Apparatus and method for determining kind of steel material

1. An apparatus for determining the kind of a steel material, comprising:

an image pickup device for imaging a spark, which is produced when the steel material is ground, continuously a plurality of times;

a detection device for detecting an alloy spark zone, which corresponds to an alloy spark produced by the grinding of an alloying component contained in the steel material, from each of picked-up images imaged by the image pickup device;

a calculation device for calculating the total number of alloy spark zones by summing up the number of alloy spark zones of each picked-up image detected by the detection device for all of the picked-up images; and

a judgment device for determining that the steel material consists of a low-alloy steel if the total number is not smaller than a first threshold value, and determining that the steel material consists of a carbon steel if the total number is smaller than the first threshold value, wherein

the detection device performs:

first processing in which a spark candidate pixel group consisting of pixels which are continuous with each other along a pixel line and have a density not lower than a second threshold value is detected for one pixel line constituting each of the picked-up images;

second processing in which a highest density of pixels constituting the spark candidate pixel group is detected, and the pixels constituting each of a plurality of spark candidate pixel groups are binarized by a third threshold value which is lower than the highest density and larger than the second threshold value, whereby the pixels constituting a spark pixel group are detected from the pixels constituting each of the plurality of spark candidate pixel groups;

third processing in which a binarized image representing the spark pixel group is prepared by executing the first processing and the second processing for all of the pixel lines constituting each of the picked-up images, and the spark pixel group continuous on the binarized image is recognized as a spark zone corresponding to a spark produced when the steel material is ground; and

fourth processing in which the alloy spark zone is detected from the spark zone recognized by the third processing.

2. The apparatus for determining the kind of a steel material according to claim 1 , wherein

the fourth processing comprises:

determination processing for determining whether or not the spark zone recognized by the third processing falls under a first determination pattern based on the ratio of the width of an end portion on the front side in the spark scatter direction to the width of an end portion on the rear side in the spark scatter direction in the spark zone recognized by the third processing; and

detection processing for detecting the spark zone determined to fall under the first determination pattern by the determination processing as the alloy spark zone.

3. The apparatus for determining the kind of a steel material according to claim 2 , wherein

the determination processing determines whether or not the spark zone recognized by the third processing falls under the first determination pattern, and also determines whether or not the spark zone recognized by the third processing falls under a second determination pattern based on the relationship between the direction of the spark zone recognized by the third processing and the direction of another rear spark zone which is present at the rear in the scatter direction of the spark zone, and the length of the rear spark zone; and

the detection processing detects the spark zone determined to fall under the first and second determination patterns by the determination processing as the alloy spark zone.

4. The apparatus for determining the kind of a steel material according to claim 3 , wherein

the determination processing determines whether or not the spark zone recognized by the third processing falls under the first and second determination patterns, and also determines whether or not the spark zone recognized by the third processing falls under a third determination pattern based on the distance between the spark zone recognized by the third processing and the rear spark zone; and

the detection processing detects the spark zone determined to fall under all of the first to third determination patterns by the determination processing as the alloy spark zone.

5. The apparatus for determining the kind of a steel material according to claim 2 , wherein

the determination processing determines whether or not the spark zone recognized by the third processing falls under the first determination pattern, and also determines whether or not the spark zone recognized by the third processing falls under a third determination pattern based on the distance between the spark zone recognized by the third processing and another rear spark zone which is present at the rear in the scatter direction of the spark zone; and

the detection processing detects the spark zone determined to fall under the first and third determination patterns by the determination processing as the alloy spark zone.

6. The apparatus for determining the kind of a steel material according to claim 1 , wherein in the case where the steel material consists of a low-alloy steel, the judgment device determines the content of the alloying component in the steel material based on the total number.

7. A method for determining the kind of a steel material, comprising:

an imaging step of imaging a spark, which is produced when the steel material is ground, continuously a plurality of times;

a detecting step of detecting an alloy spark zone corresponding to an alloy spark, which is produced by the grinding of an alloying component contained in the steel material, from each of the picked-up images imaged in the imaging step;

a calculating step of calculating the total number of alloy spark zones by summing up the number of alloy spark zones of each picked-up image detected in the detecting step for all of the picked-up images; and

a judging step of determining that the steel material consists of a low-alloy steel if the total number is not smaller than a first threshold value, and determining that the steel material consists of a carbon steel if the total number is smaller than the first threshold value, wherein

the detecting step includes:

first processing in which a spark candidate pixel group consisting of pixels which are continuous with each other along a pixel line and have a density not lower than a second threshold value is detected for one pixel line constituting each of the picked-up images;

second processing in which a highest density of pixels constituting the spark candidate pixel group is detected, and the pixels constituting each of a plurality of spark candidate pixel groups are binarized by a third threshold value which is lower than the highest density and larger than the second threshold value, whereby the pixels constituting a spark pixel group are detected from the pixels constituting each of the plurality of spark candidate pixel groups;

third processing in which a binarized image representing the spark pixel group is prepared by executing the first processing and the second processing for all of the pixel lines constituting each of the picked-up images, and the spark pixel group continuous on the binarized image is recognized as a spark zone corresponding to a spark produced when the steel material is ground; and

fourth processing in which the alloy spark zone is detected from the spark zone recognized by the third processing.

8. The method for determining the kind of a steel material according to claim 7 , wherein in the imaging step, a spark produced when the steel material is ground by a grinding member pressed against the steel material with a force not lower than 2.94 N and not higher than 9.8 N is imaged.