JP2000158005A - Manufacture of deformed wire and bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a deformed wire and steel bar which is extremely high in dimensional accuracy and excellent in the out-of- roundness of the outside diameter by satisfying the fullness into the nodal grooves of a roll and simultaneously preventing excessive over-filling of longitudinal ribs. SOLUTION: Four-roll mills P1, P2 are arranged at the final two passes of a continuous finish rolling line Ls for wires and steel bars. By controlling the interstand tension between the upstream-side four-roll mill and the rolling mill Lsn just before the same in the range of 0.2-1.2 kgf/mm2, the nodes and over-filled longitudinal ribs in four places of the circumference are formed on the surface of a material to be rolled while controlling the fullness of a material into the caliber of the upstream-side four-roll mill P1 and excess and deficiency of over-filled dimensions of the ribs. By shaping by reducing the longitudinal ribs with the downstream-side four-roll mill P2, the out-of-roundness of the outside diameter is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling method for obtaining a deformed wire rod or a steel bar used for a reinforcing bar or the like embedded in concrete, and more particularly to a method of rolling which exhibits excellent bending workability.
The present invention relates to a rolling method capable of improving the dimensional accuracy of a strip rib shaped wire rod or a steel bar.

[0002]

2. Description of the Related Art As shown in FIG. 1 (a), a general deformed steel bar has a predetermined joint 2 and two vertical ribs 3 on the peripheral surface of a round bar.
Are formed. The diameter D of the portion (free surface) 5 excluding the nodes 2 and the ribs 3, the height t of the nodes 2, the distance L between the nodes 2 adjacent in the axial direction, and the width d of the ribs 3 are determined by JIS standards. In particular, the allowable range of the height t of the node 2 is strictly set. In contrast, FIG.
A four-ribbed deformed steel bar 1 having four longitudinal ribs 3 as shown in (b) is known. The four-rib deformed steel bar does not have torsion or bending in bending during use as compared with a general two-rib deformed steel bar, and has excellent workability.

As a method for rolling this type of 4-rib deformed steel bar, the present applicant has previously proposed a method in which the final finish rolling is performed by a four-roll rolling mill (Japanese Patent Laid-Open No. 7-32330).
2). This compound, in which is disposed a 2 two pair of rolls R _1, as shown _in, R ₂ and R _3, R ₄ in the orthogonal cross shape,
Each of the finishing rolls R _{1 to} R ₄ forming the final finishing pass includes:
In the circumferential groove 6 having an arc-shaped cross section, there are formed node grooves 7 at predetermined intervals along the circumferential direction as shown in FIG. The material to be rolled, which has been rolled into a circular cross section by a row of rolling mills on the upstream side, is rolled down into the round hole die 8 formed by the roll gaps of the _four finishing rolls R _{1 to} R ₄ , and its peripheral surface is reduced. Section 2
To form At the same time, four vertical ribs 3 are formed by biting the adjacent rolls into the gap.

[0004]

However [0007] When producing such a four finishing roll R ₁ to R ₄ in by pressure the circular cross section of the material from the orthogonal direction profiled wire and deformed steel bars, such as: For this reason, there is a problem that the variation in the product dimensions becomes large, and it is particularly difficult to obtain the dimensional accuracy of the outer shape.

That is, the free surface 5 without the node 2 naturally has a large amount of reduction, and the material tends to extend in the longitudinal direction in proportion to the reduction in area. For this reason, the material of the material that would otherwise be supplied to the roll joint groove 7 to become the joint 2 is taken out by elongation, and the meat is pulled down (pulled down) to reduce the joint height t.
Tend to be smaller. This pull-down phenomenon is 4
This can be prevented by adjusting the tension on the entry side to the roll rolling mill to increase the diameter of the material S to be supplied and to increase the degree of filling of the roll groove 7 with the material. However, in this case, the amount of biting of the four rolls into the gap between the adjacent rolls increases at the same time, so that the outer diameter of the longitudinal rib 3 tends to be larger than the outer diameter of the node 2 at this time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and satisfies the filling degree of the roll joint groove, and at the same time, prevents an excessive biting of the outer diameter of the longitudinal rib. Accordingly, it is an object of the present invention to provide a method for manufacturing a deformed wire rod or a steel bar having extremely high dimensional accuracy and good outer diameter roundness.

