| 摘要 |
The manufacture of hollow articles, e.g. outer members of cross groove type constant velocity ratio universal joints, having an internal surface with two sets of grooves whose axes of symmetry are different in respect of their helical pitch or hand. A tool for manufacture of such a hollow article comprise two sets of elements (A1, A2) disposed circumferentially between one another about the axis of the tool, the elements having portions (24, 27) which interfit to define a surface whose shape corresponds to that required in the article, the portions having formations (31, 32) which form the sets of grooves. The elements (A1, A2) are so shaped that the portions (24) of the first elements (A1) can be moved radially inwardly to disengage their formations (31) from the grooves formed thereby, after which the tool can be removed from a finished article by movement of the formations (32) of the second elements (A2) along the grooves formed thereby. |
