JPH05200630A - Cutter of wire electrode in wire electric discharge machine - Google Patents

Abstract

PURPOSE:To cut a defective front end part of a wire electrode and discard it effectively when the wire electrode is inadvertently disconnected. CONSTITUTION:A sensor 41 and a cutting means 35 are provided on a direction changer 25 for selecting a route of a wire electrode at the time of machining and a route at the time of recovery by a rotational solenoid 51, between a feeding roller 28 for feeding a wire electrode, a first pinch roller 30 and a work, while the position of the front end of a wire electrode feeding side is detected at the time of disconnection of the wire electrode, by a detection signal of the sensor 41. A control means is also provided, by which completion of the recovery of the cutting at the time of disconnection and discarding of a wire electrode 8 of an appropriately fixed length, are detected from the front end part to the feeding side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a cut portion of a wire electrode in a wire electric discharge machine and removing (discarding) the wire electrode by a predetermined length before stretching the wire electrode again. is there.

[0002]

[Technical background] The wire electrode in the wire electric discharge machine is usually thin with a diameter of about 0.05 mm to 0.3 mm. When a machining discharge pulse is applied between the wire electrode and the workpiece to drill a workpiece with a complicated cross-sectional shape, after machining one workpiece, the next workpiece is processed. Before processing the work piece, it is necessary to forcibly cut the wire electrode and stretch it again.

Further, during wire electric discharge machining, the wire electrode may be disconnected due to an abnormal situation such as electric discharge being concentrated in a limited range in a small gap between the wire electrode and the workpiece. Even in that case, it is necessary to re-stretch the wire electrode. In particular, when the wire electrode is broken due to the above-mentioned accident, the broken part (the tip of the wire electrode) and the outer peripheral surface of the wire electrode in the vicinity thereof are often deformed due to the discharge with the work piece, and the gap is left as it is. Since it becomes difficult to pass the tip through a wire guide having a small size, a processing start hole formed at a processing start position, or the like, the work of reattaching the wire electrode becomes troublesome.

Therefore, an inappropriate portion such as a deformed tip portion of the wire electrode is cut by a predetermined size when the wire is broken, and is discarded so that the tip portion of the wire electrode can easily pass through the guide portion or the like. After correction, the wire electrode is attached again. Various cutting devices for this have been proposed.

[0005]

2. Description of the Related Art As a prior art of this type of cutting device, Japanese Unexamined Patent Publication No. 2-237724 discloses cutting under a wire electrode supplying device including a wire electrode supplying bobbin, a braking means, and a feed roller pair. An upper guide for guiding the wire electrode to the upper and lower parts of the workpiece located below the cutting device, which comprises a pair of rollers for applying tension to the wire electrode and a pair of energizers. And a lower guide part, the limit switch connected to the detection plate provided in the collection box of the used wire electrode or the wire electrode in the vicinity thereof as a means for detecting the disconnection state of the wire electrode. There is disclosed a configuration in which a detection circuit is formed between the power supply terminal and the power supply terminal located above the workpiece.

Then, when it is detected from the signal of the detection circuit that the wire electrode is broken due to an accident, the brake means is actuated, and a pair of rollers below the brake means are normally rotated to apply tension to the wire electrode. Then, the cutting device is operated in that state to cut the wire electrode. The pair of rollers are reversely rotated with a slight delay after the operation of the cutting device, and the wire electrode is reversely fed to the wire collecting device arranged on the upper side of the pair of rollers to collect the unnecessary portion. In order to detect the completion of the recovery work at this time, there is disclosed one in which a sensor for detecting the completion of the recovery work of the wire electrode is arranged above the upper guide portion and below the pair of rollers.