[0007]

In order to achieve the above-mentioned object, a method for producing a deformed wire rod or bar according to the present invention is performed in the final two passes in a continuous finishing rolling line for a wire rod or a bar.
A roll rolling mill is provided, and the tension between stands between the upstream 4-roll rolling mill and the immediately preceding rolling mill is 0.2 to 1.2 kgf /
mm ² is formed on the surface of the material to be rolled by forming a knot and a circumferential rib at four locations on the circumference, and further shaping the vertical rib with a downstream four-roll rolling mill.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 shows a main part of a continuous finish rolling line for deformed wires and steel bars of the present invention. This is because, after a finishing rolling mill group L for processing a base material S that has passed through a rough rolling mill group and an intermediate rolling mill group (not shown) into a circular cross section, two 4-roll rolling mills P1 and P2 are used as final two passes. The rolling direction is shifted by 45 ° and arranged in series. in this case,
The configuration of the finishing mill group L is not particularly limited. In the illustrated example, the rolling direction of the finishing mill including the _n stands Ls _{1 to} Ls _n is alternately changed in the horizontal and vertical directions and the HV is alternately arranged. However, any other arrangement may be used.

First, the base material S having a square cross section is caliberless-rolled by flat rolls of a group of rough rolling mills while changing the rolling direction alternately between a vertical direction and a horizontal direction, thereby gradually reducing the cross-sectional area of the base material. I will do it. Subsequently, the intermediate rolling mill group is used, and the finishing rolling mill group Ls is alternately pressed down from the vertical direction and the horizontal direction by the oval hole type and the round hole type to form a circular cross section. Finally, the rolling direction is changed to 45
In a round hole type of two 4-roll rolling mills P1 and P2 shifted from each other by two degrees, rolling was performed from two orthogonal directions by two-to-four rolls each having a groove, as shown in FIG. 1 (b). A deformed steel bar 1 having a section 2 and four vertical ribs (hereinafter simply referred to as ribs) 3 formed on the peripheral surface is manufactured.

[0010] At this time, 4
Tensioning the material to be rolled between the rolling mill P1 on the upstream side and its immediately preceding the previous rolling mill (round hole type) Ls _n of the rolling mill (round hole type). Even if the tension is applied by adjusting the number of rolls of both rolling mills by a single drive system in which each rolling mill is driven by a dedicated motor, the roll gap is adjusted by a common drive system in which a plurality of stands share a drive motor. Although it may be carried out only by itself, a single drive system is preferable from the viewpoint of assuring more precise dimensional accuracy. For example, by adjusting the rotation of the motor by a load relay or a motor load current value during rolling, the upstream four-roll rolling mill P1 is adjusted.
That it is possible to roll while quickly and finely control the tension applied to the material to be rolled between the rolling mill Ls _n immediately before.

The rolls R _{1 to} R ₄ of the four-roll rolling mills P 1 and P 2 in the final pass include the rolls R ₁ and R ₂ shown in FIG.
Similarly to the above, a circumferential groove 6 having an arc-shaped cross section is formed on the peripheral surface of the roll, and a nodal groove 7 having a predetermined width and a predetermined interval is formed on the groove surface of the circumferential groove 6 perpendicularly to the circumferential direction.

A four-roll rolling mill P having such a groove shape
2 to 4 rolling rolls R of 1₁~ R _FourRow formed by
Rolled material on the entry side of the gap 8 (that is, round hole type)
Rolling roll R while applying tension to S₁~ R_FourDepress with
You. In this case, the immediately preceding rolling mill Ls_nSupplied from round hole type
The material S to be rolled has a substantially round cross section as shown in FIG.
is there. The outer diameter H of the material to be rolled is the pressure of the four-roll rolling mill P1.
Roll roll R₁~ R_FourCircle formed by the groove bottom 7a of the joint groove 7
The diameter of the cross section (hereinafter referred to as “knot head diameter”) L_7aAbove
You.

