JPS63180423A - Method of boring prepared hole for wire cut electric discharge machining - Google Patents

Abstract

PURPOSE:To prevent production of burrs on the periphery of a prepared hole and to enable machining of the prepared hole, having a smooth surface, by performing excellent electric discharge, by a method wherein energy of a discharge pulse is increased with the progress of machining by using a low energy discharge pulse during the starting of machining. CONSTITUTION:When a prepared hole for a wire electrode is machined, a machining solution is injected and fed through the interior of a fine tube electrode 1 to a machining gap. Simultaneously, a discharge pulse is applied on a machining gap by a source circuit 2 according to a predetermined program. Namely, during the starting of machining, a voltage pulse having a pulse duration number mus is fed at a low voltage of approximate 40V, and pulse duration is gradually increased together with an applied voltage with the progress of machining. This method prevents burrs, produced due to hardening of the splash of a molten metal to a workpiece, from being produced on the peripheral edge of a prepared hole, and forms a prepared hole 6, having a smooth machined surface, in a manner to be extended through the workpiece.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for drilling a pilot hole for wire-cut electrical discharge machining.

[Conventional technology]

Ordinary wire-cut electrical discharge machining equipment, which performs electrical discharge machining on a workpiece using a wire electrode of about 0.2Dφ stretched in a straight line, is widely used for machining through-type dies, etc. In wire cut electrical discharge machining equipment,
In order to insert the wire electrode, it is necessary to prepare a hole in the workpiece using a thin tube electrode to insert the wire electrode.

However, in the usual method of drilling a pilot hole for wire-cut electrical discharge machining, a wire-cut electrical discharge machining machine or an electrical discharge machine different from the wire-cut electrical discharge machining machine, preferably using a water-based machining fluid, is used. While supplying machining liquid between the thin tube electrode and the workpiece using a hole-dedicated machining machine, for example, approximately 80
A voltage pulse with a constant voltage of V is applied, and a discharge having a selected predetermined discharge pulse width and discharge current amplitude is performed after a predetermined pause time to perform pilot hole machining. There was a problem in that burrs were formed around the periphery of the pilot hole that was drilled into the body. This occurrence of sparks also occurs when the drilled pilot hole exits, and is also a problem.

For this reason, when inserting a wire electrode into the pilot hole for wire electrode insertion, since the wire diameter of the wire electrode is extremely thin at approximately 0.2++ m, the tip of the wire will hit the edge and bend, making it difficult to insert the wire electrode into the pilot hole. I had something to say.

[Problem that the invention seeks to solve]

The present invention has been made based on the above-mentioned viewpoints, and
The purpose is to provide a method for drilling a pilot hole for wire-cut electric discharge machining, which can prevent splashes of molten metal from solidifying and causing cracks when drilling a pilot hole for inserting a wire electrode. It is in.

[Means for solving problems]

The above object is, in the method for drilling a pilot hole for wire-cut electrical discharge machining, to use a low-energy discharge at the beginning of machining, more preferably at the time of piercing the pilot hole at the end of machining, so as to avoid splashing of molten metal. This is achieved by a method for drilling a pilot hole for wire-cut electrical discharge machining, which uses a pulse and increases the energy of the discharge pulse as machining progresses.

[For production]

By configuring as described above, a low-energy discharge pulse is used at the start of machining a pilot hole for inserting a wire electrode, and the energy of the discharge pulse is gradually increased as the machining progresses. More preferably, it is possible to produce a smooth surface of the pilot hole by performing good electrical discharge without causing any cracks on the other exit periphery of the pilot hole.

〔Example〕

Hereinafter, details of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of an apparatus for carrying out the method of drilling a pilot hole for wire cut electric discharge machining according to the present invention, and FIG.
FIG. 3, which is a partially enlarged sectional view of a prepared hole for inserting a wire electrode in a workpiece that has been prepared using a conventional method, is a time chart of voltage pulses supplied from the power supply circuit in FIG. 1.

In FIG. 1, 1 is a thin tube electrode, 2 is a power supply circuit, 3 is a processing liquid tank, 4 is a pump, 5 is a workpiece, and 6 is a prepared hole for inserting a wire electrode.

The thin tube electrode 1 is installed in a machining head (not shown) of a wire-cut electric discharge machining device, and has a desired shape that matches the prepared hole 6 to be machined in order to insert the wire electrode into the workpiece 5. A copper or copper alloy pipe electrode or the like is used, and a machining fluid supplied from a machining fluid tank 3 by a pump 4 is passed through the pipe.

The power supply circuit 2 connects the capillary electrode 1 via a switching element or the like (not shown) according to a predetermined program.
The structure is such that a voltage pulse is supplied between the workpiece 5 and the workpiece 5 .

The program that controls the power supply circuit 2 is, for example, a board with a thickness of 60 nm.
+ S K D 1) When drilling a pilot hole in a material with a 0.8 mφ Cu vibrating electrode, a voltage pulse with a pulse width ps at a low voltage of about 40 V is applied at the start of processing as shown in Figure 3. As the machining progresses, the applied voltage and pulse width are sequentially increased to perform electrical discharge machining, and when the workpiece 5 has been machined to a depth of about 21, the voltage is about 80 V.
It is designed to supply a discharge pulse with an applied voltage of .

On the other hand, it is recommended that the machining fluid supplied from the machining fluid tank 3 to the machining gap via the pump 4 is configured so that the fluid pressure is increased sequentially from the start of machining and supplied and injected in accordance with the increase in the discharge energy. be done.

Therefore, when machining the pilot hole of the wire electrode, the thin tube electrode 1
The machining fluid is supplied and injected into the machining gap through the inside of the pipe.
, a discharge pulse is applied to the machining gap from the power supply circuit 2 according to the predetermined program to perform a good discharge, and thereby, when machining starts, the second
Unlike the conventional method shown in the figure, it is possible to prevent the generation of burr 22 on the periphery of the pilot hole 23 on the workpiece 21 due to the solidification of splashes of molten metal, and to form the pilot hole 6 with a clean machined surface through it. This is something that will happen.

Also, although not shown in the drawings, a gap is also formed around the exit point where the pilot hole sill passes through, so when processing the exit edge, it is necessary to From a predetermined time before the end of the predetermined drilling process, the passage of time in FIG. It is preferable to perform control to reduce one or more of the amplitudes so that the energy of the electric discharge machining is controlled to be small at the end of the withdrawal machining, and the machining is completed.

〔Effect of the invention〕

Since the present invention is constructed like a ridge, in accordance with the present invention, a low-energy discharge pulse is used at the start of machining a pilot hole for inserting a wire electrode, and the energy of the discharge pulse is gradually increased as the machining progresses. For wire-cut electric discharge machining, the wire electrode can be inserted easily and accurately because it can produce a smooth surface of the pilot hole by producing good electrical discharge without causing any cracks on the periphery of the pilot hole. A method for drilling a pilot hole can be provided.

Note that the configuration of the present invention is not limited to the embodiment on the ridge; for example, a low voltage is used as the discharge energy from the power supply circuit 2 at the start of machining, and the applied voltage is increased as the machining progresses. However, it may be configured to start machining by shortening the discharge pulse time τon, and the power supply circuit 2 may be of any other type as long as the object of the present invention is achieved.
The present invention encompasses all modifications that can be easily figured out by those skilled in the art from the foregoing description within the scope of its purpose.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of an apparatus for carrying out the method of drilling a pilot hole for wire cut electric discharge machining according to the present invention, and FIG.
FIG. 3, which is a partially enlarged sectional view of a prepared hole for inserting a wire electrode in a workpiece that has been prepared using a conventional method, is a time chart of voltage pulses supplied from the power supply circuit in FIG. 1.

Claims (2)

[Claims] (1) In a method of machining a pilot hole in a workpiece using a thin tube electrode using a wire-cut electric discharge machining device, a low-energy discharge pulse is used at the start of machining, and the energy of the discharge pulse is adjusted as the machining progresses. A method for drilling a pilot hole for wire cut electrical discharge machining, characterized by increasing the (2) The method for drilling a pilot hole for wire-cut electrical discharge machining according to claim 1, characterized in that the energy of the discharge pulse is sequentially reduced when the pilot hole is completed.