JP2001252850A - Damage detecting device for rotary cutting blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To observe damage to a rotary cutting blade at turning work directly without expensive equipment such as FFT, an acoustic analyzer, or the like. SOLUTION: In detecting damage to a rotary cutting blade 10 containing a blade body 13 composed of an electrical insulating material fixed to a rotating driving shaft 11, this failure detecting device for a rotary cutting blade is provided with a first loop coil 16 held coaxially with the rotating driving shaft 11, and a second loop coil 21 arranged concentrically with the first loop coil 16. The first loop coil 16 is connected to a failure detecting switch comprising a metallic thin film 14 formed along a cutting edge line of the blade body 13 and a clock signal generating means containing a quartz oscillator. The second loop coil 21 is connected to an oscillation circuit having almost equivalent oscillation frequency with a resonance frequency of the clock signal generating means and an echo back detecting means alternatively through a switch means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting damage to a rotary cutting blade, and more particularly, to detecting damage to a rotary cutting blade during turning (in-process) without stopping the apparatus. The present invention relates to a device for detecting breakage of a rotary cutting blade.

[0002]

2. Description of the Related Art Rotary cutting blades are used for various types of machining, but their damage is a direct cause of the occurrence of defective products. Therefore, an early and reliable detection method is required. However, since the rotary cutting blade during turning is rotating at a high speed and is dangerous when approaching, it has been considered extremely difficult to directly monitor the state of the blade (blade edge).

In view of the above, in the prior art, the breakage of the blade body is exclusively monitored indirectly, and the two most recent examples of the present invention will be described. First, in the first conventional example, as shown in FIG. 10, when turning the workpiece W with the rotary cutting blade 1, vibration or sound is applied to the fixing jig 2 of the workpiece W. The sensor 3 to be picked up is attached, and its detection signal is monitored by FFT (Fast Fourier Transform) or an acoustic analyzer. If the picked-up vibration or sound is different from the normal state, the cutting is stopped as an abnormal state.

In the second conventional example shown in FIG. 11, a rotary cutting blade 1 during turning of a workpiece W is monitored by an infrared radiation thermometer 4. Since the temperature of the rotary cutting blade 1 rises in the event of an abnormality, this is judged by the comparator 5, and when the temperature becomes equal to or higher than a predetermined temperature, it is determined that there is an abnormality and the cutting is stopped.

[0005]

According to these prior arts, the abnormality of the rotary cutting blade 1 can be detected without fail. First, however, the first problem is that an analysis means such as an FFT or an acoustic analyzer is used. However, even if the infrared radiation thermometer 4 is used, the cost is reflected on the workpiece W after all because it is an expensive device.

As a second problem, it is necessary to set a comparison reference pattern and a comparison reference value (threshold value). These comparison reference patterns and comparison reference values differ depending on the workpiece W. Therefore, a setting operation must be performed each time. In addition, if the setting is not appropriate, the detection accuracy becomes uncertain, so that considerable time and labor are required.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to directly damage a rotary cutting blade during turning while having a simple and inexpensive structure. An object of the present invention is to provide a breakage detecting device for a rotary cutting blade, which can be monitored in a dynamic manner.

In order to achieve the above object, a first invention of the present application is a damage detection device for a rotary cutting blade including a blade body made of an electrically insulating material fixed to a rotary drive shaft, which rotates together with the rotary drive shaft. And a fixed-side second loop coil concentrically arranged with respect to the first loop coil. The one loop coil is connected to a breakage detection switch made of a metal thin film formed along the cutting edge of the blade body, and a clock signal generating means including a crystal oscillator, and is connected to the second loop coil. Is characterized in that an oscillation circuit having an oscillation frequency substantially the same as the resonance frequency of the clock signal generation means and the echo back detection means are alternately connected via switch means.

In the first invention, when the switch means is switched to the oscillating circuit side and a radio wave equal to the resonance frequency of the clock signal generating means is transmitted from the second loop coil, the radio wave is received by the first loop coil, The clock signal generating means resonates. The clock signal generating means keeps oscillating for a while even if the oscillation circuit is disconnected from the second loop coil due to its inherent characteristics.

Therefore, by detecting the continuous vibration as an echo back from the second loop coil, it is possible to detect whether or not the blade body is damaged. By the way, when the blade body is broken, the metal thin film is also broken and the damage detection switch is turned off, and the first loop coil is opened, so that echo back is not detected.

