JPH0333450B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a wire cut electrical discharge machining method.

In the wire cut electrical discharge machining method, the wire electrode is usually stretched in a straight line with an appropriate tension between a pair of electrode guides provided at the ends of two arms, and during machining, one of the wire electrodes is stretched in a straight line. It is designed to be able to run at a constant speed from one electrode guide to the other. The distance between both electrode guides is usually several
The cutting part of the workpiece is placed here, and during machining, machining liquid is supplied between the wire electrodes and the workpiece, which face each other with a small machining gap, and there is an intermittent gap between the two. A voltage pulse is applied to generate an electric discharge, and a machining feed is applied to the wire electrode or the workpiece by numerical control or the like, thereby machining the contour of a desired shape.

Therefore, wire electrodes usually have a diameter of 0.02~
It is an extremely thin wire rod of about 0.3 mm, and the grooves on the workpiece cut with it are also 0.1 to 1.0 mm.
The extent of this is extremely narrow.

Therefore, when trying to supply machining fluid to the discharge gap from both the upper and lower surfaces of the workpiece along the wire electrode,
The machining gap is in a high temperature state due to electrical discharge, and bubbles of decomposed gas from the machining fluid are generated, pushing the machining fluid into the machining groove on the machining agent side, or rather, the machining gap of the machining fluid, etc. The wire electrode is pressed toward the machining groove by the discharge pressure caused by the discharge in the machining gap, and machining is performed with the machining gap convex in an arc shape toward the machining groove. Because of this, the supplied machining fluid tends to flow toward the machining groove side, which tends to cause air discharge and short circuits, leading to wire electrode breakage accidents. For this reason, various methods of supplying machining fluid have been devised, but even these methods are often insufficient when the workpiece is thick.

The present invention has been made based on the above-mentioned viewpoints, and its objects are to prevent outside air from entering the machining gap, to easily and reliably supply machining fluid evenly, and to prevent wire breakage during electrical discharge machining. It is an object of the present invention to provide a wire cut electrical discharge machining method that can prevent this.

The gist of this is that a workpiece is machined by a wire-cut electrical discharge machining device equipped with a machining fluid supply nozzle that sprays machining fluid into the machining gap between the wire electrode and the workpiece approximately along the wire electrode. In the wire cut electrical discharge machining method in which machining is started from a starting hole and cutting into a desired shape is performed, machining is performed while supplying machining fluid from the machining fluid supply nozzle to the machining gap at the initial stage of machining, and after machining has progressed appropriately. , a machining fluid supply auxiliary nozzle is fixedly provided in the opening path of the machining start hole of the workpiece or the machining groove formed on the surface of the workpiece as machining progresses;
The purpose is to supply machining fluid into the machining groove from the auxiliary nozzle, and to perform machining while sequentially closing the openings of the machining groove as machining progresses.

Hereinafter, the details of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is an explanatory diagram showing the main parts of an embodiment of the wire cut electrical discharge machining method according to the present invention, FIG. 2 is an enlarged perspective view of an auxiliary nozzle for supplying machining fluid, and FIG. 3 is a cutting line in FIG. 1. FIG. 4 is an enlarged sectional view of the processed portion taken along line -, FIG. 5 is a perspective view showing an embodiment different from the above.

In Fig. 1, 1 is a wire electrode, 2 is a workpiece, and 3
4 is an upper processing head supported on an upper arm (not shown); 4 is a lower processing head supported on a lower arm (not shown); 5 is an energized roller; 6
1 is a brake roller, 7 is a capstan, 8 is a pinch roller, 9 and 10 are guide dies and boat-shaped guides for positioning the wire electrode 1 in a straight line in the processing section, and 11 and 12 are upper and lower processing heads 3. , machining fluid supply pipe for 4, 13 and 14
15 is the upper and lower machining liquid supply nozzles, 15 is the auxiliary nozzle,
16 is a hose for an auxiliary nozzle.

Although omitted in the figure, the workpiece 2 is attached to a processing table provided on a cross slide table (not shown) with a clamp or the like, and the wire electrode 1 in the figure is attached between the wire electrode 1 and the workpiece 2. Relative machining feed in the horizontal direction perpendicular to the axis of is given by driving and controlling the cross slide table with an NC device or the like according to a predetermined program.

During the electrical discharge machining, the wire electrode 1 is pulled out from the electrode supply drum (not shown) and the wire electrode 1 is pulled out from the energized roller 5.
It passes through the brake roller 6, the die guide 9 and the machining start hole 2a previously drilled in the workpiece 2, and then passes through the boat-shaped guide 10, and is then given a predetermined tension by the capstan 7 and the pinch roller 8, and is then collected (not shown). collected into the device. In addition, a machining fluid supply device (not shown) supplies machining fluid continuously or alternately from upper and lower machining fluid supply nozzles 13 and 14 via upper and lower machining fluid supply pipes 11 and 12, and as shown in the figure, usually a wire Electrode 1
is supplied as a coaxial flow of processing fluid to the foreskin.

At the initial stage of machining, machining is carried out using a conventional method, but as the machining progresses and it becomes possible to insert the auxiliary nozzle 15 into the hole 2a, the auxiliary nozzle 15 for supplying machining fluid is inserted into the hole 2a as shown in the figure. Electric discharge machining is performed while constantly supplying machining liquid from the slit hole 15a to the machining part through the machining groove 2b. Normally, the machining after this point is wire cut electric discharge machining of the target mold etc. At the beginning of
The steps up to this point can be called preparatory work for installing the auxiliary nozzle 15.

Therefore, it is recommended that the auxiliary nozzle 15 for supplying the machining liquid be configured as shown in FIG. 2, for example. In the figure, 15a is a slit hole, 15b is a flange, and 15c is a rotation-preventing protrusion that fits into the machined groove.

3 and 4 show details of the opening and engagement of the auxiliary nozzle 15 with the hole 2a through which the wire electrode is inserted, the cut 2b, and the auxiliary nozzle 15 at the start of machining. The machining start hole 2a in this case is made mechanically with a drill or the like or by electrical machining such as electrical discharge machining, and has a diameter of about 1 to 2 mm compared to the width of the machining groove 2b. Because it is several times larger,
There is no problem with the quantitative supply of machining fluid.

Although this auxiliary nozzle 15 is of a type inserted into the hole 2a, the auxiliary nozzle is fixedly provided in the opening path of the machined groove 2b, so that the nozzle opening is aligned with the machined groove 2b.
It may be constructed so as to come into contact with the opening of the holder, and may be used as shown in FIG.

In FIG. 5, 17 is a machining fluid supply hose, 18 is an auxiliary nozzle, 19 is a block to which the auxiliary nozzle is attached, 20 is a magnetic chuck fixed to the block 19, and although not shown, the workpiece 2 A device similar to the above is also provided on the lower side of the .

The tip of the auxiliary nozzle 18 is open in contact with the upper and lower surfaces of the workpiece 2, and from here the processing groove 2b is opened.
Processing fluid is supplied inside. This type of auxiliary nozzle can be easily moved close to the machining area, so it can handle long and complex contour machining.

However, this may not be sufficient if the workpiece 2 has a larger thickness. Then, the auxiliary nozzle 18 is inserted into the machined groove 2b as an extremely thin pipe whose outer diameter is the same or slightly smaller than the width of the machined groove 2b (approximately 0.27 mm when the outer diameter of the wire electrode 1 is about 0.2 mm), and the slit on the side of the pipe is Alternatively, the machining fluid can be sprayed and supplied into the machining groove 2b from the perforation row openings, etc., but in such a case, the machining fluid is supplied from both ends of the pipe (both the upper and lower sides of the workpiece) from a long and thin pipe. Even if it is supplied into a pipe,
Set the machining fluid supply pressure to a considerably high pressure (for example, about 10
kg/cm ² ).

In this way, machining progresses while supplying the machining liquid into the machining groove from the auxiliary nozzle 15 or 18, but since the machining groove 2b is open on the upper and lower surfaces of the workpiece 2, the machining Even if the groove 2b is not bent much midway, as the machining progresses and the opening of the machining groove 2b becomes longer, the supplied machining fluid may flow out from the upper and lower openings midway. Sufficient machining fluid will not be able to reach the machining section.
Therefore, in the present invention, by sequentially closing the openings of the machining grooves 2b on the upper and lower surfaces of the workpiece 2 as machining progresses, a sufficient amount of machining fluid is always supplied to the machining area. The opening of the processing groove 2b can be closed by pushing a viscous material such as clay into the upper and lower openings of the processing groove 2b, or by using a permanent magnet or a permanent magnet. Various types of rubber magnets with magnet powder, plates, pieces, etc. mixed in or installed therein are successively attracted so as to close the upper and lower openings of the processed groove 2b, or permanent magnets or rubber magnets are used, for example, in JP-A-57 Various measures may be taken, such as supplying the material using an automatic supply means as described in Japanese Patent No. 149119 to close the opening of the processed groove 2b.

