Globoidal cam indexing mechanism (GCIM) plays an important role in automation and machining tools. With the compact structure, a GCIM is able to reach the required precision on account of high stiffness and minimized backlash. The requirement to improve the indexing accuracy for GCIMs from industry applications drives the research going on. In this dissertation, two strategies to improve the indexing accuracy of GCIMs are proposed.
The first strategy is by considering the manufacturing parameters involved in the processes of machining and assembly. Analytical expressions for the turret motion and indexing accuracy of grooved GCIMs have been identified. Based on the kinematic and geometric relationships between the cam and its roller-follower turret, the effects on the output of the cam mechanism due to clearances (between the cam and roller; in the roller bearing), preload (change of the distance between input and output shafts), and the cam taper angle have been investigated. As a result, the roller alternation in the cam-turret system can be analyzed. Favorable parameters for the design, machining, and assembly can be selected to manufacture such devices with improved turret motion and indexing accuracy. Worked examples are given to demonstrate the applications of the approach.
The second strategy is a technique for designing torque balancing cam (TBC) systems that are composed of spring-loaded planar cams with translating followers for GCIMs. Such a device can be attached to the input shaft of a GCIM to reduce the variation of its cam rotational speed. As a result, for high-speed applications, the intensity of residual vibrations of a GCIM can be decreased and its indexing accuracy can be improved. To approximate the required counterbalancing torque curves, nonparametric rational B-splines have been applied to synthesize the planar cam motion programs. Experimental results have also been shown in a practical and high-speed application to prove such a TBC mechanism is useful and effective.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0902103-141008 |
| Date | 02 September 2003 |
| Creators | Ho, Hui-Chun |
| Contributors | Bor-Jeng Lin, Kuang-Yuh Huang, Der-Min Tsay, Cheng-Kuo Sung, Tzuez-Lih Chern, Jao-Hwa Kuang, Ying-Chien Tsai |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0902103-141008 |
| Rights | not_available, Copyright information available at source archive |
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