| 摘要 |
A device for making a doubled-walled pipe having a wear-resistant internal pipe and a shock-resistant external pipe. The internal pipe is prefabricated. The external pipe is made from an initial pre-curved metal sheet. The shaping of the external pipe around the internal pipe is effected by means of tools which are pressed against the metal sheet. The parts of the tools are placed directly on the metal sheet on at least three lines distributed around the circumference and extending longitudinally over the length of the sheet. Using the parts of the tools, a clamping force is applied to the metal sheet perpendicularly or parallel to the edge of the metal sheet which is placed around the internal pipe to form the doubled-walled pipe.
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