| 摘要 |
PURPOSE:To contrive to improve accuracy in polishing the inner periphery of a lengthly pipe by installing a pressure tube, inside a grindstone holder, for bringing the grindstone in pressure contact, with the inner periphery of a pipe to be polished through a process of filling the inside with fluid to be expanded. CONSTITUTION:Each grindstone 1 for polishing the inner periphery 9 of a pipe to be polished is supported by a grindstone holder 3. Inside of the center of this grindstone holder 3 is hollow and therein a bladder type pressure tube manufactured from rubber or the like is installed. And this pressure tube expands when inside of which is filled with fluid, and then it presses the back of each grindstone 1 uniformly and at the same time its reactive force retains the grindstone holder 3 itself in the center of the axis of the pipe to be polished. As the result of this, each grindstone 1 is pressed against the inner periphery 9 of the pipe to be polished with the desired uniform pressure resulting from fluid pressure, therefore it is possible to accurately polish the inner periphery even if it is a lengthy pipe.
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