JPS6137302A - Method for hot rolling metallic slab in its width direction - Google Patents

Abstract

PURPOSE:To reduce a crop loss at the end of a rolling sheet-material and to improve its rolling yield by setting the width rolling reduction at a slab-biting part larger than a prescribed one to roll the slab reversingly in reversing rolling the slab width by a vertical mill having vertical rolls with calibers. CONSTITUTION:In rolling a slab in the width direction by using vertical rolls 4, 6 with calibers, the fixed length of a slab biting part is rolled under a rolling reduction larger than a prescribed one, and then the slab is reversingly rolled under the prescribed rolling reduction. When the slab is reversely rolled, the formation of a fish tail is remarkably reduced by the rolling conjointly with the effect of the caliber part. Therefore the crop loss of the slab is reduced and its rolling yield is improved.

Description

Detailed Description of the Invention (=) Industrial Application Field The present invention relates to a hot width rolling method for rolling a metal slab in the width direction using a vertical rolling mill, and more specifically relates to a hot width rolling method for rolling a metal slab in the width direction. The present invention relates to a hot width rolling method for preventing the growth of irregularly shaped portions at the leading and trailing ends that sometimes occur.

(b) Conventional technology The feature of the hot width rolling method for metal slabs is that, compared to the conventional blooming method for steel ingots, the roll contact arc length when rolling continuous cast slabs is The ratio of the average plate width and the roll gap shape ratio is as small as 0.1 to 0.2, and the vertical roll width reduction amount per roll is 200 to 3001I+.
For example, something as large as +++. For this reason, irregularly shaped parts called fishtails occur at the front and rear ends of the metal slab, which is the material to be rolled, resulting in crop loss.

Many methods have been proposed to reduce crop loss, which increases with width reduction.

These methods apply the methods and knowledge that have been put into practical use in blooming. For example, a two-sided pass is characterized in that the material to be rolled does not pass through a reciprocating scheduler with a predetermined reduction amount, but reduces the reduction amount by the time it leaves the rolling rolls. A rolling method (Japanese Patent Publication No. 51-35383) and a press forming method (Japanese Patent Publication No. 35383/1983) in which at least one longitudinal end of the material to be rolled is press-formed into a narrow width and then rolled by a subsequent rolling machine 57-81901).

(c) Problems to be Solved by the Invention In all of these conventional methods, the rolling efficiency is significantly reduced. That is, in the double-sided 4-slice rolling method, two rolling cycles are required to reduce the amount of reduction in one rolling process during rolling, and in the press forming process, there is a Downtime is required. Therefore, these methods cannot be applied to a width-reducing vertical rolling mill, which is designed to realize a process that combines the continuous casting process and the rolling process, which can utilize the sensible heat possessed by the continuously cast slab. When manufacturing various slabs from wide slabs to narrow slabs in the width rolling process, which directly connects the continuous casting process and the hot rolling process, it is necessary to have rolling efficiency that matches the capacity of the preceding and following processes, without interfering with the rolling time. It is required to reduce crop loss at the leading and trailing ends of the rolled material.

An object of the present invention is to provide an effective method for hot width rolling of metal slabs that solves the above-mentioned problems.

(d) Means for Solving Problems The above-mentioned object of the present invention is to provide a vertical rolling mill having vertical rolls with a caliber, when reversibly rolling a metal slab in the width direction, the biting end of the metal slab is Hot rolling of a metal slab characterized by rolling with a width reduction amount based on a rolling load value that is more distorted than the rolling load value determined from the distributed width reduction amount of the pass, and rolling other parts to the distributed width reduction amount. Achieved by width rolling method.

(,) Operation The operation of the present invention will be explained below with reference to the drawings. Figure 2 (a
), when the metal slab 1 is rolled in the width direction, deformed end portions called fishtails occur at the biting edges 2 and the biting edges 3.

As a result of the inventors' investigation of the fishtail 3 at the biting end 2 and the biting edge of the metal slab, we found that the biting edge 3 is the biting edge and the fishtail 3 is the biting edge 3, as shown in FIG. 2(b). I learned that it is about 3 times as much. Therefore, it can be seen that the amount of fishtail can be significantly improved by increasing the length of the end rolling leaf when the vertical rolling mill engages the end rolling leaf.

