The Study On The Contact Force Of Micro Gear Transmission Considering The Role Of Surface Forces

The mini-gearing transmission systems were widely used in the space,avigation,military industry and also robot,toy,clockwork,medical equipment andtool machine,etc.The transmission mechanism of the traditonal involute gear with a normal dimension has became much maturate,nevertheless,there is much difference in the aspect of stress distribution on the tooth profile for the involute mini-gearing system,therefore the calculation method of contact force in the case of traditional transmission will be not suitable for the mini-gearing system.In regard to the dimensional influence,as the dimension of workpiece is decreased to a critical level,the surface force has dominance over the tooth instead of the mass force.In this project the module of the mini-gear has been decreased to 0.01 mm,the micro-forces including the surface force should not be neglected,e.g.Van de Waals force,electrostatic force capillary force and Casimir force.Therefore the tooth endure the forces not only the torque during its operation,but also the surface action force,at the same time,the calculation of the surface action force is very complicated.It will be meaningful to develop a practical calculation method of the surface action force for the mini-gearing system.It will also provides the premise conditions for the calculation of contact strength,bending strength,scuffing and wear resistant.The main objective of this study is to establish calculation method of the surface action force based on the geometry model and achieve the concerned theory of the mini-gearing system.By establishing the geometry model of surface force calculation,the a approximate calculation formula of the Casimir force will be developed for the meshing teeth of the mini-gearing system,thereby The contact force calculation formula taking the surface Casimir force into account will be derived for the meshing teeth.Several study results have been reached in this project as follows:1.Take a involute spur gearing system which works at a vacuum condition as the study example,establish the geometry model for the solution of the action force between the mesh surfaces.2.By the coordinate of th meshing point,the involute formula of any meshing location,and the coordinate variation,a calculation formula of the action force upon the tooth profile was developed,and the action scope of this force was also given.3.Based on the force model upon the tooth profile,by the Casimir force upon unit area.A calculation formula for the Casimir force could be developed at each mesh point during the gearing transmission,and the variation scope of mesh point could be also provided.4.The concept of the Casimir force upon unit tooth thickness an its calculation formula have been provided.By the calculation example,several variation relationships have been studied,such as the relationship between Casimir force upon unit tooth thickness and the variation of mesh distance,the the Casimir force upon unit tooth thickness and the variation of mesh location,tooth geometry parameters,and number of teeth and ratio respectively.5.A calculation formula for the contact force at any meshing point of the mini-gearing system has been developed which works at the vacuum condition and without regard to friction force.6.A calculation formula for the contact force upon unit facewidth of mini-gearing system when the input torque is zero.By the calculation example,the relationships between the contact force upon unit facewidth and the mesh distance,the mesh location,the tooth geometry parameters,the number of teeth and ratio have been analyzed respectively.