JP2573517Y2 - Breakage detector - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breakage detecting device, and more particularly to an improvement of a breakage detecting device for detecting damage such as deformation or breakage of a jig or a machine tool.

[0002]

2. Description of the Related Art In a solid, elastic energy is released when the solid is deformed or broken, and a specific acoustic pulse mainly composed of elastic ultrasonic waves of about 10 KHz to 2 MHz is generated and propagated. This phenomenon is generally called an Acoustic Emission (AE) phenomenon. There has been proposed a breakage detecting device that detects breakage of a machine element of a machine tool such as a jig such as a cutting tool, a bearing, and a rotating shaft using the AE phenomenon.

Conventionally, this type of breakage detection device compares a measurement signal obtained from a measurement sensor attached to a cutting tool with a predetermined reference level, which is not shown in the drawings, and determines the reference level. If the measurement signal A exceeds the reference level B due to deformation or destruction, for example, by setting an appropriate reference level B as shown in FIG. The alarm signal C is configured to be output assuming that damage has occurred, such as breakage or breakage. However, in an actual damage detection device, as shown in FIG. 6, the number of times that the measurement signal A exceeds the reference level B (n1) as shown in FIG. , N2, n3, n4, ...)
Is added, and an alarm signal can be output when a predetermined number of times is reached, or the time (t1, t2, t3, t4,...) When the measurement signal A exceeds the reference level B as shown in FIG. It is configured to output a warning signal when the addition reaches a predetermined integration time, or output a warning signal when both the number of times of integration and the integration time have been reached.

[0004]

However, since the reference level B is generally different for each object to be measured, the above-described breakage detecting device sets and measures, for example, a reference level B once for a certain cutting tool, and then performs another measurement. In order to measure a cutting tool, accurate measurement cannot be ensured unless the reference level B is reset from the outside, and it is necessary to check an appropriate reference level B for each workpiece in advance and set it each time. Therefore, setting the reference level B requires a lot of trouble and is complicated. In addition, the level of the measurement signal from the device under test is not constant during normal operation or use as shown in FIGS. 5 to 7 and varies. May be measured, and accurate detection of breakage may be difficult even if the reference level of the measured object itself is known.

As a result of detailed comparison of the ultrasonic signals generated from various objects to be measured at the time of breakage, the inventor found that the level of the ultrasonic signals generated from the object under normal operation or use changed to some extent. The present invention was completed by focusing on the fact that these changing measurement signals can be used as reference levels. The present invention has been made under such a circumstance, and it is possible to automatically set a damage reference level corresponding to an object to be measured for detecting a damage state, and to provide a breakage detection device which is easy to handle. Aim.

[0006]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention provides a measuring sensor which is connected to an object to be measured and converts ultrasonic waves generated and propagated when the object to be measured is deformed or destroyed into an electric signal. A sampling unit that samples a measurement signal from the measurement sensor at a predetermined sampling cycle; a storage unit that sequentially stores and sets the sampling signal from the sampling unit as a reference level signal; A setting section for setting an object damage detection operation, and a storage control for controlling storage of the reference level signal in a storage section when the reference level is set by the setting section and controlling reading of the reference level signal when the damage detection operation is set Section, a reference level signal read by the storage control section, a measurement signal from the measurement sensor, and a start timing. A comparator for outputting an instruction signal when the measured signal by sequentially comparing together exceeds the reference level signal,
And a breakage detection unit for detecting deformation or destruction of the measured object when the instruction signal from the comparison unit exceeds a predetermined amount.

[0007]

In the present invention having such means, when the reference level setting operation is set by the setting section, the measurement signals sampled by the sampling section are sequentially stored in the storage section by the storage control section as reference level signals. Then, a reference level signal is set. When the damage detection operation is set by the setting unit, the reference level signal previously stored in the storage unit is read out by the storage control unit and added to the comparison unit. The measurement signal is sequentially compared with the start timing, and an indication signal is output when the measurement signal exceeds the reference level signal, and when the indication signal from the comparison section exceeds a predetermined amount, the damage detection unit outputs the instruction signal. Detects deformation or destruction of

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the damage detection device according to the present invention. In FIG. 1, the measurement sensor 1 is
For example, 10K that is connected by being attached to the surface of an object to be measured, for example, a cutting tool (not shown), and propagates the cutting tool.
It converts an ultrasonic wave of about Hz to 2 MHz into an analog measurement signal, and has a known configuration in which a detection electrode is formed on a facing surface of a piezoelectric ceramic plate. In addition, since the ultrasonic wave generated when the solid is deformed or broken has a peak at a frequency around 200 KHz, it is preferable that the measurement sensor 1 also has a configuration in which the sensitivity around this is enhanced.

