封切機當轉速由250rpm提高至450rpm時,其切刀的加速度值會急劇增高,影響封切的效果。本論文之目的,主要在於改良凸輪的運動曲線,有效降低切刀的加速度峰值。 首先,本文訂定450rpm時切刀運動的邊界條件,並以四段五階多項式曲線合成出滿足條件的凸輪運動曲線,當做原始曲線。其次,利用最佳方法,將加速度曲線的三個峰值當做目標,設定各種組合的權重,組成多目標函數,再以變量轉換法配合隨機猜測起始值等最佳化技術,找出最佳化的五階多項式運動曲線。最後,本文根據最佳化五階多項式曲線的線型,提出一個新型的梯形加速度曲線,並將加速度曲線的峰值再一次的降低。 相對於原始曲線,最佳化五階多項式曲線的加速度峰值降低了16.4%,而新型梯形曲線的加速度峰值降低了27.9%,證明本文所提出的方法是可行且有效。
When the speed upgrade to 250rpm to 450rpm, the cutting acceleration of the sealing and cutting machine will get higher in a very short time, and influence the result. So, the purpose of this paper is mainly about improving the motion curve of cam. First, setting up the boundary conditions of 450rpm cutting motion, then, using five-order polynomial curves of four steps to satisfy the cam motion curve. Secondly, by using the Optimization method, taking the three peaks of acceleration curve as target, setting the weight of each combination to combine the multiple objective function, and then using variable transformation method to guess the value randomly to find the best five-order motion curves. Finally, according to the best five-order polynomial motion curves to give a new trapezoidal acceleration curve and reducing the peak value of acceleration curve. With respect to original curve, the best five-order polynomial motion curve is reducing 16.4% of acceleration peak value, and the new trapezoidal acceleration curve reducing 27.9%,so it proves that the methods of this paper is workable.