JPH10180547A - Wire type electric discharge machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire type electric discharge machine which allows judgement whether the automatic wiring of a wire electrode has been done properly without going through actual process of threading the wire electrode through an initial hole and making automatic wiring. SOLUTION: An initial hole 13a is formed in a work to be processed 13, and at the time of automatic wiring of a wire, a fluid jet 23 is spouted to the initial hole 13a to guide the wire, and the pressure after the jet 23 has passed the initial hole 13a is sensed by a pressure sensor 15b mounted on the lower head 15, and judgement is made whether the automatic wiring of the wire has been done properly through comparison of the sensing value with the threshold stored previously.

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 machining a workpiece into a desired shape while relatively moving the wire electrode and the workpiece, and more particularly, to a wire electric discharge machine using a fluid jet into an initial hole formed in the workpiece. The present invention relates to a wire electric discharge machine for judging whether or not automatic connection can be performed without guiding or inserting a wire.

[0002]

2. Description of the Related Art A wire electric discharge machine is provided with a machining voltage applied between a wire electrode and a work in accordance with a desired machining program in which electric discharge machining is started from an arbitrary point on the end face of the work or outside the work. The workpiece is processed into a desired shape by relatively moving the wire electrode and the workpiece while supplying the workpiece.

Here, as shown in FIG. 4, one work such as a die cutting (a shape formed on a work itself) or a punch shape (a cut from a work) is performed for one work. May be processed at multiple locations. In particular, in the case of multi-cavity machining in the shape of a die as shown in FIG. 4, the workpiece itself in which the punched hole is formed often becomes a product, and the electric discharge machining is started from an arbitrary point outside the workpiece end face or the workpiece. I can't start.

In this case, a pilot hole having a diameter slightly larger than the diameter of a wire electrode to be used, a so-called initial hole, is formed in a work in accordance with a die-shaped or punch-shaped portion to be processed, and a fluid is directed toward the initial hole. Automatic connection of the wire electrodes is performed by jetting a jet to guide the wire electrodes into the initial holes. Thereafter, the electric discharge machining is performed with the initial hole as a starting point, and after completion of the machining, the wire electrode is once cut, and the operation of automatically connecting the wire electrode again in another initial hole and performing the electric discharge machining is sequentially repeated. A simple machining program is created and executed, and electric discharge machining is performed at a plurality of locations on one workpiece.

However, if there is a mistake in creating a machining program or a mistake in the hole position or hole diameter of an initial hole to be formed in a workpiece, the initial hole formation position and the fluid jet ejection position are appropriately adjusted during automatic wire electrode connection. Without positioning, a part of the fluid jet comes into contact with and scatters with the work, and the wire electrode cannot be smoothly guided into the initial hole, so that the probability of automatic connection of the wire electrode is significantly reduced. Further, the same may occur when foreign matter such as processing dust is mixed in the initial hole.

In recent years, it has been desired to realize automation and unmanned machining in order to improve machining efficiency in a wire electric discharge machine. For example, when performing unmanned die-shape multi-punching or punch-shape multi-cavity processing, if the desired processing program is executed without knowing the occurrence of the above-described inconvenience, the initial connection in which the automatic connection of the wire electrode fails. Processing will be temporarily suspended at the hall,
The operator must re-execute the processing after eliminating the defect, which significantly reduces the processing efficiency.

In view of the above, the automatic connection of the wire electrode is actually performed by guiding and inserting the fluid jet in each of the initial holes formed in the work, and is there a possibility that the displacement between the initial hole formation position and the fluid jet ejection position does not occur. ,
Further, the relative movement between the upper head and the lower head for guiding the wire electrode and the work is performed according to a processing program,
There is a machining program confirmation function for confirming a problem that occurs when the machining program is actually executed before actual machining, such as whether the upper head and the lower head are in contact with the work fixture.

In a general machining program confirmation function, a machining program is executed without supplying a machining voltage between the wire electrode and the work, that is, without causing a discharge action between the wire electrode and the work. Like that. Therefore, when the automatic connection of the wire electrode in the initial hole is successful, if the operator temporarily stops the machining program and does not perform the relative movement between the wire electrode and the work, the wire electrode is forcibly torn off. Causes serious damage. Therefore, the wire electrode must be cut manually, and then the wire electrode must be automatically connected in another initial hole, which is very inefficient.

