Table of Content

10 January 2023, Volume 34 Issue 01

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Research on Tool Tip Frequency Response Prediction of Robot Milling Systems Considering Characteristics of Spindle-toolholder Interface

LIANG Zhiqiang, SHI Guihong, DU Yuchao, YE Yuling, JI Yongjian, CHEN Sichen, QIU Tianyang, LIU Zhibing, ZHOU Tianfeng, WANG Xibin

2023, 34(01):  2-9.  DOI: 10.3969/j.issn.1004-132X.2023.01.001

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Aiming at the problems that the tool tip frequency response of robot milling systems was posture-dependent, which made it difficult to accurately predict the stability and effectively control the machining chatters in the process of robot pose changing, a prediction method of the tool tip frequency response of robot milling systems was proposed considering the contact stiffness of spindle-toolholder interface. Based on Euler-Lagrangian method and unit area method of Yoshimura, the dynamics model of robot body and the contact stiffness model of spindle-toolholder interface were constructed, respectively. Then, based on the theory of the main and auxiliary degrees of freedom of finite element, the dynamics model of robot body and the contact stiffness model of spindle-toolholder interface were combined to construct the prediction model of tool tip frequency response of robot milling systems. The verification test of tool-tip frequency response prediction under different postures of the robot was carried out. The results show that the maximum error of the natural frequency is as 6.63% and the maximum error of the corresponding amplitude is as 9.80% compared with the frequency response function of tool-tip obtained by simulations and experiments, which verifies the accuracy of the proposed prediction model and proves that the model may realize accurate prediction of frequency response function under any postures of the robot.

Research on Prediction and Control Method of Workpiece Tooth Flank Texture during Internal Gear Power Honing

HAN Jiang, LI Zhenfu, TIAN Xiaoqing, FEI Ningzhong, XIA Lian,

2023, 34(01):  10-16.  DOI: 10.3969/j.issn.1004-132X.2023.01.002

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Taking the internal gear power honing process as the object, the formation mechanism of the honing texture of the workpiece tooth flanks was studied, the honing texture was predicted, and an active control method of the honing texture was proposed. Firstly, a tooth flank contact line model of the workpieces was established to simulate the honing process. Secondly, the principle of the honing wheel dressing process was studied, and the mapping relationship between the honing speed and the machining texture was obtained. Since the honing speed was controlled by the parameters such as center distance and the cross-axis angle of the workpiece gear and the honing wheel, a control method for the distribution and change trend of the tooth flank texture of the workpieces was proposed, taking the cross-axis angle and the center distance as the control objects. Finally, the gears were machined with different processing parameters, and the three-dimensional morphology of the tooth flanks were detected. The measured results of the machined tooth flanks are highly consistent with that from the prediction models, which show the method herein may realize the texture control of gear honing. 

Analyses of Friction and Sealing Characteristics of Piston/Bushing Interfaces Considering Elastic Deformations#br#

HANG Yang, YAN Kanghao, HUANG Dan

2023, 34(01):  17-26.  DOI: 10.3969/j.issn.1004-132X.2023.01.003

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Considering the rough surface contacts and elastic deformations of the piston bushing in the radial piston pumps， the theoretical model was established for the piston/bushing interfaces under the mixed-elastohydrodynamic lubrication conditions. The effects of elastic deformations and surface morphology caused by different inlet pressures and cam speeds on the friction and sealing characteristics were analyzed， through the co-simulation of MATLAB and ANSYS， and the combination between the finite-differential method and finite-element method. The results show that the elastic deformations of piston bushing have significant influences on the contacts of micro-convex bodies in the piston/bushing interfaces， which is related to the inlet pressures and cam speeds. The elastic deformations and surface morphology may affect the friction power losses and leakage as well， and the former is the greater one. Besides， the friction and sealing characteristics of the piston/bushing interfaces are sensitive to the working conditions， and the friction power losses， the couette flows and the poiseuille flows raise in varying degrees with the increases of inlet pressures or cam speeds. 

Analysis on Grasping Ability for a Soft Robotic Hand with Structural Decoupling of Actuator and Variable Stiffness Mechanisms

YIN Haibin, TAO Jian, LI Qian, ZHOU Jia,

2023, 34(01):  27-35.  DOI: 10.3969/j.issn.1004-132X.2023.01.004

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 To realize the accurate grasp of soft hand with variable stiffness， a soft robotic finger with the structural decoupling of actuator and variable stiffness mechanisms was designed. The fingertip force models of soft finger were built and the fingertip forces of finger were calculated. The comparison between the experimental results and simulation ones of the fingertip forces validated that the grasping models might accurately predict the grasping behavior within a certain range of deflections. The structure sizes of the soft robotic hands were designed based on the fingertip force models of the soft finger. According to the designed structure of the soft robotic hands， the grasping ability of the finger pulp was further studied， and eventually the grasping force models of the finger pulp grasp of the soft robotic hand were obtained through the mutual verification of simulation and experiment. Simulation and experimental results show that the grasping capability of soft robotic hands was related to the stiffness of fingers， actuating ability from deformation and the grasping types. 

