| 摘要 |
In a known production process for double-walled tubes, the dimensional tolerances of the core tubes and of the jacket tubes are large enough to ensure that the tubes can be fitted into one another without problems and, after being fitted together, can be brought into firmly fitting contact with one another by hardening the core tubes a number of times. This method can be employed for double-walled tubes where it is possible to pass a hardening device through the core tube. The invention provides a method which also allows the production of double-walled tubes with outside diameters less than about 100 mm. For this purpose, the core tube 1 is first of all hardened and then inserted into the jacket tube 2, a process which involves the expansion of the latter. The tolerances of the core tube 1 and of the jacket tube 2 are closely matched. After the expansion process, the transverse contraction behaviour of the jacket tube 2 is exploited to fix the core tube 1 in the jacket tube 2. <IMAGE>
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