JPH038890B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a wire cut electric discharge machining apparatus.

[Conventional technology]

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

However, in conventional wire-cut electric discharge machining equipment, as cutting progresses, the uncut portion bends downward due to the weight of the cut portion.
There was a problem that processing accuracy deteriorated.

Various proposals have been made to solve this problem. For example, in Japanese Patent Application Laid-Open No. 128296/1986, a method is proposed in which both the cut piece of the workpiece and the part of the workpiece that has been cut by a wire electrode are held together. In this method, two permanent magnets in the form of a flat plate are provided to bridge the cut piece, thereby suppressing the bending of the cut piece due to its own weight. Press the material that is cut off or falling off against a separate material support stand at any time or position during processing to suppress bending of the cut piece due to its own weight, and prevent bending or disconnection from the wire electrode. This is intended to prevent machining failures due to

However, all of these methods and devices have to be carried out manually, resulting in a problem of poor work efficiency. Therefore, in order to solve these problems, the applicant of the present invention filed a patent application
No. 56-35191 (see Japanese Patent Application Laid-Open No. 57-149119), a wire cut electrical discharge machining device and a board to which a plurality of permanent magnets can be detachably attached to the front part of the machining head are provided, and a plurality of permanent magnets are provided on the board. Discloses a device that detaches the permanent magnet by controlling the current applied to a plurality of solenoid coils, thereby sandwiching and bridging both the cut portion and the uncut portion of the workpiece without manual intervention. did.

However, since the above device does not require manual operation, the efficiency of the work has improved, but when a permanent magnet with a high attraction and retention force is used, the solenoid coil has a large amount of energy when detaching the permanent magnet. There was a problem that current had to be supplied, which was inefficient. Therefore, in order to solve these problems, the applicant of the present invention filed a patent application in 1983.
- In No. 189081 (see Japanese Patent Application Laid-open No. 1890-94917), a device that uses a toggle mechanism to efficiently detach a permanent magnet attracted to a permanent magnet mounting seat made of a magnetic material provided on a board. disclosed.

However, although the above-mentioned device has improved the detachment action of the permanent magnet by the toggle mechanism, there is still a problem that it is inefficient when using a permanent magnet with a high attraction and holding capacity, and further improvement is desired. Mareta.

[Problem that the invention seeks to solve]

The present invention has been made to solve the above problems. The purpose of this is to automatically and efficiently arrange a plurality of magnetic suction elements to bridge both the cut part and the fixed part of the workpiece without manual intervention. Equipped with a permanent magnet holder that removably holds the child,
It is an object of the present invention to provide a wire cut electrical discharge machining device that allows easy removal of the magnetic attractor.

[Means for solving problems]

The above object is to provide a wire-cut electric discharge machining apparatus with a substrate attached to a machining head, a magnetic attractor, at least a part of which is made of a permanent magnet, and which can be attached to a workpiece by magnetic force. a plurality of permanent magnet holders that detachably hold the magnetic attractor by mechanical opening and closing without magnetic attraction; an actuator that opens and closes the permanent magnet holder; and a control device that controls opening and closing of the permanent magnet holder. This is achieved by providing a cut piece fall-off prevention device consisting of a control device and a control device.

This magnetic attractor may be a single permanent magnet, or it may be a permanent magnet with a non-magnetic coating or handle attached, or it may be a permanent magnet and an iron core, and the magnetic field lines only occur in specific parts. A device that is constructed so as not to emit any noise is used.

That is, in the present invention, a magnetic attractor is precisely dropped on the boundary line between the cut piece and the workpiece, and the permanent magnet is attracted to the workpiece, thereby separating both the cut piece and the workpiece. Any permanent magnet holder is sufficient as long as it can bridge and prevent the cut pieces from falling. Therefore, the permanent magnet holder that holds the magnetic attractor for this purpose can be attached and detached by mechanically opening and closing without magnetically attracting the magnetic attractor. The material, shape, size, etc. thereof are not particularly limited as long as they can be held in place and dropped reliably to a predetermined location.