Characteristics Analysis and Parameters Matching of a Novel Seat with Quasi-zero-stiffness Nonlinear Suspension

ZHAO Leilei, YU Yuewei, CAO Jianhu, GAO Shangpeng, ZHOU Changcheng, YUAN Jian

2023, 34(01):  36-46.  DOI: 10.3969/j.issn.1004-132X.2023.01.005

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To effectively solve the problems of poor comfort of linear seats and high cost and poor reliability of nonlinear seats， a new nonlinear suspension seat was proposed based on the link-scissor mechanism. The model was established by using the quasi-zero-stiffness theory. The variable bearing characteristics， low-frequency vibration isolation characteristics， their influence laws and the feasible design domain of the key parameters were revealed. Then， the analytical matching method of the spring stiffness and the nonlinear damping matching model of damper were proposed. The correctness of the method and the vibration isolation capability were verified by the prototype tests comparison. The results show that the comfort of the new seat is 35% higher than that of the traditional linear seat and is equivalent to that of the traditional nonlinear seats. Moreover， the cost is half lower than that of the traditional nonlinear seats， and the comfort under the failure conditions is more than 14% higher than that of the traditional nonlinear seats. 

Investigation and Application on Overall Design Method of Complex Electromechanical Systems

YANG Shixiang, LI Wenqiang, SHAO Zhehui,

2023, 34(01):  47-54.  DOI: 10.3969/j.issn.1004-132X.2023.01.006

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Complex electromechanical systems embodied the features of diverse design needs, complex structures and redundant information. To improve the quality and efficiency of overall design, a systematic method combined with QFD, AD and Petri net was put forward for overall design of complex electromechanical systems. Based on the transformation relationships of the design information from customer requirements to functional design, physical structures, and processing scenarios, innovative design methods were integrated effectively, which guided the establishment of a standardized design processes including requirement analysis, function-structure mapping, and process layout for complex electromechanical systems. Effectiveness and practicability of the method herein were verified by the overall design processes of an intelligent dusting and bagging system.

Design,Analysis and Optimization of a Cone External Surface Mounting Manipulator

HE Yufan, SUN Jianghong, GAO Feng, LI Naizheng, HE Xueping, WANG Junjian

2023, 34(01):  55-64.  DOI: 10.3969/j.issn.1004-132X.2023.01.007

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A series manipulator end-effector was designed for cone surface mounting. Firstly, the space analysis of the cone was carried out. According to the geometric characteristics of the cone, the mounting technology scheme was determined and the configuration design was obtained. Secondly, the structural design of the manipulator was completed. Lagrange method was used to derive the dynamics equation, and D-H method was used to solve the forward and inverse kinematics. Then, NSGA-Ⅱ genetic algorithm was used to optimize the structural dimensions of the high-load parts of the actuator, and the finite element analysis of the parts before and after optimization was compared. Finally, the feasibility of manipulator was verified by comparing the results of virtual prototype and prototype dynamic experiments, and the external influence factors were analyzed. The feasibility of manipulator was proved and the direction for the subsequent improvements was provided.

Thermo-mechanics Coupling Model and Experimental Research of Longitudinal Torsional Ultrasonic Grinding of TC4 Titanium Alloys

2023, 34(01):  65-74.  DOI: 10.3969/j.issn.1004-132X.2023.01.008

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 In order to explore the thermo-mechanics coupling mechanism in the longitudinal torsional ultrasonic grinding of TC4 titanium alloys， the thermo-mechanics coupling models were established based on the TC4 titanium alloy longitudinal torsional ultrasonic grinding force models， workpiece surface average temperature models， specific heat capacity calculation expressions. The finite element simulation of the TC4 titanium alloy longitudinal torsional ultrasonic single abrasive particle removal processes under the coupling of force and heat was carried out to analyze the interaction characteristics of the grinding forces and the grinding temperature. Theoretical and simulation studies show that the severe temperature rises in the grinding zones may reduce the ability of the titanium alloy to resist plastic deformations and to inhibit the growth rate of the grinding forces. Finally， it was verified by the longitudinal torsion ultrasonic grinding tests of TC4 titanium alloys. The results show that the introduction to ultrasonic vibration may significantly reduce the grinding forces and grinding temperature， and the reduction of grinding forces and grinding temperature reach 19.39% and 12.41% respectively. Grinding temperature increases with the increases of grinding depth， grinding wheel speeds and workpiece feed speeds. And with the increases of grinding temperature， the growth trend of grinding forces slows down. The decreases of grinding forces and grinding heats reduce the plastic deformations of the  workpiece surfaces and the height of the plastic bulge on both sides of the furrow. Compared with ordinary CBN grinding， the introduction to longitudinal torsional ultrasonic may reduce the surface roughness by 31.21%. Increasing the ultrasonic amplitude within a certain range may significantly improve the grinding quality of the workpiece surfaces. 

Effects of Surface Treatment on Surface Integrity and Cutting Performance of TiAlSiN Coated Cutting Tools

WU Zhenyu, ZHENG Guangming, YAN Pei, YANG Xianhai, ZHAO Guangxi, LI Xuewei

2023, 34(01):  75-83.  DOI: 10.3969/j.issn.1004-132X.2023.01.009

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Coated tools were prone to severe tool wear and short tool life when dry cutting titanium alloys at high-speed. The surface treatment of coated tools, which might improve the surface integrity of coated tools, was an effective way to improve the wear resistance and cutting life of coated tools. The TiAlSiN coated tools were selected and treated by cryogenic treatment, micro-sandblasting treatment and cryogenic + micro-sandblasting respectively to study the effects of different treatment methods on the surface integrity of the coated tools (including surface morphology, surface roughness, micro-hardness and surface residual stress, etc.). High-speed dry cutting experiments of titanium alloys were carried out to analyse the effects of different treatment methods on the cutting performance of coated tools and to investigate ways to improve the wear resistance and cutting life of coated tools. The results indicate that compared to the single cryogenic treatment and micro-sandblasting treatment, the surface integrity of the coated tool is significantly improved and tool life is significantly increased with cryogenic + micro-sandblasting treatments. Cryogenic + micro-sandblasting treatments may reduce tool chipping, crater wear and abrasive wear, and effectively improve the wear resistance of coated tools. 

Constant Partial Frequency and Constant Height Design of Nonlinear Commercial Vehicle Bionic Suspensions

SONG Yong, LU Hao, LI Zhanlong, YAN Bijuan, MENG Jie, LIAN Jinyi

2023, 34(01):  84-94.  DOI: 10.3969/j.issn.1004-132X.2023.01.010

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Aiming at the problems of poor vehicle ride comfort during variable sprung mass of commercial vehicle suspensions based on full-load design, a design scheme of constant partial frequency and constant height was proposed based on double diamond-shaped kangaroo leg suspensions(bionic suspension). The scheme was researched, analyzed and evaluated to improve the ride comfort of commercial vehicles. Through the analysis of statics characteristics, the elastic characteristics and stiffness characteristics of the bionic suspensions were obtained, and the constant partial frequency and constant height design was carried out. It is found that the bionic suspension has ideal nonlinear elastic characteristics and stiffness characteristics. Compared with the linear suspensions, it has more dynamic capacity and strong anti-breakthrough ability. The initial angle and stiffness ratio of the suspensions have important impacts on the characteristics and stroke range. By adjusting the initial angle of the bionic suspensions, the constant partial frequency and constant height design maybe realized for different sprung mass, which shows the proposed scheme is feasible. The simulation analysis results show that under different road grades(B, C, D) and different vehicle speeds(40~100 km/h), the body acceleration root mean square value is significantly reduced compared with before design, and the ride comfort is effectively improved after the constant partial frequency and constant height design for the commercial vehicle bionic suspensions. After the design of constant partial frequency and constant height, under different road conditions, the no-load and half-load vertical acceleration root mean square values of the bionic suspension experimental test model are decreased by 20.6%~28.3% and 12.1%~20.4% respectively compare with before design, which verified the correctness and effectiveness of the design schemes of constant height and constant partial frequency.

