JPS6252457A - Apparatus for generating dummy breakage signal - Google Patents

Abstract

PURPOSE:To make it possible to easily discriminate whether an AE signal is generated when the adjustment of the sensitivity of an AE sensor is performed by using a dummy breakage signal generator, by displaying the driving based on the output of a dummy breakage signal oscillation part. CONSTITUTION:The AE converter 2 of a dummy breakage signal generator is fixed to the upper part of the work of a machine tool and a dummy breakage signal level is set to an amplifier 9 corresponding to the kind of a tool to be used. When an oscillation start signal is applied to a terminal 5, the clock signal from a clock generator 6 is inputted to a multiplier 8 through a differentiation circuit 7 and multiplied by the noise signal with frequency of about 300kHz from a band-pass filter 4 to generate a dummy breakage signal wave form. The dummy breakage signal is applied to the piezoelectric element 13 of an AE signal generator through a transformer 1 and a cable 12 and a dummy breakage signal with a predetermined level is transmitted to the work. At this time, because a driving current is transmitted to a light emitting diode 15, the light emitting diode 15 lights to display that the dummy breakage signal is emitted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention solves the problem of tool breakage and abnormality in machine tools by acoustic emissions (
(hereinafter referred to as AE) for monitoring.

The present invention relates to a pseudo-breakage signal generating device used for adjusting the sensitivity of an AE sensor of a tool breakage detection device that automatically detects tool breakage.

[Summary of the invention]

The pseudo-breakage signal generating device according to the present invention is provided with an indicator that displays the driving of the drive signal in order to clarify whether power is supplied to the pseudo-breakage signal generating device and the pseudo-breakage signal is being generated. This is what I did. In this way, when the pseudo-breakage signal generating device is driven, the driving can be clearly identified.

[Background of the invention]

When a machine tool uses a tool to cut an object to be machined (hereinafter referred to as a workpiece), the tool may break for some reason or become clogged with chips, resulting in abnormal cutting. With the recent progress in factory automation, there is a strong demand for automatic detection of tool breakage and abnormal cutting. As a method for detecting tool breakage in machine tools, conventional methods have been to
An apparatus has been proposed that includes a sensor and detects tool breakage based on an AE multiplied signal obtained from the sensor.

However, according to the conventional tool breakage detection device, the AE sensor is mounted near the tool or in contact with the workpiece, but the AE multiplied signal level varies greatly depending on the mounting position. Therefore, the applicant has already applied for patent application No. 59-101554.
A pseudo-breakage signal generation means is provided to give the same signal to the machine tool as when the tool breaks, and based on this, the AE
Proposes a device to set sensor sensitivity (unpublished)
. However, since the pseudo-breakage signal generating means emits an ultrasonic signal, the ultrasonic signal cannot be directly detected by the ear. Therefore, it was not possible to easily determine whether the pseudo-breakage signal was correctly generated and transmitted to the AE sensor attached to the machine tool. Therefore, when a pseudo-breakage signal cannot be received from the AE sensor, it is difficult to determine whether the cause is on the pseudo-breakage signal generator side or the AE sensor side, making it difficult to use.

[Purpose of the invention]

The present invention has been made in view of the problems of such a pseudo-breakage signal generating device, and an object of the present invention is to provide a pseudo-breakage signal generating device that can easily detect the generation of an ultrasonic signal.

[Structure and effects of the invention]

The present invention is a pseudo-breakage signal generating device for use in adjusting the sensitivity of a tool breakage detection device that has an AE sensor installed near a tool of a machine tool and detects breakage based on an AE multiplied signal when a tool breaks. A pseudo-breakage signal oscillator that oscillates a pseudo-breakage signal including the frequencies of the A and E signals obtained at the time of breakage, and a pseudo-breakage signal oscillator that is installed near the tool of the machine tool and is driven by the output of the pseudo-breakage signal to convert the pseudo-breakage signal into an electrical signal. The present invention is characterized by comprising a piezoelectric element to be converted, and an AE signal converter having a display connected in parallel to the piezoelectric element and displaying the drive based on a drive signal of the piezoelectric element.

According to the present invention having such features, when the pseudo-breakage signal generating device is used to adjust the sensitivity of the AE sensor, the driving state is displayed on the display during driving.

Therefore, it is possible to easily identify whether or not the AE multiplied signal is oscillating, and it is possible to easily set the sensitivity of the AE sensor.

[Explanation of Examples]

(Configuration of pseudo-breakage signal generating device) FIG. 1 is a block diagram showing the overall configuration of an embodiment of the pseudo-breakage signal generating device according to the present invention. As shown in this figure, the pseudo-breakage signal generating device has a drive circuit 1 that generates a pseudo-breakage signal, and an AE signal converter 2 that transmits the pseudo-breakage signal to a machine tool.

