Industries & Applications
The Harmonic Drive® Gear belongs to the group of the strain wave gears.
The Flexspline is slightly smaller in diameter than the Circular Spline resulting in it having two fewer teeth on its outer circumference. It is held in an elliptical shape by the Wave Generator and its teeth engage with the teeth of the Circular Spline across the major axis of the ellipse.
As soon as the Wave Generator starts to rotate, the zone of tooth engagement travels with the major elliptical axis. When the Wave Generator has turned by 180 degrees, the Flexspline has regressed by one tooth relative to the Circular Spline.
Each turn of the Wave Generator moves the Flexspline two teeth in opposite direction relative to the Circular Spline.
B- and C-Axes
These axes use both standard and customised Harmonic Drive® Servo Actuators and Gears, e.g. with a customised output bearing and positional feedback from the output side.
- Output bearing with integrated angle measuring system
- Tooth belt input
- Output absolute encoder
- Hollow shaft
Linear spindle drives require low ratio gears. Customers apply Harmonic Planetary Gear Series HPG and HPN for instance.
In these indexing axes Harmonic Drive® Servo Actuators and Strain Wave Gears as well as Harmonic Drive® Planetary Gears are applied. Under large loads, clamped spur gears may be installed downstream. During machining processes, the actuator is locked on the output side (clamping, indexing).
- Hollow shaft
- Large output bearing
- Backlash up to < 1 arcmin
- High dynamics due to small ratio
Pre-loaded spur gears
When combined with downstream clamped spur gears, milling head axes are possible with an exceptionally high torque capacity and torsional rigidity in a very compact size. Illustration 12.2 presents a detail of the A-axis in a portal milling machine. The depicted gearbox with integrated HFUC Component Set forms part of an arrangement for two-stage reduction. This arrangement features a spur gear that is clamped free of backlash with a split pinion and installed downstream of the Harmonic Drive® Gear. This means that the torsional rigidity is influenced primarily by the spur gear. As a result, a Harmonic Drive® Component Set with an outer diameter of only 135 mm and an installed length of 53 mm can be used as the input stage on the A and C axis of milling heads with spindle power outputs up to 55 kW (S1). Further details on the subject of multi stage gears can be found in the section “Gear combinations”.