JPH07214218A - Method for rolling deformed bar with threaded knot - Google Patents

Abstract

PURPOSE:To equalize the height of threaded knots and also to prevent deviation in a rolling direction by arranging a rolling equipment in which a caliber with a specific necking is formed and thereby performing advance rolling for necking parts only. CONSTITUTION:In order to roll a deformed bar with threaded knots, rolling is performed for forming a base bar material 31 with an elliptical cross-section; and then, while a necking is formed in its center, rolling is performed to make a cross section in the shape of the figure 8. The base bar material 11 with the cross section in the shape of the figure 8 is rolled from the circular cross section side by a pair of rolling rolls for forming threads. Then, in the rear side of the rolling mills 7, 8 for forming the elliptical cross-section, undriven rolls 17, 18 are arranged in which a caliber is formed in such profile that the radiused shape part of the draw-down is the same as or less than the necking in the rolling for the cross-section in the shape of the figure 8, that the depth of the necking is not more than 80% of the whole height, and that the remainder is nearly the same as the base bar material 11 with the elliptical cross-section; and the only the necking part is rolled in advance. Consequently, the deviation is reduced for the two threaded knots oppositely facing.

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 deformed bar steel with a threaded joint, in which the heights of opposing threaded nodes formed in the cross section of the deformed steel bar with a threaded joint are the same and the The present invention relates to a rolling method capable of preventing deviation.

[0002]

2. Description of the Related Art Deformed bar steel with a threaded joint is advantageous not only in weather but also in terms of construction period when using it.
It has been widely used in recent years because it is used for a wide range of applications when it is not allowed except for mechanical joints, and is suitable for the case where a step is formed in the joint section, which causes problems. Its shape is as shown in FIGS.

As shown in FIGS. 6 and 7, the shape of the ordinary deformed steel bar has a joint 4 effective for adhesion tensile strength with concrete and a rib 6 which must be formed by rolling molding. The rib 6 has a strong meaning in shaping because a large metal flow is generated between the pair of rolls when the node 4 which is a protrusion having a large height is formed on the final roll of rolling. It is not particularly effective in improving adhesion.

On the other hand, since the deformed steel bar with a threaded joint is fitted by the coupler joint, there is no rib 6 unlike the ordinary deformed steel bar, and as shown in FIGS.
A portion corresponding to the rib between 6 has a thinned shape 26.

FIG. 8 shows a conventional rolling stand arrangement for producing deformed bar steel with a threaded joint and the hole shape of each rolling stand. The feature is 1 of the last stand
It has the hole shape of the N-1 stand in front of the table, and the position is previously dented by rolling the N-1 stand so that no protrusion is generated between the rolls in the rolling of the final N stand, so that it has an 8-shaped cross section. (For example, Japanese Patent Publication No. 2-24601)
Issue).

As shown in FIG. 8, the ordinary deformed steel bar can be manufactured by rolling the N-3 stand and then the N stand, whereas two passes of the N-2 and N-1 stands increase. N
-The meaning of the stand is that the arrangement of the stands is horizontal and vertical, and the number of stands is increased, which is unavoidable, and the deformed steel bar with a threaded joint improves joint rigidity with the coupler. It is necessary to make 16 a uniform height at any position in the circumferential direction, and this is meaningful for shape adjustment.

[0007]

The conventional method for manufacturing a deformed steel bar with a threaded joint has been described above. In order to form such an 8-shaped cross section, rolling on an N-1 stand is performed. The following problems are likely to occur. That is, as shown in FIG. 9, in the biting stage of rolling, the oval material 31
Since the flat part of the material is rolled by a hole type having a protrusion and the width dimension of the material 31 is narrower than that of the hole type, the material 31 is easily rolled to the left and right, and the stand in case of such offset rolling is performed. The material of the 8-shaped cross section in
As shown in FIG. 10 (a) or FIG. 10 (b), unevenness occurs due to one side being biased.

