JPH0351070Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an electric discharge machine, particularly to an improvement of an electric discharge machine using a cylindrical electrode.

[Technical Background and Problems] Conventionally, in this type of electrical discharge machine, machining fluid 103 is supplied by passing through the inside of a cylindrical electrode 101, as shown in FIGS.
Machining is performed between the electrode 5 and the electrode 101 by submerged electrical discharge. When drilling a through hole 107 (see FIG. 5) in the workpiece 105, if the tip of the electrode 101 penetrates the workpiece 105, the machining liquid 103 will flow downward, causing the workpiece 105 and the electrode 101 to flow out. It is not supplied to the discharge part near the tip and the outer periphery, and in this part, the discharge in the liquid turns into an air discharge and the electrode 101
The servo control of the feed mechanism also became unstable, and machining hardly progressed from this point on. The outer periphery of the electrode 101 near its tip usually has a slightly tapered slope because it is gradually worn away as a result of previous use, that is, discharge. When the processing is stopped when the tip of the electrode 101 penetrates the workpiece 105, the through hole 107 has a similar shape that is slightly larger than the electrode 101, so naturally the upper range is straight cylindrical, and the lower end is sloped. This results in holes and the pore diameters are not uniform. In order to improve this irregularity in pore diameter, a new electrode whose tip is not worn out must be used each time, which increases costs.
Also, it takes time and effort to replace the electrodes. In addition, wear of the tip of the electrode occurs with use, so strictly speaking, even if a new electrode is used, the above phenomenon occurs, resulting in a decrease in processing accuracy.

[Purpose of the invention] This invention was devised in view of the above-mentioned problems, and it suppresses the situation where a hole penetrates the workpiece and causes an air discharge. It is an object of the present invention to provide a device that can stably continue electric discharge using a range where there is no surface area, and can perform drilling with good machining accuracy.

[Structure of the invention] In order to achieve the above object, this invention provides an electrical discharge machine that drills a through hole in a workpiece using a cylindrical electrode through which machining fluid passes. A machining fluid receiving container is formed of an electrically insulating material and is detachably attached to the bottom surface of the workpiece in accordance with the planned hole machining position, and an electric circuit is connected to the bottom of the machining fluid receiving container by contacting the electrode. It is provided with a current-carrying member.

[Embodiment of the invention] An embodiment of the invention will be described below with reference to FIGS. 1 to 3.

Figure 1 is a configuration diagram of the electric discharge machine of this invention, Figure 2
FIG. 3 is an enlarged sectional view of the main part of FIG. 1, and FIG. 3 also shows the through hole at the time of completion.

The cylindrical electrode 3 of the electric discharge machine 1 is connected to the guide arm 5
It is configured to descend vertically along a guide 7 provided at the bottom of the screen while being rotated by a drive control mechanism (not shown) while being controlled at a predetermined feed rate. The machining fluid 11 sent from the machining fluid supply device 9 passes through the inside of the cylindrical electrode 3 and exits from the lower end of the electrode 3 . The workpiece 13 is placed horizontally on a table (not shown), and is positioned and fixed at a predetermined drilling position. A machining liquid receiving container 15 is attached to the lower surface of the workpiece 13 at the planned drilling position. The machining liquid receiving container 15 is configured in a cup shape with a cylindrical portion 17 made of an electrically insulating material such as rubber or ceramics, and a bottom plate 19 made of a metal plate. A sealing member 21 is attached to the upper edge of the cylindrical portion 17 to prevent the received machining fluid 11 from overflowing to the outside.
If it is made of steel, a magnet 23 is embedded so that it can be conveniently attached and detached. The bottom plate 19 is configured with an electric circuit so as to serve as a completion detector for the step in which the electrode 3 descends to perform drilling and penetrate the workpiece 13, and then continues submerged discharge to perform high-precision machining of the through hole 25. There is. In case the workpiece 13 is a non-magnetic material, a machining liquid receiving container 15 is installed near the lower end of the guide arm 5 or below the workpiece mounting table (not shown).
A bracket (not shown) is provided to support the.
Electric power is supplied to the electrode 3 from a power source (not shown) under voltage, current, pulse conditions, etc. according to the drilling conditions.

Next, the operation of the above embodiment will be described.

After positioning and setting the location where the through hole 25 of the workpiece 13 is to be machined, the machining fluid receiving container 15 is inserted into the workpiece 1.
It is attached to the lower surface of the location where the through hole 25 of No. 3 is planned to be machined.
Next, while discharging the machining fluid 11 from the lower end of the cylindrical electrode 3, a submerged discharge is caused between the electrode 3 and the workpiece 13 by supplying power under predetermined conditions.
is perforated. When the hole becomes deep and the lower end of the electrode 3 penetrates the lower surface of the workpiece 13, the machining fluid receiving container 15 is filled with the machining fluid 11 as shown in FIG.
The discharge in the liquid continues due to the slope near the tip of the
While gradually expanding the gradient hole on the workpiece 13 side, the electrode 3
descends. When the lower end of the electrode 3 reaches the bottom plate 19 of the machining fluid receiving container 15 at the position shown in FIG. 3, it operates as the detector and finishes machining. At this time, the unworn straight cylindrical portion of the electrode 3 has reached the bottom surface of the workpiece 13, and therefore the through hole 25 of the workpiece 13 has the same diameter from top to bottom.

In this way, machining can be continued by continuing submerged discharge to penetrate the electrode to the unconsumed part, thereby making it possible to perform drilling with high machining accuracy.

[Effects of the invention] As can be understood from the above description of the embodiments, in short, the present invention perforates the through hole 25 in the workpiece 13 using the cylindrical electrode 3 through which the machining fluid 11 passes. In the electric discharge machine, a machining fluid receiving container 15 is formed of an electrically insulating material and is detachably attached to the lower surface of the workpiece 13 in correspondence with the planned machining position of the through hole 25 of the workpiece 13. A current-carrying member is provided at the bottom of the liquid receiving container 15 to form an electric circuit through contact with the electrode 3.

As is clear from the above structure, in the invention, since the machining fluid receiving container 15 is made of an electrically insulating material, after the electrode 3 penetrates the workpiece 13, the machining fluid receiving container 15 and the electrode 3 are connected. There is no discharge between the two, and the discharge between the workpiece 13 and the electrode 3 is maintained well. When the electrode 3 sufficiently penetrates the workpiece 13 and comes into contact with the current-carrying member provided at the bottom of the machining fluid receiving container 5, it is detected that the electrical discharge machining has ended, allowing accurate hole machining. It is possible to reduce wasted time.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an electric discharge machine according to an embodiment of this invention, Fig. 2 is an enlarged sectional view of the main part of Fig. 1, and Fig. 3 is also an enlarged sectional view of Fig. 1, but with through holes. FIG. 4 is a configuration diagram of a conventional electrical discharge machine at the time of completion, and FIG. 5 is an enlarged sectional view of the main part of FIG. 4. Explanation of main drawing symbols, 1... electrical discharge machine, 3
... Cylindrical electrode, 11 ... Processing liquid, 13 ... Workpiece, 15 ... Processing liquid receiving container, 25 ... Through hole.

Claims (1)

[Scope of utility model registration request] In an electrical discharge machine that drills a through hole 25 in a workpiece 13 using a cylindrical electrode 3 through which machining fluid 11 passes, the through hole 25 in the workpiece 13 is
A machining fluid receiving container 15 is formed of an electrically insulating material and is detachably attached to the lower surface of the workpiece 13 in accordance with the planned machining position. An electric discharge machine characterized by being provided with a current-carrying member constituting an electric circuit.