Patent GB-1170577-A (GB)
Title: Method of Treating Objects and apparatus therefor
IPC: B24B31/06
Filed: 1968-05-28
Abstract: 1,170,577. Vibratory finishing. ROTOFINISH CO. 28 May, 1968 [29 May, 1967], No. 25475/68. Heading B3D. A method for treating at least one object comprising (a) Introducing the object into a treating zone; (b) Causing it to move in an orbital path while imposing upon it at least one cycle of precessional motion in a direction substantially perpendicular to the plane of orbital motion, the cycle having a first portion during which the object moves with a low velocity and a second portion during which the object moves with a higher velocity; and (c) Discharging the object from the treating zone during the second portion of a cycle. A finishing apparatus comprises a plate 2 mounted by springs 3 on a base 1 and carrying an annular trough 5 and a tubular support 4. A motor 9 mounted in the support 4 drives a lower eccentric weight 10 and an upper adjustable eccentric weight assembly 11. The latter comprises an index plate 12 keyed to the motor shaft 13 and having one or more apertures engageable by a drive pin 16 affixed to a baseplate 15 rotatably mounted on the shaft 13. An eccentric weight 17 is rotatably mounted on the shaft 13 in contact engagement with the upper surface of the plate 15. A frame mounted on the plate 15 carries a rotary actuator 26 having a shaft to which is clamped a shifting arm 28 engaging a drive pin 29 fixed in the weight 17. A rotary coupling 30 comprises a fixed member 33 mounted on a frame 31, 32 and a rotating member 36; air lines 101, 102 are connected to the member 33 and lines 34, 35 connect the member 36 to the actuator 26. A diaphragm 40 separates the finishing chamber 6 into a charging zone 41 and a discharge zone 42, the major part of the chamber being a finishing zone 43. Mounted at the diaphragm 40 is an elevator duct 44 with its lower end positioned within the finishing chamber below the surface of the finishing mixture generally within the circumferentially inner zone and with its upper end positioned above the level of the finishing mixture, preferably above the top of the trough, and loading to a screen 52, through which finishing material returns to the charging zone 41 of the chamber 6, and a discharge spout 53 for finished objects. The actuator 26 comprises a stator 75 secured to a cylindrical body 56, and a vane 80 carried by a rotor 79. To vary the velocity of travel of the finishing mixture along the trough, or to stop it completely, compressed air is supplied, through a control valve, to the air lines 101, 102 and passes via the coupling 30 and lines 34, 35 to the actuator 26 which is thus rotated to one limiting position or the other, correspondingly adjusting the weight 17. For one position the forward velocity of the finishing mixture is a maximum and for the other position it is a minimum, which may be nil or even reversed. An actuator continuously adjustable over a range may be used. During operation, a long dwell of the finishing material in the chamber can be obtained by moving the weight 17 to the position for little or no forward motion of the mixture; when finishing is completed, the weight is moved to the position for rapid forward motion of the mixture thus ensuring that the mixture rises in the elevator duct 44. If one position of the weight gives a slow forward motion, so that finishing is completed as the mixture reaches the end of the chamber, a switch may be provided at the discharge zone 42 which is actuated by contactual, magnetic or proximity influence of the objects to cause automatic movement of the weight to the rapid forward motion position. The adjustment of the weight 17 may be effected (1) by apparatus operated by oil, water &c., (2) electrically, e.g. by an electric motor and gearing, or (3) mechanically, e.g. by rods and cams. A timer may be set to move the weight 17 to rapid forward motion position every ten minutes to discharge objects after a ten minute dwell. A number of cycles of rapid and slow (or nil) forward motion may take place from the time an object enters the finishing zone until it is completely finished; individual objects may thus be introduced into the tracking zone to coincide with a particular portion of each cycle, so that a number of objects are continuously finished while maintaining them in spaced apart relationship, the timing being such that an object reaches the discharge zone during a period of rapid forward motion. The slow (or nil) motion may last for 15 seconds and the rapid motion for 5 seconds.