具三弧面中間桿平移式從動件之變速平移凸輪機構的設計

The Design of Varying-velocity Translating Cam Mechanisms with Translating Follower Having an Added Triple-arc-faced Intermediate Link

吳文碩(Wu, Wen Shuo)

指導教授 ： 吳隆庸

國立清華大學/工學院/動力機械工程學系/碩士(2015年)

https://doi.org/10.6843/NTHU.2015.00040

摘要

螺帽成型機是製造螺帽的專用機器，此機器的進料切斷裝置是其關鍵機構，其機構是一由滑件曲柄機構所驅動的平移凸輪。對於習用的平移凸輪機構而言，必須利用回位彈簧使從動件與凸輪面保持接觸。使用回位彈簧除了會對增加從動件與凸輪間的接觸應力，並且過大的回位彈簧會產生空間配置不緊實的問題。為了解決上述的問題，本文提出一種嶄新的具有中間桿的搖擺式從動件之盤形凸輪構造，該中間桿件包含有三弧面並以軸樞與端接器相聯接。該凸輪機構具有兩組相對應的輪廓曲線，且凸輪輪廓可以為溝槽式或是凸緣式的設計。該凸輪機構屬於確動凸輪因為該搖擺式從動件可隨時與凸輪保持接觸的三個接觸點。本研究提出一套解析法來設計三弧面中間桿平移式從動件之平移凸輪機構。藉由適當的設計可發現，相較於習用的滾子從動件，採用加入三弧面中間桿從動件之平移凸輪機構可使從動件與凸輪之間的接觸應力極值降低約58.9% ~ 78.1%；相較共軛式平移凸輪的設計，採用新式的從動件可使從動件與凸輪之間的接觸應力極值降低約39.1% ~ 67.6%。

關鍵字

螺帽成型機 ； 變速平移凸輪機構 ； 三弧面 ； 有槽凸輪 ； 帶肋凸輪

並列摘要

Nut former is a machine used for production of nuts. The core part of nut former is its cutting-and-feeding mechanism, which comprises a translating cam driven by slider-crank mechanism. For the conventional type of nut formers, an external force imposed by return springs is necessarily needed to maintain contact between cam and follower. The application of such a spring-loaded cam-follower system not only results in higher contact stress but also makes the machine undesirably incompact. To the end of solving these problems, this research introduces a novel configuration of translating cam mechanism with an intermediate link mounted between the cam and the translating follower. The intermediate link is made triple-arc-faced and pivoted on end-effector. The cam has two sets of cam contour which can be either grooved or ribbed form and the intermediate link is positively-driven because it remains multiple-point contact with cam contour at any instant. An analytical approach is addressed to illustrate how to synthesize such cam mechanism. With proper design of such cam mechanism, it can be found that application of the triple-arc-faced follower yields a reduction of the contact stress by 58.9% ~ 78.1% in comparison with using conventional roller follower and by 39.1% ~ 67.6% in comparison with the conjugate cam type, respectively.

並列關鍵字

Nut former ； Translating cam mechanism ； Triple-arc-faced ； Grooved cam ； Ribbed cam

參考文獻

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