JPH0124561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for rolling steel bars.

A conventional row of continuous rolling mills for round bars and square bars is shown in Fig. 1a, in which horizontal rolling mills 2, 3, 4, and 5 are equipped with grooved rolls corresponding to the cross-sectional shape of the product, with bloom or billet as the material 1. , 6 and 7, and a twister device 8 which turns the material 90° between the rolling mills.

FIG. 1b shows the shape of the roll hole and the cross-sectional shape of the material to be rolled, which are compatible with the above-mentioned horizontal rolling mill.The upper stage of the process flow divided into two by arrows is for square bars, and the lower stage is for round bars.

In the figure, 2a, 4a, 6a are diamond hole types, 3
a, 5a, 7a are square hole type, and 4b, 5
b is an oval hole type, and 6b and 7b are round hole types.

A roll stand for cross-sectional reduction in groove rolling by a continuous rolling mill row in which the cross-sectional area of the material 1 is reduced by such groove rolls and shaping rolling is performed by rolls having grooves according to the product shape. The number of is determined by the cross-sectional dimensions of the material 1 and the dimensions of the final product. There are six rolling mill stands each for rough, intermediate, and finishing mill stands, and the rolls of each rolling mill stand are engraved with grooves as shown in FIG. 1b according to the process.

In such groove rolling, the following problems occurred.

(1) In the case of groove rolling, if the grooves of two combinations deviate from each other, or if the center of the guide device for guiding the rolled material to the groove deviates from the center of the groove, Fin-like protrusions are formed in the vertical direction on the surface of the material coming out of the roll, and folding defects occur during the next shrinking process.

(2) In order to prevent the disadvantage of (1), strict precision is required when setting the rolling rolls and guides, which increases the rolling stop time.

(3) Since the size and shape accuracy of the hole directly have a large effect on product quality, roll machining requires advanced technology and therefore requires the use of an expensive roll lathe.

(4) In rolls with grooves, uneven wear occurs on the roll grooves due to frictional wear caused by speed differences at various positions within the grooves, resulting in frequent reshaping, resulting in lower roll costs. It also becomes more expensive.

(5) When changing the rolling size (for example, outer diameter 16
2 mm to round bars with an outer diameter of 40 mm), it is necessary to change several rolls and hole shapes, and the rolling stoppage time becomes long, and at least there is no hope for roll chance-free production.

(6) In groove rolling, if the gap between a pair of rolls is made closer than a predetermined value, protrusions will appear on the free surface of the material that comes out of the rolls after rolling, which will cause folding defects in the next reduction step.

In order to solve the problems in the conventional groove roll rolling technology using continuous rolling mill rows, we developed a method for rolling long steel using a pair of parallel grooveless rolls, that is, plain rolls (hereinafter referred to as flat rolls) with a uniform circular cross section. This invention is based on the following facts.

In other words, the conventional groove roll rolling technology
In the process of reduction rolling into round steel, the product is passed through a continuous rolling mill multiple times in order to manufacture it into a predetermined shape, but only a few shaping passes are sufficient.
The majority of the remaining passes are for stretching and cross-section reduction, so there is no need for groove rolling in this process.

In order to solve the above-mentioned problems caused by groove rolling, this invention adopts a flat roll pass for the reduction rolling passes of square steel and round steel except for the number of shaping passes. This is based on the knowledge that stable surface reduction processing can only be achieved by limiting the aspect ratio.

Therefore, the present invention performs shaping rolling in the final few stands using conventional slotted rolls,
The rolling upstream is, for example, flat roll rolling using a row of horizontal continuous rolling mills.

Next, one embodiment of the present invention will be described in detail.

Figure 2a shows a row of continuous finishing rolling mills for square bars or round bars, rolling mill stands F ₁ to _{F o-2} are horizontal rolling mills with flat rolls, and rolling mill stand F _o-1 , F _o is a conventional horizontal rolling mill with grooved rolls.

A twister device 8 is appropriately provided between each rolling mill stand F ₁ to _{F o-2} according to the rolling schedule.

The twister device 8 includes a twist scraper 9,
Consisting of a twister 10 and a cylindrical guide roller 11, the material is twisted to a certain extent by a twist scraper 9, and then rotated by the twister 10 until it reaches 90 degrees.The cylindrical guide roller twists the material rotated by 90 degrees. This will lead you to the next flat roll pair with the correct posture.

FIG. 2b shows the changes in the cross-sectional shape of the rolled material after each pass of rolling in each rolling stand.

3a and 3b show the situation in which the material is turned by the twister device 8. FIG.

The side surface A of the rolled material 1 is first twisted in the direction of the arrow by the twist scraper 9, and then further twisted by the twister roll 12 of the twister 10.
After turning 90 degrees, the cylindrical guide roller 11
While being held vertically by the rollers, it is inserted into the next pair of flat rolls.

