JPH01274926A - Wire electrode automatic feed unit in wire cut electric discharge machining device - Google Patents

Abstract

PURPOSE:To increase the success probability of wire insertion by counting the frequency of the return and reset of a wire electrode in such a way as to return the electrode to an initial state upon the detection of the non-engagement thereof with a wire recovery device during an automatic feed process and again giving a wire feed instruction upon the detection of the reset. CONSTITUTION:A wire electrode 2 fed from an upper die guide 20 on the turn of a pinch roller 7 is fed to a space between the belt 47 of a wire recovery device and a lower roller 48 via a machining start hole 77, a nozzle 78, a lower die guide 40, a power feeding die 41 and a guide nozzle 44, thereby being pulled by the lower roller 48 rotating at a speed higher than the pinch roller 7. The passage failure where the aforesaid wire electrode 2 is derailed from a guide 40 and the high load failure where the wire electrode 2 stops due to the contact of the chip thereof with the guide 40 are detected with the judgement of a signal from an encoder directly connected to a direction conversion pulley 5 on the basis of the predetermined timing. Then, the rotation of the pinch roller 7 is reversed, reset to an initial state and the wire electrode 2 is again inserted. The frequency of such electrode re-insertion operations is counted and wire cutting is made upon the occurrence of the predetermined frequency. Accord ing to the aforesaid construction, success probability can be made higher.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a wire feeding device for a wire-cut electric discharge machining device that detects a feeding failure due to a trouble during automatic feeding of a wire electrode and stops the automatic feeding of the wire electrode again. It's about how to fix things and lead to success.

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

In the case (!) is a wire supply reel connected to a torque converter (not shown), so that a reverse torque is applied to obtain enough braking force to prevent the wire electrode (2) from slackening. (3) is a brake roller, which is connected to an electric brake (not shown). (4) is a presser roller, which is pressed against the brake roller [3] by a spring force. The wire electrode (2) is sandwiched between the brake roller (31) and the presser roller i41, and a constant tension is applied to it without slipping. (5
) is a direction changing roller, and (6) is a positioning die, the inner diameter of which is slightly larger than the diameter of the wire electrode (2). +71 is a pinch roller for wire feeding, (8I
is a holding roller for wire feeding. The roller (7) is rotated by the pinch roller motor alIK attached to the lifting plate (91) only during automatic wire feeding.The roller (8) is pressed against the roller (7) by the spring force. 9. During automatic wire supply, the wire electrode (2
) is sandwiched between rollers (7) and (8), and is fed downward in the figure without slipping. The positioning die (61) is placed on the wire electrode (2), and the wire electrode (2) is placed on the roller (7).
1, (it will not fall outside of 81).

The elevating and lowering of the elevating plate (9) is coupled to the elevating motor fil+ and the coupling α2. This is done by rotating the ball screw α3. On the long side in the diagram of the elevating plate (9) above.

A ball nut is attached to convert the rotation of the ball screw +13 into vertical linear motion. This ball screw f13 is supported at one end by a motor attachment part α9 attached to a lifting guide (141), and the other end is supported by a bearing qti, so that it is supported at both ends.

In addition, since the elevating plate (9) is supported in elevating and lowering by the elevating guide I, accurate vertical movement is possible.

Further, a pipe guide αη is fixed to the elevating plate (9) via a guide fixing plate aδ. This pipe guide σ
D moves up and down as the lifting plate (9) goes up and down.

It is supported by a bearing (19) to prevent vibration.Furthermore, a wire electrode!21 is attached to the tip of the pipe guide αD.
A die guide ■ is attached as a precaution to support the process. Note that bearing σe, α9. The elevating guide fi41 is attached to the fixed plate +211.

Next is the cutting motor, and 0 is the arm rotation motor. Both of them are fixed to the 2 boxes.

(2) is a wire cutting part, aS is a cutting arm, and @ is a tray for discarding wire chips after cutting the wire.

The cutting device @ and the saucer surface are mounted on a fixed plate (2υ).The details of the cutting device and the wire cutting section G will be described later.

During machining, the pipe guide αη is i! The pressing member is pressed against the sv groove plate ■ and fixed by the plate ■. This reference V-groove plate @ is received by the V-groove surface so that the pipe guide aη fits therein, and its position is determined. The reference V-groove plate ■ is always fixed at 2 boxes ω.
is attached to a fixed plate an. Further, a nozzle (toward) for jetting and supplying the machining liquid C111 to the machining section is attached to the second box ω.

