JP2697993B2 - Initial hole detector for wire electric discharge machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire electric discharge machine for performing electric discharge machining of a workpiece using a wire electrode.
Wire discharge that accurately detects the center position of the initial hole formed in the work, positions the wire electrode through hole of the head of the wire electric discharge machine at the center of the initial hole, and reliably performs the automatic connection of the wire electrode. The present invention relates to an initial hole detection device for a processing machine.

[0002]

2. Description of the Related Art In a wire electric discharge machine, in order to carry out electric discharge machining of a work using a wire electrode, a work end face is used as a machining starting point, and a relative position is formed between the wire electrode and the work from the work end face according to a predetermined machining path. At the same time as the method of performing processing while giving a good feed, an initial hole formed in the work, a so-called pilot hole, is opened, and a wire electrode is inserted through this initial hole from the upper head to the lower head, and the initial hole is formed. Is used as a starting point of electric discharge machining to perform electric discharge machining of a work. For this,
Recently, wire electric discharge machines, the body of the machine,
In many cases, an initial hole processing device is attached to the upper head using an appropriate bracket member, etc., and the initial hole is formed at a predetermined position on the work using the initial hole processing device. Have been.
As an initial hole machining apparatus of this type, in general, a rod-shaped electrode having a predetermined diameter is often formed by electric discharge machining while being sent to the inside of the work at an initial hole forming position of the work.

When such an initial hole is used as a starting point for electric discharge machining of a work, a conventional wire electric discharge machine guides the upper and lower heads of the machine to the position of the initial hole of the work, and then, for example, the tip of the upper head. Controls the well-known automatic connection mechanism that guides the wire electrode to the lower head located at the opposing position via the initial hole using the machining fluid flow ejected from the hole etc., and captures the tip of the electrode with the lower head,
When the wire electrode fails to pass through the initial hole at this time, a method in which an operator assists the insertion of the wire electrode is generally adopted. Was.

[0004]

However, the wire electrode used in a normal wire electric discharge machine is a fine wire having a diameter of at most about 0.2 mm. Therefore, the initial hole serving as a machining starting point has a diameter of: In the case of a normal wire electric discharge machine, the diameter is 0.5 mm to 1.0 mm.
It is selected in the range of pores on the order of millimeters. Therefore,
In particular, as the hole diameter of the initial hole is smaller, the difficulty of processing the hole using an electrode rod or the like increases, and the processing position of the initial hole is shifted from the set hole position, and the roundness of the hole is distorted. As a result, inconvenience occurs in which the centering accuracy between the wire electrode passage openings of the upper and lower heads and the center position of the initial hole is reduced, and as a result, the automatic connection of the wire electrodes is performed using the automatic connection mechanism. When the connection is performed, the leading end of the wire electrode passes through the initial hole and is guided from the upper head to the lower head, thereby causing a problem that the success rate of the automatic connection in which the leading end is captured is reduced.

Therefore, an object of the present invention is to solve the problem in the automatic connection function in such a conventional wire electric discharge machine using an initial hole. Another object of the present invention is to enable accurate detection of an initial hole in a wire electric discharge machine, to increase the accuracy of centering positioning between the detected initial hole and the machine head, and to thereby improve the accuracy of the wire electrode. An object of the present invention is to provide an initial hole detection device of a wire electric discharge machine capable of improving a success rate of an automatic connection operation.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned object, the present invention detects an initial hole formed in a work by a sensor for distinguishing it from a surrounding work area. A scanning operation is performed at a position close to the initial hole position of the work to detect two preferably axial directions of the initial hole, that is, a position of each two hole edges in the X-axis direction and the Y-axis direction. The center position of the initial hole is determined and calculated by calculating an intermediate position between the detected positions of the two hole edges in each direction as the center position of the initial hole, and the wire electric discharge machine is moved to the center position of the initial hole where the detection result is correct. To accurately position the center of the wire electrode through-hole in the head in order to improve the success rate of the automatic wire connection action by the wire wire automatic connection mechanism. It is obtained by the.

