| 摘要 |
A method of automatically controlling the fusion process of thermoplastic resin articles is done in a stepwise fashion. In response to a start signal, a current is applied to an electrical resistance heating element for fusing together facing resin surfaces. Electrical characteristics of the resistance heating element are calculated upon increase of the power to a given level and the specific heat of the resin is calculated through ON-OFF control of the resistance heating element. The power is then raised through stages based on the electrical characteristics of the resistance heating element and the specific heat to determine variation coefficients of the characteristics and specific heat at each stage and through further ON-OFF control. Finally, the power increase is stopped as the variation coefficient of specific heat reaches or becomes smaller than a given value. With the power established at a constant level, the ON-OFF cycles are continued until the specific heat becomes equal to or lower than a preset value. At that point the power is terminated, establishing an optimal operating condition for accurately fusing together any type of thermoplastic resin and any articles made therefrom.
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