JP2900973B2 - Sizing and rolling method for steel bars - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sizing and rolling bar and wire rods using a four-roll rolling mill.
The present invention relates to a method capable of widening a sizing range with the same roll while maintaining high dimensional accuracy, which is a feature of the roll method.

[0002]

2. Description of the Related Art As a method of sizing and rolling round steel bars, a four-roll method using a four-roll rolling mill has been proposed as a method capable of obtaining high dimensional accuracy. In this method, for example, as shown in FIG. 7 (a), a material 10 having a substantially circular cross section formed by a rolling mill row such as a two-roll rolling mill is used as shown in FIGS. 7 (b) and 7 (c). Then, rolling is performed by two 4-roll rolling mills arranged in series with the rolling direction shifted by 45 ° to the downstream side of the rolling mill row.

The roll gaps d ₁ , d ₂ (d ₁ = d ₂ ) of the rolls 11 a to 11 d and 12 a to 12 d of the first stand and the second stand are set to be smaller than the diameter D _{0 of the} material 10. In the first stand, the material 10 is lowered from the top, bottom, left and right directions, and in the second stand, the surface which is not lowered by the first stand is shifted by 45 °, so that the diameter of the cross section is substantially equal to the roll gap d ₁ = d _2. A round bar is obtained.

[0004] A round bar obtained by such a four-roll method.
The dimensional accuracy of steel is higher than that obtained by the two-roll method
Is high, but the sizing range with the same roll is narrow
Was something. Therefore, the present inventors have considered the characteristics of the four-roll method.
While maintaining high long dimensional accuracy, the same roll
Method that can increase the sizing range
As shown in FIG. 1, the four roll pressure of the first stand P1
Roll the center line of the axis of the roll pair 1A, 1B that constitutes the rolling mill 1.
First reference line O projected on a plane parallel to the end face of pair 1C, 1D
₁And the center of the roll pair 1C, 1D on the surface
Connected second reference line O_TwoIs greater than 0 and above
Projected contact length at roll pair 1C, 1D located on the downstream side
l_dProposed a method to keep the value less than 5 times (Japanese Patent Application Hei 4-
No. 220065).

In this method, FIG. 8 shows the relationship between the distance L and the width expansion ratio [((width of material after rolling−width of material before rolling) / width of material before rolling) × 100]. As can be seen from the graph, the larger the distance L becomes, the closer to the two-roll method, the larger the spreading ratio becomes. However, as can be seen from the graph of FIG. 9, the degree of deterioration of the spreading ratio sharply increases, L / l. By setting _d = 5 as the upper limit, the dimensional accuracy is maintained at a high level while keeping the width spread rate small.

[0006]

In the method of the present inventors, as can be seen from the graph of FIG.
0 the relationship between the projection contact length l _d <L / l by limiting the range of _d ≦ 5, although wide rising rate is kept low, for example less than 0.4%, the value of the wide rising rate 0 <L / l _d
When ≦ 5, there is a variation of about 0.4%. Since the dimensional accuracy becomes higher as the width expansion ratio becomes smaller, there is still room for improvement in the above method.

The present invention has been made in view of such a point, and in a sizing and rolling method for a steel bar with four rolls, the sizing possible range with the same roll can be increased, and the dimensional accuracy of the obtained steel bar can be reduced. It is an object to provide a method that can be made even higher.

[0008]

In order to achieve the above object, the present invention provides a method for sizing and rolling a steel bar according to the present invention, which comprises two four-roll mills for rolling a material from two orthogonal directions with two to four rolls. In a method for sizing and rolling a steel bar by a rolling mill row arranged in series with a rolling direction shifted by 45 ° between the two rolling mills, the first stand of the two rolling mills is arranged on the upstream side. In a four-roll rolling mill, a first reference line in which the center line of the axis of one pair of rolls is projected onto a plane parallel to the end face of the other pair of rolls, and the center of the other pair of rolls are aligned with each other. The distance from the second reference line tied in the plane is kept larger than 0 and less than or equal to five times the projected contact length of the roll pair located on the upstream side of the two roll pairs of the first stand, and Between machine stands The force 0.10~0.30kgf / m
It is characterized in that it has a m ^2.

