Measures to avoid low frequency vibration of turning and milling compound CNC lathe
In the process of turning and milling compound CNC lathe processing, turning and milling compound CNC lathe sometimes will appear low frequency vibration, which will cause the workpiece surface vibration, rework rate, high scrap rate, at this time to pay attention to find out the specific reasons, and then take the corresponding elimination measures to ensure the normal work.
1. In the low-frequency vibration, the change of cutting force is mainly caused by the vibration in the Y direction, which makes F phase close to > F and produce vibration.
Measures: The larger the main deviation [**]ngle ([**]ngle R) of the tool is, the smaller the FY force is and the smaller the possibility of vibration. Therefore, the appropriate increase of the main tool [**]ngle, eliminate or reduce vibration, the appropriate increase of tool rake [**]ngle, can reduce FY force, thereby reducing vibration, the tool [**]ngle is too large or blade is too sharp, the tool is easy to bite into the workpiece, easy to produce vibration. When properly passivated, the tool face prevents the tool from "biting" the workpiece, thereby reducing or eliminating vibration.
2, chip processing process, when the chip is too fine, Y direction vibration will cause the change of cutting force. When the cutting part is wide and thin, the vibration in the Y direction will cause a sharp change in the cutting cross section area and cutting force. Therefore, the numerical control lathe in this case is very easy to produce vibration. For example, in longitudinal turning, the deeper the cut, the greater the feed, the smaller the protagonist, the wider and thinner the cutting section, the more prone to vibration.
Therefore, when selecting the rotation speed, it is necessary to avoid the medium speed region where the cutting force decreases with speed (the speed range is 30-50m/min when cutting carbon steel). [**]t the same time, reducing cutting force, increasing feed and reducing cutting depth are also helpful.
3, insufficiency of workpiece and tool holder system stiffness is the main reason for the low frequency vibration, the following measures can be taken to eliminate or reduce vibration: with three jaw or four jaw clamping workpiece as far as possible when the workpiece and the center of rotation on the center of rotation error of the spindle is small, avoid tilt and intermittent cutting CNC lathe workpiece or caused by uneven cutting vibration of the cutting force of cyclical changes.