| dc.description.abstract | The purpose of this thesis is to study the meshing characteristics of harmonic drive with a novel tangential double Bezier tooth profile as well as the cutter design of its inner toothed circular spline. Nowadays, harmonic drives are mainly used in fields with small space, high precision, and high reduction ratio, such as semiconductor equipment, robotic arm joints, medical equipment, and other institutions. With the development of global intelligent machinery in recent years, the number of harmonic drives used in the robotic arm increases year by year.
However, there is currently a lack of systematic design methods and processes for harmonic drives in the country. Therefore, through a series of characteristic analysis, this research tries to explore various tooth profiles and structural designs to find the design parameters with the best meshing characteristics. In addition, the innovation power skiving tool design for generating the optimum circular spline profile is provided. First of all, based on the theory of gearing and enveloping method, the mathematical models of involute and tangential double arc harmonic drives, those are common in the market, and of innovated tangential double Bezier harmonic drive in this paper are developed. Then, the self-developed automatic meshing generation program is used to establishe the two-dimensional and three-dimensional finite element models to conduct the finite element analysis of harmonic drives to obtain the stress distribution, torsional stiffness, number of engagted teeth, hysteresis loss, and transmission error. Based on the finite element analysis, the optimization analysis of two-dimensional tooth profile and that of three-dimensional structure are carried out sequentially, and the design parameters (including tooth profile and FS’s cup structure) of the harmonic drive with the optimal torsional stiffness and number of engaged teeth are obtained.
Subsequently, a general mathematical model for the design of the power skiving tool was developed to derive the tool’s error-free designed cutting edge (for cutting the tooth profile of the optimum circular spline) and the disk-shaped grinding wheel (for grinding the designed cutting edge of the tool). Moreover, the cutting accuracy of gear is calculated according to the ISO accuracy specification to discuss the influence of the resharpening of the power skiving tool on the tooth profile error, maximum absolute error and peak-to-valley value of the circular spline. Finally, the machine compensation angle is added in the machining process to reduce the tooth profile error, caused by regrinding the rake face, to prolong the tool life, and the effective resharpened amounts of the tool before and after the machine compensation are compared. | en_US |