JPH02106227A - Small hole electrical discharge machining method using wire electrical discharge machine - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to start hole machining for wire electrical discharge machining of workpieces such as cemented carbide and hardened steel, difficult-to-process materials such as copper and stainless steel, and curved surfaces. The present invention relates to a small hole electrical discharge machining method using a wire electrical discharge machine that can perform small hole machining on a workpiece having a tapered surface.

[Conventional technology]

Conventionally, for example, wire electrical discharge machines machine workpieces made of cemented carbide, hardened steel, etc. using the part where the wire electrode runs, but For this purpose, a start hole is required, and a small hole electric discharge machine or a wire electric discharge machine with a start hole machining device is provided as a device for machining the start hole.

In addition, the small-hole electric discharge machine is used to machine small holes in difficult-to-process materials such as copper and stainless steel, and in workpieces having curved surfaces and tapered surfaces. For such a small hole electric discharge machine or start hole machining device, a pipe electrode holding device is attached to the tip of the rotating ball shaft, and a pipe electrode of φ0.3 to φ3 is usually held in the pipe electrode holding device. High-pressure water (usually 30 kg/cd to 100 kg/aJ) sent through a rotary joint or the like is passed through the pipe of the pipe electrode and ejected from the tip of the pipe to create a connection between the pipe electrode and the workpiece. Pore formation is the process of creating small pores in a workpiece by electrical discharge.

Conventionally, a guide holder device for a pipe electrode attached to a small-hole electric discharge machine or a wire electric discharge machine with a start hole machining device is constructed as shown in FIGS. 4 and 5. That is, the guide holder device 52 connects a pair of slide rods 54 that are vertically movably attached to the head 62 of a small-hole electric discharge machine or a wire electric discharge machine with a start hole machining device, and the ends of the slide rods 54. It consists of a connecting plate 55 and a guide holder 61 attached to the slide rod 54.

A holder portion 57 is fixed to the head 62, and the holder portion 5
A chuck portion 58 is removably attached to 7.

A pipe electrode 53 for performing electric discharge machining on the workpiece 56 is attached to the chuck portion 58 .

A through hole is formed in the center of the guide holder 61, and the pipe of the pipe electrode 53 passes through the through hole so that the pipe electrode 53 is guided. The slide rod 54 is
The head 62 can be moved up and down manually or electrically. When performing electric discharge machining of a small hole or hole in the workpiece 56 using a small hole electric discharge machine, or a fine hole using a start hole machining device, the workpiece 56 is placed on the table 60.
Fixed by clamp 59 on top, ° slide rod 5
4 is lowered, and the guide holder 61 attached to the lower end of the slide rod 54 is set close to the workpiece 56.

Therefore, the guide holder 61 can guide the tip of the pipe electrode 53, prevent the pipe electrode 53 from wobbling, shaking, etc., and can be accurately set at a predetermined position.

[Problem to be solved by the invention]

However, in the conventional wire electrical discharge machine equipped with a start hole machining device, as mentioned above, a special mechanism for electrical discharge machining of small holes is used to electrical discharge machine the small holes such as the start hole. For example, in addition to the wire electrical discharge machine, a mechanism such as the one described above may be used, and a guide holder 6 attached to a connecting plate 55 connected to the lower ends of a pair of slide rods 54 may be used to guide the lower end of the pipe electrode 53.
In order to guide the pipe electrode 53 with precision, a mechanism for arranging the guide holder 61 close to the workpiece 56 is required, which makes the structure of the wire electric discharge machine complicated and expensive. Become.

In addition, if a start hole machining device is not attached to a wire electrical discharge machine, a separate device such as a small hole electrical discharge machine or a small hole processing machine is required to machine a small hole such as a start hole in the workpiece. Therefore, mounting and dismounting the workpiece requires complicated work, and the mechanism of the device itself becomes complicated. Furthermore, after machining a start hole in a workpiece with a start hole machining device, in order to perform wire electric discharge machining on the workpiece, the workpiece must be removed and installed in a wire electric discharge machine, and the wire electrode This causes poor positioning of the start hole.

