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Design and analysis of a new high frequency double-servodirect drive rotary valve

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Frontiers of Mechanical Engineering 2016年第4期11卷 344-350页

作者： Muzhi ZHU shengdun zhao Jingxiang LI School of Mechanical Engineering Xi'an Jiaotong University Xi'an710049 China

Researchers have investigated direct drive valve for many years to solve problems, such as fluid force imbalance and switching frequency. The structure of the rotary valve has received considerable research interest because of its favorable dynamic properties and simple structure. This paper studied the high frequency doubleservo direct drive rotary valve (DDRV), and proposed a novel structure and drive method satisfying high reversing frequency and adequate quantity of flow. Servo motors are integrated into the valve by the innovative structure, which is designed to equilibrate the unbalanced radial fluid force with the symmetric distributed oil ports. Aside from the fast reversing function of the valve, the DDRV presented high performance in linearity of the flow quantity and valve opening as a result of the fan-shaped flow ports. In addition, a computational fluid dynamics (CFD) method based on Fluent was conducted to verify the flux regulation effect of the height change of the adjustable boss.

关键词： direct drive rotary valve computational fluid dynamics (CFD) flow regulation

Relationship between Hardness and Deformation during Cold Rolling Process of Complex Profles

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Chinese Journal of Mechanical Engineering 2023年第5期36卷 315-329页

作者： Dawei Zhang Linghao Hu Bingkun Liu shengdun zhao Xi’an Key Laboratory of Intelligent Equipment and Control School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710049China

The hardening on surface of complex profles such as thread and spline manufactured by cold rolling can efectively improve the mechanical properties and surface quality of rolled parts. The distribution of hardness in superfcial layer is closely related to the deformation by rolling. To establish the suitable correlation model for describing the relationship between strain and hardness during cold rolling forming process of complex profles is helpful to the optimization of rolling parameters and improvement of rolling process. In this study, a physical analog experiment refecting the uneven deformation during complex-profle rolling process has been extracted and designed, and then the large date set (more than 400 data points) of training samples refecting the local deformation characteristics of complexprofle rolling have been obtained. Several types of polynomials and power functions were adopted in regression analysis, and the regression correlation models of 45# steel were evaluated by the single-pass and multi-pass physical analog experiments and the complex-profle rolling experiment. The results indicated that the predicting accuracy of polynomial regression model is better in the strain range (i.e., ε 1.2) of training samples can be well described by power regression model;so the correlation relationship between strain and hardness during complex-profle rolling process of 45# steel can be characterized by a segmented function such as third-order polynomial in the range ε 1.2;and the predicting error of the regression model by segmented function is less than 10%.

关键词： Complex profle Cold rolling Multi passes Equivalent strain Vickers hardness

Plastic Mechanism of Multi-pass Double-roller Clamping Spinning for Arc-shaped Surface Flange

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Chinese Journal of Mechanical Engineering 2013年第6期26卷 1127-1137页

作者： FAN Shuqin zhao shengdun ZHANG Qi LI Yongyi School of Mechanical Engineering Xi’an Jiaotong University

Compared with the conventional single-roller spinning process, the double-roller clamping spinning（DRCS） process can effectively prevent the sheet metal surface wrinkling and improve the the production efficiency and the shape precision of final spun part. Based on ABAQUS/Explicit nonlinear finite element software, the finite element model of the multi-pass DRCS for the sheet metal is established, and the material model, the contact definition, the mesh generation, the loading trajectory and other key technical problems are solved. The simulations on the multi-pass DRCS of the ordinary Q235A steel cylindrical part with the arc-shaped surface flange are carried out. The effects of number of spinning passes on the production efficiency, the spinning moment, the shape error of the workpiece, and the wall thickness distribution of the final part are obtained. It is indicated definitely that with the increase of the number of spinning passes the geometrical precision of the spun part increases while the production efficiency reduces. Moreover, the variations of the spinning forces and the distributions of the stresses, strains, wall thickness during the multi-pass DRCS process are revealed. It is indicated that during the DRCS process the radical force is the largest, and the whole deformation area shows the tangential tensile strain and the radial compressive strain, while the thickness strain changes along the generatrix directions from the compressive strain on the outer edge of the flange to the tensile strain on the inner edge of the flange. Based on the G-CNC6135 NC lathe, the three-axis linkage computer-controlled experimental device for DRCS which is driven by the AC servo motor is developed. And then using the experimental device, the Q235A cylindrical parts with the arc-shape surface flange are formed by the DRCS. The simulation results of spun parts have good consistency with the experimental results, which verifies the feasibility of DRCS process and the reli

