JP2004069410A - Surface defect detection system and data processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface defect detection system using an economical device wherein a surface defect detection capability is improved. <P>SOLUTION: The surface defect detection system detects a defect on a surface of a long conductive rod 11 having a circular cross-section. The detection system includes devices 13 and 14 having a rotating feeder for moving the rod 11 to a predetermined direction while spirally rotating the rod 11, a plurality of sensors 15a and 15b provided oppositely to each other in a vicinity of a surface of the rod 11, an amplifier for amplifying a signal indicating a distance between the surface of the rod 11 and the sensors 15a and 15b and detected by the sensors 15a and 15b, and a personal computer inputting a signal output from the amplifier and determining the defect on the surface of the rod 11. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface defect detection system for detecting a surface defect of a cylindrical bar, such as a long rod, having a cylindrical cross section, and a data processing method in the system.
[0002]
[Prior art]
2. Description of the Related Art A conventional surface defect detecting apparatus is disclosed in Japanese Patent Application Laid-Open No. 61-243356.
This surface defect detection device has a configuration shown in FIG. 8, and detection ends 1, 2, 3, and 4 are provided around a rotor 5. Each of these detection ends is composed of an even number of detection coils 1A and 1B and one excitation coil 1E.
[0003]
The excitation coils are connected in series between the detection terminals, that is, 1E-2E-3E-4E. A plurality of detection coils in one detection end are similarly connected in series, such as 1A-2A-3A-4A and 1B-2B-3B-4B, respectively.
[0004]
The control unit 30 includes an oscillator 31, a power amplifier 32, a bridge circuit 33, an amplifier 34, a phase shifter 35, a phase detection circuit 36, a bandpass filter 37, and a wave height discrimination circuit 38.
[0005]
[Problems to be solved by the invention]
However, in the above configuration, since the probe circuits are connected in series, averaging of the output of the opposing probe is performed. Therefore, it is possible to remove the influence (noise) due to the change in the position of the subject. There is a problem that the signal level is lowered even by a surface defect (for example, when there are four probes, the signal level is reduced to 1/4).
[0006]
In addition, according to a general eddy current flaw detector, the apparatus becomes expensive, and an apparatus having a probe rotation mechanism and an object feed mechanism for inspecting the object, or rotating the object is required. A separate device with a feed mechanism was required.
[0007]
SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a surface defect detection system using an inexpensive device and a data processing method in the system, which can enhance the capability of detecting surface defects.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is a surface defect detection system that detects a defect on the surface of a long bar having a conductive shape with a circular cross section, wherein a rotary feed mechanism that advances the long bar in a predetermined direction while helically rotating the long bar. An apparatus having a plurality of sensors installed at opposing positions near the surface of the long bar, an amplifier for amplifying a signal of a distance between the surface of the long bar and the sensor detected by the sensor, and And a personal computer for determining a surface defect by inputting a signal output from the amplifier.
[0009]
According to a second aspect of the present invention, a plurality of sensors installed at opposing positions near the surface of the long bar are output by a surface defect detection system that detects a defect on the surface of the long bar having a conductive cross section. In a data processing method in a personal computer for processing signal data of the distance between the sensor and the surface of the long rod,
Synthesizing measurement data relating to the distance of the plurality of sensors to the surface of the elongated bar;
Removing low-frequency noise from the synthesized data by a high-frequency pass filter;
Determining whether or not the surface of the long bar has a defect based on whether or not the data from which the low-frequency noise has been removed exceeds a predetermined threshold value set in advance. Having.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing the entire surface defect detection system according to the present invention. 2 is an explanatory diagram when viewed from the AA direction in FIG. 1, and FIG. 3 is an explanatory diagram when viewed from the BB direction in FIG.
[0011]
First, a surface defect detection system 10 according to the present invention includes a guide rail 12 through which a long rod 11 having a circular cross section, which is an object to be inspected, and having conductivity is moved in the longitudinal direction. A rotating wheel 13 for polishing the surface of the rod, an adjusting wheel 14 which cooperates with the rotating wheel 13 to advance the long rod 11 while rotating it spirally, and is installed near the surface of the long rod 11. It has sensors 15a and 15b.
[0012]
Further, although not shown, an amplifier for amplifying a signal of the distance between the surface of the long bar 11 detected by the sensors 15a and 15b and the sensors 15a and 15b, and a signal output from the amplifier are input to the surface for inputting a signal. And a computer for determining whether or not there is a defect.
[0013]
Here, the mechanism in which the elongate rod 11 advances while spirally rotating is different from that in which the rotating wheel 13 contacts the side surface of the elongate rod 11 and polishes the surface, while applying a downward rotational force. The adjustment wheel 14 rotates while contacting the side surface of the long rod 11 obliquely, and applies an obliquely upward turning force. As a result, the long rod 11 is given a helical rotational force and travels while spirally rotating on the guide rail 12.
[0014]
Then, as shown in FIG. 2, a stand 17 is set on another table 16, and the left and right sensors 15a and 15b are mounted on the stand 17 at a close distance that does not make contact with the long bar 11 to be inspected. It is being done.
[0015]
As shown in FIG. 3, the guide rail 12 has a U-shaped cross section, and guides the long rod 11 between the rotating wheel 13 and the adjusting wheel 14.
[0016]
Next, a method for processing signal data of a detected surface defect portion will be described with reference to the flowchart of FIG. First, when there is a flaw on the surface of the long rod 11, when the eddy current type displacement meter is used as the sensors 15a and 15b, displacement and damage due to deflection of the long rod 11 to be inspected are caused. Displacement appears, and this signal is amplified by the amplifiers (amplifiers) 18a and 18b.
[0017]
Then, when this signal is taken into the personal computer 20 for data collection and processing, the A / D board 19 converts the analog signal into a digital signal.
[0018]
Next, the digital signals from the two sensors 15a, 15b are combined 21 by the personal computer 20.
[0019]
Further, after the flaw signal is made obvious by the high-frequency pass filter 22, discrimination 23 is performed based on whether or not the signal exceeds a preset threshold value, and the determination result 24 is displayed on the monitor. .
[0020]
5 to 7 are conceptual diagrams for explaining the signal processing method according to the present invention. The signal processing method according to the present invention will be described in more detail with reference to FIG. First, as shown in FIG. 5, assuming that the long rod 11 advances in the order of (a), (b), and (c) while rotating helically, as shown in FIG. One of the sensors 15b installed on both sides of the long bar 11 detects a scratch C on the surface of the long bar 11. Then, as shown in FIG. 6A, the flaw C appears as the detection 1 on the processing personal computer 20. Next, when the other sensor 15a detects the same flaw C as shown in FIG. 5B, the flaw C appears as detection 2 on the processing personal computer 20. Further, when the sensor 15b detects the same flaw C as shown in FIG. 5C, the flaw C appears as detection 3 on the processing personal computer 20.
[0021]
The detection data of the flaw C measured in this manner has an AC waveform as shown in FIG. Here, the portion D corresponding to the amplitude of the AC waveform mainly represents the amplitude due to the horizontal swing of the long rod 11 (the direction of the arrow E in FIG. 7).
[0022]
Therefore, as shown in FIG. 6B, by synthesizing the AC waveform data of the sensor 15a and the sensor 15b, the amplitude due to the horizontal swing of the long bar 11 is canceled out, and the data of the flaw C detected. Will become apparent. Here, the amplitude F of the AC waveform located below the data of the flaw C is mainly due to the vertical swing of the long rod 11 (the direction of arrow G in FIG. 7). The AC waveform having the amplitude F has a lower frequency than the signal of the flaw C, and is a signal that is unnecessary for flaw detection and is noise to be removed.
[0023]
Thus, data obtained by removing the low-frequency noise by a high-frequency pass filter from the data obtained by synthesizing the AC waveform data of the sensors 15a and 15b is the data shown in FIG. 6C. It will be revealed.
Further, since the above-described processing is performed, the amplitude H corresponding to the remaining noise becomes small, and the scratches and noise can be easily reduced by the preset threshold value (dotted line in FIG. 6C). Therefore, the measurement accuracy is improved.
[0024]
It goes without saying that various embodiments can be adopted without departing from the spirit of the present invention. For example, in the above embodiment, two sensors are used. However, the present invention is not limited to this, and the effects of the present invention can be achieved by installing an even number of sensors at opposing positions.