As a first prior art for solving the above problems, there is an automatic connection abnormality detecting method of a wire cut electric discharge machine disclosed in Japanese Patent Application Laid-Open No. 7-204940. This is to make the automatic connection of the wire electrode actually performed in each initial hole at the time of judging the possibility of automatic connection of the wire electrode in the machining program confirmation function, and to automatically cut the wire electrode when the automatic connection is successful. is there. Further, as a second prior art, Japanese Patent Application Laid-Open No. 8-251 is disclosed.
There is a method of detecting the position of a start hole in wire electric discharge machining disclosed in Japanese Patent No. 46-46. This is to determine whether or not the automatic connection of the wire electrodes is possible by detecting the positional deviation between the initial hole formation position and the fluid jet ejection position without actually automatically connecting the wire electrodes at each initial hole. The fluid jet is scanned and moved with respect to the initial hole formed in the work, and the pressure change of the fluid jet is detected from the relationship with the position data of the scanning movement to calculate the formation position of the initial hole. It was done.

[0010]

In the first prior art, when initial holes are formed at a plurality of locations on a work, the operations from the automatic connection of the wire electrode to the automatic cutting are actually performed at each of the initial holes. This must be performed, and it takes a lot of time to determine whether or not the automatic connection of the wire electrodes is possible. In addition, the wire electrodes that are sent out during the automatic connection of the wire electrodes are wasted. Further, in the second conventional technique, a working fluid for supplying a working fluid to a fluid jet forming unit is not detected by detecting a jet pressure of a fluid jet actually ejected toward an initial hole during automatic connection of a wire electrode. The supply pressure near the outlet of the supply pump is detected. The jet pressure of the fluid jet varies due to external factors such as the length of the piping from the machining fluid supply pump to the fluid jet forming part. In this case, the fluid jet required to guide the wire electrode into the initial hole It is not possible to detect whether the ejection pressure is output at the time of automatic connection of the wire electrode.

Therefore, the present invention makes it possible to determine whether or not the automatic connection of the wire electrodes is possible in a state close to the time of the actual automatic connection of the wire electrodes without actually inserting the wire electrodes into the initial holes and performing the automatic connection. It is an object of the present invention to provide a wire electric discharge machine that can be used.

[0012]

In order to achieve the above-mentioned object, the present invention provides, for example, a machining program confirmation function in which a fluid jet ejected toward an initial hole formed in a work at the time of automatic connection of a wire electrode is provided. , The pressure after passing through the initial hole is detected and compared with a threshold value to determine whether or not the automatic connection of the wire electrode is possible. In other words, wire electric discharge machining in which a wire electrode is guided by a fluid jet, inserted into an initial hole formed in a work and automatically connected, and a desired shape is machined on the work while relatively moving the wire electrode and the work. In the machine, an upper head and a lower head for guiding the wire electrode and the work are relatively moved, and a through hole of the wire electrode of the upper head and the lower head is positioned at a position facing the initial hole. A relative moving means, a fluid jet ejecting means for ejecting the fluid jet toward the initial hole through a through hole of the wire electrode of the upper head, and a lower head facing the workpiece and the lower head. The head is provided at a predetermined distance from the position of the through hole of the wire electrode, and passes through the initial hole. A fluid jet pressure detecting means having a pressure detecting unit for detecting the pressure of the fluid jet, and when the pressure of the fluid jet is detected, the upper head and the lower head are relatively moved by the predetermined distance, and A second relative movement means for positioning the ejection part and the pressure detection part of the fluid jet pressure detection means, comparing the detected pressure of the fluid jet with a preset threshold value, and Automatic wire connection determination means for determining whether or not automatic connection to the initial hole is possible.

[0013]

[Function] When performing multiple-punching or multiple-punching processing on one workpiece starting from the initial holes formed at a plurality of locations on the workpiece, the processing program confirmation function is executed before actual processing, and In some cases, it is determined whether or not automatic connection of the wire electrodes in each initial hole is possible. In this case, the upper and lower heads for guiding the wire electrodes and the workpiece are relatively moved by the first relative moving means, and the through-holes of the wire electrodes of the upper and lower heads are positioned at positions facing the initial holes. I do. Next, the upper head and the lower head are relatively moved by the second relative moving means, and are separated from the position of the wire through hole of the lower head by a predetermined distance at a portion facing the ejection part of the fluid jet and the work of the lower head. Positioning with the pressure detecting unit of the fluid jet pressure detecting means provided at the position where the fluid jet pressure is detected. afterwards,
The fluid jet is ejected from the fluid jet ejection means toward the initial hole through the through hole of the upper head wire electrode, and the pressure of the fluid jet after passing through the initial hole is detected by the fluid jet pressure detection means, and the detected fluid is detected. The jet pressure and a preset threshold value are compared by an automatic connection determination unit.

Here, if there is a mistake in creating a machining program or a mistake in the hole position or hole diameter of the initial hole to be formed in the work, the initial hole formation position and the fluid jet ejection position are not properly positioned. Further, even when foreign matter such as processing dust is mixed in the initial hole, a part of the fluid jet comes into contact with and scatters with the workpiece, and the detected pressure of the fluid jet does not reach the threshold value. At this time, it is determined that the probability of successful automatic connection of the wire electrode is low because the ejection pressure of the fluid jet for guiding the wire electrode into the initial hole becomes insufficient due to some trouble. Therefore, it is possible to easily determine whether or not the automatic connection of the wire electrodes is possible before actual processing without actually connecting the wire electrodes automatically.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view and a configuration block diagram of a main part of a wire electric discharge machine according to an embodiment of the present invention.
Is a flowchart showing an example of a machining method in the wire electric discharge machine according to the present invention, FIG. 3 is a schematic diagram showing a wire traveling path of the wire electric discharge machine according to the present invention, FIG.
FIG. 4 is a plan view showing a workpiece at the time of punching a large number of dies.

First, with reference to FIG. 1 and FIG. 3, a main part of a wire electric discharge machine according to the present invention and a wire traveling path will be described. A wire electrode (hereinafter referred to as a wire) 1 is supplied from a wire supply device 3 including a wire bobbin 3a, a back tension motor 3b, and the like. The upper wire guide 11 provided in the upper head 11 after reaching the wire tension generating device 7 through a wire guiding device 9 having a jet nozzle 9a, a cutter 9b, and the like.
a, passes through an initial hole 13a formed in the work 13, is guided by a lower wire guide 15a provided in the lower head 15, changes the running direction via a lower guide roller 17, and takes up a winding roller 19a. , Winding motor 19
b, the wire reaches a wire winding device 19 composed of a pinch roller 19c and the like, and is collected by a wire collecting device (not shown).

When the wire 1 travels, the take-up roller 19a is driven to rotate at a predetermined speed by a take-up motor 19b, and applies a predetermined braking force to the pulley 7a of the wire tension generating device 7 to apply the wire 1 to the wire 1 in accordance with its wire diameter. The desired tension is applied. Further, the wire bobbin 3a of the wire supply device 3 is connected to the wire 1 by the back tension motor 3b.
The pulling force is always applied in the direction opposite to the traveling direction of the wire 1, and the wire 1 does not slack in the leading section from the wire feeder 3 to the wire tension generator 7.

A work 13 placed on a table 21 which moves in the X and Y directions orthogonal to each other in a horizontal plane has eight initial holes 13a to 13h serving as starting points for electric discharge machining as shown in FIG. Is formed. In actual processing
A working fluid is supplied from a working fluid tank (not shown) to the jet nozzle 9a of the wire guiding device 9 by an appropriate pipe,
The wire 1 supplied from the wire supply device 3 and passed through the wire tension generating device 7 is moved to the one of the initial holes 13a to 13h by the fluid jet 23 formed by squeezing the pipeline of the processing liquid by the jet nozzle 9a. The wire is automatically guided so as to be sequentially guided to reach the wire winding device 19. In the wire guiding device 9 provided above the upper head 11, when processing in another initial hole is performed after the completion of processing in an optional initial hole, a wire is connected between the wire supply device 3 and the wire winding device 19. A pair of cutters 9b for automatically cutting the wire 1 is provided.

Normally, the upper wire guide 11a and the lower wire guide 15a have a pair of guide members of a planar guide member and a guide member formed with a V-shaped groove, respectively. The pipes are provided so as to separate from each other to secure the pipeline of the fluid jet 23 and to form a wire through hole for guiding the wire 1 in the vertical direction by abutting a pair of guide members during processing. An appropriate power supply (not shown) is provided in the upper head 11 and the lower head 15, and supplies a pulse voltage for electric discharge machining to the running wire 1. The fluid jet 23 ejected from the jet nozzle 9a of the wire guiding device 9 is provided at a position facing the lower surface of the work 13 of the lower head 15 and at a predetermined distance from the position of the wire hole of the lower head 15. Are the initial holes 13a to 13
A pressure sensor 15b for detecting the pressure after passing through the pressure h is provided.

The moving means 25 includes an upper wire guide 11a in the upper head 11 and a lower wire guide 1 in the lower head 15.
For the wire 1 guided in 5a and traveling in the vertical direction,
An X-axis feed motor for relatively moving the table 21 on which the work 13 is placed in X and Y directions orthogonal to each other in a horizontal plane;
U which moves the upper head 11 relative to the axis feed motor and the lower head 15 in the U and V axis directions parallel to the X and Y axis directions.
It consists of a shaft feed motor and a V-axis feed motor.

The NC / power supply device 27 incorporated in the wire electric discharge machine includes a power supply (not shown) for supplying a machining voltage between the wire 1 and the work 13. Control means 31, automatic connection determination means 3
3 is provided. The program storage means 29 stores and executes an NC program used for machining a desired shape of the workpiece 13 by the wire electric discharge machine, and also controls a pressure of the fluid jet 23 necessary for automatic wire connection according to a wire diameter in the NC program. Is calculated and stored as a threshold value. The control means 31 includes a program storage means 29
The servo output is sent to the moving means 25 composed of each axis feed motor based on the moving command of the NC program stored in the step (1). The automatic connection discriminating means 33 detects the detected value of the pressure of the fluid jet 23 after passing through the initial hole during the automatic wire connection of the wire and the program storage means 29.
Is compared with the threshold value of the pressure of the fluid jet 23 stored in the step (1), and when the detected value does not reach the threshold value, it is determined that the automatic wire connection to the initial hole of the wire 1 cannot be performed.

With the above configuration, in the wire electric discharge machine, the wire 1 to which the desired tension is applied is caused to travel in the vertical direction, and the workpiece 13 placed on the table 21 is moved.
Is moved along a desired path in the X and Y axis directions orthogonal to each other in a horizontal plane, and a machining voltage is supplied between the poles of the wire 1 and the work 13 so that the electric discharge machining of a desired shape is performed on the work 13. is there.

Now, an example of a method for machining a die-shaped workpiece as shown in FIG. 4 based on the configuration of the wire electric discharge machine according to the embodiment of the present invention will be described with reference to the flowchart of FIG. . A processing program for performing processing in the initial hole after automatic wire connection in a certain initial hole, and then performing processing in the initial hole after automatic wire connection again in another initial hole, for example, as shown by a dashed line in FIG. The initial holes 13a to 13h are arranged in the order from the upper left initial hole 13a to the lower right initial hole 13h.
In step h, a machining program for performing each machining is created, and is input and stored in the program storage unit 29 of the NC / power supply device 27 by a known program input unit (not shown) (step S1). Thereafter, the initial holes 13a to 13h are formed in the die-shaped processing portion of the work 13 so as to match the processing program input and stored in the program storage means 29 (step S2).

The machining program inputted and stored in the program storage means 29 includes a command for positioning the upper head 11 and the lower head 15 to the initial hole, and the ejection of the fluid jet 23 toward the initial hole to cause the wire 1 to move.
Wire connection block consisting of an automatic connection command for guiding the wire, a processing condition setting command such as wire diameter and wire tension, a processing voltage supply command between the gap between the wire 1 and the work 13, a pause command, a desired processing shape Wire 1 and work 1 according to
3 and a machining shape program block comprising a relative movement command.

Next, input to the program storage means 29,
By executing the stored machining program, electric discharge machining for the work 1 is started. However, when machining is performed unattended for a long time, such as during nighttime operation, machining is not interrupted, and machining efficiency is improved. It is necessary to confirm before processing. Here, when a machining program confirmation command is sent to the program storage means 29, the machining program is executed while turning off the machining voltage supply command in the machining shape program block of the machining program (step S3).

In accordance with the positioning command of the upper head 11 and the lower head 15 in the wire automatic connection block of the machining program, the work 13 is moved to the upper head 11 and the lower head 15.
Is moved in the X and Y axis directions,
First, the upper head 11 and the lower head 15 are positioned in the upper left initial hole 13a (step S4). This positioned state is the processing start position in the initial hole 13a. However, since the pressure of the fluid jet 23 after passing through the initial hole 13a cannot be detected during automatic wire connection, a so-called taper moving device is used. Then, the upper head 11 is moved in the U and V axis directions with respect to the lower head 15 (if necessary, the work 13 is moved in X and Y directions).
(In the axial direction), and the fluid jet 2 of the jet nozzle 9a of the wire guiding device 9 provided on the upper head 11
3 and the pressure sensor 15 provided on the lower head 15
Positioning is performed with the pressure detecting section b (step S5). Here, a predetermined distance between the wire hole of the lower head 15 and the pressure sensor 15b is stored in advance, and when the upper head 11 and the lower head 15 move to the processing start position, the upper head 11 may be automatically moved by the predetermined distance.

Then, the fluid jet 23 is jetted toward the initial hole 13a at the pressure stored as a threshold value in the machining program storage means 29 (step S6), and the pressure of the fluid jet 23 after passing through the initial hole 13a is reduced. The pressure is detected by the pressure sensor 15b, and the detected value is sent to the automatic connection determination means 33 (step S7).

