【作者】 王凯；

【导师】 孙万臣；

【作者基本信息】 吉林大学 ， 动力机械及工程， 2018， 博士

【摘要】 高压单体泵是实现高功率密度XX发动机供油系统的关键部件,高压单体泵阀芯是一个圆锥面与圆柱面相交结合的回转体,其表面质量、尺寸精度、形状精度要求很高,一直是困扰我国国产单体泵供油压力波动大、供油量不足、一致性差的重要原因。由于我国国防工业起步较晚,在装备制造及精密零部件加工方面的技术积累较少,单体泵阀芯精密加工装备及加工工艺由少数发达国家油泵企业所垄断,提升我国高压单体泵精密加工工艺技术方法是一个亟待解决的问题。本文结合总装备部预研项目(51318020206)“XX发动机单体泵精密加工工艺技术”,对高压单体泵阀芯精密加工装备及阀芯加工工艺进行了深入的理论与实验研究。以单体泵阀芯精密加工装备——阀芯精密磨床的关键部件床身、导轨为研究目标进行了床身优化设计、导轨结构设计等问题的研究。并将这些方法引入了阀芯精密磨床床身、导轨的结构设计,完成了阀芯精密磨床的研制。以自行研制的阀芯精密磨床为基础进行了阀芯精密加工工艺技术研究。应用研制开发的阀芯精密磨床及阀芯精密加工工艺技术进行了高压供油系统单体泵阀芯加工,利用加工的阀芯与其他零件装配,进行了油泵供油压力实验,最高瞬时供油压力达到1800bar,接近国际先进水平,该项技术成果在北方发动机研究所得到了应用,打破了国外的技术垄断。本文的主要研究内容及结论如下:1.以阀芯的外形结构、尺寸精度特点为依据,制定了砂轮插补阀芯外形,通过一次装夹完成阀芯所有外圆表面的磨削加工方案。系统分析了实现这种磨削方式完成阀芯磨削加工所需要的动力单元形态及数量,完成了阀芯磨床的总体设计,根据实际的加工、装配水平提出了满足阀芯加工精度的误差分配方法。通过采用优化直线导轨行程、砂轮修整、数控插补等办法,在不提高单元精度的前提下,磨床的精度提高了49%,最后通过降低工件轴中心线与Z轴导轨平行度误差使磨床各运动单元的误差满足了加工、调试过程中的要求,有效的提高了磨床整体加工精度。2.针对大尺寸、多细节床身结构优化数据量大、收敛困难、计算时间长的问题,创新性的提出了基于单元法的床身结构优化方法,研究确定了内部一致、体现特征、尺寸适当的单元划分准则。提出了以“日”字单元作为阀芯精密磨床的单元结构,同时进行了“日”字单元结构变形和频率双约束耦合优化,通过结构优化使床身单元重量降低了13.47%,而受力后变形只增加了0.0003mm,频率增加了3.19%,实现了床身结构优化的目标。同时提出了复杂结构床身平面度检测的方法,通过将床身平面拆分成相互重叠的长方形检测单元,并检测各长方形检测单元的平面度,利用振型组合的方法将各长方形检测单元的平面误差合成,实现了复杂床身结构的平面度检测。3.创新性的提出了通过对比分析导轨零件加工难度及导轨装配难度的办法来优选导轨结构形式的方法,解决了静压导轨结构形式多样、不容易判断实现难度、在设计过程中难以取舍的问题。应用该方法选择了零件加工难度小、热处理容易、装夹定位工序少、间隙调整灵活的静压导轨结构为首选静压导轨结构,实现了静压导轨设计过程优化,应用该方法完成了静压导轨结构设计。4.系统研究了导轨间隙对导轨刚度的影响,实验结果表明:随着导轨间隙增大,刚度相应变小,导轨受力后容易出现偏移;随着导轨间隙减小,刚度相应变大,使导轨运行平稳,间隙变小与导轨刚度变大的关系呈抛物线状,与理论分析结果导轨间隙变小与导轨刚度变大成反比关系略有差异,是由于导轨加工误差造成的。采用翻转测量的方法,解决了由于直尺误差带来的导轨直线精度测量误差大的问题,应用该方法进行了导轨直线精度的测量,导轨直线误差精度达到0.27μm/250mm以下。5.创新性的提出了阀芯圆锥面、圆柱面一体化的磨削方法。采用侧母线为小圆弧的大直径窄边砂轮进行插补磨削,通过对阀芯两端装夹定位、内部拖动阀芯旋转,利用砂轮侧母线圆弧磨削阀芯圆锥面、同时利用砂轮外圆面磨削阀芯圆柱面。应用该磨削方法,通过一次装夹,一个砂轮实现了阀芯全部外圆表面的磨削加工,磨床结构简单、磨削精度高、磨削表面一致性好。6、针对阀芯圆锥面、圆柱面一体化的磨削方法,建立了装夹力的计算模型,研究了装夹力对阀芯变形影响。结果表明,在阀芯材料弹性变形范围内阀芯变形随装夹力的增大而变大,最大变形区域为阀芯内锥面及圆柱环槽区域。同时,研究了砂轮圆弧磨削圆锥面的磨削方法,以定点磨削为切入点,建立了定点磨削圆锥面的数学模型,以此为基础提出了圆弧等距磨削阀芯圆锥面的数学模型,并进行了分析,确定了圆弧磨削细分的准则,根据砂轮圆弧磨削阀芯圆锥面的原理给出了基于圆弧磨削的接触弧长、未变形切屑厚度等重要磨削参数的近似计算方法,并建立了圆弧磨削阀芯圆锥面的力学模型。探索了减小磨削力的技术措施,为后续的阀芯磨削加工实验参数选择奠定了基础。7.开展了阀芯磨削加工实验,分析了磨削参数对阀芯直线度及表面质量的影响。研究结果表明,在定进给量条件下,随着砂轮转速提高,阀芯直线度相应提高;随着工件轴转速提高,阀芯直线度相应降低;随着磨削深度减小,阀芯直线度相应提高。在定磨削深度条件下,随着砂轮转速提高,阀芯圆锥面表面质量相应提高;随着轴向进给量减小,阀芯圆锥面表面质量相应提高;随着工件轴转速提高,阀芯圆锥面粗糙度变差。采用优化后的阀芯磨削加工参数进行了阀芯磨削加工实验,阀芯直线度误差低于0.75μm/100mm、表面粗糙度低于0.025μm。8.对同一新装单体泵进行了供油量及供油压力实验。研究发现,在固定供油提前角及供油持续角的前提下,随着凸轮轴转速的提高,供油量偏差相应减小,供油压力提高。在凸轮轴转速为1200r/min时,最大瞬时供油压力达到1811.34bar。同时,进行了不同单体泵的供油量测试实验,测试结果表明,随着凸轮轴转速的提高,供油量差异减小,凸轮轴转速在1000r/min的时候,供油一致性最好。在此基础上,分析了影响供油一致性的主要因素。研究发现,电控单体泵的柱塞、泵体、阀芯加工精度,电磁线圈的感抗差异,发动机转速的不均匀性都会影响供油一致性,在实际工作中供油差异是不可避免的,可以通过提高加工精度、优化供油结构、优化控制策略来减小供油差异。通过本项目的开展,提出了单体泵阀芯精密加工装备研制方法及阀芯加工工艺方法,本文所涉及的磨床关键部件的设计、优化方法同样适用于其他结构的部件。阀芯的加工工艺方法,可用于复杂回转体结构的加工。本文研究内容可为我国复杂结构回转类零件精密加工技术的发展提供一定的理论指导和借鉴。更多还原

【Abstract】 High-pressure monomer pump is key component of high power density XX engine fuel supply system,high monomer pump valve core is a solid of revolution by conical surface and cylinder,it need high surface quality,dimensional accuracy and shape accuracy requirement,it has been plagued our country domestic monomer pump oil pressure fluctuations,oil shortage,poor consistency of the important reasons.Due to the defense industry in China started late,in the aspect of equipment manufacturing and precision parts processing technology accumulation is less,monomer pump valve core precision machining equipment and processing technology enterprises dominated by a few developed countries.It is an urgent problem to improve the precision machining technology of high pressure monomer pump in our country.Based on the program(51318020206)"XX engine monomer pump precision machining technology",we make a deep theoretical and experimental research high voltage monomer pump valve core precision machining equipment and processing technology.The key components of the valve core precision grinding machine(body and guide rail)are studied with the design and machining.In addition,these methods are introduced into the structure design of the spindle precision grinding machine bed and guide rail,and the development of the valve core precision grinding machine is completed.Based on the self-developed valve core precision grinding machine,the precision machining technology of valve core is studied.High pressure oil supply system monomer pump valve core processing using precision grinding machine and technology,assemble valve core and other parts,the oil pump oil pressure experiment,the instantaneous oil pressure up to 1800 bar,close to international advanced level,the technical results have been applied in the northern institute of engine and broke the foreign technology monopoly.The main research contents and conclusions are as follows:1.Based on the shape structure and dimension precision of the valve core,the shape of the grinding wheel plug valve core was developed,and the grinding process of the entire outer surface through one clamp.Analyzes the power unit form and quantity of valve core grinding,the design of valve core grinding machine is done,present accuracy error distribution method.By adopting optimized linear guide way such as stroke,grinding wheel dressing,NC interpolation,without increasing accuracy of unit,the precision of the grinding machine increased by 49%,by lowering parallelism error between the center line of the workpiece axis and Z axis guide rail,the grinder movement unit met the requirement in the process of processing and debugging,effectively improve the whole machining precision of the grinding machine.2.Aiming at the problems of large size and multi-detail bed structure optimization data,difficulty of convergence and long calculation time,an innovative method of bed structure optimization based on unit method is proposed.In this paper,the structure of stud unit is put forward,and the structure deformation and frequency coupling optimization of stud unit is carried out.The weight of bed unit is reduced by 13.47 %,the deformation increases by 0.0003 mm and the frequency increases by 3.19%.At the same time,the flatness measuring method of the complex structure bed is put forward.By splitting the bed surface into overlapping rectangular detection units,and detecting the flatness of each square detection unit,the method of vibration combination is used to synthesize the plane error of each square detection unit to realize the flatness detection of the complex bed structure.3.Through analysis guide parts processing difficulty and guide assembly difficulty to guide rail structure,solves the hydrostatic guideway structure forms,hard to judge implementation difficulty.The method to choose the small parts processing difficulty,easy heat treatment,clamping location process easy,flexible gap adjusting static pressure guide rail structure,realizes the hydrostatic guideway design process optimization,complete the hydrostatic guideway structure design.4.Studies the guide rail rigidity influence of the guide gap.The experimental results show that with the increase of the guide rail gap,the stiffness correspondingly becomes smaller,and the deviation of the guide rail is easy to occur.With the decrease of the guide rail gap,the stiffness correspondingly becomes larger,so that the guide rail runs smoothly,and the relationship between the gap size and the rigidity of the guide rail becomes a parabola.Theoretical analysis shows that with the decrease of the guide rail gap,the stiffness correspondingly becomes larger,the relationship between the gap size and the rigidity of the guide rail is vary inversely.There is a slight difference with experimental result.Because of the error of guide rail.Flip measurement method,solve the guide rail line precision measuring error due to the ruler errors,the precision of the guide rail line error below 0.27 mm / 250 mm.5.An innovative grinding method is proposed to integrate grinding the cone surface and cylindrical surface.Adopted small arc narrow edge large diameter grinding wheel for grinding,through clamped on both ends of the valve core orientation,internal drive valve core rotary,using the grinding wheel side circular grinding valve core conical surface,at the same time,using the grinding wheel cylindrical grinding valve core cylinder surface.Using this grinding method,the grinding process of all valve core