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Guangming Zheng,Xiang Cheng,Li Li,Rufeng Xu,Yebing Tian 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1
The high-speed dry milling of AISI 4340 steel was carried out with a CVD Al 2 O 3 /TiCN coated carbide tool. The relationships between cutting force, surface roughness and cutting parameter were conducted, and the influence of tool wear on cutting force and surface roughness was also investigated. The wear mechanism of coated tool was revealed by SEM micrograph and EDS analysis. Due to the lower tool wear rate, the increase of cutting forces and surface roughness R a was smaller at the initial wear stage and the steady wear stage, whereas the increase of cutting forces was improved suddenly when the flank wear was more than 0.25 mm. Additionally, the coated tool wear was mainly caused by adhesion, abrasion, oxidation and diffusion, accompanied with a little peeling and chipping. The research results are expected to provide optimum cutting parameters for high-efficiency machining of high-strength steel.
Fabrication accuracy analysis of micromilling tools with complicated geometries by wire EDM
Xiang Cheng,Xianhai Yang,Guangming Zheng,Yumei Huang,Li Li 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.6
The micromilling tool is one of the key factors affecting micromilling performance. The design and fabrication of micromilling toolsare still behind the increasing requirements in miniature component fabrication. How to estimate the fabrication accuracy of a newlydesigned micromilling tool is one of the urgent issues for micro tooling. This paper introduces an accuracy analysis method in the fabricationof micromilling tools by wire electrical discharge machining (WEDM) process. Taking two typical micro ball end mills into consideration,the micro tool fabrication process is kinematically modeled and analyzed. Analytical results show that the final fabricationaccuracy has a close relationship with the designed micro tool geometry. The fabrication procedures can be arranged based on the kinematicalanalysis, and the final fabrication accuracy also is affected by it. The radius errors of the fabricated micro ball end mill prototypeare within ±2μm, which is higher than that of commercially available similar ones. It verifies the proposed accuracy analysis method.
Yuan Li,Guangming Zheng,Xu Zhang,Xiang Cheng,Xianhai Yang,Rufeng Xu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.11
The TiAlN+TiN coated tool, AlTiN coated tool and TiN/TiCN/TiAlN multi-coated tool were chosen for the high-speed milling of AISI 4340. The resultant cutting force and tool wear of coated tools were reviewed. The influence of cutting parameters and coating materials on the machined surface roughness was studied. The smallest resultant cutting force was obtained by TiN/TiCN/TiAlN multicoated tool. The main wear mechanisms of coated tool were chipping, collapse, the chipping of coating, adhesive wear, abrasive wear and crater wear. The minimal flank wear width was obtained by TiN/TiCN/TiAlN multi-coated tool. Among the selected cutting parameters, the lower surface roughness R a of 0.08~0.32 μm was achieved by the TiN/TiCN/TiAlN multi-coated tool and TiAlN+TiN coated tool. This work was conducive to the selection of coated tools and the optimization of cutting parameters in high-speed milling of AISI 4340, as well as to the promotion of high-efficiency and high-quality machining of hard-to-cut material.
A flow rate on-line monitoring method for piezoelectric pump based on self-sensing circuit
Hong Jiang,Guohui Wu,Lipeng He,Yuecheng Wang,Dianbin Hu,Zheng Zhang,Guangming Cheng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5
This paper presents a new flow rate monitoring method for a piezoelectric micropump based on a self-sensing circuit. Utilizing the voltage generated by the secondary direct piezoelectric effect as the sensing voltage, a soft sensor of the piezoelectric actuator can be implemented onto the piezoelectric micropump. A bridge-type circuit is proposed as the selfsensing circuit, the piezoelectric micropump is fabricated with a circular piezoelectric actuator, the characteristics of the self-sensing voltage and the flow rate are experimentally investigated under different excitation voltages and frequencies. The results show that the method can accurately determine optimal frequency of the micropump (100 Hz, 280 Hz), and for a fixed frequency of 100 Hz and a voltage range of 50-180 V, the correlation between the self-sensing voltage and the flow rate is 0.9732. As a result, the method demonstrated in this paper allows precise monitoring of the flow rate of the piezoelectric micropump without using external sensors.
Thermal management analysis of serial-connection three-chamber piezoelectric pump
Lipeng He,Xiaoqiang Wu,Zheng Zhang,Jingran Wang,Dianbin Hu,Yamei Liu,Guangming Cheng 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10
The design of a micropump with high performance and excellent reliability on thermal management still remains a challenge for electronic cooling. The performance of a piezoelectric pump with 3 chambers connected in series on thermal management was investigated for electronic cooling in this study. Two S-shaped channel heat sinks and the piezoelectric pump with 3 chambers connected in series were combined to form a loop cooling system. With water as the pumping medium, the tested pump has a flow rate most up to 690.6 ml/min at an input voltage of 220 V and an input frequency of 110 Hz. Suitability of the system has been demonstrated through simulation analysis and experimental verification for temperature control. A temperature reduction of 3 °C of CPU could be achieved at 250 mL/min flow rate generated by the piezoelectric pump with 3 chambers connected in series.
A bi-directional valveless piezoelectric micropump based on the Coanda effect
Zheng Zhang,Lipeng He,Jianwen Zhou,Dianbin Hu,Yi Hou,Guangming Cheng 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.2
In this paper, the hydrodynamic characteristics of a piezoelectric micropump operate on the Coanda effect, and the mechanism of bi-directional pumping are analyzed by numerical simulation and experiments. The research focuses on the different positions of the fluid deflector and the influence on the output of the micropump. The results show that a closer fluid deflector to the inlet can produce greater vortices in the suction process due to the Coanda effect, and the backflow diminishing is more significant as well. Moreover, the different positions of the fluid deflector can cause a phenomenon that the micropump will achieve bi-directional pumping. As a finding, vortices arranged in pairs could improve the rectification efficiency of the micropump. The micropump achieves a maximum flow rate of 40.5 ml/min and back pressure of 5.76 cmH 2 o. In addition, the maximum flow rate per unit area can reach 305.2 μl/(min mm 2 ).