JPH06118006A - Defect detector - Google Patents

Abstract

PURPOSE:To classify distinct surface abnormalities due to carbide on inspected materials or due to water drops to allow the detection of specific surface abnormalities only as defects. CONSTITUTION:A defect detector 10 comprises the defect detecting part 12 which consists of a reference value setting means 31 for signals, an unsteady state detecting means 32 to detect the unsteadly state of the surface based on a shift from a reference value, a signal storing means 33 to store signals and a waveform classifying means 34 to classify surface abnormalities in accordance with the shape of waveforms.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect detecting device for detecting defects such as pipes.

[0002]

2. Description of the Related Art As a device for detecting a surface defect of a cable or the like, in addition to an image processing system using a general-purpose area sensor, there is also a "cable surface defect detector (FM88, FM44)" manufactured by Takikawa Engineering Co., Ltd. ) ” In this device, light is projected onto the surface of the cable, the diffused reflected light is received by the photocell through the lens system, the light amount difference of the slit photocell is converted into an electric signal, and the signal is full-wave rectified and then compared with the threshold value. Therefore, the surface abnormality is detected.

[0003]

In the above defect detecting apparatus, in addition to defects such as carbides that are mixed in during the extrusion process of pipes, defects such as water drops and white powdery debris of molded products that fall off when wiped off. Other surface abnormalities will also be detected as defects.

An object of the present invention is to classify the difference between a surface abnormality such as a carbide and a surface abnormality such as a water droplet of an object to be inspected so that only a specific surface abnormality can be detected as a defect. To do.

[0005]

According to the present invention, there is provided a signal input section having a plurality of means for receiving the reflected light from the surface of the object to be inspected and a means for converting the received light amount into an electric signal, and a signal from the signal input section. A defect detection device comprising a defect detection unit for detecting surface non-stationarity and for detecting a defect of an object to be inspected, wherein the defect detection unit includes a reference value setting means for a signal and a displacement from the reference value. Originally, it comprises non-stationarity detection means for detecting surface non-stationarity, signal storage means for storing signals, and waveform classification means for classifying surface abnormalities based on the shape of the signal waveform.

[0006]

In the present invention, the electric signal representing the difference in light quantity is not subjected to full-wave rectification, positive and negative information is stored, and the surface abnormality detected by comparing the magnitude of the signal with a threshold value is detected. Only the carbide is detected as a defect by classifying the difference between the surface abnormality such as a carbide having a low concentration and the surface abnormality such as a water droplet having a high concentration with respect to the concentration of the object to be inspected according to the shape of the waveform.

[0007]

1 is a block diagram showing an example of a defect detecting device, FIG. 2 is a schematic diagram showing an outline of the defect detecting device, and FIG. 3 is a schematic diagram showing output waveforms of respective parts of the defect detecting device.

As shown in FIG. 1, the defect detection device 10 has a signal input section 11, a defect detection section 12, and an output section 13.

The signal input section 11 has a plurality of sets of light receiving means 21 for receiving the reflected light from the surface of the object to be inspected and signal converting means 22 for converting the amount of light received by the light receiving means 21 into an electric signal.

The defect detection unit 12 detects the non-stationarity of the surface by the signal from the signal input unit 11 and detects the defect of the inspection object.

At this time, the defect detecting section 12 includes a signal reference value setting means 31, a non-stationarity detecting means 32 for detecting surface non-stationarity based on a displacement from the reference value, and a signal storage for storing signals. Means 33, waveform classification means 34 for classifying surface abnormalities based on the shape of the signal waveform.

FIG. 2 shows an outline of the defect detection device 10. When light is projected onto the pipe surface and the diffused reflected light is received by the photocell through the lens system and the light quantity of the slit-shaped photocell is converted into an electrical signal, the signal corresponding to the concentration of the surface abnormality is slit as shown in Fig. 3 (left). It is obtained with the time difference corresponding to the interval. By passing this through a differential circuit, a waveform as shown in FIG. 3 (right) with reference to the density of the inspection object is obtained. This signal is held by the signal storage means, and a surface abnormality is detected by comparing with a two positive and negative threshold values (broken line in the figure) prepared in advance in consideration of the time difference corresponding to the slit interval, and the range is determined. , The relevant part of the stored signal is classified by a waveform classification means such as a neural network,
Only surface anomalies corresponding to carbides are determined to be defects.

The operation of this embodiment will be described below.
According to this embodiment, light is projected onto the surface of the object to be inspected, the diffused reflected light is received by the photocell through the lens system, the light quantity difference of the slit-shaped photocell is converted into an electric signal, and an electric signal representing the light quantity difference is generated. Stores positive and negative information without full-wave rectification, and for surface anomalies detected by comparing the signal magnitude with a threshold value, defects are determined by the waveform shape, so the concentration of the inspected object is used as a reference. Since it is possible to classify different surface anomalies with different concentrations and even subtle differences in surface anomalies that appear as differences in waveform, it is possible to quickly detect only carbides as defects without detecting other surface anomalies as defects. can do.

[0014]

As described above, according to the present invention, the difference between the surface abnormality such as carbide of the object to be inspected and the surface abnormality such as water droplet is classified, and only the specific surface abnormality is regarded as a defect. It can be detectable.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a defect detection apparatus.

FIG. 2 is a schematic diagram showing an outline of a defect detection device.

FIG. 3 is a schematic diagram showing an output waveform of each part of the defect detection apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Defect detection device 11 Signal input part 12 Defect detection part 21 Light receiving means 22 Signal conversion means 31 Reference value setting means 32 Unsteadiness detection means 33 Signal storage means 34 Waveform classification means

Claims (1)

[Claims] 1. A signal input section having a plurality of means for receiving the reflected light from the surface of the object to be inspected and a means for converting the amount of received light into an electric signal, and the non-stationarity of the surface is detected by the signal from the signal input section. A defect detection apparatus comprising a defect detection unit for detecting a defect of an object to be inspected, wherein the defect detection unit is a signal reference value setting means, and a surface non-stationary property based on a displacement from the reference value. A defect detecting apparatus comprising: a non-stationarity detecting unit for detecting a signal, a signal storing unit for storing a signal, and a waveform classifying unit for classifying a surface abnormality based on a shape of a signal waveform.