JPS594902A - Production of metallic material having circular section - Google Patents

Abstract

PURPOSE:To enable the production of a steel material having a circular section such as a round steel bar or the like with high production efficiency by rolling a continuously cast billet with a skew rolling mill having a specific angle of inclination and angle of crossing. CONSTITUTION:A continuously cast billet 30 having center porosity is rolled as a material to be rolled with a skew rolling mill having 3-4 pieces of cone- shaped rolls 31, 32, 33. The rolls 31-33 have gorging parts 31a-33a, inlet surfaces 31b-33b and outlet surfaces 31c-33c, and the axial line X-Y thereof is inclined by an angle gamma of crossing and an angle beta of inclination to the pass line X-X of the material 30 to be rolled. The values gamma, beta are so set as to attain 0 deg.<gamma<15 deg., 3 deg.<beta<20 deg., 5 deg.<gamma+beta<30 deg., whereby the center porosity of the billet 30 is press-stuck. Since the skew rolling mill is used to the continuously cast billet, the steel material having a circular section is rolled easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing circular cross-section metal materials such as round steel bars using an inclined rolling mill.Round bars are generally manufactured through a rolling process using caliber rolls, but the equipment cost A method using an inclined rolling mill has been tried for the purpose of reducing the amount.

The "inclined roll rolling mill" disclosed in Japanese Patent Publication No. 46-43980 is famous as a high-workability rolling mill that can reduce a solid material to a high degree in one pass. FIG. 31 is a front view of the rolled material 10 from the exit side, and FIG. 2 Fi! 1 is a sectional view taken along the line ■-■, and FIG. 3 is a side view showing the inclination angle β. The entrance diameter of the rolled material IO is made sufficiently larger than the exit diameter.
Three cone-shaped rolls 11, 12, and 13 supported at one end (roll axes are indicated by Y-Y) rotate together with a roll housing (not shown) about the pass line X-X1. be. The intersecting angle γ (referred to as α in the above publication), which is an important element in the present invention, is not specified in the publication, but is 50' to -60° (the intersecting angle γ means that the end of the roll shaft is the material to be rolled). 10, the state in which they approach on the inlet side is expressed as positive, and the state in which they approach on the exit side is expressed as negative), and the inclination angle β is similarly designed to be 3° to 6°. As an effect, it is said that the surface twist of the rolled material 10 is small, but according to the experiments conducted by the inventors of the present application, no improvement effect on internal defects such as porosity was observed, and the shearing in the circumferential direction It is unsuitable for manufacturing high-quality round steel bars because of its large distortion.

Also, "Plasticity and Processing" Vol. 7 No. 67 and Vol. 10 No. 1.
In No. 04, papers titled [Research on Helical Roll Processing J] are published as the first and second reports, respectively, and the technology related to this paper is shown in Figures 4 to 6, which are shown similarly to Figures 1 to 3. However, as shown in FIG. 4 (shown from the entry side), three cone-shaped rolls 21.2 supported at both ends are arranged around the rolled material 20.
2.23 is rotated vertically to roll the material to be rolled 20 while rotating, and the intersection angle γ is 0° and the inclination angle β
The experimental results for the case where the angle is 0° to 14° are reported. Although it is thought that by applying this method, the shear strain in the circumferential direction is reduced compared to the above-mentioned known technique, the surface twist becomes thicker. According to the results of experiments conducted by the inventors of the present invention using this technique, a sufficient improvement effect on internal defects such as porosity cannot be obtained. I am reporting again.

As mentioned above, there are many unresolved problems in the conventional round steel manufacturing technology using an inclined rolling mill, and the reality is that it has not been put into practical use.

The present invention was made against this technical background, and its purpose is to provide a method for manufacturing a circular cross-section metal material that can be rolled with a high degree of workability in one pass and has extremely high production efficiency. There is something to do.

Another object of the present invention is that the shear strain in the circumferential direction is extremely small, and even when rolling separated workpieces (those with poor hot deformability),
It is an object of the present invention to provide a method for manufacturing a metal material with a circular cross section in which no inner side n is generated starting from inclusions due to shear stress.

Another object of the present invention is to enable highly efficient production of circular cross-section metal materials from billets (generally having center porosity) produced by continuous casting.
In other words, by reducing shear strain in the circumferential direction to prevent internal fractures originating from porosity, so-called Mannesmann fractures, and by performing sufficient rolling to compress porosity and reduce its n itself, continuous rolling can be achieved. The object of the present invention is to provide a method that enables the production of circular cross-section metal materials by means of a cast billet force and tilt rolling mill.

