Spiral spring
A spiral flat spring (also known as a clock spring, power spring, or flat spiral spring) is a type of spring made from a flat strip of material wound into a spiral shape. Unlike helical springs, which are coiled vertically, spiral flat springs store and release energy through rotational motion.
Key Features of Spiral Flat Springs:
- Material:
- Usually made of high-carbon steel, stainless steel, or phosphor bronzefor flexibility and fatigue resistance.
- Sometimes coated for corrosion resistance.
- Design:
- Flat strip wound in an Archimedean spiral(constant gap between coils) or involute spiral (variable gap).
- One end is fixed to a central arbor (shaft), and the other is anchored to a housing.
- Energy Storage:
- Works on torsional (rotational) energy—unwinds when released.
- Follows Hooke’s Lawfor rotational springs:
T = k \cdot \thetaT=k⋅θ
where:
- TT= Torque (Nm)
- kk= Spring rate (Nm/rad)
- \thetaθ= Angular displacement (radians)
- Self-Retracting Mechanism:
- Often used in applications where the spring must rewind automatically(e.g., tape measures, retractable cords).
Types of Spiral Flat Springs:
| Type | Description | Common Uses |
| Power Spring | Stores high energy in tight spaces | Toy cars, wind-up mechanisms |
| Constant-Force Spring | Delivers near-constant torque | Retractable badge reels, seatbelts |
| Hairspring (Balance Spring) | Precision micro-spring | Mechanical watch regulation |
| Motor Spring | Used for mechanical drives | Clockwork mechanisms, gramophones |
Applications:
- Retractable Devices: Tape measures, dog leashes, vacuum cord reels.
- Timekeeping: Mainspring in clocks/watches.
- Automotive: Seatbelt retractors, starter motors.
- Toys & Gadgets: Wind-up toys, self-winding mechanisms.
Advantages & Disadvantages:
| Pros | Cons |
| ✔ High energy storage in compact space | ✖ Limited angular rotation (typically < 360°) |
| ✔ Smooth torque delivery | ✖ Can suffer from fatigue over time |
| ✔ Self-retracting capability | ✖ Requires precise manufacturing |
Design Considerations:
- Strip Thickness: Affects stiffness and torque.
- Number of Turns: Determines energy storage capacity.
- Housing Design: Prevents over-extension and buckling.
Would you like details on calculations (torque, stress analysis) or manufacturing methods for spiral flat springs?
This kind of spiral spring usually used in car seat and High-speed train’s curtain.
Welcome your inquiry.
