RESEARCHING FOR THE SAMPLING METHOD ON CMM

Accurate dimensional inspection and error analysis of free-form surfaces requires accurate registration of the component in hand. Registration of surfaces defined as non-uniform rational B-splines (NURBS) has been realized through an implementation of the iterative closest point method (ICP). The paper presents performance analysis of the ICP registration method using Monte Carlo simulation. A large number of simulations were performed on an example of a precision engineering component, an aero-engine turbine blade, which was judged to possess a useful combination of geometric characteristics such that the results of the analysis had generic significance. Data sets were obtained through CAD (computer aided design)-based inspection. Confidence intervals for estimated transformation parameters, maximum error between a measured point and the nominal surface (which is extremely important for inspection) mean error and several other performance criteria are presented. The influence of shape, number of measured points, measurement noise and some less obvious, but not less important, factors affecting confidence intervals are identified through statistical analysis.

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Automatic Generation of Anisotropic Patterns of Geometric Features for Industrial Design

Journal of Mechanical Design ◽

10.1115/1.4032092 ◽

2015 ◽

Vol 138 (2) ◽

Cited By ~ 3

Author(s):

Diego Andrade ◽

Ved Vyas ◽

Kenji Shimada

Keyword(s):

Boundary Conditions ◽

Computer Aided Design ◽

Industrial Design ◽

Automatic Generation ◽

Free Form ◽

Geometric Features ◽

Target Domain ◽

Metric Tensor ◽

Target Region ◽

Free Form Surfaces

While modern computer aided design (CAD) systems currently offer tools for generating simple patterns, such as uniformly spaced rectangular or radial patterns, these tools are limited in several ways: (1) They cannot be applied to free-form geometries used in industrial design, (2) patterning of these features happens within a single working plane and is not applicable to highly curved surfaces, and (3) created features lack anisotropy and spatial variations, such as changes in the size and orientation of geometric features within a given region. In this paper, we introduce a novel approach for creating anisotropic patterns of geometric features on free-form surfaces. Complex patterns are generated automatically, such that they conform to the boundary of any specified target region. Furthermore, user input of a small number of geometric features (called “seed features”) of desired size and orientation in preferred locations could be specified within the target domain. These geometric seed features are then transformed into tensors and used as boundary conditions to generate a Riemannian metric tensor field. A form of Laplace's heat equation is used to produce the field over the target domain, subject to specified boundary conditions. The field represents the anisotropic pattern of geometric features. This procedure is implemented as an add-on for a commercial CAD package to add geometric features to a target region of a three-dimensional model using two set operations: union and subtraction. This method facilitates the creation of a complex pattern of hundreds of geometric features in less than 5 min. All the features are accessible from the CAD system, and if required, they are manipulable individually by the user.

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Algorithmen-basierte Freiformflächenstrukturierung/Generation of NC programs for the micromilling structuring of free-form surfaces – Algorithm-based free-form surface structuring

wt Werkstattstechnik online ◽

10.37544/1436-4980-2021-11-12-27 ◽

2021 ◽

Vol 111 (11-12) ◽

pp. 797-802

Author(s):

Leonhard Alexander Meijer ◽

Torben Merhofe ◽

Timo Platt ◽

Dirk Biermann

Keyword(s):

Computer Aided Design ◽

Computational Effort ◽

Free Form ◽

Process Chain ◽

Surface Structuring ◽

Computer Aided ◽

Cad Cam ◽

Free Form Surface ◽

Aided Design ◽

Free Form Surfaces

In diesem Beitrag wird ein neuer Ansatz zum Erstellen von Maschinenprogrammen zur mikrofrästechnischen Oberflächenstrukturierung vorgestellt und die Anwendung der Prozesskette für ein komplexes, industrielles Verzahnungswerkzeug beschrieben. Durch die Reduzierung des Berechnungsaufwandes in der CAD/CAM (Computer-aided Design & Manufacturing)-Umgebung können die Limitierungen konventioneller Softwarelösungen umgangen und Bearbeitungsprogramme für komplexe Strukturierungsaufgaben effizient erstellt werden.   A new method for generating machine programs for micromilling surface structuring is presented, and the application of the process chain to a complex, industrial gearing die is described. By reducing the computational effort in the CAD/CAM (Computer-aided Design & Manufacturing) environment, the problems of conventional software solutions can be avoided and complex machining programs can be created.

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From 2D to 3D: Construction of a 3D Parametric Model for Detection of Dental Roots Shape and Position from a Panoramic Radiograph—A Preliminary Report

International Journal of Dentistry ◽

10.1155/2013/964631 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Laura Mazzotta ◽

Mauro Cozzani ◽

Armando Razionale ◽

Sabrina Mutinelli ◽

Attilio Castaldo ◽

...

