Harmonic Drive

Harmonic Drive Gearing

The Leader in Precision Motion

MEETING AGENDA
Company Overview Harmonic Drive Gearing Principles Benefits of Harmonic Drive Gearing Design Innovation & Reliability Types of Products Application Examples Conclusion
The Leader in Precision Motion

HD Systems Worldwide
•

Sales: $150 Million Worldwide • Modern facility in Nagano, Japan:
– – – –

150,000Square Feet 300+ Employees ISO 9001 Certified Numerous quality awards

The Leader in Precision Motion

HD Systems Worldwide
Production Facility in Germany

HD Systems, New York


Application & design engineering, assembly, CNC production capabilities, & repair services  ISO 9001 Certified

The Leader in Precision Motion

HD Systems Worldwide
Production facility in Peabody, MA

TheLeader in Precision Motion

Harmonic Drive Gearing Principles

The Leader in Precision Motion

Harmonic Drive Gearing Inventor
• Walt Musser – Prolific Inventor – HDG Patent 1957 – www.waltmusser.org

The Leader in Precision Motion

Harmonic Drive Gearing Principles

The Leader in Precision Motion

Harmonic Drive Gearing Principles
Three Gearing Components Form the Basis of theProduct Line

Assembles and Operates Concentrically
Circular Spline
Flexspline Wave Generator
The Leader in Precision Motion

Harmonic Drive Gearing Principles
Wave Generator Elliptical Steel Plug

Special Ball Bearing is Pressed Around Plug
- Forms Elliptical Bearing
Wave Generator

The Leader in Precision Motion

Harmonic Drive Gearing Principles
Flexspline Steel Cup

-Thin Walled: Radially Compliant
- Large Diameter: Torsionally Stiff Teeth on Outer Rim of Cup - Rim (teeth) Conforms to Elliptical Shape of Bearing Flexspline

The Leader in Precision Motion

Harmonic Drive Gearing Principles
Circular Spline Rigid Circular Ring with Teeth on ID

- Has 2 Teeth More Than Flexspline
Teeth of Circular Spline and Flexspline Engage in two regions - EllipseInscribed in a Circle
Circular Spline

The Leader in Precision Motion

Harmonic Drive Gearing Principles

The Leader in Precision Motion

Harmonic Drive Gearing Principles
Rated Torque, Rated Speed: Define Rated Life of Wave Generator Bearing
Rated Torque @Rated Speed = Rated Life (50,000 hr.)

Average Torque, Average Speed Affect Lubricant Life Repeated Peak Torque
Maximum Torque OverTypical Operating Cycle -Unlimited # of Cycles

Momentary Peak Torque
For Emergency Stop
The Leader in Precision Motion

Harmonic Drive Gearing Principles
Flexspline Achieves Infinite Life

Stress
Endurance Limit of Steel

Safety Factor

Flexspline Stress @Repeated Peak Torque

# Cycles

10 6

10 7

10 8

10 9
The Leader in Precision Motion

Robust Design
BucklingTorque

Torque Level/ Rated Torque

Ratcheting Torque Wave Generator Bearing Life L10
Finite Fatigue Life

S-N Curve for Steel
Momentary Torque

Infinite Fatigue Life

Peak Torque Rated Torque ( Reference = 1 )

# Wave Generator Revolutions

The Leader in Precision Motion

Benefits

The Leader in Precision Motion

Benefits
High Positional Accuracy (30 arc-sec)

The Leader inPrecision Motion

Benefits
30 arc-sec (0.5 arc-min) Positional Accuracy

27.72 arc-sec

1 Wave Generator Revolution = 2 Cycles

The Leader in Precision Motion

Benefits
High Gear Ratio
- Single Stage, In-line Configuration
- 30:1 to 160:1 in a Single Stage - Compact

- Geometry is independent of Gear Ratio
- Example for 100:1

- # Flexspline teeth: 200
- # Circular Splineteeth: 202 Ratio = 200 / (200 – 202) = -100
The Leader in Precision Motion

Benefits
Smooth Motion - High Positional Accuracy Provides Smooth Motion
Velocity Ripple ~ d/dt (Position Error) Vibration ~ d2/dt2 (Position Error)

- Torque is distributed on many teeth
- Up to 30% of teeth are always in contact - Load Transfer from Tooth to Tooth is smooth

The Leader in Precision Motion...