The modern aviation industry uses a large number of integrated thin-walled structural parts. Its main structure consists of side walls and webs. Because of its simple structure, large volume and large processing capacity. Due to its relatively low rigidity, processing technology is poor. Under the influence of cutting force, cutting heat, cutting vibration and other factors, the deformation is easy to deal with, the machining accuracy is difficult to control, and the machining efficiency is improved. Processing deformation and processing efficiency are important constraints for processing thin-walled structures. Therefore, due to the special structure of the milling cutter and the characteristics of the machine tool, an effective milling method is proposed, which brings a new breakthrough in the processing technology of thin-walled parts.
1. Optimize high-speed machining tool path
The key to machining thin-walled parts with high-speed cutting technology is the stability of the cutting process. Many experimental studies have shown that the thinner the wall of the part, the lower the rigidity of the part. Machining deformation becomes larger, it is easy to produce chattering, which affects the processing quality and processing efficiency of parts. The tool path optimization program to maximize the overall stiffness of the part. The idea is to use the original part of the part as a support for the milling part as much as possible during the cutting process to make the cutting process more rigid.
Sidewall milling uses large radial cutting depths and small axial cuts within cutting tolerances. Maximize the overall stiffness of the part. In order to prevent the tool from interfering with the side wall, a cutting tool with a special shape can be selected or designed to reduce tool deformation and interference to the workpiece.
Effectively mill deeper cavities and side walls. Based on the research of dynamic milling, a tool with a reasonable large aspect ratio can effectively solve this problem. The natural frequency of the machine tool and workpiece processing system is adjusted by adjusting the tool protrusion under higher spindle speed and output conditions. The stability of the lobe effect can be used to avoid cutting vibration and the possibility of milling deep cavities and sidewalls with deep axial cutting depth. Experimental results show that this method has a larger metal removal rate and higher surface integrity.
2. Double-spindle processing to control deformation
It is difficult to machine thin-walled parts with high precision with an end mill, because the side wall of the workpiece is deformed by the “knife” due to the milling force. The traditional low feed rate and low depth of cut can meet constant machining accuracy, but the efficiency is relatively low. The parallel dual-spindle solution can effectively solve the deformation problem of single-spindle machining parts. This method requires the use of two end mills with the same radius of gyration, effective length, and helix angle, each rotating to the left and right (see Figure 3). In the parallel two-axis machining method, the force acting on both sides of the workpiece is a symmetrical force, so the machining deformation of the workpiece can be basically eliminated except for the machining error caused by the small deformation of the tool.
Thin-walled parts are processed by parallel dual-spindles, effectively controlling the deformation of thin-walled parts. It greatly improves the processing accuracy and processing efficiency of the parts, and can be applied to the processing of simple-shaped side walls. However, the limitation of this method is that it can only handle the side walls of simple thin-walled parts, requires the spacing of the machine’s dual spindles, and is complex in structure and not suitable for general use.
Link to this article：High-speed milling of side walls of thin-walled structural parts
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