JPH0691309A - Work roll and cold tandem mill using the same - Google Patents

Abstract

PURPOSE:To prevent the generation of a singular point due to the rapid change in gradient and the generation of defective rolling in the end face part of roll by forming a tapered part with a taper curve from a curve of which the tangent at the starting point of curve is coincident with the tangent in the axial direction on the outer peripheral surface of the straight part. CONSTITUTION:The external shape of the tapered part 3 with the taper curve which is connected to the one end part of the cylindrical straight part 2 is formed by the curve C of which the radius of curvature is successively reduced from the boundery between the straight part 2 and the tapered part 3 i.e., the starting point A of curve toward the side of the end part and the tangent X at the starting point A of curve is coincident with the tangent Y in the axial direction on the outer peripheral surface in the straight part 2. Then, by continuing the straight part 2 on the tapered part 3 with a smooth curve of which the tangent is common at the starting point A of curve, rapid change in thickness and shape at the taper starting part is prevented and the sensitive change of crown due to deviation from the center in the passing direction of the strip during passing is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work roll used in a rolling mill such as a four-high rolling mill, a six-high rolling mill, or a multi-high rolling mill, and a tandem cold rolling mill using the work roll or a complete continuous rolling mill. Type tandem cold rolling mill.

[0002]

2. Description of the Related Art When cold rolling a steel sheet with a rolling roll,
The part where the work roll abuts the width end of the steel sheet material is elastically deformed, and due to this elastic deformation, the rolled material width end is rolled more than other parts. As a result, a so-called edge drop phenomenon occurs, which causes a local end extension shape defect in the width direction of the rolled material. .

In order to deal with such a problem, for example,
JP-A-61-165215, JP-A-58-173
Japanese Patent Laid-Open No. 001-237005 and Japanese Patent Application Laid-Open No. 1-237005 disclose a tapered rolling roll in which a tapered taper portion is continuously provided at a side end of a cylindrical straight portion of a work roll.

By forming such a tapered taper portion, elastic deformation of the work roll is absorbed, excessive rolling of the rolled material end portion is prevented, and edge drop at the rolled material end portion is prevented to some extent. be able to.

However, all the taper portions of the work rolls described in the above publications are linearly changed from the taper portion start point to the outside, and the taper start point becomes a singular point during rolling. Exist, which causes defective rolling.

FIG. 5 is an explanatory diagram showing this state.
FIG. 5A is a diagram showing a change in thickness of the steel sheet in the width direction, FIG.
(B) is a figure showing the change of rolling load similarly.

In FIG. 5 (a), the plate central portion rolled by the straight part of the work roll has substantially flatness, the plate thickness is suddenly reduced at the taper start point, and then the plate thickness is reduced at the taper part. The thickness becomes thicker, and further, the thickness becomes sharply thin at the edge of the electrode plate due to edge drop, resulting in a thickness distribution.

It is presumed that such a rapid change in the plate thickness at the taper start point is due to a rapid change from the straight portion to the tapered portion of the work roll, which is the boundary portion between the tapered portion and the straight portion, that is, At the taper portion start point, as shown in FIG. 5B, the rolling force is concentrated, which causes abnormal wear and fatigue of the work roll.

In Japanese Patent Laid-Open No. 61-82906, N
o. The taper work roll is used for one stand. No. With only one stand, it is necessary to increase the taper or the work roll shift amount to increase the edge gap.

When the gap is increased, stress is applied to the edge, which leads to plate breakage. Further, since the rolling force distribution at the edge portion is different, an edge mark (difference in plate roughness) appears.

If the gap is made smaller, plate breakage is less likely to occur, but edge drop is not improved.

Therefore, it is applied to a plurality of stands of a tandem mill to improve edge drop as a whole.

In a completely continuous tandem mill, since the trailing end of the preceding coil and the leading end of the next coil are welded and rolled, the plate being cambered easily causes the plate being threaded to be displaced in the roll axial direction from the mill center, and avoids meandering. I can't.

Further, the backlash (play) of the work roll shift device also causes an error between the position of the plate edge in the roll axial direction and the end taper position of the work roll.

In this case, it is advantageous that the reduction rate of the roll diameter gradually increases from the taper start position like an arc shape rather than a trapezoidal taper. That is, even if there is an error in the plate camber or the backlash of the work roll shift, the plate pressure fluctuation is not sensitive at the taper start portion, and the plate edge with a large edge drop has a sufficient effect.

[0016]

The problem to be solved by the present invention is to prevent the occurrence of singularity due to the abrupt change of the gradient at the boundary between the straight portion and the taper portion, and prevent the occurrence of rolling defects at the roll end face portion. To get a work roll.

[0017]

In order to solve the above-mentioned problems, the present invention provides a work roll in which a tapered curved tapered portion is continuously provided at a side end of a cylindrical straight portion, the tapered portion being at a curve starting point. The tangent line is formed by a curve that coincides with the axial tangent line of the outer peripheral surface of the straight portion.

As the curve of the taper portion, an arc, a sine curve, a hyperbola, an ellipse and a clothoid curve whose radius of curvature continuously decreases in proportion to the curve length can be used.

[0019]

In the present invention, the straight portion and the taper portion are connected by a smooth curve having a common tangent line at the curve start point so that a sharp plate thickness (crown) and shape (tension) at the taper start portion can be obtained. ) Is prevented, and
It is possible to prevent a sensitive crown change due to a deviation from the center of the plate passing plate direction.

[0020]

1 is a sectional view of a 6-high rolling mill equipped with work rolls according to an embodiment of the present invention.