[Effect]

With the above configuration, during processing, the magnetic attractors are held by the plurality of permanent magnet holders in a removable manner by mechanical opening and closing without being magnetically attracted, and are conveyed to the cutting line of the workpiece, and are conveyed to the cutting line of the workpiece. The magnetic attractor, which is mechanically held by the permanent magnet holder, is easily removed by controlling the permanent magnet holder to open and close as needed, and the cut piece is fixed across the cutting line. It can be held by adsorption to the processed object.

〔Example〕

The details of the present invention will be specifically explained below with reference to the drawings.

FIG. 1 is an explanatory diagram showing one embodiment of the wire-cut electrical discharge machining apparatus according to the present invention, and FIG. 2 is a permanent magnet holder that holds a magnetic attractor consisting only of permanent magnets of the wire-cut electrical discharge machining apparatus shown in FIG. 1. An enlarged explanatory view of the tool, FIG. 3 is an enlarged bottom view of the device for preventing cut fragments from falling off as seen from the direction A-A in FIG. 1, and FIG.
FIGS. 5 and 6 are explanatory diagrams showing the state of the workpiece at the end of machining when the workpiece is machined using the wire-cut electrical discharge machining apparatus according to the present invention, which is another example. An explanatory diagram showing Fig. 7 is the 6th
The figure is a partially cutaway explanatory diagram showing a holding mechanism of a permanent magnet holder that holds a magnetic attractor made of only permanent magnets, and FIGS. 8A and 8B illustrate an example of a attractor made of a permanent magnet and other members. They are a sectional view and a front view.

Therefore, the magnetic attractor used in the embodiments shown in FIGS. 1 to 7 consists of a single permanent magnet or only a magnet, whereas the attractor shown in FIG. 8 consists of one permanent magnet. It is a composite of a steel core and an iron core.

In FIGS. 1 to 4, 1 is an upper support arm formed by extending from a column at a side end (not shown) toward the upper part of the stage for the workpiece on the bed, and 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, and 14 The machining fluid nozzle 14a is located in the center of the
A holding plate 15a, 15a is a bolt for attaching the processing head 2 to the lower end of the upper support arm 1, and 16 is attached to the processing head 2, and rotates and positions the substrate 3 through a gear. A motor, 17 is a gear that is attached to the motor 16 and rotates as the motor 16 rotates, 18 is a gear that is provided on the base plate 3 so as to mesh with the gear 17, and 19a, 19a are the holders. The substrate 3 is transferred to the processing head 2 via the plate 14.
a bolt rotatably attached to the top of the
20 is a scissor-shaped permanent magnet holder made of non-magnetic material; 21, 21 are the permanent magnet holders 20, 2;
a spring that provides a clamping state or clamping force to 0;
Reference numerals 2 and 22 refer to magnetic attractors consisting of only a single permanent magnet held in the permanent magnet holders 20 and 20 by the action of springs 21 and 21, respectively;
23, 23 are hydraulic cylinders, 23a, 23a are pistons, 23b, 23b are the pistons 23a,
With the reciprocating movement of 23a, the hydraulic cylinders 23,
A piston rod moves within 23, 24, 24 are 4-port 2-position switching valves, 24a, 24a are solenoid coils, 24b, 24b are springs,
25 is a hydraulic pump, 26 is an oil tank, 27 is a workpiece, 27a is a cutting line thereof, 28 is a clamp for fixing the workpiece 27, 29 is a stage, and 30 is a numerical control device.

During electrical discharge machining, the wire electrode 13 is transferred from the electrode supply drum (not shown) to the capstan 7.
The workpiece 27 is pulled out at a constant speed by the capstan 8 and the pinch roller 10 with a predetermined tension applying brake applied by the pinch roller 9, and passes through the guide rollers 4, 5 and the energized roller 6. It 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 1.
The roller 2 is stretched in a straight line with a constant tension between the rollers 6 and 27, and a discharge voltage is applied between the energizing roller 6 and the workpiece 27 to generate an electric discharge between the workpiece 27 and the current-carrying roller 6.

