Papers by Author: Liang Li

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Authors: Wen Ping Du, Liang Li, Wei Zhao
Abstract: With the development of advanced automation degree industries, the requirements of network management for workshop tool become more and more urgent. A very important part in network management system is identification technology of the tool. In this paper, 2D (two-dimensional) barcode identification technology is applied in the tool information in real-time query to realize network management. The 2D barcode reading device, which is combined with the local computer decoding software, could achieve communication between production line and the server. By using 2D barcode identification technology, it could achieve network management for workshop tool, improve production efficiency and reduce the artificial error.
Authors: H. Wu, Liang Li, N. He
Abstract: Micro milling force is the main parameter in motoring dynamic cutting process. The natural frequency of dynamometer is the key factor in the accurate measurement of high speed milling force. In this paper, a new structure fixture is designed, and the natural frequency of the fixture is obtained by finite element methods. After optimizing the structure design, the fixture is produced for the force signal acquisition system, together with the forces transducer, signal acquisition card and the software based on the LabVIEW. The experiment shows that the design of the fixture can meet the requirements of force acquisition.
Authors: Zi Yang Cao, Ning He, Liang Li
Abstract: In order to investigate the effects of cutting edge radius on micro/meso-scale cutting process, the current paper is concerned with a fundamental investigation of the contribution of cutting edge radius to cutting temperature, stress field and size effect by means of two-dimensional finite-element simulation for orthogonal cutting process. The results indicated that cutting edge radius has remarkable effects on cutting temperature and stress field, and the existence of cutting edge radius is one of the main reasons generating size effect. The cutting edge radius affects the micro/meso scale cutting process at smaller uncut chip thickness by altering the effective rake angle and enhancing the plowing effect, affecting the material deformation process, expanding and widening the plastic deformation zone, and causing higher energy dissipation due to increased tool-chip contact length.
Authors: Ning He, Liang Li, X.L. Li
Abstract: Gas cooled cutting is an important branch of green machining technology with its excellent cooling performance and is used more and more widely in field of machining. A new method of developing cooling gas generator using semiconductor refrigeration is presented in this paper. Then the main principle, structure and performance of the generator are introduced. In addition, the experiments of high speed milling of Ti Alloy using cooled nitrogen gas were conducted and satisfactory results were achieved. These researches show that the new cooling gas generator has a series of merits such as simple structure, excellent performance, handy operation, low cost and significant spreading value etc.
Authors: Yu Pei Jia, Wei Zhao, Liang Li
Abstract: Cutting tools play an important role in the cutting process of titanium aircraft components, but it is difficult to comprehensively evaluate the cutting tool performance, so the selection of appropriate cutting tool becomes extremely important. In this paper, an evaluation method using grey relational analysis for cutting tool performance was proposed. Meanwhile, in this method, a test benchmark with some typical difficult-to-machined features extracted from titanium aircraft components was designed, and the processing route was developed. Grey comprehensive evaluation models of cutting tool performance were established for the rough and finish machining respectively. Finally, the grey comprehensive evaluation models were used to evaluate the cutting tool performance in the milling experiments of the benchmarks. The results show that the grey relational comprehensive evaluation method is convenient and effective to evaluate milling tools performance for titanium aircraft components.
Authors: Xiao Qiang Xue, Ning He, Liang Li, Wei Zhao, Qi Wang
Abstract: This paper investigates the selection method of vari-speed milling parameters by experiments. The orthogonal experiments of vari-speed milling were studied on a given speed according to the stability lobes, and various parameters were selected. The experimental results show that varying speed milling approach possesses effects on vibration suppression on proper parameters selection though the acceleration damping ratio γa and the sound damping ratio γs. The variance analysis of dual factors test is adopted to data process and the acceleration damping ratio γa is taken as the evaluation index of vibration suppression. Finally, the preliminary conclusions on how to select proper parameters are obtained on the basis of the analysis of the experimental results, which is applied to online monitoring techniques using vibration to achieve automatic control of variable speed cutting.
Authors: Xiao Qiang Xue, Ning He, Liang Li, Wei Zhao, Qi Wang
Abstract: The axial limit cutting depth(LCD) of constant speed were studied, and the stability lobes were gotten by expriments and simulation. The vari-speed milling selected various parameters was investigated by expriments,also.The experimental results show that varying speed milling approach improves the limit cutting depth on proper time and prope parameters selection. According to the comparative analysis of the exprimental results of constant speed and vari-speed milling, it was obtained whether the varying speed milling approach was to be chosen and how to select proper parameters, should be reference to the stability lobes of constant speed.
Authors: G. Liu, Ning He, Z.L. Man, Liang Li
Authors: Wei Zhao, Ning He, Liang Li
Abstract: Titanium alloys are known for their strong chemical reactivity with surrounding gas due to their high chemical affinity, especially in dry machining. This paper describes a study of chip formation characteristics under nitrogen gas media when machining Ti6Al4V alloy with WC-Co cemented carbide cutting tools at high cutting speeds. Based on the experimental study, a finite element model of two-dimensional orthogonal cutting process for Ti6Al4V alloy at different cutting conditions was developed using a commercial finite element software Deform-2D. Saw-tooth chips with adiabatic shear bands were produced in both experiments and simulations. And the enhanced cooling and anti-frictional effects of nitrogen gas upon the high speed cutting process of Ti6Al4V alloy were analyzed. Results of this investigation indicate that the anti-frictional performance of nitrogen gas has a significant effect on chip formation when machining Ti6Al4V alloy at high cutting speeds. Compared to air, Nitrogen gas is more suitable in improving the contact conditions at chip-tool interfaces and in increasing the shear band frequency of chip formation during high speed cutting of Ti6Al4V alloy.
Authors: Yu Su, Ning He, Liang Li
Abstract: Cryogenic minimum quantity lubrication (CMQL) is a kind of green cooling/lubrication technique, which consists of the application of a small amount of lubricant (6-100 ml/h), delivered in a refrigerated compressed gas stream to the cutting zone. This paper experimentally investigates the effect of CMQL on cutting temperature and tool wear in high-speed end milling of titanium alloys. Comparative experiments were conducted under different cooling/lubrication conditions, i.e. dry milling, refrigerated air cutting, and CMQL. The refrigerated gas equipment was manufactured based on composite refrigeration method to provide the refrigerated air. The experimental results show that application of CMQL resulted in drastic reduction in cutting temperature and tool wear especially when machining titanium alloys at a high cutting speed.
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