不同润滑条件下氧化铝基陶瓷材料磨损特性的对比

对氧化铝基陶瓷材料在室温无润滑以及滴油润滑条件下的磨损特性进行了研究，进而对两种状况下材料的磨损机理进行了探讨。     

良加工热镀铝锌钢板表面摩擦特性及冲压成型性能研究

为满足家电户外件对热镀铝锌耐指纹钢板冲压成型性的需求,开发了一种具有优异冲压成型性的热镀铝锌耐指纹钢板,并通过摩擦因数分析仪和冲压试验机研究了室温及高温条件下其表面摩擦特性及冲压成型性能。结果显示,在室温及高温(100℃)条件下,热镀铝锌耐指纹钢板均能够保持较低的动摩擦因数,表明其具有良好的表面润滑性能及稳定的摩擦特性。冲压成型后,热镀铝锌耐指纹钢板受力变形区域表面无明显犁痕、发黑和脱锌现象,表明其具有优异的冲压成型性能。     

宝钢汽车用无机润滑热镀锌钢板的特性

为了提高汽车用热镀锌钢板的冲压成形性能,对热镀锌钢板表面进行了一种无机润滑处理。介绍了宝钢自主研发的汽车用无机润滑处理热镀锌钢板的特性与市场应用情况。与普通的热镀锌钢板相比,无机润滑处理热镀锌钢板具有较低的表面摩擦因数与更好的冲压润滑性能、更稳定的摩擦特性与冲压稳定性、更低的冲压参数敏感性,以及良好的焊接、黏胶、磷化涂装适应性。市场应用结果表明,宝钢无机润滑处理热镀锌钢板具有良好的冲压成形性及广阔的应用前景。     

汽车翼子板零件应用技术研究

通过对汽车翼子板零件投料冲压试验，对零件进行了应变测试分析，评价试验钢板的成形效果；分析了冲压工艺，表面粗糙度和板厚等条件零件冲压生产的影响，得到翼子板零件的最佳用材方案及冲压工艺条件。     

用静电模壁润滑-温压复合工艺增高粉末冶金零件生坯与烧结件性能

对于生产静态与动态力学性能高的粉末冶金零件,在合理价格下,使零件材料达到高密度,有一定效益.采用温压-模壁润滑复合工艺是增高粉末冶金零件材料密度的一条很受人关注的途径.在试验室条件下进行的一些研究证实了这条工艺路线的潜力.在工业生产条件下,对于这种复合工艺的实际效益需要进一步探索.为确定这种复合工艺使材料达到较高密度,从而达到较高的力学性能方面能达到何种程度,在工业生产用机械式压机上进行了试验研究.这篇论文对这种复合工艺和常规的冷压与温压工艺,以及冷压-模壁润滑复合工艺的效益进行了比较与评估.     

一种环保节能的新型精细润滑方式——油气润滑

本文介绍了一种新型的集中润滑方式-油气润滑，对油气润滑的工作原理及设备设置也进行了较详细的说明，油气润滑将在工业中的具有广泛的运用前景．     

乘用车门内板冲压开裂缺陷分析

某款乘用车门内板零件的冲压生产中出现开裂缺陷问题,通过网格试验进行应变测量分析,从材料、模具以及工艺3个方面进行排查及分析,明确了该零件在冲压成形中存在开裂现象的主要因素是工艺中的辅助工序有缺陷,通过合理优化润滑条件,可以减少模具和拉伸件的有害摩擦,提高拉伸变形程度,开裂问题得到了有效解决。     

为生坯加工用强化生坯强度的润滑系统的开发

粉末冶金零件烧结后往往面要切削加工，以达到压制时无法成形的设计特征或窄小的尺寸公差。可是，随着高性能材料出现，鉴于这些材料烧结后表观硬度与强度高，采用生坯切削加工可减低切削加工费用与增强竞争性，因此，是一种很有吸引力的生产工艺。现在，采用新润滑系统可使零件在烧结前进行切削加工，这些新润滑系统和常用润滑剂相比，都是一些能大大增高零件生坯强度的聚合物润滑剂。在切削加工时，较高的生坯强度可减低生坯开裂和／或棱边剥落的危险。这篇论文对由新聚合物润滑系统或常用EBS蜡润滑剂压制的烧结硬化材料FLC-4608的脱模特性与生坯特性进行了比较。这种比较是用实验室与生产规模压机压制成形的密度为6．7～7．1g／cm^3的横向断裂试样和油泵齿轮进行的。还报告了油泵齿轮烧结后的性能和零件间性能的均一性。     

