Torsion springs are mechanical components designed to store and release energy through elastic deformation when subjected to torsional loads (forces applied perpendicular to the spring’s axis). The ends of torsion springs can be customized into hooks, straight arms, or other specific shapes to meet various installation and operational requirements. These springs are versatile in design and are widely used in numerous mechanical systems and applications.

Design Parameters of Torsion Springs

The design of torsion springs depends on the specific application and mechanical requirements. Due to their diverse shapes and configurations, torsion spring designs often involve detailed calculations and considerations. Below are the primary parameters to consider when designing a torsion spring:

1. Free Length: The natural, uncompressed length of the spring.
2. Control Diameters:
   • Outer Diameter (D): The maximum external diameter of the spring.
   • Inner Diameter: The internal diameter of the spring.
   • Tube Inner Diameter: The inner diameter of the tube that the spring fits into.
   • Shaft Diameter: The diameter of the shaft the spring will surround.
3. Wire Diameter: The diameter of the spring wire (also referred to as “gauge”).
4. Material: The type and grade of the spring material (e.g., carbon steel, stainless steel, alloy steel).
5. Number of Coils and Orientation: The total number of coils in the spring and whether it is right-handed or left-handed.
6. Torque Requirements: The torque the spring needs to provide at a specified deflection angle (measured in units such as Newton-meters or pound-force).
7. Maximum Deflection Angle: The maximum angle the spring can safely twist without damage.
8. End Configuration: The shape of the spring ends, such as hooks, loops, straight arms, or custom designs.

When designing torsion springs, it is essential to specify key geometric and mechanical parameters, including:

• Wire diameter (d)
• Outer diameter (D)
• Arm length (L)
• Free height (Lo)
• Additional geometries, such as moment arms (T1, T2, … Tn) and their corresponding torsional angles (Ψ).

Torsional Angle Calculation

When a torsion spring is subjected to a load, the material inside experiences a neutral bending shear stress state. The calculation of the allowable torsional angle primarily depends on the material’s strength.

• The maximum allowable torsional angle is determined by the material’s failure point. When the material yields (undergoing plastic deformation), the spring will not return to its original state.
• Using the von Mises stress theory, the maximum allowable stress must not exceed the material’s strength limit. This ensures the spring operates within its elastic range.
• By combining material properties, geometric parameters, and load conditions, the maximum allowable torsional angle can be accurately calculated to ensure the spring’s durability and performance.

Applications of Torsion Springs

Torsion springs are essential mechanical components that utilize elastic deformation to perform various functions. Their main applications include:

• Controlling Mechanical Motion: Regulating and stabilizing movement in mechanical systems.
• Shock Absorption and Vibration Damping: Minimizing the transmission of impact forces and vibrations.
• Energy Storage and Release: Storing energy under load and releasing it when required.
• Force Measurement: Measuring the magnitude of applied forces through spring deformation.

Due to their adaptability and reliable performance, torsion springs are widely used in industrial machinery, household appliances, vehicles, aerospace equipment, and many other fields.