JP2900971B2 - Sizing rolling method for round steel bars - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for rolling a material having a substantially circular cross section, which is rolled by an upstream rolling mill row, by two 4-roll rolling mills installed downstream of a rolling mill row. The present invention relates to a sizing rolling method for shaping into a round bar (a bar or a wire having a round cross section), and more particularly to a method capable of obtaining a round bar having high roundness and having a wide sizing range with the same roll.

[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, as shown in FIG. 1 (a), a raw material 1 having a substantially circular cross section by a rolling mill row such as a two-roll rolling mill.
As shown in FIGS. 1 (b) and 1 (c), 0 is rolled by two four-roll rolling mills arranged in series downstream of the rolling mill row by shifting the rolling direction by 45 °.

[0003] Of these two four-roll mills, FIG.
The first-pass four-roll rolling mill arranged on the upstream side shown by (b) has grooves 21a to 21c having a shape in which an arc and an appropriate relief are arranged.
1 is provided with two to four rolls 21 to 24 each having a peripheral surface 24a, and a groove is formed by the grooves 21a to 24d.
The (c) second-pass four-roll rolling mill arranged on the downstream side has grooves 31a to 31d each having a circular arc and an appropriate relief.
The groove 31a to 34a is provided with two-to-four rolls 31 to 34 having a peripheral surface 34a, and the groove of the first pass is formed to have a shape rotated by 45 ° about the pass line. I have.

The roll gaps d ₁ , d ₂ (d _{1) of the} rolls 21 to 24, 31 to 34 of the first pass and the second pass, respectively.
= D ₂ ) is set smaller than the diameter D _{0 of the} raw material 10, and the diameter D _F1 of the portion of the raw material 11 not in contact with the roll in the first pass is equal to the diameter of the raw material 10 before entering the first pass. It is known that it is almost the same as the diameter D ₀ and hardly changes. Similarly, the diameter D _F2 of the portion of the material 12 not in contact with the roll in the second pass is determined by the roll gap d in the first pass.
_It is almost the same as ₁ .

As a result, the cross section of the material 13 after passing through the second pass is formed into a circle close to an octagon as shown in FIG. 1D, and the distances D ₁ and D between the opposing faces of the octagon are formed. ₂ is the roll gap d _{1 of} the first pass and the roll gap d _{2 of} the second pass, respectively.
, And since d ₁ = d ₂ , D
₁ equals approximately D _2. That is, in the rolling by such a four-roll method, the difference between the maximum diameter and the minimum diameter (cross-section difference) in the cross section of the material 13 after passing through the second pass can be suppressed to be smaller than the two-roll method or the three-roll method. Further, as can be seen from FIG. 2 showing the relationship between the width expansion rate and the area reduction rate of the round bar steel obtained by each method, the width expansion rate can be suppressed to be smaller than the two-roll method and the three-roll method.
The effect of rolling conditions such as rolling temperature, steel type, and rolling speed on the cross-sectional dimensions of the material is extremely small, and high dimensional accuracy is obtained.

[0006] With respect to such a sizing rolling method for round bar steel by the four-roll method, in the technique described in Japanese Patent Publication No. 3-6841, the lower limit of the roll gap in the first pass and the second pass is set to ₀ for the material diameter D ₀ . .8 times, the diameter 2R ₁ , 2R of the arc of the groove of each roll of the first pass and the second pass
_2, to not equal to the diameter D ₀ of the material to be 120% of the size, which is desirable in order to widen the sizing range with the same role.

[0007]

However, regarding the dimensional accuracy of the round bar, the roundness of the cross-section circle becomes a problem in addition to whether the diameter of the cross-section circle is a predetermined size. That is, in the case of the four-roll method, regarding the peripheral surface shape of the material 13 after passing through the second pass shown in FIG. 1D, the material 13 comes into contact with the roll grooves 31 a to 34 a in the second pass and the curvature of the circular arc thereof the curvature radius R ₂ moiety formed curvature corresponding to 13a (R ₂ corresponding surface), in a first pass in contact with the roll groove of a radius of curvature R _1, it does not come into contact with the roll groove in the second pass (Fig. 1 (C)
The closer the curvature of the deformed portion 13b (the portion corresponding to the free surface) of the free surface 12b) is, the higher the roundness becomes.