In addition, the pipe guide σn has three notches as shown in Figure 1. During machining, these notches make contact with the power supply pin ■, (to) ka, su, and wire electrode (2) at three points. Keep it up.

Power is supplied from here. The power supply pin 1341 is a moving plate ■
When the pipe guide 171 is fixed to and moves up and down, move it to the right in Figure 2 to avoid contact.

Similarly, the i@electric pin (to) is fixed to the movable plate 0 so that when it is pressed to the left in the figure, it moves together with the plate. (to) is the workpiece, and 09 is the table.

Next, IQ is the lower die guide, and Sir is the lower power supply die. Both are fixed to one box and attached to the lower arm. Box UZ contains machining fluid 31.
A nozzle (78) for jetting and supplying the wire electrode +21 to the processing section (2) is attached thereto, and a guide nozzle (2) for guiding the wire electrode +21 is also attached.

The wire electrode (2) that has passed through the guide nozzle (Foundation) advances while being sandwiched between the belt roller device, the lower belt +471 stretched around the throat, and the lower roller (toward), and then travels to the trumpet tube device. be guided. After that, the wire electrode (2) passes through the first collection pipe ω and the second collection roller (51), (52)
collection bell) (53) and collection roller (54)
), the wire electrode (2) is guided to the collection box (55), and as shown in Figure 1, the wire electrode (2) is discarded in a circle. Note that the feeding speed of the wire electrode (2) is variable (as shown in the figure of the second collection roller (54)) by the rotation of a motor with a reduction gear attached to the back, and furthermore, The roller (to) is belt-transmitted on the back side. Furthermore, both of the rollers 1481.
(54) have the same diameter, so they rotate synchronously.

Therefore, the wire electrode (2) is pulled without slipping due to the frictional force by the lower roller (toward) section and the frictional force by the recovery roller (54) section, and is recovered into the second recovery box (55).

Next, o, h of the device for cutting the wire electrode (2).

The configurations of (1) and (2) will be explained using FIG.

(56) is a cutter for cutting the wire electrode (21), and is fixed to the movable rod (58) by a screw (57). At the tip of the movable rod (5B) is a wire electrode. (2) Support rod (5) that supports it so that it does not move when cutting
9) is fixed, and rubber (60) is adhered to the contact portion to prevent slippage. Also, (61)
is a cutting receiving plate, which is fixed to the cutting arm ① with screws (62). The cutting plate (61) is made of rubber (
64) is glued to prevent slippage. When cutting the wire electrode (2), the movable rod (58) is moved between the cutting plate (61) and the cutter (56) under pressure in the figure.
By moving in the ``direction'', the rod is cut and simultaneously supported between the rubber (60) and the rubber (6).
) is threaded at the right end in the figure, and a compression spring (65
), the locking nut (66) is screwed in and fixed. The horizontal movement of the moving rod (58) is performed by half-rotation of the eccentric cam (67). The figure shows the case where the eccentric cam (67) is at the rightmost position, and the S motion Ig (5B)
is also located at the right end due to the rear force of the compression spring (65). vice versa.

When cutting the wire electrode, the eccentric cam (67) rotates half a turn to the leftmost position, so the movable rod (58) and locking nut (66) are positioned at the left end, and the cutter (56)
) and the cutting plate (61).

Next, the rotation of the cutting arm (2) will be explained.

When the arm rotation motor attached to the box U rotates, the gear (69) and gear (70) attached to its shaft rotate. The gear (7o) is the arm rotation rod (
71), and is further connected to a cutting arm ■. The arm rotating rod (71) has a bearing (72),
(75). However.

Make sure that the arm rotation motor rotates approximately half a rotation.
The cutting arm (■) rotates to the opposite side of 1800 in Figure 2 and stops. The position on the opposite side of 1800 from 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 rotatable nine times. An eccentric cam (67) is fixed to the lower end of the eccentric cam rotating rod (7), and can rotate smoothly due to the bearing (7s).A cutting motor is connected to the upper end via a coupling (76). Therefore, when the arm rotation motor 0 rotates in order to position the cutting arm ■ on the opposite side by 180 degrees, the cutting motor ■ is also activated at the same time and rotates 1800 degrees. In the figure, the eccentric cam (67) and locking nut (
66) remains the same, the wire electrode (2) is located between the cutter (56) and the cutting plate (61).

