What Is a Volute Spring?
A volute spring is a spring made by winding a plate like a bamboo shoot.
The name “bamboo shoot spring” is derived from its shape, which resembles a bamboo shoot, and its ability to withstand a significant load in proportion to its volume.
A volute spring is made by winding up plates of hardened steel or stainless steel, shifting them little by little, and polishing both ends.
Usually, a wide range of plate thicknesses from 1mm to 30mm are used to manufacture volute springs.
Uses of Volute Springs
Volute springs are used in a wide range of applications, such as in small ball screw covers, and in large springs that absorb the shock of collisions in industrial equipment.
In an unusual case, a spring called a “bamboo shoot spring” is also used on bicycles.
This bamboo shoot spring is attached to the “quick release type” axle often used in cross bikes and mountain bikes. At first glance, it looks like a coil spring due to the narrow width of the plate material.
Characteristics of Volute Springs
Volute springs are known to have non-linearity in the load characteristic graph that expresses “load” versus “deflection”.
Non-linearity of the load characteristics of volute springs refers to a phenomenon in which the amount of deflection becomes smaller than the linearity of the load characteristics graph, even if the load is increased.
Generally, it is proven that the amount of deflection of a spring is proportional to the “load” and “effective number of turns”.
However, in the case of volute springs, as the load increases structurally, the wound plates gradually begin to adhere to each other, and the effective number of turns of the spring gradually decreases in effect, which is thought to break the linearity.
Volute springs can exert a substantial load relative to their volume, with a published record of 500 kN.
The rectangular plates used in volute springs are tapered to the appropriate dimensions in both width and thickness so that the ends of the plates (known as “sea wraps”) are horizontal and gradually thickened in the finished state.