According to the technique disclosed in Japanese Patent Publication No. 3-6841 described above, when the diameter of the material is 50 mm, the diameter 2R ₁ , 2 of the arc of the groove provided in each roll of the first and second passes.
R ₂ is set to 50-60 mm, R ₁ = 30 mm, R
₂ = 25 mm is included. In this case, as shown in FIG. 3, the R of the material 13 after passing through the second pass
₂ curvature radius r _13a of the corresponding surface 13a is approximately 25 mm, the curvature radius r _13b of the free surface equivalent portion 13b is formed approximately 30 mm, minimum diameter D _min 50.0 mm, true becomes maximum diameter D _max 50.4 mm The roundness is low. That is, in this technique, no particular consideration has been given to the improvement of the roundness.

The present invention has been made in view of such problems of the prior art, and a method of sizing and rolling a round steel bar with four rolls can obtain a round steel bar having a high roundness and the same. It is an object of the present invention to provide a method capable of widening a sizing range by a roll.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a method in which a groove is formed by two-to-four rolls provided on a peripheral surface with a groove having a circular arc and a suitable relief. In the mold, two 4-roll rolling mills for rolling down a material having a circular or almost circular cross section from two orthogonal directions are arranged in series with the rolling direction shifted by 45 ° between the two rolling mills. In the method of sizing and rolling a round bar by a rolling mill row, the radius of curvature of the arc of the groove provided in each roll in the four-roll rolling mill arranged upstream of the two rolling mills is R ₁ , the downstream radius When the radius of curvature of the arc of the groove provided in each roll in the arranged four-roll rolling mill is R ₂ , R ₁ / R ₂ = 1.05 to 1.15, and the radius of curvature R ₂ is a material. Of the diameter of the material from the radius of.
A method for sizing and rolling a round steel bar characterized by being set to be smaller by 2 to 2%.

[0011]

According to the method of the present invention, the radius of curvature of the arc of the groove provided in each roll in the four-roll rolling mill arranged on the upstream side among the two rolling mills is R ₁ , and the radius of curvature of the arc arranged on the downstream side is four.
When the radius of curvature of the arc of the groove provided in each roll in the roll rolling mill is R ₂ , R ₁ / R ₂ = 1.05 to 1.1
By setting it to 5, the roundness of the material after passing through the second pass can be increased. The reason is described below.

Material after passing the first pass in FIG. 1 (b)
Of the 11 circumferential surfaces, the rolls 21 to 24 are used in the first pass.
Curvature radius R of circular arc of roll grooves 21a to 24a₁And almost equal
The part 11b (R₁Corresponding surface) is the second pass
Is deformed as a free surface 12b at
The degree of deformation of the steel by examining the difference in rolling reduction
The results are shown in a graph in FIG. The vertical axis of this graph is the material
Indicates the deformation rate of the curvature of the peripheral surface in the second pass.
Corresponds to the free surface 12b of the material 13 after passing through the second pass.
Radius of curvature r of the corresponding portion 13b_13bAnd the first pass low
Radius of curvature R of the arc of the groove provided in the groove₁(R₁Corresponding surface 11b
(Equivalent to the radius of curvature of₁/ R _13bRepresented by
It is. The horizontal axis is the reduction ratio (reduction amount / material diameter D)₀).

As can be seen from this graph, the rolling reduction is large.
The rate of change of curvature R increases₁/ R _13bBecomes larger.
In general, only the roll gap can be
The upper limit of rolling reduction when rolling is changed is about 10%
, But within this range, the curvature change rate R₁/ R_13bBox's
It becomes approximately 1.05 to 1.15 from the graph. Where
The peripheral surface of the material 13 after two passes is shown in FIG.
Thus, the free surface equivalent portion 13b and the radius of curvature r_13aBut
Radius of curvature R of the groove arc provided in the roll of the second pass_TwoNiho
R formed equally_TwoBecause it consists of the corresponding surface 13a,
Radius of curvature r of free surface equivalent portion 13b_13bIs R_TwoEqual to
R if formed_13aIs almost r _13bRoundness equal to
Approaches 100%. Therefore, R₁/ R_Two= 1.
The material after passing through the second pass by setting it to 05 to 1.15
13 has a higher roundness.

