A Solid Boundary Based Tolerance Representation Model

1992 ◽  
Author(s):  
S. Liu ◽  
Z. Dong
Keyword(s):  
Geometric Modeling ◽  
Coordinate Measuring Machine ◽  
Solid Boundary ◽  
Solid Model ◽  
New Approach ◽  
Part Geometry ◽  
Geometric Tolerances ◽  
Design And Manufacturing ◽  
Boundary Face ◽  
Measuring Machine

Abstract An ambiguous representation of design geometry and its allowed variation is essential to design and manufacturing analysis tools using geometric modeling. In this paper, a new approach for modeling and representing mechanical tolerances, using information embedded in the solid model, is introduced. The work focuses on mathematical mapping between the nominal and variant configurations of design geometry, using boundary face-based model variables. The method identifies the relation between the errors of part geometry, represented by a solid model and measured using a coordinate measuring machine, and the tolerances, specified by dimensioning and tolerancing standards. The work is of benefit in understanding of the fundamental nature of geometric errors and tolerances; it guides the specification of dimensional and geometric tolerances; and, contributes to automated mechanical tolerancing in a solid modeling based system.

scholarly journals The Influence of Automated Machining Strategy on Geometric Deviations of Machined Surfaces

2021 ◽  
Vol 11 (5) ◽  
pp. 2353
Author(s):  
Ján Varga ◽  
Teodor Tóth ◽  
Peter Frankovský ◽  
Ľudmila Dulebová ◽  
Emil Spišák ◽  
...  
Keyword(s):  
Control System ◽  
Surface Quality ◽  
Coordinate Measuring Machine ◽  
Geometric Tolerance ◽  
Geometric Tolerances ◽  
Significant Difference ◽  
Geometric Deviations ◽  
Measuring Machine ◽  
Overlap Parameter ◽  
Total Average

This paper deals with various automated milling strategies and their influence on the accuracy of produced parts. Among the most important factors for surface quality is the automated milling strategy. Milling strategies were generated from two different programs, CAM system SolidCAM, with the help of workshop programming in the control system Heidenhain TNC 426. In the first step, simulations of different toolpaths were conducted. Using geometric tolerance is becoming increasingly important in robotized production, but its proper application requires a deeper understanding. This article presents the measurement of selected planes of robotized production to evaluate their flatness, parallelism and perpendicularity deviations after milling on the coordinate measuring machine Carl Zeiss Contura G2. Total average deviations, including all geometric tolerances, were 0.020 mm for SolidCAM and 0.016 mm for Heidenhain TNC 426. The result is significantly affected by the flatness of measured planes, where the overlap parameter of the tools has a significant impact on the flatness of the surface. With interchangeable cutter plate tools, it is better to use higher overlap to achieve better flatness. There is a significant difference in production time, with SolidCAM 25 min and 30 s, and Heidenhain 48 min and 19 s. In accordance with these findings, the SolidCAM system is more suitable for production.

A new approach of kinematic geometry for error identification and compensation of industrial robots

2018 ◽  
Vol 233 (5) ◽  
pp. 1783-1794
Author(s):  
Zhi Wang ◽  
Huimin Dong ◽  
Shaoping Bai ◽  
Delun Wang
Keyword(s):  
Curve Fitting ◽  
Kinematic Model ◽  
Coordinate Measuring Machine ◽  
Reference Points ◽  
Industrial Robots ◽  
Kinematic Calibration ◽  
Kinematic Pair ◽  
Good Efficiency ◽  
New Approach ◽  
Measuring Machine

A new approach for kinematic calibration of industrial robots, including the kinematic pair errors and the link errors, is developed in this paper based on the kinematic invariants. In most methods of kinematic calibration, the geometric errors of the robots are considered in forms of variations of the link parameters, while the kinematic pairs are assumed ideal. Due to the errors of mating surfaces in kinematic pairs, the fixed and moving axes of revolute pairs, or the fixed and moving guidelines of prismatic pairs, are separated, which can be concisely identified as the kinematic pair errors and the link errors by means of the kinematic pair errors model, including the self-adaption fitting of a ruled surface, or the spherical image curve fitting and the striction curve fitting. The approach is applied to the kinematic calibration of a SCARA robot. The discrete motion of each kinematic pair in the robot is completely measured by a coordinate measuring machine. Based on the global kinematic properties of the measured motion, the fixed and moving axes, or guidelines, of the kinematic pairs are identified, which are invariants unrelated to the positions of the measured reference points. The kinematic model of the robot is set up using the identified axes and guidelines. The results validate the approach developed has good efficiency and accuracy.

Evaluation of Actual Geometric Tolerances Using Coordinate Measuring Machine Data

1989 ◽  
Author(s):  
W. H. ElMaraghy ◽  
Z. Wu ◽  
H. A. ElMaraghy
Keyword(s):  
Three Dimensional ◽  
Measurement Data ◽  
Simulated Data ◽  
Coordinate Measuring Machine ◽  
Optimization Techniques ◽  
Test Cases ◽  
Tolerance Zone ◽  
Geometric Tolerances ◽  
Measuring Machine

Abstract This paper focuses on the development of a procedure and algorithms for the systematic comparison of geometric variations of measured features with their specified geometric tolerances. To automate the inspection of mechanical parts, it is necessary to analyze the measurement data captured by coordinate measuring machines (CMM) in order to detect out-of-tolerance conditions. A procedure for determining the geometric tolerances from the measured three dimensional coordinates on the surface of a cylindrical feature is presented. This procedure follows the definitions of the geometric tolerances used in the current Standards, and is capable of determining the value of each geometric tolerance from the composite 3-D data. The developed algorithms adopt the minimum tolerance zone criterion. Nonlinear numerical optimization techniques are used to fit the data to the minimum tolerance zone. Two test cases are given in the paper which demonstrate the successful determination of geometric tolerances from given simulated data.

