JPS58177234A - Automatic supply method of wire in wire cut electric discharge machining device - Google Patents

Abstract

PURPOSE:To improve reliability in the automatic supply method of a wire, by detecting supply failure due to a trouble to again repeat and successfully perform automatic supply of the wire during its automatic supply to an electric discharge machining device. CONSTITUTION:To detect supply failure of a wire electrode 2, detection for a change of advancing speed of the wire 2 is only required, and the change is detected by replacing the speed to the intermittent motion of a direction changing pulley 5. An encoder 91 is mounted to the pulley 5 to output AC voltage in a range 0-5V, and a DC component is cut by a capacitor C1 and a resistor R1. Then R3/R2 times amplification is performed by an OP amplifier 92. At the time of a waveform W3, a relay coil L1 is in an OFF condition, and the occurrence of intermittent motion of the pulley 5 can be detected. Further from an OFF condition of a relay coil L2, the electrode 2 located out of its insertion route can be detected. Then a newly fed wire electrode is again automatically supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for automatically feeding wire in a wire-cut electrical discharge machining apparatus, by detecting feeding failure due to trouble during automatic wire feeding.

This article relates to a method for redoing automatic wire feeding and achieving success.

First, the configuration of a conventional automatic wire feeding device will be explained with reference to FIG.

In the figure, (1) is a wire supply reel, which is connected to a torque motor (not shown), and is configured to apply reverse torque to obtain enough braking force to prevent the wire electrode (2) from slackening. (3) is a brake roller connected to an electromagnetic brake (not shown). (4) The holding roller is pressed against the brake roller (3) by spring force. The wire electrode (2+U) is sandwiched between the brake roller (3) and the presser roller (4), and a constant tension is applied to it without slipping.

(5) is a direction conversion roller, and (6) is a positioning die.

The inner diameter is slightly larger than the diameter of the wire electrode (2). (7) is a pinch roller for wire feeding.

(8) This is a foot roller for feeding Hawaiian. The above roller (
7) is rotated by the pinch roller motor Q0 attached to the lifting plate (9) only during automatic wire feeding. Also, the roller (8) is moved by the spring force to the roller (7).
During automatic wire feeding, the wire electrode (2) is fed downward in the figure without twisting or slipping between the rollers (71, (81).Positioning The wire electrode (2) does not come off between the rollers f71 and (81) due to the die (6).

The elevating and lowering of the elevating plate (9) is coupled to the elevating member αl) by a coupling a2. A pole nut is attached to the back side of the lift plate (9), which is operated by the rotation of the ball screw, on the back side thereof, for converting the rotation of the ball screw at the 0th floor into vertical linear motion. This ball screw U
One end is supported by a motor attachment part α9 attached to the U lift guide I, and the other end is supported by a bearing αQ, making it a two-end support system. In addition, since the elevating plate (9) is supported in elevating and lowering by the elevating guide α4, accurate vertical linear movement is possible.

Further, a pipe guide (1?) is fixed to the elevating plate (9) via a guide fixing plate α16. This pipe guide 0η rises and falls as the elevating plate (9) moves up and down, so
It is supported by the bearing α value to prevent vibration.

Further, a die guide rod for fully supporting the wire electrode (2) is attached to the tip of the pipe guide αη.

Note that bearings 019 and α9. Lifting guide α is fixed plate Q
attached to υ.

Next, @ is the cutting motor, and (c) is the arm rotation motor, both of which are fixed in one box (2). (c)
is a wire cutting part, (e) is a cutting arm, and @ is a tray for discarding wire chips after cutting the wire. And the above cutting device (goods) and saucer (goods).

It is attached to the fixed plate C11). Note that the details of the cutting device C4 and the wire cutting section (c) will be described later.

During processing, the pipe guide θη is pressed and fixed against the reference groove plate (c) by a plate. This reference V-groove plate @ is received by the V-groove surface so that it fits in the above pipe guide + 17) so that its position is determined.The reference ■ groove plate @ is.

It is always fixed to one box (7), and nine boxes (31 is fixed plate C)
! attached to υ. Further, a nozzle (to) for jetting the machining liquid 001 and supplying it to the machining section 03 is attached to the 9th box (to).

In addition, the pipe guide (lη) has three notches as shown in Figure 9, and during machining, the power supply pin, (
) is in contact with the wire electrode (2) at three points, and power is supplied from here. The power supply pin (b) is connected to the movable plate (to)
When the pipe guide an moves up and down, it moves to the right in Figure 9 to avoid contact. Similarly, the power supply pin (to) is fixed to the movable plate On, so that when pressed to the left in FIG. 1, it moves together with the plate. (to) is the workpiece.

0I is a table.

Next, Gll is the lower die guide, (4D is the lower power feeding die. Both are fixed to the box (4) and attached to the lower arm (4~).

The box (42) is equipped with a nozzle (78) for supplying 0υ of machining fluid to 0 machining sections, and a guide nozzle (44) for guiding all of the wire electrodes (2).
is installed.

