JPH0536172B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides wire-cut electrical discharge machining while jetting and supplying machining liquid coaxially with the wire electrode into the machining gap formed between the wire electrode and the workpiece. The present invention relates to a processing method for performing.

[Conventional technology]

In wire cut electric discharge machining, machining debris generated during electric discharge machining is removed from the machining gap, and the workpiece and wire electrode in the machining section heated by electric discharge are cooled to prevent abnormal electric discharges such as arcs. In order to prevent the wire electrode from fusing due to overheating and to achieve high machining speed and accuracy, machining fluid (usually water) is supplied during machining to intervene in the machining gap. It is necessary to renew the fluid. In order to renew the machining fluid, it has been conventionally done to supply machining fluid coaxially with the wire electrode. Since the machining fluid that flows into the machining gap from the surface of the workpiece gradually spreads along the already machined machining groove, it is necessary to supply a sufficient amount of machining fluid to the machining gap near the opposite surface of the workpiece. is difficult. In addition, since a normal nozzle device whose position is manually adjusted and set is located several mm away from the surface of the workpiece, it is necessary to supply a sufficient amount of machining fluid to the machining gap. When the fluid pressure of the jetted machining fluid is increased, the machining fluid jetted from the nozzle spout will entrain the air around the separated area, and the machining fluid mixed with air such as bubbles will be supplied to the machining gap. This not only reduces the cooling effect of the machining fluid, but also makes it easier for air discharge to occur, causing wire electrode breakage. Furthermore, if the machining fluid is jetted out from only one side of the workpiece and flows out from the other side, even if the pressure of the jetted machining fluid is increased, the machining gap near the surface on the opposite side of the workpiece,
In particular, it is difficult to supply machining liquid in a stable manner to the upper end of the machining gap, resulting in a problem that machining becomes unstable in this area. Therefore, it is common practice to provide nozzle devices for jetting and supplying machining fluid on both sides of the upper and lower parts of the workpiece, and to jet the machining fluid from both the top and bottom coaxially with the wire electrode.

[Problem to be solved]

However, when machining fluid is sprayed and supplied from both the upper and lower sides of the workpiece in this way, the machining fluid flowing from both the upper and lower sides merges and collides near the machining gap at the center of the thickness of the workpiece, which is the highest temperature during machining. However, turbulence and vortices are formed here, and there are parts where the machining fluid stagnates without being renewed. In particular, the stagnation of machining fluid that occurs near the center of the thickness of the workpiece is difficult to eliminate, and the machining fluid remains for a long time. As the machining fluid tends to stagnate for a long time, the machining fluid is not refreshed sufficiently, and as a result, abnormal discharges such as arcs occur, and the machining area is abnormally heated, reducing machining accuracy and causing disconnection of the wire electrode. I will let you do it. In addition, in order to prevent the machining fluid from stagnating, the pressure of the machining fluid jetted out from the nozzle device is increased to increase the amount of machining fluid supplied to the machining gap. Since the nozzle device is located several millimeters away from the surface of the workpiece, the spouted machining fluid still entrains the surrounding air, resulting in machining fluid mixed with air being supplied to the machining gap. .

In view of the above-mentioned problems, the present invention has been developed to supply a sufficient amount of machining fluid to the machining gap without entraining and mixing the surrounding air, and to stabilize the renewal of the machining fluid at each part of the machining gap. An object of the present invention is to provide a wire cut electric discharge machining method that allows machining to be carried out smoothly in a stable condition.

[Means to solve problems]