In the method for manufacturing a circular cross-section metal material according to the present invention, three or four rolls are arranged facing around the pass line, and the axis lines of the rolls are arranged such that the shaft ends on the same side face the same side in the circumferential direction. The shaft end on the inner 1 side can be tilted (crossed) toward or away from the pass line side, and is supported at both ends of the entire roll. Using a cross-type inclined rolling mill, the rolls are rolled into a bar shape with the inclination angle β and the crossing angle γ satisfying the following conditions: 0° < γ (15° 3° < β < 20° 5° < γ + β < 300 All characteristics include the process of softening the outer diameter of the material and stretching and rolling it.

Next, the method of the present invention will be specifically explained based on the drawings showing its implementation state.

Fig. 7 is a front view showing the rolling state from the entrance side of the rolled material 3o when the method of the present invention is carried out at 30 mm, Fig. 8 is a sectional view taken along the line -■ in Fig. 7, and Fig. 9 is a side view showing the inclination angle β. 3 rolls 31, 32.33Fi
, gorge parts 31a, 32a at the exit end of the rolled material 3o,
33a and f, the entrance side of the rolling machine 30 with the gorge section as a boundary gradually reduces in diameter completely n toward the shaft end, and the exit side widens f to form a truncated conical entrance surface 311), 32b, 33
b and outlet surfaces 31c, 32c, and 33c. Such cone-shaped rolls 31, 32, 33 have their entrance surfaces 31t+, 32b, 33b located upstream in the moving direction of the rolled material 30, and the axis Y-
The intersection point 0 between Y and the plane including the gorge portions 31a, 32a, and 33af (hereinafter referred to as the roll setting center).

1 to 6) on the same plane perpendicular to the pass line x-orthogonal to the 3° pass line
- They are arranged at approximately equal intervals around the X circumference. The axis line Y-Y of each roll 31, 32, 33 is set at the roll setting center opening, and the pass line x-x of the rolled material 30 is
In relation to this, the machine shown in FIG.
As shown in FIGS. 7 and 9, the front shaft end is inclined toward the same side in the circumferential direction of the material to be rolled 30 by an inclination angle β. Roll 31°32.3
3Fi is connected to a drive source (not shown) and rotated in the same direction as shown by arrows in FIG. 7. The hot rolled material 30 caught between these rolls is While being rotationally driven by the shaft center line, it is moved in the longitudinal direction of the shaft, that is, the outer diameter is narrowed while being screwed, and subjected to high pressure.

The cross-sectional shape of the hot-rolled material 30 is preferably circular, but may be a hexagonal or more polygonal shape. Since this roll rolls the material while rotating it, a roll with few corners is undesirable because it will cause a large impact on the rolling mill, and a square cross section is unsuitable.

Now, as mentioned above, in the method of the present invention, γ and β.

The conditions described above are imposed on γ+β. Upper limit of γ 1
The reason why the angle is set at 5° is that if the angle is greater than n, interference will occur between the roll end face and the portion of the roll chock closest to the pass line on the downstream side in the moving direction of the rolled material. Also, the lower limit fiIt is set to 0° because it is less than or equal to n, and γ=0
Or, if it is negative, it becomes impossible to completely eliminate shear deformation in the circumferential direction near the center of the rolled material and ensure dimensional accuracy in the longitudinal direction.

The reason why the upper limit value of β is set to 20° is the same as the reason for specifying the upper limit value of γ. The lower limit t is set at 73° because below that value, it is impossible to reduce the shear deformation in the circumferential direction near the center of the rolled material, making it impossible to obtain a sufficient porosity compression effect in the continuously cast rolled material. That's why.

The reason for setting the upper limit of T+β to 1i1jt30° is that if it exceeds this value, not only will the interference between the roll chock and the roll as described above become significant, but it will also be difficult to keep the bearing that supports the roll in the roll chock, which makes it difficult to maintain the roll support structure. This is because it will not be possible to maintain the The reason for setting the lower limit of γ and β to 5° is that below n, the rolling efficiency (speed I
K) cannot be ensured, and it becomes difficult to compress the porosity of the continuously cast rolled material.The conditions for γ and β are described above, and the following is compared with the values of γ and β of the conventional technology. A significant difference is that the value of γ is positive, which is effective in improving the porosity compressibility and suppressing the removal of the circumferential shear stress field.

