JP3228868B2 - Sizing rolling device and rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sizing rolling apparatus and a rolling method for producing linear or bar steel having a circular cross section.

[0002]

2. Description of the Related Art Conventionally, as sizing rolling using a four-roll rolling mill, for example, there is one described in Japanese Patent Application Laid-Open No. 62-199206.

[0003] This sizing rolling apparatus is constituted by arranging two four-roll rolling mills whose rolling directions are inclined at 45 degrees to each other in series along a rolling line. Same or 120% as the diameter of the rolled material circle
An arc-shaped perfect circle forming portion having a large diameter and an appropriate relief portion continuous to the left and right of the perfect circular forming portion.

Here, for the purpose of suppressing the deviation in diameter, it is considered that the angle of the relief portion of the roll hole type should be as large as possible without causing flaws. It is determined in consideration of the range (size range of a product that can be manufactured by changing the roll gap using the same hole type roll) and the dimensional tolerance of the product (for example, JIS tolerance).

That is, since the holding angle of the cross section of the material to be rolled by one rolling roll is 90 degrees, the above-mentioned Japanese Patent Application Laid-Open No.
No. 99206 describes that a central angle (hereinafter simply referred to as a central angle) of a roll hole type perfect circle forming portion is selected as small as possible in consideration of a size free range and a dimensional tolerance.

[0006]

However, the center angle is not determined only by the size-free range and the dimensional tolerance, but is determined by a four-roll mill in which normal rolling without surface flaws occurs. This is also a major factor.

That is, in a four-roll rolling mill, unless the material to be rolled passes through the centers of four radially arranged roll cavities, biting occurs as shown in FIG. It becomes defective with scratches. Here, FIG.
In the figure, 50 indicates a rolling roll, and 51 indicates a material to be rolled. The same applies to FIG.

Further, when the material to be rolled rotates between each pass, the material to be rolled is twisted, and as shown in FIG. 9, the material to be rolled becomes defective in size. As described above, it is possible to design a hole shape in consideration of the size free range and the dimensional tolerance only after normal rolling is performed, but there is a problem that the conventional technology does not consider this point.

In other words, the size-free range that can be actually used while securing the desired dimensional accuracy and surface properties by conventional sizing rolling due to the occurrence of biting and the like as described later is larger than the range based on geometrical inference. Narrows.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a sizing rolling which can secure a predetermined size-free range while securing predetermined dimensional accuracy and surface properties. And

[0011]

In order to solve the above-mentioned problems, a sizing rolling apparatus according to the present invention comprises an arc-shaped perfect circle forming portion formed at the center and an appropriate continuous right and left continuous right and left portions of the perfect circle forming portion. A sizing rolling device that installs a plurality of four-roll rolling mills using rolling rolls provided with a groove formed of a relief portion along a rolling line, and sizing-rolls a material to be rolled having a substantially circular cross section. In the above, three or more four-roll rolling mills are installed in series, and the center angle of the perfect circle forming part of each roll roll die is set to 15 degrees or more in the first pass and 45 degrees or more in the final pass, It is characterized in that it is set at 30 degrees or more in the intermediate path.

Here, the central angle of the perfect circle forming part is the angle of the arc of the perfect circle forming part as viewed from the center of the four rolling rolls arranged radially. The contour of the relief portion is, for example, a straight line inscribed in the perfect circle forming portion or a curve having a smaller curvature than the perfect circle forming portion.

When the contour shape of the perfect circle forming part is an arc shape, the centering property is not as good as that of a square shape. However, in the present invention, the central angle of the hole-shaped perfect circle forming part is limited as described above. Thus, the adverse effect of the centering property of the material to be rolled based on the shape of the groove is suppressed, and the rotation (falling) of the material to be rolled between passes can be reduced.

Here, the grounds for the above operation and the limitation of the numerical values will be described. In a four-roll rolling mill as shown in FIG. 2A, a material to be rolled having a substantially circular cross section was rolled by changing the center angle θ ₁ of the roll hole type perfect circle forming portion in various ways. The result as shown in FIG.

In the above experiment, the centering property of the material to be rolled after rolling is expressed by the difference Δb between the maximum diameter and the minimum diameter of the dimension at a position shifted by 45 degrees from the rolling direction. As can be seen from FIG. 4, when the central angle θ ₁ is smaller than 15 degrees from about 15 degrees, the difference Δb
It suddenly becomes large, and the centering effect by the hole type is reduced.

This tendency is noticeable at the leading end and the tail end of the material to be rolled, as shown in FIG. 5, and when this material starts to bite, it is discarded as a defective part. Accordingly, from FIG. 4 described above, the central angle θ ₁ of the perfect circle forming portion in the first pass is obtained.
It can be understood that by setting the angle to 15 degrees or more, the centering can be improved. Therefore, in the present invention, the central angle of the first pass is set to 15 degrees or more.

Next, as shown in FIGS. 2 (a) and 2 (b), in two four-roll rolling mills whose rolling directions are shifted from each other by 45 degrees and arranged in series, the rolling rolls 5 in the second pass are used. The inclination of the material in the second pass B (rotation of the material between the passes) was measured by changing the central angle θ ₂ of the perfect circle forming portion 5a, and the result shown in FIG. 6 was obtained.

Here, in FIG. 6, a solid line indicates a case where the central angle θ ₁ of the perfect circle forming portion 4a in the first pass A is set to 15 degrees, and a broken line indicates a perfect circle in the first pass A. The central angle θ ₁ of the forming portion 4a is set to 30 degrees, and the dashed line indicates the first angle.
The central angle θ ₁ of the perfect circle forming portion 4a in the path A is set to 45 degrees.

The tilt angle β is calculated indirectly by measuring α shown in FIG. here,
In FIG. 7, reference numeral 20 denotes a material to be rolled, and reference numeral 21 denotes a rolling roll. Α is the angle of the relief surface.

[0020] As can be seen from FIG 6, regardless of the value of the central angle theta ₁ of the first path A, which is set more than 15 degrees, the center angle theta ₂ of the perfect circle forming section 5a of the second pass B is If the angle is less than 30 degrees, the inclination angle β suddenly becomes large, and it may be difficult to continue the subsequent rolling, and an unstable rolling region such as a high possibility of occurrence of surface flaws due to digging out. Become.

Conversely, it can be seen that the inclination angle β decreases as the central angle in the intermediate pass increases, and that the inclination angle β becomes almost zero when the central angle exceeds 45 degrees. Therefore, by setting the central angle of the perfect circle forming portion in the intermediate pass to 30 degrees or more, the influence of the fall is reduced. Based on this, the central angle of the intermediate pass was set to 30 degrees or more.

In the final pass, by setting the central angle of the perfect circle forming portion to 45 degrees or more, the inclination approaches zero and the product dimensional accuracy is improved. Based on this, the central angle of the final pass was set to 45 degrees or more.

Note that the central angle of each roll hole die is a value within 90 degrees including the perfect circle forming portion and the relief portion.
The central angle of the perfect circle forming portion of each pass cannot be larger than 90 degrees.

Next, according to the second aspect of the present invention, the central angle of the perfect circle forming portion of each of the roll roll dies becomes larger as it goes toward the succeeding stage. It is characterized by:

As can be seen from the relationship between the central angle of the perfect circle forming portion and the fall angle in the second pass (see FIG. 6), the central angle of the perfect circular forming portion in the second pass is larger in the first pass. It was found that the smaller the central angle of the perfect circle forming portion, the smaller the fall.

Therefore, by setting as in the present invention,
Further, the occurrence of torsion of the material to be rolled during rolling is suppressed, and the surface flaws generated on the product are reduced. Next, the invention described in claim 3 is different from the structure described in claim 1 or 2 in that the rolling directions of the adjacent four-roll rolling mills are mutually set to four.
It is characterized by tilting 5 degrees.

In the present invention, the rolling direction of the adjacent four-roll rolling mill is inclined by 45 degrees with respect to each other, so that the rolling direction is reduced from the direction of the gap between the rolling rolls in the immediately preceding pass, that is,
By rolling around the non-rolled portion in the previous pass, a cross section having a small diameter difference is formed into a perfect circle close to an octagon.

That is, the inclination difference can be suppressed to a small value by inclining by 45 degrees. This is because the entire peripheral surface of the material to be rolled is shaped by a roll hole surface. Next, the invention described in claim 4 corresponds to claims 1 to 3
And a plurality of two-roll rolling mills are arranged upstream of the four-roll rolling mill.

