JPH03243261A - Method for executing grinding cleaning for melt-cutting face in continuously cast slab - Google Patents

Abstract

PURPOSE:To obtain finished surface without any burr by executing grinding to ruggedness of cutting face or resolidified layer after melting at the first time and successively, executing the grinding and removal of cutting droop. CONSTITUTION:At first, by removing the ruggedness of cutting face and the resolidified layer after melting with the grinding, these are removed, and the burr 3 is newly developed at the cutting droop 6 part. Successively, by removing the cutting droop 6 with the grinding, the burr 3 is removed together with the droop 6 and not at all allowed to remain in the ground surface. By this method, the burr removal work with scarfing is unnecessary, and the reduction of cost and the improvement of yield can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for cleaning the melted surface of a continuously cast slab by grinding it with a grinder.

<Prior Art> In general, methods for cleaning the gas-melted section of slabs include scarfing and grinding (hereinafter abbreviated as "grinding"). Among these, as a cleaning method by grinding, there is an automatic grinding method using an automatic sag removing device for the end face of a steel piece, as disclosed in Japanese Patent Application Laid-Open No. 63-30207.

<Problems to be Solved by the Invention> The above-mentioned invention removes sag attached to a steel piece (referred to as a slab in the present invention) by cutting the base of the sag by grinding the corner portion of the steel piece. This is a device that removes sagging, and it is characterized by reducing the grinding power and increasing the grinding speed, as well as being able to automatically finish the marking surface (one end surface). No consideration is given to burrs.This burr is
As shown by 3 in Fig. 1, when grinding is performed by rotating the circular grinding wheel l downward relative to the cross section of the slab 2 and moving it parallel to the longitudinal direction of the slab 2, the scraps generated by grinding. It hardens into threads and adheres to the edge of the grinding surface.

However, if this firmness is not scaled on during hot rolling of the slab, it remains as a bald spot at the end of the hot rolled steel sheet.

This sagging is a surface defect that occurs in the form of streaks in the rolling direction of a rolled steel plate.If this sagging is large, it is necessary to take measures such as cutting off the edges of the steel plate where the sagging occurs. Therefore, there was a problem that the yield decreased. Therefore, the slabs with burrs are treated by scarfing, which causes a problem of lower yield.

The present invention has been made in order to provide a method for grinding and caring for the melted surface of a cast slab, which provides a finished surface that does not generate any firmness.

<Means for Solving the Problems> The present invention is characterized by: (i) grinding to remove irregularities on the molten surface of continuously cast slabs, melted and resolidified layers generated on the surface layer of the cross section, and sag attached to the lower part of the cross section; When cleaning and removing by grinding, continuous casting is characterized by first grinding the unevenness of the cross section or the melted and resolidified layer, and then grinding and removing the sag to obtain a burr-free finished surface. In the method for grinding and cleaning the melted surface of a slab, and when grinding and removing the sag described in the previous section, the sag attached to the lower part of the melted surface of the slab should be applied to an extent that does not exceed the welded part to the bottom surface of the slab. This is a grinder-grinding method for cleaning a melted surface of a continuously cast slab, characterized in that burrs grow on the underside of the sagging and are removed together with the sag.

Function> The present invention is capable of cleaning and removing by grinding the unevenness that occurs on the cross section when a slab is divided by fusing, the melted and resolidified layer that is generated on the surface layer, and the sagging that adheres to the lower part of the cross section. When doing so, the grinding procedure is to first grind the unevenness of the cross section or the melted and resolidified layer, then remove the sagging,
This is a care method that allows you to obtain a burr-free finished surface.

FIG. 2 shows a cross section of the slab after melt cutting, and unevenness 4 occurs on the melted surface of the slab 2 due to turbulence of the cutting gas. Further, a melted and resolidified layer 5 is formed on the surface layer forming the uneven cross section. This is a base metal (slab) melted by the action of fusing and re-solidified by being cooled by other base metals, resulting in a structure that is chemically different from the original base metal. Furthermore, a sag 6 is attached to the lower part of the cross section.

For such a cross section, in the present invention, first, the unevenness of the cross section and the melted and resolidified layer are removed by grinding.

The cross section obtained as a result is shown in FIG. 3, and the unevenness of the cross section and the melted and resolidified layer are removed, and burrs 3 are newly formed in the sag portion.

Next, the sag was removed by grinding, and the resulting cross section and the sag removed are shown in FIG. By removing this sag, all burrs are removed along with the sag, and no burrs remain on the ground cross section. However, if the ground surface is ground again after removing the sag, burrs will be generated on the ground surface, so in the present invention, it is important not to perform grinding after removing the sag.

If the cross section is wide and the unevenness of the cross section or the melted and resolidified layer cannot be removed by one grinding, a burr-free cross section can be obtained by the following method.

Fig. 5 shows the state of the first grinding when the number of times of grinding is two or more. Thread-like burrs 3 are produced at the bottom of the surface. The next grinding is performed by lowering the grindstone position from the first grinding. At this time, as shown in FIG. 6, it is important to overlap the grinding ranges so as to remove the burrs produced by the first grinding. Thereafter, the position of the grindstone is similarly lowered and grinding is performed as many times as necessary, and when burrs form on the sag attached to the lower end of the cross section, the sag is removed.

If the unevenness of the cross section or the melted and resolidified layer is not a problem, only grinding may be required to remove the sag. The same applies to the removal of sagging performed after grinding to remove unevenness of the cross section and the melted and re-solidified layer, but in order to obtain the effects of the present invention, the following is true in the grinding for removing sag. This is important.

That is, as shown in FIG. 7, the area to be ground by the grinding wheel 1 should not exceed the area where the sag 6 is welded to the lower surface of the slab. The dashed line in the figure shows the case where the grinding range of the grinding wheel l exceeds the range where the sagging 6 is attached, which results in the formation of burrs on the lower end of the slab. However, even if the range is not exceeded, burrs may adhere depending on the grinding conditions such as bone collection of the material to be ground and adhesion of sag, so it is necessary to find a grinding method that suits each grinding condition through experiments. be.

However, since grinding conditions rarely change in a short period of time, stable grinding can be performed for a long period of time by setting the -degree grinding method. This also applies to grinding to remove irregularities in the cross section and melted and resolidified layers.

<Example> An embodiment of the present invention will be described with reference to the drawings.

Figure 8 shows the path of movement of the grinding wheel when cleaning the cross section by grinding. In this figure, the solid line shows the path of movement while grinding, and the broken line shows the path of movement without grinding. There is. Further, the direction of the arrow in the figure indicates the direction in which the grindstone 1 is moved. The position to be ground is indicated as the height (x) of the center of the grinding wheel with the lower surface of the slab 2 as a reference.

The grinding process 8 was divided into three times in total for the cross section of the slab 2.

Grinding was carried out twice to remove irregularities in the cross section and the melted and solidified layer, and grinding was carried out once to remove sag.

The first grinding process 8 (1) is grinding to remove unevenness on the cross section and the melted solidified layer, and the grinding height x (1)
was set at 40 mm with respect to the total height of the cross section (thickness of slab 2). The reason why the setting was not set to the highest level was because the properties of the cross section were good and the unevenness of the cross section was not a problem, and as a result of photographic analysis of the cross section, the melted and solidified layer
This is because it has been found that it is sufficient to grind the range m+n. When the grindstone was crimped at this position, a grinding surface was obtained within a range of ±35 cylinders in the vertical direction relative to the grinding height. A burr of 3 to 4 mm was attached to the lower end.

Next, the process moved to the second grinding step 8 (2) for removing the unevenness of the cross section and the melted and resolidified layer. Grinding height x at this time
(2) was set to 10 mm. The grinding range is ±35 as before.
Since it is IIIrrl, the grinding range overlaps by 40 cabinets. As a result, the burrs generated during the previous grinding were removed, and new burrs were formed at the sag portion at the lower end of the grinding section. Note that the purpose of overlapping the grinding ranges is to obtain a sufficient grinding thickness, and is not intended only to remove firmness.

Finally, the third grinding step 8 (3) to remove sagging
has moved to The crimping direction of the grinding wheel at this time was set at 45°, whereas previously the crimping direction was perpendicular to the cross section (90°). This is because it is an effective angle for sufficiently grinding the part where the sagging adheres to the slab, and as a result, it was possible to completely remove the sagging by grinding to a depth of 10 am from the cross section.

Burrs caused by this grinding were also formed on the lower surface of the sag and did not remain on the ground surface.

According to the present invention, all the burrs caused by grinding could be accumulated in the sag, and the sag could be removed without leaving any on the surface to be ground, so that a good surface to be ground without burrs could be obtained.

Note that the numerical values exemplified in the above examples vary depending on the properties, characteristics, grinding conditions, etc. of the material to be ground (cast slab) and the grinding wheel, and are not limited to these values.
In the grinding process, by applying the present invention, it is possible to simultaneously remove unevenness in the cross section, melted and resolidified layer, and sag.

The gist of the present invention is to collect all the burrs caused by grinding into sag, and to remove the sag so that the burrs do not remain on the surface to be ground.

When cleaning the melted surface of a slab by grinding, first grind the cut surface and then remove the sag, and when removing the sag, grind within the range where the sag is welded to the bottom surface of the slab. By doing this, we were able to obtain a burr-free finished surface. This eliminates the need for the work of scarfing to remove tension, which has been done up until now, making it possible to reduce the cost of writing lyrics and improve yield.

Furthermore, in the past, efforts have been made to reduce the grain size of the grinding wheel in order to minimize the burrs produced by grinding. However, since the effects of the present invention are not affected by the size of burrs, it was possible to increase the grain size of the grindstone. Increasing the grain size of the whetstone increases the life of the whetstone and reduces running costs.

<Effects of the Invention> According to the present invention, it is possible to obtain a smooth surface to be ground by grinding with a grinder for gas cutting of cast slabs, eliminating the need for deburring work by scarfing, reducing the amount of work and improving yield. I was able to achieve it.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the state of grinding with a grindstone, Fig. 2 is a perspective view showing the slab after melt cutting, Fig. 3 is a perspective view showing the cross section after end face grinding, and Fig. 4 is a perspective view showing the slab after being fused. A perspective view showing the cross section and sag after removal, Fig. 5 is a perspective view showing the first grinding state, Fig. 6 is a perspective view showing the second grinding state, and Fig. 7 is for removing sag. FIG. 8 is a perspective view showing the grinding position of the grindstone. FIG. 8 is a perspective view showing the movement path of the grindstone. ■...Grinding wheel, 3...Paris, 5...Dissolved solidified layer, 7...Position where burrs remain, 8(1)...Grinding process (first time), 8(2)... ...Grinding process (2nd time), 8 (3)...Grinding process (3rd time), X...Grinding height, x (1)...Grinding height of grinding process (1st time), (
2)...Grinding height of the grinding process (second time). 2... Slab, 4... Concave and convex, 6... Dashing, 8... Grinding process,

Claims (1)

[Claims] 1. When cleaning and removing irregularities on the melted surface of a continuously cast slab, the melted and resolidified layer formed on the surface layer of the cross section, and the sag attached to the lower part of the cross section by grinding, Grinder-grinding care of the molten surface of continuous cast slabs characterized by first grinding the unevenness of the cross section or the melted and resolidified layer, and then grinding and removing the sag to obtain a burr-free finished surface. Method. 2. When grinding and removing sagging as described in claim 1, the sagging attached to the lower part of the melted surface of the slab should be ground and removed within a range that does not exceed the welded part to the lower surface of the slab, so that the burr does not sag. A grinder grinding method for cleaning a melted surface of a continuously cast slab, characterized in that the sag formed on the lower surface of the slab is removed together with the sag.