柱塞泵预紧力对滑靴回程盘影响的仿真分析

轴向柱塞泵中滑靴的倾覆偏磨、回程盘的磨损与其所受应力大小有关。为改善二者的磨损性能,研究预紧力增大对滑靴、回程盘应力变化特性的影响。通过对A4VG125型柱塞泵中心弹簧预紧力的分析计算,应用仿真软件ADAMS和ANSYS搭建轴向柱塞泵的刚柔耦合模型,研究分析预紧力增大时,滑靴、回程盘应力的变化规律,得到同周期内最大应力点图和应力云图。分析结果表明:合理增大预紧力有助于减小滑靴平面、滑靴颈部的磨损;回程盘孔口与滑靴颈部的碰撞得到改善;当预紧力为707N时,该型号轴向柱塞泵的滑靴与回程盘应力分布状态最好。     

轴向柱塞泵滑靴的动力学特性仿真分析

滑靴与斜盘、柱塞、回程盘之间的配合是保证柱塞泵正常工作的重要条件,滑靴的磨损失效会影响与之配合零件的正常工作。首先对A4VG125型柱塞泵滑靴进行理论受力分析,应用SimulationX建立柱塞泵的一维液压模型和三维MBS模型,仿真柱塞底部所受液压力。然后与ADAMS和ANSYS建立的柱塞泵动力学模型进行联合,完成柱塞泵的刚柔与液固耦合仿真模型。在仿真工作参数作用下,研究滑靴与斜盘、柱塞、回程盘之间摩擦副的动力学特性。结果表明:当斜盘倾角增大、主轴转速提高时,对滑靴总体的受力/力矩情况影响较大;滑靴与柱塞之间的球铰副受工作参数变化影响较为明显,受力/力矩波动较为严重。     

基于斜盘式轴向柱塞泵结构优化的应用研究

针对应用于工程机械上某型号斜盘式轴向柱塞泵滑靴与柱塞组件及缸体试验出现局部严重磨损及干涉故障,从滑靴与柱塞组件及缸体的力平衡关系、滑靴与柱塞组件工艺与结构以及缸体配合间隙三个方面进行失效分析,在保证柱塞泵容积效率的前提下,提出以下改进措施：优化设计了滑靴内外辅助支撑面与中心通油孔的固定节流器结构、利用回程盘与滑靴联动配合理论进行结构优化尝试对比应用薄壁空心柱塞,将这些措施运用于产品批量制造,取得较好效果。为斜盘式轴向柱塞泵的结构优化、提高效率和性能方面提供实用经验,具有一定的综合效益和推广价值。     

柱塞泵斜盘端面磨削夹具

斜盘由弧面支撑端面,与压块配合固定滑靴和回程盘的行程。在实际工作中斜盘与柱塞滑靴间存在50～80μm的静压油膜,斜盘端面如果出现划痕直接影响到滑靴静压油膜导流槽的寿命,从而影响到柱塞泵的容积效率,甚至由于间隙过大造成滑靴与柱塞杆的脱落。由于斜盘端面积较大,人工研磨费时费力,本文中对斜盘磨削夹具做详细概述。     

基于虚拟样机技术的轴向柱塞泵回程盘动力学特性仿真分析

根据柱塞泵的故障统计数据,回程盘过度磨损、碎裂的现象时常发生。首先通过对回程盘的受力分析,计算出它在SCY14-1B型柱塞泵中的受力。然后通过ADAMS和ANSYS搭建柱塞泵的刚柔耦合动力学模型,经过仿真分析找出回程盘的受力规律和影响回程盘受力状态的因素,并得到几种情况下应力最大时刻的分布图。最后对回程盘进行模态分析,得出它的固有频率,为下一步研究工作提供依据。     

