JPH0125653B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electric discharge machining apparatus, particularly an electric discharge machining apparatus that performs electric discharge machining on a workpiece in a machining liquid containing an organic compound mixed with water at a proportion that does not burn it.

Generally, electrical discharge machining equipment that uses machining fluid has been used to maintain the resistivity value of the machining fluid above a certain value, so the resistivity value has been improved by using an ion exchange tank. However, it is known that the life of the ion exchange resin in the ion exchange tank is significantly reduced due to adsorption of impurities in the processing fluid.
For this reason, filters made of paper, cloth, etc. have been used in combination to remove impurities.

A conventional device of this type includes a machining tank 1 in which electrical discharge machining is performed in a machining fluid 10 inside as shown in FIG.
2, and a machining fluid circulation device 16 that circulates the machining fluid 10 in the machining tank 12 while maintaining it at a constant resistivity value in an ion exchange tank 14. In the machining liquid 10 of the machining tank 12, an electrode 18 and a workpiece 20 are placed facing each other. The machining fluid circulation device 16 includes a drain fluid tank 22 into which machining fluid 10 containing sludge is delivered after electrical discharge machining is performed in the machining tank 12.
and a supply liquid tank 24 that supplies the machining fluid 10 to the machining tank 12. Machining fluid 10 in drain tank 22
is sent by a pressure pump 26 to a filter 28 made of paper, cloth, etc., and then divided and a portion is sent to the supply liquid tank 24. The remainder that is diverted and sent to the supply liquid tank 24 is sent to the ion exchange tank 14 via an electromagnetic valve 30, and then similarly sent to the supply liquid tank 24.
sent to. The machining fluid 10 in the supply fluid tank 24 is sent to the machining tank 12 by a pressure pump 32, and a part of the machining fluid 10 is diverted and passed through a resistivity measuring device 34 to measure its resistivity value. In the figure, reference numeral 36 denotes a control box that opens and closes the electromagnetic valve 30 and adjusts the flow rate of the machining fluid 10 sent to the ion exchange tank 14 according to the resistivity value measured by the resistivity measuring device 34. Further, numerals 38 and 40 in the figure are valves that respectively adjust the flow rate of the machining fluid 10.

Next, we will explain the operation of this conventional device.
After performing electrical discharge machining in the machining tank 12, the machining fluid 10 containing sludge is sent to the drain tank 22. In this drain tank 22, heavy sludge is precipitated, and the processing liquid 10 containing light sludge is sent to a filter 28 by a pressure pump 26 and filtered. This filtered machining fluid 10 is supplied to the supply fluid tank 24.
The liquid is further circulated by the pressure pump 32 to the processing tank 12 through a valve 38 for adjusting the flow rate. Further, a part of the machining fluid 10 sent from the supply fluid tank 24 to the machining tank 12 is diverted, and the resistivity value is measured by the resistivity measuring device 34, and this value is set as a value specified in advance in the control box 36. In the following cases, the electromagnetic valve 30 is opened, a part of the machining fluid 10 sent from the filter 28 to the supply liquid tank 24 is passed through the ion exchange tank 14 to increase the specific resistance value, and the machining fluid 10 in the supply liquid tank 24 is The entire resistivity value is maintained at the set value and the material is fed into the processing tank 12.

However, in order to prevent filter clogging, the filters used in this type of machining fluid circulation system are generally designed so that impurities of 2 to 1 μm or less are not filtered out. It remains in the machining fluid 10 as it is, and the machining fluid 10
In addition to reducing performance, the ion exchange tank 14
It was also adsorbed to the ion-exchange resin inside, significantly shortening the life of the resin.

The present invention was made in view of the conventional problems mentioned above, and its purpose is to constantly maintain the performance of the processing fluid, extend the life of the ion exchange resin, reduce running costs, and improve processability. An object of the present invention is to provide an electrical discharge machining apparatus that has the following features.

In order to achieve the above object, the present invention provides a machining tank in which electrical discharge machining is performed in a machining fluid inside, and a machining fluid in which the machining fluid in the machining tank is circulated while being maintained at a constant resistivity value in an ion exchange tank. The electrical discharge machining apparatus comprises a circulation device, and is characterized in that an activated carbon filtration tank is provided in the machining fluid circulation device.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

The present invention is shown in FIG. 2, and the same members as in FIG. 1 are given the same reference numerals and their explanations will be omitted.

In the machining fluid 10 that has passed through the filter 28,
The liquid that is not directly sent to the supply liquid tank 24 is sent to the ion exchange tank 14 via a solenoid valve 30, but in the present invention, an internal An activated carbon filtration tank 42 containing activated carbon and a filtration determination device 44 are provided. According to the embodiment, this filtration determination device 44 is formed using a transparent glass pipe 48 on which a determination line 46 of varying thickness is drawn on the opposite side of the viewing direction.

Next, the operation of the apparatus according to the present invention will be described. After electrical discharge machining is performed in the machining tank 12, the machining fluid 10 containing sludge is sent to the drain tank 22. The heavy sludge is precipitated in the drain tank 22, and the processing liquid 10 containing light sludge is sent to the filter 28 by the pressure pump 26.
The processing liquid 10 containing 1 μm of sludge is filtered. This filtered machining fluid 10 is supplied to the supply fluid tank 2
4, and is further circulated by a pressure pump 32 to the processing tank 12 through a fluid control valve 38. Further, a part of the machining fluid 10 sent from the supply fluid tank 24 to the machining tank 12 is diverted, and the resistivity value is measured by the resistivity measuring device 34, and this value is set as a value specified in advance in the control box 36. In the following cases, the electromagnetic valve 30 is opened and a part of the processing fluid 10 sent from the filter 28 to the supply fluid tank 24 is passed through the activated carbon filtration tank 42 and the ion exchange tank 14 in order to remove 2 to 1 μm of sludge. At the same time, the specific resistance value is increased to maintain the specific resistance value of the entire machining fluid 10 in the supply fluid tank 24 at the set value, and the machining fluid 10 is fed into the machining tank 12. Further, since the machining fluid 10 from the activated carbon filtration tank 42 passes through the filtration determination device 44, the lifespan of the activated carbon can be determined.

In the present invention, since the activated carbon filtration tank 42 is provided in the machining fluid circulation device 16, it is possible to adsorb and remove sludge and impurities of 2 to 1 μm or less, which were conventionally considered impossible to remove. For this reason, the machining fluid 10 obtained from the machining fluid circulation device 16 contains very few pigment components, etc., and due to the decrease in carbon powder, etc., when this is circulated to the machining tank 12, there is no adverse effect on electrical discharge machining. do not have.

Furthermore, since trace amounts of organic matter such as pigment components, sludge, and impurities in the processing fluid 10 are removed to a high degree, sludge and the like are not adsorbed to the ion exchange resin in the ion exchange tank 14, and the ion exchange resin has a long lifespan. Extension and performance can be maintained.

Specifically, data has been obtained that the addition of the activated carbon tank 42 of the present invention extends the life of the ion exchange resin by about 1.3 to 1.4 times. That is, using the ion exchange resin 51, the specific resistance measuring device 3
When the specific resistance of the machining fluid 10 is controlled to be 10×10 ⁴ Ωm and the passage to the activated carbon filtration tank 42 and the ion exchange tank 14 is controlled according to 4, the resistivity of the machining fluid 10 which was initially 11×10 ⁴ Ωm
The processing amount (corresponding to the processing period) of the workpiece until the specific resistance of the workpiece becomes 8×10 ⁴ Ωm or less was 7 kg without the activated carbon filtration tank 42, but with the activated carbon filtration layer 42 In some cases, it grew to about 10kg.

As described above, by providing the activated carbon filtration tank 42, the amount of sludge etc. adhering to the ion exchange resin can be greatly reduced, and the effect that the original ability of the ion exchange resin can be fully exhibited is obtained. It will be done.

The fact that the ability of the ion exchange resin can be fully demonstrated means that the specific resistance value of the circulating machining fluid can be reliably maintained at a certain value or higher.
As a result, accuracy in electrical discharge machining can be improved.

The activated carbon filtration tank 42 may be installed in any position as long as it can remove 2 to 1 μm of sludge, but it may be installed in front of the ion exchange tank 14 as in the embodiment, and the activated carbon filtration tank 42 may be installed in front of the ion exchange tank 14 to filter the machining fluid 10 that has passed through the filter 28. Forming the activated carbon so that only a part of it is fed into it not only has the effect of extending the life of the ion exchange resin, but also extends the life of the activated carbon compared to when it is installed in series with the processing fluid circulation path, resulting in a long-term Can be used.

Furthermore, if a filtration determination device 44 is provided after the activated carbon filtration tank 42, the lifespan of the activated carbon itself can be determined by determining the filtration state of the activated carbon, and it can be replaced before performance deterioration occurs. There are no accidents such as damage to the resin due to deterioration of the activated carbon.

Although the filtration determination device 44 can be constructed electrically by measuring the amount of light passing through it, it can also be formed using a transparent glass pipe 48 with a determination line 46 of varying thickness drawn on the opposite side of the viewing direction. This not only eliminates running costs, but also prevents breakdowns.

It goes without saying that the present invention can be applied to a machining fluid supply device for a wire-cut electrical discharge machine.

As described above, the present invention greatly contributes to maintaining the performance of machining fluids, extending the life of ion exchange resins, and maintaining performance.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a conventional device, and FIG. 2 is a system diagram of the device of the present invention. The same members in each figure are given the same symbols, 10 is the processing fluid, 12 is the processing tank, 14 is the ion exchange tank, 16
42 is an activated carbon filtration tank, 44 is a filtration determination device, 46 is a determination line, and 48 is a transparent glass pipe.

Claims (1)

[Scope of Claims] 1. A machining tank that performs electrical discharge machining in a machining fluid inside the machining tank, and a machining fluid circulation device that circulates the machining fluid in the machining tank while maintaining a constant resistivity value in an ion exchange tank. What is claimed is: 1. An electrical discharge machining apparatus comprising: an activated carbon filtration tank provided in a machining fluid circulation device. 2. An electrical discharge machining device according to claim 1, characterized in that an activated carbon filtration tank is provided in front of the ion exchange tank.