The process damping effect in milling of titanium alloy is analyzed and verified by experiment. Titanium alloy is a typical hard-to-machine material commonly used in aviation. Its large cutting force per unit area is prone to chatter, deterioration of surface quality, and damage to tools during processing. The chatter of titanium alloy cutting is an important issue that restricts the efficiency and quality of aviation manufacturing. The process damping effect comes from the ploughing effect caused by the interference between the flank face and the vibration of the workpiece surface. The implicit Runge-Kutta method is used to calculate the intrusive area and resistance caused by the interference in the milling of typical titanium alloy materials. Non-linear model. The calculation results show that, compared with the traditional linear dynamic model that does not consider process damping, the limit cutting depth in the low-speed region of the nonlinear model can be significantly improved; the experimental results show that the model can predict the stability limit of the low-speed region more accurately , Provide an important reference for the selection of processing parameters. Keywords: milling; chatter; titanium alloy; process damping; ploughing effect
Titanium alloy has been widely used in the aviation manufacturing industry. It has excellent comprehensive properties such as high specific strength, small density, strong heat resistance and low temperature resistance. Using it to manufacture aircraft parts can not only extend the life of the aircraft, but also reduce weight. , Reduce fuel consumption, thereby greatly improving its flight performance.
However, titanium alloy is also a typical difficult-to-machine material, with poor thermal conductivity, high chemical activity, severe work hardening, short tool life, and due to large unit cutting force, chatter is prone to occur during machining, and chatter is left for the workpiece The oblique chatter marks often need to be removed by manual honing, which affects the processing efficiency, seriously leads to the scrap of the workpiece, and even destroys the tool. The chatter problem of titanium alloy processing is a major bottleneck restricting the quality and efficiency of aviation manufacturing.
The method of controlling flutter can generally be attributed to increasing system damping. Cutting system damping can be divided into machine tool structural damping and damping caused by the interference between the tool flank and the workpiece surface, also known as process damping. Modeling and calibration of process damping has been a research hotspot in the international academic community in recent years. Canadian famous scholar Altintas once listed it as an unsolved research difficulty in cutting chatter.
At present, , the international research on process damping mainly focused on turning. For milling process damping, there is still a lack of a perfect dynamic analysis model. It has many degrees of freedom, force analysis requires coordinate conversion, and there is a time-varying coefficient in the cutting force equation. It is much more difficult to describe the invasion area and process resistance than turning. However, no domestic scholars have conducted in-depth research on process damping. In the current existing literature, the cutting stability analysis uses a more traditional linear model . Without considering process damping, this model will produce a large amount in the low speed region. error. For titanium alloy processing, in order to ensure the life of the tool, the cutting speed is generally low. If the conventional linear model is also used at this time, the predicted limit depth of cut is far lower than the actual limit depth of cut, which will inevitably affect the processing efficiency.
In view of this problem, this paper establishes a milling dynamics model that considers process damping, and uses the implicit fourth-order Runge-Kutta method to calculate the intrusion area and interference resistance of the vibration undulation of the tool flank and the workpiece during processing of typical titanium alloy materials. Draw the stability limit graph. Finally, it is concluded in combination with the experiment that the nonlinear model built in this paper can predict the stability limit of the low speed region more accurately, which provides a reference for the selection of titanium alloy processing parameters.
The flutter problem in the milling of titanium alloy materials is a major bottleneck restricting the efficiency of aviation manufacturing processing. In order to ensure the life of the tool, the titanium alloy material is basically cut at a relatively low speed. At this time, if the stability limit is very low according to the traditional linear model, the cutting depth is selected according to the linear model, which will be very detrimental to the processing efficiency. In this paper, a nonlinear milling dynamic model considering process damping is established to calculate the intrusive area formed by the ploughing effect and process resistance. The critical depth of cut is calculated by the time-domain simulation method. The experimental results show that the nonlinear calculation model proposed in this paper, which includes the process damping, can predict the stability limit of the titanium alloy in the low-speed region more accurately. This provides a necessary reference for the selection of parameters at normal working speeds when machining titanium alloys.