The drive circuit 1 includes a pseudo-breakage signal oscillation section and an amplifier that amplifies its output based on a drive level applied from the outside. The pseudo-breakage signal oscillation section is provided with a noise generator 3 that generates white noise up to a frequency of around 300 KHz, and a bandpass filter 4 that transmits only noise having components around a frequency of 300 Kllz to the next stage. Further, a clock generator 6 that generates a clock signal of a predetermined period based on an oscillation start signal given from the terminal 5 and a differentiation circuit 7 that differentiates its output are provided, and the outputs of the bandpass filter 4 and the differentiation circuit 7 are used as a multiplier. given to 8. The multiplier 8 multiplies the output of the bandpass filter 4 and the differential output to generate the same signal as when the tool breaks, and its output is given to the amplifier 9. Amplifier 9 is a variable gain amplifier that amplifies the pseudo-breakdown signal based on a level setting input applied from terminal 10, and its output is applied to transformer 11 for impedance conversion. The secondary output of the transformer 11 is transmitted to the AE signal converter 2 via the cable 12.

The AE signal converter 2 is fixed on a workpiece (not shown), and a piezoelectric element 13 that converts a pseudo-breakage signal into mechanical vibration is connected to the output end of a cable 12 as shown in the figure. A light emitting diode 15 is connected to the resistor 14 via a resistor 14.

Further, a diode 16 for reverse voltage protection is connected in parallel with the light emitting diode 154 in a direction opposite to that of the light emitting diode 15.

FIG. 2 is a side view and a top view showing the appearance of the AE signal converter 2, and FIG. 3 is a longitudinal sectional view thereof.

As shown in these figures, the AE signal converter 2 has a ceramic plate 21 provided at the bottom of a cylindrical insulating case 20, and the above-described piezoelectric element 13 is disposed above the ceramic plate 21. A resistor 14 and a diode 16 are provided inside the case 20, and are filled and fixed with an insulating resin 22.

A cable lead-out part 23 is integrally formed in the case 20, and the above-mentioned light emitting diode 1 is mounted on the upper surface of the cable lead-out part 23 as shown in the figure.
5 is installed.

(Operation of pseudo-breakage signal generating device) The AE converter 2 of the pseudo-breakage signal generating device configured in this manner is fixed to the upper part of the workpiece of a machine tool (not shown), and a pseudo-breakage signal is generated depending on the type of tool used, for example, the drill diameter. Set the level to amplifier 9.

When an oscillation start signal is applied to the terminal 5, the clock generator 6 generates a lock signal as shown in FIG. A differential waveform like this can be obtained.

Further, a noise signal with a frequency of around 300 KHz from the noise generator 3 and bandpass filter 4 is added to the multiplier 8 and multiplied, producing a pseudo-broken signal waveform as shown in FIG. Then, the AE is connected from the secondary output of the transformer 11 through the cable 12.
A pseudo-breakage signal of a predetermined level is applied to the piezoelectric element 13 of the signal generator and transmitted to the workpiece. At this time, at the same time as the piezoelectric element 13 is driven, the light emitting diode 15 connected in parallel
Since the driving current is also transmitted to the light emitting diode 15, the light emitting diode 15 lights up, indicating that a pseudo-breakage signal is being generated. Therefore, by adjusting the output level from the AE sensor installed in the machine tool to a predetermined value, it is possible to easily adjust the sensitivity, etc. of the AE sensor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the pseudo-breakage signal generating device according to the present invention, and FIG.
Figure 2(b) is a side view of the signal converter; Figure 2(b) is its top view; Figure 3(b) is its top view;
The figure is a longitudinal sectional view thereof, and FIG. 4 is a waveform diagram showing waveforms of various parts of the pseudo-breakage signal generating device of this embodiment. 1--Drive circuit 2, ---A E signal converter
3...--Noise generator 4--Band pass filter 6--Clock generator 7--Differentiating circuit 8--Multiplier 9--1...Amplifier 11-・−・−Transformer 12・・・・−・Cable 13. -...Piezoelectric element 14--1--...
Resistor 15-・-・Light-emitting diode 16-・-
Diode patent applicant Tateishi Electric Co., Ltd. agent Patent attorney Yoshiki Okamoto (and one other person) Figure 2 (8) Figure 2 (b) Figure 3

Claims (2)

[Claims] (1) A pseudo-breakage signal generating device used for adjusting the sensitivity of a tool breakage detection device that has an AE sensor installed near a tool of a machine tool and detects breakage based on an AE signal when a tool breaks, a pseudo-breakage signal oscillator that oscillates a pseudo-breakage signal including the frequency of an AE signal obtained at the time of breakage; and a pseudo-breakage signal oscillator that is provided near the tool of the machine tool and is driven by the output of the pseudo-breakage signal oscillator to convert the pseudo-breakage signal into an electrical signal. piezoelectric element,
and an AE signal converter having a display that is connected in parallel to the piezoelectric element and displays the drive of the piezoelectric element using a drive signal of the piezoelectric element. (2) The pseudo-breakage signal generating device according to claim 1, wherein the indicator is a light emitting diode, and the light emitting diode and the resistor are connected in parallel to the piezoelectric element.