Patent GB-1191153-A (GB)
Title: Process and Apparatus for the Continuous Surface Treatment of Articles
IPC: B24C3/08
Filed: 1967-05-01
Abstract: 1,191,153. Blasting. WHEELABRATOR CORP. 1 May, 1967 [19 May, 1966], No. 20057/67. Heading B3D. [Also in Division B8] Apparatus for the surface treatment of large shaped articles comprises:- (i) at least one open support member for retaining a said article therein; (ii) means for transporting the or each said support member to a loading station; (iii) means for transporting the or each loaded support member from the loading station on to a conveyer means; (iv) means for displacing the or each said loaded support member endwise along said conveyer means through a blasting zone; (v) means for throwing particulate treating material at high velocity on to the article during travel through the blasting zone whereby particulate material engages the exposed surfaces of the article for treatment; (vi) means for rotating the or each loaded support member during travel along the conveyer means through the blasting zone for maximum exposure of the said surfaces to the treating material; (vii) means for displacing the or each loaded support member from the conveyer means to an unloading station after passage through the blasting zone, and (viii) means for displacing the article endwise from the or each support member while in the unloading station to free the or each support member for return to the loading station. Cages 20 are cycled through the apparatus with workpieces supported therein during travel of the cages from a loading station through a blasting zone to an unloading station. Each cage comprises rings 22, 24 connected by bars 26 sloping inwardly from the rings to form tapered entrance portions 30 and a central portion corresponding with the cross-section of the workpiece 36. One bar has an abutment 27. An empty cage positioned at the downstream end of a conveyer 32 is displaced laterally to a loading station 34 where it dwells while a workpiece 36 from a conveyer 38 is inserted endwise into the cage. The cage is then displaced laterally on to a conveyer 40 extending lengthwise through a blast cabinet 42 having wheels for throwing particulate blast material; the conveyer 40 comprises a pair of rotating cylindrical sections for rotation of the cages during passage through the blast cabinet. The cages are displaced stepwise along the conveyer 40 by a pusher mechanism engaging the cage at the upstream end of the conveyer. A loaded cage reaching the downstream end of the conveyer 40 is displaced laterally to an unloading station 46 where the cage dwells while the workpiece is moved endwise out of the cage on to a delivery shoot. The empty cage is then displaced laterally to the upstream end of the conveyer 32. The conveyer 32 comprises an elongate trough formed of downwardly inclined side walls 60, 62, preferably curved, having between their bottom edges a slot 66 in which runs an endless chain 68 trained over sprockets 70, 72, the sprocket 70 being driven by a motor 74. To effect separation between the leading cage and the following ones the conveyer has means for arresting the second cage as the first is displaced to the end of the conveyer. This comprises a solenoid 50 having a stop pin 52 movable into and out of the path of the rings 22, 24 of the cage; downstream of the stop pin a distance less than the length of a cage is a switch 54 having an arm 56 extending into the path of the rings 22, 24. When a leading ring engages the arm 56 the switch 54 is made so activating the solenoid whereby the stop pin is extended into the path of the trailing ring to stop the cage. An air or fluid cylinder may be used instead of the solenoid 50. Transfer of the empty cage from the downstream end of the conveyer 32 to the loading station is effected by a U-shaped rocker arm 90 pivoted to the frame and having at its free end a curved plate 96 in lengthwise alignment with the conveyer slot 66 to form an extension thereof and having a length greater than that of a cage. The arm 90 can be pivoted upward by an air cylinder 104 so that the cage is lifted from the conveyer for lateral displacement on to a rail or platform 98 down which the cage rolls on to rollers 100, 102 at the loading station. Return of the arm 90 to its lowered position is signalled to the solenoid 50 for withdrawal of the stop pin 52. For supporting and rotationally adjusting the cage at the loading station, spaced rollers 100, 100 and 102, 102 are mounted on shafts 101, 103 driven by a motor 128. A cage stop 130 extends into the path of the cage abutment 27 to arrest the rotation of the cage when it is in proper alignment for receiving a workpiece 36 which has been delivered by the conveyer 38, e.g. a slat conveyer, to a position in endwise alignment with the cage. The workpiece is displaced endwise on to a shelf 142 and into the cage, which is backed up by one or more bars 144 to prevent axial movement, by a ram 146 suspended from a carriage 151 mounted on rollers 152 and operated by an air cylinder 150. Transfer of the loaded cage from the loading station to the conveyer 40 is effected by a pivoted arm 172 which can be raised by an air cylinder 161 to lift the cage off the rollers 100, 102 on to a ramp 178 over which it rolls on to conveyer rollers 180, 182 for passage through the blast cabinet 42. The rollers 180, 182 of the conveyer 40 are elongate and mounted on shafts rotated by a motor. The portion of the conveyer on to which the loaded cages are deposited is enclosed in an entrance vestibule 199 and a portion of the conveyer between the vestibule and the blast cabinet is enclosed in a tunnel 201. Stepwise endwise travel of the loaded cages along the conveyer is effected in response to forward displacement of the cage last to be deposited on the conveyer by a ram 202 suspended from a carriage 206 mounted on rollers 212 and operated by an air cylinder 210. The blast cabinet 42 is a sheet-metal housing having a length corresponding to several cages, e.g. five or six, and has entrance and exit openings provided with flexible flaps. Blastant is fed from a hopper 232 to throwing wheels 230 delivering downwardly on to the rotating loaded cages. Spent blastant falls into a trough 236 and is fed by a screw conveyer 238 to an elevator 240 raising it to a separator 242 from which clean blastant passes to the hopper 232. The cages may rotate at 40 r.p.m. and be displaced at a rate of 900 per hr. From the blast cabinet the cages advance through a covered section 250 to an unloading vestibule 252 within which and below the conveyer rollers is a cradle having wheels 258 riding on spaced tracks 260 each having a level entry portion 262 and an upwardly inclined portion 264. Arms extending upwardly from the opposite ends of the cradle lift a cage off the conveyer rollers when the cradle is moved up the incline 264 by an air cylinder 265. To effect lateral displacement of the raised cage through a door opening in the vestibule on to a ramp 278 for delivery to the unloading station a shaft 282 has arms 288 extending angularly downwardly to the outside of the cage with an end portion 286 turned inwardly to underlie longitudinally spaced apart portions of the raised cage but to clear the rollers when the cage is lifted; the arms are rocked by an air cylinder 290. At the unloading station the loaded cage comes down the ramp 278 on to spaced rollers 300, 300 and 302, 302 on shafts 304, 306 driven by a motor 308 to rotate the cage until a cage stop is engaged by the abutment 27 on a cage bar. The workpiece is pushed from the cage on to a delivery ramp 319 by a ram 324 carried by a carriage 328 mounted on rollers 332 and moved by an air cylinder 330. Endwise movement of the cage is prevented by a backing- plate. To effect transfer of the emptied cage to the conveyer 32, a pivoted arm 358 is raised by an air cylinder 346 lifting the cage off the rollers 300, 302 for displacement laterally on to a ramp 364 over which the cage rolls on to the conveyer 32. Sequential operation is effected by limit switches.