考虑表面接触力的滑靴副油膜特性分析方法

由于受倾覆力及刚体表面粗糙度影响,液压柱塞泵斜盘-滑靴运动副(滑靴副)在相对运动时处于混合润滑状态。斜盘和滑靴表面接触引起弹性和塑性变形,进而产生表面接触力。接触力与油膜厚度密切相关,在油膜特性分析时不应被忽略。提出一种基于流体动压润滑理论的滑靴副油膜特性(油膜厚度、压力分布、油膜间隙流量)的分析与计算方法,考虑了滑靴副粗糙表面的支撑力影响。在雷诺流体动压润滑方程基础上,考虑滑靴副刚体表面粗糙度水平和油膜厚度,计算液压柱塞泵不同工况下的表面接触支撑力,并将接触力融入运动副的受力方程。提出了基于改进的雷诺流体动压润滑方程的数值计算方法,并进行了仿真分析,通过间接对比滑靴副间隙流量的仿真结果,证实了提出方法的有效性和结果的准确性。     

柱塞泵早期损坏的原因

我公司生产DZYS0型移动电站在某工地运行1000h后,连续出现数台行走泵损坏故障。该机行走泵为萨澳45系列柱塞泵,其损坏部位主要是滑靴严重磨损、滑靴脱落、回程盘断裂和斜盘出现沟槽。     

滑靴材料及封严带结构对摩擦副性能的影响

目前，高压柱塞泵普遍采用滑靴的柱塞结构，滑靴不仅增大了与斜盘的接触面，减小了接触应力，而且其封严带结构，使滑靴与斜盘表面之间形成一层润滑油膜，极大地降低了滑靴-斜盘摩擦副之间的摩擦损失，提高了整泵机械效率。柱塞泵最高工作压力不同，滑靴封严带也随之采用不同结构。该文通过故障分析、理论研究和仿真计算滑靴副PV值，并结合试验验证的方式，阐述了3种不同封严带结构的滑靴在工程实际中的应用。     

基于ANSYS workbench的柱塞泵回程盘结构优化设计

针对某型号斜盘式轴向柱塞泵回程盘与柱塞组件试验出现局部严重磨损及干涉故障,利用ANSYS Workbench软件对斜盘式柱塞泵回程盘进行了强度和刚度分析,首先找出了回程盘的应力主要集中区和变形量较大的位置,为回程盘的设计提供了参考;其次,对回程盘进行了优化,在保证回程盘的强度达到设计要求的情况下,增强了回程盘的刚度,改善了泵的整体性能,为斜盘式轴向柱塞泵的结构优化、提高效率等方面提供实用经验和参考。     

一种十字摆盘驱动式轴向柱塞泵结构设计

 轴向柱塞泵作为液压系统的核心动力元件,具有额定压力高、流量大、功重比高等优点,传统斜盘式柱塞泵结构复杂,易导致滑靴磨损,且柱塞与缸体之间具有较大的侧向力易造成柱塞卡死,影响柱塞泵的可靠性及寿命。提出了一种新型十字摆盘驱动式轴向柱塞泵结构,斜盘轴旋转驱动十字摆盘摆动回程,实现柱塞的往复运动,同时高低压配液阀实现流体介质的配流,完成柱塞吸排油动作。通过模型受力分析验证,该柱塞泵具有回程结构性能稳定、侧向力小等优点,应用前景广泛。     

Integrated slipper retainer mechanism to eliminate slipper wear in high-speed axial piston pumps

The power density of axial piston pumps can greatly benefit from increasing the speed level. However, traditional slippers in axial piston pumps are exposed to continuous sliding on the swash plate, suffering from serious wear at high rotational speeds. Therefore, this paper presents a new integrated slipper retainer mechanism for high-speed axial piston pumps, which can avoid direct contact between the slippers and the swash plate and thereby eliminate slipper wear under severe operating conditions. A lubrication model was developed for this specific slipper retainer mechanism, and experiments were carried out on a pump prototype operating at high rotational speed up to 10000 r/min. Experimental results qualitatively validated the theoretical model and confirmed the effectiveness of the new slipper design.     