That is, according to the present invention, the center position of the initial hole is detected by inserting the wire electrode into the initial hole formed in the work and detecting the center position of the initial hole before automatic connection. In an initial hole detection device of a wire electric discharge machine for positioning a wire electrode through hole of a head, the initial hole formed in the work is attached to a body of a wire electric discharge machine capable of approaching and separating from the work, and separated from the work. Hole position identification means for generating a hole position identification signal for identifying a hole area as a peripheral work area; and scanning driving means for causing the hole position detection means to perform a predetermined scanning operation at a position close to an initial hole formed in the work. When,
An initial hole position determining unit that determines and determines the coordinates of the center position of the initial hole from the hole region identification signal of the initial hole generated by the hole position identifying unit during the scanning operation by the scanning driving unit. In addition, there is provided an initial hole detecting device of a wire electric discharge machine, wherein the wire electrode through hole of the head can be precisely positioned at the center position of the initial hole determined and determined by the position determining means.

[0008]

1 is a schematic view of a mechanism of a wire electric discharge machine equipped with an initial hole detecting device according to the present invention. FIG. 2A is a diagram showing a hole in the initial hole detecting device of the wire electric discharge machine according to the present invention. FIG. 2B is a partial schematic diagram illustrating a configuration of a main part of an embodiment in which the position identification unit is realized as an optical sensor. FIG. 2B is a partial schematic diagram illustrating a modified example of the optical sensor illustrated in FIG. , FIG. 3A shows FIG. 1 or FIG.
FIG. 3B is an explanatory plan view for explaining an operation process of scanning an initial hole of a work by the optical sensor shown in FIG. 3. FIG. 3B shows a hole center position from a hole region identification signal of the initial hole obtained by scanning by the optical sensor. FIG. 4 is a graph showing a signal diagram for explaining the principle of action to be determined. FIG. 4 is a diagram showing an optical sensor forming the hole position identification means shown in FIG. 2A and a wire electrode through hole of the upper head or the lower head. FIG. 5 is a plan view showing a fixed positional relationship with the center.
Hole position identification means, scanning drive means in the initial hole detection device of the wire electric discharge machine shown in FIG. 1,
5 is a flowchart illustrating an initial hole detection operation performed by an initial hole position determining unit.

First, referring to FIG. 1, a wire electric discharge machine equipped with an initial hole detecting device according to the present invention comprises:
This is a mechanical device for performing electric discharge machining of the work W by the wire electrode 10. The work W is controlled by the wire electric discharge machine control device 40 via the work table driving means 41 from the wire electric discharge machine control device 40 in the X and Y two axis directions orthogonal to each other in the horizontal plane. Table 4
2 mounted and held. In addition, the wire electrode 10
In the electric discharge machining section 12 for electric discharge machining of the work W, the upper head 14 is generally arranged so as to travel in a vertical direction perpendicular to both the X and Y axes orthogonal to each other in the horizontal plane. , And are guided by the lower head 16 to travel. Work W and wire 1
Between 0 and 0, a pulse voltage for electric discharge machining is applied from an electric discharge machining power supply (not shown), and is supplied to the traveling wire 10 via an appropriate power supply as is well known.
Further, between the wire 10 and the work W, an electric characteristic between the wire 10 and the work W in accordance with the residual chips in the discharge gap, for example, a voltage from a contact detection mechanism for detecting a change in voltage is also supplied to another power source. It is configured to be able to be supplied from the means at all times or as needed.

The above-mentioned wire 10 is supplied from a wire electrode supply source 18 composed of a wire bobbin.
After passing through a predetermined wire tension control device including a tension control pulley 31, a brake 32, a tension sensor 33, a torque motor 34, and the like. Through the electric discharge machining part 12 facing the work W through the lower head 1
6, after passing through the lower guide roller 20b, the traveling direction is changed, and a winding force is applied when passing between the winding roller 22 and the pinch roller 24 of the wire winding section. Sent to the department. The take-up roller 22 is driven to rotate at a predetermined speed by a take-up motor 22a. On the other hand, since the wire 10 that is running is braked by the above-described wire tension control device, the wire 10 has an appropriate tension. The wire tension set and controlled at the level is applied, and the electric discharge machining section 12 feeds the wire 10 maintained in the predetermined tension state and the work table driving means 41 in the rectangular coordinate system along a desired path. The electric discharge machining is performed between the work W to be operated. The wire bobbin of the wire electrode supply source 18 has a back tension motor 18
a is connected, and a tensile force is always applied to the wire 10 in the direction opposite to the running direction. In this way, in the leading section from the wire electrode supply source 18 to the wire tension control device, the wire 10 is prevented from being slackened by the reverse pulling force by the back tension motor 18a.

