Factors Affecting Dimentional Accuracy of Free Height of Compression Coil Springs on Compression Coil Forming

In spite of a demand for an improvement in the dimensional accuracy of compression coil springs formed with an automatic coiling machine, factors affecting the dimensional accuracy of compression coil springs have not yet been clarified. Under the circumstances the assurance of the dimensional accuracy of compression coil springs has been left to skilled workers.To improve these circumstances, the Research Committee on Compression Coil Forming was established in July of 1990 and implemented to make clear factors affecting the dimensional accuracy of compression coil springs until June of 1997.The purpose of this paper is to show the results of experiments of the committee conducted to demonstrate the influence of loop uniformity, shapes and positions of coiling tools, and initial tension of compression coil on the free height dispersion of compression coil springs which had been taken up from among other factors.