工具機次系統可靠度研究

摘要：工具機的可靠度直接影響用戶的使用情況及購買慾望，可靠度與精度穩定性一直是台灣工具機產業的弱點，可靠度必然重要但往往在開發新產品的時候總是不被放在首要的考慮重點，主要因為工具機系統是由多個次系統組合而成的一個複雜系統，其系統結構複雜、功能多樣性及應用範圍廣，整機系統的可靠度不僅須考慮各次系統的問題，還須考慮次系統間的匹配問題，這些問題都會影響整機系統的可靠度，也因此在可靠度工程的實施顯得困難重重。

次系統可視為一獨立產品，其可靠度的實施與整機系統相較之下，較易實行，且次系統可靠度的提升，必定對整機系統可靠度的提升有所幫助，本文將以一個次系統為例，介紹一系統於設計階段導入可靠度工程技術的方法，於系統方塊圖的建立及FMEA分析中找出影響失效原因的關鍵零件，針對此零件進行可靠度預估。

Abstract：The reliability of machine tools affects the usage and purchasing desire of users directly. The reliability and stability of accuracy are always the weakness of Taiwan’s machine tools industry. Even though the reliability is very important, it often has not been the primary consideration during the development of a new machine tool. The main reason is that a machine tool is a complex system which consists of multiple subsystems. The system usually has complicated architecture and versatile functionalities with a wide application range. The reliability of machine tool is not only the problem of individual subsystem, but also the correlated problems among all the subsystems. All of these problems affect the reliability of a machine tool system. Therefore, the implementation of reliability engineering becomes very difficult.

The subsystem can be considered as a separate product. The implementation of its reliability is easier than the whole machine tool system. The reliability enhancement of a single subsystem is helpful to the reliability of the whole system. This article uses a subsystem as an example to introduce the reliability engineering technique during the design phase of machine tool. The key part affecting the cause of failure was found through the establishment of the system block diagram and the FMEA analysis. The reliability estimation of this part was performed as well.

關鍵詞：工具機、預估、次系統可靠度
Keywords：Machine Tool, Prediction, Subsystem Reliability

前言
國內的工具機在功能及精度面取得了一定的成果，但在可靠度方面仍與國外先進工具機廠有很大的差距，工具機可靠度水平的高低，嚴重影響產業的製造能力，也因此台灣在高階工具機市場佔有率低，僅能在中低階市場上生存，另外中國大陸在2009年至今針對工具機可靠度已有深入的研究，已漸漸地拉近與國內工具機可靠度的差距，且台灣目前在工具機可靠度的研究技術少，未來國內工具機將陷入被前後包夾造成出口衰退的危機，因此提升國內工具機可靠度是必要的課題。

次系統可靠度分析
失效模式與效應分析是在系統開發設計的過程中，對系統各組成的單元各種失效模式及對系統功能的影響，及產生後的嚴重程度進行分析，提出可能採取的改善措施，以提高產品的可靠度，本章節簡單介紹於產品設計階段如何透過失效模式與效應分析（failure mode and effect analysis, FMEA）的可靠度分析手法，瞭解產品主要的潛在失效原因及可能會故障的關鍵零件。