带底深孔空心件热成形工艺改进分析

目的研究带底深孔空心件热成形工艺现状与改进措施。方法介绍分析了目前国内外所采用的新工艺、模具结构,新型润滑剂、强制润滑方法,新型模具材料、制造工艺及应用情况。结果采用压型、预冲孔、冲孔、拔伸工艺及模口导向的效果良好,通过高压将润滑剂从冲头内部流向冲孔冲头前端,可实现冲孔强制润滑,模具材料可用3Cr3Mo3VNb,4Cr2MoVNi,3Cr3Mo3W2V等,并采用表面强化等工艺。结论应用表明,上述改进措施可降低壁厚差,改进产品质量,并减小摩擦,降低成形力,比传统材料及工艺显著提高了模具寿命。最后指出了还需进一步解决的问题。     

3 Cr3 Mo3 VNb 在热冲孔中的应用研究

高合金钢热冲孔冲头寿命关系到模具与产品成本、生产效率、自动化设备的使用,因此,应注重冲头的选材、材料制备与冲头制造工艺。 用 3 Cr3Mo3 VNb 作为高合金钢热冲孔冲头,为提高模具寿命,在材料制备上,优化了成分,采用电渣重熔冶炼,减少杂质,毛坯锻造两次,用大锻造比锻造,冲头热处理用真空炉,三次回火,热处理硬度取 HRC42 ~ 46 ,冲头表面处理采用镀铬工艺,开展了热冲孔工艺试验。 结果表明,用3 Cr3Mo3 VNb 可使冲孔冲头寿命平均达到 800 件以上。     

冲头形状对液压冲孔塌陷的影响

为了研究管材液压冲孔中冲头形状对塌陷的影响规律,采用7种不同形状的冲头进行了液压冲孔实验,分析了冲头形状对液压冲孔质量的影响.实验结果表明:塌陷深度随着冲头端面倾斜角度的增大而减小,随着冲头圆角的增大而增大.提高内压能够降低塌陷深度,塌陷深度随着管内压力的增大而减小.不同形状冲头对塌陷的影响不同,斜冲头冲孔后塌陷较小,圆角冲头冲孔后塌陷较大.     

超高强钢 QP980 液压成形 B 柱仿真及试验研究

目的研究超高强钢QP980液压成形汽车B柱的可成形性。方法基于Autoform有限元模拟软件,仿真对比了宝钢第三代超高强钢QP980及当前广泛应用的DP980超高强钢液压成形B柱的可成形性,通过试验试制了QP980液压成形B柱,并与仿真结果进行对比。结果在相同工艺条件下,QP980具有较高安全裕度,DP980具有开裂风险,采用2种材料模拟壁厚减薄率及回弹趋势一致,DP980壁厚减薄率大于QP980,QP980回弹大于DP980;QP980液压成形B柱模拟及试验对比显示,壁厚减薄率和回弹变化趋势一致,试验壁厚减薄率大于模拟,样件实际回弹小于模拟,QP980液压成形B柱实测最大壁厚减薄率7.6%,一端施加约束,另一端回弹约6 mm。结论超高强钢QP980液压成形B柱成形性良好,满足零件性能要求。     

B1500HS材料热成形后冷冲切试验

目的研究热冲压零件冷冲切刀块易磨损寿命低的问题。方法设计开发一套多功能冷冲切试验模具,对热成形后B1500HS材料进行连续冲切试验,并对3组模具间隙、4种典型模具钢材质对应的冲切试样进行断面质量检测及统计,以此分析热冲压高强钢冷冲切合理模具间隙和典型冷冲切模具钢的冷冲切特性。结果 8%~10%料厚模具间隙在冲切初期毛刺较小,且在连续冲切过程中毛刺高度比较稳定,为合理的模具间隙范围;4种典型模具钢中,ASP60冲头耐磨性性能最优,SKD11冲头耐磨损性最差,SKH-9和CALDIE介于两则之间。结论热冲压钢的冷冲切稳定性及刀块寿命相对常规高强钢还存在较大差距,针对其冲切特性有必要开发更高寿命、高性价比的模具钢及热处理方法,以提高刀块寿命和生产效率,降低零件制造成本。     