The reason why the roll is supported at both ends is to strengthen the mill rigidity and prevent the occurrence of spiral marks. In order to clarify the effects of the method of the present invention, various implementation results will be explained. Both rolled materials are 545C carbon steel, and 12
Example 1 A base material having a circumferential shear strain diameter of 101 N and a length of 300 mm was heated to 00° C. and rolled. As shown in FIG. 10, five bottles 40 ( 2,5 mmφ) are embedded so as to be located on the same radius, and the flow 1rL (representing metal flow) of the bottle 40 after rolling as shown in FIG. The inclination angle β is the zero rolling condition for investigating the shear strain of
= 7°, and the intersection angle γ is set in three ways: 9°, which is within the scope of the present invention, and 0°, -9°, which is outside the scope of the present invention.
Area reduction for each intersection angle: 60%, 70%, 7
It was changed in four ways: 5% and 80%. The results are shown in FIG. 12 as a diagram connecting the bottle flow fL with a solid line. This result shows that when the area reduction is small, there is no big difference in the influence of the cross angle γ, but as the area reduction becomes larger, there is a difference in the shear strain in the circumferential direction, and it is the smallest when γ = 9°. it is obvious. When γ = 9°, no shear strain in the circumferential direction appears at the center of the cross section of the rolled material (metal flow exhibits a straight line), but when γ = -9°, no shear strain appears at the center of the cross section of the rolled material. Clear circumferential shear deformation is present in the entire cross-sectional circle including .

Note that when γ=0°, the state is intermediate between the two. By setting r>0° and increasing the value of γ, it is possible to prevent shear strain at the center of the cross section of the rolled material. The absence of shear strain in the circumferential direction means that there is no shear stress field in the circumferential direction, and therefore, in the case according to the present invention, cracks from the center porosity do not occur,
So-called Mannesmann destruction does not occur.

Example 2 Crimping performance of center porosity Diameter 70 mm,
2 MMφ and 4MMφ at the center of the matrix of length 30ONIR.

The degree of crimping during rolling was investigated by changing the inclination angle β in 6 ways between 3° and 13° using a material with a 6 mm diameter hole (simulating a center hole) drilled artificially. . The crossing angle γ is γ-9, which is within the scope of the present invention as in Example 1.
° and γ=0°, which is outside the scope of the present invention.

-9°. The area reduction is 53
% (70 mm φ - 33 mm φ). Figure 13(a),
(b).

(C) shows the results.

The following points are clear from this result. That is, when γ = 9°, an artificial hole up to 4 NM- is crimped at β = 13°, but when γ = -9°, even if β = 13°, the minimum 2 mm φ
Even the artificial hole is not crimped. In the case of γ-00, it is between the two, and an artificial hole of 2φ is crimped at β=13°.
Ru. In addition, regardless of the intersection angle γ, the inclination angle β affects the diameter reduction function of the artificial hole, and the larger β is, the greater the diameter reduction effect.

From this, it can be said that the crimp performance of the center porosity becomes higher as γ>0°, higher intersection angles and higher inclination angles are set.

Example 3 Crimping performance of center porosity Next, the crimp performance of actual center porosity was investigated using a base material obtained by continuous rotting.

The rolled steel is a round steel machined to a diameter of 70 mm and a length of 300 mm using the center part of a 380 mm φ large cross-section continuously cast slab, and the total area reduction is 78% ('7 <) φ
φ 朋→33+u). The rolling conditions are inclination angle β = 4°
, 8°, 12°, intersection angle γ = 9°, 0', -9
There were 3 ways of ゜, 9 ways in total. Then, the rolling mill was stopped during rolling, a stopper material was made, and the rolling condition of the porosity was investigated by cutting the material in half. The photograph in FIG. 14 shows this condition. The following points became clear from these results.

I) When the intersection angle is γ - -9°, there is a phenomenon of gradual Mannesmann fracture, in which the porosity of the base material becomes the starting point and the defect expands due to shear stress in the circumferential direction.

This tendency is improved as the inclination angle β becomes larger, but it is difficult to obtain sound internal properties.

11) When the crossing angle γ=9°, the porosity is completely crimped even if the inclination angle β is low.

II+) When the crossing angle γ=0°, a state is intermediate between the two, and when the inclination angle is large, the porosity crimping condition is good.

From these results, when a continuous cast slab is used as a material to be rolled, a high intersecting angle of γ>0° and a high inclination angle are desirable in order to compress the porosity.

Embodiment 4 Surface threading The present invention is inferior to the two known techniques described above in surface threading. As shown in FIGS. 15(a)' and 15(b), a s41 with a depth of I MM and a width of I MN is formed in the axial direction on the surface of a base material with a diameter of 7 Off and a length of 300 mm, and the area is reduced by 78%. (7ortrrpr'f
i-+33gg+'). FIG. 17 shows the results of measuring the n-angle ψ (the angle between the groove trace and a straight line on the surface parallel to the axis line as shown in FIG. 16) of the #441 screw after rolling in this case. The rolling conditions are that the inclination angle β is 3°~
There are 6 ways of 13 degrees and 3 ways of intersection angle γ of 9 degrees, 0 degrees, and -9 degrees, a total of 18 ways. The following points are clear from this result.

1) When γ=-9°, the surface twist is small.

11) When γ=9°, the surface threading is large. however,
This drawback can be compensated for by increasing the inclination angle β.

111) When γ=0°, it is between the two.

In other words, when implementing the present invention, it is desirable to set the inclination angle β to be high in order to reduce the surface thread -fli.