Usually, this type of rotary cutting blade has a plurality of blades. Therefore, if any one of the blades is damaged, it can be detected by connecting the damage detection switch provided in each of them in series with the first loop coil.

Further, a damage detection switch provided on each blade body may be connected in parallel to the first loop coil. In this case, clock signal generating means having different resonance frequencies are connected in series to each of the damage detection switches, and the oscillation frequency of the oscillation circuit is changed every time the switch means is switched. To be switched sequentially. According to this, it is also possible to detect which blade body has been damaged.

According to a second aspect of the present invention, there is provided a breakage detecting device for a rotary cutting blade including a blade body made of an electrically insulating material fixed to a rotary drive shaft, wherein the rotary drive shaft side rotates together with the rotary drive shaft. And a drive coil having an AC signal source supported by fixed-side support means facing the respective rotation-side coils and a signal detection means. A detection coil, wherein the first and second coils are connected to each other via a breakage detection switch made of a thin metal film formed along the cutting edge of the blade body. The above object is also achieved by the above.

According to the second aspect, a current is induced in one of the coils (the receiving coil) by the drive coil, and the other coil becomes the oscillation coil. Therefore, when the blade body is not damaged, a pulse-like waveform corresponding to the rotation of the rotary cutting blade is detected from the detection coil. When the blade body is broken, the metal thin film is also broken and the damage detection switch is turned off, so that each coil is electrically disconnected. Therefore, the output from the detection coil is interrupted, thereby detecting damage to the blade body.

In this case, the first and second coils may be arranged symmetrically about the rotation drive shaft, and the drive coil and the detection coil may also be arranged symmetrically about the rotation drive shaft. On the other hand, the first and second coils may be arranged at positions overlapping each other, and the drive coil and the detection coil may also be arranged at positions overlapping each other.

According to a third aspect of the present invention, there is provided a damage detection device for a rotary cutting blade including a blade body made of an electrically insulating material fixed to a rotary drive shaft, wherein the rotary drive is configured to rotate together with the rotary drive shaft. A power generating coil attached to the shaft side and signal generating means driven by the power generating coil,
The fixed-side supporting means includes a magnet and a fixed-side signal receiving means supported so as to surround the power generating coil, and between the power generating coil and the signal generating means, a cutting edge of the blade body is provided. It is characterized in that a breakage detection switch formed of a metal thin film formed along the connection is connected, thereby achieving the above object.

That is, when the blade is not damaged, the signal receiving means is driven by the electric power generated by the power generating coil. However, when the blade is damaged, its metal thin film is also broken and damaged. Since the detection switch is turned off, the power generation coil and the signal receiving means are electrically disconnected, and thereby the damage of the blade body is detected.

In the third aspect, the signal generating means may be a light emitting element and the signal receiving means may be a light receiving element. That is, it may be a photocoupler. Further, the signal generating means may be a wireless signal transmitting circuit, and the signal receiving means may be a wireless signal receiving circuit.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will now be described. FIG. 1 is a schematic perspective view of the first embodiment. In the damage detection device 1A of the first embodiment, the rotary cutting blade 10 to be damaged is
It has a substrate 12 attached to a rotary drive shaft 11, and the substrate 12 has a plurality of, in this example, four blades 13a to 13
d is fixed at intervals of 90 degrees. The rotation drive shaft 11 is connected to a motor (not shown).

Each of the blades 13a to 13d is made of an electrically insulating material such as ceramic. In this embodiment, an alumina base material is used. Since each of the blades 13a to 13d has the same configuration, the reference numeral 13 is used as a generic term for the blades unless it is necessary to specifically describe them.

As shown in FIG. 2, the blade 13 has, for example, a triangular shape, and a metal thin film 14 is formed along the cutting edge line. In this embodiment, the metal thin film 14 is made of a TiN film. The metal thin film 14 is formed so as to be removed or peeled off from the edge of the cutting edge as the blade 13 is damaged, and functions as a damage detection switch for the blade 13. When the metal thin film 14 of each of the blades 13a to 13d is individually indicated, the same thin suffix is attached to the metal thin film 14 to form metal thin films 14a to 14d.

A disk 15 is coaxially fixed to the rotary drive shaft 11. Referring to the circuit diagram of FIG. 3 as well, a first loop coil (loop antenna) 16
Are provided concentrically with respect to the rotary drive shaft 11. Between the terminals of the first loop coil 16, a clock signal generator 17 including a crystal oscillator and a breakage detection switch 18 of the blade 13 are connected in series via predetermined wiring.

