Spring is one of the most commonly used parts in the mechanical and electronic products industry. It can produce very large elastic deformation when it is loaded, and this elastic deformation also transforms mechanical work or kinetic energy into deformation energy, which can unload the change of spring, and disappear and return to the original shape, finally, finally. Transformation of deformation energy into mechanical work or kinetic energy. With the continuous progress of the times, the application of spring is very wide, the automobile, computer, TV, pin, phone, cell phone and so on are used in many things in the daily life of the spring. (1) the spring can control the movement of the machine, for example, the valve springs in the internal combustion engine, the control springs in the clutch, etc. (2) it can absorb the energy and impact energy of vibration, for example, the cushioning spring and the vibration absorbing spring in the coupling. (3) it can be used as a power to store and output energy, such as the springs of watches and clocks and the springs in guns. (4) springs can also be used as components for measuring forces, such as springs in dynamometer and spring scales, etc. The ratio of the bearing and the deformation of the spring is the stiffness of the spring as we often call it. The greater the stiffness, the harder the spring is.