Keyword(s):

Panoramic Radiograph ◽

Maximum Error ◽

Parametric Model ◽

Parametric Models ◽

Free Form ◽

Spline Curves ◽

Accuracy Level ◽

Root Movement ◽

Free Form Surfaces ◽

Movement Simulation

Objectives. To build a 3D parametric model to detect shape and volume of dental roots, from a panoramic radiograph (PAN) of the patient.Materials and Methods. A PAN and a cone beam computed tomography (CBCT) of a patient were acquired. For each tooth, various parameters were considered (coronal and root lengths and widths): these were measured from the CBCT and from the PAN. Measures were compared to evaluate the accuracy level of PAN measurements. By using a CAD software, parametric models of an incisor and of a molar were constructed employing B-spline curves and free-form surfaces. PAN measures of teeth 2.1 and 3.6 were assigned to the parametric models; the same two teeth were segmented from CBCT. The two models were superimposed to assess the accuracy of the parametric model.Results. PAN measures resulted to be accurate and comparable with all other measurements. From model superimposition the maximum error resulted was 1.1 mm on the incisor crown and 2 mm on the molar furcation.Conclusion. This study shows that it is possible to build a 3D parametric model starting from 2D information with a clinically valid accuracy level. This can ultimately lead to a crown-root movement simulation.

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Registration method for free-form surfaces

10.1117/12.323171 ◽

1998 ◽

Author(s):

Markus Rieder ◽

Ruediger Dillmann

Keyword(s):

Free Form ◽

Registration Method ◽

Title Registration ◽

Free Form Surfaces

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Touch probe radius compensation for coordinate measurement using kriging interpolation

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/0954405971516031 ◽

1997 ◽

Vol 211 (1) ◽

pp. 11-18 ◽

Cited By ~ 33

Author(s):

J. R. R. Mayer ◽

Y. A. Mir ◽

F Trochu ◽

A Vafaeesefat ◽

M Balazinski

Keyword(s):

Computer Aided Design ◽

Kriging Interpolation ◽

Free Form ◽

Probe Radius ◽

Part Surface ◽

Probe Radius Compensation ◽

Normal Vectors ◽

Radius Compensation ◽

Free Form Surfaces ◽

Touch Probe

Obtaining CAD (computer aided design) descriptions of actual parts having complex surfaces is a key part of the process of reverse engineering. This paper is concerned with the estimation of actual surfaces using coordinate measuring machines fitted with a spherically tipped touch probe. In particular, it addresses in detail the problem of probe radius compensation. A general mathematical model, using kriging, is proposed which first generates the initial probe centre surface and then estimates the compensated or part surface. The compensation is achieved using normal vectors to the initial probe centre surface at each measured point to compensate for the probe radius. The method is validated experimentally on known and free-form surfaces.

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Sketch-based shape exploration using multiscale free-form surface editing

Artificial intelligence for engineering design analysis and manufacturing ◽

10.1017/s0890060412000182 ◽

2012 ◽

Vol 26 (3) ◽

pp. 337-350

Author(s):

Günay Orbay ◽

Mehmet Ersın Yümer ◽

Levent Burak Kara

Keyword(s):

Computer Aided Design ◽

Free Form ◽

Levels Of Detail ◽

Solid Models ◽

Free Form Surface ◽

Conceptual Flexibility ◽

Aided Design ◽

Free Form Surfaces ◽

Surface Editing ◽

Different Levels

AbstractThe hierarchical construction of solid models with current computer-aided design systems provide little support in creating and editing free-form surfaces commonly encountered in industrial design. In this work, we propose a new design exploration method that enables sketch-based editing of free-form surface geometries where specific modifications can be applied at different levels of detail. This multilevel detail approach allows the designer to work from existing models and make alterations at coarse and fine representations of the geometry, thereby providing increased conceptual flexibility during modeling. At the heart of our approach lies a multiscale representation of the geometry obtained through a spectral analysis on the discrete free-form surface. This representation is accompanied by a sketch-based surface editing algorithm that enables edits to be made at different levels. The seamless transfer of modifications across different levels of detail facilitates a fluid exploration of the geometry by eliminating the need for a manual specification of the shape hierarchy. We demonstrate our method with several design examples.

