Multiple-Points Constraints Based Deformation for Free-Form Surfaces

1999 ◽  
Author(s):  
J. M. Zheng ◽  
K. W. Chan ◽  
I. Gibson
Keyword(s):  
Surface Deformation ◽  
Single Point ◽  
Displacement Function ◽  
Surface Shape ◽  
Free Form ◽  
Surface Model ◽  
Deformation Method ◽  
Multiple Points ◽  
Free Form Surface ◽  
Free Form Surfaces

Abstract There is an increasing demand in the conceptual design for more intuitive methods for creating and modifying free-form curves and surfaces in CAD modeling systems. The methods should be based not only on the change of the mathematical parameters but also on the user’s specified constraints and shapes. This paper presents a new surface representation model for free-form surface deformation representation. The model is a combination of two functions: a displacement function and a function for representing an existing NURBS surface called parent surface. Based on the surface model, the authors develop two deformation methods which are named SingleDef (Single-point constraint based deformation method), and MultiDef (Multiple-points constraints based deformation method). The techniques for free-form surface deformation allow conceptual designer to modify a parent surface by directly applying point constraints to the parent surface. The deformation methods are implemented and taken in an experimental CAD system. The results show that the designer can easily and intuitively control the surface shape.

scholarly journals Reverse Engineering of Free-Form Surface Based on the Closed-Loop Theory

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Xue Ming He ◽  
Jun Fei He ◽  
Mei Ping Wu ◽  
Rong Zhang ◽  
Xiao Gang Ji
Keyword(s):  
Reverse Engineering ◽  
Point Cloud ◽  
Closed Loop ◽  
Free Form ◽  
Surface Model ◽  
Accurate Model ◽  
Check Points ◽  
Adaptive Measurement ◽  
Free Form Surface ◽  
Free Form Surfaces

To seek better methods of measurement and more accurate model of reconstruction in the field of reverse engineering has been the focus of researchers. Based on this, a new method of adaptive measurement, real-time reconstruction, and online evaluation of free-form surface was presented in this paper. The coordinates and vectors of the prediction points are calculated according to a Bézier curve which is fitted by measured points. Final measured point cloud distribution is in agreement with the geometric characteristics of the free-form surfaces. Fitting the point cloud to a surface model by the nonuniform B-spline method, extracting some check points from the surface models based on grids and a feature on the surface, review the location of these check points on the surface with CMM and evaluate the model, and then update the surface model to meet the accuracy. Integrated measurement, reconstruction, and evaluation, with the closed-loop reverse process, established an accurate model. The results of example show that the measuring points are distributed over the surface according to curvature, and the reconstruction model can be completely expressed with micron level. Meanwhile, measurement, reconstruction and evaluation are integrated in forms of closed-loop reverse system.

Fully Free-Form Deformation Features (δ-F4) Incorporating Discontinuities

2004 ◽  
Author(s):  
Vincent Cheutet ◽  
Jean-Philippe Pernot ◽  
Jean-Claude Leon ◽  
Bianca Falcidieno ◽  
Franca Giannini
Keyword(s):  
Surface Deformation ◽  
Geometric Constraints ◽  
Free Form ◽  
Initial Surface ◽  
Cad Systems ◽  
Free Form Deformation ◽  
Deformation Features ◽  
Generate Surface ◽  
Prototype Software ◽  
Free Form Surfaces

To limit low-level manipulations of free-form surfaces, the concept of Fully Free Form Deformation Features (δ-F4) have been introduced. They correspond to shapes obtained by deformation of a surface area according to specified geometric constraints. In our work, we mainly focused on those features aimed at enforcing the visual effect of the so-called character lines, extensively used by designers to specify the shape of an object. Therefore, in the proposed approach, 3D lines are used to drive surface deformation over specified areas. Depending on the wished shape and reflection light effects, the insertion of character lines may generate surface tangency discontinuities. In CAD systems, such kind of discontinuities is generally created by a decomposition of the initial surface into several patches. This process can be tedious and very complex, depending on the shape of the deformation area and the desired surface continuity. Here, a method is proposed to create discontinuities on a surface, using the trimming properties of surfaces. The corresponding deformation features produce the resulting surface in a single modification step and handle simultaneously more constraints than current CAD systems. The principle of the proposed approach is based on arbitrary shaped discontinuities in the parameter domain of the surface to allow the surface exhibiting geometric discontinuities at user-prescribed points or along lines. The proposed approach is illustrated with examples obtained using our prototype software.

Application of Convex Hull for Tool Interference Avoidance in 5-Axis CNC Machining

1996 ◽  
Author(s):  
Yuan-Shin Lee ◽  
Tien-Chien Chang
Keyword(s):  
Convex Hull ◽  
Tool Path ◽  
Correction Method ◽  
Nc Machining ◽  
Cnc Machining ◽  
Free Form ◽  
Interference Avoidance ◽  
Tool Interference ◽  
Free Form Surface ◽  
Free Form Surfaces

Abstract In this paper, a methodology of applying convex hull property in solving the tool interference problem is presented for 5-axis NC machining of free-form surfaces. Instead of exhausted point-by-point checking for possible tool interference, a quick checking can be done by using the convex hull constructed from the control polygon of free-form surface modeling. Global tool interference in 5-axis NC machining is detected using the convex hull of the free-form surface. A correction method for removing tool interference has also been developed to generate correct tool path for 5-axis NC machining. The inter-surface tool interference can be avoided by using the developed technique.

