Introduction to Variable Force Springs: What They Are and How They Work

Variable force springs, also known as variable rate springs, are mechanical springs that change their amount of resistive force throughout their compression or extension. Unlike traditional springs that have a fixed rate of resistance, variable force springs can provide a different amount of force depending on the degree of compression or extension. These unique properties make them ideal for many applications, especially those that require a constant force.

The basic design of a variable force spring consists of a coiled strip of metal, usually made from stainless steel or other high-tensile alloys. The coiled strip is designed to provide resistance against compression or extension, depending on the direction of the force applied to it. The strip is wound in such a way that it provides a varying amount of resistance throughout its travel, creating a non-linear force curve. This non-linear force curve means that the amount of force required to compress or extend the spring increases or decreases depending on the distance traveled.

To understand how variable force springs work, it is important to understand the concept of the spring rate. The spring rate is a measure of the amount of force required to compress or extend a spring a certain distance. Traditional springs have a fixed spring rate, meaning that the amount of force required to compress or extend them is constant throughout their travel. Variable force springs, on the other hand, have a variable spring rate.

The variable spring rate of a variable force spring is achieved through the unique design of the coiled strip. The strip is wound in such a way that the coils are closer together at one end and farther apart at the other end. This means that the amount of material that is compressed or extended increases or decreases depending on the distance traveled. This, in turn, changes the amount of resistance provided by the spring, creating a non-linear force curve.

Variable force springs are used in a wide range of applications, including automotive, medical, aerospace, and industrial. One of the most common uses of variable force springs is in the automotive industry, where they are used in seat belts, clutch mechanisms, and suspension systems. In medical applications, variable force springs are used in prosthetics and orthotics to provide a constant level of support or resistance. In the aerospace industry, they are used in landing gear systems and flap mechanisms to control the movement of the aircraft.

In conclusion, variable force springs are a unique type of mechanical spring that provides a varying amount of resistance throughout their compression or extension. Their non-linear force curve makes them ideal for many applications that require a constant level of support or resistance. Understanding how they work and their applications can help engineers and designers choose the right spring for their specific needs.