METHOD OF PRODUCING DIFFERENT THICKNESS STEEL PLATE AND DEVICE FOR FORMING DIFFERENT THICKNESS

摘要

PROBLEM TO BE SOLVED: To provide a method of producing a different thickness steel plate without using welding and performing complicated roll gap control.SOLUTION: The method of producing a different thickness steel plate comprises: a roll forming step of gradually performing bend-forming on a steel strip with rolls for forming arranged in many steps while sending the steel strip continually, thereby forming a nearly circular cross-section material having a nearly circular cross-section; a step of conveying the nearly circular cross-section material to a device for forming different thickness composed of a fixed die and a mandrel having a diameter different in a longitudinal direction without welding the end of the nearly circular cross-section material; a step of forming different thickness in the longitudinal direction of the nearly circular cross-section material by removing and inserting the mandrel inside the fixed die; and an unbending-forming step of relieving the bending added to the material in the roll forming step, in order to relieve the bending of the nearly circular cross-section material to thereby form a steel strip.