Developement Of CNC Machine Tool For Drilling & Milling Composite Materials And Experimental Studies On Its Functions

Characterized by high specific strength, high specific modulus, its material property is devisable, and other excellent properties, composites have been widely used in aviation domain, aerospace field and other fields. However, it's one of the difficult-to-machine materials. Due to its mechanical property is markedly anisotropic, it's easy to produce delamination, avulsion, burr and other damages in composites machining process. Machining temperature is high, and the durability of the tool is low in composites machining process. At present, the gap between the domestic and foreign technology and equipment is huge in composite drilling and milling.In order to conduct researches on the technologies and equipments of non-defective drilling and milling composite materials, based on the National High Technology Research and Development Program of China and the National Natural Science Foundation of China Projects, a triaxial-simultaneous-control experimental CNC machine tool was developed for drilling, milling and end grinding composites, with auxiliary air cooling and ultrasonic vibration assisted machining functions.Main functional parameters of the experimental machine tool were determined through the analysis of the functions of experimental machine tool and the accuracy requirements of drilling and milling composite materials. According to the functional parameters, the schemes of general structure and functional units of the experimental machine tool were designed. Finite-element analyses of static structure, modal and harmonic response were conducted to validate the feasibility of the designed scheme of the experimental machine tool. The analyses results showed that the static and dynamic stiffness of the designed structure scheme of the experimental machine tool can satisfy the drilling and milling process requirements. In order to inspect the assembly and control accuracy of the experimental machine tool, its geometer precision, position precision and the motion precision were detected and debugged. The results indicated that the precision of the experimental machine tool is good, which met the design requirement. Tests of drilling, milling and end grinding composites were conducted in the experimental machine tool to verify its machining functions and precisions. The results demonstrated that precision of the holes and surfaces after machining are good, which satisfied the operating requirements. Besides, the temperature of the cutting area was significantly reduced and the machining quality was notably improved by adopting air cooling in hole-making process. And the durability of the tools was efficiently improved by using ultrasonic vibration assisted in milling & grinding composites.Experimental studies of technologies of non-defective drilling and milling composite materials can be conducted in the experimental machine tool, which can provide technical support for the development of special-purpose CNC machine tools for machining composites structures.