斜盘泵滑靴副剧烈磨损过程的油膜润滑特性分析

斜盘泵滑靴副在发生剧烈磨损过程中,滑靴和斜盘将处于边界润滑状态,油膜润滑特性将发生较大的变化。为此,基于弹性流体动力润滑理论,结合滑靴副的实际工况,推导出滑靴副在剧烈磨损过程中的稳态等温线接触混合弹流润滑基本方程,并建立相应的数学模型。对模型进行数值求解,分析得出滑靴和斜盘接触区油膜压力、油膜厚度与泵转速和外载荷的关系。为斜盘泵滑靴磨损故障程度的影响因素分析及液压泵健康状态评估方法的研究奠定理论基础。     

Tribological study on hydrostatic slipper bearing with annular orifice damper for water hydraulic axial piston motor

Hydrostatic slipper bearing is an effective way to maintain a fluid film between slipper pad and swash plate that slide against each other, and thereby mitigate direct surface-to-surface contact in water hydraulic axial piston motor (WHAPM). The hydrostatic slipper bearing with an annular orifice damper is proposed, and the reaction force of the bearing in WHAPM is investigated. The effects from the friction within the cylinder bore, the dynamics of the piston, and the centrifugal force of the piston–slipper assembly are examined. The characteristic equation of the hydrostatic slipper bearing with an annular orifice damper is formulated, where the effects of various geometric parameters (e.g. damping length, supporting length, and clearance between the piston and the cylinder bore) are reflected. The relevant criterion for designing the hydrostatic slipper bearing can then be established. Results of the theoretical analyses indicate that (a) the friction coefficient, the swash plate angle, and the inertia and centrifugal loads (generated under a high motor rotating speed) would have significant influences on the reaction force; (b) an appropriate swash plate angle can help eliminate the fluctuation of the reaction force; (c) the load-carrying capacity of the hydrostatic slipper bearing is more sensitive to the damping length than to the supporting length of the piston; (d) a short damping length can help enhance the load-carrying capacity; (e) a small clearance between the piston and the cylinder bore would help improve the adaptive ability to the varying load for the hydrostatic slipper bearing, when clearance between the slipper pad and the swash plate ranges from 5 to 20 μm. Experimental studies of the slipper pads sliding against the swash plates are conducted at a custom-manufactured test apparatus, given different material combinations and design methods. The experimental results indicate that the hydrostatic slipper bearing with an annular orifice damper would decrease the possibility of the severe wear between the slipper pad and the swash plate in comparison with the hydrostatic clamping ratio bearing in the WHAPM, and the CRA laser cladding (compared to the ZrO₂·MgO-plasma-sprayed coating and the stainless steel 2Cr13) is a promising candidate as the tribo-material when sliding against composite materials in water lubrication system. The hydrostatic slipper bearing with an annular orifice damper has been successfully applied to a WHAPM developed at the Huazhong University Science and Technology. The result demonstrates that the developed bearing has a satisfactory tribolgical performance, and can be extended to the manufacture of water hydraulic axial piston pumps.     

Experimental Research on the Dynamic Lubricating Performance of Slipper/Swash Plate Interface in Axial Piston Pumps

The interface between the slipper/swash plate is one of the most important frication pairs in axial piston pumps. The test of this interface in a real pump is very challenging. In this paper, a novel pump prototype is designed and a test rig is set up to study the dynamic lubricating performance of the slipper/swash-plate interface in axial piston machines. Such an experimental setup can simulate the operating condition of a real axial piston pump without changing the relative motion relationship of the interfaces. Considering the lubricant oil film thickness as the main measurement parameter, the attitude of the slipper under the conditions of different load pressure, rotation speed and charge pressure are studied experimentally. After the test, the wear state of the swash plate is observed. According to the friction trace on the surface of the swash plate, the prediction for the attitude of the slipper and the zone easy to wear are verified.     

Optimal contact design and allowable limit on spindle assembly of aluminum hot rolling process

Aluminum sheet ingots go through the hot rolling process to be converted into coils with a gauge suitable for the cold rolling process or plates. The top spindle, end coupling and slipper metal are main components of the hot roll process and used for transmission of rotational power with heavy-duty load. The top spindle connected to the motor and end coupling connected to the roller are combined with the slipper metal which acts as a bearing and joint. The contact surface between end coupling and slipper metal is subjected to stress concentration, and life cycles of slipper metal is reduced. This study aims to minimize the mechanical problems which might happen in the production process. The load condition for hot rolling processes is derived under load condition that is conducted for a hot rolling process under slipper metal combination types and operation situations. A structural analysis is performed by applying mechanical characteristics, combination type, and rotational boundary condition of top spindle, end coupling and slipper metal. Optimal design is performed for contact surface between end coupling and slipper metal. Interference analysis is studied to reduce the stress concentrations. Kinematics simulation is performed by applying the various combination type and dynamic boundary condition of the mill spindle assembly. The interference does not occur on the top spindle and slipper metal, so actual driving of the hot mill spindle assembly can operate in the normal operation condition.     