[0025]
Further, the sensor is not limited to the eddy current type displacement meter, and may use a laser or air as a detection principle.
[0026]
Furthermore, in the above embodiment, it is assumed that a cylindrical grinder already installed in a factory or the like is used, but the present invention is not limited to this, and a long rod is spirally rotated in a predetermined direction. Any device having a rotary feed mechanism for moving the device can be used in the present invention.
[0027]
【The invention's effect】
The invention according to claim 1 is a surface defect detection system that detects a defect on the surface of a long bar having a conductive shape with a circular cross section, wherein a rotary feed mechanism that advances the long bar in a predetermined direction while helically rotating the long bar. An apparatus having a plurality of sensors installed at opposing positions near the surface of the long bar, an amplifier for amplifying a signal of a distance between the surface of the long bar and the sensor detected by the sensor, and It is characterized by having a personal computer that determines a surface defect by inputting a signal output from an amplifier, so that if an eddy current displacement meter is used as a sensor, for example, an expensive Inspection can be performed, and if a cylindrical grinder has already been installed in the production line of the factory, it is not necessary to newly install a device having a rotary feed mechanism for flaw inspection, and the length of the work Can be performed, such rod polished at the same time of a contributing system in reducing manufacturing costs of the device.
[0028]
According to a second aspect of the present invention, a plurality of sensors installed at opposing positions near the surface of the long bar are output by a surface defect detection system that detects a defect on the surface of the long bar having a circular cross section and conductivity. In a data processing method in a personal computer for processing signal data of the distance between the sensor and the surface of the long rod,
Synthesizing measurement data relating to the distance of the plurality of sensors to the surface of the elongated bar;
Removing low-frequency noise from the synthesized data by a high-frequency pass filter;
Determining whether or not the surface of the long bar has a defect based on whether or not the data from which the low-frequency noise has been removed exceeds a predetermined threshold value set in advance. Therefore, this is a data processing method that can accurately detect surface defects by data processing on a computer despite being a simple device.
[Brief description of the drawings]
FIG. 1 is a plan view showing an entire surface defect detection system according to the present invention.
FIG. 2 is an explanatory diagram when viewed from an AA direction in FIG. 1;
FIG. 3 is an explanatory diagram when viewed from a BB direction in FIG. 1;
FIG. 4 is a flowchart showing processing of signal data.
FIG. 5 is a conceptual diagram illustrating a signal processing method according to the present invention.
FIG. 6 is a conceptual diagram illustrating a signal processing method according to the present invention.
FIG. 7 is a conceptual diagram illustrating a signal processing method according to the present invention.
FIG. 8 is an explanatory diagram showing a conventional surface defect detection method.
[Explanation of symbols]
Reference Signs List 10 Surface defect detection system 11 Long rod 12 Guide rail 13 Rotating wheel 14 Adjusting wheel 15a, 15b Sensor 16 Separate table 17 Stand 18a, 18b Amplifier 19 A / D board 20 Data collection / processing personal computer

Claims (2)

A surface defect detection system for detecting a defect on the surface of a long rod having a circular cross section and conductivity, comprising: a device having a rotary feed mechanism for moving the long rod in a predetermined direction while helically rotating the rod; A plurality of sensors installed at opposing positions near the surface of the long bar, an amplifier that amplifies a signal of the distance between the surface of the long bar detected by the sensor and the sensor, and a signal output from the amplifier. A personal computer for determining a surface defect by inputting the information. A surface defect detection system that detects a defect on the surface of a long bar having a circular cross section and conductivity, a plurality of sensors installed at opposing positions near the surface of the long bar outputs the long bar. In a data processing method in a personal computer that processes signal data of a distance between a surface and a sensor,
Synthesizing measurement data relating to the distance of the plurality of sensors to the surface of the elongated bar;
Removing low-frequency noise from the synthesized data by a high-frequency pass filter;
Determining whether or not the surface of the long bar has a defect based on whether or not the data from which the low-frequency noise has been removed exceeds a predetermined threshold value set in advance. A data processing method in a surface defect detection system.

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