Spiral groove journal bearings (SGJBs) are widely used in high-performance rotating machinery due to their excellent hydrodynamic performance and wear resistance. However, the strong nonlinear interactions among key geometric parameters made considerable challenges to performance optimization. This study introduces an integrated approach utilizing Response Surface Methodology (RSM) coupled with Finite Element Method (FEM) to systematically investigate the influences of groove width, length, depth, spiral angle, and groove numbers on bearing load-carrying capacity (LCC) and lubricant leakage. Analysis of variance (ANOVA) results identified significant interactions among parameters, with groove width, length, and depth strongly influence LCC, while groove length, depth, and number primarily govern leakage, with spiral angle having a comparatively minor effect. A multi-objective optimization framework was developed, achieving a 6% increase in LCC and a 37.17% reduction in leakage. The results provide valuable insights into the practical design to improve lubrication efficiency in high-performance engineering applications.

The synergistic mechanism between crack network evolution and energy release in deep coal mine roof sandstone is a critical factor triggering rock burst disasters. This study combined acoustic emission (AE) monitoring with digital image correlation (DIC) technology to conduct uniaxial compression tests on double-flawed sandstone, systematically analyzing how rock bridge dip angle regulates crack propagation paths and damage evolution. A mechanical criterion for mixed-mode crack propagation was developed based on stress intensity factor theory, optimizing traditional crack classification standards. Results show that as rock bridge dip angle increases, crack penetration length shortens, energy dissipation channels decrease, and AE energy accumulation intensifies. Under low rock bridge angles, tensile stress drives crack initiation with predominantly mixed I/II propagation modes, whereas at high angles, cracks initiate via shear slip, dominated by mixed III modes. The regulatory mechanism of rock bridge dip angle on crack network configuration and energy release paths is revealed, providing a theoretical basis for achieving directional energy release in roof rock through active optimization of rock bridge angles.

In deep mining engineering, the geological-mining interaction (repeated disturbance from mining activities leading to stress field reconstruction) results in significant roof instability and failure. This study uses combined Acoustic Emission (AE) and Digital Image Correlation (DIC) techniques to monitor and conduct cyclic loading tests on double-fractured sandstone specimens with different rock bridge angles. The study systematically analyzes the impact of rock bridge angle on the dynamic response and damage-fracture mechanisms of sandstone under cyclic loading. The results show that cyclic loading hardens sandstone, but the weakening effect of initial defects is more dominant. The 60 degrees rock bridge angle specimen exhibits the lowest Ded, with most of the energy stored elastically. Furthermore, the evolution of AE parameters characterizes the progressive damage under cyclic loading. For the 60 degrees sample, the rapid crack propagation results in AE energy concentrating at the peak release stage, consistent with the macroscopic energy release characteristics. The RA-AF plot indicates that microscopic damage is primarily driven by the propagation of tensile cracks, with their proportion first increasing and then decreasing as the rock bridge angle changes. Based on DIC displacement fields, two types of single-mode cracks and six types of mixed-mode cracks were identified. The evolution of macroscopic crack types is associated with the trend of tensile cracks in the RA-AF plot, with the proportion of tensile cracks being highest in the 60 degrees rock bridge specimen. Finally, through analyzing the RA-AF values and the surface strain field characteristics captured via DIC at distinct loading stages, the disaster-causing mechanisms induced by varied rock bridge angles under cyclic loading were elucidated. Based on these findings, a dual-control theory of rock damage evolution under cyclic loading, comprising an energy dissipation-driven mechanism (the competition between tensile and shear energy efficiencies) and a spatial configuration-regulated mechanism (rock bridge angles governing crack propagation directions), was proposed. This theoretical framework provides a robust foundation and quantitative criteria for evaluating surrounding rock stability and preemptively mitigating hazards under high-intensity disturbance conditions in practical engineering contexts.