摆线液压马达内花键输出轴冷锻成形工艺与模具研究

目的 为了提高摆线液压马达内花键输出轴零件的加工效率及材料利用率、降低生产成本,提出一种冷精密成形的工艺与模具。方法 首先分析了摆线液压马达内花键输出轴的形状特点,初步制定了三工序冷挤压成形工艺:正挤细杆—反挤深孔—反挤花键孔,并通过数值模拟和实物实验对该成形工艺进行分析验证。在工艺实验中发现,采用线切割方法加工的第3序通体花键形状冲头,在与冲头套下端面交界处极易发生断裂。因此对花键冲头的结构和加工方法进行了调整,将冲头整体设计为圆柱台阶状,头部采用电火花加工方法加工一段花键形状,花键与圆柱部分采用锥角过渡。结果 实验结果显示,锻件成形工艺稳定,成形锻件精度较高,改进后的冲头寿命较高。结论 内花键输出轴成形工艺可行,改进的冲头结构降低了冲头产生应力集中的风险,提高了抵御偏载力的能力,成形工艺与模具满足了批量生产的考核。     

液压成形同步冲孔工艺仿真分析及试验

对液压冲孔过程进行分析,介绍了液压成形同步冲孔的工艺原理,分析了不同类型液压冲孔的特点和应用范围。采用有限元分析方法,建立了液压冲孔仿真有限元模型,并对冲孔过程中应力分布和应变变化情况进行分析。在此基础上,进行液压冲孔工艺试验,把工艺试验结果与有限元分析结果进行比较。结果显示,液压冲孔仿真分析与工艺试验呈现相同的变化规律,仿真分析能够较好预测实际冲孔过程。     

齿套闭塞式锻造成形研究

目的 为了解决某截齿齿套锻压载荷大、模具寿命低、齿套腔充填难等技术问题.方法 采用数值模拟的方法,选取不同的始锻温度和冲头进给速度,对截齿齿套热锻成形过程进行模拟分析,根据模拟结果优化参数.结果 研究发现上下冲头载荷的增长趋势基本一致,但在成形伞头侧壁及伞头尾部时,下冲头成形载荷的增长率相较于上冲头有所增加.采用上冲头进给速度为10 mm/s,下冲头进给速度为23.50 mm/s,始锻温度为1000℃的优化参数,其最大成形载荷不会出现明显增加,另外最大等效应力和最大损伤因子皆较小,并且金属填充效果良好.结论 通过分析始锻温度和冲头进给速度对截齿齿套成形的影响,并对其进行优化和控制,得出了最优工艺参数区间,为实际生产提供了参考依据和理论指导.     

激光单道熔覆成形的金属零件壁厚模型的研究

为掌握激光熔覆成形壁厚的变化规律,提高成形薄壁结构能力,对激光单道熔覆成形的金属零件壁厚进行了研究,提出并验证了激光单道熔覆成形金属零件壁厚的理论模型.研究表明,在一定简化条件下,根据能量平衡和物质守恒定律,推导出较低功率、较小光斑的激光单道熔覆成形的金属零件壁厚的理论模型,该模型显示单道熔覆成形的零件壁厚是各工艺参数和材料热物理特性的函数.采用500W功率连续输出的CO2激光以较小光斑进行单道熔覆成形,实验得到了最小壁厚为0.4 mm的薄壁试样,试样壁厚与理论模型计算的壁厚比较一致.     

星形套冷态闭塞式精锻成形分析

目的提出星形套冷精锻成形工艺优化方案,提高模具使用寿命,对生产操作进行规范。方法分析零件结构,确定了合理的分模面;运用数值模拟方法,选取不同的冲头进给速度和冲头形状,对星形套冷精锻成形过程进行了模拟分析。结果获得了冷精锻成形过程中冲头进给速度和冲头形状对温度场、应力场、金属速度场、工作载荷和模具寿命的影响。结论通过分析冲头进给速度和冲头形状对星形套成形的影响,并对其进行控制和优化,得出了最优工艺参数区间,为实际生产提供了参考依据和理论指导。     

