JPS58301A - Blooming method - Google Patents

Abstract

PURPOSE:To improve the yield of blooming by pressing the leading and trailing ends of blooms of a rectangular section produced by a continuous casting process prior to blooming. CONSTITUTION:Blooms B of a rectangular section which are cast by a continuous bloom casting machine 21 and are cut to suitable lengths by a gas cutter 22 or blooms B which are continuously cast and are heated by a heating furnace 23 are fed into a pressing device 24. The leading and trailing end parts thereof are reduced down to a suitable thickness within a >=250mm. range from the end parts and the end parts are bulged to a projecting shape by means of a pair of upper and lower dies of a device 24 while the longer sides of the blooms B are restrained. After these are rolled down to a prescribed size with the 1st blooming mill 25, they are scarfed away of the surface flaws with a hot scarfer 26 depending upon cases, and are rolled down to billets of square sections and sizes by continuous rolling mills 27. The billets are cut to required sizes with a shear 28.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a blooming material produced by a blooming method, specifically a continuous casting process.

This relates to the blooming method of rolling billets with small cross-sections.In blooming, the size of the material (ingot) is large, so the rolling force does not penetrate into the inside, so the first surface layer extends upward from the center and reaches both ends. Fixtures, tails, and overlaps are formed, and therefore, these parts are cut and removed, reaching a gloss of about 3 to 6 inches.

In the past, efforts have been made to improve the shape of the ingot and minimize the formation of overlapping or fish island till to achieve the desired objective. -1 Recently, a rounding continuous casting process has been actively introduced to eliminate material loss or energy loss during ingot making and blooming rolling. In particular, when rolling a blue material with a rectangular cross section into a billet with a square cross section, no consideration has been given to the aC material, so the above-mentioned rolling of blue material with a rectangular cross section into a billet with a square cross section may result in the above-mentioned rolling of the blue material with a square cross section.
If the amount of fishtail or overluff is constant, the end deformation will occur depending on the thickness of the entry side plate as shown in Figure 1. It is known that, when rolling a bloom with a rectangular cross section, when rolling is applied from the long axis side, the processing rate in the wrinkle direction is extremely large compared to the processing rate in other directions. The formation of fish till or overlap is manifested in a significant increase in cropping amount and a decrease in rolling yield.

In view of the above-mentioned points, as a result of various studies, the present invention provides various shapes to the leading and trailing ends of the blue material obtained by a continuous casting process, and investigates the relationship between such shapes and the mechanism for producing fish island tills or overlaps. It was created in pursuit of the following, and its characteristics are:
Manufactured using a continuous casting process with a large length and width dimension ratio of l:
When blooming 12 or more rectangular cross-sections is bloomed into a square cross-section billet, prior to rolling, the tip and rear ends are machined by a pair of upper and lower dies with an end milling depth of at least 2
Within the range of 50ψ, the long side of the bloom is restrained, the thickness is reduced to an appropriate thickness, the end is press-formed into a convex bulge, and then rolled to form a tail or overlap. suppresses the production of
There are also things that try to reduce crop loss.

The second feature is that when a bloom with a rectangular cross section manufactured by a continuous casting process and having a large length/width dimension ratio of 1:L2 or more is bloomed into a billet with a square cross section,
Prior to rolling, the leading and trailing ends are rolled using a pair of upper and lower dies to an appropriate thickness while restraining the long sides of the bloom within a range of at least 2501Q/m and applying back pressure from the rear of the bloom. The process is performed by press forming into a bulged portion with a convex shape at the end to reduce the thickness, and then rolling.

