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Redesigned Surface Based Machining Strategy and Method in Peripheral Milling of Thin-walled Parts

Chinese Journal of Mechanical Engineering 2010年第3期23卷 282-287页

作者： JIA Zhenyuan GUO Qiang SUN Yuwen GUO Dongming Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of Technology Dalian 116024 China

Currently, simultaneously ensuring the machining accuracy and efficiency of thin-walled structures especially high performance parts still remains a challenge. Existing compensating methods are mainly focusing on 3-aixs machining, which sometimes only take one given point as the compensative point at each given cutter location. This paper presents a redesigned surface based machining strategy for peripheral milling of thin-walled parts. Based on an improved cutting force/heat model and finite element method（FEM） simulation environment, a deflection error prediction model, which takes sequence of cutter contact lines as compensation targets, is established. And an iterative algorithm is presented to determine feasible cutter axis positions. The final redesigned surface is subsequently generated by skinning all discrete cutter axis vectors after compensating by using the proposed algorithm. The proposed machining strategy incorporates the thermo-mechanical coupled effect in deflection prediction, and is also validated with flank milling experiment by using five-axis machine tool. At the same time, the deformation error is detected by using three-coordinate measuring machine. error prediction values and experimental results indicate that they have a good consistency and the proposed approach is able to significantly reduce the dimension error under the same machining conditions compared with conventional methods. The proposed machining strategy has potential in high-efficiency precision machining of thin-walled parts.

关键词： redesigned surface tool path part deflection error prediction finite element method

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error Compensation of Thin Plate-shape Part with Prebending Method in Face Milling

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Chinese Journal of Mechanical Engineering 2015年第1期28卷 88-95页

作者： YI Wei JIANG Zhaoliang SHAO Weixian HAN Xiangcheng LIU Wenping School of Mechanical Engineering Shandong University Engineering Training Center Shandong University Key Laboratory of High-efficiency and Clean Mechanical Manufacture at Shandong University Ministry of Education

Low weight and good toughness thin plate parts are widely used in modem industry, but its flexibility seriously impacts the machinability. Plenty of studies locus on the influence of machine tool and cutting tool on the machining errors. However, few researches focus on compensating machining errors through the fixture. In order to improve the machining accuracy of thin plate-shape part in face milling, this paper presents a novel method for compensating the surfacc errors by prebending the workpiece during the milling process. First, a machining error prediction model using finite element method is formulated, which simplifies the contacts between the workpiece and fixture with spring constraints. Milling fbrces calculated by the micro-unit cutting force model arc loaded on the error prediction model to predict the machining error. The error prediction results are substituted into the given formulas to obtain the prebending clamping forces and clamping positions. Consequently, the workpiece is prebent in terms of the calculated clamping forces and positions during the face milling operation to reduce the machining error. Finally, simulation and experimental tests are carried out to validate the correctness and efficiency of the proposed error compensation method. The experimental measured flatness results show that the flatness improves by approximately 30 percent through this error compensation method. The proposed mcthod not only predicts the machining errors in face milling thin plate-shape parts but also reduces the machining errors by taking full advantage of the workpiece prebending caused by fixture, meanwhile, it provides a novel idea and theoretical basis for reducing milling errors and improving the milling accuracy.

关键词： face milling error prediction prebending error compensation fixture

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Comparison of the Refraction Precision Results between Pentacam AXL and IOL Master 700 Using Universal II Barrett Formula after Cataract Surgery

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Open Journal of Ophthalmology 2023年第1期13卷 1-12页

作者： Budiman Tjokrovonco Ludwig Melino Sugiarti Emmy Dwi Knoch Andrew Maximilian Cataract and Refractive Surgery Unit Cicendo National Eye Center Bandung Bandung Indonesia Department of Ophthalmology Faculty of Medicine Universitas Padjajaran/National Eye Center - Cicendo Eye Hospital Bandung Indonesia

Background: The availability of premium intraocular lenses (IOL), including toric, multifocal, and EDOF, has become very sophisticated and now demands accurate biometric measurement accuracy. The Pentacam AXL and IOL Master 700 are often used for optical biometry and they are available in the market today. They can also be used to measure the parameters needed in the IOL calculation using the latest generation formulas, such as the Barett Universal II. Therefore, this study aims to compare the accuracy of refraction results between Pentacam AXL compared to IOL Master 700 after cataract surgery with the Barett Universal-II formula. Method: A total of 64 eyes from 64 patients who had a preoperative examination with IOL Master 700 and Pentacam AXL were included in this study. Parameters such as K, ACD, LT, WTW, and AL were then compared between the two tools. prediction error values were also calculated and compared based on the difference between the Spherical equivalent (SE) of subjective refraction results after 4 weeks of surgery with their refractive prediction targets. Results: There was no statistically significant difference in the parameters measured from the two tools except ACD and WTW. Furthermore, LT was difficult to obtain on the Pentacam AXL due to penetration problems, as well as in patients with significant lens opacities. The percentage of error prediction values that reach ± 0.50 D on Pentacam AXL and IOL Master 700 was 70.3% and 73.5%, respectively. However, the average prediction error that was close to emmetropia with IOL Master 700 was greater compared to the other tool. Conclusion: Pentacam AXL has a fairly good accuracy for refraction prediction compared to IOL Master 700. However, it is still necessary to optimize its constants to obtain optimal results.

关键词： error prediction Biometry IOL Master 700 Pentacam AXL

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A Novel Control Strategy Based on Temperature Dynamic Decoupling and Belief Expert Rule Base for Large-scale Vertical Quench Furnaces

A Novel Control Strategy Based on Temperature Dynamic Decoup...

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第36届中国控制会议

作者： Weiran Dang Jianjun He School of Information Science and Engineering Central South University

ISBN: (纸本)9781538629185

The large-scale vertical quench furnace has large volume,comphcated structure,strong coupling property,and a variety of heat transfer *** is hard to achieve stability *** in the actual production process,due to the serious variety of ambient temperature,its temperature fluctuate greatly In this paper,a Kernel Extreme Learning Machine（KELM） prediction method is proposed to predict the decoupling parameters in real time by predicting the temperature difference between adjacent two zones at the current time to achieve decouple the temperature of each ***,the Belief Expert Rule Base（BERB） PID control algorithm is utilized to control the temperature *** results show that the method can effectively improve the homogeneity of the temperature in the furnace,and the method is better than the existing method when the ambient temperature changes greatly.

关键词： Large Vertical Quench Furnace error prediction Dynamic Decoupling Belief Expert Rule PID

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Volumetric calibration of multi-axis machine tools through parametric way

Volumetric calibration of multi-axis machine tools through p...

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2008InternationalConferen...

作者： Abdul Wahid Khan School of Mechanical Engineering and Automation Beihang University

＜正＞A methodology was implemented to evolve the volumetric errors of multiaxis machine tools through a parametric way. The volumetric error was calibrated and evaluated in the workspace arbitrarily by implementing parametric methods and *** parametric method linear displacement errors and angular displacement errors were measured through a laser interferometer with combination of a newly developed three-line measuring method to measure the prismatic joints for efficient and quick error *** these,squareness errors between the axes were also quantified by using reversal *** accuracy portrayed the real error picture between the workpiece and cutting tool or end effectors or a measuring *** positional errors,straightness errors,angular errors and squareness errors were quantified and transformed into volumetric accuracy by using generalized homogenous transformation matrices,whereas forward kinematics technique was used as a *** results can be used to compensate the volumetric errors to achieve high precision in manufacturing and measurement through physical compensation,making correction, adjustment or improvement through *** here is the volumetric accuracy results carried on a multi-axis CNC milling machine under controlled environmental conditions and as per the standard procedure and practice.

关键词： volumetric accuracy machine tools calibration HTM error prediction Laser interferometer error modelling Metrology.

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