DE2524224A1 - METHOD AND DEVICE FOR ROLLING BAR STEEL - Google Patents

Description

Applicant: Nippon Steel Corporation

6-3, Otemachi 2-chome, Chiyoda-ku Tokyo, Japan

Method and device for rolling steel bars

The invention relates to a method for rolling steel bars

from a square starting workpiece. I.

The invention also relates to a "" Valzenstrasse or a! Rolling mill to carry out this process.

Steel bars are rolled in an open line, in a staggered arrangement, or in a mixed arrangement of dual scaffolding or trio scaffolding. In doing so, the. ' Rolled into the desired finished cross-section in numerous passes with the appropriate gauges.

Stretch-reducing mills with three-roll stands for rolling tubes are known. The use of such three-roll stands for, rolling steel bars is also known.

When rolling with duo and trio stands, so-called incised calibres are used. When rolling with three-roll stands a pass is formed by the interaction of the rollers j and is called a composite pass.

Groove rows for rolling steel bars with duo stands i ! ~ f

j or trio frameworks in four stitches are indicated in Fig. 1, J where one starts with a square cross-section of the .workpiece L goes out. A series of calibres

Set calibers of three-roll stands is indicated in FIG.

In a series of passes for rolling steel bars in duo stands or trio stands according to FIG. 1, the optimum relative changes Cross-section reduction depending on the steel material, the dimensional accuracy of the workpieces and the respective Processing stage namely pre-rolling, intermediate rolling and finish rolling. The following table can be used as a rough estimate accept:

Table relative reduction in cross-section (%)

Special steel construction steel (stainless steel)

Reinforcement bars

Pre-rollers 20-25 j 20 - 25 Intermediate rollers 14-20 I 16 - 22

iFinishing rollers 8-14 ^{: 10-16}

24
20th
16

28 24

middle

18-22

18 - 24

20-26

The maximum reduction in cross-section is with regard to the occurrence of surface imperfections due to deformation and wear the caliber specified during the rolling operation and changes accordingly depending on the roll material, the shape of the groove and the weight of the workpieces. However, it is ensured on the basis of numerous experiences that to achieve higher quality Workpieces a smaller cross-section reduction must be applied.

According to "Iron and Steel Engineering", November 1972, is the relative reduction in cross-section of a composite pass a three-roll stand to a maximum of 40%, normal

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wisely to use less than 23%. The mean value is even j lower. The difficulties of the three-roll stand are that the deformation quality in the first stand of such a line cannot be very great if billets, small blocks, continuously cast billets or similar semi-finished products are used as the starting material, especially if they have a square cross-section. 3 shows the assignment of a workpiece II with a square cross-section to a composite caliber Ck formed from three rollers. The deformed areas M ^ and I / U of the workpiece M are not evenly distributed among the three rollers R ^ ,, ILji R * · As a result, there is the possibility that the V / piece M is deformed or twisted when it passes the 'rolling gap leaves. During the reduction, the workpiece M fills the caliber sections Ck-1, Ck-2, Ck-3 unevenly, so that deformations and twists also continue in the second stitch. To improve the output when rolling with three-roll stands, a circular or hexagonal starting cross-section must be formed with a duo stand or a trio stand, so that at least two or three roughing passes are necessary in a roughing mill. The first pass in the three-roll stand after the roughing passes have been carried out can hardly have a large reduction in consideration of the shape of the workpiece, the cross-section of the composite pass and the relationship of the cross-sectional shapes. As a result, additional roll stands are required for roughing passes, although the three-roll stand itself has a high aspect ratio. As a result, the rolling is not economical compared to the conventional method

According to "Iron and Steel Engineering", November 1972, the width when rolling in a three-roll stand is greater than it is was expected. From this it can be concluded that the three-roll stand itself is the reason for the low elongation.

The object of the invention is to provide a method for rolling steel bars with high output and high output

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medium reduction in a small number of stitches. In a further objective, the invention aims at a method with more precise Provide rib-free edge processing, so that a rolling without broadening is possible and so that high-quality steel bars with good surface properties are obtained.

