Analysis Of Contact And Gear Surface On Modified Planar Double-enveloping Worm Pairs

The transmission types of modified planar double-enveloping worm pairs are generally divided into two kinds. One isâ… -type contact line ,the other isâ…¡-type. However through the research of this paper's author, Actually there are not the only two contact patterns. Besides these two types, in a certain moments there also will be a contact pattern of the first enveloping reappearing during the second enveloping and there will be a transformation process in which the standard contact type is changed gradually based on the vary of the parameters. And these three contact patterns will appear on the worm gear surface at one time or appear repeatedly. We can name this pattern as III-type contact line. So the construction of worm gear will be changed completely. The two kinds of boundary lines also will appear on the worm gear surface in various forms.This paper mainly discussed the vary of the type of the contact when the two-parameter are changed. We obtained a new method to determine the type of contact lines through the analysis of equation of the second limiting curve of worm gear. And we also make the picture which shows the relationship of the vary of the two-parameter and the contact line type using Matlab language programming. So that the determining of the contact type achieve a graphical visualization. There have an important practical significance to reveal the evolution of contact ,guide the assembly process of worm vice and recorrect the way of the parameters modified .The structure of worm gear surface are analysis every types using the phase angle analysis and the first limiting curve. And divide the worm gear surface into two areas, one is working, another is not. This paper also proposes the measures of increasing the working area and avoiding the root cutting, which increase the carrying capacity of worm gear and enhance lubricity .