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Effect of tempering on bonding characteristics of cross wedge rolling 42CrMo/Q235 laminated shafts

Journal of Iron and Steel Research International 2020年第10期27卷 1170-1178页

作者： Shuai Zhu Wen-fei Peng Xue-dao Shu Zhejiang Provincial Key Laboratory of Part Rolling Technology Ningbo UniversityNingbo 315211ZhejiangChina

To further improve the comprehensive properties of 42CrMo/Q235 laminated shafts produced by cross wedge *** treatment of the shafts was *** and bending tests were carried out to compare the changes in mechanicalproperties before and after heat *** results showed that the interfacial bonding strength increased most aftertempering at 350℃for 45 *** microstructure of the interface was observed using a digital *** resultsshowed that the dispersed oxides on the interface were basically eliminated by using the scheme of tempering at 350 cand holding for 45 *** reasons for the change in mechanical properties were explained from the point of theinterfacial *** electron microscopy was used to analyze the micro-morphology of the tensile *** was observed that after tempering at 350℃and holding for 45 min,the dimple holes became larger and deeper,and thestructure of fracture became more uniform and *** the point of the tensile fracture *** reasons for thechange in mcchanical propcrties wcrc explained as well.

关键词： Heat treatment Cross wedge rolling Interface Microstructure Fracture morphology

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Concept system and function of dynamic symmetry in mechanical product structure

引用

Open Mechanical Engineering Journal 2015年第1期9卷 47-51页

作者： Liu, Fan Ma, Zhiyong Zhejiang Provincial Key Lab of Part Rolling Technology Ningbo University Ningbo China

Dynamic symmetry is a common phenomenon in mechanical product structures, and is used for describing the regular motion process over time in mechanical systems. It plays an important role in implementing product functions, transfering and transforming movement motion, increasing the strength of product functions, expanding the scope of the functions. For the case that the lack of research about dynamic symmetry and imperfection of symmetric system, based on the analysis of instances, a new concept system of mechanical dynamic structure symmetry was established by taking the different properties of the geometric character and the time character of the motion process as standards. The concept system is made up of rotation dynamic symmetry, translation dynamic symmetry, scaling dynamic symmetry, combinatorial dynamic symmetry, time-translation dynamic symmetry and time-inversion dynamic symmetry. Among the concept systemthe author has a symmetry theory analysis of many instances to verify the validity and rationality of the established symmetry concept system. Finally, the functions of dynamic symmetry in realizing the function of transferring or transforming motion, matching the space-time characters and improving the performance of mechanical product functions was proposed. The concept system can completely describes the existences of dynamic structure symmetries in mechanical systems, and can offer an academic basis for further research on the functions and application laws of dynamic structure symmetry in mechanical systems. © Liu and Ma;Licensee Bentham Open.

关键词： Rotation

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Influence of process parameters on interracial tensile strength of crosswedge rolling of 42CrMo/Q235 laminated shafts

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Journal of Iron and Steel Research International 2018年第10期25卷 1003-1009页

作者： Wen-fei Peng Chao Yan Xiao Zhang Xue-dao Shu Guang-xing Huang Dong-ming Xu Zhejiang Provincial Key Lab of Part Rolling Technology Ningbo University Ningbo 315211 Zhejiang China Faculty of Mechanical Engineering and Mechanics NingboUniversity Ningbo 315211 Zhejiang China

Through rolling experiments and interfacial tensile strength tests of cross-wedge rolled laminated shafts of 42CrMo/Q235 composites, the influence of process parameters, including forming angle, spreading angle, area reduction, rolling temperature and core material diameter on the interfacial shear strength was analyzed. The results show that the sequence of process parameters in order of greatest influence on interfacial tensile strength was rolling temperature, area reduction, core material diameter, forming angle and spreading angle. At the interface of the combined materials, tensile strength decreased as forming angle and spreading angle increased, whereas the tensile strength first increased and then decreased as area reduction, rolling temperature and core material diameter increased.

关键词： Laminated shaft Process parameter Interfacial tensile strength Cross-wedge rolling

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Residual stress analysis of multi-pass cold spinning process

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Chinese Journal of Aeronautics 2022年第3期35卷 259-271页

作者： Zixuan LI Xuedao SHU Faculty of Mechanical Engineering&Mechanics Ningbo UniversityNingbo 315211China Zhejiang Provincial Key Laboratory of Part Rolling Technology Ningbo UniversityNingbo 315211China

Uncontrolled residual stresses have significant effects on the service time and defects of the spun ***,X-Ray Diffraction(XRD)method has been widely used in the residual stress measurement of industry products with different forming *** calculated residual stress is usually obtained from the data fitting slope of strain and angle with Ordinary Least Squares(OLS)*** this fitting method is not always suitable for the big fluctuant *** this paper,the Weighted Least Square(WLS)method is used for the data fitting and compared with the OLS *** nickel-based superalloy GH3030 and iron-based superalloy GH1140 are applied in the multi-pass cold spinning *** residual stress distributions of normal,potential crack and wrinkle workpieces are discussed with the grain *** results show that WLS method has better goodness of fit compared with OLS *** residual stress distributions have special relationship with potential crack,wrinkle workpiece and grain structure.