On the other hand, at the start of the operation of the wire electric discharge machine, the initial hole machining device 44 drills an initial hole Wh at a predetermined position of the work W, that is, at a position designated by the electric discharge machining program. This specified position is formed at the corner of the work W in advance by the contact detection mechanism described above, and the two-dimensional coordinates of the set reference position are detected.
The movement amount of the work and the work table from the reference position to the designated initial hole forming position is obtained by reading the coordinates by a table feed amount detecting device such as a scale (not shown) or the like, and the initial hole Wh is moved to the designated position. It pierces. Next, after the center of the drilling position and the wire through-holes at the tips of the upper and lower heads 14 and 16 are positioned, the above-described automatic connection mechanism provided in the upper and lower heads 14 and 16 (shown clearly in FIG. 1). Absent)
An automatic connection operation is performed in which the tip of the wire 10 penetrates the initial hole Wh and is captured by the lower head 16 using the processing liquid jet. According to the present invention, the initial hole Wh formed at the specified position of the workpiece W is misaligned or deformed in the course of processing by the initial hole processing device 44, so that the hole center position does not always exactly match the coordinates of the specified position. In view of this, the center position of the processed initial hole Wh is accurately and accurately detected, and the upper and lower heads 14, 1 are moved to the center position of the initial hole Wh.
6, the center of the wire through hole is accurately positioned, and then the wire 10 is automatically connected by the automatic wire connection mechanism. Thus, the success rate of automatic connection can be improved, and the results of automation and labor saving of wire electric discharge machining can be improved.

Here, a schematic configuration of the initial hole detecting apparatus according to the present invention will be described.
It is provided for detecting an initial hole Wh for the passage of the wire 10 formed as a processing start position on the workpiece W by the piercing tool 45 of the initial hole processing device 44 attached to the third or the like. In the initial hole detecting device, an optical sensor 50 (FIG. 1 shows an example of a sensor including a light emitting device 50a and a light receiving device 50b) forming a hole position identifying means, and the optical sensor 50 is used. A driving means for applying a scanning operation at a predetermined position close to the initial hole Wh (this embodiment shows a case where the work table driving means 41 also serves as a scanning driving means), and a scanning action by the optical sensor 50 When the obtained hole area identification signal of the initial hole is emitted from the light receiver 50b, an initial hole position determining means 51 for determining and determining the hole center position from the signal.
Etc. are provided.

The coordinate value of the center of the initial hole Wh determined and determined by the initial hole position determining means 51 is sent from the initial hole position determining means 51 to the wire electric discharge machine control device 40, and is controlled by the control device 40.
Moves the upper and lower heads 14, 16 relative to the coordinate values sent by the initial hole position determining means 51 through the operation of the work table driving means 41, and
Positioning is performed so that the center coordinate value of the wire through hole 6 accurately matches the center of the initial hole Wh.

Next, the configuration, operation, and effects of the initial hole detecting device of the wire electric discharge machine according to the present invention will be described based on further embodiments. FIG. 2A shows a first embodiment of the optical sensor 50 forming the hole position identification means according to the present invention, which is, for example, well-known to an optical system 50c such as a lens mounted on the upper head 14. An optical signal is transmitted from the light emitting device 50a composed of a light emitting diode or the like via an optical fiber, and the optical signal is received by the light receiving device 50b via the light receiving optical system 50d and the optical fiber, converted into an electric signal, and transmitted. Configuration.

