JP2005153089A - Method for removing surface flaw of billet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain and set a flaw removing depth during an automatic maintenance with high precision in processes of an automatic examination and the automatic maintenance of a billet. <P>SOLUTION: In the method for examining a flaw on a surface of the billet by an automatic flaw examining device and removing the detected flaw by an automatic flaw removing device, a set value of the flaw removing depth is obtained according to a kind of the steel of the billet and a flow signal level of the automatic flaw examining device and the flaw is removed by the automatic flaw removing device based on the set value of the flaw removing depth. At the time of removing the flaw, the set value of the flaw removing depth is corrected according to a reexamined area rate of the flaw. It is preferred that the automatic flaw removing device is an automatic milling cutter and flaw removal is carried out by one pass. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for automatically removing surface flaws of steel slabs (including slabs that have been continuously cast in addition to slabs that have been rolled into pieces. The same shall apply hereinafter), and more particularly to a method for setting the shave depth. Is.

Since the surface quality of the steel slab greatly affects the surface quality of the final product such as steel bars and wire rods, the surface scum of the steel slab is inspected to remove the slag. Patent Document 1 describes a method in which care is performed after automatic inspection, and then re-inspection is performed by visual inspection using a magnetic particle inspection method. As an automatic inspection method, for example, Patent Document 2 describes an automatic inspection method in a magnetic particle inspection method. In recent years, devices that are automatically cared for based on wrinkle information captured by automatic inspection have been used. As a care device, a milling cutter or the like that removes wrinkles by rotating a disk-shaped rolling tool (for example, Patent Document 3) provided with an outer peripheral blade is known in addition to a grinder. In automatic care, the depth of wrinkle removal greatly affects wrinkle removal accuracy, metal loss, and efficiency. Patent Document 4 proposes a method of predicting the wrinkle depth according to a preset surface wrinkle shape and grinding the wrinkle with the predicted wrinkle depth. However, even with this method, the accuracy of predicting the depth is not satisfactory.
JP 2003-136135 A Japanese Patent No. 3440569 JP 2001-38517 A Japanese Patent Laid-Open No. 7-40248

  This invention makes it a subject to provide the method of calculating | requiring and setting the flaw removal depth at the time of automatic care with high precision in the process which carries out the automatic inspection and automatic care of a steel piece in view of said situation. .

In the present invention, the present invention has been completed by incorporating the concept of steel type into the prediction of the flaw removal depth during automatic slab care. That is, the gist of the present invention is as follows.
(1) In the method of inspecting the surface flaw of a billet with an automatic flaw inspection device and removing the detected flaw with an automatic fraying device, the flaw is selected according to the steel type of the billet and the flaw signal level of the automatic flaw inspection device. A method for removing surface flaws from a steel slab, characterized in that a removal depth setting value is obtained, and wrinkles are removed by an automatic fraying device based on the wrinkle removal depth setting value.
(2) Reinspecting the surface of the steel piece removed with the automatic scraping device, and correcting the removal depth setting value according to the area ratio of the reexamined soot. A method for removing surface flaws on steel pieces.
(3) The method for removing surface flaws from a steel piece according to (1) or (2), wherein the automatic fraying device is an automatic milling cutter, and the flaw removal is performed by one pass.

  According to the present invention, the accuracy of removing the steel slab surface flaw is improved, the product quality is improved, the metal loss is reduced, and the productivity is improved, which is extremely useful in the industry.

  The method which is the premise of the present invention is a method in which the surface flaw of a steel slab is detected by an automatic flaw inspection device and the detected flaw is removed by an automatic fraying device. As an automatic flaw inspection apparatus, an apparatus that uses an electromagnetic flaw detection method, an apparatus that uses a method of detecting a temperature change of a buttock by heating a steel slab, or a magnetic powder pattern formed by a magnetic flaw detection method is imaged. In any device, the detected wrinkle signal level changes with a positive correlation depending on the depth of the wrinkles. The grinder, hot scurfer, abrasive water jet, or milling cutter can be used as the automatic scraping device, and all of them are electrically controlled rather than directly operated by the operator like a hand grinder. It is possible.