The material S to be rolled through the round hole die as described above
Diameter H of the roll hole type_7aIf greater than,
In the state where tension is applied to the material S to be rolled, the rolling roll R₁
~ R _FourWhen rolling down, the material to be rolled S is in the longitudinal direction
Elongation due to tensile stress in addition to the elongation to the outside diameter H
Is rolled while reducing the diameter more than without tension.
You. However, as the outer diameter is large, extra material rolls
Since it is supplied into the grooved groove 7, the round grooved groove is provided.
7 is good, no large pull-down
No. Therefore, the knot height t of the product deformed bar 1 is reduced.
No roundness is good.

At this time, the material S to be rolled is formed in the gap between the adjacent rolling rolls R _{1 to} R _4, which is the non-rolled portion, and the ribs 3 of the deformed steel bar are formed (FIG. 5). .
The chew 10 defines a rib outer diameter dimension L ₃ of the deformed steel bars, because the rolling force is not loaded, when it is rolling without tension, ribs profiled steel bar products are as shown in FIG. 6 outer diameter L ₃ becomes considerably larger than Fushigai径L _2. However, by performing rolling while applying tension, the diameter reduction rate of the outer diameter H of the entry-side rolled material S supplied to the round-hole die (the ratio of the diameter reduction amount to the original outer diameter H) is larger. As a result, the biting of the rib 3 is also reduced.

[0015] Figure 7, the size of the interstand tension between the immediately preceding rolling mill Ls _n upstream 4 rolling mill P1 and the rib outside diameter L
₆ is a graph showing the relationship with ₃ . As shown in the figure, the magnitude of the inter-stand tension is 0 to 0.2, 0.5, 1..
As it increases to ² kgf / mm ² , the biting of the ribs 3 formed by the upstream four-roll rolling mill P1 decreases, and the rib outer diameter L ₃ decreases, and the target outer diameter L ₂ gradually decreases. It can be seen that it approaches.

[0016] In the present invention, the chew of the path upstream 4 rolling mill P1, the protrusion of Fushigai径L ₂ larger than the outer diameter L ₃ ribs 3 formed with a subsequently And the shape is reduced by the pass of the 4-roll rolling mill P2 on the downstream side. In the upstream four-roll mill P1, for example, a pair of two rolls R ₁ and R ₃ are vertically opposed to each other, and
_{When 2} and R ₄ are horizontally opposed to each other, the ribs 3 are formed to bite obliquely at 45 °. In the four-roll rolling mill P2 on the downstream side, the rolling direction of each pair of rolls R ₁ , R ₃ and R ₂ , R ₄ is obliquely shifted by 45 ° from the cross so that the rib 3 is shaped and reduced.

FIG. 8 shows ribs 3 formed by biting in the path of the upstream four-roll mill P1 in this manner.
Is schematically illustrated in a state where the shape is reduced by a pass of a four-roll rolling mill P2 on the downstream side. At this time, if the amount of protrusion a of the rib 3 from the node 2 in the former four-roll rolling mill P1 is too large, the amount of reduction in the rib becomes too large, and the material to be rolled rotates as indicated by the arrow symbol θ. The portion moves from the position (a) to the position (b), that is, the position of the roll plow, and as a result, the rib 3 remains unpressed.

Therefore, it is necessary to control the magnitude of the tension between stands between the upstream four-roll rolling mill P1 and the immediately preceding rolling mill L4 so that the protrusion amount a of the rib 3 does not become excessive. 0.2 kg / mm ² or more is required. On the other hand, there is a limit in the accuracy of the shapes and dimensions of the wires and bars that can be produced by hot rolling, and the resulting rolled material does not have a perfect point-symmetric cross section. When an excessive tension is applied during the rolling of such an asymmetric cross-section material, the material to be rolled is rotated by generating a rotational moment. For this reason, while exiting from the upstream four-roll rolling mill P1 and entering the downstream four-roll rolling mill P2, the portion of the rib 3 is shifted from the proper position (a) to the roll clearance (b). The ribs 3 have moved, so that the ribs 3 remain undepressed. As described above, the limit of the tension to be applied to the material to be rolled is 1.2 kg /
It was found to be mm ^2.