The wire electrode (2) has passed through the guide nozzle (44).

The belt roller (45) moves forward while being sandwiched between the lower belt (4η) stretched to 4fil and the lower roller (marked 4).

It is guided to the trumpet tube (49). Then the wire electrode (
2) passes through the 1 collection pipe (50) and the collection belt (53) stretched over the 9 collection rollers (51) and (52).
The wire electrode (2) is sandwiched between the collection roller (54) and the collection box (55), and is guided to the collection box (55) as shown in Figure 1.
are discarded in a circle. In addition, the feeding speed of the wire electrode (2) is variable by the rotation of a motor with a reduction gear attached to the back in the figure of the 9 collection roller (54). It is belt-transmitted.

Moreover, since both rollers (415I) have the same diameter, they rotate synchronously. Therefore, the wire electrode (2)
The friction force due to the lower roller (Kabe) and the collection roller (
54) As a result, the wire is pulled without slipping and collected into the collection box (55). Next, there is a device for cutting the wire electrode (2), (c), (
wealth).

The configurations (c) and (c) will be explained using FIG. 2.

(56) is a cutter for cutting the wire electrode (2), and is fixed to a screw (57) and a movable rod (58). A wire electrode (
2) Support rod (59) that supports it so that it does not move when cutting.
) is fixed, and rubber (60) is glued to the contact part, making it smooth. ) completely prevented.

Also, (61) is the cutting plate, which can be fixed by screws (62).
It is fixed to the cutting arm (c). The above cutting plate (6
1) Nitr1. The wire electrode (64) is glued to prevent the wire electrode (2) from bending.
By moving the moving rod (58) to the left in the figure between the cutting receiving plate (61) and the cutter (56).

It is cut and simultaneously supported between rubber (60) and (64). The right end of the movable rod (58) in the figure is threaded, and after inserting the compression spring (65)', a locking nut (66) is screwed in to fix it. Moving rod (58)
The horizontal movement of is performed by a half-rotation operation of the eccentric cam (67). The figure shows a case where the eccentric cam (67) is at the rightmost end, and the moving rod (58) is also at the right end due to the restoring force of the compression spring (65). Conversely, when cutting the wire electrode, the eccentric cam (67) rotates half a turn to the leftmost position, so the movable rod (58) and stopper (C66) are located at the left end, and the cutter (56) ) and the cutting plate (61).

Next, we will explain the rotation of the cutting arm (E). When the arm rotation motor (C) attached to the HVc rotates,
The gear (70) is attached to the shaft by the gear (69).
) rotates. The gear (70) is.

It is identified as an arm rotation rod (71), and is further connected to a cutting arm (E). The arm rotating rod (71) is supported by bearings (72) and (7+).

However, as the arm rotation motor (C) rotates approximately half a rotation, the cutting arm (C) rotates 180 degrees in the opposite direction in FIG. 9 and then stops. The position 180° opposite to the position shown in the figure can be determined by detecting it with a limit switch or the like.

Next, the rotation of the eccentric cam (67) will be explained.

An eccentric cam rotating rod (74) is inserted into the center of the arm rotating rod (71), as can be seen in the interrupted section in Figure 1, and is capable of nine rotations. An eccentric cam (67) is fixed to the lower end of the eccentric cam rotating rod (74), and a bearing (75)
Yo! It can rotate smoothly.

Further, the upper end is connected to a cutting motor (c) via a coupling (76). Therefore, cutting arm 4
When the arm rotation motor (c) rotates to position it on the opposite side by 180 degrees, the cutting motor (c) simultaneously rotates.
By starting up and rotating 180 degrees, the relationship between the eccentric cam (67) and the locking nut (66) in the figure does not change, so the wire electrode (2) is connected to the cutter (5) and the cutting plate (61). ).Then, by further rotating only the cutting motor (a) by 180 degrees, the moving rod (58) moves in the direction of the cutting receiving plate (61), as described above. The wire electrode (2) can be completely cut off. After that, the arm rotation motor @ is rotated 180° in the opposite direction to return it to the position shown in Figure 1, with the cutting motor (2) still stopped. Then, by rotating the cutting motor (c) by 30° in reverse VCl, the state shown in Fig. 1 can be restored.

Next, referring to FIG. 3, the operation of completely cutting the wire electrode (2) will be explained.

First, FIG. 3(a) shows a case where the wire electrode (2) is initially set to pass through the machining start hole (77) of the workpiece (to) and the cutting operation is started. That is, FIG. 1 shows the initialized state. First, there is a movable plate (to) to which power supply pins (b) and (c) are attached so that the pipe guide ση moves up in the direction of the arrow in the figure.

c37) and moving plate C17) are attached, the plate moves in the direction of the arrow in the figure.

In addition, the pipe guide fin is located at a certain fixed position (11). It will rise to the position and stop.

