典型锻模的热负荷分析

根据热锻模具的实际使用和损伤情况 ,确立了描述锻模热负荷状况的有关参数 ,并应用传热学和热弹塑性理论 ,得出了上述热负荷参数的工程计算公式 ,应用这些公式分析研究了几种典型模具的热负荷状况 ,通过比较认为 :该方法能够满足工程实际的需要。     

AlCrN涂层在热锻模中的应用

针对汽车稳定杆热锻模使用寿命较短的问题,以W6Mo5CrV2钢为基体,采用AlCrN涂层方法对模具型腔表面进行了材料改性,使模具的使用寿命获得较大提高,降低了使用成本,取得了良好的效果。     

Reduction of wear at hot forging dies by using coating systems containing boron

The near surface area of forging dies is exposed to high mechanical loads. Additionally thermal and chemical stresses appear during the hot forging process. Depending on the number of forged parts, several kinds of stresses occur in the near surface area, which lead to the initial failures of forging dies. Wear is the main reason for production downtimes with a ratio of 70%. Furthermore, thermal and mechanical cracks are typical causes for failures causes as well as plastic deformation. In order to reduce wear, the abrasion resistance of the forging die surface has to be increased. Hence, different methods like plasma nitriding and optional additional thin hard coatings (TiN, TiCN, TiC, TiBN and TiB₂) were successfully examined. Recently developed Ti–B–N coatings in specific multilayer designs are thermally stable, wear-resistant and anti-adhesive regarding the sticking of work piece material. This paper presents the wear reduction possibilities of boron-containing multilayer coating systems applied to forging dies by using the plasma enhanced chemical vapor deposition treatment. A basic mechanical and analytical characterization of different coating systems is realized in the first stage of the project. Best qualified multilayer coating variants were applied to forging dies for experimental investigations. As a result of the tests, wear can be reduced significantly by using thermally stable boron multilayer coatings. To receive realistic wear values under production conditions, an automated forging process was used for testing. After 3,000 forged parts, the coatings were examined by tactile measurement, SEM and EDX analyses to characterize the occurring wear.     

Study of the hot forging of weld cladded work pieces using upsetting tests

This paper focuses on the hot forging of multi-material cladded work pieces using upsetting tests. The case study corresponds to gas metal arc welding cladding of a SS316L on a mild steel (C15). Experimental tests and simulations using a slab model and the finite element method were performed using different temperatures and die/billet tribological conditions. As a result, a crack mode, specific to clad billets, was observed experimentally and can be predicted by the FE method using a Latham and Cockcroft criterion. The material distribution was well simulated by the FE method; in particular, the effects of the friction at die/work piece interface on the crack occurrence, the material distribution and, to a lesser extent, the forging load are well predicted. However, the latter was underestimated, highlighting the fact that the effect of the dilution associated with the cladding process on the material behavior of the clad layer cannot be neglected.     

多层金属热锻模在热锻服役下的循环载荷分析

热锻模在进行连续锻造时,型腔表层受到循环的机械载荷与激冷激热载荷,导致模具表层产生疲劳裂纹与失效。采用多层金属模具结构可以缓解热锻模所受热力载荷、提高热锻模的高温磨损性能以及热-机械疲劳磨损寿命。以直齿圆柱齿轮坯的锻造为例,利用有限元模拟和计算模型获得了均质热锻模和多层金属热锻模在连续热锻条件下的循环温度场和应力分布。结果表明,相对均质热锻模,以钴基合金为覆层、高速钢为过渡层的多层金属热锻模可以有效改善模具表层温度和应力分布;在一定程度上揭示了多层金属模具结构在热锻服役条件下的力学行为。     

Influence of heat pipe cooling on the wear of hot forging dies

The temperature of hot forging dies has a high influence on the wear of tool surfaces. In order to reduce the thermal impact on tool life, passively acting heat pipes are tested and the results are presented within this paper. For this purpose, the upper die of a commonly used hot forging tool was equipped with heat pipes and serial forging trials have been performed. The influence of the heat pipes on the die temperature as well as the effects on wear behavior are presented. The heat pipe cooling leads to a lower die temperature and thus to a reduction of adhesive wear. The wear is examined by optical and tactile measurements as well as by micrograph analyses. Conclusively, hardness tests of the tool edge layer are carried out.     

