Load balancing of welds in multi station sheet metal assembly lines
Paper in proceedings, 2010

The balancing of weld work load between executing stations and its robots has a significant influence on achievable production rate and equipment utilization. However, no automatic simulation based method for line balancing has been formulated up to this point. In practice, it is still manually conducted. Therefore in this work we propose two novel methods for load balancing of welds in multi station sheet metal assembly lines to minimize line cycle time. The methods are based on superimposition of the scenes/geometries of all line stations, with maintained robot positioning relative to the work piece, creating a “multi station”. The weld load is balanced between all multi station robots, whereupon the individual robots are combined into stations and coordinated station wise for simultaneous operation. Furthermore one of the proposed methods reduces the subsequent need for robot coordination, by introducing some restrictions on the load balancing: Firstly, for each robot, the weld load is balanced over the other station robots such that the working envelopes are maximally separated. Secondly, for each robot, the weld load is balanced over equivalently positioned robots in other line stations, based on previous station load balancing techniques. The proposed line balancing methods are applied on two industrial case studies which each involves the balancing of about 200 automotive stud welds between 3 stations, each of 4 robots. One of the proposed methods produces line cycle times close to that of the slowest uncoordinated robot, which can be considered a theoretical optimum of the line cycle time. Corresponding algorithm running time is about 30 minutes on an Intel Core 2 Quad with 8 GB RAM.

robot coordination

Sheet metal assembly

equipment utilization

load balancing

Author

Johan Segeborn

Chalmers, Product and Production Development, Product Development

Daniel Segerdahl

Fraunhofer-Chalmers Centre

Johan Carlson

Fraunhofer-Chalmers Centre

Anders Carlsson

Volvo Cars

Rikard Söderberg

Chalmers, Product and Production Development, Product Development

Proceedings of the ASME 2010 International Mechanical Engineering Congress & Exposition, Vancouver, British Columbia, Canada, November 12-18, 2010

PARTS A AND B 625-630

Subject Categories

Production Engineering, Human Work Science and Ergonomics

Mathematics

Computational Mathematics

Manufacturing, Surface and Joining Technology

Reliability and Maintenance

Areas of Advance

Production

DOI

10.1115/IMECE2010-40396

ISBN

978-0-7918-3891-4

More information

Latest update

11/26/2018