A Fixture Failure Control Chart for Variation Caused by Assembly Fixtures

2012 ◽  
Author(s):  
Kristina Wärmefjord ◽  
Johan S. Carlson
Keyword(s):  
Fault Diagnosis ◽  
Case Studies ◽  
Control Chart ◽  
Assembly Process ◽  
Final Assembly ◽  
Sources Of Variation ◽  
Auto Body ◽  
Different Sources

In the auto body assembly process, fixtures are used to position parts during assembly and inspection. If there is variation in the positioning process, this will propagate to the final assembly. There are also other sources of variation in the final assembly, such as variation in parts due to previous manufacturing steps. To facilitate the separation of the different sources of variation, and thereby also improve fault diagnosis, a fixture failure subspace control chart is proposed. This control chart is based on a multivariate T2-chart, but only variations in the fixture failure subspace are considered. The method is applied to two industrial case studies with satisfying results.

Controlling Geometrical Variation Caused by Assembly Fixtures

2016 ◽  
Vol 16 (1) ◽  
Author(s):  
Kristina Wärmefjord ◽  
Johan S. Carlson ◽  
Rikard Söderberg
Keyword(s):  
Control Chart ◽  
Manufacturing Processes ◽  
Assembly Process ◽  
Final Assembly ◽  
Sources Of Variation ◽  
Geometrical Variation ◽  
Auto Body

In the auto body assembly process, fixtures position parts during assembly and inspection. Variation in the positioning process propagates to the final assembly. To control the assembly fixtures, repeatability studies are used. Those studies are, however, usually done with long intervals and the fixtures might be afflicted with variation between studies. There are also other sources of variation in the final assembly, such as variation in parts due to previous manufacturing steps. To separate variation caused by fixtures and the variation caused by previous manufacturing processes, a multivariate fixture failure subspace control chart is proposed.

Analysis of Nonlinear Variation Accumulation in Auto-Body Assembly Process

Manufacturing ◽  
2002 ◽  
Author(s):  
Jun Lian ◽  
Zhongqin Lin ◽  
Fusheng Yao ◽  
Xinmin Lai
Keyword(s):  
Sheet Metal ◽  
State Equation ◽  
Assembly Process ◽  
Transformation Mechanism ◽  
Metal Parts ◽  
Sheet Metal Parts ◽  
Accumulation Mechanism ◽  
Auto Body ◽  
Non Gaussian ◽  
Geometrical Dimensions

In the assembly process of auto-body, variations in the geometrical dimensions of sheet metal parts and fixtures are inevitable. These variations accumulate through the multi-station assembly process to form the dimensional variations of the final products. Compared with the assembly of rigid parts, the assembly process of the elastic parts is more complex because the variation accumulation patterns rely much on the variations of fixture, jointing methods and mechanical deformation. This paper aims at analyzing the variation transformation mechanism and accumulation characteristics for the assembly of sheet metal parts based on the analysis of dimensional coordination relations among parts and fixtures. Finite element method (FEM) and Monte-Carlo Simulation (MCS) were used to analyze the effect of jointing contact on variation transformation, while a state equation was developed to describe the variation accumulation mechanism. The result of the analysis indicates that the main characteristics of elastic assembly jointing are the overlap jointing methods and elastic contacts action. The fact that the variation transform coefficients (VTC) are variable makes the assembly variation distribution Non-Gaussian even if the dimension variation of parts is Gaussian distribution. The analysis conclusions have potential value for more reasonable tolerance synthesis of elastic parts assembly.

scholarly journals Sign surveys for red fox (Vulpes vulpes) censuses: evaluating different sources of variation in scat detectability

2018 ◽  
Vol 64 (2) ◽  
pp. 183-190 ◽  
Author(s):  
María Cortázar-Chinarro ◽  
Peter Halvarsson ◽  
Emilio Virgós
Keyword(s):  
Vulpes Vulpes ◽  
Red Fox ◽  
Sign Surveys ◽  
Sources Of Variation ◽  
Different Sources

Multiple Fault Diagnosis Method in Multistation Assembly Processes Using Orthogonal Diagonalization Analysis

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Zhenyu Kong ◽  
Dariusz Ceglarek ◽  
Wenzhen Huang
Keyword(s):  
Fault Diagnosis ◽  
Product Information ◽  
Statistical Significance ◽  
Measurement Data ◽  
Space Representation ◽  
Assembly Process ◽  
Dimensional Control ◽  
Multiple Fault ◽  
Multiple Fault Diagnosis ◽  
Multistation Assembly

