JPS59118204A - Production of unevenly thicked steel plate - Google Patents

Abstract

PURPOSE:To flatten one side with ease by cambering upward the one surface at low curvature to concentrate stepping only on the other side at the point of the time when rolling is completed. CONSTITUTION:A material 1 to be rolled is subjected to ordinary rolling at a uniform thickness t1 over the entire part. A roll gap is set to a desired thickness reduction, i.e. thickness t2 is set and the material is rolled in the succeeding pass. Steps S1, S2 are formed on both sides as shown in (a) in the figure until the length (l) of reduced thickness rolling measured from the point of the time when the material is fitten coincides with the prescribed value and thereafter the rolling rolls are rotated reverse and fiting-back is performed. A lower rolling roll 3 is lowered so that the level of the rolling and working surface thereof exhibits DELTAX with respect to the level 4 of the conveying surface of the roller tables before and behind the mill to put the material under the three-point bending effect generated by the table rolls 5, 5' before and behind the mill sandwiching the roll 3 adjacently thereto, in the stage of said intermediate fiting-back.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a method of rolling a steel plate with a difference in thickness,
Here, the monthly thickness steel plate is the middle of the plate in the longitudinal direction.
It refers to a steel plate with different thicknesses, with one side being virtually flat and the opposite side having an inclined step, and the plate thickness being different before and after the step.

(Problems with the conventional technology) Regarding the manufacturing method of this kind of thick steel plate, the conventional
-24898, 24899 and Special Publication Sho 51-
45545, etc., the roll gap is partially opened during the rolling material biting in the final pass of rolling, or by simply biting back halfway, a vertically symmetrical differential thickness steel plate is created, and the roller table thereof is It is explained that by conveying the upper surface, the difference in thickness on the back surface is eliminated, and the inclined steps are concentrated only on the other surface facing the back surface.

However, the expectation that such a method will eventually flatten one side of the trench skein is lacking theoretical support, and at least the steel plate finishing temperature, rolling thickness, finishing rolling direction, etc.
It is unavoidable to be subject to the following restrictions.

(Object of the Invention) In order to avoid the above-mentioned restrictions, the present invention creates an upside-down shape with a gentle curvature on one side at the time of completion of rolling, and concentrates the steps only on the other side. The purpose of this invention is to provide a new rolling method that can easily achieve single-sided flattening.

(Motivation of the Invention) Normally, during flat plate rolling, the side cross section of the material to be rolled during rolling from the roll bite inlet to the outlet has a vertically symmetrical geometrical relationship.

Therefore, even in the differential thickness rolling as described above, vertically symmetrical steps on both sides are formed as intermediate thickness tapered regions corresponding to the shape of the roll bit.

In order to concentrate the double-sided step in this area on the other side and flatten the other side, we have found that it is convenient and appropriate to bend the tapered area either upward or downward. .

In other words, the vertically symmetrical double-sided step 1S shown in Fig. 1(a)
□, differential thickness steel plate p with l1r2! is supported by a pair of anvils a, , and a2 as shown in the same figure ('b), and when one step s1f is pressed by a hydraulic press, XL, for example,
The other step S is formed into a curved surface C that is almost smooth across the front and back as shown in the same figure (cl), and then press-worked for slight correction so that the curved surface C becomes flat, resulting in the difference thickness steel plate in the same figure (d). p' is obtained.

In this case, the illustrated dimensions 1. -12±-?→-+Hakko41
It was learned that the difference in thickness Δt, shown by →, and the intermediate thickness taper part length are hardly affected.

However, such cold working using a press increases the number of handling steps, and therefore increases the number of man-hours and time, resulting in problems in terms of cost. Therefore, in the present invention, the above-mentioned correction measures are incorporated into the hot rolling of all thick plates. We have established a reliable manufacturing technology for steel plates with variable thickness, which is not subject to restrictions such as steel plate finishing temperature, rolling thickness, and finish rolling direction, as was the case with conventional methods.

