METHOD OF PRODUCING SHAPED STEEL CHANGING IN CROSS-SECTIONAL SHAPE IN LONGITUDINAL DIRECTION AND ROLL FORMING APPARATUS FOR SAME

摘要

A roll forming apparatus for roll forming for producing from a sheet material a shaped steel which varies in cross-sectional shape in a longitudinal direction comprises a first rolling die which has an annular ridge part which varies in cross-sectional shape in a circumferential direction; a second rolling die which has an annular groove part which varies in cross-sectional shape in a circumferential direction; and a drive device for the first rolling die and the second rolling die. At least transition parts of the side surfaces of the annular ridge part of the first rolling die are provided with relief so that the gap with respect to the side surfaces of the annular groove part of the second rolling die becomes broader inward in the radial direction.

主权项

1. A method of producing a shaped steel which varies in cross-sectional shape in the longitudinal direction from a sheet by roll forming, comprising:
a step of preparing a first rolling die which has a rotation shaft and an annular ridge part which varies in cross-sectional shape in a circumferential direction which is centered about said rotation shaft; a step of arranging said first rolling die so that the rotation shaft of said first rolling die becomes perpendicular to a sheet feed direction; a step of preparing a second rolling die which has a rotation shaft and an annular groove part which varies in cross-sectional shape in a circumferential direction which is centered about said rotation shaft; a step of arranging said second rolling die so that a gap which is equal to a thickness of said sheet is formed between said first rolling die and second rolling die and the annular ridge part of said first rolling die and the annular groove part of said second rolling die engage; a step of making said first rolling die and said second rolling die rotate synchronized; and a step of feeding a sheet between said first rolling die and second rolling die, wherein the side surfaces of the annular ridge part of said first rolling die are provided with relief so that the gap with respect to side surfaces of the annular groove part of the second rolling die broadens over at least part of the circumferential direction and at an inner side in the radial direction of said first rolling die, wherein said annular ridge part of said first rolling die is configured so that the relative angle between the ridgeline and the rotation direction of said first rolling die varies at least partially in the circumferential direction, and wherein the relief amount at said relief is set to vary in accordance with the relative angle between the ridgeline of the annular ridge part of said first rolling die and the rotation direction of said first rolling die.