JPH04113256A - Impact type apparatus for detecting change in structure - Google Patents

Abstract

PURPOSE:To output a desired discrimination signal simply by an analog processing while reducing the number of components, by enabling execution of output corresponding to the amplitude of an output signal by inputting an output of an integration circuit to a plurality of comparators which have reference values being different in amplitude. CONSTITUTION:An impact force of a hammer 10 is conducted to a member 30 to be inspected, through a contactor 26, and a counter-force of impact is given to the contactor 26. When a signal V detected by a sensor 32 is inputted to a determination circuit 34, a noise part is cut off by a comparator 36 and a rectangular pulse signal V1 corresponding to the width of a waveform pulse is outputted therefrom. Moreover, this pulse signal V1 is inputted to an attenuator 38 and a rectangular pulse signal V2, attenuated so to be outputted with the sensitivity corresponding to the member 30 to be inspected is outputted therefrom. This signal V2 is integrated in an integration circuit 40, an integration signal V3 corresponding to the pulse width is compared with reference voltages V02 and V03 in comparators 42 and 44 and when these threshold values are exceeded, display means 46 and 48 are lighted.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an impact-type structural change detection device, and more particularly to a impact-type structural change detection device suitable for application to peel inspection of composite structures such as honeycomb plates, crack inspection of solid materials, and the like.

[Conventional technology]

Conventionally, when inspecting internal abnormalities in composite materials such as cracks occurring in a structure or separation between the surface material and core of a honeycomb structure, the surface of the structure is struck with a hammer, and the sound of this strike is used to detect Structures are inspected to see if they have cracks or peeling. This type of inspection method requires a high level of skill because it is determined based on the impact sound. Therefore, recently, a method has been proposed in which a sensor is attached to the hammer and the sensor detects the change in reaction force upon impact to inspect whether or not there is an abnormality in the structure. A striking structural change detection device that uses such a sensor as an inspection means attaches a sensor such as a piezoelectric element to a hammer head that directly strikes a structure, and while continuously striking the inspection surface, the sensor measures the impact reaction force. is detected, and structural abnormalities are determined based on this detection signal. Conventionally, this determination process uses a digital circuit to measure the time interval of impact reaction force pulses with a counter, and this count time is used to determine structural abnormalities.

[Invention or problem to be solved]

However, since the conventional impact type structural change detection device described above uses a digital circuit to determine structural abnormalities, it requires many parts and has the problem of being expensive. The present invention focuses on the above conventional problems and provides a low-cost percussion type structural change detection device that can easily output a desired discrimination signal through analog processing while reducing the number of parts. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the impact type structural change detection device according to the present invention inputs a waveform signal output from a force detection sensor or an acceleration detection sensor that is attached to a hammer for impact and detects signal changes accompanying impact. It is equipped with a comparator, a variable attenuator capable of attenuating the output of this comparator, and an integrating circuit that integrates the output signal of the attenuator, and the magnitude of the output of this integrating circuit is manually input to a plurality of comparators having different reference values. This makes it possible to output according to the magnitude of the output signal.

[Effect]

According to the above configuration, a waveform signal corresponding to the impact reaction force can be obtained from the sensor by one-timer impact, and this waveform signal is converted into a rectangular pulse signal by the comparator based on a predetermined reference value. This is attenuated by an attenuator according to the hardness of the object to be inspected, and the sensitivity is adjusted according to the object to be inspected. The output signal of the attenuator is input to the integrating circuit, where it rises at a predetermined slope depending on the rectangular pulse width. Since the magnitude of the rise in the slope of this output corresponds to the time interval of the rectangular pulse, by inputting this to each of multiple comparators having different reference values, each comparator can be adjusted according to the magnitude of the rising signal. Therefore, by using multiple LEDs that light up depending on the output of each comparator, it is possible to output power as an on/off signal from the The display can be made so that the number of lit LEDs changes.

[Embodiments] Specific embodiments of the impact type structural change detection device according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram of an impact type structural change detection device according to an embodiment. As shown, the device has a hammer 10 at the bottom end.
The hammer shaft 12 equipped with
is penetrated by a guide 16 formed in the center of the casing 14 and is movable up and down, and between the lower surface of the guide 16 and the stripe 10, and between the upper surface of the guide 16 and the plate 18 provided at the upper end of the shaft. They are each held in a suspended state by interposed springs 20. In order to apply a striking action to the hammer 10, a motor 22 is installed on the upper side of the casing 14, and a crank arm 24 is attached to this motor 22 so that it can be rotated. The rotation locus of the crank arm 24 is set so as to engage with the edge of the plate 18 provided at the upper end of the hammer shaft 12,
After the plate 18 is pushed up by the rotation of the crank arm 24, the engagement is released and the hammer 10 is caused to perform a striking action by the elastic force of the spring 20. Further, in this embodiment, the hammer 10 is configured to perform indirect tapping. That is, a contact 26 is placed in the lower part of the casing 14 surrounding the hammer 10 and faces the hammer 10 at a distance, and is held in place by a leaf spring 28 in the lower part of the casing 14. It is installed like this. The contact 26 is brought into direct contact with the member 30 to be inspected, and the hammer 10 hits the head of the contact 26. Therefore, the impact of the hammer 10 primarily acts on the contact 26,
It acts on the member to be inspected 30 through the contactor 26 . Here, the impact reaction force from the member to be inspected 30 is applied to the contact 26 by the impact of the hammer 10, but in order to detect this impact reaction force, the contact 26 is equipped with a sensor 32 having a piezoelectric element laminated thereon. It is provided. The sensor 32 is interposed in the middle of the contactor 26 and integrated, and the whole has a sandwich structure. The detection signal V of this sensor 32 is output to a determination circuit section 34. The determination circuit section 34 inputs the detection signal V of the sensor 32 and also inputs the fixed reference voltage (2). It has a comparator 36 that inputs . In the comparator 36, the waveform pulse signal due to the impact reaction force is used as a reference voltage V for removing noise signals. A rectangular pulse V having a width corresponding to the time T which is 1 or more is output. Additionally, an attenuator 3 is connected to the output side of the comparator 36.
8 is connected and the supply voltage level V. C (=VI)
The rectangular pulse signal is attenuated. This attenuation level v2 is variable, and is adjusted according to the elasticity, hardness, etc. of the surface of the object 30 to be inspected, thereby making it possible to adjust the display sensitivity. Further, an integrating circuit 40 is provided on the output side of the attenuator 38, which inputs a rectangular pulse signal v2 attenuated to a predetermined level and outputs a signal v3 whose output voltage is increased at a constant rate of increase from the rise of the pulse. It is intended to be output. As a result, the output voltage of the output signal (2) of the integrating circuit 40 increases at a constant rate during the pulse width of the human power signal (2), and thus the waveform pulse width T due to the impact reaction force. Therefore, it is possible to set a threshold value at a plurality of different levels for the level of this increased voltage (3), and determine the magnitude of the pulse width T based on whether or not the threshold value is exceeded. Therefore, first, the integrating circuit 40 is configured to discharge the charged voltage, and a plurality of comparators 42 and 44 are connected in parallel to the output side of the integrating circuit 40. One input terminal of each comparator 42,44 has a voltage V of different value. 2, V os (V 02 < V. 8) is input as a reference voltage, and the output signal V3 from the integrating circuit 40 is input to the other input terminal. As a result, the output signals of each comparator 42 and 44 are at the reference voltage V. 2. It remains on for the time that Vo8 is exceeded, and outputs the pulse signals v4 and ■5. A display means 46.48 such as a light emitting diode is connected to the output side of each comparator 42.44, and the corresponding display means 46.48 is turned on by outputting an ON signal. These display means may be arranged on the surface of the casing 14 so that the measuring person can easily see them. In the impact-type structural change detection device configured in this way, the hammer shaft 12 is reciprocated in the axial direction by driving the motor 22, and the hammer 1.0 at the lower end is moved toward the contact 26.
to hit. The contactor 26 is held by a leaf spring 28,
Since it is in contact with the member to be inspected 30, the striking force of the hammer 10 is transmitted to the member to be inspected 30 through the contactor 26,
