An analysis of the spiral spring.

This thesis reports what is believed to be a new approach to the analysis of the spiral (clock-type) spring based on a re-thinking of the fundamental equations. Detailed examination of this type of spring has led to the discovery that the free spiral form approximates to a logarithmic spiral. Methods of examining the free spiral form are described and what are thought to be unique methods ·of determining its equation are presented. Knowledge of the spiral equation enables the moment-rotation characteristic to be constructed which is then compared with experimental results obtained on a testing machine designed by the author. This machine allows measurements of torque to be obtained without introducing machine friction. It has been designed to allovl autographiC recordings to be made of the spring test. Prediction of the spiral equation from consideration of the elastic-plastic behaviour of an idealised material has been achieved and charts have been produced which will facilitate this prediction. The relationship between the back-tension during winding and the free spiral form has also been investigated. A further research programme has been outlined which, together with the present findings, should lead to a complete understanding of the mechanics of the spiral-spring forming process however performed.