Individualizing Locator Adjustments of Assembly Fixtures Using a Digital Twin

Abstract

Implementing the concept of a digital twin in full production provides enough data on each individual assembly for real-time control of production processes. Taking advantage of this opening, this paper proposes individualized locator adjustments as a new method to improve the geometrical quality of assemblies. In this method, all locators in the assembly fixture can be adjusted for each individual assembly based on the scan data of the mating parts of that assembly. The optimal adjustment of every locator for each individual assembly is obtained using an optimization algorithm and nonrigid variation simulation tools (computer-aided tolerancing tools). This method is applied to three industrial cases and geometrical variations and the mean deviation from nominal positions are compared to nonindividualized adjustments and also when there are no adjustments. The results show that applying this method, an improvement of up to 81% in geometrical variation and 78% in the mean deviation of assemblies can be obtained compared to assemblies without adjustments. These improvements are 60% and 57% higher than nonindividualized adjustments of locators for the variation and the mean deviation, respectively. Moreover, a modification on the optimization algorithm has been proposed that reduces the amount of required adjustments.

Digital Twin for Variation Management: A General Framework and Identification of Industrial Challenges Related to the Implementation

“…Furthermore, the joining process can be optimized with respect to geometrical quality. Locators can be adjusted [19], and spot welding sequences can be optimized [20] for each individual assembly. By those suggested adjustments, the geometrical quality of the assembly can be improved without changing the tolerances of the parts, which is beneficial from a cost perspective.…”

“…With this approach, studies on several industrial cases have shown that the variation of the final subassembly can be reduced up to 50%, compared to when no adjustments are done [18][19][20]. With the labeling digital model, digital shadow, and digital twin mentioned at the beginning of this section, a digital twin for geometry assurance can be interpreted as:…”

“…With this approach, studies on several industrial cases have shown that the variation of the final subassembly can be reduced up to 50%, compared to when no adjustments are done [18][19][20].…”

Calculating the gravity-free shape of sheet metal parts

“…With these simulation models, often referred to as digital twin, optimizations can be performed and more precise predictions can be made. Especially, for the automotive and aerospace industry, this principle is used for optimizing the assembly of thin parts, for example, sheet metal body parts as presented by A. Rezaei Aderiani et al [2]. Before simulations with digital twins were performed in the quality assurance processes, only physical measurements were compared.…”

Physics-Based Compressive Sensing to Enable Digital Twins of Additive Manufacturing Processes

“…The ultimate goal of DTs is to reduce the overall lifecycle cost of physical systems. In manufacturing systems, DTs enable us to better monitor, control, and optimize the processes [1][2][3][4]. The enabling technologies of manufacturing DTs include sensing [5], control [6], modeling and simulation [7], predictive maintenance [8], data analytics [9,10], lifecycle information management [11], and others.…”