| 1. |
- Lööf, Johan, 1979, et al.
(författare)
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Top-Down Decomposition of Multi-Product Requirements onto Locator Tolerances
- 2007
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Ingår i: Proceedings of IMECE2007, 2007 ASME International Mechanical Engineering Congress and Exposition, November 11-15, 2007, Seattle, Washington, USA.. - 0791842975 ; 3, s. 247-255
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Konferensbidrag (refereegranskat)abstract
- The tolerance allocation problem consists of choosing tolerances on dimensions of a complex assembly so that they combine into an ‘optimal state’ while fulfilling certain requirements on an allowed variation. This optimal state often coincides with the minimum manufacturing cost of the product. Sometimes it is balanced with an artificial cost that the deviation from target induces on the quality of the product.This paper suggests a multiobjective formulation of the tolerance allocation problem to automatically decompose requirements for an allowed variation on a set of critical product dimensions. This formulation is demonstrated using a rear lamp on a car with multiple requirements on allowed variation. In this case only the tolerances on locators that locates the lamp on the body are considered. The paper also reviews a selection of work that has been made on solving tolerance allocation problems.
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| 2. |
- Jareteg, Cornelia, 1986, et al.
(författare)
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Geometry Assurance Integrating Process Variation with Simulation of Spring-in for Composite Parts and Assemblies
- 2014
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Ingår i: Proc. of ASME 2014 International Mechanical Engineering Congress & Exposition. - 9780791846438 ; 2A
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Konferensbidrag (refereegranskat)abstract
- Geometrical variation and deviation in all manufacturing processes affect quality of the final product. Therefore geometry assurance is an important tool in the design phase of a new product. In the automotive and aviation industries where the use of composite parts is increasing drastically, new tools within variation simulations are needed. Composite parts tend to deviate more from nominal specification compared to metal parts. Methods to simulate the manufacturing process of composites have been developed before. In this paper we present how to combine the process variation simulation of composites with traditional variation simulations. The proposed method is demonstrated on a real complex subassembly, representing part of an aircraft wing-box. Since traditional variation simulation methods are not able to capture the spring-in and the special deviation behavior of composites,the proposed method adds a new feature and reliability to the geometry assurance process of composite assemblies.
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| 3. |
- Jareteg, Cornelia, 1986, et al.
(författare)
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Variation simulation for composite parts and assemblies including variation in fiber orientation and thickness
- 2014
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Ingår i: Procedia CIRP CATS 2014. 5th CATS 2014 - CIRP Conference on Assembly Technologies and Systems. - : Elsevier BV. - 2212-8271. ; 23, s. 235-240
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Konferensbidrag (refereegranskat)abstract
- All manufacturing processes are afflicted by geometrical variation, which can lead to defect products. A simulation tool for geometry assurance analysis is therefore important in the design process. The use of composites has recently increased drastically, but there is still a lack of understanding about the effects of variation in such parts. A method for predicting variation in subassemblies, including variation in fiber orientation and ply thickness for composites is presented. The approach is demonstrated on an industrial case and finite element analysis is used to calculate the deformation. In particular, contribution from variation in material properties to the variation in critical points is analyzed. The results indicate that material uncertainties have a small impact on the geometric variation for the test case.
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| 4. |
- Lorin, Samuel C, 1983, et al.
(författare)
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Simulating Geometrical Variation in Injection Molding
- 2010
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Ingår i: Proceedings of NordDesign2010 International Conference on Methods and Tools for Product and Production Development, August 25-27, Gothenburg, Sweden.. - 9789163370649 ; 8:2, s. 395-404
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Konferensbidrag (refereegranskat)
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| 5. |
- Salman, R., et al.
(författare)
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An industrially validated CMM inspection process with sequence constraints
- 2016
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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 44, s. 138-143
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Konferensbidrag (refereegranskat)abstract
- An efficient CMM inspection process implemented in industry gives significant productivity improvements. A key part of this improvement is the optimization of the inspection sequences. To ensure quality of the inspection the sequences are often constrained with respect to the order of the measurements. This gives rise to so called precedence constraints when modelling the inspection sequence as a variation of the travelling salesperson problem (TSP). Two heuristic solution approaches and a generic optimizing algorithm are considered. A generation based stochastic algorithm is found to reduce cycle time by as much as 12% in comparison to the currently used algorithm.
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| 6. |
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| 7. |
- Segeborn, Johan, 1972, et al.
(författare)
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Load balancing of welds in multi station sheet metal assembly lines
- 2010
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Ingår i: Proceedings of the ASME 2010 International Mechanical Engineering Congress & Exposition, Vancouver, British Columbia, Canada, November 12-18, 2010. - 9780791838914 ; 3:PARTS A AND B, s. 625-630
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Konferensbidrag (refereegranskat)abstract
- 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 manuallyconducted. 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 arecombined 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 theworking 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.
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| 8. |
- Wandebäck, Fredrik, et al.
(författare)
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Variation Feedback and 3D Visualization of Geometrical Inspection Data
- 2010
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Ingår i: Proceedings of the ASME 2009 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE, August 30 - September 2, 2009, San Diego, California, USA. - 9780791849057 ; 8, s. 197-208
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Konferensbidrag (refereegranskat)abstract
- There is no type of manufacturing process that is not afflicted by variation. Activities intended to ensure the quality of a company's geometry processes are usually referred to as geometry assurance activities. One clear industrial problem is to understand the relations between the products concept and the manufacturing process. Dimensional data is a very important source of experience of how a product's geometry has worked in the interaction with the actual manufacturing system. Users therefore need good analysis and presentation tools of geometry outcomes to support both the product developers and production engineers in the analysis of the production output and its consequences. Today the dimensional data can be difficult to obtain or access, and is not necessarily presented in such a way as to provide the user with all necessary information. This paper presents how presentation and analysis tools of geometrical inspection data can be taken a step further. New functionality for feature based 3D visualization of inspection data has been developed which integrates the variation simulation platform and the inspection data database. The goal has been to create better tools for analysis of geometrical variation and increase the understanding of the sources of variation.
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| 9. |
- Wärmefjord, Kristina, 1976, et al.
(författare)
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Geometrical inspection point reduction for rigid and non-rigid parts using cluster analysis – an industrial verification
- 2007
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Ingår i: 10th CIRP Conference on Computer Aided Tolerancing, Specification and Verification for Assemblies, March 21-23, Erlangen, Germany, 2007.
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Konferensbidrag (refereegranskat)abstract
- Since the model program in automotive industry gets more and more extensive, the costs related to inspection increase. Therefore, there are needs for more effective inspection preparation. In many situations, a large number of inspection points are inspected, despite the fact that only a small subset of points is needed. In this paper a method for reducing the number of inspection point using cluster analysis is tested on production data. The method finds clusters, where the points in a cluster are highly correlated. From each cluster only one representing point is selected for inspection. This leads to reductions with up to 90 percent in the case studies considered. Further, the problem about sample size is considered. The sample must be large enough to reflect the different phenomena occurring in the process. The choice of sample size is also affecting the statistical confidence of the estimated correlation coefficient between points or clusters. The theory supports rigid parts as well as non-rigid parts.
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| 10. |
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