In this invention, when the material rolled by the pair of flat rolls is rotated by 90 degrees by the twister device 8, the width B of the material to be rolled after each pass rolling is
The ratio of height H and height H is limited as follows.

H/B3.0 On the other hand, when H/B > 3.0, as shown in Fig. 4a, in order to obtain the necessary twist angle θ with the twister roll 12, the strain in the width direction of the rolled material due to twisting is necessary. Through many experiments, they discovered that because ΔB becomes too large, the rolled material collapses and twists during the next flat roll rolling.

The twist angle θ is indicated by the subscript 1, the twist scraper 9 and the twister roll 12, respectively.
Normally, θ ₁ = 15~20°, θ ₂ = 40
~45°.

It has been found from experimental results that the optimal setting value l for the distance between the cylindrical guide roller 11 and the material is the width of the rolled material plus 2 to 10 mm, as shown in FIG.
If it is wider than this, the material may fall over.
Also, if it is narrowed, there is a risk that the material will get stuck in the guide.

Note that the twister device 8 can be a conventional one, and the cylindrical guide roller 11 has conventionally been mainly a grooved roller, but for this invention, a cylindrical one with a smooth surface is used. .

Note that the guide rollers 13, 13 used at the entrance of the pair of finishing rolls F _o-1 and F _o may be conventionally grooved rolls, an example of which is shown in the lower part of FIG. 3a.

An example of the twist scraper 9 is shown in FIGS. 5a, b, and c, where 14 is the scraper end, 15 is a rectangular inlet for rolling material, and 16 is a twisted rectangular outlet. 17 is a guide passage;
18 is a mounting seat, 19 is a suspension seat, and 20 is an adjustment gap.

Further, an example of the twister 10 is shown in FIG. 6. In the figure, 21 is a holding housing, 22 and 23 are bearing boxes for a pair of twister rollers 12, which are held movably forward and backward relative to the housing 21, and each bearing box 2
2 is a link 2 to each clevis 24 on the end face.
5 to a lever 27 pivotally mounted on the end of the protruding arm 26 of the housing 21, which lever 27 is connected to the adjusting stud 2 fixed to the housing 21.
8, the nuts 29 and 30 occupy an arbitrary fastening position, thereby making the roll gap of the twister roller 12 variable.

As described above, according to the present invention, in a continuous rolling mill in which the roll axes of a plurality of rolling stands made of flat rolls are arranged in parallel, there is a vertical or horizontal orientation between adjacent stands. By stably guiding twisting that does not cause fluctuations in the rolled cross-sectional shape of the rolled material during different rolling operations, it is possible to reduce the area of long steel without any disadvantages due to collapse or twisting, and to significantly reduce the roll consumption rate. reduction and a significant enhancement of rolling efficiency can be achieved.

[Brief explanation of drawings]

Fig. 1a is a layout diagram showing a conventional example of a row of continuous rolling mills for long steel, and Fig. 1b is a system diagram showing the roll hole shape and cross-sectional shape of the rolled material for square steel and round steel. Figure 2a is a layout diagram of a row of continuous rolling mills according to the present invention, Figure 2b is a system diagram showing each stage of deformation of a rolled material by flat rolls, and Figure 3a is a diagram showing the deformation of a rolled material between roll stands. Fig. 3b is a system diagram of each stage passing through the twisting guide.
is a plan view showing the arrangement of the guide rollers, Fig. 4 is a detailed view of the main part showing the effect of excessive twisting of the rolled material by the twister rollers, and Figs. 5 a, b, and c are side views and plan views of the twist scraper. FIG. 6 is a cross-sectional view of the main part of the twister.

[Claims]

1 The ratio of web thickness to web height is 1:5 to 1:
When an H-shaped rough-shaped steel slab in the range of 12 is subjected to etching rolling with an etching caliber to reduce the web internal method, the total etching possible amount s determined for each flange inclination angle inside the flange of the H-shaped rough-shaped steel billet is and the allowable buckling amount corresponding to the possible edging amount to determine the edging amount n per pass, and calculate {(s/n)
+1} times or less of edge rolling and then rolling in a shaping hole mold, or after shaping rolling, the above-mentioned edge rolling is performed again and then shaping rolling is carried out. In-web reduction rolling method.

Claims (1)

[Scope of Claims] 1. In the case where a continuous rolling mill train passes a rectangular cross-section material through multiple pairs of flat rolls to reduce its area alternately vertically and horizontally, a twist scraper, a twister, and a cylinder are placed between the pairs of flat rolls. After each pass of rolling passing through the flat rolls, the material to be rolled, whose aspect ratio has been reduced to 3.0 or less, is rotated by 90 degrees via a twister and bitten into the next pair of flat rolls. A method for rolling steel bars, characterized by rolling. 2. The method according to claim 1, wherein the material is bloom. 3. The method according to claim 1, wherein the material is billet.