Aiming at the problem that the flow rate of the two cavities of the differential cylinder does not match and it is not easy to achieve pump control, the team proposed the asymmetrical distribution principle of the axial piston pump with three ports, which can compensate for the flow difference between the two cavities of the differential cylinder without auxiliary components. Based on this principle, a new type of valve plate structure is designed by using the residual compression method. The pump performance is analyzed by PumpLinx simulation and experiment; the influence of the transition zone structure on the pressure and flow characteristics of the piston pump is researched. The basic characteristics of the pump such as pressure, flow, and noise under different working conditions were tested on the experimental platform, and the rationality of the new structure was verified. The new flow distribution scheme can not only compensate the flow difference of the differential cylinder, but also output two different pressures, which realizes the ideal effect of the hydraulic pump directly controlling the differential cylinder. The research work lays a theoretical foundation for the realization of the pump-controlled volumetric direct drive system.

Servo press is a forming equipment that uses a servo motor to drive a crank slider for stamping and deep drawing process. The servo drive can adjust the motor speed in real time and dynamically, which provides an important support for the dynamic adjustment of the crank slider movement. To realize the smooth reciprocating movement of the large-mass and high-inertia slider, it is necessary to develop a motor speed adjustment algorithm to achieve a good match between the movement load of the slider and the torque that the motor can bear, to ensure the operation safety of the whole machine. S-curve algorithms are often used for the planning of slider movement curves, which is easy to produce flexible impact on the motor. Therefore, to improve this situation, an improved S-curve algorithm is proposed based on the above common methods, which realizes the motion control method of smooth speed change. In this paper, a movement planning algorithm for servo press slider with improved S-curve is proposed based on the 7-phase S-curve acceleration algorithm. Firstly, the kinematic calculation of the crank slider mechanism is carried out. Secondly, 4 control points are set up to divide the slider movement curve of the typical drawing process, including the idle feed stage, deep drawing stage, idle return stage, and loading/unloading stage. Furthermore, the uniform acceleration stage and the uniform deceleration stage are removed, and the acceleration cusp was smoothed, and the improved S-curve algorithm was obtained. Finally, the large-scale crank slider servo press and its deep drawing parameters in a literature are taken as an example to solve the slider movement curves by using the improved S-curve. The results show that the improved S-curve algorithm can be used for servo press slide motion profile planning, which can realize efficient deep drawing process mode.

This paper proposes a new control scheme that is composed by the sliding mode control(SMC) with three-dimensional ceiling control to reduce the multi-dimensional vibration of the vehicle’s seat. The seat suspension system is made of a kind of 3-RPS parallel mechanism, in which each limb is mainly composed by the spherical pair, spring, piston rod, damping fluid and rotary pair. Based on the single-open-chain theory, Position and Orientation Characteristics (POC) set of a 3-RPS seat mechanism was analyzed to verify its movement law. Three-dimensional seat system mathematical model was established, and the SMC and ceiling control were combined to obtain the required force. The ceiling control belongs to an ideal control method, it could provide the reference for the SMC. The comparisons between the SMC and passive seat suspension system were done when the vehicles were walking or working on E, F and G-roads. The results show that the transient amplitudes of seat acceleration outputs were reduced with the proposed control scheme. The research in this work can be extended and applied for other vehicles and improve their performance.

Pump-controlled single-rod hydraulic cylinders are energy-saving and efficient, which is the development direction of hydraulic systems in the future. However, the flow imbalance caused by the unequal effective areas of the two chambers of single-rod hydraulic cylinders has always restricted the development and application of pump-controlled single-rod hydraulic cylinders. The flow rate of the inlet and outlet ports of the ordinary axial piston pump is equal and the flow rate of the large and small chambers of the single rod hydraulic cylinder does not match. In order to solve this problem, the ordinary axial piston pump is improved into an asymmetric axial piston pump, on this basis, the flow distribution mechanism of the asymmetric axial piston pump is explored, and the design theory of the asymmetric axial piston pump is improved. Theoretical analysis of the relationship between the angle of the distribution window of the asymmetrical axial piston pump and the area ratio of the single-rod hydraulic cylinder is carried out, and its mathematical model is derived. Design of valve plates for asymmetrical axial piston pumps to match single rod hydraulic cylinders with different area ratios. The physical model of the asymmetrical axial piston pump and the asymmetrical axial piston pump controlled single-rod hydraulic cylinder system was established in the computer simulation software AMESim. The simulation analysis of the inlet and outlet flow of the asymmetric axial piston pump under different working conditions and the matching of the asymmetric axial piston pump and the single-rod hydraulic cylinder with different area ratios. The simulation results show that the use of an asymmetrical axial piston pump can compensate the flow imbalance caused by the unequal effective areas of the two chambers of the single-rod hydraulic cylinder, so that the flow of the asymmetrical axial piston pump and the single-rod hydraulic cylinder can completely match.

Brittleness is a critical property in gas-bearing rock excavation and reservoir fracturing. This paper analyzes the three types of brittleness indices in detail, proposes new indices, and conducts relevant conventional triaxial tests for analysis. A stress–strain curve-based brittleness index would be appropriate for the evaluation of brittleness if the parameters represented unique and certain stress–strain curves. Therefore, a new brittleness index is proposed. It consists of two components: the stress variation index and the strain variation index, which reflects the strain ratio of the stress drop and the relationship between elastic and post-peak strains, combining the stress variation and strain variation in the pre- and post-peak phases. Triaxial compression tests of sandstone under different confining pressures and gas pressures were conducted, and specific stress and strain parameters were collected. Based on the comparison and analysis of various brittleness indices, it is found that the newly proposed brittleness index can be a good measure of the brittle evolution of sandstones under different confining pressures and gas pressures, and it can provide a more accurate estimate of rock brittleness than the existing indices. The index is also used to further investigate the relationship between rock brittleness and confining and gas pressures. This has important implications for the assessment of rock brittleness in practical engineering.

There have been frequent occurrences of water–sand inrushes in underground mines due to irregular mining activities under thick loose gravel layers. The morphological development characteristics of the caving zone and the changes in the geological conditionsin the working face under a thick loose sedimentlayerof the Pingan Coal Mine have been studied. The empirical formula and numerical simulations are carried out to explore the effect of different thicknesses of the bedrock on the height of the caving zoneand mining thickness. The method of solving the water-sand inrush of the fully mechanized caving face by adjusting the mining thickness was proposed. The results indicate that there is a linear relationshipbetween the height of the caving zone and the mined thickness. The caving height ratio decreases with an increase in the mined thickness and the correlation can be described by a power function. The maximum allowable height of the caving zone and mined thickness are determined based on the thickness of the bedrockand the changed tendency of the caving height ratio. This provides a mean to control the stability of the sand layer on the roof of the working face by adjusting the mined thickness of coal. The method has been applied in the Pingan mine to prevent water-sand inrushes successfully.

针对三配流窗口非对称轴向柱塞泵在非死点过渡区配流转换产生较大的流量和压力冲击问题,提出一种采用额外油道将非死点过渡区高压油预泄至上死点过渡区的新型配流盘结构,不仅可降低流量脉动和压力冲击,而且过渡区高压油液得到再利用,提高液压泵能效.首先设计新型配流盘结构,理论分析了新型配流盘工作原理,并建立基于新型配流盘的非对称轴向柱塞泵仿真模型,分析油道半径和分布位置对轴向柱塞泵流量脉动的影响,研究不同负载情况下新型配流盘结构的有效性.结果表明:该方案能对非死点过渡区柱塞起到预降压作用,对上死点过渡区柱塞起到预升压作用;当油孔半径为0.65 mm,分布位置为8.和88.时,轴向柱塞泵性能最优.

