The Research on Milling Temperature and Heat Deformation of Tool in Virtual Numerical Control Simulation

2010 ◽  
Vol 97-101 ◽  
pp. 2865-2870 ◽  
Author(s):  
Xiu Lin Sui ◽  
Li Juan Jin ◽  
Jiang Hua Ge ◽  
Jia Tai Zhang ◽  
Zheng Wei Kong
Keyword(s):  
Correlation Coefficients ◽  
Least Square Method ◽  
Mathematic Model ◽  
Joint Modeling ◽  
Least Square ◽  
Numerical Control ◽  
Technical Problems ◽  
Nc Simulation ◽  
Milling Temperature ◽  
Heat Deformation

Joint modeling of exponentially fitting and least square method was proposed for key technical problems on milling temperature and heat deformation of tool in virtual numerical control (NC) simulation. Mathematic model of surface temperature and its influencing factors based on ball-end mill was established. Correlation coefficients of model are over 0.8, and the errors comparing with the experimental ones are within 10%, which shows that the model meets precision requirement, and fitting effect is good. By this model a mathematical model of the ball-milling cutter’s thermal deformation was established, and the relative error is small by comparing with test values, which proves that this model has high calculation precision and practical meaning. A simulation prediction system of milling temperature and ball-end mill’s heat deformation in virtual NC was developed based on above mentioned models, which can provide theoretical basis for machining error prediction, optimizing milling parameters and improving machining quality.

The Mathematical Model of Welding Process Comparative Study of Identification Method

2012 ◽  
Vol 472-475 ◽  
pp. 2241-2244 ◽  
Author(s):  
Jun Feng Wu ◽  
Jing Huang
Keyword(s):  
Weld Pool ◽  
Academic Research ◽  
Welding Process ◽  
Least Square Method ◽  
Mathematic Model ◽  
Least Square ◽  
Complex Object ◽  
Strong Nonlinearity ◽  
Area Method ◽  
Pulsed Gtaw

The dynamic process of the weld pool is a high complex object with strong nonlinearity, mult-variable coupling and a mount of stochastic and uncertain factors. It is very difficult to obtain an analysis mathematic model of weld pool dynamics. Pulsed Gas Tungsten Arc Welding (GTAW) is an important metal’s welding technology, which has been widely applied in the aerospace and manufacturing areas. Therefore, the dynamic characteristic of the welding process has always been hot and difficult in the field of academic research and engineering applications. In order to solve the difficulties of modeling and controlling of nonlinear system, this paper investigates the dynamic characters of the pulsed GTAW from the classic control systems. It obtains the SISO transfer function model by the area method and least square method. The results of simulation experiment show that the area method is better between the two methods.

Minimum Zone Evaluation of Symmetry Error for Flatness to Flatness Based on the New Generation GPS

2013 ◽  
Vol 662 ◽  
pp. 887-891
Author(s):  
Qian Qian ◽  
Mei Fa Huang ◽  
Huan Yu Li
Keyword(s):  
Least Square Method ◽  
Mathematic Model ◽  
Least Square ◽  
Adaptive Genetic Algorithm ◽  
Machining Error ◽  
Minimum Zone ◽  
New Generation ◽  
Tolerance Method ◽  
The Mathematical Model ◽  
Better Than

Least square method (LSM) is the most popular method used to evaluate machining error nowadays. However, LSM is likely to overestimate the error value, therefore its solution is only approximate and rather than minimum. In order to obtain the minimum, we study the principle of the minimum zone tolerance method (MZT), analyze the characteristics of the new generation GPS, and give the minimum zone mathematic model of the symmetry error for flatness to flatness. For the purpose of optimizing the mathematical model, this paper describes the application of adaptive genetic algorithm to achieve the best estimation. Simultaneously, the process of optimization is realized by MALTAB. Finally, the experiment shows that the evaluation results of MZT is better than evaluation results of LSM.

Design and Realization on the Optimal Quadratic Controller for the Positional Servo System of Numerical Control System

2011 ◽  
Vol 317-319 ◽  
pp. 1960-1963
Author(s):  
Li Bing Zhang ◽  
Ting Wu
Keyword(s):  
Control System ◽  
Control Method ◽  
Servo System ◽  
Least Square Method ◽  
Least Square ◽  
Servo Control ◽  
Numerical Control ◽  
Recursive Least Square ◽  
Servo Control System ◽  
Position Servo

This paper presents a technique for the position servo system of numerical control (NC) machine tool by utilizing the optimal quadratic controller. The mathematical model of the position servo control system is structured, which of the plant model is identified by making use of recursive least square method. The fundamental method of designing the optimal quadratic controller is proposed. Simulation of the optimal quadratic controller and PID controller are implemented by using MATLAB. The results of simulation show that the proposed control method of positional servo control system has better dynamic characteristics and better steady performance.

