JP2535257B2 - Strip surface defect inspection system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for efficiently detecting surface defects (defects) in a steel sheet strip manufactured by cold rolling.

[0002]

2. Description of the Related Art It is preferable that a steel sheet strip manufactured by cold rolling is subjected to a flaw inspection for quality assurance over substantially the entire surface. In practice, this flaw inspection thoroughly implements quality control. It is one of the important requirements above. As one of the flaw inspection methods, the surface of a strip running on a manufacturing line is scanned with a laser beam in the width direction, the reflected wave is converted into a voltage intensity by a photoelectric conversion element such as a CCD element, and the flaw is detected from this signal data. A method for determining the presence / absence of the above has already been established (see Japanese Patent Laid-Open No. 63-62825, etc.).

However, since such an optical flaw detection device cannot discriminate the degree and nature of the flaw, it is used as a preliminary inspection device, and the final judgment is a visual inspection. It is customary for the examiner to do this separately.

[0004]

By the way, in recent years, there is a tendency to increase the line speed in order to improve the productivity, but under the present circumstances, it is necessary to visually judge the final pass / fail judgment for the surface defect of the strip. In the quality control system, there is a limit to the improvement of the inspection accuracy and the improvement of the inspection speed, which is one of the factors that hinder the further increase of the line speed.

The present invention has been devised in order to eliminate such disadvantages of the prior art, and its main purpose is to improve the efficiency of the work of checking the flawed part by the inspector and improve the productivity. It is an object of the present invention to provide a surface defect inspection apparatus for a strip that can contribute to the above.

[0006]

The object is to provide a laser oscillating means, a photoelectric converting means for receiving the reflected light thereof and converting it into a voltage intensity, and a display for converting the voltage intensity into image data and displaying it on a screen. In the strip surface defect inspection device having a defect detection unit for determining a surface defect from the voltage intensity and a storage unit for storing the defect portion data determined by the defect detection unit , a defect detection unit is provided. From the comparison with the threshold
The one that uses the threshold method to determine the flaw and the one that determines the flaw from the feature amount
Multiple with different neural network method
And the storage means that meet the specified conditions.
Then, the signals from these flaw detection means are selectively stored.
It is achieved by shall be composed such that.

[0007]

According to this apparatus, the defect itself on the strip flowing in the line can be displayed as a still image to facilitate the inspection itself. In particular, the type and degree of defects, or
Multiple flaw inspections with different methods depending on steel grade and grade
By changing the signal from the output means,
To make it possible to identify defects more accurately and accurately.
It

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to specific embodiments shown in the accompanying drawings.

FIG. 1 shows the overall structure of the device of the present invention. The He—Ne laser projector 2 sweeps and irradiates a laser spot in the direction orthogonal to the transport direction, that is, the width direction of the strip 1, toward the surface of the steel strip 1 transported in the direction of the arrow F, and the reflected light thereof is For example, the light is received by the light receiver 3 including a photomultiplier. This converts the light intensity signal into a voltage intensity signal. This voltage intensity signal is processed by the voltage waveform generator 4 to obtain a voltage waveform, and one side is differentiated by the differentiating circuit 5 to obtain a differential waveform. Then, either one of the differential waveform and the voltage waveform is selectively input to the A / D converter 7 by the switch 6, and the data converted into the digital value here is input to the pre-trigger circuit 8. Since the degree of distinction between the differential waveform and the voltage waveform differs depending on the texture of the material, a more suitable signal is selected according to the coil information provided from the main computer 9 and the pre-trigger circuit 8 is selected. Is entered.

On the other hand, the differentiated waveform obtained by differentiating the voltage waveform is input to the threshold processing unit 10 on the one hand. Here, the presence or absence of a flaw on the strip surface is determined by comparison with a preset threshold value, and a trigger signal (defect detection signal) corresponding to the flaw type and its degree is output. On the other hand,
The A / D converter 11 converts the data into, for example, an 8-bit digital value, and from this data, the feature amount calculation circuit 12 outputs a plurality of feature amounts (for example, a normalized quadratic average and a normalized differential range 2
One) is calculated. Then, by inputting these into the neural network 13, the presence / absence of a flaw on the strip surface is similarly determined, and a trigger signal is output. A plurality of trigger signals output from the threshold processing unit 10 and the neural network 13 corresponding to the flaw type and its degree, that is, flaw detection signals are input to the trigger signal processing circuit 14.

In this way, by using the threshold value processing unit 10 and the neural network 13 together to determine the presence / absence of a flaw, the type and degree of the flaw can be discriminated with higher accuracy and fineness.