The sampling section 3 performs A / D conversion of an analog measurement signal into a digital signal and performs sampling at a sampling period of, for example, 10 msec (0.01 sec), and is connected to the storage control section 5. The setting of the sampling cycle is changed by the setting unit 11 described later. The storage control unit 5 sequentially stores the sampled measurement signals as a reference level signal in the storage unit 7 and controls the setting, while repeatedly reading out the stored reference level signal and controlling the output to the comparison unit 9. . Storage control unit 5
Has a function of raising the level of the entire reference level signal after reading and outputting the signal to the comparison unit 9. Note that a configuration in which the reference level signal before storage is increased and stored in the storage unit 7 is also possible.

The storage section 7 is a non-volatile memory capable of storing a reference level signal in a readable and writable manner, for example, an EEP-ROM, but may be a power-backed-up RAM. The setting unit 11 externally sets and changes the sampling period by the sampling unit 3 and switches between the reference level setting (setting mode) and the damage detection operation (measurement mode), and stores the setting when the reference level is set (setting mode). The control unit 5 controls the storage of the reference level signal in the storage unit 7,
In addition to controlling the reading of the reference level signal stored during the damage detection operation (measurement mode), the switch has a setting function to be described later, and can be set externally. The comparing unit 9 sequentially compares the reference level signal from the storage control unit 5 and the measurement signal from the measurement sensor 1, and outputs an instruction signal to the damage detection unit 13 when the measurement signal exceeds the reference level signal. .

Generally, the level of the reference level signal read out by the storage control unit 5 and the measurement signal from the measurement sensor 1 always change with time, so that the measurement is performed at the same start timing as the setting start of the reference level signal. It is necessary to compare the measurement signals taken from the sensor 1. For example, when detecting a broken state of a cutting tool attached to a machine tool, when a reference level is set (setting mode), a measurement signal for a certain period from the start of the machine tool or from a time when the cutting tool advances to a certain position after the start. Is set as a reference level signal, and the measurement signal of the cutting tool is compared with the reference level at the time of starting the machine tool or at the time when the cutting tool advances to the same position after the start even during the damage detection operation (measurement mode).

From the viewpoint of ensuring accurate comparison, when the cutting tool advances to a predetermined position, for example, a known microswitch is turned ON, and a measurement signal is taken in accordance with the measurement start detection operation by this ON operation, and a reference level is read. It is better to make settings and compare signals. When the instruction signal from the comparing section 9 exceeds a predetermined amount, the damage detecting section 13 detects deformation or destruction of the measured object and outputs it to a display section not shown in FIG.

As shown in FIGS. 6 and 7 described above, the breakage detecting unit 13 determines that the object to be measured is broken or deformed when the integrated number of appearance times of the instruction signal reaches a predetermined set number, When the integration time of the output time of the instruction signal reaches the set time, it is determined that the DUT is destroyed or deformed, or when both the integration count and the integration time reach the set number or the set time, the DUT It has the function of judging that it is destruction or deformation and outputting the judgment result. The number of times of integration and the integration time are set by the setting unit 11.

FIG. 2 is a block diagram more specifically showing the configuration of the above-described damage detection device. The measurement sensor 1 includes an A / D conversion circuit 17 and a comparison unit 9 via an amplification circuit 15.
Are connected to one input terminal of each of the OP amplifiers 19 and 21 which form the. Note that the amplifier circuit 15 is not essential. A /
The D conversion circuit 17 converts the analog measurement signal from the measurement sensor 1 amplified by the amplification circuit 15 into a control circuit 23 described later.
The A / D conversion is performed by sampling under the management of the above, and a digital measurement signal is output to the control circuit 23.

The control circuit 23 comprises a main part of a so-called computer having a CPU 23a serving as a main body of an arithmetic function and a comparison / determination function, a ROM 23b storing an operation program of the CPU 23a, and an interface I / O 23c. The circuit 25, the setting circuit 27, the OP amplifiers 19 and 21, the D / A conversion circuits 29 and 31, the output circuit 33, and the display circuit 35 are connected. This control circuit 2
The operation function of No. 3 will be described later. The storage circuit 25 includes the control circuit 2
3 under the control of EEP- 3 functioning as the storage unit 7 of FIG.
ROM. The storage time (the number of data) of the reference level signal is determined by the storage capacity of the storage circuit 25.

