| The traditional long flexspline harmonic drive gear can′t satisfy application requirement owning to the limited installation space in the body of humanoid robot, however, the short flexspline one becomes more acceptable and favor by the researchers because of the advantages of compact structure and small size. Nowadays, only a few country knows the skill of design and manufacture a short flexspline harmonic drive gear. In china, the related technology started late and there are many problems to be studied further. In this paper, the author focus on the meshing theory and structure analysis of short flexspline and offers reference on the profile and structure design of short flexspline harmonic drive.First, the teeth kinematics of flexspline is deduced from the characteristic curve theory and the conjugate profile of rigid spline is got. On that basis, a subsection conjugate teeth profile is proposed aim at the coning angle of flexspline when deformation and the proposed profile is suit for short harmonic drive use.Next, to solve the stress leap by the reduction of flexspline axis length, the relation between max equivalent stress and structural parameters of flexspline is obtained by finite-element analysis. A optimized structure is got and the stress distribution in it made uniform. These results can be used in flexspline structure design.Then, a harmonic drive finite-element model with contact pairs between meshing surfaces was proposed. Take the type 50 harmonic drive as an example, the analysis result, including equivalent stress, deformation, meshing force on each teeth surfaces of the flexspline and the contact ratio is got. And the rationality and is validated by the above result.Finally, according to the analysis above, a type 50 harmonic drive prototype with 1/4 short flexspline is designed. In additional, the housing of short harmonic drive and the simple load device are designed, these work laid foundation for the next step testing. |
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