[0007]

By the way, as described above, when the wire electrode is broken, the tip portion of the wire electrode which becomes unusable due to the concentrated discharge with the work piece is located within the plate thickness of the work piece. There is only a very limited length of location. In the above-mentioned prior art, although the sensor can detect the completion of the recovery work of the wire electrode of the unnecessary portion after cutting, the position where the wire is broken due to a defect accident, in other words, the length of the wire electrode to be discarded when cutting and discarding. In the prior art, the length of the wire electrode to be cut and removed (discarded) is from the lower part of the cutting device to the broken part in the work piece because the tip position of the wire electrode, which is the reference position for determining the height, cannot be detected. Is prescribed. Therefore, when the distance between the cutting unit and the cutting device becomes long, such as when the collecting device disposes the collecting device between the pair of rollers as tension generating means and the cutting device, the wire electrode to be collected and discarded accordingly. Since the length of the wire is long and the originally normal wire portion is discarded for a long time, there is a drawback that there is much waste.

An object of the present invention is to provide a wire electrode cutting device which solves the above problems.

[0009]

In order to achieve the above object, a wire electrode cutting device in a wire electric discharge machine according to the present invention comprises a detector between a wire electrode supply device and a workpiece. A cutting means is provided, and the position of the tip of the wire electrode supply side is detected by the detection signal of the one detector when the wire electrode is broken, while the wire electrode of a certain length is provided from the tip to the supply side. The control means is provided so as to detect the completion of cutting and collecting when the cutting is performed.

[0010]

EXAMPLE FIG. 1 shows an example embodying the present invention.
~ It demonstrates with reference to FIG. A machining tank 2 is placed on a base 1 of the wire electric discharge machine.
A workpiece W placed and fixed on a work table 3 fixed to the processing tank 2 is immersed in an insulating working liquid (fresh water or a mixed liquid of fresh water and oil) 5 therein. Its working fluid 5
Is supplied from the processing liquid supply device 4, the processing liquid 5 polluted by the processing is collected by the processing liquid supply device, filtered through a filter or the like, and then circulated again to be supplied. In addition, as shown in FIG. 1, an XY table 6 for moving the workpiece W on the XY plane is arranged between the base 1 and the processing tank 2, and its drive is controlled by a drive mechanism (not shown). ..

A wire bobbin 9 around which a wire electrode 8 is wound is provided on the upper part of the column 7, and an upper nozzle 11 is formed on an upper arm 10 supported on the upper part of the column 7. Further, a lower nozzle 13 is arranged on a lower arm 12 supported on the lower portion of the column 7. The wire electrode 8 pulled out from the wire bobbin 9 is connected to the upper nozzle 11
From above to the lower nozzle 13 via the workpiece W in a substantially vertical shape, a pulse current is passed from the power source (not shown) to the wire electrode 8 and the workpiece W, and the wire electrode passes vertically downward. 8 and a small gap between the workpiece W (electric discharge machining part)
The electric discharge machining is performed. It should be noted that the machining liquid 5 is ejected toward the electric discharge machining portion from both or one of the upper nozzle 11 and the lower nozzle 13 to perform the removal of metal scraps in the electric discharge machining and the cooling of the electric discharge machining portion. The wire electrode 8
The transport speed (moving speed) of the
Although there are various types depending on the plate thickness, etc., 100 to 300 m at a plate thickness of about 50 mm
m / sec.

The direction changing pulley 14 is arranged below the lower nozzle 13 to forcibly hold and carry the used wire electrode 8 whose lateral carrying direction has been changed by the direction changing pulley 14. A pair of upper and lower rollers 15, 16
At least one of the rollers is housed in the storage motor 17 (see FIG.
(See (1)), and rotates and drives the wire electrode 8 into a storage box 18 for storing the used wire electrode 8.

Next, the supply portion of the wire electrode 8 will be described with reference to FIGS. 2 and 3. The drive motor 20 that applies a rotating force to the wire bobbin 9 generates a rotating force in a direction opposite to the rotating direction of the wire bobbin 9 during electric discharge machining, applies a pre-tension to the wire electrode 8 during electric discharge machining, and causes a wire tension during wire breakage. A force for unwinding the electrode 8 is applied. Tension is applied to the wire electrode 8 by the pulley 21 that is connected to the powder brake 23 having the rotation sensor 22 and is applied with a braking force.

As shown in FIG. 3, the direction changing table 25 is supported on the frame 24 via a pivot 26 so that the upper end thereof can swing and rotate. The wire guide 27 is provided on the frame 24 above the pivot 26, and the feed roller 28 is provided on the frame 24 below the wire guide 27. The feed roller 28 is a conveyance motor 29 composed of a step motor via a transmission mechanism such as an endless belt (not shown).
Is rotated by.

