提高针阀体流动特性及喷孔表面质量的挤压研磨技术研究

针阀体流量系数及喷孔表面质量对发动机燃油动力性及排放有重要影响。研究了挤压研磨工艺参数对喷孔表面质量及流动特性的影响规律。首先分析了研磨剂中磨料颗粒材质、粒径及浓度对加工效果的影响,随后设计试验研究挤压研磨压力和时间对加工效果的影响。结果表明:在一定范围内增加压力和时间能提高表面质量及流量系数增加率。     

模糊控制在针阀体挤压研磨设备中的应用

提出将模糊控制方法用于针阀体挤压研磨过程中。用流量计采集通过针阀体孔径的实时流量,计算差值和差值的变化率,利用模糊数学的方法通过模糊化以及模糊推理得出模糊控制量,经过模糊判别之后,将模糊控制量清晰化为实际控制输出量。实际加工实验证明,模糊控制方法有效抑制了因针阀体前期工艺参数差异而导致的加工误差,降低了针阀体偶件的流量散差,降低了废品率,提高了加工效率。     

基于动态指数平滑法的针阀体加工流量预测

用指数预测方法对针阀体研磨过程进行控制、研究,分析了传统指数平滑预测模型的不足,在此基础上,提出动态指数平滑法的模型,并将其应用于针阀体高精度研磨过程的停机判断。利用二分法的优化算法得到精确的动态平滑系数。通过分析实验数据,针阀体的加工精度得到显著的提高。     

基于神经网络的针阀体挤压研磨工艺模型

针阀体的挤压研磨加工是一个受多参数影响的复杂随机的过程,很难建立一个全面而准确的工艺模型。以人工神经网络建模技术为基础,以自制的ASF/I-IS型高精度智能挤压研磨机床为实验平台,通过对ZCK154S427型针阀体进行加工以获得样本数据,建立针阀体挤压研磨工艺模型,模型以系统压力、磨料粒度和磨料浓度为输入参数,以流量增速和流量误差率为输出参数。测试结果表明,该模型的预测值与实际值误差较小,能够较好地反映针阀体挤压研磨效果指标与工艺参数间的工艺规律。     

喷油咀针阀体通用钻模设计及加工

喷油咀偶件是柴油机上精密部件之一。喷孔加工工序又是针阀体加工中一道关键工序,喷孔质量的好坏将直接影响到柴油机的动力性能参数。图1所示的零件是长型四孔喷油咀针阀体。该种形式的针阀体零件喷孔多,孔径小,其孔径一般在0.2～0.3范围内居多,几何形状复杂,这对于钻模设计、模具制造、喷孔加工都带来了一定的难度。图2所示的模具是用于加工长型多孔针阀体工件喷孔的钻模。一次定位装夹就能完成钻削多个喷孔的任务。一、钻模结构     

针阀体研磨过程流量增速回归方程的建立

用回归设计的方法对磨料浆体射流研磨过程的关键因素进行研究,提出了利用二次响应曲面法建立针阀体喷孔研磨过程的回归方程。通过分析组合试验数据,建立了基于系统压力、磨料粒度和磨料浓度3个关键因素的流量增速回归方程,并给出了回归方程的显著性检验,为进一步的定量研究提供可能。     

长型多孔针阀偶件的喷孔加工(下)

三、国外加工针阀体喷孔的方法国外油泵油嘴厂加工嘴孔大都采用钻、铰加工方法,喷孔表面粗糙度可达到Ra1.25μm,孔径公差为0.006mm,保证了多孔式针阀偶件的性能。以瑞士DUAP公司介绍的专用设备加工长型针阀体喷孔为例,它的加工如图7所示。其特点是在钻、铰喷孔的同时,又能去除工件压力室与喷孔交叉边缘的毛刺。将工件套在分度头的心轴上,并对准定位销,由转轴转动摇臂,再用挡板在轴向方向上压紧工     

行星式永久磁体研磨夹具的应用

图1是精密针阀偶件针阀体工艺简图,对大端面的研磨加工质量要求高:平面度为0.0009mm;粗糙度为Ra0.2μm。该端面与喷油器体的端面贴合,要求密封柴油,不允许从贴合面间渗漏。因而该端面必须经过精研磨加工。人工研磨精度低,质量不稳定。为此,我厂采用行星式永久磁铁研磨夹具。     

长型孔式喷油嘴喷孔加工设备研究

本设备主要用于加工柴油机喷油嘴针阀体的喷孔,适用于油泵油嘴行业加工S.J.P系列长型多孔式喷油嘴针阀体喷孔。本设备可作以下加工过程的自动循环:钻中心孔、粗钻孔并排屑、精钻孔、去压力室内毛刺。机床动作由机械、电气、气动系统控制,通过一组凸轮装置实现一组孔的半自动加工。     

基于氩弧焊的柴油机冷却式针阀偶件的研制

冷却式针阀偶件的针阀体在普通的机械加工生产条件下是很难加工制造出来的.课题基于氩弧焊焊接加工工艺方法,从对针阀体进行分离设计、制造,然后装配、焊接入手,研究了冷却式针阀体冷却腔的结构设计及布置、焊缝的强度控制、过热影响区对二次机械加工的影响等难题.摸索出了一套冷却式针阀偶件的制造加工方法,解决了为改善柴油机经济性而使用重油后,带来的喷孔周围结胶、积碳问题.     

