Table of Content

25 November 2022, Volume 33 Issue 22

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A Collision Detection Method of Heavy-duty CNC Machine Tools Based on Digital Twin

JIANG Xuemei, YUAN Zihang, LOU Ping, ZHANG Xiaomei, YAN Junwei, HU Jiwei,

2022, 33(22):  2647-2654，2663.  DOI: 10.3969/j.issn.1004-132X.2022.22.001

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At present, the collision detection of CNCMTs usually used the basic simulation function of the CNC system to detect machining G codes, which only considered whether there were collisions between the tool and the ideal workbench, or the tool and fixtures on the tool path during the processes. It was difficult to meet the actual dynamic processing environments, clamping mode and fixture change of open heavy-duty machine tools. So the digital twin was introduced into the collision detection of open heavy-duty CNCMTs, and a perception-evolutionary prediction-feedback collision detection framework was constructed. By constructing digital twin of CNCMTs and dynamically sensing machining elements such as workpieces ，fixtures and cutting tools, the evolution of the digital twin should be driven by perception data, and the potential interference phenomenon would be predicted in the machining processes. Thus, the efficiency of the CNCMTs was improved, and the potential harm was avoided. The method was applied to the collision detection of heavy-duty CNC gantry boring and milling machine ZK5520, and the effectiveness and feasibility of the proposed method were proved.

Linear Corner Asymmetry Smoothing Planning under Kinematics Constraints

HE Yulong, JU Changjiang, YANG Genke, WANG Chengguang,

2022, 33(22):  2655-2663.  DOI: 10.3969/j.issn.1004-132X.2022.22.002

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In order to realize the continuous smooth feeds at the straight-line corners in CNC machining, a kind of asymmetric smooth machining planning method for the straight-line corners was proposed. Aiming at the situations where the initial and final velocities and accelerations of the corners were different, the kinematics and geometric error constraints at the straight-line corners were considered, and the solution of the high-order corner model to a linear programming problem was simplified, which might directly solve the corner parameters , realize the advanced simultaneous planning for rate smoothing and tool path smoothing improves planning efficiency and processing efficiency. The simulation comparison experiments with the symmetric corner smoothing show that the proposed method may ,and improve the efficiency and accuracy while ensuring the smooth machining processes. The motion platform prototype experiments verify the feasibility of the proposed method.

Effects of Wheel Tread Out-of-roundness on Wheel-rail Interface Adhesions and Wheel Surface Damages of High-speed Trains#br#

SHEN Mingxue, RONG Bin, LI Shengxin, ZHAO Huoping, JI Dehui, XIONG Guangyao

2022, 33(22):  2664-2672,2683.  DOI: 10.3969/j.issn.1004-132X.2022.22.003

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The tribological tests of wheel/rail roll-slip contacts with or without eccentric wheels were carried out on the dual-mode rolling contact fatigue/wear testbed (JD-DRCF/M type). The effects of first-order out-of-round wheels and normal circular wheels on wheel/rail interface adhesions, wheel surface damages and rolling contact fatigue characteristics were compared and analyzed. The results show that the non-roundness of the wheel may significantly reduce the wheel-rail adhesion coefficient, and their wheel-rail adhesion coefficient is less than 0.2 under the wet conditions, which may affect the safe operations and traction effectiveness of trains. The non-roundness of the wheel significantly aggravates wear of the rail and causes obvious difference in wheel surface damages along the circumferential direction. Specifically, the characteristics of fatigue delamination and tearing fracture are most obvious on the convex sides of the wheels. Generally, the surface delamination and pitting are more serious and the fatigue crack propagation angles are larger on the sides facing the convex than that on the sides away from the convex, but the more adhesive layers are accumulated on the sides away from the convex. In addition, the surface roughness, hardness and thickness of plastic deformation layers on the wheels gradually increase at first from the wheel rolling radius rθ changes from the minimum value to the maximum value and then to the minimum value along the circumferential direction, and then gradually decrease after going around the convex.