Thereafter, by further rotating only the cutting motor ■ by 1800 revolutions, the movable rod (58) moves in the direction of the cutting receiving plate (61), and as described above, the wire electric &! (21
can be cut. After that, the cutting motor■
While keeping it stopped, turn the arm rotation motor ■ backwards to 180 degrees.
'Rotate K and return to the position shown in Figure 1. Then, by rotating the cutting motor 1800 times in reverse, it is possible to return to the state shown in Figure 1.

Next, referring to FIG. 3, the operation of cutting the wire wire &f2) will be explained.

First, in FIG. 3(a), a state is initially set in which the wire electrode (2) passes through the machining start hole (77) of the workpiece (to).

This is the case when the cutting operation begins. That is, FIG. 1 shows the initialized state. First, in order for the pipe guide tin to rise in the direction of the arrow in the figure, the moving plate (to) to which the l/@t bin-1 (to) is attached, the Gel and the moving plate to are attached to it. When pressing, the plate moves in the direction of the arrow in the figure.

Note that the pipe guide αD rises and stops at a certain predetermined position 1.

At this time, as described in FIG. 1, the wire feeding pinch roller (71) and the wire feeding press roller (8) rise and stop together with the pipe guide an.

It is designed to rotate as shown by the arrow in the figure.

The reference V-groove plate ■ is always fixed and the pipe guide a
When η rises and falls, it rubs. Note that the nozzle (to) is always fixed. The die guide (2) has enough clearance to scrape the wire electrode (2) when the pipe guide fin rises. (The lower end position of the die guide ■ in Figure a1 is called the cutting position.)

Next, in Fig. 3(b), the cutting arm is set to 1 at the cutting position.
The figure shows the state in which it has been rotated 1800 times. This means that the wire electrode (2) has been positioned at the cut section (2). The operation of the arm rotation motor of the cutting motor is the same as described in FIG. At this time, the wire feeding pinch roller (71) and the wire feeding press roller (8) are stopped.

Furthermore, a one-way clutch (not shown) is attached to the pinch roller (7) so that it does not rotate in the direction opposite to the direction of the arrow in FIG. 3 (at).

Next, Fig. 3 (cl) shows the state after actually cutting the wire at pole (2). In other words, after cutting as described in Fig. 2, the cutting arm Then, the lower part of the wire electrode (2) after cutting detects that the cutting motor ■ has rotated further 180 degrees as described in Fig. 2, and returns to its original position as shown in Fig. 1. As the collection roller (54) starts rotating, the items are collected into the second collection box (55).

Next, Fig. 3 (dl) shows the state where the wire electrode (2) has actually been cut.In other words, after the state of Fig. 3 (C) is completed, the pipe is cut until the state of Fig. 3 (Td) is reached. The guide an descends. This state is the initial state shown in FIG. 3(a), with the moving plate (to) and the forehead moving and remaining at fc.

The position of the pipe guide ciη is now the same as in FIG. The lower end of the die guide (■) at this time will be called the home position.

Note that while the pipe guide αη is descending, the wire electrode (21
is sandwiched between the wire feed pinch roller (7) and the wire feed presser roller (8), and a one-way clutch is attached to the pinch row 2 (7), which prevents the reverse rotation. Therefore, it will not slip out from the tip of the die guide ■ and come out upward.

Figure 3 (cutting is complete when the state of dl is reached.
During the cutting operation shown in Figures (at) to (d), the braking force of the electromagnetic brake connected to the brake roller (3) in Figure 1 is extremely weakened.

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

Here, the wire electrode is passed through the machining start hole first and then into the lower die guide7. The process up to sending the wire electrode (2) to the collection box (55) in FIG. 1 is referred to as the insertion operation of the wire electrode (2). First, the state of the fourth [1W (at) is the initial state of the wire insertion operation. This is the same state as the final state of the cutting operation in Fig. 3. That is, the upper die guide ■ and the machining start hole ( 77) and the lower die guide are aligned in the vertical direction.

Next, as shown in FIG. 4(b), the pipe guide a
n is lowered and passed through the machining start hole (77), and the upper die guide (3) and the lower die guide CO are made to face each other. The lower end of the upper die guide ■ in this state will be referred to as 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 feed pinch roller (7) and the wire feed press roller (8) is moved by the rotational force of the wire feed pinch roller (7) and the wire feed press roller (8). start. FIG. 4 (C1 shows the state in which the wire electrode (2) has passed through the lower die guide C0.

Thereafter, as seen in FIG. 1, the wire electrode (2) passes through the feeding die I and the guide nozzle (2).

