| 摘要 |
<p>A method of forming a longitudinal groove in the wall (1) of a passage comprises inserting a mandrel (3) into the passage to engage the wall of the passage, said mandrel including a working surface (5) which, when the mandrel engages the wall of the passage, is located facing, and in a predetermined spatial relationship with, the portion of the wall in which the groove is to be formed. A carriage (7) is then forced to run through said passage along the working surface of the mandrel. The carriage carries a forming member (9) such that as the carriage moves along the working surface the forming member forms a groove in the wall of the passage with the base of the groove parallel to the working surface of the mandrel. By making the working surface (5) converge with the passage wall (1) a groove of progressively increasing depth can be formed.</p> |