To explain in detail the blooming method of the present invention, the present inventors have explained the above-mentioned mechanism for producing tails and overlaps in the blooming process using plasticine (oil-based clay) to form a bloom shape obtained by a continuous casting process. (hereinafter simply referred to as a bloom), the shapes of the leading and trailing ends were examined in relation to the bloom dimensions, the rolling reduction amount, and the roll diameter. The thickness of the edge of the bloom is reduced by press forming, and as shown in Figure 1, the press tool restrains the side of the bloom and prevents the expansion of the material in the direction perpendicular to the pressing direction. A parallel caliber 11 is connected to the caliber 11 to regulate the rolling, and a caliber 11 is connected to the caliber 11 so as to be inclined so as to avoid the occurrence of rolling flaws caused by folding during rolling at the transition area between the thin part and the original size part. The bloom was fed between a pair of upper and lower dies 10 each having a surface 12 formed thereon, and press molding was performed. The bloom has a step S formed at its leading end (or rear end), and as a result of press working, a convex bulge is formed on the end surface.

As can be understood from the results in Fig. 1, fish till and overlap can be sufficiently suppressed when the reduction in thickness can be sufficiently achieved by increasing the amount of press reduction at the end of the bloom. However, considering the actual production line, the press reduction amount is 100 to 200 muli due to conditions such as equipment productivity.
In this case, it is assumed that the bloom size after the thickness reduction still produces fish tilt and overlap from the relationship shown in FIG. The ninth way to avoid such a tail and overlap is to form the end shape into a convex bulge so that the bloom end shape can absorb the material stretched at the surface layer of the material in the post-rolling process. It turns out that this can be avoided by using kudzu. Is it possible that this convex shape of the end of the bloom is possible due to the thickness being reduced by the pair of upper and lower dies 10?Experiments have shown that the amount of bulge depends on the length of the thin end. The results were confirmed.

That is, as shown in Fig. 3, the relationship between the amount of bulge formed when the length of the thinned part is changed stepwise in the range of 50, 100, and 150 mm with the amount of press reduction is approximately 20 om or more, preferably It is understood that a remarkable effect can be obtained by having a thin part length of 250 to 350 mm.

Based on this viewpoint, the inventors of the present invention further studied the optimal die shape for forming a convex bulge at the end. In the die of the form shown, the influence of the inclined surface 12 provided to avoid folding defects during rolling, or the influence of the tip of the caliber 11 that allows the material to flow freely, is due to the influence of the material during press forming. It was clarified that this is due to the fact that the flow does not sufficiently contribute to the convex bulge. For this reason, as shown in Fig. 4, the shape of the die 10 is rounded to prevent the material from flowing backward and to promote the formation of a convex bulge in the forward direction of the material. Form a back-cut protrusion 13 having an appropriate width and height h, or prevent material flow at the tip of the die 10 and create a convex bulge. It is also an effective means to provide a base portion 14 that is inclined forward at an angle θ in order to improve the angle θ.

In order to further promote the formation of convex and shaped bulges, the present inventors attempted to apply back pressure to the material during press molding. This application of back pressure not only applies a positive pressing force to the material toward the die 10, but also simply grips the material to prevent the material from flowing backwards due to the die slope 12 during press forming. In particular, it also includes the use of naturally occurring pressure on the material side. Now, an example of this will be explained with reference to the illustrated embodiment. As shown in Fig. 5, the press reduction amount is 100 mm.
It is understood that if the plume is firmly gripped and the plume is reduced in thickness, the amount of convex bulge increases even if the reduced thickness is short.

In any case, during press forming, it is necessary to smoothly convert the flow of material accompanying forming into a convex bulge at the end, especially during press forming in a direction perpendicular to the pressing direction. It is necessary to strictly control the expansion of In this ninth stage, the shape of the die 1'O should be considered, and an example is shown in Fig. 6. In (a), the lower die 10a is divided into two parts, and the side wall 15 that restrains the side of the plume is formed. The structure is such that the upper die is fitted between the side walls, and when forming the caliber 11 of the lower die tea, the upper die 10b is also formed deeper than that of the upper die 10b. The die shown in (C) has a frame 16 and a regulating member 17 supported by a sliding mechanism 18 on a roller or the like in order to regulate the bulging of the side surface.

