Causes and prevention methods of high-speed wire-cut EDM wire cutting process (2)

(2) The adjustment of the cutting preset feed rate has a great influence on the cutting speed, the machining accuracy and the surface quality. The preset feed speed is adjusted too fast, exceeding the possible erosion speed of the workpiece, frequent short-circuit phenomenon occurs, the cutting speed is slow, the surface roughness is also poor, and the upper and lower section slits are burnt yellow, and may even be broken; The feed rate is adjusted too slowly, which is far behind the erosion speed of the workpiece. The poles will be biased to open circuit, sometimes open and sometimes short-circuited. The surface of the machine is also light brown, and the upper and lower ends of the workpiece are also burnt. Therefore, the preset feed rate should be suitable, that is, the cutting speed of the workpiece is equivalent to the feed speed. Thus, the machined surface is thin and bright, the thread is uniform, the surface roughness is good, and the precision is high.

(3) Improper adjustment of the frequency conversion tracking is also an important cause of broken wire, because the tracking is too fast, it is easy to form a short circuit and the wire tension is increased to cause the broken wire. The actual adjustment can be judged by the stability of the ammeter pointer, and the more stable the pointer is, the better. If the pointer is not stable, try to make the pointer fluctuate in the direction of 0.

1.5 Factors of working fluid In the high-speed wire-cut EDM wire-cutting process, the working fluid is a medium for pulse discharge, which has a great influence on the processing. The working fluid generally requires certain insulation properties, good washing performance, good cooling performance and no pollution to the environment, and no harm to the human body. The configuration of the working fluid is also very important. When it is too thick or too light, it will cause broken wire. The concentration ratio of water and liquid is in the range of 1:10-1:20. When the cutting speed is high or the thickness of the workpiece is cut, the concentration is appropriately lower, so that the processing is relatively stable and the yarn is not easily broken. However, the working fluid concentration should not be too low, otherwise the working fluid insulation performance will be reduced, the electrical resistivity will be reduced, and the cooling capacity will be enhanced, thereby reducing the lubrication effect on the workpiece, which is not conducive to chip removal and easy to break. In order to ensure that the working fluid channel is non-blocking, the flow rate of the working fluid should also be properly controlled. Generally, when the cutting is completed, the workpiece is sagged under the action of the hydraulic fluid of the working fluid, the cutting portion is detached, and the electrode wire is easily pinched off. At this time, the working fluid should be kept at a certain pressure and flow rate, and the corrosive substances should be discharged in time to prevent the occurrence of broken wire. When cutting soft materials such as aluminum and copper, especially in the case where the cutting material is relatively thick, in order to improve the processing efficiency and surface finish, and to reduce the yarn breakage, some special cooling liquids can be used, which is also beneficial to environmental protection.

1.6 Factors for operation In the high-speed wire-cut EDM wire-cutting process, in order to efficiently process the workpieces that meet the requirements, there are certain requirements for the operators. The operator must correctly understand the technical requirements of the drawings. The working fluid should be replaced in time to maintain a certain degree of cleanliness, to ensure that the upper and lower nozzles are not blocked and the flow rate is appropriate. The wire is aligned vertically and the workpiece is clamped correctly. Reasonable selection of pulse power supply parameters, when the processing is unstable, it is necessary to adjust the frequency conversion feed rate in time. When switching the function keys, do not carry out during the processing, so as to avoid short circuit of the switch or cause the wire to burn and break the wire. When the cutting is completed, the cut portion will fall under the action of gravity, and the electrode wire is easily pinched off, and can be fixed in time by magnet adsorption, clamping plate clamping, etc., to avoid broken wire.

2 Conclusion

There are many factors affecting the broken wire of the electrode in the high-speed wire-cut wire-cutting process, and the influence of each factor is often interdependent and mutually restrictive. The above analysis and research on some phenomena of high-speed wire EDM wire cutting interrupted wire, and put forward corresponding preventive measures, this paper is based on long-term work experience and a lot of information, I believe that to improve the surface of the workpiece Quality and precision, and improve processing efficiency have certain reference.