Based on the space curve meshing theory, a novel noncircular line gear mechanism was advanced, namely, this paper presented a design method of the variable speed ratio noncircular line gear with coplanar axes. Firstly, the universal contact curve equations of the constant speed ratio and variable speed ratio line teeth were established. After the constraint equations of the rotating angle of the driving and driven variable speed ratio noncircular line gears were analyzed and established, the relationship between the rotating angle of the driven variable speed ratio noncircular line gear and the parameter t in the VSR area was assumed to be a piecewise fourth-order curve. Then, the contact curve equations of the variable speed ratio noncircular line gears were derived, and the entity models of variable speed ratio noncircular line gears were built. The prototypes of the parallel axis and intersecting axis variable speed ratio noncircular line gears were manufactured by Stereo Lithography Apparatus, and the speed ratios were measured on the kinematic test rig. The kinematic and finite element analysis results demonstrate that the relationship between the rotating angle of the driven variable speed ratio noncircular line gear and the parameter t conforms to the designed function and the noncircular line teeth smoothly achieve the preset VSR transmission. The proposed design method is helpful to design the variable speed ratio noncircular line gears with lower theoretical sliding rate and wider variation range of the speed ratio; consequently, the designed variable speed ratio noncircular line gears have better applicability in specific variable speed ratio applications.

The utilization rate of miniature gears has increased sharply with the widespread application of micro-pumps, electronic equipment, and measuring instruments, and therefore the design and processing of miniature gear has become a subject of intense research. Current research has predominantly focused on machining miniature parallel-axes gears, but well-established machining methods for miniature intersecting-axes gears are still lacking. This paper presented a nanosecond pulsed laser micro-milling technology for miniature intersecting-axes gear (MIAG). Firstly, the 3D models of driving MIAG and driven MIAG were established, and the machining schemes were proposed on the basis of the characteristics of the models. Then, the influences of processing parameters such as defocusing distance, pulse overlap, and scanning strategy on the output responses, including removal rate, surface roughness, and shape accuracy were analyzed. Afterward, some miniature structures, such as miniature grooves, cylinders and cones, were machined by combining these process parameters. Finally, the MIAGs were machined, and the accuracy evaluation and kinematics experiment were carried out. The diameter of driving MIAG was 1.21 mm, and the diameter of driven MIAG was 3.389 mm. The experimental results indicate that the proposed machining technology can process MIAG with relatively high precision and can also offer a valuable reference for the manufacturing of other miniature components.

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.