JPS6320661B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an electric discharge machining apparatus, and particularly aims to eliminate errors in a mechanical system caused by heat with a simple structure.

Figure 1 shows the machining tank and table portion of a conventional electrical discharge machining device, where 1 is a column supporting the main shaft 2 of the electrical discharge machining device, 3 is an electrode, and 4 is a table 5.
6 is a machining fluid, and 7 is a machining tank in which the machining fluid 6 is stored and convected. Here, as shown in FIG. 1a, it is assumed that the electrode 3 and the workpiece 4 are fixed at a position emm eccentric with respect to the center line of the electrode 3 and the center line of the workpiece 5. When centering work is performed and electrical discharge machining is started in this state, all of the spark energy discharged between the electrode 3 and the workpiece 4 is absorbed by the surrounding machining fluid 6, and the machining fluid itself is gradually heated. For this reason, the machining fluid 6, which was initially at t°C, is heated and rises by △t°C to (t+Δt)°C, and there is a temperature difference between the machining fluid 6 and the temperature t°C of the table 5, which was at the same temperature. As a result, heat transfer occurs from the machining fluid 6 to the table 5 side. As a result, the top surface of the table 5 stretches, and the bottom surface does not stretch as much, so the first
The table 5 is deformed as shown in Figure b, and the workpiece 4 is positioned on an axis inclined at an angle θ° from the center of the table, resulting in e'mm. Generally, e' - e>0, and if electrical discharge machining proceeds in this state, the positional relationship with the electrode 3 centered at the beginning of the workpiece 4 will be distorted, making it impossible to perform straight machining, and Various problems arise such as machining not progressing due to electrical discharge,
Therefore, it was sometimes difficult to manufacture a satisfactory mold.

This invention was made to solve the above-mentioned problems, and the embodiment shown in FIG. in,
One end thereof communicates with the processing tank 7, and the other end is guided outside the processing tank 7. Reference numeral 5b denotes a baffle plate that obstructs the passage 5a in a meandering manner, and is composed of a plurality of ribs formed on the bottom surface of the table 5. 5d is the passage 5a
This is a watertight lid, which is fixed to the table 5 via a gasket 5c and forms the bottom surface of the table 5. 8 is a saddle for loading and guiding table 5, 9
1 is a bed on which the processing tank 7, table 5, saddle 8, etc. are loaded; 10 is a hood provided on the top of the spindle 2; 11 and 11' are holes and passages provided in the column 1; 12 is this passage 11' Piping connected to the fan cooler 13, 13a and 13b are fans and heat radiation tubes of the fan cooler, 14 is a machining fluid tank, 15 is a machining fluid supply pump, 17,
Reference numerals 18, 19, and 20 are pipes through which the processing fluid flows to the tank 14, pump 15, heat radiation tube 13b, electrode 3, and processing tank 7, respectively, and 21 connects the passage 5a and the pipe 20 via a valve 16. This is a connecting pipe.

Next, to explain the operation of this embodiment, the machining fluid 6
is supplied under pressure between the electrode 3 and the workpiece 4 by the pump 15, and in the process of electrical discharge machining of the workpiece 4 by the electrode 3, the machining fluid 6 supplied under pressure is supplied between the electrode 3 and the workpiece 4. Afterwards, it passes through the machining tank 7 while dissipating heat to the surrounding machining fluid, and returns to the tank 14 via the piping 20. For this reason, the temperature of the machining fluid in the machining tank 7 is inevitably higher than in other parts, but this machining fluid is pumped through the passage 5 which passes through the bottom side of the table 5 by opening the valve 16.
If the machining fluid 6 is also allowed to flow into the machining fluid 6 and join the piping 20 through the piping 21, the lower surface of the table 5 has a large surface area due to a large number of ribs or baffle plates 5b, so heat conduction from the machining fluid 6 is enhanced. As a result, the table 5 is heated evenly from both the upper and lower surfaces by the machining fluid. Therefore, the table 5 is evenly heated to substantially the same temperature as the machining liquid 6 in the machining tank 7, eliminating any temperature difference.

The relatively high temperature machining fluid returned to the tank 14 is
Heat is forcibly radiated while passing through the fan cooler 13, and all the heating energy absorbed in the processing tank 7 portion is radiated and removed.

Therefore, the temperature of the machining fluid 6 is controlled to be constant, and the table 5 is heated evenly from above and below, so it is possible to prevent bending due to the temperature difference between the top and bottom surfaces.
Therefore, the positional relationship between the electrode 3 and the workpiece 4 is maintained with high precision.

Furthermore, the air to the fan cooler 13 is passed through a passage 11' formed in the column 1 with a pipe 12 serving as an inlet.
Since the smoke is connected to and inhaled through the passage 11' and the hood 10 of the main shaft 2, exhaust fumes generated during processing can be disposed of at the same time, improving the working environment.

As described above, according to the present invention, a passage for circulating the machining fluid is provided inside the table for fixing the workpiece, and the machining fluid is drawn out of the machining tank by flowing through the passage. Since the machining fluid is guided to the fan cooler that cools the air at the top of the machining tank through the hollow columnar body of the column, it not only brings the upper and lower surfaces of the table into contact with the machining fluid at the same temperature, but also eliminates the smoke generated by machining. It can be removed effectively and helps improve the working environment.Furthermore, with a fan cooler for cooling the machining fluid,
Since the column itself can be cooled and adverse thermal effects on the entire electrical discharge machining apparatus caused by heat generated during machining can be prevented, an electrical discharge machining apparatus capable of high-precision machining can be provided.

[Brief explanation of the drawing]

Fig. 1a is a schematic cross-sectional view showing a machining tank in a conventional electric discharge machining device, Fig. 1b is an explanatory view illustrating its thermal change state, and Fig. 2 is a cross-sectional view of a main part showing an embodiment of the present invention. FIG. In addition, the same reference numerals in the figures indicate the same or equivalent parts, 1 is a column, 2 is a main shaft, 3 is an electrode, 4 is a workpiece, 5 is a table, 5a is a passage, 5b is a baffle plate such as a rib, and 6 is a baffle plate such as a rib. 7 is a processing tank, 10 is a hood, 13 is a fan cooler, and 14 is a tank.

Claims (1)

[Claims] 1 A machining tank having a machining fluid, a workpiece fixed to a table in the machining tank, an electrode for electrical discharge machining of the workpiece through the machining fluid, and a hollow columnar body that holds the electrode and a hollow columnar body. A column having a column, a passageway for circulating the machining fluid inside the table, a piping device for drawing out and circulating the machining fluid outside the machining tank, and a piping device provided midway through the piping device, and discharging the air in the upper part of the machining tank. An electrical discharge machining device characterized by comprising a fan cooler that cools the machining fluid through a hollow columnar body portion of the column.