At this time, as described in Fig. 1, the wire feeding pinch roller (7) and the wire feeding leg roller (8) rise and stop together with the pipe kite αη, and rotate as shown by the arrow in Fig. 1. I'm starting to do it.

Standard ■Groove plate @ is always fixed and pipe guide t
When one moves up and down, it rubs. Note that the nozzle 03 is always fixed. The die guide rod has enough clearance to scrape the wire electrode (2) when the pipe guide αD rises. (a) The lower end position of the die guide holder in the figure will be called the cutting position.

Next, in FIG. 3(b), the cutting arm +
It shows the state in which it has been rotated by 41 degrees. With this, the wire electrode (2) is positioned at the cutting part (c).0 The cutting motor (2) and the arm (b)
The operation of the diversion motor (c) is the same as described in FIG. At this time, the wire feeding pinch roller (7) and the wire feeding leg roller (8) are stopped (12). Moreover, the pinch roller (7) is
) A one-way clutch (not shown) is attached to prevent rotation in the direction opposite to the arrow direction.

Next, FIG. 3(Q) shows the state after the wire electrode (2) is actually cut. That is, as described in FIG. 2, after cutting, the cutting arm (c) rotates 180 degrees and returns to its original position. The lower part of the wire electrode (2) after cutting detects that the cutting motor blade has further rotated 180 degrees as described in FIG. 2, and the collection roller (54) in FIG. Since it starts, it is collected in the 9 collection box (55).

Next, FIG. 3(d) shows a state in which the wire electrode (2) has actually been completely cut. In other words, after the state shown in Fig. 3(c) is completed, the movable plate is moved in the initial state of the knob guide (11 in Fig. 3C&) until it reaches the state shown in Fig. 3(, i). (7), 6 pieces are still moving, and now the position of the pipe guide (17) is the same as in Figure 1.The lower end of the die guide handle at this time is called the fixed position. Note that while the pipe guide a1 is descending, the wire electrode (2) is moved by the wire feeding pinch roller (
Since the pinch roller (7) is sandwiched between the wire feeding foot roller (8) and the wire feeding foot roller (8), it may be difficult to remove the wire from the tip of the die guide wire. It will not come out upwards. Cutting is completed when the state shown in FIG. 3(d) is reached. Note that during the cutting operation shown in FIGS. 3(a) to (d).

The braking force of the electromagnetic brake connected to the brake roller (31) in FIG. 1 is extremely weakened.

Next, referring to FIG. 4, the insertion operation of passing the wire electrode (2) through the entire machining start hole and the lower die guide will be described.

Here, the process of passing the wire electrode through the machining start hole, then the lower die guide, and sending it to the collection box (55) in FIG. 1 will be referred to as the insertion operation of the wire electrode (2). First, the state shown in FIG. 4(a) is the initial state of the wire insertion operation. This is the same state as the final state of the cutting operation in FIG. Namely.

The upper die guide frame, the machining start hole (77), and the lower die guide frame are aligned in the vertical direction.Next, as shown in FIG. 4(b), the pipe guide α
Lower the η, pass it through the processing start hole (77), and make the upper die guide face and the lower die guide (41k) face each other.The lower end of the upper die guide face in this state is called the lower limit. .

This position is detected by a limit switch or the like.

Next, as shown in FIG. 4(c), the wire electrode (2) sandwiched between the wire feeding pinch roller (7) and the wire feeding leg roller (8) is Start progressing. FIG. 4(C) shows a state where the lower die guide (40k wire electrode (2)) has passed.

After that, the wire electrode (21f
It passes through the power supply die (41) and the guide nozzle (44)' and is guided to the lower belt (4η).The lower roller (c) and the collection roller (54) are referred to as the pinch roller (7) in FIG. The lower roller (IIQ) and the collection roller (54) are synchronized by the H belt transmission. Therefore, the wire electrode (2) When the belt (47) advances to the entrance of the lower roller decoy, it is drawn in and guided between the two.

It is collected into a collection box (55) as shown in FIG. Here, by performing all contact sensing between the power feeding die (41) and the collection box (55), the wire electrode (2) is connected to the collection box (55).
). After the contact is sensed in this way, the pipe guide αη rises to the fixed position and corrects itself as shown in FIG. Move in the direction of the arrow to fix the pipe guide (1?) and become ready to feed power to the wire electrode (2) using the power supply bottle. Now it is possible to start machining, and at the same time
The state shown in the figure (,i) is the completion of the insertion operation. In addition, the third
Similar to the cutting operation shown in the figure, during the insertion operation shown in FIG. 4, the braking force of the electromagnetic brake connected to the brake roller (3) shown in FIG. 1 is extremely weakened.

(16) As described above, the conventional wire automatic feeding method is a method in which a cutting operation is performed every time the machining start hole changes, and then an insertion operation is performed to automatically bring the wire into a state where machining can be performed.