Nonlinear Robust Fusion Estimation of Centroid Sideslip Angle and Tire Lateral Forces for Four-wheel-drive Electric Vehicles

WANG Fanxun, YIN Guodong, SHEN Tong, REN Yanjun, WANG Yan, FENG Bin

2022, 33(22):  2673-2683.  DOI: 10.3969/j.issn.1004-132X.2022.22.004

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It was rather difficult to measure the centroid side slip angle and the tire lateral forces of the four-wheel-drive electric vehicles directly. Considering the unmodeled dynamic characteristics of the systems, model parameter perturbations, system process noises and measurement noises, a joint estimation method was proposed based on FFRLS and RCKF. Based on applying FFRLS to estimate the mass of the vehicle in real time and the estimation error minimization in the background of the maximum value embedded into the standard cubature Kalman filter to realize RCKF. The improved strategy of the joint estimation algorithm was proposed, which effectively improved the anti-interference ability of the filter to the model parameter perturbations and the unmodeled noises under composite conditions. It may  realize the accurate estimation of the centroid sideslip angle and tire lateral forces. By CarSim/Simulink, the accuracy, robustness and anti-interference of the algorithm were verified in different conditions. Through the actual vehicle platform of four-wheel-drive electric vehicle, the validity of the algorithm was verified. Research show that the results of the proposed method are more accurate than that of RCKF and the standard Cubature Kalman filter. The problems of joint estimation of centroid side slip angle and tire lateral forces of four-wheel-drive electric vehicle are solved under composite conditions.

Research on Backlash Elimination Method of Dual-motor Precision Transmission Mechanisms

ZHENG Jieji, CHEN Lingyu, FAN Dapeng, XIE Xin

2022, 33(22):  2684-2692.  DOI: 10.3969/j.issn.1004-132X.2022.22.005

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Aiming at the problems of large speed fluctuation and impact caused by the gaps between the two transmission chains of the dual-motor precision transmission mechanisms, the method of eliminating the gaps of the system was studied. First, a mechanism dynamics model including the meshing clearances between the output gear of the planetary reducer and the large ring gear was established. Through the model simulation, the influences of the gap size on the system characteristics were analyzed. Then, a compound anti-backlash method was proposed combining dynamic bias torque based on speed command and cross-coupling synchronous control based on differential negative feedback. An experimental device for dual-motor precision transmission mechanisms was built, and the verification experiments of the anti-backlash method were carried out. The experimental results show that in the case of closed-loop speed, the proposed compound anti-backlash method may ensure the complete elimination of the system gaps, and may improve the system speed tracking accuracy by 73.38%, and the shock amplitude in the start-up phase may be attenuated by 76.35%. The research results lay a certain foundation for the research of the high-precision control method of the double-motor precision transmission mechanisms, and provide a reference scheme for the elimination of the gaps in the gear transmission systems. 

Optimization of Planetary Roller Screw Tolerance Matching Based on Machining Error Sensitivity Analysis and Fuzzy Analytic Hierarchy Processes

WU Hanlin, WEI Peitang, CAI Lei, HU Rui, LIU Huaiju, DU Xuesong, ZHU Caichao, LIU Lang

2022, 33(22):  2693-2703.  DOI: 10.3969/j.issn.1004-132X.2022.22.006

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The active design of PRSM tolerance was essential to improve the transmission performance and processing feasibility. A PRSM travel error and axial clearance model was established by integrating the thread coaxiality errors, pitch errors and mid-diameter errors of the screw, roller and nut, and the sensitivity index of each error factors was calculated. Based on the expert judgment hierarchical analysis method of triangular fuzzy number, processing weights, and initially assigning the tolerance of each error terms of PRSM travel accuracy were calculated. The tolerances of each error terms of axial clearance tolerances were optimized based on the sequential quadratic programming algorithm. And the effectiveness of the method was verified by taking the standard PRSM as an example. The results show that the method of optimizing the tolerances of each error terms for the stroke accuracy and axial clearance balances the stroke accuracy and axial clearance extremely well, and relaxes the width of the key tolerance zones, which improves the machining feasibility of the parts. The example shows that after optimization, the minimum value of axial clearance in the complete cycle is changed from -25 μm to 0 to avoid thread interference; after optimization, the amount of V300 stroke variation is basically unchanged, and the width of tolerance zone is increased by 65% on average, which ensures PRSM grade 5 accuracy index, improves the machining feasibility of key parts, reduces machining costs and may provide reference for PRSM tolerance active design theory.

Design of Hobbing Motion Chamfering Tools for Cylindrical Gears

HE Kun, HE Xiaohu, DU Yanbin

2022, 33(22):  2704-2710.  DOI: 10.3969/j.issn.1004-132X.2022.22.007

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Aiming at the high-speed tooth profile chamfering requirements of cylindrical gears in actual productions, a new method of continuous cutting hobbing motion chamfering was proposed, and the profile design of the hobbing motion chamfering tools was completed. First, referring to the hobbing motion of cylindrical gears, the initial position relationship between the tool and the gear and the tool installation pose coordinate system were established, and the tool installation pose parameters were calculated through the chamfering parameters and the established installation pose coordinate system. Secondly, according to the chamfering motion and tool installation pose, a spatial motion coordinate system and derive the transformation relationship between the coordinate systems, and a tool profile calculation method was established by continuously solving the contact point between the tool rake face and the gear chamfering target profiles. Finally, a certain type of cylindrical helical gear was selected as the chamfering object. The three-dimensional modeling of the gears and the hobbing motion chamfering tools was completed by the cutting simulation software, and the chamfering cutting simulation was realized by writing the simulation motion program, the processing experiments were performed by chamfering machine. The simulation and experimental results show that the designed chamfering tool may meet the requirements of efficient tooth profile chamfering of cylindrical gears, and the correctness of the tool profile calculation method is also verifies.

Modeling of Material Removal Depth in ABFW Polishing Based on Modified Preston Equation

ZHANG Junfeng, SHI Yaoyao, LIN Xiaojun, WU Xiaojun

2022, 33(22):  2711-2716.  DOI: 10.3969/j.issn.1004-132X.2022.22.008

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Due to the elasticity of ABFW, the actual material removal depth was not consistent with the nominal polishing depth, which directly affected the control of polishing efficiency and surface quality. Based on the Hertz elastic contact theory, the distribution function of polishing pressure and cutting speed in the contact area was established, and the material removal depth model was established according to the modified Preston equation. Based on this, the key processing parameters that affected the material removal depthi.e、abrasive particle size, spindle speed, ABFW deformation and feed rate were determined. Then, the distribution of material removal depth in contact areas and the influences of key polishing process parameters on the material removal depth were obtained. Finally, the correctness of the model and the influence law were verified by simulation and polishing experiments, the results show that the model may better predict the material removal depth of ABFW polishing. 

Green Design Knowledge Expression and Acquisition Method under Product Performance Association

KE Qingdi, SUN Boao, XUE Bing, ZHANG Lei, CHEN Pengfei

2022, 33(22):  2717-2726.  DOI: 10.3969/j.issn.1004-132X.2022.22.009

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In the environments of big data and networking, designers could not effectively utilize the massive information and data of electromechanical product design to meet the demands of green design in the whole life cycle of electromechanical products. To solve this problem, a method of green design knowledge expression and acquisition was proposed based on lifecycle performance association. Firstly, the basic operation-product-performance(OPP) relational architecture was established, and the green design knowledge expression oriented to the requirements of green design in life cycle was proposed, and the normalized expression of each element in the structure was proposed. Secondly, synonym forest and similarity analysis were used to annotate the design information and data, and a basic association dictionary was constructed based on OPP architecture. A green design knowledge acquisition method was proposed based on green association degree. Finally, an example of hydraulic valve parts in electromechanical products was given to verify the validity of the proposed green design knowledge expression and acquisition method. The results may realize multi-level and multi-granularity expression and effective acquisition of green design knowledge, and provide basic method support for the practical applications of green design in the whole life cycle of electromechanical products.

Energy Consumption Prediction Method for Industrial Robots

TUO Junbo, PENG Qiuyuan, ZHANG Xianmin, LI Congbo

2022, 33(22):  2727-2732,2740.  DOI: 10.3969/j.issn.1004-132X.2022.22.010

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Aiming at the defects of complex models, cumbersome operation and high cost of traditional energy consumption prediction methods for industrial robots, a meta-action-based energy consumption prediction method for industrial robots was proposed from the perspective of motion trajectory and action mode of end-effector. First, the meta-actions and energy consumption characteristics of static operations and dynamic operations of industrial robots were analyzed in the first place, and the energy consumption function of static meta-action and dynamic meta-action like axial motion and rotation et al, were built. Then, the motions of the target processes were disassembled based on the proposed meta-action library and the energy sonsumption calculation model of each meta-motion was built. Finally, energy consumption of industrial robots at target processes was realized by combining the energy consumption functions and calculation models. By applying the proposed method, the energy consumption prediction may be realized by disassembling operation processes as long as the energy consumption function of each meta-action was established by measuring meta-action power in advance, so the method has broad application prospects.

Study on Chip Forming Characteristics of Orthogonal Cutting of PTFE Materials

NI Jing, SUN Jingbo, HE Lihua, CUI Zhi, XUE Fei

2022, 33(22):  2733-2740.  DOI: 10.3969/j.issn.1004-132X.2022.22.011

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In order to study the chip formation mechanism of PTFE materials in cutting processes, single factor orthogonal cutting experiments and quasi-static mechanics experiments were designed. Firstly, cutting speed and cutting thickness were taken as variables, the continuous chip and chip edge forming mechanism of PTFE materials were proposed based on the shear plane theory and fracture theory. Secondly, by analyzing the height and spacing of the edges, the influences of cutting parameters on the edge morphology were explored. Finally, the fractal theory was used to analyze the cutting force stability, revealing the relationship among the number of burrs, frequency and cutting force stability. The results show that the PTFE continuous chips are generated because the true compressive strain of the materials does not exceed the fracture yield strain in the cutting processes. The burrs are produced because of the nucleation and propagation of cracks at the lamellar structure of the chip edges. In addition, cutting parameters will affect the generation of burrs, when the cutting speed is as 100 mm/min and the cutting thickness is as 0.3 mm, the number of chip edges is the least, the frequency is the smallest and the cutting force is the most stable. The research results may provide reference for the edge suppression and surface processing quality optimization of PTFE materials in cutting processes. 

Rebound Law and Precision Compensation Method of Three-dimensional Laser Cutting of High Strength Steel Hot Stamping Structural Parts

LI Shougang, LIU Peng, LIU Xiang, HU Zhili,

2022, 33(22):  2741-2747.  DOI: 10.3969/j.issn.1004-132X.2022.22.012

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In order to reduce the influences of springback defects on the cutting accuracy in the three-dimensional laser cutting of high-strength steel body structures, the rebound characteristics was studied by applying three-dimensional laser cutting of hot stamped high-strength steel body components.For high-strength steel car body structure A-pillar, hot stamping and laser cutting finite element models were established respectively by the finite element simulation software AUTOFORM and ABAQUS respectively. The rebound value distribution diagram was obtained through numerical simulation, and the rebound law of the contour of the body structures after cutting was found. The optimal cutting contour was determined according to the direct compensation method based on rebound prediction. The compensation method was validated by cutting the A-pillar semi-finished products. The results show that the contour may be controlled within the tolerance range, the contour errors are decreased by about 28.5%, and the profile rebound is decreased by about 38.3%，by the proposed compensation method,which verify the effectiveness of the compensation method.

