JPS6218291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic wire electrode insertion method for automatically inserting a wire electrode of a wire cut electric discharge machining apparatus into a prepared machining hole of a workpiece, and an apparatus for carrying out the method.

Wire-cut electric discharge machining equipment is currently widely used in mold machining and other applications because it can be machined in any shape and can be operated unmanned for long periods of time using an NC control device, and its machining accuracy has also been significantly improved. are doing.

However, in the processing of progressive molds, extrusion molds, etc. in which multiple parts are processed in one mold, the processing contour line is rarely formed by a single line, and the processing of one shape is difficult. Each time the wire is finished, it is necessary for the operator to cut the wire electrode, insert it into a pilot hole prepared at the start point for the next machining, and then route it to a predetermined guide roller, etc. Everything was done by hand.

Therefore, even though most of the machining conditions such as electrical discharge conditions, machining feed, circulating supply of machining fluid, etc. of wire-cut electrical discharge machining equipment are currently automatically controlled,
The fact that only the wire electrode insertion work has not yet been automated is a major obstacle to realizing long-term unmanned operation.

The main reason why the electrode insertion work has not been automated until now is that in order to ensure the straightness of the wire electrode necessary for insertion, there is no suitable means other than applying a certain external restriction to the electrode. For example, it was impossible to obtain enough linearity to accurately catch a pilot hole drilled in a workpiece simply by the weight of the wire electrode. That is, during processing, the wire electrode is supplied to the processing part from the wire electrode supply drum via several rollers such as a guide roller, brake roller, and power supply roller, and then is collected by a recovery device again via a plurality of guide rollers. It is becoming more and more
In the processing section, special consideration has been taken, such as by applying a certain tension to the machine so that it travels in a straight line, which is essential for processing. However, once the wire electrode is cut, the electrode is released from tension and immediately loses its linearity due to its curling tendency. Therefore, in order to automatically insert such a wire electrode into a prepared hole for machining of a workpiece, extremely complicated mechanisms such as an electrode gripping means, a means for detecting the position of the prepared hole for machining, and an electrode feeding means are required. This requires a control device, and a means to solve this problem with a simple device has not yet been provided.

The present invention has been made based on the above-mentioned viewpoints, and an object of the present invention is to eliminate the work of inserting a wire electrode into the workpiece when changing the machining position, which was conventionally done manually. The object of the present invention is to provide a method and apparatus for automation using relatively simple means.

The gist of the method of the present invention is to utilize the linearity of the wire electrode in the machined part after electrical discharge machining. That is, cut the wire electrode while preserving this straight line state, gently pull it up at the position where machining is finished, move the new machining pilot hole to the straight line below the electrode, and lower the wire electrode as it is below this point. It is inserted through the hole. To explain this in more detail, the wire electrode before discharge has distortions such as curling and guiding by guide rollers, etc., so when it is cut, it immediately loses its linearity. However, at least in the section where electrical discharge occurs between the machined part and the workpiece,
In addition to being pulled in a straight line, it is heated by the electrical discharge and cooled by the machining fluid, and the non-linear distortions such as curling that it had previously had are largely removed.
Therefore, when cutting and pulling out the wire electrode after finishing the machining of one machining contour line, in the present invention, the feeding of the wire electrode is immediately stopped at the same time as the discharge current for machining is cut off. Or, separately, the wire electrode is subjected to a running electric discharge treatment in the hole of the workpiece, for example, and then stopped.
The wire electrode is cut at a portion of the lower workpiece on the wire electrode winding side, and the electrode left in the workpiece is pulled out upward or downward as it is.
In this way, the wire electrode that has been pulled out is the part that has had its distortion removed by the discharge, so
It has sufficient straightness required for insertion work. It is not appropriate to wind up only the electrode with a roller or the like when pulling out the wire electrode, as this may cause the electrode to shake or create new kinks. Therefore,
The wire electrode is pulled out by lifting or lowering it together with its electrode guide, ie by sliding the processing head itself upward or downward. The same applies when raising or lowering.

