JPS591123B2 - Double row loop rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to loop control in continuous rolling of rods and wire rods, and more particularly to a rolling technique that simultaneously and appropriately controls double-row loops in intermediate and finishing rows of rolling mills.

Conventionally, in rolling mill rows for rods and wire rods, the rolled material is maintained in a free tension state during rolling, resulting in good dimensional accuracy and
Tension control rolling and loop control rolling are used to obtain quality and yield.

However, in a double-row rolling system in which two or more rolled materials are passed through a rolling mill row at the same time, rolling conditions differ depending on each rolling row due to bending deformation of the rolls or variations in material dimensions, so rolling conditions are different between intermediate and finishing stages. In the section in the sequence where double-row loops are used, the loops in each row will be irregular.

Therefore, in the past, multiple loop control has sometimes adopted a method of accepting that the loops are not aligned and providing sufficient loop capacity to avoid this problem.

However, in this method, the direction of movement of the material to be rolled is
Since it uses a method of changing 80 degrees several times, a large space is required to create the loops, and if the loops are too large, surface flaws are likely to occur due to scratches, bulges, etc. It was hard to say that it was a good method.

The present invention performs appropriate loop control in double-row rolling, ensures stable rolling with the minimum amount of loops and space, obtains products of good quality, and eliminates waste in the layout of the bar/wire rolling mill. The aim is to provide an extremely small number of highly efficient rolling mill rows for rods and wire rods.

The present invention will be explained in detail below.

In double-row rolling, in order to simultaneously create a plurality of loops between the i stand and the (i +1) stand in good alignment, it is necessary to take the following measures.

(i-1) The rigidity of the rolling mill of the stand, that is, the longitudinal rigidity corresponding to the mill spring and the lateral rigidity representing the bending rigidity of the rolls, are made larger than those of other stands.

■ Increase the lateral rigidity of the i-stand compared to other stands.

(2) Control the tension between the (i-2) stand and the (i-1) stand to preferably no tension or minimum tension.

(i-1) Control the tension between the stand and the i-stand to preferably no tension or minimum tension.

Of the above four measures, the effect is especially great when used in combination with ■~■, but the effect is not sufficient even if some of the measures are used in combination or if any one of the measures is implemented. be.

mentioned above.

The effects brought about by the constituent elements for solving the technical problems of this invention will be described below.

In ■, by increasing the rigidity, (i-1) absorbs the variation in the dimensions of the material that goes into the stand, and (i-1)
Align the dimensions of the materials coming out of the stand.

In addition, by increasing the rigidity of this stand, it is possible to suppress the change in tension between stands (i-1) and i when the number of rolls rolled simultaneously changes, so the unsteady parts of the top and bottom become loops. It is possible to prevent the impact of

In (2), the lateral rigidity of the i-stand is increased to suppress bending and deformation of the rolls, and the roll gap is made equal in all rolling rows.

As a result, the material speeds leaving the i-stand can be equalized.

In case of ■, if a fairly large tension is applied between stands (i-1) and (i-2), non-uniform conditions due to the rolling row, such as variations in the dimensions of the material entering stand (i-2), will be removed from the stand. This appears as uneven tension.

If this is too large, it cannot be absorbed completely by the measures (2) and (2), so the measure (2) is required to minimize this negative effect.

In (i-1), in the same manner as described above, the non-uniformity of the rolling row of the material entering the stand is prevented from appearing as a change in the tension between the stands.

As an example, a typical rolling line shown in FIG. 1 will be explained.

In Figure 1, 1 is an H-type rolling mill with (i-2) stands, 2 is an H-type rolling mill with (i-1) stands, 3 is an H-type rolling mill with i-stands, and 4 is an (i +1) stand. 5 is an H-type rolling mill with (i +2) stands, 6 is (
i+3) H-type rolling mill of stand, 7 is the material to be rolled.

This figure 1 shows four double-row rolling machines up to i-stand 3, (i
This is an example in which rolling is performed in a state where the loop capacity is relatively small, where two double-row rolling is performed up to +1) stand 4 and (i +2) stand 5, and single-row rolling is performed from (i+3) stand 6 onwards.

In this case, between i stand 3 and (i + 1) stand 4, and between (i + 1) stand 4 and (i + 2) stand 5
Two rolled materials each form a double-row loop between the two.

In this case, problems such as curling occur in the two rolled materials due to slight changes in rolling conditions.

Therefore, in the past, the operator could control the loop amount of one of the two rolled materials to be slightly smaller, and then reduce the loop amount of the other rolled material accordingly, while the operator observed the situation. It was normal to go there.

However, even in this case, if there are large fluctuations in rolling conditions,
If an attempt is made to prevent this, the amount of the other loop may be zero or may be rolled under tension, which often results in a significant loss of quality.

As described above, there were problems in terms of both quality and labor saving, but the inventors solved these problems using the following method.

That is, in order to equalize the double loops between the i-stand and the (i+1) stand, a rolling mill was used for the (i-1) stand whose rigidity was two to three times greater than that of the other stands.

