JPS6146249B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in electrical processing equipment using wire electrodes.

In the wire cutter, a wire electrode is pulled and wound from one reel to the other, and this moving wire faces the workpiece at a nearly right angle to form a machining gap, and this gap is filled with water, oil, etc. Machining is performed mainly by electrical discharge machining by supplying machining fluid and repeating pulse discharge by applying voltage pulses. Machining is performed by applying a required shape machining feed in the X and Y directions perpendicular to the wire gap direction Z between the wire electrode and the workpiece. By the way, the wire used is a thin wire with a wire diameter of about 0.05 to 0.5 mmφ, and since it is processed under sufficient tension, even a slight arc or short circuit will cause it to melt as it moves through the workpiece. It gets cut off due to etc.

In order to solve these problems, the present invention includes a vibration device that applies vibration to the wire electrode by vibrating a guide, and a cooling device that cools the vibration device. be.

Since the machining gap in a wire cut is minute, short circuits are likely to occur during machining, and if machining debris is not smoothly removed from the gap, short circuits may occur through the machining debris, or abnormal electrical discharges such as arcs may occur. However, by installing a vibrating device to generate vibrations in the wire between the guides, machining debris can be removed smoothly, arcing and short circuits can be reduced, and Even if a short circuit or the like occurs, it can be quickly resolved mechanically, making it possible to continue stable machining of scraps.

Also, by applying continuous vibration during processing, the vibration device itself and the vibration-acting parts are heated.
The present invention is equipped with a cooling device to cool this down, so it will not overheat, and overheating will not change the vibration generation state of the vibration device, reduce the accuracy of mechanical devices such as wire guides, or cause the wire to stretch and cause the wire diameter to change. This has been improved so that stable processing can be performed by stable vibration without becoming thin, not being subjected to a predetermined tension or vibration, or breaking.

The present invention will be explained below with reference to one example.

A wire electrode 1 is sent out from a drum 2 and wound around another arc 3. Reference numerals 4 and 5 denote guides that guide the axial movement of the wire electrode 1 in the processing section facing the workpiece 6, and the wire 1 is moved between these guides by a brake device, tension drive device, etc. (not shown). It moves in the direction of the arrow with tension, and a machining gap is formed between it and the workpiece 6 disposed opposite to it. Machining fluid (water, oil, etc.) is supplied to the gap from nozzles 7 and 8.
Electricity is applied between the cut and the workpiece to process it. 9 is a vertical movement device for the guide 5; 10 is an ultrasonic vibrator; this vibration is transmitted to the integrally formed vibrating tip member fixed to the guide 4 via a transmitter such as a horn 11; Vibrations impart vibrations to the wire 1. Therefore, the guide 4 has both the function of guiding the running movement of the wire 1 and the function of imparting vibration to the wire 1. Reference numeral 12 denotes a member that forms a coolant flow path over the entire vibrating device such as a vibrator and a horn, and the portion of the guide 4 that applies vibration, into which the coolant is supplied and distributed from a pipe 13.

The workpiece 6 is fixed to a processing table (not shown), and is normally machined into a desired shape by machining feed in the two-dimensional X and Y axes of this processing table. During this processing, the wire electrode 1 has a guide 4,
An appropriate tensile force is applied between the parts 5 and 5, and the parts move in the direction of the arrow under tension. When the wire 1 moving under tension between the guides 4 and 5 is vibrated at the guide 4 portion, the wave-like vibration acts on the wire 1 between the guides 4 and 5 and propagates to the portion facing the workpiece. It is preferable that the vibration generated in the wire 1 is a higher-order harmonic vibration in which two or more antinodes are formed, rather than a fundamental vibration in which the guides 4 and 5 at both ends are nodes and the central part is an antinode. Therefore, the frequency F is given by the following equation (1).

n: Vibration order L: Wire length between guides (cm) γ: Wire electrode unit length weight (Kg/cm) P: Tension (Kg) g: Gravitational acceleration 981 (cm/S ² ) Therefore, vibration order n is as follows.

