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Among the many benefits of a harmonic drive may be the lack of backlash because of the unique design. However, the fact they are light-weight and extremely compact can be important.
High gear reduction ratios as high as 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 had been selling licenses to ensure that industry giants might use his patented product.
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 is a kind of reduction equipment mechanism consisting of at the least three main elements. These parts interact in a way that allows for high precision reduction ratios that would otherwise require much more complex 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 a variety of advantages that it taken to the desk. Musser recognized the potential of his invention at an early stage and in 1960 started offering licenses to producers so they could use his patented product. Nowadays, there are only a small number of manufacturers in america, Germany, and Japan who are keeping the license to produce harmonic drives, doing so at their top-notch facilities and producing 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 electric motor axis for instance. This is linked to an element called “wave generation” which includes an elliptical shape and is normally encircled by an elliptical ball bearing. As the shaft rotates, the edges modification position, so it looks like it really 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 movement by flexing according to the rotation of the insight shaft and in addition creates an elliptical form. The outer edge of the flex spline features equipment teeth 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 gear featuring internal tooth. This outer band can be rigid and its own internal size is marginally larger than the main axis of the ellipse shaped by the flex spline. This implies that the circular spline does not believe the elliptical shape of the various other two components, but rather, it merely meshes its internal tooth with those of the outer flex spline part, 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 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 input shaft. The reduction ration is distributed by: (number of flex spline tooth – quantity of circular spline teeth) / number of flex spline tooth. So for example, if the flex spline has 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 opposite direction of spin). The difference in the amount of teeth can be changed to support different decrease ratios and thus different specialized needs and requirements.
Achieving reduction ratios of 1/100 and up to even 1/300 by simply using such a concise light arrangement 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 in practice. This is mainly because of the elliptical bearing installed 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 forwards and backward rotation without the need to improve anything, and they retain the same positional accuracy in both spin directions.
The efficiency of the harmonic drive measured on real shaft to shaft tests 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 a nutshell a harmonic drive can be utilized “in any gear reduction software where small 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 devices, flexo-printing devices, semiconductor equipment, optical measuring machines, woodworking machines and camera mind 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.