共查询到20条相似文献，搜索用时 31 毫秒
1.
Bomsster is a key load-bearing part of railway lorry bogie.Because of its inherent defects casting-steel bomsster could not meet the demands of the heavy load,acceleration and security for lorry.So forging process is proposed to form it.The forming performance of forging-steel bomsster is analyzed.A forging technology is presented which realizes two forging-steel bomsster parts formed in one die.With the plastic forming simulation software DEFORM-3D,the simulation and optimization of the forming process of forging bomsster has been taken based on 3D rigid visco-plastic FEM theory.Optimized scheme has been used to direct the pilot product.The results of product's testing and application suggest that the new forging technology is feasible and the performance of the product is credibility and stabilization.The factory has realized large scale production of a series of forging-steel bomsster.Remarkable benefits of both economy and society have been achieved. 相似文献
2.
Numerical simulation of influence for the process parameters on multi-roll flexible stretch forming 总被引：1，自引：0，他引：1
Multi-roll stretch forming (MRSF) process is a new flexible process. Through extensive numerical simulations of the MRSF process, it is found that the smaller the distance between die and rollers is, the more easily the shape can be formed, and the better the quality of formed part can be. However, the distance between clamps and rollers has little effect on the formed parts. The corresponding stretch forming experiment has been done and the results show that the simulation trend is consistent with the experimental results. 相似文献
3.
农产品热泵烘房温度场均匀性是影响农产品干燥品质的重要因素。本文选用5HGR-35型农产品热泵烘房,通过交互式CAD/CAM系统(UG)软件建立热泵烘房3D模型,运用理论分析与计算流体动力学(Computational fluid dynamics,CFD)模拟相结合的方法,研究其内部温度场分布情况,对现有结构烘房的温度场建模模拟,分析模拟结果并对现有结构进行优化。通过模拟得出结论:送风速度越大,烘房内热空气更新越快,换热效果越好。综合温度场分布以及农产品烘干要求,烘房内合理的送风速度为11 m/s左右;在11 m/s风速下,烘房空载时在15 min左右达到设定温度(65℃);小推车设计高度加大300~310 mm烘房内部温度场更均匀;烘房顶部均匀加入3块长×宽×高=2900 mm×20 mm×300 mm的挡板,可以使烘房内部温度场更均匀;小推车与烘房之间及相互之间保持30 mm左右间隙摆放更有利于烘房内部温度场的分布;验证试验中,模拟温度与实测温度吻合性良好。上述结论对烘房的进一步优化设计具有一定的指导意义。 相似文献
4.
To research the influence of combustion chamber thermal boundary conditions on micro combustion characteristics in micro ICE, the laminar flow finite rate model is adopted to simulate the micro combustion process. Firstly, the influence of grid scale, the time step length and the maximum iterations per time step on accuracy of simulation results are explored. The results show that simulation results agree well with experimental results. And then, the influences of heat transfer coefficient, wall thickness and material on combustion characteristics are discussed. The results indicate that heat transfer coefficient has obvious influence on combustion characteristics. The pressure rise rate decreases, the ignition delays and the highest pressure value drops 2 atmospheres as heat transfer coefficient increases from 0 to 55 W/(m 2·K). The wall thickness and material have a little effect on combustion characteristics. This is because that the main heat transfer resistance in the heat flow path from cylinder to external environment lies between the outer wall and environment. 相似文献
5.
Filling process of differential-pressure cast for thin-wall castings of aluminum alloy is simulated with the hydraulic simulation method. The effects on filling fluid pattern was taken by the figure and amount of the ingate and the wall width of castings are researched. It is shown that the wall width of castings has obvious effect on critical pressure increase rate and critical filling rate, the thinner the wall width of castings is, the bigger the critical pressure increase rate and critical filling rate are; but the figure and the amount of the ingate has no obvious effect on the stationarety of filling. On the basis mentioned above, it is carried out that numeric simulation of filling process of differential-pressure cast and the process design of defferential -pressure cast to some large-scale thin-wall cabin-shape parts, and the result showes that are the smooth and stepwise filling,and the project of differential pressure cast is instituted by the process parameters, which is provide by the hydraulic simulation method. It provides the reference for the produce of this kind of castings. 相似文献
6.
The processing characteristics of the front bumper bracket are analyzed,and a reasonable process scheme is worked out.The three-dimensional sheet metal forming analysis software PAM-STAMP are adopted to simulate the bracket's drawing process.Then the surface of die is proved fine through analyzing the FLD diagrams and the forming results.An economical and optimized die structure is decided,and a complete set of dies of the bracket is designed.The spacing block is added in the sizing mold,which control the size precision of end products and assembling columns actively,and finally the certified products.The material utility and the labor productivity are raised,the production cost is saved,and the mold design quality and the efficiency are improved effectively. 相似文献
7.
The capacity,voltage,and length of modern electric power system are increasing ceaselessly.Synchronous generators will cause self excitation with the help of armature reaction,its stator current and voltage will increase.The self excitation conditions and the transient process are two aspects for studying self excitation.Now,self excitation conditions are mathematical formulas under certain postulate.The model of transient process of self excitation is linear.The conditions of self excitation are presented based on simulation,and the results of self excitation effected by the electromagnetic parameters of hydro generators operating extra high voltage long transmission line are simulated,based on a saturation model of hydro generators.The conclusions are very helpful for operation and design of hydro generators. 相似文献
8.
扩张蛋白(Expansin)研究进展 总被引：9，自引：0，他引：9
扩张蛋白是一类细胞壁酶蛋白,能够通过打断细胞壁多聚物之间的氢键诱导酸依赖的细胞壁延展和压力松弛。其由两类多基因家族编码,分别命名为α-expansin、β-expansin,每类扩张蛋白基因家族又有很多的基因成员。扩张蛋白已在不同的种属植物中被鉴定存在,并且大量的扩张蛋白基因被克隆。研究表明：每一个扩张蛋白基因在高度特定的位点和高度特定的细胞类型中表达,其表达在时间、空间上受到严格的调控且受到激素和环境因子的调控。目前认为扩张蛋白几乎参与了植物的整个发育过程：除具有增大细胞的功能外,扩张蛋白在细胞生长、种子萌发、根毛形成、根系生长、叶原基形成、叶子生长发育、果实成熟、器官脱离,以及花粉管生长方面起着重要的作用。就此最新研究进展,作一综合阐述。 相似文献
9.
Wrinkling limit prediction of rotary-draw bending process for thin-walled rectangular aluminum alloy tube 总被引：1，自引：0，他引：1
Wrinkling is one of main forming defects of the rotary-draw bending process for thin-walled rectangular aluminium alloy tube, which severely restricts the improvement of the forming quality and forming limit. Therefore, a regression prediction model of the wrinkling wave height is built based on finite element(FE) simulation combined with orthogonal regression analysis, and its reliability is validated by experiments. Then the analytical model of forming limit without the occurrence of wrinkling is derived. The laws of the core number, the clearance between mandrel and tube and the clearance between wiper die and tube affecting wrinkling limit are obtained, and the wrinkling limit diagram for the rotary-draw process of thin-walled rectangular tube is obtained.This research provides basis and guidance for improving forming quality of the rotary-draw bending process for the rectangular tubes in production. 相似文献
10.
In order to improve utilization of cold and heat source from river, turbulence theory and entropy generation theory were adopted to analyze the effect of fouling on convective heat transfer performance in small diameter tube of constant wall temperature.It is found that the entropy generation caused by conduction of fouling plays a more important role in total entropy generation of heat transfer process through a duct than that in cveast rate of caused by temperature difference.The entropy generation caused by viscous flow is more than the entropy generation caused by temperature difference in flow with bigger Reynolds and small radius.The increase rate of entropy generation monotonically increase with Reynolds and the generation process of fouling resistance.Thereafter, the effect of fouling resistance on the heat transfer performance of water source heat pump heat exchanger should be paid more attention, when river water are used as the cold and heat source of heat pump. 相似文献
11.
ZHANG Kun GAO Xiao qiang ZHENG Zhong ZHAO Ke wen SONG Guo ju ZHANG Da de CHEN Xiao ping 《保鲜与加工》2003,(12):43-47
A simulation system for logistics in steel-making process has been developed by analyzing the state of logistics in steel plant, integrating the approach of coloured Petri nets with time and queuing network and using object-oriented methodology. The software functions for building-up simulation model, executing simulation, managing simulations, playing demo, analyzing statistics and online help. The objectives and principles of the simulation software have schematically been introduced. At last, the software is visually validated with measured input data of primary logistics in Vanadium-extracting, Steel-making Plant of Panzhihua Iron and Steel Corporation. A Gantt diagram and statistics of simulation case are included in simulation results and can be used to assist decision-making for scheduling in steel-making process. 相似文献
12.
Luo Xinrong 《保鲜与加工》1998,(6):29-34
The transport equation and numeric simulation equation of gas migration in compressible coal seam with dual pore have been built up. The distribution curves of gas pressure in coal seam and the attenuation curves of coal or drilling hole wall have been obtained according to solution of numeric simulation and similar theory. 相似文献
13.
原生质体作为单细胞且具有全能性,为研究植物细胞壁生物合成提供了独特的视角和模型。原生质体细胞壁再生过程复杂,涉及诸多细胞信号转导通路,应用普通的研究方法难以全面解析整个再生壁过程的分子网络。为充分了解植物原生质体再生壁内在特性,推动植物原生质体再生壁的分子机理进一步完善,笔者从原生质体再生细胞壁培养、细胞壁再生的细胞生物学证据、结合诸多组学技术研究细胞壁再生分子机理3个方面进行系统分析和归纳总结。分析了不同植物原生质体培养的主要影响因素如植物材料限制、培养基及培养方式的差异;归纳了2种常用染料应用于原生质体再生壁可视化研究的进展;总结了转录组、蛋白组及更为精细的核蛋白组及磷蛋白组技术在揭示细胞壁再生分子网络机理方面的应用和意义,并提出了对原生质体细胞壁再生机理深入研究的展望。 相似文献
14.
HE La-mei~ 《保鲜与加工》2004,(5):57-61
To solve potential scheduling problems in production after renewal of continuous casting process in Vanadium-extracting and Steel-making Plant of Panzhihua Iron and Steel Corporation (PISCO), how to model and simulate logistics system in steel-making processhas been discussed. A series of simulatingtests for logistics system in steel-making processhave been conducted based on inputs of presentsteel-making processof PISCO. In the tests, cases of regular schedule case and cases with repairing converter have also been regarded as essential simulation condition. It has been shown that three casters can not start at same time in order to ensure continuous hot metal supply for casters when three kinds of steel are made. It has also been shown that the simulation system for logistics system in steel-making processis valid and can be used for simulating logisticsin upcoming 100% continuous casting process of PISCO. The better schedule scheme of production and reasonable match of converter-caster in time and capacity can be achieved with the help of using simulation approach. 相似文献
15.
美国奶业新特点、新趋势及对中国的启示 总被引：1，自引：0，他引：1
美国奶业发展历史悠久,其生产端、消费端乃至流通贸易方面长期积累的丰富经验,对中国奶业振兴具有一定的参考价值。笔者对2000年以来美国奶业生产、价格、消费、贸易等方面所呈现的新特点进行分析,对奶业相关的支持政策及其变化趋势进行梳理。研究发现,近年来,美国奶牛场数量向北部和西部集中,500头以上规模化牧场成为主流,奶牛存栏增加;技术进步推动奶牛单产突破10 t,生鲜乳产量接近1亿t。基于分级定价的乳成分定价机制不断完善,近5年生鲜乳价格低位运行,2019年快速复苏。乳制品加工业向龙头企业集中,奶酪是主要加工产品。乳制品消费逐年增长,年人均消费量达292.90 kg,奶酪是主要增长点且增速加快。乳制品贸易波动增加,出口目的地集中在北美、东亚和东南亚地区,品类以奶粉、奶酪和乳清为主。奶业产业支持政策广泛涵盖生产、消费、贸易等各环节,各政策间功能互补、协调配套,形成了强大的政策合力与综合效能。美国奶业在产业组织、运行机制、政策配套等方面的经验与做法,对推动完善中国奶业利益联结机制、优化生鲜乳价格形成机制、完善奶业支持政策体系和培育乳制品消费习惯等方面具有重要启示。 相似文献
16.
Huang Dongjie 《保鲜与加工》1990,(3)
The lateral structures of frame-shear wall system are simplified into bending beams and shear beams which stiffness can vary in different stages along the building height. The three-dimension stiffness matrix and mass matrix are deduced, and the characteristic equation is established to calculate the tortuous free vibration of the asymmetric system. The method is simple and has satisfactory precision, and it is easily fulfilled in micro-computers. 相似文献
17.
As the domestic technology of selective catalytic reduction(SCR) has not been mature.A assembled-parameter dynamic mathematical model is established for the primary chemistry reaction process in SCR reactor.The mass balance equation of the NH3 adsorption-desorption on the catalyzer surface and six gas components,and total energy balance equation in SCR reactor are set up respectively.A dynamic simulation model has developed by using MATLAB simulation tool.The steady calculation for model is carried on.Based on the established dynamic simulation model,two dynamic simulation experiments have been done,which include the simulation experiment of step disturbance about NOx concentration and temperature.The simulation results current is correctl.The analyzed results indicate that the established dynamic mathematical model for SCR reactor is credible,and prove that the simulation model is practical. 相似文献
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19.
A new type of circuit topology for DC-AC type contactless power transfer(CPT) system is proposed, and the asymmetric DC-AC convert is used to imply the new topology. The topology simplifies the circuit and control of DC-AC type CPT system, reduces the power loss of power conversion of secondary circuit, and improves the overall efficiency and power density of the system. This paper presents the topology of the converter and investigated its control strategy. A model of the system has been derived, with which the system is simulated and studied. The measured experimental results have verified the theoretical and simulation results. 相似文献
20.
With numerical simulation, an analysis is done on the three-dimension air flow in the helix intake port of a diesel engine. The anthors acquire the distribution of characteristic parameters of air in the port, such as velocity, pressure, turbulence kinetic energy, as well as the flow coefficient and rotate moment around the erect axes at the outlet. The results of simulation indicate that the negotiability of the port is very good while the ability of forming eddy can be enhanced, so several improve measures have been put forward. Comparing with simulation results of these measures, it finds out that the method of combining increase the distance between the definition curve of volute cavity and central line of valve protruding support as well as increase the eddy shell angle can obviously enhance the ability of forming eddy, which is an efficient and rational method. 相似文献