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Traditionally coil springs were used for applications to exert one-dimensional force along a given spring coil axis. However, in recent years, there has been an increasing trend in using coil springs to provide forces in a multi-dimensional space. In this paper, an approach to construct a model of a coil spring for suspension systems using a spatial six degree-of-freedom parallel mechanism is presented. In kinematics and dynamics simulation, the use of a parallel mechanism to model a coil spring allows a designer to simulate six degrees of freedom spring characteristics with vehicle kinematics without using FEA feature embedded in the simulation software. This requires a significant amount of computational load and maybe a file format converter.

As for the McPherson strut, a force from the tire acts on the shock absorber producing a bending moment, which causes an increase in the friction acting on the shock absorber. Reducing the friction is one of the most important issues to improve the riding comfort of an automobile. The bending moment can be reduced by controlling the load axis of the coil spring assembled with the shock absorber. In order to control the load axis, several types of coil springs have been recently reported. This paper proposes another shape-controlled coil spring, called L-shape. The L-shape spring has the following advantages: (1) The load axis can be precisely controlled with ease; (2) Additional space is unnecessary; (3) Manufacturing tractability is increased. The proposed L-shape spring is validated analytically and experimentally in this paper. The effect of the L-shape spring for reducing the friction on a shock absorber is also experimentally confirmed.

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.