The first pinch roller 30 is the feed roller 2
8, a first pinch roller 30 is connected to a rotary plate of a rotary first solenoid 31 via a lever 33 that rotates around a pivot 32, and
When the coil of the solenoid 31 is excited, the rotary plate of the solenoid 31 rotates by a certain angle, and when the wire electrode 8 is sandwiched by the feed roller 28 by the first pinch roller 30 via the lever 33 that rotates about the pivot 32. , The wire electrode 8 is conveyed downward. When the excitation of the coil of the rotary first solenoid 31 is stopped, the built-in return spring has a self-recovery function of returning the rotary plate to the original position in the opposite direction.
The direction changing table 25 has a wire guide 34 near the pivot 26.

The cutting means 35 provided on the direction changing table 25 includes a pair of current carrying members 37 and 38 for mounting a holder 39 provided on the rotation support shaft 36 and the holder 39 to the rotation support shaft 36.
It is composed of a rotary second solenoid 40 that rotates around, and the rotary second solenoid 40 is excited to energize from a power source (not shown) in a state in which the pair of conducting electrons 37 and 38 are in contact with the wire electrode 8. As a result, the wire electrode 8 between the electrons 37, 38 is melted. The rotary second solenoid 4
0 also has a self-recovery function like the rotary first solenoid 31.

A sensor 41 for detecting a wire electrode is provided on the direction changing table 25 below the cutting means 35, and wire guides 42 and 43 are provided above and below the sensor 41.
Even when the wire electrode 8 is disconnected due to an accident as described later, the wire electrode 8 is located in the pair of wire guides 42 and 43, so that the wire electrode 8 is out of the detectable range of the sensor 41. It is for holding so that it does not exist.

The feed roller 44 is provided on the frame 24 below the wire guide 43, and the second pinch roller 45 provided opposite to the feed roller 44 is the feed roller 44.
Is rotated by a delivery motor 46 which is a step motor through a transmission mechanism such as an endless belt (not shown). The second pinch roller 45 is connected to a rotary plate of a rotary third solenoid 49 having a self-recovery function similar to that described above through a lever 48 that rotates around a pivot shaft 47. When the coil of the third solenoid 49 is excited, its rotary plate rotates by a certain angle, and the second pinch roller 45 clamps the wire electrode 8 to the feed roller 44 via a lever 48 that rotates around a pivot shaft 47. Then, the wire electrode 8 is conveyed downward. The feed mechanism having these configurations operates only when the wire electrode 8 is cut, and does not operate during electric discharge machining.

Further, the wire guide 50 is attached to the frame 24.
It is provided at the lower end of. The rotary fourth solenoid 51 is for driving the direction changing table 25 to swing right and left around the pivot 26, and is connected to the direction changing table 25 via a swing lever 52. This rotary fourth solenoid 5
When the coil No. 1 is excited, its rotary plate rotates by a certain angle and pulls the swing lever 52. As a result, the direction changing table 25 is rotated so that the lower end opening of the wire guide 50 at the lower end of the direction changing table 25 faces the upper end direction of the wire electrode collection box 53 (see FIG. 4).

On the contrary, when the excitation of the coil of the rotary fourth solenoid 51 is stopped, the built-in return spring has a self-recovery function of returning the rotary plate to the original position in the opposite direction. As a result, the direction changing table 25 is arranged so that the lower end opening of the wire guide 50 faces the upper end opening of the tubular guide body 54 arranged adjacent to the recovery box 53.
Position returns (see FIG. 3). The lower end of the guide body 54 is for guiding the wire electrode 8 toward the upper guide 62 during processing.

