Observing various electrical switches, it can be found that one of the two contacts of the switch must be equipped with a spring to ensure that the two contacts are in close contact and have good conduction. If the contact is not good, the resistance at the contact will increase, the heat generated by the current will increase, and in serious cases, the metal at the contact will melt. The two metal pillars of bayonet lamp holder are equipped with springs to ensure good contact;
as for the central metal sheet of screw lamp cap and all socket metal plates, they are spring plates, and their function is to keep both sides in close contact so as to maintain good contact. In a cassette tape, there is a reed of phosphor bronze, which makes the magnetic head in close contact with the tape by the elastic force produced by its bending deformation. There is a long spiral spring in the stapler. On the one hand, it is used to tighten the staples.
On the other hand, when the front nail is pushed out, the back nail can be sent to the front for comfortable pushing out. In this way, one nail can be pushed to the front automatically until all the nails are pushed out. Many machines feed automatically, and the automatic loading of bullets in automatic rifles relies on the function of springs. In addition, like clip for clothes, ball point pen and clip on pen cover are clamped on clothes by spring.