The setting circuit 27 is formed by a mechanical changeover switch or the like which can be set from the outside, and functions as the setting unit 11 in FIG. 1 under the control of the control circuit 23. That is, the setting and change of the sampling cycle, the setting of switching between the reference level setting (setting mode) and the damage detection operation (measurement mode), and the setting and change of the number of integrations and the integration time are externally input. Are stored in the storage circuit 25 under the control of the control circuit 23.

In a situation where the reference level setting (setting mode) is set by the setting circuit 27, the control circuit 23
The digital measurement signal from the A / D conversion circuit 17 is averaged at a predetermined sampling period, and the average is calculated and stored as a reference level signal in the storage circuit 25. On the other hand, the damage detection operation (measurement mode) is performed by the setting circuit 27. Under the set condition, the reference level signal stored in advance is repeatedly read out from the storage circuit 25, and the D / A conversion circuits 29 and 3 are read.
1 and functions as the storage control unit 5 in FIG. The control circuit 23 samples the digital measurement signal from the A / D conversion circuit 17 at a predetermined sampling period, and averages the sampling signals for a plurality of periods with a sampling signal for several tens of seconds as one period. Thus, the reference level signal can be configured.

The sampling period for sampling by the control circuit 23 is, for example, 10 ms (0.01 s) as described above.
ec) is set by the setting circuit 27, and this sampling cycle can be arbitrarily changed. However, the sampling time, in other words, the number of samples (the number of data) changes according to the storage capacity of the storage circuit 25. That is, when the sampling period is reduced, the sampling time is reduced. For example, 2K
When a sampling period of 10 ms is set using the byte storage circuit 25, a reference level signal of about 20 seconds is stored in the storage circuit 25.

FIG. 3 is a diagram showing the relationship between the measurement signal A and the sampling period T in the control circuit 23. The D / A conversion circuit 29 D / A converts the reference level signal from the control circuit 23 into an analog reference level signal and raises the level (for example, increases the reference level signal before storage by 20 to 30%). The first reference level signal is output to the other input terminal of the OP amplifier 19, and the D / A conversion circuit 31 performs D / A conversion of the same reference level signal and raises the same at a lower level than the first reference level signal. The second reference level signal for deformation detection is output to the other input terminal of the OP amplifier 21. That is, these D / A
The conversion circuits 29 and 31 together with the control circuit 23 form the storage control unit 5 of FIG.

In the configuration in which the reference level signal is leveled up and stored in the storage circuit 25, the control circuit 23 performs an amplification operation and stores it in the storage circuit 25. In this case, these D / A conversion circuits 29 and 31 are OP amplifier 1
It is considered that the comparison part 9 of FIG. The OP amplifier 19 compares the measured analog signal from the measurement sensor 1 via the amplifier circuit 15 with the first reference level signal, and when the measured analog signal exceeds the first reference level signal, sends a first instruction signal to the control circuit. The OP amplifier 21 outputs the measured analog signal to the second
And outputs a second instruction signal to the control circuit 23 when the measured analog signal exceeds the second reference level signal.

In order to compare the measured analog signal with the first and second reference level signals at the same comparison start timing in the OP amplifiers 19 and 21, the measurement is started near the cutting tool (not shown). By inputting a start signal from the microswitch 37 as a detection unit,
The control circuit 23 stores the reference level signal in the storage circuit 25, while the control circuit 23 reads the reference level signal from the storage circuit 25. Instead of providing the microswitch 37, for example, the control circuit 23 stores the reference level signal in the storage circuit 25 in accordance with the start of the acquisition of the measured analog signal detected via the A / D conversion circuit 17, while reading it out similarly. Configurations are also possible.

In the damage detection operation (measurement mode), the control circuit 23 determines that the object to be measured has been destroyed when both the number of times and the time of integration of the first instruction signal have reached the predetermined set number and time. It has a function of judging, outputting a signal to that effect to the output circuit 33, and turning on a destruction alarm lamp (not shown) of the display unit 35. Control circuit 23
Determines that the device under test is deformed when both the number of integrations and the integration time of the second instruction signal reach the set number and the set time, outputs a signal to that effect to the output circuit 33, and displays the signal. It has a function of turning on a deformation alarm lamp (not shown) of the unit 35. That is, the control circuit 23 functions as the damage detection unit 13 in FIG.

