| 摘要 |
<p>The shank is used for centering the tool into a bore of a workpiece with said tool, particularly for centering a welding head in a welding pipe with a plate. The shank has at a free end a ball race (3) wherein a plurality of centering balls (4) are retained, distributed at the peremeter thereof. These balls may be moved radially inwardly from an operating position where they form a protuberance on the peremeter of the lining (5) of the race. In their operating radial position, they are supported and blocked by the peremeter of a cylindrical section (6) of a mandrel (7). The mandrel (7) is provided in order to unblock the centering balls (4), a conic portion (8) extending towards the free end of the shank from its cylindrical section (6). The mandrel may be removed with its cylindrical portion from the centering balls (6) against the force of a spring (9, 12). </p> |
