JPH0113926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for controlling sheet warpage in rolling at different speeds.

In recent years, a method of rolling at different speeds in which rolling is performed by changing the circumferential speed of upper and lower work rolls has been considered, and this rolling method has the following advantages.

(i) Rolling force is significantly reduced.

(ii) Thin plates can be rolled using large diameter rolls.

(iii) Since edge drops are reduced, edge cracking can be prevented.

(iv) The rolling limit is lowered, making it possible to roll thinner plates.

(v) The number of rolling passes is reduced.

(vi) The rigidity of the rolling mill may be low.

(vii) The number of intermediate annealing can be reduced.

(viii) Shape control using different speeds is possible.

(ix) Roll Crown can be reduced.

However, in different speed rolling, since the circumferential speeds of the upper and lower work rolls ₁ and ₃ shown in FIG.
M ₀ and M ₁ act. These moments M ₀ and M ₁ cause plate warpage as shown in FIG. 2 A and B.

However, such plate warpage that occurs in the longitudinal direction of the metal strip S deteriorates the threadability in the subsequent process, and even if an attempt is made to straighten and flatten the metal strip S using a straightening machine, bending occurs in the width direction of the metal strip S, resulting in a finished product. As a result, it becomes difficult to obtain a flat plate. However, in Fig. 1, h is the average thickness of the metal strip S, and as shown in Fig. 2 A, the upwardly convex shape is considered a minus;
As shown in Figure B, a downward convex shape is considered a positive sign.

On the other hand, when rolling is performed by varying the offset amount of the upper and lower work rolls toward the inlet or outlet side of the rolling mill, warpage occurs in the metal strip in proportion to the offset amount, as shown in Figure 3. I understand.
The graph of the experimental results in Figure 3, in which the horizontal axis represents the offset amount of the upper work roll and the offset amount of the lower work roll, and the vertical axis represents the curvature of the warpage, shows that the upper work roll is moved toward the exit side of the rolling mill, and If the work roll is offset to the rolling mill entrance side, a downward convex positive plate warpage will occur, and if the upper work roll is offset to the rolling mill entrance side and the lower work roll to the rolling mill exit side,
An upwardly convex negative plate warpage occurs. Therefore, if the upper and lower work rolls 1 and 3 are offset to the required positions during rolling at different speeds, the warping of the sheet caused by mere rolling at different speeds and the warping of the sheet due to offset are offset, and as a result, a product without warping of the sheet can be obtained. becomes possible. However, in FIG. 3, the offset amount is positive on the rolling mill outlet side and negative on the inlet side.

Now, to explain how far the upper and lower work rolls should be offset in order to prevent warpage from occurring in the metal strip S after rolling, using FIG.
If M _x is the moment generated by the offset, M _x - (F ₀ + F ₁ ) h/2 = 0... (a) Then, the metal strip S has a moment M ₀ at the end,
M ₁ should not occur and the plate warpage should disappear.

In addition, in Fig. 4, the rolling load per unit length is p, and the length on which the rolling load acts (offset amount) is
If x is the distance between the center of the length x on which the rolling load p of the upper work roll 1 acts and the center of the length x on which the rolling load p of the lower work roll 3 acts, then M _x = pxl =xP...(b) becomes. However, P is the entire rolling load.

Furthermore, the radius of the upper and lower work rolls 1 and 3 is R, the torque applied to the upper work roll 1 is T ₀ , and the lower work roll 3 is
If the torque applied to is T ₁ , then the frictional forces F ₀ and F ₁ are as follows: F ₀ = T ₀ /R, F ₁ = T ₁ /R...(c), so (F ₀ +F ₁ )h/ 2=T ₀ +T ₁ /R・h/2 ...(d).

When formulas (b) and (d) are put into formula (a), xP=T ₀ +T ₁ /R・h/2 is established, and when the shape modification coefficient ξ is taken into account, x=ξT ₀ +T ₁ / 2RPh...(E) is found. That is, if the rolling load P during rolling and the torques T ₀ and T ₁ applied to the upper and lower work rolls 1 and 3 are determined, the radius R of the upper and lower work rolls 1 and 3 and the average thickness h of the metal strip S are known. The offset amount x can be found from .

By the way, if we consider the straight line ' in Fig. 4 as a reference, the upper and lower work rolls 1 and 3 are not offset,
It can be understood that the same effect can be obtained even if the metal strip S is inclined by the inclination angle α as shown in FIG. Therefore, the relationship tanα=x/2R+h′...(f) holds true, and since the inclination angle α is a small angle and the plate thickness h is also small compared to the radius R, α≒x/2R+h′≒x/ 2R ……(g) holds true. When formula (E) is inserted into this formula (G), α=ξhT ₀ +T ₁ /4R ² P ...(H) is established, and the rolling load P during rolling and the torque T applied to the upper and lower work rolls 1 and 3 are established. ₀ and T ₁ , the inclination angle of the metal strip S can be determined.

The present invention was made in view of this point of view, and the rolling load and the torque for driving the upper and lower work rolls are
The diameter of the upper and lower work rolls is preset in the calculator,
Calculate the average thickness of the metal strip and the shape modification coefficient to determine the offset amount of the work roll necessary to prevent warpage, and use that signal to move the work roll in a direction parallel to the direction of travel of the metal strip. It is also characterized by the fact that the rolling load and the torque for driving the upper and lower work rolls are calculated together with the diameter of the upper and lower work rolls, the average thickness of the metal strip, and the shape modification coefficient, which are preset in a calculator, to prevent the warpage of the sheet. The present invention is characterized in that the angle of inclination of the metal strip necessary to prevent this is determined, and the metal strip is tilted back and forth with respect to the pass line based on that signal.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 6 and FIG. 7 are one embodiment of the present invention,
This is an example in which the upper work roll is offset.

In the figure, 1 is an upper work roll that is pivotally supported on an upper work roll shaft box 2, 3 is a lower work roll that is pivotally supported on a lower work roll shaft box 4, and 5 is an upper work roll that is pivotally supported on an upper work roll shaft box 6. A backing roll 7 is a lower backing roll pivotally supported by a lower backing roll shaft box 8, and 9 is a housing.

A nut 10 whose axis extends in the direction of movement of the metal strip S is fixed to the upstream part of the housing 9, and a screw shaft 11 for pushing the upper work roll shaft box 2 is screwed onto the nut 10. A thrust bearing 12 is interposed between one end and a seat 13 in contact with the upper work roll shaft box 2 so that there is no problem even when the screw shaft 11 rotates.
The worm wheel 14 is attached to the other end of the worm wheel 14 via the spline key 35.
can be driven by a worm 15 connected to a motor 16.

A cylinder 28 whose axis extends in the direction of movement of the metal strip S is provided on the downstream side of the housing 9, and a piston 17 having a seat 18 pivotally attached thereto is fitted into the cylinder 28, and the seat 18 is connected to the upper work roll shaft. A conduit 20 is brought into contact with the box 2 and is connected to the cylinder 28 for feeding oil discharged from the hydraulic pump 19.

A load detector 21 such as a load cell attached to the upper part of the housing 9 is connected to a calculator 22 to detect the rolling load during rolling, and the torque T ₀ of the motors 23 and 24 that drive the upper and lower work rolls 1 and 3 is calculated.
The signal of _T1 can be sent to the calculator 22, and the signal of the offset amount x of the upper work roll 1 calculated by the calculator 22 can be sent to the motor 16.

In the figure, 25 is an oil tank, 26 and 27 are spindles, 37 is a worm wheel housing, and 37 is an oil tank.
indicates a bearing.

When different speed rolling is started, the rolling load P is detected by the load detector 21 and its signal is sent to the computing unit 22, and the signals of the torques T ₀ and T ₁ of the motors 23 and 24 are sent to the computing unit 22, In the calculator 22, the offset amount x is calculated based on the preset shape correction coefficient ξ, the radius R of the upper and lower work rolls 1 and 3, and the average plate thickness h, and the signal is sent to the motor. 1
6, and as the screw shaft 11 is rotated by the drive of the motor 16, it moves by x in a direction parallel to the traveling direction of the metal strip S. During this movement, the piston 17 also moves by the same amount in the same direction as the screw shaft 11, so the upper work roll shaft box 2
Move forward or backward while being held in place. The amount of offset is continuously controlled during rolling, and no warpage occurs in the rolled metal strip S.

FIG. 8 shows another embodiment of the present invention, in which the inclination angle α of the metal strip S is varied.

In the figure, 29 and 30 are push rollers provided at the inlet and outlet sides of the rolling mill, 31 and 32 are push rollers 29,
It is a fluid pressure cylinder that raises and lowers the fluid pressure cylinders 31, 30, and the signals calculated by the calculator 22 are
Servo valve 3 that controls the amount of pressure oil fed to 32
3 and 34. Note that the same reference numerals as those shown in FIG. 7 indicate the same components.

As in the case of the previous embodiment, the rolling load P is detected by the load detector 21 and its signal is sent to the computing unit 22, and the signals of the torques T ₀ and T ₁ of the motors 23 and 24 are sent to the computing unit 22. and in the computing unit 22, the expression
The inclination angle α is calculated by (H), and the signal is sent to the servo valves 33, 34, and the hydraulic cylinders 31, 3
2 is supplied with pressure oil, the push rollers 29 and 30 move up and down, and the inclination angle α becomes a predetermined angle. The inclination angle α is continuously controlled during rolling, so that the rolled metal strip S does not warp.

In the first embodiment of the present invention, the upper work roll is offset, but the lower work roll may also be offset, and the direction of the offset and the direction of the inclination angle may be any direction that eliminates warping. Of course, various changes may be made without departing from the gist of the present invention.

Since the method and device for controlling sheet warpage in different speed rolling of the present invention have the above-described configuration, it is possible to eliminate sheet warpage of the metal strip, thereby improving product quality and adding tension to the metal strip. Whether it is added or not, board warpage control can be performed, and various excellent effects can be achieved, such as eliminating the need for a board warp detector.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of why a metal strip warps when rolled at different speeds, Figure 2 A and B are illustrations of warpage caused by rolling at different speeds, and Figure 3 is an illustration of vertical work. A graph showing the relationship between the roll offset amount and the curvature of the plate warpage. Figure 4 is an explanatory diagram of the principle of eliminating plate warpage. Figure 5 shows that plate warpage can be eliminated even if the metal strip is tilted. An explanatory diagram of the reason, FIGS. 6 and 7 are explanatory diagrams of one embodiment of the board warp control method and apparatus of the present invention, and FIG. 8 is an explanation of another embodiment of the board warp control method and apparatus of the present invention. It is a diagram. In the figure, 1 is the upper work roll, 3 is the lower work roll, and 9
is a housing, 11 is a screw shaft, 14 is a worm wheel, 15 is a worm, 16, 23, 2
4 is a motor, 17 is a piston, 21 is a load detector, 22 is a calculator, 29 and 30 are push rollers, 3
1 and 32 indicate fluid pressure cylinders.

Claims (1)

[Scope of Claims] 1. The rolling load and the torque for driving the upper and lower work rolls are calculated together with the diameter of the upper and lower work rolls, the average thickness of the metal strip, and the shape modification coefficient, which are preset in a calculator. A method for controlling strip warpage in different speed rolling, characterized in that the amount of offset of a work roll necessary to prevent strip warpage is determined, and the work roll is moved in a direction parallel to the traveling direction of a metal strip based on the obtained signal. 2 Calculate the rolling load and the torque for driving the upper and lower work rolls together with the diameter of the upper and lower work rolls, the average thickness of the metal strip, and the shape modification coefficient that are preset in the calculator to prevent sheet warping. 1. A method for controlling warping of a metal strip in different speed rolling, characterized in that the angle of inclination of a metal strip is determined, and the metal strip is tilted back and forth with respect to a pass line based on the signal obtained. 3 A device that drives a pair of work rolls at a predetermined circumferential speed ratio, a load detector that detects the rolling load, the rolling load, the torque of the drive device, the diameter of the upper and lower work rolls,
A calculator that calculates the amount of offset of the work roll from the average thickness of the metal strip and a shape modification coefficient and outputs the result, and a signal output from the calculator to move the work roll in a direction parallel to the direction of travel of the metal strip. 1. A sheet warpage control device for rolling at different speeds, characterized in that the device is provided with a device for moving the sheet at different speeds. 4 A device that drives a pair of work rolls at a predetermined circumferential speed ratio, a load detector that detects the rolling load, the rolling load, the torque of the drive device, the diameter of the upper and lower work rolls,
a calculator that calculates the inclination angle of the metal strip from the average thickness of the metal strip and a shape modification coefficient and outputs the result;
A sheet warpage control device for rolling at different speeds, characterized in that a push roller is provided that tilts the metal strip back and forth based on a pass line in response to a signal from the computing unit.