is placed on a carriage 68 movable along rails 69 of a turntable 61 rotatably carried by rollers 65 on a rail 64 around which it is driven by a motor 66. A seal 67 is disposed at the edge of the turntable adjacent a ditch 62 which receives spent abrasive and liquid and has a low point X connected to the wet flow classifier. A further ditch 63 collects any liquid which may pass the seal. The frame 35 is associated with collapsible doors (58, Fig. 8, not shown) which prevent abrasive liquid falling onto the carriage motor during movement of the frame.