One of the many benefits of a harmonic drive may be the lack of backlash because of the unique style. However, the actual fact that they are lightweight and intensely compact is also important.
High gear reduction ratios of up to 30 situations 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 item.
harmonic drive assembled The harmonic drive is a kind of gear arrangement also known as a strain wave gear because of just how it works. It is some sort of reduction gear mechanism consisting of a minimum of three main parts. These elements interact in a way that allows for very high precision reduction ratios that would otherwise require a lot more complicated and voluminous mechanisms.
As a product, 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 table. Musser recognized the potential of his invention at an early on stage and in 1960 began offering licenses to producers so they might use his patented item. Currently, there are just a small number of manufacturers in america, Germany, and Japan who are holding the license to create harmonic drives, doing this at their top-notch facilities and making ultimate quality stress gears for your world.
harmonic drive exploded viewThe workings of a harmonic drive
The rotational motion originates from an input shaft that can be a servo engine axis for example. This is linked to an element called “wave generation” which includes an elliptical shape and is usually encircled by an elliptical ball bearing. As the shaft rotates, the edges transformation position, so that it appears like it really is generating a motion wave. This part is inserted in the flex spline that is crafted from a torsionally stiff yet flexible materials. The material occupies this wavy motion by flexing based on the rotation of the insight shaft and in addition creates an elliptical shape. The outer advantage of this flex spline features gear tooth that are suitable for transferring high loads with no problem. To transfer these loads, the flex spline is fitted within the circular spline which is a round equipment featuring internal teeth. This outer band is usually rigid and its own internal diameter is marginally larger than the main axis of the ellipse produced by the flex spline. This implies that the circular spline does not assume the elliptical shape of the other two components, but instead, it merely meshes its inner tooth with those of the outer flex spline aspect, resulting in the rotation of the flex spline.
The rate of rotation is dependent on the rotation of the input shaft and the difference in the number 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 much reduced ratio and in the opposite path than that of the input shaft. The reduction ration is given by: (quantity of flex spline teeth – number of circular spline teeth) / amount of flex spline teeth. So for instance, if the flex spline provides 100 teeth and the circular spline provides 105, the reduction ratio is (100 – 105) / 100 = -0.05 which implies 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 accommodate different reduction ratios and thus different specialized demands and requirements.
Achieving decrease ratios of 1/100 and up to even 1/300 simply by using such a concise light set up of gears cannot be matched by any additional 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. That is mainly thanks to the elliptical bearing fitted on the external 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 forward and backward rotation without the need to improve anything, and they wthhold the same positional accuracy about both spin directions.
The efficiency of the harmonic drive measured on real shaft to shaft studies by the manufacturer goes up to 90%. There are very few mechanical engineering components that can claim such an operational effectiveness level.
Uses for a harmonic drive
In a nutshell a harmonic drive can be utilized “in any gear reduction app where small size, low weight, zero backlash, very high precision and high reliability are needed”. Examples include aerospace applications, robotics, electric vehicles, medical x-ray and stereotactic devices, milling and lathe machines, flexo-printing machines, semiconductor devices, optical measuring devices, woodworking machines and camera mind pans and tilt axes. The most notable examples of harmonic drive applications are the wheels of the Apollo Lunar Rover and the winches of the Skylab space station.