合锻四个产品通过省级科技鉴定

日前，安徽省科技厅主持对合锻开发的YH61—630快速热挤压液压机、YH25车门包边液压机及自动换模系列、YH73系列热压成型液压机、RZU1000快速深拉深液压机系列项目进行了省级科技成果暨新产品鉴定。     

合锻四个产品通过省级科技鉴定

2006年10月29日，安徽省科技厅主持对合锻开发的YH61-630快速热挤压液压机、YH25车门包边液压机及自动换模系列、YH73系列热压成形液压机及RZU1000快速深拉深液压机等系列项目进行了省级科技成果暨新产品鉴定。鉴定委员会的7名专家首先听取了产品研制报告、产品检验报告和用户使用意见报告，然后分组进行了资料审查。     

锅炉集箱封头热挤压成形过程分析

当前，锅炉集箱封头的加工工艺有两种基本方法，即热旋压成形与热挤压成形。热挤压成形相对热旋压成形更为先进，本文将主要分析集箱封头的热挤压成形。     

影响热挤压模具寿命的因素分析

热挤压工艺是近些年逐渐形成并推广应用的一门金属成形工艺，它是利用金属加热后变形抗力降低这一特性，使用专用热挤压模具对加热状态的金属进行塑性加工，以得到特定毛坯形状的热加工工艺。使用热挤压工艺生产的产品，因其毛坯组织致密，可形成连续不问断的金属流线，     

工业铝材热挤压成型中摩擦状态的 CAE 分析

在工业铝材热挤压成型中，摩擦状态直接决定了铝材的产品质量和挤压模具的使用寿命，因此作为衡量摩擦状态的重要参数，摩擦因子是热挤压过程中主要的工艺参数之一。以某工程机械驾驶室窗框铝材为例，通过CAE技术模拟仿真了在热挤压成型过程中不同摩擦因子对挤压材料温度和模具受力的影响。模拟过程中采用Pro／E软件构建成型挤压模具，并导入模拟分析软件MSC Superforge仿真成型过程，后处理结果可为工业铝材热挤压模具的设计及企业生产实践提供参考。     

斯太尔轴头热挤压新工艺

介绍了斯尔轴头热挤压工艺及模具，分析了原工艺存在的问题，提出了采用热挤压镦挤成形工艺，可挤出内孔完全成形，不需再加工的工件，满足了工件特定的技术要求。     

铝合金拉杆复合挤压工艺及模具设计

提出了铝合金拉杆的热挤压成形新工艺及模具设计，与传统的加工工艺相比，新工艺采用杆部反挤头部正挤的复合热挤压工艺进行生产，使材料利用率和生产效率大大提高，设计制造的挤压模具结构简单、通用性强。     

关于5000 kN四柱液压机的热挤压工艺改造

随着现代科学技术的迅速发展，对通用型式的液压机进行工艺技术改造，其必要性和迫切性愈来愈得到重视，改造后所带来的巨大经济效益以及在短期内回收投资的可能性也被人们所接受。四柱万能液压机主要用于冲压、粉末冶金和金属冷挤压等工作，尚未见用于产品热挤压，碳素产品（如电极、碳棒等）热挤压成形工序常使用卧式液压机。文章讨论了以最少的投资、有效地实现四柱液压机的改造，将其用于热挤压工序，从而扩展其工作能力范围。     

热挤压对粉末冶金PM-0002镍基高温合金组织及热变形行为的影响

对热等静压制备的一种新型粉末冶金PM-0002镍基高温合金进行了热挤压处理,然后在1 0001 100℃下进行了不同应变速率的热模拟压缩试验,对比分析了热挤压前后合金的显微组织和热变形行为。结果表明:该合金经热挤压后,显微组织中的原始颗粒边界基本被消除,晶粒为细小的等轴晶粒;晶粒尺寸由热挤压前的11.29μm减小到8.32μm,且分布较为集中;在不同温度和应变速率下热压缩时,热挤压后合金的峰值压缩应力略高于热挤压前的;热挤压前后合金的变形激活能分别为1 012.9kJ·mol-1和1 146.9kJ·mol-1。     

