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Hanover Messe 2020: igus tribo-polymers make shaft gears cost-effective and light

Photo by igus GmbH

In order to realize movements, for example on the 5th robot axis, at low cost, the motion plastics specialist igus has developed new types of shaft gears based on its tribo-polymer technology. By using the lubricant-free high-performance plastics, they are not only particularly compact and light, but also particularly low-maintenance and durable. The latest generation complements igus’ gearbox series and is part of the constantly growing range of products for low-cost automation.

Tribo-polymers are used wherever technology is to be improved and costs reduced in moving applications. The advantages of tribo-polymers are particularly evident in transmissions: Thanks to the use of iglidur high-performance plastics, igus shaft transmissions do not require additional lubrication like metallic variants. Friction and wear are optimized by the dry-running tribo-polymers. At the same time, the use of plastics enables an extremely compact design and cost-effective production. Through active research and further development of the shaft gears, especially in the latest generation, the running smoothness, backlash and service life have been further improved through design optimizations and the selection of materials.

Shaft gear units made of lube-free tribo-polymers

The main components of the gearboxes comprise a shaft generator and flex ring with external teeth as well as a housing-fixed outer ring and a rotatable output element with internal teeth. The use of lubricant-free igus high-performance plastics provides the necessary flexibility with very high wear resistance. The wave generator has an elliptical shape, which is transferred to the surrounding flex ring. The toothing of the flex ring engages at two points in the internal toothing of the outer ring and output element. Since the outer ring has two teeth more than the other components, the flex ring is only moved forward by two teeth per revolution when the shaft generator rotates. The shaft gear can be used in the last axis of jointed-arm, portal and delta robots before various gripper systems. At this point it takes over the task of gripping and precisely positioning objects that are not rotationally symmetrical. The current development is based on the Nema 17 size for direct connection to a stepper motor and can be easily adapted to other motor types. The load capacity of the shaft gears was determined in tests in the test laboratory. For example, with a gear ratio of 28:1, the gear shows a service life of 1 million cycles at a load of 1.5 Nm and a speed of 6 rpm. The next step is to transfer the development steps to the Nema 23 size.

Inexpensive automation solutions can already be implemented today

Like the igus worm and planetary gears, the shaft gears are part of the low-cost automation range from igus. This enables cost-effective and durable automation solutions to be developed for medium-sized companies – for example, robots that serve coffee in the retail trade, perform pick-and-place tasks in the electronics industry or will in future be able to clear out the dishwasher at home. And all this at a particularly low price: For example, a five-axis robot kinematics system from the igus robolink DP series costs around 3,500 euros due to the predominant use of plastics, and the investment often pays for itself in just a few months. For a simple combination of further components such as grippers, control or pneumatics to form a robotic solution, igus launched the RBTX.com platform together with partners last year. The platform brings users and suppliers of low-cost robotic components together quickly and easily. Interested parties can thus put together a low-cost robotics solution that meets their requirements and budget.

For more information, please visit: https://www.igus.com/