Next, we will explain the shortcomings during the insertion operation in this conventional automatic wire feeding method. There are a wide variety of troubles, but we will explain troubles that make it impossible to continue the insertion operation with reference to Figures 5 and 6. Figure 5 (a)
), (b), consider the case where the distance between the lower surface of the workpiece (to) and the upper end surface of the lower nozzle (78) is large. The figure also corresponds to the state shown in Figure 4(e), where the pipe guide (171) has entered the machining start hole (77) and is at the lower limit position.The lower die guide (11 is a cross section) It shows.

Embedded in the center are dice (79) of jewelry such as diamonds and sapphires.

In the case of FIG. 5(a), the wire electrode (2) is connected to the die (
79) and instead enters the gap between the lower die guide frame and the lower nozzle (78). This is because the initial state of the wire electrode (2) is due to internal strain or curl. On the other hand, in the case of FIG. 5(b), the curl is even more curly, and it has protruded outside the lower nozzle (78). Both.

Since the wire electrode (2) has not passed through the die (79)', the insertion of the wire electrode (2) naturally fails, and subsequent electric discharge machining cannot be performed, making it impossible to continue.

Next, as shown in FIG. 6, let us consider a case where the shortcoming of FIG. 5, which is that the distance between the lower surface of the workpiece (to) and the upper end surface of the lower nozzle (70) is large, is solved. Other situation settings are the same as in FIG.

In the case of Fig. 6(a), the wire electrode
79) This is the case where Th is successfully passed. As expected, the fifth
It can be said that the wire electrode (2) is more easily guided to the position of the lower die guide field in FIG. 6 than in the figure.

However, if the bend 9 of the wire electrode (2) enters at a nearly right angle to the introduction taper part of the lower die guide (41) as shown in FIG. 6(b), the wire electrode (2) may get caught. , it becomes impossible to proceed any further.Also, the sixth
As shown in Figure (C), machining chips generated by electrical discharge machining may accumulate on the introduction taper portion of the lower die guide OQ over a long period of time. This is because it is not constantly immersed in the machining fluid but is repeatedly dried every 9 minutes, resulting in hard and irregular deposits (80). In this case, as shown in Figure 6(b).Compared to VC, a stuck state occurs on many occasions, as shown in Figure 6(b).
Similarly, the wire electrode (2) is blocked from advancing. In this way, in the case of Fig. 6(b) and (c), the wire electrode (
Not only is the progress of wire electrode (2) blocked, but if you try to move it in the direction of the arrow with a stronger force, it will bend or break, resulting in a failure in inserting the wire electrode (2), as shown in Figure 5. It becomes impossible to continue.

Therefore, in view of the above nine drawbacks, the present invention attempts to significantly improve the probability of successful wire electrode insertion by detecting the failure (19), having the insertion operation be repeated again, and ultimately succeeding. be.

First, we will describe the principle of classifying failures during insertion operations and detecting each failure. Let's consider the two types of failure as shown below.

(1) If the progress of the wire electrode is obstructed, the 6th
A case like the one shown in the figure can be cited.

It can be said that this is a case where a high load occurs on the advancing ability of the wire electrode, so it is not limited to what is shown in Fig. 6.
It includes anything that impedes progress.

(2) When the wire insertion operation is not completed Mainly as shown in Fig. 5, unlike in (1) above, the progress of the wire electrode is not hindered, but the wire electrode advances in a direction other than the insertion path. Then, 0 ■ First, regarding (1) of the above failures, the detection principle in that case will be described.

(20) FIG. 7(a) corresponds to the state of FIG. 4(C).

That is, the wire feeding pinch roller (7) is driven, and the wire electrode (2) is driven by the wire feeding leg roller (8).
) and is moving in the direction of the arrow in the figure. The wire electrode (2) has a slight clearance with the die (81), so it slides. Further, the wire feeding foot roller (8) presses the wire electrode (2) against the wire feeding pinch roller (7) by the force of a spring (83) against the fixed plate (82). Here, the force for fully advancing the wire electrode (2) is as follows. From the figure, normal force N due to spring (83) force, roller +7)
, +8) and the friction coefficient tμ between the wire electrode (2)
Then, roller f71, (81 is a wire electrode (
2) The frictional force that causes the ball to advance completely is μN. In addition, the wire electrode (2) on the upper side of the roller (7), (81
At 1K, a tensile force To is working. However, T.O.
This is due to the braking force acting on the supply reel (1) and the braking force acting on the brake roller (3) in FIG.

During the insertion operation, the braking force of the brake roller (3) is weakened to the minimum in order to reduce +Tok.

Therefore, the force for moving the wire electrode (2) fully is μ from the figure.
It becomes N-To. Of course, μN〉'ro
Needless to say, it is.

Next, FIG. 7(b) shows a case where there is an obstacle (84) in the traveling path of the wire electrode (2). However, in reality,
Although all the high loads mentioned in Fig. 6 are indicated, for the sake of simplicity, we will treat them as obstacles from Fig. 7 onwards.

FIG. 1(b) shows a state in which the wire electrode (2) is obstructed in its progress by an obstacle (84), so that the bend inside the pipe guide (171) is deformed by the force.