针对目前轴向柱塞泵工作过程中柱塞腔压力信号难以测试的问题,提出了一种基于无线传感器的柱塞腔测试方法.通过在柱塞泵相关部件上打孔,将测试节点固定到柱塞泵缸体及轴端,使微型压力传感器直接与柱塞腔内部液压油接触以此来采集压力信号.节点集成压力采集、无线数据传输、无线供电等模块,实现了压力信号的高速准确采集.该设计方案理论上能够进行柱塞泵旋转缸体内部压力测试,为柱塞泵状态监测和压力特性研究提供了新的技术手段,经测试,节点具有较高的稳定性和准确性,能够满足柱塞泵压力信号测试要求.

An experimental and theoretical research was conducted in this work focused on seal behavior. An innovative mixed lubrication model considering the elastohydrodynamic (EHD) theory which introduces a deformation theory was employed. This paper presents a computational procedure for resulting a coupled solution of the fluid and the seal. The model gains insight into the effects of seal pressure, rod velocity and the compression ratio on the sealing characteristics in terms of the contact pressure, fluid pressure distribution as well as fluid transport in the sealing zone. The proposed approach accurately predicts the friction force corresponding to the experimental data and provides a theoretical basis for EHL modeling that captures the sealing characteristics.

变排量非对称轴向柱塞泵直接控制非对称液压缸闭式系统具有能效高、结构紧凑等优势.针对变排量三配流窗口轴向柱塞泵存在变量阻力矩脉动大、斜盘倾角振荡频率高等问题,提出在变排量机构中增加阻尼孔以提高变排量控制性能的方案,推导了变排量控制系统的传递函数;通过AMESim仿真模型分别研究了有无阻尼孔情况下的斜盘倾角振荡、变量缸活塞受力、斜盘变量阻力矩等.结果表明,在控制系统阀控缸中加入直径2 mm的阻尼孔,能有效降低斜盘倾角的振荡频率,减小系统脉动冲击.

针对锥形缸体轴向柱塞泵工作时,柱塞腔内油液体积急剧变化,腔内产生的压力脉动和压力冲击会造成柱塞泵振动以及噪声的问题,采用了AMESim建立锥形缸体柱塞泵模型的方法,研究了斜盘倾斜角度和油液的可压缩性及粘性对柱塞腔内压力的影响特性.首先,分析了A4VSO锥形缸体柱塞泵的工作原理和运动学关系,以及柱塞腔内压力的理论分析;其次,通过AMESim的二次开发对原有的柱形缸体模块进行了改进,在考虑泄漏的影响下,建立了锥形缸体轴向柱塞泵的仿真模型;最后,使用实验数据验证了仿真模型的可靠性.研究结果表明:随着斜盘倾角、油液体积弹性模量和动力粘度的增大,柱塞腔内压力增大,且油液体积弹性模量的脉动率由最初0.6％的涨幅降为0.34％.

为提高普通液压蓄能器的能量密度和检验四配流窗口液压泵样机在能量回收方面的性能,利用AMESim搭建液压飞轮蓄能器和四配流窗口轴向柱塞泵的物理仿真模型,并结合重物举升模型和液压挖掘机动臂升降的特性构建了相关的能量回收液压回路,求得变量泵排量与重物运动速度微分方程.通过重物静态升降工况的参数匹配,进一步分析了液压飞轮蓄能器的能量密度和能量回收效果.仿真结果表明:相同体积下的液压飞轮蓄能器和普通液压蓄能器相比,液压飞轮蓄能器在兼顾能量回收效率的同时提高了89.4％的储能密度;运用所求得的微分方程控制泵的斜盘倾角,减小了负载的抖动.

