| 摘要 |
A pipe-bending machine mandrel comprises a rigid member (5), which can be inserted inside a pipe (T) to be bent which has an internal dimension Di and can tilt herewith in a bending operation with a prefixed mean radius Rm as measured between the rotation centre (O) of a bending die and the longitudinal axis ( l ) of the pipe (T) to be bent. The rigid member (5) has a proximal side profile with respect to the rotation centre (O) comprising at least a concave intermediate portion as generated by a radius Rci section of circumference (50), and a distal side profile with respect to the same rotation centre (O) comprising two convex, divided, end portions as generated by respective radius Rce sections of circumference (51, 52), where Rci = Rm - (Di/2) + t , and Rce = Rm + (Di/2) - t , t being a term varying according to the accuracy of the dimensional characteristics of the pipe to be bent and of the curve to be obtained.
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