Therefore, it is an elastic deformation that is contrary to the bending stiffness.

As shown by F in the figure, a reaction force acts in the direction of returning the deformation to its original state. Therefore, the pinch roller for wire feeding (
7) continues to rotate because it is a one-way clutch that can freely rotate in the direction of the arrow, but a gap is created between it and the wire electrode (2), and the wire feed leg roller (8) stops rotating. .

In other words, the state is F+To=μN.

To explain in more detail, as shown in FIG. 1(C), if the coefficient of friction between the inner wall (85) of the pipe guide and the wire electrode (2) is μm, and the normal force pressing against the inner wall (85) is n, then The wire electrode (2) is deformed by the force μN-To applied inside the pipe guide (range shown in the figure), and the wire electrode (2) is deformed by the inner wall (85) at multiple points as shown in the figure. come into contact with.

Each generates a frictional force of μm and n. With these,
The wire electrode (2) acts like a spring inside the inner wall (85), and as the contact progresses at multiple points, the wire electrode (2) progresses to deformation in short sections. Therefore, the resultant force F of the reaction force of the bending deformation increases. Its final form is shown in Figure 1(b).
Then, li=μN −To. That is, in the state shown in FIG. 1('b), the advance of the wire electrode (2) is completely stopped.

Therefore, the inventor of the present invention actually conducted an experiment to confirm FIG. As a result of various experiments (23), it was found that although the wire electrode (2) may sometimes come to a complete stop, there are interruptions in its progress.

This will be explained using FIG.
This is a case where K has not been reached. Further, (86) is the tip position of the wire electrode (2), and (87) is the position of the die portion.

Even in this case, the frictional force f when the wire electrode (2) passes through the die part. This is what is happening.

In other words, it is the state of μN-To)f□, and the arrow (88)
The wire electrode (2) is drawn in the direction.

Next, in FIG. 8(b), the wire electrode (2) is blocked by an obstacle (84).
), fo increases to fl()fo). However, because μN-To)fl, the arrow (
88) is four directions.

Next, (c) and (d) are the vibe guide inner wall (85)
At the inner.

The bending deformation of the wire electrode (2) is increasing, and 1 reaction force f2. It has increased to f3, but still.

μN −To ) f2, f5, so the arrow (88
) direction does not change.

(24) Next, as the bending of the wire electrode (2) progresses to Figure 8 (8), the 9 reaction force increases by f4 K and μN −To = f
4, which is the same as that shown in FIG. 7(b), and the wire electrode (2) stops advancing. And ideally,
The wire feed pinch roller (7) rotates while rotating the surface of the Hawaiian electrode (2).

However, in reality, there is a play in the one-way clutch attached to the pinch roller (7) and the drive transmission gear, a change in the concentricity of the pinch roller (7), and a change in the concentricity of the pinch roller (7).
Due to changes in the surface properties of the outer periphery, etc.

Due to the reversal of the pinch roller (7) and the change in μN, (f
) as shown! /C1 is reversed by the reaction force f4 and returns to f4-Δf.

That is, in (f), the direction of the arrow (88) changes and the wire electrode (2) returns. However, △ for 9 reaction force drop
It can be considered that f corresponds to the decrease in μN.Next, the direction of the arrow (88) changes again as shown in FIG. 8(g), and the wire electrode (2) is fed. Then, by repeating the cycle of Fig. 8 (θ) → Fig. 8 (f) → Fig. 8 (gl), the wire electrode (2) makes an intermittent movement (including a reverse movement), and the wire feeding leg The roller (8) performs an intermittent movement of rotation.

So-called Figure 8 (e), (f), (g) VC
By the length of the wire electrode (2) fed into the range L at

This causes a change in reaction force f4 (Δf)'Ik, which causes spring vibration. This movement is L1 in Figure 1.
This will continue as long as the wire in the range does not buckle.

At this time, the direction changing pulley (5) shown in FIG. 1 similarly stops or makes one intermittent movement (rotation), so this can be used to detect the change in direction.

It can be determined whether the advancement of the wire pole (2) is obstructed or if there is a high load. This type of detection will be termed high load detection during wire electrode advancement.

Next, regarding failure (2) mentioned above, the detection principle will be described.

FIG. S shows a case where the upper die guide holder and the lower die guide 4 are at the farthest position during the wire insertion operation. In this case, contact is sensed between the pipe guide aη and the workpiece (to) (conductivity is established through the die guide Hk), and the wire electrode (2) begins to advance. The thickness of the workpiece (to) is the maximum HmaX, which is 0. Furthermore, the length in the figure is unique to the 9 machine and can be uniquely determined.