Influence of the flow area around the ball valve on the flow characteristics of the injector control valve

The increase in common rail pressure can lead to increased cavitation inside the injector, resulting in degradation of injector performance and reduced life. The paper investigates the effect of the pressure block structure parameters (initial flow area around the ball valve) on the velocity field, pressure field, fuel gas phase volume fraction and drain rate of the control valve. The relationship between the initial flow area around the ball valve on the cavitation strength and unloading rate inside the valve was revealed. The results show that both the reduction of the flow area around the ball valve and the increase of the cavitation intensity inhibit the rate of oil discharge from the control valve. The reduction of the fuel flow area inhibits the expansion of the low-pressure region (0–1 MPa) within the flow layer, thus limiting the development of cavitation. The reduction of the cavitation area increases the fuel flow rate, however, the increase in flow rate increases the cavitation phenomenon, and these changes form a cycle (Reviewer 5. comment 2). The increase in cavitation inhibits the control valve pressure relief rate more significantly than the decrease in the initial flow area around the ball valve. Based on this, a stepped-pressure block model is proposed. The stepped pressure block model can effectively reduce the cavitation strength near the seal and enhance the oil discharge rate of the control valve. The study can provide a reference for the engineering optimization design of high-pressure common rail injector control valves.     

高压水磨料射流切割机制的实验研究

根据工业性切割的需要，对磨料水射流（ＡＷＪ）切割机制进行实验研究。通过射流与材料之间的相互作用过程，建立和验证了ＡＷＪ切割过程模型，ＡＷＪ切割过程主要是通过磨粒对材料的周期性切割磨削和变形磨削完成；验证分析了典型材料的切割特征（切割深度、切口宽度、冲蚀量）与切割变量（水压、靶距、切速等）的关系，以及磨料、材质两大因素的影响。实验研究结果对ＡＷＪ切割技术的开发与应用具有指导意义和实用价值。     

Modeling and simulation of useful fluid flow rate in grinding

This research established a mathematical model of the useful grinding fluid flow rate of a rough grinding wheel. The abrasive distribution matrix of the grinding wheel surface topography was programmed on the MATLAB software platform to obtain the grinding wheel porosity φ at different particle sizes. The grinding fluid flow field was simulated and studied by using the volume of fluid multiphase flow model of FLUENT. Results showed that given a certain circular velocity of the grinding wheel, a larger grinding fluid jet velocity resulted in greater useful grinding fluid flow. When the grinding fluid jet velocity was set, the useful grinding fluid flow increased with increasing circular velocity of the grinding wheel. With the increasing velocity of the grinding wheel, as affected by the airbond layer, the increasing rate of the useful grinding fluid flow decreased, and the flow likewise showed a tendency to decrease. With a certain grinding fluid jet velocity, the useful flow rate of the grinding fluid was positively proportional to the useful flow. When the grinding fluid jet velocity changed and grinding wheel velocity was set, the grinding fluid jet velocity increased as the useful flow rate decreased. When the grinding fluid jet velocity was equivalent to the grinding wheel velocity, the useful flow rate of the grinding fluid was positively proportional to the useful flow. When the minimum clearance of grinding zone h increased, the useful grinding fluid flow and useful flow rate likewise increased. When the grinding fluid jet velocity was equivalent to the grinding wheel velocity, a larger nozzle gap width increased the flow supply for the grinding fluid and the useful grinding fluid flow. However, the increase in the useful flow rate of the grinding fluid was significantly smaller than that of the nozzle flow. This condition decreased the useful flow rate of the grinding fluid.     