In this case, the breakage detecting switches 18 are made of metal thin films 14a to 14d. In the circuit diagram of FIG. 3, these are the breakage detecting switches 18a to 18d. In the first embodiment, each of the damage detection switches 18a to 18
d is connected in series.

Assuming that the configuration of the rotary cutting blade 10 is the rotary side, the damage detection device 1A includes a second loop coil 21 as a fixed-side component. The second loop coil 21 is supported by the support arm 22 so as to be concentric with the first loop coil 16. In this embodiment, the second loop coil 21 is arranged so as to surround the first loop coil 16, but may be arranged above or below the first loop coil 16 so as to overlap with the first loop coil 16.

The second loop coil 21 includes an oscillation circuit 24
And the echo back detection means 25 are alternately connected via the switch 23. The oscillation circuit 24 outputs a signal having substantially the same frequency as the resonance frequency of the clock signal generator 17. The echo back detection means 25 includes an amplifier 25a, A /
D converter 25b and CPU (ce as a detector main body)
ntral processing unit) 25c
It has.

Next, the operation of the first embodiment will be described. Assuming that the rotary cutting blade 10 is driven by the motor to turn the workpiece, first, the switch 23 is switched to the oscillation circuit 24 side, and the electromagnetic wave having the same frequency as the resonance frequency of the clock signal generator 17 is output from the second loop coil 21. Release.

When the electromagnetic wave is received by the first loop coil 16, the clock signal generator 17 starts to resonate.
Next, the switch 23 is switched from the oscillation circuit 24 to the echo back detection means 25 side. Thus, the oscillation circuit 24
Is separated from the second loop coil 21, the clock signal generator 17 continues to vibrate for a predetermined time due to its inherent characteristics.

This continuous vibration is used as an echo back for the second
Appears in the loop coil 21. The echo back signal is amplified in a predetermined manner by an amplifier 25a, converted into a digital signal by an A / D converter 25b, and provided to a CPU 25c. The CPU 25c monitors the blade 13 based on the presence or absence of the echo back signal.

That is, if an echo back signal is obtained every time the switch 23 is switched, it is determined that the blade 13 is not damaged. On the other hand, if no echo back signal is detected, one of the damage detection switches 18a to 18d is turned off, and it is determined that the blade 13 is damaged.

Then, the switch 23 is switched again from the echo back detecting means 25 to the oscillation circuit 24. The switching timing is preferably at a time before the echo back signal disappears.

As shown in the circuit diagram of FIG. 4, as a modification of the first embodiment, four breakage detection switches 18a to 18d may be connected in parallel to the first loop coil 16. Good. In this case, clock signal generators 17a to 17d having different resonance frequencies are connected in series to the damage detection switches 18a to 18d.

The oscillation circuit 24 is of a variable frequency type, and outputs a frequency signal substantially equal to the resonance frequency of each of the clock signal generators 17a to 17d.
In this modification, the oscillation frequency of the oscillation circuit 24 is sequentially changed every time the switch 23 is switched.

For example, the oscillation frequency of the oscillation circuit 24 is calculated as follows: the resonance frequency of the clock signal generator 17a → the resonance frequency of the clock signal generator 17b → the resonance frequency of the clock signal generator 17c → the resonance frequency of the clock signal generator 17d. Switch the frequency sequentially. According to this, by examining the clock signal generator 17 having no echo back signal, it is possible to detect which blade 13 has been damaged (abnormal).

Next, a damage detection device 1B according to a second embodiment of the present invention will be described with reference to FIGS. In addition,
In the second embodiment, the same reference numerals are used for components that may or may be considered the same as in the first embodiment.

According to the second embodiment, the rotary drive shaft 11
A pair of coils 31 and 3
2 are provided. The arrangement is symmetric about the rotary drive shaft 11. As shown in the circuit diagram of FIG. 6, a breakage detection switch 18 is connected between the coil 31 and the coil 32. Breakage detection switch 18
Are metal thin films 14a to 14d as in the first embodiment.
And four break detection switches 18a to 18d connected in series with each other.

A drive coil 41 and a detection coil 42 are provided on the fixed-side support arm 22. in this case,
The drive coil 41 and the detection coil 42 are the coils 31 and 32
And the coil 3
Like 1 and 32, it is symmetric about the rotation drive shaft 11. An AC signal source 43 is connected to the drive coil 41. The detection coil 42 is connected to a signal detection means 44 including a rectifier circuit 44a and an amplifier 44b for amplifying the rectified output thereof in a predetermined manner.

With the rotation of the rotary cutting blade 10, the coils 31 and 32 alternately face the drive coil 41 and the detection coil 42, and one of the coils facing the drive coil 41 becomes a receiving coil. The other coil on the opposite side becomes the transmitting coil.

That is, the rotary cutting blade 10 is rotated while an AC signal is supplied from the AC signal source 43 to the drive coil 41, and one of the coils 31 faces the drive coil 41 as shown in the circuit diagram of FIG. , The other coil 32 is the detection coil 4
When capturing the point in time opposite to 2, a current is induced in one coil 31 by the magnetic flux from the drive coil 41. That is, one coil 31 operates as a receiving coil.

This current flows through the damage detection switch 18 to the other coil 32, thereby
Generates magnetic flux. That is, the other coil 32 operates as an oscillation coil. Therefore, a current is induced in the detection coil 42 facing the coil 32, and the induced current is detected via the rectifier circuit 44a and the amplifier 44b.

If the blade 13 is normal, the rotary cutting blade 10
As a result, a pulse-like output appears on the signal detecting means 44. On the other hand, when at least one of the damage detection switches 18a to 18d is turned off due to the damage of the blade body 13, the coil 31 and the coil 32 are electrically disconnected, so that the pulse output from the signal detection means 44 disappears. .

Thus, also in the second embodiment,
The blade body 13 can be directly monitored similarly to the first embodiment. As shown in FIG. 7, the coil 31 and the coil 32 are arranged so as to overlap with each other, and the driving coil 41 and the detection coil 42 are also arranged so as to overlap with each other in a corresponding manner. May be. Although not shown, a magnetic shield is provided between the drive coil 41 and the detection coil 42.

Next, a damage detecting device 1C according to a third embodiment of the present invention will be described with reference to FIGS. In addition,
Also in the third embodiment, the same reference numerals are used for components that may or may be regarded as the same as those in the first embodiment.

According to the third embodiment, the rotary drive shaft 11
The power generating coil 51 shown in the circuit diagram of FIG. Signal generating means 53 is connected to the power generation coil 51 via a rectifying / smoothing circuit 52 and a damage detection switch 18.

Also in the third embodiment, the breakage detection switch 18 is provided with the metal thin films 14a to 14a in the same manner as in the above embodiments.
14d and four breakage detection switches 18a to 18d connected in series to each other. A light emitting diode is used for the signal generating means 53.

A pair of permanent magnets 61 a and 61 are attached to the fixed side support arm 22 so as to surround the rotating side power generation coil 51.
b is supported. An electromagnet may be used in place of the permanent magnet. Further, the signal generating means 53 is provided on the support arm 22.
Signal receiving means 62 is provided.
In this example, the signal receiving means 62 comprises a phototransistor. That is, the signal generating means 53 and the signal receiving means 6
2 constitutes a kind of photocoupler.

According to the third embodiment, the rotary cutting blade 10
With the rotation of, AC power is generated from the power generation coil 51. This AC power is converted into DC by the rectifying / smoothing circuit 52 and supplied to the light emitting diode 53 as a signal generating means via the damage detection switch 18. This allows
The light emitting diode 53 lights up in synchronization with the rotation of the rotary cutting blade 10.

On the fixed side, this lighting signal is received by a phototransistor 62 as a signal receiving means, and a pulse output synchronized with the rotation of the rotary cutting blade 10 is obtained from the phototransistor 62.

Therefore, when a pulse output is periodically obtained from the phototransistor 62, the blade 13
Is determined to be normal. On the other hand, when at least one of the damage detection switches 18a to 18d is turned off due to the damage of the blade body 13, the output of the phototransistor 62 disappears because the power generation coil 51 and the light emitting diode 53 are electrically disconnected. become.

As described above, also in the third embodiment,
The blade body 13 can be directly monitored in the same manner as in the first and second embodiments. Note that it is easy to replace the rotating-side signal generating means 53 and the fixed-side signal receiving means 62 with wireless transmitting / receiving means, and such aspects are also included in the present invention.

[0050]

As described above, according to the present invention,
By using a metal thin film formed along the cutting edge line of the blade as a breakage detection switch, turning can be performed without using analysis means such as FFT or acoustic analyzer or expensive equipment such as infrared radiation thermometer. The breakage of the rotating cutting blades inside can be monitored directly.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a first embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing one of the blade bodies used in the present invention.

FIG. 3 is a circuit diagram of the first embodiment.

FIG. 4 is a circuit diagram showing a modification of the first embodiment.

FIG. 5 is a perspective view schematically showing a second embodiment of the present invention.

FIG. 6 is a circuit diagram of the second embodiment.

FIG. 7 is a perspective view schematically showing a modification of the second embodiment.

FIG. 8 is a perspective view schematically showing a third embodiment of the present invention.

FIG. 9 is a circuit diagram of the third embodiment.

FIG. 10 is a perspective view schematically showing a first conventional example.

FIG. 11 is a perspective view schematically showing a second conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1A, 1B, 1C Breakage detecting device 10 Rotary cutting blade 11 Rotary drive shaft 12 Substrate 13 Blade body 14 Metal thin film 15 Disc body 16 First loop coil 17 Clock signal generator 18 Breakage detection switch 21 Second loop coil 22 Support arm REFERENCE SIGNS LIST 23 switch 24 oscillation circuit 25 echo back detection means 31, 32 coil 41 drive coil 42 detection coil 43 AC signal source 44 signal detection means 51 power generation coil 53 transmission circuit 61 a, 61 b magnet 62 reception circuit

Claims (9)

[Claims] 1. A damage detection device for a rotary cutting blade including a blade body made of an electrically insulating material fixed to a rotary drive shaft, wherein the rotary blade is coaxially held on the rotary drive shaft side so as to rotate together with the rotary drive shaft. A first loop coil on the rotating side,
A fixed-side second loop coil disposed concentrically with respect to the first loop coil, wherein the first loop coil is formed of a metal thin film formed along a cutting edge line of the blade body. A damage detection switch is connected to clock signal generation means including a crystal oscillator, and the second loop coil includes an oscillation circuit having an oscillation frequency substantially equal to the resonance frequency of the clock signal generation means, and an echo circuit. A damage detection device for a rotary cutting blade, wherein the back detection means is alternately connected to the back detection means via a switch means. 2. In a case where the number of blades is plural,
2. The damage detection device for a rotary cutting blade according to claim 1, wherein the damage detection switch provided on each of them is connected in series to the first loop coil. 3. When the number of the blades is plural,
The damage detection switches provided in each of the damage detection switches are connected in parallel to the first loop coil, and the clock signal generation means having different resonance frequencies are connected in series to the respective damage detection switches. 2. The damage detection device for a rotary cutting blade according to claim 1, wherein the oscillation frequency of the oscillation circuit is sequentially switched to the resonance frequency of each of the clock signal generation means each time the switching means is switched. 4. A damage detection device for a rotary cutting blade including a blade body made of an electrically insulating material fixed to a rotary drive shaft, wherein the rotary side attached to the rotary drive shaft so as to rotate with the rotary drive shaft. First and second coils of
A drive coil having an AC signal source supported by a fixed-side support means so as to face each of the rotation-side coils, and a detection coil connected to the signal detection means, wherein the first and second coils are: A damage detection device for a rotary cutting blade, which is connected to each other via a damage detection switch made of a metal thin film formed along a cutting edge line of the blade body. 5. The first and second coils are symmetrically arranged around the rotation drive shaft, and the drive coil and the detection coil are also symmetrically arranged around the rotation drive shaft. The damage detection device for a rotary cutting blade according to claim 4. 6. The rotary cutting blade according to claim 4, wherein said first and second coils are arranged at positions overlapping each other, and said drive coil and said detection coil are also arranged at positions overlapping each other. Breakage detection device. 7. A damage detection device for a rotary cutting blade including a blade body made of an electrically insulating material fixed to a rotary drive shaft, wherein the generator coil is attached to the rotary drive shaft so as to rotate with the rotary drive shaft. And a signal generating means driven by the power generating coil, and a magnet supported on the fixed side supporting means to surround the power generating coil and a signal receiving means on the fixed side, and the power generating coil and the signal generating means A damage detection switch made of a metal thin film formed along a cutting edge line of the blade body is connected between the two. 8. An apparatus according to claim 7, wherein said signal generating means is a light emitting element, and said signal receiving means is a light receiving element. 9. The damage detection device for a rotary cutting blade according to claim 7, wherein said signal generating means is a wireless signal transmitting circuit, and said signal receiving means is a wireless signal receiving circuit.