| 摘要 |
PURPOSE:To control preheating surely and to obtain the reliability of welding by detecting the electric currents flowing in a flash welding machine, integrating the same at a constant period, comparing the same with a reference current value and moving materials to be welded forward or backward. CONSTITUTION:Electrode platens 2, 3 are provided on the secondary side of a welding transformer 1, and materials 4, 5 to be welded are held. The contact currents thereof are detected with a current detector 6. The outputs thereof are integrated with an integrator 7, and the results of the integration are stored in a sample holding circuit 8. A reset circuit 10 resets the integrator 7 thereby starting the next integration. The potential difference between the circuit 8 and a reference voltage setter 11 is outputted by an arithmetic unit 12 and this is amplified and is applied to a servocontrolling valve 14 and a cylinder 16, by which a movable platen 3 is moved. In this feedback controlling, sampling frequencies are selected and the periods, etc. for contacting and pulling back of the material 5 with and from the material 4 are controlled, whereby the preheating is controlled satisfactorily. |