粉末冶金渗铜钢的摩擦磨损性能

通过压制、预烧和熔渗,制备1种液压零件用粉末冶金渗铜钢。用UMT 3型摩擦磨损实验机评价该材料在边界润滑条件下的耐磨性,研究基体密度对渗铜钢摩擦磨损性能的影响,并与目前常用的耐磨合金进行摩擦磨损性能对比。结果表明:在边界润滑条件下,渗铜量相同,基体材料密度分别为6.40、6.60、6.80 g/cm3的粉末冶金渗铜钢摩擦副的摩擦因数相差不大,4 h的质量磨损量分别为1.70、1.50和3.10 mg;而传统耐磨合金中硬度较低的HMn58 2铜合金磨损量为24.10 mg,磨损较快。     

影响冲压过程中钢板摩擦行为的因素

研究了不同试验条件下对两种毛化钢板冲压摩擦行为的影响,结果表明,润滑条件将影响冲压过程中的摩擦行为,润滑油种类对凹模圆角处摩擦因数影响不大,而对冲头圆角处摩擦因数的影响较大;一般随冲程的增加,钢板的凹模、冲头圆角处摩擦因数都降低,而且凹模处的摩擦因数低于冲头圆角处的摩擦因数;在同一润滑条件下,激光板的表面具有较低的摩擦因数。     

用温压制造高密度材料的关键参数

温压技术是由在加热的阴模中压制预热的粉末组成[1],已知温压有助于零件密实,从而改进烧结件的性能[2,3]。温压需要在适合温压的温度范围内进行。特别是,粉末混合粉应具有好的流动性,同时对阴模模壁有良好润滑性,以减小脱模力。在试验室和工业生产中都研究了用粘结剂处理的和未经粘剂处理的用温压技术制造的材料的性状与性能。为了确定和定量各种关键生产参数,诸如压制压力,粉末温度与阴模温度,生产速率及零件大小对生坯和烧结件特性和零件脱模力的影响,进行了专门的试验研究。依照粉末流动性与松装密度的稳定性,压制压力与温度以及压制零件的重量与密度讨论了温压的工艺性。     

A REVIEW OF SINTERED METAL BEARINGS: THEIR PRODUCTION,PROPERTIES, AND PERFORMANCE

Abstract

Five classes of sinter-based bearings are identified: steel-backed materials with compacted non-porous sintered linings for engine bearings and wrapped bushes; steel-backed materials with porous sintered linings impregnated with a plastic, intended for operation dry or with sparse lubrication; unbacked porous sintered-metal parts impregnated with oil to form self-lubricating bearings; unbacked non-porous sintered metal parts incorporating graphite; sintered polytetrafluoroethylene parts incorporating powdered metals. Methods of manufacture are outlined.

Techniques of bearing evaluation are described, the most useful being sophisticated, flexible test-rigs which approach closely the conditions of actual bearing applications.

The relative fatigue strengths of sintered engine-bearing linings are given and sintered copper-lead is shown to be equivalent in fatigue strength to cast linings.

The impregnation of sintered bronze linings with PTFE and lead yields a material with good un lubricated wear-resistance. The effect of load, rubbing speed, and other variables is described. A polyacetal lining bonded to a steel backing via a porous bronze interlayer gives a bearing material with good performance under conditions of sparse lubrication.

The relative merits of oil-impregnated porous metal bearings obtained by the pressing and sintering of copper, iron, or aluminium alloy powders are described. For optimum performance the bearing conditions should favour the formation of a hydrodynamic film of oil over the bearing surface.

The incorporation of graphite into fully compacted powder-metallurgy parts gives improved wear-resistance under dry and sparsely lubricated rubbing conditions.

PTFE parts incorporating metal powders can be moulded to finished size by powder-metallurgy techniques.     

汽车冲压零件分类的一种新方法

提出了一种汽车冲压零件分类的新方法,根据零件的几何形状和实际冲压成形过程中危险部位的变形特点,将汽车零件分为3种类型,并对32种汽车零件进行了分类。     

武钢CSP轧机活套干油润滑系统的优化

润滑对存在相对运动的零件非常重要,是降低磨损、延长设备寿命的关键。在轧钢过程中,活套处于不断运动中,这就对活套运动副间的润滑提出较高的要求。原SMSD设计的武钢CSP轧机活套润滑方式,不能满足现场使用要求,通过一系列改进措施,较好地改善了活套的润滑,减少了油脂消耗和环境污染,取得了良好的经济效益。     

立式压滤机控制系统的优化

承钢钒产品提炼过程中,钒酸铵的精制经过立式压滤机压滤、水洗、吹干等工序后,得到低水分、低杂质的钒酸铵料饼,供下道工序使用。针对钒酸铵料浆压制水洗工艺存在的问题,对立式压滤机的控制系统进行了研究并加以改进。改进后,立式压缩机的单次循环时间共减少510~780 s,吨钒产生废水量大幅度降低,设备的工作效率提高13%~30%,降低了生产备件费用。     

多台阶铁基粉末冶金结构件在CNC压机上的压制成形

本文介绍了利用CNC粉末成形液压机成形多台阶粉末冶金结构零件的方法。通过优化模具结构 ,发挥CNC独特功能 ,压制出机械压机无法一次成形的复杂零件 ,简化了生产工艺 ,节省了成本     

FACTORS CONTROLLING THE SHAPE REGULARITY OF SINTERED U02 PELLETS

Abstract

As explained mathematically, the magnitude of the ‘diabolo’ effect in sintered nuClear-fuel pellets is a function of the slope and position of the sinterability curve and the density gradient existing in the green pellets. If sinterability is representedby a straight line passing through the origin, the diabolo effect is negligible; this condition can be fulfilled when using a deactivated powder.

In any other case, the density gradient must be kept as low as possible to produce sintered pellets of regular shape. This is discussed as a function of powder roughness, lubricant quality, lubrication technique, and compaction characteristics.

When the sinterability curve cannot be adapted and powder quality and lubrication conditions are fixed, the possibility still exists of minimizing irregularities in sintered diameter by using a single-action press and compacting the powder in an adapted conical die with a moving lower punch.     

A Review of the Physical Metallurgy related to the Hot Press Forming of Advanced High Strength Steel

The automotive industry requirements for vehicle weight reduction, weight containment, improved part functionality and passenger safety have resulted in the increased use of steel grades with a fully martensitic microstructure. These steel grades are essential to improve the anti‐intrusion resistance of automotive body parts and the related passenger safety during car collisions. Standard advanced high strength steel (AHSS) grades are notoriously difficult to be press formed; they are characterized by elastic springback, poor stretch flangeability and low hole expansion ratios. Hot press forming has therefore received much attention recently as an alternative technology to produce AHSS automotive parts. In this contribution, the physical metallurgy principles of the hot press forming process are reviewed. The effect of composition on CCT curves of standard CMnB hot press forming steels is discussed taking the deformation during press forming into account. Furthermore,the effect of the static strain ageing processes occurring during the paint baking cycle on the in‐service mechanical properties of press hardened steel will be presented. The influence of temperate and strain rate on the flow stress during press forming and the final room temperature mechanical properties will be discuss ed. Moreover, the issues related to coatings on B‐alloyed CMn hot press forming steel will be critically reviewed. In particular the combined effects of thermal cycle and deformation on the degradation of the Al‐10%Si coating will be discussed in detail. Finally, the properties of both Al‐based and Zn‐based coating systems are compared, and the possibility of the formation of a diffusion barrier during press forming is discussed.     

板框式压滤机技术发展概况

通过对国内外过滤机发展历史的分析,针对其中的板框式压滤机,结合它的自身特点,把它的构成分成主要的几部分,然后按照各部分的演变、改进过程进行说明。     

THE EFFECT OF LUBRICATION ON THE PRESSING OF METAL POWDER COMPACTS

Abstract

Admixture of lubricant with metal powder can assist or retard densification according to the applied pressure and the lubricant content. Lubricant exuded on to the die wall under pressure seems to be the main lubricating factor. The change-over or transition pressure from lubrication to inhibition varies in a Gaussian manner with lubricant content. Molecular films of lubricant are sufficient, but for reduction in ejection pressure a minimum content of 0.2% lubricant is necessary. Die-wall lubrication is far more useful and effective than admixed lubricant. Simultaneous die lubrication and admixture is of no value.