JPS6012122B2 - How to improve crop in hot strip mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for minimizing the amount of crop that inevitably occurs in strip rolled in a hot strip mill.

In hot strip mill rolling, width reduction rolling is performed using vertical rolls in the rough rolling process, which is the preliminary stage, so a dog-pawn-like thickening is formed along both edges of the rolled material. with a tendency to be

For this reason, at the top or bottom portion of the strip after finish rolling in the downstream process, the above-mentioned excess thickness is extruded in the rolling direction, resulting in a fish-till-shaped crop as shown in FIG. Originally, the cropped part was cut with a crop shear to adjust the shape of the finished product, but in this case, the amount of cropping is relatively large, so the crop length IF that needs to be cut becomes large, and the progress of the finished product is reduced. There was a drawback that led to a decline in crab quality. For this reason,
Conventionally, methods have been used to limit the amount of reduction during width reduction to minimize the generation of excess thickness, or to increase the amount of reduction in the center of the rolled material by making the roll shape trapezoidal during rough rolling. Ta.

However, when the width limit is applied, the frequency of mold changes increases, and at the same time the rolling wheel becomes smaller, which reduces rolling efficiency.In addition, in the method using trapezoidal rolls, It is not very effective because it cannot respond accurately to changes in the temperature, and furthermore, in the case of tenter rolling, the crop becomes tongue-shaped (the center part is convex and protrudes for a long time). This method has the disadvantage that a considerable amount of cropping is required, and it does not necessarily lead to improved walking performance. Therefore, an object of the present invention is to eliminate the drawbacks of these conventional methods, and to provide an improved method for reducing the amount of cutting based on clots to a maximum of 4.0, in order to improve the rolling process. .

A feature of the present invention is that the shape of the pair of upper and lower rolls is formed into a predetermined shape in a predetermined stand of the rough rolling process, which is a pre-process of finish rolling, and the width of the rolled material is Accordingly, the combined position of the rolls is moved in the axial direction for rolling, and as a result, it is possible to minimize the amount of cropping that occurs in the strip after finish rolling.

The method of the present invention will be specifically explained below.

In the method of the present invention, flat rolls are not used in the rough rolling stage, and as shown in FIG. are assembled in opposite directions, and the part formed by the combination of the flat parts of the upper and lower rolls corresponds to the center part of the rolled material d, and the flat part of one roll and the boopa part Cp of the other roll are combined, respectively. The portion to be formed is rolled in correspondence with both edges of the rolled material d.
Therefore, as shown in Fig. 3, the cross-sectional form of the rolled material d during rough rolling is such that the central part is flat on both the upper and lower surfaces, and the tapered thick parts d' are formed in opposite directions at both edges. When it is formed, it becomes. In the method of the present invention, the dimension W of the tapered part and the dimension W2 of the flat part are determined according to the width W of the rolled material d or the amount of reduction at the time of width reduction.
is adjusted and set to a ratio that minimizes the amount of cropping in the strip that has completed downstream finish rolling.

Therefore, as shown in FIG. 4, a clock detector F is installed between the roughing stands, on the output side of the final rough rolling stand or the final finishing stand E to detect the crop amount IF of the strip after rolling. is sent to control device G,
The amount of deviation S (see FIG. 2) when the rolls R of the rough rolling stand are assembled is adjusted based on a preset reference value. In carrying out the method of the present invention, it is necessary to support the roughing roll R so that it can be adjusted and moved in the axial direction.

As a roll structure for this purpose, for example, a rolling roll having a movable sleeve as shown in FIG. 5 is used. The configuration of this roll with movable sleeve is arbor 1.
1, a roll body 12 fixed to the outer periphery of the roll body 12, and movable sleeves 13 arranged on the outside of the roll body 12 so as to be movable in all directions. and is rotatably supported by the chock 17. An annular pressure chamber 14 is formed between the arbor 11 and the roll body 12, and a hydraulic passage 11i provided in the arbor 11
The pressure fluid can be supplied from the pressure booster 15 through the pressure booster 15. Therefore, when the pressure value in the pressure chamber 14 is low, the movable sleeve 13 is easily moved in the direction of the koji, so the position is adjusted by the cylinder 181. After the adjustment, the pressure value in the pressure chamber 14 is increased by the expansion device 15, the roll body 12 is expanded in the outer circumferential direction and attached to the movable sleeve 13, and the movable sleeve 13 is prevented from moving and fixed in position. Set the amount of deviation S. As the structure of the rough rolling roll R, another structure as shown in FIG. 6 can also be used.

