| 摘要 |
PURPOSE:To control the contraction of a weld zone so as to cause no inner part stress by welding the completed welding part with heating in case of welding in order the plural reinforcing bars projecting in parallel approx. from a member and the tip of the similar reinforcing bars of other member respectively. CONSTITUTION:PC members A, B are arranged so that the tips of a reinforcing bar A1... and reinforcing bar B1... can be opposed with some separations to weld the reinforcing bar A1 and B1. After completion of this welding the surrounding of the weld zone is quickly covered by the heater 1 of a contraction control device and heated so that the reinforcing bars A1, B1 can maintain the temp. state of the weld time. With this state the reinforcing bars A2 and B2 are welded, after the completion of which, the weld surrounding zone is heated with covering by the heater 1 quickly. Reinforcing bars A3, B3 are similarly welded and after completion of all weldings all heatings by the heater 1 is quickly stopped and removed. All welding parts are thus cooled under the same conditions, starting a contraction uniformly. The contraction control device equips with the temp. regulating device to control the heating of the heater 1 by the signal transmitted from the sensor 3 to detect the temp. (or strain) around the weld zone being heated by the heater 1.
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