scholarly journals An optical model for deriving the spectral particulate backscattering coefficients in oceanic waters

Ocean Science ◽  
2013 ◽  
Vol 9 (6) ◽  
pp. 987-1001 ◽  
Author(s):  
S. P. Tiwari ◽  
P. Shanmugam
Keyword(s):  
Optical Model ◽  
Trust Region ◽  
Simulated Data ◽  
Correlation Coefficients ◽  
Least Square Method ◽  
Least Square ◽  
Data Set ◽  
New Model ◽  
Trust Region Algorithm ◽  
In Situ Data

Abstract. An optical model is developed based on the diffuse attenuation coefficient (Kd) to estimate particulate backscattering coefficients bbp(λ) in oceanic waters. A large in situ data set is used to establish robust relationships between bbp(530) and bbp(555) and Kd(490) using an efficient nonlinear least-square method which uses the trust region algorithm with Bisquare weights scheme to adjust the coefficients. These relationships are obtained with good correlation coefficients (R2 = 0.786 and 0.790), low root mean square error (RMSE = 0.00076 and 0.00072) and 95% confidence bounds. The new model is tested with three independent data sets: the NOMAD SeaWiFS Match ups, OOXIX IOP algorithm workshop evaluation data set (Version 2.0w APLHA), and IOCCG simulated data set. Results show that the new model makes good retrievals of bbp at all key wavelengths (from 412–683 nm), with statistically significant improvements over other inversion models. Thus, the new model has the potential to improve our present knowledge of particulate matter and their optical variability in oceanic waters.

Reconstruction of the Stone Tablet Based on Vectorization of Images

2012 ◽  
Vol 155-156 ◽  
pp. 800-804
Author(s):  
Jie Zhang
Keyword(s):  
Least Square Method ◽  
Least Square ◽  
Numerical Control ◽  
Source Image ◽  
Numerical Control Machining ◽  
Image Preprocessing

Traditionally, it costs a lot of time and efforts to reconstruct the stone tablet manually. The system which can transformat the image got by photography into the dxf file is proposed and make it possible to program automatically and to machine in numerical control machining. To get the dxf file, using the image preprocessing、 the surrounding eight pixels and the least square method to complete the Vectorization in this paper. Finally, the specific interface program to generate a DXF file is given. The result proved feasible and the comparison of the source image and the objective dxf file opened by AutoCAD is given in this paper.

scholarly journals An optical model for deriving the spectral particulate backscattering coefficients in clear and turbid coastal waters

2013 ◽  
Vol 10 (1) ◽  
pp. 261-290
Author(s):  
S. P. Tiwari ◽  
P. Shanmugam
Keyword(s):  
Coastal Waters ◽  
Optical Model ◽  
Trust Region ◽  
Correlation Coefficients ◽  
Least Square Method ◽  
Least Square ◽  
Data Set ◽  
New Model ◽  
Trust Region Algorithm ◽  
In Situ Data

Abstract. An optical model is developed based on the diffuse attenuation coefficient (Kd) to estimate particulate backscattering coefficients bbp(λ) in clear and turbid coastal waters. A large in-situ data set is used to establish robust relationships between bbp(530) and bbp(555) and Kd(490) using an efficient nonlinear least square method which uses the Trust-Region algorithm with Bisquare weights scheme to adjust the coefficients. These relationships are obtained with good correlation coefficients (R2 = 0.786 and 0.790), low Root Mean Square Error (RMSE = 0.00076 and 0.00072) and 95% confidence bounds. The new model is tested with two independent data sets such as the NOMAD SeaWiFS Match-ups and OOXIX IOP algorithm workshop evaluation data set (Version 2.0w APLHA). Results show that the new model makes good retrievals of bbp at all key wavelengths (from 412–683 nm), with statistically significant improvements over other inversion models. Thus, the new model has the potential to improve our knowledge of particulate matters and their optical variability in both clear and turbid coastal waters.

Uncertainty Evaluation of Duration of Aircraft DC Transient Signal Based on Least Square Method

2014 ◽  
Vol 599-601 ◽  
pp. 1801-1806
Author(s):  
Pu Zhong Ouyang ◽  
Zhong Hua Zhang ◽  
Jing Yu Sun
Keyword(s):  
Performance Evaluation ◽  
Uncertainty Analysis ◽  
Least Square Method ◽  
Least Square ◽  
Transient Signal ◽  
Uncertainty Evaluation ◽  
Test Results ◽  
Technical Problems ◽  
Signal Waveform ◽  
And Performance

By using the waveform measurements and the least square method, the duration of transient level, and the duration of transient decreasing segment of aircraft DC transient signal are evaluated precisely. The evaluation courses and some technical problems are discussed in detail, the uncertainty analysis both of the durations are presented. Some test results have proved the effectiveness and practicability of the method. It could be applied to the characteristic and performance evaluation of aircraft DC transient signal waveform generators.

