| 摘要 |
In driving tubes (1, 2) used in the advance method, the leg (3a, 4a), running in the longitudinal direction of the tube, of one angled joint section (3, 4) each is embedded approximately in the centre between the inner surface and outer surface of the tube. The leg (3b, 4b) of one joint section, which leg (3b, 4b) runs transversely to the tube axis, is firmly connected at its marginal zone to the opposite marginal zone of the joint section of the adjacent tube by adhesive bonding or welding. At least one of the two joint sections (3, 4) also has a third leg (3c) which extends to the outside transversely to the tube axis and during driving serves as a pressure-transmission means in the same way as the legs (3b, 4b) connected to one another. In centrifugal casting, this leg serves to centre the joint section in the centrifugal mould. <IMAGE>
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