| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a new form-rolling method in which a working condition for improving the productivity as much as possible can be set very easily while maintaining the desired form-rolling property when form rolling a shaft part of a variable blade built in a VGS type turbocharger. SOLUTION: A shaft part forming part 12a of a blank work W for the variable blade 1 is form-rolled into the desired diameter. When selecting the number of revolution R of a form-rolling roller and the feed speed V for bringing a set of form-rolling rollers 61 close to each other, the working condition is set in an area AR surrounded by a locus showing the relationship between the number of revolution R and the form-rolling property P of the form-rolling roller when the feed speed V of the form-rolling roller is set to the critical minimum value Vmin, the line with the number of rotation R of the form-rolling roller being the critical maximum value Rmax, and the line with the degree of the form-rolling property P being the critical minimum value Pmin on the graph with the number of rotation R of the form-rolling roller and the degree of the form-rolling property P different from each other.</p> |
