抄録
Experiments of induction bending at the actual processing site have been performed on the STPG370-E steel pipe from which the systematic data on profile, temperature, strain and dimensions with such parameters as diameter, thickness and bending radius. The obtained data show that the processing is a good success with all the parameter cases, and that some characteristics of induction bending, including appearance of real deviation such as asymmetry from the ideal state and actual situation as mentioned below, were observed. Thermocouples measured the temperature distributions around the induction coil whose peak was just below 1000°C, width along the x-axis was about160mm to 300mm, and the graph curve resembled the shape of a smooth mountain. Two axial strain gages measured the strain distributions along the straight area of the pipes which were simple, and suggested the bending moment acts the area to generate 0. 034% elastic strain. We used our own tracing instrument newly created to draw the profiles of the bent pipes well which proved that springback can be ignored. An ultrasonic thicknessmeter measured the thickness along the bent area to calculate the rates of variations which were in the range of 20% to 30%, satisfied the requirement and showed that in the harsher conditions like 2DR case they fluctuated wider in accordance with time. Vernier caliper measured the diameters along the bent area to calculate the rate of variation in ovality which was almost less than 1% to 3% and a diameter tape measured the circumferential length. These results satisfy the requirement while they show some interesting features of the process. The obtained data with various contrivance can be available for verifying the accuracy of coming FE analyses.
