JPS5952777B2 - flaw detection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flaw detection apparatus that detects surface flaws on a material to be flaw-detected, such as a hot steel material.

In a blooming rolling or continuous casting process in a steel manufacturing plant, generally, a hot steel material is cooled to room temperature and surface flaws in the steel material are visually detected.

Therefore, in such a method, when performing hot rolling, the steel material must be heated again, complicating the process and causing an extremely large loss of thermal energy.

Therefore, in order to solve this problem, surface flaws in the steel material can be detected by using an imaging device to image the surface of the steel material in the hot state, without having to cool the steel material in the hot state. <A flaw detection device that dynamically detects surface flaws in steel materials and determines the location of the flaws in the hot state to remove the flaws, thereby omitting the cooling and reheating process. It is considered.

Conventionally, in such a flaw detection apparatus, a video signal from an imaging device is directly input to an analog comparator, and the presence or absence of a flaw is determined by comparing the amplitude levels.

By the way, a video signal from an imaging device that images the surface of a steel material in a hot state is a signal having an amplitude that corresponds to the brightness of the surface of the steel material. However, since such defect signal components are extremely small and the video signal contains a lot of irregular noise, it is difficult to distinguish them from the irregular noise components. Although it is difficult and impractical to input signals directly into an analog comparator and compare their amplitude levels to directly identify only the flaw component signal, the problem is that accurate flaw detection cannot be performed. There is.

This invention was devised in view of these problems, and it is possible to clearly separate and distinguish the flaw signal component and the irregular noise component contained in the video signal, thereby detecting surface flaws on the material being tested. The object of the present invention is to provide a flaw detection device that can perform accurate detection.

An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, the present invention is applied to the detection of surface flaws in hot steel material during the blooming or continuous casting process in a steel manufacturing plant. The surface of the material to be tested, that is, the hot steel material 1, is imaged by the imaging device 2.

The composite video signal a from the imaging device 2 is input to a buffer amplifier 3, and after being power amplified, it is input to a signal distributor 4, where it is transmitted for each horizontal scanning period as shown in FIG. It is divided into N equal parts in the time axis direction. Here N
is any integer including 1. Each divided composite video signal a is integrated by each corresponding integrator 51 to 5N, and the integral value of each divided signal of the composite video signal a integrated by each integrator 54 to 5N is sequentially processed by a multiplexer 6. The signal is inputted to the A/D converter 7 at a certain timing, digitized, and inputted to the adder 8. The integral value of each divided signal of the composite video signal a input to this adder 8 is added by the adder 8 to the integral value of each divided signal divided at the same timing in each horizontal scanning period of the composite video signal a. , are stored in the storage device 9. This means, for example, that A/
Each integral value from the D converter 7 and the stored value read from each predetermined location in the storage device 9 are added, and the addition results are stored again in each predetermined location in the storage device 9, thereby producing a composite video signal a. The integrated values of each divided signal divided at the same timing in each horizontal scanning period are accumulated, and the accumulated results are stored in each predetermined location of the storage device 9. Here, the contents of the storage device 9 are set to zero before starting the addition operation. The cumulative results of a predetermined number of integral values stored in each predetermined location of the storage device 9 are sequentially read out by a scanner 10, and a reference value set by a reference value setter 12 is read out by a comparator 11. C, and the comparison result is taken out as a flaw information signal b. In other words, if it is larger than the reference value C, the logic is 1.
b, and it is detected that there is a flaw on the surface of the hot steel material 1. Further, the composite video signal a from the imaging device 2 is input to the sync separation circuit 13, and the sync separation circuit 13 separates the vertical and horizontal sync signals.

Each synchronization signal separated by this separation circuit 13 is combined with a pulse signal output from a pulse signal oscillator 15 in a timing signal generation circuit 14, and the timing signal generation circuit 14 synchronizes the operation of each signal processing circuit. The timing pulse d is taken out and supplied to each signal processing circuit. Further, the storage contents of the storage device 9 are cleared each time the scanner 10 reads out a predetermined number of accumulated results of integral values stored in each predetermined location of the storage device 9. In this way, if the imaging device 2 images a flaw on the surface of the hot steel material 1, the flaw will appear in the signal divided at the same timing in each horizontal scanning period of the composite video signal a output from the imaging device 2. The generated defect signal component appears repeatedly, and the sum value obtained by integrating the respective divided signals becomes a very large value.

In comparison, irregular noise components do not appear repeatedly in signals divided at the same timing in each horizontal scanning period of composite video signal a, so the sum of the integral values of each divided signal is Even if an irregular noise component is included in the video signal a, it will not be very large. Therefore, by comparing the summed value with the reference signal C, it is possible to clearly separate and distinguish the flaw signal component and the irregularity noise component contained in the composite video signal a, and the surface of the material to be tested can be clearly distinguished. Defects can be detected accurately. Further, by integrating the video signal along the time axis in this manner, it is extremely effective in detecting flaws parallel to or diagonal to the horizontal scanning line, and can be detected accurately. Note that the configuration of this invention is not limited to that of the above embodiment,
Of course, various changes can be made without changing the gist.

As described above, according to the present invention, it is possible to clearly separate and distinguish the flaw signal component and the irregularity noise component contained in the video signal, thereby accurately detecting surface flaws on the material to be tested. It is possible to provide a flaw detection device that can perform

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
FIG. 2 is a diagram showing signal waveforms in the same embodiment. DESCRIPTION OF SYMBOLS 1... Heat steel material, 2... Imaging device, 4... Signal distributor, 51-5N... Integrator, 6... Multiplexer, 8... Adder, 9... Storage device , ]1... Comparator, b... Flaw information signal.

Claims (1)

[Claims] 1 Image the surface of the hot steel material to be tested with an imaging device,
dividing each horizontal scanning period of the video signal output by the imaging device into a predetermined number, integrating each of the divided signals, and adding and storing the corresponding integrated signals in the predetermined number of horizontal scanning periods; A flaw detection device characterized in that a flaw information signal is obtained by comparing the stored added value with a preset reference value.