Identification Of Weak Parts Of Machine Tool And Research On Vibration Suppression Of Spindle Based On External Damper

The CNC machine tool is a complex and precise overall system composed of multiple components.Each component will vibrate during the machining process,and the component with the highest vibration intensity is the weak component of the machine tool.Current research generally regards the whole machine tool as a rigid body,and considers the knife tool as the weak part of the machine tool.This method ignores the internal structural characteristics of the machine tool.In view of the above problems,this article takes VMC850 E vertical CNC machining center as the research object,and does the following research on how to identify the weak parts of the machine tool and suppress the vibration of the weak parts by adding a damper:First of all,the modal parameters of the machine tool structure are obtained from the hammering experiment under the static state of the machine tool,and the modal mass distribution matrix is obtained according to the modal vibration shape of the machine tool structure.The greater the modal quality,the greater the vibration energy of the corresponding component,and the more the component is.It may be a weak part,from which it is identified that the spindle is most likely to be a weak part.The modal parameters of the machine tool structure are inherent attributes of the machine tool,which is only related to the structure of the machine tool itself and has nothing to do with external excitation.In the dry-running experiment where the spindle starts and stops randomly,the response signal of the spindle identifies the mode of the corresponding order of the machine tool,so it is confirmed that the spindle is a weak part of the experimental machine tool.Secondly,according to the structural characteristics of the main shaft of the weak component,an additional damper structure is designed for easy loading and unloading.This method absorbs the energy of the main shaft vibration through the form of additional damping and mass blocks to reduce the vibration intensity of the main shaft.Perform disassembly.After the damper is added,the amplitude of the response signal of the spindle's random start-stop dry running is significantly reduced,indicating that the additional damper does have a suppressive effect on the vibration of the spindle.In-depth analysis of the modal parameters of the main shaft,it is found that the natural frequency and damping ratio of the main shaft are changed after the damper is added.Finally,a cutting experiment was performed on the workpiece with the same shape when a damper was added to the main shaft to explore the effect of the added damping on the machining quality.Under certain processing parameters,the greater the external damping,the smaller the amplitude signal of the main shaft,indicating vibration suppression.The better the effect.According to the working deformation analysis method,the contribution of each mode of the machine tool to the structural vibration during the machining process is decomposed,and the influence of the cutting excitation force on the main vibration mode and vibration characteristics of the spindle is analyzed,and the influence of the various modes of the spindle after the addition of a damper is analyzed.Changes in the degree of structural vibration contribution during processing.In summary,this article mainly uses experimental modal analysis and working modal analysis to identify the weak parts of the machine tool,proposes an additional damper to suppress the vibration of the weak parts,and passes dry running experiments and cutting experiments.To verify the vibration suppression effect of external dampers on weak parts.