NC Control Point Estimator for Shape-Controlled Coil Spring

Friction caused by side force on a damper axis results in riding discomfort. In order to cancel the side force, accurate shape control for coil springs have been recently become crucial. After designing a target coil shape using a finite element analysis (FEA), actual coiling processes can be done by a NC coiling machine(C/M). The problem with this method is that the NC coiling machine has its own characteristics which coiling experts have to consider when adjustments are made to the control points of the NC machine. This adjustment process usually takes significant amounts of time in order to meet the target coil shape, because the coiling experts do their adjustments by a conventional method based on their experience.

This paper describes how to automate the control point design process to reduce the coiling effort and to save time. An ARMA model is used for the coiling machine modeling and its dimensions are determined by the physical dimension of the actual coiling machine. Our own algorithm based on a linear descent method for control point adjustment is then proposed in this paper.