The automatic connection determination means 33 compares the detected pressure value of the fluid jet 23 detected by the pressure sensor 15b with the stored threshold value of the fluid jet 23 (step S8).
As a result, if the detected value does not reach the threshold value, the formation of the initial hole 13a is caused by a defect such as a mistake in creating a machining program or a mistake in machining of the position or diameter of the initial hole 13a to be machined in the work 1. A part of the fluid jet 23 comes into contact with the work 13 because the position and the ejection position of the fluid jet 23 are not properly positioned, or because foreign matter such as processing dust is mixed in the initial hole 13a. The ejection pressure of the fluid jet 23 that scatters and passes through the initial hole 13a is insufficient,
It is determined that the probability that the wire 1 cannot be guided smoothly and the automatic wire connection is successful will be low.

As described above, it is determined whether or not automatic wire connection is possible by detecting the pressure of the fluid jet 23 in each of the initial holes 13a to 13h formed in the work 13 (step S9). After determining whether or not the automatic wire connection is possible (here, after determining whether or not the automatic wire connection is possible in the lower right initial hole 13h), the machining program input and stored in the program storage means 29 is executed, and the die-shaped hole 3 in the work 13 is formed.
5 is performed (step S10).

If the machining program is not confirmed before the actual machining, it is needless to say that the machining program should be executed immediately after inputting and storing the program in the program storage means 29. For example, the probability of successful automatic wire connection is low. If the position of the initial hole is read by a position detecting device such as a scale provided on the table 21 and stored, the operation from the automatic connection to the processing related to the initial hole is not performed during the actual processing. Can also be skipped, and the processing efficiency can be further improved.

[0031]

As is clear from the above description, the present invention is applicable to a case where a plurality of pieces are punched out or a plurality of pieces are cut from one work starting from each of the initial holes formed at a plurality of places of the work. In the case where a machining program confirmation function is executed before actual machining, a wire jet is detected by detecting whether a fluid jet ejected toward an initial hole formed in a workpiece reaches a predetermined pressure after passing through the initial hole. This is to determine whether or not automatic connection of the electrodes is possible. Therefore, it is possible to easily determine whether or not the automatic connection of the wire electrodes is possible in a state close to the time of the actual automatic connection of the wire electrodes without actually automatically connecting the wire electrodes before the actual processing. Also, since the wire electrodes are not actually automatically connected, the time from the automatic connection of the wire electrodes to the automatic cutting can be omitted, and the amount of the wire electrodes sent during the automatic connection of the wire electrodes is wasted. Not even.

[0032]

[Brief description of the drawings]

FIG. 1 is a sectional view and a configuration block diagram of a main part of a wire electric discharge machine according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an example of a machining method in the wire electric discharge machine according to the present invention.

FIG. 3 is a schematic diagram illustrating a wire traveling path of the wire electric discharge machine according to the present invention.

FIG. 4 is a plan view showing a workpiece at the time of punching a large number of dies.

[Explanation of symbols]

 Reference Signs List 1 wire 9 wire guiding device 9a jet nozzle 11 upper head 11a upper wire guide 13 work 13a to 13h initial hole 15 lower head 15a lower wire guide 15b pressure sensor 21 table 23 fluid jet 25 moving means 27 NC / power supply device 29 program storage means 31 control means 33 automatic connection determination means

Claims (1)

[Claims] 1. A wire electrode is guided by a fluid jet, inserted into an initial hole formed in a work, automatically connected, and processed into a desired shape on the work while relatively moving the wire electrode and the work. In a wire electric discharge machine, an upper head and a lower head for guiding the wire electrode and the work are relatively moved, and a through hole of the wire electrode of the upper head and the lower head is positioned at a position facing the initial hole. A first relative moving unit, a fluid jet ejecting unit that ejects the fluid jet toward the initial hole through a through hole of the wire electrode of the upper head, and a facing portion of the lower head facing the workpiece. The lower head is provided at a position separated by a predetermined distance from the position of the through hole of the wire electrode, and the initial hole is A fluid jet pressure detecting means having a pressure detecting unit for detecting a pressure of the fluid jet after passing; and, when detecting the pressure of the fluid jet, relatively moving the upper head and the lower head by the predetermined distance, A second relative moving means for positioning the jet ejection part of the jet and the pressure detection part of the fluid jet pressure detection means, comparing the detected pressure of the fluid jet with a preset threshold value, An automatic connection determination means for determining whether or not automatic connection of a wire electrode to the initial hole is possible.