Patent GB-665832-A (GB)
Title: Abrading apparatus
IPC: B24C5/06
Filed: 1948-02-29
Abstract: 665,832. Sand-blast. PANGBORN CORPORATION. Feb. 29, 1948 [Sept. 5, 1941], No. 6365/48. Class 60. An abrasive-particle-throwing apparatus comprises a feed spout structure including a cylindrical boss having a passage therein communicating with an external opening for discharging abrasive particles at a limited portion of the periphery of said boss, a rotatable impeller including circumferentially spaced outwardly impelling vanes arranged for rotation around said boss to pick up the abrasive particles issuing from said passage and discharge them into the path of a set of peripherally disposed throwing blades, said vanes being shaped to control the degree of rotation which the picked up particles undergo in the vanes before they are moved outwardly into a controlled zone in the path of the blades for limiting the peripheral-range over which the blades throw out the particles, and a stationary guard member embracing only a portion of the impeller periphery adjacent the controlled zone. A centrifugal wheel of the downblast type is mounted in a housing having side walls 11, 12, front and rear walls 13, 14 and a hinged top 15; the housing, which is provided with internal wear plates 18, is supported by angle irons 19, the bottom of the housing being open for discharge of abrasive. The wheel comprises a rotor assembly R carried by a flange 23 secured to a flange 22 on a driving shaft 20. The rotor assembly R comprises a disc 25 to the face of which sector plates 26 are secured, the adjacent edges of which are spaced apart and bevelled to form grooves receiving bevelled flanges 31 on the blades 27 which are retained by a ring 28, projections 32 on the blades locking into a groove 33 in the ring 28. Abrasive from an elevated hopper is fed by gravity into a feed spout 34 the upper end of which is secured by an angle bracket 37 to the housing wall 13. A holder 41 has a cylindrical section 42, fitting within an opening 39 in the housing wall 13, and a flange 43, engaging a recess 44 in the housing wall 13. The holder 41 is secured in position by clamps engaging the flange 43 and secured to the housing wall 13. An opening 47 in the holder 41 receives a flange 48 on a feed spout extension 49 having an opening 50 receiving a shoulder 51 on the lower end of the feed spout 34, a flange 52 in which is engaged by a clamp 53 secured to the holder 41 by a bolt 54; leakage is prevented by a gasket 55. The spout extension 49 has a control boss 57 and a flange 56, extending through about 270 degrees, secured to the holder 41 by bolts 58; the boss 57 has a substantially straight and unobstructed passage 59 registering with the discharge end of the feed spout 34. Immediately above the passage 59 the boss 57 is formed hollow at 60 to reduce weight and economize material. The discharge end of the feed spout 34 and the inlet end of passage 59 have a cross-section shaped like a flattened pear. A portion of the right wall of the discharge end of the passage 59 is removed at 62, permitting a greater unobstructed flow of abrasive in a path slightly inclined in the direction of rotation of the wheel. The transfer mechanism includes a vaned impeller 64 having a face 65 arranged to abut against the outer end of a flange 23<SP>1</SP> of the rotor and held in engagement therewith to rotate with the rotor by a bolt 66 passing through a hole in an interior boss 67. The impeller 64 has a cylindrical portion 68 terminating adjacent the inner edges of the blades 27, and a second hollow frustum-shaped section 69 spaced therefrom and connected thereto by a series of impeller vanes 71. The inner surface of section 69 is curved at 72 to aid in the guiding of the abrasive onto the inner ends of the vanes 71. Flanges 73, 76 on the section 69 co-operate with a rib 74 formed on the interior of a guard 75 of arcuate shape. A flange 77 on the impeller 64 co-operates with an arcuate flange 78 on the guard 75. The guard 75 is formed as an arcuate shield about a portion of the periphery of the impeller 64 and is provided with an arcuate flange 79 shaped to fit within the open section of the flange 56 of the spout extension 49. The guard 75 is secured to the holder 41 by screws. The impeller vanes 71 are circumferentially spaced from one another and their forward surfaces comprise a substantially radial face 82 and a forwardly inclined surface 83. Abrasive fed downwardly from the passage 59 on to the inner ends of the vanes is collected in individual charges by faces 82 and discharged by centrifugal force along surfaces 83, the inclination and curvature of which is such as to retard the discharge of the abrasive until the vanes 71 reach approximately the twelve o'clock position at the left end of guard 75 as viewed in Fig. 3; at this selected point, the abrasive is discharged on to the inner ends of the blocks 27, the discharge therefrom beginning at approximately 90‹ further around the periphery of the wheel, and being in a downward direction. The guard 75 functions to collect the 'stray particles of abrasive which are discharged from the vanes 71 at other than the desired point of discharge and return them to the main stream of abrasive. Serrations 63 function as deflectors for the abrasive particles contacting the outside of the spout extension immediately clockwise of the point of feed and return the particles back into the path of vanes 71. To discharge sidewise to the right, guard 75 is positioned as shown in Fig. 11, passage 59 being adjusted clockwise short distance to discharge abrasive at a point slightly forward of the position shown in Fig. 3. Vanes 71' are formed with rearwardly curved surfaces 82<SP>1</SP> terminating in substantially radial faces 83<SP>1</SP>. The individual charges of abrasive pass rapidly along surfaces 82<SP>1</SP> to surfaces 83' from which they are discharged on to the inner ends of blades 27; guard 75 functions to return stray particles of abrasive to the main stream. By the selective use of different impellers having variously shaped vanes the direction of discharge on to the inner ends of the rotor blades can be varied so as to adjust the point or zone of discharge from the periphery of the wheel.