The high-water-based directional valve serves as a key control element for actuating hydraulic supports in mining operations. However, conventional valve designs are increasingly inadequate in meeting the demands for high precision and digital control in modern support systems. To address this gap, the development of digital high-water-based proportional valves has become essential. Despite their potential, existing designs often suffer from excessive power consumption and structural complexity, limiting their practical application. In response, a digital high-water-based proportional valve suitable for high-flow conditions is proposed. This valve utilizes a hydraulic bridge circuit composed of high-speed switching valves for pilot control, effectively reducing the average power consumption during operation. Additionally, the hydraulic bridge directly controls the spool pressure to achieve proportional movement, minimizing intermediate stages between input and output and streamlining the overall structural design. Based on the completed main valve structure and control strategy, finite element simulations and system simulations of the proportional valve are conducted, verifying the valve’s functional feasibility. To simplify the experimental tuning process, a parameter self-tuning algorithm employing simulated annealing methodology is developed. Finally, prototype manufacturing and experimental validation of the proportional valve are performed. Under a maximum flow rate of 400 L/min, the valve achieves a response time of 150 ms and a hysteresis of 9.64
The magnetic levitation planar motor utilizes electromagnetic force directly to achieve a six-degree-of-freedom motion. The magnitude and fluctuations of the electromagnetic force directly determine system’s acceleration and motion accuracy. This paper comprehensively improves the performance of magnetic levitation planar motor through structure optimization and controller design. A novel magnet array is adopted to enhance acceleration while establishing a precise analytical model for harmonic electromagnetic forces and analyzing the loop gain fluctuations. The optimized structure achieves an acceleration increase of over 58
Focusing on the need for stable and reliable face gear transmissions, this study develops a high-order topology modification strategy to precisely control meshing behavior. Guided by contact path optimization, four modification functions including fourth-order, fourth-order segmented, second-order, and double-crowned are established along the contact path and instantaneous contact line. Comprehensive tooth contact analysis (TCA) and loaded TCA simulations reveal that the method effectively controls the contact path and shapes the transmission error curve. The fourth-order segmented modification proves particularly robust, significantly improving contact distribution and eliminating edge contact. Consequently, this approach effectively increases transmission stability and contact pattern percentage while reducing deviation. This research provides a practical framework for designing high-performance face gear pairs, especially for critical applications such as helicopter transmissions.
Bone tissue is more accurately removed by micro-grinding, which is more conducive to postoperative recovery and healing. However, the anisotropy of the bone material is not taken into account in current research on bone tissue micro-grinding, and experiments to optimize the parameters of the bone grinding process are lacking, leaving a gap in reference for the selection of parameters in clinical surgery. Based on this, the bone micro-grinding force is first analyzed by considering the anisotropy of bone tissue, and a single-factor experiment investigates the effects of machining parameters on the micro-grinding process under the three directions of vertical, cross, and parallel to the feed direction of the grinding head and the bone unit. Orthogonal experiments are then used for optimization to evaluate the effect of each machining parameter on the machining quality based on the magnitude of micro-grinding force in the x- and y-directions and the surface morphology of the machined bone tissue. The results show that the minimum Fx and Fy and the best surface quality are obtained at a feed rate of 100 mm/min, a grinding head rotational speed of 16000 r/min, and a grinding depth of 15 µm. Finally, the results of the orthogonal experiments are analyzed by signal-to-noise ratio and analysis of variance, and the results show that the grinding depth factor has the greatest effect on Fx and Fy in the vertical direction, the grinding head rotational speed factor has the greatest effect on Fx and Fy in the cross direction, the grinding depth in the parallel direction has the greatest effect on Fx, and the grinding head rotational speed has the greatest effect on Fy. The aim of this study is to provide theoretical guidance and technical support to improve the processing quality of biological bone micro-grinding.
Minimum quantity lubrication (MQL) machining has gained widespread attention in both academic and industrial research fields as a beneficial technology for improving machining performance and sustainability, due to its low cost and environmental protection. Nevertheless, there is still room for improvement in MQL, such as the lack of research and analysis on the development history of MQL, key authors, and research hotspots. This may be one of the reasons limiting the development of MQL. Based on this, this paper proposes a new bibliometric analysis of MQL research, with the aim of describing current research trends and visualizing the development history and emerging trends of MQL to support researchers in conducting in-depth studies. First, a bibliometric analysis was conducted on 1842 publications related to MQL in the Web of Science (WoS) Core Collection database from 2008 to 2023. Secondly, bibliometric analysis software such as VOSviewer and bibliometrix were used to visualize the annual growth of publications, distribution of research fields, regional distribution, distribution of research institutions, author distribution, highly cited articles, and keywords. The results show that from 19 publications annually in 2008 to 292 publications annually in 2023, there has been a 15-fold increase, with India (550 publications) being the country with the most publications and China (19420 citations) having the highest number of citations. Furthermore, an analysis was conducted on the research hotspot directions represented by keyword classification, summarizing the current research achievements. This paper reveals the development trend, global cooperation pattern, basic knowledge, research hotspots, and emerging frontiers of MQL.