outer surface realized through a single clip,and the grinding machine has simple structure,high grinding precision and good consistency of grinding surface.6.Based on the grinding method of the valve core conical surface and cylindrical surface,the calculation model of the clamping force was established,and the influence of the clamping force on the valve core deformation was studied.The results show that in the valve core elastic deformation range,the valve deformation is larger with the clamping force increasing,the maximum deformation zone is the inner cone and the cylindrical ring groove area.At the same time,studied the method of circular grinding wheel grinding conical surface,establishing the mathematical model of point grinding giving mathematical model of circular isometric grinding valve core cone surface,identified the circular grinding segmentation criterion,according to the principle of arc grinding wheel grinding the valve core cone surface,presented based on the arc grinding contact arc length,non-deformation in grinding the approximate calculation method of critical grinding parameters such as cutting depth,and circular grinding on the surface of the cone valve core mechanics model is established.The technical measures to reduce the grinding force are explored,which lays a foundation for the selection of experimental parameters in the subsequent grinding process.7.Carried out the test of valve core grinding,and analyzed the influence of grinding parameters on the straightness and surface quality of the valve core.The results show that,with the increase of the grinding wheel speed,the linear degree of the valve is increased.With the increase of the axis speed of the workpiece,the straightness of the valve core decreases correspondingly.As the grinding depth decreases,the valve core straightness increases correspondingly.Under the condition of grinding depth,the surface quality of the valve cone surface increases with the increase of grinding wheel speed.With the decrease of axial feed,the surface quality of the cone surface increases accordingly.With the increase of the workpiece shaft speed,the surface roughness of the valve core becomes worse.The valve core grinding process was tested by the optimized grinding parameters of the valve core,and the straightness error of the valve core was lower than 0.75 mm /100 mm,and the surface roughness was less than 0.025 mm.8.The oil supply and pressure experiment were carried out for the same new single pump.It is found that,under the condition of the fixed oil supply pre angle and the continuous angle,with the increase of the camshaft speed,the quantity deviation of the oil supply decreases correspondingly and the oil supply pressure increases.When the camshaft speed was 1200r/min,the maximum instantaneous oil supply pressure reached 1811.34 bar.At the same time,the different monomer pump oil testing experiment,the test results show that with the improvement of the camshaft speed,oil supply difference decreases,and the camshaft speed at 1000 r/min,the consistency of oil supply is best.On this basis,the main factors affecting the consistency of oil supply are analyzed.Study found that the electronic control unit pump plunger,pump body,valve core processing precision,the electromagnetic coil impedance difference,the non-uniformity of engine speed will affect the oil supply consistency,oil supply difference is inevitable in the practical work,through improve the machining accuracy,improve the structure of fuel supply,optimizing control strategy to reduce oil supply.Through this project,giving the monomer pump valve core precision machining equipment production method and valve core processing method,this paper involves the design and the optimization method of the grinding machine key components are also applicable to other structural parts.The machining process of the valve core can be used for the processing of complex rotary body structure.The research can provide some theoretical guidance and reference for the development of complex structure rotary parts precision machining technology in China.更多还原