The structural feature of the point-line meshing gear pair is that the pinion is a modified involute short gear. The tooth surface of the big gear is divided into two parts, the upper part is the involute convex tooth profile, and the lower part is the transition curve concave tooth profile. During the meshing transmission process of the gear, there are both linear meshing of the contact line and point contact of the convex-concave tooth profile meshing, because the majority of the point-line meshing gear tooth profile is involute, Therefore, many geometric dimension calculation methods of point-line meshing gear are the same as that of ordinary involute gear, but due to its own characteristics, the design and selection of geometric parameters of point-line meshing gear is much more complex than that of involute gear.
For the design of geometric parameters of point-line meshing gear, domestic scholars and technicians have carried out systematic research. Chen Zooming and others introduced the basic theory of point-line meshing gear transmission, deduced the tooth profile equation of point-line meshing gear, expounded its meshing theory, defined the selection of point-line meshing gear parameters and the calculation method of geometric dimensions, which has a guiding role in the design and application of this type of gear. Luo Qihan et al. studied the closed diagram of the parameter selection of the point-line meshing gear. On the basis of the closed diagram of the involute gear parameters and in view of the characteristics of the point-line meshing gear, the closed curve of the parameter selection of the point-line meshing gear was developed, the significance of the curve of the closed diagram was described, and the influence of the parameters in the closed diagram on the gear performance was given. According to different design requirements, different gear parameters could be selected in the closed diagram, The research results are of great significance for the correct selection of the parameters of the point-line meshing gear.
In the design process of point-line meshing gear, the selection of helix angle has an important impact on its meshing performance and bearing capacity, and is one of the key design parameters of this type of gear. Huang Hai and others have conducted research on the selection of helix angle of point-line meshing gear, and pointed out that the selection of helix angle should be considered together with the machining machine tool, which can reduce the helix deviation, improve the meshing contact accuracy of tooth surface, and improve the contact strength of tooth surface. The selection of the modification coefficient of the point-line meshing gear is related to the success or failure of the design of this type of gear. Therefore, the selection of the modification coefficient is crucial to the geometric design of this type of gear. Ding Jun and others have studied the selection of the modification coefficient of the point-line meshing gear, and obtained the point-line meshing equation without backlash and the calculation method of the minimum modification coefficient, which is similar to the involute cylindrical gear. In order to avoid the undercutting phenomenon of gear processing, The minimum modification coefficient of the point-line meshing gear shall be calculated. At the same time, it is pointed out that the modification coefficient and helix angle of the big gear of the point-line meshing gear pair can only be accurately determined in the closed drawing of the point-line meshing gear parameters. This civilization determines the selection method of the modification coefficient of the point-line meshing gear, which has certain significance for its geometric parameter design.
In summary, the key design parameters (tooth number, modulus, modification coefficient, helix angle) of the point-line meshing gear have been thoroughly studied, and the research results can basically meet the design requirements of the point-line meshing gear transmission. However, the optimization of the design parameters of the point-line meshing gear needs further research, and the research on the influence of the key design parameters on the dynamic characteristics of the point-line meshing gear transmission system has not been involved, This also leads to the lack of in-depth research on the optimization of geometric parameters of the point-line mesh transmission system. It is necessary to further strengthen the theoretical and experimental research in this area, which is of great significance for the expansion of the application range of this type of gear.