Research On Meshing Characteristics Of Spur Curve-Face Gear Compound Transmission

As the most important form of power and motion transmission in modern mechanical transmission,gear transmission mechanism has a series of advantages,such as high precision,high load-bearing,high efficiency and so on.With the rapid development of industry and daily life,the application limitations of gear pairs with constant transmission ratio are becoming more and more obvious.Therefore,the researchers put forward the time-varying transmission ratio gear mechanism of the curve-face gear pair,and further combined with the cylindrical gear,the curve-face gear compound transmission mechanism and the non-circular gear moving-shaft transmission mechanism were put forward.The curve-face gear compound transmission is composed of the cylindrical gear and the curve-face gear,which can realize transmitting compound motion and power with the variable transmission ratio between the two intersecting shafts.The non-circular gear moving-shaft transmission mechanism is composed of cylindrical gear and non-circular gear with the characteristics of variable center distance plane transmission.Curve-face gear compound transmission and non-circular gear moving-shaft transmission enrich the transmission form of gear pair,simplify the transmission chain of compound transmission mechanism and improve the mesh efficiency of compound transmission,and comply with the modern design concept of lightweight.It is of great theoretical significance to study the characteristics of time-varying meshing and spatial finite helical motion of curve-face gear composite transmission,which has important potential applications in the agricultural machinery,industrial robot and aerospace fields.According to the driving gear and its motion form,the spur curve-face gear compound transmission is divided into three transmission forms,which are respectively applied to the tooth surface generating of the curve-face gear,the deceleration motion and acceleration motion of the curve-face gear compound transmission.Since the gear pair is mainly used in the reduction mechanism,the previous two transmission modes are the research objects.The main research contents of this paper are as follows:(1)The compound transmission principle and tooth surface generation model of curve-face gear were constructed.On the one hand,based on the principle of space gear meshing,the principle of curve-face gear compound transmission was discussed,and taking the basic parameters and pitch curve function of curve-face gear compound transmission were designed according to the expected transmission ratio.The tooth surface generation methods of curve-face gear were proposed,and the laws of the two tooth surfaces in one meshing cycle were compared and analyzed.(2)The generalized reference coordinate system of curve-face compound transmission was established.From the known basic parameters and tooth surface geometry of cylindrical gear and curve-face gear,the basic motion relationship of curveface gear compound transmission was deduced,and the influence of two tooth surface generation methods on the basic motion relationship of compound transmission is compared and analyzed.Combined with the screw theory,the generalized motion geometry of curve-face gear compound transmission was established,and the auxiliary geometric elements that provide important reference for the design and manufacture of gear pair were discussed,including instantaneous screw axis,axodes,transverse surfaces,meshing axial surface and reference pitch surface.(3)The point contact trajectory and the induced normal curvature of the contact tooth surface of the curve-face compound transmission were deduced.The continuous contact relation equation of conjugate tooth surface on curve-face gear compound transmission was established,and the contact trajectory on the tooth surface of curve-face gear in the process of conjugate meshing was obtained,and the difference between the two tooth surfaces to generate the contact trajectory of curve-face gear compound transmission was compared and analyzed.The principal curvature and principal direction of the tooth surface of cylindrical gear and curve-face gear were deduced,further more,the induced normal curvature at the contact position of the tooth surface was obtained,and the interference problem on the effective tooth surface of curve-face gear was checked.(4)The time-varying motion characteristics of curve-face gear compound transmission were discussed.According to spatial mechanism,the degrees of freedom of curve-face gear compound transmission mechanism were calculated.Based on the screw theory,the reciprocity between the instantaneous screw of compound transmission and the normal screw of contact tooth surface were verified.The spiral angle determined by the curve-face gear surface and the reference pitch surface was calculated,and the transverse contact ratio and axial contact ratio of the compound transmission are further obtained.The relative displacement between cylindrical gear and curve-face gear was quantified,and the sliding velocity and rolling velocity between two contact tooth surfaces were solved.Based on this,the meshing efficiency of curve-face gear compound transmission considering only sliding friction was obtained.(5)The correctness of construction method of the conjugate tooth profile on curveface gear and the analysis theory of time-varying motion characteristics and time-varying contact characteristics of compound transmission were verified.The theoretical mathematical models of curve-face gear were established.The gear parts were obtained by milling in the five-axis NC machining center,and the tooth surface coordinates of the machined gear were obtained by using the gear measuring center.Further more,the relative error of the gear tooth surface was detected and evaluated,and the correctness of construction method of the conjugate tooth profile on curve-face gear was verified.The experimental platform of curve-face gear compound transmission for the motion and rolling detection was built,which can verify the correctness of the basic motion law and point contact trajectory theory of curve-face gear compound transmission.(6)The design for the potential application of curve-face gear compound transmission was explored.The curve-face gear compound transmission focusing mechanism applied to space remote sensing camera was designed.The minimum displacement of the focusing mechanism was obtained.The motion simulation of the transmission of the focusing mechanism was analyzed to verify the feasibility of this mechanisms.