Further, according to the method of the present invention, the radius of curvature R ₂ of the arc of the groove provided in each roll in the four-roll rolling mill arranged downstream (ie, in the second pass) is calculated from the radius of the material. by setting only 0.2 to 2% less of the diameter of the material, the aforementioned R ₁ / R ₂ = 1.05~1.1
With the setting of 5, it is possible to widen the range in which sizing rolling can be performed by changing only the roll gap with the same roll while keeping the roundness high, and it is possible to prevent the occurrence of biting. The reason is described below.

First, according to experiments by the present inventors, the radius of curvature R ₂ of the circular arc of the roll groove in the second pass is determined by the radius D _{0 of the} material.
It has been found that the smaller the value is, the wider the sizing rollable range by changing only the roll gap with the same roll. That is, taking the case where the diameter D _{0 of} the material is 50 mm as an example, the radius of curvature R ₂ of the arc forming the roll groove of the second pass is 25 mm, which is the same as the radius of the material, 25.5 mm larger than the radius of the material, and 24.5 smaller than radius
mm, the roll gap of the second pass is 50 to 4 mm.
FIG. 5 is a graph showing the result of examining the deviation in diameter when the distance was changed between 5 mm. However, this result is based on the case where the radius of curvature of the arc of the roll groove of the first pass is R ₁ = R ₂ , the two pairs of roll gaps of each rolling mill are the same, and ideal rolling without roll misalignment is performed. belongs to.

[0016] From this graph, the more the radius of curvature R ₂ of the arc of the roll groove in the second path is smaller than the radius D _0/2 of the material, when the allowable value of the polarization diameter difference are the same, only the roll gap at the same roll It can be seen that the range that can be sizing-rolled by changing the range is widened. Secondly, the radius of curvature R ₁ of the arc of the roll groove in the first path is too small than the radius D _0/2 material, for K flashings as shown in FIG. 6 tends to occur, in order to prevent this it is necessary to somewhat greater than the radius D _0/2 of the radius of curvature R ₁ of the arc of the material of the roll groove in the first path.

These facts and the above-mentioned setting formula R ₁ / R ₂
= 1.05 to 1.15 simultaneously satisfy R ₂ and, when determining when the diameter D ₀ = 50 mm of the material, R ₂ is approximately [D ₀ /2-(0.1～1.0)〕Mm Was found to be appropriate. When applied to an entire different round bar steel material of thickness, equivalent to the R _2, set only 0.2 to 2% smaller radius D _0/2 than of the material diameter of the material.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 7 is a schematic diagram showing the arrangement of rolling mill rows used in this embodiment. As shown in FIG. 7, a rolling mill row in which 18 two-roll rolling mills 1H, 1V to 17H, 18V (H: horizontal stand, V: vertical stand) are arranged in series with the rolling direction shifted by 90 °. downstream, and to the rolling direction and the vertical direction and the horizontal direction 4 rolling mill a _1, the pressing directions shifted 45 ° from the four-roll rolling mill a ₁ a four-roll rolling mill a ₂ arranged in series. The upstream side of the 4-hole shape of the rolling mill A ₁ in FIG. 8 (a), respectively a downstream side of the 4-hole shape of the rolling mill A ₂ in Figure 8 (b).

Each die has two to four rolls 21 to 24, 3
1 to 34, and a central angle θ ₁ ,
A groove is formed by arcs 21A and 34A of θ ₂ = 45 ° and relief portions 21B and 34B extending linearly from both sides of the arc. Here, four-roll rolling mill A 27.5 mm radius of curvature R ₁ of the arc of each roll groove in _1, 4 rolling mill A of the arc of each roll groove in the _two radii of curvature R ₂
Was set to 24.75 mm. Therefore, R ₁ / R ₂ =
1.11, also 4 rolling mill A enters into ₁ Material for a diameter D ₀ = 51 mm (2 roll mill IH, 1V～17H, round steel bar after hot rolled by 18V column) _{, R 2 (= 24.75) =} 25.5-0.75 =
(D ₀ /2)−0.0147·D ₀ , and R ₂ is set smaller than the radius of the material by 1.47% of the diameter of the material.

