| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 97 === In the nut forming process, workpieces may stick to male dies because of high pressure forming. As a result, the knock-out mechanisms attached to female dies fail to knock out workpieces. Hence, ejector mechanisms attached to male dies are required to restrict workpieces to stay in female dies for being knocked out. Moreover, it is inconvenient to change the cam components when forming nuts with different thickness by a traditional nut forming machine. Thus, the nut forming industry is nowadays seeking for adjustable ejector mechanisms to produce nuts with various thickness.
The main purpose of this study is to design new adjustable ejector mechanisms of a nut former by using a systematic method for the structural synthesis and dimensional synthesis of the mechanisms. First, the design requirements and constraints are concluded from the results of structural analysis and kinematic analysis of existing adjustable ejector mechanisms of nut formers. According to the structural requirements for an adjustable ejector mechanism, some feasible adjustable ejector mechanisms are synthesized via the morphological chart analysis method. By using the method of decision matrix, four better designs are then selected for the dimensional synthesis of new adjustable ejector mechanisms. Based on the functional requirements of an existing ejector mechanism, the dimensions of the four designs are synthesized. Two of them are shown to fulfill the functional requirements for an adjustable ejector mechanism.
The main advantage of the new designs is that the synchronous ejection stroke of the synthesized mechanisms can be adjusted for forming nuts with different thickness. The design procedures used in this study can also be provided for the structural synthesis and dimensional synthesis of other adjustable ejector mechanisms of nut formers and relative mechanisms.
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