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Strain Wave/Harmonic Gearboxes are specialized mechanical components designed to transmit power with high precision through the deformation of elastic components. Employing an ingenious mechanism that includes a Wave Generator, Flexspline, and Circular Spline, these gearboxes achieve high reduction ratios, minimal backlash, and compact design. Developed for applications requiring exact motion control and high torque capacity within limited spaces, their usage spans across robotics, aerospace, medical devices, and precision equipment manufacturing.
The core operation of Strain Wave/Harmonic Gearboxes hinges on the interaction between three primary components: the Wave Generator, Flexspline, and Circular Spline. Each plays a crucial role in converting input torque into precise output motion, setting these gearboxes apart in terms of efficiency and precision.
Wave Generator: This element is the driving force within the gearbox. It consists of an oval-shaped disc that fits inside the Flexspline with a ball-bearing assembly. Its rotation causes the Flexspline to adopt an elliptical shape, initiating the strain wave motion critical for the gearbox's operation.
Flexspline: Acting as the gearbox's output element, the Flexspline is a flexible, thin-walled cylinder with external teeth. Its diameter is slightly smaller than that of the Circular Spline, allowing it to deform and fit into the Wave Generator's elliptical shape. This deformation is key to the engagement process with the Circular Spline.
Circular Spline: This stationary component encases the other two, featuring internal teeth that mesh with those on the Flexspline. Its tooth count is slightly higher than that of the Flexspline, a difference that is fundamental to achieving the desired gear reduction ratio.
Upon operation, the Wave Generator's rotation deforms the Flexspline, causing its teeth to engage and disengage with those of the Circular Spline sequentially. This interaction results in the Flexspline's rotation at a significantly reduced speed relative to the Wave Generator, embodying the gearbox's high reduction ratio. The precise nature of this engagement ensures minimal backlash, contributing to the system's overall efficiency and accuracy.
The advantages and benefits of Strain Wave/Harmonic Gearboxes are directly attributable to their unique design and operational principles. These gearboxes provide solutions that are critical in applications where precision, reliability, and compact size are non-negotiable. The following points outline the key advantages, demonstrating why these components are integral to the success of high-precision mechanical systems:
These advantages make strain wave/harmonic gearboxes a preferred choice for engineers and designers facing challenges that require solving complex motion control and power transmission problems.
The unique advantages of Strain Wave/Harmonic Gearboxes, including high precision, compact size, and high torque capacity, make them indispensable in a wide array of applications. Their ability to deliver accurate and reliable performance in space-constrained environments has led to their adoption in several critical industries and technological fields. This section explores some of the key applications of strain wave/harmonic gearboxes, highlighting their versatility and importance.
Robotics: In robotics, strain wave gearboxes are favored for their precision and high torque density. They are used in robotic arms, manipulators, and humanoid robots to provide smooth, accurate motion control. Their compact design allows for more efficient use of space within the robot's structure, enabling more sophisticated and flexible designs.
Aerospace and Defense: The aerospace industry requires components that can operate reliably under extreme conditions while maintaining precise control. Strain wave gearboxes are used in satellite communication systems, spacecraft mechanisms, and defense equipment for their precision, reliability, and ability to withstand harsh environments.
Medical Devices: Precision is critical in medical devices, where strain wave gearboxes are employed in surgical robots, diagnostic equipment, and prosthetics. Their smooth operation and high positional accuracy allow for enhanced performance in applications where precision can directly impact patient outcomes.
Precision Machining Tools: CNC machines and other precision machining tools utilize strain wave gearboxes to achieve high accuracy and repeatability in cutting, engraving, and shaping processes. The gearboxes' zero-backlash and high reduction ratios enable the production of complex parts with tight tolerances.
Semiconductor Manufacturing Equipment: The semiconductor industry demands equipment capable of extremely precise movements for wafer processing and chip assembly. Strain wave gearboxes facilitate the fine positioning required in lithography, inspection, and packaging processes.
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Entertainment and Simulation: In the entertainment industry, strain wave gearboxes are used in virtual reality systems, simulators, and animatronics to produce realistic movements. Their precision and smooth operation enhance the user experience in simulations and interactive exhibits.
These applications illustrate the broad adaptability and critical role of strain wave/harmonic gearboxes across different sectors. By enabling precise control in compact spaces, these gearboxes facilitate advancements in technology and contribute to the development of cutting-edge solutions in various fields.
Sumitomo
Drive TechnologiesOur Elastic Cyclo (ECY) is an innovative addition to the realm of strain wave gearboxes, exemplifying the fusion of precision engineering with practical design. The Elastic Cyclo leverages Sumitomo's renowned Cyclo® technology, known for its durability and reliability, integrating it within the strain wave gearing mechanism to deliver unmatched accuracy and torque density.
