Automatic Detection of Directions of Dimensional Control in Mechanical Parts

2014 ◽  
Author(s):  
Prashant Mohan ◽  
Payam Haghighi ◽  
Jami J. Shah ◽  
Joseph K. Davidson
Keyword(s):  
Linear Chain ◽  
Tolerance Analysis ◽  
Relative Orientation ◽  
Graphical Form ◽  
Computer Assisted ◽  
Dimensional Control ◽  
Mechanical Parts ◽  
Geometric Tolerancing ◽  
Feature List ◽  
Cad Models

This research is part of a larger project which aims at developing a tool to help designers create effective GD&T schemas. The first step towards this goal is to determine the particular directions in which dimensions and tolerances need to be controlled. These directions we label here as “Directions of (Dimensional) Control” or DoC for short. Regardless of whether one uses chain dimensioning, reference dimensioning or geometric tolerancing, all size and basic dimensions of position line up in a finite number of directions or Directions of Control. This paper presents an approach for automatically identifying the directions of control from CAD models of mechanical parts. The only input to the system is the geometry of parts or assemblies in STEP file format. The analysis is done part by part for an assembly. First, planar and cylindrical features are recognized and their normal/axes extracted. The extracted features are then organized into groups of parallel normal or axes directions. Cylindrical features can belong to two or more Directions of Control, while planar features belong can only belong to one. Features in each DoC are then ordered based on perpendicular relative distances. Each ordered feature list forms a linear chain in which nodes represent features and links are attributed with relative distance to the nearest neighbors on each side. DoC chains are related to each other by relative orientation. Therefore, the chains are combined into a unified graph, using the junction nodes to contain the relative orientation between the chains. The extracted Directions of Control can be output in both textual and graphical form. Although the primary motivation for automatic DoC graph generation is computer assisted tolerancing and automatic tolerance analysis, the paper also discusses other applications in manufacturing.

User-Driven Computer-Assisted Reverse Engineering of Editable CAD Assembly Models

2021 ◽  
pp. 1-16
Author(s):  
Ghazanfar Ali Shah ◽  
Jean-Philippe Pernot ◽  
Arnaud Polette ◽  
Franca Giannini ◽  
Marina Monti
Keyword(s):  
Reverse Engineering ◽  
Point Cloud ◽  
Point Clouds ◽  
Geometric Constraints ◽  
Computer Assisted ◽  
Reconstruction Process ◽  
Mechanical Parts ◽  
Starting Point ◽  
Cad Models ◽  
Incomplete Datasets

Abstract This paper introduces a novel reverse engineering technique for the reconstruction of editable CAD models of mechanical parts' assemblies. The input is a point cloud of a mechanical parts' assembly that has been acquired as a whole, i.e. without disassembling it prior to its digitization. The proposed framework allows for the reconstruction of the parametric CAD assembly model through a multi-step reconstruction and fitting approach. It is modular and it supports various exploitation scenarios depending on the available data and starting point. It also handles incomplete datasets. The reconstruction process starts from roughly sketched and parameterized geometries (i.e 2D sketches, 3D parts or assemblies) that are then used as input of a simulated annealing-based fitting algorithm, which minimizes the deviation between the point cloud and the reconstructed geometries. The coherence of the CAD models is maintained by a CAD modeler that performs the updates and satisfies the geometric constraints as the fitting process goes on. The optimization process leverages a two-level filtering technique able to capture and manage the boundaries of the geometries inside the overall point cloud in order to allow for local fitting and interfaces detection. It is a user-driven approach where the user decides what are the most suitable steps and sequence to operate. It has been tested and validated on both real scanned point clouds and as-scanned virtually generated point clouds incorporating several artifacts that would appear with real acquisition devices.

Reverse Engineering of Mechanical Parts: A Brief Overview of Existing Approaches and Possible New Strategies

2016 ◽  
Author(s):  
Francesco Buonamici ◽  
Monica Carfagni
Keyword(s):  
Reverse Engineering ◽  
A Priori ◽  
Reconstruction Process ◽  
Mechanical Parts ◽  
Cad System ◽  
Software Packages ◽  
Geometrical Constraints ◽  
Cad Models ◽  
Data Points ◽  
New Strategies

Reverse Engineering (RE), also known as “CAD reconstruction”, aims at the reconstruction of 3D geometric models of objects/mechanical parts, starting from 3D measured data (points/mesh). In recent years, considerable developments in RE were achieved thanks to both academic and industrial research (e.g. RE software packages). The aim of this work is to provide an overview of state of the art techniques and approaches presented in recent years (considering at the same time tools and methods provided by commercial CAD software and RE systems). In particular, this article focuses on the “constrained fitting” approach, which considers geometrical constraints between the generated surfaces, improving the reconstruction result. On the basis of the overview, possible theoretical principles are drafted with the aim of suggest new strategies to make the CAD reconstruction process more effective in order to obtain more ready/usable CAD models. Finally, a new RE framework is briefly outlined: the proposed approach hypothesizes a tool built within the environment of an existing CAD system and considers the fitting of a custom-built archetypal model, defined with all the a-priori known dimensions and constraints, to the scanned data.

Partial Matching Algorithm of 3D CAD Models Based on the Constraints of Transition Features

2010 ◽  
Vol 97-101 ◽  
pp. 3371-3375
Author(s):  
Kai Xing Zhang ◽  
Shu Sheng Zhang ◽  
Xiao Liang Bai
Keyword(s):  
Feature Recognition ◽  
Graph Isomorphism ◽  
Topological Information ◽  
Machining Features ◽  
New Approach ◽  
Partial Matching ◽  
Mechanical Parts ◽  
3D Cad ◽  
Matching Efficiency ◽  
Cad Models

The CAD models of mechanical parts usually have many blends and chamfers, and the existence of these machining features can greatly change the geometric and topological patterns of the CAD models, but the existing partial matching algorithms cannot match the CAD models which contain machining features such as blends and chamfers. In this paper, a new approach to partial matching based on the constraints of transition features is proposed. Firstly, the transition features are identified by feature recognition, and then these machining features are removed to eliminate the impacts to the geometric and topological information of the CAD models, and the attribute adjacent graph is reconstructed, finally, the sub-graph isomorphism approach is used to achieve the partial matching. Experimental results show that this method can achieve partial matching of CAD models which contain machining features such as blends and chamfers, and the matching efficiency can satisfy the requirement of the engineering retrieval.

Combining Strings and Fibers With Additive Manufacturing Designs

2016 ◽  
Author(s):  
C. J. Kimmer ◽  
C. K. Harnett
Keyword(s):  
Tensile Strength ◽  
Additive Manufacturing ◽  
Traditional Approach ◽  
Water Soluble ◽  
Circuit Board ◽  
Process Time ◽  
Computer Assisted ◽  
Manual Labor ◽  
High Tensile Strength ◽  
Mechanical Parts

High tensile strength cables, low-resistance motor windings, and shape memory actuators are common examples of technical fibers used in robots and other electromechanical assemblies. Because properties like tensile strength, crystal structure, and polymer alignment depend strongly on processing history, these materials cannot be 3D printed with the same properties they have on the spool. Strings and fibers are inserted in mechanical parts at the end of the manufacturing process for these assemblies. When the fibers take complex paths, the installation is often done by hand. This activity can dominate the process time, increase its human labor and reduce its social sustainability [1]. This paper applies the non-traditional approach of machine embroidery to insert sheets of patterned fibers in layered additive manufacturing processes such as 3D printing and lamination. Fibers are aligned with features in laser-cut or printed parts without the manual labor of hand threading. We demonstrate that water-soluble stabilizer materials originally designed for textiles can hold hard mechanical parts in a machine embroidery hoop with enough strength and rigidity to withstand sewing through pre-existing holes in the part. Alignment to within 250 microns has been demonstrated with a sub-$300 consumer embroidery machine. Case studies in this paper include a cable-driven mechanism, a soft-to-hard electronic connection, and an electromechanical sensor. Process-compatible and commercially available materials that can be embroidered include conductive threads, shrinking threads, water-soluble threads and high tensile strength fibers. The biggest hurdle for a user interested in this automated fiber installation process is linking the existing design file with an embroidery machine file. There is a much larger user base for 2D and 3D computer-assisted design (CAD) software than for expensive and proprietary embroidery digitizing software. We take the route chosen by the laser cutter industry, where the user produces a CAD file in their preferred editor, and makes annotations that communicate where and how densely to stitch. Translation software scans the file for a particular line style and generates stitch coordinates along it. Development is done in Jupyter/iPython notebooks that allow end-users to inspect, understand, and modify the conversion code. The intent is for users of existing planar fabrication technology (whether laser, printed circuit board, or micro/nano) to apply this method to their own CAD files for a versatile and straightforward way to put advanced materials in their devices without adding manual labor. This general approach can solve a class of assembly problems relevant to underactuated tendon-driven robotics and other electromechanical systems, expanding the range of devices that can be put together using automation.

scholarly journals Application of process mapping for digitization of mechanical parts with 3D laser scanner

2018 ◽  
Vol 9 ◽  
pp. 11 ◽  
Author(s):  
Antonio Piratelli-Filho ◽  
Alberto José Alvares ◽  
Rosenda Valdés Arencibia
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Mapping Method ◽  
Free Form ◽  
Process Mapping ◽  
Mechanical Parts ◽  
Cad Models ◽  
Measurement Planning ◽  
Aided Design

This work presents a systematization method for digitization of mechanical parts with three-dimensional (3D) laser scanner using the process mapping method. The application involves the use of the IDEFØ methodology of process mapping to address the sequence of steps required to obtain the computer-aided design (CAD) model of the measured part. The variables involved in the setup and measurement with 3D laser scanner were investigated and applied to regular and free-form parts, and the parameter geometry, texture, light reflection and procedure of data acquisition were considered in the analysis. The software commands used to create the CAD models were also included and the ones related to mesh and surface creation were detailed. The systematized measurement planning was graphi graphically presented, and it proved useful to operators during the digitization process.

scholarly journals Tolerance Analysis of Mechanical Parts

2020 ◽  
Vol 14 (3) ◽  
pp. 265-272
Author(s):  
Živko Kondić ◽  
Đuro Tunjić ◽  
Leon Maglić ◽  
Amalija Horvatić Novak
Keyword(s):  
Tolerance Analysis ◽  
Case Method ◽  
Worst Case ◽  
Mechanical Parts ◽  
Assembly Tolerance ◽  
Huge Impact ◽  
Quality Of Products ◽  
The One

The determination of tolerances has a huge impact on the price and quality of products. The objective of tolerance analysis is to provide the widest possible tolerance range of parts, without disturbing the functionality of the assembly. Tolerance analysis should be performed during the design process because then there is still the possibility for change. For the purpose of carrying out the analysis, three methods will be used: Worst Case method, Root Sum Square method and Monte Carlo Simulation. Methods are explained through simple examples and applied on the one-way clutch.

Development of an AutoCAD-Based Geometric Tolerancing System

1997 ◽  
Author(s):  
Jhy-Cherng Tsai ◽  
Jing-Sheng Chang
Keyword(s):  
Functional Performance ◽  
Tolerance Analysis ◽  
Manufacturing Cost ◽  
Geometric Dimensioning And Tolerancing ◽  
Geometric Tolerancing ◽  
Interactive Interface ◽  
Dimensioning And Tolerancing ◽  
Frame Transformation ◽  
Tolerance Assignment ◽  
Type Classification

Abstract Geometric tolerancing is an important factor affecting the functional performance and manufacturing cost of a product. Tolerancing specifications have to be assigned with care at design time to reduce the gap between design and manufacturing. This paper describes a system that simplifies tolerancing assignment and uses dimensioning and tolerancing data for related applications. The system consists of five modules for feature type classification, tolerance assignment, tolerance network construction, frame transformation, and tolerance analysis interface. It provides an interactive interface for tolerance assignment based on geometric features that a designer can select from decomposed isometric drawing. The system also recognizes the type of a feature so that only appropriate tolerancing specifications can be assigned. Geometric dimensioning and tolerancing data are used to construct a network for representing the tolerancing and mating relationship among features. The network is then converted for tolerance analysis via a tolerance analysis interface.

scholarly journals Integrating Multiple Engineering Resources in a Virtual Environment for Reverse Engineering Legacy Mechanical Parts

2005 ◽  
Author(s):  
Suraj R. Musuvathy ◽  
David E. Johnson ◽  
H. James de St. Germain ◽  
Elaine Cohen ◽  
Chimiao Xu ◽  
...  
Keyword(s):  
Reverse Engineering ◽  
Domain Knowledge ◽  
Engineering Process ◽  
Sources Of Information ◽  
New Approach ◽  
Mechanical Parts ◽  
Reverse Engineer ◽  
Time Restrictions ◽  
Cad Models ◽  
Processing Information

Reverse engineering is a time-consuming and technically formidable process that is increasingly becoming an economic imperative due to replacement costs. The Multiple Engineering Resources aGent Environment (MERGE) system, introduced in this paper, is a new approach toward reverse engineering whose architecture and modules are driven specifically by the requirements of legacy engineering. Legacy engineering scenarios presume availability of multiple (possibly incomplete or inconsistent) sources of information, lack of digital descriptions of the parts, constrained time restrictions and need for significant domain knowledge expertise. The reverse engineering process must yield modern CAD models capable of driving state-of-the art CAM processes. The MERGE system aims at making the reverse engineering process more effective, using both intuitive interaction and visualization as key components, by enabling quick identification and resolution of inconsistencies among various resources in a unified environment. The MERGE system also aims at simplifying the reverse engineering process by integrating various computational agents to assist the reverse engineer in processing information and in creating the desired CAD models.

Tolerance-based Variations in Solid Modeling

2003 ◽  
Vol 3 (4) ◽  
pp. 345-352 ◽  
Author(s):  
G. Moroni ◽  
W. Polini
Keyword(s):  
Tolerance Analysis ◽  
Design Stage ◽  
Tolerance Design ◽  
Functional Requirements ◽  
Mechanical Parts ◽  
Assembly Tolerance ◽  
Geometric Tolerances ◽  
Design Requirements ◽  
Optimal Values ◽  
Definition Of

Information on tolerances and attributes of mechanical parts and assemblies is crucial for many activities in a product’s life cycle. Tolerance design is a complex task because many factors (functional, technological and economical) should be considered. It is an iterative process, starting from a first tolerances assignment and ending with the definition of their optimal values. Once all tolerances have been assigned to each part of an assembly, tolerance analysis is performed. This stage aim is to evaluate if the combined effects of the assigned tolerances let the design requirements be met. Then, feasible and economical aspects are considered on the basis of both available processes and cost evaluations. The whole tolerance design stage is usually defined as tolerance synthesis. The focus of this work is the discussion of the algorithms to model the geometrical variations, of each part of an assembly, allowed by geometric tolerances. This involves the change of the boundary nominal representation of a part face on the basis of the assigned dimensional and geometric tolerances. At present, the developed algorithms are able to simulate flatness, location and orientation. The modified parts, generated by tolerance simulation, may be used to evaluate the overall assemblability and, then, to verify the assembly functional requirements.

scholarly journals Plant data visualisation using network graphs

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5579
Author(s):  
Afrina Adlyna Mohamad-Matrol ◽  
Siow-Wee Chang ◽  
Arpah Abu
Keyword(s):  
Morphological Characteristics ◽  
Graph Model ◽  
Graphical Form ◽  
Computer Assisted ◽  
Data Visualisation ◽  
Model Data ◽  
Network Graph ◽  
Novice Users ◽  
Plant Data ◽  
Meaningful Relationships

BackgroundThe amount of plant data such as taxonomical classification, morphological characteristics, ecological attributes and geological distribution in textual and image forms has increased rapidly due to emerging research and technologies. Therefore, it is crucial for experts as well as the public to discern meaningful relationships from this vast amount of data using appropriate methods. The data are often presented in lengthy texts and tables, which make gaining new insights difficult. The study proposes a visual-based representation to display data to users in a meaningful way. This method emphasises the relationships between different data sets.MethodThis study involves four main steps which translate text-based results from Extensible Markup Language (XML) serialisation format into graphs. The four steps include: (1) conversion of ontological dataset as graph model data; (2) query from graph model data; (3) transformation of text-based results in XML serialisation format into a graphical form; and (4) display of results to the user via a graphical user interface (GUI). Ontological data for plants and samples of trees and shrubs were used as the dataset to demonstrate how plant-based data could be integrated into the proposed data visualisation.ResultsA visualisation system named plant visualisation system was developed. This system provides a GUI that enables users to perform the query process, as well as a graphical viewer to display the results of the query in the form of a network graph. The efficiency of the developed visualisation system was measured by performing two types of user evaluations: a usability heuristics evaluation, and a query and visualisation evaluation.DiscussionThe relationships between the data were visualised, enabling the users to easily infer the knowledge and correlations between data. The results from the user evaluation show that the proposed visualisation system is suitable for both expert and novice users, with or without computer skills. This technique demonstrates the practicability of using a computer assisted-tool by providing cognitive analysis for understanding relationships between data. Therefore, the results benefit not only botanists, but also novice users, especially those that are interested to know more about plants.

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