The workpiece 27 is moved via the stage 29 in a plane perpendicular to the stretching direction of the wire electrode 13 by driving a cross slide table (not shown) using the numerical control device 30. Machining is performed according to the desired machining contour.
During electrical discharge machining, machining fluid is supplied from a machining fluid nozzle 14a provided on the holding plate 14 in order to remove machining debris generated on the machined portion of the workpiece 27 and to smooth the electrical discharge machining.

In such a wire cut electric discharge machining apparatus, a cut piece drop-off prevention device for arranging the magnetic attractors 22, 22 on the cutting lines 27a, 27a of the workpiece 27 is the first embodiment shown in FIGS. 1 to 3. It has the following structure.

A gear 18 is provided at one end of the board 3,
This gear 18 meshes with a gear 17 attached to a motor 16 fixed to the processing head 2. The substrate 3, which is rotatably attached to the top of the processing head 2 via the holding plate 14 with bolts 19a, is connected to the numerical control device 30.
As the motor 16 is rotated, the positioning rotation is performed at a predetermined rotation angle.

Further, on the substrate 3, there is a permanent magnet holder 2 made of a non-magnetic material that holds the magnetic attractors 22, 22 between them.
A plurality of nozzles 0 and 20 are arranged around the machining liquid nozzle 14a so as to face the workpiece 27.
A hydraulic cylinder 23, 23 is attached to each permanent magnet holder 20, 20, and each hydraulic cylinder 23, 23 receives oil from a hydraulic pump 25 via a 4-port 2-position switching valve 24, 24. The pistons 23a, 23a in the respective hydraulic cylinders 23, 23 reciprocate as the four-port, two-position switching valves 24, 24 are switched. Therefore, the piston rods 23b, 23b connected to the pistons 23a, 23a also connect to the pistons 23a, 23a.
It similarly moves along with the reciprocating motion of 23a.

Therefore, the wire electrode 13 of the cross slide table (not shown) on which the stage 29 is placed
movement in the tension direction and vertical direction, rotation of the board 3 by the motor 16, and 4-port 2-position switching valve 2.
Controls 4 and 24 are performed by a numerical control device 30 according to a predetermined program.

After the start of machining, no current is applied to the solenoid coils 24a, 24a of the 4-port, 2-position switching valves 24, 24 from the numerical control device 30 until the predetermined position is reached. The position switching valves 24, 24 are operated by the action of springs 24b, 24b, so that the hydraulic pump 2
Since the hydraulic pressure from 5 is switched in the direction of lifting the pistons 23a, 23a upward in FIG.
The permanent magnet holders 20, 20 are springs 21, 2
It is closed by an elastic force of 1. Therefore,
The magnetic attractors 22, 22 are permanent magnet holders 20, 2
It is sandwiched by 0. However, when a predetermined position is reached and current is supplied from the numerical controller 30 to the selected solenoid coil 24a, 24a of the 4-port 2-position switching valve 24, 24, the 4-port 2-position switching valve 2
4 and 24, the magnetic force of the solenoid coils 24a and 24a overcomes the elastic force of the springs 24b and 24b to switch the hydraulic pressure from the hydraulic pump 25.
Therefore, the hydraulic pressure from the hydraulic pump 25 moves the pistons 23a, 23a in the hydraulic cylinders 23, 23 to the second position.
Since the switch is made in the downward pushing direction in the figure, the permanent magnet holders 20, 20 overcome the elastic force of the spring 21 and are pushed open. 22, 22 can be easily removed from the permanent magnet holders 20, 20, and are placed on the cutting line 27a of the workpiece 27 by the wire electrode 13.
When the desired processing is completed, the cutting lines 27a, 27a
This makes it possible to prevent the cut pieces from bending or falling off.