Resistance spot welding aluminium to magnesium using nanoparticle reinforced eutectic forming interlayers

Successful joining of dissimilar metals such as Al and Mg can provide significant advantages to the automotive industry in the fabrication of vehicle bodies and other important components. This study explores dissimilar joining of Al–Mg using a resistance spot welding process to produce microstructurally sound lap joints and evaluates the impact of interlayer composition on microstructural evolution and the formation of intermetallic compounds within the weld nugget. The results indicated that mechanically sound joints can be produced, with fine equiaxed and columnar dendrites within the weld nugget. The presence of intermetallic compounds was also confirmed by the variation in the microhardness values recorded across the weld zone.     

Influence of the fabrication method on the wear resistance of hot forging dies

Tools used for hot forging are subject to simultaneously acting process-related high mechanical, tribological, chemical and thermal cyclic loads. In comparison to other manufacturing methods, the resulting load spectrum leads to a failure of the form-giving tool components after a short tool life. Wear is the main reason for die failure in hot forging processes, accounting for 70?% of all causes. Other kinds of failures are thermal and mechanical cracks as well as plastic deformation (a result of the loss of hardness due to the high thermal charge). In order to reduce wear, several kinds of wear reducing methods are subject of industrial applications as well as research works. For example, nitriding and optional thin hard coating or overlay welding are effective methods to increase the wear resistance of hot forging dies. Beside the process related stresses during the service, manufacturing of forging tools itself initializes microstructural changes in their subsurface zones. During fabrication, the general influence of the fabrication method on the tool lifetime has not been considered so far. The implementation of the knowledge of this influence into the fabrication process could lead to an increased productivity of hot forging processes without using expensive and complex wear reducing methods.     

异种钢接头焊接试验

针对低合金钢、铬钼钢与不锈钢的异种接头组织、性能相差较大、甚至产生裂纹等问题,对比焊条选用、预热、热处理对接头组织性能的影响进行了焊接试验。     

5Cr2NiMoVSi钢大型热锻模的复合强化工艺及应用

对新型高热稳定性模具钢5Cr2NiMoVSi进行复合强化工艺(镀镍稀土渗硼→预冷淬火→高温回火)试验.结果表明:该处理工艺可以大幅提高5Cr2NiMoVSi钢的表面硬度、高温抗氧化性、热疲劳性能、耐磨性和耐蚀性能.将处理过的该材料用于汽车前轴大型热锻模具,取得了显著的效果.     

Heat treatment of forging dies

Conclusions In forging-die production there is a considerable range of forging dies which are promising for a changeover into advanced heat treatment involving bulk temper hardening and surface hardening using induction heating. The heat treatment suggested provides a saving of material resources as a result of improving the life of forging dies by a factor of 1.5–3 depending on the grade of die steel.As a result of induction hardening of forging dies, after temper hardening close to the boundary of the hardened layer a zone of reduced hardness forms whose unfavorable effect may be reduced by using before induction surface hardening bulk warming in a furnace or deep induction heating with a reduced energy concentration in the heating zone to the tempering temperature in the temper hardening cycle.In order to improve the uniformity of induction surface hardening for dies with a complex working shape it is desirable to use heating at reduced power with an increase in heating time.Physicotechnical Institute, Academy of Sciences of the Belorussian SSR. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 37–41, August, 1987.     