It is guided to the lower belt 1471. Note that the lower roller throat and recovery roller (54) start rotating at the same time as the pinch roller (7) and presser roller (8) rotate in FIG. 4. The lower roller (to) and the collection roller (54) are synchronized by belt transmission.

Therefore, when the wire electrode (2) advances to the entrance of the lower roller at 471° (lower bell), it is drawn between the two and guided, and collected into the collection box (55) as shown in Figure 1. . Here, power supply dice (41) (!: Collection box (
55).

It can be determined whether the wire electrode (2) has been led to the collection box (55). After the contact is sensed in this way, as shown in FIG. 4 (dl), the pipe guide aη rises to a fixed position and stops, and then moves to the moving plate (to).

(2) and pressing move the plate in the direction of the arrow in the figure to fix the pipe guide aη and the power supply bin 341. (To) makes it possible to supply power to the wire electrode (2). At the same time as it becomes possible to start machining, the insertion operation is completed in the state shown in Fig. 4 (dl).In addition, during the insertion operation in Fig. 4, as well as during the cutting operation in Fig. 3, the brake roller in Fig. 1 (The braking force of the electromagnetic brake connected to 31 is extremely weakened.

As described above, the conventional wire automatic feeding device performs a cutting operation every time the machining start hole changes, and then performs an insertion operation to automatically bring the wire into a state where machining can be performed.

Next, we will discuss the drawbacks of this conventional wire automatic feeding device during the insertion operation.

First, during the insertion operation refers to the period from (a) to (dl 1) in Figure 4.There are various types of travel during the insertion operation, but as shown in Figures 5 and 6, the insertion operation cannot be continued. Let me explain the possible troubles. Figure 5 (
Let us consider a case where the distance between the lower surface of the workpiece (to) and the upper end surface of the lower nozzle (7B) is large, as shown in (b). In addition, the situation in the same country corresponds to the situation shown in Fig. 4 (C), in which the pipe guide an enters the machining start hole (77) K and is at the lower limit position. The lower die guide frame is shown in cross section, and a jewel die (79) of diamond, sapphire, etc. is embedded in the center.

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 decoy and the lower nozzle (7B). This is due to internal strain or curl in the initial state of the wire electrode (2). On the other hand, in the case of Fig. 5 (mountain), the curl is even more curly, and the curl is so large that it protrudes outside the lower nozzle (78). In both cases, the wire electrode (2) has not passed through the die (7), so naturally the insertion of the wire electrode (2) is a failure, and subsequent electrical discharge machining cannot be performed, so it is impossible to continue. It ends up.

Next, as shown in FIG. 6, let us consider a case where the shortcoming of FIG. 5, that is, the distance between the lower surface of the workpiece (2) 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 (2) passes through the die (79) successfully. Yaha 5th
From the drawings, it can be said that the wire electrode (2) is more easily guided to the position of the lower die guide frame in Fig. 6.

However, if the bend of the wire electrode (2) is almost perpendicular to the introduction taper of the lower die guide (A) as shown in Fig. 6(b), the wire electrode (2) will not get caught. occurs, and no further progress is possible. Furthermore, the sixth
As shown in Figure (C), machining chips generated by electrical discharge machining may accumulate on the introduction taper part of the lower die guide (2) over a long period of time. This is because the dry state is repeated at two intervals, instead of being constantly immersed in the machining liquid, resulting in hard and irregular deposits (80). In this case, compared to FIG. 6(b), the gripping state occurs more frequently, and the progress of the wire electrode (2) is obstructed as in FIG. 6(b). In this way, Fig. 6(b).

In the case of (C), not only is the advancement of the wire electrode (2) blocked, but if a stronger force is used to advance it in the direction of the arrow, a large bend or break will occur, resulting in
Similarly to the above case, if the insertion of the wire electrode (2) fails, it becomes impossible to continue.

Therefore, in view of the above two or more drawbacks, the present invention attempts to significantly improve the probability of a successful wire electrode insertion operation by detecting a failure, making the insertion operation a little more difficult, and finally 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.

+11 When the advancement of the wire electrode is obstructed. The main example is the case shown in Figure 6, which can be said to be a case where a high load is applied to the advancing ability of the wire electrode.
It does not have to be limited to what is shown in Figure 6, but it includes everything that impedes progress.

(2) When the wire insertion operation is not completed. Mainly the 5th
As shown in the figure, unlike the above (11), the progress of the wire electrode is not hindered, but there is a case where the wire electrode advances in a direction other than the insertion path.

