Xuezhu Dong

Lubrication characteristics of dual-tori double-enveloping toroidal worm drive

The present study is an application of elastohydrodynamic-lubrication (EHL) theory on a new type of toroidal worm drive with concave worm profile, ground by a grinding wheel whose profile consists of two circular arcs. The EHL analysis is focused on the minimum oil-film thickness and entraining geometry. When a primary geometric design is made for a worm set, many factors, except speed and contact geometry, are very difficult to know exactly. For this reason, a method is proposed to evaluate the minimum EHL oil-film thickness indirectly but conveniently in the whole contact area. Parallel research of the entraining geometry for this type of worm pair has been accurately carried out by using the theory of gearing. On the basis of the theory established, the EHL characteristics of the recommended worm pair are discussed in detail by means of computerized simulation approach. Obtained results show that this kind of hourglass worm pair has preferable EHL performance because favorable unification is embodied in terms of the forming condition of oil-film and its thickness within the whole contact area.