JPS60259334A - Electric discharge machining apparatus - Google Patents

Abstract

PURPOSE:To restrain a positional shift between an electrode and a workpiece due to a difference in thermal deformation amount between a spindle and a column, by feeding always external air to a spindle slider for vertical feed, from a ventilating fan. CONSTITUTION:When a workpiece is subjected to electric discharge machining by generating electric discharge between an electrode and a workpiece in machining liquid within a machining tank, heat due to machining energy is transmitted to a spindle 4 through the electrode. However, a ventilating fan 12 fitted in the spindle 4 always feeds external air to the inside of the spindle 4 and is discharged through a ventilating port 13. Further, a ball-and-screw shaft 14 for driving the spindle 4 is arranged therearound with a dust cover 15. Accordingly, no temperature difference is generated between the spindle 4 and the column 9. Therefore, the amounts of thermal deformations in the spindle 4 and the column 9 are made equal to each other, thereby substantially no relative positional shift in the vertical direction is brought about between the electrode and the workpiece.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to electrical discharge machining equipment, and in particular to positional deviation between a workpiece and an electrode caused by changes in machining energy or environmental conditions. This invention relates to an electrical discharge machining device that prevents the occurrence of damage and enables precision machining.

[Prior art]

A conventional device of this type is shown in FIG.

In the figure, (1) is the machining tank, and (2) is the machining fluid.

(3) is the electrode, (4) is the main shaft that feeds the electrode (3) in the vertical direction, (5) is the workpiece, and (6) is the processing tank (1
) and workpiece (5)? Move the table to be attached in the X direction indicated by the arrow. Further, (7) is a saddle, and the table (6) moves in the Y direction shown by the full arrow.

(8) is a spatula I-'' that slides and holds the main shaft (4), (
9) is the column that supports the head (8), and the column (9) is installed and the bed that supports this.

Next, the operation will be explained. In the machining fluid in the machining tank (1), discharge energy is supplied between the electrode (3) and the workpiece (5) from a machining power source (not shown), and an electric discharge is generated, causing the workpiece (5) to electrical discharge machining is performed. In this case, the temperature of the electrode (3) and machining fluid (2) rises due to the discharge energy, and this amount of heat is absorbed by the main shaft (
4), and the temperature of the main shaft (4) increases.

The main shaft (4) is connected to the head (
8), the amount of heat from the spindle (4) is difficult to be transferred to the head (8) and column (9).
4) and the column (9). on the other hand,
When performing electric discharge machining in an environment with large changes in room temperature, the column (9) is exposed to the outside air, while the main shaft (4)
) is held inside the spatula y (s), so it is difficult for it to come into direct contact with the outside air, so a temperature difference of 2 to 5 degrees Celsius occurs between the main shaft (4) and the column (9) due to changes in room temperature.

FIG. 6 is an Ici diagram showing all the actual measurement results of room temperature and temperature changes of the spindle (4) and column (9) under the usage environment of a general electrical discharge machine.

Since the conventional electric discharge machining apparatus is configured as described above, as the workpiece (5) is subjected to electric discharge machining, the temperature between the spindle (4) and the column (9) increases due to machining heat or changes in room temperature. Due to the difference, the main shaft (4) and column (9)
There is a difference in the amount of thermal deformation (thermal expansion) in the vertical direction between the t in the machining depth direction? This was the cause of deterioration.

Figure 7 shows the electrode (3) and workpiece (
5) is a diagram showing the results of actual measurement of changes in the relative positional deviation amount in the vertical direction.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and a ventilation fan is installed on the main shaft (4) where a temperature difference occurs with respect to the column (9) Ic.
), the temperature difference between the column (9) and the spindle (4) is minimized, and the vertical gap between the electrode (3) and the workpiece (5) is The present invention provides an electric discharge machining apparatus that performs highly accurate machining with minimal directional positional deviation.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (1) is the tj' processing tank, and (2) is the processing fluid.

(3) is the electrode, (4) is the main shaft, and (4b) is the electrode clamp device.

(5) is the workpiece, (6) is the X table, (7) ldy
table.

(8) is the head, (9) is the column, α0 is the bed, Qη
is the heat dissipation from the processing tank, (6) is the main shaft ventilation fan installed at the bottom of the main shaft, and Ql is the ventilation opening provided in the main shaft (4).

FIG. 2 is a sectional view showing the internal structure of the main shaft (4).

In the figure, ◇41 is the main shaft drive ball screw, (to) is the dust cover that covers the main shaft ball screw 04, and ◇ is the main shaft drive mode.

Next, the operation will be explained. In Figures 1 and 2, an electric discharge is generated between the electrode (3) and the workpiece (5) in the machining fluid (2) in the machining tank (1), and the workpiece (5) is When electrical discharge machining is performed, heat generated by machining energy is transmitted to the main shaft (4) through the electrodes (3)f, but the main shaft ventilation fan (6) constantly supplies outside air to the inside of the main shaft (4), Since exhaust is exhausted from the port, no temperature difference occurs between the main shaft (4) and the column (9). Further, the temperatures of the main shaft (4) and the column (9) are kept almost the same even when the room temperature changes. Therefore, the amount of thermal deformation (thermal expansion) in the vertical direction of the main axis (4) and the column (9) is the same, and the relative positional deviation in the positive vertical direction between the electrode (3) and the workpiece (5) is almost the same. Does not occur.

FIG. 6 is a diagram showing the results of actual measurement of changes in the relative displacement amount in the vertical direction between the main shaft (4) and the column (9).

In addition, in the embodiment described above, the main shaft ventilation fan (2) and all main shafts (4
) is installed at the bottom of the main shaft (4
) Even if other partial pressures are installed, the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to this invention, by installing a ventilation fan on the main shaft and constantly supplying outside air to the main shaft, the temperature difference between the main shaft and the column, which is the biggest cause of misalignment in the main shaft direction, can be avoided. Since it is configured to completely suppress the amount of thermal deformation (M expansion) between the spindle and the column, it is possible to obtain an extremely high-precision electrical discharge machining device in which there is no relative positional deviation between the 11L pole and the workpiece caused by the difference in the amount of thermal deformation (M expansion) between the spindle and the column. It has the effect of

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an electric discharge machining apparatus according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a hole in the main shaft in FIG. 1, and FIG. Figure 4 is a diagram showing the changes over time in the room temperature, column temperature, and spindle temperature, and Figure 4 is a 'fca diagram showing the changes over time in the relative positional deviation between the electrode and the workpiece. , Is Fig. 5 a conventional electrical discharge machining device? 6 is a diagram showing the changes over time in the room temperature, column temperature and spindle temperature of the conventional example shown in FIG. 5, and FIG. 7 is a diagram showing the changes over time in the conventional example shown in FIG. FIG. 3 is a diagram showing changes in relative positional deviation over time. The figure shows (1) processing tank, (2) rI'i processing liquid,
(3) is the electrode, (4) is the main shaft, (4b) is the electrode clamp device, (5) is the workpiece, (6) is the X table, (7
) is the Y table, (8) is the head, (9) is the column,
QO is the bed, (2) is the main shaft ventilation fan, ←3 is the ventilation hole, and a fathom is the main shaft drive ball screw. (G) is a dust cover. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent: Mr. San Kimura, Rojo 1, Scary Kakutetsu ε Isousaisaki

Claims (3)

[Claims] (1) In an electrical discharge machine that performs machining by generating electrical discharge between opposing electrodes and a workpiece, a ventilation fan is installed to constantly supply outside air to the main shaft slider that feeds the workpiece in the vertical direction. electrical discharge machining equipment. (2) The electric discharge machining apparatus according to claim 1, wherein the main shaft slider has a large number of ventilation holes. (3) The electric discharge machining apparatus according to claim 1, further comprising a dust cover installed around a ball screw that drives the main shaft.