Patent GB-1381685-A (GB)
Title: Portable blasting device
IPC: B24C3/06
Filed: 1973-05-11
Abstract: 1381685 Pneumatic separation SINTOKOGIO Ltd 11 May 1973 [11 May 1972 (2) 27 July 1972 2 March 1973] 22648/73 Heading B2H [Also in Division B3]  A portable blasting machine comprises a cabinet 1 having an opening 8 and a sealing member 9 of rubber or like synthetic material disposed around the opening so that surface grinding and abrasive materials blasted towards the surface 40 of a workpiece, such as the hull of a ship, are confined within the cabinet, and centrifugal blasting means 3 mounted on the cabinet and having an impeller 5 driven by an air motor for blasting the materials towards the surface to grind and clean it. A container 13 communicates with the interior of the cabinet and collects used materials and dust, and a dust separator 17 has an aperture for discharging separated dust to a dust collector 19 and an air injection means 22 for directing compressed air towards the aperture 20 as to establish a negative pressure within the separator whereby separated dust is discharged to the collector. Means are provided, including a throat means 15  and nozzle 14 for conveying materials and dust to the separator.  The centrifugal blasting means 3 consists of an impeller 5 which is mounted on the shaft 4 of the air motor 2 within a casing 6 secured to a wall of the cabinet 1, a control cage 7 also being secured to the casing and a tubular member 16 for feeding shot or grit material to the impeller. The opening 8 is formed in a front wall of the cabinet, the front wall being inclined to the back wall which has a guide means 11 which acts on the material rebounding from the workpieces so that it is again directed onto the surface. The sealing member 9 is fixed to the opening 8 by a mounting member 10, and a plurality of non-magnetic stops 36 engage the workpiece surface, the stops being associated with permanent magnets 37 which assist in holding the machine against the workpiece surface 40.  The container 13 is connected to the lower end of the cabinet 1 for temporary receiving the abrasive material. The nozzle 14 is located without the container and is connected by a conduit 33 to a cross joint 31 having an inlet connected by a hand-operated valve 25 to a source of compressed air 50. The container is also connected by the throat 15 and a conduit 18 to the dust separator 17 which has  a deflector 21 whereby shot and grit passed to the separator by an air flow from the nozzle passing through the throat 15 is directed to the tubular member 16 leading to the impeller. An aperture in the separator 17 is connected by a conduit 20 to the dust collector 19 and an injection conduit 22 is directed towards the aperture and connected by a conduit 34 to the cross joint whereby a negative pressure is produced in the aperture to cause dust to be directed to the dust collector. The negative pressure in the separator is also applied by a conduit 23 to the upper part of the cabinet so that dust therein is drawn into the separator and hence directed to the collector. The air motor is connected by a conduit 32 to the cross joint 32 so that when an operator presses a lever 27 of the control valve 25, the compressed air is supplied simultaneously to the motor 2, nozzle 14 and separator 22. The machine is used by the operator gripping the motor 2 and a handle 26 incorporating the valve 25.  The impeller consists of a plurality of blades 42, Fig. 7, integral with a plate 41 secured to the shaft of the motor 2 by a nut in the form of a deflector 44, Fig. 8, having radial projections 48.