[0019] That is, in the rolling method of the profile wire-bars of the present invention, the magnitude of the tension applied between the upstream side 4 stand rolling mill P1 and the immediately preceding rolling mill Ls _n is
0.2 to 1.2 kg / mm ² . As mentioned above,
When the tension is less than 0.2 kg / mm ² , the supply amount of the material to be rolled becomes excessive and the biting of the rib 3 becomes excessive. Is rotated so that no reduction is made at an appropriate position, and the product has a defective rib outer diameter. On the other hand, the upper limit is 1.2 kg / mm
^{If the} tension exceeds ² , the material to be rolled having an asymmetrical cross section rotates, and as a result, as described above, the appropriate rolling reduction is not performed in the downstream four-roll rolling mill P2, and the product has poor rib outer diameter dimensions. . EXAMPLES way entry side dimension of the rolled material S to the upstream side four-roll rolling mill P1 is a diameter of 10.5 mm, interstand tension between the upstream side four-roll rolling mill P1 and the immediately preceding rolling mill Ls _n Was adjusted to about 0.4 to 0.7 kg / mm ² .

Roll hole die 8 of upstream four-roll mill P1
The dimensions of are shown in FIG. The diameter of the roll hole was 9.0 mm, and the diameter between the groove bottoms 7a of the joint grooves was 10.0 mm. FIG. 10 shows the dimensions of the roll die of the downstream four-roll mill P2. The radius of curvature R of the surface of each of the rolls R _{1 to} R ₄ that presses the rib 3 =
5.2 mm, and the opposing interval was 9.9 mm. As a result, a deformed steel bar product that passed the JIS standard was manufactured.

[0021]

As described above, according to the method for rolling deformed wire rods and bars according to the present invention, a four-roll rolling mill is used in the last two passes, and the entrance tension of the upstream roll rolling mill is controlled within a predetermined range. And the ribs are pressed down and shaped by the downstream roll mill, which prevents excessive biting of the ribs and rotation of the material. As a result, the dimensional accuracy of the deformed wire rods and bars that are products The effect of improving is produced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a deformed steel bar, in which (a) is a two-rib deformed steel bar, and (b) is a four-rib deformed steel bar.

FIG. 2 is a front view illustrating a roll arrangement of a four-roll rolling mill.

FIG. 3 is a schematic diagram showing an example of a roll groove of a final finishing mill for deformed bar rolling.

FIG. 4 is a schematic diagram showing an example of a path schedule according to the present invention.

FIG. 5 is a sectional view showing a dimensional relationship between a roll die and a material to be rolled in a four-roll finishing mill of the present invention.

FIG. 6 is a view showing an example of a cross-sectional shape of a deformed steel bar when rolled by an upstream roll mill without applying tension.

FIG. 7 is a graph showing the relationship between the stand-to-stand tension between the upstream four-roll rolling mill and the immediately preceding rolling mill and the protrusion size of the rib.

FIG. 8 is a diagram illustrating the effect of the inter-stand tension on a downstream four-roll rolling mill.

FIG. 9 is an explanatory view of a groove shape of an upstream four-roll rolling mill in an embodiment.

FIG. 10 is an explanatory diagram of a groove shape of a downstream four-roll rolling mill in an embodiment.

[Explanation of symbols]

2 Section 3 ribs 7 Fushimizo R ₁ roll R ₂ roll R ₃ roll R ₄ roll S material being rolled P1 upstream 4 rolling mill P2 downstream four-roll rolling mill Ls _n upstream 4 rolling mill immediately before rolling mill

Claims (1)

[Claims] 1. A four-roll rolling mill is disposed in the last two passes in a continuous finishing rolling line for wire rods and steel bars, and the tension between stands of the upstream four-roll rolling mill and the immediately preceding rolling mill is set to 0.
A node and four circumferential ribs are formed on the surface of the material to be rolled at a pressure of ^{2 to} 1.2 kgf / mm ² , and the downstream rib 4 is formed.
A method for producing deformed wire rods and bars, wherein the vertical ribs are pressed down and shaped by a roll rolling mill.