Understanding the 7th Axis for Robots
Robotic technology has come a long way, and while four,
five, or six-axis robots have their merits, they often face limitations. These
robots are typically bolted to the floor, confined to a fixed position within a
predefined workspace. Enter the 7th axis - a game-changer in the world of
robotics.
What Exactly Is a 7th Axis?
A 7th axis,
also known as a linear transfer system, serves as a robotic mobility enhancer,
allowing robots to move along an additional linear axis. Some folks refer to
these systems as "robot transfer units" or "linear transfer
units." Despite their high-tech sound, the concept is surprisingly simple.
Pictured: igus® drylin® 7th axis
ZLW-linear belt actuator with a robolink®
robotic arm
In this article, we'll explore the advantages of the 7th
axis, its practical applications, and a self-lubricating linear actuator that
simplifies its implementation and maintenance.
Benefits of Incorporating a 7th Axis
Adding a 7th axis to a robot yields several noteworthy
benefits. Firstly, it grants the robot the ability to be easily relocated to
another workstation, reducing the need for additional robots. Moreover, it
provides the flexibility to position the robot outside of the work area,
meeting stringent safety requirements.
Another significant advantage is that it allows smaller
robots to perform tasks typically reserved for larger, more extended-arm
robots. This scalability not only saves costs for end-users but also
accelerates return on investment.
Where Can You Apply a 7th Axis?
The versatility of 7th axis systems shines in various
applications, including painting, coating, welding, palletizing,
pick-and-place, conveying, and warehousing/logistics. These robots excel at
tasks that are repetitive and potentially hazardous for humans.
Depending on requirements, 7th axis systems can be mounted
horizontally or vertically. Elevating them enhances safety and maximizes open
floor space in warehouses and factories. In fact, smaller 7th axis systems can
even be mounted on automated guided vehicles (AGVs), further boosting
flexibility and workflow efficiency.
Linear Actuators: The Driving Force Behind the 7th Axis
Several types of linear systems can actuate a 7th axis. One
common choice for moving smaller robots, such as Universal Robots, is linear
actuators driven by timing belts and equipped with linear bearings. For
instance, products like igus'®
drylin® 7th axis feature self-lubricating polymer sliding
bearings, making them ideal for harsh environments and eliminating the need for
messy oil or grease lubrication. This feature enables their use in clean
environments as well.
Plain bearing 7th axis systems offer another advantage: they
are notably lighter than their linear ball bearing counterparts. However, in
cases involving larger robots with substantial cantilevered loads, linear ball
bearings are recommended, albeit at a higher cost. It's crucial to protect
these bearings from potential debris like dirt, dust, or metal shavings.
NEMA-framed stepper motors are commonly employed to power
7th axis systems and can be seamlessly integrated into the robot's control
systems.
Simplified Assembly with igus®
While all this might seem complex, some companies, such as igus®, have streamlined the hardware and control elements for effortless assembly. Their mounting plates come pre-drilled for many UR and EPSON robots, and their 7th axis includes a user-friendly UR cap and USB stick, enabling programming within just 1-2 minutes. Check out the video below to witness the simplicity of assembling the igus® 7th axis into UR controls.
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