In order to achieve this object, the present invention provides a nozzle device that is placed at least in the lower part of the nozzle devices that are placed in the upper and lower parts of the workpiece, and is moved in the axial direction of the wire electrode by the hydraulic pressure of the machining fluid. Using a nozzle device having a floating cylindrical nozzle consisting of a hollow cylindrical body that is pressed and opened at the tip with a diameter larger than the width of the processing groove of the workpiece,
The pressure of the machining fluid jetted and supplied from the lower nozzle device is higher than the pressure of the machining fluid jetted and supplied from the upper nozzle device, and the lower surface of the workpiece is within the slidable range of the floating tube nozzle. By arranging the lower nozzle device and adjusting the hydraulic pressure of the supplied machining fluid, the tip surface of the floating tube nozzle that moves in the axial direction and is about to contact the bottom surface of the workpiece and the workpiece A disc-shaped nozzle with a small distance is automatically formed between the bottom surface of the object and machining is performed while a part of the supplied machining fluid flows out radially from the disc-shaped nozzle. This is a characteristic feature.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a preparatory stage before the start of electrical discharge machining, and also shows the vicinity 2 of a machining section of a wire cut electrical discharge machining apparatus equipped with a nozzle device 1. As shown in FIG. The wire cut electrical discharge machining device has a structure similar to a normal one, and has a machining groove 3 corresponding to a part of the machining contour shape of the workpiece 3.
1, a wire electrode 4 extends vertically,
The wire electrode 4 extends coaxially through an upper nozzle device 5 above the workpiece 3 and a lower nozzle device 6 below the workpiece 3, and has positioning guide members such as rollers, dies, or ship-shaped rollers arranged above and below. 67 (the upper guide is not shown) and rollers 7 and 8 while traveling from the bottom to the top or vice versa, between the wire electrode 4 and the workpiece 3 via the brushes 70 and 80. A pulse discharge is generated by the supply pulse from the electric discharge machining power supply 9 provided in the workpiece 3.
The workpiece 3 is subjected to electrical discharge machining by being fed at a set constant speed or by servo feed control depending on the machining state.

Next, the nozzle device 1 will be explained. The upper nozzle device 5 located above the workpiece 3 is provided on the processing machine head or upper arm (not shown), and the distance between the processing fluid spout and the surface of the workpiece is fixed at a predetermined interval. The nozzle device is similar to the conventional nozzle device, or the same as the lower nozzle device 6 described below.
In the case of mmφ, the machining liquid is spouted coaxially and columnarly from the opening diameter (usually around 3 mmφ) surrounding the wire electrode 4 on the surface of the workpiece 3.

In this embodiment, a case will be described in which a conventional normal nozzle device is used as the upper nozzle device 5. The upper nozzle device 5 is arranged close to the upper surface of the workpiece 3 and the opening 52 of the upper nozzle device 5 so that the gap is about several mm or at least about 1 mm, and a part of the machining liquid is injected into the machining gap. However, it is desirable that the other machining fluids flow radially across the surface of the workpiece 3 as shown by the arrows (Fig. 2), and for this reason, the upper nozzle device is equipped with appropriate means (not shown). It is configured such that the vertical movement position can be adjusted, and the distance between the opening 52 and the workpiece 3 can be adjusted. Moreover, the lower nozzle device 6 is
Fixed to the processing machine body or the end of the lower arm 10,
Also, although not shown, there is a nozzle body 62 that is installed so as to be vertically adjustable and has a cylindrical hollow part 61 that opens at the upper end, and a cylindrical hollow part of the nozzle body 62 that is made of a hollow cylindrical body. It is slidably supported in the axial direction by a flange 68 on the side wall surface of the part 61, and at least the outer diameter of the tip is formed smaller than the diameter of the opening of the nozzle body 62, and the hollow part is formed in the tip. The cylindrical hollow part 6 of the nozzle body 62 is opened at the other end with a diameter larger than the width of the machining structure of the workpiece to form a machining fluid spout.
1, and a guide member 67 located coaxially inside the floating tube nozzle 63, through which the wire electrode 4 is inserted and guided for positioning. The wire electrode guide member 64 is fixedly provided to the wire electrode guide member 64. A cylindrical groove 65 is formed on the inner lower surface of the nozzle body 62, and this groove 65 communicates with a pipe 66 extending outside the lower nozzle device 6.
6, the machining fluid flows from the groove 65 to the floating cylinder nozzle 63.
The liquid is injected under pressure into the lower chamber of the hollow part 61 which is divided into upper and lower parts by the flange part 68 . If the wire electrode 4 has a diameter of about 0.2 mm, the machining fluid jetting opening of the floating cylinder nozzle 63 is usually about 3 mm in diameter. In this way, the lower nozzle device 6 includes the wire electrode guide member 64 fixed approximately at the center of the hollow portion 61 of the nozzle body 62,
A floating tube nozzle 63 is disposed between the nozzle body 62 and slidable in the wire and nozzle axial directions.