关键词： Cold spinning process Data fitting Grain structure Potential crack Residual stress Weighted least square method

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An Untethered Soft-Swallowing Robot with Enhanced Heat Resistance,Damage Tolerance,and Impact Mitigation

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Chinese Journal of Mechanical Engineering 2024年第6期37卷 456-465页

作者： Haili Li Xingzhi Li Pan Zhou Jiantao Yao Zhejiang Provincial Key Laboratory of Part Rolling Technology School of Mechanical Engineering and MechanicsNingbo UniversityNingbo 315211China Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao 066004China

Soft robotics focuses on addressing the locomotion problem in unstructured environments and the manipulation problem of non-cooperative objects,which inevitably leads to soft robots encountering multiple uncertainties and ***,improving the robustness of soft robots in hostile environmental conditions has always been a *** methods usually improve this robustness through damage isolation,material elasticity,and self-healing *** contrast to existing methods,this paper proposes a method to improve the robustness of an untethered soft-swallowing robot based on the physical properties of fluids,such as the high specific heat capacity of water,the viscosity of soft glue,and the shear thickening of non-Newtonian *** on this method,we developed a soft-swallowing robot with enhanced heat resistance,damage tolerance,and impact mitigation capability by only replacing its fluid working *** show that the developed soft-swallowing robot can withstand high temperatures above 600°C,maintain high performance even after enduring hundreds of damages,and protect grasped object from more than 90%of external *** principle extends beyond the three fluids used in this *** fluids,such as magnetic fluid,can increase adhesion to metal materials,whereas oily fluids can reduce frictional resistance between soft ***,other solid materials with elasticity and compliance can serve as alternative working mediums for the soft-swallowing *** work contributes an effective method for fluid-dependent soft robotic systems to resist the damage from uncertain factors in harsh environments.

关键词： Soft gripper Untethered design Heat resistance Damage tolerance Impact mitigation

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A 0.5-meter-scale,high-load,soft-enclosed gripper capable of grasping the human body

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Science China(Technological Sciences) 2023年第2期66卷 501-511页

作者： LI HaiLi ZHANG Shuai ZHANG XuanHao ZHAO WuMian YAO JianTao Zhejiang Provincial Key Laboratory of Part Rolling Technology Faculty of Mechanical Engineering&MechanicsNingbo UniversityNingbo 315211China Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao 066004China

Developing large,soft grippers with high omnidirectional load(above 40 kg)has always been *** address this challenge by developing a powerful soft gripper that can grasp the human body based on a soft-enclosed grasping structure and a soft-rigid coupling *** envelope size of the proposed soft gripper is 611.6 mm×559 mm×490.7 mm,the maximum grasping size is 417 mm,and the payload on the human body is more than 90 kg,which has exceeded most existing soft ***,the grasping force prediction of the gripper is achieved through theoretical *** primary contribution of this work is to overcome the size and payload limits of current soft grippers and implement a human-grasping experiment based on the soft-grasping method.

关键词： soft gripper large size high-load soft-enclosed grasping

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An improved eclat algorithm for mining association rules based on increased search strategy

International Journal of Database Theory and Application

引用

International Journal of Database Theory and Application 2016年第5期9卷 251-266页

作者： Ma, Zhiyong Yang, Juncheng Zhang, Taixia Liu, Fan Faculty of Mechanical Engineering and Mechanics Zhejiang Provincial Key Lab of Part Rolling Technology Ningbo University 818 Fenghua Rd Ningbo City Zhejiang Province315211 China

Although Eclat algorithm is an efficient algorithm for mining association rules, there are some disadvantages which limit the efficient of Eclat. In this paper, we proposed an improved Eclat algorithm called Eclat_growth which is based on the increased search strategy. There are three main steps in the Eclat_growth algorithm. First, it scans the database and stores it into a table using vertical data format. Then, it builds an increased two-dimensional pattern tree and the TID_sets of itemsets in the vertical data format table are added into the pattern tree row by row. New frequent itemsets are generated by combining the new added item data with the existing frequent itemsets in the pattern tree. Finally, all frequent itemsets can be found by picking up all nodes of the pattern tree. In the process of generating new frequent itemsets, the prior knowledge is used to fully clip the candidate itemsets. In the process of generating an intersection of two itemsets and calculating the support degree, we proposed a new method called BSRI (Boolean array setting and retrieval by indexes of transactions) to reduce the run time. By comparing Eclat_growth with Eclat, Eclat-diffsets, Eclat-opt and hEclat, it is indicated that Eclat_growth has the highest performance in mining associating rules from various databases. © 2016 SERSC.

关键词： Association rules

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Research on the stress uniformity of the high speed bearing with heavy load in cold rolling

Research on the stress uniformity of the high speed bearing ...

引用

4th International Conference on Frontiers of Manufacturing Science and Measuring technology, ICFMM 2014

作者： Hong, Zhe Sun, Bao Shou Hu, Bin Ningbo University Ningbo 315211 China Zhejiang Provincial Key Lab of Part Rolling Technology Ningbo 315211 China

ISBN: (纸本)9783038351924

An FE model is established on the basis of ABAQUS software for simulating the closed cold rolling process of the high speed TRB (tapered roller bearing) with heavy load. The influences of the feed speed, main roll rotational ratio, and initial angle between two guide rolls on the stress uniformity of the formed bearing rings are studied by evaluating the standard deviation of the Von Mises on all elements in the FE model. The research shows that the stress uniformity of the formed bearing rings decreases with the increment of the feed speed;the stress uniformity increases with the increment of the main roll rotational ratio;and the stress uniformity increases with the increment of the angle between two guide rolls. © (2014) Trans Tech Publications, Switzerland.

关键词： Cold rolling

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Numerical Analysis of Multi-pass Cold Spinning of Superalloy of Cylindrical part

Numerical Analysis of Multi-pass Cold Spinning of Superalloy...

引用

2020 International Conference on Internet of Things, Artificial Intelligence and Mechanical Automation, IoTAIMA 2020

作者： Li, Z.X. Shu, X.D. Ye, B.H. Faculty of Mechanical Engineering and Mechanics Ningbo University Ningbo315211 China Zhejiang Provincial Key Laboratory of Part Rolling Technology Ningbo315211 China

In view of the poor plasticity and easy cracking of superalloy at room temperature, the multi-pass cold spinning of cylindrical part was studied. Firstly, the tensile test of superalloy GH3030 is carried out, and the true stress-strain curve is obtained. Then, the numerical models of 250 and 87.5 diameter-thickness ratio blank are established, and the stress and strain field, wall thickness distribution and tool force distribution of the cylindrical part are analyzed and compared. The wrinkle model of 250 diameter-thickness ratio blank was analyzed, and the experiment of 87.5 diameter-thickness ratio blank was carried out. The results show that the wall thickness of the cylindrical part has metal accumulation at the flange, and the thickness of the waist is very small, which is easy to crack under the repeated forming of the roller;the wall thickness distribution of the large diameter-thickness cylindrical part is more uniform, but it has a great challenge to the equipment force and the equipment stiffness. The main reason for the flange wrinkle is staggered distribution of the tangential tensile and compressive stress of the whole flange. © 2020 Published under licence by IOP Publishing Ltd.

关键词： Stress-strain curves

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Feasibility Analysis of Cross Wedge rolling (CWR) of Hexahedral Billet

Feasibility Analysis of Cross Wedge Rolling (CWR) of Hexahed...

引用

2020 International Conference on Internet of Things, Artificial Intelligence and Mechanical Automation, IoTAIMA 2020

作者： Chang, Y. Shu, X.D. Chen, T.Z. Faculty of Mechanical Engineering and Mechanics Ningbo University Ningbo315211 China Zhejiang Provincial Key Laboratory of Part Rolling Technology Ningbo315211 China

In order to expand the product range of cross wedge rolling (CWR) and realize the CWR of hexahedral billet, the hexahedral CWR is studied. In this paper, a three-dimensional finite element model (FEM) of hexahedral cross wedge rolling is established by using DEFORM software. In this paper, a three-dimensional FEM of hexahedral CWR is established by using DEFORM finite element software. The change and distribution of equivalent stress and strain in the rolling process of hexahedral billets are analyzed. By tracking the strain in the rolling core of hexahedral billet, the change law of strain in each stage of forming process is obtained. The equivalent strain during the manufacturing process, the obtained CWR of hexahedral billet and round billet are basically the same. The feasibility of CWR of hexahedral billet is further verified by experiments. The research results provide theoretical guidance for realizing CWR of hexahedral billet. © 2020 Published under licence by IOP Publishing Ltd.

关键词： Billets (metal bars)

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