First, the wire electrode (2) indicated by a solid line is a case where the insertion is successful, and the wire electrode (2) fed from the upper die guide wire is inserted into the machining start hole (77)'! It passes through the v1 nozzle (78), the lower die guide OO1 power feeding die (41), the guide nozzle (4 nozzles), and is fed between the belt roller (451 and lower belt 07) and the lower roller (fence), and then the , lower roller (4
It is pulled by a hammer. This is the normal wire insertion path, and the time and distance required for this are almost uniquely determined. The wire electrode (2) indicated by a broken line is an example of a failed insertion and has come off the insertion path. Therefore, the present inventor developed a pinch roller (7) for wire feeding as shown in Fig. 1.
According to (27), since the speed at which the wire electrode advances and the speed at which the wire electrode advances as it is pulled by the lower roller (mark 4) are different,
They found a way to detect failure. That is, the advancing speed by the lower roller decoy is as fast as the speed during electrical discharge machining, and the advancing speed by the wire feeding pinch roller (7) is slow because it passes through a small clearance such as the die guide frame.

Next, the detection principle will be explained using FIG. 10.

The vertical axis of (a) l (b) is the advancing speed V of the wire electrode (2), where v2 is due to the lower roller, and ■1 is due to the wire feeding pinch roller (7).

Also, on the horizontal axis, S is the length along the wire insertion path from the die guide (A) in Figure 8, and T is the elapsed time since the wire electrode (2) first advances by the wire feeding pinch roller (7). It is.

First, (a) is a graph of ■ and S, where (89) is a successful insertion, and (90) is a failed insertion.

As can be seen from this graph, Hmax +
After traveling a distance of L, the speed increases from ■1 to (28) ■2 in the case of success, and remains at vl in the case of failure. The reason why the speed does not increase immediately from (1) to (2) at position L is due to the deviation due to the drawing time to the lower belt.

Next, as can be seen from the graph in FIG. 10(b), the time TL for the speed to increase from vl to {circle around (2)} in FIG. 10(a) is uniquely determined. Therefore, the wire electrode (2) is advanced by the wire feeding pinch roller (7), and from the beginning the wire electrode (2) is moved at a maximum of TI.
, when the advancing speed increases from vl to ■2, it can be determined that the wire has gone out of the wire insertion path and can be treated as a failure.

In this way, failure can be detected by detecting a change in the advancing speed after a certain period of time after the wire electrode (2) first advances. This type of detection will be referred to as detection of the wire electrode (2) coming off from the wire insertion path.

Next, an example of a circuit that actually detects failure will be described. First, a high load detection circuit when the wire electrode (2) is advanced will be explained.

First, as explained in Fig. 8, the wire electrodes (2
) to detect the intermittent motion of the rotation of the direction changing pulley (5) shown in FIG. 1. FIG. 11 shows a detection device for this purpose. Figure 11 (a
), an encoder (91) is attached to the direction conversion pulley (5). If the wire electrode (2) does not advance intermittently.

This results in intermittent rotational movement of the direction conversion boolean IJ-(51). Also, Fig. 11(b) explains how to use the encoder (91). They are shared.R is a resistor that limits the current flowing to the diode.

The output side A and B terminals are connected to a detection circuit.

Next, the detection circuit will be explained using FIG. 12. Note that the A and B input terminals correspond to those shown in FIG. 11, and the B side is the diode side.

In this Figure 12, the output of the encoder is Q, =
Since it is AC in the range of 5 V, first capacitor c1
By cutting out the DC component of the resistor RIK, we only use it for social gatherings. Next, the OP amplifier (92) performs amplification by a factor of R3/R2. After that, diode D1. By D2
Q, clamp in the -5V range. The waveform of T2 after passing through the inverter is the low 5 waveform of the alternating current of Wl.
It is converted into a pulse in the range of (2). (93) is a one-shot for high load detection, and the output pulse is Tc1
This is the width. Relay coil L1 is for high load detection, and D
3 is a diode for protection. Also.

(94) is a one-shot for failure detection outside the insertion path, which will be described later, and has a width of output pulse tllTQ2.

For detecting relay coil L2 outside the u insertion path.

D4f is a protection diode.

Wl in FIG. 12, T2. A schematic timing chart is shown in FIG. 13 using the T3 waveform.

I will explain the entire high load detection method.

Wl in FIG. 13(a) is the output waveform of the encoder.

This is the rotation of the direction changing roller by the wire feeding pinch roller, and is the case when the choir is inserted. At this time T
The waveform No. 2 is a square wave pulse with a period T1. and T3
Since the one-shot pulse k14E (31) is generated at the rising edge of the pulse of waveform H and W2, since Ti (Tc1).

While the wire is being inserted, it is always at a high level of 5■.

Therefore, it can be seen that the relay coil L1 in FIG. 12 is in the ON state. This state is a state in which no high load occurs.

Next, under the conditions (8), (f), and (g) in FIG. 8, the waveform becomes T2 in FIG. 13(b). That is, a cycle T1 with a normal pulse width and a cycle T2 with a short pulse width and a long pause repeatedly occur.

