Car plant benefits from intelligent robots

Three robots with intelligent control and integrated 3D laser vision systems help build cars at modern floor pan assembly line in Sunderland, the first of its kind in Europe.

Nissan's Sunderland plant is the first in Europe to implement the company's latest approach to floor pan assembly.

The recent installation of the floor pan assembly line has effectively removed the need for framing jigs on initial spot welding operations.

Core to the line's effectiveness is the use of three Fanuc robots with intelligent control and integrated 3D laser vision systems.

Three conveyor systems each bring subassemblies - the engine compartment, and front and rear floor sections - to the robot handling area.

Each subassembly is loaded freely onto its respective conveyor without the use of tooling so when they arrive at the robot area positioning is inconsistent.

Each robot is a Fanuc R2000iA, a six-axes 200kg load capacity arm, fitted with a Fanuc V500iA 3DL vision system to locate the panel position.

The robots handling the front and rear floor are each mounted on a servo driven linear axis allowing them to travel out to the conveyor pick up point.

The robot handling the engine compartment section is statically mounted next to the other two units.

When the subassemblies arrive at their respective pick up points, each robot moves to its programmed panel location.

At this point the vision system, which is interfaced directly to the RJ3i intelligent controller, locates datum points allowing the panels orientation to be compensated for by the robot.

With the subassemblies firmly gripped, each robot moves to a position above the NC tooling station that also uses Fanuc control.

In free space, the robots interlock the panels together - firstly assembling the engine compartment to the front floor and then the third robot interlocking the rear floor section.

The three robots and the NC tooling station then move in unison to transfer the floor pan from the robots' grippers to the NC tooling posts.

At this point the locate-and-load process is complete and further spot welding robots continue the assembly operations.

Chris Watt, Engineer with Nissan European Production Engineering, said: "The cycle time for the assembly is currently 56s although if required the line is designed to run at 47s".

"Where we really benefit is in the ability to produce variants without lengthy tool change times".

"Variants are programmed into the robot and the NC tooling controllers and conventional tooling and fixtures are not required".

"Using standard off-the-shelf products has added value to this new line by removing the need for dedicated tooling".

"The savings are not only on initial capital cost but also ongoing savings are gained".

"Conventional tooling gets damaged and also wears causing non intelligent robots to need regular reprogramming".

"In addition to removing tooling errors, the need to compensate for slack and worn conveyors is removed - this makes our conveyor requirements really straight-forward".

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