JPH0671602B2 - Method of rolling thick plate material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for rolling a thick plate material having a material thickness of more than 50 mm and a final finishing length shorter than a roll cylinder length of a rolling mill. Is.

(B) Conventional technology As shown in FIG.
It consists of two processes. In other words, there are three stages: forming pass 1, width-passing pass 2, and finishing pass 3. This is done regardless of the thickness, width and length of the rolled sheet.

However, in the case of thick materials exceeding 50 mm, the third pass
As shown in the figure, small waves (also called local strain) are generated in the plate biting portion, resulting in poor flatness, which often goes through the press correction process.

The cause of this wavelet is, as shown in FIG. 4 (A) to (D) over time, a table arranged on the upper surface of the lower work roll 11 of the rolling mill 10 and on the outlet side of the rolling mill 10. Laura 12
Is considered to be at an arrangement (pass line height) ΔT between the upper surface and the upper surface. That is, as the height of the pass line of the tip portion 131 of the material 13 immediately after the roll is bitten is large, the rolling reduction is different between the front surface and the back surface of the material, and tends to warp (B).
After that, it collides with the table roller 12 (C) and is pushed and bent (D).

Conventionally, as a method of eliminating this small wave, there have been a method of performing strong reduction rolling at a low speed in the final pass, and a method of changing the pass line height according to the rolled material.

In the former strong reduction rolling method, low-speed strong reduction rolling is performed in the final pass, so problems such as seizure occur when the conventional backup roll roller bearing is an oil film bearing. For this reason, it is necessary to modify it into a rolling bearing, which has a drawback of increasing equipment cost. Further, since low speed rolling is performed, there is a drawback that the rolling work efficiency decreases.

The latter pass / line adjusting method has a drawback that a device capable of freely changing the pass / line height is required, and the equipment cost is also high as in the former case. Since it is necessary to change the pass / line height for each pass, it takes time to set the pass / line height, and the rolling work efficiency also decreases.

(C) Problems to be Solved by the Invention A problem to be solved by the present invention is to obtain a method for efficiently rolling a thick plate material without remodeling existing equipment.

(D) Means for Solving the Problems In the method for rolling a thick plate material of the present invention, a thick plate material having a material thickness of more than 50 mm and a final finish length shorter than a roll cylinder length of a rolling mill is rolled. In order to solve the above problems, the thick plate material was formed into a finished length in the pass immediately before the final pass, and the material was rotated 90 degrees in the final pass to complete the tenter. There is.

(E) Example As shown in FIG. 1, in the method of the present invention, after performing a normal rolling method (forming pass 1, tentering pass 2, finishing pass 3), tentering finishing pass 4 is performed. Before the tentering finishing pass 4, the thick plate material is formed into a finished length.

In tentering finishing pass 4, the material is first rotated 90 times,
Next, rolling is performed so that the width and the intended thickness are obtained. Therefore, the finished length of the material must be within the length of the rolling mill roll. It must also be within dimensions that satisfy the turn constraints of the turntable. A specific method for satisfying such a condition will be described below.

<Regarding Method of Determining Width Width Correction Factor α> α may not be too large or too small. In the middle, there should be an appropriate value depending on the size of the rolled material.

According to the experience of the present inventors, it has been found that for a thick product having a thickness of 50 mm or more, if the final load is set to be 500 to 1500 tons, the small wave disappears.

Further, the load varies depending on the final finish length. This is because the rolling width is reached when the material is turned 90 times. According to the experience of the present inventors, the final load R _L is the finishing target length.
0.35 times L _F is suitable.

Reduction amount ΔhL to set the load of the final width aiming path to P _L
The following equations (1) and (2) are obtained from the Sims equation.

Where kf _{m is the} deformation resistance. Q _P: rolling force function R: work roll radius. L _F : Rolling width (1) Forming pass This pass is the same as the conventional rolling method. A pass for adjusting the shape of the slab and accurately recognizing the thickness, and the amount of reduction is determined so that the maximum efficiency is obtained within the constraints of the rolling mill.

(2) Width-out pass This pass determines the target thickness H _A of the final width-out pass. When the thickness during molding path ends H _B width W _B final rolling aim width W _A,
Normally, the aiming thickness H _{A for the} final pass is calculated from the following equation (3).

H _A = H _B × W _B / W _A (3) However, in the method of the present invention, the width is squeezed out in the final pass, so the final target thickness H ′ _A of the shunting pass is expressed by the following formula (4). Desired.

However, α: Width correction coefficient Reduction distribution is the same as the conventional one.

(3) Finishing pass In this pass, it is the usual method to determine the distribution so that the final finish thickness H _A is reached. However, in the method of the present invention, the final target thickness H _F of the finishing pass is the final target thickness H ″ _A ,
When the target width is W _A , it can be calculated by the following equation (5).

When the aim of the finishing pass is decided so as to become the formula (5), the length of the material reaches L _F.

(4) Final tentering finishing pass The material is turned 90 ° again, tentering again, and rolled to the desired thickness.

Small waves at the tip of the material can be eliminated with the final tentering finishing pass. The reason is not clear quantitatively. According to the experience of the present inventors, it is known that the larger the small wave, the less likely the warp is to occur. If the load is too large or too small, the wavelet will not disappear. Therefore, it is considered that the rolling that does not generate the small wave can be performed even in the final pass because the force that corrects the small wave and the force that tends to warp are appropriately balanced.

(F) Concrete examples Slab dimensions: thickness 250 mm x width 1800 mm x length 1870 mm Product dimensions: thickness 100 mm x width 2200 mm x length 3800 mm Determination of α is, the plate aim length L _F when finishing is for 3800 mm, the final load P _{L is, P L = 3800 × 0.35 =} 1330to
n. Therefore, kf = 8kg / mm ² Q _P = 1 and R = 500
Then, from the formula (2), the reduction amount Δk _L is about 2.9 mm. Substituting H _F = 102.9 and H ″ _A = 100 into equation (5) gives α
= 0.028 is obtained.

Therefore, in equation (4), α = 0.028, H _B = 200, W _B = 1800, W _A
The final aim thickness = 2200 substitutes the tentering path H _'A is 168.
It will be 4 mm.

According to the conventional method, 30 rolled products were rolled, and according to the method of the present invention, 30 rolled products were rolled in each of the above-mentioned pass schedules, and the press correction process was carried out due to the generation of small waves. In the case of the conventional method, 20/30 = 67%, and in the method of the present invention, 0/30 = 0%.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of the rolling method of the present invention. FIG. 2 is a schematic explanatory view of a conventional rolling method. FIG. 3 is a perspective view of a rolled material in which small waves are generated. FIG. 4 is an explanatory view showing a process in which a small wave is generated at the tip of the rolled material. 10: Rolling mill, 11: Lower work roll 12: Table roller, 13: Plate material 131: Tip

Claims (1)

[Claims] 1. When rolling a thick plate material having a material thickness of more than 50 mm and a final finishing length shorter than a roll cylinder length of a rolling mill, a normal forming pass, a tenter pass and a finishing pass are performed. That the thick plate material is formed into a finished length in the pass immediately before the finishing final pass, the material is rotated by 90 degrees in the finishing final pass, and the finishing length is multiplied by a value obtained from past operations. A method for rolling thick plate material, characterized in that the final tentering is completed by.