| 摘要 |
The invention relates to a plastic tube sealing device comprising a clamp which has a pair of jaws that can move relative to each other for inserting and crimping a plastic tube, said jaws containing high-frequency (HF) jaw electrodes (12a, 12b), and comprising an electrical HF power supply circuit (8) including an HF generator (10) and the HF jaw electrodes. The plastic tube sealing device according to the invention further comprises an impedance control device (9) for acting towards maintaining an impedance of the HF power supply circuit constant during a respective welding operation by correspondingly controlling the variable impedance HF resonant circuit. For this purpose, the HF generator includes a variable impedance HF resonant circuit with a capacitor unit (13) and a coil unit (14), and comprising the jaw electrodes, wherein the inductance of the coil unit and/or the ohmic resistance of the HF resonant circuit is/are variably adjustable and/or wherein the capacitance of the capacitor unit is variably adjustable and the capacitor unit comprises an electrically controllable capacitance diode or at least one movable capacitance-altering capacitor electrode arranged in the clamp. A plastic tube sealing device of this type can be used, for example, for welding of blood collection tubes for blood donation bags. |