■ A down loop was created between the (i-2) stand and (i-1) stand.

Although these measures were simultaneously adopted, it was found that even when only ■ was used, the effect was significant.

In the present invention, as a specific means to increase the rigidity of the rolling mill, pre-stressing is applied to the housing of the rolling mill, and a known compact mill is used, which is lightweight and strong as a whole and has high rigidity. There are various ways to increase the rigidity. For example, to increase the longitudinal rigidity: (1) Make the housing of the rolling mill more rigid.

■ Increase the apparent vertical stiffness by adjusting the roll gap using oil pressure, water pressure, air pressure, etc.

methods such as In addition, when increasing the lateral stiffness, ■ Increase the roll diameter.

■ Shorten the roll barrel length.

As shown in FIG. 2, a support roll 9 is provided on the back of the grooved roll 8 through which the material 7 to be rolled is passed.

(2) As shown in FIG. 3, a bending force F or bending moment M is applied to reduce the bending deformation of the roll 10.

■ As shown in Figure 4, attach the round 12 so as to counteract the bending of the roll 11.

There are several methods, and any method can be expected to be effective.

In the end, it goes without saying that the most advantageous and effective method is preferable in terms of equipment costs, operation, etc.

The effects of the present invention are as follows.

) According to the present invention, it is possible to simultaneously control multiple loops in an optimal state while keeping the loop capacity small.

(2) Since the loop is stable, dimensional accuracy and quality can be significantly improved, and labor can be saved.

The control of two double-row loops has been explained above based on an example, but the invention of Ikemi basically consists of three
It can also be applied to simultaneous double-row loop control of more than one mill. If a method is adopted in which each rolling mill performs four-through rolling and the four loops are made into a down-loop, the line can be significantly streamlined and compacted.

More specific examples will be described below.

Using a rolling mill row consisting of a rough rolling stand row, a first intermediate rolling stand row, a second intermediate rolling stand row, and a finishing rolling stand row shown in FIG. It was rolled into a wire rod.

The characteristics of the rolling line that carried out this rolling are as follows.

(1) The vertical rigidity of the #18 stand (corresponding to the i-1st stand) is 60 ton/rran, which is twice the rigidity of the conventional stand (30 ton/#), and the lateral rigidity is 60 ton/rran, which is twice the rigidity of the conventional stand (30 ton/#). In order to approximately double the roll diameter, a rolling mill was used in which the roll diameter was increased by approximately 20%.

(2) In order to make the stand #19 (corresponding to the i-th stand) have a lateral rigidity that is approximately twice that of a conventional stand, the roll diameter is increased by approximately 20%.

(3) #16 stand (i-2nd stand) and 818
In order to make the tension in the rolled material between (i-1st stand) zero, stand #17 (dotted line in FIG. 5) was removed and a down looper was installed.

(4) #18 (i-1st) stand ~ #19
(i-th) The space between the stands was slightly tension-rolled to prevent bulges from occurring when the bottom ends or the head ends are bitten.

The results of this actual rolling are shown in FIGS. 6 and 7.

As is clear from FIGS. 6 and 7, the dimensional accuracy near the bottom of the wire before the rolling line modification (when rolling was performed using the conventional technology) was greatly improved after the modification (rolling according to the present invention). There is.

Figure 7 shows the fluctuation of the double loop. In the line before modification, the loop fluctuations of the third and fourth rows were X1 = 1.7 m and X2 = 0.4 m, respectively, and the difference was l =1
．． The line was as long as 3m, but after the modification, the above values are X1 = 0.95mt and X2 - 0.65m, and the difference is l = 0.30m, and the amount of irregularity in the double loop is l.
has been greatly improved.

Since the present invention is configured and operated as described above, (1) it is possible to simultaneously control double-row loops in an optimal state while keeping the loop capacity small;

■ Since the loop is stable, dimensional accuracy and quality can be improved and labor can be saved.

It has the following effects.

[Brief explanation of drawings]

FIG. 1 is a schematic view showing a typical rolling line, and FIGS. 2, 3, and 4 are explanatory views showing specific means for increasing the lateral rigidity of the rolling mill. FIG. 5 is a diagram showing a specific example of a rolling mill row for implementing the present invention, and FIGS. 6 and 7 are charts showing the results of implementing FIG. 5.

Claims (1)

[Claims] 1. When rolling bars or wire rods by passing two or more passes between pairs of rolls in a row of rolling mills, the rolling mill (stand) in the previous stage of the loop of the rods or wire rods scheduled between the rolling mill stand When the i-th stand is defined as the (i-1)-th stand, the vertical stiffness and lateral stiffness of the (i-1)-th stand are made larger than the other stands except the i-th stand, and the rod or wire rod is rolled and discharged from the (i-1)-th stand. The amount of stretching of the rod or wire rod to be rolled is made substantially equal between the rows, and the lateral rigidity of the i-th stand is increased, and the amount of stretching of the rod or wire rod rolled and discharged from the i-th stand is made uniform between the rows. A method for rolling a double-row loop, characterized in that a bar or wire is rolled by performing one or both of the following.