First, regarding (1) of the above failures, the detection principle in that case will be described.

FIG. 7(a) shows the state shown in FIG. 4(c). That is, the wire feeding pinch roller (7) is driven.

and wire electrode (21 is a presser roller (8) for wire feeding)
It is sandwiched between them and is moving in the direction of the arrow in the figure.

It has a slight clearance from the wire electrode +21 #i diamond (81), so it slides.

In addition, the presser roller for wire feeding (81Fi fixing plate (82)
The wire electrode [21] is pressed against the wire feeding pinch roller (7) by the force of the spring (85). here.

The force for advancing the wire electrode (2) is as follows.

From the figure, the normal force N due to the spring (85) force and the roller (7
1,181 and the wire electrode (2), the frictional force exerted by the rollers (7), (8) to advance the wire electrode (21) is μN.
A tensile force To is acting on the wire electrode (2) above +81. However, TO is due to the brake force acting on the supply reel (1) K and the brake force applied to the brake roller (3) in FIG.

During the insertion operation, the braking force of the brake roller (31) is weakened to the minimum in order to reduce To.

Therefore, the force that advances the wire electrode (2) is
It becomes N-To. Naturally, μN > T.

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,
I am referring to the high load mentioned in Figure 6, but for the sake of simplicity, I will treat it as an obstacle in Figures 7 and onwards.

Figure 7 (bl shows that the wire electrode (2) is an obstacle (84) I
Since the pipe guide an is obstructed in its progress by the pipe guide an, it is deformed by bending force inside the pipe guide an. Therefore 1
Since the elastic deformation is against the bending rigidity, a reaction force acts in the direction of returning the deformation to its original state, as shown by F in Figure 2. Therefore, the wire feeding pinch roller (71ij) continues to rotate because it is a one-way clutch that can freely rotate in the direction of the arrow, but it slips between it and the wire electrode (2), and the wire feeding presser roller (8) stops rotating. It stops.

In other words, DK is such that F+TO=μN.

To explain in more detail, as shown in FIG. 7 (cl), if the coefficient of friction between the inner wall (85) of the pipe guide and the wire electrode +21 is μm, and the normal force pressing against the inner wall (85) is n, then the wire electrode ( 2) into the pipe guide (range shown in the figure), the wire electrode (21) is deformed and contacts the inner wall (85) at multiple points as shown in the figure. Each generates a frictional force of μmn.Thus, the wire electrode +21
5) A spring-like action is generated internally, and as the contact progresses at multiple points, the deformation of the short portion of the wire electrode (2) progresses, so the bending deformation increases. The resultant force F increases. Its final form is shown in FIG. 7(b), and 9. F=μN−To. That is, in this state K> of FIG. 7('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. Results of experiments conducted in the manuscript.

Although the wire electrode (2) may come to a complete stop, it should be noted that there will be interruptions in its progress.

This will be explained using FIG. 8.

Figure 8(a) shows that the wire electrode (2) is still an obstacle (84).
This is a case where the amount 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, a frictional force fo occurs when the wire 11I pole (2) passes through the die portion. That is, the state is μN-To>fo, and the wire electrode (2) is drawn in the direction of the arrow (88).

Next, in FIG. 8(b), the wire electrode (2) is blocked by an obstacle (84).
) and e f o Fif 1 (> f
o).

However, when μN−'ro>rt, the arrow still remains (
88) are in the same direction.

Next K(c), (di within the pipe guide inner wall (85).

In a state where the bending deformation of the wire electrode (2) is increasing, the reaction force is '2m'! Although it increases with i, the window, μN
-To>f2. f, so the direction of the arrow (88) does not change.

Next, as the bending of the wire electrode (2) progresses in Figure 8 (e) 1, the 2 reaction force increases to f4 and becomes μN-To = f4, and as shown in Figure 1 (Kl is the same as bl) , wire electrode (2
) will stop progressing. Ideally, the wire feeding pinch row 2 (7) rotates while sliding on the wire electrode (21 surface).However, in reality,
Due to play in the one-way clutch and drive transmission gear attached to the pinch roller (7), changes in the concentricity of the pinch roller (71), and changes in the surface texture of the outer periphery of the pinch roller (7), the pinch roller (7) As shown by the reversal of and the change in μN (f), it is reversed by the reaction force f4 and returns to f4-Δf.

In other words, the direction of the arrow (88) changes and the wire electrode (2) returns. However, Δ for 1 reaction force drop
It can be considered that this corresponds to the decrease in fIfi and μN.

