Coil springs can continuously provide large restoring force in a small space, and can return mechanical components to their original positions after one stroke to prepare for the next stroke. It is currently widely used in cord retracting components such as garden tool starters and vacuum cleaners.

　　Introduction to coil spring functions

　　Coil springs are generally used as the power for micromachines without electrical energy, such as the power of mechanical clocks and timing systems; the driving force for the rotation of mechanical gramophone records; the power of mechanical music boxes; the power to wind up toys, etc. What this kind of coil spring driven machinery has in common is that the transmission chain is a speed-increasing mechanism rather than a reducer commonly used in machinery. In addition, when the coil spring is tightened, the output torque is larger, but when it is almost completely relaxed, the output torque will be much reduced. In order to reduce the uneven output torque of the spring, these devices have a speed stabilizing mechanism 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 in the free state instead of a flat equidistant spiral, so that the output torque of the coil spring is more balanced.

　　For coil springs, the small driving torque and the large torque that can be used need to be determined; the torque and speed of the final actuator of the drive; and other factors, such as the total travel time, need to be found from the relevant design manual. The barrel size, gear size and module number of teeth are also determined. After the test, the parameters of each part are determined through correction.

　　Applications of coil springs

　　Most coil springs can be used to achieve automatic reset within a certain range. For example, when drilling with a benchtop drill press, press and hold the feed handle to move the drill bit downward. After drilling the hole, once you let go, 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 as reset in machinery, and they are widely used in various automatic machines, printing machines, and packaging machines. There are also coil springs that are often used for balancing. For example, there is a component installed on a vertical guide rail that needs to move up and down along the guide rail and can stop stably at any position. The up and down movement of the components is pulled by the chain. As components go down, the chain becomes longer. Because the chain also has weight, it is heavier than the components at the upper end of the guide rail. This results in different up and down positions of the components, and the total weight of the components plus the chain is also different. For this kind of imbalance in different positions, coil springs can also be added. The common box ruler is also an example of coil spring application, which can reduce the size. Coil springs are not as widely used as torsion springs. The main reason is that the production is complicated and usually made by professional manufacturers. But there is less work being done, the price is very high, manufacturers still can’t make money, and they don’t want to do it anymore. Doing too much will cause a lot of waste and make life difficult for technicians. At the same time, the manufacturing cycle is relatively long, so designers generally try not to use coil springs. In most cases, it is only worthwhile to use coil springs when the product is produced in larger batches.