Next, the apparatus shown in FIG. 5 will be explained.

In FIG. 5, the same numbers as in FIGS. 1 to 4 indicate the same components, and 31,
31 is a permanent magnet holder, 32, 32 is a solenoid coil, 33, 33 is an iron core, 34, 34 is a pressing tool made of non-magnetic material, 35, 35 is an iron core 33 attached to one end, and the other A connecting rod 36, to which a pressing tool 34 is attached at one end, is a power supply circuit that supplies current to the solenoid coils 32, 32 based on a control signal from the numerical control device 30.

Therefore, the substrate 3 is made of a cylindrical non-magnetic material having an elastic force, or a cylindrical body is fitted into a ring-shaped spring, and a large number of slits are formed in the vertical direction of the circumferential wall of the cylindrical body. Permanent magnet holder 3
A plurality of magnetic attractors 1 and 31 are provided, and magnetic attractors 22 and 22 are hooked and held on each of the magnetic attractors 22 and 22 by elastic fitting.

After a predetermined period of time has elapsed after the start of wire cut electrical discharge machining and a certain amount of machining has been performed on the workpiece 27, the selected solenoid coil 32, 32 is supplied with current from the power supply circuit 36, and the corresponding iron cores 33, 33 receive the magnetic force and are pushed downward. As a result, the pressing tools 34, 34 attached to the lower end of the connecting rod 35 are connected to the cylindrical permanent magnet holder 31,
31 to the outside to open it, detach the magnetic attractors 22, 22, and remove the workpiece 27.
It is adsorbed onto the cutting line 27a formed by the wire electrode 13.

Magnetic attractor 2 from permanent magnet holders 31, 31
2, 22 are removed, the current supplied from the power supply circuit 36 to the solenoid coils 33, 33 is stopped, and as a result, the pressing tools 34, 34
is returned to its original position before the electric current was supplied by the elastic force or spring of the permanent magnet holders 31, 31.

Next, FIGS. 6 and 7 will be explained.

In FIGS. 6 and 7, the same numbers as in FIG. 5 indicate the same components, and 37,
37 is a permanent magnet holder, 37a, 37a are through holes provided in the side walls of the permanent magnet holders 37, 37, 38, 38 are solenoid coil mechanisms, 38
a, 38a are solenoid coils, 38b, 38b
is a spring, 39, 39 is an axially movable iron core, 4
0 and 40 are switches.

Thus, the substrate 3 is provided with a plurality of permanent magnet holders 37, 37 made of a non-magnetic material. The walls of the permanent magnet holders 37, 37 have through holes 37a, 3 for passing the iron cores 39, 39 through them.
7a is provided, and the magnetic attractors 22, 22 are connected to solenoid coils 38a, 38a with a power supply circuit 36.
When no current is supplied from the permanent magnet holder 3 due to the elastic force of the springs 38b, 38b.
It is designed to be held by iron cores 39, 39 extending within 7, 37.

When machining, turn on the start switch of the electrical discharge machining equipment.
When turned ON, the power supply circuit 36 is connected to the numerical control device 30.
A signal is sent to the power supply circuit 36 which receives this signal.
supplies current to each predetermined solenoid coil 38a, 38a, and causes the respective iron cores 39, 39 to be attracted into the solenoid coil mechanisms 38, 38 by the magnetic force of the solenoid coils 38a, 38a. However, when the magnetic attractors 22, 22 are installed in the permanent magnet holders 37, 37 and the switches 40, 40 are pressed, the supply of current from the power supply circuit 36 to the solenoid coils 38a, 38a is stopped, and the iron core 39, 39 extend and close inside the permanent magnet holders 37, 37, and mechanically hook and hold the magnetic attractors 22, 22.