Creation and Manipulation of Complex Displacement Features During the Conceptual Phase of Design

1996 ◽  
Author(s):  
P. A. van Elsas ◽  
J. S. M. Vergeest
Keyword(s):  
Boundary Conditions ◽  
Surface Feature ◽  
Free Form ◽  
Shape Design ◽  
Surface Model ◽  
Test Results ◽  
Base Surface ◽  
Feature Design ◽  
Data Explosion ◽  
Free Form Surface

Abstract Surface feature design is not well supported by contemporary free form surface modelers. For one type of surface feature, the displacement feature, it is shown that intuitive controls can be defined for its design. A method is described that, given a surface model, allows a designer to create and manipulate displacement features. The method uses numerically stable calculations, and feedback can be obtained within tenths of a second, allowing the designer to employ the different controls with unprecedented flexibility. The algorithm does not use refinement techniques, that generally lead to data explosion. The transition geometry, connecting a base surface to a displaced region, is found explicitly. Cross-boundary smoothness is dealt with automatically, leaving the designer to concentrate on the design, instead of having to deal with mathematical boundary conditions. Early test results indicate that interactive support is possible, thus making this a useful tool for conceptual shape design.

Research on Digital Modeling about Free-Form Surface with Holes Based on Coordinate Measuring Machine

2011 ◽  
Vol 287-290 ◽  
pp. 2805-2809
Author(s):  
Ming Yu Huang ◽  
Xiu Juan Wu ◽  
Zhong Shi Jia ◽  
Hong Jun Ni ◽  
Jing Jing Lv ◽  
...  
Keyword(s):  
Point Cloud ◽  
Coordinate Measuring Machine ◽  
Free Form ◽  
Model Reconstruction ◽  
Contact Measurement ◽  
Digital Modeling ◽  
Measuring Machine ◽  
Fast Reconstruction ◽  
Free Form Surface ◽  
Free Form Surfaces

Data acquisition and model reconstruction of free-form surfaces with holes were been studied, based on coordinate measuring machines. First, the structural process of the parts was analyzed, the method of combinate contact measurement with non-contact measurement were used to get point cloud; Then the point cloud were been preprocessed, feature curve extracted and solid modeled; Finally, the restructure model was been quality assessed and accuracy assessed. Using the measurement of combinated contact and non-contact can also meet both the precision requirement of key part and the fast reconstruction requirement of non-critical part, which has great significance on that part to fast and accurate reconstruction.

Path Planning For Robotic Polishing of Sheet Metal Parts

2021 ◽  
Author(s):  
Yuezhi (Sean) Liu ◽  
Fengfeng (Jeff) Xi ◽  
Reza Faieghi
Keyword(s):  
Path Planning ◽  
Sheet Metal ◽  
Contact Force ◽  
Optimal Path ◽  
Surface Shape ◽  
Free Form ◽  
Metal Parts ◽  
Contact Areas ◽  
Sheet Metal Parts ◽  
Free Form Surface

Abstract Unlike solid parts, the deformation caused by a contact force during robotic polishing of sheet metal parts has become an issue. In this paper, a path planning method is purposed to resolve this issue. This method includes three steps. The first step is to apply the Hertz theory to compute the contact areas between the tool head and the free-form surface of a sheet metal part. The second step is to apply the finite element method to compute the deformation under a contact force. The third step is to reconstruct the deformed free-form surface and modify the contact areas accordingly. The underlying problem is dynamic because the deformed surface shape changes as the tool head moves along a tool path. Based on the proposed method, an optimal path can be determined to achieve full coverage of the entire surface without over or under polishing.

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

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.

Parting Line Formation by Slicing a Trimmed Surface Model

1996 ◽  
Author(s):  
T. Wong ◽  
S. T. Tan ◽  
W. S. Sze
Keyword(s):  
Product Design ◽  
Free Form ◽  
Surface Model ◽  
Curved Surfaces ◽  
Line Formation ◽  
Planar Surfaces ◽  
Manufacturing Efficiency ◽  
Computer Aided ◽  
Trimmed Surface ◽  
Free Form Surfaces

Abstract The parting line on a product affects the final layout of the mould blocks and hence the manufacturing efficiency. The increased usage of free-form surfaces in product design increases the burden of computer aided parting line and parting surface determination. Previous proposed algorithms may not be sufficient to deal with such situation since most of them were originally designed to deal with products having planar surfaces or simple curved surfaces. A new algorithm is proposed to deal with such situation. The algorithm adopted a recursive uneven slicing on a trimmed surface model. The method provides a quick and efficient way of locating the parting line of a product.

A Shape Modeling System with a Volume Scanning Display and Multisensory Input Device

1993 ◽  
Vol 2 (2) ◽  
pp. 104-111 ◽  
Author(s):  
Ken-ichi Kameyama ◽  
Koichi Ohtomi
Keyword(s):  
Virtual Reality ◽  
Shape Modeling ◽  
Free Form ◽  
Input Device ◽  
Surface Image ◽  
Free Form Surface ◽  
Multisensory Input ◽  
Free Form Surfaces ◽  
As If

This paper describes a newly developed 3-D shape modeling system, in which a user can design a free-form surface as if he or she actually manipulates a flexible object made from rubber or clay. Such reality can be realized in the system without any encumbering devices like goggles, glasses, or gloves, which is impossible in conventional virtual reality systems. The system is composed of a volume scanning display for presenting a surface image in a real 3-D space, a multisensory input device for detecting the force for deformation, and a half-silvered mirror for spatial superposition of the image onto the input device. A user can directly manipulate a free-form surface by virtually pushing the image, actually pushing the input device, and at the same time, he or she can feel the input device resist its actual deformation as the resisting force of the virtual surface. The system has several types of deforming models, and two types of free-form surfaces that have different curvatures have been experimentally created.

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