Next, the direction of the arrow (88) is changed again as shown in FIG. 8(g), and the wire electrode (2) is fed. Then, by repeating the cycle of FIG. 8 (el → StV) → FIG. (8) performs intermittent rotational motion.

The length K of the wire electrode +21 sent into the range L in so-called Fig. 8 Del, G, (g),
This causes spring vibration accompanied by a change (Δf) in the reaction force f4. This movement is shown in Figure 9.

This will continue as long as the wire in the range does not buckle.

At this time, the direction changing pulley (51) shown in FIG. , it is possible to judge whether there is a high load.This detection will be referred to as detection of high load during wire electrode advancement.

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

FIG. 9 shows a case where the upper die guide (1) and the lower die guide (Co., Ltd.) are at the farthest position during the wire insertion operation. In this case, the pipe guide aη and the workpiece (to)
This is the case when the wire electrode (2) starts advancing by sensing the contact (conducting through the die guide 2).

The thickness of the workpiece (to) is the maximum Hmax. Further, the lengths shown in the drawings are specific to the two machines and can be defined arbitrarily.

First, the wire electrode +21 shown by the solid line is a case where the insertion is successful. ), lower die guide, power supply die lff
1. It is fed between the guide nozzle, the belt roller 6, the lower belt 147'l, and the lower roller, and is then pulled by the lower roller. 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 discovered a method for detecting failure based on the fact that the speed at which the wire electrode is advanced by the wire feeding pinch roller (7) shown in Fig. 1 and the speed at which the wire electrode is advanced by being pulled by the lower roller brocade are different. The next one is i.e. the lower roller (
The advancing speed due to the wire feeding pinch rollers () is as fast as the speed during electrical discharge machining, and the advancing speed due to the wire feeding pinch rollers () is slow because it passes through a small clearance such as the die guide.

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

The vertical axis of (at, (bl) is the advancing speed V of the wire electrode (2).

v2 is caused by the lower roller, and vl is caused by the wire feeding pinch roller (7). The nine horizontal axis is.

S is the length along the wire insertion path from the die guide (2) in FIG. 9, and T is the elapsed time from when the wire electrode (2) first advances by the wire feeding pinch roller (7).

First, in (a) the graph of FiV and S, if (89) is a successful insertion, (90) is a failed insertion.

As you can see from this graph, Hmax+L on the insertion path
After traveling a distance of , the speed increases from vl to v2 in case of success, and remains at vl in case of failure.

The reason why the speed does not increase immediately from vl to v2 at position L is due to the deviation due to the time taken to draw the lower belt.

Next, as can be seen from the graph in FIG. 10(b), the time TL for the speed to increase from V to v2 in FIG. 10(a) is uniquely determined. Therefore, from the beginning when the wire electrode (2) is advanced by the wire feeding pinch roller ()), the maximum TI
If, after , the advancing speed has not increased from V to (2), it can be determined that the wire has deviated from the wire insertion path and can be treated as a failure.

In this way, the wire electrode (2) is moved by detecting the change in the speed of movement after a certain period of time after the wire electrode (2) first moves forward.

Failures can be detected. 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 described.

First, as explained in FIG. 8, in order to detect the intermittent movement of the advance of the wire electrode (2), the intermittent movement of the rotation of the direction changing boob IJ-fell shown in FIG. 1 is replaced with the intermittent movement of the rotation.

FIG. 11 shows a detection device for this purpose. Figure 11(a)
In the FC, an encoder (91) is attached to the direction conversion pulley 15+K. Wire electrode (2)
When the direction change pulley (5) makes an intermittent movement, the rotational movement of the direction changing pulley (5) becomes intermittent. Also, Fig. 11 (bl explains how to use the encoder (91). P5 (+5V)
The external power supply is shared between the diode side and the transistor side. R is a resistor that limits the current flowing to the diode. The output side A and B terminals are connected to the 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.

Referring to Fig. 12, since the encoder output is AC in the range of 0 to 5V, first capacitor C1 and resistor R1
By cutting the DC component, only the social gathering is possible. Next, the OP amplifier (92) performs amplification by twice R, /R.

After that, diode D1. Clamp in the range of 0-5v by D2. The waveform of W2 after passing through the inverter is converted into a pulse in the range of 0 to 5V by shaping the alternating current of W. (95) is a one-shot for high load detection.

The output pulse has a width of TCl. The relay coil L1 is for high load detection, and tD3 is a protection diode. Further, (94) is a one-shot for failure detection outside the insertion path, which will be described later, and the output pulse has a width of Ta2.