After a predetermined period of time has elapsed after the start of wire cut electrical discharge machining and a certain amount of machining has been performed on the workpiece 27, a selected solenoid is activated by a command from the numerical control device 30 or by the operation of a set timer. Current is supplied from the power supply circuit 36 to the coils 38a, 38a, the iron cores 39, 39 are retracted and opened, the magnetic attractors 22, 22 fall, and the workpiece 27
is placed on the cutting line 27a formed by the wire electrode 13. Therefore, even after the desired processing is completed, it is possible to prevent the cut pieces from bending or falling off due to the cutting lines 27a, 27a.

In addition, arm 1 of this type of wire cut electrical discharge machining equipment
There are various configurations and combinations of the processing head 2 and the suspended guiding method of the wire electrode 13.
A typical example is a pair of arms extending from a single column, or an arm spanning between a pair of columns erected on both sides, and a suspended guide roller, a capstan, and a wire connected to a pinch roller in front of the arm. The processing head 2 is configured to form a suspended guide path for the electrode 13, or the processing head 2 is configured and arranged so as to be able to adjust and fix the processing head 2 vertically with respect to the arm 1 near the tip or center position. Although there are some devices that have this configuration, the present invention can be similarly applied to wire-cut electric discharge machining devices having such a configuration.

Further, the substrate 3 is a workpiece 27 of the processing head 2.
In addition to providing a permanent magnet holder to hold the permanent magnet holder around the processing head 2 in the vicinity of the processing head 2, a permanent magnet holder is also provided so as to protrude from the arm 1 toward the workpiece 27 in a cylindrical shape so as to cover the processing head. It is also possible to configure it so that it is retained. Moreover, in addition to providing a plurality of permanent magnet holders on one substrate 3,
It is also possible to provide a star-shaped substrate consisting of one or more parts, in which arms extend from the processing head 2 in the same shape, e.g. The arm may be configured to be foldable so as to be parallel to the head axis.

In addition to the conventional alnico magnets and ferrite magnets, the permanent magnets used in the magnetic attractors 22, 22 include so-called rare earth alloy magnets such as iron-chromium-cobalt alloy magnets and samarium-cobalt alloy magnets. Magnets can also be used, and in particular, the rare earth alloy magnets mentioned above have an extremely large maximum energy product, and by appropriately selecting the permeance coefficient, for example 20 to 30 mm.
If the workpiece 27 and its cut pieces are not particularly large, a few tens of kilograms or more of weight can be suctioned and held with a φ one, and a few magnetic suction pieces 22, 22 are sufficient. Can be held securely.

Further, in the above embodiment, the magnetic attractors 22, 22
The explanation was based on the assumption that short cylindrical magnet pieces, which may be magnetically attracted to sides other than the NS extreme face, were used as they were, so each permanent magnet holder 20, 31, 37 and permanent magnet holder The magnetic attractor holder part 39 or the holding part 34 of the tool had to be made of non-magnetic material, but the outer peripheral wall of the permanent magnet and the part that comes into contact with the wall of the permanent magnet holder should be made of a non-magnetic material. A magnet with almost no magnetic attraction in areas other than the vicinity of the magnetic poles can be created by covering it, forming a non-magnetic sandwiched part, or arranging the magnetic poles side by side like horseshoe magnets, or by forming them coaxially side by side. It is also possible to manufacture it from a magnetic material if it is constructed and used.

FIGS. 8A and 8B show a cross-sectional view A and a front view B showing an example of such a magnetic attractor 22, in which 41 is a short cylindrical magnet made of, for example, SmCo ₅ ,
42 has a concave shape on one side, and a magnet 4 is placed in the center of the concave part.
1 is a cylindrical iron core, 43 is a synthetic resin or alloy-based annular non-magnetic material interposed as necessary between them, and the magnet 41 and iron core 42 are magnetically attracted to each other. They are fixed together by means of fixing means, etc., or by the above-mentioned non-magnetic material.

In the magnetic attractor 22, the back surface 44 of the iron core 42 and the flange 45 formed on the outer circumferential surface, particularly the outer circumferential surface on the back side, have almost no magnetic attraction ability as a permanent magnet.

