Harmonic drive working principle


Harmonic Gearbox also called as Harmonic drive Gearbox or Strain Wave Gearbox was initially introduced only as a speed changers to reduce the gear ratio by increasing the torque. But now in the present manufacturing reforms it is also used for different purposes other that its speed changer features. They can be used in a variety of applications from low cost machines like vending machines to high value systems like defence and aerospace. Harmonic Gear reducer has now become the only choice for applications requiring positional accuracy and repeatability. This Gearbox has simple three-element construction combined with harmonic drive principle making it suitable for high reduction ratios capabilities and light weight. This structure of the Harmonic Gearbox makes this gearbox unique and also helps in maintaining the minimum Backlash. Also, the performance of Harmonic gearbox also remains constant over a longer period of time because of its structure and teeth alignment. With all these features Harmonic gearbox offers a price advantage than any other transmission system, its simple and elegant design allows manufacturing cost to be reduced and results into performance advantage.

Basic Elements or Components of Harmonic gearbox :-

There are 3 basic elements in the Harmonic Drive Gearbox: a circular spline, a flexspline and a wave generator. These 3 components interact in such a way that helps in achieving high reduction ratios.

Wave Generator –

Wave Generator is an assembly of bearing and a circular disk known as a wave generator plug. The outer surface of this plug has an elliptical shape which is manufactured with the most care. The Ball Bearing which is specifically designed is mounted and pressed around this plug which results in bearing to comply to the shape of elliptical as of wave generator plug. The Wave generator is basically the input of Harmonic Gearbox assembly.

Flexspline –

The flex spline is the thin-walled steel cup with teeth machined on the outer surface at the edge of the cup. This cup edge can deflect or be flexible and still remain torsionally stiff enough to transmit motion. The wave generator is inserted inside the flex spline and takes the shape of an elliptical wave generator disk ring. The flexspline usually works towards the output part of the mechanism.

Circular spline –

Circular Spline is the internal gear machined ring and is usually fixed or Rigid ( does not rotate ). The Circular spline has an internal tooth that meshes with the external teeth of flexspline. The flex spline is usually less in diameter than internal gearing and has less teeth than circular spline ( Internal Gear ). The wave generator acts as a link within the two rollers that rotates within the flex spline causing it to mesh with the circular spline progressively at diametrically opposite points. If wave generator rotates clockwise the flexspline will rotate and roll inside the circular spline at a much slower rate in the counter clockwise direction.

The wave generator is rotated by motor which creates a wavelike motion to the flexspline. This results into meshing on external teeth of the flexspline with the internal teeth of circular spline. As the flexspline has two fewer teeth than the circular spline, the tooth disengagement takes place and each revolution of the wave generator causes two tooth displacement of the flexspline in relation to the circular spline. With the help of this mechanism, the Harmonic Reducer acts as a speed reducer. The difference in the teeth of the circular spline and on flex spline results into the ratio of the input speed to the output speed.

SMD Harmonic Gearbox :-

Harmonic gearbox is the Most precise gearbox available with the SMD Gearbox series. The Gearbox has a Backlash of upto 12 arc-sec and short axial length which makes our Harmonic series compact and shortest reduction Gearbox for your applications. It is widely used in Robotics and automation Industry where high precision and high accuracy is needed in a limited space.

  • Nominal Torque range from 5.4 Nm to 402 Nm.
  • Ratios available from 1:50 to 1:160 .
  • Sizes available from 14 to 45.
  • High Load carrying capacity.
  • High transmission efficiency and long service life.
  • High Running Smoothness and Torsional Rigidity.

Visit Our website www.smdgearbox.com for more Blogs and Product Information.

Reference Link - https://www.britannica.com/technology/sawing-machine

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