JP2886759B2 - Rolling method and rolling device for round bars and wires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for rolling round bars and wires. More specifically, the present invention relates to a rolling technique for reducing the wire diameter by performing hot or cold roll rolling on a steel material having a circular cross section and the like to obtain a round bar or a wire having a desired size.

[0002]

2. Description of the Related Art In recent years, size-free rolling, which is a rolling method capable of coping with a fine size pitch with a small number of rolls, has been proposed. This size-free rolling uses a roll with the same hole shape and changes the rolling position of the roll steplessly to change the diameter of the round bar / wire rod steplessly and finishes it. Japanese Patent Application Hei 4-56189
And Japanese Patent Application No. Hei 4-311369.

In these rolling apparatuses, the former comprises a finishing roll mill group consisting of a plurality of stands of four roll mills, and the latter comprises a finishing roll mill group consisting of a plurality of stands combining two rolls and four rolls. Rolling is performed sequentially from different directions.

[0004]

However, in a plurality of stands as described above, speed matching between the stands is important. If the speeds do not match, tension or compression acts on the material, resulting in unexpected dimensions. In this case, there is a problem that the dimensional accuracy is reduced. on the other hand,
To control the speed of each stand very accurately for speed matching, sophisticated control technology is required and equipment costs are increased.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rolling method and a rolling apparatus capable of reducing the equipment cost while increasing the sectional accuracy of a material.

[0006]

According to a first aspect of the present invention, there is provided a rolling method using a rolling machine in which a four-roll mill is arranged on a final-stage stand of a finishing roll mill group including a plurality of roll mills. It is characterized in that a compressive force is applied to the inlet side of the material to be rolled and the outlet side is operated without tension.

Furthermore, the rolling apparatus of the invention of claim 2, wherein
Item 4. A rolling apparatus used in the method for rolling round bars and wires according to Item 1 , wherein the final-stage four-roll mill is constituted by an idler roll or a helper drive roll.

[0008]

First, the relationship between the area reduction rate and the width expansion rate at the time of rolling will be described. FIG. 7 shows the area reduction rate and the width expansion rate at the time of 4-roll mill rolling using the input and output side tensions as parameters. . The width expansion ratio is the diameter do of the rolled material before rolling shown in FIG.
Is expressed in relation to the diameter d of the rolled material after rolling of the surface that is not rolled by the rolls, that is, the unconstrained surface.
−do) × do × 100 (%). If the width expansion ratio is positive, the width is expanded, and if the width expansion ratio is negative, the width is narrowed.

As shown in the graph of FIG. 7, as a general tendency, in the case of a four-roll mill, the width expansion rate decreases as the area reduction rate increases, but the relationship between the entrance and exit tensions is The distinction is as follows. In the following, σf indicates the output side tension, σb indicates the input side tension, and σy indicates the yield stress of the rolled material. The line X is always negative when both the entrance and exit sides have no tension. That is, the width is narrowing. σf / σy = 0.2, σb / σy
When = 0, that is, when the outlet side is tension and the inlet side is tensionless, there is almost no difference in the width expansion ratio from the case where the inlet / outlet side is tensionless as indicated by the line Y. When .sigma.f / .sigma.y = 0 and .sigma.b / .sigma.y = -0.2, that is, when there is no tension on the outgoing side and a compressive force acts on the inward side, the width expansion ratio approaches 0 as indicated by the line Z. From these results, it is understood that the influence of the width expansion rate can be suppressed by applying a compressive force to the rolled material on the 4-roll mill entry side of the final pass.

[0010] When the rolled material is finished, if the diameter of the non-constrained surface changes in the final pass, the subsequent correction is not effective. Therefore, in the present invention, since the four-roll mill in the final pass is constituted by idler rolls or helper drive rolls (rolls having only the power necessary to rotate the own roll), the rolling power in the final pass is a rolling power. It is supplied from the previous stand through the material. In other words, since a compressive force acts on the material to transmit the power, the influence of the width expansion by the four-roll mill in the final pass can be suppressed, and the cross-sectional accuracy of the rolled material can be improved.

[0011]

Next, a rolling method and a rolling apparatus according to the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a roll layout diagram of a rolling device according to a first embodiment of the present invention, and FIGS. 2 to 4 are explanatory diagrams of passes of a finishing roll mill group in the rolling device of FIG.