[0009]

According to the present invention, the distance L and the projected contact length l _d
If the relationship between the ranges of _{0 <L / l d ≦ 5} , 0.10~0.30kgf the interstand tension of the two rolling mill
/ Mm ² , the width expansion ratio can be made close to zero. That is, the relationships between the two rolling mill stands between the tension and the wide rising rate when the L / l _d = 1 in are shown graphically in FIG. 4, as can be seen from this graph, interstand tension 0.10 If the width is 0.30 kgf / mm ² , the spread of the width is suppressed by ± 0.2% (that is, with a width of 0.4%).
<It becomes as L / l _d ≦ 5 wide rising rate variation 0.4% is offset in is close to zero, the higher the dimensional accuracy.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view for explaining the configuration of the present invention, FIG. 2 is an enlarged view showing a hole-shaped portion in the first stand of FIG. 1, and (a) is A ₁ -A ₁ of FIG. line cross-sectional view (b) corresponds to a ₂ -A ₂ cross-sectional view taken along line. FIG. 3 is an enlarged view showing a hole-shaped portion in the second stand of FIG. 1, and corresponds to a cross section taken along line BB of FIG.

As shown in FIG. 1, two two-roll rolling mills are arranged downstream of a general rolling mill row in which a plurality of two-roll rolling mills are shifted in a rolling direction by 90 °, as shown in FIG. Were arranged in series along the pass line P. Among them, the four-roll rolling mill 1 arranged on the first stand P1 on the upstream side includes:
The rolled material 3 is made up of two to four rolls 1A, 1B, 1C and 1D, and the rolled material 3 is lowered from the horizontal direction by one pair of rolls 1A and 1B and from the vertical direction by the other pair of rolls 1C and 1D. Is done.

[0012] Each of the roll pairs is a roll 1A.
A first reference line O obtained by projecting the center line of (1B) on a plane parallel to the end face of the roll 1C (1D) (for example, on the paper surface of FIG. 1).
_1, roll 1C, the distance the center C _1, C ₂ each other 1D between the second reference line O ₂ that connects in the plane L = 40 m
m. Therefore, the four-roll rolling mill 1 is a four-roll rolling mill, but a two-roll rolling mill 21 including a pair of rolls 1C and 1D as shown in FIG. It can be considered that such a two-roll rolling mill 22 composed of a pair of rolls 1A and 1B is arranged at a position shifted by L.

The rolled material 3 rolled in the rolling direction (vertical direction) indicated by the second reference line O ₂ in the first pass of FIG. , A line O ₃ orthogonal to the first reference line O ₁ (ie,
After rolling in the rolling direction (horizontal direction) indicated by (θ ₁ = 90 °), it is directed to the second stand P2 on the downstream side. The four-roll rolling mill 2 arranged on the second stand P2 is a normal four-roll rolling mill composed of two to four rolls 2A, 2B, 2C, and 2D (that is, the distance L = 0). as can be seen, the roll 2A, the roll 1 line O ₄ as the first stand P1 showing the rolling direction of the 2D forming one pair
The angle θ ₂ formed by a line (second reference line) O ₂ indicating the rolling direction by C and 1D, and the rolls 2B and 2 forming the other pair
Roll 1A line O ₅ and the first stand P1 showing the rolling direction of C, are all set to 45 ° the angle theta ₃ formed by the line O ₃ showing the rolling direction of 1B.

A material having a diameter of 55.5 mm, whose cross section has been rolled into a substantially circular shape in a two-roll rolling mill row, which is the former stage of the rolling mill row constructed as described above, is processed by two four-roll rolling mills, which are the latter stage. First stand P1 and second stand P2
While applying a tension of 0.1 to 0.3 kg / mm ^{2 to} the material to be rolled, a roll bar having a diameter of 50 to 55 mm was sizing-rolled by changing the roll gap using the same hole mold.

FIG. 5 is a schematic view showing the shape of the hole shape of the roll used, and the central angle θ _c = 45 of the arc forming the roll groove.
°, radius of curvature R = 27.27 mm (target cold diameter 54 m
m to form a perfect circle), and straight reliefs are formed on both sides of the arc. Further, the same roll is used in the first stand and the second stand, and the dimension S (1/2 of the interval between the shoulders of the grooves of the adjacent rolls) is set to 0.9 mm in the first stand and 1.6 mm in the second stand. Set. Note that the roll pitch diameter D _P = 400 mm.