H13热挤压凸模失效形式及提高寿命的途径

我厂是生产汽车半轴套管的专业厂，热挤压工艺应用较广泛，大至工程机械轮边支承轴，小至微型车半轴套管。模具以采用H13(4Cr5MoSiV1)钢制造为主，由于钢中含有大量的碳化物形成的Cr和Mo，因而具有较高的高温红硬性和耐热疲劳性，是一种较理想的热挤压模具钢。     

A study of the measurement of surface temperature at a cam/tappet contact

Cam/tappet wear is one of the most difficult reliability and durability problems to predict during the development of a prototype engine valve‐train system. In the present study, the cam/tappet surface temperature was measured and calculated to determine the effect of surface temperature on the lubricating conditions at a cam/tappet contact. The measurement method, sometimes called the dynamic thermocouple technique, was based on the Seebeck effect: by using different materials for the cam and tappet, the cam/tappet contact point becomes the hot junction of a ‘thermocouple’. The cam/tappet contact surface temperature can therefore be measured continuously. The measured temperature results show good agreement with predictions. Temperature spikes, however, were not found in the test using new oil, but were shown by the theoretical model. Such results indicate that the cam/tappet interface operates in effective lubricating conditions, even when the oil temperature is relatively high. Further research with degraded oil supplied at high temperature is needed for a thorough understanding of abnormal cam wear.     

Novel method of measuring tappet rotation and the effect of lubricant rheology

One of the main drivers for developing lubricant technology is engine durability. Researchers and scientists are using new technologies, materials and advanced lubricant formulations to reduce overall engine friction and wear. One of the main engine tribological components is the valve train. This is one of the most challenging components to lubricate effectively because of the higher contact loadings and accounts for 10–20% of the total engine friction loss. The two main factors affecting the performance of engine valve trains are wear and friction, and a wide range of mechanical configurations are used to improve these. For example, direct-acting overhead camshaft valve train configurations use a rotating tappet design. Normally, the tappet is slightly offset from the cams and the cam is slightly conical to match the domed tappet to facilitate tappet rotation for even wear and to reduce slippage. In this paper, a novel innovative technique has been described to monitor tappet rotation in a real production engine having a direct overhead cam–tappet arrangement. The monitoring technique was applied to a VW Tdi engine head, and tests were carried out under different operating conditions. Lubricant compositions, oil temperature, pressure and camshaft speeds on tappet rotation were measured and all are shown to have an effect. The balance of forces between the cam–tappet and tappet-bore was found to be interlinked and the design of the hydraulic lash adjuster had a significant effect.This unique tappet rotation monitoring system can be used on most of the direct overhead camshaft engines, with minor engine modifications, to measure lubricant and hardware effects under both motored and fired conditions.     

发动机凸轮轴异常磨损分析

某型发动机在运行早期出现异响,经拆解发现凸轮轴存在异常磨损,从凸轮与挺柱的材质、硬度、凸轮轴型线等方面进行分析,得出凸轮轴与挺柱的偏心量设计不合理是凸轮轴磨损的主要原因.通过优化凸轮轴型线,变更挺柱设计,显著改善了凸轮轴的磨损情况.     

DLC涂层改善气门挺柱摩擦学性能的试验研究

为探求DLC涂层对气门挺柱摩擦学性能的影响,制备了三种不同表面处理的气门挺柱,搭建了配气机构试验台架,对比分析了不同顶面处理方法的气门挺柱在不同转速和缸盖温度下的摩擦功耗;测试了试验前后气门挺柱和凸轮的表面形态,研究了DLC涂层表面特性及其耐磨损特性。试验结果表明,DLC涂层能够减小气门挺柱表面粗糙度,含Si的DLC涂层表面粗糙度极小;气门挺柱与凸轮之间的摩擦力矩随着凸轮轴转速上升逐渐减小,随着缸盖温度上升逐渐增大;相对于传统碳氮共渗气门挺柱,DLC涂层能有效减小摩擦损失,含Si的DLC涂层能减小高达20%的摩擦损失;无涂层气门挺柱和不含Si的DLC涂层气门挺柱的耐磨性较差,含Si的DLC涂层具有极好的耐磨性。     

发动机壳体热挤压成形模拟及模具设计

针对发动机壳体零件的特点,分析了其热挤压成形工艺,确定了挤压成形工艺参数,并利用数值模拟软件,分析了发动机壳体挤压成形时金属的流动规律和压力行程曲线,从而保证了挤压件的质量,为实际生产提供了理论基础,并以此为依据设计了一套热挤压模具。     