Relay coil L2 is for detection outside the insertion path, and D4 is a protection diode.

Using the waveforms of wl, w2, and WA in FIG. 12, a schematic timing chart is shown in FIG. 13 to explain the high load detection method.

W 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 wire is inserted. At this time W
The waveform No. 2 is a square wave pulse with a period T1. Since the waveform of W3 generates a one-shot pulse at the rising edge of the pulse of W2, it is always at the high level of Vcsv during wire insertion since Ti<Tct.

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

Next, under the conditions (el, (f), and (g) in Figure 8), the waveform becomes W2 in Figure 13 (b).In other words, the period T1 and pulse width are short with normal pulse width. The long pause period T2 appears repeatedly.This is because the encoder outputs pulses even when reversed.

As shown in Fig. 8(f), the wire electric fi! F (2
When + is returned, a reverse rotational force acts instantaneously, and the pause at T1 in FIG. 13 (bl) is short, and the pulse at T2 is also short.

On the other hand, in the case of Fig. 8 (g), the rotation of the pinch roller for wire feeding is when the forward rotation is started, so the maximum start-up time is required, so T2 in Fig. 13 (b) is As a result, the pause becomes longer. When the detection circuit is actually observed with a synchroscope etc., K is also W in (b)
A waveform equivalent to 2 was confirmed.

As a result, a zero level with a width of Tf occurs in the waveform of W3. At this time, the relay coil L in Fig. 12
1 is in the OFF state. In this way, relay coil L1 is turned ON to indicate that intermittent rotational movement of the direction change/exhaust pulley has occurred.
It can be detected by the state change from 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 when inserting the wire, and the section of Ts seen at W in FIG. 14(a) is the first
This is the same situation as in Figure 3(a), and is caused by the rotation of the wire feeding pinch roller (7). The subsequent high frequency portion is drawn into the lower belt 14n in FIG. 9 and shows a state in which the advancing speed of the wire electrode (2) increases.

Therefore, as seen in Figure 14 Φ)K.

The period of TS has a period Ti, and thereafter changes to a period Tm. At this time, the waveform of W4 has a one-shot width of Tc 2 (T 1 > TC2 > Tm).

During the period Ts, the pulse width is Tc2, and after that it is a high level trap. Therefore, since Ts corresponds to the time when the insertion is successful, 1, for example, Ts(TD becomes the time TD
Afterwards, the state of W4 becomes always high level. That is, the relay coil L2 in FIG. 12 is always in the 1 c ON state after TD after the wire feeding pinch roller (7) starts rotating. ) progresses, as shown in FIG. 14(b), the waveform of w2 continues as a pulse with a period of Ti, and the waveform of W4 continues with a pulse width of Tc2. So e TD (
After TD>TS), by looking at the waveform of W4, it can be seen that there is a pause Tf2.

At this time, the relay coil L2 in FIG. 12 is in the OFF state. In this way, if the wire electrode (21) comes off the insertion path during insertion of the wire electrode (2), it can be detected by determining the OFF or OFF state of relay coil L2 from ON after TD. be able to.

Next, a logic detection circuit that generates a failure detection signal from the states of the above-mentioned relay coils L, L2 will be explained with reference to FIG.

Timer relay RT, RT2. relay f,,f
The coil No. 2 operates at P24 (+24V) "t". #M
This is a relay for a wire insertion command that is given manually by a 20tl computer or the like, and #WF' is a relay that is turned ON while the pinch roller for wire feeding is rotating.

First, in the case of a high load failure, the wire insertion starts, relay #WF is turned ON, and the timer RT.

is set. Relay #RT, 2 Sal: KO after
Become N. The pack contact of relay $IRA is open during normal operation and closes when a failure occurs, resulting in a short circuit, so failure detection relay #f1
is turned ON and held. The relay @RT has a detection inhibiting function to prevent false detection when the wire electrode (2) starts to advance.

Next, in case of failure outside the insertion path, start from the beginning of wire insertion.
Timer RT2 is set. Relay #: RT2 is T
It turns ON after D. Since relay #2RA is short-circuited in the event of a failure, similar to a high-load failure, failure detection relay #f2 is turned ON and held.

Therefore, for both failures, relay #f
1 or #f2 is turned ON. Therefore, P5(+
5V) Against K Te'J'＃' 1t ＃'
2': When placed in the M column, the F output changes to high level for either failure. This F signal may be transported to a computer or the like.