Hybrid of Self-resistance Electric Heating and In-situ Membrane Heating of CF/PEEK Composites Consolidation

TAO Shuangquan, HAO Xiaozhong, YANG Zijian, LIU Shuting

2022, 33(22):  2748-2754.  DOI: 10.3969/j.issn.1004-132X.2022.22.013

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Carbon fiber reinforced polyetheretherkatone composites (CF/PEEK) had low density, high toughness, high fatigue strength, and could be recycled. However, the melting temperature of PEEK was extremely high(>340 ℃), so as the melting viscosity(>1000 Pa·s). Meanwhile, the melting-ablation process temperature window of PEEK was narrow, the consolidation of CF/PEEK parts was difficult. This paper proposed a new heating method of CF/PEEK composites, as the combination of self-resistance electric heating and in-situ membrane heating method. The authors introduced the in-situ membrane heating to compensate the heat dissipation, achieve the uniformly temperature field distribution. Finite element simulation and experimental results verify the effectiveness of the proposed method Compared with the pure self-resistance electric heating method, the temperature uniformity of the parts is increased by 75%, the crystallinity is increased by 16.2%. The high efficiency, uniformly heating of CF/PEEK composites are achieved.

Failure Analysis of a Rolling Sealed Wall Climbing Robots

LIU Zhihui, CAI Wei, FU Xingwei, YUAN Bingbing, WANG Hongguang, SONG Yifeng,

2022, 33(22):  2755-2763,2771.  DOI: 10.3969/j.issn.1004-132X.2022.22.014

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The sealing structure was the core component that kepts the wall-climbing robot running. As a new type of sealing structure with the characteristics of good wear resistance, large load, and strong wall adaptability, was increasingly studied in the field of wall-climbing robots. The failure criterion of the rolling seals under typical working conditions was proposed based on the research of the rolling seal mechanism. The failure mode of the rolling seal structure was obtained by analyzing the sealing mechanism. The specific failure modes under the three typical working conditions of horizontal translation, vertical translation, and steering were analyzed. Then the relationship between key design parameters and seal leakage was established based on the dynamics method and based on these analyses, the failure criterion of the rolling seal was proposed. Eventually, the prototype improvement and experiments were completed based on the proposed failure criterion. The experimental results show that the enhances design improves the adsorption stability, which verifies the validity and accuracy of the rolling seal failure criterion. 

Study on Levitation Characteristics of High Temperature Superconducting Pinned Maglev Train

ZHANG Mingliang, LI Mingyuan, LIU Pengfei, YAN Yangyang, LIU Liru, YANG Xinmeng

2022, 33(22):  2764-2771.  DOI: 10.3969/j.issn.1004-132X.2022.22.015

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Facing the magnetic rail relationship of high temperature superconducting levitation train, the suspension force characteristics between dual-peak permanent magnetic orbit and high temperature superconducting block combination were tested at different field cold heights, and it is found that the magnitudes of suspension forces first increase then decrease as the distance increases, and existe the obvious hysteresis characteristics. In order to optimize the parameters of high temperature superconducting block combination and permanent magnetic track pair, the equivalent processing method for high temperature superconducting block was proposed based on image dipole model. The simulation model was established in order to obtain the trapped magnetic fields. The attractive force and repulsive force of the combination of high temperature superconductor block combination were calculated by way of trapped magnetic field and low relative permeability, and the relationship between suspension force and suspension gap at different field cold heights was gained. The results show that the simulated results are in good agreement with experimental ones at position of near different field cold heights, which verifies the equivalent processing method. The aim of paper is to provide a simple and effective method for the suspension force calculation of high temperature superconducting flux pinned magnetic levitation trains.