This article mainly discusses five-axis linkage CNC electrical discharge machining technology, focusing on several aspects such as electrical discharge forming technology, electromechanical composite machining technology, and low-speed wire EDM technology in five-axis five-linkage CNC systems. It is hoped that this article will provide some assistance for the future development of five-axis linkage CNC electrical discharge machining technology.
1. Five-axis five-linkage CNC electrical discharge machining technology
Four-axis CNC precision EDM machine tools can meet the needs of efficient and precise machining of complex molds, such as high-temperature alloys and titanium alloys, including integral turbine disks with blades. They are particularly suitable for critical manufacturing applications in power generation equipment, precision molds, aerospace, and many other fields, playing a vital role in advancing CNC technology. The machine used here is a FORM300 four-axis CNC precision EDM machine imported from Europe. The B-axis of the servo-controlled rotary table, with a positioning accuracy of ±5°, was imported from HIRSCHMANN in Germany. This allows for research on five-axis CNC precision EDM machining technology, which can then be conducted on the resulting five-axis CNC EDM machine tool.
The main performance parameters and technical indicators of the machine tool are as follows: (1) Dimensional accuracy (mm): ±0.002; (2) Optimal surface roughness (μm): Ra0.2; (3) Maximum electrode weight (kg): 50; (4) Maximum workpiece size (mm): 1200×800×350; (5) X, Y, Z working stroke (mm): 600×400×500.
In the forming and machining of precision and complex parts, five-axis five-linkage CNC EDM machine tools can demonstrate significant advantages, showcasing the excellent performance of machining tools. They are particularly suitable for the machining and processing of precision and complex parts in aerospace and other fields, such as crowned integral turbine disks, turbine disk compressor rotors, turbine casings, and aerospace engine turbine disks. They also have good results in processing special materials, including low-expansion alloys, alloy structural steels, heat-resistant alloys, titanium alloys, aluminum alloys, and other special materials.
2. Five-axis five-linkage CNC electrolytic mechanical composite machining technology
In five-axis, five-linkage CNC electrolytic-mechanical composite machining technology, the composite cathode with internal spraying function is a rotating tool that combines the advantages of mechanical grinding, electrolytic machining, and CNC. The composite cathode surface is selectively treated by plating or embedding diamond abrasive. The diamond abrasive helps maintain the electrolytic machining gap, provides insulation, and removes the anodic passivation film from the workpiece. During the machining process, the negative terminal of the DC pulse power supply is connected to the composite cathode, while the positive terminal is connected to the workpiece. Electrolyte is sprayed between the workpiece and the composite cathode. This allows for CNC operation, meeting the machining requirements of complex parts under the principle of electrolytic-mechanical grinding composite machining.
Based on the principles of electrolytic-mechanical grinding composite machining analyzed above, specific research can be conducted on related five-axis, five-linkage CNC electrolytic-mechanical composite machining tools. For five-axis, five-linkage CNC electrolytic-mechanical composite machining tools, different composite cathodes can be used to replace the polishing, grinding, cutting, boring and milling, and composite drilling processes. This machine tool system can perform roughing, finishing, and polishing on the same workpiece in a single setup. Its main characteristics are analyzed as follows: First, it can effectively handle various difficult-to-machine materials such as high-toughness, high-hardness, and high-wear-resistant metals. Second, complex shapes of parts can be machined using simple-shaped composite cathodes. Third, compared to electrical discharge machining (EDM) and mechanical grinding, this system has higher machining efficiency and higher machining accuracy than electrolytic machining. Fourth, the removal of workpiece allowance relies on the principle of electrochemical anodic dissolution, which has no impact on the surface metallographic structure and has relatively low macroscopic mechanical cutting force, enabling the machining of low-rigidity, thin-walled, narrow-groove, and narrow-slit parts. Fifth, the composite cathode tool experiences virtually no wear.
The traditional machining concepts have undergone tremendous changes in the characteristics of the aforementioned machine tool systems. For example, the hardening heat treatment process can be pre-planned, and then corresponding roughing, finishing, and polishing processes can be considered; removing a whole piece of material from the workpiece while essentially utilizing the whole piece of material can effectively improve production efficiency, improve machining accuracy, further eliminate heat treatment deformation, reduce energy consumption, and save resources, all of which are of great significance.
3. Five-axis, five-linkage CNC electrical discharge machining technology for low-speed wire EDM.
Three-dimensional complex ruled surface precision parts play an important role in special fields such as mold making, military industry, and aerospace in my country. They can solve corresponding precision, micro, and efficient cutting and processing problems. The FA20PSAdvance four-axis linkage precision CNC low-speed wire EDM machine tool was introduced from Mitsubishi Electric Corporation of Japan. In addition, the servo-controlled rotary table B-axis (positioning accuracy ±5°) was configured from HIRSCHMANN of Germany. This can form a corresponding five-axis linkage CNC EDM low-speed wire EDM machine tool, and can carry out related research on five-axis linkage precision CNC EDM low-speed wire EDM technology.
The main technical performance and index parameters of the equipment are as follows: (1) Dimensional accuracy (mm): ±0.002; (2) Optimal surface roughness (μm): Ra0.03; (3) Maximum taper (°): ±15; (4) Electrode wire diameter range (mm): 0.05～0.3; (5) Maximum workpiece weight (kg): 1500; (6) Maximum workpiece size (mm): 1050×800×295; (7) U, V working stroke (mm): ±75; (8) x, r, z working stroke (mm): 500×350×300.
In five-axis, five-linkage CNC EDM low-speed wire EDM machines, the main method used is to process the injection mold cavity of propellers. This method achieves good results, meets production requirements, and has gained recognition for plastic propeller products, thus maintaining China's leading position in mold processing.
4 Conclusion
First, the processing of complex parts within the overall structure of difficult-to-machine materials can be effectively solved using five-axis CNC electrical discharge machining (EDM). Furthermore, it provides an effective means for machining slender, thin-walled, and low-rigidity parts, which is beneficial for the forming and processing of precision and complex components in mold making, aerospace, and other fields. Second, five-axis CNC EDM and five-axis CNC electromechanical composite machining centers are essentially the same in terms of the objects they process. However, the processing efficiency of the five-axis CNC electromechanical composite machining center is often about 10 times that of EDM. Additionally, it can perform electrochemical composite polishing of parts. Third, the highly intensive and complex characteristics of special machining tools are embodied in the five-axis five-linkage CNC low-speed wire EDM machine, which represents an advanced level of EDM machine tools. It is mainly used for precise, fine, and efficient cutting of complex three-dimensional ruled surfaces, featuring good surface quality and high machining accuracy, playing a crucial role in the machining of precision parts in mold making, military, and aerospace fields.