基于数值仿真的十字型内高压成形吸能盒优化设计

目的 实现吸能盒的高碰撞吸能性和低成本化设计。方法 以传统的方形冲焊结构吸能盒为研究对象,将其优化为十字型冲焊和十字型内高压成形结构吸能盒,并利用成形数值仿真技术对十字型内高压成形吸能盒进行了成形性研究,还利用碰撞数值仿真技术对3种吸能盒结构进行了碰撞性能研究。结果 为提高碰撞吸能性,将传统方形冲焊结构吸能盒的4条主吸能常规传力路径,优化为十字型冲焊和十字型内高压成形结构吸能盒的12条主吸能传力路径,十字型内高压成形吸能盒同时能实现减重6.4%;利用成形数值仿真技术对十字型内高压成形吸能盒进行了成形性研究,结果显示十字型内高压成形吸能盒通过一模十二件生产,能具备优良的可制造性和经济性,相比方形冲焊吸能盒,十字型内高压成形吸能盒可实现降成本5.7%;利用碰撞数值仿真技术对3种吸能盒进行正面100%碰撞和正面40%偏置碰撞性能研究,相比方形冲焊吸能盒,结果显示十字型内高压成形吸能盒吸收能量分别增加12.8%和32.0%,碰撞力峰值分别降低8.4%和39.2%,比吸能分别增加20.5%和41.0%。结论 相比方形冲焊吸能盒,十字型内高压成形吸能盒可实现轻量化、低成本和高碰撞吸能性,同时还兼具优良的可制造性的特点。     

Springback prediction and reduction in deep drawing under influence of unloading modulus degradation

Springback is considered as one of the major problems in deep drawing of high-strength steels (HSS) and advanced high-strength steels (AHSS) which occurs during the unloading of part from the tools. With an ever increasing demand on the automotive manufactures for the production of lightweight automobile structures and increased crash performance, the use of HSS and AHSS is becoming extensive. For the accurate prediction of springback, unloading behavior of dual phase steels DP600, DP1000 and cold rolled steel DC04 for the deep drawing process is investigated and a strategy for the reduction of springback based on variable blankholder force is also presented. Cyclic tension compression tests and LS-Opt software are used for the identification of material parameters for Yoshida-Uemori (YU) model. Degradation of the Young’s modulus is found to be 28 and 26 and 14 % from the initial Young’s modulus for DP600, DP1000 and for the DC04 respectively for the saturated value. A finite element model is generated in LS-DYNA based on the kinematic hardening material model, namely Yoshida-Uemori (YU) model. The validation of numerical simulations is also carried out by the real deep drawing experiments. The springback could be predicted with the maximum deviation of 1.1 mm for these materials. For DP1000, the maximum springback is reduced by 24.5 %, for DP600 33.3 and 48.7 % for DC04 by the application of monotonic blankholder force instead of a constant blankholder force of 80 kN. It is concluded that despite the reduction of Young’s modulus, the springback can be reduced for these materials by increasing the blankholder force only in last 13 % of the punch travel.     

TP304H与12Cr1 MoV锅炉管异种钢的焊接

利用舍夫勒组织图对韶关发电厂SA2 13TP30 4H与 12Cr1MoV异种钢接头可能出现的焊接组织进行了分析 ,制订出了合理的焊接工艺 ,并对锅炉上的SA2 13TP30 4H与 12Cr1MoV钢焊口进行了施焊 ,经 17个月的运行 ,10 4个焊口未出现爆漏现象     

Study of curvature and pre-damage effects on the edge stretchability of advanced high strength steel based on a new simulation model

Edge cracking is one of the common failures during the stamping of Advanced High Strength Steel(AHSS). The limit strains of the edge are hard to predict by traditional methods because edge formability is influenced by many factors such as edge quality, process parameters, material properties and so on. Hole expansion tests are conducted with DP780 under three hole diameters and two punching clearances to investigate the effects of curvature and pre-damage caused by punching on edge stretchability. The corresponding simulations are carried out meanwhile with a new model based on Marciniak and Kuczynski (M-K) model and Hill’s localized necking theory to predict the edge limit strain. This new model is proposed for the hole edge with pre-damage and improves the predictability of edge cracking in hole-expansion simulation. The problem that the traditional ideal model fails to predict the hole expansion ratio (HER) of pre-damage edge is also successfully solved by the new model with the use of the Damage Zone and Effective Failure Strain Ratio (EFSR). The comparison between the experiments and simulations reveals that this new model can be used in edge forming failure prediction of AHSS.     

