JPS6217185B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting flaws on the surface of a hot rolled material in a hot state during a blooming process.

Conventionally, flaw detection of hot-rolled materials has been carried out after the temperature of the rolled material has been lowered, since it is difficult to detect flaws in hot conditions. However, this method requires reheating the rolled material in the next step, which has been an obstacle to energy savings.

Therefore, various studies are currently being carried out to perform flaw detection on hot rolled materials, but they are still in a state of groping in the dark and nothing has been technically established.

As a result of various experiments conducted by the applicant of the present application, it was found that the reason why hot flaw detection is difficult is due to the non-uniformity of the texture of the material to be detected, especially the adhesion of secondary scale, and uneven drooping of the scarf. This secondary scale can be removed by a descaler such as a high-pressure water jet, and the scarf sag can be removed by grinding, but this requires a descaler and grinding device with powerful performance, which has the disadvantage of increasing equipment costs.

By the way, the removal of flaws from hot rolled material is carried out by passing it through a hot scarf in order to facilitate the processing of the rolled material in the next step. In scarfing, partial scarfing is preferable to full scarfing in order to improve product yield, but immediately after hot rolling, there are defects almost all over the rolled surface, and in reality, full scarfing occurs. The current situation is that we have no choice but to do this. Therefore, the present invention utilizes this full-surface scarfing to easily remove scarf droop, facilitate flaw detection, improve flaw detection accuracy in hot flaw detection, and ultimately enable energy savings. The hot-rolled material is rolled to a predetermined size, the surface to be tested is hot-scarved, and then lightly rolled for post-flaw detection. Rolling the surface other than the main surface of
Next, in the final pass, the rolled surface is flaw-detected, and then the hot-rolled material is hot-scarved over the entire surface and returned to the entrance side of the rolling mill, and in the final pass of the second rolling, the main surface of the hot-rolled material is An embodiment of the present invention will be described below with reference to FIGS. 1 to 3, which is characterized in that the main surface is subjected to flaw detection after light reduction.

In the figure, 1 is a soaking furnace, 2 is a continuous casting equipment, 3 is a rolling mill, 4 is a hot scarf core, 5 is a flaw detection device connected to a storage device 6, and 7 is the first rolling.
Reference numeral 9 denotes a device for the next process, which is connected to the storage device 6 and is a transport line that reversely transports the hot-scarved hot-rolled material (hereinafter simply referred to as rolled material) 8 or 8'. The flaw detection device 5 is located between the rolling mill 3 and the hot scarf 4 in order to detect flaws after the final rolling. On the final pass rolled surface, before the hot scarfing is performed, the elapsed time after rolling is short, and secondary scale is generated little and uniformly, so that there is no problem in flaw detection. However, scarfing makes the scale non-uniform, so the flaw detection device 5 is installed between the rolling mill 3 and the hot scarfing 4.

Next, we will explain how to perform flaw detection.

The rolled material 8 or 8' sent out from the soaking furnace 1 or the continuous casting equipment 2 passes through the rolling mill 3, where surfaces other than the main surface are rolled, and after the first rolling (rolling before reverse feeding), flaw detection is performed. The final pass rolling surface (surface other than the main surface) is inspected for flaws by the device 5. The flaw position obtained as a result of the flaw detection is stored in the storage device 6.

After the flaw detection, the rolled material 8 or 8' is hot-scarved on both the main surface and other surfaces, and then transported back through the rear wheel feed line 7 and subjected to light reduction rolling (final pass) in the final pass of the second rolling. rolling) is performed. Then, the final pass rolling surface (principal surface) is flaw-detected again, and the flaw position is stored in the storage device 6. The results of the first and second flaw detections are used in the device 9 in the next process for cleaning, shearing, etc. of the flaw.

Due to the rolling of the second and final pass on the main surface, secondary scale and hot scarfing are generated on the main surface and surfaces other than the main surface in the rolled material 8 or 8' by the second rolling. The resulting scarf droop is removed. This removal enables highly accurate flaw detection in the second flaw detection.

As described above, the first rolled surface is a surface other than the main surface, and the second rolled surface is the main surface. For example, in a slab as shown in FIG. 2, the wide surface X is the main surface and the other surfaces are surfaces other than the main surface. In addition, in the shaped steel material as shown in FIG. 3, the flange surface Y is the main surface, and the other surfaces are surfaces other than the main surface.

The reason why the final pass in the second rolling is performed with a light rolling force, that is, the reason why the light rolling is performed is to remove secondary scale and scarf droop. Furthermore, when light rolling is performed, flaws directly below the surface may easily appear on the rolled surface.