11 (a) to 11 (c) show uneven thickness 8
11 shows a state in which the material 11 having a V-shaped cross section is sequentially rolled down by the rolling rolls 12 and 13.
(A) shows the initial state of biting, and (b) of the same figure, the material is deformed like 11a at an intermediate stage. The same figure (c) shows the final state, the material is transformed into 11b and the product 14
Becomes

12 and 13 show the form of the rolled product 14 thus produced. As a result, due to the influence of the uneven thickness, the height of one of the joints 15 becomes insufficient, and the heights H ₃ and H ₄ are not equal to each other as compared with the other joint 16, and H ₃ <
A defective product with H ₄ is generated. Also, at this time, one section 1
5 and the other node 16 have different rolling reductions, so the amount of advancement is different, and the node position in the rolling direction is deviated, which causes a problem that the coupler joint cannot be inserted during the construction.

As described above, in order to make the heights of the nodes facing each other in the final product the same and to prevent the nodes from shifting, the 8-shaped cross-sectional shape is a key point, and uneven thickness is generated. It is important not to have it. As a rolling method therefor, there is, for example, Japanese Examined Patent Publication No. 2-24601, and FIG. 14 shows the rolling stand arrangement and the hole type, and FIG. 15 shows the rolling process of the 8-shaped cross section in the N-3 stand. Is.

In the rolling of the N-1 stand, a steel bar material 21 having a rectangular cross section is used as an entry side material, which is twisted 45 ° behind the N-4 stand and supplied to the pair of rolls 19 and 20. FIG. 15A shows an initial state in which the steel bar material 21 having a rectangular cross section starts to be caught in the rolls 19 and 20, and FIG. 15B shows a state in which the steel bar material 21 is compressed by the rolls 19 and 20. FIG. 15 (c) shows a material having an 8-shaped cross section finally obtained by rolling with the rolls 19 and 20.

That is, according to Japanese Patent Publication No. 2-24601, the rolls 19 and 2 are provided at the initial stage of the biting of the steel bar material 21.
At the X portions of the inclined side walls 30 on both sides in 0, the convex portions 28 of the roll contact the steel bar material 21 while restraining the corner portions of the material 21 from all sides, and the rolling is continued as shown in FIGS. 15 (b) and 15 (c). As a result, the central depression, that is, the constricted portion of the figure 8 can be correctly rolled, so that it is possible to roll the section of the figure 8 without deviation.

The rolling of the N-2 stand shown in FIG. 14 has the purpose of making the joints uniform in height at any position in the circumferential direction in order to improve the joint rigidity, as described in the above-mentioned conventional manufacturing method. And the rolling of N-1 stand is more accurate 8
It is expected that the purpose is to obtain a V-shaped cross section.

However, in the rolling method of Japanese Patent Publication No. 2-24601, the restraining force is weak against the inclination of the steel bar material 21 due to the restraint by four points, and the state shown in FIG. 16 tends to occur. That is, in the initial state of the bar steel material being bitten into the roll, the bar steel material is not always bite exactly as described in Japanese Patent Publication No. 2-24601, and as shown in FIG. Even if the steel bar material 21 is tilted, the convex portions 28 of the rolls come into contact with each other while being constrained by the four points Xa, so that the rolling is stable in this case as well. As a result, the final figure-eight cross section on the N-3 stand is shown in FIG.
As shown in Fig. 6 (c), the convex portions on the upper right and lower left sides are lacking in thickness, and the left and right surfaces formed between the rolls also have an oblique shape, and due to the influence, the final rolled material of the N stand has uneven node heights, etc. Problem occurs.

[0015]

DISCLOSURE OF THE INVENTION The present invention provides a new rolling method for solving the problems of the prior art such as the deviation of one side of the material having the figure-eight cross section and the inclination described above. is there. That is, rolling is performed to form an oval cross section, then the circular cross section is widened while forming a constriction in the center of the straight portion of the steel bar material having the oval cross section, and rolling is performed to form an 8-shaped cross section. In a rolling method for producing a deformed bar steel with a threaded joint by rolling a bar steel material having an 8-shaped cross section from a circular section side with a pair of threaded bar forming rolling rolls, a rolling machine for forming the elliptical section Behind the, the R of the constriction is the same or less than the constriction in the figure 8 rolling, and the constriction has a constriction of 80% or less of the total height, and the other is the ellipse. This is a rolling method for deformed bar steel with a threaded joint, characterized in that a non-driving roll device having a hole shape having substantially the same profile as the bar steel material of the cross section is arranged, and the preceding rolling is performed only on the constricted portion.

