What Is a Coil Spring?
A coil spring, primarily made of metal wire, stores energy when compressed, pulled, or twisted. This energy then acts as a restoring force. There are three types of coil springs based on their function: compression springs for compression, tension springs for pulling, and torsion springs for twisting.
Coil springs are widely used in automobiles and machine tools to absorb shock and vibration, and in various machines and everyday items that require a return action, such as push buttons.
Uses of Coil Springs
Coil springs serve two primary functions: returning to their original length by repulsive force, and absorbing shock and vibration. Repulsive force applications include ballpoint pens, bicycle locks, and automatic tape measures. Shock-absorbing applications feature automobile suspensions and shock absorbers on Tarzan ropes.
Principle of Coil Springs
Coil springs operate on elastic energy from the wire’s plastic deformation. The restoring force is proportional to compressive displacement. The spring constant, determined by dividing the restoring force by displacement, varies with wire diameter. When selecting coil springs, both the spring constant and the spring length are important considerations.
For repulsive force applications, the spring constant is estimated based on the intended displacement and required force. In shock absorption, the spring constant is chosen based on displacement length and expected load. To avoid resonance, the system’s natural frequency should not match external periodic forces. Often, dampers are used alongside coil springs to provide resistance and control displacement rate.
Coil Springs in Dental Applications
In orthodontics, coil springs apply force to teeth for corrective treatment. They are often made from cobalt-chrome alloy and chosen based on the direction of tooth movement. Open coil springs widen the gap between teeth, while closed springs are used to close gaps. It’s crucial to ensure compatibility with the patient’s body to avoid allergic reactions.
Coil Springs for Automotive Applications
Automotive coil springs are integral to vehicle suspensions, often combined with shock absorbers. The spring’s characteristics, like wire diameter, length, and number of turns, influence the suspension’s performance. Various types of coil springs, such as equal pitch, unequal pitch, and nonlinear pitch, respond differently to shocks. While coil springs absorb shocks, shock absorbers paired with them help control vibrations more quickly.