This is because, in order to output pulses even if the encoder is reversed, when the wire electric machine (2) is returned by spring force as shown in Fig. 8(f), the reverse M rotation force acts instantly and the Figure 13 (b
) is shorter at T1 and the pulse at T2 is also shorter. In contrast to VC, in the case of the 8th rotation, the rotation of the pinch roller for wire feeding is when the forward rotation is started, so the maximum rise time is required, so T2 in Fig. 13 (b)
This results in a long pause. When the detection circuit was actually observed with a synchroscope etc., waveforms corresponding to W2 in (b) were also confirmed in (32).

As a result, a zero level with a width of 1 is generated in the waveform Yc of T3. At this time, relay coil L1 in FIG. 12 is in the OFF state. In this way, the relay coil L indicates that intermittent rotational movement of the direction conversion pulley has occurred.
It can be detected by the state change of 1 from ON to OFF.

Next, a failure detection circuit outside the insertion path and a timing chart will be explained.

The detection circuit is the same as that shown in FIG. 12.

FIG. 14 is a timing chart at the time of wire insertion. The section T8 seen in Wl in FIG. 14(a) is the first
This is the same as the state shown in FIG. 3(a), and is caused by the rotation of the wire feeding pinch ruler (7). The subsequent high-frequency part is shown in Figure 8 (lower bell) (47) K is pulled in and the advancing speed of the wire electrode (2) increases 〇Therefore, as seen in Figure 14 (b) like.

The period T8 is the period T1, and thereafter the period changes by 'rmK. At this time, since the one-shot width of the T4 waveform is Tc2 (Ti) Tc2) Tm), the pulse width is Tc2 during the Ts period, and is at a high level thereafter. Therefore, T8 corresponds to the time when the insertion was successful.

For example, after Ts (time Tl corresponding to TD), the state of KW4 is always at a high level. That is, the relay coil L2 in FIG. 12 is always in the ON state after Tl) after the wire feeding pinch roller (7) starts rotating.

Next, when the wire electrode (2) advances outside the wire insertion path, as shown in FIG. 14(b), the T2 waveform continues as a pulse with a period of T1, and the T4 waveform continues with a pulse width of Tc2. . Therefore, TD (Tl)>T8)ff1.
By looking at the waveform of T4, it can be seen that there is a pause called 'rf2.

At this time, relay coil L21 in FIG. jOFF state. In this way, if the wire (2) comes off the insertion path during the insertion of the wire 12), it can be detected by determining the state of relay coil L2 from ON to OFF or OFF' after Tl). I can do it.

Next, a logic detection circuit that generates a failure detection signal from the states of the relay coils Li and L2 will be explained using FIG. 15.

Timer relay RT1, RT2, relay f1. f
Coil No. 2 operates at P24 (+24 V). #
M20 is a relay for a wire insertion command given by a computer or the like or manually; ps=14: This is a relay that is turned ON while the WFU wire feeding pinch roller is rotating.

First, in the case of a high load failure, the wire insertion starts, relay #WF is turned on, and timer RTi is set. Relay #RT1 turns ON after 2 SeC. Since the back contact of relay #I RA is open during normal operation and closed during failure, resulting in a short circuit, failure detection relay #f1 is turned ON and held.

Relay #RT1 has a detection inhibiting function to prevent false detection at the start of the wire electrode (2) progression.

Next, in case of failure outside the insertion path, start from the beginning of wire insertion.
Timer RT2 is set. Relay (35) 1#RT2 turns ON after Tl). Relay: 14=2
RA will short circuit when it fails, just like when it fails under high load.
Failure detection relay #f2 is turned ON and held.

Therefore, 1 for both failures.

Relay #f1 or #f2 is turned ON. So P5
When relays #f11 and $f2 are connected in parallel to (+5V), the F output changes to high level in response to either failure. All you have to do is transport this F signal to all the computers.

When processing the next KF signal using a computer.

The processing method to be used will be explained using the flowchart (f) in FIG. Unless a failure is detected (the P signal is at a high level), the insertion is completed. If a failure is detected, it is determined whether the number of failures has reached N times.N
If the number of times has been reached, it is assumed that there is an abnormality in one mechanical device and the function is stopped. If the number of times has not reached N, a cut command (36) is issued to cause the cutting operation to be performed. The cutting and insertion mentioned here means the series of operations shown in FIGS. 3 and 4. However, the wire electrode (2) that was required to fail in the cutting operation is removed by the cutting device shown in Figure 3, and the wire electrode (2) is inserted again.
Use a new wire electrode (2) ○ After cutting is complete, issue the insertion command again and repeat the cycle of inserting. in this way.

The flow in Figure 16 shows the number of successful and unsuccessful insertions.

It is repeated until reaching N times.

Here I will explain why I am counting the number of failures.

If the probability of failure when inserting the wire electrode (2) is set to X, then the probability of failure N times in succession is xN. Therefore, the probability P that the wire insertion is successful at the m-th time is as follows.

