汽车推力杆热铆接质量控制及工艺设计研究进展

近年来,很多学者对重型汽车推力杆的热铆接工艺进行了深入研究,热铆接质量的精确控制以及推力杆铆接工艺则成为了研究的重要课题。为了便于今后研究者工作的开展,本文总结了重型汽车推力杆铆接过程中对铆接工艺参数以及质量控制方面的发展,并指出了今后的研究方向。     

DMAIC流程在AC-pin铆接质量改进中的应用

通过对C企业AC-pin铆接过程系统实施六西格玛DMAIC流程来提高AC-pin铆接质量。首先,对问题进行定义,明确项目的改进范围和改进目标。接着,分析AC-pin铆接过程的主要缺陷类型,并对相关测量系统进行评价与改进。在此基础上,进一步分析导致AC-pin铆接缺陷的根本原因,并确定相应的改进方案,使AC-pin铆接缺陷由先前的7000ppm降到500ppm以下,同时产量得到显著提高。最后,对关键质量特性建立相应的控制方案和纠偏措施,以使改进成果得以保持。DMAIC流程在AC-pin铆接质量改进中的成功应用有助于促进六西格玛管理在我国企业的有效实施,提升企业的质量管理水平。     

Comparing mechanical behaviour of aluminium welds produced by laser beam welding (LBW), friction stir welding (FSW), and riveting for aeronautical structures

Three welding processes for aluminium parts have been considered for aircraft fabrication: riveting, friction stir welding (FSW) and laser beam welding (LBW). These processes have advantages and threats, which were analysed in the present work focusing on T-pull and Hoop tensile properties. Concerning T-pull tests, LBW coupons presented higher ability to withstand the applied loads. This was due to the better distribution of loads when the strain is done in the stringer direction. In the case of the Hoop tests, which stress only the skin, the results obtained after FSW were notably higher in terms of ultimate tensile stress, yield stress and maximum strain. It was concluded that both LBW and FSW could replace riveting usually applied for commercial aircraft manufacturing.     

浮动悬臂式折边扣缝模设计

介绍了全自动洗衣机不锈钢内桶成形工艺 ,将折边、扣缝二道工序在1副模具内完成 ,可节省模具费用     

Prediction of Cross-Tension Strength of Self-Piercing Riveted Joints Using Finite Element Simulation and XGBoost Algorithm

Self-piercing riveting(SPR)has been widely used in automobile industry,and the strength prediction of SPR joints always attracts the attention of researchers.In this work,a prediction method of the cross-tension strength of SPR joints was proposed on the basis of finite element(FE)simulation and extreme gradient boosting decision tree(XGBoost)algorithm.An FE model of SPR process was established to simulate the plastic deformations of rivet and substrate materials and verified in terms of cross-sectional dimensions of SPR joints.The residual mechanical field from SPR process simulation was imported into a 2D FE model for the cross-tension testing simulation of SPR joints,and cross-tension strengths from FE simulation show a good consistence with the experiment result.Based on the verified FE model,the mechanical properties and thickness of substrate materials were varied and then used for FE simulation to obtain cross-tension strengths of a number of SPR joints,which were used to train the regression model based on the XGBoost algorithm in order to achieve prediction for cross-tension strength of SPR joints.Results show that the cross-tension strengths of SPR steel/aluminum joints could be successfully predicted by the XGBoost regres-sion model with a respective error less than 7.6％ compared to experimental values.     

Ti45Nb铆钉脉冲电流辅助压铆成形性能分析

为改善Ti45Nb铆钉紧固飞机碳纤维增强复合材料（CFRP）结构时的连接性能,拓宽普通铆钉的适用紧固范围,降低铆接成本,提高连接强度,引入了脉冲电流来辅助压铆。设计了电流前处理辅助铆接试验和同步电流处理辅助铆接试验,围绕两种新工艺及其与常规铆接工艺之间的紧固质量与特性展开了对比研究。测试了不同工艺下铆钉截面的典型硬度,对比观测了铆钉不同区域的微观金相与组织成分,分析了电流导致微观组织差异及元素成分区别的原因,最后评估了不同接头的拉伸强度与破坏行为,测试结果验证了电流辅助铆接工艺的有效性与可行性。     

退火处理对钛合金自冲铆接头疲劳特性的影响

对钛合金自冲铆接头整体进行去应力退火处理,并对热处理前后的接头进行静拉伸及疲劳试验;采用三参数幂函数表达式对热处理前后接头的疲劳试验数据进行拟合,得到热处理前后接头的F-lgN曲线;运用扫描电子显微镜对疲劳失效后接头的铆钉断口进行微观观察,并对比分析去应力退火对接头疲劳特性的影响. 结果表明,铆钉断裂为接头在疲劳试验中的主要失效模式;去应力退火对接头疲劳失效模式有很大影响,使得接头在疲劳试验中的薄弱环节具有由铆钉向基板转变的趋势;去应力退火热处理提高了接头在中等寿命区的疲劳特性,但降低了钛合金自冲铆接头在长寿命区的疲劳特性.     

一种基于DSP控制的飞机电磁铆枪控制电路设计

设计一种基于DSP控制的飞机电磁铆枪控制电路,依据电磁铆枪在飞机构件铆接过程中的技术要求,设计出充电电压采集电路、充电回路控制电路以及放电回路控制电路.     

Avoiding knife-edge countersinks in GLARE through dimpling

Traditional machine countersinking practices create a knife‐edge condition in one or more of the outer aluminium layers in riveted GLARE joints. Press countersinking (dimpling) provides an alternative method of countersinking that prevents the formation of a knife‐edge; however, its application and potential benefits to fatigue performance in GLARE are not known. This paper investigates the dimple‐forming process and its application to GLARE, and the resulting benefits in fatigue crack‐initiation life in unfilled rivet holes. Initial results showed that the limited formability of GLARE complicates the dimpling process, but that dimpling shows promise as a method for increasing the crack‐initiation life of riveted GLARE joints.     

LMB50型智能旋铆机的设计及研究

针对轮毂轴承铆接加工过程中存在的微调不方便、加工精度不高等问题,基于闭环控制原理,设计研究了一种可编程序控制器和伺服电机控制进给位移的新型旋铆机。该旋铆机的升降装置采用了大功率伺服电机、行星减速机和重型滚珠丝杠驱动,外加光栅尺构成了闭环控制;检测装置采用了精密级高度计作为检测传感器检测实际毛坯高度和加工后成品的高度;通过在工件夹具下方装设轮辐称重传感器以实时反馈旋铆加工时的工作压力。实践结果表明,该旋铆机实现了加工坐标值自动调整和毛坯材料性能的自动检测,从而实现了轮毂轴承零游隙和负游隙的控制,同时降低了轮毂轴承的各零件制造精度要求。