The cutting of large thickness is not how high the wire frame can rise, how thick it can cut, and the selection of pulse width of wire cutting machine will be limited by the thickness. Subject to the restriction of discharge machining corrosion conditions, after a certain extent, the processing is very unstable until there is a current without discharge short circuit occurs. With the tear burn will soon break the wire, in the very unstable processing, the cutting surface will also form grooves, and the surface quality is seriously damaged. The slit is filled with extremely viscous corrosion, even almost powdery carbon black and corrosion particles.

Large thickness usually refers to more than 200mm steel, as for higher electrical conductivity, higher thermal conductivity or high temperature resistance of other materials can not reach 200mm, such as copper, tungsten carbide, pure tungsten, pure molybdenum, 70mm thick is very difficult.

First, the main problems caused by large thickness cutting are as follows:

1. Without the entry and exchange of enough water, the corrosion can not be removed in the gap, the insulation can not be restored, and the discharge can not be formed.

2. The filler in the gap diverts the energy of the pulse source in the form of resistance, so that sufficient breakdown voltage and individual pulse energy are lost between the wire and the workpiece.

3. Limited by the current carrying capacity of the molybdenum wire itself, it is impossible to have a larger pulse energy transferred to the gap.

4. The distance from the middle part of the slit to discharge the corrosion is too long, and the attenuated spark discharge has not formed enough explosive force and sewage power.

5. Material reasons, the possibility of impurities and internal stress in large thickness is greatly enhanced. The probability of local anomalies and deformation of the slit is also greater. The cutting impact is lost, but the possibility of short-circuit is increased.

Second, to solve the main contradiction of large thickness cutting, the following measures can be taken to alleviate or solve.

1. Increase the energy of a single pulse (the product of the voltage, current and pulse width of a single pulse is the energy of a single pulse). Increase the pulse interval, the purpose is to do not increase the average current carrying capacity of the molybdenum wire under the previous title, the ability to form spark discharge, the explosive force of the spark is enhanced.

2. Choose a coolant with higher dielectric coefficient, stronger recovery insulation ability, and stronger fluidity and resolution.

3. Greatly increase the pulse voltage, increase the discharge gap, and it is easier for water to enter and discharge.

4. Prepare the treatment of the material to be cut in advance, such as uniform organization by repeated forging, removing impurities, and internal stress of the material by annealing and effective treatment. The material stress can be fully released by removing large residual factors.

5. Improve the wire speed, more stable wire transport, so that the ability to carry water and resist short circuit is enhanced.

6. Artificially biased polyline feed or automatic feed into two back one, so that the gap is effectively expanded.

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