Mg-xSi （x=0, 1.5, 3.3） alloys were fabricated and subjected to cyclic closed-die forging （CCDF）, a new severe plastic deformation process, at 450 ℃ for 1, 3, and 5 passes. With applying CCDF, tensile strength, el...Mg-xSi （x=0, 1.5, 3.3） alloys were fabricated and subjected to cyclic closed-die forging （CCDF）, a new severe plastic deformation process, at 450 ℃ for 1, 3, and 5 passes. With applying CCDF, tensile strength, elongation and hardness increase, while coarse Mg2Si particles break into smaller pieces and exhibit more uniform distribution. Mg-1.5%Si alloy exhibits a combination of improved strength and elongation after 5 passes of CCDF processing. The tensile strength is about 142 MPa and elongation is about 8%. The improvement in mechanical properties was further characterized by dry sliding wear testing. The results show that wear resistance improves with silicon content and CCDF process passes, particularly the first pass. The wear resistance increases by about 38% for Mg-3.3%Si after 5 passes of CCDF compared with pure Mg. The improvement of wear is related to microstructure refinement and homogenization based on the Archard equation and friction effect.展开更多
The closed-died cold forging technology of the bevel gears used in Jada car was investigated. With the analysis of the strain field and velocity field of the plastic deformation and the endured forces of the dies, the...The closed-died cold forging technology of the bevel gears used in Jada car was investigated. With the analysis of the strain field and velocity field of the plastic deformation and the endured forces of the dies, the filling rules for the metal were analyzed by the elastic-plastic finite element method （FEM）. The results show that there is a great difference among closed-die cold forging, extrusion and forging, as far as the metal flowing is concerned. The outer addendum cannot be filled completely in the closed-die cold forging of the bevel gears, and the round angle will be formed. But it does not influence the application of the bevel gears. At the beginning, the rigid area is formed in the cavity of the lower die. And then it will move upwards to supply the metal for the gear filling. For the closed-die cold forging of the bevel gears, the force acting on the upper die and the lower die is significantly different.展开更多
Cold closed-die forging is a suitable process to produce spur-bevel gears due to its advantages, such as saving materials and time, reducing costs, increasing die life and improving the quality of the product. The hom...Cold closed-die forging is a suitable process to produce spur-bevel gears due to its advantages, such as saving materials and time, reducing costs, increasing die life and improving the quality of the product. The homogeneity of microstructure of cold closed-die forged gears can highly affect their service performance. The homogeneity of microstructure and Vickers hardness in cold closed-die forged gear of 20 Cr Mn Ti alloy is comprehensively studied by using optical microscopy and Vickers hardness tester. The results show that the distribution homogeneity of the aspect ratio of grain and Vickers hardness is the same. In the circumferential direction of the gear tooth, the distribution of the aspect ratio of grain and Vickers hardness is inhomogeneous and they gradually decrease from the surface to the center of the tooth. In the radial direction, the distribution of the aspect ratio of grain and Vickers hardness is inhomogeneous on the surface of the gear tooth; while it is relatively homogeneous in the center of the gear tooth. In the axial direction of the gear tooth, the distribution of the aspect ratio of grain and Vickers hardness is relatively homogeneous from the small-end to the large-end of the gear tooth.展开更多
为了解决曲轴模锻材料利用率低和能耗高的问题,基于有限元数值模拟技术,研究了热锻曲轴的无飞边精密成形工艺及模具系统。由于曲轴的几何结构单元主要为单缸曲轴,故首先给出了单缸曲轴的热锻工序,包括板式楔横轧、多向锻造和精锻。利用D...为了解决曲轴模锻材料利用率低和能耗高的问题,基于有限元数值模拟技术,研究了热锻曲轴的无飞边精密成形工艺及模具系统。由于曲轴的几何结构单元主要为单缸曲轴,故首先给出了单缸曲轴的热锻工序,包括板式楔横轧、多向锻造和精锻。利用DEFORM 3D软件对曲轴的无飞边锻造过程进行全程数值模拟,结果表明:楔横轧工序中工件两端易突起,多向锻造中连杆颈圆角容易折叠,精锻中主轴颈圆角处容易折叠;楔横轧工序最大载荷为250 k N,多向锻造X向最大载荷为450 k N,精锻最大载荷为5 450 k N。最后将该技术推广到两缸曲轴和多缸曲轴,同样得到了良好的无飞边结果。展开更多
The article has described the technological analysis of the plastic deformation of slip joint pliers,the design of forging drawing,the sectional diagram and the diametral diagram of the calculating billet.The flashles...The article has described the technological analysis of the plastic deformation of slip joint pliers,the design of forging drawing,the sectional diagram and the diametral diagram of the calculating billet.The flashless die construction and the productive technological process of slip joint pliers are introduced.It has elaborated the advantages of replacing traditional old technology with technology of flashless die forging.In the end it has given the techno economic comparison of the new and old technologies.展开更多
