JPH0615530A - Wire cut electric discharge machine - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object of the present invention to provide a wire-cut electric discharge machine capable of overlapping the operations of stretching a wire electrode and shortening the stretching time. [Structure] At the cutting position where the direction changing table 25 is moved in the direction of the collecting box 53, the wire electrodes 8 are moved by the conducting electrons 37 and 38.
When is cut, the direction changing table 25 is moved to the initial position in the direction of the guide body 54. In the movement process, the wire electrode 8 sandwiched between the feed roller 28 and the first pinch roller 30 is fed toward the workpiece, and the wire electrode 8 is fed continuously even after being moved to the initial position. Then, the wire electrode 8 is automatically stretched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire cut electric discharge machine for moving a wire electrode and a work piece relative to each other to perform a predetermined work on the work piece.

[0002]

2. Description of the Related Art A wire electrode in a wire electric discharge machine is usually thin and has 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 complex cross-sectional shape in the workpiece, after the machining of one workpiece is completed, the next workpiece is processed. Before the work piece is processed, it is necessary to forcibly cut the wire electrode once 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 accident, the broken part (the tip of the wire electrode) and the outer peripheral surface of the wire electrode in the vicinity of the broken part are often deformed by the discharge with the workpiece, and the gap is left as it is. 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, and the work of re-tensioning the wire electrode becomes troublesome.

Therefore, an inappropriate portion such as a deformed tip portion of the wire electrode is cut to 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 stretched again. Various devices have been proposed for that purpose.

For example, Japanese Patent Application No. 4 filed by the present applicant earlier
In No. 12248, a wire guide provided under a rotatable direction changing table between a wire electrode and a workpiece is provided with a rotary solenoid for processing the wire electrode and a path for discarding the wire electrode. And the wire guide is exposed in advance to the discarding path, the tip of the wire electrode is fed, and then the wire electrode is cut by the cutting means and discarded in the discarding section. After that, when it is detected that the wire electrode is collected in the discarding unit, the direction changing table is returned to the original position, and then the wire electrode stretching operation is performed.

[0006]

However, since a lot of continuous movements are required for the work of stretching the wire electrode,
The next operation is performed after waiting for the completion of each operation, which takes a very long time.

The present invention has been made in order to solve the above-mentioned problems, and provides a wire-cut electric discharge machine capable of shortening the stretching time by overlapping the operations involved in stretching the wire electrode. The purpose is to provide.

[0008]

To achieve this object, in the wire cut electric discharge machine of the present invention, it is possible to move between an initial position for inserting a wire electrode and a cutting position for cutting the wire electrode. Moving means, cutting means for cutting the wire electrode at the cutting position of the moving means, and wire electrode feeding means for feeding the wire electrode cut by the cutting means toward the workpiece. And controlling the wire electrode feeding means so as to feed the wire electrode in the process of returning the moving means to the initial position after the wire electrode is cut by the cutting means at the cutting position of the moving means. And a control means.

[0009]

In the wire-cut electric discharge machine of the present invention having the above structure, the moving means moves from the cutting position to the initial position after the cutting means cuts the wire electrode while the moving means is moved to the cutting position. In the process of returning, the control means controls the wire electrode feeding means to start feeding the wire electrode.

[0010]

EXAMPLE FIG. 1 shows an example embodying the present invention.
~ It demonstrates with reference to FIG.

On the base 1 of the wire electric discharge machine,
The processing tank 2 is placed, and the processing tank 2 is placed in the processing tank 2.
The workpiece W mounted and fixed on the work table 3 fixed to the above is immersed in the insulating machining liquid 5. The processing liquid 5 is supplied from the processing liquid supply device 4, and 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.

Further, between the base 1 and the processing tank 2 is shown in FIG.
As shown in, X to move the workpiece W on the XY plane.
A Y table 6 is arranged and driven and controlled by a driving 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. 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. In addition, 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 remove metal scraps in the electric discharge machining and cool 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 nip 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. 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. Further, the powder brake 2 equipped with the rotation sensor 22 at the time of electric discharge machining
The wire electrode 8 is sandwiched between the pulley 21 and the pinch roller 19 which are connected to the pulley 3 and are provided with a braking force, and a predetermined tension is applied to the wire electrode 8.

As shown in FIG. 3, the direction changing table 25 is swingably supported by the frame 24 via a pivot 26 at the upper end thereof. 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 rotated by a conveyance motor 29 composed of a step motor via a transmission mechanism such as an endless belt (not shown).

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 nipped 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 rotary support shaft 36 and the holder 39 to the rotary 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.

The sensor 41 for detecting the wire electrode is provided on the direction changing table 25 below the cutting means 35, and the 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 there is no.

The feed roller 44 is provided on the frame 24 below the wire guide 43, and the second pinch roller 45 provided opposite 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 via a lever 48 which rotates about a pivot shaft 47. When the coil is excited, the rotary third solenoid 49 rotates its rotating plate by a certain angle, and the second pinch roller 45 sends the wire electrode 8 to the roller via the lever 48 which rotates about the pivot shaft 47. When rotated so as to be sandwiched by 44, 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 direction changing table 2.
It is provided at the lower end of 5. Rotating fourth solenoid 51
Is for swinging and rotating the direction changing table 25 to the left and right around the pivot 26, and is connected to the direction changing table 25 via a swing lever 52. When the coil of the rotary fourth solenoid 51 is excited, the rotary plate thereof 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 for 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. 7, 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 a 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 constructed as described above, as to the control for recovering the unnecessary portion of the wire electrode 8 by a predetermined length when the wire electrode 8 is suddenly broken, FIG. 8 and FIG. It will be described according to the flowchart shown in FIG.

