Identification And Research On Characteristic Parameter Of Machine Sliding Joint

High-speed, precision, complex, intelligent and green technology is the general trend of development of modern CNC machine tools. The grade of precision processing technology has been elevated from the original wire-level to the current micron-level. Improving the geometric precision of machining and other indicators such as reducing the geometric error of machine tools is increasingly important. Dynamic and static characteristic of the main system of machine tools is the key factor of production. It is proved that damping and elasticity of machine tools'joint is greater than mechanical structure themselves', so joints affect the dynamical characteristic of machine tools very much. The matter of how to get accurate dynamic data of joints has always been attached great importance to by the scholars in the field of machinery manufacturing and structural dynamics. Therefore, the study of the dynamic characteristics of the mechanical joints is of great significance.This issue is part of the national key projects--Database of joint characteristic of the numerical control machine and the digital system design of machine's static and dynamic function accuracy. According to the Y direction sliding guide of a large gantry milling machine, an experimental system for testing dynamic characteristic parameter of sliding state joints is designed. It can be used to test sliding guide joints'parameters in different load and relative speed and other conditions.Experiments use Rapid time-steady-state sinusoidal excitation swept shock excitation method. The excitation power is great and the energy is concentrated. Excitation response uses static data and has high SNR and more frequency resolution, and it sampled in a whole cycle, the result has a high precision. A useful method on testing the actual contact ratio of joints is used on data processing, which is base on relative displacement of vibration. It can make the multi degree of freedom system equivalent to a single degree of freedom system and eliminate the vibration of basic, and finally obtain high accuracy recognition.Unit area parameters of sliding guide joints under the conditions of several engineering are tested. And the impact of external conditions to the damping is analyzed and explained, providing academic consult for the method of getting the joint of high stiffness and big damp modulus.