Patent GB-865217-A (GB)
Title: Improvements in or relating to machines for throwing abrasive particles at high velocity onto surfaces
IPC: B24C9/00
Filed: 1957-07-24
Abstract: 865,217. Tumbling : blasting. WHEELABRATOR CORPORATION. July 24, 1957 [Jan. 30, 1957], No. 23506/57. Class 60. A machine for cleaning articles, e.g. removing sand from metal castings or burrs and flashing from moulded parts, by abrasive blasting the articles while they are tumbled in a trough formed by an endless conveyer where it passes around two spaced-apart discs, has a loading and unloading opening in the housing wider than the distance between the two discs ; shields are provided for protecting certain parts; the opening is provided with an upper rigid door and a lower flexible door, the doors moving oppositely to each during opening or closing. Flight bars 10 overlapping to provide a continuous surface on which the work to be blasted is carried for tumbling are secured at their ends to pads extending inwardly from link members forming a chain which passes around roller 12, around a second roller located rearwardly of and below the first roller and around a driving sprocket located rearwardly of and above the first roller. The top flight runs about spaced drums 14 carrying wear plates 16 on their inner surfaces, the drums forming the side walls of a space having for its bottom and back walls the flight bars travelling about the drums ; the space is conceded at its top by the sheet metal housing 18 and at its front by a door 20. The door can be opened for loading and unloading the space with work, or closed when the work is subjected to the action of abrasive particles from one or more centrifugal blasting wheels 117 mounted on the top of the housing. A metal casting 22 forming a shield fits tightly over the roller 12 and has a rearwardly upwardly extending portion 24 of curved shape corresponding to the periphery of the drum and dimensioned to cover the space between the periphery of the drum adjacent the roller and the side wall 26 of the housing to conceal the space therebetween. Extending forwardly from the roller edge portion of the curved portion 24 is a portion 28 concentric with the roller 12 and dimensioned to extend crosswise between the adjacent edge portions of the flight bars 10 and the housing side wall 26 to conceal the space therebetween. The two curved portions converge and extend beyond the point of convergence to form a nose piece 30 projecting rearwardly and downwardly into the region between the roller 12 and drum 14. The shield has a side wall section 32 attached by bolts 34 to the housing side wall. The curved portion 28 has a downturned apron 36 at its inner edge extending downwardly below the top surfaces of the flight bars 10 as they pass about the roller 12. The shield extends forwardly beyond the effective range of the abrasive particles and is contacted by the door 20 when the latter is closed. The door has an upper part 40 formed of a heavy metal plate 42 of width corresponding to the width of the opening between the housing side walls 26 and of length corresponding to the distance between the upper end of the door opening adjacent the top wall of the housing and the tangent to the periphery of a cylinder slightly greater than the cylindrical section formed by the flight bars passing about the roller 12. Reinforcing members 44 are welded on the outer face of the plate. The inner face of the plate is protected from wear by the abrasive particles by a replaceable rubber blanket 46 held by straps 48 secured by bolts. The rubber lining 46 and plates 48 terminate short of the edges of the plate 42 to accommodate wear plates 52 secured by bolts. The wear plates are in sliding relation with a door frame member 56. An angle iron welded to the door plate has a guide flange 58 received in a recess 62 provided by an angle iron 64 secured at one edge 66 to the outer edge of the side plate 68 of the housing which defines the door opening. Also secured to the inner wall of the side plate 68 is a member having a flanged portion 56 extending inwardly from the side edge beyond the end of the recess 62. Door-operating means comprises cables 74 secured at their free ends to an upper portion of the door plate and wound about pulleys 76 on a shaft 78 driven by reversible electric motor 82. The door has a bottom section comprising a panel 84 of rubber or like material with guide members 86 on the edges sliding within guide channels. The lower edge of the panel 84 is fixed by bolts 88 on to a metal closing plate 90 to which is secured a rod 92. Metal bars 94 are pivoted on the rod 92 and connected to pivoted actuating arms 100 operated by air cylinder 106. The closing plate 90 has secured thereto a guide plate 116. Specification 865,216 is referred to.