Patent GB-1196086-A (GB)
Title: Abrasive Blasting Apparatus
IPC: B24C5/06
Filed: 1968-03-26
Abstract: 1,196,086. Blasting. PANGBORN CORP. 26 March, 1968 [3 April, 1967], No. 14493/68. Heading B3D. Abrasive blasting apparatus, particularly for cleaning relatively inaccessible places such as the inside of covered hopper cars, pipes and tanks, comprises (i) an abrasive blasting wheel having a plurality of radial vanes thereon; (ii) a motor disposed adjacent to and above said wheel ; (iii) a relatively short shaft connecting said motor to said wheel whereby said motor may rotate said wheel ; and (iv) confined abrasive feed means leading from above said motor to said wheel.  A blast wheel 16, having radial vanes 18, and its driving motor 28 are mounted at the lower end of a vertical or substantially vertical boom 10. To keep the diameter as small as possible the motor 28 may be a two-pole 3,600 RPM motor giving a speed of approximately 3500 RPM. Alternatively, a 30 HP motor may be energized by a high frequency A.C. alternator (46) driven by a 60 cycle A.C. induction motor, to give 50 HP and a speed of 3440 RPM. The motor 28 is cooled by filtered air blown down tube 40 and passing through and round the motor windings to outlet 44. Abrasive is fed to the blast wheel through one or more feed pipes 20 terminating at the top of arcuate passageways 24 each containing a deflector 22. The abrasive then passes through passages 26 around the motor 28 until it reaches plate members 30 which include apertures to permit the abrasive to be fed in a controlled manner such as a full 360 degrees or a fixed portion thereof; the total area of the apertures is slightly more than the orifice area feeding abrasive to the wheel 16. Shrouds 36, 38 are provided. Various arrangements for the plate members 30 are described. One arrangement comprises two plates 31, 33, Fig. 9, with apertures 35, 37, the plate 31 being rotationally adjustable to vary the register of the apertures. In another arrangement, the plates 41, 43, Fig. 10, are fixed to provide full 360 degree feed. In another arrangement blocking segments 45, Fig. 11, are arranged over the apertured plates; apertured segments 47, Fig. 12, may be used these being rotationally adjustable.  The boom 10 is mounted for tridirectional movement so that the blast wheel can easily be inserted into otherwise inaccessible locations such as railroad cars 49. Up and down movement is achieved by rails 51 and collars 53. sideways to and fro movement is achieved by rollers 55 on rails 57. Back and forth movement is achieved by rollers 59 on rails 61. In a modification, Fig. 13, abrasive is fed through tube 20 into an upper chamber 65; a lower chamber 67 is divided into a number of individual non-communicating co-arcuate segments 69 which lead past the motor to the blast wheel as described above. The chambers 65, 67 are separated by a power driven rotating plate 71 having one or more apertures 73, the position of which is indicated by a switch 75 in the path of a tripper 77 on the plate 71; the switch 75 actuates a counter 80 at the operators panel. The total area of the aperture(s) 73 is slightly more than that of the gate 79 in feed spout 21. If abrasive backs up into upper chamber 75 a probe indicator 81 shuts the gate 79 until the abrasive level falls. Alternatively, the apertures 73 serve as metering feed holes, and the chamber 65 has high and low level indicators 83, 85 controlling the gate 79. The rotation of plate 71 can be remotely controlled and can be programmed by conventional methods of rotational control for electric, air or hydraulic drives. For example, in cleaning a part, Fig. 15, having an off centre entrance opening, the plate 71 is programmed to rotate quicker over area A than over area B to ensure more uniform blasting. To clean the inner and outer surfaces of two cylindrical workpieces 87, 89, Fig. 16 with a single blast wheel, the workpieces are rotated, and the blast wheel is located successively in the positions 91, 93. 95.