Example 5 Dimensional Accuracy in Axial Direction A base material with a diameter of IONM and a length of 300 gm was rolled at an area reduction of 67% (70 mm φ → 40111 W φ), and dimensional changes in the longitudinal direction were investigated. The rolling condition is that the inclination angle β is 4.
There are three crossing angles γ: 9°, 0°, and -9°. 1st
Figures 8 (a), (b), and (0) show the results. Accordingly, when γ=9°, ±0.10%, γ=
-9° is ±0. 5, ±0 between the two at γ=0°
．． It is clear that γ>0° is effective in ensuring the dimension fllf degree.

Example 6 Rolling speed Diameter: 10114 Total area reduction of 78% (7
The rolling speed in the case of rolling to 0mmφ - 33mmφ) was investigated. Rolling conditions are roll rotation speed: 1ooR, p, M
, .

The diameter of the gorge portion of the roll was 250 mm, 6 types of inclination angle β from 3° to 13°, and 3 types of crossing angle γ of 9°, 0°, and -9°, for a total of 18 rolls. FIG. 19 shows the results, showing that the rolling speed is the highest when γ=9°, and that the rolling speed tends to increase as the inclination angle β increases. Therefore, in order to improve rolling efficiency, γ〉0°
, preferably a high crossing angle and a high inclination angle.

As described above, in the case of the method of the present invention, it is possible to perform inclined rolling without causing the so-called Mannesmann fracture, which is caused by porosity, and therefore it is possible to realize a rolling line with a revolutionary high workability. This makes it possible to dramatically increase the production efficiency of circular cross-section metal materials.Also, even when a continuous casting material with center porosity is used as the base material, the porosity can be crimped and no cracks will occur. It is also possible to realize a rolling line that is connected to a continuous casting machine, and in this aspect as well, production efficiency can be improved and thermoeconomic benefits can be enjoyed.

Furthermore, in the case of the present invention, since the shear strain in the circumferential direction is small, there is no possibility that the internal side fL will occur starting from inclusions, so high efficiency manufacturing is possible even when using difficult-to-process materials as the raw material. etc. The present invention has excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a schematic front view of the structure fc of a conventional inclined roll rolling mill, Fig. 2 is a sectional view taken along the row line in Fig. 1, Fig. 3 is a side view showing its inclination angle β, Fig. 4 is a front view schematically showing the conventional inclined rolling method for round steel materials, and FIG.
The cross-sectional view taken along the v-line, Figure 6, shows the inclination angle β? 7 is a front view schematically showing the structure of an inclined rolling mill used for carrying out the method of the present invention, and FIG. 8 is a vlIl-vl diagram of FIG.
9 is a side view showing the inclination angle β; FIG. 10 is a sectional view of the sample for shear strain measurement;
Figure 1 is a cross-sectional view showing an example of the shape after rolling, Figure 12 is a diagram showing the measurement results of shear strain, and Figures 13 (a) and (b).
). (c) Graph showing the inner diameter of H artificial hole after rolling, No. 14
The figure is a photograph of the longitudinal cross-sectional structure of the rolled material after rolling, No. 15.
Figures (a) l (b) Front and side views showing the sample for measuring Vi surface torsion, Figure 16 is a side view showing the groove form after rolling, and Figure 17 is a graph showing the surface torsion measurement results. , FIG. 18(a), (b), (cI tr
i-axis long axis length method dimensional accuracy determination result chart, Figure 19 is a graph showing the rolling speed measurement results0 31.32.33...Rolls 31a, 32a, 33
a...-gorge portion 31b, 32b, 33b...inlet surface 31c, 32c, 53c...exit surface 30...
Patent applicant for rolled material Noboru Kono, Patent attorney representing Sumitomo Metal Industries Co., Ltd. Figure 1 Figure 2 V Retain 4 Figure 3 Figure 5 Figure 1 of artificial hole (mm) @ 13 Figure (a) Figure 13 (b) Figure 13 fcl (+11 tbl
15 Figure not shown Calculation 16 Figure A11 Sentry 4 To'4 (p) Figure 1q ←-----Cold scolding-1---- I111 娑1μm (p) Hole lq figure

Claims (1)

[Claims] 1. Three or four rolls are arranged facing around the pass line, and their axial center lines are inclined so that the shaft ends on the same side face the same side in the circumferential direction. A cross-type inclined rolling mill in which the shaft ends of n1 and the same side can be tilted (crossed) so as to approach or move away from the pass line side, and the rolls are supported at both ends of each. The outer diameter of the rod-shaped material is reduced with the inclination angle β and crossing angle γ of the rolls satisfying the following conditions: 0°〈γ〈15°3°〈β〈20°5°〈γ+β〈30° A method for producing a circular cross-section metal material, the method comprising the steps of elongation and rolling.