One of the many advantages of a harmonic drive is the lack of backlash due to the unique design. However, the actual fact they are lightweight and intensely compact can be important.
High gear reduction ratios of up to 30 moments that achieved with planetary gears are possible 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 could use his patented product.
harmonic drive assembled The harmonic drive is a type of gear arrangement also known as a strain wave gear because of just how it works. It is some sort of reduction equipment mechanism comprising at the least three main components. These parts interact in a manner that allows for high precision decrease ratios that would otherwise require much more complicated 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 the countless advantages that it taken to the desk. Musser identified the potential of his invention at an early on stage and in 1960 began selling licenses to manufacturers so they could use his patented product. Nowadays, there are only a handful of manufacturers in america, Germany, and Japan who are holding the license to produce harmonic drives, doing this at their top-notch facilities and generating ultimate quality strain gears for your world.
harmonic drive exploded viewThe workings of a harmonic drive
The rotational motion originates from an input shaft which can be a servo engine axis for example. This is linked to an element called “wave generation” which includes an elliptical form and is definitely encircled by an elliptical ball bearing. As the shaft rotates, the edges switch position, so it looks like it really is generating a movement wave. This part is inserted in the flex spline that is crafted from a torsionally stiff yet flexible material. The material occupies this wavy motion by flexing according to the rotation of the input shaft and in addition produces an elliptical form. The outer advantage of the flex spline features equipment tooth that are suitable for transferring high loads without any problem. To transfer these loads, the flex spline is installed in the circular spline which is a round equipment featuring internal teeth. This outer band is rigid and its own internal size is marginally larger than the major axis of the ellipse formed by the flex spline. This implies that the circular spline will not believe the elliptical form of the various other two parts, but instead, it just meshes its inner tooth with those of the outer flex spline part, 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 decreased ratio and in the contrary path than that of the insight shaft. The decrease ration is given by: (amount of flex spline tooth – quantity of circular spline teeth) / amount of flex spline teeth. So for example, if the flex spline provides 100 teeth 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 contrary direction of spin). The difference in the amount of teeth could be changed to support different decrease ratios and therefore different specialized requires and requirements.
Achieving decrease ratios of 1/100 and up to even 1/300 by simply using such a compact light arrangement of gears can’t be matched simply by any other gear type.
The harmonic drive is the only gear arrangement that doesn’t feature any backlash or recoil effect, or at least they are negligible in practice. That is mainly because of the elliptical bearing fitted on the outer rim of the insight shaft allowing the free of charge 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 with no need to improve anything, plus they wthhold the same positional accuracy in both spin directions.
The efficiency of a typical harmonic drive measured on real shaft to shaft studies by the producer rises to 90%. There are very few mechanical engineering components that may claim this operational performance level.
Uses for a harmonic drive
In short a harmonic drive can be utilized “in any gear reduction program where small size, low weight, zero backlash, very high precision and high reliability are needed”. For example aerospace applications, robotics, electric vehicles, medical x-ray and stereotactic devices, milling and lathe devices, flexo-printing machines, semiconductor products, optical measuring devices, woodworking machines and camera mind pans and tilt axes. The most known examples of harmonic drive applications include the wheels of the Apollo Lunar Rover and the winches of the Skylab space station.