Researches On Spatial Conjugate Curve Bevel Gears

In gear transmissions, motion and power are transmitted by tooth surfaces directly. So, the researches on tooth surface geometry are always hot in the gearing field. In re-cent years, new meshing theory, spatial conjugate curve meshing theory(SCCM), has been proposed based on the spatial conjugate surface meshing theory. Because in SCCM theory, curves are the basic elements of designing gear tooth surfaces, the tooth surface can be designed more flexibly. Based on this theory, this paper try to use curves as the geometric elements of meshing to investigate novel meshing theory of gearing. In our opinion, this research contribute to improving the performance of gears, and it also has great theoretical significance.In this thesis, the main contents are as below:(1) The basic principles of conjugated curve meshing are discussed in detail. Based on the basic theory of conjugate curve meshing, the general characteristics of spatial conjugate curves are investigated. The existence of gear tooth surface and uniqueness of spatial conjugate curves are argued. These characteristics of spatial conjugate curves are the foundations of applying these curves in the field of gearing.(2) The novel design method of gear tooth surfaces based on spatial conjugate curves is proposed. In this method, the tooth surface are generated through a series of continuous vibrational curves in the normal section of spatial conjugate curves. The shapes of the curves in the normal section of spatial conjugate curves can be arbitrary. As for these tooth surfaces, the contact paths are the spatial conjugate curves.(3) According to spatial conjugate curve meshing theory, the general model of continuous pure-rolling contact bevel gears are proposed. For these bevel gears, the spatial conjugate curves are on the pitch cone. In other words, the contact point are always on the pitch cone. Besides, the general characteristics of continuous pure-rolling contact bevel gears are studied. The general equations of spatial conjugate curves of continuous pure-rolling contact bevel gears are derived. The meshing correctly constraints are also argued. As a result, the general simplified judgment inequalities are derived.(4) Based on the general model of continuous pure-rolling contact bevel gears, the cylindro-conical equal-helical-angle spiral curve gears, cylindro-conical equal-distance spiral curves and prolate epicycloid gears, which are all of continuous pure-rolling contact, are proposed. Besides, the solid models of these gears are built. As for these solid models, finite element analysis is introduced to observe the contact paths and the stress distribution conditions of these gears under loads.(5) Based on spatial conjugate curve meshing theory, the design method of general spiral bevel gears of local bearing contact are proposed. Through this method, the solid models of cylindro-conical equal-helical-angle spiral curve gears are built. Besides, finite element analysis is introduced to observe the contact paths and the stress distribution conditions of these gears under loads. As for the model of general spiral bevel gears of local bearing contact, because the contact points are not constrained on the pitch cone and the contact paths can be chosen arbitrarily, the tooth surface can be designed more flexibly.(6) On the base of researches about continuous pure-rolling contact bevel gears and general spiral bevel gears of local bearing contact, the basic theory of spatial conjugate curve bevel gears of multi-point contact is proposed. The design principle, calculation criterion, generation method and so on are investigated. Based on the model of multi-point contact bevel gears, the solid models of 2-point contact bevel gears and 5-point contact bevel gears are built. Based on these solid models, finite element analysis is introduced to observe the stress distribution conditions of these gears of these gears under loads.(7) The prototype spatial conjugate gears are manufactured. Besides, the experiment tables of SEW gearbox and the gearboxes which employ novel spatial conjugate gears are set up. Through these tables, the basic transmission characteristics of SEW gearbox and the gearboxes which employ novel spatial conjugate gears are evaluated.