基于Autoform的汽车左右侧围内板前段成形的数值模拟

利用Autoform软件对汽车左、右侧围内板前段进行模拟分析,在压边力、拉深筋等因素已确定的条件下,对板料成形过程中的各个工序进行数值模拟,通过对所得到的成形极限图、厚度减薄率等性能参数的分析,判定各成形工序的合理性,最终确定最优的成形工艺。     

前围内板横梁的工艺分析及模具设计

对前围内板横梁的冲压工艺性进行了分析,详细介绍了前围内板横梁修边冲孔模的结构.通过对模具设计过程的介绍,阐述了汽车覆盖件模具的设计要点.该模具虽然结构复杂,但设计合理,在生产中使用效果良好,满足了产品设计要求,提高了生产效率.     

覆盖件拉深模压料面设计研究

以汽车覆盖件拉深工序为研究对象,利用有限元数值模拟方法,探讨了不同类型覆盖件拉深成形压料面的设计方法.结果表明：浅拉深覆盖件宜采用平压料面,能够降低拉深成形难度;深拉深覆盖件宜采用随形起伏压料面,可以保证各部分塑性变形均匀;质量要求不高的骨架类覆盖件,可将作为零件本身的翻边作为压料面的一部分.     

钢面板泡沫铝夹心板的三点弯曲行为

采用胶粘法制备大尺寸钢质泡沫铝夹心板,测试夹心板的三点弯曲强度,分析面板厚度、芯层厚度对夹心板弯曲性能的影响规律,研究弯曲载荷作用下的夹心板失效机理。结果表明：钢质泡沫铝夹心板可承受很高的弯曲载荷,夹心板抗弯强度随着芯层泡沫铝厚度的提高而提高。增加钢面板的厚度,夹心板抗弯强度整体呈增强趋势。当面板厚度为8 mm、芯层厚度为50 mm时,夹心板的极限抗弯强度可达66.06 kN。芯层泡沫铝内泡壁表面的大尺寸裂纹是夹心板在弯曲载荷作用下失效的主要原因;采用熔体发泡法制备的泡沫铝板材,因冷却强度过大而导致的附加应力使泡壁的强度下降,也是影响夹心板力学性能的主要因素。     

Effect of energy transfer modes on solidification cracking in pulsed laser welding

Abstract

In this study, solidification cracking in pulsed laser welding of fully austenitic, AISI Type 316 stainless steel has been analysed at different energy transfer modes. The pulse parameters have been selected appropriately to obtain conduction, transition and keyhole mode welds. Conduction and transition mode welds exhibit higher susceptibility to cracking than keyhole mode welds. It is observed that both heat input and energy transfer mode affect the cooling rate and hence influence solidification cracking. Microstructures of the fusion zone have been analysed, and the cooling rate experienced by the weld is estimated from the mean cell size in the weld. It is found that the critical cooling rate below which cracking does not occur is ～10⁴ K s^??1.     

Fatigue Failure of Ductile Iron Crankshafts

Abstract

Automobile crankshafts can be produced as either steel forgings or ductile-iron castings. In the latter case, because of the high structure-sensitivity of fatigue strength, mechanical test requirements must be very specific. A detailed investigation of two series of crankshafts produced from pearlitic nodular-graphite iron, grade SG 60, is described. Normal tensile tests and microstructural examinations were supplemented by determination of fatigue life and fatigue limit. Fatigue tests under axial bending conditions were carried out on segments taken from two series (I, II) of machined crankshaft castings. Satisfactory bending moment and performance data were obtained for one series of samples. In the other series, sub-surface microporosity in the cast structure was exposed during subsequent machining and led to premature fatigue failure after less than 2 × 10⁵ cycles of testing.     

安装板注射模设计

讨论了安装板塑件注射模设计的方法和步骤,介绍了在传统的模具设计基础上,采用MoldFlow、UG等相关模具软件更加科学地进行浇口位置选择、浇道、冷却系统等设计,并通过对不同方案进行分析、对比,选择较好的方案进行优化,得到最少气穴、熔接痕等缺陷的塑件,使注射成型过程在设计时就充分克服了工艺缺陷。     

A new method for evaluating cooling capacity of blast furnace cooling stave

The detailed process of the heat transfer of the cooling stave in blast furnace (BF) has been systematically analyzed and the simplified mathematical model was constructed based on heat transfer theory. Precise definitions of the cooling capacity, stable working slag thickness and safe working slag thickness were put forward so as to evaluate the cooling capacity of cooling stave systematically. The results show that 95% of heat is carried off by cooling water through convection and the heat taken away through convective heat transfer between furnace shell and atmosphere only account for 5%. The entire heat transfer process can be divided into four modules and the cooling system is divided into three parts. The cooling capacity φ is defined and function curve of temperature of cooling stave hot surface T_b with changes of brick thickness is drawn and the safe working area and stable working area are put forward.     

Maximum inclusion size in two clean steels Part 1 Comparison of maximum size estimates by statistics of extremes and generalised Pareto distribution methods

Abstract

Estimation of the maximum size of inclusions in a large volume of steel is an important issue in relation to clean steels. Statistics of extremes can be used for the estimation, and one such method, developed by Murakami and coworkers, is now used by the steel industry for characterising steel specimens. An alternative method, based on the generalised Pareto distribution, has recently been developed and has advantages. A key factor in such methods is the extent to which they can discriminate between steels of different cleanness levels. In the present paper, this discrimination is demonstrated using data from polished metallographic specimens. The confidence limit intervals are estimated using the maximum likelihood method.     

铝塑复合板用铝板基表面黄斑缺陷的研究

黄斑缺陷是铝塑复合板用铝板基生产过程中经常出现的一类表面缺陷,黄斑缺陷不仅对铝板基的前处理和涂装造成不利影响,还影响铝塑复合板的使用寿命。本文在实验室条件下对黄斑缺陷的成因进行了分析,结果表明黄斑缺陷的成因主要是退火工艺不合理和轧制油理化性能指标不符合要求。通过优化退火工艺参数和使用性能优良的轧制油,消除了黄斑缺陷。