板簧切角模具的设计及材料改进

斯太尔系列板簧的主要成型工序是轧头切角,其工艺复杂,模具消耗量大,主要是因为模具为单工序设计,需多次成型才能完成,模具的失效形式主要为刃口磨损和刃口裂纹.介绍了根据产品特点和模具使用特点,对板簧切角模具的设计及材料进行的改进.     

气体渗碳在耐火材料模具热处理中的应用

采用气体渗碳工艺替代固体渗碳对耐火材料成型模具进行热处理。经合理设计工艺 ,模板表面的含碳量达到0 .9%～ 1.0 % ,淬火后的表面硬度达到 HRC62～ 64 ,成本降低 3 5 4.6元 / t,而且提高了模具使用寿命     

创壹虚拟模具教学软件应用探讨

创壹虚拟模具教学软件是为模具教学开发的软件.应用该系统配合模具教学大纲,将注塑模、挤压模,冲压模、吹塑模等二十多种模具,采用虚拟现实的三维仿真技术向学生进行全方位模具教学和成型模具的展示.辅助以模具的设计教学使学生能更快、更好的掌握模具的工作原理和设计方法.     

注塑模具设计关键问题

塑料件在汽车上的应用已经越来越广泛,而制件的表面质量、成型精度完全由模具决定之外,它的内在质量、成型效率也受模具的控制,但许多模具行业设计加工过程中出现大量的失误,造成成本的增加,工期的延误,所以在汽车产品更新换代极快的今天,当务之急是如何高效、快速、高质量和规范化地设计注塑模具,在本文中,我们从产品设计和模具设计经验两方面来阐述.     

一模32腔圆隙浇口粉末注射成型模具的设计及应用

对于大批量、小规格的永磁粘接磁环大多采用注射成型工艺,其模具设计是产品制造的重要环节之一,模具设计的合理与否直接关系到制品的生产效率、成品质量和经济性等.文章分析了多种注射成型模的方案后,结合小规格钕铁硼稀土永磁粘接薄壁磁环的材料特性,设计了一种32型腔圆隙浇口的薄壁磁环注射成型模.该模具具有自动化程度高、尺寸一致性好、能大批量生产等特点,有较佳的经济效益和进一步行业推广的价值.     

多空腔异形铝型材的模具设计

对多空腔异形铝型材新型模具,采用以下的几种独特、创新设计思路进行设计、加工,打破以往的传统设计加工方案,从而保证了模具加工简单,铝型材成型良好,从而减少了试模次数,提高了模具的使用寿命,降低了模具成本.     

多模芯挤压模的设计与制造分析

生产具有多个模芯的空心铝型材的关键因素在于模具的设计与制造,合理的设计及制造工艺是保证空腔间连接部位成形良好的关键。通过实例,对具有多个模芯的空心铝型材挤压模具设计的关键要素作了具体分析,并对该类模具在制造中的要点作了介绍。实践表明,采用这些方法很有效,能很好地解决这类型材的成型问题。     

近终形连铸用浸入式水口模具设计

由于近终形连铸用浸入式水口形状特异,为了提高生产水平,降低生产成本,设计了组合模具。组合模具由外形模具、内孔模具和密封模具组成,外形模具采用了内外双层胶模,内层胶模设计为双分式,成型后制品外形加工余量约为10%;内孔采用金属组合模具,配合紧密,脱模顺利,可重复使用。组合模具为浸入式水口的批量生产奠定了基础。     

新型开口式气缸挤压模具新设计

研发设计一种新型开口式气缸模具,在采用独特设计的同时使气缸成型良好,其气密性、光滑度和尺寸精度均能满足高要求。该款产品的设计不仅提高了工业气配行业挤压模具的设计、加工水平,更是打破了以往单一的封闭式气缸设计模式,具有较高创新性。     

高强铝合金中的氢

高强铝合金中的氢致缺陷是长期示曾解决的重大技术难题，作者结合自己的科研工作，对多年来有关该问题的研究成果进行了系统的介绍和分析。在氢致缺陷的成因和本质问题上进行了部分澄清，并且认为，氢致缺陷起源于熔炼，但后继的热变形过程也将对缺陷的尺寸产生明显的影响，因此合理设计成型模具和优化成型工艺也减少氢致缺陷不良影响的有效途径。     

宝钢300t转炉新炉型炉壳有限元法强度分析研究

对宝钢 30 0t转炉新炉型炉壳进行了有限元强度分析 ,计算结果表明 ,该炉壳在机械荷载 (炉体自重和钢水重力 )、温度荷载及热膨胀压力等联合作用下所产生的综合应力 ,在转炉炉壳的许用应力允许值之内 ;其所产生的变形 ,也在新炉型炉壳的刚度设计范围内。     

基于ANSYS的高炉推移小车有限元分析

文章对高炉推移小车进行了设计,确定了小车的外形尺寸及选材。通过建立小车的三维模型,本文在ANSYS中对小车进行了有限元静力分析,得到了其在特定载荷下的应力图及车架变形图,进一步校核了小车的强度。最后得出小车满足设计要求的结论。     

Allowable Bearing Pressures of Bridge Sills on GRS Abutments with Flexible Facing

Compared to geosynthetic-reinforced soil (GRS) retaining walls, GRS abutment walls are generally subjected to much greater intensity surface loads that are fairly close to the wall face. A major issue with the design of GRS abutments is the allowable bearing pressure of the bridge sill on the abutments. The allowable bearing pressure of a bridge sill over reinforced soil retaining walls has been limited to 200?kPa in the current NHI and Demo 82 design guidelines. A study was undertaken to investigate the allowable bearing pressures of bridge sills over GRS abutments with flexible facing. The study was conducted by the finite element method of analysis. The capability of the finite element computer code for analyzing the performance of GRS bridge abutments with modular block facing has been evaluated extensively prior to this study. A series of finite element analyses were carried out to examine the effect of sill type, sill width, soil stiffness/strength, reinforcement spacing, and foundation stiffness on the load-carrying capacity of GRS abutment sills. Based on the results of the analytical study, allowable bearing pressures of GRS abutments were determined based on two performance criteria: A limiting displacement criterion and a limiting shear strain criterion, as well as the writers’ experiences with GRS walls and abutments. In addition, a recommended design procedure for determining the allowable bearing pressure is provided.     

用粉末冶金方法制造压缩机法兰

为防止压缩机在运行中变形,用粉末冶金方法制造了带减压槽的压缩机法兰。将制造法兰的粉末材料装于模腔中,然后,将熔点比粉末材料低的熔渗件置于减压槽位置进行成形;将粉末材料与熔渗件压制成形为法兰;在粉末材料与熔渗件熔点之间的温度下进行烧结,使熔渗件熔化和渗入粉末材料之中。用新方法制造的法兰比用常规方法生产的强度高、密封性好。根据分析,在烧结时,由于熔渗件熔化与渗透到法兰结构中,改进了气密性,增高了强度。     

Microstructural control of toughness in aluminium-lithium alloys

Investigation of the deformation behaviour of AlLi based alloys containing zirconium as a grain-refining addition shows that the poor toughness properties are attributed to the intense coplanar slip associated with δ' (Al₃Li) precipitation being unimpeded by the grain structure as a result of the pronounced deformation texture present in the sheet product; fracture proceeds via a transgranular shear failure mode which limits toughness. Changes in composition and thermomechanical treatment have been utilised in order to encourage the formation of additional precipitate phases, and, whilst δ' confers the major increment of strength to all AlLi based alloys, widespread precipitation of S phase (Al₂CuMg) within AlLiMgCuZr alloys is shown to influence strongly the deformation behaviour; in particular the propensity towards slip coplanarity is reduced, and significant improvements in toughness are obtained. Additionally, by promoting homogeneous deformation within the grain structure, the presence of S phase causes the material to display isotropic properties even though a strong texture remains in the zirconium-refined sheet product.     

Assessment of steel deformability in terms of energy dissipation

The deformability of steel grades with different strength is analyzed, from the perspective that deformation is dissipative in thermodynamic terms: some of the kinetic energy of the external mechanical perturbation is converted to internal energy of the metal being deformed, with the creation of particular dislocational structure. Accordingly, energy criteria are proposed for the deformability of steel. These criteria may be determined in standard tensile tests. They are based on the work of deformation, which is determined by the area of the extension diagram. The absorbed energy determines the work of deformation, while the rate of energy absorption determines the resistance of the steel to deformation (the pliability in plastic deformation). The energy dissipation is quantitatively estimated, with comparison of the unit work and the pliability. The research is based on standard tensile tests of samples made from steels that differ in strength as a result of alloying (changes in chemical composition) and heat treatment and are used for different purposes. The steels vary in yield point from 210 to 1660 MPa and in strength from 840 to 1940 MPa. The unit work of point deformation is found to exceed the unit work of uniform deformation by an order of magnitude. The pliability in point deformation is markedly less than the pliability in uniform deformation. A clear correlation between these quantities is noted. This may be regarded as the expression of the structural evolution of the metal at both stages of deformation. In particular, in self-organization of the dissipative system—that is, the deformable steel—the dislocation density acts as an internal parameter regulating the evolutionary transformations. A correlation is established between the pliability criteria and the limiting loads in uniform deformation and failure. Thus, steels that differ in strength may be ranked in terms of the energy absorbed in deformation. In practice, the numerical values of the unit work and the pliability may be used to predict the behavior of structural steels belonging to different steel classes under mechanical perturbations in the course of operation and machining.     