As shown in FIG. 5, a central processing unit (CPU) 55 as a control device for the wire electric discharge machine has a control program for the entire wire electric discharge machine and a control program for cutting and collecting the wire electrode 8 which will be described later. Read-only memory (ROM) 56 in which is stored in advance, and readable / writable memory (RAM) in which various data are temporarily stored
57 and an interface (not shown), and a CPU
Reference numeral 55 indicates a fusing power source and an electronic conductor 3 in the cutting means
The switch 58, the wire electrode detecting sensor 41, and the rotation sensor 22 are connected to the housing motor 17, the drive motor 20, and the powder brake 23 via a drive circuit (input / output driver circuit) 59. , Transport motor 29, feed motor 46, rotary solenoid 31,
40, 49 and 51 are connected.

Next, in the wire electric discharge machine configured as described above, regarding the action of the sensor 41 when the wire electrode 8 is suddenly disconnected and the control for collecting the unnecessary portion of the wire electrode 8 by a predetermined length, Description will be given according to the flowcharts shown in FIGS. 6 and 7. When a start button (not shown) is operated, electrical discharge machining is executed (S2) following the initial setting (S1). In this state, the drive motor 20 is provided with a rotational force that applies a pre-tension to the wire electrode 8. Further, since the wire electrode 8 is detected by the wire electrode detecting sensor 41, the output signal of the sensor 41 is ON. At this time, during the processing, it is always judged whether or not the wire electrode 8 is broken at the location of the workpiece W (S3).

When the wire electrode 8 is broken, the rotation of the pulley 21 is stopped and the rotation sensor 22 detects it (S3, yes). In this case, the broken wire electrode 8 is in a free state, so that the rotational force of the drive motor 20 acts as a force in the direction of rewinding the wire electrode 8 (direction of arrow A). It is rewound in the direction (S4). Then, the sensor 4 for detecting the wire electrode
It is determined whether 1 is turned off (S5). When the rewinding of the wire electrode 8 progresses and the tip of the wire electrode 8 is located above the sensor 41, the output signal of the sensor 41 is turned off. Output signal of sensor 41 is OFF
If (S5, yes), the rotation of the drive motor 20 is immediately stopped (S6), and then the rotary fourth solenoid 5
When 1 is excited (ON) (S7), the direction changing table 25 is rotated around the pivot 26, and the position is changed so that the lower end opening of the wire guide 50 at the lower end of the direction changing table 25 is above the recovery box 53. (See FIG. 4).

While keeping the position of the direction changing table 25 in this state, the rotary first solenoid 31 is excited to sandwich the wire electrode 8 between the feed roller 28 and the first pinch roller 30, and then the carry motor 29. Drive (arrow B in FIG. 4)
When the wire electrode 8 is rotated in the normal direction (S8), the tip portion (disconnection) of the wire electrode 8 is sent toward the collection box 53. Then CP
The timer provided in U55 is reset to 0 (S
9). When the tip of the wire electrode 8 passes through the location of the sensor 41 and goes downward, the output signal of the sensor 41 changes to an ON signal.

Next, it is determined whether or not a fixed time (To) has elapsed, that is, whether or not the value t of the timer has reached the time value To stored in the ROM 56 (S10). After a lapse of this fixed time, it means that the wire electrode 8 is extended downward by a fixed dimension from the tip portion (disconnection portion) of the wire electrode 8 detected by the sensor 41 in S5. It should be noted that this fixed dimension is a dimension beyond a certain range in which it can be estimated that the wire electrode 8 is defective due to deformation of the upper surface of the wire electrode from the broken portion of the wire electrode 8 due to wire breakage, electric discharge machining, etc. If 100 ~
The predetermined time (To) is stored in the ROM 56 in advance so that about 120 mm is discarded (discarded).

When it is determined that the predetermined time (To) has elapsed (S10, yes), the rotary first solenoid 3
1 is turned off and the carry motor 29 is stopped (S
11). Next, the rotary second and third solenoids 40 and 49
Is turned on and the feed motor 46 is driven, the feed roller 44 is rotated in the direction of arrow C (S12), and the switch 58 of the power supply in the cutting means is turned on to turn on the electronic device 3.
A current is applied to 7, 38 (S13).

