JPS6329604B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing warpage of a sheet during rolling at different speeds.

In recent years, a different speed rolling method has been considered in which rolling is performed by changing the circumferential speed of upper and lower work rolls, 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, the elongation of the metal strip S in the longitudinal direction differs between the upper and lower sides due to the difference in the circumferential speed of the upper and lower work rolls, and warpage occurs in the metal strip S as shown in FIGS. 1A and 1B. However, such plate warping that occurs in the longitudinal direction of the metal strip S deteriorates the threadability in the subsequent process, and even if it is attempted to be straightened and flattened through a straightening machine, bending occurs in the width direction of the metal strip S. However, it becomes difficult to obtain a flat plate as a finished product. It should be noted that the plate warpage is considered to be negative if it becomes convex upward as shown in FIG. 1A, and positive if it becomes convex downward as shown in FIG. 1B.

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 2. I understand.
The graph of the experimental results in Figure 2, where the horizontal axis is the offset amount of the upper work roll and the offset amount of the lower work roll, and the vertical axis is the curvature of the sheet warp, shows that the upper work roll is moved toward the exit of the rolling mill, and the lower work roll is moved toward the exit side of the rolling mill. If the 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 are offset so that the warp of the sheet occurs in the opposite direction to the direction of warpage of the sheet caused by rolling at different speeds, it is possible to eliminate warpage of the sheet after rolling at different speeds. However, in FIG. 2, the offset amount is positive on the rolling mill outlet side and negative on the inlet side.

The present invention has been made in view of this point of view, and is intended to solve the problem of work on the side of sheet warping that occurs when the work rolls are not offset in the longitudinal direction of the metal strip during rolling at different speeds in which the circumferential speed of a pair of work rolls is changed. The rolls are offset to the rolling mill entrance side, or the work rolls on the side opposite to the strip warpage that occurs when the work rolls are not offset in the longitudinal direction of the metal strip are offset to the rolling mill exit side, or the work rolls are offset to the rolling mill exit side. The work roll on the side of the sheet warpage that occurs when the metal strip is not offset in the longitudinal direction is offset to the rolling mill entrance side, and the work roll on the side opposite to the sheet warpage that occurs when the work roll is not offset in the longitudinal direction of the metal strip. This method is characterized in that the work rolls are offset toward the exit side of the rolling mill.

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

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 into 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 31.
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 box. 2, and a conduit 20 for feeding oil discharged from the hydraulic pump 19 is connected to the cylinder 28.

A setting device 21 for setting the circumferential speed ratio of the upper and lower work rolls 1 and 3 is connected to a calculator 22, and a signal from the calculator 22 is transmitted to the motor 16 and the upper and lower work rolls 1 and 3.
so that it can be sent to the motors 23 and 24 that drive it.

In the figure, 25 is an oil tank, 26 and 27 are spindles, 29 is a worm wheel housing, and 30
indicates a bearing.

During rolling, the circumferential speed ratio of the upper and lower work rolls 1 and 3 is input to the calculator 22 by the setting device 21. Then, the calculator 22 sends a signal instructing the rotation speed to the motors 23 and 24, respectively, and calculates how much the upper work roll 1 should be offset, and sends the signal to the motor 16. , the screw shaft 11 is driven by the motor 16.
rotates and moves a required amount in a direction parallel to the direction in which the metal strip S travels. During this movement, the piston 17
Since the upper working roll shaft box 2 is moved by the same amount in the same direction as the screw shaft 11, the upper working roll shaft box 2 is held between the seats 13 and 18, moves forward or backward, and is offset by a required amount with respect to the axis of the upper holding roll 5. In the case of a metal strip that warps convexly upward (downward warp) when rolled at different speeds with an offset amount of zero, the direction of offset of the upper and lower work rolls 1 should be set toward the exit of the rolling machine from a perpendicular line passing through the axis of the upper backing roll. In the case of a metal strip that warps downward convexly (upward warping) when rolled at different speeds with an offset amount of zero, the rolling mill entrance side is set from the perpendicular line passing through the upper backing roll axis. Further, the amount of offset is made approximately proportional to the amount of warpage of the plate.

In the embodiments of the present invention, the case in which the upper work roll is offset has been explained, but it is also possible to offset the lower work roll or both the upper and lower work rolls (in the case where the lower work roll is offset). In the case of a metal strip that curves upward when rolled at different speeds with an offset amount of zero, the offset direction should be set closer to the entrance of the rolling mill than the perpendicular line passing through the axis of the bottom roll, and when rolled at different speeds with an offset amount of zero. Then, in the case of a metal strip that warps downward,
It should be on the rolling mill exit side from the perpendicular line passing through the axis of the lower support roll. In addition, when both the upper and lower work rolls are offset, in the case of a metal strip that warps upwardly, the upper work roll is offset toward the rolling mill entrance side, the lower work roll is offset toward the rolling mill exit side, and the lower work roll is offset toward the rolling mill entrance side. In the case of a metal strip that warps convexly, the upper work roll is offset toward the rolling mill exit side, and the lower work roll is offset toward the rolling mill entrance side. In short, the direction of offset is the direction in which strip warpage disappears, and the work roll on the side of the strip warpage that would occur if the work roll is not offset is offset toward the rolling mill entrance side, or the work roll on the side that is opposite to the strip warp that would occur when the work roll is not offset. The side opposite to the side of the plate warp that occurs when the work roll is offset to the rolling mill outlet side or when the work roll is not offset, and when the work roll is offset to the rolling mill entrance side and the work roll is not offset Offset the work rolls to the rolling mill outlet side. ), it goes without saying that various other changes may be made without departing from the gist of the present invention.

Since the method for preventing sheet warpage during rolling at different speeds according to the present invention has the above-described configuration, a product without sheet warpage can be obtained.

[Brief explanation of drawings]

Figures 1A and 4 are explanatory diagrams of sheet warping when rolled at different speeds, Figure 2 is a graph showing the relationship between the offset amount of the upper and lower work rolls and the curvature of the sheet warpage, and Figures 3 and 4 are the main FIG. 2 is an explanatory diagram of the method for preventing board warpage of the invention. In the figure, 1 is the upper work roll, 3 is the lower work roll, and 9
is the housing, 10 is the nut, 11 is the screw shaft, 14 is the worm wheel, 15 is the worm,
17 is a piston, 21 is a setting device, and 22 is a computing device.

Claims (1)

[Claims] 1 In different speed rolling in which the circumferential speed of a pair of work rolls is changed and rolling is performed, the work roll on the side where the strip warps, which occurs when the work roll is not offset in the longitudinal direction of the metal strip, is offset toward the entrance of the rolling mill, or Occurs when the work roll is not offset in the longitudinal direction of the metal strip.This occurs when the work roll on the side opposite to the strip warpage side is offset toward the rolling mill exit side, or when the work roll is not offset in the longitudinal direction of the metal strip. The work roll on the strip warping side is offset to the rolling mill entrance side, and the work roll on the opposite side to the strip warping side, which occurs when the work roll is not offset in the longitudinal direction of the metal strip, is offset to the rolling mill exit side. A method for preventing sheet warpage during rolling at different speeds.