What Is a Torsion Spring?
A torsion spring (torsion coil spring) is a spring that uses the repulsive force generated by the distortion caused mainly by the torsion moment.
Torsion springs are used by winding in a coil, but they may also be used by unwinding a coil.
Common everyday uses of torsion springs include clothespins.
Uses of Torsion Springs
Torsion springs are used in the following applications.
1. Opening and Closing Mechanisms of CD and DVD Drives in Personal Computers, Etc.
When the lid of a CD or DVD player is lightly pushed by hand, it is used in the mechanism that opens by recoil. Therefore, it can be opened and closed without turning on the power of the main unit.
Simply placing a spring eliminates the need for space for a motor.
2. Reclining Seats in Cars, Buses, Etc.
There is a mechanism to adjust the angle of the seat by pushing it with the back, and when the angle is returned to the original position, the force of the torsion spring is used to return the seat without pushing it by hand.
Principle of Torsion Springs
Torsion springs are the same coil spring, but there is a difference in the energy generated when the spring deflects.
A torsion spring is subjected to a torsion moment with the center of the coil as its axis.
In other words, compression coil springs and tension coil springs store torsion elastic energy in the material, while the torsion springs store bending elastic energy.
Therefore, torsion springs are used by exerting force in the rotational direction, while compression and tension coil springs exert force in the linear direction.
In designing a torsion spring, the number of coils, angle, inner diameter and length are determined.
The gap between the coils may or may not be tight, but when it is tight, resistance due to wear will cause torque variation.
A guide rod is placed on the inner diameter of the torsion spring, and the outer diameter must be selected so that the guide rod does not rub against the inner diameter of the coil (approximately 90%). (The outer diameter should be approximately 90% of the inner diameter.)
Torsion spring arms can be straight or bent, and are selected according to the environment in which they will be used.