How does a Harmonic Drive work? Why are they utilized?

Among the many advantages of a harmonic drive is the lack of backlash due to the unique style. However, the actual fact they are lightweight and extremely compact is also important.
High gear reduction ratios of up to 30 occasions that achieved with planetary gears are feasible in the same space.
C W Musser designed strain wave gearing back 1957 and by 1960 he was already selling licenses to ensure that industry giants might use his patented item.
harmonic drive assembled The harmonic drive is a type of gear arrangement often referred to as a strain wave gear because of the way it works. It really is some sort of reduction equipment mechanism consisting of a minimum of three main components. These parts interact in a way that allows for very high precision reduction ratios that would otherwise require much more complex and voluminous mechanisms.

As something, the harmonic drive was invented by the American engineer Clarence Walton Musser in 1957, and it quickly conquered the industry with a variety of advantages that it brought to the desk. Musser discovered the potential of his invention at an early stage and in 1960 started selling licenses to producers so they could use his patented item. Nowadays, there are only a handful of manufacturers in america, Germany, and Japan who are holding the license to create harmonic drives, doing so at their top-notch services and creating ultimate quality stress gears for your world.

harmonic drive exploded viewThe workings of a harmonic drive
The rotational motion comes from an input shaft which can be a servo engine axis for instance. This is connected to an element called “wave era” which includes an elliptical shape and can be encircled by an elliptical ball bearing. As the shaft rotates, the edges transformation position, so it appears like it is generating a motion wave. This part is inserted inside a flex spline that is made out of a torsionally stiff yet flexible material. The material occupies this wavy motion by flexing according to the rotation of the insight shaft and also creates an elliptical shape. The outer advantage of this flex spline features equipment tooth that are suitable for transferring high loads without any issue. To transfer these loads, the flex spline is fitted inside the circular spline which really is a round equipment featuring internal teeth. This outer ring is rigid and its internal size is marginally bigger than the major axis of the ellipse shaped by the flex spline. This means that the circular spline will not assume the elliptical shape of the additional two parts, but instead, it just meshes its internal tooth with those of the external flex spline aspect, leading to the rotation of the flex spline.

The rate of rotation would depend on the rotation of the input shaft and the difference in the amount of teeth between the flex spline and the circular spline. The flex spline offers fewer teeth than the circular spline, so that it can rotate at a very much reduced ratio and in the contrary direction than that of the insight shaft. The reduction ration is distributed by: (amount of flex spline teeth – quantity of circular spline teeth) / amount of flex spline tooth. So for instance, if the flex spline offers 100 tooth and the circular spline offers 105, the reduction ratio is (100 – 105) / 100 = -0.05 which means that the flex spline ration is -5/100 (minus indicates the opposite direction of spin). The difference in the amount of teeth can be changed to support different decrease ratios and therefore different specialized demands and requirements.

Achieving reduction ratios of 1/100 or more to even 1/300 by simply using such a concise light set up of gears can’t be matched simply by any various other gear type.
The harmonic drive may be the only gear arrangement that doesn’t feature any backlash or recoil effect, or at least they are negligible used. This is mainly because of the elliptical bearing installed on the outer rim of the input shaft enabling the free rotation of the flex spline.
The positional accuracy of harmonic drives even at an extreme number of repetitions is extraordinary.
Harmonic drives can accommodate both ahead and backward rotation without the need to change anything, plus they retain the same positional accuracy about both spin directions.
The efficiency of the harmonic drive measured on real shaft to shaft studies by the producer rises to 90%. There are extremely few mechanical engineering components that can claim this operational efficiency level.
Uses for a harmonic drive
In short a harmonic drive can be used “in any gear reduction program where little size, low weight, zero backlash, very high precision and high reliability are required”. Examples include aerospace applications, robotics, electric automobiles, medical x-ray and stereotactic devices, milling and lathe machines, flexo-printing machines, semiconductor devices, optical measuring machines, woodworking devices and camera head pans and tilt axes. The most notable types of harmonic drive applications are the tires of the Apollo Lunar Rover and the winches of the Skylab space station.


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