There are two characteristics, and the first is that the conventional rolling method causes unevenness in the steel bar material, which results in Japanese Patent Publication No. 2-246.
The rolling method of No. 01 is an improvement to the problem that the restraining force against the inclination of the steel bar material is weak. The second one is to use the non-driving roll without newly adding the rolling stand to solve the first problem. is there.

[0017]

The above two features will be described in detail with reference to the drawings. FIG. 1 shows a rolling stand arrangement and a hole shape of each rolling stand for explaining a rolling method of a deformed bar steel with a threaded joint according to the present invention. The feature is clear when compared with FIG. 8 which illustrates the conventional rolling method described above,
Non-driving rolls 17 and 18 added immediately after the N-2 stand
And its hole type.

FIG. 2 shows the concept of the hole type, which is the first feature of the present invention, in which the restraint force against the inclination is strengthened simultaneously with the deviation of the steel bar material. In the present invention, the steel bar material 31 to be rolled by the N-2 stand uses an elliptical cross-sectional shape at the same time as the conventional rolling method, and the bar steel material 11 having an 8-shaped cross-section to be rolled at the next N-1 stand is used. A new hole type was added. The hole shape is the same as or less than the constriction of the constriction of a steel bar material 11 having an 8-shaped cross section that is rolled by an N-1 stand, and the constriction has a constriction depth of 80% or less of the total height. And the others have almost the same profile as the bar steel material 31 having an oval cross section rolled by the N-2 stand, while restraining the entrance side bar steel material 31 having an oval cross section shape by the rolls 17 and 18. Since the constriction is preformed, the constriction can be accurately formed in two places at the upper and lower sides of the center of the entry side steel bar material 31 having an oval cross section. The size of R of the constriction is a steel bar material with an 8-shaped cross section that is rolled by the N-1 stand 11
It is suitable that it is the same as or slightly smaller than R of the constriction.

Thus, the steel bar material 32 whose pre-neck is accurately preformed is offset in the conventional rolling method, and in the rolling of the N-1 stand in which an inclination is generated, in the N-1 stand having a larger width than its own. Even if the hole type is bitten in a state where the center in the width direction is slightly displaced, the constriction moves following the hole type convex portion 28 of the N-1 stand, so that the deviation occurs in the N-1 stand. Even if it is not bitten, or if it is bitten in a slightly inclined state, the upper and lower constrictions follow the hole-shaped upper and lower convex portions 28 of the N-1 stand, so that the inclination is corrected and the N-1 stand is inclined. do not do.

FIG. 1 also shows a non-driving roll device 33 which is the second feature of the present invention. As described above, the present invention adds one new rolling pass to the conventional rolling method. In order to do this on a rolling stand, the number of stands must be increased because the stand arrangement is a horizontal and vertical alternating arrangement, as described above, which increases the cost of roll preparation and the downtime due to an increase in the number of stand replacements. Leads to an increase in In the present invention, in order to solve these problems, a non-driving roll device 33 is installed behind the N-2 stand.

[0021]

EXAMPLE FIG. 3 shows an example of a rolling method for deformed bar steel with a threaded joint according to the present invention. The non-driving roll device 33 is fixed to the delivery side bulken 34 of the N-2 stand main body, and the non-driving rolls 17 and 18 are arranged in a direction perpendicular to the rolls 7 and 8 of the N-2 stand. As shown in FIG. 2, a hole mold having an oval cross section with a preformed neck is provided. The steel bar material in which the constriction is preformed in the elliptical section by the non-drive roll device 33 moves to the right in FIG.
It is rolled into a figure-eight section with a stand.

