ABB welding robots help Mabey & Johnson bridge the world

Citation

(2001), "ABB welding robots help Mabey & Johnson bridge the world", Industrial Robot, Vol. 28 No. 6. https://doi.org/10.1108/ir.2001.04928faf.002

ABB welding robots help Mabey & Johnson bridge the world

ABB welding robots help Mabey & Johnson bridge the world

Keywords: Welding, Construction industry

Bridge builder Mabey & Johnson Ltd has ordered an IRB 2400L welding robot to add to the six ABB welding robots already in use with the company at its Lydney, Gloucestershire, plant (Plate 2).

Dave Bickerton, the Mabey & Johnson project engineer who headed the robot selection process said: "The IRB 2400L was chosen over the competition because of its advanced design; its cutting-edge productivity features such as Bullseye^® automated torch calibration and Advanced Welding Control 'Seamtracking' system; and commonality with, and reliability of, our current ABB robots".

The robot will provide extra capacity for new bridging contracts, particularly increased production of the Mabey Compact System of modular panel bridges, and will form the initial phase of a programme of re-investment in new automation.

As well as a wealth of civil applications throughout the world, Mabey & Johnson's Compact Bridging System was used for no less than 18 sites in Bosnia to fulfil the line of communication for the United Nations Protection force in Bosnia.

The Compact is a readily transportable, prefabricated bridging system, which can be rapidly erected in only a few days by unskilled labour without plant, and requires minimal maintenance thereafter.

Plate 2 ABB welding robots at Mabey & Johnson's Lydney plant

The system uses a high strength steel structure based on 3.05m long vertical panels, with attaching transoms, reinforcement chords, frames, braces, steel decking units, kerbing and other basic components. To maintain simplicity, these are standardised and the number of different components kept to a minimum.

Welding/fabrication of the components is carried out primarily by six modular-based ABB robots, each mounted on a traveling column and organised into paired cells operating 24 hours a day, seven days a week. Although the function of each cell can change, normally cells 1 and 2 are dedicated to panel fabrication, cells 3 and 4 chords, and cells 5 and 6 decking.

The new IRB 2400L will form a seventh "floating" cell that will process components as production contingencies occur, and form a back-up cell as individual robots are removed for upgrading.

The IRB 2400L is part of the IRB 2400 family of robots which offer a longer reach for welding, higher load capacities, improved motion performance, improved reliability and improved serviceability.

Each robot model uses an average 40 per cent fewer parts than earlier models and reliability has been increased even further with the introduction of maintenance-free gearboxes, better cabling and longer intervals between routine inspections (now a simple two-point check every three years).

A key feature of the IRB 2400L, which won over the Mabey & Johnson specifiers, was its Bullseye^® automated torch calibration system. Bullseye^® ensures optimum quality and reduces downtime by enabling the robot to check its own tool centre point (TCP). The TCP is a crucial reference point that determines the position, accuracy and quality of the weld.

On most robots, TCP confirmation is normally a lengthy, arduous process that is carried out on a regular basis after occurrences such as collision with a fixture, changes in ambient temperature or a worn contact tip.

The IRB 2400L also features advanced weld control (AWC) "through-the-arc" tracking. AWC follows weld joints by sampling the welding current and voltage signals synchronized with the robot weave pattern, and provides vertical and horizontal correction signals to the robot controller to assure a consistent fill of the weld joint. Advanced tracking is required to accommodate special situations where joints vary, other special weld conditions apply or when a "part fit" is less than desirable.

For further information please contact: David Marshall, ABB Automation, Auriga House, Precedent Drive, Rooksley, Milton Keynes MK13 8PQ, UK. Tel: +44 (0)1908 350300; Fax: +44 (0)1908 350301; E-mail: david.marshall@gb.abb.com