This blog is translated from German with DeepL.
1. What is a torsion spring?
Torsion springs are used where torque must be generated or rotational energy must be stored in a structure.
2. Formation process
There are an infinite number of applications for torsion springs, which means that their designs are also almost unlimited. The spring body can be crowned, bulbous, conical, with or without coil spacing. The legs can be simple and straight from the body or can be manufactured with various bends or lugs: axial, tangential, radial, radial/tangential.
The material of the spring has a great influence on the design. This is sometimes a variable that can still be played with if the design space is given, but the force still needs to be “screwed”.
3. Principles
Basically, three criteria apply to the design of a torsion spring:
- Function: What function must the spring perform?
- Manufacturing: Can the spring be manufactured?
- Testing: Is the required force achieved and fatigue strength ensured?
4. Tips
Unfavorable:
- Coils inside (Fig a)
- Unguided spring
Favorable:
- Coils outside (of the hairpin)
- Firmly clamped spring ends
- Guiding of the body on a mandrel
(Fig b)
Fig. c and d = firmly clamped spring ends, Fig. e and f = guiding the body on mandrel
5. In the past and today
In the past, it was necessary to calculate the forces with the aid of a so-called “calculating disc”, taking all factors into account, or to set the forces on the disc. However, this required a great deal of specific knowledge about torsion springs and their behavior.
Today, you can easily use online tools. You “only” have to enter the desired mass or forces and you will receive “ready-made” springs as 3D models. The designer’s job is then to integrate and test the spring. The challenges are often the installation space, force ratios, assembly and ultimately the cost of the spring.
