JPH0618491A - Apparatus for detecting crack in component parts of construction machine - Google Patents

Abstract

PURPOSE:To detect cracking positions in component parts of a construction machine by using a method of detecting elastic waves radiated due to plastic deformation or cracking in spots being broken down i.e., so-called acoustic emission, to foresee cracks. CONSTITUTION:This apparatus is composed of at least three acoustic emission sensors mounted on respective component parts of a construction machine, a band-pass filter 14 for passing therethrough only a signal in a predetermined frequency region among respective detecting signals of the acoustic emission sensors, a main amplifier 15 for inputting the respective detecting signals passing through the band-pass filter 14 and detecting respective times when the detecting signal exceeds initially a predetermined threshold value, a wave memorizer 16 for figuring out a time difference between the respective time signals and an MPU 17 for figuring out positions of cracks according to the time difference signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crack detecting device for a hydraulic excavating machine component, and more particularly to a crack detecting device for a part where a fracture is about to occur, unlike a nondestructive inspection method for inspecting the existence of defects formed in the past. Hydraulic excavation that detects the location of cracks by using a so-called acoustic emission (hereinafter referred to as AE) method that predicts cracks by detecting elastic waves radiated due to plastic deformation and the occurrence of cracks The present invention relates to a crack detection device in a component of a construction machine such as a machine.

[0002]

2. Description of the Related Art In a construction machine such as a large hydraulic excavator working at a mine or a crushed stone site, the work rate at the site is greatly affected by the operating rate of the machine. There is a strong demand for preventative measures.
In particular, it is necessary to strictly check daily inspections for cracks in important parts such as booms, arms, and revoframes of large hydraulic excavators. Conventionally, a crack detection method in a component of a construction machine is a visual inspection method, a magnetic flaw detection method, or a penetrant flaw detection method in which a colored liquid with a small surface tension or a fluorescent liquid is applied by a spray or the like to penetrate into a defect. There is.

[0003]

However, among the crack detecting methods for the component parts of the construction machine, the visual crack detecting method is a boom, an arm, or a revolving robot in an environment with a lot of dust such as a mine or a crushed stone site. Parts exposed to the outside such as the frame are dirty with the dust, etc., so it is difficult to find and repair them in small cracks such as hair cracks. Cracks that had progressed to the stage where they could be confirmed could not be repaired at the work site, and in many cases they had to be stopped and forced to make full-scale repairs. Therefore, not only the work load on site decreases significantly due to the decrease in the operating rate of construction machinery, but also cracks that have progressed to the stage where they can be visually confirmed may break the boom, arm, revo frame, etc., leading to a serious accident. There was a problem. Further, the magnetic flaw detection method or the penetrant flaw detection method is effective when the position of the crack is generally known, but particularly in a construction machine such as a large hydraulic excavator, there are many flaw detection points or flaw detection areas, It was almost impossible to apply the flaw detection method.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems in the prior art. Claim 1 discloses three or more acoustic emission sensors attached to each component of a construction machine. A band pass filter that passes only a signal within a predetermined frequency range among the detection signals of the acoustic emission sensor,
A main amplifier that inputs each of the detection signals that have passed through the bandpass filter, detects each time when the detection signal first exceeds a predetermined threshold, and a wave memoizer that calculates a time difference between the time signals. And an MPU that calculates the position of the crack based on the time difference signal. A second aspect of the present invention includes a main memory or an IC card that stores the position of the crack and the measurement time each time the position signal of each crack is detected by the MPU.

[0005]

According to the present invention, when a crack is generated at a predetermined position of each component of the construction machine or when the crack propagates, an AE wave which is a characteristic ultrasonic wave is generated from the crack portion. When each detection signal of the AE wave detected by three or more acoustic emission sensors attached to each component passes through a bandpass filter to remove noise and is input to the main amplifier, each detection signal is detected. When each time when the signal first exceeds a predetermined threshold is detected and each time signal is input to the wave memory, the time difference between the time signals is calculated, and the time difference signal is output to the MPU.
, The propagation speed of the AE wave has a predetermined value depending on the material, so the position of the crack in each component of the construction machine is calculated from each of the time difference signals. According to a second aspect of the present invention, each time the position of the crack in each component of the construction machine is detected by the MPU, the position signal of the crack and the measurement time are stored in the main memory or the IC card.

[0006]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 1 to 6 are views showing an embodiment of the present invention, FIG. 1 is a side view showing a hydraulic excavating machine to which a crack detecting device for a component of a construction machine is attached, and FIG. 2 of the construction machine shown in FIG. The figure which shows the detail of the crack detection apparatus in a component, FIGS. 3-6 is explanatory drawing of the crack position calculation method regarding the boom in FIG.