Dimensional control has a significant impact on overall product quality and performance of large and complex multistation assembly systems. To date, the identification of process-related faults that cause large variations of key product characteristics (KPCs) remains one of the most critical research topics in dimensional control. This paper proposes a new approach for multiple fault diagnosis in a multistation assembly process by integrating multivariate statistical analysis with engineering models. The proposed method is based on the following steps: (i) modeling of fault patterns obtained using state space representation of process and product information that explicitly represents the relationship between process-related error sources denoted by key control characteristics (KCCs) and KPCs, and (ii) orthogonal diagonalization of measurement data using principal component analysis (PCA) to project measurement data onto the axes of an affine space formed by the predetermined fault patterns. Orthogonal diagonalization allows estimating the statistical significance of the root cause of the identified fault. A case study of fault diagnosis for a multistation assembly process illustrates and validates the proposed methodology.

Optimization of the installation sequence for the temporary fasteners in the aircraft industry

2021 ◽  
pp. 1-25
Author(s):  
Tatiana Pogarskaia ◽  
Sergey Lupuleac ◽  
Julia Shinder ◽  
Philipp Westphal
Keyword(s):  
Combinatorial Problem ◽  
Hole Drilling ◽  
Assembly Process ◽  
Process Verification ◽  
Final Assembly ◽  
Uncertain Input ◽  
Uncertain Input Data ◽  
Aircraft Production

Abstract Riveting and bolting are common assembly methods in aircraft production. The fasteners are installed immediately after hole drilling and fix the relative tangential displacements of the parts, that took place. A proper fastener sequence installation is very important because a wrong one can lead to a “bubble-effect”, when gap between parts after fastening becomes larger in some areas rather than being reduced. This circumstance affects the quality of the final assembly. For that reason, the efficient methods for determination of fastening sequence taking into account the specifics of the assembly process are needed. The problem is complicated by several aspects. First of all, it is a combinatorial problem with uncertain input data. Secondly, the assembly quality evaluation demands the time-consuming computations of the stress-strain state of the fastened parts caused by sequential installation of fasteners. Most commonly used strategies (heuristic methods, approximation algorithms) require a large number of computational iterations what dramatically complicates the problem. The paper presents the efficient methods of fastener sequence optimization based on greedy strategy and the specifics of the assembly process. Verification of the results by comparison to commonly used installation strategies shows its quality excellence.

Fault Diagnosis of MOVA Based on Evidence Theory

2014 ◽  
Vol 556-562 ◽  
pp. 2685-2688
Author(s):  
Ai Hua Zhou ◽  
Hong Song ◽  
Yu Fang ◽  
Zheng Wei Chang
Keyword(s):  
Experimental Data ◽  
Fault Diagnosis ◽  
System Reliability ◽  
Infrared Imaging ◽  
Early Stage ◽  
Evidence Theory ◽  
Power System Reliability ◽  
Present Evidence ◽  
Insulation Coordination ◽  
Different Sources

The health of MOVA is very important for power system reliability and insulation coordination studies.MOVA is subjected to different kinds of stresses in services, which will cause degradation at early stage or in the long run.This paper present evidence theory for fault diagnosis of MOVA. Evidence theory can simultaneously analyze information from different sources,draw comprehensive conclusions,reduce single information misjudgment. In this paper, resistive leakage current and infrared imaging make up two types of evidence body for judge. Analysis of experimental data shows that this method can effectively detect early fault of the MOVA.

scholarly journals Modeling and verification of contingency resolution strategies for multi-robot missions using temporal logic

2019 ◽  
Vol 16 (6) ◽  
pp. 172988141988569
Author(s):  
Shaurya Shriyam ◽  
Satyandra K Gupta
Keyword(s):  
Adverse Effects ◽  
Case Studies ◽  
Temporal Logic ◽  
Human Intervention ◽  
Assembly Process ◽  
Assembly Operations ◽  
Multiple Assembly ◽  
Multi Robot ◽  
Resolution Strategies

This article presents an approach for assessing contingency resolution strategies using temporal logic. We present a framework for nominal mission modeling, then specifying contingency resolution strategies and evaluating their effectiveness for the mission. Our approach focuses on leveraging the use of model checkers to the domain of multi-robot missions to assess the adequacy of contingency resolution strategies that minimize the adverse effects of contingencies on the mission execution. We consider missions with deterministic as well as probabilistic transitions. We demonstrate our approach using two case studies. We consider the escorting of a ship in a port where multiple contingencies may occur concurrently and assess the adequacy of the proposed contingency resolution strategies. We also consider a manufacturing scenario where multiple assembly stations collaborate to create a product. In this case, assembly operations may fail, and human intervention is needed to complete the assembly process. We investigate several different strategies and assess their effectiveness based on mission characteristics.

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