Coil springs are generally used as the driving force for micromachines without electrical energy, such as mechanical clocks and timing systems; the driving force for the rotation of mechanical gramophone records; mechanical music boxes; the power to wind up toys, etc. What this kind of coil spring drive has in common is that the transmission chain is a speed-increasing mechanism instead of a reducer commonly used in machinery. In addition, the output torque is larger when the coil spring is tightened, but when it is almost completely relaxed, the output torque will drop a lot. In order to reduce the uneven output torque of the spring, all 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 relatively balanced.
Coil spring design determines the size of the small driving torque and the size of the large torque that can be used; the torque and speed of the driving actuator; and the total time required to drive and other factors to select from the relevant design manual. The barrel size, gear size and module number of teeth are also determined. After testing, the parameters of each part are determined through calibration.
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, hold down the feed handle to move the drill bit downward. After drilling, once you let go, the drill bit will automatically rise back to its original position, that is, a coil spring is installed on 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, packaging machines, etc. Additionally, coil springs 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 the components are lowered, the chain becomes longer. Because the chain also has weight, it is heavier than the components at the upper end of the guide rail, so the up and down positions of the components are different, 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 commonly used box ruler is also an application example of coil spring, which can reduce the size. Coil springs are not as widely used as torsion springs. The main reason is that the manufacturing is complicated and usually made by professional manufacturers. But if we do less and the price is high, manufacturers still can’t make money and don’t want to do it. If you do too much, it will cause a lot of waste and cause difficulties 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.