| 摘要 |
The invention relates to a method for determining the temperature-dependent state, in particular the melt state and/or the melt quantity of thermoplastic material when producing a weld seam (6), for example for joining thermoplastic parts (7, 7') by means of a plastics welding device. For process control purposes, a temperature-dependent electric state variable of the thermoplastic material of the plastic parts (7, 7') is measured continuously with and without applying heat to the plastic parts (7, 7') along the weld seam (6) and compared to a target value or to benchmark values. In the method according to the invention, the electric state variable that is used is preferably the permittivity of the plastic parts (7, 7') and the change thereof during the welding process. The permittivity is determined by means of a capacitor assembly (1), wherein the plastic material is used as the dielectric between the electrodes (3, 4) of the capacitor assembly (1). The capacitors (2) of the capacitor assembly (1) are preferably operated at different frequencies for the determination of the permittivity. |
