GB675643A - Method of and apparatus for grinding or polishing solids of revolution - Google Patents

Abstract

675,643. Grinding and polishing. FOUQUET, E. Dec. 14, 1950, No. 30579/50. Class 60. A work-piece 1, Fig. 1, formed as a solid of revolution is ground or polished by plunging it into a mass 14 of powdered or quasi-fluid abrasive material under pressure and causing relative angular movement between the work-piece and the abrasive material. In Fig. 1, the workpiece 1 is attached to one end of a shaft 2 rapidly rotated on a spindle 3 which receives a limited axial reciprocation. The abrasive, which is in the form of a powder or paste, is held in a flexible container 13 secured to a cover 5 which is in turn secured to an air-tight box 8 connected through a valve with a supply of fluid under pressure, e.g. compressed air. When the valve is opened, the container 13 contracts so that the abrasive surrounds the work-piece. Fig. 3 shows a construction in which pressure is applied to the abrasive by mechanical means comprising two jaws 27, 28 which embrace the container 13 and may be moved towards and away from each other by a rod 29 having right and left-hand threads. The cover 5 from which the container is supported is secured by rotatable clamps 17 having recesses to accommodate a flange 33 on the spindle 3. These recesses are dimensioned to allow the spindle to be reciprocated by a hand lever 34 pivotally connected by a link 35 to the frame of the apparatus. The shaft 2 is rotated by a belt drive 39. Fig. 5 shows an apparatus for treading bicycle hubs. The hub 70 is clamped to the shaft 2 by a nut 69. The abrasive container consists of a cylinder 54 with a rubber lining 53 and a cylinder 49 with a flexible pocket 56. The lower end of the latter is clamped to a piston 62 connected by a rod 64 with a piston 65 free to slide in a cylinder 51 to the lower end of which fluid under pressure may be admitted to compress the pocket 56 and surround the hub with abrasive. The piston 65 is biassed by a spring 67 to its lowermost position. To compensate for the difference in rubbing velocity of the abrasive in contact with varying diameters of the hub, two wedge-like members 75 are provided which form convergent passages with the hub. The members 75 are secured to spring-loaded, axially-displaceable rods 83 so that when fluid under pressure is admitted to cylinders 77 the members 75 are moved towards each other and into proximity with the hub 70, the rubber lining 53 being deformed. The fluid supply to the cylinders 51 and 77 may be operated either independently or from a common valve. When a number of polishing operations with successively finer grades of abrasive have to be effected, a number of abrasive containers corresponding to the number of operations may be mounted on a conveyer which brings them in turn into operative relation with the work-piece. The pressure on the abrasive container may be varied or interrupted during each polishing operation.