检索结果-内蒙古大学图书馆

2020 5th International Seminar on Computer technology, Mechanical and Electrical Engineering, ISCME 2020

作者： Peng, Baoying Hou, Mingpeng Zhang, Milan State Key Laboratory of Advanced Forming Technology and Equipment China Academy of Machinery Science and Technology Beijing China The Department of Mechanical Engineering Beijing Information Science and Technology University Beijing China

The accuracy of five-axis linkage machining is influenced by many factors, such as linear axis errors, tool rotation errors, contour trajectory changes, milling force changes, and five-axis parameters do not mismatch. To improve the machining accuracy, the kinematical model of five-axis linkage with B-C double swing head is derived on the basis of RTCP (Rotation tool center point). The following errors of five axis coupled form contour error calculation model is proposed and a cross-coupled controller is designed. Choosing the curve of impeller as an example, a simulation model of five-axis linkage machining is established. Simulation results show that the cross-coupling controller designed for can improve the machining contour accuracy of the five-axis machining effectively. © Published under licence by IOP Publishing Ltd.

关键词： Errors

来源：评论

学校读者我要写书评

暂无评论

Influence of Co on the microstructure and mechanical properties of M42 high-speed steel 2

Influence of Co on the microstructure and mechanical propert...

引用

2nd International Conference on advanced Materials and Chemical Engineering, AMCE 2022

作者： Wang, Shunduo Chen, Yunbo Pan, Peng Lin, Zhenghua Zuo, Lingli China Academy of Machinery Science and Technology Beijing100044 China Beijing National Innovation Institute of Lightweight Ltd. Beijing100083 China State Key Laboratory for Advanced Forming Technology and Equipment Beijing100083 China Fujian Hengerda New Materials Ltd. Putian351142 China

M42 high-speed steel (W2Mo9Cr4VCo8) is a kind of high cobalt super-hard high-speed steel (HSS), which is extensively used in various cutting tool materials, but because of the high price of cobalt, high cobalt HSS does not bring good economic benefits. In this thesis, the consequences of various cobalt contents (0.0%, 2.0%, 4.0%, 6.0%, 8.0%) on the organization and mechanical properties of M42 HSS have been studied. The microstructure of HSS was analyzed by OM, SEM, and EDS, and the Rockwell hardness test, impact toughness test, and flexural strength test were conducted. The results show that cobalt helps to increase the nucleation rate of eutectic carbide precipitation and hinder its growth during tempering of HSS and refine the size of eutectic carbide, and the tempering hardness can be maintained above 68 HRC when the cobalt content is 4%-8%;however, cobalt also significantly reduces the impact toughness of HSS, and each 2% increase in cobalt impact toughness decreases about 4 J·cm-2. From the point of view of cobalt savings, cobalt content of 4%, high-speed steel tempering hardness, impact toughness, and other mechanical properties can be at a higher level. © Published under licence by IOP Publishing Ltd.

关键词： Eutectics

来源：评论

学校读者我要写书评

暂无评论

Performance of digital patternless freeze-casting sand mould

引用

China Foundry 2020年第4期17卷 308-313页

作者： Zhong-de Shan Hao-qin Yang Feng Liu Yi-fei Wang State Key Laboratory of Advanced Forming Technology and Equipment China Academy of Machinery Science and Technology Group Co.Ltd.Beijing 100044China

Digital patternless freeze-casting technology is a new approach for obtaining frozen sand moulds using digital milling technology. The change law of tensile strength and air permeability of frozen sand moulds (100-mesh and 200-mesh silica sand, and zircon sand moulds) under different freezing temperatures and water contents was studied. Results show that with the decrease of freezing temperature and the increase of water contents, the tensile strength and air permeability of the sand moulds are gradually improved. Meanwhile, computed tomography technology was used to characterize the shape and size of the water film between the sand particles mixed with 4wt.% water. The results show that in silica sand moulds, the form of water film is lumpy, and 200-mesh silica sand moulds have more water films and higher proportion of small-sized water films than 100-mesh silica sand moulds, while in zircon sand moulds, the form of water film is membranous. At the same freezing temperature and water content, the tensile strength of zircon sand mould is the highest, and 100-mesh silica sand mould is the lowest. A comparative solidification experiment of A356 aluminum alloy was carried out in frozen sand mould and resin sand mould. The results show that the primary α-Al phase appears in the form of equiaxed and eutectic silicon phase is needle-like in freezing sand mould casting, but the primary α-Al phase grows in the form of dendrites, and the eutectic silicon phase is coarse needle-like in the resin sand mould casting. The difference of microstructure is caused by the different cooling rate. The cooling rate of A356 aluminum alloy in frozen sand mould is higher than that in resin sand mould.

