【作者】 马春生；

【导师】 张治民；

【作者基本信息】 中北大学 ， 火炮、自动武器与弹药工程， 2012， 博士

【摘要】 由于轮式战车的战略机动性好，作战和支持费用低，远距离部署起来比较方便的特点，因此世界各军事强国非常重视新型轮式战车的发展。车轮作为轮式战车重要的行驶部件，对其运载能力和越野机动性有较大的影响。从武器装备轻量化角度考虑，结合轮式战车对车轮的特殊要求，采用镁合金车轮，不仅能够减轻战车自重、提高有效载荷能力，而且提高了战车机动性和越野性。但镁合金车轮在生产和应用中存在着诸多缺点严重阻碍了其发展。本文提出了集旋压成形和挤压成形优点相结合的全浸入式等温挤旋成形技术，它是一种改善产品质量，提高材料利用率的先进制造技术。以弹塑性有限元理论为依据，对战车车轮等温挤旋成形工艺特点进行分析的基础上，完成了三维模型的建立。车轮采用AZ80镁合金，利用Deform软件进行有限元数值模拟。镁合金车轮挤旋成形过程中，挤旋轮与车轮从不接触到接触状态，由点接触转变为线接触，接触面积逐步增加，从而接触区压应力增大，改善了车轮成形质量，提高了加工精度。通过对不同工艺参数下战车车轮挤旋成形工艺过程的数值模拟，得到了温度T、进给率(径向)f、挤旋轮直径Φ和主轴转速n等工艺参数对挤旋成形的影响较大，并以此作为主要试验因素，利用正交试验法设计了试验方案，得到了一组最优的工艺参数组合：即温度T=380℃、进给率f=1.5、挤旋轮直径Φ=90mm、主轴转速n=120 n/min，车轮成形质量较好。为了清楚地了解挤旋成形变形机理，分别沿车轮壁厚、纵向和周向取点，绘制各点的应力应变曲线图，分析发现：（1）成形中金属主要在径向运动，完成车轮精密成形；（2）切向基本没有相对运动；（3）轴向车轮内外表面有相对运动，造成了壁厚的增加，这会引起车轮的扩径和不贴模现象。为了定量了解壁厚变化，对车轮成形过程简化，建立了车轮壁厚与壁厚变化量之间的数学模型，为提高车轮成形精度提供了依据。镁合金车轮成形时全部浸入在液态介质中，利用Fluent软件建立挤旋成形模型进行流体模拟。模拟结果表明由于有压力场的存在，在挤旋轮与车轮的间隙中产生负压，而且间隙越小负压越大，这对工件润滑非常有利；而速度迹线图表明，由于挤旋轮和支架的阻挡，整体流动状态呈紊流状态，这样有利于恒温槽内液态热量的传递，保证了油槽内总体温度的一致，同时解决了高温下镁合金易氧化的保护问题。针对全浸入式等温挤旋成形技术研制了挤旋成形装置，重点设计了主轴部件、主要工艺装备和恒温槽的结构。根据傅立叶定律，建立了恒温槽保温层厚度的“热导值曲线”模型，得到δ=70mm是最佳保温层厚度。装置控制系统选择AT89C52单片机为控制器，根据偏差变化选择传统PID控制与模糊控制相结合的方法，完成控制系统总体设计，提高了控制精度，增强了抗高温和抗震动干扰能力。最后以模拟分析的工艺参数为依据进行试验，试验结果与数值模拟情况基本一致，说明此项成形技术的提出和装置的设计可行，实现了镁合金车轮的精密成形，为镁合金车轮的生产技术及装置推广提供依据，为轮式战车轻量化提供思路。更多还原

【Abstract】 Due to the strategic mobility of wheeled combat vehicles, operational and supportcosts low, long-distance deployment is more convenient features, therefore the world’smilitary powers attached great importance to the development of new wheeled combat.Wheels as the chariot moving parts have a larger impact on their carrying capacity andoff-road.Considered lightweight angle from the weapons and equipment, combined with thespecial requirements of the wheeled chariot wheels. If the magnesium alloy material tomanufacture the chariot wheels, not only to reduce the chariot weight and increase payloadcapacity, but also to improve the chariot maneuverability and off-road. However, there aremany shortcomings seriously hindered its development in the production and application.This paper presents a full immersion isothermal squeeze spin forming technology; itset the spin forming and extrusion of the advantages of combining. That is a way toimprove product performance, and improve material utilization of advanced manufacturingtechnology.Based on the analysis of the chariot wheels of isothermal squeeze spin formingprocess characteristics, by elastic-plastic finite element theory, completed athree-dimensional model. Deform finite element numerical simulation of AZ80 magnesiumalloy wheels. The forming process of magnesium alloy wheels, squeeze roller and wheelsnever come into contact with the contact state, from the point of contact into line contact,the gradual increase in contact area. Due to the increase of the deformation zone, thedeformation path is more reasonable, uniform deformation. These improve the formingwheel performance, and improve the machining accuracy.Forming process to simulate by squeeze spin the wheel of the chariot in the differentprocessing parameters, the temperature T, the feed rate (radial) f, squeeze roller diameterΦand the spindle speed n, which on the squeeze spin deformation is greater impact. As the main experimental factors, the use of orthogonal experiment method to design a testprogram for optimization of process parameters design. has been one of the bestcombinations of process parameters, Temperature T = 380°C, feed rate f = 1.5, squeezeroller diameterΦ= 90mm, spindle speed n = 120 n / min, forming wheels of good quality.In order to clearly understand the deformation mechanism squeeze Spinning along thewheel wall thickness and longitudinal and circumferential take points, changes in thestress-strain curve ,found that: (1) metal forming, mainly in the radial motion, whichcomplete wheels precision forming; (2) no relative motion on tangential; (3) the axial wheelinner and outer surfaces in relative motion, resulting in increased wall thickness, which cancause the wheels expanding and punch phenomenon. In order to quantitatively find outchange of the wall thickness, simplified the wheel forming process, and the establishmentof a mathematical model between the wheels of wall thickness and wall thickness variation,and provides a basis to improve the wheel forming precision.In order to meet Squeeze Spinning thermostat requirements, magnesium alloy wheelprocessing allowed all immersed in a liquid medium. Create squeeze spinning model forfluid simulation by Fluent. The simulation results show that the existence of the pressurefield in the squeeze roller and the wheel gap, resulting in negative pressure and the smallerthe gap the negative pressure the greater, which is very beneficial to the wheel lubrication.Speed trajectories, that the overall flow state was turbulent state by squeeze the roller andbracket blocks. So that is conducive to the thermostatic tank of liquid heat transfer toensure the consistency of the overall temperature in the tank.Develops squeeze spin forming device for full immersion isothermal extrusion rotaryforming process, with a focus on design of the spindle assembly, the main processequipment and bath structure. according to Fourier’s law, establish“the value of thethermal conductivity curve”model, whenδ= 70mm is the optimum insulation thickness.Device control system takes AT89C52 microcontroller as the controller. Circuit selects thetraditional PID control and fuzzy control method of combining, select the control methodbased on change in error, complete the overall design of control systems. Improve the control precision, enhanced resistance to high temperature and vibration interference.Finally, the simulation analysis of the process parameters as a basis for the test, testresults and simulations consistent, indicating the forming technology and device design isfeasible, which can achieve precision forming of magnesium alloy wheels. Whichmagnesium alloy wheels production technology and device promotion provides the basis toprovide ideas for lightweight wheeled combat vehicles.更多还原