Each of the work rolls A-1 and A-2 has an R-shaped taper on one roll end and is set upside down. One set of two intermediate rolls B-1 and B-2 are arranged on the opposite side of the plate across the work roll, and further backup rolls C-1 and C-2 are arranged outside thereof.

FIG. 2 is an enlarged view of a main part of the work roll 1 shown in FIG. 1, FIG. 3 is a detailed view of a curve forming a taper, 2 is a cylindrical straight part forming the main body of the work roll 1, 3
Is a tapered tapered portion with a curved line which is continuously provided at one end of the cylindrical straight portion 2. An outer shape of the tapered portion 3 is formed by a boundary between the straight portion 2 and the tapered portion 3, that is, a curve C in which the radius of curvature is gradually reduced from the curve start point A toward the end side, and at the curve start point A. The tangent line X in the straight portion 2 coincides with the tangent line Y in the axial direction on the outer peripheral surface of the straight portion 2. (For the sake of explanation, X and Y are shifted in FIG. 3.) Referring to FIG. 3, the curve C (= TR ₂ )
Has a radius of curvature R at the curve start point A, and at the point Pn, changes by -dZ and dX in the Z-axis and Y-axis directions with respect to the arc TR ₁ having a radius of curvature R + r, respectively. Has become.

This curve C can be formed by grinding using the grindstone 5 whose corners shown in FIG. 3 are formed with a radius of curvature r ₁ .

The grindstone 5 is rotationally driven in the same direction as the rotation direction of the work roll 1 by a rotation shaft (not shown) parallel to the work roll 1. The corner of this grindstone 5 is the work roll 1
A predetermined curve C is formed while sequentially abutting from the curve starting point A. At that time, the grindstone 5 is provided so that the moving speeds of the Z axis and the X axis, which are the plane moving axes, cause a difference in moving distance between the locus TR ₁ and the moving speed at which the locus becomes an arc, −dZ and dX.
The moving locus of the center O _r of the radius of curvature of is reduced by −dV _{Z in the} Z-axis direction and increased by + dV _{X in the} X-axis direction compared to the case of the locus describing TR _{1 in} the moving velocity of both axes corresponding thereto. . As a result, the contact point P _W of the curved portion of the grindstone 5 forms a contraction locus TR ₂ deviated from the arcuate movement locus TR ₁ . Note that TR indicates the locus of the center of curvature O _r of the grindstone 5.

FIG. 4 shows No. 5 of the 5-stand tandem cold rolling mill. Work roll 1 with taper on 1 and 2 stands
Fig. 5 shows the state (a) of the rolled plate crown and the distribution (b) of the rolling load per unit width when applied to a SPCC class steel plate in which a 3 mm thick steel plate is rolled to 1.0 mm x 1200 mm using It is shown corresponding to.

As shown in the figure, in the straight portion 2, the flatness is secured as in the conventional example, and at the starting point A of the curve, the plate thickness is slightly reduced, but there is almost no change. Moreover, the increase in the plate thickness at the tapered portion 3 was also very gradual. Similarly, although the rolling load also showed the maximum value at the curve starting point A, the straight portion 2
Is very gradual, and the load from the tapered portion 3 to the end is also gradual compared with the conventional one.

As described above, by using the work roll of this embodiment, it is possible to perform good rolling without causing a sharp reduction in the plate thickness at the boundary between the straight portion and the tapered portion, that is, the starting point of the curve. became. Further, the rolling load was not concentrated on the work roll itself at the starting point of the curve, and abnormal wear and fatigue were significantly reduced.

In the above embodiment, the radius of curvature gradually decreases, but the invention is not limited to this, and it is of course possible to use an arc, a parabola, a quadratic curve, a sine curve, a hyperbola or the like. .

[0029]

According to the present invention, the following effects can be obtained.

(1) Stable rolling without stress concentration became possible, and abnormal wear and fatigue near the boundary between the straight portion and the tapered portion of the work roll could be reduced.

(2) It is possible to prevent a rapid reduction in plate thickness at the boundary between the straight portion and the tapered portion of the manufactured steel sheet, and it is possible to perform work with few rolling defects.

(3) By using the roll of the present invention for a plurality of stands of the tandem rolling mill, the edge drop reducing effect can be obtained with a small taper. Also, the effect of the work roll shift play was small.

(4) By using the roll of the present invention in the completely continuous tandem rolling mill, the influence of the plate camber can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rolling mill including a work roll according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the work roll shown in FIG.

FIG. 3 is an explanatory diagram of curve formation of a tapered portion.

FIG. 4 is a diagram showing a rolled plate crown and rolling load in Examples.

FIG. 5 is a diagram showing a rolled plate crown and a rolling load in a conventional work roll.

[Explanation of symbols]

 1 Work roll 2 Straight part 3 Tapered part C curve A curve start point

Claims (3)

[Claims] 1. A work roll of a rolling mill, wherein a tapered curved shoulder drop portion is continuously provided on a side end of a cylindrical straight portion, and the taper portion has a tangent line at a curve start point in an axial direction of an outer peripheral surface of the straight portion. A work roll characterized by being formed by a curve that coincides with a tangent line. 2. A tandem cold rolling mill comprising two or more stands of a tandem cold rolling mill having a plurality of rolling stands, which is equipped with the work roll and the axial movement device for the work roll according to claim 1. . 3. The tandem cold rolling mill is characterized in that it is a completely continuous tandem cold rolling mill that welds the rear end of the coil being rolled and the front end of the next rolling coil.
Tandem cold rolling mill described.