Sheet Metal Joining Process Parameters Evaluation in a Geometry Assurance Context
Examensarbete på grundnivå
Li, Xuewei Li
The thesis was a master thesis project done at Volvo Trucks in cooperation between Technology and Operation departments with supervision from Wingquist Laboratory at Chalmers University in Sweden. During the assembly process of the sheet metals, a complicated combination of many assembly factors influences the geometry outcome and lead to unexpected deformation. The project is conducted in the geometry assurance field with the goals of evaluating the assembly process parameters and suggesting an improving method for the geometrical quality of the final assembly. The purposes are to highlight the most influential assembly factors and investigate the impact of changing the geometry spots (geo-spots) parameters on the assembly geometrical variation. To achieve the project goals, directed interviews and surveys were made with industrial experts in Volvo Trucks Technology and Operation departments, to propose the most influential assembly factors that cause geometrical deformation in the assembly process, and to perceive and evaluate the approach of choosing the geo-spots parameters from experience perspective. Moreover, a study based on the Design of Experiments was performed to determinate the active geo-spots parameters. Furthermore, a sensitivity-based optimization for the geo-spots sequence was demonstrated and implemented to illustrate the ability for geometry improvement. Eventually, several variation simulations for different geo-spots parameters were executed for analysis and comparison purposes. One industrial study case and three simple cases with common shapes were used to simulate, analyze and evaluate the gathered data. CAT simulation tool RD&T was used for the simulation and optimization purposes. The simulation results confirmed the survey results about the high variation sensitivity of the geo-spots position, number and sequence changes. It also showed that there is a big room for geometry improvement when implementing geo-spots sequence optimization. The DoE simulation results showed the number of geo-spots interacted with the welding sequence of the nearest locator and the welding based from the geometry spot to the nearest locator needs to be considered when deciding the location of the geo-spots. The variation simulation results proved that using a variation simulation software significantly helps when choosing the most appropriate set of geo-spots parameters. Combining the CAT software simulation with practical engineering experience, improvement of the final assembly geometrical result could be achieved, and a more robust design could be made.
spot welding simulation, geometry assurance, engineering improvement, , operation analysis, DoE, CAT, RD&T