| 摘要 |
<p>In order to produce a double-wall composite metal pipe, a pipe assembly made up of an outer pipe of carbon steel and an inner pipe of stainless steel inserted in the outer pipe is caused to advance relative to a plastic working device such as die or a series of rollers. Before the pipe assembly is caused to pass through the plastic working device, the outer pipe is heated to cause it to expand while the inner pipe is cooled to establish a temperature difference between the outer and inner pipes. The heated outer pipe is constricted by device of the plastic working means and caused to plastically contract against the outer surface of the inner pipe, while the cooled inner pipe is subjected to expanding force of a mandrel inserted in the inner pipe, the mandrel backing up the pipe assembly from within the inner pipe against the constricting action of the plastic working device. The pipe assembly thus subjected to the action of the plastic working device is cooled from the outside whereby the outer pipe is caused to shrink to firmly bind the inner pipe thereby to obtain an interference fit between the pipes.</p> |