〔Effect of the invention〕

Since the present invention is constructed as described above, when wire cut electrical discharge machining is performed according to the present invention, as the electrical discharge machining progresses, the cut part is supported by the uncut part by its own weight and is bent downward, and the cutting part is bent downward. It is possible to prevent the processing accuracy of the inner part from deteriorating, and it is also possible to prevent the cut part from falling off automatically and efficiently without manual intervention.
It is possible to provide a wire-cut electric discharge machining apparatus that can easily detach a magnetic attractor from a permanent magnet holder made of a non-magnetic material at any time.

It should be noted that the present invention is not limited to the embodiments described above; for example, in the device of this embodiment, the permanent magnet holder was opened and closed by a hydraulic cylinder, but an air cylinder or a motor may be used. It is also possible to perform this by using a rod driven by a wire electrode or a solenoid coil, or by bridging the cut piece of the workpiece that has been cut by the wire electrode and both parts of the workpiece. The shape of the magnetic attractor is not limited to a cylindrical shape, and prismatic shapes such as a square pole can also be used, and the design of the present invention can be freely changed within the scope of its purpose. , the present invention encompasses all of them.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the wire cut electric discharge machining apparatus according to the present invention, and FIG.
An enlarged explanatory view of a permanent magnet holder that holds a magnetic attractor made of only permanent magnets of the wire cut electric discharge machining apparatus shown in the figure. Figure 3 is a cut piece fall-off prevention device seen from the direction A-A in Figure 1. Enlarged bottom view of 4th
The figure is an explanatory diagram showing the state of the workpiece at the end of machining when the workpiece is machined using the wire cut electrical discharge machining apparatus according to the present invention. FIG. 7 is an explanatory view showing one embodiment, and FIG. 7 is a partially cutaway explanatory view showing a holding mechanism of a permanent magnet holder that holds a magnetic attractor made of only permanent magnets in FIG. 6. FIGS. FIG. 2 is a cross-sectional view and a front view illustrating an example of an adsorbent made of a permanent magnet and other members. 1...Support arm, 2...Processing head, 3...
Substrate, 4, 5... Guide roller, 6... Current roller, 7, 8... Capstan, 9, 10... Pinch roller, 11, 12... Electrode guide, 13...
wire electrode, 14... holding plate, 16... motor,
17, 18... Gear, 20, 20... Permanent magnet holder, 21, 24b... Spring, 22... Magnetic attractor, 23... Hydraulic cylinder, 23a... Piston, 23b... Piston rod, 24... 4
Port 2 position switching valve, 24a... Solenoid coil, 25... Hydraulic pump, 26... Oil tank, 27... Workpiece, 30... Numerical control device,
33, 39... Iron core, 34... Pressing tool, 35...
Connecting rod, 36...Power circuit, 37
...Permanent magnet holder, 38...Solenoid coil mechanism, 40...Switch.

Claims (1)

[Scope of Claims] 1. A substrate attached to a processing head, a magnetic attractor, at least a part of which is made of a permanent magnet, and capable of adhering to a workpiece by magnetic force, and a magnetic attractor provided on the substrate and said magnetic attractor. consisting of a plurality of permanent magnet holders that are detachably held by mechanical opening and closing without magnetic attraction, an actuator that opens and closes the permanent magnet holders, and a control device that controls the opening and closing of the permanent magnet holders. A wire cut electrical discharge machining device characterized by being equipped with a device for preventing cut pieces from falling off. 2. A patent characterized in that the substrate is rotatably attached to a processing head, and the rotation drive device is controlled by a control device that controls opening and closing of the permanent magnet holder. A wire cut electric discharge machining apparatus according to claim 1. 3. The wire-cut electric discharge machining apparatus according to claim 1, wherein the actuating device for opening and closing the permanent magnet holder is a fluid pressure cylinder. 4. The wire-cut electric discharge machining apparatus according to claim 1, wherein the actuating device for opening and closing the permanent magnet holder is a solenoid coil.