A striking reaction force is applied to the contactor 26. Since a sensor 32 is attached to the contactor 26, the sensor 32 detects a waveform pulse signal V corresponding to the impact reaction force (FIG. 2A). By the way, when the measured member 30 is a composite material with a honeycomb core sandwiched between them as shown in FIG. 1 and a peeling test is performed, when the peeled part is hit, the spring constant of that part will be higher than that of other normal parts. Since the width T of the waveform pulse V becomes smaller, the width T of the waveform pulse V becomes larger. Therefore, the structural abnormality of the object to be inspected can be determined based on the magnitude of this pulse width T. Therefore, when the signal detected by the sensor 32 is input to the determination circuit 34, the noise part is first cut out by the comparator 36, and a rectangular pulse signal V corresponding to the width T of the waveform pulse is output (see Fig. 2). B). Furthermore, this pulse signal V1 is input to the attenuator 38, which outputs a rectangular pulse signal v2 that has been attenuated so as to be output with a sensitivity corresponding to the inspected member 30 (FIG. 2C). This signal v2 is integrated by an integrating circuit 40 and has a pulse width T
An integral signal v3 corresponding to the input pulse signal v2 is output (Fig. 2D), and by providing an appropriate discharge circuit, the level is attenuated at a predetermined slope from the falling point of the input pulse signal v2 as shown by the broken line in the figure, and the next By the time of the blow, ■2 is set to 0. Such integrated signals are input to a plurality of comparators 42,44, where respective reference voltages V. 2. They are compared with VO2, and when these thresholds are exceeded, the display means 46, 48 connected to their outputs are lit. By distinguishing the display colors of the light emitting diodes used as the display means 46 and 48, such as "red" for higher thresholds and "green" for lower thresholds, the measurer can detect abnormal conditions in the structure of the member 30 to be inspected. It becomes something that can be judged visually. In the inspection, first, while the normal part is being struck, the sensitivity of the attenuator 38 is adjusted so that the light emitting diode of the display means 48 becomes "green" (determined to be normal). Thereafter, when the inspection work begins, the "red" light emitting diode of the display means 46 lights up in the abnormal area, indicating that there is an abnormality. Another method may be to attach a scale to the attenuator 38 and set the attenuator value for each test object. According to such an embodiment, the signal width of the detection pulse corresponding to the impact reaction force can be determined only by analog processing, and the device can be inspected with a reduced number of parts for determination. Therefore, there is no need to use expensive digital circuit components to determine the pulse width, resulting in a very inexpensive inspection device. In particular, since the abnormality determination can be visually displayed and the abnormality can be determined using a simple color-coded display, no skill is required for the inspection. In this embodiment, the hammer is driven by a combination of a motor and a cam, but it may be driven by a solenoid and a spring, or a bidirectional solenoid. As for the tapping method, although an indirect tapping method is illustrated in this embodiment, a direct tapping method without the contactor 26 may be used. Effects of the Invention As described above, according to the present invention, a comparator receives a waveform signal output from a force detection sensor or an acceleration detection sensor attached to a striking hammer and detects signal changes accompanying striking; It is equipped with a variable attenuator that can attenuate the output of this comparator and an integrating circuit that integrates the output signal of the attenuator. Since it is possible to output according to the size, it is possible to reduce the number of parts and easily output a desired discrimination signal by analog processing.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an impact-type structural change detection device according to an embodiment, and FIG. 2 is an output waveform diagram of a determination circuit by the same device. 10... Hammer, 12... Hammer shaft, 22... Motor, 24... Crank arm, 26... Contact, 30...・・・・・・
・Member to be inspected, 32...Sensor, 34...
...Judgment circuit section, 36...Comparator, 38
...Attenuator, 40...Integrator circuit, 42.44...Comparator, 46.48
...Display means (light emitting diode). Agent Patent Attorney Tomo Murakami −

Claims (1)

[Claims] 1) A comparator that inputs a waveform signal output from a force detection sensor or an acceleration detection sensor that is attached to a striking hammer and detects signal changes accompanying striking, a variable attenuator that can attenuate the output of this comparator, and the attenuator. It is characterized by comprising an integrating circuit that integrates the output signal of the integrating circuit, and inputting the magnitude of the output of this integrating circuit to a plurality of comparators having different reference values, thereby making it possible to output according to the magnitude of the output signal. A percussion type structural change detection device.