Disc Springs

 

1. What is a Disc Spring?

It resembles a “metal bowl,” known professionally as a Disc Spring or Belleville Washer. Its cross-section is inverted conical, storing energy through “compression-rebound.” Stacking identical springs alternately, like LEGO bricks, instantly amplifies tiny deformations into ton-level forces.

 

2. Why can it “achieve big results with small means”?

The core lies in its “high stiffness + nonlinearity.”

A standard disc spring with thickness t=0.5 mm and outer diameter D=40 mm can generate approximately 2 kN of force with just 0.3 mm of compression per leaf.

• Stacking 20 leaves maintains the same 0.3 mm compression stroke but yields a total force of ≈40 kN (≈4 tons).
• Switching to “paired” stacking (flipping individual discs) doubles the stroke ×20 while maintaining force, resulting in a total stroke of 6 mm.

 

3. Three-Step Selection Process

Step1 Calculate load: F = (4E·t³·f) / ((1-μ²)·D²·K₁·K₄)

Step2 Select material:

60Si2MnA: General purpose, -40°C to 120°C

Inconel 718: High temperature 600°C, no relaxation

Step3 Verify life: N≈(σ/σ₀)^b, b≈8~10, σ₀

4. Practical Case Study

① High-speed punch press mold Issue:

Stamping at 500 spm, standard springs failed after 2 weeks.

Solution: Replaced with 50-piece paired disc spring assemblies, extending life from 500,000 to 8,000,000 cycles.

② Wind turbine spindle bearing preload Issue: Preload decay at -30°C. Solution: Inconel 718 disc spring assembly, 10 years maintenance-free.

③ Aerospace Solar Wing Hinge Issue: Requires “hard lock” during launch phase and “micro-elasticity” in orbit.

Solution: Two-stage series disc springs, achieving 90% stiffness reduction upon unlocking for rigid-to-flexible transition.

5. Pitfall Avoidance Guide

Avoid “stacking to the limit”: Over 20 layers may cause lateral slippage; guide sleeves are recommended.

Surfaces must undergo phosphating + molybdenum disulfide coating; otherwise, high-frequency “screeching” may occur.

Tightening torque ≠ compression: Disc springs exhibit rebound hysteresis after compression; always verify with actual measurements using micrometer shims.