| 摘要 |
PURPOSE:To prevent breakage and wear of a projecting and recessing pattern embossed on the surface of a roll, and to prolong a life time of the roll, by using, as a band-shaped metallic material, a steel band having a softened layer formed on the side to be worked of the material. CONSTITUTION:In a rolling mill using, at least, one variable crown roll between its rolling rolls, a projecting and recessing pattern, of which tips are pointed, is formed on the surface of the variable crown roll respectively and continuously in the directions of roll axis and circumference. As a blank material for a heat transfer pipe; a steel band having a softened layer, of which the thickness is the same as or larger than the depth of embossing worked on the surface of one side of the material is used. This steel band is rolled by the mill, and is slit after transferring said pattern embossed on the surface of the variable crown roll to the surface of the blank material, then the material is manufactured into a pipe material in a conventional electric welded steel pipe manufacturing line. |
