螺絲成型機是利用鍛造將胚料逐步塑性變形成螺絲半成品，成型後的半成品會因高壓而黏貼在模具內，必須先利用前通出機構讓半成品留在母模，隨後再利用後通出機構通出半成品。為了配合前通出機構的運作，後通出機構必須具備一段暫停的時序，而一般後通出機構使用凸輪機構來產生此暫停時序。但由於凸輪機構具有製造成本高、易磨損且替換不便等缺點，近年來業界希望能改用連桿機構來取代凸輪機構。此外，為了生產不同長度的產品，後通出機構也必須具備可調整通出行程的功能。
本文的研究目的是針對螺絲成型機的後通出機構進行構造合成與尺度合成，設計具有暫停與可調整行程兩種功能的新型連桿式後通出機構。本文根據後通出機構所需的功能，將其分解成暫停機構與可調整行程機構兩個獨立的子機構，並分別對兩者進行機構運動合成。暫停機構的可行構造主要是引用文獻中已有的各種連桿式暫停機構，評選出的最佳構造為Stephenson III 型六連桿機構。至於可調整行程機構的可行構造，則是利用旋轉對與滑行對的排列組合而得到，評選出的最佳構造為RRRSR五連桿機構。接著，分別對兩個子機構的最佳構造訂定設計需求與設計限制，使用兩階段的網格式搜索搭配最佳化的方式進行機構尺度合成。最後，將兩個子機構組合起來，完成螺絲成型機新型後通出機構的運動合成。
本文所提出的新型後通出機構為全連桿式構造，因此不具有製造及保養成本高、替換不便等凸輪機構的缺點。此外，此機構在暫停區間所產生的輸出桿角度誤差，對通出工作完全不具負面影響，因此可視為具有極完美的暫停效果，同時，此機構在進行通出行程時的傳力效益甚佳。由於在尺度合成的過程中，本文融入了設計限制以及實際工程上需要考量的條件，因此此新型後通出機構應用在實際機器上的可行性頗高。最後，本文所提出的設計流程也可以應用於其他同樣需要暫停時序或可調整行程的機構設計。

A screw former deforms billets into semi-finished screws by a forging process. Because of the high pressure during the forging process, work pieces always stick to dies. Hence, ejector mechanisms are required to restrict work pieces to stay in female dies for being knocked out by knock-out mechanisms which must dwell for a period of time. Moreover, knock-out mechanisms must be adjustable to produce screws with different length. The purpose of this thesis is to design a new adjustable knock-out mechanism with a dwell period for screw former. The design requirements and constraints are concluded from the results of structural analysis and kinematic analysis of an existing adjustable knock-out mechanism for a screw former. Due to the separation of independent working functions, a knock-out mechanism is divided into two sub-mechanisms: a dwell mechanism and a variable-stroke mechanism. In the structural synthesis stage, the best structures of new sub-mechanisms, a Stephenson-III six-bar dwell linkage and an adjustable 4R1S linkage, are proposed and evaluated by using the decision matrix method. In the dimensional synthesis stage, the dimensions of each sub-mechanism are synthesized by a two-stage gridded-domain-search method for preliminary dimensions of the sub-mechanism together with an optimization approach for optimum dimensions of the sub-mechanism under the design constraints. The new synthesized adjustable knock-out mechanism, consisting of two linkages instead of a cam mechanism and a linkage, provides a perfect dwell period before the knock-out stroke for a screw former. It is low cost, convenient to switch, and easy to manufacture and maintain.

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