Method and apparatus for bending long member, and method for bending door frame

摘要

A method of bending a long member includes applying a tensile force to the long member to draw out the long member in a lengthwise direction thereof, measuring a displacement of the long member after commencement of the application of the initial tensile force, and bending the long member by applying a correction tensile force and a bending pressure for bending the long member into a curved shape in the lengthwise direction simultaneously to the long member upon the displacement exceeding a predetermined tensile fracture threshold value within a predetermined period of time or after a lapse of the predetermined period of time without the displacement exceeding the tensile fracture threshold value. The correction tensile force is smaller than the tensile force at the time the displacement exceeds the tensile fracture threshold value or the tensile force at the lapse of the predetermined period of time.

主权项

1. A method of bending a long member, comprising:
applying a tensile force, which increases from an initial tensile force, to said long member to draw out said long member in a lengthwise direction thereof; measuring a displacement of said long member after commencement of said application of said initial tensile force; bending said long member by applying a correction tensile force and a bending pressure for bending said long member into a curved shape in said lengthwise direction simultaneously to said long member upon said displacement exceeding a predetermined tensile fracture threshold value within a predetermined period of time; and after a lapse of said predetermined period of time without said displacement exceeding said tensile fracture threshold value, said correction tensile force becomes smaller than said tensile force when said displacement exceeds said tensile fracture threshold value or said tensile force at said lapse of said predetermined period of time.