This proposes that the equipment cost of a four-roll mill is higher than that of a two-roll mill, so that it is not always necessary to convert the entire rolling line into four rolls.

In particular, when remodeling a rolling line provided with an existing two-roll rolling mill, only a four-roll rolling mill may be used on the downstream side. By doing so, there is an extremely great advantage in reducing equipment costs.

Next, in a rolling method according to a fifth aspect of the present invention, the roll gap of one or more four-roll rolling mills is changed using the rolling apparatus according to the first to fourth aspects. By doing so, it is characterized in that linear or bar steel having different product diameters is rolled.

In the present invention, by changing the roll gap, it is possible to roll linear or bar steel having different product diameters even when using the same hole type roll.

[0033]

Embodiments of the present invention will now be described with reference to the drawings. As shown in FIG. 1, the rolling equipment of the present embodiment is configured such that a sizing rolling device 2 of the present invention is disposed behind a normal linear block mill 1.

In FIG. 1, the linear block mill 1 is configured by arranging ten two-roll rolling mills in series along a pass line L, and the rolling direction of each two-roll rolling mill is adjacent to each other. It is set at an angle of 90 degrees with the two-roll rolling mill.

The sizing mill 2 is composed of three four-roll mills 3 arranged in series along a pass line L. As shown in FIG. 2, each four-roll rolling mill 3 includes four rolling rolls 4, 5, and 6 arranged radially. The groove shape of each of the rolling rolls 4, 5, 6 is such that arc-shaped perfect circle forming portions 4a, 5a, 6a provided at the central portion for rolling, and the perfect circular forming portions 4a, 4a, 6a.
Appropriate relief portions 4a, 5 formed on the left and right of 5a, 6a
a, 6a. The perfect circle forming portions 4a, 5
The contour shapes of a and 6a are formed by arcs having substantially the same diameter as the diameter of the material 7 to be rolled. Also, the left and right relief portions 4a,
The contour shapes of 5a and 6a are respectively
a, 5a, and 6a, and are formed by a continuous linear shape or a curve having a smaller curvature than the arc of the perfect circle forming portions 4a, 5a, 6a.

Here, the perfect circle forming portions 4a, 5a, 6a
Is not necessarily the same as the diameter of the material 7 to be rolled, and may be set to a diameter slightly smaller or larger than the diameter of the material 7 to be rolled.

Further, the four-roll mill 3 for the first pass A
In the example, the opposing directions of two pairs of roll holes are arranged in the vertical direction and the horizontal direction, respectively, and the rolling direction is set in the vertical and horizontal directions. Further, setting the central angle theta ₁ of the perfect circle forming section 4a of each roll caliber than 15 degrees.

Further, in the four-roll rolling mill 3 for the second pass (intermediate pass) B, the opposing directions of the two sets of roll hole dies forming the pair are arranged at an angle of 45 from the horizontal direction, and the rolling direction is reduced. Is set in a direction inclined by 45 degrees. Also, the central angle θ ₂ of each roll hole type perfect circle forming portion 5a is set to 30 degrees or more.

In the four-roll rolling mill 3 for the third pass (final pass), the opposing directions of the two pairs of roll hole dies are arranged in the up-down direction and the left-right direction, respectively, so that the rolling direction is up-down and up-down. Set to left and right. Also, the central angle θ ₃ of each roll hole type perfect circle forming portion 6a is set to 45 degrees or more.

Next, rolling in the above-mentioned rolling equipment will be described. The material to be rolled 7 is rolled into a substantially circular section by rolling by the linear block mill 1, and is sequentially sent to the sizing rolling device 2.

In the sizing rolling device 2, in the first pass A, the material 7 to be rolled is shaped into a circle that is slightly square.
At this time, the central angle θ ₁ of the perfect circle forming portion 4a in the first pass A
Is set to 15 degrees or more, a decrease in the centering effect can be avoided even if an arc shape is adopted as the contour shape of the perfect circle forming portion 4a.