According to the present invention, the machining fluid is supplied into the machining groove from the auxiliary nozzle fixedly provided on the workpiece, and the opening of the machining groove formed as the machining progresses is sequentially closed. As a result, a sufficient amount of machining fluid is always supplied to the machining section, and machining debris and bubbles generated in the machining section can be removed and the machining fluid can be refreshed smoothly, while at the same time preventing outside air from entering the machining section. The wire electrode is sufficiently cooled, and the occurrence of abnormal discharge such as air discharge is prevented, reducing the risk of wire electrode disconnection.
It is possible to increase the machining current and perform machining at high speed, and even if the workpiece is thick, it is possible to supply a sufficient amount of machining fluid evenly to the entire machining area. Also, it is possible to easily cut a thick workpiece.

The configuration of the present invention is not limited to the embodiments described above, and in particular, the shape and attachment method of the auxiliary nozzle can be freely changed within the scope of the purpose of the present invention. It is all-encompassing. For example, the auxiliary nozzle 15 in FIG.
As mentioned above, the machining fluid supply hose 16 is connected to both ends of the hose.
It is desirable that the nozzle 15 is configured to be connected to supply the machining fluid, and the cross section of the nozzle 15 does not have to be circular as shown in the figure, but may be rectangular long in the path direction of the machining groove 2b. The slit holes 15a, which are the openings through which the machining fluid is ejected, may be formed by opening round holes at predetermined intervals in the axial direction, or by opening the round holes toward the center of the thickness of the workpiece 2. The configuration can be such that the diameter is increased. In addition, at the beginning of machining, machining is performed while supplying machining fluid to the machining gap from a conventional machining fluid supply nozzle equipped in a wire cut electric discharge machining device, but after an auxiliary nozzle is installed, the machining fluid is supplied from the auxiliary nozzle. The machining may be performed using only the machining fluid used.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the main parts of an embodiment of the wire cut electrical discharge machining method according to the present invention, FIG. 2 is an enlarged perspective view of an auxiliary nozzle for supplying machining fluid, and FIG. 3 is a cutting line in FIG. 1. FIG. 4 is an enlarged sectional view of the processed portion taken along line -, FIG. 5 is a perspective view showing an embodiment different from the above. 1... Wire electrode, 2... Workpiece, 2a...
Machining start hole, 3... Upper processing head, 4... Lower processing head, 5... Current roller, 6... Brake roller, 7... Capstan, 8... Pinch roller, 9... Guide die, 10 ... Boat-shaped guide, 1
1, 12... Processing liquid supply pipe, 13, 14...
Processing fluid supply nozzle, 15, 18...Auxiliary nozzle for supplying processing fluid, 16, 17...Hose for supplying processing fluid, 19...Block, 20...Magnetic chuck.

Claims (1)

[Claims] 1. Machining from the machining start hole of the workpiece using a wire cut electrical discharge machining device equipped with a machining fluid supply nozzle that spouts machining fluid into the machining gap between the wire electrode and the workpiece substantially along the wire electrode. In the wire cut electrical discharge machining method, in which cutting into a desired shape is carried out after starting the process, machining is performed while supplying machining fluid from the machining fluid supply nozzle to the machining gap, and after machining has progressed appropriately, the workpiece is cut into a desired shape. A machining fluid supply auxiliary nozzle is fixedly provided in the opening path of the machining start hole or the machining groove formed on the surface of the workpiece as machining progresses, and the machining fluid is supplied from the auxiliary nozzle into the machining groove. A wire cut electrical discharge machining method characterized in that the machining is performed while sequentially closing the opening of the machining groove as the machining progresses. 2. The wire cut electric discharge machining method according to claim 1, wherein the opening of the machined groove is closed by a permanent magnet. 3. The wire cut electric discharge machining method according to claim 1, wherein the opening of the machining groove is closed by a rubber magnet in which permanent magnet powder is mixed in rubber.