Abstract
A coil spring made of the wire with a diameter larger than 4mm, is generally subjected to shot peening to improve its fatigue strength.
The authors have previously investigated the effect of liquid honing using glass beads on the fatigue strength of piano wires, and obtained the experimental results showing that liquid honing was effective to improve the fatigue strength, for example, by 30% for the wire with 5mm diameter.
In order to make clear the effects of liquid honing and shot peening on the wires with various diameters, the rotating bending fatigue strength of shot peened piano wires were studied.
And the results were compared with the data for liquid honed wires. The results obtained are as follows:
(1) The optimum condition of shot peening to improve fatigue strength was different for each wire diameter, i. e. the modest degree of peening was suitable for small diameter but the stronger for large diameter.
(2) In case of the wire with a diameter less than 5mm, the fatigue strength of the liquid honed wire was higher than that of the shot peened wire. However, in case of the wire with a diameter larger than 5mm, the shot peening was estimated to be superior to the liquid honing.