The operation of the upper and lower nozzle devices 5 and 6 configured as described above will be explained with reference to FIGS. 1 and 2. The state shown in FIG. 1 is a state in which the wire cut electrical discharge machining apparatus is not operating, that is, machining fluid is not being fed into the nozzle device 1. The vertical positions of the upper nozzle device 5 and the lower nozzle device 6 are adjusted and set from the state shown in FIG. The lower surface of the floating tube nozzle 63 is positioned within the axially slidable range, and then the tube 5
Processing fluid is injected under pressure from No. 1 and 66.

From the upper pipe 51, approximately 0.1 to 0.5 except in special cases.
The machining fluid is supplied under pressure from the machining fluid supply section, which is configured so that the pressure can be adjusted in kg/cm ² , usually about 0.2 to 0.3 Kg/ ^{cm 2} , and preferably in units of several tens of g/cm 2 . The liquid is ejected from the part 52 onto the workpiece 3 and the wire electrode 4. On the other hand, from the lower pipe 66, it is usually about 1~
The machining fluid supplied under pressure from the machining fluid supply liquid configured to be able to adjust the pressure in units of about 2 kg/cm ² , preferably several tens to 100 g/cm ² , floats from the groove 65 communicating with the pipe 66 . It passes through the cylindrical gap between the cylindrical nozzle 63 and the electrode guide member 64, and is ejected from the tip of the floating cylindrical nozzle 63 to the lower surface of the workpiece 3 while coaxially surrounding the wire electrode 4. In this case, the flange 68 of the floating tube nozzle 63 acts as a piston, and the floating tube nozzle 63 rises due to the pressure of the machining fluid, protrudes from the main body 62, and attempts to come into contact with the lower surface of the workpiece 3. A part of the machining liquid spouted from the tip of the floating tube nozzle 63 with a diameter of approximately 3 mmφ is injected into the machining groove 31 and rises as a jet in the machining gap and cutting groove. Machining groove width (the machining gap is usually about several tens of microns, so the wire electrode
In the case of 0.2mmφ, the processing groove width is 0.3mm or less)
Because it is formed sufficiently larger, a part of the jetted machining fluid collides with the surface of the workpiece at the periphery of the machining groove and seeks a flow path laterally, and the tip of the floating cylinder nozzle 63 is caused by the action of this machining fluid. A disk-shaped flow path with a minute gap is formed between the surface and the lower surface of the workpiece 3, and the machining liquid is radially jetted outside as shown by the arrows in FIG. 2 from this minute gap. In this case, there is a distance of about 0.5 mm or less between the tip surface of the floating tube nozzle 63 and the lower surface of the workpiece 3.
Normally, a minute gap of about 0.1 to 0.3 mm is formed, and a part of the machining fluid is ejected from the disk-shaped nozzle in the minute gap as shown by the arrow, causing the floating tube nozzle 63
The pressure of the supplied machining fluid is adjusted so that it is not only pressed as described above, but also sucked into the lower surface of the workpiece 3. However, since the pressure of the machining fluid ejected from the lower nozzle device is higher,
The machining liquid spouted from the lower nozzle device 6 flows into the machining groove 3.
The machining liquid rises in the upper nozzle device 5 side and merges with the machining fluid spouted from the upper nozzle device 5 on the upper surface of the workpiece 3 or in the machining groove 31 slightly below the upper surface. The machining liquid flows on the upper surface of the workpiece 3, and a part of the machining fluid flows toward the machined groove 31. In this way, the ejection pressure of the machining fluid from the upper nozzle device 5 and that from the lower nozzle device 6 are such that, as described above, the ejection pressure from the lower nozzle device 6 is set higher, and the ejection pressure from the upper nozzle device 5 is set higher. Since the gap between the upper surface of the workpiece 3 and the upper surface of the workpiece 3 is larger than the gap between the lower nozzle device 6 and the lower surface of the workpiece 3, the machining liquid from the lower nozzle device 6 flows inside the machining groove 31 toward the upper nozzle device 5 side. It can rise to or near there, merge with the machining liquid from the upper nozzle device 5, and flow down laterally on the upper surface of the workpiece 3 and inside the machined groove 31. In addition, the floating cylinder nozzle 63 has a flange 68 formed by the machining fluid as described above.
When the machining fluid is supplied, the tip of the floating cylinder nozzle 63 is pushed up and adsorbed by the machining fluid that is ejected relatively quickly from the disk-shaped nozzle in the minute gap between the tip surface of the floating tube nozzle 63 and the bottom surface of the workpiece 3. is always held at a predetermined minute distance from the surface of the
A portion of the machining fluid will be ejected to the outside from the small gap formed by the disc nozzle, so high-pressure machining fluid will be ejected from a position extremely close to the workpiece to fill the machining gap with a sufficient amount. In addition to being able to supply liquid, the processed groove 31 can be opened from the lower nozzle device 6 side.
Air does not get mixed into the machining fluid that enters,
Furthermore, since the machining fluid rises within the machining groove 31 and joins the machining fluid from the upper nozzle device 5, air is not mixed into the machining fluid in this path as well, thereby reducing the cooling ability of the machining fluid. can be prevented, the occurrence of air discharge is reduced, and both upper and lower nozzle devices 5, 6
The machining fluid ejected from the workpiece 3 does not merge and collide at the center of the workpiece 3 and stagnate therein, and the machining fluid can be smoothly refreshed at each location between machining operations.
In addition, the distance between the tip end surface of the floating tube nozzle 63 and the lower surface of the workpiece 3 may be different if the surface of the workpiece 3 has some undulations or the thickness of the workpiece 3 is uneven. Even if the surface of the workpiece 3 is undulated, the machining fluid is always ejected from a position that is a predetermined distance away from the surface of the workpiece 3, so that the predetermined minute interval is maintained by following the shape changes such as undulations. , it is possible to perform stable machining by always supplying a constant amount of machining liquid to the machining gap, and furthermore, the nozzle tip is located close to the workpiece 3.
Since there is no contact such as pressure welding with, there is no possibility of short circuits or damage to the surface of the workpiece 3.

In addition, in the present invention, the pressure of the machining fluid jetted from the lower nozzle device is made higher than the pressure of the machining fluid jetted from the upper nozzle device, and the machining fluid is jetted from the bottom to the top of the machining gap. Therefore, a nozzle device having a floating cylinder nozzle that does not cause the risk of entraining and mixing in the surrounding air even if machining fluid is ejected under high pressure is used as the lower nozzle device.
The upper nozzle device has a relatively low pressure of the machining fluid spouted out, and there is no need to inject the machining fluid into the machining gap, so manual setting is relatively easy. No problem occurs even if the ejection ports are arranged at positions separated by about mm, and therefore, it is possible to use a conventional nozzle device as the upper nozzle device. Therefore, in the above-mentioned embodiments, a conventional nozzle device is used as the upper nozzle device, but a nozzle device having a floating cylinder nozzle similar to the lower nozzle device can also be used as the upper nozzle device. Of course, this is also a good thing.

〔effect〕

As explained above, according to the present invention, nozzles are disposed at the upper and lower parts of the workpiece, and the nozzle is disposed at a position lower than the pressure of the machining fluid ejected from the nozzle disposed at the upper part. By increasing the pressure of the machining fluid jetted out from the device, the machining fluid jetted out from the lower nozzle device rises in the machining gap and the machining groove and sprays out onto the top surface of the workpiece, causing damage to the workpiece. Since the machining fluid from the upper nozzle device joins with the machining fluid from the upper nozzle device on the top surface and flows radially over the top surface of the workpiece, there is no possibility that the machining fluid will stagnate due to vortices or turbulence occurring in the machining gap. In addition, the relatively low pressure machining fluid ejected from the upper nozzle device joins the machining fluid that has risen through the machining gap and the machining groove and spouted onto the top surface of the workpiece, causing the upper surface of the workpiece or Since the flow of the machining fluid at the upper end of the machining gap is also adjusted, the machining fluid can be stably supplied to all parts of the machining gap and the machining fluid can be smoothly renewed.

