Research On Turning Vibration At Different Feed Speeds Based On Moving Load Theory

The slender workpiece is difficult to cut and easy to vibrate or chatter for its special structure.The improvement of production efficiency makes extensive use of cutting output and cutting speed,which makes vibration problem obvious and the moving load more and more prominent.The theory of cutting vibration has not paid enough attention to the influence of feed speed,and the classical Lobe diagram considers only the effects of rotational speed,depth and width on the machining stability.This paper analyses the influence of feed rate f in turning process on the turning stability from the point of view of moving load theory,and the main research contents are as follows:The paper introduces the theory of moving load,and the two important relationships between the moving velocity and the natural frequency of the beam are derived from the vehicle-bridge model,the theory points out that the moving speed affects the vibration of the carrier.Then proceed to the rotation axis model of the moving load in three directions and the simulation results point out that the moving speed affects the vibration of the loaded rotating shaft.The tool and workpiece are paid enough attention to study the influence of feed rate on cutting vibration in the cutting process.So the specific experimental exploration of the tool and workpiece are conducted,the effects of f on their modal parameters were analyzed by static knocking tests and different f turning experiments;The cutting force signal and acceleration signal of the cutting tool and the vibration displacement signal of the workpiece,the surface quality and the roughness of the workpiece in different f turning experiments are collected,which helps to explore the influence of different f on the change of the moving load and the power spectrum density of the cutter,study the effects of different f on the vibration displacement and the surface quality and roughness of the workpiece.It is found that the feed rate affects the vibration of the tool and the workpiece,the f affects the vibration frequency,the change of the moving load and the self power spectrum density of the tool,meanwhile it affects the modal parameters,the vibration displacement,the surface vibration and the surface roughness of the workpiece.And some f have a greater impact on these factors,which consistents with the moving load theory,that is,when the moving speed and the vibration frequency of the carrier satisfy a certain relation,it will cause the vibration of the carrier.This paper introduces the basic model and principle of the moving load.The cutting tool and the workpiece are analyzed,it's found that the feed speed affects the turning vibration,some f have a greater impact on the turning vibration,which is consistent with the moving load theory that the moving speed affects the vibration of the carrier.