WADSWORTH Jeffrey and FLUSS Michael(Chemistry and Materials Science Directorate
,
Lawrence Livermore National Laboratory
,
Livermore
,
CA 94551)
金属学报(英文版)
The role of the National Laboratories is summarized from the era of post World War II to the present time. The U.S. federal government policy for the National Laboratories and its influence on their materials science infrastructure is reviewed with respect to .determining overall research strategies, various initiatives to interact with industry (especially in recent years),building facilities that serve the nation, and developing leading edge research in the materials sciences. Despite reductions in support for research in the U.S. in recent years, and uncertainties regarding the specific policies for Research &Development (R&D) in the U.S., there are strong roles for materials research at the National Laboratories. These roles will be centered on the abilities of the National Laboratories to field multidisciplinary teams, the use of unique cutting edge facilities, a focus on areas of strength within each of the labs,increased teaming and partnerships, and the selection of motivated research areas. It is hoped that such teaming opportunities will include new alliances with China, in a manner similar, perhaps, to those recently achieved between the U.S. and other countries.
关键词:
: U.S. Materials Science. U.S. National Laboratories and Facilities
,
null
T. Umemura
,
Y.Zhou
,
S.Kamimura
,
N.Motoi
,
Y Ohta
,
N. Yamaguchi
材料科学技术（英文）
The die motions of a new forging process for automation with an intermediate die assembly called hamburger were analyzed through high-speed video pictures. The results showed that the upper die that is assembled in the hamburger and retained over the lower die collides few times with the ram and workpiece, but sound products can be obtained with less sticking in spite of the lowered impacts of hit.
关键词:
H.W.Liu 1)
,
H.Ding 2) and J.Z.Cui 2) 1) School of Mechanical Engineering
,
Shenyang University
,
Shenyang 110044
,
China 2) School of Materials & Metallurgy
,
Northeastern University
,
Shenyang 110006
,
China
金属学报(英文版)
Porthole dies are important tools in extrusion process to produce hollow sections and the life of the dies counts for the cost of products. In this work, the finite element method was adopted to analyze a particular porthole die to produce hollow rectangle sections which are widely used in construction. The upper die was mainly studied. Because it is symmetrical, a quarter of the die was analyzed. The upper die was divided into 2199 elements with 3018 nodes. Elements were produced by four steps and the geometric shape of the die could be well simulated. The boundary condition was given according to the shape of the welding chamber and an empirical average extrusion stress was adopted, which was 210N/mm 2. Three-dimensional equivalent stresses were received. The original porthole die studied had obvious stress concentration and the stress distribution was very inhomogeneous, which would heavily affect the die life. A new design was proposed in which the portholes were rearranged and their shape and dimension were changed. According to the finite element analysis, the stress distribution of the improved die was quite homogeneous and the stress concentration was lessened.
关键词:
section extrusion
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null
,
null
W.Q. Ma
,
H.Y. Sun
,
D.C. Kang
,
K.D. Zhao
金属学报(英文版)
The steel reinforced plastic pipe is a new kind of pressure pipe. It is made up with steel
wires and plastic. Because reinforced skeleton of the steel wire increase the complexity
of plastic flow during the extrusion phase, the traditional design criteria of extrusion
die is not suitable. The study on extrusion die of the kind of pipe is very important
step in produce development. Using finite element (FE) method in this paper, the
flow rule of molten plastic inside the die has been predicted and a group of optimal
structural parameters was obtained. These results are helpful for reducing the design
cycle and improve the quality of the final product.
关键词:
steel reinforced plastic pipe
,
null
,
null
Zhichao SUN
,
He YANG
材料科学技术（英文）
Tube inversion including free deformation under conical die is an advanced forming process for manufacturing complicated thin-walled parts with high strength/weight ratio, high efficiency, and good flexibility for size changing. However, the successful reality of forming process, the change of deforming mode and shape and size of part formed are mainly on the die angle. Based on the analysis of the forming process, the model of rigid-plastic FEM (finite element method) is established and a numerical simulation system is developed. The effect of die angle on the tube inversion forming process is investigated with the code developed. The results of the effect of half die angle on shape of free deformation zone and on deforming load are obtained. There is an optimal die angle (about 75 deg), which makes the forming load minimum.
关键词:
Tube inversion under conical die
,
null
,
null
,
null
Hongwei JIANG
,
Chunfeng LI
,
Haiping YU
,
Zhiheng ZHAO
材料科学技术（英文）
Calculation of magnetic pressure is the basis of application of electromagnetic forming (EMF). This paper carries out a numerical simulation of magnetic pressure under the influence of die by means of finite element method. The analysis model of electromagnetic bulging with die is created by using ANSYS, and the distribution of magnetic pressure acting on the tube and the die is obtained. The differences between EMF and other technologies and the effect of die on tube formability are analyzed. The die has important influence upon the calculation accuracy. The simulating conclusions with different discharge energy and current frequency are verified through the technologic tests. The distribution of magnetic pressure acting on the tube agrees well with the measurements of the deformed tube.
关键词:
Electromagnetic bulging
,
null
,
null
,
null
CUI Xianghong
,
SHAN Jun
,
YANG Zirun
,
WEI Minxian
,
WANG Shuqi
,
DONG Chuang
钢铁研究学报(英文版)
The alloying design of cast hotforging die steels was analyzed. The relationship of the life of cast hotforging dies with the failure patterns was studied. The thermal wear resistance was believed to be the key property for the alloying design of cast hotforging die steels. The alloying design parameters were selected and optimized for the cast hotforging die steel with high wear resistance. The wear resistance of the optimized cast die steel was evaluated in comparison with commercial H13 steels and 3Cr2W8V steel. In the new cast hotforging die steel, VC is predominant carbide with Cr and Mo as the main solution elements in αFe. It is found that the cast die steel has significantly lower wear rate than normal H13 steel and 3Cr2W8V steel, almost the same as that of high purity H13 steel. The high wear resistance of the new cast hotforging die steel can be attributed to its reasonable alloying design and nonsensibility to the detrimental function of S and P.
关键词:
hotforging die;cast steel;wear resistance;alloying design
Z.Wang
,
K.Dohda
材料科学技术（英文）
The fatigue behavior of cemented carbide die under service load in the multistage cold forging of steel was investigated. It was found that the fatigue cracks do not initiate at the stress concentration position and the crack initiation position can be classified to three types. The crack initiation position can be predicted by FEM only when the plastic deformation of the die is considered.
关键词:
Huamin LIU
材料科学技术（英文）
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.
关键词:
Bevel gear
,
gear
,
closed-die
,
cold
,
gorging
,
FEM
,
f
Xiang XUE
,
Zhiliang NING
,
Bide ZHOU
,
Chunhui ZHANG
材料科学技术（英文）
In this study, the Solidworks was used as pre-processor, which performed the three- dimensional solid construction and automatic enmeshment. The COSMOS was adopted as post- processor to display the temperature distribution and further to simulate the thermal stress distribution of dies. A software package for three-dimensional temperature fields of complicated die casting and its dies was developed and the temperature distributions of a fan cover casting were simulated by the software.
关键词:
