6PNJ胶泵前护套压制模设计

分析了6PNJ胶泵前护套结构 ,介绍了该零件的橡胶压制模 ,由于制件尺寸较大 ,不便于加工与大气相通的排气槽 ,采用了不与大气相通的“藏气槽”新方法 ,解决了制件的排气问题     

逆向工程技术在泵前护套模具修复中的应用

通过应用逆向工程技术,得出了250PNJ泵前橡胶护套模具尺寸不合适之处,确定了合理的模具修复方案,用修复后的模具生产出了合格的前橡胶护套产品。说明逆向工程技术在测量带有复杂曲面外形零件及分析对比零件外形的细微差别时具有明显的优势。结果表明了修复方案的正确性。     

两线嵌件护套注射模设计

分析了带嵌件护套的结构特点和成型工艺,阐述了1模4件的设计方案以及上下模镶块和滑块的设计要点,介绍了嵌件注射成型时双下模模具的工作过程和特点。针对护套含带嵌件的要点,采用热流道浇注系统的结构形式,节约了原材料,立式转盘注射机的选用,缩短了制件的成型周期,在很大程度上提高了塑件的质量;经批量生产验证,制件的尺寸精度高,注射成型工艺过程稳定可靠。     

具有非垂直结构特征的硅橡胶压制模具的加工

在模具设计中,不可避免会存在一些相对于模具体的较大截面非垂直结构的特征,这些非垂直异形结构特征,给模具制造带来很大的麻烦。以某高压互感器外护套压制成型模具为例,通过分析模具体的组成及上模芯和下模腔的非垂直结构特征,介绍了利用自制工装,解决非垂直结构特征模具加工难题的方法。     

旋转卡板精冲连续复合模结构的改进

通过分析旋转卡板精冲连续复合模中压凸台凸模和导正销折断的原因 ,提出了模具的改进措施和结构 ,给出了一种带护套的小凸模快换结构。     

10孔插座护套热流道注射模设计

通过对该塑件的分析,介绍了10孔插座护套的注射模设计,详细讲解了热流道在精密模具中的实际应用,阐述了模具在成型时延时抽芯结构的作用及滑块顺序合模的动作,使用喷气冷却器保证了良好的冷却效果。实践证明:模具结构合理,成型周期短,抽芯运动顺利,塑件质量满足使用要求。     

S型弯曲软波导橡胶护套成型工艺及模具设计

从选材入手,综合分析如何选择适宜的橡胶材料。采用柔性组合压胶模芯,突破弯曲软波导无法压制橡胶护套的技术难题。合理选择模具结构,提高橡胶护套的机械物理性能及产品质量。调整橡胶硫化的温度、压力和时间等3要素,确保了产品的各项技术指标符合设计要求。     

汽车插接护套注射模设计

通过对插接护套复杂结构的工艺分析 ,确定了该类制件的注射模结构、工作过程 ,并对其设计特点进行了介绍     

46孔护套注射模设计

对46孔护套进行了分析,对多孔精密塑件注射模进行了详细介绍,并对长距离抽芯模具设计及产品功能型钩子的模具设计进行了阐述。     

一种交叉式侧抽芯机构

介绍了一种一模2腔四面抽芯的汽车电喷插座护套注射模结构,分析了纵向和横向拼块机构的运动过程,设计了一交叉式纵横同时运动的斜滑槽。采用此模具结构实现了连续注射生产,提高了生产效率。     

SA508-3钢低温韧性不合格原因分析及工艺改进

分别从化学成分、热处理工况和金相组织等方面对不合格产品与合格产品进行了对比分析,结果表明,低温韧性不合格的主要原因是金相组织中存在较多的碳化物堆积。通过热处理工艺试验发现,冷却速度慢会导致碳化物堆积数量增加。在冷速有限的情况下,通过延长回火低温等温时间可以有效改善碳化物堆积状况,提升锻件低温韧性。     

Effect of the plating parameters on the electrodeposition of Ni matrix coatings containing Ti nanoparticles

This work focuses on the production of electrodeposited nickel matrix composite coatings containing Ti nanoparticles and on the modification of the process parameters in order to maximise the codeposited particles content as well as obtaining a uniform distribution along the coating thickness. The deposition was carried out using a Ni sulphamate plating bath with different amounts of Ti nanoparticles. The plating parameters such as current density, current type (direct, DC, or pulsed, PC) and the use of ultrasound during the deposition have been modified. The specimens produced have had their microstructure, chemical composition and microhardness analysed. It was found that the increase of the particle concentration in the plating bath up to 40?g?L^?1 leads to an increase of the amount of codeposited particles. The use of ultrasound prevents agglomeration of the particles, leads to a more uniform distribution and increases the Ti content. However, it induces microstructural defects in the matrix. These defects can be limited by increasing the current density or by using pulsed current.     

