GB857781A - Improved method and means for barrel finishing - Google Patents

Abstract

857,781. Tumbling. ROTO-FINISH Ltd. June 27, 1957 [March 27, 1956], No. 9520/56. Class 60. A method of finishing work-pieces by tumbling them together with polishing materials in a barrel 1 comprises rotating the barrel about a horizontal or approximately horizontal axis, continually feeding the polishing material and work-pieces into an inlet aperture 8, and discharging them continually through an outlet aperture 10 having its lower edge at a lower level than the lower edge of the inlet such that the difference in level causes the progression of the contents through the barrel. If desired, periods of continuous introduction and discharge are alternated with periods during which no fresh material is introduced and discharge is prevented, tumbling being continued without substantial axial movement of the material in the barrel. As shown, the inlet and outlet apertures 8, 10 are provided in rigid end walls 7, 9 attached to the barrel and are in the form of circular holes concentric with the axis, the outlet aperture being larger in diameter in order to obtain the difference in level between the lower edges of the apertures. The difference in level may be varied by changing the apertured end walls or by partially blanking off one of the apertures. Alternatively, either or both of the openings could be formed by an aperture in a stationary end plate which is in sealing engagement with the rotating drum, the level of the lower edge of the opening then being adjusted by altering the height of the plate. In another arrangement, the rigid end wall of the drum may be in the form of a resilient diaphragm having a central aperture bounded by a collar engaging with a non-rotating locating member which may be adjusted in order to stretch the diaphragm and thereby alter the level of the aperture ; such an arrangement may be replaced by an iris-type diaphragm which can be adjusted during rotation of the barrel. In operation, polishing material, such as rock fragments and an abrasive, either dry or included in a liquid, may be initially introduced through a shoot 11 and distributed along the length of the dum by rotating the latter at high speed ; this is followed by the introduction of the workpieces and move tumbling media for the finishing operation proper. Discharge occurs through a shoot 12 at a rate dependent upon the setting of the outlet aperture 10. To increase the treatment time, the feed is stopped at intervals and the discharge prevented by either closing the outlet aperture or, aligning its lower edge with that of the inlet, thus preventing any progression of the workpieces during the continued rotation of the barrel. Alternatively, the feed may be interrupted and the level allowed to fall to that determined by the discharge aperture. The barrel is rotated by an electric motor 5 driving through a pinion a toothed ring 6 secured to the barrel which is supported on rollers 3 mounted on a base 4.