JPH0721461B2 - Surface flaw inspection device for rolled material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface flaw inspection device for continuously inspecting a surface flaw of a rolled material produced by rolling a thick plate, a shaped steel or the like.

[Conventional technology]

A technique for continuously detecting flaws on the surface of an object by continuously photographing an object to be inspected with a solid-state imaging camera and analyzing an output signal thereof is well known and has been put into practical use.

[Problems to be Solved by the Invention]

When this method is applied to a surface flaw detection device for rolled material, there is a problem to be solved. It is a problem of the temperature distribution of rolled material. Immediately after rolling, the surface temperature of the steel material is not constant due to cooling conditions, heat radiation conditions such as TOP and MIDDLE position differences, heat conduction, steel material dimensions, and steel grade shapes. Therefore, a portion having a high surface temperature is bright, that is, the signal intensity is strong, and a portion having a low surface temperature is dark, that is, the signal intensity is weak, and a situation may occur in which a flaw is erroneously detected or fails to be detected.

In order to deal with this problem, it is conceivable to devise a cooling method for the steel surface so that the temperature of the surface to be inspected is constant, but it is difficult to always maintain a constant level of brightness, and cooling is also necessary. This is not good for the product.

Therefore, an object of the present invention is to provide a detection device capable of continuously detecting a flaw on the surface of a rolled material without the need for newly providing a cooling means for the detection.

[Means for Solving the Problems]

FIG. 1 is a principle block diagram of a surface flaw inspection apparatus for rolled material according to the present invention.

In the figure, the image pickup device 10 has a variable shutter speed according to an external signal, and continuously photographs the surface of the rolled material 30 and outputs an image signal. The flaw detection means 20 analyzes the image signal to detect flaws on the surface of the rolled material 30. On the other hand, the trimming means 14 takes out only the signal within a predetermined range of the image signal, the integrator 15 integrates the output, and the computing means 17 makes the output of the integrator 15 constant from the output from the integrator 15. Such an appropriate shutter speed is calculated and output to the image pickup device 10.

[Action]

By controlling the shutter speed so that the average brightness within a predetermined range is constant, even if there is a change in the temperature of the surface of the rolled material 30, a substantially constant brightness can be obtained regardless of the surface temperature. It is possible to detect flaws on the surface of the rolled material 30 without being affected by fluctuations.

〔Example〕

FIG. 2 is a block diagram showing an embodiment of the surface flaw inspection apparatus for rolled material according to the present invention. Further, FIG. 3 shows a range of a screen continuously photographed by the apparatus of FIG. 2 in a view of the rolled material 301 from directly above and an area trimmed for controlling the shutter speed.

In FIG. 2, the test material 301 rolled by the rolling mill is shown.
Is transported by a transport roll 302, and a solid-state image pickup camera 101 is attached at a position separated by an appropriate length above the transport roll 302, and the test material 301 of self (home) emitted from the test material 301 The surface image can be taken. 1
Reference numeral 02 denotes a controller of the solid-state imaging camera 101, which outputs an image signal for one frame (60, 60 ′ or 60 ″ in FIG. 3) and can input a signal for controlling the shutter speed. The image processing device 201 sends an image signal in the form of an analog signal to the monitor 202 and analyzes the image signal for one frame to detect the presence / absence of a flaw on the surface of the test material 301 and output the detected image. The signal is a trimming circuit
It is also sent to 141, where only signals corresponding to the shaded area in FIG. 3 are passed. The output of the trimming circuit 141 is integrated by the integrating circuit 151, amplified by the amplifier 171, and then compared by the comparator circuit 151.
The value is compared with a predetermined value at 172, and the result is amplified by the amplifier 173 and supplied to the controller 102 as a signal for controlling the shutter speed.

The circuits from the trimming circuit 141 to the amplifier 173 can also be realized by executing predetermined software on a computer of a normal stored program type.

〔The invention's effect〕

As described above, according to the present invention, there is provided a surface flaw inspection device for a rolled material capable of continuously detecting flaws on the rolled surface without adding any temperature stretching means such as cooling of the rolled material. To be done.

[Brief description of drawings]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a diagram showing a photographing area of one frame and an area to be trimmed. In the figure, 10 ... Imager, 30 ... Rolled material.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-58-168944 (JP, A) JP-A-54-51582 (JP, A) JP-A-54-92793 (JP, A) JP-B-55- 31415 (JP, B2)

Claims (1)

[Claims] 1. An image pickup device (10) having a shutter speed variable by an external signal and continuously photographing the surface of a rolled material (30) and outputting an image signal, and analyzing the image signal to perform the rolling. A flaw detecting means (20) for detecting a flaw on the surface of the material (30), a trimming means (14) for extracting only a signal within a predetermined range from the image signal, and an integration for integrating the output of the trimming means (14). Bowl (15)
And a calculating means (17) for calculating an appropriate shutter speed for keeping the output of the integrator (15) constant from the output of the integrator (15) and outputting the shutter speed to the image pickup device (10). A surface flaw inspection device for rolled material.