| 摘要 |
This invention is related to a device for hot working, preferably hot forming or welding of plastics. comprising electric heating means for said hot working and a control device for supplying electric heating power to said heating means. Said control device comprises a) power restricting means (3), b) means (9) for setting a maximum heating power, said setting means (9) being connected to a control unit (4) which controls said power restricting means, c) means (6) for measuring the heating temperature, said means being connected to said control unit (4), the signal from said temperature measuring means (6) acting through said control unit (4) on said power restricting means (3) to continuously or in a plurality of steps, preferably at least 3 steps, which preferably are essentially of equal size, restrict the heating power when exceeding a particular, pre-selected temperature, and d) pulse control means (8) arranged for maintaining the heating power switched-on for an adjustable period of time during at least one continuous pulse period. The invention is also related to a process for hot working, preferably hot forming or welding plastics, with the aid of electric heating means for said hot working, especially resistance heating means, in which the feeding of electric heating power to said heating means is controlled for at least one continuous pulse period. |
