One of the many benefits of a harmonic drive is the insufficient backlash because of the unique design. However, the actual fact that they are light-weight and intensely compact can be important.
High gear reduction ratios as high as 30 situations that achieved with planetary gears are feasible in the same space.
C W Musser designed strain wave gearing back in 1957 and by 1960 he had been selling licenses so that industry giants might use his patented product.
harmonic drive assembled The harmonic drive is a kind of gear arrangement also known as a strain wave gear due to just how it works. It is some sort of reduction gear mechanism consisting of at the least three main elements. These components interact in a manner that allows for high precision reduction ratios that would otherwise require a lot 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 table. Musser determined the potential of his invention at an early on stage and in 1960 began offering licenses to producers so they might use his patented product. Currently, there are just a small number of manufacturers in the USA, 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 movement originates from an input shaft that can be a servo engine axis for instance. This is linked to an component called “wave generation” which includes an elliptical form and is usually encircled by an elliptical ball bearing. As the shaft rotates, the edges modification position, so that it looks like it really is generating a motion wave. This part is inserted inside a flex spline that is crafted from a torsionally stiff however flexible materials. The material occupies this wavy movement by flexing based on the rotation of the input shaft and also creates an elliptical shape. The outer advantage of the flex spline features equipment teeth that are suitable for transferring high loads without any problem. To transfer these loads, the flex spline is installed inside the circular spline which is a round equipment featuring internal tooth. This outer ring is normally rigid and its own internal diameter is marginally bigger than the main axis of the ellipse formed by the flex spline. This implies that the circular spline does not believe the elliptical form of the additional two elements, but instead, it simply meshes its inner teeth with those of the external flex spline side, 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 number of teeth between your flex spline and the circular spline. The flex spline has fewer teeth than the circular spline, so that it can rotate at a much decreased ratio and in the opposite direction than that of the insight shaft. The decrease ration is given by: (quantity of flex spline tooth – amount of circular spline tooth) / number of flex spline teeth. So for example, if the flex spline offers 100 tooth and the circular spline provides 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 number of teeth can be changed to accommodate different reduction ratios and therefore different specialized requires and requirements.
Achieving decrease ratios of 1/100 and up to even 1/300 simply by using such a concise light arrangement of gears cannot 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 used. That is mainly thanks to the elliptical bearing installed on the outer rim of the input shaft permitting 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 forwards and backward rotation without necessity to improve anything, and they wthhold the same positional accuracy on both spin directions.
The efficiency of the harmonic drive measured on real shaft to shaft tests by the manufacturer goes up to 90%. There are extremely few mechanical engineering elements that may claim this operational performance level.
Uses for a harmonic drive
In a nutshell a harmonic drive can be utilized “in virtually any gear reduction software where little size, low weight, zero backlash, high precision and high reliability are needed”. For example aerospace applications, robotics, electric vehicles, medical x-ray and stereotactic machines, milling and lathe devices, flexo-printing devices, semiconductor tools, optical measuring devices, woodworking machines and camera head pans and tilt axes. The most known types of harmonic drive applications are the tires of the Apollo Lunar Rover and the winches of the Skylab space station.