关键词： patternless moulding freeze casting frozen sand mould green casting

来源：评论

学校读者我要写书评

暂无评论

Digital high-efficiency print forming method and device for multi-material casting molds

引用

Frontiers of Mechanical Engineering 2020年第2期15卷 328-337页

作者： Zhongde SHAN Zhi GUO Dong DU Feng LIU Wenjiang LI State Key Laboratory of Advanced Forming Technology and Equipment China Academy of Machinery Science and TechnologyBeijing 100044China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China

Sand mold 3D printing technology based on the principle of droplet ejection has undergone rapid development in recent years and has elicited increasing attention from engineers and ***,current sand mold 3D printing technology exhibits several problems,such as single-material printing molds,low manufacturing efficiency,and necessary post-process drying and heating for the manufacture of sand *** study proposes a novel high-efficiency print forming method and device for multi-material casting *** proposed method is specifically related to the integrated forming of two-way coating and printing and the shortflow manufacture of roller compaction and layered *** processes can realize the high-efficiency print forming of high-performance sand *** results demonstrate that the efficiency of sand mold fabrication can be increased by 200%using the proposed two-way coating and printing *** integrated forming method for layered heating and roller compaction presented in this study effectively shortens the manufacturing process for 3D-printed sand molds,increases sand mold strength by 63.8%,and reduces resin usage by approximately 30%.The manufacture of multi-material casting molds is demonstrated on typical wheeled cast-iron *** research provides theoretical guidance for the engineering application of sand mold 3D printing.

关键词： multi-material casting mold 3D printing efficient print forming method

来源：评论

学校读者我要写书评

暂无评论

Study on Microstructure Distribution of Al-Cu-Mg Alloy in Squeeze Casting Process 8

Study on Microstructure Distribution of Al-Cu-Mg Alloy in Sq...

引用

2022 8th International Conference on Applied Materials and Manufacturing technology, IcamMT 2022

作者： Li, Longfei Zheng, Yuankai Chen, Yunbo Feng, Jian Li, Chunming Chen, Lin Zuo, Lingli Zhang, Yang State Key Laboratory of Advanced Forming Technology and Equipment Beijing100083 China Beijing National Innovation Institute of Lightweight Ltd. Beijing100083 China Beijing Research Institute of Mechanical and Electrical Technology Beijing100083 China GRIMAT Engineering Institute Co. Ltd. Beijing101407 China

The squeeze casting process is an advanced technology, which is suitable for a wide range of alloys including Al-Cu-Mg alloys. The high pressure in squeeze casting process both refines the microstructure and enhances the mechanical property of the alloys. The heat transfer and solidification process are complex with the chilling mould and pressure of machine punch. This results in the inhomogeneous microstructure and property in casting alloy. This study focuses on the distribution of microstructure, chemical composition, and hardness of Al-Cu-Mg alloy along the radial direction of casting. The composition and area fraction of eutectic phases are characterized. Moreover, the relationship between the microstructure and mechanical property was also analysed to show the characteristic of microstructure in squeeze casting process. © Published under licence by IOP Publishing Ltd.

关键词： Ternary alloys

来源：评论

学校读者我要写书评

暂无评论

Failure analysis of the piston used in a pneumatic down the hole impactor 8

Failure analysis of the piston used in a pneumatic down the ...

引用

2022 8th International Conference on Mechanical Engineering, Materials and Automation technology, MMEAT 2022

作者： Pan, Peng Li, Yongsheng Chen, Yunbo Wang, Jinnan Zuo, Lingli Chen, Rongrong Zhang, Baoyan Beijing National Innovation of Lightweight Ltd Beijing100083 China State Key Laboratory for Advanced Forming Technology and Equipment China Academy of Machinery and Technology Beijing100083 China Shandong Tianrui Heavy Industry Company Weifang Shandong261000 China Department of Mechanical Engineering Tsinghua University Beijing100084 China

In this paper, the failure mechanism of the piston in the pneumatic down the hole (DTH) impactor has been studied. Failed piston microstructure has been analyzed using the light optical microscopy (OM) and scanning electron microscope (SEM). Impact toughness test and the Rockwell hardness test were conducted. Results showed the following: a) The carburizing layer of IQCT failed piston is mainly composed of acicular martensite and lower bainite after the carburizing-tempering-isothermal quenching-cryogenic treatment-tempering (IQCT), and there are collapses on the impact side and outer surface of the piston, mainly fatigue failure. b) IQT failed piston samples are subject to carburizing-tempering-isothermal quenching-tempering treatment (IQT). The carburized layer is mainly composed of high-carbon martensite, carbide and retained austenite. The transition layer is still composed of lower bainite and acicular martensite, but the volume fraction of lower bainite increases significantly and the core is mainly composed of lower bainite. It has the best impact toughness, up to 61.5 J/cm2, which is mainly fatigue failure. c) OQT failed piston sample is subject to carburizing-tempering-oil quenching-tempering (OQT). The carburized layer is mainly composed of acicular martensite, the transition layer is composed of acicular martensite (AM) and lath martensite (LM), and the core is mainly composed of LM. The impact toughness of the sample is the worst. Therefore, fatigue fracture failure is caused. © Published under licence by IOP Publishing Ltd.

关键词： Scanning electron microscopy

来源：评论

学校读者我要写书评

暂无评论

Hot Deformation Behavior and Microstructure Evolution of a Novel Mn-Containing Hea

SSRN

引用

SSRN 2023年

作者： Wu, Yanxin Wang, Tianxiang Zhang, Yun Tian, Shiwei Xiong, Chengyue Jiang, Haitao National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology Beijing Beijing100083 China State Key Laboratory of Advanced Forming Technology and Equipment Beijing National Innovation Institute of Lightweight Ltd. Beijing101407 China

The deformation behavior and microstructure evolution of a novel Mn-containing HEA were explored during the deformation temperature ranges of 800~1100℃, and strain rate ranges of 0.001~1s-1. The study results indicate that the true stress-strain curves after work hardening exhibit continuous softening type at low strain rate ranges of 0.001~0.01 s-1, while softening then steady-state type at high strain rate ranges of 0.1~1s-1, respectively. The activation energy (Q) and stress exponent (n) are calculated to as 404.6 kJ/mol and 4.9016, respectively. As the strain increases, the flow instability is prone to expand towards the regions of lower strain rate and higher deformation temperature, and the optical processing window is determined at 1050~1100 °C and 0.001~0.002 s-1. The strain and stress field distribution of the FEM simulations reveal the inhomogeneous deformation and the damage field distribution predict the crack region of deformation specimen. The critical (Εc)/peak strain (Εp) for DRX do not display a proportional relationship with strain rate and an inversely proportional relationship with deformation temperature, and the relationship between Εc and Εp can be expressed as: Εc = (0.3~0.5) Εp. Only the discontinuous dynamic recrystallization (DDRX) mechanism is activated in the whole range of deformation conditions, but it is not fully carried out. Because of the inhomogeneous stress distribution between dendrites (DR) and interdendritic (ID) regions, the dynamic recrystallized grains show bimodal grain size. Furthermore, the recrystallized grains do not grow significantly due to the synergistic contribution of sluggish diffusion effect, high solution hardening effect and the trimodal B2 precipitate phase distribution. © 2023, The Authors. All rights reserved.

关键词： Dynamic recrystallization

来源：评论

学校读者我要写书评

暂无评论

Enhanced wear resistance of a die steel via modification of the M7C3 and M23C6 carbides

引用

Wear 2025年 576-577卷

作者： Shen, Xinyu Peng, Mulan Fu, Hao Wei, Tongtao Wu, Hong Huang, Xiedong Li, Zulai Li, Lu Baker, Ian Shan, Quan Faculty of Material Science and Engineering Kunming University of Science and Technology Kunming650093 China State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China Thayer School of Engineering Dartmouth College HanoverNH03755-8000 United States National & Local Joint Engineering Laboratory for Technology of Advanced Metallic Solidification Forming and Equipment Kunming650093 China

Large volume fractions of carbides in die steels are a crucial source of high wear resistance. However, the inherent brittleness of micrometer sized carbides reduces the toughness, and can cause embrittlement and even premature failure of die steels. In this work, Cr8Mo2VSi die steel, a typical cold work die steel, has been modified by both reducing the volume fraction and refining the M7C3 carbides. The modified Cr8Mo2VSi die steel was produced via a 0.8 wt% reduction of Cr and a 5 % increase in deformation during composition design and rolling process, respectively. Increased aging-induced precipitation of M23C6 carbides in Cr8Mo2VSi can balance the negative effects of the M7C3 carbides, thereby toughening the die steel and extending its fatigue life. Moreover, M7C3 carbides are prone to peeling during wear because of their inherent brittleness, the stacking faults present, and the low interfacial adhesion. The modified Cr8Mo2VSi die steel exhibited superior toughness and fatigue performance and high wear resistance not only due to the increased participation of M23C6 carbides, but also because of the increased number of high-angle grain boundaries resulting from increased deformation. This study aims to provide guidance for the toughening of die steels with high-carbide contents. © 2025 Elsevier B.V.

