Traditional involute gear pumps find it difficult to meet the requirements of miniaturization and high performance because of the undercutting, trapped oil, and flow pulsation. To eliminate the phenomenon of trapped oil and reduce flow pulsation in the miniature gear pump, a novel miniature double-circular-arc line gear (MDLG) and its manufacturing method are proposed. Firstly, based on the spatial curve meshing theory, the tooth flank equation of the MDLG is established, and the design method of the MDLG hob is presented. Then, the instantaneous flow rate of the MDLG pump is analyzed by using the swept-area method. Subsequently, a hobbing machining model is built on the VERICUT virtual simulation platform, and machining experiments are conducted on a hobbing machine. Furthermore, the manufactured MDLGs are inspected at a gear measuring center. Finally, an MDLG pump prototype is developed and machined. The measurement results show that the total cumulative pitch deviations of the machined MDLGs are controlled within 32.1 μm, achieving the ISO 8 accuracy grade. The theoretical calculations and experimental results in this article verify the feasibility of the design and processing of MDLG pumps, providing a reference for the development of high-performance miniature gear pumps.

To mitigate the deterioration of the tribological performance of end-face friction pairs under low-speed conditions, this study investigated a water-lubricated CF/PEEK–316L stainless steel end-face friction pair. Surface micro-textures with different depth-to-diameter ratios and texture area ratios were fabricated on the 316L stainless steel surface to evaluate the effects of texture parameters and sliding speed on tribological performance. The results showed that appropriately designed micro-textures effectively reduced the coefficient of friction and improved the wear characteristics of the friction pair. Among the tested conditions, the CF/PEEK–316L stainless-steel tribo-pair with a 316L counterface textured at ε = 0.05 and s = 10% exhibited the lowest average friction coefficient. At 200 rpm, this textured tribo-pair exhibited an average friction coefficient approximately 34.8% lower than that of the untextured tribo-pair. Furthermore, laser micro-textures suppressed interfacial material transfer and mitigated adhesive wear and three-body abrasive wear by capturing wear debris. Gear-pump prototype tests further showed that the textured surface improved flow-delivery and volumetric-efficiency performance, while promoting more uniform end-face wear morphology, indicating its potential application in practical gear-pump components. The findings provide guidance for surface-texture design and tribological-performance optimization of polymer/metal end-face friction pairs.

To address the limited design flexibility in meshing equations, complex modeling processes, and a lack of systematic research on bidirectional transmission in traditional parallel-axis line gears, this paper proposes a rapid design method for bidirectional transmission parallel-axis external line gears (BTPELG). Firstly, a multi-coordinate system is established, and homogeneous transformation matrices are derived. Secondly, the meshing equation is extended with an angular parameter to obtain a widely applicable conjugate condition. Then, two pairs of conjugate contact curves and center guide curves are constructed, and the offset vector for a circular-arc tooth profile is derived. Subsequently, taking the equidistant cylindrical helix as the driving contact curve, a 3D solid model is built via the sweeping method. Finally, kinematic simulations and experiments on 3D-printed prototypes verify the transmission ratios under forward and reverse conditions. Results show stable bidirectional transmission with average ratios matching theory and small fluctuations, confirming the method’s feasibility and providing a reference for rapid design and engineering applications.