| 摘要 |
Split tubes or spiral tubes have hitherto been produced by a process in which a flat metal strip has first of all been notched on one or both sides and, after the notching operation, fed to a tube profiling device. This method of proceeding is associated with disadvantages especially where the flat metal strip is composed of a steel with a high carbon content. This material is work-hardened by the notching process and, as a result, becomes very brittle, so that a fracture of the length of the material in the tube profiling device in the region of the previously produced notches may easily occur. In contrast, the invention envisages a process in which the flat strip of material is first of all formed in a profiling device to give a split tube or spiral tube (3) and then notched at the circumference. For this purpose, the invention provides a notching device with a revolving tool carrier (51), the notching tools (55) of which are brought into contact with the surface of the spiral tube (3) at intervals for only a short period of time. Contact occurs at least twice for each notch (6) but the two contacts are circumferentially offset relative to one another. By positioning the notching device after the profiling device and by virtue of the special design of the notching device, it is now possible to produce notched profiled tubes (3) from flat metal strips composed of steels with a high carbon content. <IMAGE>
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