Patent GB-939331-A (GB)
Title: Abrasive blasting apparatus
IPC: B24C3/26
Filed: 1961-12-22
Abstract: 939,331. Pneumatic separation. PANGBORN CORPORATION. Dec. 22, 1961 [Jan. 4, 1961], No. 46011/61. Class 117. [Also in Group XXIII] Abrasive blasting apparatus includes a housing 20 within which is supported an endless conveyer belt 22 so that it has upper and lower flights 24, 26. The upper flight is shaped to a trough by rotatable guide discs 28. The belt is reversibly driven by a motor 30. Blastant particles are projected by a throwing wheel 32 or a set of such wheels, actuated by one or more motors 33. A shut-off valve 35 is provided in a conduit that supplies blastant particles to the wheel. The lower portion of the housing 20 tapers down to form a hopper 106 through which the blastant particles are guided to a screw conveyer 108 or a vibrating conveyer which propels the particles to one side of the housing where they are lifted by a bucket elevator 110 and dropped into a separator 112. The latter can be a combination of scalping drum and rotating screen and causes the recycled blastant particles along with any fine materials accompanying them to drop through a moving air screen at 118 so that the fine materials are carried along by the air stream while the heavier particles drop into storage bin 120 which feeds the throwing wheel. The air stream is provided by a suction duct 122 having a branch 124 leading through a chamber 126 having baffles 130, 131 to a screened opening 128 in the wall of the separator. The heavier of the swept-along particles fall into spout 133 for discharge into a container 135. The lighter particles are carried by the air stream to a filtered or unfiltered outlet for the air. For the more complete removal of high concentrations of lighter particles, as where large amounts of sand are introduced into the apparatus by the workpieces, a tapered nozzle 136 is inserted in screen opening 128 to increase the speed of the air stream; the nozzle may be connected at its outer end to a source of pressure air and need not then be tapered. An overflow conduit 137 is provided at the remote end of the separator to carry particles that reach that end so as to indicate that the separator is operating at full capacity, and a conduit 139 is located with its upper end near the top of storage bin 120 so as to indicate by overflow of the particles when the bin is full, both conduits having transparent sections or air gaps for observation of movement of particles therethrough. The conduits lead directly to the screw conveyer or to the housing so that particles passing through them are not removed from the system. A conduit 141 carries off larger objects, e.g. core wire, rods, &c., separated by the scalping drum. The suction duct 122 is connected by duct 145 to the interior of the housing 20 so as to withdraw dust. A screen 151 is mounted across the bottom of the hopper 106 to catch large objects, e.g. cores and wires, and prevent them from going through the recycling system. The screen is tilted, so that the objects collect at the lowermost portion of the screen; they can be removed by the operator through a hinged access door 153 with which is associated a baffle 157. Specifications 743,093, 743,107 and U.S.A. Specifications 2,771,189, 3,048,947 and 3,087,615 are referred to.