As described above, the entire surface of the rolled material can be easily tested by first testing the surfaces other than the main surface and then testing the main surface. In addition, flaw detection on surfaces other than the main surface before scarfing the entire surface of the main surface and surfaces other than the main surface will result in lower flaw detection accuracy, but the flaw detection accuracy will be lower when performing flaw detection on surfaces other than the main surface before scarfing. This is because even if some flaws remain after the flaws have been cleaned with device 9, there is no problem with the product, and the main surface is detected after scarfing the entire main surface and surfaces other than the main surface using hot scarfing. This is because the removal of the flaws is not complete even after ing, and since flaws on the main surface have an adverse effect on product quality, it is necessary to inspect them and completely remove them in the next step, the device 9. Furthermore, if hot scarfing is not performed, there will be many flaws that must be removed by care etc. in a subsequent process, and energy loss during removal will be large, which will significantly impair the advantages of hot flaw detection.

Next, another embodiment of the present invention will be described with reference to FIG.

In this embodiment, the difference from the previous embodiment is that the rolling mill 3 is
In addition, a rolling mill 3' is installed after the hot scarf 4, a flaw detection device 5 is installed between the rolling mill 3 and the hot scarf 4, and a flaw detection device 5 is installed between the rolling mill 3' and the device 9 for the next process. A device 5' is installed to perform flaw detection.

With such a configuration, hot flaw detection can be performed simply by directly feeding the rolled material. In addition, light reduction is performed in the rolling process of rolling mill 3', as in the case of the embodiment shown in Fig. 1, because the purpose of this is to remove secondary scale and scarf sag. This is because flaws tend to appear on the rolled surface.

In the embodiments of the present invention, a television camera, an infrared detector, a rotating mirror, etc. can be used as the hot flaw detection device, and the storage device can be anything that can send a signal to the next process.
It goes without saying that the rolling line may be configured such that the table rollers of the rolling line are fed in reverse or a separate wheel feeding device is provided, and that various other changes may be made without departing from the gist of the present invention. It is.

Since the hot flaw detection method of the present invention has the above-described configuration, it can achieve various excellent effects as described below.

() Since the final pass rolling surface is tested for flaws, there is little secondary scale and it is uniform, making it easy to detect hot flaws.

() The scarf sagging caused by hot scarfing is removed by the second light rolling process, so secondary scales can be removed and the texture can be made uniform.Furthermore, due to the light rolling process, the flaws just below the surface can be removed from the rolled surface. Since the flaws easily appear, the accuracy of hot flaw detection is significantly improved.

() By the flaw detection after the first rolling and the flaw detection after the second rolling, the main surface and the entire surface other than the main surface of the material to be tested can be detected, and the main surface has relatively few flaws. Since the flaws are detected in the state where the flaws have been removed by hot scarfing, the flaws to be removed become clear and it is possible to prevent omission of flaw removal during maintenance in the next process.

() Since the uniformity of the formation produced as a result of rolling is utilized, there is no need for special formation uniformity equipment, such as a descaler or grinding device, and if reverse rolling is performed, conventional equipment can be used as is, reducing equipment costs. is cheap.

(V) Since flaws can be detected on hot-rolled materials without lowering the temperature, there is no need to reheat the material, resulting in energy savings.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an embodiment of the hot flaw detection method of the present invention, Fig. 2 is an explanatory diagram showing a cross section when the rolled material is a slab, and Fig. 3 is an explanatory diagram showing a cross section when the rolled material is an H-beam steel. FIG. 4 is an explanatory diagram of another embodiment of the hot flaw detection method of the present invention. 3 and 3' are rolling mills, 4 is a hot scarf mill,
5 and 5' are flaw detection devices, 6 is a storage device, 7 is a transportation line, and 8 and 8' are hot rolled materials.

Claims (1)

[Scope of Claims] 1. A hot flaw detection method characterized by rolling a hot-rolled material to a predetermined size, hot scarfing the surface to be tested, and then performing a light reduction for post-flaw detection. 2. In the final pass of the first rolling, the surface other than the main surface of the hot-rolled material is rolled, then in the final pass, the rolled surface is flaw-detected, and then the entire hot-rolled material is hot-scarved and rolled. Return to the entry side of the machine,
A hot flaw detection method characterized in that the main surface of the hot rolled material is lightly rolled down in the final pass of the second rolling, and then the main surface is tested for flaws.