JPH0379228A - Wire electric discharge machine - Google Patents

Abstract

PURPOSE:To increase drive efficiency and improve positioning precision by using a piezoelectric actuator as a drive source. CONSTITUTION:When an alternating current electric signal is impressed on piezoelectric acutators 11a, 11b which obtain a machine output by utilizing, for example, an piezoelectric body as an electric machine conversion element, approximately oval vibrations of a minute amplitude are excited at their predetermined places, and a machining stand 31 which is a driven body, receives the force of drive, and is directly driven in a predetermined direction in relativity with a wire electrode 32. At this time, a work 50 mounted on the machining stand 31 is machined by means of an electric discharge phenomenon with the wire electrode 32.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a wire electrical discharge machine that generates electrical discharge between a workpiece and a wire electrode and processes the workpiece using the discharge energy. be.

[Prior Art] A wire electrical discharge machine generates an electrical discharge between a workpiece that is moved relative to a wire electrode, and processes the workpiece using the discharge energy.

Conventionally, workpieces have been transferred using a drive source consisting of a rotary electromagnetic motor and a power conversion mechanism consisting of a screw, etc., converting rotational motion into linear motion and moving the processing table in two directions within a plane. I was able to act by moving.

The drive control of the electromagnetic motor is automatically performed according to the program of the computer.

[Problems to be Solved by the Invention] However, in the above-mentioned wire electric discharge machine, the power loss in the power conversion mechanism is large, so the drive efficiency is low.
In addition, backlash etc. have made it difficult to perform highly accurate positioning on the order of microns.

In addition, the electromagnetic motor used as the drive source cannot be said to have good responsiveness and is likely to generate magnetic noise, so electromagnetic noise shielding means are required to prevent malfunction of the computer used in the control system. The problem was that it was necessary.

The present invention has been made to solve the above-mentioned problems, and its purpose is to obtain a wire electrical discharge machine that has high drive efficiency and can achieve high positioning accuracy by directly driving a piezoelectric actuator. It is said that

Furthermore, the objective is to obtain an excellent wire electric discharge machine that has a high machining speed and has little risk of malfunction.

[Means for Solving the Problems] In order to achieve this object, the wire electrical discharge machine of the present invention connects a substantially thin wire electrode and a processing table on which a workpiece is placed with two degrees of freedom in a plane. A piezoelectric actuator is used as a driving source for relative driving.

Further, the piezoelectric actuator includes an elastic body, and an electromechanical transducer that generates ultrasonic vibration when an AC electric signal is applied to the elastic body is attached, and by driving the electromechanical transducer, a predetermined vibration is generated. The ultrasonic transducer is provided with an ultrasonic vibrator that is excited to vibrate in at least two directions substantially orthogonal to the vibrating site.

[Function] In the wire electric discharge machine of the present invention having the above configuration, when an AC electric signal is applied to a piezoelectric actuator that obtains a mechanical output using, for example, a piezoelectric body as an electromechanical transducer, a predetermined portion of the piezoelectric actuator is Substantially elliptical vibration with minute amplitude is excited, and the processing table, which is a driven body, receives the driving force and is directly driven in a predetermined direction relative to the wire electrode.

At this time, the workpiece placed on the processing table is processed by an electric discharge phenomenon between the workpiece and the wire electrode.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

The piezoelectric actuator used in the present invention is disclosed in, for example, Japanese Patent Application No.
An ultrasonic transducer including a mechanical resonator as proposed in the specification and drawings attached to application No. 46866 may be used.

An example of the configuration will be described below with reference to FIG. The ultrasonic transducer 11 includes an elastic body 2 having a rectangular flat plate shape.
A first piezoelectric body 22 for exciting bending vibration in the elastic body 21 is attached to the upper surface of the elastic body 1 . In the elastic body 21, second piezoelectric bodies 23a and 23b for exciting longitudinal vibration in the elastic body 21 are attached to the side surfaces substantially orthogonal to the mounting surface.

The longitudinal center of the elastic body 21 is fixed by fixing bolts 24a and 24b for fixing the elastic body 21. The other ends of the fixing bolts 24a and 24b are fixed to bases 25a and 25b.

An electrode 26 is provided on the upper surface of the first piezoelectric body 22 . Further, electrodes 27a and 27b are installed on the upper surfaces of the second piezoelectric bodies 23a and 23b. The elastic body 21 itself also serves as a ground electrode, and is grounded to the bases 25a and 25b via the fixing bolts 24a and 24b.

Further, the elastic body 21 bends in a secondary mode at both free ends at a predetermined frequency f in the thickness direction, and longitudinally vibrates in a primary mode at both free ends in the length direction at the same frequency f. The shape and dimensions have been adjusted.

Generally, the resonant frequency of longitudinal vibration propagating in an elastic body depends on the length of the elastic body. Further, the resonance frequency of bending vibration in the thickness direction of the elastic body depends on the length and thickness. Therefore, since it is easy to design the elastic body 21 as described above, the details thereof will be omitted.

The operation of the ultrasonic transducer 11 configured as above will be explained below.

First, when an alternating current voltage of frequency f is applied to the first piezoelectric body 22 to cause it to vibrate, the elastic body 21 resonates in a secondary mode of bending vibration and a standing wave is excited.

Next, when an alternating current voltage of frequency f is applied to the second piezoelectric bodies 23a and 23b to cause them to vibrate, the elastic body 21 vibrates in the first mode of longitudinal vibration and a standing wave is excited. In other words, the positions fixed by the fixing bolts 24a and 24b are the nodes of each standing wave.

