Mass and assembly time reduction for future generation automotive vehicles based on existing vehicle model.

摘要

This research presents method for evaluating the lightweightedness of a vehicle and an approach for vehicle assembly time savings potential developed through a case study. The Lazy Part Identification method for mass reduction specifically addresses those components whose primary purpose is to aid in manufacturing and assembly rather than to provide end-user function. Seven specific laziness indicators are described and illustrated: rigid-to-rigid connection, support for a flexible, non-moving part, positioning feature, duplicate geometry, fastener, bridging system, and material flow restriction. These indicators are used to evaluate individual vehicle components as part of a proposed method for identifying mass reduction potential. The indicators do not require extensive knowledge of the functionality of the components being evaluated, focusing instead on the geometry and assembly information available. The purpose of the proposed method is to focus the attention of designers on components or assemblies with high potential for mass reduction. This method is applied to a complete automotive vehicle consisting of approximately 1500 parts, demonstrating a mass savings potential of the overall vehicle of approximately 114 kilograms, or 5% of the total mass of the vehicle. The frequency of use of seven laziness indicators and various combinations of these indicators is also analyzed, and it is determined that the greatest potential for mass savings within the vehicle occurs when a part has rigid-to-rigid connection and duplicate geometry indicators. This analysis also demonstrates that entry-level manufacturing engineers can analyze a system based on geometric and assembly relationships, with a limited understanding of functionality, to identify potential mass savings. The outcome of this part of the research is a method for identifying potentially "lazy" components within a vehicle by providing laziness indicators and a systematic method for identifying the lazy parts.;This research also presents an approach and recommendations resulting from an empirical study on a vehicle assembly time savings workshop. The focus of the workshop was to reduce the assembly time of an automotive vehicle by reverse engineering a vehicle currently in production and applying design for assembly guidelines. The workshop was conducted at the OEM's research and development laboratory in Germany and required a collaborative effort between the US manufacturing plant and the German design group. The organization, equipment needed, and method used to conduct the assembly workshop are discussed in detail. The outcomes of the empirical study include assembly time reductions as well as best practices for conducting a time savings workshop. The results from the case study include a method used during a workshop focusing on reducing the assembly time of an automotive vehicle and a set of "best practice"; guidelines for future assembly time reduction workshops. Within the case study, a realization of immediate mass savings through the analysis of assembly time savings was recognized. This research will also discuss the potential of identifying parts in which both of these advantages may be gained. The ultimate goal of the research, is to develop a systematic and objective method that may be used to support lightweight engineering and assembly time savings for vehicles.