全密閉型馬達塑膠風扇強度改善研究

Abstract

目前一般常用的全密閉型馬達，在風扇的使用上，考慮成本與加工組裝便利等因素下，逐漸由金屬風扇改為塑膠風扇，塑膠風扇雖然有其重量輕、組裝方便、價格低廉與儲存方便等優勢，但在強度上與金屬風扇相較，就有一段差距，在高轉速使用下常會發生塑膠風扇斷裂的情形，嚴重地影響馬達的可靠度。但使用塑膠風扇是不可避免的趨勢，因此如何提高塑膠風扇的強度為本次研究的主題，希望藉由不同塑膠材質的強度分析、機械特性試驗、與有限元素分析模擬，找出塑膠風扇強度改善的方法，做為後續產品改善的參考及依據。 首先透過拉伸試驗確認塑膠材料的機械性質，然後運用Catia分析軟體做應力分析，確認現有設計風扇的強度是否足夠?並針對風扇應力集中或強度不佳之處加以改善，同時配合不同材質的運用，尋求較佳的改善方案，提高風扇安全係數。 經過實驗與分析結果顯示，將現有風扇迫取孔形狀改善，同時使用Nylon + 20% Glass fiber，風扇的強度最佳且產生的應力亦最小， 並將此結果做為本次風扇強度改善的建議。

For recent application of ventilation fans, considering the cost and the facility during process and assembling, metal fans mounted in totally enclosed fan cooled type motors are being gradually replaced by plastic ones. Though light weight, ease to assemble, low cost and simple storage are considered as the main advantages of plastic fans, its strength comparing with metal fans is inevitably weaker. Furthermore, plastic fans failed or fractured relatively easily especially during high speed operation, which seriously influence motor's operation. While the utilization of plastic fans is an unavoidable trend, the main point of this research will focus on increasing the strength of plastic fans. Solutions for improving plastic fans' strength were compared by analyzing different types of plastic materials, mechanical property test and finite element analysis, which will also be a fairly important reference for quality improvement. The first step is to define the mechanical property by tensile test. Then use Catia (software) to analyze stress distribution on the fan blades,and check if the current design is adequate. Shall it is not sufficient, the application of a variety of different materials and design were selected in order to improve the strength and increase the fan's safety factor. From experiments and analysis, it is found that modification of the form of fan's jacking holes and apply Nylon + 20% Glass Fiber as fan material could achieve the best strength and the least stress. This result is proposed as a suggestion for improving fan material's strength.