(Structure of the Invention) The present invention provides a steel plate having a different rolling thickness between the front and rear sides through an inclined step in the middle in the rolling direction between one flat side and the opposite side in the rolling direction. When processing, firstly, the entire material to be rolled is rolled to a uniform thickness, and then a roll gap is set to achieve the desired thickness reduction in the next bath, and then the material is rolled in this roll gap. When the length of the reduced thickness measured from the point of biting of the rolled material matches the target length, the rolling rolls are reversed, and the middle (4) half-bite back is fully carried out. Lower the rolling roll to a position where its rolling operating surface level is equal to or lower than the level of the roller table conveyance surface before and after the mill,
Under the 8-point bending action caused by the table rollers before and after the mill and the upper roll that are adjacent to and sandwich the lower roll, an upward curvature bend occurs in the roll bite area of the rolled material across these table rollers. This is a method of rolling thick steel plates that combines deformation and a curved shape with gentle curvature on one side. It is a recommended embodiment that the thickness reduction extension is by repetition up to the commanded thickness.

This invention first performs normal rolling to a uniform thickness t□ throughout the rolled material 1, and then sets the roll gap to achieve the desired thickness reduction, that is, the thickness t2, in the next bath. Steps (S11 S2)' are formed on both sides as shown in FIG. At the time when the thickness reduction extension length l matches the target length, the rolling roll 2.3 is completely reversed to complete the mid-way biting back, and in particular, during this mid-way biting back, the lower rolling roll 8 is adjusted so that its rolling operating surface is at the level shown in FIG. As shown in the figure, the table rollers 5 before and after the mill are lowered as shown by ΔX in the figure to a position equal to or lower than the conveyance surface level 4 of the roller table before and after the mill, and are adjacent to the lower rolling roll 3 and sandwich it. , 5' above and
Eight-point bending reaction force F , F (F=F, +F
, ), an upwardly curved bending deformation is applied starting from the roll bite region 6 of the rolled material 2 to be pressed, and a forced upwardly curved shape 71 is produced on the other surface. Although this upwardly curved shape 7 is shown in an exaggerated manner in FIG. 8(a), it can normally be corrected to a flat shape 7' as shown in FIG. Of course, correction may be forced by returning the lower rolling roll 3 to the rolling position and applying light rolling.

In this way, the desired thickness difference (t□-12) is formed on the other surface, that is, on the upper surface side.
is almost concentrated, and the length of the differential thickness part ltx is 50 to 100.
・Our comparatively sharp monthly thickness steel plate p' will be manufactured in an as-rolled state, and the aforementioned cold pressing is of course completely unnecessary.

The degree of concentration on the other surface, that is, the top surface, is determined by the surface difference thickness ratio 11tU7Δt (where ΔtU: step difference on the top surface, Δt: required thickness difference (1, −12), therefore, the concentration remains on one side that is virtually flat. The difference in level is ΔtL,°.

Assuming that (11-12)=(Δtu+ΔtL), there is a relationship shown in the following equation for the above-mentioned lowering formula ΔX of the lower rolling roll 8.

ΔtU/At, = f (tl 'ΔX) Regarding this relationship, some actual rolling experiments were conducted, although the number of N was small, and it was found that the tendency shown in FIG. 4 was shown.

That is, in the figure, to is to. -10~20
m, t11 = ao~4θ device, tl, = 5
For the three types of rolled materials subjected to uniform thickness rolling of 0 to 60 degrees, a roll gap that gives a constant difference thickness Δt = ΔtU + HA L was set, and the lower roll 3 lowering method during the above-mentioned midway chewing was performed. By changing Δχ in various ways according to Δt and taking it on the horizontal axis,
The effect on ΔtU/Jt is investigated.

As shown in the figure, the thicker the original thickness t0, the higher the surface difference thickness ratio ΔjVΔt can be obtained with a small ΔX. Also, ΔtU/l
The total t reaches about 0.8, and a virtually flat surface can be obtained. It is clear that the closer to ΔxfΔt, the higher the surface difference thickness ratio can be.

This invention does not require any new additions to the rolling mill or rolling mill control compared to conventional rolling mills, and it is possible to simply lower the lower rolling roll during the entire metal-in process in the existing thick plate rolling mill during half-way chewing. It is sufficient to have a function to detect the thickness reduction extension after metal-in with high accuracy, and it is sufficient to have a plate length tracking sensor based on the rotation speed detection of the rolling roll.

In addition, regarding the rolling finish temperature in normal rolling (!:
Similarly, it is possible to roll at any temperature in the range of K 650' to 100°C, and there is no need to place any special restrictions on the rolling direction of the finishing bath, and in terms of size, the plate thickness is extremely thin, 12.5J1m or less. There are no particular restrictions except for.