In addition, to prevent the wobbling of the drawn wire electrode,
A guide arm with a guide hole to hold the tip of the electrode that has been pulled out is installed to determine the electrode position and serve as a guide when inserting the wire electrode into the next prepared hole for processing. .

Next, the pilot hole for machining, which will be the starting point for the next machining shape of the workpiece, is moved directly below or directly above the tip of the drawn wire electrode, but this is the same value as the normal machining feed. This may be done by a controlled sequential positioning means, and the position of the prepared hole may be written in advance in the program of the NC device.

If the machining head is raised or lowered as it is, the straight wire electrode will insert itself into the prepared machining hole of the workpiece, and its tip will be placed at the position of the electrode cutting device below or above the workpiece. Therefore, if the guide rollers for feeding the wire electrode are driven again at this point, the tip of the electrode passes between the predetermined rollers and reaches the electrode collection device. In this way, the series of electrode insertion operations is completed, and the next electrical discharge machining can be started immediately. The above-mentioned series of operations include stopping electrical discharge at the end of machining one machined shape, stopping the wire electrode from running, cutting the electrode, pulling out the electrode, moving the workpiece, raising or lowering the electrode, starting electrode feeding, starting electrical discharge, etc. The work is carried out directly by commands from the NC device.
Alternatively, it can be executed using a known simple logic or discrimination circuit.

In addition, if the straightness of the drawn part of the wire electrode cannot be obtained sufficiently by electric discharge alone, when the electric discharge and electrode feeding are stopped after finishing machining of one part, before cutting the electrode, In other words, while the electrode is stationary at the machined part and pulled linearly by a constant tension, the electrode is heated by means such as passing a relatively large current through the electrode itself, and the non-linearity of the electrode is reduced. The habit may be removed.

Hereinafter, the method according to the present invention and the method according to the present invention will be explained using the drawings.
A device that implements this will be specifically explained.

FIG. 1 is an explanatory diagram showing one embodiment of the wire electrode automatic insertion device according to the present invention, FIG. 2 is a functional explanatory diagram of the device, FIG. 3 is an explanatory diagram showing another embodiment, and FIG. FIG. 6 is an explanatory diagram showing another example of the guide arm.

In Fig. 1, 1 is a column of a wire-cut electrical discharge machining device, 2 is an upper arm extending from column 1, and 3
is a lower arm, 4 is a processing head, 5 is a driving screw for sliding the processing head 4 up and down with respect to the upper arm 2, 6 is a driving motor thereof,
7 is a wire electrode; 8 is a wire electrode cutting device; 9 is a guide arm that has a guide hole 9a at its tip and is attached to the upper arm 2 by a fixture 9b with its vertical position adjusted; 10, 10 are Wire electrode retraction belt, 10a, 10a is retraction belt 10,1
0 is a running roller, 11 is a wire electrode supply drum, 12 is a brake roller, 13, 14, 15
is a guide roller, 16 is a current-carrying roller, 17, 20
is a capstan, 18 and 21 are pinch rollers, 1
9 and 22 are electrode guides such as boat-shaped guides, 23 is a machining liquid nozzle, 24 is a machining liquid supply pipe, 25 is an electrode recovery device, 26 is a workpiece, 27 is a stage, 2
8, 29 are cross slide tables, 30, 31
is the table drive motor.

During electric discharge machining, the wire electrode 7 is pulled out from the electrode supply drum 11 at a constant speed by the capstan 20 and the pinch roller 21, passes through the rollers 12 to 16, and is delivered to the machining part where the workpiece 26 is placed. Supplied. In the processing part, the wire electrode is stretched in a straight line with a constant tension between electrode guides 19 and 22 such as boat-shaped guides, and
6 and the workpiece 26 by a discharge voltage applied between the workpiece 26 and the workpiece 26 . Workpiece 2
6 is a cross table 28, 2 using an NC device.
By driving 9, it is moved in a direction perpendicular to the direction in which the electrodes are stretched, and processing is performed in accordance with the processing contour line. Note that machining fluid is supplied to this machining portion from a machining fluid nozzle 23 in order to remove machining debris and the like to smoothen the electrical discharge. The wire electrode that has passed through the processing area in this way passes between the electrode guide 22, the capstan 20, and the pinch roller 21, and then passes between the retraction belts 10 and 10 that are running by the rotation of the rollers 10a and 10a. The electrode is passed through and discharged to the electrode recovery device 25. The above configuration is the same as the basic configuration of a normal wire-cut electric discharge machining apparatus, except for the use of retraction belts 10, 10.

Therefore, in order to carry out the electrode automatic insertion method according to the present invention, the device of the present invention has an upper electrode guide 1.
A guide arm 9 having a guide hole 9a through which the electrode 7 is inserted is provided directly below the workpiece 26 and above the workpiece 26, an electrode cutting device 8 is provided below the workpiece 26, and the arm 2 is provided with a machining head 4 that can be moved up and down, and a capstan 17 and a pinch roller 18 can be added as required. Another feature of this apparatus is that by using the retraction belts 10, 10, the tip of the wire electrode can be easily captured after being automatically inserted into the workpiece.

The functions of the apparatus of the present invention will be explained below with reference to FIG. In FIG. 2, after the machining of one shape on the workpiece 26 is completed at the portion 26a, the electrode is automatically inserted into the next machining pilot hole 26b, and the process can be resumed until machining can be resumed. It is shown.

That is, when the wire electrode 7 reaches one machining end position 26a of the workpiece, the discharge current is cut off and at the same time all rollers for running the electrode are stopped. ……A diagram. At this time, the substantially straight wire electrode 7, from which most of the non-linear tendencies such as curls have been removed by the discharge, remains in the portion 26a. However, if the kinks cannot be removed sufficiently by discharging alone, the energizing roller 16 and the electrode guide 22, or the capstan 2 may be provided separately.
0. Electricity is applied to the electrode through the pinch roller 21 to heat the electrode, thereby removing any remaining non-linearity and maintaining it in a substantially straight line without any external force acting on it. Next, the electrode cutting device 8
Cut the electrode below the processed part using a . ……
...B figure. In this case, a gripper for the wire electrode may be provided between the device 8 and directly below the workpiece so that the wire electrode can be cut properly without bending. The cutting device 8 in the embodiment shown in FIG. 1 consists of a substrate 8a having a hole through which the electrode passes, and a blade plate 8d that slides along the substrate 8a by a cam 8c attached to a motor 8b. The electrode is mechanically cut by a blade plate 8d. Thermal cutting or other means can optionally be used as long as they do not impair the linearity of the electrode. Next, the electrode 7 with its straight portion preserved is pulled out from the hole 26a of the workpiece by pulling up the processing head 4. ……Ha diagram. The pulling length at this time is from the cutting device to the guide hole 9a.
This length has already been determined when the position of the guide arm 9 is adjusted and fixed in advance with the fixture 9b according to the thickness of the workpiece. Therefore, there is no need for a sensor to detect the position of the electrode tip, and the length may be stored in advance in the program of the NC device or the control device of the processing head slide device. The workpiece 26 is then moved so that the next prepared hole 26b for machining is located directly below the guide hole 9a. ……Diagram 2. This is done by driving the cross slide tables 28, 29 in rapid traverse using the same means as for machining feed. Thereafter, when the machining head 4 is lowered to its original position, the electrode is inserted into the prepared machining hole 26b. ……E diagram. If the diameter of the guide hole 9a is made smaller than the diameter of the pilot hole 26b for processing, there is no fear of malfunction during insertion. At this time, the tip of the electrode has reached the position of the electrode cutting device 8. In order to send this further downward, the processing head 4 may be lowered further, but since there is a limit to this, only the electrode is moved using the capstan 17 and the pinch roller 18. ...Figure F. That is, the capstan 17 and the pinch roller 18
is a device provided to feed the tip of the electrode from the position of the cutting device 8 to the position where the retraction belts 10, 10 are present, and are usually separated from each other (during electrical discharge machining), so that the wire electrode does not run. This is a device that has no effect on the On the other hand, a capstan 20 and a pinch roller 21 play the role of making the wire electrode run at a constant speed during electrical discharge machining.
It is appropriate to separate the electrodes from each other only during this period so that they do not become an obstacle when the electrode tips advance to the position of the retracting rollers 10, 10.
If the rollers 10a, 10a are rotated and the retraction belts 10, 10 are run, the electrode tips will be drawn into the space between the belts and reach the collection device 25 at the same time as the electrode tips come into contact with the belts. The capstan 17 and the pinch roller 18 are separated again, and the capstan 20 and the pinch roller 21 are brought back into contact with each other.

As a result of the above, all the series of electrode insertion operations are automatically completed, and the electrical discharge machining is then restarted in the same state as shown in FIG. 1 for the prepared machining hole 26b.

FIG. 3 is an explanatory diagram showing another embodiment of the wire electrode automatic insertion device according to the present invention, and FIG.
In the figure, this device is similarly equipped with the components indicated by 1 to 31, but this device is different from the one in FIG. 1 in that the upper arm 2 is configured to be able to move up and down. They are different. That is, the upper arm 2 can be moved up and down by a motor 33 along a guide rail 32 provided on the column 1. Such a configuration is advantageous when automatically inserting an electrode into a workpiece 26 whose thickness varies as shown in the figure. That is, the hole 26 of the workpiece 26
When moving the electrode that has finished machining at part a to the hole 26b, the guide hole 9a is quite far vertically from the hole 26b, so even if the electrode that has been pulled up once is lowered, it will accurately catch the hole 26b. On the other hand, when trying to move the workpiece toward the hole 26c, the guide arm 9 collides with the workpiece and the workpiece cannot be moved. In such a case, if the upper arm 2 is moved up and down by the amount of change in the thickness of the workpiece, the position of the guide arm 9 will also change according to the height of the top surface of the workpiece. As a result, the electrode can be inserted into each prepared hole without any problem. The processing head 4 slides up and down with respect to the upper arm 2, as in the previous embodiment. In short, this embodiment can be said to have a configuration with wider adaptability that can accommodate more types of workpieces than the embodiment shown in FIG.

FIG. 4 is an explanatory diagram showing another embodiment of the guide arm 9, and FIG. Figure B is a plan view of only the guide arm 9.

Guide hole 9 provided at the tip of guide arm 9
As mentioned above, point a is set as close to the workpiece as possible between the workpiece and the processing head, and the cut electrode tip is maintained so that it does not shake, and the electrode is inserted into the next prepared hole for processing. It serves as a guide for appropriate introduction. Therefore, it is better to make the inner diameter as small as possible so that it is close to the electrode diameter, and it needs to be at least smaller than the inner diameter of the prepared hole for processing.
However, during electric discharge machining, it is necessary to constantly supply machining fluid from the machining fluid nozzle 23 to the machining part, and making the inner diameter of the guide hole too small results in obstructing the flow of the machining fluid, which is not necessarily appropriate. In order to solve such problems, the fourth
In the example shown in the figure, the guide part at the tip of the arm that forms the guide hole is divided into two parts, and the two divided guides are separated during electrical discharge machining, and only when the machining is interrupted and the electrode is inserted. The two separation guides are configured to match.

That is, in FIG. 4, 9 is the entire guide arm, 9a
9b is a fixture that adjustably fixes the guide arm support shaft 9c to the upper arm 2, and 9d is fixedly attached to the guide arm support shaft 9c. supporting frame, 9
e, 9f have split guides 9a', 9 at their respective tips.
a′, and at its bent portion, the pin 9g,
9h is a rotating arm rotatably attached to the support frame 9d; 9i is a pin that is loosely fitted into a slide hole provided in each of the rotating arms 9e and 9f and locks both rotating arms; 9j is a pin that is loosely fitted into a slide hole provided in each of the rotating arms 9e and 9f; A tension spring suspended between the support frame 9d and the rotating arm 9e, 9k a drive device having a lever 9m and fixedly attached to the support frame 9d, and 9n projecting onto the rotating arm 9f and fixedly attached thereto. This is the driven pin.

During electrical discharge machining, the rotating arm 9e is pulled by the tension spring 9j, and the rotating arm 9f also receives that force via the locking pin 9i, resulting in the state shown by the dotted line in Figure B. Accordingly, the divided guides 9a' and 9a' provided at the respective tips are also separated from each other by a large distance. Therefore, the machining fluid flowing out from the machining fluid nozzle 23 is supplied to the machining part without any hindrance. On the other hand, when processing is interrupted and the electrode is moved, the drive device 9k is operated and the lever 9m pushes the pin 9n attached to the rotating arm 9f outward. In this case, the rotating arms 9c and 9f are in the state shown by the solid line in Figure B, the divided guides 9a' and 9a' are combined to form the guide hole 9a, and the wire electrode is held in the guide hole. It will be done. In addition, the rotating arm 9
In order to rotate e and 9f, it is not necessarily necessary to install a drive device 9k and a spring 9j near the support frame 9d, and the driving force is transferred from the drive device provided in the upper arm 2 to the support shaft 9c. The information may also be transmitted through.

Since the method and apparatus of the present invention are configured as described above, the wire electrode insertion work, which is the key to realizing long-term unattended operation of wire-cut electrical discharge machining equipment, is complicated. It is automated without the need for any mechanical mechanisms or control devices.

Note that the method of the present invention is not limited to a wire-cut electrical discharge machining device that performs machining feed by moving the workpiece, but can also perform machining feed by moving a column or a machining head relative to the workpiece. It can also be applied to wire-cut electrical discharge machining equipment. Alternatively, in addition to inserting the electrode into a plurality of holes for machining provided in one workpiece as described above, it is also possible to insert the electrode into the holes for machining of a plurality of workpieces lined up at predetermined positions on a processing table. It will be easily understood that the device can be used as is even when an electrode is inserted through the hole.

Note that the configuration of the device of the present invention is not limited to the above-mentioned embodiments. That is, for example, as a means for automatically changing the height of the guide arm 9 in accordance with changes in the thickness of the workpiece, the upper arm 2 is raised and lowered in the embodiment shown in FIG.
Instead, only the guide arm 9 may be automatically slid with respect to the upper arm 2, and instead of using the retraction belts 10, 10 as the electrode retraction device, for example, the guide arm 9 may be automatically slid relative to the upper arm 2. 54
The electrode drawing device disclosed in Japanese Patent Publication No. 146995 may be used, and furthermore, widely known means may be used for the specific configuration of the cutting device 8 and the guide arm 9, and the device of the present invention may be used. This includes all such configurations whose design has been changed within the scope of the purpose of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the wire electrode automatic insertion device according to the present invention, FIG. 2 is an explanatory diagram of the function of the same device, FIG. 3 is an explanatory diagram showing another embodiment, and FIG. It is an explanatory view showing other examples of a guide arm. DESCRIPTION OF SYMBOLS 1... Column, 2... Upper arm, 3... Lower arm, 4... Processing head, 5... Drive screw, 6... Drive motor, 7... Wire electrode, 8
...Wire electrode cutting device, 9...Guide arm,
9a... Guide hole, 10, 10... Electrode retraction belt, 16... Current roller, 17, 20... Capstan, 18, 21... Pinch roller, 19,
22... Electrode guide, 23... Machining liquid nozzle, 2
6... Workpiece, 26b, 26c... Prepared hole for machining, 32... Guide rail, 33... Motor.