As a result, the feed roller 28 and the first pinch roller 30 in the stopped state at the upper position, and the feed roller 44 and the second pinch roller 45 rotating in the arrow C direction at the lower position are nipped and tensioned. The wire electrode 8 provided with is melted and cut at 37 and 38 conduction points. At this time, the cutting portion of the wire electrode 8 melted in the pulled state has a needle-like pointed tip, so that it can be easily inserted later into the upper and lower guides 62, 63 and the processing start hole in the workpiece W. Become.

Since the feed roller 44 is rotated in the C direction by the operation of the feed motor 46, the wire electrode 8 is cut and at the same time the cut wire electrode 8 is fed into the recovery box 53 by its own weight. .. When the cutting and collecting work is completed in this way, the wire electrode 8 is not detected at the location of the sensor 41, so the output signal from the sensor 41 is OF
The F signal is output, and the determination result in S14 as to whether the output signal of the sensor 41 is OFF is yes. Then, the switch 58 is turned off to cut off the electric current to the electrons 37, 38 (S15). Then, the second and third solenoids 40, 4
9 is turned off and the feed motor 46 is stopped (S16), the passage above the wire guide 50 is opened, and the rotary fourth solenoid 51 is turned off to return the direction changing table 25 to the original position. It returns (S17). As a result, the lower end opening of the wire guide 50 faces the upper end of the original tubular guide body 54.

In this way, when the wire electrode 8 is unexpectedly broken, the one sensor 41 controls the cutting of the broken part on the wire electrode supply side by a certain length to discard and recover it.
And its control means (CPU 55 or the like) can be easily executed. Therefore, in the wire electric discharge machine, even when the wire electrode is unexpectedly disconnected, only the defective portion due to the disconnection accident can be surely discarded, and the next wire electrode 8 can be reliably stretched again. That is the effect.

The rotary solenoids 31, 40, 49
Needless to say, may be replaced by a direct-acting electromagnetic solenoid, and the cutting means may be of another type.

[0031]

As described above, according to the present invention, one detector and a cutting means are provided between the wire electrode supply device and the workpiece in the wire electric discharge machine, and the one detector The detection signal can detect the position of the tip of the wire electrode supply side when the wire electrode is broken, and can detect the completion of cutting and collection when the wire electrode of a certain length is cut from the tip to the supply side. Since the control means for controlling is provided, it is possible to reliably discard only the defective portion due to the wire electrode disconnection accident, and it is not necessary to discard the originally normal wire portion for a long time, so that there is no waste. Play. In addition, since one detector can detect the tip portion of the wire electrode disconnection and the wire electrode cutting and disposal / collection work, the cost of the wire electric discharge machine can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic side view of a wire electric discharge machine.

FIG. 2 is a side sectional view of a wire electrode cutting and collecting unit.

FIG. 3 is a side cross-sectional view of a wire electrode cutting and collecting unit during electric discharge machining.

FIG. 4 is an explanatory diagram of a state in which the position of the rotary table is changed.

FIG. 5 is a block diagram showing a control device.

FIG. 6 is a flowchart of control.

FIG. 7 is a continuation of the control flowchart.

[Explanation of symbols]

 W Workpiece 3 Worktable 4 Processing liquid supply device 8 Wire electrode 9 Wire bobbin 17 Storage motor 20 Drive motor 21 Pulley 22 Rotation sensor 23 Powder brake 24 Frame 25 Direction conversion table 26 Axis 27, 34, 42, 43 Wire guide 28, 44 Feed Roller 29 Transport Motor 30,45 Pinch Roller 31, 40, 49, 51 Rotating Solenoid 36 Rotating Spindle 37, 38 Conductor 41 Sensor 46 Sending Motor 50 Wire Guide 52 Swing Lever 53 Recovery Box 54 Guide Body 55 Center Processor (CPU) 56 Read-only memory (ROM) 57 Read / write memory (RAM) 58 Switch 59 Drive circuit

Claims (1)

[Claims] 1. A detector and a cutting means are provided between a wire electrode supply device and a workpiece, and a detection signal of the one detector is used to detect the wire electrode supply side when the wire electrode is disconnected. A wire electric discharge machine is provided which is provided with a control means for detecting the position of the tip part and detecting the completion of cutting and recovery when the wire electrode of a certain length is appropriately cut from the tip part to the supply side. Device for wire electrode in machine.