Next, in the second pass B, the material to be rolled 7 is slightly closer to an octagon by rolling down the boundary portion of the surface reduced in the first pass A which is the largest diameter portion after passing the first pass A. It is shaped into a perfect circle. At this time, by setting the central angle θ ₂ of the perfect circle forming portion 5a in the second pass B to 30 degrees or more, a large fall such that the material 7 to be rolled is produced during the intermediate rolling of the sizing rolling. Does not occur.

Here, the central angle of the perfect circle forming portion 5a in the second pass B can be set to a value of 30 degrees or more. However, as the center angle increases, the angle of the relief portion 5a decreases, and Is determined according to the roundness required for the material 7 to be rolled.

Next, in the third pass C, the boundary portion of the surface reduced in the second pass B, which is the largest diameter portion after passing through the second pass B, is pressed down, and the rolled material 7 is further approximated to a perfect circle. Shape into a cross-sectional shape.

At this time, by setting the central angle θ ₃ of the perfect circle forming portion 6a in the third pass C, which is the final pass, to 45 degrees or more, the rolled material 7 is tilted by the rolling in the third pass C. Is reliably avoided, and the dimensional accuracy of the product can be improved.

Here, in the above-described embodiment, an example is described in which the sizing rolling device 2 is constituted by three four-roll rolling mills 3, but the present invention is not limited to this. For example, four or more four-roll rolling mills 3 may be arranged in series.

Further, it is preferable to set the central angles of the perfect circle forming portions 4a, 5a, 6a in each pass in the sizing rolling device 2 so as to gradually increase toward the subsequent pass. With this setting, the rolled material 7 can be further prevented from falling between passes, and the occurrence of surface flaws can be reduced. For example, the central angle θ ₁ in the first pass A is set to 15 degrees, the central angle θ ₂ in the second pass B (intermediate pass) is set to 33 degrees, and the central angle θ ₃ in the final pass is set to 45 degrees. .

Although it is desirable to increase the center angles θ ₁ , θ ₂ , θ ₃ in terms of prevention of falling and roundness of the product, there is a disadvantage that the size free range is narrowed. An appropriate value may be selected within the range.

[0049]

EXAMPLE In practice, the central angle θ ₁ of the perfect circle forming portion 4a in the first pass A is 15 degrees, the central angle θ ₂ of the perfect circular forming portion 5a in the second pass B is 33 degrees, and the third pass is C, the central angle θ ₃ of the perfect circle forming portion 6 a is set to 45 degrees, the distance between the first pass A and the second pass B is 470 mm, and the distance between the second pass B and the third pass C is It was set to 230 mm. Furthermore, if the roll diameter is 220
mm, the size of the material to be rolled 7 before sizing rolling was 6.8 mmφ, and the product diameter was 5.5 mmφ, and sizing rolling was performed. The product is obtained.

Further, when the relationship between the diameter reduction amount and the dimensional accuracy was obtained under the same conditions as described above, the results shown in FIG. 3 were obtained. Here, 中 in FIG. 3 is based on the present invention. Further, for comparison, Δ indicates that only the first pass A is a flat roll (central angle = 0) and the central angles θ ₂ and θ ₃ in the second and third passes B and C are 33 degrees and 45 degrees, respectively. Is shown. Further, □ indicates that the central angle θ ₂ in the second pass B is 20
This is a comparative example in which the center angles θ ₁ and θ ₃ in the first and third passes A and C are 15 degrees and 45 degrees, respectively.

As can be seen from FIG. 3, in the two comparative examples deviated from the settings based on the present invention, the dimensional accuracy decreased and the generation of surface flaws was observed at higher pressures due to the occurrence of collapse. As a result, the size free range that can be actually used is reduced.

That is, if the first pass A is a flat roll pass, the size-free range seems to be wide if estimated geometrically, but the centering property is reduced and biting occurs. In addition, the size free range becomes narrower. Further, it causes a decrease in dimensional accuracy due to fall too small a central angle theta ₂ of the perfect circle forming section 5a at the middle path, so that the dimensional error occurs frequently.

On the other hand, it can be seen that the use of the apparatus according to the present invention ensures a predetermined dimensional accuracy even under high pressure and does not cause biting. That is, when the apparatus according to the present invention is used, the actual size-free range of the product diameter that can be manufactured with the same roll size is expanded within a range in which a predetermined dimensional accuracy is secured and no harmful surface flaw is generated.

