Spiral bevel gear is an important transmission part of automobile, engineering machinery and other equipment. It mainly includes two forms of tapered teeth and equal height teeth. Compared with the same height teeth, the performance of equal height teeth is better than that of tapered teeth, and the advantages are more prominent. However, its modeling and manufacturing process are more complex, which limits its application and development. Therefore, the research on the automatic modeling and manufacturing method of equal high tooth spiral bevel gear has important theoretical and engineering significance to improve the performance and modeling and manufacturing efficiency of equal high tooth spiral bevel gear, and promote its development and application.
Taking the equal height spiral bevel gear as the research object, the parameter equation of equal height spiral bevel gear is deduced and established. Taking UG / OpenGRIP as the secondary development tool, the automatic modeling of three-dimensional solid model, hot forging model and forging die model of equal height spiral bevel gear is realized, The forging process of equal high tooth spiral bevel gear is discussed. The main conclusions are as follows:
(1) Based on the formation principle and process of spherical involute, the spatial rectangular coordinate equation of spherical involute is deduced and established; Based on the formation and properties of the extended epicycloid, the relationship between the number of teeth and tool position of the imaginary plane gear and the helix angle at the midpoint is deduced. Finally, the plane polar coordinate equation, space rectangular coordinate equation and the calculation formula of helix angle at any point of the extended epicycloid are obtained; Based on the meshing principle of equal height teeth and the relevant knowledge of analytical geometry, the calculation formulas of the radius and cone height of base circle, pitch circle, tooth tip circle and tooth root circle are established; The cutter positions of n-type teeth and G-type teeth under different conditions are studied, and the method of tooth profile correction for the two gears is put forward.
(2) With the help of UG / OpenGRIP secondary development language, the automatic modeling method of equal height spiral bevel gear matrix, tooth shape entity and tooth root fillet is established; The reasonable addition methods of tooth profile, tooth width, tooth surface allowance, tooth top allowance and tooth root allowance are analyzed and established. The small end tooth top and gear big end are trimmed, and the draft angle and forging fillet are added. The three-dimensional automatic modeling of cold forging model of equal height spiral bevel gear is completed. Considering the influence of temperature and elastic deformation on the size of gear forging, the hot forging model of equal height spiral bevel gear is established. By making the toolbar menu, it is convenient to call the modeling program, and through the comprehensive comparison with the existing modeling results and theoretical results of equal height spiral bevel gear module, it shows that the accuracy of automatic modeling results is high.
(3) According to the standards of the relevant manual of forging die design of equal height spiral bevel gear, combined with the structural composition of the actual forging die and the characteristics of the forging process, the two-dimensional design of the precision forging die of equal height spiral bevel gear is realized; The automatic modeling of each part of precision forging die is carried out by UG / OpenGRIP secondary development language; Based on UG / OpenGRIP, the thread modeling subroutine is developed, the parametric modeling method of thread hole and bolt is proposed, and the three-dimensional parametric automatic design module of precision forging die is developed.
(4) Through hot compression test, the high temperature hot deformation behavior of 20CrMnTiH steel is studied, and its constitutive model and hot working diagram are constructed. It is found that the conditions of 1050 ° C temperature and strain rate of 0.1s-1 are the best conditions for final forging process; The finite element model of precision forging process of equal height spiral bevel gear is established, and the finite element simulation of its forming process is realized; A blank shape with concave section is designed. The forging simulation of equal height spiral bevel gear is carried out with 6 groups of special-shaped section blanks. It is found that No. 2 blank can achieve the comprehensive goal of no external flash and low forming load.