A Study on the Forming Process of Husk-Powder Composites by Using Guiding Devices

• Main Authors: Shih-Huang Yuan, 袁世煌
• Other Authors: Wen-Long Dai
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/69498845974044475108

碩士 === 逢甲大學 === 機械工程學系 === 88 === A further study on the characterization of molding process for rice-husk/PVA composite sheet is presented in this research. The rice-husk/PVA (RHP) composite sheet is made through the rolling process of the mixture of rice husk powders and PVA. An assistant forming device, wrinkle guider attachment, is developed to improve the formability of RHP composite sheet because the composite has very poor flowability and low forming capability. During deep drawing, the RHP sheet will easily buckle in the circumferential direction, and cause a lot of asymmetric wrinkles along the circumference of the forming part. Meanwhile, cracks will initiate because the friction force between die wall and part increases. The main purpose of the guider is to pilot the shrinkage in the pre-determined direction and position, and hence make controllable wrinkles to reduce the friction force. Consequently, more drawing depth is obtained during deep drawing. In addition, an advanced methodology, constrained processing method, for high depth drawing is also proposed in this study. While deep drawing, shrinkage will occur and extra-material exist in the part; and thus the extra-material must be removed from the part, or redistributed in the bulk material through compressing process. Therefore, we use the concept of internal and external constraint to control the shrinkage force and to enhance the formability of RHP composite sheet. Controlling internal constraint is executed by removing material from the composite sheet to reduce the material restraint according to the designed requirement. These results provide useful information not only on the appropriate manufacturing requirements of RHP composite parts, but also how to design and optimize the forming methodology of composite structures or mechanical elements. Moreover, analysis results indicate that the developed methodology is applicable to the fabrication of containers, packagings or other applications.