SE302577B - - Google Patents

Abstract

956,758. Grinding. SOC. NATIONALE DES PETROLES D'AQUITAINE. March 26, 1963 [April 10, 1962], No. 11900/63. Heading B3D. A machine for grinding thin sections, such as rock samples for microscopic examination, comprises a frame 1 having a bearer plate 2 to which is fixed a section-holding system consisting of a section-holding plate 7 on a shaft 6 rotated by a motor 10, and a grindstone-holding system consisting of a shaft 11 which is parallel to the shaft 6 and has a grindstone 18 at its end, the shaft 11 being rotated by a second motor 19 and axially displaceable by a fine feed mechanism 16 controlling a nut and screw system 17 acting on the shaft to move the grindstone relative to the section-holder plate. The shaft 6 of the section-holder plate is mounted in bearings beneath the plate 2 which is inclined at an angle of approximately 10 degrees from the horizontal, the shaft being connected by a chain 9 to reduction gearing and a motor 10. The shaft 11 of the grindstone, which is driven by belts 22 from the motor 19, is mounted in bearings in a support movable along guides 14 on the under surface of the plate 2. The slide is displaceable to move the grindstone towards or away from the sectionholder plate 7 by the screw-and-nut 17 controlled by the fine feed mechanism 16. The mechanism 16 is operated by a connecting rod 23 which is, at one end, adjustably connected to a bush 24 on the shaft 6 of the section-holder plate, and, at the other end, formed with a slot 27 receiving a pin 28 on a lever 29 having a pawl 30 engaging a ratchet 31 connected to the fine-feed mechanism 16. The end of the rod 23 has a hook-shaped member 32 which, when retained in the position shown by a finger 34, transmits movement from the rod to the lever 29 to feed the grindstone towards the section-holder plate. The length of the finger is adjustable by a knob 36 so that the finger, which moves with the grindstone support, is retracted from the member 32 when the sections are of the desired thickness, the member swinging away from the pin 28 which then slides in the slot without moving the lever 29. During grinding, the sections are sprayed with water or petroleum through nozzles 42, 43 connected to a pump 41 and settling tank 40. The sections to be ground are first rough-cut with a saw and then stuck to glass plates which are adhered to the glass surface of the section-holder plate 7; suction may be applied to assist in holding the sections on the plate. The plate may have a transparent recess and a source of polarised light provided behind the plate so that a microscope can be used to assess the colour transmitted by the sections and determine their thickness.