The control circuit 23 operates so as to determine that the object to be measured has been destroyed or deformed when either the number of times of integration of the first and second instruction signals or the integration time has reached the set number or time. These can be arbitrarily set by the setting circuit 27. In addition, a configuration in which only one type of reference level signal and one instruction signal are compared is possible, and in this configuration, the D / A conversion circuit 31 and the OP amplifier 21 are not required. FIG. 4 is a diagram showing the relationship between the measurement signal A and one type of reference level b. When the measurement signal A exceeds the reference level b, an instruction signal is output from the OP amplifier 19 to the control circuit 23.

Reference numeral 39 in FIG. 2 denotes a level meter for displaying a bar graph of the measurement signal from the measurement sensor 1 and the first and second reference level signals from the D / A conversion circuits 29 and 31, and a changeover switch SW. Connected to them through but is not a mandatory requirement. In the damage detection device configured as described above, when the reference level is set (setting mode), the measurement signals of the device under normal operation are sampled and sequentially stored as the reference level signal, and the damage detection operation (measurement mode) Sometimes, the previously stored reference level signal is sequentially and repeatedly read and compared with the measurement signal from the measurement sensor 1 at the same start timing.
By obtaining a measurement signal of the object under normal operation, a damage reference level can be set. By comparing the reference level with the measurement signal, it is possible to detect the destruction or deformation of the object.

Therefore, it is not necessary to check the reference level in advance for each object to be measured for detecting a damaged state such as destruction or deformation, and it is possible to automatically set the damage reference level for each object to be measured, facilitating the setting operation. The handling becomes simple. Moreover,
Even if the measurement signal from the device under test changes, it can be set as a reference level, so that damage detection on a wide range of devices under test is easy.

[0026]

As described above, in the present invention, the measurement signals of the device under test which are operating normally in the setting mode are sequentially stored for a predetermined period as a reference level, and are stored and stored in the measurement mode. Since the reference level and the measurement signal from the measurement sensor are compared at the same start timing, the reference level is automatically set by storing the measurement signal of the device under test during normal operation. Therefore, an appropriate damage reference level according to the DUT for which the damage state is detected can be easily and automatically set, and even if the DUT is changed, the measurement can be performed by storing the measurement signal as the reference level in the same manner, There is an advantage that damage detection of various objects to be measured is simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a damage detection device according to the present invention.

FIG. 2 is a block diagram specifically showing a configuration of the damage detection device of FIG.

FIG. 3 is a waveform diagram illustrating an operation of the damage detection device of FIG.

FIG. 4 is a waveform diagram illustrating an operation of the damage detection device of FIG.

FIG. 5 is a waveform diagram illustrating the operation of a conventional damage detection device.

FIG. 6 is a waveform diagram illustrating the operation of a conventional damage detection device.

FIG. 7 is a waveform diagram illustrating the operation of a conventional damage detection device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 measurement sensor 3 sampling unit 5 storage control unit 7 storage unit 9 comparison unit 11 setting unit 13 breakage detection unit 15 amplification circuit 17 A / D conversion circuit 19, 21 OP amplifier (comparison unit) 23 control circuit (sampling unit, storage control) Section, damage detection section) 23a CPU 23b ROM 23c interface (I / O) 25 storage circuit (storage section) 27 setting circuit (setting section) 29, 31 D / A conversion circuit 33 output circuit 35 display circuit 37 micro switch (measurement) Start) 39 level meter

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23Q 17/09 G01N 29/14

Claims (1)

(57) [Scope of request for utility model registration] 1. A measuring sensor connected to an object to be measured and converting an ultrasonic wave generated and propagated when the object to be measured is deformed or destroyed into an electric signal, and a measuring signal from the measuring sensor is sampled at a predetermined sampling cycle. A sampling unit; a storage unit for sequentially storing and setting a sampling signal from the sampling unit as a reference level signal; a setting unit for setting at least a reference level setting operation and a damage detection operation for the device under test; A storage control unit that controls storage of the reference level signal in the storage unit when a reference level is set, and controls reading of the reference level signal from the storage unit during the damage detection operation; The reference level signal and the measurement signal from the measurement sensor at the time of the damage detection operation and the start timing are sequentially matched. A comparison unit that outputs an instruction signal when the signal exceeds the reference level signal, and a damage detection unit that detects deformation or destruction of the device under test when the instruction signal from the comparison unit exceeds a predetermined amount. A damage detection device comprising: