Clock Spring Technology Explained
Core Elastic Components in Mechanical Energy Storage Systems
Fundamental Principles
Clock springs (Spiral Torsion Springs) are mechanical components that store and release energy through elastic deformation of spiral-shaped metal strips, based on bending and torsion theories in material mechanics:
- Energy Storage Mechanism: External force winds the spring, converting mechanical energy into elastic potential energy
- Energy Release: Elastic restoring force drives mechanism movement, converting potential to kinetic energy
- Torque Characteristics: Torque T vs. rotation angle θ follows approximately linear relationship T = kθ + T0
- Mechanical Model: Maximum stress σmax = (6M)/(bt²), where M is bending moment, b is strip width, t is thickness
Key Characteristics
Structural Features
- Compact Design: Energy density up to 5-15J/kg
- Multi-Layer Structure: Stackable layers increase energy capacity
- End Types: Various connection methods (inner/outer hooks, straight arms)
Mechanical Properties
- Torque Range: 0.01-500N·m
- Rotation Capacity: Up to 20-50 turns maximum
- Efficiency: 70-90% energy conversion efficiency
Functional Features
- Self-Locking: Special structures maintain position
- Constant Force Output: Specific designs provide near-constant torque
- Overload Protection: Elastic deformation provides mechanical buffering
Classification System
By Structure
- Spiral Type: Flat spiral structure, most common
- Tapered Spiral: Axial stacking increases energy storage
- Non-Contact Type: Gaps between coils reduce friction
By Energy Storage
- Constant Force: Nearly constant torque
- Variable Force: Torque varies with rotation angle
- Segmented: Different stiffness in different sections
By Application
- Timekeeping: Clocks and precision timing devices
- Power Drive: Toys/automatic mechanisms
- Safety Devices: Overload protection mechanisms
Design Parameters
| Parameter | Symbol | Range | Design Impact |
|---|---|---|---|
| Strip Thickness | t | 0.1-2mm | Determines load capacity |
| Strip Width | b | 2-50mm | Affects torque output |
| Spiral Diameter | D | 10-500mm | Determines space requirements |
| Coil Count | n | 3-50 | Determines energy storage capacity |
| Preload Coils | n0 | 1-5 | Provides initial torque |
Torque Calculation: T = (Ebt³θ)/(12πRn), where E is elastic modulus, R is mean radius
Maximum Stress Verification: σmax = (6T)/(bt²) ≤ [σ]
Material Properties
| Material | Standard | E(GPa) | [σ](MPa) | Features |
|---|---|---|---|---|
| Carbon Steel | ASTM A228 | 210 | 1500-1800 | High strength |
| 304 Stainless Steel | ASTM A666 | 193 | 800-1000 | Corrosion resistant |
| Phosphor Bronze | ASTM B103 | 110 | 500-700 | Good conductivity |
| Nickel-Titanium Alloy | ASTM F2063 | 75 | 800-1000 | Shape memory |
Manufacturing Process
- Material Preparation:
- Strip straightening (straightness ≤0.03mm/m)
- Surface polishing (Ra≤0.4μm)
- Coil Forming:
- Special coiling machines (precision ±0.05mm)
- Heat treatment shaping (300-400°C)
- End Processing:
- Hook/straight arm forming
- Welding/riveting
- Heat Treatment:
- Stress relief annealing (250-350°C)
- Quenching+Tempering (for high carbon steel)
- Surface Treatment:
- Electroplating (Zinc/Nickel/Chromium, 5-20μm)
- Passivation (for stainless steel)
- Performance Testing:
- Torque-rotation angle curve testing
- Fatigue life testing (≥10⁵ cycles)
Application Scenarios
Timekeeping Instruments
- Mechanical clocks (30-240 hour energy storage)
- Timer mechanisms
Automatic Mechanisms
- Toy power sources (0.1-5N·m)
- Automatic winding devices
Safety Devices
- Overload protection mechanisms
- Emergency braking devices