As described above, the size-free range in the range where the accuracy of the product dimensions can be improved and the product surface flaw can be prevented is expanded as compared with the conventional case, and the frequency of the roll change when changing the target product diameter is reduced. I do. As a result, it is possible to reduce the number of man-hours for exchanging rolls and the downtime of equipment.

Further, under the condition that the same roll size is used as the rolling roll, and the dimensional tolerance is within the JIS tolerance and no harmful surface flaw is generated, the size-free range of the product diameter that can be manufactured is different from the conventional one. When the sizing rolling device is composed of two four-roll rolling mills, the size is, for example, 5.5 to 6.0 mmφ, whereas when the sizing rolling device is based on the present invention, the size is 5.5 to 6.3 mmφ. It has also been confirmed that the size-free range usable for the device can be increased by about 1.6 times.

[0056]

As described above, in the sizing rolling device and the rolling method of the present invention, the size free range in which the sizing rolling can be performed while ensuring the predetermined product dimensional accuracy and preventing the generation of flaws on the product surface. Can be improved as compared with the related art.

As a result, the frequency of the roll effect associated with the change of the target product diameter is reduced, and the man-hour for replacing the roll and the equipment downtime can be reduced. In particular, by adopting the invention described in claim 2, the material 7 to be rolled is prevented from falling down, and the size free range in which sizing rolling is possible by further improving product dimensional accuracy and preventing product surface defects from occurring. Spreads.

[Brief description of the drawings]

FIG. 1 is a diagram showing a pass schedule of a rolling facility according to an embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing roll shapes used in sizing rolling according to the embodiment of the present invention, wherein FIG. 2A shows a first pass, FIG. 2B shows a second pass, and FIG. ) Indicate those of the third pass.

FIG. 3 is a diagram showing a relationship between a diameter reduction amount and dimensional accuracy.

FIG. 4 is a diagram showing a relationship between a center angle and centering in a first pass.

FIG. 5 is a view showing a state of centering in a longitudinal direction of a material to be rolled.

FIG. 6 is a diagram illustrating a relationship between a center angle and a tilt angle after a second pass.

FIG. 7 is a diagram for explaining a tilt angle.

FIG. 8 is a view showing a conventional state of biting.

FIG. 9 is a diagram showing a conventional centering defect.

[Explanation of symbols]

Reference Signs List 2 sizing rolling device 3 4-roll rolling machine 4, 5, 6 rolling roll 4a, 5a, 6a perfect circle forming portion 4b, 5b, 6b relief portion 7 rolled material L pass line θ ₁ central angle in first pass θ ₂ Central angle in the second pass θ ₃ Central angle in the third pass A First pass B Second pass C Third pass

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-168202 (JP, A) JP-A-6-501 (JP, A) JP-A-62-199206 (JP, A) JP-A-7-202 100501 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 1/00-1/46 B21B 13/10 B21B 27/02

Claims (5)

(57) [Claims] 1. A four-roll rolling mill using a rolling roll provided with a groove formed by an arc-shaped perfect circle forming part formed at the center and a suitable relief part continuous to the left and right of the perfect circle forming part. A sizing rolling device for sizing and rolling a rolled material having a substantially circular cross section by installing a plurality of rolling rolls along a rolling line. A sizing rolling device wherein the center angle of the roll hole type perfect circle forming portion is set to 15 degrees or more in the first pass, 45 degrees or more in the final pass, and 30 degrees or more in the intermediate pass. 2. The sizing rolling apparatus according to claim 1, wherein the central angle of the perfect circle forming portion of each of the roll roll dies increases toward a subsequent pass. 3. The sizing rolling apparatus according to claim 1, wherein the rolling directions of adjacent four-roll rolling mills are inclined by 45 degrees with respect to each other. 4. The apparatus according to claim 1, wherein a plurality of two-roll rolling mills are arranged upstream of the four-roll rolling mill.
A sizing rolling device according to any one of claims 1 to 3. 5. A wire or bar having a different product diameter is formed by changing a roll gap of one or more of the four-roll rolling mills by using the rolling apparatus according to any one of the above-mentioned claims 1 to 4. A rolling method characterized by rolling.