| 摘要 |
<p>PURPOSE:To easily find out welding inferiority, by detecting whether an electric characteristic is abnormal from the current allowed to flow to an electric heating wire after the completion of welding work. CONSTITUTION:When a switch 4 is closed, a current flows from a high voltage source and the resistance value of a heating coil 2 is inputted to a control apparatus 3 and the kind of a pipe joint 1 is discriminated. Then, in order to apply the power quantity corresponding thereto to the coil 2, a variable resistor 5 is controlled. Simultaneously with the opening of the switch 4 after the completion of welding, the switch 6 on the side of a low voltage source is temporarily closed and a weak current is allowed to flow to the coil 2 for a short time. The resistance value of the coil 2 at this time is compared with a resistance value at a normal time by the control apparatus 3 and, when said value exceeds a normal range, an alarm circuit 8 is closed to emit an alarm. By this method, welding inferiority can be simply found out.</p> |