The trigger signal processing circuit 14 has a built-in logic for selecting the plurality of trigger signals in accordance with the steel type, grade, etc., and a plurality of triggers output from the threshold value processing unit 10 and the neural network 13. The signals are discriminated according to the coil information given from the main computer 9, and only when a predetermined trigger signal is input,
A trigger signal (data storage command) to the subsequent pre-trigger circuit 8 is output. As a result, defect data (output of differential waveform or voltage waveform) to be temporarily stored in the buffer memory built in the pre-trigger circuit 8 is selected. In addition, the welded portion of the strips is connected to the photoelectric tube 1
The signal detected in 5 and the output amount of the tachometer 17 attached to the hearth roll 16 are calculated by the calculator 18 and the strip feeding amount is input to the strobe signal generator 19, which causes the welded portion to be welded. By generating a proximity signal and inputting it to the trigger signal processing circuit 14, the flaw data in the vicinity of the welded portion is ignored.

The pre-trigger circuit 8 has a built-in buffer memory for sequentially recording a plurality of screens, and a trigger signal (data storage) from the trigger signal processing circuit 14 in order to place the defective portion in the center of the screen. Data before and after the output of (command) is also stored.

The data of the defective portion taken in the buffer memory is inputted to the memory control circuit 20. here,
Defect types and their priorities relating to their degree are preset in correspondence with the steel types, and only the data around the location where the trigger signal with the highest priority is output is extracted according to the coil information given from the main computer 9. It This processing is performed in order to deal with the fact that the type and degree of the defect in question differ depending on the customer, that is, the criteria of the degree of harm differ. Then, this data is stored in the image display control unit 21.
Is displayed on the CRT display 22 as a still image and is documented by the video printer 23 as needed.

On the other hand, in the memory control circuit 20, the display data is thinned out according to the strip passing speed, and the data density is adjusted. As a result, the size of the display image in the length direction is changed appropriately. At the same time, it is divided into a plurality of areas in the plate width direction, priorities are assigned according to the size of the flaws, and areas with large flaws are preferentially extracted. Thereby, when a plurality of flaws are arranged in parallel in the plate width direction, only the flaw having the highest degree of harmfulness is stored. Therefore, it is possible to reliably store only the required flaws without increasing the number of data and requiring an excessively large memory capacity or an excessively high processing speed.

The final flaw data thus obtained is recorded in an external storage device 25 such as a magnetic storage device together with coil information, position data on the strip, or operator intervention data from the keyboard 24, and verification data. Or as data for inspection records for customers.

[0017]

As described above, according to the present invention, it is possible to automatically select the flaws, which are considered to be particularly important , in the flawed portion on the strip and display them as a still image, so that the flawed portion can be confirmed. It is possible to ensure that the certifier can perform at a high speed. In particular, a plurality of flaw detection means having different characteristics from each other
In combination with these flaw detection signals to a predetermined preset
By switching to another according to the conditions,
Defects can be determined with stratified accuracy and high accuracy.
Therefore, there is a great effect in reducing the work load of the certifier and ensuring thorough quality control.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a surface defect inspection apparatus based on the present invention.

[Explanation of symbols]

 1 Strip 2 Emitter 3 Light Receiver 4 Voltage Waveform Generator 5 Differentiating Circuit 6 Switcher 7 A / D Converter 8 Pre-Trigger Circuit 9 Main Computer 10 Threshold Processing Unit 11 12 Feature Calculation Circuit 13 Neural Network 14 Trigger Signal Processing Circuit 15 Photoelectric Tube 16 Hearth Roll 17 Tachometer 18 Computing Machine 19 Strobe Signal Generator 20 Memory Control Circuit 21 Image Display Control Unit 22 CRT Display 23 Video Printer 24 Keyboard 25 External Storage Device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-56-114747 (JP, A) JP-A-2-74852 (JP, A) JP-A-61-245045 (JP, A) JP-A-54- 84785 (JP, A)

Claims (1)

(57) [Claims] 1. A laser oscillating means, a photoelectric converting means for receiving reflected light thereof and converting it into a voltage intensity, a display means for converting the voltage intensity into image data and displaying it on a screen, and a surface defect from the voltage intensity. A surface defect inspection apparatus for a strip, comprising: a defect detection unit that determines the defect, and a storage unit that stores the defect-portion data that is determined by the defect detection unit , wherein the defect detection unit is based on comparison with a threshold value. Threshold for determining defects
Neural network that distinguishes flaws from feature quantities
It also consists of multiple means with those using the network method.
And than, the storage unit, the plurality of Kizuken according to a predetermined condition
The signal from the output means is selectively stored.
An apparatus for inspecting a surface defect of a strip, characterized in that