The tension between the stands is the first stand P
The rotational speed V ₁ of the roll 1A~1D constituting one fourth the rolling mill 1, increasing by a predetermined amount than the rotation speed V ₂ of the roll 2A~2D constituting the four-roll rolling mill 2 of the second stand P2 Given by Regarding the control of the tension between stands, since the current value applied to the motor that rotates the roll of each stand is equivalent to the difference between the force that rotates the roll and the force that prevents it, for example, the current value By performing the torque control by the control described above, the feedback control of the tension between stands can be performed.

The rolling conditions other than those described above are as follows. For steel type S45C rolling temperature 850 to 900 ° C. roll gap first stand target diameter + 0.4 mm second stand target diameter L / l _d 1.2 to 4.0 each round bar steel obtained by measuring the polarization diameter difference, Hen径FIG. 6 is a graph showing the relationship between the difference and the product diameter. As can be seen from this graph, by sizing rolling with the same roll, it is possible to obtain a round bar material having a high roundness with an eccentricity difference of 0.4 mm or less in an unprecedented wide range of a product diameter of 50 to 55 mm. did it.

In the method of the present invention, since the tension between the stands is controlled to an appropriate value, there is also an effect that buckling, misroll, and the like hardly occur in the material to be rolled.

[0019]

As described above, according to the present invention, the distance L is maintained between two pairs of rolls constituting a four-roll rolling mill, and the value of L is set to an appropriate range. By applying a predetermined amount of inter-stand tension between the first stand and the second stand, it is possible to simultaneously achieve high dimensional accuracy and a wide sizing range with the same roll. In addition, buckling, misroll, and the like hardly occur in the material to be rolled.

As a result, it is possible to roll a product having high dimensional accuracy which does not need to be subjected to secondary processing such as drawing or peeling over a wide range of sizes without performing the number of roll exchanges. Since the rolling time is shortened and a rolling trouble hardly occurs, the effect that the working efficiency is improved is also brought about.

[Brief description of the drawings]

FIG. 1 is a schematic side view for explaining the configuration of the present invention.

FIG. 2 is an enlarged view showing a hollow portion of the first stand of FIG. 1;
FIG. 1A is a large diagram, and FIG. ₁-A₁Line cross section
(B) is A_Two-A_TwoIt corresponds to a line sectional view.

FIG. 3 is an enlarged view showing a hole-shaped portion in the second stand of FIG. 1, and corresponds to a cross section taken along line BB of FIG. 1;

4 is a graph showing the relationship between the interstand tension and the wide rising rate when the L / l _d = 1.

FIG. 5 is a schematic view showing a shape of a groove of a roll used in an example.

FIG. 6 is a graph showing the relationship between the diameter difference and the product diameter of the round steel bars obtained in the examples.

FIG. 7 is a schematic diagram showing an example of a conventional four-roll method.

FIG. 8 is a graph showing a relationship between a distance L and a width expansion rate.

9 is a graph showing the relationship between the ratio of L with respect to the projection contact length l _d (L / l _d) in the roll pair is located in the width spread rate and upstream.

[Explanation of symbols]

1 4 rolling mill 1A~1D roll 2 4 rolling mill 2A~2D rolls O ₁ first reference line O ₂ second reference line P1 first stand

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Sakamoto 1-chome, Kawasaki-dori, Mizushima, Kurashiki-shi, Okayama Pref. No. 2 Sumitomo Heavy Industries, Ltd. Niihama Works (72) Inventor Takeshi Tange 5-2 Sokaicho, Niihama-shi, Ehime Prefecture Sumitomo Heavy Industries, Ltd. Niihama Works (58) Field surveyed (Int.Cl. ⁶ , DB name) B21B 1 / 16,1 / 18 B21B 13/12 B21B 27/02

Claims (1)

(57) [Claims] 1. A rolling mill comprising two four-roll rolling mills for rolling a material from two directions orthogonal to each other with two-to-four rolls, and two rolling mills arranged in series with a rolling direction shifted by 45 ° between the two rolling mills. In the method of sizing and rolling a bar by a row, in the four-roll rolling mill of the first stand arranged on the upstream side of the two rolling mills, the center line of the axis of one pair of rolls is set to the other pair. The distance between the first reference line projected on a plane parallel to the end face of the roll to be formed and the second reference line connecting the centers of the other pair of rolls on the plane is larger than 0, Among the two roll pairs, the projection contact length of the roll pair located on the upstream side is maintained at 5 times or less, and the tension between stands of the two rolling mills is set to 0.
A sizing and rolling method for steel bars, wherein the method is 10 to 0.30 kgf / mm ² .