Residual stress field of ballised holes

Ballising, involving pushing a slightly over-sized ball made of hard material through a hole, is a kind of cold working process. Applying ballising process to fastener holes produces compressive residual stress on the edge of the holes, and therefore increases the fatigue life of the components or structures. Quantification of the residual stress field is critical to define and precede the ballising process. In this article, the ballised holes are modeled as cold-expanded holes. Elastic-perfectly plastic theory is employed to analyze the holes with cold expansion process. For theoretical simplification, an axially symmetrical thin plate with a cold expanded hole is assumed. The elasticplastic boundaries and residual stress distribution surrounding the cold expanded hole are derived. With the analysis, the residual stress field can be obtained together with actual cold expansion process in which only the diameters of hole before and after cold expansion need to be measured. As it is a non-destructive method, it provides a convenient way to estimate the elastic-plastic boundaries and residual stresses of cold worked holes. The approach is later extended to the case involving two cold-worked holes. A ballised hole is looked upon as a cold expanded hole and therefore is investigated by the approach. Specimens ballised with different interference levels are investigated. The effects of interference levels and specimen size on residual stresses are studied. The overall residual stresses of plates with two ballised holes are obtained by superposing the residual stresses induced on a single ballised hole. The effects of distance between the centers of the two holes with different interference levels on the residual stress field are revealed.     

基于形态差值算子和特征能量比的液压泵故障分离方法

针对液压泵滑靴和斜盘磨损复合故障信号的分离问题,提出了一种基于形态差值算子与特征能量比相结合的方法。首先,将若干种不同长度的结构元素和复合故障信号的形态特征进行匹配,利用形态差值算子提取出若干个信号;其次,分别对上述信号计算两种故障的特征能量比;最后,找出两种故障的最大特征能量比,他们所对应的即为最优匹配结构元素长度,且基于该两种长度的形态差值算子所提取出的两个信号分别为最优分离出的滑靴和斜盘磨损故障信号。通过对实测液压泵复合故障信号的实验验证,表明所提方法能够根据信号形态特征的多样性有效地实现对复合故障信号的最优分离,且比RobustICA方法有效和优越。     

Lubrication characteristics analysis of slipper bearing in axial piston pump considering thermal effect

In this study, the lubrication characteristics of a slipper bearing for axial piston pump considering oil thermal effect have been investigated. A mathematical model is developed to predict the film thickness and temperature on the slipper/swash plate interface under different operating conditions. Based on the mathematical model, a parametric study is conducted to evaluate the slipper lubrication performance. It is found that the slipper is characterised by an unstable behaviour and the behaviour is enhanced by lower pressure and higher rotational speed. As the film temperature increases rapidly due to high shaft speed and piston chamber pressure, the overall result is a rather low decline in the film thickness. The leakage flow rate increases with increasing speed or oil film thickness. The structure parameter can be optimised to obtain satisfactory slipper performance. Copyright © 2015 John Wiley & Sons, Ltd.     

Thermoelastic stress analysis of oblique holes in flat plates

The stresses in the region of an oblique hole in a flat plate are analysed using the thermoelastic stress analysis technique. Particular attention is given to the obliquity of the hole and to the line of action of the applied load in relation to the hole axes. The effects of varying plate thickness are also studied. The data from around the rim and along the internal axis of the hole are presented as a series of stress concentration factors. The results are compared to those from previous studies and discussed in detail. These confirm the findings of the previous work in that increases in hole obliquity increase the stress at the hole, the maximum principal stress is obtained when the load is applied normal to the major axis of the surface ellipse and that as the thickness of plate increases the stresses on the surface of the plate decrease. Issues such as differences in the material’s Poisson’s ratio value are also discussed. The effect of any non-adiabatic behaviour on the thermoelastic output is described.