FIG. 3(a) shows an example of the stand configuration of a width reduction mill, in which a horizontal roll 5 (H) is disposed between two stands of vertical rolls 4 (Vi) and 6 (v2). The metal slab is reversibly rolled between stands 4, 5.6.

FIG. 3(b) shows the relationship between the slab width and the number of passes when the slab is rolled with the maximum reduction determined by the rolling load limit. In the figure, ledger slab dimension W. When obtaining the target slab width dimension W, Wl is w2N<Wl<”2N+1
When it is within the range, a reduction amount margin w[w2N+1 occurs. This rolling margin can be varied depending on the purpose, such as when distributing it evenly to smooth out small loads in each quarter, when providing a rolling margin in the initial pass, when providing a rolling margin in the latter pass, etc. Used in various reduction schedules. In particular, a strong reduction schedule in which the reduction margin is not evenly distributed among the nine spaces is often implemented from the standpoint of rolling efficiency.

FIG. 4 is a result of the inventors' investigation of the maximum actually measured load at the biting end and other parts. As a result, it was found that the load at the biting end is lighter than other parts, although the details differ depending on whether the biting shape is rectangular or the dog is single-shaped. FIGS. 1 and 5 show a rolling method according to the present invention using this knowledge.

Figure 1 shows the findings obtained in Figure 4 as vertical roll rolling load values and 1)
This is shown in relation to the amount of vertical roll width reduction in the vertical roll.
In the figure, line 7 is the biting end, line 8 is the part other than the biting edge, and P is the rolling load value with sufficient rolling reduction distributed to each pass, and max is the maximum rolling load value. Fig. 5 shows a specific vertical roll rolling method when the amount of reduction distributed to each pass is the maximum amount of reduction corresponding to the maximum rolling load.In Fig. 5 (&), When rolling the biting end 2 of the metal slab 1 which is the material to be rolled, the maximum rolling amount Δ)I
Rolling is performed by adding a reduction amount Δhmax corresponding to the difference in rolling load between the biting end and other parts to rli & machining, and parts other than the biting edge are rolled with the maximum reduction amount ΔHmax. Furthermore, as shown in FIG. 1, when the distributed rolling reduction amount ΔH is equivalent to P less than the maximum rolling load, when rolling the biting end 2 of the metal slab 1, the biting end and other parts Rolling is performed by adding a rolling load equivalent reduction amount Δh or more, or the maximum rolling load PK at the biting end portion (m & Rolling is performed with the specified rolling reduction amount ΔH. When this metal slab 1 is then rolled in a reverse pass, the rolling reduction amount is ΔH as shown in FIG. 5(b).
max-ΔhmaX amount, and the bite shown by 3& in FIG. 2(,) and the end fissy tail are greatly improved as shown in 3b in FIG. 5(b).

FIG. 6 shows the relationship between the difference in the amount of reduction and the difference in load at the biting end and other parts when the amount of reduction distributed to each pass is the maximum amount of reduction. As is known, the maximum reduction amount Δ
In the case of Hmax, the rolling load does not exceed the rolling load limit even if the reduction amount difference ΔhmaX is added up to 30 ffl and the biting end is rolled. In other words, according to the method of the present invention, it is possible to obtain a larger rolling reduction at the biting end than in other parts, and because the difference in load between the biting edge and other parts is utilized, the rolling time can be reduced even when rolling with the maximum reduction amount. It is possible to implement without hindering crop loss, and crop loss can be greatly improved.

