Meshing Theory Research Of Variable Height Modified Globoidal Worm Pair Drive

Hindley worm is processed by a linear blade from turning in the main cross-section worm gear tooth profile are straight.It has the characteristics that double line contact,the number of contact teeth at the same time,more carrying capacity,and high transmission efficiency.Due to the presence of frequent contact line which happens in the middle of the worm gear tooth surface,so worm gear is used to fatigue pitting and premature failure.The modification is to improve the meshing conditions by changing the helical surface of the worm so that shorten the running time of the worm pair,and improve the meshing quality.Firstly,based on the knowledge of differential geometry and gear meshing,taking the machine tool seat vertical height parameter into meshing analysis,the mathematic model of worm pair meshing analysis is established.The tooth surface equation of worm and worm gear,the meshing function of worm pair,the boundary function of two kinds of meshing,the parameter of curvature and the expression of microscopic meshing characteristic parameters are deduced by applying vector transformation and mathematic method of rotating matrix into the mathematic model.Secondly,the meshing mechanism of the TA worm pair drive is classified resaerch based on the high modification parameter.By meshing theory analysis of the original type and constant height modification transmission,the meshing characteristics of the corresponding worm pair are described in detail.It is proved that the type I and type II drive are exist in the heights modified condition.The highly modified expression is obtained from the aspect of easy manufacturing.Finally,the meshing analysis of the worm drive is carried out and the meshing performance is simulated by Matlab.The meshing characteristics of the two types of transmission,such as meshing partition and characteristic line,are verified by the simulation of the two types of transmission with high initial modification and constant modification.It is pointed out that the main problems of these two kinds of transmission are the constant contact line.Through the simulation of the standard drive and constant height modification drive,verifying the engagement features of these type transmissions,such as engaging the corresponding partition feature lines.And pointing out the main problems is the exist of regular contact line.By type I and type II variable height modification drive meshing example,the detailed study of macroscopic and microscopic characteristics of the two types conducted.Comparing with the first two kinds of transmission,the advantages of the variable height modified TA wormpair drive are pointed out.By means of the variation of the height expression coefficient,the meshing area size,instantaneous line distribution,single and double line contact and micro-meshing quality characteristics of the two kinds of height modified worm pair were studied,and suggestion is given about parameter selection of height modification.