The optical sensor 50 having the above configuration is
Only when a light detection signal emitted from the light emitting side passes through the initial hole Wh formed in the work W, the light receiving signal is transmitted from the light receiving side to the above-described initial hole position determining means 51 via the light receiving circuit 50b. Thus, a signal for detecting the presence / absence of the initial hole Wh, in other words, a signal for identifying the initial hole area as an area around the hole of the workpiece W is transmitted.

FIG. 2B shows an example of an optical sensor 50 having a light reflection system instead of the above-described optical sensor 50 having a light emission and light reception system. That is, the light projecting / receiving optical system 50e attached to the upper head 14 and the optical signal detector 50f composed of the light emitting / receiving system are connected by an optical fiber, and the light reflected signal from the work W is transmitted to the initial hole Wh.
This is an example of a configuration in which an electric signal that changes according to the presence or absence of the hole signal and that identifies the hole area as the hole surrounding area of the workpiece W is obtained from the optical signal detector 50f. Of course, in the first example described above, the light-emitting side may be attached to the upper head 14 and the light-receiving side may be attached to the lower head 16 in an upside down mounting structure. In the second example, the projection / reception optical system 50e may be attached to the lower head 16 side. Further, although not shown, a person skilled in the art can easily understand that a commercially available or well-known proximity sensor device or the like of a type for detecting a magnetic change or a capacitance change can also be used for detecting the identification signal between the hole area and the surrounding work area. it can.

In the present invention, in order to accurately and accurately detect the center position of the initial hole Wh from the hole position identification signal from the hole position identification means such as the optical sensor 50, the hole position identification means is used. The scanning operation is performed relative to the work W, and the initial hole position determining means 51 is determined from the hole position identification signal obtained in the scanning operation process.
Thus, the coordinates of the center position of the initial hole Wh are obtained.

That is, for example, the optical sensor 50
Is relatively moved in advance to a known designated coordinate position designated as a processing position of the initial hole, the optical sensor 50 is positioned at a position substantially close to the initial hole Wh. Next, the work table 42 on which the work W of FIG.
As shown in FIG. 3 (a), relative to the optical sensor 50 using the work table driving means 41 in response to a command from the controller, two orthogonal directions in the two-dimensional coordinate system (X-axis direction and Y-axis direction)
The scanning operation is performed separately in a zigzag manner. At this time, the spelling pitch Sp of the scanning operation is
It is necessary to select a small distance of about 1/2 of the diameter of the initial hole Wh, and to perform a scanning operation so as to surely scan the surrounding area including the initial hole Wh. When such a scanning operation is used, the electrical area identification signal obtained from the hole position identification means including the optical sensor 50 is provided in each of the two axial directions as shown in FIG. It is possible to detect the rising point H1 and the falling point H2 at the radial edge of the initial hole Wh. Therefore, the initial hole position determining means 51 obtains the coordinate values of the positions of the rising point H1 and the falling point H2 generated in the scanning operation process from the feed amount detecting device composed of the scale of the machine, and determines the intermediate position between the two. Is determined to be the coordinates of the center of the initial hole Wh in each axis direction, and if it is determined by calculation, the accurate coordinate value of the center of the initial hole Wh machined on the workpiece W can be detected. is there.

Next, the upper and lower heads 1 are moved to the position of the initial hole Wh of the work W determined and detected as described above.
The centers of the wire electrode through holes 4 and 16 are accurately matched, and the tip of the wire 10 is passed through the initial hole Wh from the wire electrode through hole of the upper head 14 by the connection operation of the automatic connection mechanism and captured by the lower head 16. If it is, upper and lower head 1
The center of the wire electrode through holes 4 and 16 and the initial hole W
It can be understood that an extremely high automatic connection success rate can be obtained because the center position of h is surely coincident. In the above-described scanning operation, the work table 42 is operated in a zigzag manner by the work table driving means 41.
Needless to say, a configuration capable of performing a scanning operation using an appropriate actuator means may be employed.

