Creating a custom-built safety system

BROCK Dominish, mechatronic engineer with Lincoln Electric’s automation division, recently had to design and build a robotic welding cell capable of assembling and welding large cable trays.

BROCK Dominish, mechatronic engineer with Lincoln Electric’s automation division, recently had to design and build a robotic welding cell capable of assembling and welding large cable trays.

The cell had to accommodate two custom designed working tables with two robots working on either table depending on the work in progress.

The robots are located in the centre, between the working tables. The project called for very fast robot movements with frequent operator’s access to the working area to load and unload the tables.

Operators had to be allowed near a working table while robots would be working on the other table. A safety challenge, indeed.

Although safety is stressed as the most important part of the manufacturing process, situations arise where safety procedures are bypassed. Injuries often occur when operators, with the best intentions, think they’ll just quickly fix a hiccup on the line without needing to shut down the machinery.

The controller

The solution involved sensors and actuators, including light curtains and emergency switches, but it was only one side of the coin. On the flip side, the solution had to work all together; this is the role of the controller. Brock chose a Schneider Electric (Telemecanique) safety controller, the XPS MC. The controller offered a reduction in panel size and flexibility.

“The controller could handle all the requirements of our application and, using the software, changes could be done instantly compared to hours spent redesigning and rewiring a hard wired safety relay solution,” said Brock.

The XPS MCWIN, Windows environment software, enables the user to create safety applications with simple “Drag and Drop” operation.

XPS MCWIN includes a library of certified safety functions, with multiple combination possibilities and various starting conditions, which are easily assignable to the controller’s inputs and outputs.

The wiring of safety components has been made easy, with controllers like the XPS MC. The wiring simply consists of connecting the components to the corresponding input/output terminals; the software will do the rest.

Once validated, the configuration can be saved to Hard Disk, CDROM or any other standard PC storage media to be used again in the future or simply modified according to layout changes.

Four XUS LT light curtains were installed at the entrance of the working area. The curtains feature unique in-built alignment LEDS. The transmitter-receiver alignment is simplified by using red LED indicators for each light beam. This feature makes lining up curtains and keeping them aligned a simple task.

Schneider Electric 1300 369 233.

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