| 摘要 |
At least one section of the screw (11) has a wear-protection layer (13) and at least one other section of the screw preferably has an anti-friction layer (18). In a solid rod (11'), abed (12) for the wear-protection layer (13) is first formed, and in this the wear-protection layer (13) is then applied, and finally the interstices (14) between the screw flights (15) are formed. According to the invention, the wear-protection layer (13), for example composed of tungsten carbide, is applied by build-up welding, and the interstices (14) are formed with lateral separation (16, 16') with respect to the wear-protection layer (13). For production of the anti-friction layer, the dimension of that/those section(s) of the screw (11) where the anti-friction layer, e.g. composed of molybdenum, is to be applied is reduced below specification, while providing lateral separation (19) with respect to the wear-protection layer. The anti-friction layer is then applied in the under-dimensioned region (17). Finally, the screw (11) is brought to the specified dimension. |
