| Harmonic gear transmission is a transmission method that uses the controllable elastic deformation of flexible components to achieve a large transmission ratio.It is widely used in high-precision fields such as robotics,medical equipment and military weaponry.It has the advantages of high transmission efficiency,low noise,light weight and high precision,and has attracted much attention in the field of mechanical transmission.The contact area of the tooth profile directly determines the meshing performance of the harmonic gear drive.The S-shaped full-tooth profile meshing area formed by the gap adjustment is insufficient,and the modification will easily lead to a significant reduction in the effective meshing range.The conjugate tooth profile obtained by the envelope method has advantages in the meshing interval,but the solution process is complex and prone to no solutions.Based on the numerical envelope method and the S-shaped tooth profile design,a tooth profile design method with effective edge conjugate points is pr oposed in this paper,which can effectively increase the meshing area of the entire tooth profile,the main research contents are as follows:(1)The working principle of the harmonic gear transmission is introduced,and the structure design of the main parts of the flexspline,rigid spline and wave generator is completed.The planar geometric relationship model between the components is established,the rotation angle relationship betwe en the components is analyzed,and the motion trajectory equation of the original curve of the harmonic drive is established.(2)Based on the principle of rack and pinion trajectory curve mapping,an approximate convex tooth profile expression is established,and the transition method of the tooth root is studied.Considering the deflection of the tooth profile during the movement of the flexspline tooth,the approximate tooth profile plane modification is carried out.A conjugate tooth profile design method of effective edge points is proposed,and the conjugate tooth profile of the convex tooth profile is solved by numerical env elope.The plane meshing characteristics of the designed tooth profile are analyzed,and it is verified that the tooth profile designed by this method can simultaneously realize secondary meshing and two-point meshing.(3)In order to solve the problems of space gear tooth interference and reduction of meshing teeth in the actual meshing process,three methods for tooth profile space modification of harmonic gear transmi ssion based on axial inclination,tooth profile rotati on angle and addendum interference are proposed,and the meshing characteristics of the modified space tooth profile are compared and analyzed.Taking the design section as the reference surface,the in fluence of the change of the axial modification amount on the meshing contact area and the number of meshing tooth pairs is studied.(4)Based on the transient dynamics,the physical assembly simulation of the harmonic gear drive was carried out,and the finite element analysis model of the key components was established,the stress distribution of flexspline ring gear under different tooth root transition methods is studied.The influence of two planar tooth profile design methods,clearance adjustment and effective edge conjugate point,on the contact stress of the meshing secondary ring gear is analyzed,and it is verified that the tooth profile designed by the effective edge conjugate point has more meshing areas.The distribution of stress in the major and minor axis directions and in different sections of the flexspline before and after modification in the assembled state was studied. |
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