An upset pipe bending machine to control automatically a bending radius by means of high-frequency induction heating was developed by us. By using this machine and by varying the bending radius
R/
D (
R : bending radius;
D : nominal outside diameter) and offset
e (eccentric distance), an experiment was conducted with respect to a condition to accept eccentric axial compression load of the pipe. Concurrently with this, thickness of the bending outside of the pipe was controlled. Furthermore strain measurement of the experiment where offset was changed under the condition that the bending radius
R/
D =1.5 and
R/
D =3.0 (respectively constant). This resulted in slight increase in the thickness of bending outside at
e =11mm. In the meantime, a small amount of decrease was noticed likewise at
e =13mm. Thus it is explained from the above that controlling the bending outside thickness is possible by changing the offset. In the experiments, carbon steel pipe for pressure service (STPG 370, JIS G 3454) of nominal number 2B×Sch80 is used.
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