Stress-strain state in the hydrostatic pressing of tubular parts from powder materials and method of calculating mold assembly elements

Conclusions An analysis is made of the mechanism of deformation of sizing shells in mold assemblies during the hydrostatic pressing of tubular parts from powder materials by the radial expansion technique. A plot has been obtained showing the distribution of pressure across the thickness of a part being pressed. A method is proposed for calculating the elements of mold assemblies for the hydrostatic pressing of tubular parts from powder materials by the radial expansion technique.Translated from Poroshkovaya Metallurgiya, No. 12(228), pp. 17–21, December, 1981.     

回转式飞剪机刀轴强度分析

分析了回转式飞剪机上刀轴在剪切过程中的受力状况,分别利用弯扭合成强度计算方法和安全系数法校核了改进设计的回转式飞剪机上刀轴疲劳强度和静强度。理论计算结果表明,上刀轴危险截面的弯曲应力均小于刀轴材质的许用弯曲应力,并具有足够的静强度安全系数。通过实际生产的检验,证明了改进设计的飞剪机能够满足生产线的使用要求。     

Purpurediolin and purpurenin, two new cytotoxic adjacent bis-tetrahydrofuran annonaceous acetogenins from the seeds of Annona purpurea

PURPOSE: This study investigated the different effects of quantitative percentages of glass fiber intensity on the transverse strength, maximum deformation, and the modulus of elasticity of acrylic resin. MATERIALS AND METHODS: Fifty-four specimens were formed in a specially designed mold to produce identical specimens in accordance with the manufacturer's recommendations. Six percentages of glass fiber reinforcement in loose random form were studied. Each glass fiber treatment percentage (0%, 1%, 2%, 5%, 10%, 15%) was related to the total powder/liquid mass. RESULTS: The results indicated that 1% glass fiber treatment enhanced the transverse strength of the tested specimen. Maximum deformation at failure in the tested treatment groups was found to be different. The interaction of glass fiber concentration on fracture strength and deformation was significant (p < 0.0001). CONCLUSION: The 1% glass fiber concentration was found to give the best fracture strength and deformation results. Significantly higher glass fiber percentages was found to weaken the resin.     

Modeling the thin-slab continuous-casting mold

A three-dimensional mathematical model has been developed to compute the thermomechanical state in the mold of thin-slab continuous casters. The thin-slab mold differs from those used in conventional slab casters in that the upper portion of the broad side walls defines a funnel-shaped chamber which allows the nozzle to be submerged into the liquid metal. The chamber converges with distance down the mold, reducing to the rectangular cross section of the finished casting near the mold exit. The new mold, along with casting speeds up to 6 m/min, allows slabs to be cast 50–60 mm thick, compared with 150 to 350 mm in conventional continuous slab casting. However, the mold shape and high casting speed lead to higher mold temperatures and shorter mold life than are found in conventional slab casters. In this article, we develop mathematical models of the process to determine the role of various process parameters in determining the mold life. Finite-element analysis is used to determine the temperatures in the mold and cast slab, and these data are then used in an elastic-viscoplastic analysis to investigate the deformation of the mold wall in service. Cyclic inelastic strains up to 1.75 Pct are found in a region below the meniscus along the funnel edge. These large strains result from the combination of locally high temperatures coupled with geometric restraint of the mold. The deformation leads to short mold life because of thermal fatigue cracking of the mold. The computed locations and time to failure of the mold in fatigue agree very well with observations of the appearance of mold surface cracks in an operating caster. The models are also used to develop an improved mold design. Formerly Research Assistant, Department of Mechanical and Industrial Engineering, University of Illinois, Urbana, IL