Next, when the F signal is processed using a computer, the processing method to be used will be explained using the flowchart shown in FIG. 16.

1. First, a flow start command is issued to perform the insertion operation. Unless a failure is detected (two issues are at a high level), the insertion will be successful. If a failure is detected, it is determined whether the number of failures has reached N times. If it has reached N times.

Due to an abnormality in the mechanical equipment, it will stop functioning.

If the number of times has not reached N, issue a disconnection command.

Make cutting work. What do we mean by cutting and inserting here?

This means the series of operations shown in FIGS. 3 and 4. however,
In case the cutting operation fails, the wire electrode r21 is removed and inserted into the cutting device shown in FIG.

Perform this using a new wire electrode (2).

After the cutting is completed, the insertion command is issued again and the cycle of inserting operation is repeated. In this way, the flow of FIG. 16 is repeated until the number of successful and unsuccessful insertions reaches ljK.

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 successive failures N times becomes H and XN. Therefore, the probability P that the wire insertion is successful at the m-th time is as follows.

P (E) = 1-xm (Example) +1) X: 50% (7) If m = s times P (51:97% m = 7 times P +71 = 99% (4) X = 3
For 0%, m = 3 times p (3+ = 97% m = 4 times p (41 = 99 T.

As you can see in the example above, the success rate for one insertion is 50% (X
= 5096), the success rate can be increased to 99 by detecting the T slip and trying the insertion again. Furthermore, if the success rate for one attempt is 70% (X = 30%), if the insertion is repeated four times, the number increases to 99chi. In this way, even if the probability of successful insertion at one time is low, the success rate can be increased by repeating insertion several times. In other words, it can be said that the reliability of insertion is significantly improved.

In summary, the present invention detects failure or failure during wire electrode insertion and re-inserts the wire.
We provide a highly reliable automatic wire feeding device that will lead to success.

It goes without saying that the scope of the present invention includes any method that automatically corrects insertion by using other means for detecting failure.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional wire electrode automatic supply i@ device.
FIG. 2 is a diagram showing the configuration of a conventional cutting device, FIG. 3 is a diagram showing the conventional cutting operation, and FIG. 4 is a diagram showing the wire electrode insertion operation.
Figures 5 and 6 are diagrams showing the conventional drawbacks, Figures 7 to 10
Figure 11 explains the reason for the drawback and the ripple effect.
12 is a diagram showing a ninth embodiment of the detection means and circuit that implements the present invention, FIGS. 13 and 14 are timing charts of the detection circuit and diagrams showing the detection principle, and FIG. 15 is an insertion failure signal The 16th factor is a flowchart for implementing the present invention by computer. In the figure, (2) is a wire electrode, and (5) is a direction changing pulley. (91) is an encoder, (92) is an OP amplifier,
(95). (Figure 9 is a one-shot. The same reference numerals in Figure 1 indicate the same parts. Figure 1 Figure 2 Figure 5 (a) (b) (a) Q)) Figure 3 Figure 4 ( a') (b) (C') (d') Figure 9 Figure 10 Figure 11 Eng (a) (b) q Figure 13 (a) Figure 14 (a) (b) Figure 15 Figure 16

Claims (3)

[Claims] (1) Wire cut discharge that automatically feeds the wire electrode so that the wire electrode passes from the wire electrode feeding device to the machining start hole of the workpiece and is further engaged with the wire electrode recovery device. In a wire electrode automatic supply device in a processing device, a first detection device detects that the wire electrode does not engage with a wire collection device during wire automatic feeding, and a wire a return device that returns to the initial state before feeding the electrode; a second detection device that detects the return to the initial state; and a return device that returns the wire to the wire electrode feeding device again based on the detection signal of the second detection device. 1. An automatic wire electrode feeding device for a wire-cut electrical discharge machining machine, comprising a command device that commands wire feeding, and a counter that counts the number of times the command device issues a wire feeding command. (2) The first detection device is a device that detects that the advance of the wire electrode is obstructed during the regular feeding route of the wire electrode, or that the wire electrode is advanced in a direction other than the regular feeding route. An automatic wire electrode feeding device in a wire-cut electrical discharge machining apparatus according to claim 1, characterized in that the device comprises a device for detecting a dead state. (3) A third detection device that detects that the wire electrode has engaged with the wire electrode collection device is provided, and the refeeding of the wire electrode is completed by a detection signal from the third detection device. An automatic wire electrode feeding device for wire-cut electric discharge machining equipment according to claim 1 or 2.