Posted to Applications on Sunday, March 18, 2007 Share:

Mitsubishi robots protect workers from RSI

Three Mitsubishi RV12SLs robots are protecting human workers from the risks of RSI (repetitive strain injury) at a manufacturer of suspended flooring panels, thanks to palletisers installed by Barr & Paatz.

Suspended flooring systems are becoming almost obligatory in new-build offices and other working environments where computers are used. The space beneath the floors allows cabling to be run freely to each workstation without being unsightly or causing a trip hazard. Access to the cabling is gained by lifting one or more panels - a procedure so simple that it does not hamper the regular reconfiguration and updating needed by professional computer networks.

One manufacturer of suspended flooring is using three Mitsubishi RV12SLs robots, the company's largest and most powerful, installed by systems integrator Barr & Paatz.

The panels are made of steel-clad chipboard and weigh 12kg each. Originally a conveyor belt collected them from the production cells, transporting them to the packing area, where they would be manually stacked 38 high onto fork lift truck pallets. Sterling Paatz who led the design and installation team, states: "This was hard physical labour. The first few panels onto the pallets had the operatives bending over, and the last few had them stretching up. Additionally every other panel has to be inverted so that the polished steel surfaces face each other, rather than risk them being scratched by contact with the chipboard side."

Automating materials handling

It was realised that the best way to protect personnel from RSI and back injuries was to design out manual lifting from their processes. Barr & Paatz is recognised for its expertise in automating materials handling processes. Paatz explains: "We started by listing the givens; these included that the panels have to be stacked on fork lift pallets because that is essential for efficient distribution and logistics. We also had to protect the polished steel face of each panel."

There are many stacking mechanisms, and thought was given to using these and interleaving the panels with protective liners. However, it was soon realised that robots would be better, as they could be programmed to turn over alternate panels in the industry-standard way and would provide a simple, reliable 'one machine' arrangement and would be easy to adapt for future developments.

"Having decided to go down the robot route, we set about finding the best for the job. They had to be able to lift a 12kg panel and needed a reach of 1.2m. Additionally they had to have the dexterity to perform the inversion, the accurate repeatability for neat and secure stacking and speed to spare for expected increases in production."

State-of-the-art robots

Mitsubishi RV12SL robots were selected because they have a payload of 14kg and reach of 1.4m, so are comfortably able to cope, and with six axes of motion, the manipulation was easily accomplished. Mitsubishi Electric offers a full range of articulated-arm robots, from small units that can be installed directly next to or even inside machinery and systems for handing small components, to the mighty RV-S series. The latter is the latest generation of six-DOF (degrees of freedom) robots from Mitsubishi Electric. With repeatability of +/-0.05mm and speeds of up to 9500mm/s the RV-12SL is said to represent the state-of-the-art for robots.

Paatz sums up: "Using robots to protect people from potential injury is very much an emerging trend. It seems that suddenly robots have broken out of car plants and into every industrial sector. Amongst other jobs, they are great for the repetitive heavy lifting and manipulating tasks where the risks of back injuries and RSI would hang over human operatives."