Numerical Correction High Temperature of Near-Infrared Colorimetry

2011 ◽  
Vol 301-303 ◽  
pp. 1378-1383
Author(s):  
Li Hua Yuan ◽  
Guan Hua Wu ◽  
Ming Li
Keyword(s):  
High Temperature ◽  
Surface Temperature ◽  
Near Infrared ◽  
Least Square Method ◽  
Mathematic Model ◽  
Least Square ◽  
Radiation Pyrometer ◽  
Surface Emissivity ◽  
Relationship Of ◽  
The Relationship

Colorimetry is commonly used to measure the surface temperature as true one when the surface emissivity is constant. That is, the target is regarded as greybody. But in fact, most materials are not greybody. Spectrum emissivity has to do with wavelength and temperature. And in the most case, it is difficult to assure the exact values of the emissivity .This makes the relative error of the temperature big. Therefore, it is necessary to modify the emissivity response of radiation pyrometer. The factor influencing the spectrum was researched through the application of least square method to create the relationship of spectrum emissivity with wavelength and temperature, at last mathematic model was established which provided numerical correction of infrared two-color thermometry.

Conversion method study from cutter-location points to nonuniform rational B-spline toolpath NC file for high-speed machining

2018 ◽  
Vol 233 (2) ◽  
pp. 514-525
Author(s):  
Jian-wei Ma ◽  
De-ning Song ◽  
Zhen-yuan Jia ◽  
Guo-qing Hu ◽  
Wei-wei Su
Keyword(s):  
Computer Aided Design ◽  
High Speed ◽  
Least Square Method ◽  
Least Square ◽  
Numerical Control ◽  
High Speed Machining ◽  
B Spline ◽  
Conversion Method ◽  
Nc Program ◽  
Computer Aided

Parts with complex curved surfaces are widely applied and the demands for the machining quality and the machining efficiency of such complex parts become increasingly higher. In order to realize high-speed and high-quality machining, the nonuniform rational B-spline interpolator is widely researched and demonstrated to be superior to the conventional linear or circular interpolators. However, the nonuniform rational B-spline toolpath NC files cannot be directly generated from the computer-aided design (CAD) models by using commercial computer-aided manufacturing (CAM) software. To deal with this problem, a conversion method from the cutter-location points to the nonuniform rational B-spline toolpath numerical control (NC) file is presented. To avoid the bad curve-fitting effect at sharp corners of the toolpath and to meanwhile reduce the computational burden, the cutter-location pre-processing method, consisting data segmentation and data simplification, is provided first. Then, the least-square method is employed to fit the cutter locations to the nonuniform rational B-spline curves, and an iterative fitting approach is proposed for linear/nonuniform rational B-spline hybrid toolpath generation. Finally, a user interface is designed for displaying the fitting results and outputting the NC file with nonuniform rational B-spline toolpaths. By using this method, nonuniform rational B-spline and linear toolpaths hybrid interpolation NC program can be generated for the high-speed machining of complex curved surface parts with the utilization of the nonuniform rational B-spline interpolator. The experimental results demonstrate the feasibility and the advantages of the presented method.

Primitive Study on Model-Based Process Identification by Utilizing Force Estimation Techniques

2016 ◽  
Author(s):  
Norikazu Suzuki ◽  
Ryosuke Ikeda ◽  
Eiji Shamoto
Keyword(s):  
Transfer Function ◽  
Cutting Force ◽  
Least Square Method ◽  
Least Square ◽  
Numerical Control ◽  
Cutting Process ◽  
Force Model ◽  
Force Estimation ◽  
Force Coefficient ◽  
Cutting Force Coefficient

This study presents a new method to identify parameters representing cutting process and transfer function of flexible mechanical structures mounted on a traveling stage by utilizing only internal information of computerized numerical control (CNC) system. Disturbance force input to CNC is estimated by disturbance observer and cutting force is estimated based on cutting force model. Analyzing influence of the estimated cutting force on the disturbance force, parameters used in the assumed models of cutting process and structural dynamics are identified in quasi-real-time. Least square method (LSM) is utilized for the parameter identification. Face turning experiment using an ultra-precision machine tool was conducted to verify feasibility of the proposed method. Experimental results clarified that the cutting force coefficient and the modal parameters representing the dynamic characteristics of the force transfer function can be identified accurately by the proposed method.

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