Toolpath generation for freeform surface models

1994 ◽  
Vol 26 (6) ◽  
pp. 490-496 ◽  
Author(s):  
Gershon Elber ◽  
Elaine Cohen
Keyword(s):  
Freeform Surface ◽  
Toolpath Generation ◽  
Surface Models

Networked Haptic Interfaces for Distant Redesign and Review of Free-Form Surfaces

1997 ◽  
Author(s):  
Satoshi Kanai ◽  
Hidetomo Takahashi ◽  
Takeshi Kishinami
Keyword(s):  
Work Flow ◽  
Haptic Interface ◽  
Freeform Surface ◽  
Free Form ◽  
Surface Model ◽  
Haptic Interfaces ◽  
Long Distance ◽  
Surface Models ◽  
Free Form Surfaces ◽  
Network Software

Abstract The review and redesign of a freeform surface model, a process known as approval, is the final and indispensable stage in advancing a model from style designer to die manufacturer. This paper proposes a collaborative system for the review, redesign, and exchange of data on freeform surface models over a network, with the goal of improving the efficiency of the approval process among distant sites. First we analyze the work-flow of the long-distance approval. Then, in order to eliminate the physical model, we present a 3DOF haptic interface (force display) that accurately renders the feel of the freeform surface in great detail. Finally, we describe the architecture of the intra-network software that manages each step of the approval while maintaining consistency between the numerous versions of the surface models. The experimental results of a 3DOF communication between Tokyo and Sapporo and the subsequent review and redesign of the system are also shown.

scholarly journals T-Spline Surface Toolpath Generation Using Watershed-Based Feature Recognition

2020 ◽  
Vol 10 (19) ◽  
pp. 6790
Author(s):  
Yazui Liu ◽  
Gang Zhao ◽  
Pengfei Han
Keyword(s):  
Feature Recognition ◽  
Machining Process ◽  
Freeform Surface ◽  
Local Refinement ◽  
Surface Machining ◽  
Spline Surface ◽  
Toolpath Generation ◽  
Comparison Results ◽  
Bounding Boxes ◽  
Freeform Surface Machining

The freeform surface is treated as a single machining region for most traditional toolpath generation algorithms. However, due to the complexity of a freeform surface, it is impossible to produce a high-quality surface using one unique machining process. Hence, region-based methods are widely investigated for freeform surface machining to achieve an optimized toolpath. The Non-Uniform Rational B-spline Surface (NURBS) represented freeform surface is not suitable for region-based toolpath generation because of the surface gaps caused by NURBS trimming and merging operations. To solve the limitation of the NURBS, T-spline is proposed with the advantages of being gap-free, having less control points, and local refinement, which is an ideal tool for region-based toolpath generation. Thus, T-spline is introduced to represent a freeform surface for its toolpath generation in the paper. A region-based toolpath generation method for the T-spline surface is proposed based on watershed technology. Firstly, watershed-based feature recognition is presented to divide the T-spline surface into a set of sub-regions. Secondly, the concept of a PolyBoundingBox that consists of a set of minimum bounding boxes is proposed to describe the sub-regions, and Manufacturing-Suitable Regions are constructed with the help of T-spline local refinement and the PolyBoundingBox. In the end, an optimized multi-rectangles toolpath generation algorithm is applied for sub-regions. The proposed method is tested using three synthetic T-spline surfaces, and the comparison results show the advantage in toolpath length and toolpath reversing number.

Feature Simplification Techniques for Freeform Surface Models

2003 ◽  
Vol 3 (3) ◽  
pp. 177-186 ◽  
Author(s):  
Nikhil Joshi ◽  
Debasish Dutta
Keyword(s):  
Poor Quality ◽  
Freeform Surface ◽  
Surface Model ◽  
Complete Suppression ◽  
Body Parts ◽  
Automobile Body ◽  
Surface Models ◽  
Basic Features ◽  
Simplification Techniques ◽  
Manual Correction

Freeform surface models are conventionally used to model sheet metal components, such as automobile body parts. Finite element meshes generated automatically for such models have poor quality around small detailed features. Manual correction of the mesh is extremely tedious. An approach presently receiving attention in industry aims to alleviate this problem by automatically simplifying these features in the surface model such that an acceptable mesh is automatically generated. Simplification involves recognition of the feature and modification of its geometry or complete suppression of the feature. Since features such as holes, notches, etc. are punched after the basic shape has been formed, such a simplification will also help in the modelling of forming dies and molds. The ability to detect features will also allow part comparison and classification in surface models. This paper proposes techniques to directly query the CAD data structure to recognize and suppress two basic features, viz. holes and fillets in freeform surface models. It further demonstrates how these techniques can be extended to suppress compound features that are composed of a combination of basic features. Results of a software implementation for the same are discussed with suitable examples and the improvement in mesh quality is demonstrated.