Therefore, when electrical discharge machining a start hole on a workpiece, a wire electrical discharge machine is used as an extension of wire electrical discharge machining, without using a dedicated small hole electrical discharge machine or start hole machining equipment. There was a problem of whether or not electrical discharge machining could be performed without causing poor positioning of the start hole relative to the wire electrode.

The purpose of this invention is to solve the above problems,
When machining a small hole such as a start hole using a wire electrical discharge machine, a wire electrode is supplied using a wire electrode supply pipe such as an automatic wire supply device without using a pipe electrode, and the wire is Directly electrical discharge machining of a small hole such as a start hole in a workpiece using the tip of the electrode, and following machining of the start hole, the wire electrode is directly passed through the start hole to perform wire electrical discharge machining on the workpiece. An object of the present invention is to provide a method for electrical discharge machining of a small hole using a wire electrical discharge machine.

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. That is, in this invention, a holder to which a supply pipe is fixed is lowered along a guide rod fixed to a head, the lower end surface of the supply pipe is opposed to the workpiece at a predetermined distance, and the workpiece is sent out from the source bobbin. supplying the wire electrode in a state where the wire electrode passes through the supply pipe and protrudes from the lower end surface of the supply pipe, and then applying an inter-electrode voltage between the wire electrode at the protruding portion and the workpiece; A small hole by a wire electric discharge machine, characterized in that a small hole such as a start hole is machined in the workpiece by electrical discharge, and the wire electrode is fed in accordance with the progress of the small hole machining. Related to electric discharge machining method.

Further, in this small hole electric discharge machining method, the degree of wear of the discharge portion of the wire electrode is detected, and when the degree of wear is greater than a predetermined value, the tip of the wire electrode is cut and removed. The lower end of the supply pipe is raised above the cutter attached to the head along the guide rod to cut and remove the lower end of the wire electrode, and then the holder is lowered to remove the workpiece. It consists of wire electrical discharge machining.

Further, in the present invention, after machining a start hole in the workpiece with the wire electrode, the wire electrode is subsequently run through the start hole, and there is a gap between the wire electrode and the workpiece. Apply voltage to discharge,
The present invention is characterized in that the workpiece is electrically discharge-machined into a predetermined shape using the electrical discharge energy.

[Effect]

The small hole electric discharge machining method using a wire electric discharge machine according to the present invention is configured as described above, and operates as follows. That is, in the present invention, a wire electrode is passed through the supply pipe and protrudes from the lower end surface of the supply pipe using a supply pipe along a guide rod fixed to a head;
An inter-electrode voltage was applied between the wire electrode and the workpiece to cause a discharge, and the discharge energy was used to discharge a small hole such as a start hole into the workpiece, so that the wire electrode itself used for wire discharge machining It is possible to perform electric discharge machining of small holes such as start holes, and after machining the start hole, wire electric discharge machining can be performed immediately without reinstalling the workpiece. In addition, when the wire electrode is worn out, the holder is moved along the guide rod to raise the lower end of the supply pipe above the wire electrode cutting means, and the lower end of the wire electrode is removed. If it is cut and removed, start hole machining can be performed again in the same manner, and start ball machining and wire electric discharge machining of a predetermined machining shape can be achieved by automation.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a wire electrical discharge machine that achieves a small hole electrical discharge machining method according to the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing a wire electrical discharge machine capable of achieving the small hole electrical discharge machining method according to the present invention.

FIG. 2 is a schematic front view showing a state in which the wire electric discharge machine shown in FIG. 1 performs start hole machining.

This wire electrical discharge machine is capable of, for example, performing wire electrical discharge machining on a workpiece 8 into a predetermined machining shape using the wire electrode 1, and electrical discharge machining of a small starting hole or the like through which the wire, which is the wire electrode 1, penetrates. The head 10 constituting the wire electrical discharge machine is equipped with an automatic wire feeding device. The workpiece 8 is also clamped 22 on a worktable 21 mounted on a cross slide operated in servo function by a servomotor.
Fixed by At the top of the head 10 of the wire electrical discharge machine, there is a supporting body 9 constituting an automatic wire feeding device.
Further, a support body 23 to which the upper wire head 6 is attached, and a support body 24 to which rollers 18 and the like for guiding the supply pipe 5 and the wire electrode 1 are attached are fixed to the lower part of the head 10. A pair of guide rods 3 are arranged between the support body 9 and the support body 24.

A holder 20 is attached to these guide rods 3 so as to be slidable in the vertical direction. A supply pipe 5 that guides the wire electrode 1 is fixed to the holder 20 with a set screw 25 or the like, and a thread guide 12, a pair of annealing rollers 4 having the function of a power supply bottle, and a pipe holder 13 are also attached to the holder 20. ing. The pair of annealing rollers 4 are
It has the function of pinching the wire electrode l fed through the thread guide 12 attached to the holder 20 and feeding it into the supply pipe 5. A direction conversion roller 7 and a felt brake roller 11 are attached to the support body 9,
The wire electrode 1 is configured to be fed into the supply pipe 5 with a predetermined tensidin applied thereto. In addition, a slide rail 14 is provided on the support body 24 attached to the head 10 in order to make the sliding movement of the supply pipe 5 smooth.
is fixed. In the support body 24, a cutter 16 is installed below and adjacent to the slide rail 14.

This cutter 16 is provided to cut the wire electrode 1 in order to prepare a good wire electrode end. That is, the cutter 16 normally inserts the tip of the wire electrode 1 into a start hole and performs wire electrical discharge machining to form a predetermined machining shape on the workpiece 8, then cuts the wire electrode 1, and then cuts the wire electrode 1. This cutter 16 has the function of allowing the tip to be newly inserted into another start hole or the start hole of another workpiece, but in addition to this function, this cutter 16 also performs small hole electric discharge machining. In case, wire electrode 1
For cutting and removing the end worn out by small hole electric discharge machining, or cutting and removing the tip of the wire electrode 1 when the tip is bent or otherwise unfavorable for wire electric discharge machining. It also has functions.

At the support 24 fixed to the head 10, the cutter 16
A pair of common rollers 15, rollers 18, etc., which guide the power supply pin 17 and the wire electrode 1, are arranged below. In addition, the head 1 is close to the lower surface of the support 24 and
A roller 1B for guiding the wire electrode 1 and a tip end of the supply pipe 5 come into contact with the support body 23 fixed at 0 to prevent the supply pipe 5 from descending further downward and protruding. A pipe stopper 19 and a lower wire head 6 are attached. Although the upper wire head 6 is not shown in detail, it incorporates a die guide, a jet nozzle, a feeder, a feeder presser, etc., as in the prior art.

The wire electrical discharge machine that achieves the small hole electrical discharge machining method according to the present invention is constructed as described above and operates as follows. That is, the wire electrode 1 is wound onto a source bobbin, and the source bobbin is loaded into a wire electrical discharge machine and fed out from the source bobbin by an automatic wire feeding device.

Typically, automatic wire feeding equipment uses various rollers, e.g.
direction change roller, tension roller, brake roller,
It has a wire running system consisting of a wire electrode disconnection sensor and the like, and through this wire running system, the wire is fed into the electrical discharge machining area formed between the wire electrode 1 and the workpiece 8. In the figure, the direction changing roller 2 located downstream of the tension roller of the wire running system is shown, and the wire electrode l
is fed from the direction changing roller 2 to the upper wire head 6 through the direction changing roller 7, felt brake roller 11, thread guide 12, annealing roller 4, supply pipe 5, common roller I5 and guide roller 18. , and finally supplied to the electrical discharge machining site with the workpiece 8.

FIG. 1 shows a wire electrical discharge machine in which the holder 20 is moved upward along the guide rod 3 and the supply pipe 5 is
When the lower end is positioned above the cutter 16 attached to the support body 24, it can be used for normal wire electrical discharge machining, that is, wire electrical discharge machining of a predetermined machining shape on a workpiece, or The case where the wire electrode is cut after wire electric discharge machining or the case where the tip of the wire electrode 1 is cut and removed when performing small hole electric discharge machining are shown. Also,
FIG. 2 shows a wire electrical discharge machine in which the holder 20 is moved downward along the guide rod 3 and the supply pipe 5 is
When the lower end of the pipe stopper 19 is placed on the top surface of the pipe stopper 19 attached to the support body 24, it can be used when machining a small hole such as a start hole on the workpiece 8, or when machining a predetermined machining on the workpiece. When performing wire electrical discharge machining on a shape, pass the wire electrode l through the start hole of the workpiece 8.
The case of setting is shown.

Next, an example of the small hole electrical discharge machining method according to the present invention is explained with reference to FIGS. 1 and 2 showing a wire electrical discharge machine, and the flowcharts in FIGS. 3(A) and 3(B) showing the operation. and explain.

First, in order to machine a start hole in the workpiece 8 using a wire electrical discharge machine, the workpiece 8 is set on the work table 21, the main switch, motor, servo motor, etc. of the wire electrical discharge machine are turned on, and the wire is automatically fed. Activate the device (step 30).

By the operation of the automatic wire feeding device, the wire electrode l is passed from the source bobbin through various rollers such as a tension roller and a direction change roller to a direction change roller 2.7, a felt brake roller 11. The wire electrode 1 is fed into the supply pipe 5 through the thread guide 12 and the annealing roller 4 sequentially, and set so that the tip of the wire electrode l is exposed and protrudes from the lower end of the supply pipe 5 (steps 31 and 32).

At the same time as the wire electrode 1 is supplied to the supply pipe 5, the holder 20 is lowered along the guide rod 3, and the holder 20
The lower end of the supply pipe 5 fixed to the pipe stopper 19
The lowering operation continues until it comes into contact with (step 33).

According to the above process, the position of the work table 21 on the cross slide is adjusted by operating the servo motor feed mechanism, and electrical discharge machining of a small hole such as a start hole is performed on the workpiece 8 fixed to the work table 21. The wire electrode 1 is sent out so that the wire electrode 1 is positioned above and facing the area to be treated (step 34).

A position sensor detects and judges whether or not the lowering position of the wire electrode 1 and the position setting of the workpiece 8 have been completed, and when the position setting is completed, a small hole such as a start hole is made in the workpiece 8. In order to perform electrical discharge machining, the machining fluid supply device is activated to eject machining fluid from the jet nozzle, and if the position setting has not been completed, the positioning of the wire electrode 1 and the workpiece 8 is continued (step 35). .

An inter-electrode voltage is applied between the workpiece 8 and the wire electrode 1, a discharge is caused between the workpiece 8 and the wire electrode 1, and the discharge energy is used to perform electrical discharge machining of a small hole such as a starting ball in the workpiece 8. . In this case, the wire supply device is operated to feed the wire TIPj according to the progress of the small hole drilling on the workpiece 8.
control the feeding of l (step 36).

During small hole electrical discharge machining using the wire electrode l on the workpiece 8, a voltage between the workpiece 8 and the wire electrode l is applied, and the voltage value V of the machining voltage generated according to the voltage between the machining electrodes is It is detected as appropriate and it is determined whether or not the voltage value (2) is greater than or equal to a predetermined voltage value v0. If the machining voltage value ■ is equal to or higher than the predetermined voltage (IV o), the wire electrode 1 is not worn out and is in a normal state, and the machine is in a state where it is possible to perform small-hole electrical discharge machining with a pull Vt. In order to continue performing the small hole electric discharge machining on the object 8, the process proceeds to step 38.If the machining voltage value V is less than the predetermined voltage value ■, the wire electrode 1 is in an abnormal state and is worn out. The process proceeds to step 47 in order to cut and remove the tip of the wire electrode 1 and expose the normal tip of the wire electrode 1 from the supply pipe 5. In this case,
Although the machining voltage has been detected, it is of course possible to configure the system to detect the machining current (step 37).

If the wire electrode 1 is in a normal state and has not yet been consumed, in order to continue small hole electrical discharge machining, a voltage between the electrodes is continuously applied between the workpiece 8 and the wire electrode 1, and the electrical discharge is repeated. The start hole machining continues on the workpiece 8 (step 38).

A sensor or the like detects and determines whether or not the predetermined small hole machining on the workpiece 8 has been completed. When the small hole machining is completed, the small hole electric discharge machining by the wire electric discharge machine ends. is step 4
Proceed to 0, or if the small hole machining is not completed,
The small hole machining continues (step 39).