2A16 铝合金锥形件多级充液热成形仿真及优化分析

目的解决2A16铝合金锥形件常温充液成形困难、表面质量差的问题。方法介绍了充液热成形工艺,并提出了3种锥形件成形方案,通过专用有限元软件Dynaform对所有方案进行了数值仿真;同时,对一步成形方案进行了试验。结果通过试验验证了有限元模型的正确性。由仿真分析可知,成形缺陷包括悬空区起皱和凹模圆角及底部破裂,一步成形方案不可取,两步成形方案均可以将减薄率控制在13%以下。起皱危险主要发生在零件法兰以下30~55 mm处。结论充液热成形与常温充液成形相比,可以显著提高材料的成形性;两步充液热成形方案可以获得2A16铝合金锥形件;预成形凸模的形状设计对零件的表面质量影响明显;最终确定用先热冲压筒形件,后充液热成形的工艺方案,来成形2A16铝合金锥形件。     

Yb:YAG laser welding of TRIP780 steel with dual phase and mild steels for use in tailor welded blanks

Advanced high strength steels (AHSS) are essential to meet the demands of safety and fuel efficiency in vehicles. In this paper, we present the results of laser welding of two AHSS steels, TRIP780 and DP980. A 2 kW Trumpf TRUDISK 6002^® Yb:YAG laser beam was utilized to join 1 mm thick TRIP780 with 1.5 mm thick DP980 and 1 mm thick mild steel. Optical metallography was used to characterize the weld profile and microstructures. Microhardness, tensile and fatigue tests were performed to evaluate the mechanical properties. Results indicate that the laser welds exhibit excellent strength and hardness with minimal defects which are attributed to the high beam quality, disk type of laser. In addition, there is a distinct effect of pre-straining of TRIP780 steels on the energy absorption.     

Cr12MoV钢焊接区表面高频淬火后的超塑性焊接

对Cr12MoV钢进行表面高频淬火后超塑性焊接,选用的工艺参数为:加热温度为800℃,焊接时间t=5min,预压应力σ0=56.6MPa,初始应变速率ε0=2.5×10-4s-1。对接头组织进行了观察和分析。试验结果表明,焊接区局部高频淬火后的Cr12MoV钢在其超塑变形温度及应变速率范围内,经短时间超塑焊接,其接头抗拉伸强度可以达到母材值。     

2024 铝合金难成形高锥盒形件充液成形数值模拟

目的解决锥盒形件传统拉深成形十分困难,废品率高,成形质量差的问题。方法介绍了充液成形工艺的2种方式,即主动式充液成形和被动式充液成形,并利用有限元软件Dynaform对各充液成形方案进行了数值模拟。结果通过模拟分析,明确了2种充液成形方式的优缺点,提出了被动式-主动式充液成形方案,并进行了数值模拟验证;合理的预成形凸模圆角大小是A侧长边底部圆角R=40 mm,B侧长边底部圆角R=30 mm,其他底部圆角R=15 mm。结论充液成形技术与传统拉深相比,具有一定的优势;被动式-主动式充液成形方案数值模拟结果良好;预成形形状对终成形有很大的影响,改变预成形凸模圆角可控制各侧补料量。     

The limit drawing ratio and formability prediction of advanced high strength dual-phase steels

Dual phase (DP) steels, being among advanced high-strength steels (AHSS), have been successfully used in the sheet metal stamping of automotive components for its great benefit in reducing vehicle weight while improving car safety. In their practical application, one of the major challenges is related to formability prediction of onset crack. This paper first conducts limiting drawing ratio (LDR) experiments to identify the maximum blank diameter of SPFC340, DP600, DP800 and DP1000 with onset crack. The fracture modes of these four types of blanks are then compared and classified into two categories: necking crack and shear crack. Further for DP1000, appropriate hardening formula is determined to fit the flow curve derived by the tensile test. Three yielding models (Hill-48, Batlat-89 and Banabic-2005) are compared with each other in the numerical simulation of DP1000 LDR onset crack. The investigation shows that a Swift and Hockett–Sherby combined formula is in good agreement with the flow curve of the tensile test and Batlat-89 yield model successfully predicts the onset shear crack of DP AHSS.