In this invention, the roll gap is set to directly aim at the thinner commanded thickness t2 after finishing the plate to the thicker thickness t1.
2, a plurality of buses may be subjected to thickness reduction rolling.

Next, at the point when the thickness reduction extension matches the target length, the rolling rolls are completely reversed and when performing mid-way biting back, the roll gap is maintained from just before that, and
) It is more desirable, and At this time, during biting back, the length of the upwardly curved portion can be shortened by restoring the positions of the upper and lower rolling rolls at the time when the lowering is forced.

Up to now, we have explained the case where there is one stage of difference in thickness, but even if the number of stages of difference in thickness is two or more, after the thickness reduction rolling at t, the thickness reduction in the next stage which is thicker than that in the next stage. Rolling may be repeated.

In either case, it is clear that the method can be used to roll steel plates with a difference in thickness on one side without any particular restrictions on finishing temperature, rolling direction, etc.

EXAMPLE FIG. 5 shows several examples of actual rolling results according to the method of the present invention.

Continuously cast slabs with a thickness of 220 mm are rolled by normal rolling to thicknesses tlt of 30 mm, 25 mm, and 15 mm, respectively, and then reduced thickness t is 20 mm, 18 mm, respectively.
] Set the roll gap so that the roll gap is 0, and roll at the normal rolling speed (roll diameter 12001+Im, roll rotation speed 2 Or, p, m), and the thickness reduction rolling extension meets the target value. At this point, the rolling roll is completely reversed and when performing mid-way biting, the lower rolling roll is moved so that its rolling operating surface level is approximately 10 mm and 5 mm below the level of the roller table conveyance surface at the front and rear of the mill, respectively. The curved truntable is lowered to the position where
), (b), (c) Monthly thickness steel plates with VC were manufactured. As shown in the figure, it can be seen that the desired thickness difference is concentrated on the upper surface side and is almost flat on the lower surface side.

As described above, according to the present invention, a steel plate having a flat thickness on one side and having a desired thickness completely concentrated on the other side can be easily manufactured using existing rolling equipment.

[Brief explanation of drawings]

FIG. 1(a) is a perspective view of a steel plate with different thickness on both sides, and FIG. 1(b) is a perspective view of the steel plate. (0) and (CI) are schematic diagrams of the process of processing a differentially thick steel plate by cold pressing, Figure 2 is an explanatory diagram of the method of forcing bending deformation during biting back in the middle of rolling according to the present invention, and Figure 3 ( al, O)l is a side view of the warped steel plate showing the warped shape and its correction after biting back during rolling, and Fig. 4 is
5 is a graph showing the influence of the lowering of the rolling working surface level ΔX of the lower rolling roll on the surface difference thickness ratio of a steel plate of different thickness, and FIGS. 5(a), (b), and (C) show the monthly difference according to the present invention. FIG. 3 is a side view showing several examples of thick steel plates. Patent applicant: Kawasaki Steel Corporation Figure 1 <C> (d) Figure 2

Claims (1)

[Scope of Claims] L: In processing a steel plate with different thicknesses, in which the finished thickness of the front and back rolls differs through a step that is inclined in the middle of the rolling direction on one flat side and the other side facing each other through thick plate rolling. First, the material to be rolled is rolled to a uniform thickness throughout, and then the roll gap is set to achieve the desired thickness reduction in the next pass.Then, the material to be rolled in this roll gap is At the point when the thickness reduction extension measured from the point of rolling matches the target length, the rolling rolls are reversed and half-way biting back is performed; The surface level is lowered to a position that is equal to or lower than the conveyance level of the roller table before and after the mill, and 8 points are generated by the table rollers before and after the mill, which are adjacent to and sandwich the lower roll, and the upper roll. A method for rolling a steel plate with a difference in thickness that combines the following steps: under bending action, an upwardly curved bending deformation is induced in the roll bite area of the rolled material across these table rollers, and an upwardly curved shape with a gentle curvature is induced on one side. . 2. The method according to 1, wherein the thinning and rolling extension is based on a plate length tracking sensor based on the rotational speed detection of the rolling roll. & The method according to any one of 1.2, wherein the thickness reduction rolling is repeated until the commanded thickness is reached.