Patent GB-1458476-A (GB)
Title: Polishing apparatus
IPC: B24B37/10
Filed: 1974-11-15
Abstract: 1458476 Polishing BUEHLER Ltd 15 Nov 1974 [17 May 1974] 49449/74 Heading B3D Apparatus for automatically polishing specimens for purposes of microstructural analysis comprises a generally cup-shaped member 28 mounted on a housing 13 and having a flat base or polishing surface 36 on which abrasive slurry or the like may be dispersed and over which a specimen is moved, a specimen drive arm 40 supported on the housing for composite axial and pivotal movement and having an outer end engageable with a specimen, first drive means 58 mounted in the housing for rotation about a fixed axis, a drive motor 64 connected to the first drive means, second drive means 100 rotatably mounted eccentrically on the first drive means, means interconnecting the first and second drive means so that the first means rotates the second, means interconnecting an inner end of the drive arm to an eccentric portion of the second drive means, and guide means 50 intermediate the ends of the drive arm, whereby a composite motion is imparted to the inner end of the drive arm and a related composite motion is imparted to the outer end of the drive arm and a specimen engaged therewith. The cup-shaped member 28 has a wall and a base portion formed with a non-circular projection 32 engaging a recess 30 in a horizontal portion 18 of the housing. A glass platen 34 carrying an abrasive or polishing disc 36 is non-rotatably located in the member 28 which may be partially filled with abrasive slurry. A specimen mount 38 is located within the member 28 and connected by a pointed arm 42 to one end of the drive arm 40, an intermediate portion of which is secured to a cylindrical bushing 44 slidable between a pair of parallel guide plates 50 whereby its drive arm is axially movable and pivotable about the axis of the bushing. The inner end of the drive arm is connected by a yoke 70 to a pair of pins 78 extending from a bush 80, the pins permitting pivotal movement of the arm to facilitate loading of a specimen. The bush 80 is rotatable on a pin 84 eccentrically mounted on a pulley 88 carried by a drive plate 60 rotatable by a motor 64. The pulley is also connected by a belt 124 to a second pulley 102 secured to a shaft which is mounted in bearings in the plate 60 and has a gear 116 engaging a stationary gear 104 whereby as the plate 60 is rotated to move the pulley 88 in a circular orbit, the gears impart a rotation to the pulleys about their own axes. Thereby the inner end of the drive arm moves with a low speed in a first large circular path on which is superimposed a higher speed motion in a smaller circular path. The specimen is biased against the abrasive disc 36 either with a constant load or with a variable or decreasing load by a spring 132 connected, at one end, to the bush 44 and arm 40 and, at the other end, to a lever 142 movable about a pivot 143 and having an end 144. A cam 134 is mounted on a rod 150 which is axially and rotatably adjustable by a knob 156 and is secured to a stop disc 164 co-operating with projections 166, 168, 169. The rod 150 and cam 134 can be moved to an extreme right hand position, as shown in Fig. 4, in which the projection 168 engages a notch in the disc 164 and the cam 134 is disengaged from the end of the lever 142 so that no load is applied to arm 40 and the arm can be pivoted upwardly to facilitate loading of a specimen. When the rod 150 is moved to an intermediate position, it can be rotated so that the cam 134 pivots the lever to a desired position, a spring 174, upon release of the knob 156, urging a roughened portion of the disc 164 against projection 168 to prevent further rotation of the cam so that a constant load is applied by spring 132 on the specimen. In the extreme left hand position of the rod 150, the rod 150, and hence the cam 134, is automatically rotated during the polishing operation to vary or decrease the load applied by the spring 132 to the specimen by actuation of a one-way clutch 182 on the rod 150. The clutch has an arm 184 which is urged by a spring 190 against a stop plate 186 and is rockable by a lever 183 mounted on a pivot 192 and having an end 196 engaged by an eccentric pin 198 in the hub portion of the drive plate 60 driven by the motor 64.