【作者】 孙宁；

【导师】 姜生元；

【作者基本信息】 哈尔滨工业大学 ， 机械工程（专业学位）， 2019， 硕士

【摘要】 超大规格硬质铝合金预拉伸厚板(简称硬质铝合金厚板)是现代大飞机制造不可或缺的材料,硬质铝合金厚板在经过轧制和淬火工艺处理后,其内部会存在很大的残余应力,这种残余应力如不及时消除,将会导致硬质铝合金厚板应力腐蚀及疲劳断裂敏感性增加,从而降低部件的使用寿命,影响飞机的飞行安全性能,因此有效消除硬质铝合金厚板内部残余应力,是实现航空用硬质铝合金厚板生产工艺不可或缺的重要环节。目前,消除硬质铝合金厚板中的残余应力,最行之有效的办法就是在硬质铝合金厚板淬火后进行预拉伸矫直,利用其塑性变形早期阶段来释放应力,使其内部沿厚度方向上的残余应力重新分布并趋向均匀。为消除硬质铝合金厚板内部的残余应力,东北轻合金有限责任公司(简称:101厂)从意大利引进了预拉伸矫直设备“8500T铝板拉伸机(简称:拉伸机)”,但是该设备在实际拉伸矫直厚度为180-200mm硬质铝合金厚板的生产过程中,经常发生硬质铝合金厚板在拉伸机钳口处局部断裂情形,这不仅影响了硬质铝合金厚板的质量、成品率和经济收益,同时还容易对拉伸机设备本体造成损坏,引发设备故障和安全事故。本课题针对此情况,从分析硬质铝合金厚板在拉伸机钳口处发生局部断裂的原因入手,以优化拉伸机夹持钳口,减少厚度为180-200mm的硬质铝合金厚板在拉伸机钳口处发生局部断裂为目标,开展对拉伸机夹持钳口优化及其试验研究,用以解决硬质铝合金厚板进行预拉伸矫直过程中在钳口处频繁发生局部断裂这一技术难题。首先,开展了拉伸机钳口组件与硬质铝合金厚板相互作用力学特性分析,介绍了拉伸机系统组成及功能参数,并从其夹持钳口的结构组成和工作原理上分析了易造成夹持端部应力分布不均的原因。针对拉伸机钳口组件与硬质铝合金厚板的相互作用形式,分别开展了硬质铝合金厚板力学特性分析、末端执行机构力学特性分析和支撑结构件力学特性分析,以材料力学特性分析的形式获得了硬质铝合金厚板应力大小及分布情况。其次,针对拉伸机钳口组件与硬质铝合金厚板之间力学作用关系,开展了硬质铝合金厚板拉伸断裂模式数值模拟研究。基于有限元分析理论,利用ANSYS有限元仿真软件建立拉伸组件仿真模型,对钳口及硬质铝合金厚板夹持端的拉伸特性进行有限单元法数值模拟分析。根据分析结果对夹持钳口重新建模,并开展相应的夹持刚度和应力分布仿真分析,优化夹持钳口设计参数。最后,为与上述力学特性分析和数值模拟分析结果相互验证,开展了基于改进夹持钳口的硬质铝合金厚板拉伸试验研究。根据理论受力分析与仿真模拟中优化的钳口结构参数,对夹持钳口进行了改进设计,并进行了多组硬质铝合金厚板拉伸试验,并与钳口改进前的拉伸效果进行了对比。经过拉伸机夹持钳口的优化改进,以及对改进后的硬质铝合金厚板拉伸性能测定、拉伸试验验证和拉伸质量分析,验证了硬质铝合金厚板拉伸矫直夹持钳口优化的技术可行性。最终用最少的资金投入、最短的时间影响、和最小的设备改动,解决了厚度为180-200mm硬质铝合金厚板在预拉伸工艺过程中出现其在钳口处局部断裂的这一技术难题,实现了国产大飞机用超大规格硬质铝合金厚板的顺利生产。更多还原