This roll structure rotates both ends of the mandrel 21.
The support member 22 having the joint 23 is tilted to support the chock 241 so as to be rotatable, and the mandrel 21 and the rotary joint 23 are connected and disconnected by hydraulic pressure, and the mandrel 21 can be slightly displaced in the axial direction when not connected. It's like this. The outer peripheral surface of the mandrel 21 is tapered at an angle of 8 over the entire surface, and a sleeve 25 having a bouper surface that fits this taper formed on the inside is iron-fitted to the outside of the mandrel 21. A movable sleeve 26 forming a roll surface is further iron-coupled to the outer periphery of the sleeve 25.
It is made to be able to be displaced by the cylinder 26. In this structure, by displacing the mandrel 21 in all axial directions by hydraulic pressure, the sleeve 251 exerts a wedge action to fix the position of the movable sleeve 6.

As shown in FIG. 7, the sleeve 25 is divided into a plurality of parts in the circumferential direction and does not move in the axial direction.

According to the roll configuration described above, the combination of the upper and lower coarse rolls R can be set at a desired position depending on the width of the rolled material.

For example, when performing width reduction of 5 ribs, W, is 200 ~
Set the length to 40 ribs, and set the t to 2 to 6 ribs. To explain the effect when rough rolling is performed with the rolls combined in such a state using Fig. 2, the rolling force of the roll R applied to the rolled material d is mostly applied to the flat central part d''. , only this part is rolled strongly, and the taper Cp of the roll surface C
The material flows, and tapered thick portions d' are formed at both edge portions of the rolled material d.

At this time, the top or bottom portion of the rolled material d becomes tongue-shaped. If the normal thickness reduction of the rolled material is continued from this state, the thick part d' of the rolled material d will be reduced more strongly than the flat part, and eventually it will become as shown by the solid line in Figure 8. Become top or bottom shape.

In the rolling method of the present invention, since the central portion is rolled strongly, some cropping occurs in the central portion of the strip as well.

That is, as shown in FIG. 8, the cropping pattern is such that less cropping occurs on both edge sides, and a slight cropping occurs in the center instead. For this reason, the length direction of the entire top or bottom part with cropping is made uniform, and the amount of crop cutting 1 for trimming can be kept to a minimum compared to the conventional case (IF). be able to. As described above, according to the method of the present invention, the cropping amount of the strip in the hot strip mill can be reduced and the product yield can be improved, resulting in an improvement of 0.1%. Further, the roll used in the present invention can also be used as a normal roll by using only the flat portions of the upper and lower rolls.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing a cropped form of strip in a conventional hot strip mill. FIG. 2 is a front view showing the roll combination state of the method of the present invention. FIG. 3 is a cross-sectional view of a rolled material during the rolling process according to the present invention. FIG. 4 is a drawing schematically showing a control form of the method of the present invention. Fifth
The figure is a cross-sectional view showing an example of a roll structure used in carrying out the method of the present invention. FIG. 6 is a cross-sectional view showing another embodiment of the oar structure used for carrying out the method of the present invention. FIG. 7 is a perspective view of the sleeve in FIG. 6. FIG. 8 is a plan view showing the cropped form of the strip obtained by the method of the present invention. R: rough rolling roll,
d: rolled material, F: clot detector. Figure 'Figure 3 Figure 2 Figure 4 Figure J Figure 6 Figure 7 Figure a

Claims (1)

[Claims] 1. In a hot strip mill in which a rolled material is roughly rolled by a rough rolling stand and then finished rolled by a finishing rolling stand, one end of the roll surface is gradually shrunk toward the end surface. using a rolling roll having a tapered portion with a radial slope as a rough rolling stand;
The tapered portions of the upper and lower rolling rolls are assembled in opposite directions, and the axial position of the roll surfaces is movable and adjustable, and the flat portions of the upper and lower rolling rolls face each other. A crop improvement method in a hot strip mill characterized in that the setting is changed according to the strip width or width reduction amount of the rolled material.