JPH0240455B2 - WAIYAKATSUTOHODENKAKOSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire cut electric discharge machining apparatus.

2. Description of the Related Art Wire-cut electric discharge machining apparatuses are widely used for cutting or drilling holes in a workpiece by electric discharge machining using a wire electrode.

However, with conventional wire-cut electrical discharge machining equipment, as the cutting progresses, the cut part is supported by the uncut part due to its own weight and bends downward, which deteriorates the machining accuracy of the part being cut. There was a problem.

Various proposals have been made to solve this problem. For example, in Japanese Patent Application Laid-Open No. 128296/1984, a method is proposed in which both the cut piece of the workpiece and the cut piece that has been cut by a wire electrode are held together. to bridge the gap 2
Another example is Japanese Patent Application Laid-Open No. 48-60379, which uses a flat plate-like permanent magnet to suppress bending of the cut piece due to its own weight. This presses the material that is to be cut or fallen off against a separately provided material support at any time or position during processing, suppressing bending of the cut pieces due to their own weight, and preventing bending or disconnection of the wire electrode. The aim is to prevent this and reduce processing failures.

However, all of these methods and devices have to be carried out manually, resulting in a problem of poor work efficiency.

The present invention has been made based on the above-mentioned viewpoints, and its purpose is to automatically clamp and bridge both the cut and uncut parts of a workpiece without manual intervention. It is an object of the present invention to provide a wire cut electrical discharge machining apparatus in which a plurality of permanent magnets are arranged in such a manner as to

The gist of this is that a substrate to which a plurality of vacuum chucks are attached is provided at the top of the processing head, and each of the vacuum chucks is made to detachably hold a permanent magnet, and the permanent magnet is held by the vacuum chuck. A desired one of the above permanent magnets is removed at any time or by a control device controlling a switching valve in accordance with a control command programmed in advance, etc., to separate both the cut and uncut parts of the workpiece. The idea is to hold them together and create a bridge between them.

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

FIG. 1 is an explanatory diagram showing one embodiment of a wire-cut electric discharge machining apparatus according to the present invention, FIG. 2 is a bottom view of the substrate seen from the direction A-A in FIG. 1, and FIG.
A bottom view of the machined workpiece drop-off prevention device seen from the B-B direction in the figure, and Fig. 4 shows the end of machining when a workpiece is machined using the wire cut electric discharge machining device according to the present invention. FIG. 2 is an explanatory diagram showing the state of the workpiece.

1, 2, 3, and 4, reference numeral 1 indicates an upper part extending from a column at a side end (not shown) toward an upper part of the stage for placing the workpiece on the bed. Support arm, 2 is a processing head, 3 is a substrate, 4 and 5 are guide rollers, 6 is a current-carrying roller,
7 and 8 are capstans, 9 and 10 are pinch rollers, 11 and 12 are electrode guides such as die-shaped or boat-shaped guides, 13 is a wire electrode, 14 is a machining fluid nozzle, and 15a and 15b are upper support arms 1.
A bolt 16 is attached to the processing head 2 and rotates the substrate 3 via a gear. A gear 17 is attached to the motor 16. A bolt 18 is attached to the substrate 3 so as to mesh with the gear 17. Gear attached to, 19a, 1
Bolts 9b rotatably attach the substrate 3 to the top of the processing head 2, 20a, 20b, 20c,
20d, 20e, 20f, 20g, and 20h are vacuum chucks provided on the substrate 3 to remove the permanent magnets (however, in FIG. 1, 20b,
20c, 20d, 20f, 20g and 20h are not shown. ), 21a, 21b, 21c, 2
1d, 21e, 21f, 21g and 21h are permanent magnets (however, in Fig. 1, 21b, 21
c, 21d, 21f, 21g and 21h are not shown. ), 22 are the respective vacuum chucks 20a, 2
0b, 20c, 20d, 20e, 20f, 20g
and a pump that applies suction force to 20h, 23
a to 23h are from the pump 22 to the vacuum chuck 2.
A 3-port 2-position switching valve that switches the suction force applied from 0a to 20h (however, 2-position switching valve is shown in the figure).
2b, 22c, 22d, 22f, 22g and 2
2h is not shown. ), 23a-1 to 23
h-1 is a solenoid coil (23b-1 in the figure,
23c-1, 23d-1, 23f-1, 23g-
1 and 23h-1 are omitted. ), 23a
-2 to 23h-2 are springs (23h-2 in the figure)
b-2, 23c-2, 23d-2, 23f-2,
23g-2 and 23h-2 are omitted. ), 24 is a workpiece, 24a is a cutting section, 25 is a clamp for fixing the workpiece 24, and 26 is a stage.

During electrical discharge machining, the wire electrode 13 is transferred from the electrode supply drum (not shown) to the capstan 7,
8 and pinch rollers 9 and 10.
The workpiece 24 is pulled out at a constant speed so as to move with a constant tension between the workpiece 24
is supplied to the processing section where it is placed. In the processing part, the wire electrode 13 is connected to the electrode guides 11 and 12.
The roller 6 is stretched linearly with a constant tension between the rollers 6 and 24, and a discharge voltage is applied between the energizing roller 6 and the workpiece 24 to generate an electric discharge between the workpiece 24 and the workpiece 24.

The workpiece 24 is mounted on the workpiece stand 2 in a direction perpendicular to the tensioning direction of the electrode 13 by driving a cross slide table (not shown) using an NC device.
6, and machining is performed according to the desired machining contour. Note that machining fluid is supplied to the machining portion of the workpiece 24 from a machining fluid nozzle 14 in order to remove machining debris and the like and smooth the discharge.

In the device, permanent magnets 21a to 21h
The apparatus for preventing falling of a machined workpiece, which is arranged so as to sandwich and bridge both the cut and uncut parts of the workpiece 24, has the following special structure.

That is, the substrate 3 is made of non-magnetic metal,
A gear 18 is attached to one end, and the processing head 2
It meshes with the gear 17 of the motor 16 attached to the. The substrate 3 is rotatably attached to the top of the processing head 2 by mounting bolts 19a and 19b, and rotates as the motor 16 rotates.

Further, a plurality of vacuum chucks 20a to 20h are arranged around the machining liquid nozzle 14 at the other end of the substrate 3 facing the workpiece 24, and at one end of the vacuum chucks 20a to 20h, A 3-port 2-position switching valve 23a to 23h is attached to each, and a permanent magnet 2 is attached to the other end.
1a to 21h are vacuum chucks 20a to 2
It is held by the suction force of 0h.

Thus, the movement of the wire electrode 13 of the cross slide table (not shown) on which the stage 26 is placed in the tensioning direction and the vertical direction, the rotation of the board 3 by the motor 16, and the 3-port 2-position switching valve 23a.
The solenoid coils 23a-1 to 23h-1 are controlled by an NC device (not shown) according to a predetermined program.

Therefore, until an arbitrary position or an arbitrary time elapses after the start of machining, a current is applied from an NC device (not shown) to the solenoid coils 23a-1 to 23h-1 of the 3-port 2-position switching valves 23a to 23h. Since there is no spring 23a-2
Due to the action of the respective 3-port 2-position switching valves 23a to 22h, the suction force of the pump 22 is controlled by the respective vacuum chucks 20a to 20h.
Each vacuum chuck 20a to 20h is switched to act on a permanent magnet 21a to 21.
It attracts h. However, at an arbitrary position or after an arbitrary period of time, the 3-port 2-position switching valves 23a to 23h are released from an NC device (not shown).
When a current is applied to the solenoid coil of one selected 3-port 2-position switching valve, the 3-port 2-position switching valve switches, so the pump 22
The suction force that was acting on the vacuum chuck stops, and the permanent magnet held by the vacuum chuck detaches from the vacuum chuck, and the workpiece 2
The wire electrodes 13 are arranged so as to sandwich and bridge the portions on both sides of the cutting line of the portion where the cutting by the wire electrode 13 of No. 4 has proceeded. Therefore, even after the desired processing is completed, bending or falling off due to the cutting portion 24a can be prevented.

There are various configuration combinations of the arm 1 and machining head 2 of this type of wire-cut electric discharge machining apparatus, and various suspension guide systems for the wire electrode 13. For example, an arm extending from one column,
Alternatively, an arm is provided to span between a pair of columns erected on both sides, and a suspended guide path for the wire electrode 13 is formed by a suspended guide roller, a capstan, and a pinch roller on the front surface of the arm; Usually, the processing head 2 is arranged near the tip of the arm 1 or near the center thereof so that it can be moved up and down relative to the arm and can be fixed.
The present invention can be similarly applied to a wire cut electrical discharge machining apparatus having such a configuration. In addition, the board 3
is not only provided to hold a permanent magnet around the machining head 2 in the vicinity of the workpiece of the machining head 2, but also protrudes from the arm toward the workpiece in a cylindrical shape so as to cover the machining head. It is also possible to configure the device to hold the substrate. Moreover, instead of providing a plurality of permanent magnets on one substrate 3, it is possible to extend dissipating arms of the same shape from the processing head to the surroundings, for example, and to provide a substrate on which one permanent magnet is installed at the tip of each arm. You can also do it.

In addition to the conventional alnico magnets or ferrite magnets, so-called rare earth alloy magnets such as iron-chromium-cobalt alloy magnets and samarium-cobalt alloy magnets can be used as the permanent magnets. In particular, according to the rare earth alloy magnet, the maximum energy product is extremely large, and by appropriately selecting the permeance number, for example, a magnet with a diameter of 20 to 30 mm can attract and hold a weight of several tens of kilograms or more. As long as the workpiece and its cut portion are not particularly large, they can be held sufficiently with a few magnets. In addition, in the above-mentioned embodiment, the permanent magnets 21a to 2
1h, the substrate 3 was made of a non-magnetic material because short cylindrical magnet pieces with the possibility of magnetic attraction on side surfaces other than the N and S extreme faces were used as they were, but the permanent magnets 21a or 21h, depending on its shape, combination configuration with yoke iron core, or even combination configuration such as foreskin made of non-magnetic material,
Since it can be constructed so that only a part or one end face is magnetically attracted, in such a case, the substrate 3 or the chuck portion may be made of a magnetic material.

FIGS. 5A and 5B show a cross-sectional view A and a front view B of an embodiment of such a permanent magnet.
5 is a short cylindrical magnet made of, for example, SmCo ₅ , 26 is a yoke-shaped iron core with a recess formed on one side and a magnet 25 in the center of the recess, and 27 is interposed between them as necessary. The magnet 25 and the iron core 26 are made of an annular non-magnetic material made of synthetic resin or alloy, and are fixed by adhesive, mechanical fixing means, or the like.

In the magnet, the back surface 28 of the iron core 26 and the outer circumferential surface, especially the outer circumferential surface 29 on the back side, have almost no magnetic adsorption ability as a permanent magnet, so they must have a predetermined thickness. The chuck of the magnetic substrate 3 can be vacuum-chucked and dropped without being covered with a non-magnetic material.

In this way, by configuring the permanent magnet so that no magnetic flux leaks from a part or one end face and eliminating the magnetic adsorption ability, the need to manufacture the vacuum chuck from a non-magnetic material is eliminated. .

In addition, if the magnets 21a to 21h are placed in a vacuum chuck with a spring interposed between them and the spring is crushed, or if the magnets 21a to 21h are placed in a vacuum chuck state, or even in a state where they are mechanically hooked and chucked, the magnets will not only easily come off and fall when the chuck is opened. Since the magnet can also be levitated, it is also possible to set the substrate 3 below the workpiece 24 and make the magnet fly up and levitate to attract it.

Since the present invention is constructed as described above, according to the apparatus of the present invention, during wire cut electric discharge machining, as the electric discharge machining progresses, the cut portion is supported by the uncut portion by its own weight and bent downward. , prevents deterioration of processing accuracy of the part being cut, and
It is also possible to automatically prevent the cut portion from falling off without any manual intervention.

Note that the present invention is not limited to the embodiments described above. That is, for example, in this embodiment, the substrate was rotated by a motor via a gear, but other known drive mechanisms may also be used, and depending on the shape of the substrate and the vacuum chuck. The design of the method of attachment can be freely changed within the scope of the purpose of the present invention, and the present invention encompasses all of them.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of a wire-cut electric discharge machining apparatus according to the present invention, FIG. 2 is a bottom view of the substrate seen from the direction A-A in FIG. 1, and FIG.
A bottom view of the machined workpiece drop-off prevention device seen from the B-B direction in the figure, and Fig. 4 shows the end of machining when a workpiece is machined using the wire cut electric discharge machining device according to the present invention. FIGS. 5A and 5B are a cross-sectional view and a front view showing an example of a changed configuration of the permanent magnet used. 1... Upper support arm, 2... Processing head, 3
... Board, 4, 5 ... Guide roller, 6 ... Current-carrying roller, 7, 8 ... Capstan, 9, 10 ...
Pinch roller, 11, 12...electrode guide, 13
...Wire electrode, 14...Machining liquid nozzle, 16...
...Motor, 17, 18...Gear, 20a, 20
b, 20c, 20d, 20e, 20f, 20g,
20h...Vacuum chuck, 21a, 21b, 21
c, 21d, 21e, 21f, 21g, 21h...
...Permanent magnet, 22...Pump, 23a, 23b,
23c, 23d, 23e, 23f, 23g, 23
h...3 port 2 position switching valve, 23a-1, 23
b-1, 23c-1, 23d-1, 23e-1,
23f-1, 23g-1, 23h-1...Solenoid coil, 23a-2, 23b-2, 23c-
2, 23d-2, 23e-2, 23f-2, 23
g-2, 23h-2... Spring, 24... Workpiece, 24a... Cutting portion.

Claims (1)

[Scope of Claims] 1. A substrate provided in a position facing the workpiece of a processing head, a plurality of vacuum chucks arranged on the substrate, and a permanent permanent film removably held by each of the plurality of vacuum chucks. A wire-cut electrical discharge machining apparatus comprising a machined workpiece drop-off prevention device comprising a magnet and a control device capable of controlling the vacuum chuck and detaching a desired permanent magnet at any time. 2. The wire cut electric discharge machining apparatus according to claim 1, wherein the suction part of the vacuum chuck is made of a non-magnetic material. 3. The wire-cut electric discharge machining apparatus according to claim 1, wherein the surface of the permanent magnet that is attracted to the vacuum chuck is of a magnetic flux non-leak type.