In FIG. 1, reference numeral 1 is a lower traveling body, 2 is an upper revolving body which is rotatably supported on the lower traveling body 1, and the upper revolving body 2 is a revo frame 3, a driver's cab 4, and a machine room 5. And 6 is a boom whose foot portion is pivotally supported by the revo frame 3, 7 is a boom cylinder for operating the boom 6, and 8 is an arm pivotally supported at the top portion of the boom 6.
Reference numeral 9 is an arm cylinder for operating the arm 8, 10 is a bucket pivotally supported on the top portion of the arm 8, and 11 is a bucket cylinder for operating the bucket 10. The above construction is the same as that of the conventional technique. .

In this embodiment, the case of detecting cracks in the revo frame 3, boom 6, and arm 8 will be described. Acoustic emission sensors (hereinafter referred to as AE sensors) Sr1 and Sr, which are piezoelectric elements made of lead zirconate titanate, are provided at predetermined three positions on the revo frame 3.
2, Sr3 are attached, and similarly, AE sensors Sb1, Sb2, Sb3 are mounted on the boom 6, and A is mounted on the arm 8.
E sensors Sa1, Sa2, Sa3 are attached to each of the AEs.
The sensors Sr1 to Sa3 have lead wires Hr1, Hr2, Hr3, Hb.
It is connected to the signal processing circuit 12 installed in the operator's cab via 1, Hb2, Hb3, Ha1, Ha2, Ha3. In addition,
Each of the AE sensors Sr1 to Sa3 and each of the lead wires Hr1 to
An appropriate protector may be attached to Ha3 to protect it from a stone or the like that collides from the outside, and each lead wire Hr1 to Ha3 may be connected by a slip ring at the pivotal support portion of the working machine. Therefore, the description is omitted.

Next, in FIG. 2, 13 is a preamplifier for amplifying the detection signal of ultrasonic waves detected by the AE sensors Sr1 to Sa3, which accompanies the generation of cracks, and 14 is ultrasonic waves generated by the generation of cracks. , A bandpass filter for removing noise other than the detection signal, 15 inputs each detection signal passed through the bandpass filter 14, and each detection signal first exceeds a predetermined threshold value c1, c2, c3 A main amplifier for detecting the time, 16 is a wave memory for calculating the time difference between the time signals from the main amplifier 15, 1
7 is an MPU that calculates the position of a crack from the time difference signal from the wave memoizer 16, 18 is a main memory that stores the position signal of the crack from the MPU 17, and a measurement time signal, and 19 is a crack from the main memory 18. 2 is an IC card for taking out the position signal and the measurement time signal, and 20 is a host processor for displaying the position signal of the crack of the IC card 19 and the measurement time signal.

Next, the operation of FIGS. 1 and 2 will be described with reference to FIG.
The boom 6 shown in FIG. 4 will be described as an example with reference to FIGS. When a crack is generated in the Z portion of the boom 6 shown in FIG. 3 or a crack already existing progresses, an AE wave which is a characteristic ultrasonic wave is generated from the crack portion Z, but the AE wave is a boom. 3 AE sensors Sb1, Sb2, S attached to 6
After being detected by b3, the detection signal is sent to each lead wire Hb1,
The AE wave, which is input to the preamplifier 13 of the signal processing circuit 12 installed in the operator's cab 4 via Hb2 and Hb3 and has a large attenuation due to the high frequency, is amplified by 40 to 60 dB. AE
The frequency band of waves is generally on the order of 100 KHz to 1 MHz, but the AE waves generated by cracks in steel materials are 100
Since the component of KHz to 300 KHz is large, only the detection signals in the frequency band are passed through the band pass filter 14, so that a stone collides with the boom 6 or a low frequency of 20 KHz or less generated by normal mechanical work or ,
Noise such as high frequency on the order of MHz generated in the control circuit is removed and only the AE wave is input to the main amplifier 15.

When a time at which each of the detection signals first exceeds each of the thresholds c1 to c3 set in the main amplifier 15 is detected and the time signals are input to the wave memoizer 16, the time signals are first detected. The time differences t1 and t2 with respect to the time signal are calculated. The time difference signals t1
, T2 are input to the MPU 17, the propagation speed of the AE wave is about 5000 m / s for longitudinal waves and about 3 for transverse waves in steel.
Since it is known that the time difference signals t1 and t2 are 000 m / s, the time difference signals t1 and t2 represent the difference between the distances from the cracks of the AE sensors Sb1, Sb2 and Sb3. Depending on t2, boom 6
The relative position of the crack with respect to each AE sensor Sb1, Sb2, Sb3 above can be calculated.