Fixture Design Process Automation for Coordinate Measuring Machines: A Knowledge-Based Approach

2006 ◽  
Vol 526 ◽  
pp. 103-108
Author(s):  
J. Perez ◽  
R. Hunter ◽  
J.C. Hernandez ◽  
Antonio Vizan Idoipe
Keyword(s):  
Design Process ◽  
Manufacturing Process ◽  
Coordinate Measuring Machine ◽  
Fixture Design ◽  
Knowledge Based ◽  
Design And Manufacturing ◽  
Inspection Process ◽  
Measuring Machine ◽  
The Right ◽  
Inspection Fixture

Nowadays, the inspection process is an essential part of the manufacturing process, where a product is subjected to verification of the geometric features, dimensions and tolerance specifications with respect to the product design specifications. One of the most interesting topics in the automation of the inspection process is the right fixture design. In the fixture design process we have used the information provided by the part design and manufacturing process. However, the lack of integration and structuring of this information results in one of the most important problems, producing an increase in the time and cost implied in the development of the fixture design and its implementation. For this reason, this work presents a knowledge model for the inspection fixture design process for a Coordinate Measuring Machine (CMM), which allows the automation of the inspection fixture design process to be made easier, reducing time and cost associated to the inspection process and to the manufacturing process in general.

The Modeling Design of Plastic Ashtray Technology and Rapid Prototyping Technology Based on Reverse Engineering

2014 ◽  
Vol 889-890 ◽  
pp. 9-13
Author(s):  
Zhi Yang Li ◽  
Xiao Mei Wang ◽  
Yu Zhu ◽  
Ming Yu Huang ◽  
Hong Jun Ni
Keyword(s):  
Rapid Prototyping ◽  
Reverse Engineering ◽  
Geometric Modeling ◽  
Three Dimensional ◽  
Coordinate Measuring Machine ◽  
Production Costs ◽  
Production Cycle ◽  
Engineering Technology ◽  
Surface Data ◽  
Measuring Machine

Reverse engineering is a process of using 3D geometric modeling method to reconstruct actual objects CAD model based on these points, which is used physical digital measuring equipment to measure the three-dimensional coordinates of points on the surface of the object accurately and rapidly. Based on reverse engineering technology as the theoretical basis, the paper used three-coordinate measuring machine to measure ashtray surface data. After data was be handled, which was used to reconstruct 3D entity in Pro/E software. Last, the 3D entity of ashtray was printed out through rapid prototyping machine, which can be achieved by physical sample to rapid manufacturing of products, shortening production cycle, reducing production costs.

Best Fit Uncertainty Analysis for Computing Geometric Tolerances

1997 ◽  
Author(s):  
Hong-Tzong Yau
Keyword(s):  
Sample Size ◽  
Measurement Data ◽  
Coordinate Measuring Machine ◽  
Point Location ◽  
Geometric Tolerances ◽  
Surface Deviation ◽  
Measuring Machine ◽  
Point Data ◽  
Geometric Variables ◽  
Best Fit

Abstract In computing geometric tolerances using point data from a coordinate measuring machine (CMM), a best fit process needs to be carried out to bring the measurement data to the coordinate system of the substitute geometry. The measurement data does not precisely conform to the substitute geometry. It involves errors from machining as well as measurement itself. With this error-carrying measurement data, the best fit result contains uncertainties which in turn reduce the accuracy of the evaluated tolerances. In this paper, a model is proposed to estimate the best fit uncertainties caused by surface deviation, point location, and CMM sample size. The model was verified by simulation and experiment. To explore factors that affect the uncertainty variations, geometric variables that influence the uncertainties were first studied. Then, to understand the effect of point location on the uncertainty, optimization using the conjugate gradient method was developed to find the best measurement locations by minimizing the total uncertainties. In addition, simulations showed that the uncertainty is inversely proportional to the squared root of the number of points. This result can be used to predict the CMM sample size that will control the best fit uncertainty under certain tolerances.

scholarly journals Experimental and Numerical Investigation of Engine Foundation for Vibration Reduction

2018 ◽  
Vol 68 (6) ◽  
pp. 604 ◽  
Author(s):  
Varanasi Ramakrishna ◽  
Shinadam Rama Krishna ◽  
PVS Ganesh Kumar
Keyword(s):  
Harmonic Analysis ◽  
Frequency Response ◽  
Vibration Reduction ◽  
Coordinate Measuring Machine ◽  
Vibration Response ◽  
Solid Model ◽  
Topology Optimisation ◽  
Baseline Model ◽  
Testing Frequency ◽  
Measuring Machine

<p>The purpose of this study is to minimise frequency response of engine foundation using topology optimisation. The study involves vibration response estimation of an existing marine engine foundation, validation of estimations with measurements and estimation of reduction in vibration response after optimisation. Initially, solid model of baseline model is generated using dimensions of the existing foundation measured by a laser line probe coordinate measuring machine. Harmonic analysis is used to find the vibration response of the foundation. These results are experimentally validated by the measurements on the foundation using the vibration testing. Frequency response topology optimisation is then carried out on the baseline model to reduce vibration response with specified constraints and objective function. Subsequently, harmonic analysis is performed on the topology optimised design to verify the reduction in vibration response. From these results, it is observed that considerable frequency response is reduced with modified design compared to baseline model.</p>

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