With the rolling mill train configured as above, hot rolling
When rolling, 4-roll rolling mill A ₁, A_TwoEach role
Gap H₁, H_TwoTo H₁= H_Two= 45.45-50.50m
m, it is possible to directly control various steel materials.
Round steel bars having a diameter of 45 to 50 mm were produced. Round bar obtained
Measure the eccentricity difference of the steel product.
Is graphically shown in FIG. You can see from this graph
As described above, the diameter difference is suppressed to 0.4 mm or less in all sizes.
JIS standard tolerance of deviation diameter 1.05 or less
It was satisfactory enough. Also, the obtained round bar steel
When measuring the roundness of the product, the deviation from the perfect circle
Round bar steel with good roundness in the range of 0.5 to 1.0%
Obtained.

[0021]

As described above, according to the method of the present invention, in the method of sizing and rolling round steel bars with four rolls, round steel bars having high roundness can be obtained, and the sizing range of the same rolls is possible. Can be increased, and the occurrence of biting can also be prevented.

As a result, it is possible to roll a product having high dimensional accuracy, which does not require secondary processing such as drawing or peeling, into a wide size range, and to reduce the number of roll exchanges, thereby greatly reducing the rolling stop time. This shortens the work efficiency and increases the number of types of rolls required, thereby reducing the number of rolls to be held. This has the effect of reducing costs.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a rolling method using a four-roll rolling mill.

FIG. 2 is a graph showing the relationship between the width expansion rate and the area reduction rate by each rolling method.

FIG. 3 is an explanatory diagram showing roundness in the related art.

FIG. 4 is a graph showing the relationship between the rate of change of the curvature of the peripheral surface of the material and the rolling reduction in a downstream four-roll rolling mill (second pass) in relation to the operation of the present invention.

FIG. 5 is a graph showing the relationship between the roll gap of the second pass and the eccentric difference regarding the operation of the present invention.

FIG. 6 is an explanatory diagram showing exudation that occurs during rolling by a four-roll rolling mill.

FIG. 7 is a schematic diagram showing a row of rolling mills used in the example.

FIG. 8 is a schematic diagram showing the shape of a groove of a four-roll rolling mill used in Examples.

FIG. 9 is a graph showing the relationship between the diameter difference and the diameter of the round steel bars obtained in the examples.

[Explanation of symbols]

Reference Signs List 10 material 21 to 24 rolls 21a to 24a grooves 31 to 34 rolls 31a to 34a grooves A ₁ , A ₂ 4 roll rolling mill

──────────────────────────────────────────────────続 き Continued on the front page (72) Norio Kunida, Inventor No. 5-2, Sokai-cho, Niihama-shi, Ehime Prefecture Sumitomo Heavy Industries Machinery Co., Ltd. Niihama Works (72) Inventor, Takeshi Takeshi 5-2, Sokai-cho, Niihama-shi, Ehime No. Sumitomo Heavy Industries Machinery Co., 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 mold is formed by two to four rolls having a circumferential surface with a groove having an arc and an appropriate relief, and a cross section is rolled into a circle or substantially circular in the mold. A two-roll rolling mill for rolling down the rolled material from two directions perpendicular to each other, and sizing and rolling a round bar by a rolling mill row in which the rolling direction is shifted by 45 ° between the two rolling mills. The radius of curvature of the arc of the groove provided in each roll in the four-roll rolling mill arranged on the upstream side of the three rolling mills is R
_1, R ₁ an arc of radius of curvature of the grooves provided in the rolls in four-roll rolling mill disposed downstream when the R ₂
/ R ₂ = 1.05 to 1.15 and the radius of curvature R ₂ is 0.2 to 0.2 to the diameter of the material from the radius of the material.
A sizing and rolling method for round steel bars, which is set to be smaller by 2%.