First, as shown in FIG. 4, the signals shown in FIG. 2 are detected at the positions of the three AE sensors Sb1, Sb2, Sb3 whose x and y coordinate positions are known, and the respective time difference signals are detected. Consider the case where t1 and t2 are calculated. Generally, the velocity of the AE wave propagating through the steel material is about 5000 (= a) m / s in the longitudinal wave at room temperature as described above.
Therefore, by multiplying the time difference signals t1, t2 at the positions of the AE sensors Sb1, Sb2, Sb3 by am / s, the difference in relative distance from the positions of the AE sensors Sb1, Sb2, Sb3 is at1. , at2.

As shown in FIG. 5, when circles C1 and C2 with radii at1 and at2 are drawn from Sb2 and Sb3, respectively, the circles A and
The distances to the E sensor Sb1 and the circles C1 and C2 should be equal. Therefore, as shown in FIG. 6, when a circle in contact with Sb1 and the circles C1 and C2 is drawn, the center of the circle is the crack position Z. The crack position Z calculated by the MPU 17 is stored in the main memory 18 together with the measurement time of the crack position Z each time. The preamplifier 13, the bandpass filter 14, the main amplifier 15, the wave memory 16, the MPU 17, and the main memory 18 constitute a signal processing circuit 12.

The crack P stored in the main memory 18
Position Z and the measurement time of the position Z of the crack are stored in the IC card 19, and the position signal of the crack and the measurement time signal stored in the IC card 19 are stored in the host processor 2
Since it is displayed as a crack generation frequency map on the boom 6 as shown in FIG. 3 by displaying 0, the crack generation portion Z is immediately visually recognized if the crack signal is generated by solidifying at a specific location. You can check.

[0015]

As described in detail above, according to the present invention, the following effects can be obtained. (1) Since it is possible to completely automate the inspection of cracks in the components of the construction machine, the inspection work can be saved and the operating rate of the hydraulic excavating machine can be significantly improved. (2) Even if the component parts of the construction machine are dirty due to dust, etc., they can be found and repaired in small cracks such as hair cracks because they are not visible, so the operation rate of the construction machine decreases and The work load is not significantly reduced, and it is possible to reliably prevent a serious accident in which a component of the construction machine is broken. (3) When developing a new model, it is necessary to detect in detail the cracks in each component of the construction machine from the viewpoint of safety, but this crack detection device can fully automate even small cracks such as hair cracks. Therefore, the number of test steps can be reduced because the detection can be performed reliably.

[Brief description of drawings]

FIG. 1 is a side view showing a hydraulic excavating machine equipped with a crack detection device in a component of a construction machine.

FIG. 2 is a diagram showing details of a control circuit of the crack detection device in the component parts of the construction machine shown in FIG.

3 is an explanatory diagram of a crack position calculation method for the boom of FIG. 1. FIG.

FIG. 4 is an explanatory diagram of a crack position calculation method for the boom shown in FIG. 1;

5 is an explanatory diagram of a crack position calculation method for the boom of FIG. 1. FIG.

FIG. 6 is an explanatory diagram of a crack position calculation method for the boom shown in FIG. 1;

[Explanation of symbols]

 1 Lower Traveling Body 2 Upper Revolving Body 3 Revo Frame 4 Operator's Room 5 Machine Room 6 Boom 7 Boom Cylinder 8 Arm 9 Arm Cylinder 10 Bucket 11 Bucket Cylinder 12 Signal Processing Circuit 13, Pre-Amplifier 14, Band Pass Filter 16, Wave Memorizer 17 MPU 18 Main memory 19 IC card 20 Host processor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Otsuka 3-1-1 Ueno, Hirakata-shi, Osaka Komatsu Ltd. Osaka factory

Claims (2)

[Claims] 1. Out of three or more acoustic emission sensors attached to each component of a construction machine and each detection signal of the acoustic emission sensor,
A bandpass filter that passes only a signal within a predetermined frequency range, and a main amplifier that inputs each of the detection signals that have passed through the bandpass filter and detects each time when the detection signal first exceeds a predetermined threshold value, A crack detecting device in a component of a construction machine, comprising: a wave memoizer for calculating a time difference between the time signals and an MPU for calculating a position of the crack based on the time difference signal. 2. A component of a construction machine, comprising: a main memory for storing the position of each crack and a measurement time each time the position signal of each crack is detected by the MPU, or an IC card. Crack detection device.