| 摘要 |
The tool (1) consists of a support tube (4), with the cutting head fitted at the lower extremity. The cutting head consists of a casing (6), which is fixed to the lower extremity of the tube and contains a primary hole (24). A rotating shaft (10) is mounted on bearings within the casing and has its lower end (20) threaded. An inner base plate (14) is fitted so as to rotate with the shaft and is provided with the secondary hole (26). A rotating blade (16) is fixed to the inner base by means of a fixing device (22), which is screwed on to the threaded end of the shaft. A rod (39) is designed to be inserted into the primary hole (24) and the secondary hole (26) in order to prevent the rotation of the inner base. The rod is held in the correct alignment by means of an elastic element (36).
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