Hereinafter, the present invention will be described in detail with an example in which a device for imaging a magnetic powder pattern formed by a magnetic particle inspection method is employed as a preferred embodiment of the present invention of an automatic flaw inspection device.
As described in the above-mentioned Patent Document 2, the automatic scissor inspection device for imaging the magnetic powder pattern formed by the magnetic particle flaw detection method attaches the fluorescent magnetic powder to the surface of the magnetized steel piece, A flaw is detected by imaging fluorescence emitted by irradiating excitation light. The same document also describes a method for determining a soot seed using a magnetic particle flaw detection method and image processing, and is shown as a soot seed determining method using a feature amount that increases image brightness when the eyelid is deep. . According to this, it is easily considered that the wrinkle removal depth of the automatic wrinkle device can be obtained by a unique function with the wrinkle signal level (luminance) of the inspection device. However, according to the investigation results of the present inventors, when the relationship between the hull signal level and the hull depth was investigated by mixing four steel types of billets, as shown in FIG. On the other hand, it was found that the correlation was large and the same investigation was conducted in a single steel type. As shown in Fig. 1, it was found that the correlation was small and the correlation was high. The present invention has been completed by obtaining the removal depth.

That is, in the present invention, the relationship between the steel signal level and the depth of the steel is investigated in advance, and the depth of the removal is determined from the actually detected level of the defect signal based on this relationship. The removal depth of the automatic scraping device is set by the removal depth.
The method for obtaining the soot removal depth will be described with reference to FIG. FIG. 1 shows the relationship between the soot signal level in the automatic soot inspection apparatus and the actually measured soot depth for steel types A, B, C, and D. FIG. Each line is an upper limit line of variation of each steel type, and the wrinkle removal depth is obtained based on the upper limit line. For example, in steel grade A, for the soot having a soot signal level of 50% in the automatic soot inspection device, the soot removal depth is 2.5 mm as shown by the dotted line in FIG. It is.

After automatic picking with the flaw removal depth set by the above method, re-inspection, re-inspected flaws, that is, flaw removal depth set from the next steel slab by the area ratio of the remaining flaws after automatic picking By correcting the thickness, the wrinkle removal accuracy is further improved.
The re-inspection means may preferably be an automatic scissor inspection device that images the magnetic particle pattern formed by the above-described magnetic particle inspection method, or may be visual observation instead of imaging. The ridge area ratio in the case of visual observation may be a rough one by visual observation.
For the correction of the wrinkle removal depth, for example, a method of adding a constant according to the rank of the re-inspected wrinkle area ratio is adopted. If the re-inspected dredging area ratio is large, the set removal depth of the steel type is corrected to be deep, and conversely if the dredging area ratio is 0 or extremely small, the set removal depth is corrected to be shallow for the steel type. Is.

  An automatic milling cutter is preferably employed as the automatic scraping device. As described above, the automatic milling cutter removes surface wrinkles by rotating a disk-shaped tool provided with an outer peripheral blade, and is automatically controlled by wrinkle information from an automatic wrinkle inspection device. The milling cutter has a maximum removal depth of 3 mm per pass, is much deeper than the maximum depth of 1 mm of the grinder and has high performance, and the steel slab surface after removal of the defects is smooth due to the mirror surface. This has the advantage of easily detecting leftover wrinkles. And a wrinkle removal efficiency can be improved by performing a wrinkle removal with 1 pass with this automatic milling cutter.

It is a figure which shows the relationship between the wrinkle signal level of steel classification, and an actual wrinkle depth. It is a figure which shows the relationship between the wrinkle signal level at the time of mixing multiple steel types, and an actual wrinkle depth.

Claims (3)

  In the method of inspecting the surface flaw of a billet with an automatic flaw inspection device and removing the detected flaw with an automatic fraying device, the flaw removal depth according to the steel type of the billet and the flaw signal level of the automatic flaw inspection device A method for removing surface flaws from a steel slab, characterized in that a set value is obtained and wrinkles are removed by an automatic fraying device based on the set value for removing flaws.   The surface of the steel slab removed by the automatic scraping device is re-inspected, and the removal depth setting value is corrected according to the area ratio of the re-inspected steel slab. Surface wrinkle removal method.   The method of removing surface defects from a steel slab according to claim 1 or 2, wherein the automatic scraping device is an automatic milling cutter, and the defects are removed by one pass.

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