In order to generate accurate movement along the 5th robot
axis, the motion plastics specialist igus has developed new
types of strain wave gears based on its tribo-polymer
technology. Due to the use of lubrication-free
high-performance polymers, they are not only extremely
compact and light but also require very little maintenance
and have an especially long service life. The latest
generation supplements the gearbox series from igus and is
part of the continually growing range of products for Low
Cost Automation.
Tribo-polymers are used wherever the goal is an improvement
of technical performance and a simultaneous reduction of
costs. The advantages of tribo-polymers are especially
apparent in the case of gearboxes: due to the use of iglidur
high-performance polymers, strain wave gears from igus
require no additional lubrication, in contrast to metal
types of gear. Friction and wear are improved if
lubrication-free tribo-polymers are used. At the same time,
the use of plastics enables an extremely compact design and
cost-effective manufacture. As a result of active research
and further development of the strain wave gear, operating
smoothness, backlash and service life have been optimised
further by means of improvements in the technical design and
in the selection of materials. This especially applies to
the latest generation.
Strain wave gear made of lubrication-free tribo-polymers
The main components of the gearbox include a wave generator
and a flexible ring with outer drive teeth, as well as an
outer ring, fixed in place in the housing and a rotary power
take-off element with inner drive teeth. The necessary
flexibility and high degree of wear resistance are achieved
through the use of lubrication-free high-performance igus
polymers. The wave generator has an elliptical shape,
therefore the surrounding flexible ring also assumes this
shape. The drive teeth of the flexible ring engage at two
places in the inner drive teeth of the outer ring and power
take-off element. As the outer ring has two teeth more than
the other components, the flexible ring is only moved two
teeth further per rotation when the wave generator is
rotated. Along the last axis of an articulated arm, linear
robot or delta robot, the strain wave gear can be used
before different gripper systems. Here, it performs the task
of gripping objects that are not rotationally symmetrical
and positioning them exactly. The current version is based
on the installation size Nema 17 for direct connection to a
stepper motor and can easily be adapted to other types of
motor. The load bearing capacity of the strain wave gear has
been determined in the test laboratory. With a transmission
ratio of 28:1, the gearbox has a service life of 1 million
cycles under a load of 1.5Nm and at a speed of 6rpm. As a
next step, there are plans to develop a size Nema 23 gearbox.
Cost-effective automation solutions now possible
Like igus worm gears and planetary gears, strain wave gears
are also part of the igus Low Cost Automation product range.
These products can be used to develop cost-effective and
long-lasting automation solutions for small and medium-sized
enterprises – such as robots that can dispense coffee in the
retail trade, perform pick-and-place tasks in the
electronics industry or, in future, empty a dishwasher in
the home. And all this is possible at a very favourable
price: for example, a five-axis robot kinematics system from
the igus robolink DP series costs around 3,500 euros, due
mainly to the use of plastics, whereby the investment often
pays for itself within just a few months. Last year, igus
worked with partners to start the platform
RBTX.com 
, which
makes it easy to put together additional components such as
gripper, control system or pneumatic components in order to
create a full robotics solution. The platform brings users
and suppliers of low-cost robotics components together
quickly and easily. Interested parties can put together a
low-cost robotics solution that matches their requirements
and their budget exactly.
!!!!!!
igus GmbH is a global leading manufacturer of energy
chain systems and polymer plain bearings. The Cologne-based
family business has offices in 35 countries and employs
4,150 people around the world. In 2018, igus generated a
turnover of 748 million euros from motion plastics, plastic
components for moving applications. igus operates the
largest test laboratories and factories in its sector to
offer customers quick turnaround times on innovative
products and solutions tailored to their needs.
