JPS6242733B2 - - 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, in electric discharge machining equipment that uses machining fluid, the concentration of the machining fluid being circulated changes as machining is performed.
This has caused a decline in machining performance or machining accuracy. Therefore, in this type of equipment, a processing fluid concentration measuring device is attached to the processing fluid circulation device.
The measurement results of this concentration measuring device have been appropriately displayed on a display device to indicate whether replenishment is necessary or not, as well as the type and amount of replenisher. This type of conventional equipment includes a machining tank 12 in which electrical discharge machining is performed in a machining fluid 10 made of a solution of water and an organic compound, as shown in FIG. filter 14
and a machining fluid circulation device 20 that circulates the machining fluid 10 by disposing an ion exchange tank 18 for improving the specific resistance value of the machining fluid 10 in the middle thereof. In the machining fluid 10 of the machining tank 12, an electrode 22 and a workpiece 24 are placed facing each other. The machining fluid circulation device 20 includes a drain fluid tank 26 to which machining fluid 10 containing sludge that has been subjected to electrical discharge machining in the machining tank 12 is fed, and a supply fluid tank 28 to supply the machining fluid 10 to the machining tank 12. have. The processing fluid 10 in the drain tank 26 is sent by a pressure pump 30 to a filter 14 made of paper, cloth, etc., and then divided and a portion is sent to the supply fluid tank 28 . The remainder that has been separated and sent to the supply liquid tank 28 is sent to the ion exchange tank 18 via an electromagnetic valve 32, and then similarly sent to the supply liquid tank 28. Processing liquid 10 in supply liquid tank 28
is sent to the processing tank 12 by the pressure pump 34,
A part of the flow is diverted and passed through a resistivity measuring device 36 to measure the resistivity value. A chemical feeder 38 is separately installed in the supply liquid tank 28 in order to keep the concentration of organic compounds in the processing liquid 10 constant. An electromagnetic valve 40 provided at the outlet of the chemical feeder 38 is opened and closed, and the insufficient organic compound is supplied into the supply liquid tank 28 from the separately placed chemical supply device 38 via the electromagnetic valve 40. Further, a concentration measuring device 42 is provided in the supply liquid tank 28,
The organic compound concentration of the processing liquid 10 is measured by this measuring device 4.
Measured at 2. 44 in the figure is the resistivity measuring device 3
Based on the resistivity value measured in step 6, the electromagnetic valve 32
The flow rate of the processing liquid 10 sent to the ion exchange tank 18 is adjusted by opening and closing the electromagnetic valve 40 according to the organic compound concentration of the processing liquid measured by the concentration measuring device 42.
This is a control box that adjusts the concentration of organic compounds by opening and closing. Next, this prior art will be explained. As a result of electrical discharge machining, the machining fluid 10 containing sludge is sent to the drain tank 26. In this drain tank 26, the heavy sludge is precipitated, and the machining fluid 10 containing light sludge is sent to the filter 14 by the pressure pump 30, where it is filtered as the machining fluid 10 containing 2 to 1 micron sludge. Ru. This filtered machining fluid 10 is sent to the supply fluid tank 28 and further circulated to the machining tank 12 by the pressure pump 34. Further, a part of the machining fluid 10 sent from the supply fluid tank 28 to the machining tank 12 is diverted, and a resistivity value is measured by a resistivity measuring device 36, and this value is set as a value preset in the control box 44. In the following cases, the electromagnetic valve 32 is opened and a part of the machining fluid 10 sent from the filter 14 to the supply fluid tank 28 is passed through the ion exchange tank 18 to remove 2 to 1 μm of sludge and to adjust the specific resistance value. The specific resistance value of the machining fluid 10 as a whole in the supply fluid tank 28 is maintained at the set value, and the machining fluid 10 is fed into the machining tank 12. Similarly, the organic compound concentration of the processing fluid 10 is measured by a concentration measuring device 42 provided in the supply fluid tank 28, and if this value is less than a value preset in the control box 44, the electromagnetic valve 40 is opened. ,
The insufficient organic compound is supplied from the chemical supply device 38 into the supply liquid tank 28, and the organic compound concentration of the processing liquid is kept constant. However, although this type of machining fluid circulation device automates the measurement and supply of the organic compound concentration of the machining fluid 10, it has the disadvantage that the electrical discharge machining device itself becomes complicated and is therefore expensive. . The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide electrical discharge machining that can maintain the organic compound concentration of machining fluid in a saturated state and perform stable electrical discharge machining with a simple structure. The goal is to provide equipment. 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 consisting of a solution of water and an organic compound, a filter that removes sludge from the machining fluid, and a machining fluid from the filter. In an electrical discharge machining apparatus that has a supply liquid tank that stores and resupplies the machining fluid to the machining tank, and a machining fluid circulation device that has an ion exchange tank that improves the specific resistance value in the middle, the supply liquid tank has a machining fluid It is characterized by being equipped with a chemical supply device that maintains the concentration of organic compounds in the liquid in a saturated state. Preferred embodiments of the present invention will be described below based on the drawings. FIG. 2 shows a preferred embodiment of the electrical discharge machining apparatus according to the present invention, and in the figure, the same members as those in the conventional example described above are given the same reference numerals, and the explanation thereof will be omitted. A chemical feeder 46 is provided at the inlet of the supply liquid tank 28 into which the machining liquid 10 flows from the filter 14. It contains organic compounds, such as sucrose. Therefore, the machining fluid 10 from which sludge has been removed by the filter 14 dissolves the sucrose in the chemical supply device 46 and is supplied into the supply fluid tank 28, so that the machining fluid 10 in the supply fluid tank 28 is The sucrose concentration is always saturated. Table 1 shows the relationship between processing liquid temperature and sucrose solubility.

[Table] As is clear from this table, the solubility of sucrose is little affected by temperature, so processing performance is not affected even if the concentration of sucrose is not controlled. Therefore, in the apparatus of the present invention, the machining fluid can always be maintained in a saturated state corresponding to the temperature, so that stable electric discharge machining can be performed. As described above, according to the present invention, a simple chemical feeder for maintaining the organic compound concentration of the machining fluid in a saturated state is provided at the inlet of the supply liquid tank into which the machining fluid flows from the filter, thereby simplifying the electric discharge machining apparatus. This makes it easy to handle, and the device can be manufactured at low cost. Of course, in the present invention, since the organic compound concentration of the machining fluid is maintained in a saturated state, stable electric discharge machining can be performed as in the conventional method. Although this example describes the case where a chemical feeder is installed in the supply liquid tank, the same effect can be obtained by directly supplying the chemical, i.e., a solid organic compound such as sucrose, into the supply liquid tank. can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a conventional electric discharge machining apparatus, and FIG. 2 is an explanatory diagram showing a preferred embodiment of the electric discharge machining apparatus according to the present invention. In the figure, 10 is a machining fluid;
12 is a processing tank, 14 is a filter, 18 is an ion exchange tank, 20 is a processing fluid circulation device, and 46 is a chemical supply device. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (1)

[Claims] 1 A machining tank that performs electrical discharge machining in a machining fluid made of a solution of water and organic compounds, a filter that removes sludge from the machining fluid, and a machining fluid that stores the machining fluid from the filter and supplies the machining fluid to the machining tank again. a supply liquid tank;
In an electric discharge machining apparatus having a machining fluid circulation device in which an ion exchange tank for improving a resistivity value is disposed in the middle thereof, the supply fluid tank is provided with a chemical feeder for maintaining an organic compound concentration of the machining fluid in a saturated state. An electrical discharge machining device characterized by: