Three Things About Constant Force Spring

What is Constant Force Spring？

Constant force spring also known as Coil spring,which can continuously provide a large restoring force in a small space. After a mechanical part completes a stroke, it can return the part to its original position to prepare for the next stroke. Currently, it is widely used in garden tool starters, vacuum cleaners and other wire-reeling parts.

The Function of Constant Force Spring

Constant force springs are generally used as the power of micro-machines without using electricity, such as the power of mechanical clocks and timekeeping systems; the power of mechanical phonograph records; mechanical music boxes; automatic pianos; the power of wind-up toys, etc. The common point of these machines powered by coil springs is that the transmission chain is a speed-up mechanism, rather than a reducer commonly used in machinery. In addition, the torque output by the coil spring is large when it is tightened, and the output torque will be much reduced when it is close to full relaxation. In order to reduce this uneven output torque of the spring, this type of device has a speed stabilizing mechanism, which is used to stabilize the speed of the mechanism. In mechanical watches, in order to reduce this torque difference, the spring is deliberately made into an S shape when in a free state, rather than a flat equidistant spiral line, so that the output torque of the coil spring is relatively balanced.

The Design of Constant Force Spring

The design of the constant force spring must determine the minimum driving torque and the maximum torque that can be used; the torque and speed of the final actuator to be driven; and the total driving time and other factors. These factors should be selected from the table in the relevant design manual, and the size of the barrel and the size and module number of teeth of the gear should be determined. After testing, the parameters of each part should be modified and finally determined.

Application of Constant Force Spring

Most constant springs can be used to achieve automatic reset within a certain range. For example, when drilling with a bench drill, press the feed handle to move the drill bit downward. After drilling the hole, let go and the drill bit will automatically rise back to its original position. That is, a coil spring is installed in the shaft of the handle. There are many examples of using coil springs for reset in mechanical equipment, and they are widely used in various automatic machines, printing machines, and packaging machines. In addition, coil springs are often used for balancing. For example, a component is installed on a vertical guide rail, which needs to move up and down along the guide rail and can be stably stopped at any position. The up and down movement of the component is pulled by a chain. The lower the component is, the longer the chain becomes. Since the chain also has weight, it is heavier than when the component is at the upper end of the guide rail. This causes the component to be in different positions at the top and bottom, and the total weight of the component plus the chain is different. For this imbalance at different positions, coil springs can also be used to add balancing force. The common box ruler is also an application example of a coil spring, which can reduce the volume. The use of coil springs is not as widespread as torsion springs. The main reason is that the production is complicated. Usually, professional manufacturers are found to make them. However, if the number of coil springs is small, the price is very high. The manufacturers cannot make money and are unwilling to do it. If too many coil springs are made, it will cause a lot of waste if they do not meet the requirements, and the technicians will lose face. At the same time, the production cycle is relatively longer. Therefore, designers generally try not to use coil springs. In most cases, coil springs are worth using only when the product volume is large.

SNMHardware provides many types of constant force springs and also undertakes the manufacturing of customized constant force springs.