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MOTOMAN ROBOTICS (UK) LTD |
Press Release
NEW PRODUCTION CELL FOR WELDING DISCOVERY EXHAUSTS
A new robotic facility entered production in July 2004 at the Coventry factory of first-tier automotive supplier, Unipart Eberspächer Exhaust Systems (UEES), to manufacture stainless steel exhausts for the Land Rover Discovery 3, due for launch this autumn, and for a future model of Range Rover. A total of 21 Motoman robots served by rotary positioners from the same supplier have been installed. Most are for arc welding, with two robots being deployed for in-process sub-assembly operations.
Motoman advises that four interlinked cells make up the new production facility, which operates two shifts, five days a week producing three exhaust variants for the Discovery 3 and, later this year, three for the future Range Rover model. Two cells containing four robots each currently weld twin-skinned, fabricated manifolds for V6 and V8 petrol engines respectively for the Discovery 3; and a twin-robot cell welds all the downpipes. The fourth cell, with nine robots, produces inter-rears – the section from the end of the downpipes to the tailpipes, including silencers, of which four are required for each petrol engine. A further two Motoman robots carry out assembly of internals for the silencers.
One technical innovation that has reduced both the capital investment and footprint of the inter-rear production cell was to configure two Motoman UP20 robots with a twin-wire feed system, normally used with identical wires to increase speed of deposition and allow thicker material to be welded. However, in this case two different types of stainless steel wire are used sequentially, one austenitic and the other ferritic, to accomplish different joining operations and avoid having to install additional robots. The same technique is used on a Motoman UP6 robot for cup welding on V6 manifolds.
Simplest of the cells is downpipe welding, completed by a single- and a twin-robot system. In contrast, by far the most complex operation is manifold production. Motoman here describes the sequence of operations for the V8 petrol version, although production for the V6 and diesel manifolds is similar.
The V8 manifold comprises separate left- and right-hand elements, the cell being configured to produce 12 pairs per hour. Each half contains eight internal hydroformed parts that are welded at the first station and subsequently inserted between lower and upper pressings. These are joined together at the next station by deposition of a 1.4 metre weld seam using a single robot, one manifold hand being welded while the other is loaded.
Four inlet flanges are welded on at a similar station and then milled flat using a Chiron vertical machining centre. Following automatic cleaning, the left- and right-hand assemblies pass to another robotic station where the outlet flanges are welded on. After leak testing and in-cycle engraving when the manifolds pass, the flatness and surface finish of flanges are checked on a purpose-built quality rig which generates SPC data for production control.
Final assembly of inter-rears takes place within a cell equipped with two Motoman welding robots and a large, twin-station positioner measuring three metres across which rotates in the horizontal plane. This solution for component manipulation was less expensive than using two single positioners and occupies less floor space.
As far as possible there is commonality of robotic welding equipment across the different applications. Programming is carried out in-house using Motoman's XRC controller, which simplifies co-ordinating the movements of multiple robots in a cell. To speed changeover after a batch of one exhaust variant is complete, all stations are equipped with jig recognition with feedback to the control to ensure that the correct program is run for the next batch. This is particularly important as the suites of jigs appear similar, having only subtle differences, so it would be only too easy for errors to occur.
Banbury-based Motoman Robotics (UK) undertook turnkey responsibility for installation of the whole facility. Much of the integration was subcontracted to Bauromat (UK), Pershore, which built two of the seam welders in the inter-rear cell and another for the V6 manifold cell. It also manufactured all the tooling for the latter.
Commented Paul Ross, project engineer at UEES, "Although Motoman is our preferred robot system partner, we nevertheless reviewed the market before placing the latest order. We receive a high level of support from Motoman, with rapid resolution of any issues that occur. In addition, the long-term reliability of the robots themselves has proved to be very good."
For More Information Contact:
Motoman Robotics (UK) Ltd
Johnson Park, Wildmere Road, Banbury, Oxon OX16 3JU
Tel: 01295 272755
FAX: 01295 267127
E-mail:
information@motoman.co.uk