JPS58181401A - Rolling method by cross rolling reduction - Google Patents

Abstract

PURPOSE:To improve the yield of a product considerably by combining edging or horizontal rolling after preforming to form one pass of rolling stage and performing said stage repeatedly a number of times. CONSTITUTION:The slab S which is heated in a heating furnace 1 is first preformed P with a press for cross rolling reduction in the upper stream position of a vertical roll 3 in hot rolling said slab. The preforming P is accomplished in the part apart at least 100mm., max. 500mm. from the end face at one end part in the longitudinal direction of the slab in a symmetrical shape from both sides in the transverse direction of the slab. The slab is subjected to edging V over the entire length of the slab with a vertical roll 3 immediately upon ending of the preforming P and is then subjected to horizontal rolling H with a horizontal roll 4. The rolling stage of P-V-H is repeated a number of times. The rolling reduction of the press in the preforming P in each stage is set at the rolling reduction obtained by subtracting the width of the slab after horizontal rolling H from the width of the slab before the edging V in each stage.

Description

[Detailed description of the invention] The present invention relates to a slab width reduction rolling method.

In general, in hot rolling of a slab that has been flattened in a V shape by continuous casting or blooming, width reduction rolling is performed to ensure the width of the finished product, as shown in FIG. 1(A). A tail F is formed at the end.

In addition, recent efforts have been made to improve the efficiency of continuous casting.
Since the number of roots is small, it may be necessary to use the aforementioned width killing forcefully, and the weight/yu chile tends to become larger and larger. This fin/
Since the tail F is discarded after rolling, it is the biggest cause of a decrease in yield.

Furthermore, in hot strip rolling, Fig. 1 (B)
As shown in Figure 2, the width of the leading and trailing ends is smaller than the width of the middle part fI''a) A problem arises in which the width of the leading and trailing ends is small, which is also a major cause of a decrease in yield. Therefore, as a method to reduce fish tails, a preforming method has been proposed in which the leading and trailing ends of the slab are pressed using a press and deformed into a narrow width.

However, in the conventional preforming method, the leading and trailing ends of the slab are preformed prior to hot rolling. It is necessary to increase the amount of preforming. For this reason, there are problems such as buckling of the slab during molding, the need for a powerful press device, and increased equipment costs. In the conventional method of preforming the front and rear ends of the slab, the slab runs away in the longitudinal direction, unbalanced loads are applied to the press body, and in order to form the very end of the slab into a narrow width, the front and rear ends of the strip are There is a problem in that the fish tail is not effectively reduced due to the small width.

The present invention is a further improvement of the "slab preforming method" related to Japanese Patent Application No. 17286/1986 by the same applicant, which was already proposed in view of the above-mentioned circumstances.
The purpose of this is to effectively reduce fish tails even for wide slabs with a large amount of width loss without promoting narrowing at the leading and trailing ends of the strip, thereby further improving yield, and to improve the yield during preform rolling. The purpose is to prevent unbalanced loads acting on the press body.

The method of the present invention is based on applying preform rolling using a press to give χ + t to the end of the material before wax killing rolling, similar to the slab preforming method of the previous application, but after preforming rolling, width killing rolling or The method is characterized in that horizontal rolling is combined to form one bath of rolling process, and this process is repeated several times.

Hereinafter, the method of the present invention will be explained with reference to the drawings.

As shown in FIG. 2, the slab S heated in the heating furnace 1 is
When performing hot rolling, first, preform rolling (
Do P). The preform rolling (P) by the press 2 is the sixth
As shown in the figure, a portion at least 100 mm away from one end in the longitudinal direction of the slab, and 500 mm at most, is symmetrically formed from both sides in the width direction of the slab. The shape of the molded portion is preferably a wide U-shape or a wide V-shape. Preform rolling (
After P) is finished, width rolling (V) is immediately performed over the entire length of the slab with vertical rolls 6, and then with horizontal rolls 4.
Horizontal rolling (H) in the thickness direction of the slab is performed.

In the method of the present invention, as shown in FIG.
Considering Tonoro type of process as one correction process, this (P)
-(V) -(H) Rolling is performed repeatedly several times with one bus. In this case, the rolling reduction amount ΔP at 1 in the preform rolling (P) is the slab width W before width reduction rolling (V) in each process.
It is set to an amount (ΔP-Wo-W2) obtained by subtracting the slab width W2 returned after horizontal rolling (H) from o, and half of that value, ΔP/2, is set for the left and right presses 2, respectively.

As a modification example of the above-mentioned (P)-(V)-(H) rolling,
FIG. 5 shows the preform rolling (P) and the width reduction rolling (V) in 1
The process of carrying out the above-mentioned horizontal rolling (H) after (P) - (V) rolling which is repeated several times as a bus is shown. The shaded area in the figure shows the raised area (dock pawn shape) due to width reduction.

In the method of the present invention, the inside of the predetermined length range of the front and rear ends of the slab is preformed and rolled using a press, so the end Se of the slab has a relatively wider width than the pressed part. It has a shape that extends in the direction. Since preforming is performed before valley width reduction, the amount of width increase is larger than in the conventional one-time preforming press.Therefore, the fish tail that tends to occur when width reduction rolling and horizontal rolling are performed is minimized. This offsets the effect of the overhang of the end face, and the fish tail is significantly reduced. Therefore, by repeating this operation several times, most of the fish tails are eliminated.

Next, specific examples of slabs rolled according to the present invention will be described. A slab with a width of 1210 mu and a thickness of 270 mm was heated at a temperature of 1200°C (P) - (V) - ()
l) Rolling was carried out to reduce the width to 10 DOmm.

The pressing conditions at this time were that a 70 mm Lares reduction rod was set for both 41j baths, and the slab was pressed 100 mm inside from the end. Width rolling is performed with a reduction of 100 mm per ζ step, and horizontal rolling (H) is performed with a roll gap of 270 m.
1. Knob bone smoothing rolling was performed at m. A rolled product from a slab obtained by repeating such (P)-(V)-(H) rolling three times, thickness 6. Omm x width 1000+
The clot rate of nm is 0.1 for the top and bottom.
3%, and no small width phenomenon occurred. This is a significant increase compared to the cropping rate of 0.5% when the method of the present invention is not used.

As described above, according to the method of the present invention, it is possible to suppress the occurrence of fish tails to a satisfactory level without promoting the narrow width of the slab end, thereby significantly improving the yield of finished products. do.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a strip rolled by a conventional method. FIG. 2 is a schematic plan view of a rough rolling facility to which the method of the present invention is applied. FIG. 6 is a plan view of the slab preforming and rolling process. FIG. 4 is a plan view showing one unit process of the method of the present invention. FIG. 5 is a plan view showing another embodiment of the method of the present invention. 1: Heating furnace 2: Press for width reduction: Vertical roll 4: Horizontal roll S varnish slab\C illusion [

Claims (1)

[Claims] (1) In hot rolling, before width reduction rolling, preform rolling (P) is performed on both sides of the front end and rear end of the slab to a narrow width by pressing, and the slab is rolled in the width direction by vertical rolls to make the slab width narrower. Performing killing rolling (V), performing horizontal rolling (H) on the slab in the thickness direction using horizontal rolls, and repeating the rolling process of (P)-(■)-(H) several times. , the preform rolling is performed at a position 100 to 500 mm away from the end face of the slab, and the amount of press reduction in the preform rolling in each step is the width of the slab after horizontal rolling from the width of the slab before width reduction rolling in each step. Width reduction rolling method 3, characterized in that (2) the above (P) - (V) rolling is repeated a plurality of times, and then the above (H) rolling is performed. Claim No. (
The method described in section 1).