At this time, the first piezoelectric body 22 and the second piezoelectric bodies 23a and 2
By adjusting the amplitude and phase of the voltage applied to the elastic body 3b, it is possible to generate substantially elliptical vibration of any shape in the elastic body 21.

In the above embodiment, an ultrasonic vibrator that excites the first-order mode of longitudinal vibration and the second-order mode of bending vibration and generates approximately elliptical vibration by combining them is described, but the present invention is not limited to this, and Various vibration modes such as , bending vibration, shear vibration, and torsional vibration can be used, and higher-order modes may also be used.

A machining table 31 of a wire electric discharge machine that suitably utilizes the above-mentioned ultrasonic vibrator 11 is shown in FIGS. 2 and 3. In this figure, each member labeled with the same reference numeral as in FIG. 1 is the same as each component described in detail above.

The wire electrode 32 is supplied from a wire supply reel (not shown) to power supply rollers 33 disposed above and below the processing table 31.
a and 33b, and is sent to a take-up reel (not shown) and wound up.

The processing table 31 has an X-axis table 34 and a Y-axis table 35.
The two tables have a structure in which they are stacked one above the other, and the two tables have a hollow frame shape for passing the wire electrode 32 therethrough. The X-axis table 34 includes a first ultrasonic transducer 11a supported on a base 37 via a support member 36, and a pressure bonding mechanism 38a made of a rubber roller and also attached to the base 37.

38b and 38c are crimped with a predetermined pressure.

The first ultrasonic transducer 11a has drive parts 39a and 39b formed at both ends where the maximum amplitude can be obtained, and is press-fitted to the X-axis table 34.

Similarly, in the Y-axis table 35, the support member 4
0 supports the second ultrasonic transducer 11b, and is crimped with a predetermined pressure by crimping mechanisms 41a, 41b, and 41c.
and 42b are formed.

In the wire electric discharge machine as described above, when an alternating current voltage of a predetermined frequency is applied to the first ultrasonic vibrator 11a, the vibration amplitude varies from several tens of degrees to several tenths. Approximately elliptical vibrations with a very small amplitude are excited. As a result, the drive parts 39a and 39
The X-axis table 34 is driven in the direction of the arrow X in the figure by receiving a driving force caused by the frictional force between the X-axis table 34 and the X-axis table 34.

At this time, since the ultrasonic vibrator 11a utilizes a resonance phenomenon, its vibration displacement is orders of magnitude larger than that of a fine movement mechanism using a conventional laminated piezoelectric actuator, and it has high-speed movement and high-speed response. is possible. the result,
A workpiece 50 placed on the X-axis table 34 is processed.

Further, the Y-axis table 35 is also driven in the direction of the arrow Y in the figure by the same principle of operation.

Incidentally, by forming the driving parts 39a, 39b and 42a, 42b formed in the ultrasonic transducers 11a and llb from ceramic, insulation and wear resistance can be improved.

The piezoelectric actuator used in the present invention has the following various advantages over conventional electromagnetic motors.

1) No winding required, simple structure, small size,
It is possible to reduce the weight.

2) High energy conversion efficiency can be obtained; for example, the output/volume ratio and output/weight ratio are 10 times or more compared to a DC motor.

3) Since it uses frictional force, it has excellent responsiveness and position controllability.

4) Does not generate magnetic or electromagnetic noise.

Furthermore, in the above embodiments, an ultrasonic vibrator that generates standing wave vibration is used as an example of the piezoelectric actuator.
Various piezoelectric actuators are possible.

Further, although an example in which the ultrasonic transducer is shaped like a flat plate has been described, the shape is not limited thereto, and rod-shaped, rectangular, cylindrical, disc-shaped, annular, etc. may also be used.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, it is possible to realize a wire electrical discharge machine with high drive efficiency and high positioning accuracy.

Furthermore, it is possible to realize an excellent wire electric discharge machine that has a high machining speed and has little risk of malfunction.

[Brief explanation of drawings]

1 to 3 show embodiments embodying the present invention. FIG. 1 is a top view of an ultrasonic vibrator used in the present invention, and FIG. 2 is a wire electric discharge machining process to which the present invention is applied. FIG. 3, which is an overall perspective view of the machine, is an explanatory view showing the mounting state of the processing table of the wire electric discharge machine. In the figure, 11 is an ultrasonic transducer, 21 is an elastic body, and 22 is a first
A piezoelectric body, 23a and 23b are second piezoelectric bodies, 31 is a processing table,
32 is a wire electrode, 34 is an X-axis table, 35 is a Y-axis table, and 50 is a workpiece.

Claims (1)

[Claims] 1. A substantially thin wire electrode (32) and a workpiece (50
) is provided with a drive source for relatively driving the processing table (31) on which the wire electrode (3
2) and a workpiece (50), and a wire electric discharge machine that processes the workpiece (50) using the discharge energy, piezoelectric actuators (11a, 11b) are used as the drive source.
) A wire electrical discharge machine characterized by using. 2. The wire electrical discharge machine according to claim 1, wherein the piezoelectric actuator includes an elastic body (21),
21), electromechanical transducers (22, 23a, 23
b) is attached, and includes an ultrasonic vibrator (11) that is excited to vibrate in at least two directions substantially orthogonal to a predetermined vibration site by driving the electromechanical transducer (22, 23a, 23b). A wire electrical discharge machine featuring: