Evaluation for Vibration Restriction of Punch Press by CAE.

Abstract

A computerized numerically controlled C-frame turret punch press for sheet metal punching induces impulsive vibration and accompanying noise when punching. Actual study of the vibration and noise reduction has been mainly carried out by experimental analysis using actual machine structures. In recent years, the finite element method (FEM) has spurred remarkable progress in numerical analysis. In the analysis of actual complicated structures by the FEM, many natural frequencies and eigenvectors are obtained in the specified frequency range as a result of computer calculations. Important modes for the vibration restriction are usually picked out from the results of FEM analysis by professional engineers on the basis of experimental results. In this study, bending vibration of a C-frame turret punch press frame which radiates noise when punching was noticed. Then, a new evaluation criterion of the vibration which strongly influenced noise radiation, that is, "modal inertance between the load point and the response area", was developed. Examination of the modal inertance in comparison with the experimental results showed effectiveness in actual use. Furthermore, this evaluation criterion was applied to improve the actual frame structure of the C-frame turret punch press to acquire a much more restricted "vibration-free" structure and confirmed the criterion's effectiveness.