微磨料水射流切割头装置设计与研究

传统磨料水射流切割头的磨料靠负压吸入,可靠性差、吸入不均匀、流量不能精确控制。采用螺杆泵输送原理,设计了一种新型微磨料水射流切割头装置及控制系统。该装置采用螺杆泵主动送料,螺杆由步进电机驱动,单片机发出的控制脉冲控制步进电机的转速,步进电机的转速与磨料流量一一对应,从而将磨料定量、连续地送到切割头混合腔,实现磨料流量的精确控制。在混合腔的排出通道上设置单向阀门,解决了喷嘴堵塞后高压水直接进入磨料罐引起磨料输送系统失效问题。     

应用模糊理论预测磨料水射流切深模型的建立

以理论为基础,应用磨料水射流切割加工时的工艺参数:水射流压力、射流横移速度和磨料流量等实验数据,建立一个模糊控制模型。这个模糊控制模型可以预测在任何给定一组加工参数时,可获得的切割深度。给出磨料水射流切割铝合金实例。     

磨削液供给参数对工件表面完整性的影响

针对不同磨削液供给参数,通过CFD软件构建磨削过程中磨削区处气-液两相的磨削液喷射模型,并对喷嘴的喷射参数进行仿真与计算。通过比较不同喷射速度、喷射方位和喷射角度对磨削液流场的质量流量的影响,以及它们对喷射过程中磨削液在整个磨削区的体积分数的影响,来确定合理的喷嘴喷射方位。最后通过磨削液喷射角度对工件表面完整性影响的试验研究,为确定相对合适的喷嘴方位提供试验依据,验证磨削加工过程中磨削液供给参数选择的合理性。     

NUMERICAL ANALYSIS AND VISUALIZATION OF NATURAL GAS JET WITH MULTI-POINT INJECTION SYSTEM

Aiming at the change in intake air flow caused by the injection of natural gas in intake manifold if one simply replaces the gasoline injector with natural gas injector with the installing position of injector in intake manifold unchanged,and also the reflection of gas toward intake manifold inlet resulted from the impingement between the injected large volumetric natural gas jet and intake valve,an impulsively started natural gas jet injected from a gas injector is characterized as a three-dimensional unsteady compressible viscous turbulent flow,based on which its transient development process is numerically analyzed using general-purpose CFD codes.The predicted velocity vector maps show a vortex,which indicates the occurrence of an unsteady state jet region,is formed downstream of the jet.A schlieren apparatus is utilized to get several groups of visible schlieren photographs of natural gas jets.In the experiment,photographs of natural gas jets taken by a CCD camera are laid in a portrait processor where the shapes,tip penetration distance and injection angles of the gas jets are investigated.Comparisons between predicted results and measurements indicate an excellent agreement between simulations and experimental results.     

Cu-3镍铜合金砂带磨削试验研究

分析了Cu-3镍铜合金砂带磨削加工过程中,砂带粒度和磨削用量的不同对磨削加工效率、工件表面质量和砂带磨损的影响。采用氧化铝磨料砂带在不同的砂带线速度或磨削压力下对镍铜合金进行了工艺试验,对材料去除量、工件表面粗糙度和砂带磨损量进行了测量。研究表明:增加砂带线速度和磨削压力可在一定程度上提高材料去除率和磨削比;随着磨削压力的增大,工件表面粗糙度呈增大趋势;随着砂带粒度的增大,工件表面粗糙度呈减小趋势;砂带线速度为25m/s,磨削压力为43N,砂带粒度为P240时,镍铜合金综合磨削效果最好。     

Effect of the convergence flow conditioner on rectifying eccentric jet flow induced by a ball valve

Installing a flow conditioner is an important method for rectifying irregular and unstable flow to stable flow state within a short flow distance in fluid transportation and control industrial applications. However, classical flow conditioners (such as Laws and Zanker flow conditioners in ISO 5167) with parallel pipeline axial orifices ineffectively rectify the distinct eccentric jet flow caused by valve regulation. The convergence flow conditioner with convergent orifices was innovatively designed for rectifying the eccentric jet flow caused by a ball valve in this study. Three convergent orifice angles (8°, 10°, and 12°) defined as angles between orifice and pipeline axes were considered to compare their effect on eccentric jet flow rectification as well as with the classical Laws flow conditioner (characterized by the convergent orifice angle of 0°) under different valve openings with an experimental setup for monitoring downstream pressures that develop along the pipeline and corresponding numerical simulation used. Pressure loss and throttling effect of installing convergence flow conditioners downstream the ball valve was assessed. Analysis of distributions of the pressure, velocity, and streamline for convergent flow conditioners showed that the flow conditioner with a large convergent orifice angle can effectively improve violent eccentric jet flows, especially under a small valve opening. The axial velocity on various downstream cross sections was extracted to evaluate the velocity uniformity. A dimensionless parameter of velocity eccentric ratio was used to quantify the rectification effect of eccentric jet flow evolving in the downstream pipeline. Results showed that a short pipeline length is needed to obtain additional symmetry and uniform flow field downstream of the flow conditioner with a high convergent orifice angle, that is, the convergence flow conditioner with a high convergent orifice angle demonstrated a strong effect of flow rectification on the valve-induced eccentric jet flow. This work can help understand characteristics of flow rectification on valve-induced eccentric jet flow in scientific research, and provide guidance for the flow conditioner design in fluid engineering.