关键词： spinning double-roller clamping multi-pass arc-shaped surface

Effects of sheet thickness and material on the mechanical properties of flat clinched joint

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Frontiers of Mechanical Engineering 2021年第2期16卷 410-419页

作者： Chao CHEN Huiyang ZHANG shengdun zhao Xiaoqiang REN State Key Laboratory of High-Performance Complex Manufacturing Light Alloy Research InstituteCentral South UniversityChangsha 410083China School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China

The flat clinching process is attracting a growing attention in the joining field of lightweight materials because it avoids the geometric protrusion that appears in the conventional clinching process. In this paper, the effects of sheet thickness and material on the mechanical properties of the clinched joint were studied. Al1060 and Al2024 sheets with 2 mm thickness were employed to develop the clinched joint by using different material configurations, and Al1060 sheets with 2.5- and 1.5-mm thicknesses were used to produce the clinched joint by using different thickness configurations. The clinched joints using various sheet configurations were sectioned, and dimensional analysis was conducted. Cross-tensile and shearing tests were carried out to analyze the mechanical properties of the clinched joint, including tensile strength, shearing strength, and absorbed energy. In addition, the failure modes of the clinched joints were discussed. Results indicated that the clinched joint with a stiff top sheet had increased static strength regardless of the test type. The clinched joint with a thick top sheet demonstrated lower static strength than the joint with a thick bottom sheet in the cross-tensile test. However, this result was reversed in the shearing tests. The flat clinching process has a great potential in joining dissimilar and various thickness materials.

关键词： clinched joint flat clinching process thickness configuration material configuration mechanical property

Study of utilizing differential gear train to achieve hybrid mechanism of mechanical press

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Science China(Technological Sciences) 2007年第1期50卷 69-80页

作者： HE YuPeng zhao shengdun ZOU Jun ZHANG ZhiYuan School of Mechanical Engineering Nanjing University of Science&TechnologyNanjing 210094China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China

The problems of hybrid input of mechanical press are studied in this paper, with differential gear train as transmission mechanism. It is proposed that “adjust-able-speed amplitude” or “differential-speed ratio” is the important parameters for the hybrid input mechanism. It not only defines the amplitude of the adjustable speed, but also determines the ratio of the power of the servomotor to the power of the conventional motor. The calculating equations of the ratio of transmission in all axes, the power of two motors, and the working load distribution are deduced. The two kinds of driving schemes are put forward that the servomotor and the conven-tional motor simultaneously drive and the servomotor and the conventional motor separately drive. The calculating results demonstrate that the latter scheme can use much lower power of the servomotor, so this scheme makes manufacture and use cost much lower. The latter scheme proposes a feasible way to apply the hybrid mechanism of mechanical press in practice engineering.

关键词： mechanical press hybrid mechanism differential gear train adjustable-speed

Variation of the friction conditions in cold ring compression tests of medium carbon steel

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Friction 2020年第2期8卷 311-322页

作者： Dawei ZHANG Bingkun LIU Jingxiang LI Minchao CUI shengdun zhao School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049China Key Laboratory of High Performance Complex Manufacturing Central South UniversityChangsha 410083China

Lubrication and friction conditions vary with deformation during metal forming *** macro-variations can be observed when a threshold of deformation is *** study shows that during the cold compression processing of#45(AISI 1045)steel rings,the magnitude of friction and surface roughness(Ra)changes significantly upon reaching a 45%reduction in ring *** example,the Ra of compressed ring specimens increased by approximately 55%immediately before and after reaching this threshold,compared to an 18% or 25%variation over a 35%-45%or a 45%-55%reduction in height,*** ring compression test conducted by this study indicates that the Coulomb friction coefficient and Tresca friction factor mare 0.105 and 0.22,respectively,when the reduction in height is less than 45%;and 0.11 and 0.24,respectively,when the reduction in height is greater than 45%.