基于车间信息集成的工序质量控制技术研究

针对质量控制研究较多局限于工序质量统计分析、预警阶段以及制造过程信息的激增,提出了质量预防———诊断——反馈控制于一体的基于车间信息集成的动态工序质量控制系统架构,分析了系统的主要模块功能;利用试验设计方法作为系统诊断工具对机床制造企业工艺改进案例进行了分析,结果表明:该方法用有限的试验可以解决多因素对质量输出特征值的影响问题,能够满足工序质量闭环控制需求。     

电弧放电制备内包金属纳米洋葱状富勒烯的研究

在金属微粒催化的条件下探索了用直流电弧放电法制备内包金属纳米洋葱状富勒烯(Onionlike Fullerenes OLFs)的过程和工艺。用扫描电镜(SEM)和高分辨透射电镜(HRTEM)等实验手段对生成的OLFs进行了形貌、结构的观察和表征。研究结果表明：调整工艺参数，并辅以催化剂掺杂可大量制备内包金属的OLFs；对个别工艺参数的影响进行了探讨。     

Electrochemical methods of assessing the corrosion of painted metals—a review

The possibility of using potential—time and polarization curves for predicting the corrosion of metals covered by paint films is considered, and the limited amount of published experimental work is briefly described.Difficulties which may be encountered in using the techniques are discussed, and further experimental investigation is recommended.     

De-alloying of rapidly solidified amorphous and crystalline alloys

De-alloying occurs when a less noble metal is selectively removed from an alloy either by chemical or electrochemical means. Under appropriate experimental conditions and for suitable alloy composition, the resulting material is constituted by crystalline ligaments rich in the noble element and pores. The literature reports a substantial amount of information on de-alloying crystalline homogeneous solid solutions, mostly based on noble metals, whereas the process has been attempted in a limited number of cases with amorphous alloys. The latter case is reviewed here and new results are given for an Au-based metallic glass evidencing the role of the critical potential and surface roughness.It can be also of interest to remove selectively from the alloy a single phase leaving a sieve-like matrix. which might itself be porous. The size of the pores and of the remaining solid can be tailored by controlling the grain size of the phases. Examples are given for this second process and experiments are reported on successful selective etching of rapidly solidified Fe–C eutectics.     

Theoretical-experimental modeling of milling machines for the prediction of chatter vibration

Productivity of high speed milling operations can be seriously limited by chatter occurrence. Chatter vibrations can imprint a poor surface finish on the workpiece and can damage the cutting tool and the machine. Chatter occurrence is strongly affected by the dynamic response of the whole system, i.e. the milling machine, the tool holder, the tool, the workpiece and the workpiece clamping fixture. Tool changes must be taken into account in order to properly predict chatter occurrence. In this study, a model of the milling machine-tool is proposed: the machine frame and the spindle were modeled by an experimentally evaluated modal model, while the tool was modeled by a discrete modal approach, based on the continuous beam shape analytical eigenfunctions. A chatter identification technique, based on this analytical-experimental model, was implemented. Tool changes can be easily taken into account without requiring any experimental tests. A 4 axis numerically controlled (NC) milling machine was instrumented in order to identify and validate the proposed model. The milling machine model was excited by regenerative, time-varying cutting forces, leading to a set of Delay Differential Equations (DDEs) with periodic coefficients. The stability lobe charts were evaluated using the semi-discretization method that was extended to n>2 degrees of freedom (dof) models. The stability predictions obtained by the analytical model are compared to the results of several cutting tests accomplished on the instrumented NC milling machine.     

压路机前围拉伸模设计

对于拉伸模最大的难度就是要求有合理的工艺方案、良好的工艺补充,只有确定好方案．才能够拉伸出合格的产品。该前围覆盖件拉伸模经过工艺分析,采用1模2件对称方式拉伸。经过CAE拉伸软件的模拟分析,对于拉伸不足的区域采用增加拉伸筋的方式,通过试模最终加工出合格的零件。     

A numerical model of the EDM process considering the effect of multiple discharges

The electrical discharge machining (EDM) process is, by far, the most popular amongst the non-conventional machining processes. The technology is optimum for accurate machining of complex geometries in hard materials, as those required in the tooling industry. However, although a large number of EDM machines are sold every year, scientific knowledge of the process is still limited. The complex nature of the process involves simultaneous interaction of thermal, mechanical, chemical and electrical phenomena, which makes process modelling very difficult. In this paper a new contribution to the simulation and modelling of the EDM process is presented. Temperature fields within the workpiece generated by the superposition of multiple discharges, as it happens during an actual EDM operation, are numerically calculated using a finite difference schema. The characteristics of the discharge for a given operation, namely energy transferred onto the workpiece, diameter of the discharge channel and material removal efficiency can be estimated using inverse identification from the results of the numerical model. The model has been validated through industrial EDM tests, showing that it can efficiently predict material removal rate and surface roughness with errors below 6%.     

Study on Contact Fatigue Life and Failure Mechanism of Subquenched 42CrMo Steel

The effect of undissolved ferrite amount in subcritically quenched 42CrMo steel on contact fatigue properties and failure mechanism were studied. The amount of undissolved ferrite in the steel were 0%,3%,10%,15% and 20% in volume fraction, respectively. The experimental results show that the existence of undissolved ferrite can increase the contact fatigue life The contact fatigue life can be prolonged with increasing the amounts of undissolved ferrite The grain size can be fined by using subcritical quenching process and the area of phase boundaries can also be greatly increased. The stress relaxation and grain refinement due to occurring of plastic deformation are main reasons for improving the fatigue life. The existence of undissolved ferrite can increase the crack initiation period. Under the experiment conditions, when the amount of undissolved ferrite is 10%, the longest contact fatigue life can be the obtained.