When the start hole machining for the workpiece 8 is completed, the application of the interelectrode voltage between the wire electrode 1 and the workpiece 8 is stopped, and the discharge is interrupted (step 40).

Next, the automatic wire feeding device is activated to run and feed the wire electrode 1, to pass the wire electrode 1 into the starting hole of the workpiece 8 which has been subjected to small hole electrical discharge machining, and to insert the wire electrode 1 into the wire drawer provided downstream. The wire electrode 1 is set by being clamped by the device and brought into a running state (steps 41 and 42).

Move the holding body 20 upward along the guide rod 7do 3,
It is raised to the position shown in FIG. 1 (step 43).

By raising the holder 20, the wire electric discharge machine is set to a state in which wire electric discharge machining can be performed on the workpiece 8.

Therefore, as in normal electric discharge machining, a voltage between the electrodes 1 and the workpiece 8 is applied to generate an electric discharge, and the electric discharge energy generated by the electric discharge is used to perform electric discharge machining to form a predetermined machining shape on the workpiece 8. (step 44).

It is detected and judged whether electric discharge machining of a predetermined machining shape has been completed on the workpiece 8, and if the predetermined machining shape has not been subjected to electric discharge machining on the workpiece 8, a normal wire electric discharge machining method is performed. Electric discharge machining continues (step 45).

When the electric discharge machining of the predetermined machining shape is completed on the workpiece 8, the operation of the wire electric discharge machine is stopped and the workpiece 8 is
The above-mentioned steps are repeated in order to perform electrical discharge machining of the next start hole.

If there is no need to perform electrical discharge machining on the workpiece 8 attached to the work table 21, replace it with another workpiece 8 and process it according to each step in the same manner as above (step 46).

By the way, in step 37, if the machining voltage value V is equal to or lower than the predetermined voltage 4aVo, it is determined that the wire electrode 1 is in an abnormal state and the tip of the wire electrode 1 is worn out. Since the small hole electric discharge machining of the start hole cannot be continued, the application of the voltage between the wire T141m1 and the workpiece 8 is stopped, and the electric discharge machining is interrupted (
Step 47).

The holder 20 fixing the supply pipe 5 is raised along the guide rod 3, and the lower end of the supply pipe 5 is positioned above the cut 116 attached to the support 24 fixed to the head IO (step 4B). ).

The lower end of the supply pipe 5 is located above the cutter 16,
A sensor such as a rim switch is used to detect and determine whether or not it is set at a predetermined position.

If the lower end of the supply pipe 5 is set above the cutter 16, the upward movement of the holder 20 is stopped, and the process proceeds to the next step 50. If the lower end of the supply pipe 5 is not set at the predetermined position, Subsequently, the lifting operation of the holding body 20 is continued (step 49).

When the lower end of the supply pipe 5 is located above the cutter 16, the cutter 16 is activated to cut off the worn out portion of the wire electrode 1, that is, the tip of the wire electrode 1, and the separated wire electrode 1 by appropriate means. By eliminating the consumable part of the wire electrode 1, the tip of the wire electrode 1 becomes a good wire electrode part again.Next, in order to expose the normal tip of the wire electrode 1 from the supply pipe 5, the processing is carried out. The process proceeds to step 31, and subsequently, processing for small hole electrical discharge machining of a small hole such as a start hole in the workpiece 8 using the wire electrode l is performed according to each of the steps described above (steps 50 and 51).

〔Effect of the invention〕

The small hole electric discharge machining method using a wire electric discharge machine according to the present invention is configured as described above, and has the following effects. That is, in this invention, a holder to which a supply pipe is fixed is lowered along a guide rod fixed to a head,
The lower end surface of the supply pipe is opposed to the workpiece at a predetermined distance, and the wire electrode sent from the source bobbin is passed through the supply pipe and the wire electrode is supplied so as to protrude from the lower end surface of the supply pipe. Then, an inter-electrode voltage is applied between the wire electrode at the protruding portion and the workpiece to cause a discharge, and the discharge energy is used to perform electrical discharge machining of a small hole such as a start hole in the workpiece. Since the wire electrode is fed according to the progress of the wire, the wire electrode itself can be used to perform electrical discharge machining of a small hole such as a start hole, and after machining the start hole, the workpiece cannot be reinstalled. The wire electric discharge machining can be performed on the workpiece in a predetermined shape immediately after the workpiece is mounted as it is without having to do any additional work, and there is no problem with positioning the start hole or the like.

Furthermore, since the electrical discharge machining of a small hole is performed using the wire electrode, for example, a special pipe electrode used in conventional small hole processing becomes unnecessary, and the mechanism of the wire electrical discharge machine can be simplified. Further, when machining a small hole in a workpiece, there is no need to prepare a separate small hole electric discharge machine, a small hole processing machine, etc. Furthermore, since the small-hole electrical discharge machining of the start hole and the wire electrical discharge machining of a predetermined machining shape can be performed on the workpiece using the same wire electrical discharge machine, there is no need to change the setup of the workpiece.

Further, detecting the degree of wear of the discharge part of the wire electrode,
When the degree of wear exceeds a predetermined level, in order to cut and remove the tip of the wire electrode, the holder is raised along the guide rod to the lower end of the supply pipe above the cutter attached to the head. The lower end of the wire electrode is cut and removed, and then the holder is lowered to perform wire electrical discharge machining on the workpiece. When the wire electrode is worn out, the holder is moved along the guide rod. If the lower end of the supply pipe is raised above the wire electrode cutting means and the lower end of the wire electrode is cut and removed, electrical discharge machining of a small hole such as a start hole can be performed again in the same manner. Therefore, start hole machining and wire electric discharge machining of a predetermined machining shape can be easily accomplished by automation.

Further, in the present invention, after machining a start hole in the workpiece with the wire electrode, the wire electrode is subsequently run through the start hole, and there is a gap between the wire electrode and the workpiece. Apply voltage to discharge,
Since the predetermined machining shape is electrically discharged into the workpiece using yield discharge energy, it is possible to smoothly transition from the small-hole electrical discharge machining process of the start hole on the workpiece to the wire electrical discharge machining process with the predetermined machining shape on the workpiece. can.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of a wire electrical discharge machine that achieves the small hole electrical discharge machining method according to the present invention, and FIG.
Schematic front view showing the small hole electrical discharge machining process in Figure 3 (A)
and FIG. 3(B) is a flowchart showing an example of the operation for achieving the small hole electrical discharge machining method according to the present invention.
The figure is a schematic diagram showing an example of a pipe electrode guide holder device in a conventional small-hole electric discharge machine or start hole machining device, and FIG. 5 is a side view of FIG. 4. l--1-wire electric scraper, 3--guide rod, 5-supply pipe, 6--upper wire head, 8-curved ball crop, 9--automatic wire feeder main body, 10- - Song head, 16--cutting device, 20--holding body.

Claims (3)

[Claims] (1) Lower the holder to which the supply pipe is fixed along the guide rod fixed to the head, so that the lower end of the supply pipe faces the workpiece at a predetermined distance, and the wire electrode to be sent out from the source bobbin is supplying the wire electrode in a state that penetrates the supply pipe and protrudes from the lower end surface of the supply pipe, and then applying an inter-electrode voltage between the wire electrode at the protruding portion and the workpiece to cause a discharge; A small hole electrical discharge machining method using a wire electrical discharge machine, characterized in that the electric discharge energy is used to electrical discharge machine a small hole such as a start hole in the workpiece, and the wire electrode is fed in accordance with the progress of the small hole machining. . (2) detecting the degree of wear of the discharge portion of the wire electrode;
When the degree of wear exceeds a predetermined level, in order to cut and remove the tip of the wire electrode, the holder is raised along the guide rod to the lower end of the supply pipe above the cutter attached to the head. 2. The wire electrical discharge machine according to claim 1, further comprising the steps of: cutting and removing the lower end of the wire electrode; and then lowering the holder to perform wire electrical discharge machining on the workpiece. Small hole electrical discharge machining method. (3) After machining a start hole in the workpiece with the wire electrode, the wire electrode is subsequently run through the start hole, and a voltage between the electrodes is applied between the wire electrode and the workpiece. 2. The method for electrical discharge machining of a small hole using a wire electrical discharge machine according to claim 1, wherein the discharge energy is used to discharge a predetermined shape on the workpiece.