Rib Effects on Locking Torque of Plastic Boss
| Autor: | Jia-Qing Chu, 朱家慶 |
|---|---|
| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 A boss design with an outside diameter that is two or three times the inside diameter is sufficient strong for most application, such as assembling, positioning and supporting. To support the “locking torque” in assembling that with self-tapping screw, an enhanced rib would be added on the outside of the boss. The enhanced rib can both improve the melt polymer flowing at injection process and prevent the residual stress deforming. In this study, six types of the boss were designed and molded under the same injection condition. The maximum locking torque of these bosses can be measured with the torque-test machine. The boss design emphasized to use the boss and the enhanced rib at the same time. It should avoid to using the boss without any enhanced rib. The boss must have enough strength to support the locking torque. Besides, it can’t crack. The three main functions of the enhanced rib are to reinforce the boss, improve the polymer melt flow and prevent the deformation of residual stress. The data indicates that the fourth circle is the maximum locking torque stage when the self-tapping screw locks into the boss. The curve of this stage is from 1080∘ to 1440∘. Besides, it will continue the value of the locking torque until the boss produces the strip. In these six different types of the boss, the maximum locking torque of the boss without the enhanced rib is 4.68㎏f -㎝. On the other side, the maximum locking torque of the boss with two-side enhanced rib is 7.29㎏f -㎝. So, using the boss with two-side enhanced rib is almost 1.56 times as much as using it without any enhanced rib. As a result, the value of the boss with two-side enhanced rib is actually much bigger than the boss without the enhanced rib. That way, we can see that the enhanced rib has a large influence on the boss. Therefore, we suggest when you design the boss, you should focus on the design of the boss with enhanced rib, and avoid using the boss alone. Whether using the single or two-side enhanced rib, the maximum locking torque will be different due to the different shapes of the enhanced rib. The main aspect of this experiment factors in the need of the factory operations. The real conditions in the factory should be used to make this experiment of the maximum locking torque. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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