Vibration Analysis And Experimental Research Of Particle Damping Lengthened Shrink-fit Tool Holder

The application of the lengthened shrink-fit tool holder to the high-speed milling process of large deep cavity molds,such as automobile dashboards and washing machine casings,can shorten the time of subsequent electric spark machining and manual polishing and polishing,thereby greatly improving the mold processing efficiency and shortening the mold manufacturing cycle.However,due to the small damping,long overhang and long diameter ratio,and small dynamic stiffness,the lengthened shrink-fit tool holder system is easy to generate vibration during machining,which affects the quality of the machined surface and the life of the machine tool and tool.On the basis of summarizing the research status of the vibration type,mechanism and control method of the tool bar at home and abroad,the particle damping is applied to the lengthened shrink-fit tool holder,in order to reduce the tool vibration and improve the milling processing quality and processing efficiency.According to the principle of dynamic vibration absorption,the particle damping the lengthened shrink-fit tool holder damping system is analyzed,and a simplified two-degree-of-freedom damping system with lengthened shrink-fit tool holder is obtained.Based on Newton's motion theorem,the dynamic equation is established.the relationship between mass amplitude ratio and mass ratio,frequency ratio and damping ratio is calculated.Finally,by analyzing the optimal frequency ratio and the optimal damping ratio of the damping system,the relationship between the amplitude-frequency response curve of the lengthened shrink-fit tool holder and the mass ratio is obtained.Based on particle damping vibration reduction technology,the static characteristics of the particle object are analyzed to obtain the distribution of the force chain between the particles when the particles are stationary,and the distribution relationship between the static stress and the filling depth;by analyzing the dynamic characteristics of the granules,the main energy-consuming forms of the particles during the movement process are obtained and a single-particle mechanical model is established;finally,the static characteristics and dynamic characteristics are combined to analyze the particle body,and the actual influence of the maximum static stress on the particle vibration and fluidization motion is obtained.In order to explore the effect of particle damping vibration reduction technology on vibration weakening of lengthened shrink-fit tool holder,the milling test of the lengthened shrink-fit tool holder under different particle damping materials is carried out.Through the analysis of the vibration signal,the influence of different particle damping materials,particle size,filling rate and other factors on the damping performance of the lengthened shrink-fit tool holder is obtained,which provides a new idea for the vibration reduction of the lengthened shrink-fit tool holder.