Extension Springs

The full name spiral extension springs, is also called tension springs.

The extension springs are designed to cause tension and store energy. It is similar to a compression springs and are also made of wire coils. The difference is that most of the tension springs have adjacent coils in close contact with each other. If the coils are to be separated, an initial force needs to be applied. When the tensile force acts on the springs, if the force is greater than the compressive force, the springs begin to deform, and the tensile load is called the initial tension strength. The typical initial strength is about 10-25% of the maximum design tension.

In order to facilitate the use on different occasions, the ends of the tension springs are often designed as hooks/loops of different shapes, mainly considering the installation requirements, installation space and load characteristics of the mechanism. For tension springs, all coils are effective. In addition to the coiling of the end hook/loop, which affects the actual spring force of the springs, it is also important to note that the end hook/loop is also its weakest part, especially when subjected to fatigue loads. Therefore, we recommend that at the beginning of the design, the shape of the end hook/loop should be as simple as possible.

Unlike the compression springs, the tension springs can become a tight barrier to prevent overload, so the stress level is lower than that of the compression springs. Applying the characteristics of its axial load, tension springs have different shapes due to their different use environments. The end face of the tension springs will use hooks to connect the tension spring body to the force source, and hooks, loops or holes are made at the two ends at different positions from the spring body. The position may be on the side or the center. In principle, the spring body and the hook are used one-piece manufacturing to reduce costs, roughly divided into the following types: