| 摘要 |
The improvement in the boring devices is adapted to cut grooves or cavities at the bottom of bored holes. It comprises a tool (3) containing a diaphragm (17) forming an expansion chamber to which a liquid under pressure can be supplied for radially displacing cutting elements (24) set with diamonds between a retracted position and a projecting working position. The measurement of the variation of the volume of the liquid under pressure in a chamber (26) enables the radial position of the elements (24) to be known.
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