| 摘要 |
The actual welding temperature is fed to the control unit(8) and compared with a set value stored in the data carrier(10) on the plastic fitting(2) and using an adjustable variable the temperature is controlled to the set temperature for optimum welding quality. A set temperature for preheating and another for the welding event are also stored in the data carrier together with the time/set temperature profile. The actual welding temperature is recorded on the basis of either the physical properties of the heating wire(14), a melt pressure sensor or magnetic, especially high frequency properties. A tolerance band is provided for the set temperature during welding. The control unit(8) performs several tasks, e.g. heating to the set temperature, measuring temperature, carrying out safety checks and controlling the resulting adjustable variable. The data carrier(10) contains fixed control parameters, especially welding temperature and/or preheating temperature and/or heating wire temperature coefficients and/or welding and preheating times and cooling times. The control variable remains constant during the measuring and control cycles of the control circuit or can be switched on and off at intervals. A further temperature sensor(30) at a precise distance from the melting zone checks whether the heating wire and hence melt has reached a prescribed limit and a signal from this sensor halts the welding action. |