From equation (2), in order to generate wave-like vibration with two or more antinodes and nodes in the wire 1 between the guides 4 and 5, n
It is only necessary to satisfy the condition ≧2, and it is possible to easily generate wave-like vibration by setting the conditions, and even if an arc or short circuit occurs in the gap, it can be extinguished mechanically. The effect of removing machining waste and air bubbles is enhanced, and the contact friction resistance of the guide part is also significantly reduced, allowing for smooth wire guidance and sufficient tension.
If the vibration is the fundamental vibration, there is a risk that the shape of the machined surface will become a drum-shaped curve, but if it is a high-order harmonic vibration, this risk disappears, and the pulse discharge is at the antinode of the vibration. Because it is easy to occur,
If high-order double vibration is performed, the dispersion of the discharge points will improve, which will prevent wire breakage due to concentrated discharge, and will increase the ratio of pulsed discharge to the applied voltage pulse, improving machining efficiency. Due to the synergistic effect of these vibrations, the thin wire 1 can continue to be stably processed without breaking, and the processing speed is improved. In addition, in wire cutting, which is processed by repeated arc discharge, if the specific resistance of the machining fluid is low, the electrolytic machining effect will increase, making it difficult to generate a good pulse discharge in the gap. Conventionally, it was necessary to use a machining fluid with high specific resistance, but the periodic movement of the wire 1 approaching the machining surface due to vibration acts as a trigger for the generation of electric discharge, making it easier to generate pulsed electric discharge. It is now possible to use a machining fluid with a lower resistivity than before, and whereas conventionally a high-resistance fluid with a resistivity of about 10 ⁵ to ^{10 6} Ωcm was used by ion-exchanging tap water, the present invention Specific resistance: 10 ₃ ~ 10 ₄
Stable machining can be performed even with water of about Ωcm as the machining fluid, and the machining current can be increased by making the gap easy to discharge, increasing the machining speed. In addition, tap water that is not treated with ion exchange resin can be used directly as the processing liquid, and even if ion exchange treatment is performed, the treatment time can be reduced.

The vibration amplitude applied to the wire electrode 1 is usually 1
It can be used up to about 3μ, in some cases up to about 5μ, and the vibration frequency is 100Hz or more, preferably 10K or more.
Apply 50KHz sound waves. For example, 0.2mmφ
Using Cu electrode, P=800g, L=10cm, F=
If it is 10KHz, γ=2.8×10 ⁶ Kg/cm.
From equation (2), the vibration order n is approximately 12.

However, when such vibrations are continued, the vibration generation voltage and its vibration propagation action parts generate heat and are heated, but a member 12 is provided to surround them, and cooling water is passed through a pipe 13 to cool them down. ing. Therefore, the vibration generating device is not overheated and can stably generate a predetermined vibration, and can generate stable vibrations with no change in amplitude, frequency, etc. In addition, parts of mechanical devices such as guides that are subjected to vibrations are also overheated and expand and contract, allowing stable guidance to be performed without deteriorating machine precision, making it possible to perform stable machining with high precision. In addition, the wire electrode does not stretch or become thinner due to heating of the guide part, and the machining part can be moved with a predetermined dimensional tension, and there is no wire breakage, and stable vibration allows stable machining. It can be continued.

As described above, the present invention can significantly improve the processing effect of wire cuts, and is extremely effective in practice.

Note that the vibration device may be provided on the guide 5 or on both the guides 4 and 5. The cooling device may utilize the machining fluid supplied to the machining portion, and cooling devices that utilize air blowing, heat of evaporation, etc. other than the liquid flow can also be used.

[Brief explanation of the drawing]

The drawing shows an embodiment of the present invention. 1 is a wire electrode, 2 and 3 are reels, 4 and 5 are guides, 6 is a workpiece, 7 and 8 are machining fluid supply nozzles, 10 is a vibrator, 11 is a vibration transmitter, and 12 is a coolant flow path formation The member 13 is a coolant supply pipe.

Claims (1)

[Claims] 1. Supplying machining fluid to a gap between a wire electrode and a workpiece disposed opposite to each other and applying a voltage pulse to give a machining shape feed to the wire electrode or the workpiece. A vibrating device in which a vibrating tip member is formed integrally with a guide for guiding the axial movement of a wire electrode in a machining section facing a workpiece in an energized wire cutting device for machining, and the vibrating device An energizing wire cutting device characterized by being provided with a cooling device for cooling the energized wire. 2. An energized wire cutting device characterized in that the cooling device according to claim 1 is configured to allow a cooling liquid to flow through it.