Next, Fig. 7(a) shows an example of a rolling mill equipment for carrying out rolling according to this method.
, shown in (b). FIG. 7(b) is a detailed diagram of the roll opening hydraulic control device 11. When carrying out width rolling of the metal slab 1, the opening degrees of the vertical rolls 4, 6 are set by a roll opening adjustment device 9 and a reduction screw 10 driven via a worm wheel 14). Reduction screen-10
is engaged with the worm wheel 14 and the housing 15 by splines, and the roll opening hydraulic control device 11 allows rolling to be carried out smoothly even during rolling. The stroke of the roll opening hydraulic control device 11 is set to 12 (dog) or 1 based on the set value of j, -10.
By changing to 3 (small), the roll opening degree can be adjusted and the slab width can be changed. That is, by controlling the cylinder stroke at the biting end to 12 degrees and controlling the cylinder stroke to 13 degrees at the other edges, it is possible to increase the amount of reduction at the biting end.

(f) Example Next, an example of the present invention will be described. The rolling conditions are as shown in Table 1. A three-stand reverse rolling method of 65 mm, V, -H-V2 is used to produce a finished slab size of 250 x (585 to 1585) from a continuous cast slab of 280 x 18'OOm. did.

Table 1 Rolling Condition Table 2 shows the crop loss reduction rate of each size when rolling to the maximum rolling reduction. Incidentally, the clog loss reduction rate is the improvement ratio between the case where the biting end and other parts are rolled with the maximum reduction amount and the case where the clog loss is rolled by the method of the present invention.

Note that the method of the present invention utilizes the difference in rolling load between the biting end portion and other portions, and can be applied even when rolling is not performed at the maximum reduction amount.

Examples in this case are shown in Table 3. The comparative method is a case in which rolling is not carried out to the maximum reduction amount, a reduction allowance is provided, and the pressure at the biting end is increased and reduced only by the reduction allowance. In the method of the present invention, rolling is performed by adding a reduction amount corresponding to the difference in rolling load to the amount of pressure increase at the end of the comparative method. The clog loss reduction rate in the table is the improvement rate compared to the case where the difference in the reduction amount is not added between the biting end and other parts, and the rolling from the biting end to the biting end is less than the maximum reduction with sufficient rolling margin. be.

(g) Effects It is impossible to apply the conventional yield-enhancing rolling method to a width reduction mill in a process that directly connects the continuous casting process and the hot rolling process because it significantly impedes the rolling time. According to the method of the present invention, even in rolling under the maximum reduction amount for the purpose of improving rolling efficiency, the rolling load difference between the biting edge and the biting edge is used, so crop loss can be achieved without interfering with rolling time. This brings about a very effective effect in industry, in that the yield rate can be improved significantly.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between the reduction amount and rolling load of the biting end part and other parts, and Fig. 2 (-) (b) is an explanatory diagram of the fishtail amount of the biting end part and the biting end part. , Figure 3 (
IL) (b) is an explanatory diagram of the rolling schedule in the case of reversible rolling in a stand configuration with two vertical rolling mills, Figure 4 is a diagram of the relationship between the maximum measured loads at the biting end part and other parts, Figure 5 (!L) (b) is a detailed explanatory diagram of the present invention, Figure 6 is a diagram showing the relationship between the reduction amount difference and the load difference at the biting end and other parts, and Figure 7 (, ) is the mouth- Le opening hydraulic system,
(b) is a detailed view of the hydraulic cylinder. 1... Metal slab, 2... Biting end fishtail, 3a... Biting out is end fishtail, 3b... Improved biting is end fishtail, 4... Vertical rolling roll (V
, mill), 5... horizontal rolling roll (H mill), 6...
・Vertical rolling mouth (V2 mill), 7...Load on parts other than the biting end, 8...Load on the biting end part, 9...
Roll opening adjustment device, 10...pressure sufu'Jz-1l
l... Roll opening hydraulic control device, 12.13... Stroke. Fig. 1 Amount of width reduction given by 1/6th Fig. 4 (Ton) Fig. 6 4.6

Claims (1)

[Claims] When a metal slab is reversibly rolled in the width direction using a vertical rolling mill with vertical rolls equipped with a caliber, the biting end of the metal slab is set at a rolling load value that is greater than or equal to the rolling load value determined from the distributed width reduction amount of the relevant pass. 1. A method for hot width rolling of a metal slab, characterized in that the metal slab is rolled with a width reduction amount based on the width reduction amount, and other parts are rolled with the distributed reduction amount.