Next, when comparing Za with the experimental example of the relationship with the amount of crop loss when the specific press forming process of the present invention is carried out and running, the die shape specifications are shown in FIG. 7 as an example, and the press reduction amount #' Table 1 shows the results when the thickness was set to 1100 mm and the length of the reduced thickness was set to 3QQmm and 400mm, respectively.

Table 1 (Margins below) Using blooms with the end shapes shown in Table 1,
FIG. 8 shows the results of titrating the length of crop loss caused by the grain tail and overlap formed at the edges after repeated rolling passes and 13 passes. As can be seen from this, it is understood that according to the present invention, by applying press processing to the front and rear ends of the bloom, it is reduced to 40 to 55 inches compared to the conventional unprocessed one (4). It is understood that the effect is even more pronounced by providing the back cut protrusion 13 in the form of a die and further increasing the size of the convex bulge by applying back pressure.

FIG. 9 shows an example of the equipment layout when implementing the blooming method of the present invention.

Bloom B is cast by a bloom continuous casting machine 21 and cut into appropriate lengths by a gas cutter 22 to have a good rectangular cross section.
1 or a press device 2 equipped with a pair of upper and lower dies (for example, in FIG. 4) having a shape shown in FIG.
Send it to 4.

After the tip and rear end of the bloom 1 are press-molded until the thickness is reduced to a predetermined shape, the first blooming mill 2S is used to roll the bloom to a predetermined dimension. In order to remove the surface flaws, the surface flaws are removed with a solvent using a hot scarper 7A-26, and the billet is rolled in a continuous rolling mill 27 to a billet with the required cross-sectional dimensions, and then cut to the required size with a shearing machine 28. It is something to do.

As is clear from the above explanation, the formation of fillet tails and oats (-wraps) can be suppressed by press-forming the leading and trailing ends of the bloom produced by the continuous casting process prior to blooming. This makes it possible to significantly reduce crop loss, and improve crop pressure and yield yield, which is extremely effective.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the entrance plate thickness and the amount of end deformation in the rolling of blooming, Fig. 2 is the shape of the die used in the blooming method of the present invention, and Fig. 3 is the result of press working. A diagram showing the relationship between the reduced thickness section and the amount of convex bulge, Figure 4 is a diagram showing another modified example of the die, and Figure 2 shows the relationship between the reduced thickness section and the convex bulge when back pressure is applied. Diagram showing the relationship with quantity, #! 6
The figure shows another modified example of the die, Fig. 1 is an explanatory diagram showing experimental details of the press forming process of the present invention, Fig. 8 is a graph showing crop loss length, and Fig. 9 is a zero-start - is an explanatory diagram showing an example of the layout of equipment when implementing. In the figure, 10 is a die and 11 is a caliber. 12 is an inclined surface, 13Fi is a back cut protrusion, and 14 is a base. Patent applicant: Kobe Steel, Ltd. Figures 5 and 6! 0b19 (a) (b) Figure 7 Figure 8M Figure 9

Claims (1)

[Claims] Ex) When blooming a bloom with a rectangular cross section manufactured by a continuous casting process and having a lateral dimension ratio of 1:12 or more into a billet with a square cross section, the front and rear ends are A pair of upper and lower dies is used to cut the edge S in a range of at least 250 m/wr. A blooming rolling method (2) characterized by reducing the thickness of the bloom to an appropriate thickness while restraining the long sides of the bloom, and press-forming the end portion into a convex bulge to form a 60-inch square image (2). ) Manufactured by a continuous forging process with a vertical and horizontal dimension ratio of 1. When blooming a bloom with a rectangular cross section of L2 or more into a billet with a square cross section, prior to rolling, the long side of the bloom is cut using a pair of upper and lower dies with a pair of upper and lower dies. While restraining and applying back pressure from the bloom rear blade, thin the material to an appropriate thickness, press-form the end into a convex bulge, and then roll. A blooming rolling method characterized by: