Product category:
Gears, brakes, couplings and engines
News Release from: Harmonic Drive UK | Subject: Micro Harmonic Drive
Edited by the Engineeringtalk Editorial
Team on 26 February 2007
Precision gear sets claimed as world's
smallest
Harmonic Drive's new gear components typically measure less than 8.0mm in diameter, with an axial length of under 1.0mm and a tooth module of just 34 microns.
Harmonic Drive has introduced the world's smallest backlash-free precision gear sets Called the Micro Harmonic Drive, the new gear components typically measure less than 8.0mm in diameter, with an axial length of under 1.0mm and a tooth module of just 34 microns, yet when supplied as part of a miniaturised gearbox or actuator can provide high reduction ratios, plus exceptional acceleration, repeatability and torque with low moments of inertia
This article was originally published on Engineeringtalk on 1 Aug 2005 at 8.00am (UK)
Related stories
Gear system handles twice the bearing load
A novel integrated gear and preloaded output bearing unit provides higher bearing load capacity with significantly improved concentricity and runout tolerances than competing devices.
Small claims for servo actuator
A device believed to be the world's smallest servo actuator is capable of delivering 1.8Nm of torque from an integrated AC motor, gearbox and encoder that measures just 50mm3 in size and weighs 0.4kg.
The latest micro gears sets are based on proven Harmonic Drive technology, with a conventional assembly of a wave generator, Flexspline and circular spline.
In the Micro Harmonic Drive gear sets, however, the wave generator comprises a sun gear, which is normally connected to a motor shaft, with two elastically deformable planetary gears being used to transmit motion from the motor shaft to the Flexspline and thus the circular spline.
Additionally, it is also possible to incorporate a dynamic spline as an output element when the gear set is used as a speed reducer.
Further reading
Stainless steel gears feature in latest Airbus
The latest Harmonic Drive technology is being used in a specially designed trolley lift system, now being fitted to the latest Airbus A340-600, the world's longest passenger aircraft.
Hollow-shaft servo actuators boast top torque
A new range of compact hollow-shaft servo actuators are designed to offer exceptionally high levels of transmission accuracy and acceleration torque.
Although conventional manufacturing techniques enable gear teeth modules down to 60 microns to be produced, depending on the geometry, the profile of each gear tooth is invariably compromised, affecting factors such as stiffness and torque capacity.
To overcome these problems, Harmonic Drive uses a specially modified LIGA process, called Direct-LIG, which combines X-ray lithography and electro-forming to create tough nickel-iron or stainless steel components with dimensional tolerances that are typically better than one micron.
The manufacturing process, combined with the unique construction and characteristics of the Micro Harmonic Drive components, delivers a number of important benefits to design and production engineers.
In particular, it is possible to create large reduction ratios in a small envelope; for a given size of gear, these ratios can be from 160 up to 1000 in a single stage.
As the planetary gear wheels are hollow and elastically deformable, it is possible to eliminate backlash completely by pre-loading the gears in the planetary gear stage.
In addition, when mounted in a Micro Gearbox and used with a miniature motor, the high torque capacity and low moment of inertia enable extremely fast acceleration to be achieved at the input shaft.
This corresponds to an acceleration of the motor shaft from 0 to 100,000 revs/min in just 25 milliseconds, and in the correct configuration also enables extremely fast angular movements; for example, rotation of 180 degrees in less than 80 milliseconds.
The latest Micro Harmonic Drive gear sets can be supplied with hollow output shafts and as gearboxes and actuators, with miniature motors, making them ideal for use in applications ranging from electronics and semiconductor manufacturing, including high-vacuum, to medical and surgical equipment, aerospace systems and Micro Scara robots.
• Harmonic Drive UK: contact details and other news
• Email this article to a colleague
• Register for the free Engineeringtalk email newsletter
• Engineeringtalk Home Page
Search the Pro-Talk network of sites
