| 摘要 |
PROBLEM TO BE SOLVED: To provide a mandrel guide which makes the coating film of a release agent almost uniformly thick by keeping a vacuum pressure in the vacuum crosshead of an extruder high and uniform. SOLUTION: A mandrel guide 8 is fixed by a fastening ring 9 to the rear end part of a cylinder 2, and has an annular inner face protrusion part 10 with an archlike longitudinal cross section shape formed in a mandrel through hole 7. When a mandrel 12 which tends to bend easily passes through the mandrel through hole 7, a region with which the arc face of the annular inner face protrusion part 10 follows up being displaced and thus the mandrel through hole 7 is kept airtight. Consequently, the degree of internal vacuum of a crosshead is kept high and uniform. In addition, when the release agent is applied to the mandrel 12, it is possible to make the thickness of the coating film of the release agent constant and thereby enhance the release effect. |