Here, referring to FIG. 4, it will be described that according to the present invention, the center of the wire electrode through hole of the upper and lower heads 14, 16 and the center position of the initial hole Wh can be surely matched. FIG. 4 shows, as an example, a specific configuration of an optical system 50c such as a lens of an optical sensor 50 fixed to the upper head 14, and when the optical system 50c is attached to the upper head 14 in advance, the optical path center and the upper head 14 Wire electrode through hole 14a
Is a known amount of data Xs,
Ys is set in advance in the manufacturing process of the wire electric discharge machine,
It is shown that it is fixed. The method of setting the known distance data Xs and Ys can be easily realized by various methods such as using a precision mounting and a setting jig prepared in advance, and the setting method is the essence of the present invention. Since it does not matter, further description is omitted. In addition,
The light receiving system 50d attached to the lower head 16 is the optical system 5
The lower head 16 itself may be set to a position for receiving the optical signal emitted from the upper head 14c. , The lower head 16 can be integrated to perform the positioning operation at the center position of the initial hole Wh.

Further, as shown in FIG.
The optical system 50c, 50d is provided with a shutter 56 that is operated back and forth by an air cylinder 55, and the initial hole Wh
In the electric discharge machining process other than the detection process, it is preferable that the shutter 56 closes the optical systems 50c and 50d to prevent contamination due to exposure to a machining fluid or the like. FIG. 5 is a flowchart showing the operation process of the above-described initial hole detecting device of the wire electric discharge machine according to the present invention.
Is shown in

FIG. 5 shows an initial hole processing apparatus 44.
After the initial hole Wh is formed at the designated position (see FIG. 1), the coordinates of the accurate center position of the initial hole Wh are detected, and the center coordinate position and the positions of the wire electrode through holes of the upper and lower heads 14 and 16 are detected. 7 illustrates an operation process of an initial hole detection device performed to accurately match a center. The initial hall W
If h is not machined, it goes without saying that the initial hole Wh is machined in the initial hole machining step.

In FIG. 5, a step 1 is to move the upper and lower heads 14 to a designated position of the processed initial hole Wh.
16 shows a step of moving the 16 wire electrode through-holes to substantially position the work W. The work W is moved to the upper and lower heads 14 and 16 together with the work table 42 (see FIG. 1) of the work table driving means 41. To perform positioning. In step 2, the offset amount (Xs, Y) between the optical sensor 50 forming the hole position identification means and the center of the wire electrode through hole of the upper and lower heads 14, 16 is described.
s) A relative movement is provided between the two by the amount of the optical sensor 5.
The center of 0 is moved to a position substantially close to the center position of the initial hole Wh, and is an operation preparation step of the optical sensor 50. Next, in step 3, the shutter 56 (see FIG. 4) of the optical sensor 50 is opened, and the optical sensor 50 is activated. Next, in step 4, the optical sensor 50 is caused to scan in two directions of the X-axis direction and the Y-axis direction by the drive of the work table driving means 41. As a result, an identification signal for identifying the hole region from the hole peripheral region of the work is generated from the optical sensor 50 (step 5) and sent to the initial hole position determining means 51. At this time, in step 6, the initial hole position identifying means 51 determines and detects the coordinate value of the accurate center position of the initial hole Wh from the transmitted identification signal. Thus, in step 7, the center position of the optical sensor 50 is positioned at the center position of the detected initial hole Wh. In this positioning operation, the work W having the initial holes Wh may be moved by the work table driving means 41. Thereafter, the shutter 56 of the optical sensor 50 is closed (Step 8). Further, in step 9, the center of the optical sensor 50 and the upper and lower heads 1
The upper and lower heads 14, 16 can be moved to the exact center position of the initial hole Wh by moving them back to the original position by the offset amounts Xs, Ys described above with respect to the centers of the wire electrode through holes 4 and 16. The center of the wire electrode through hole can be accurately positioned. In such an initial hole detection process, the wire electric discharge machine control device 40 may store an initial hole detection operation program and automatically execute the program in a predetermined order. The work table driving means 41 and the initial hole position determination The device 40 is configured to control the operation of the means 51 and the like.

According to the present invention through the description of the above embodiment of the present invention, the center position of the initial hole in the wire electric discharge machine and the center of the wire electrode through hole of the upper and lower heads 14 and 16 can be accurately determined. It can be seen that a matching initial hole detection action is performed.

[0025]

As is apparent from the above description, according to the initial hole detecting device of the wire electric discharge machine according to the present invention, the initial hole serving as the machining starting point formed on the workpiece to be subjected to electric discharge machining is formed around the initial hole. At this time, the hole position identifying means performs a scanning operation at a position close to the initial hole position of the work to perform the scanning operation in two axial directions, preferably orthogonal to each other, of the initial hole. That is, a signal indicating the position of each of the two initial hole edges in the X-axis direction and the Y-axis direction is generated, and the signal between the positions of the two initial hole edges in the X-axis and Y-axis directions obtained from the signals is generated. By calculating the position of the point as the center position of the initial hole, the center position (coordinate value) is determined and detected, and the correct initial value of the detection result is obtained. The center of the wire electrode through hole in the head of the wire electric discharge machine was accurately positioned to the center position of the hole, so even if the initial hole processing position was misaligned from the specified position, it was also processed to the initial hole hole Even if distortion occurs in the process, it is possible to accurately detect the center position coordinates of the processed initial hole and accurately position it with the center of the wire electrode through hole of the head, so that automatic wire connection by the wire electrode automatic connection mechanism or The success rate of the loading operation can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a mechanism of a wire electric discharge machine equipped with an initial hole detection device according to the present invention.

FIG. 2 (a) is a partial schematic mechanism diagram showing a configuration of a main part of an embodiment in which a hole position identification unit in an initial hole detection device of a wire electric discharge machine according to the present invention is realized as an optical sensor. (B) is a partial schematic diagram showing a modification of the optical sensor shown in (a).

FIG. 3A is an explanatory plan view for explaining an operation process of scanning an initial hole of a wire by the optical sensor shown in FIG. 1 or FIG. 2; FIG. 4B is a graph showing a signal diagram for explaining an operation principle for determining a hole center position from a hole region identification signal of an initial hole obtained by scanning with an optical sensor.

FIG. 4 is a plan view showing a fixed positional relationship between an optical sensor forming the hole position identification means shown in FIG. 2A and a center of a wire electrode through hole of an upper head or a lower head.

5 is a flowchart illustrating an initial hole detecting operation performed by a hole position identifying unit, a scanning driving unit, and an initial hole position determining unit in the initial hole detecting device of the wire electric discharge machine shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Wire electrode 12 ... Electric discharge machining part 14 ... Upper head 14a ... Wire electrode through hole 16 ... Lower head 40 ... Wire electric discharge machine control device 41 ... Work table drive means 42 ... Work table 44 ... Initial hole machining device 50 ... Optical Target sensor (hole position identifying means) 50a: light emitting circuit 50b: light receiving circuit 51: initial hole position determining means 55: air cylinder 56: shutter

Claims (2)

(57) [Claims] A first hole formed in the work;
Before performing the automatic wire connection by inserting the ear electrode, wherein by detecting the center position of the initials <br/> Ruhoru, wire allowed to position said initiative <br/> Yaruhoru head of the wire electrode hole to the center position of the In an initial hole detection device of an electric discharge machine, a hole that is attached to a body of a wire electric discharge machine that can approach and separate from the work and that identifies a hole area of the initial hole formed in the work as a peripheral work area. A hole position identification unit that generates a position identification signal, a scanning drive unit that causes the hole position identification unit to perform a predetermined scanning operation at a position close to an initial hole formed in the workpiece, and a scanning operation performed by the scanning drive unit. The initial hole from the hole area identification signal of the initial hole generated by the hole position identification means. An initial hole position determining means for determining and determining the coordinates of the center position of the head, and precisely positioning the wire electrode through hole of the head to the center position of the initial hole determined and determined by the position determining means. The initial hole detection device of the enabled wire electric discharge machine. 2. The hole position identification means comprises an optical sensor that optically identifies a hole area of an initial hole formed in the work from a peripheral work area and generates an identification result as an electric signal. An initial hole detection device for a wire electric discharge machine according to claim 1.