Power circuit and pulse power supply system for wire cutting machines

Abstract

The invention relates to the technical field of wire cutting, in particular to a power circuit and a pulse power supply system for wire cutting machines which can improve the cutting quality of work pieces. The power circuit for wire cutting machines is characterized by comprising a first power supply, a first set of integrated power devices, a second set of integrated power devices, a third set of integrated power devices and a fourth set of integrated power devices, wherein the first set of integrated power devices, the second set of integrated power devices, the third set of integrated power devices and the fourth set of integrated power devices are provided with more than one power device, and the power devices are MOS transistors or IGBT transistors.

Description

Technical field: [0001] The invention relates to the technical field of wire cutting, in particular to a power circuit and a pulse power supply system for a wire cutting machine that can effectively improve the cutting quality of workpieces. Background technique: [0002] The electric spark cutting machine belongs to the field of electric processing technology. It uses a continuously moving thin metal wire as the electrode 1 to conduct pulse electric spark discharge on the conductive workpiece (as the electrode 2), and uses the high voltage between the two electrodes to break down the processing medium. Realize the erosion, cutting and shaping of the processed workpiece. [0003] In the actual application process, the thin metal wire and the conductive workpiece are respectively connected to the positive pole and the negative pole of the power supply. When the voltage reaches a certain threshold, the air gap is broken down and is in a low resistance state. At this time, it i...

AI Technical Summary

Problems solved by technology

The damage mode is that if the isolation of the two power supplies fails, the ground will be shared. If any switch tube of T5-Tn on the POWER2 power supply is turned on, it will be connected to POWER1 through the body diode on T1, and the two power supplies will be short-circuited; the two power supplies have been described above. One of the power supply voltages is 50-200V, and the other is 200V-400V, unless it works at a point of 200V where the voltage is completely equal; (2) After the above analysis, it is easy to analyze that when T1 and T3 are turned on, the workpiece is under positive pressure, When the electrode wire breaks down and works under back pressure, because the internal resistance of the mosfet tube is very small, the internal resistance of T3 is only tens of milliohms, and the two power supply grounds are also common ground at this time. If the circuit wants to work normally, T1 and T3 must be turned off , end the breakdown voltage, and then the right circuit can work. At this time, the breakdown state must be affected, which makes the circuit work in a dilemma. The right circuit works late, the breakdown state disappears, and the two work early. Once there is overlap in the working sequence, two power supplies will inevitably be short-circuited, which is very difficult in sequence control; especially in the patent document, it is clearly required that the breakdown voltage is lower than the cutting voltage

Among them, the patent requires Figure 3, which is the figure 1 When R31 is connected in series between the electrode wires, this phenomenon is most obvious, and it is most likely to burn one of the power supplies. The resistance in other positions is slightly better due to resistance current limiting, but mutual discharge between the two power supplies is still a very big hidden danger. Especially when the current-limiting resistance is small, such as taking a resistance of 10 ohms, the maximum difference between the two power supplies is 350V, and the maximum current will be 35A. Usually, ordinary power supplies cannot absorb current and work for a long time.

(3) After actual test analysis, the breakdown voltage is usually high and the cutting voltage is low. This is mainly because there is cutting fluid between the workpiece and the electrode wire when no discharge occurs, and ions are generated after breakdown through high voltage. , the insulation between the workpiece and the electrode wire is lost, the resistance is reduced, and low-voltage high-current cutting is enough, but this patent uses low-voltage breakdown, high-voltage high-current cutting, which is an invalid solution, and high-voltage high-current cutting does not use any Current-limiting measures, if the power of the power supply is large enough, the current will be very large, and the electrode wire will be blown, and the high-voltage and high-current circuit can only give one-way pulse work

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