초록 ▼

A method and apparatus for bending elongate workpieces, particularly pipes, by applying a bending moment to the workpiece while inductively heating a cross-sectional zone of the workpiece to provide a nonuniform temperature distribution along the circumference of this cross-sectional zone by means o

A method and apparatus for bending elongate workpieces, particularly pipes, by applying a bending moment to the workpiece while inductively heating a cross-sectional zone of the workpiece to provide a nonuniform temperature distribution along the circumference of this cross-sectional zone by means of an induction loop which surrounds the workpiece and by cooling the workpiece in at least one adjacent zone. According to the method of the invention, within a partial region of the circumference of the workpiece to be bent, which partial region is to be set at a relatively low temperature, the electrical current of the induction loop is branched off into a plurality of partial currents of which at least one is inductively directed primarily onto the cross-sectional zone to be heated and at least one other partial current is inductively directed primarily onto an adjacent zone of the workpiece, and the inductive heating of the respective adjacent zone is partially or completely cancelled out by cooling. The branching may be realized in the apparatus by a bypass line which divides a portion of the induction loop into parallel branches.

대표청구항 ▼

In a method of bending elongate workpieces, particularly pipes, including: inductively heating a cross-sectional zone of a workpiece with a nonuniform temperature distribution along the circumference of said cross-sectional zone by means of an induction loop which surrounds the workpiece, applying a

In a method of bending elongate workpieces, particularly pipes, including: inductively heating a cross-sectional zone of a workpiece with a nonuniform temperature distribution along the circumference of said cross-sectional zone by means of an induction loop which surrounds the workpiece, applying a bending moment to the workpiece to bend the heated cross-sectional zone, and subsequently cooling the heated cross-sectional zone of the workpiece; the improvement wherein said step of inductively heating comprises: dividing the electrical current of the induction loop into a plurality of partial branch currents over a partial region of the circumference of the loop adjacent the partial region of the circumference of the workpiece which is to be set at a relatively low temperature; causing at least one of said branch currents to act inductively primarily on said cross-sectional zone to be heated and at least another of said branch currents to act inductively primarily on a respective adjacent cross-sectional zone of the workpiece lying outside of said cross-sectional zone to be heated; and, at least partially cancelling out the inductive heating of said respective adjacent cross-sectional zone by cooling same.