[0022]

FIG. 17 shows the actual data of the thread knot height of size D25, where the horizontal axis indicates the thread knot height and the joint axis indicates the N number, and FIG. 17 (a) shows the result of the conventional rolling method. 17 (b) shows the results of the rolling method of the present invention. JIS specification range 1.3
In contrast to ˜2.6 mm, the lower limit of the conventional rolling method was sometimes exceeded, but the application of the present invention brought it into the range. In addition, the maximum value of the actual value is 2.0 mm because the hole type screw node height is 2.0 median of the JIS specification range.
Since the work piece is machined in mm, the thread knot height may increase as the roll wears, in which case the bar graph in FIG. 17 shifts to the right. Although not shown in the figure, the deviation of the screw joints at two opposite locations is also reduced by the application of the present invention.

[Brief description of drawings]

FIG. 1 is an explanatory view of a rolling stand arrangement of the present invention and a hole shape of each rolling stand.

FIG. 2 is a detailed view of the hole type of the present invention.

FIG. 3 is an explanatory diagram of an embodiment of the present invention.

FIG. 4 is an explanatory view of the shape of a deformed steel bar with a threaded joint.

FIG. 5 is an explanatory view of the shape of a deformed steel bar with a threaded joint.

FIG. 6 is an explanatory view of the shape of an ordinary deformed steel bar.

FIG. 7 is an explanatory view of the shape of an ordinary deformed steel bar.

FIG. 8 is an explanatory view of a conventional rolling stand arrangement and a hole shape of each rolling stand for producing a deformed bar steel with a threaded joint.

FIG. 9 is an explanatory view of a state where deviation occurs in conventional rolling.

FIG. 10 is an explanatory diagram of a state where deviation occurs in conventional rolling.

FIG. 11 is an explanatory view showing a state where a bar steel material having an uneven thickness and having an 8-shaped cross section is rolled into a product.

FIG. 12 is a shape diagram of a product made by rolling shown in FIG.

FIG. 13 is a shape diagram of a product that can be produced by rolling shown in FIG.

FIG. 14 is an explanatory view of the rolling stand arrangement of the cited patent that provides a rolling method for a steel bar material having an 8-shaped cross section without uneven thickness and the hole shape of each rolling stand.

FIG. 15 is an explanatory diagram of the progress of rolling of the 8-shaped cross section in the rolling of FIG.

FIG. 16 is an explanatory diagram of the progress of rolling when the entry side material is inclined and bites in the rolling of FIG. 15.

FIG. 17: Conventional rolling method (a) and inventive rolling method (b)
Figure showing comparison of actual data of screw joint height

[Explanation of symbols]

4 Ordinary Deformed Steel Bar Section 6 Ordinary Deformed Steel Bar Rib 7,8 For rolling steel bar material with an oval cross section 11 8 Steel bar material with an 8-shaped cross section 12,13 Roll for final pass rolling 14 Product of Deformed Steel Bar with Screw Nodes 15, 16 Threaded Deformed Steel Bar Section 17,18 Non-Drive Roll 19,20 Roll for Rolling Steel Bar Material with Referenced Patent 8 Shaped Section 21 Entry Steel Bar Material for Rolls 19, 20 26 Missing Deformed Steel Bar with Threaded Node Meat shape 288 Convex portion of roll having a cross section of 8 30 Hole-shaped sloping side wall of rolls 19 and 20 31 Steel bar material having an oval cross section 32 Steel bar material preformed with a constriction 33 Non-driving roll device 34 Exit side balken

Claims (1)

[Claims] 1. Rolling to form an elliptical cross-section, and then to widen the circular cross-section while inserting a constriction in the center of the straight portion of the steel bar material of the elliptical cross-section to form an 8-shaped cross-section. In the rolling method for producing a deformed bar steel with a threaded joint, the steel bar material having the 8-shaped cross-section is rolled from the side of the circular section with a pair of threaded-roll forming rolling rolls. Behind the rolling mill, the R of the constriction is the same or less than the constriction in the figure 8 rolling.
And the depth of the constriction has a constriction of 80% or less of the total height, and the others have a non-drive roll device that forms a hole shape of almost the same profile as the steel bar material of the oval cross section, and precedes only the constricted part. A method for rolling a deformed steel bar with a threaded joint, which comprises rolling.