JPH0351481B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) In this specification, regarding the rolling of metal sheets, such as steel sheets, using a six-high rolling mill with intermediate rolls between the work rolls and reinforcing rolls, the work rolls and the intermediate rolls are A rolling method that advantageously aims to reduce the contact pressure generated between rolls,
We will describe the results of our development research on this topic. In recent years, there has been a demand for rolling that maintains appropriate thickness accuracy and flatness of plate materials. The causes of defects in the thickness distribution in the width direction (plate profile) or flatness of the plate material are (1) elastic deformation such as deflection and flattening of the rolls of the rolling mill, and (2) progress of rolling. (3) The diameter along the roll body length (roll profile)
Examples include changes in . In consideration of the above-mentioned causes, a rolling mill, for example, a six-high rolling mill, has been developed to avoid deterioration of the plate profile and flatness. (Prior art) A six-high rolling mill has three upper and lower rolling mills that are provided with an intermediate roll that is in contact with both rolls between a work roll and a reinforcing roll.
It is a twin rolling mill, which reduces the vertical bending constraint of the work roll by moving the intermediate rolls axially in opposite directions, increasing the effectiveness of the work roll bender and ensuring proper plate profile and flatness. It also suppresses changes in plate profile and flatness due to changes in rolling load. Further, Japanese Patent Publication No. 7635/1983 discloses that the work roll is moved in the axial direction together with the intermediate roll to enhance the effect of optimizing the sheet profile. In other words, both the intermediate roll and the work roll are moved close to the edge of the strip width of the material to be rolled, or the intermediate roll is fixed at an appropriate position from the viewpoint of optimizing the strip profile and flatness, and the work roll is moved close to the edge of the strip width of the material to be rolled. Move accordingly to reduce wear and thermal crown. This operation suppresses changes in the roll profile and restricts the sheet width that is normally done, such as rolling from widest to narrowest and not reversing the width, and restricts the amount of continuous rolling of material of the same width. The effect of alleviating this is great. As described above, there are various effective ways to use the six-high rolling mill, but the contact pressure between the rolls may become extremely high due to the movement of the rolls. In particular, in the case of strong reduction rolling and thin plate rolling of difficult-to-roll materials, which have been in high demand in recent years, the rolling load increases, so the contact pressure between the rolls increases, especially at the ends of the intermediate rolls,
The work rolls and reinforcing rolls that are in contact with the rolls may become rough, and spalling may also occur. (Problems to be Solved by the Invention) In addition to optimizing the plate profile and flatness of a material to be rolled, it is desirable to provide a rolling method that enables control of the roll profile by reducing the contact pressure between rolls. This is the object of this invention. (Means for Solving the Problems) This invention provides a pair of upper and lower work rolls and an intermediate roll each having one end tapered and ground, and a pair of reinforcing rolls between the intermediate roll, the work roll, and the intermediate roll.
Work rolls and intermediate rolls are assembled in this order in an alternating arrangement of the tapered grinding, and the work rolls and intermediate rolls are moved axially in opposite directions to each other to position the width end of the plate of the material to be rolled inside the tapered grinding end. , characterized in that rolling is performed with a roll arrangement such that the length from the center of the plate width of the material to be rolled to the tapered grinding boundary of the work roll is equal to the length from the center of the plate width to the tapered grinding boundary of the intermediate roll. A method of rolling plate materials, and a pair of upper and lower work rolls and intermediate rolls each with tapered grinding on one end.
An intermediate roll, a work roll, a work roll, and an intermediate roll are assembled in this order between a pair of reinforcing rolls in an alternating arrangement of the tapered grinding, and the work roll and the intermediate roll are moved axially in opposite directions to be rolled. The width edge of the material is located inside the tapered grinding edge, and the length from the center of the plate width of the rolled material to the tapered grinding boundary of the work roll is equal to the length from the center of the plate width to the tapered grinding boundary of the intermediate roll. This method of rolling plate material is characterized in that the roll arrangement is such that the work rolls are cyclically shifted. Now, FIG. 1 shows a six-high rolling mill according to the present invention. The 6-high rolling mill has a pair of upper and lower work rolls 1A,
1B and intermediate rolls 2A, 2B as reinforcing roll 3
Intermediate roll 2A and work roll 1 are placed between A and 3B.
A, a work roll 1B, and an intermediate roll 2A are arranged in this order. The work rolls 1A and 1B each have a tapered grinding part 4 at one end thereof, and similarly, an intermediate roll 2
A and 2B also have a tapered grinding part 5 at one end thereof,
Work rolls 1A, 1B and intermediate roll 2 are arranged so that these tapered grinding parts 4, 5 are arranged alternately.
A and 2B are assembled into the mill housing 6 of the rolling mill. Also, when installing, work rolls 1A, 1
B and intermediate rolls 2A, 2B can be shifted in the axial direction. 7 and 8 are bearing chocks for the upper and lower work rolls, and 9 and 10 are spindles for the upper and lower work rolls 1A and 1B, respectively, which have a spline structure for torque transmission. Further, 11 and 12 are bearing chokes for the intermediate roll. Although the device for moving the upper and lower work rolls 1A, 1B in the roll axis direction is not shown, it may be installed around the work roll bearing chocks 7, 8, for example, on the extensions of the spindles 9, 10. It may be installed around the gearbox, and the movement method may be hydraulic, transmission, or magnetic. 13 is a balance device for the work rolls 1A, 1B or a roll bending device for increasing, and 14 is a roll bending device for decreasing. 15 and 16 are reinforcing roll jocks for the upper and lower work rolls 1A and 1B, and 17
is a bearing, and 18 is a reduction screw. Although this example shows a work roll drive system, the drive system may be intermediate roll or reinforcing roll drive, and the left-right relationship of the tapered grinding areas of the upper and lower work rolls may be reversed from this example. When rolling the material to be rolled 19, the work rolls 1A and 1B are moved in opposite directions, and the intermediate rolls 2A and 2B are moved in a direction opposite to the moving direction of the work rolls 1A and 1B that are in contact with each other, and the material to be rolled is rolled. Length X ₁ from the plate width center C of No. 19 to boundary 20 of tapered grinding portion 4 of work roll 1A (1B), and similarly length X to boundary 21 of tapered grinding portion 5 of intermediate roll 2A (2B) Set the roll arrangement so that ₂ is equivalent (X ₁ = X ₂ ). Also, from the above roll arrangement, work rolls 1A, 1
By cyclically moving only B within a predetermined movement range, width return rolling can be advantageously achieved. (Function) Next, the contact pressure generated between the work roll and the intermediate roll and the roll arrangement will be described. By the way, since the center of the plate width of the rolled material 19 is generally aligned with the center of the body length of the reinforcing rolls 3A, 3B, the above lengths X ₁ and X ₂ are measured from the ends of the reinforcing rolls 3A, 3B to Length X ₁ to tapered grinding part boundary 20 of rolls 1A, 1B and similarly tapered grinding part boundary 21 of intermediate rolls 2A, 2B
Can be replaced by length x ₂ . Here, the length from the reinforcing rolls 3A, 3B to the tapered grinding part boundary 20 or 21 is called the shift amount. Therefore, in order to realize the roll distribution of X ₁ = X ₂ , the shift amount x ₁ and the shift amount Therefore, _{the relationship between the shift amounts x 1 and} x ₂ and the contact pressure between the rolls will be explained below. First, if we approximate the distribution of contact linear pressure in the trunk length direction between the work roll and the intermediate roll and between the intermediate roll and the reinforcing roll to a straight line, we can find that the contact points B, D, E, and G between each roll in Fig. 1 are approximated as straight lines. The linear pressure of is expressed by the following formula. Note Linear pressure at point _B P B P _B = F / B _R・ 1-4Z ₁ +4Z ₁ Z ₂ -2Z ₂ ² +2Z ₁ ² / (1-2Z ₁ ) (1-2
Z ₂ ) (1-Z ₁ -Z ₂ )...(1) Linear pressure at point D P _D P _D = F/B _R・ 1-4Z ₂ +4Z ₁ Z ₂ +2Z ₂ ² -2Z ₁ ² /( 1-2Z ₁ ) (1-2
Z ₂ ) (1-Z ₁ -Z ₂ )...(2) Linear pressure at point E P _E P _E = F/B _R・1-2Z ₂ ² /(1-Z ₂ )(1-2Z ₂ )...(3) Linear pressure at point G P _G P _G = F/B _R・1-4Z ₂ +2Z ₂ ² / (1-Z ₂ ) (1-2Z ₂ )...
...(4) However, F: Rolling load B _R : Roll body length x ₁ : Work roll shift amount x ₂ : Intermediate roll shift amount Z ₁ : Work roll shift rate (=X ₁ /B _R ) Z ₂ : Shift rate of the intermediate roll (=X ₂ /B _R ) Using the above (1) to (4), the shift rate of the work roll is kept constant at Z ₁ =0.1, and the shift rate Z ₂ of the intermediate roll is set between 0 and 0.2. Figure 2 shows the results of examining the linear pressure distribution between the work roll and the intermediate roll and between the intermediate roll and the reinforcing roll when the pressure was varied within the range. Note that rolling load F: 1300 tons, workpiece, intermediate, and reinforcing roll body length B _R : 1420 mm. From the same figure, it can be seen that when Z ₂ =0.1=Z ₁ , that is, if the shift amounts are matched, the linear pressure distribution ( _{3 3} ) between the work roll and the intermediate roll can be made uniform. On the other hand, the linear pressure distribution between the intermediate roll and the reinforcing roll is
It shows a large change as Z ₂ increases, and the linear pressure distribution becomes uniform when Z ₂ =0. However, when considering the contact pressure between normal rolls, the contact pressure between the work roll and the intermediate roll is higher than that between the intermediate roll and the reinforcing roll as shown below, so the contact pressure between the work roll and the intermediate roll is controlled. However, the contact pressure between the intermediate roll and the reinforcing roll may be checked as necessary. Comparing the linear pressures at point B and point E in Figure 1, as shown in Figure 2, point E has a slightly higher value, but considering the wear and fatigue associated with rolling, the contact pressure can be reduced. It must be evaluated as Hertzian pressure. The relationship between linear pressure P and Hertzian pressure P _HZ is However, 1/D _R = D ₁ + D ₂ /D ₁ · D ₂ where D ₁ : Work roll diameter (or intermediate roll diameter) D ₂ : Intermediate roll diameter (or reinforcing roll diameter). For example, when the work roll diameter is 400mm, the intermediate roll diameter is 500mm, and the reinforcement roll diameter is 1350mm,
1/D _R at the contact between the work roll and the intermediate roll = 4.5×10 ^-3 mm ^-1 , and 1/D _R at the contact between the intermediate roll and the reinforcing roll = 2.74×10 ^-3 mm ^-1 ,
Even if the line pressure is the same, the pressure between the intermediate roll and the reinforcing roll will be about 40% smaller at Hertzian pressure. Therefore, controlling the contact pressure between the rolls is
It is advantageous to perform this mainly between the work roll and the intermediate roll, and it is sufficient to check between the intermediate roll and the reinforcing roll as necessary. If we look again at the linear pressure distribution between the work roll and intermediate roll in Figure 2, we see that around Z ₂ = 0.10.
The slope of BD is reversed, that is, the magnitude relationship between the linear pressures at point B and point D is reversed. When Z ₂ <0.10, the linear pressure at point B is lower than at point D, and when Z ₂ >0.10, the linear pressure at point B is higher than point D. That is, the maximum value of the contact pressure occurs at point B or point D, and the situation in which it occurs depends on the shift rate Z ₂ of the intermediate roll, that is, the shift amount when the shift rate of the work roll is constant. Furthermore, the relationship between this shift amount and the linear pressure between the work roll and the intermediate roll is shown in FIG. Figure 3 shows the work roll shift amount x ₁ : 300
The linear pressure at point B or point D, whichever is higher, when the roller is moved within a range of mm is investigated for cases where the shift amount of the intermediate roll is 0, 100, and 200 mm, respectively. First, when the shift amount x ₂ =0, the linear pressure changes along the curve A ₀ C ₀ with the shift amount x ₁ of the work roll. Linear pressure when x ₂ = 100 is a curve when 0≦x ₁ < 100
It decreases along A ₁ B ₁ and reaches a minimum at x ₁ = 100,
For 100<x ₁ it increases along the curve B ₁ C ₁ . x ₂ =
The linear pressure at 200 is curve A ₂ B ₂ when 0≦x ₁ <200
_{decreases along}
then increases along the curve B ₂ C ₂ . Therefore, the maximum linear pressure is the minimum when x ₂ =
It can be seen that at 100, x ₁ = 100, and at x ₂ = 200, x ₁ = 200. Therefore, the linear pressure when x ₁ = x ₂ is further plotted and shown as a dotted line in Figure 3. As is clear from the figure, the maximum linear pressure is the smallest when the work roll and the intermediate roll are shifted by the same amount. In addition, the reason why each roll is subjected to tapered grinding on one end and the tapered grinding is arranged alternately is for edge drop control, as well as to reduce the contact pressure with the intermediate roll at the body end of the work roll, thereby reducing excess bending moment. Since no action is applied to the work roll, the deflection of the work roll is reduced.Furthermore, tapering grinding of the work roll and tapering grinding of the intermediate roll are arranged alternately, so that the plate thickness distribution in the cross section in the width direction of the rolled material is almost horizontal and horizontal. It is possible to achieve stable threading of the rolled material by making it vertically symmetrical and achieving off-center (x ₂ ≠ x ₂ )
This is to avoid. This is also to relieve the concentration of contact pressure on the end of the roll that is shifted toward the center of the sheet width. (Example) Example 1 A rolling mill having the configuration shown in Fig. 1 (work roll: 400 mmφ,
Intermediate roll: 500mmφ, reinforcement roll: 1350mmφ,
Each roll body length: 1420mm), plate thickness 2.3mm, width
A 1000mm medium carbon material was rolled to a final thickness of 0.40mm. The board thickness at the entrance to the final stand is 0.645mm.
The tension at the entry and exit sides is 16.0 and 6.0, respectively.
Kg/mm ² , rolling speed is 1500m/min, rolling load is
It was set at 1300 tons. In addition, for the purpose of etch drop control in plate shape control, the shift amount of the work roll and intermediate roll is set to 200 mm, which is close to the length (210 mm) from the end of the rolled material to the end of the reinforcing roll. The end of the rolled material was also located in the grinding area. The maximum linear pressure at this time is the linear pressure at ₂ points B in Figure 3 (1.39), and if there is no shift movement (x ₁ = 0)
is about 10% compared to the linear pressure at _two points A (1.56)
Since the linear pressure can be reduced and the pressure distribution becomes flat, local wear is reduced and the life of the work roll and intermediate roll until replacement can be extended. Further, Table 1 shows the roll wear after rolling 200 tons of rolled material under the same conditions.

[Table] As is clear from Table 1, it was found that roll shifting can extend the roll life by about 1.4 times. Example 2 Under the same conditions as Example 1, shift amount x ₁ = x ₂ =
Rolling was performed by cyclically shifting only the work roll from the state where it was set to 200 mm. Cyclic shift of the work roll is essentially moving the work roll cyclically within a predetermined shift range.
Shift amount x ₁ : A shift movement of 5 mm was performed in the range of 97 to 210 mm for a rolling length of 1000 mm of the unrolled material. The shift range of the work roll is the maximum Hertzian pressure between the work roll and the intermediate roll to the roll fatigue limit.
To limit it to 210Kg/mm2 or ^less , P/(F/
B _R )≒1.5 to a range in which the linear pressure shown in FIG. 3 is 1.5 or less, that is, the shift amount x ₁ is defined as 97 to 210 mm. Also, the shift amount x ₁ without considering the Hertzian pressure limit:
Rolling with a cyclic shift in the range of 0 to 210 mm was also carried out. Table 2 shows the uneven wear of the rolls, the amount of rolling that can be done, and the amount of width that can be returned after each rolling process has been carried out up to a rolling amount of 200 tons. Note that the definitions of uneven wear and rollable amount are the same as in Table 1.

[Table] By performing a cyclic shift, it was possible to suppress the uneven wear of the rolls, and in particular, for rolls with a Hertzian pressure limit set, the amount of rollable material increased significantly. This shows that cyclic shift can promote uniform wear of the rolls, which not only extends the life of the rolls, but also enables so-called width rolling (for example, rolling back from a narrow material to a wide material), which increases the flexibility of the rolling schedule. I was able to expand it. Also, the width return amount is almost the same, but the shift amount ratio is 80mm/113mm≒0.7 and 84mm/210mm, respectively.
Although the shift amount was limited, the efficiency was found to be ≒0.4. Although the above example shows an example of cold rolling,
It is similarly applicable to hot rolling. (Effects of the Invention) As described above, the present invention can equalize roll wear during the rolling process by reducing the contact pressure between the rolls and making the distribution uniform, thereby increasing the rolling amount and reducing the roll consumption rate. Improvements can be made.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a six-high rolling mill, FIG. 2 is a graph showing the relationship between shift rate and linear pressure, and FIG. 3 is a graph showing the relationship between shift amount and linear pressure. 1A, 1B... Work roll, 2A, 2B...
Intermediate roll, 3A, 3B... Reinforcement roll, 4, 5
...Tapered cutting part, 19...Non-rolled material.

Claims (1)

[Claims] 1. A pair of upper and lower work rolls and an intermediate roll each having one end tapered and ground are ground between a pair of reinforcing rolls in the order of the intermediate roll, work roll, work roll, and intermediate roll. The work rolls and intermediate rolls are moved axially in opposite directions to position the width end of the material to be rolled inside the tapered grinding end, and the width center of the material to be rolled is A method for rolling a plate material, characterized in that rolling is performed with a roll arrangement such that the length from the center of the plate width to the tapered grinding boundary of the work roll is equal to the length from the center of the plate width to the tapered grinding boundary of the intermediate roll. 2 A pair of upper and lower work rolls and an intermediate roll each having tapered grinding applied to one end are arranged between a pair of reinforcing rolls in the order of the intermediate roll, work roll, work roll, and intermediate roll in the order of the tapered grinding. Assembling, move the work roll and the intermediate roll axially in opposite directions to position the width end of the material to be rolled inside the tapered grinding end, and further perform tapering grinding of the work roll from the center of the width of the material to be rolled. The rolls are arranged so that the length to the boundary is equal to the length from the center of the sheet width to the tapered grinding boundary of the intermediate roll,
A method for rolling plate materials characterized by cyclically shifting work rolls.