关键词： Stacking faults

来源：评论

学校读者我要写书评

暂无评论

Research of the Influence Mechanism of Multi Gradient Printing on Sand Mold Performance 7

Research of the Influence Mechanism of Multi Gradient Printi...

引用

2021 7th International Forum on Manufacturing technology and Engineering Materials, IFEMMT 2021

作者： Zheng, L.I. Zhongde, Shan Feng, Liu Yuelong, Ran State Key Laboratory of Advanced Forming Technology and Equipment Beijing National Innovation Institute of Lightweight Ltd. Beijing100044 China Nanjing University of Aeronautics and Astronautics Nan jing211106 China

In this paper, multi gradient sand mold sample printing was carried out based on the gray printing technology of sand mold 3D printing, and the influence of gradient distribution of resin addition in sand mold on the property of sand mold was studied. The results showed that the increase of resin addition gradient in sand mold would result in the decrease of tensile strength of sand mold with the constant total resin addition. The bending strength and air permeability of sand mold were mainly affected by the surface resin addition and gradient distribution. With increase of surface resin addition, The bending strength of sand mold decreased, and of which the air permeability increased at the same time. And the increase of gradient spacing between adjacent resin addition gradients in sand mold would lead to the increase of sand mold air permeability and the decrease of tensile strength and bending strength. The result also showed that The surface hardness of the sand mold increased with the increase of the resin content of the surface layer, and had nothing to do with the gradient distribution of the resin content. © Published under licence by IOP Publishing Ltd.

关键词： Resins

来源：评论

学校读者我要写书评

暂无评论

Enhancing Thermal Stability of Laser-Powder Bed Fusion Fabricated High Entropy Alloy by Introducing Elemental Segregation Using in-situ Alloying

SSRN

引用

SSRN 2024年

作者： Zhu, Xiangjian Niu, Mengchao Liu, Shan Yu, Yanan Han, Luyi Zhao, Guoqun Wang, Guangchun State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Shandong Jinan250061 China Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of Education Shandong University Shandong Jinan250061 China Department of Mechanical Engineering Research Institute for Advanced Manufacturing The Hong Kong Polytechnic University Hong Kong The Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen518057 China Hebei Key Laboratory of Material Near-net Forming Technology Hebei University of Science and Technology Hebei Shijiazhuang050000 China

A method is proposed to enhance the thermal stability of laser-powder bed fusion fabricated (L-PBFed) alloys by incorporating Al element segregation through in-situ alloying. The high entropy alloy (HEA) with Al segregation was prepared through in-situ alloying of mixed powders of AlSi10Mg and FeCoCrNi, and the enhanced thermal stability of the grain boundary (GB) and dislocation in high-temperature annealing at 1000 °C and 1200 °C is verified and studied. Experimental characterization and molecular dynamics (MD) simulations revealed that the introduced Al segregation exists in two forms of B2/BCC phases, one in banded shape in the FCC matrix and the other as particles at GBs. At elevated temperatures, short-range uphill diffusion occurs within the banded B2/BCC phase, resulting in the formation of dispersed or mesh-like B2/BCC phases of higher Al and Ni content, along with the generation of dislocations. Additionally, long-range diffusion of Al atoms, originating from the aggregated region of banded B2/BCC, travels to the matrix, utilizing GBs as rapid channels. This diffusion stabilizes GBs by reducing their cohesive energy and maintaining the nailing effect of the B2/BCC phase at GBs. Consequently, the mechanical property exhibits remarkable resistance to softening compared to the traditional L-PBFed alloys. This study demonstrates that element segregation introduced by in-situ alloying serves as an effective approach to enhance the thermal stability of L-PBFed alloys. Furthermore, the proposed theory of sustained phase transitions offers insights into understanding the transitions of heterogeneous alloys fabricated through in-situ alloying at elevated temperatures. © 2024, The Authors. All rights reserved.

关键词： Molecular dynamics

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：