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Boundary-conformed machining of turbine blades

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/095440505x28981 ◽

2005 ◽

Vol 219 (3) ◽

pp. 255-263 ◽

Cited By ~ 16

Author(s):

S Ding ◽

D C H Yang ◽

Z Han

Keyword(s):

Computer Aided Design ◽

Tool Path ◽

Flow Line ◽

Turbine Blades ◽

Free Form ◽

Implementation Processes ◽

Tool Marks ◽

Tool Paths ◽

Continuous Boundary ◽

Free Form Surfaces

Boundary-conformed machining is a new method to mill free-form surfaces with tool paths that reflect the natural shapes of the surfaces. It is suitable for the machining of turbine blades taking into account the direction of tool marks left on the vanes. To facilitate this type of machining, this paper introduces an application of the ‘boundary-conformed algorithm’ to generate continuous boundary-conformed flow line tool paths for the milling of blade surfaces. With this approach, the initial segment of the flow line tool paths is along the top edges of the blade while the final segment follows the intersection curves between the blade and the hub surface. The intermediate segments cover the surface by changing smoothly from the initial tool path to the final tool path. The two opposite sides of the blade, which are two trimmed surfaces, are machined together continuously from top to bottom with these continuous boundary-conformed tool paths. This method has been successfully integrated into an industrial computer-aided design and manufacture system (Pro/Engineer) by using Pro/Toolkit. A detailed algorithm and implementation processes have been introduced.

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Registration of Dental Tomographic Volume Data and Scan Surface Data Using Dynamic Segmentation

Applied Sciences ◽

10.3390/app8101762 ◽

2018 ◽

Vol 8 (10) ◽

pp. 1762 ◽

Cited By ~ 2

Author(s):

Keonhwa Jung ◽

Sukwoo Jung ◽

Inseon Hwang ◽

Taeksoo Kim ◽

Minho Chang

Keyword(s):

Computer Aided Design ◽

Automatic Segmentation ◽

Iterative Closest Point ◽

Data Sets ◽

Volume Data ◽

Metal Artifacts ◽

Registration Method ◽

Dynamic Segmentation ◽

Surface Data ◽

Edge Points

Over recent years, computer-aided design (CAD) has become widely used in the dental industry. In dental CAD applications using both volumetric computed tomography (CT) images and 3D optical scanned surface data, the two data sets need to be registered. Previous works have registered volume data and surface data by segmentation. Volume data can be converted to surface data by segmentation and the registration is achieved by the iterative closest point (ICP) method. However, the segmentation needs human input and the results of registration can be poor depending on the segmented surface. Moreover, if the volume data contains metal artifacts, the segmentation process becomes more complex since post-processing is required to remove the metal artifacts, and initially positioning the registration becomes more challenging. To overcome these limitations, we propose a modified iterative closest point (MICP) process, an automatic segmentation method for volume data and surface data. The proposed method uses a bundle of edge points detected along an intensity profile defined by points and normal of surface data. Using this dynamic segmentation, volume data becomes surface data which can be applied to the ICP method. Experimentally, MICP demonstrates fine results compared to the conventional registration method. In addition, the registration can be completed within 10 s if down sampling is applied.

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An Approach to the Low-Cost Computer Aided Manufacture of Components Embodying Free-Form Surfaces

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/pime_proc_1989_203_057_02 ◽

1989 ◽

Vol 203 (2) ◽

pp. 119-126 ◽

Cited By ~ 1

Author(s):

X Gao ◽

D K Harrison ◽

B J Davies

Keyword(s):

Computer Aided Design ◽

Numerical Control ◽

Personal Computers ◽

Surface Patch ◽

Free Form ◽

Height Determination ◽

Computer Aided ◽

Cusp Height ◽

Five Axis ◽

Free Form Surfaces

The numerical control (NC) machining of free-form surfaces is usually accomplished utilizing minicomputer or mainframe computer aided design and manufacturing (C ADC AM) systems. The resulting NC data are suitable for either three-axis or five-axis machining dependent upon machine tool type/capability and CAM package complexity. However, the cost of such packages and systems precludes the use of these in smaller companies with an occasional requirement for components embodying free-form surfaces. The increasing availability of powerful yet reasonably priced personal computers (PC) coupled with improving software provides such companies with a far cheaper alternative approach. However, a common feature of PC-based CADCAM systems is that they are limited to 2 1/2-axis machining for all but special applications such as three-axis canted Z-plane milling of four-axis wire electro discharge machining (EDM). This paper presents a method for manufacturing true three-dimensional free-form surfaces using PC-based 2 1/2-axis CADCAM systems. All the main functions performed on mainframe systems can be performed on personal computers, such as toolpath generation for free-form surfaces, cusp height determination and change in shape and volume which may be used for the compensation of shrinkage or to suit market requirements. This is significant for manufacturers who make use of moulds, such as are found in the plastic processing industries. The manufacture of a blown plastic bottle mould is presented as a typical example. The inclusion into the PC environment of features to be found in mainframe systems is also discussed, such as machining the surface patch by patch in any direction or machining a number of patches at one time, shape and volume change in any direction, cusp height determination, etc.

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