Cylindrical Torsion Springs

Cylindrical torsion springs are helical springs, typically with round wire, designed to exert a rotational force or torque about their central axis when their ends are rotated. They are used to hold components in place, return a mechanism to a starting position, or provide a constant torque.
Design and Function
The core function of a torsion spring is to store and release angular energy.
Torque Generation: The spring is mounted over a shaft or arbor, and when a rotational force is applied to its "legs" (ends), the coils deflect, resisting the movement and storing energy.
Rotational Movement: When the applied force is released, the spring unwinds to its original position, delivering the stored energy as torque to drive the attached components back.
Load Direction: Torsion springs are specified for a particular direction of wind (right-hand or left-hand) and should be loaded in a direction that causes the coils to tighten to maximize efficiency and service life. Unwinding them from their free position can reduce fatigue life.
Leg Configurations: The ends of the spring (legs) are crucial for attachment and can be formed into various custom shapes, bends, or hooks (e.g., straight offset, straight torsion, hinge, short hook ends) to suit specific application needs.
Materials
The material selection depends on the operating environment, load demands, and temperature requirements. Common materials include:
High Carbon Steel (e.g., Music Wire ASTM A228): A general-purpose, economical choice with high strength and good fatigue life, commonly used in high-stress applications.
Stainless Steel (e.g., Type 302, 316, 17-7PH): Offers excellent corrosion resistance and performs well across a wide temperature range, making it ideal for marine, medical, or food processing applications.
Alloy Steels (e.g., Chrome Silicon, Chrome Vanadium): These materials provide superior strength, toughness, and fatigue resistance for heavy-duty and high-stress environments.
Non-Ferrous Alloys: Specialty materials such as Beryllium Copper, Phosphor Bronze, or Inconel are used for applications requiring non-magnetic properties, electrical conductivity, or enhanced performance in extreme temperatures.
Common Applications
Cylindrical torsion springs are highly versatile and found in millions of products across various industries, from simple household items to complex machinery.
Clothespins: A classic example where the torsion spring provides the clamping force.
Garage Doors: Heavy-duty torsion springs are mounted above the door to counterbalance its weight, making it easier to open and close.
Clipboards: The spring mechanism in the clip that holds the paper in place is a torsion spring.
Hinges: Used in self-closing doors, appliance lids, or folding mechanisms to control rotational movement.
Levers and Pedals: Provide the necessary return force for brake or accelerator pedals in vehicles and various lever mechanisms.