【Abstract】 The super-large pre-stretching heavy plate of aluminum alloy(referred to as the hard aluminum alloy heavy plate)is an indispensable material for modern large aircraft manufacturing.After being rolled and quenched,there will be a lot of residual stress in the hard aluminum alloy heavy plate.If this residual stress is not removed in time,it will lead to increased stress corrosion and fatigue fracture sensitivity of hard aluminum alloy heavy plate,thus reducing the service life of components and affecting the flight safety performance of ai rcraft.Therefore,effectively eliminating the residual stress inside the hard aluminum alloy heavy plate is an indispensable link to realize the production process of hard aluminum alloy heavy plate for aviation.At present,the most effective way to eliminate the residual stress in the hard aluminum alloy heavy plate is to conduct pre-stretching straightening after hardening.The early stage of plastic deformation is used to release the stress so that the interior residual stress in along the thickness direction is redistributed and tends to be uniform.In order to eliminate the residual stress inside the hard aluminum alloy heavy plate,Northeast Light Alloy Co.,Ltd.(hereinafter referred to as: 101 plant)has introduced the pre-stretching straightening equipment "8500T aluminum plate stretcher(hereinafter referred to as: stretcher)" from Italy.However,in the stretching process of the 180-200 mm thick hard aluminum alloy heavy plate,local fracture often occurs to the plate in the stretcher jaws.It no t only affects the quality,yield and economic benefits of the hard aluminum alloy heavy plate,but also easily causes damage to the stretcher itself,causing equipment failure and safety accidents.According to the a.m.situation,this paper starts with c ause analysis of local fracture on the plate in the jaws,sets the object as eliminating local fracture on the 180-200 mm thick hard aluminum alloy heavy plate,optimizes the stretcher jaws and carries out experimental study,to solve the technical problem that local fracture frequently occurs at the jaws during the prestretching and straightening process of hard aluminum alloy heavy plate.Firstly,the mechanical properties of the interaction between the stretcher jaws and the hard aluminum alloy heavy plate are analyzed,the composition and function parameters of the stretcher system are introduced,the reason of uneven stress distribution at the jaws is analyzed according to the structure and working principle of the stretcher jaws.In view of the interaction form between the jaw component of the stretcher and the hard aluminum alloy heavy plate,the mechanical characteristics analysis of the hard aluminum alloy heavy plate,the mechanical characteristics analysis of the end actuator and the mechanical characteristics analysis of the supporting structure are carried out respectively.The stress size and distribution of hard aluminum alloy heavy plate are obtained by means of analysis of mechanical properties of materials.Secondly,the numerical simulation of the tensile fracture mode of hard aluminum alloy heavy plate is carried out according to the mechanical interaction between the jaw component of the stretcher and the hard aluminum alloy heavy plate.Based on the finite element analysis theory,the finite element simulation software ANSYS is used to establish the simulation model of the tensile component,and the finite element method is used to conduct numerical simulation analysis of the tensile characteristics of the jaws and the clamping end of hard aluminum alloy heavy plate.According to the analysis results,the clamping jaws are modeled again and the corresponding clamping stiffness and stress distribution simulation analysis are carried out,to optimize the design parameters of the jaws.Finally,in order to verify with the results of mechanical analysis and numerical simulation,the tensile test of hard aluminum alloy heavy plate based on improved clamping jaws is carried out.According to the optimized structure parameters of the jaws in the the oretical force analysis and simulation,the design of jaws is improved,and several groups of tensile tests of hard aluminum alloy heavy plates are carried out,and the tensile effects are compared with those before the improvement of jaws.The technical feasibility of the optimization of the stretcher jaws is verified after the tensile properties measurement,the tensile test verification and the tensile quality analysis are carried out on the hard aluminum alloy heavy plate after the optimization of the stretcher jaws.In the end,with the minimum capital investment,the shortest time effect and the minimum equipment modification,the technical problem of local fracture of the 180-200 mm thick hard aluminum alloy heavy plate at the stretcher jaws in the pre-stretching process is solved,and the smooth production of the super-large hard aluminum alloy heavy plate for domestic large aircraft is realized.更多还原