| 摘要 |
<p>PURPOSE:To mold a foamed layer integrally combined with an inner layer by extruding melted resin for a material of a cover on to the outer periphery of melted resin for a material of a pipe integrally and in the condition of being melted and by expanding the same after it is extruded. CONSTITUTION:With dies 10 are connected an extruder 13 for resin 8a for the pipe and an extruder 12 for resin 9a for the material of the cover. From behind the dies 10 to the outer periphery of a core bar 11, the melted resin 9a for the material of the cover is extruded on to the outer periphery of the melted resin 8a for the material of the pipe. At this time, the resin 9a is kept still unfoamed in the dies 10. Since the joint part of the resin 9a with the resin for the material of the pipe is extruded in the state of being welded, the material of the cover is made to foam only in the direction of the outside thereof even when it is expanded after extrusion. Thus, the pipe 8 having a prescribed bore and the pipe cover 9 consisting of the foamed layer located on the outer periphery of the pipe are molded through extrusion.</p> |