关键词： friction condition ring compression test friction calibration curve surface topography

Finite element modeling of counter-roller spinning for large-sized aluminum alloy cylindrical parts

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Frontiers of Mechanical Engineering 2019年第3期14卷 351-357页

作者： Dawei ZHANG Fan LI Shuaipeng LI shengdun zhao School of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 China

Counter-roller spinning (CRS), where the mandrel is replaced by rollers, is an effective means of manufacturing large-sized, thin-walled, cylindrical parts with more than 2500 mm diameter. CRS is very complex because of multi-axis rotation, multi-local loading along the circumference, and radial-axial compound deformation. Analytical or experimental methods cannot fully understand CRS. Meanwhile, numerical simulation is an adequate approach to investigate CRS with comprehensive understanding and a low cost. Thus, a finite element (FE) model of CRS was developed with the FORGE code via meshing technology, material modeling, determining the friction condition, and so on. The local fine mesh moving with the roller is one of highlights of the model. The developed 3D-FE model was validated through a CRS experiment by using a tubular blank with a 720 mm outer diameter. The developed 3D-FE model of CRS can provide a basis for parameter optimization, process control, die design, and so on. The data on force and energy predicted by the 3D-FE model can offer reasonable suggestions for determining the main mechanical parameters of CRS machines and selecting the motors. With the predicted data, an all-electric servo-drive system/machine with distributed power was designed in this work for CRS with four pairs of rollers to manufacture a large-sized, thinwalled, cylindrical part with 6000 mm diameter.

关键词： large-sized cylindrical part counter-roller spinning aluminum alloy finite element method distributed power

Characteristics of surface and subsurface of formed thread parts by axial-infeed thread rolling process

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Chinese Journal of Aeronautics 2023年第3期36卷 471-481页

作者： Shuowen ZHANG Dawei ZHANG shengdun zhao Fei JIANG Myoung-Gyu LEE Xi’an Key Laboratory of Intelligent Equipment and Control School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710049China Department of Materials Science and Engineering Seoul National University08826 SeoulRepublic of Korea

The thread rolling process has been widely applied to manufacture high-performance thread *** this process,the evolutions of surface and subsurface are frequently introduced,which affect the working performance of manufactured *** this study,an axial-infeed thread rolling process(ATRP)is employed,and the macro-meso surface characteristics under different lubrications and operating conditions are ***,the distributions of microstructure and hardness on the subsurface of formed tooth are analyzed in detail,along with the study of stress state and yield strength *** is found that the MoS_(2)grease is more effective in reducing the surface roughness and defects than the lubrication oil and water-base graphite during the ATRP *** rolling speed improves the quality of surface morphology and can reduce the surface *** the subsurface of bottom and flank,intensive shear stress occurs in a narrow region,resulting in the elongation and refinement of the grains and increasing the low angle grain boundary *** on the grain size and plastic strain,the yield strength is *** maximum yield strength and hardness on the bottom of formed tooth are improved by 41.2% and 39.4%,respectively.

关键词： ATRP Lubrication Surface characteristics Microstructure distribution Hardness improvement Grain size

Research on Combined Hot Extrusion Forming Process of Alternator Poles

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Journal of Materials Science and Chemical Engineering 2013年第5期1卷 16-22页

作者： Cheng Yang shengdun zhao School of Mechanical Engineering Xi’an Jiaotong University Xi’an China School of Metallurgical Engineering Xi’an University of Architecture and Technology Xi’an China

Based on the structure analysis of alternator poles, two closed die forging steps in one heat forming process of alternator poles were put forward, as well as the forming die system. Firstly, a thicker bottom base of alternator poles was per-formed by radial forging, then the middle boss and pole claw were forming on the bottom base by backward extrusion. A 3-D coupled thermo-mechanical finite element model was created. The billet deformation, metal flow and forming load were obtained. The results showed that a filling well forging without overlap defects could be obtained by this process, and that?the forming load at the first step increased slowly, but the load increased sharply at the second step when the middle boss was filling completely by the former process. An improved process was put forward, which changed the flow mode in the second forging step, it can considerably reduce the final forging load.

关键词： Radial Forging Backward Extrusion Alternator Poles Closed Die Forging