Requirements for Datum Systems in Computer Aided Tolerancing and the Verification Process

Weißgerber, Marco; Ebermann, Marko; Gröger, Sophie; Leidich, Erhard

doi:10.1016/j.procir.2016.02.096

Cited by 8 publications

(9 citation statements)

References 10 publications

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“…Four main operations play a key role in the manipulation of Skin Model Shapes as defined in ISO 17450-1: (1) partitioning (division of extracted skin model corresponding to respective features), (2) extraction (representation of an object by point cloud), (3) filtration (separation of form defects from waviness and roughness), and (4) association (a mathematical operation to fit ideal features) [40]. Specifically, the partitioning and extraction operations help in representing and manipulating of parts and fixtures proposed in this paper.…”

Section: Skin Model Shapesmentioning

confidence: 99%

“…( 36)- (41). The test points whose origin set at [ (40,40,120), (40,160,120), (160, 40, 120), (160, 160, 120)] for KPC 1 and [ (40,200,100), (40,200,120), (160, 200, 100), Fig. 11 An illustration of virtual inspection of a part ( b S h; 0 0 0 0 1…M Þ using 4 probe points (160,200,120)] for KPC 2 were projected onto their respective machined surface to obtain measurement points.…”

Section: Case Studymentioning

confidence: 99%

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Variation propagation modeling in multistage machining processes considering form errors and N-2-1 fixture layouts

Yacob

Semere

Anwer

2021

Int J Adv Manuf Technol

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Variation propagation modeling of multistage machining processes enables variation reduction by making an accurate prediction on the quality of a part. Part quality prediction through variation propagation models, such as stream of variation and Jacobian-Torsor models, often focus on a 3-2-1 fixture layout and do not consider form errors. This paper derives a mathematical model based on dual quaternion for part quality prediction given parts with form errors and fixtures with N-2-1 (N>3) layout. The method uses techniques of Skin Model Shapes and dual quaternions for a virtual assembling of a part on a fixture, as well as conducting machining and measurement. To validate the method, a part with form errors produced in a two-stationed machining process with a 12-2-1 fixture layout was considered. The prediction made following the proposed method was within 0.4% of the prediction made using a CAD/CAM simulation when form errors were not considered. These results validate the method when form errors are neglected and partially validated when considered.

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Section: Skin Model Shapesmentioning

confidence: 99%

Section: Case Studymentioning

confidence: 99%

Variation propagation modeling in multistage machining processes considering form errors and N-2-1 fixture layouts

Yacob

Semere

Anwer

2021

Int J Adv Manuf Technol

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“…Due to the error of point data during the acquisition process in practice [14], the vertices in a relatively small region do not share the same value of curvedness and shape index. Therefore, an iterative voting method [15] is conducted in order to refine the local shape type.…”

Section: Initial Region Partitionmentioning

confidence: 99%

A Framework for Curvature-Based CAD Mesh Partitioning

Qie

Qiao

Anwer

2021

Lecture Notes in Mechanical Engineering

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In ISO Geometrical Product Specifications and Verification Standards (GPS) [1], partition is one of the fundamental operations used to obtain ideal or non-ideal features of a product. The operation of partition produces independent geometrical features by decomposing the object. A curvature-based CAD mesh partitioning framework is proposed in this paper. The framework combines several key steps including curvature-based attribute calculation, local shape type refinement, region growing, slippage analysis and statistical modeling. The partitioned features are classified into seven invariance classes of surface in the context of ISO GPS. A case study shows that not only appropriate partitioning but also accurate invariance class recognition for GPS are achieved by the proposed framework.

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“…The norm ISO 5459:2011 describes the current, standardized approach [28]. Datum systems are used to define a coordinate system for geometrical evaluations and an alignment for tolerance zones of geometrical tolerances (GD&T) according to the ISO system for Geometrical Product Specifications (GPS) [29][30][31].…”

Section: Problem Settingmentioning

confidence: 99%

On the Development of a Surrogate Modelling Toolbox for Virtual Assembly

2021

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Virtual assembly (VA) is a method to simulate the physical assembly (PA) of scanned parts. Small local part deviations can accumulate to large assembly deviations limiting the product quality. The propagation of geometrical deviations onto the assembly is a crucial step in tolerance management to assess the assembly quality. Current approaches for VA do not sufficiently consider the physical joining process. Therefore, the propagated assembly geometry may deviate strongly from the PA. In the state of the art, only specific and complex methods for particular joining processes are known. In this paper, the concept of Surrogate Models (SMs) is introduced, representing the connection between part and assembly geometries for particular joining processes. A Surrogate Modelling Toolbox (SMT) is developed that is intended to cover the variety of joining processes by the implementation of suitable SMs. A particular SM is created by the composition of suitable Surrogate Operations (SOs). An open list of SOs is presented. The composition of a SM is studied for a laser welding process of two polymer components. The resulting VA is compared to the PA in order to validate the developed model and is quantified by the exploitation ratio R.

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Requirements for Datum Systems in Computer Aided Tolerancing and the Verification Process

Cited by 8 publications

References 10 publications

Variation propagation modeling in multistage machining processes considering form errors and N-2-1 fixture layouts

Variation propagation modeling in multistage machining processes considering form errors and N-2-1 fixture layouts

A Framework for Curvature-Based CAD Mesh Partitioning

On the Development of a Surrogate Modelling Toolbox for Virtual Assembly

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