The precision that can be achieved by precision machining is one of the important indicators to measure the level of manufacturing technology in a country, and with the continuous improvement of machining accuracy, the requirements of machined parts on the surrounding environment of the machine tool are getting higher and higher, except for the hydraulic pressure and air pressure in precision machining. In addition to the fluctuation of the working environment, the temperature, cleanliness and vibration of the working environment also have a great influence on the processing quality. In order to improve the surface accuracy of precision mechanical parts, multiple cutting techniques have appeared.
Multi-cutting technology is the fundamental method for wire EDM to improve the machining accuracy and surface quality of precision mechanical parts. Generally, the first cut is used to form, the second cut is used to improve accuracy, and the third cut or more is used to improve surface quality.
In the process of multiple cutting, the first cutting needs to use large pulse energy to obtain a higher cutting speed. At this time, the quality of the processed surface of the precision mechanical parts is to be cut multiple times, which first requires the machine tool table to have a high The geometric accuracy and movement accuracy of the wire, and secondly, the wire feeding system must ensure the constant and stability of the electrode wire in space. Of course, in order to achieve the purpose of stable multiple cutting, it is necessary to improve the high-frequency pulse power supply and conduct systematic research on the multiple cutting process. The motion accuracy of the worktable can be cut along the repeated offset trajectory, which is a guarantee for improving the processing accuracy of precision mechanical parts and improving the surface quality. The electrode wire has a certain rigidity. After passing through the positioning guide wheel, it actually presents an arc shape, and there is a deviation from the common tangent line of the upper and lower guide wheels. The magnitude of the deviation will change with the change of the electrode wire tension. In the actual processing of precision mechanical parts, because the wire electrode tension is in an unstable state, the wire feeding system must control the wire electrode tension. At the same time, when the electrode wire is positioned by the guide wheel, due to the semi-open positioning method of the guide wheel, the electrode wire is subjected to the action of the discharge explosive force during cutting, which causes the positioning state of the electrode wire to be different in all directions. Therefore, to ensure the electrode For the stability of the spatial position of the wire during processing, an electrode wire guide must be added to the wire walking system. A higher first cutting speed is a prerequisite for the practical application of multiple cuts. The average cutting speed and surface quality of multiple cuts are almost the same as the results of the first cut after reducing the discharge energy, although the precision of precision mechanical parts can be processed through multiple cuts. Correction. However, multiple cutting requires high quality of equipment and personnel, and the risk is also high. It is easy to cause wire breakage caused by the increase of discharge energy during the first cutting, or the workpiece is scrapped due to unstable cutting state during multiple cutting. Practice has proved that when using a composite working fluid with less oil content for cutting, the processing stability, cutting thickness ability, wire breakage rate, and surface roughness of the processed surface are greatly improved.
Post time: Jan-27-2021