This unique gearbox is designed to meet the demanding requirements of high-precision applications, offering advantages such as high reduction ratios, exceptional positional accuracy, and minimal backlash. The ECY series is precisely engineered to cater to the needs of robotics, automation, and other applications where efficiency and compactness are critical. Sumitomo's commitment to quality and innovation is evident in the Elastic Cyclo's design, which ensures a long service life and consistent performance, even in the most challenging operational environments.
For detailed information on the Harmonic/Strain Wave Gearboxes, visit our product information page here.
Sumitomo
Drive TechnologiesSumitomo Drive Technologies, a global leader in power transmission and control solutions, has been at the forefront of engineering excellence for over a century. With a commitment to innovation, quality, and reliability, Sumitomo offers a wide range of products and services designed to meet the rigorous demands of diverse industries. From the advanced Elastic Cyclo series to robust industrial gearboxes, Sumitomo Drive Technologies provides solutions that drive efficiency and productivity for our customers worldwide. Our global network of support and engineering expertise ensures that we deliver responsive, customer-focused solutions that optimize performance across various applications.
Ever since they were invented, Harmonic Drive® strain wave gears have remained of great interest in a variety of industries, thanks to the constant innovation, improvements and modifications that they are still undergoing. Today they represent the first choice for applications that require a high level of positioning and repeat precision. Whether enclosed in a housing, employed as an actuator with motor and encoder, or as components in customer-specified configurations with specific materials or design elements, the flexibility of strain wave gears makes them suitable for a wide range of applications. However, there is one aspect, in particular, that has remained constant for decades, and this is the principle by which the Harmonic Drive® strain wave gear functions.
The Harmonic Drive® strain wave gear is made up of three basic components. These are first of all the so-called wave generator, an elliptical steel disc that forms the heart of the gear unit, which has a centric hub and a special thin, elliptically deformable ball bearing. The wave generator is also connected to the motor shaft. Secondly, the wave generator consists of the flexspline &#; a deformable, cylindrical steel bushing with teeth arranged around its outer circumference &#; and the circular spline. The latter surrounds both the wave generator and the flexspline as a rigid, cylindrical outer ring, with teeth along its inner circumference. What is significant is the number of teeth &#; the outer toothing of the flexspline has fewer teeth than the inner toothing of the circular spline. The difference in number is frequently two. Typically, the wave generator is used as the input member and the flexspline as the output element of the mechanism.
The elliptical wave generator is the driven element and initiates the process of the Harmonic Drive® strain wave gear, with preliminary deformation of the flexspline. The latter is enmeshed with the internally toothed circular spline in the opposing areas of the large elliptical axis. The rotation of the wave generator causes the large elliptical axis to shift, along with the enmeshed area of the teeth. The key to the design and function of the Harmonic Drive® strain wave gear is that the flexspline has fewer teeth than the circular spline. With a difference of two teeth, a half-revolution of the wave generator produces a relative motion between the flexspline and the circular spline corresponding to one tooth. After a complete revolution, the difference is already two teeth.
The central features and advantages of the strain wave gear compared to other, more conventional types of gear unit, are primarily due to the combination of its simple construction and the unique principle of elastic deformation found in steel gear wheels. Harmonic Drive® gears display absolute play-free performance throughout their service life and maintain a high level of torsional rigidity over the whole torque range. With smaller dimensions and a lower weight compared with conventional gear types, they are suitable for use in lighter and more compact applications and systems. Owing to their high reduction ratios and the fact that they consist of three basic components and have a coaxial orientation, strain wave gears can be easily integrated into existing applications.
A central hollow shaft is sometimes used to create the aforementioned properties. It provides space for shafts, cables and other media or components, and lends itself to user-friendly construction. High single-stage reduction ratios, high efficiency levels, and very good values in terms of position and repeat precision are further advantages of the strain wave gear.
When Walton Musser first conceived the Harmonic Drive® principle in , he primarily envisaged that it would be used in space travel, which is why it was funded above all by NASA. Over the ensuing years, strain wave gears from Harmonic Drive AG have visited the moon and Mars; they have left our solar system and may one day in the future even find their way to hitherto undiscovered planets. To this day, strain wave gears are still in use in space. But their range of applications has expanded considerably, and they now represent an extremely important component of complex drive systems, alongside motors, controllers, measuring instruments and brakes.
Another application field is that of robotics, where strain wave gears primarily function as axle drives in a wide range of robot designs. They are also found in drive units in flight simulators, as well as in the orientation of parabolic antennas, in the automobile industry, and in machine tools.