| 摘要 |
PROBLEM TO BE SOLVED: To automatically and easily examine the properties of pores such as air transmittance and porosity over the entire area of a porous pipe during the production of the pipe made of polytetrafluoroethylene(PTFE). SOLUTION: The one end 32 of the PTFE pipe 30 is fixed in a cylindrical mold 34, the pipe 30 is made movable in the other end 33 direction of the pipe 30 with the other end 33 closed and heated at a temperature which is the softening point or above and lower than the melting point of PTFE, compressed gas is supplied from the end 32, and the pipe 30 is expanded/elongated to be porous and cooled while being pressurized. A pressure detected by a pressure gage 7 set between a valve 4 for supplying the compressed gas and the end 32 of the pipe is level-discriminated at a point of time t4 when a predetermined time W3 measured by a timer after the valve 4 is closed with the completion of molding has passed.
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