牙嵌齿轮热精锻模具设计

牙嵌齿轮因其形状所致无法切削加工，采用电解加工工艺，生产效率低，精度差、寿命低，而且电解废液污染环境，应采用热精锻工艺。本文给出了牙嵌齿轮热精锻成形的实用模具结构，论述了模具设计、装配要点。该模具采用强力脱模装置，使锻件在锻击结束瞬间可以立即脱离凸模，解决了锻件将凸模抱死的关键技术问题。     

CrMo耐热钢气体保护焊接接头焊缝金属的组织与性能

采用ф1.2 mm实芯焊丝对CrMo耐热钢进行了热输入量为8和18 kJ/cm的富氩气体保护焊试验,对焊板整体进行焊后热处理后,研究了焊缝金属的组织与性能。结果表明,随着热输入量从8 kJ/cm增加至18 kJ/cm,焊缝金属组织由板条贝氏体(LB)+粒状贝氏体(GB)转变为GB+少量多边形铁素体(PF);随着回火温度从620℃升高至660℃,焊缝金属中M-A组元逐渐分解,碳化物在基体上弥散析出;同时,焊缝金属韧性随热输入增加和回火温度降低而降低,硬度随热输入增加和回火温度升高而减小。     

Effects of current on nanoparticle reinforced magnesium alloy welding joints

Abstract

Effects of welding current on macromorphologies, microstructures and mechanical properties of nano-SiC particles strengthening activating flux tungsten inert gas welded AZ31 magnesium alloy joints were investigated by scanning electron microscope and energy dispersive X-ray spectrometer observations and microhardness and tensile tests. The results showed that SiC particles mainly dwelled in the centre and bottom zone of welding pool. Moreover, with the welding current increasing, the mechanical properties of the welding joints were improved by the increased SiC particles in welding pool, the depth/width ratios of weld pool and the refined α-Mg grain size. However, the α-Mg grains coarsened and the mechanical properties of joints decreased due to excessive heat input in welding process when welding current over 115?A.     

63 MN热模锻压力机自动锻造线上模具设计和快换技术应用

介绍了以63 MN热模锻压力机为主机的自动化锻造生产线上的模具设计、使用及快换技术。生产线主要设备为63 MN热模锻压力机、8 MN机械切边机及10 MN液压精整形机,用于生产铁路货车中型锻件。针对该生产线上不同产品的特点,设计了不同的模具布局,同时确定了模架和压力机的顶出位置。用5Cr Mn Mo作为模具基体,H13焊条堆焊锻模型腔和切边模刃口的方法制造模具,可以延长模具使用寿命。分析结果表明,模具快换技术的应用可以缩短换模时间,保证生产线高效运行。     

汽车曲轴热锻模焊锻复合电弧熔丝自动增材制造工艺

为了提高曲轴模具的服役寿命和降低再制造成本,提出了焊锻复合电弧熔丝自动增材制造工艺,并开发了相应的软件和硬件系统.在该工艺中,曲轴模具的增材目标模型被分层切片和轨迹规划,并将锤击轨迹和焊接轨迹重合从而将每一道焊缝均进行焊后锤击.锤击分析表明,焊后锤击能够将焊缝残余拉应力矫正为残余压应力,提高焊缝的力学性能.自动增材制造...     

金属温热成形模具磨损问题的研究进展

从模具磨损机理、模具磨损预测模型和模具磨损预防及使用寿命提高等方面介绍了金属温热成形模具磨损问题的研究进展。在模具磨损机理方面,简述了几个经典的磨损理论并讨论了模具材料因素和工艺条件因素对磨损机理的影响。在模具磨损预测模型方面,介绍了两大类预测模具磨损的模型和方法。在模具磨损预防及使用寿命提高方面,主要从模具材料改性和成形工艺参数优化两个角度,阐述了提高模具耐磨性、减少模具磨损、延长模具使用寿命的一些措施。对于模具磨损研究有一定的参考价值。     

基于关节机器人的电弧熔丝焊锻复合增材再制造热锻模修复

为了降低失效热锻模修复成本、提高修复效率,基于ABB工业关节机器人,开发了电孤熔丝焊锻复合增材再制造算法和装备,并用曲轴热锻模具进行再制造修复,以验证算法和装备的有效性.首先,提出增材制造目标模型的分层切片、截面复合填充算法;随后,提出满足增材再制造工艺所需的关节机器人TCP姿态控制算法,以达到控制焊枪与焊接路径夹角的...