Preparation Method and Directional Adhesion Properties of Bio-inspired Wedge Arrays

LIU Yanwei, ZHOU Qiang, PAN Hao, LI Pengyang, LI Shujuan

2023, 34(01):  95-101.  DOI: 10.3969/j.issn.1004-132X.2023.01.011

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In order to solve the problems of low efficiency and complex processes of preparing directional adhesive arrays using disposable wax mold or photolithography, an efficient preparation process of wedge-shaped micro structure arrays was proposed based on micro-nano 3D printing technology, and the prepared wedge-shaped array material possessed good adhesion properties and directional adhesion properties. First, the bio-inspired wedge array adhesion structure with directional characteristics was designed. Then, the corresponding micro-structure array mold was fabricated by micro-nano 3D printing technology, the preparation processes of the bio-inspired adhesive material were developed, and the contour accuracy of the wedge-shaped structure was analyzed. Finally, an experimental test platform was constructed to study the influences of shear direction, shear distance, preload, desorption speed and other factors on the adhesion performance. The results demonstrate that the bio-inspired wedge-shaped array adhesive materials have significant directional adhesion properties, which verify the feasibility of the micro-nano 3D printing technology in preparing bio-inspired directional dry adhesive materials.

An Electro-permanent Magnet Blank Holder Method Considering Influences of Magnetic Field Region

SHI Rui, QIN Siji, PAN Ziji, CHEN Haodong, LI Xueyang

2023, 34(01):  102-108.  DOI: 10.3969/j.issn.1004-132X.2023.01.012

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 Considering that the EPM blank holder method had the advantages of independent loading, short transmission chain, energy saving and easy control, a new electronically controlled permanent magnet blank holder method with overlap of forming area and magnetic field area was proposed for ferromagnetic sheet forming. Taking the deep drawing of cylindrical parts as an example, the magnetic-mechanics coupling finite element simulation of structural deformations was carried out under different blank holder force loading conditions by using the newly designed blank holder device. And the influences of slab magnetism on the distributions of magnetic fields and blank holder forces were analyzed. The analysis results reveal that the stiffness of newly designed blank holder force loading devices is significantly improved, the new blank holder method has better blank holder effectiveness, and the die structure is more compact. According to the simulation and theoretical analysis results, a deep drawing experimental device was designed and manufactured. The experimental results show that the method of electronically controlled permanent magnet blank holder with the overlap the forming areas and magnetic field areas is completely feasible.

Study on Offset Mechanism and Adaptive Fuzzy Control Method for Radial-axial Ring Rolling Processes of Super Large Rings

ZHANG Ke, WANG Xiaokai, HUA Lin, HAN Xinghui, NING Xiangjin,

2023, 34(01):  109-117.  DOI: 10.3969/j.issn.1004-132X.2023.01.013

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During the radial-axial ring rolling processes of super large rings, the rings offset was easy to appear, which might affect the rolling stability and forming quality. To study the rolled rings offset mechanism and the control method,the law of distribution changes of the forward slip zones and the back slip zones in the axial rolls slip zones was analyzed.The rotational kinematic conditions of the axial roll without rings offset were established under ideal states and the optimal velocity matching coefficient in the slip regions was obtained. In addition, after summing up the experience of manual control from the historical ring rolling data,a control method of ring center offset was put forward based on adaptive fuzzy adjustment of axial rolls rotational speed. Based on ABAQUS software and the VUAMP subroutine, the finite element model of radial-axial ring rolling with an integrated fuzzy control algorithm for ring center offset of a 10 m super large ring was established and the variation law of the ring center offset under the conventional control and the adaptive fuzzy control with the optimal velocity matching coefficient was studied. The results show that,compared with the conventional control, the average ring center offset of the adaptive fuzzy control is reduced by 72.4%. The simulation results and experimental data verify the effectiveness of the proposed adaptive fuzzy control method for super large ring rolling processes which has rings offset.

Study on Performance of Digital Extrusion Gradient Sand Mold and Distance of Supplementary Pressure

JIANG Erbiao, SHAN Zhongde, CHENG Guang, YANG Haoqin

2023, 34(01):  118-125.  DOI: 10.3969/j.issn.1004-132X.2023.01.014

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As a new forming process for patternless casting, the extrusion-milling forming technology broke through the conventional sand mold manufacturing method and provided a new notion for the preparation of gradient sand molds. In the processes of gradient sand molds, the supplementary pressure on the surface layers of the sand mold would cause changes in the strength, permeability and thickness of the surface layers, which in turn would affect the casting performance. For this problem, the strength, air permeability and cutting force of the gradient sand molds with different cavity depths were studied. It is found that the distance of supplementary pressure has a great impact on the performance of the sand mold. In the 2~12 mm range of supplementary pressure distance, the larger the distance, the higher the strength, the smaller the air permeability, the higher the hardness and the greater the cutting force. Considering the air permeability, strength and cutting force of the sand mold surface layers, the optimal supplementary distance for different cavity depths was obtained. Finally, the superiority of gradient sand mold was verified by the ZL114A aluminum alloy casting tests.