Claims (1)

[Scope of Claims] 1. A method for automatically inserting a wire electrode of a wire-cut electric discharge machining device into a prepared machining hole of a workpiece, characterized by comprising the steps described in the following items (a) to (f). Automatic wire electrode insertion method. (a) A process of cutting off the discharge current between the workpiece and the wire electrode and simultaneously stopping feeding of the wire electrode at the time when machining of one machining shape on the workpiece is completed. (b) A step in which the wire electrode is cut above or below the workpiece opposite to the feeding side of the wire electrode, with the straight part of the wire electrode remaining in the processing part. (c) A step in which the processing head on the wire electrode feeding side is moved in the axial direction of the wire electrode in the processing section in order to pull out the straight wire electrode left in the processing section from the workpiece. (d) A step of moving the workpiece or the processing head so that the next pilot hole for processing on the workpiece comes to a position opposite to the tip of the drawn straight wire electrode. (e) A step of moving the processing head on the wire electrode feeding side in the electrode axis direction in order to insert the drawn straight wire electrode into the processing hole. (f) A step of driving a wire electrode retracting device to capture and retract the tip of the straight wire electrode inserted into the pilot hole of the workpiece. 2. A method for automatically inserting a wire electrode of a wire-cut electrical discharge machining device into a prepared machining hole of a workpiece, which is characterized by comprising the steps described in items (g) to (m) below. Method. (g) A process of cutting off the discharge current between the workpiece and the wire electrode and simultaneously stopping feeding of the wire electrode at the time when machining of one machining shape on the workpiece is completed. (h) A step in which a current sufficient to heat and harden the wire electrode is applied to the straight portion of the wire electrode that is stationary in the processing area. (i) A process in which the wire electrode is cut above or below the workpiece opposite to the feed side of the wire electrode, with the straight part of the wire electrode remaining in the processing part. (o) A process of moving the processing head on the wire electrode feeding side in the direction of the wire electrode axis of the processing section in order to separate the straight wire electrode left at the tip of the wire electrode feeding side from the workpiece. (k) A process of moving the workpiece or processing head so that the next pilot hole for processing on the workpiece is in a position opposite to the tip of the above-mentioned straight wire electrode. (l) A step of moving the processing head in the axial direction of the electrode in order to insert the linear wire electrode into the prepared hole for processing. (m) A step of driving a wire electrode retracting device to capture and retract the tip of the straight wire electrode inserted into the pilot hole of the workpiece. 3. An automatic wire electrode insertion device for carrying out the method according to claim 1, characterized in that the automatic wire electrode insertion device comprises the components described in the following items (n) to (q). (n) A processing head that has a capstan and a pinch roller through which a wire electrode is inserted on the upper or lower surface of the workpiece, and is supported so as to be able to move up and down together with the wire electrode. (o) A guide arm having a guide hole through which a wire electrode is inserted close to the top or bottom surface of the workpiece. (p) A wire electrode cutting device capable of cutting the wire electrode above or below the workpiece. (q) Provided below or above the workpiece,
A wire electrode retracting device that can catch and retract the tip of a wire electrode inserted into a workpiece. 4. The wire according to claim 3, wherein the guide hole provided in the guide arm is a guide hole whose inner diameter is smaller than the inner diameter of a prepared hole for machining bored in the workpiece. Automatic electrode insertion device. 5. The wire electrode automatic insertion according to claim 3, wherein the guide arm is a guide arm whose position can be automatically changed in the vertical direction depending on the thickness of the workpiece. Device. 6 The guide arm is divided into a plurality of divided guides at the portion forming the guide hole, and each divided guide is separated from each other during electrical discharge machining, and each divided guide is aligned only during wire electrode insertion work. The wire electrode automatic insertion device according to claim 3, characterized in that the guide arm is configured to form the guide hole.