GB1066714A - Improvements relating to the finishing of parts - Google Patents

Abstract

1,066,714. Finishing. ROTO-FINISH Ltd. Dec. 20, 1963 [Oct. 16, 1962], No. 39098/62. Heading B3D. A workpiece, e.g. of steel, such as a helically toothed gear, is finished, i.e. deburred, ground or polished, by burying the workpiece in a mass of loose solid chips or particles of abrasive material flooded with liquid and rotating the workpiece, while it is buried, at a speed of at least 500 r.p.m., first in one direction and then in the other. An electric motor 10 drives, through a chain, a spindle 11 at a speed of at least 500 r.p.m., the preferred range being 500-1000 r.p.m. although speeds up to 1500 r.p.m. may be employed. The motor speed may be fixed, variable in steps or infinitely variable. The spindle 11 has a collet for enabling a workpiece W to be removably secured to the spindle for rotation therewith, the collet being operable by a pusher rod 13 connected to a lever 14 rocked by a pneumatic jack 16 controlled by a foot operated valve. A sub-frame 21 movable vertically relative to the main frame by a pneumatic jack 22 carries a tub 20 containing a mass of abrasive material. Also mounted on the sub-frame 21 are a tank 23 and a motor driven pump 24, the latter pumping liquid from the tank through a hose 26 into the tub. The liquid is drained off from the bottom of the tub and passed through a filter, the cleaned liquid being returned to the tank. With the sub-frame 21 in its bottom position, a workpiece W is fixed in the collet. The pump 24 is set in operation, and two timers associated with the motor 10 are set manually to equal or unequal periods. Subject to the closure of doors 33, motor 10 is started. Operation of the motor starter initiates operation of the pneumatic jack 22 to raise the sub-frame. When it reaches its top position the sub-frame 21 actuates a limit switch to set the first timer in operation; when this times-out an electrical signal reverses the motor 10 and sets the second timer in operation; when this times-out an electrical signal stops the motor 10 and returns the sub-frame to its bottom position. The apparatus described may be used to put a small radius on the crowns of the gear teeth of a hardened crown wheel for a motor car and remove hardening scale. Small partially rounded rock chips are then used. A fine abrasive is used for polishing. The pneumatic jack 22 may reciprocate the sub-frame 21 automatically throughout the cycle, reversing valves or limit switches being associated with the jack. The tub 20 may be rotated about an axis parallel to, but off-set from, the axis of rotation of the spindle 11.