| 摘要 |
PURPOSE:To enable the internal surface of a long hole to be accurately ground, by interposing a spreading member with a wedge surface between ends of a rotary grindstone and a spacer, which are inserted to an equal depth into the hole to be ground, and grinding its internal surface while adjusting a distance between the both grindstone and spacer. CONSTITUTION:After a rotary grindstone 4 and a spacer 5 are inserted into a hole 1 to be ground, a spreading member 12 with a wedge surface 11 provided on a headstock 3 is advanced to a position in which the wedge surface 11 is brought into contact with a sloped surface 10 of the spacer 5 while a protrusion 13 protrusively provided in an opposite direction to the wedge surface 11 is brought into contact with the end of a rotary shaft 6 of the grindstone 4. And the spreading member 12, if it is further advanced by the hydraulic pressure or the like, spreads a distance between a curved surface 9 of the spacer 5 and a grinding surface 8 of the grindstone 4 by causing the wedge surface 11 to move outward the spacer 5. On the contrary, the spreading member 12, if it is retreated, contracts the distance between the curved surface 9 of the spacer 5 and the grinding surface 8 of the grindstone 4 by moving the spacer 5 inward by elasticity of a supporting bar 7. In this way, the hole 1 to be ground, if it is ground by rotating the grindstone 4 while adjusting the distance, is ground in good dimensional accuracy.
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