| 摘要 |
PURPOSE:To remove a lengthwise strain of a crosslinked polyethylene (XLPE) tube almost completely, by passing the XLPE tube continuously through an aqueous solution which is the mixture of water and ethylene glycol (EG) at a specified weight ratio and heated at a constant temp. CONSTITUTION:An optimum heating temp. to remove strain of an XLPE tube is about 120 deg.C which is higher than a softening point of XLPE and lower than its flow point. Meanwhile, as for a relation between a mixing ratio of water and EG and the boiling point of the aqueous solution, the boiling point of the aqueous solution whose mixing ratio of water: EG is 1:2 is just 120 deg.C. Consequently, when this aqueous solution is used, the temp. of the aqueous solution is always kept at its boiling point, 120 deg.C. For example, a heating bath 6 which is filled with EG aqueous solution 4 and contains a heater 5 is set up between a delivery apparatus 2 and a take-up apparatus 3 of a XLPE tube 1. The XLPE tube 1 sent out of the delivery apparatus 2 runs continuously through the EG aqueous solution 4 at 120 deg.C in the heating bath 6 heated, and thereafter it is taken up with a take-up apparatus 3. |
