Plug-and-Play Extra Axis Gets Robots Moving

Robotic production lines are becoming extremely common. And although various robots can be easy to program and use, one facet can still be a sticking point: How do you move the entire robot, including its base?

Most robots can mount in virtually any position or from any location, including overhead, in-line/platform, or side mount. For many of the larger six-axis robots, platform mounting is the most convenient and cost effective. However, the question then becomes, “How can these robots be moved for even better efficiency?”

Machine manufacturer Creative Automation Co., Ypsilanti, Mich., builds customized robots for machine-tool loading, often for the automotive industry. This means combining hard-tooled automation, robots, gantries, conveyors, controls, and specialized components into automated work cells.

Older systems used overhead robots, but Creative Automation identified a growing need for floor-mounted robots in custom automation projects. Floor robots need the flexibility to move beyond their normal area of motion, such as away from or along assembly lines.

In one case, the company designed a pallet unloader for an automotive assembly line. It used two six-axis robots with customized end-effector tooling and an embedded cell controller for accuracy. The first robot loads parts in one machine while the second robot moves parts between machines.

Creative Automation needed a way to easily and quickly move the robots away from the line for maintenance or troubleshooting.

Creative Automation engineers had visited an IPR Automation, Ann Arbor, Mich., plant in Germany where a seventh-axis motion subsystem specifically moves robots in relation to assembly lines. IPR developed the first 7th Axis Robot Transporter in 2002 in response to a void in the rapidly developing robot market. At the time, robots moved using welded steel structures. These structures were heavy, the rails or tracks had no safety covers, they were not adjustable, and IPR felt they did not meet all the technical requirements of the manufacturing market.

In contrast, the main beams of IPR’s 7th Axis are lightweight, custom aluminum extrusions. Each beam’s crosssection provides high rigidity in all directions. Adjustable-height legs support the beams. The legs fit in T-grooves on a beam’s underside and can be moved anywhere along the beam’s length. This means the legs compensate for uneven ground and common plant obstacles such as wiring and tubing fixtures. Operators bolt the axis to the ground using adjustable floor-mounting elements.

The robot mounts to a plate which rides on hardened, grounded guide rails with the help of high payload bearings. Operators adjust the bearings to an application’s accuracy and payload requirements.

Hardened and ground helical gear racks drive the assembly. A cable track transmits power and control signals while a Perma central-lubricator keeps the gear rack moving smoothly.

A “walk on” cover protects the drivetrain, rack and pinion, and supports from contaminants. The removable cover also gives maintenance personnel easier access to equipment around the robot.

According to Creative Automation engineers, adding IPR’s 7th Axis to the pallet unloader’s conveyor was both cost effective and convenient. Its transport railing extended the range of a robot up to 80 m in 6-m increments. Its plug-and-play design adapts easily to custom configurations. The 7th Axis supports the controls of any robot in use today, so it needs no specialized control software.

The first work cell where Creative Automation used IPR’s 7th Axis has been operating trouble-free for two years.