| 摘要 |
PROBLEM TO BE SOLVED: To realize the supply of the heating steam, the pressure of which is controlled in a short period of time, and consequently the stable and efficient production of an expanded plastic product can be obtained. SOLUTION: At the beginning of molding, steam is fed under the condition being feed-back controlled to a primary set pressure value on the basis of the value of the pressure detected at a drain discharge valve or within a molding chamber. Next, thermal expansion treatment is performed by feeding the steam under the condition being feed-back controlled to a final set pressure value on the basis of the value of the pressure detected at a steam valve. Further, a first feed-back circuit 6 for controlling the stem valve 2 on the basis of the signal of a first detector 5 provided at the drain discharge valve or within the molding chamber and a second feed-back circuit 8 for controlling the steam valve 2 on the basis of the signal of a second detector 7 provided on the outlet side of the steam valve 2 are provided. Furthermore, the first and the second feed-back circuits 6 and 8 are made changeable over them by means of a changeover valve 9. |
