Patent GB-998106-A (GB)
IPC: B24C3/06
Abstract: 998,106. Blasting. MERCANTILE MARINE ENGINEERING & GRAVING DOCKS CO. July 30, 1962 [May 11, 1962], No. 29140/62. Heading B3D. [Also in Division B1] Blast apparatus for cleaning surfaces, more particularly metallic surfaces, comprises the combination of a steerable vehicle, a projection housing with an open end, a support mounted on said steerable vehicle and carrying said housing, said support being capable of bringing and maintaining said housing with its open end adjacent the surface to be treated, centrifugal projecting means projecting into said housing toward said open end and capable of projecting hard particles outwardly through said open end and against said surface to be  treated, a feeding chamber for storing said hard particles, a filtering means for carrying out the separation between said hard particles after impact on said surface to be treated and air carrying the powdery mass of the treatment waste products, control means for .controlling the operation of the blast apparatus and control means for said steerable vehicle. Apparatus for treating horizontal or substantially horizontal, plane or curved, surfaces comprises a carriage A, a device B for project ing hard particles and a filtering means C. The carriage A comprises a frame 1 carried by wheels 2, 3, 4, 5. The wheels 2, 3 are driven by an electric motor 6 through a belt 8, reducing gear 7 and a clutch 10; the wheels 4, 5 may also be driven. The wheels 2, 3 are steered by a steering wheel 11; the wheels 4, 5 may also be steered. Near the steering wheel is a control panel 21. A platform 22 for the operator may be provided with a seat. The device B comprises a housing 23 having at its underside a long narrow opening 25 through which it is connected with the outlet of centrifugal projecting means 24. The peripheral edge of the housing 23 is in a plane X-X inclined to the projecting axis Y-Y. A wall 26 extends from the rear longitudinal edge of the opening 25 up to near the plane X-X. A wall 27, parallel to the wall 26, extends from the front longitudinal edge of the opening 25 upwards for part of the height of the housing 23, the free upper edge of the wall 27 being bent to form an inclined portion 28. The wall 27 forms a boundary of a chamber 29 to receive the blasting medium after impact on the treated surface, the bottom of the chamber 29 having an opening 30 facing an inclined plane 31 formed by the adjacent portion of the housing 23 and leading to the inlet 32 of the projecting means 24. In the chamber 33 defined by plane 31 is a slide valve 34. A wall 36 is spaced from and parallel to the front wall 37 which has an outlet opening 38 opposite which is a deflector 39 having small holes 40. Between the wall 26 and the back wall 41 is a wall 42 defining a chamber 43 having openings 44 leading into the channel defined by the walls 26, 27. The walls are preferably lined with rubber or synthetic resin. The lining may be extended to form resilient frames 45-48 and 49-52 for seating against the surface being treated. The centrifugal projecting means 24 is driven through belts by an electric motor 53. The housing 23, the centrifugal projector 24 and its driving means form an assembly supported so as to be movable from a rest position to any suitable working position. The supporting means comprises arms 57, 64. Arm 57 is pivotable, by a jack 59, about an axis 58 on the frame 1. Arm 64 is pivotable, by a jack 66, about an axis 65 on a post 70 pivotable about a perpendicular axis 71 on the frame 1. The arms 57, 64 have parts 74, 75 receiving spherical knuckles 72, 73 on the housing 23. A flexible tube 76 connects the outlet 38 of the housing 23 to the inlet 77 of a filtering chamber 78 having an outlet 79 opposite the inlet. The filter consists of upper sills 80, 81 and lower sills 82, 83 connected by crossbars 84, 85. The filter element bears on a thin flexible strip 86 supported by the cross-bars 84, 85. A shaker for periodically removing particles adhering to the filter comprises cross-bars 87 carried by a frame 88 supported from the upper sills 80, 81 by links 89, 90 and rapidly reciprocated by means driven by an electric motor 91. The bottom of the chamber 78 is removable for periodical emptying. The outlet 79 communicates with the inlet of a fan 93 driven by an electric motor 94. The circuit of the motor 53 driving the centrifugal projector 24 contains switches controlled by the correct position of the housing 23 against the surface being treated. Switches 96, 97 are mounted by supports 100, 101 on the housing 23. Switches 98, 99 are mounted on the ends of a lever 102 pivoted about an axis 103 on the housing 23. Switch 97 comprises a plate 108 pivoted at 107 to the support 101 and carrying a metallic sphere 104 and a microswitch 116; the latter is activated by a rod 119 adjustable in the support 101. The other switches are similarly constructed, and the circuit is such that the motor 53 can only be energized when the housing 23 is everywhere correctly applied against the surface being treated. The slide valve 34 controlling the supply of particles to the centrifugal projector 24 is normally closed by a spring and is opened by an electromagnet when the projector has reached its working speed, the electromagnet being controlled by a tachometer or by a timer. Another embodiment for treating vertical or substantially vertical surfaces is shown in Fig. 12.