1 is a two-roll mill stand S
It consists of a 2-roll mill group in which 1 to Sn are alternately arranged in n stages at 90 ° phase, and a 4-roll stand Sn + 1 which is inclined 45 ° with respect to the immediately preceding stand Sn as the final stage stand. The two roll mills Sn-2, Sn-1, Sn from the last stage to the third stage before the last stage and the last four-roll mill Sn + 1 constitute a finishing roll mill group.

The finishing roll mill group passes in the order of a horizontal arrangement H with a pair of rolls up and down, a vertical arrangement V with a pair of rolls left and right, a horizontal arrangement H, and four rolls as shown in FIG. Vertical arrangement V, horizontal arrangement H, vertical arrangement V, 4
Any of the order of rolls, the staggered arrangement shown in FIG. 4 (eg, diagonally right down, diagonally right up, diagonally right down), or the order of four rolls may be employed.

Each roll of the final four-roll mill is constituted by a non-driving idler roll or a helper drive having a driving force necessary for rotating its own roll. The supply of the material 1 to the final stage 4 roll Sn + 1 is performed by the stands Sn and Sn-1 before the immediately preceding stage.
Etc. are performed by the force which sends out the material 1. Therefore, a compressive force acts on the material 1 on the entry side of the four-roll mill Sn + 1, and the material 1 on the exit side is in a tensionless state where no tension acts. For this reason, according to the present embodiment, the width expansion ratio approaches 0, and the sectional accuracy is improved.

(Second Embodiment) FIG. 5 is a roll layout diagram of a rolling mill according to a second embodiment of the present invention, and FIG. 6 is an explanatory view of paths of a finishing roll mill group in the rolling mill of FIG.

The finishing roll mill group of the second embodiment comprises a four-roll mill Sn + 1 of the last stand and a four-roll mill Sn of the immediately preceding stand. The four-roll mill Sn immediately before the final stage is a stand corresponding to the two two-roll mills Sn-1 and Sn of the first embodiment, and two rolls before the four-roll mill Sn in the same manner as in the first embodiment. A plurality of stands are arranged.

Also in this embodiment, the final stage stand 4
Each roll of the roll mill Sn + 1 is constituted by a non-driving idler roll or a helper drive roll having a driving force necessary for rotating its own roll. The supply of the material 1 to the last-stage four-roll mill Sn + 1 is performed by the force of sending out the material 1 by the stand Sn or the like before the immediately preceding stage. Therefore, 4 roll mill Sn + 1
The compressive force acts on the material 1 on the entry side of, and the material on the exit side is in a tensionless state where no tension acts. Therefore, also in the present embodiment, the spread rate approaches 0, and the cross-sectional accuracy is improved.

In each of the above embodiments, the final stage four-roll mill is merely of an idler or helper drive structure, so that the equipment cost is not significantly increased.

[0019]

According to the present invention, there is an advantage that the cross-section accuracy of the round bar / wire is increased and the equipment cost is reduced.

[Brief description of the drawings]

FIG. 1 is a roll layout diagram of a rolling device according to a first embodiment of the present invention.

FIG. 2 is an explanatory sectional view of a pass of a group of finishing roll mills in the rolling apparatus of FIG. 1;

FIG. 3 is an explanatory cross-sectional view of a pass of a group of finishing roll mills in the rolling device of FIG. 1;

FIG. 4 is an explanatory sectional view of a pass of a group of finishing roll mills in the rolling device of FIG. 1;

FIG. 5 is a diagram showing a rolling apparatus and roll arrangement according to a second embodiment of the present invention.

FIG. 6 is an explanatory cross-sectional view of a pass of a group of finishing roll mills in the rolling device of FIG. 1;

FIG. 7 is a diagram showing a relationship between tension and a reduction in area between a plurality of mills.

FIG. 8 is an explanatory view of a cross section before and after rolling.

[Explanation of symbols]

S1, S2, S3, Sn-1, Sn 2 roll mill stand Sn + 1 Final stage 4 roll mill stand

Claims (2)

(57) [Claims] 1. A compressing force is applied to an input side of a material to be rolled by said four-roll mill, using a rolling device in which a four-roll mill is arranged on a final stage stand of a finishing roll mill group composed of a plurality of roll mills. A method for rolling round bars and wires, wherein the method is operated without tension. 2. A method for rolling a round bar or wire according to claim 1.
A rolling device for use , wherein the final-stage four-roll mill is constituted by an idler roll or a helper drive roll.