For medium plate leveler,the constant pressure control can improve the quality and precision of the plates,at the same time,the rack can be protected.A constant pressure control system is put forward for the screw-down system of the leveler,which converts the position control system to the pressure control system at a specific point.For the characteristics of nonlinearity,time-varying and disturbance of the hydraulic system of levelers,the control strategy of auto disturbance rejection with disturbance feedforward is adopted,which can reduce the influences of disturbance forces on the straightening force,improving the control precision of the straightening force and achieving constant pressure control.This control strategy is verified by the Matlab simulation and the hydraulic leveler prototype.The results indicate that the influences of disturbance force are brought down and the stability of the leveler hydraulic system is significantly improved.

The traditional valve-controlled hydraulic servo system has large throttling losses and undergoes serious heat problems when used in electro-hydraulic servo systems (EHSSs) for a rolling shear. In order to improve the energy efficiency of the EHSS for the rolling shear while also ensuring the position tracking accuracy, the separate metering electro-hydraulic servo system with varying supply pressure (VSP-SMEHSS) is proposed in this work. The inlet valve controls the position of a hydraulic cylinder, while the outlet valve controls the back pressure of the hydraulic cylinder. However, due to the disturbance caused by the varying supply pressure, the proportional–integral–derivative (PID) controller or active disturbance rejection controller (ADRC) cannot meet the requirements of accuracy. In order to solve this problem, based on a nonlinear disturbance observer (NDO) and a tracking differentiator (TD), a dynamic surface control (DSC) is proposed in this work. Firstly, the stability of the controller is validated using the Lyapunov method. Then, experiments are conducted to verify the proposed control strategy. As a result, the hydraulic cylinder can accurately track the reference displacement signal and effectively reduce the pressure drop at the valve’s orifice, due to which the hydraulic system achieves significant energy-savings. Compared with that of the EHSS, the energy consumption of the VSP-SMEHSS is reduced by 44.6%.

The hydraulic system of a bilateral rolling shear for a thick and wide plate is a nonlinear system. The sudden loading on the hydraulic cylinders caused by the collision between the steel plate and the upper blade is huge at the beginning. The system response may be unable to meet the requirements of actual production, thereby resulting in low cutting quality or failure to shear the steel plate. To solve these issues, we propose a preloaded hydraulic system in which some amount of pressure is preloaded in the rodless chamber before the hydraulic cylinders contact the load. Then, the pressure held in the rodless chamber of the hydraulic cylinder is immediately released as the load applied, compensating for the inadequacies in the response time of the system and providing a sufficiently large supplementary flow to the hydraulic cylinder. A cascade controller based on a disturbance observer is designed, which includes a position outer loop and a pressure inner loop. The new electrohydraulic servo system improves the shearing precision and power of the bilateral rolling shears and increases the load tolerance of the system, thereby improving the system stability.

提出了一种具有三个配流窗口的轴向柱塞泵,用来补偿单出杆液压缸两腔面积差引起的流量不平衡,同时减小了液压缸在换向时的压力冲击,使液压泵与液压缸的流量完全匹配,实现泵控单出杆液压缸系统.

The invention relates to the technical field of medical instruments, and discloses a mechanical arm of a surgical robot in the urology department. The mechanical arm comprises an inverted-U-shaped fixing plate and a rotary arm, the rotary arm is vertically located below the inverted-U-shaped fixing plate, the upper end of the rotary arm extends into the inverted-U-shaped plate, a through groove isformed in the upper end of the rotary arm, a first rotary shaft is transversely arranged inside the through groove, fixing holes are formed in the left side and the right side of the through groove respectively, the wall of the first rotary shaft and the rotary arm are fixedly sleeved through the fixing holes, the two ends of the first rotary shaft are rotatably connected with the opposite innerside walls of the inverted-U-shaped fixing plate respectively through first rolling bearings, a first gear is fixedly arranged at the part, located inside the through groove, of the wall of the firstrotary shaft, and a second rotary shaft is transversely arranged inside the inverted-U-shaped fixing plate and located above the first gear. The mechanical arm of the surgical robot in the urology department can realize multi-freedom-degree sensitive high-precision operation, and a long shaft and a tail end executing component are convenient to rapidly disassemble and assemble with a driving assembly.