帶胚玉米粒機械脫粒之研究

Abstract

糯玉米較普通玉米含有更豐富的營養和更好的適口性，且易於消化吸收，因此將玉米之胚芽保留，其營養將更有利於健康。若能將帶胚糯玉米粒作爲主要糧食作物之一，能讓全球主食有了替代選擇，相信其開發前景是非常可觀的。國內尚未有帶胚玉米之脫粒機，目前用手工的脫粒方式，其產量實無法應付國內、外市場之所需。 機構設計先以有限元素法分析，不僅可以增加產品設計的可靠性、更可減少試驗成本、加速研發時程，且提供設計者較精確的設計參數。玉米的力學特性對玉米粒的損傷及玉米脫粒裝置的設計具有重要意義，透過對玉米進行物性試驗，可以獲得其機械性質，在此基礎上，根據玉米果穗結構建立玉米幾何模型與有限元素計算模型，採用ANSYS電腦輔助工程軟體模擬玉米果穗在不同重量之推進力及三個不同旋轉速度之橡膠滾輪作用下的應力分佈，找出脫粒設備之情境，以決定研發脫粒設備所施與之力量及脫粒速度。進而研究玉米脫粒的損傷機制，所提供的模擬分析結果，可作為後續脫粒裝置優化的依據。 本研究將先針對國內外玉米脫粒裝置進行技術剖析，並研製帶胚玉米粒脫粒設備。根據ANSYS電腦輔助工程軟體之模擬結果，以玉米果穗施予2公斤向下壓力及三個橡膠滾輪的轉速各為108 rpm、72 rpm、36 rpm之邊界條件進行分析，其結果可收斂並求解成功，該模擬成果進一步應用於所研製之帶胚玉米粒脫粒裝置上。以含水率30%的白色糯玉米為對象物，以三個同方向而不同旋轉速度(108 rpm、72 rpm、36 rpm)之脫粒元件間所形成的速度差且以定向進給的方式施予2公斤之推進力來測試玉米果穗之脫粒效果，透過玉米脫粒裝置之性能試驗，結果顯示該設備滿足玉米脫粒過程中對破損率之低損耗的要求，且對胚芽的傷害最小。實際實驗結果，脫粒率為99.25%，破損率為0.32%。

Waxy corn contains more nutrients and better palatability than ordinary corns, and it is easier to digest and absorb. If the embryo of corn kernel can be preserved, its nutrition would be more salubrious. Hence, if we can use waxy corn kernel with embryo as a main grain crop, it could have an alternative for staple choices; and we believe the prospect is quite substantial. However, there are no corn shellers to thresh the corn kernel with embryo now. Currently, people operate the threshing process manually, and the output cannot meet the needs of domestic and international markets. The mechanism design is analyzed by the finite element method (FEM) at first, which not only increases the reliability of product design, but also reduces the experimental costs. FEM can accelerate the development process and provide designers with better design parameters. Mechanical characteristics of the corn was important regarding the damages of the corn kernel and the design of corn shellers. Finite element models were established according to the structure and mechanical properties of corn ear. The computer-aided engineering software ANSYS was used to simulate the stress distribution of the corn ear under different weight propulsion and three different rotational speed on rubber rollers. The best situation of the threshing equipment is used to determine the strength and the speed of exerting on corn sheller. Additionally, we can study the damage mechanism of corn threshing. It provides theoretical basis for the subsequent improvement of the threshing device. In this study, the technical analysis of the domestic and international corn threshing equipment was conducted to develop a threshing device of the corn kernel with embryo. According to the simulation results of ANSYS, the parameters of 2 kg downward pressure and the three different rotation speeds (108 rpm, 72 rpm, 36 rpm) on rubber rollers were used as the boundary conditions of corn ears. The ANSYS simulations were converged and solved successfully. The simulation results were further applied to develop the threshing device of the corn kernel with embryo. The white waxy corn contained with 30% of moisture content was used as a sample, the threshing elements at different rotation speeds (108 rpm, 72 rpm, 36 rpm) and in a directional feed with 2 kg propulsive force to pass through the performance testing on corn threshing device developed in this study. These results showed that the device qualified the requirement for the lowest loss of breakage rate during the threshing of corn. And it resulted in the least damage to the embryo. The experiments used ANSYS parameters as input settings gave threshing rate of 99.25% and breakage rate of 0.32%.