In addition, even if the machining fluid from the lower nozzle device and the machining fluid from the upper nozzle device meet in the machining gap slightly below the top surface of the workpiece, the machining gap at the center of the thickness of the workpiece There is no possibility that the machining fluid will remain stagnant for a long period of time, unlike in the case of merging at the Furthermore, if the pressure of the machining fluid ejected from the lower nozzle device is increased, there is a risk that surrounding air will be drawn in and air will be mixed into the machining fluid. By using a nozzle device having a lower nozzle device, arranging the lower nozzle device so that the lower surface of the workpiece is located within the axially slidable range of the floating tube nozzle, and adjusting the hydraulic pressure of the supplied machining fluid, A disk-shaped nozzle with a minute gap is automatically formed between the tip surface of the floating cylinder nozzle that is about to move in the axial direction and come into contact with the lower surface of the workpiece, and the lower surface of the workpiece is automatically formed. By performing machining with a portion of the supplied machining fluid flowing out radially from the shaped nozzle, it is possible to increase the fluid pressure and supply a sufficient amount of machining fluid to the machining gap without introducing air. I can do it. In addition, by allowing a portion of the supplied machining fluid to flow out from the disc-shaped nozzle between the microscopic holes that are automatically formed,
Even if there are some undulations on the surface of the workpiece, the distance between the tip of the floating nozzle and the bottom surface of the workpiece is maintained at a predetermined minute distance even if it follows the shape changes such as the undulations. The machining fluid is always sprayed and supplied from a position a predetermined distance away from the workpiece surface, and a constant amount of machining fluid is always supplied between machining without mixing in the surrounding air, allowing stable machining. In addition, the nozzle tip does not come into pressure contact with the workpiece, thereby preventing short circuits or damaging the surface of the workpiece. According to the present invention, by achieving these effects,
It is possible to prevent the occurrence of abnormal discharges such as arcs and aerial discharges, and also to efficiently remove machining debris and cool the machined part, allowing high-precision machining to be performed at high speed.

[Brief explanation of drawings]

FIG. 1 is a partially omitted cross-sectional view of a wire-cut electric discharge machining apparatus showing an embodiment of the present invention, and FIG. 2 is a partially omitted cross-sectional view of the wire-cut electric discharge machining apparatus showing the operating state of a nozzle device. DESCRIPTION OF SYMBOLS 1... Nozzle device, 2... Around the machining part of the wire cut electrical discharge machining device, 3... Workpiece, 4... Wire electrode, 5... Upper nozzle device, 6... Lower nozzle device, 61... Hollow part , 62... Nozzle body, 63... Floating cylinder nozzle, 64... Wire electrode guide member.

Claims (1)

[Claims] 1. In a wire cut electric discharge machining method in which nozzle devices for supplying machining fluid are arranged at the upper and lower parts of the workpiece, and machining is performed while machining fluid is jetted and supplied coaxially with the wire electrode from both nozzle devices, at least As a nozzle device placed at the bottom of the workpiece,
A nozzle body that has a cylindrical hollow part with one end open and is provided in a machining fluid supply conduit communicating with the other end of the cylindrical hollow part, and a nozzle body that is coaxial with the cylindrical hollow part of the main body by the nozzle body. and a hollow cylindrical body that is slidably supported in the axial direction of the cylindrical hollow part of the main body and has a hollow part that opens at the tip with a diameter larger than the width of the processing groove of the workpiece. a floating tube nozzle that is moved in the axial direction by the hydraulic pressure of the machining fluid supplied from the machining fluid supply pipe; A nozzle device configured of a wire electrode guide member having a through hole formed in the central axial direction and a positioning guide member for a wire electrode inserted through the through hole is used to eject water from a lower nozzle device. While the pressure of the machining fluid being supplied is higher than the pressure of the machining fluid jetting and being supplied from the upper nozzle device, the lower part is placed such that the lower surface of the workpiece is located within the slidable range of the floating cylinder nozzle. By arranging the nozzle device and adjusting the fluid pressure of the supplied machining fluid, the contact between the tip surface of the floating cylinder nozzle that moves in the axial direction and attempts to contact the bottom surface of the workpiece and the bottom surface of the workpiece is A wire cut electric discharge machining method characterized in that a small disc-shaped nozzle is automatically formed in between, and machining is performed in a state in which a part of the supplied machining fluid flows out radially from the disc-shaped nozzle.