基金Projects(50674067,51074106)supported by the National Natural Science Foundation of ChinaProject(2011BAE22B01-5)supported by the National Key Technologies R&D Program during the 12th Five-Year Plan Period,ChinaProject(09JC1408200)supported by the Science and Technology Commission of Shanghai Municipality,China
文摘Mg-xSi （x=0, 1.5, 3.3） alloys were fabricated and subjected to cyclic closed-die forging （CCDF）, a new severe plastic deformation process, at 450 ℃ for 1, 3, and 5 passes. With applying CCDF, tensile strength, elongation and hardness increase, while coarse Mg2Si particles break into smaller pieces and exhibit more uniform distribution. Mg-1.5%Si alloy exhibits a combination of improved strength and elongation after 5 passes of CCDF processing. The tensile strength is about 142 MPa and elongation is about 8%. The improvement in mechanical properties was further characterized by dry sliding wear testing. The results show that wear resistance improves with silicon content and CCDF process passes, particularly the first pass. The wear resistance increases by about 38% for Mg-3.3%Si after 5 passes of CCDF compared with pure Mg. The improvement of wear is related to microstructure refinement and homogenization based on the Archard equation and friction effect.
文摘The closed-died cold forging technology of the bevel gears used in Jada car was investigated. With the analysis of the strain field and velocity field of the plastic deformation and the endured forces of the dies, the filling rules for the metal were analyzed by the elastic-plastic finite element method （FEM）. The results show that there is a great difference among closed-die cold forging, extrusion and forging, as far as the metal flowing is concerned. The outer addendum cannot be filled completely in the closed-die cold forging of the bevel gears, and the round angle will be formed. But it does not influence the application of the bevel gears. At the beginning, the rigid area is formed in the cavity of the lower die. And then it will move upwards to supply the metal for the gear filling. For the closed-die cold forging of the bevel gears, the force acting on the upper die and the lower die is significantly different.
基金Project(51105287)supported by the National Natural Science Foundation of ChinaProject(2013M531750)supported by China Postdoctoral Science Foundation
文摘Cold closed-die forging is a suitable process to produce spur-bevel gears due to its advantages, such as saving materials and time, reducing costs, increasing die life and improving the quality of the product. The homogeneity of microstructure of cold closed-die forged gears can highly affect their service performance. The homogeneity of microstructure and Vickers hardness in cold closed-die forged gear of 20 Cr Mn Ti alloy is comprehensively studied by using optical microscopy and Vickers hardness tester. The results show that the distribution homogeneity of the aspect ratio of grain and Vickers hardness is the same. In the circumferential direction of the gear tooth, the distribution of the aspect ratio of grain and Vickers hardness is inhomogeneous and they gradually decrease from the surface to the center of the tooth. In the radial direction, the distribution of the aspect ratio of grain and Vickers hardness is inhomogeneous on the surface of the gear tooth; while it is relatively homogeneous in the center of the gear tooth. In the axial direction of the gear tooth, the distribution of the aspect ratio of grain and Vickers hardness is relatively homogeneous from the small-end to the large-end of the gear tooth.
文摘为了解决曲轴模锻材料利用率低和能耗高的问题,基于有限元数值模拟技术,研究了热锻曲轴的无飞边精密成形工艺及模具系统。由于曲轴的几何结构单元主要为单缸曲轴,故首先给出了单缸曲轴的热锻工序,包括板式楔横轧、多向锻造和精锻。利用DEFORM 3D软件对曲轴的无飞边锻造过程进行全程数值模拟,结果表明:楔横轧工序中工件两端易突起,多向锻造中连杆颈圆角容易折叠,精锻中主轴颈圆角处容易折叠;楔横轧工序最大载荷为250 k N,多向锻造X向最大载荷为450 k N,精锻最大载荷为5 450 k N。最后将该技术推广到两缸曲轴和多缸曲轴,同样得到了良好的无飞边结果。
文摘The article has described the technological analysis of the plastic deformation of slip joint pliers,the design of forging drawing,the sectional diagram and the diametral diagram of the calculating billet.The flashless die construction and the productive technological process of slip joint pliers are introduced.It has elaborated the advantages of replacing traditional old technology with technology of flashless die forging.In the end it has given the techno economic comparison of the new and old technologies.