Applying ANN to predict the forming load and mechanical property of magnesium alloy under hot extrusion

This study establishes the database concerning magnesium alloy hot extrusion, and uses it to conduct various investigations. Firstly, artificial neural networks (ANN) analysis is used to determine the die shapes of various extrusion ratios. Secondly, the process parameters for the hot extrusion of magnesium alloy are determined, and thirdly, the tensile strength and maximum extrusion load of the finished product are predicted. The database includes 11 parameters, associated with 108 sets of experiment, determined by material type (AZ31 and AZ61), extrusion ratio (14.41, 35.9 and 55.85), product shape (tubular and sheet), semicone angle of the die (90° and 30°), extrusion speed, temperature to which the billet is heated, temperature to which the container is heated, lubricant, hold-time at a specified temperature, extrusion load and tensile strength. ANN is applied to learn from this database, and backward propagation analysis is conducted to find the mechanical properties of the products under various extrusion ratios. This study adopts the orthogonal array of the Taguchi method to hot extrusion experiments that involve dies with different extrusion ratios, and sets the tensile strength and extrusion load of the finished product as the quality characteristics, to acquire the optimal parameter condition. Then, based on the results obtained from the additive model, confirmatory experiments are performed. An Analysis of Variance (ANOVA) analysis is then performed to investigate and analyze the influence of factors on the hot extrusion process. The weight of important factors in the database is increased, and subsequently, the forming load and mechanical properties of magnesium alloy under extrusion are accurately predicted.     

柴油机机体气门挺杆孔加工工艺改进

现行柴油机机体挺杆孔加工工艺柔性不足,为此,本文结合生产实际,提出了新的工艺廊,使研制的柴油机机体挺杆孔加工组合机床具有一定的柔性,以适应同一系列不同缸数的同体挺杆孔的加工。     

Improvement of mechanical properties of Al6061 extrudate by die cooling with N2 gas during hot extrusion

In this study, the mechanical properties of the extrudate are improved by correcting the defects such as abnormal grain growth (AGG). Die cooling with N₂ gas is conducted to control the extrusion temperature during the hot extrusion of Al6061 in order to obtain fine grains of the extrudate. Computational fluid dynamics (CFD) is conducted to evaluate the effect of die cooling with N₂ gas and to determine the relationship between AGG and the extrusion temperature. The optimal cooling channel with a high cooling effect is designed by using the design of experiment (DOE) method, and thermo-mechanical analysis is performed to predict the extrusion temperature. A hot extrusion experiment is also carried out to measure the extrusion temperature and to observe the microstructure of the extrudate. The extrusion temperature predicted from the thermo mechanical analysis is found to be in good agreement with the measured extrusion temperature. The process condition required to reduce the AGG is determined on the basis of the distribution of the evolved microstructure in the hot extrusion experiment. The results confirm the relationship between the distribution of AGG and the mechanical properties of the extrudate. It is confirmed that the mechanical properties of Al6061 can be improved by the application of die cooling with N₂ gas during the hot extrusion process.     

零部件优化对发动机燃油经济性影响的研究

为了降低发动机的机械损失,提高燃油经济性,考虑对挺柱和水泵进行设计优化,从而降低挺柱的摩擦损失和水泵的功耗。利用发动机台架测量整机的机械损失扭矩和万有特性油耗,配合方差分析,研究挺柱和水泵的优化对燃油经济性的影响。结果表明,挺柱和水泵的优化均可提高燃油经济性,其中挺柱影响最显著,而它们的交互作用无影响。     

冷激合金铸铁气门挺杆表层组织对其耐磨性的影响

为了深入了解冷激合金铸铁气门挺杆的磨损规律,研究了冷激合金铸铁气门挺杆表层组织对耐磨性的影响.结果表明:当气门挺杆组织中的石墨以点状均匀分布,碳化物呈细小针状、块状,分布较为均匀时,耐磨性较好,磨损形式以划伤、点蚀为主;当气门挺杆组织中的石墨以片状均匀分布,碳化物呈粗大针状、块状,分布不均匀时,耐磨性较差,磨损形式以剥落为主.