P(m) = 1-xrn (Example) (i) When x = 50%, m = 5 times P(5) = 97% m = 7 times P(7) = es% (If) x = 30% In the case m = 3 times P(3) = 97% m = 4 times P(4) = sg% As can be seen in the above example, the success rate of one insertion is 50% (x
= 50%), the success rate increases to 99% by detecting failure seven times and retrying the insertion. Also 1
If the success rate is 70% (x = 30%), the number increases to 99 by reinserting 4 times. In this way, even if the probability of successful insertion at one time is low, the success rate increases by repeating insertion several times. In other words, it can be said that the reliability of insertion has been significantly improved.

In summary, the present invention detects failure during wire insertion and leads to success by re-inserting the wire, thereby providing a highly reliable automatic wire feeding method.

In addition, all misfires 8A are included in the scope of all failures that are automatically inserted by other means to detect failures.
Not even.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional automatic wire feeding device, FIG. 2 is a block diagram of a conventional cutting device, FIG. 3 is a diagram showing a conventional cutting operation, and FIG. 4 is a diagram showing a wire insertion operation. Figures 5 and 6 are diagrams showing the conventional drawbacks, Figures 7 to 10 are diagrams explaining the reasons for the drawbacks and ripple effects, and Figures 11 and 12
13 and 14 are timing charts of the detection circuit and diagrams showing the detection principle. FIG. 15 is a relay sequence diagram for generating an insertion failure signal. , FIG. 16 is a diagram showing a flowchart 1r for implementing the present invention by all computers. In the figure, (2) is a wire electrode, (5) is a direction conversion pulley, (91) is an encoder, and (92) is an OP amplifier. (93) and (94) are one-shots. Note that the reference numerals in the middle of FIG. 6 indicate the same parts. Agent Shin Kuzuno - (39) Figure 1 Figure 2 Figure 9 (α) (b) L knee L-8 Figure 13 (α) Ding f1 Kyoku 14 Figure (α) +b+ Figure 15 Figure 16 Mr. Commissioner of the Japan Patent Office, Date of Month, Showa 1, Indication of the case, Patent Application No. 57-57892, 2.
Invention O Title Automatic wire feeding method in wire-cut electrical discharge machining equipment 3. Person making the correction (1) 5. Subject of correction (1) Column for detailed explanation of the invention in the specification. 6. Contents of the amendment (1) In the second line of page 8 of the Mei #il Oath, it has been stated that “Roller
Correct "Zeng" to "Roller θ→, (Foundation) J. (2) On page 11, line 4 of the same book, “After that...
・・・・・・・・・Return, -1, [After that,
When the arm rotation motor (G) is rotated 180° in the opposite direction, the cutting motor (A) is also started at the same time.
Return to the position shown in the figure, and the moving rod (g) is at the leftmost position. ” he corrected. (3) In the second line of page 17 of Chuon in the same book, ``cutting operation'' is corrected to ``cutting operation 1''. (4) Same book, page 23, line 9 VCr μ+, n respectively
J is corrected to [respectively μ+n-J]. (5) Ibid. Chuon, page 37, line 9 K [The flow in Figure 16 is repeated.] -]
There is a certain [1st. Figure (7) 7 C1-1 has 5 insertions
It works, well, that is, in a game where failure is 4' out of n times, it is not repeated, 1 and W correct.
C1hi (2)

Claims (5)

[Claims] (1) Wire-cut electrical discharge machining in which the wire electrode is automatically fed so that the wire electrode passes from the wire electrode supply section to the machining start hole of the workpiece and engages with the wire electrode collection section. In the wire automatic feeding method in the device, the wire electrode does not come into engagement with the wire electrode collecting part in the section between the wire electrode feeding part and the wire electrode collecting part, even though the wire is being automatically fed. In such a case, an automatic wire feeding method in a wire cut electrical discharge machining machine RYc is characterized in that the wire is automatically returned to the initial state before automatic wire feeding and the wire is automatically fed again. (2) The automatic wire feeding method in a wire cut electrical discharge machining apparatus according to claim 1, characterized in that during automatic wire feeding, failure in feeding the wire electrode is detected. (3) When a failure in automatic wire feeding is detected, the wire electrode that was fed from the wire electrode supply unit until the failure is removed, and automatic wire feeding is performed again using a newly fed wire electrode. An automatic wire feeding method in a wire-cut electric discharge machining apparatus according to claim 1 or 2, characterized in that the method is characterized by: (4) In automatic wire supply, the cyclic operation of feeding the wire electrode from the wire electrode supply section, detecting a failure, and restarting the automatic wire supply again indicates that the wire electrode has reached engagement with the wire electrode recovery section. Depending on the signal to be detected,
3. An automatic wire feeding method in a wire-cut electric discharge machining apparatus according to claim 1 or 2, characterized in that the wire feeding method is completed. (5) Cycle the automatic wire supply again.
Wire-cut electric discharge machining according to claim 1 or 4, characterized in that if the automatic wire supply fails and is not completed even if it is performed only a certain number of times, the automatic wire supply is stopped. Automatic wire feeding method in equipment.