Feature Simplification in Surface Models for Efficient Finite Element Mesh Generation

2002 ◽  
Author(s):  
Nikhil Joshi ◽  
Debasish Dutta
Keyword(s):  
Finite Element ◽  
Mesh Generation ◽  
Poor Quality ◽  
Mesh Simplification ◽  
Software Implementation ◽  
Freeform Surface ◽  
Complete Suppression ◽  
Element Mesh ◽  
Surface Models ◽  
Basic Features

Sheet metal components are typically modelled as freeform surface models. Finite element meshes generated automatically for such models have poor quality around small detailed features. These features need to be simplified in order to obtain an acceptable mesh. Simplification involves recognition of the feature and modification of its geometry or complete suppression of the feature. This paper proposes techniques to directly query the CAD data structure to recognise and suppress two basic features, viz. holes and fillets in freeform surface models. Results of a software implementation for the same are discussed with suitable examples.

Voxel-Based Adaptive Toolpath Planning using GPU for Freeform Surface Machining

2021 ◽  
pp. 1-31
Author(s):  
Aman Kukreja ◽  
Mandeep Dhanda ◽  
Sanjay Pande
Keyword(s):  
Tool Path ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Freeform Surface ◽  
Processing Unit ◽  
Cad Model ◽  
Cnc Machine ◽  
Toolpath Planning ◽  
Toolpath Generation ◽  
Freeform Surface Machining

Abstract Today freeform surfaces are widely used on products in automobile, aerospace, and die/molds industries, which are generally manufactured using multi-axis CNC machines. Frequent changes in the design of products necessitate creation of CNC part programs which need fast and accurate toolpath generation methods. Traditional toolpath generation methods involve complex computations and are unable to consider multiple surface patches together. The voxel-based CAD model provides the ability to represent the multi-patch surfaces in a discretized manner which can be processed using an advanced parallel computing framework for accurate tool path planning. This paper presents a new method to generate an adaptive Iso-planar toolpath for a 3-axis CNC machine using the voxel-based part model. The algorithm is designed to work on a Graphics Processing Unit (GPU) that allows parallel processing for faster toolpath generation. The proposed approach consists of two main steps, an algorithm to generate gouge free cutter location points from the voxel-based CAD model and an algorithm to find out sidestep and forward step from those cutter location points to create the final CNC tool path. A new image-processing technique has been proposed to identify gouge by detecting the shadow surface voxels and their intersection with the cutting tool. The developed system was extensively tested and compared with the various reported toolpath planning strategies for machining complex freeform surface parts. The results show that the developed method is computationally efficient, robust, and accurate in generating adaptive planar toolpath.

Elemental chlorine-free bleaching of North American hardwood kraft pulps: Evaluation of oxidant-reinforced extraction variables on overall bleaching optimization

TAPPI Journal ◽  
2013 ◽  
Vol 12 (10) ◽  
pp. 33-41 ◽  
Author(s):  
BRIAN N. BROGDON
Keyword(s):  
Response Surface ◽  
Chlorine Dioxide ◽  
North American ◽  
Yield Loss ◽  
Alkaline Extraction ◽  
Kraft Pulps ◽  
Pulp Bleaching ◽  
Response Surface Models ◽  
Elemental Chlorine ◽  
Surface Models

This investigation evaluates how higher reaction temperatures or oxidant reinforcement of caustic extraction affects chlorine dioxide consumption during elemental chlorine-free bleaching of North American hardwood pulps. Bleaching data from the published literature were used to develop statistical response surface models for chlorine dioxide delignification and brightening sequences for a variety of hardwood pulps. The effects of higher (EO) temperature and of peroxide reinforcement were estimated from observations reported in the literature. The addition of peroxide to an (EO) stage roughly displaces 0.6 to 1.2 kg chlorine dioxide per kilogram peroxide used in elemental chlorine-free (ECF) bleach sequences. Increasing the (EO) temperature by Δ20°C (e.g., 70°C to 90°C) lowers the overall chlorine dioxide demand by 0.4 to 1.5 kg. Unlike what is observed for ECF softwood bleaching, the presented findings suggest that hot oxidant-reinforced extraction stages result in somewhat higher bleaching costs when compared to milder alkaline extraction stages for hardwoods. The substitution of an (EOP) in place of (EO) resulted in small changes to the overall bleaching cost. The models employed in this study did not take into account pulp bleaching shrinkage (yield loss), to simplify the calculations.

Data post processing

2018 ◽  
Author(s):  
Serge A. Wich ◽  
Lian Pin Koh
Keyword(s):  
Land Cover ◽  
Structure From Motion ◽  
Land Cover Classification ◽  
Post Processing ◽  
Surface Models

This chapter discusses how data that have been collected with drones can be used to derive orthomosaics and digital surface models through structure-from-motion software and how these can be processed further for land-cover classification or into vegetation metrics. Some examples of the various programs are provided as well. The chapter ends with a discussion on the approaches that have been used to automate counts of animals in drone images.

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