When a start button (not shown) is operated, electrical discharge machining is executed following the initial setting (S1) (S).
2). In this state, the drive motor 20 has the wire electrode 8
A rotational force is applied to give a pre-tension to. Further, since the wire electrode 8 is detected by the wire electrode detecting sensor 41, the output signal of the sensor 41 is ON.
Is. 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. The output signal of the sensor 41 is OF
When it becomes F (S5, yes), the rotation of the drive motor 20 is immediately stopped (S6), and when the rotary fourth solenoid 51 is excited (ON) (S7), the direction changing table 25 moves around the pivot 26. The rotation is changed so that the lower end opening of the wire guide 50 at the lower end of the direction changing table 25 is located above the recovery box 53.

While maintaining 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. Next, 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.

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, 4
9 is turned on, 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 conduction 3
A current is applied to 7, 38 (S13) (see FIG. 4).

As a result, the pulley 21 and the pinch roller 19 in the stopped state at the upper position, the feed roller 44 and the second pinch roller 4 rotating in the arrow C direction at the lower position.
The wire electrode 8 which is sandwiched between the electrodes 5 and 5 and which is given a tension is melted and cut off at the conductions 37 and 38. 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 rotating in the C direction by the operation of the feed motor 46, the wire electrode 8 is cut at the same time and the cut wire electrode 8 is fed into the recovery box 53 by its own weight (FIG. 5). reference).

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 becomes an OFF signal,
The determination result of whether the output signal of the sensor 41 is OFF in S14 is yes. Then turn off the switch 58.
Then, the electric current to the conduction electrons 37 and 38 is cut off (S15).
Next, by turning off the second and third solenoids 40 and 49 and stopping the delivery motor 46 (S1
6) Open the passage above the wire guide 50.

Further, the 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 is driven (in the direction of arrow D in FIG. 6) to rotate forward. Then (S17), a new wire electrode 8 whose tip is cut is sent in the direction of the wire guide 50. Further, almost simultaneously with S17, the rotary fourth solenoid 51 is turned off to return the direction changing table 25 to the initial position (S18). As a result, when the direction changing table 25 is returned to the initial position and the lower end opening of the wire guide 50 faces the upper end of the original tubular guide body 54, the tip of the wire electrode 8 reaches near the upper end of the wire guide 50. Then, the wire electrode can be automatically stretched (see FIG. 6).

In this embodiment, from the time the wire electrode 8 shown in FIG. 5 is cut and a command to return the direction changing table 25 to the initial position is output until the direction changing table 25 is actually moved to the initial position. It took 2 seconds, and the time required for the wire electrode 8 shown in FIG. 5 to reach the upper end of the wire guide 50 from the cut state of the wire electrode 8 was 2.5 seconds. Therefore, in the case where the movement of the direction changing table 25 and the feeding of the wire electrode 8 are sequentially performed after the wire electrode 8 is cut in the related art, it takes 5 seconds if the confirmation operation is included until the state of FIG. 6 is reached. In contrast to this, in the present embodiment, the state of FIG. 6 can be reached in 2.5 seconds only for the operation of feeding the wire electrode 8.

The present invention is not limited to the above embodiment, but various modifications can be made.

For example, the direction changing table 25 is not limited to the one that swings to the left and right, but the one that moves up and down or that the wire electrode 8 is gripped and transferred to another place in order to discard the wire electrode 8. It may be one.

Further, the timing of feeding the wire electrode 8 is determined based on the signal for turning off the fourth solenoid 51 to the first
The solenoid 31 may be turned on and the transport motor 29 may be driven. In short, if the operation relating to the automatic stretching of the wire electrode 8 is duplicated, the optimum operation timing is set according to the time required for each operation. Should be selected.

Further, rotary solenoids 31, 40, 4
It goes without saying that 9, 51 may be replaced by a direct-acting electromagnetic solenoid, a motor or the like, and the cutting means may be of another cutter type.

[0039]

As is apparent from the above description, in the wire cut electric discharge machine of the present invention, the wire electrode is fed in the process of returning from the position where the wire electrode is cut to the position where the wire electrode is inserted. Since it is started, there is an effect that the time required for the work of stretching the wire electrode can be shortened.

[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 showing a state in which the position of the rotary table is changed.

FIG. 5 is an explanatory diagram showing a state in which the wire electrode is cut.

FIG. 6 is an explanatory diagram showing a state in which a wire electrode is fed.

FIG. 7 is a block diagram showing a control device.

FIG. 8 is a flowchart of control.

FIG. 9 is a continuation of the control flowchart.

[Explanation of symbols]

 W Workpiece 8 Wire electrode 25 Direction conversion table 28,44 Feed roller 29 Conveyor motor 30,45 Pinch roller 31, 40, 49, 51 Rotary solenoid 37, 38 Conductor 41 Sensor 46 Sending motor 52 Swing lever 55 Central Processing unit (CPU) 56 Read only memory (ROM) 57 Read / write memory (RAM) at any time

Claims (1)

[Claims] 1. A wire-cut electric discharge machine for moving a wire electrode and a work piece relative to each other to perform a predetermined work on the work piece, wherein an initial position for inserting the wire electrode and the wire electrode are cut. To the cutting position for cutting, the cutting means for cutting the wire electrode at the cutting position of the moving means, and the wire electrode cut by the cutting means toward the workpiece. A wire electrode feeding means for feeding, and a wire electrode feeding means for cutting the wire electrode by the cutting means at the cutting position of the moving means, and then for feeding the wire electrode in the process of returning the moving means to the initial position. A wire-cut electric discharge machine comprising: a control means for controlling the wire electrode feeding means.