This object is achieved according to the invention in that in a four-roll stand, the roll axes on the sides of one perpendicular to the rolling direction aligned rectangle are arranged, the output cross-section in each case simultaneously Square areas are reduced along the respective diagonals to form an approximately square cross-section, the sides of which connect roughly the centers of adjacent sides of the output cross-section, that this reduction to the receipt of the end cross-section is repeated several times and that the final shaping of the cross-section by reduction in a composite Caliber of the desired shape takes place within a four-roll stand.

The invention also proposes a rolling train for rolling steel bars in such a way that one behind the other in the rolling direction several four-roll stands are arranged, the rolls of which form a composite caliber with an approximately square cross-section, and that the diagonals of the square cross-sections of immediately successive roll stands are offset from one another by 45 ° are and that finally a four-roll finishing stand is arranged in connection with the rolling train, its composite Caliber is shaped according to the finished cross-section.

The invention enables the number of stitches to be reduced, as a result of which one comes with a smaller number from stands, so that the entire rolling mill can be built in a compact design.

Embodiments of the invention are explained below with reference to the accompanying drawings, in which

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show:

Fig. 1 caliber rows for a rolling process with incisions Calibers,

2 shows a series of calibres with assembled gauges from three-roll stands,

Fig. 3 is a diagram for explaining the plastic Deformation in a compound caliber,

4 (A) shows a series of calibres when the invention is applied,

Fig. 4 (B) and (C) '. Roll arrangements for a four-roll stand according to the invention,

5 shows a diagram of the cross-sectional diminution of a Workpiece within the scope of the invention,

6 shows diagrams of the respective deformed cross-sectional areas ,

7 is a diagram comparing the distribution of the spread in conventional methods and in Application of the invention.

Fig. 4 (A) shows the arrangement of a line of four-roll stands with the associated row of passes. After that, a workpiece with roughly square cross-section or circular cross-section like a billet, a small block or a continuous cast billet in the four-roll stand reduced, with the four in the first stitch Corner areas of the cross-section can be edited. So there is a shaping along the respective diagonals. in the Second pass, the corner areas of the cross-section of the workpiece M obtained in the first pass are machined. In further In the third stitch (e.g. in the third stitch), the workpiece is placed in the corner areas of the previous stitch (e.g. in the second stitch) obtained cross-section. The rolling of the workpiece is circular with one stitch through the one or straight lines compound calibres according to Fig. 4 (14) ended.

Have the four-roll stands for stitches 4 - (1) ... (14)

6 0 9 8 5 1/0484

£ 524 224

four rollers each R ^, Ro »R *, R ^» those within the not shown Stand are arranged so that the axial directions are a square or a rectangle within a plane Form perpendicular to the rolling direction.

In the rolling mill according to FIG. 4 (A), a plurality of rolling stands are arranged along the rolling direction. Four-roll stands according to Pig follow in each case. 4 (B) with inclined rolls and four-roll stands according to FIG. 4 (C) with horizontally and vertically arranged rolls alternating one on top of the other. In the case of four-roll stands with inclined rolls, is it true for the case that all four rolls are driven _? the diagonal line Za - Za Zb - Zb of the square spanned by the axis lines of the four rollers coincides with the horizontal axis XX and the vertical axis YY through the center of the caliber cross section. If two opposing rollers are driven in such a stand, the pressed length of the non-driven rollers is smaller than the pressed length of the driven rollers, so that a secure grip of the workpiece is ensured by the rollers. In the four-roll stands according to FIG. 4 (C) with horizontally and vertically arranged rolls, the diagonals Za-Za and Zb-Zb are offset by 45 ° with respect to the horizontal axis XX and the vertical axis YY. As a result, the diagonal lines of the caliber cross-sections are f I
offset.

successive roll stands at 45 ° to each other

The process according to the invention can take place in a continuous Four-roll mill line can also be exercised in an open arrangement of such, with the individual Roll stands each have inclined rollers or horizontally and vertically aligned rollers. It is necessary, however, that the workpieces have to be folded by 45 ° after passing through a pass before the next pass. As a result, additional Roll fittings required for edging the workpieces, j the higher investment costs compared to the one described

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~ "7575775

- 7 - condition the roller mill.

When Vj al ζ en of steel bars with a circular cross-section in the sense of In accordance with the invention, a workpiece with a square cross-section according to FIG. (A) is inclined in a first stitch in a four-roll stand arranged rollers according to Fig. 4 - (1) rolled so that the corner areas of the cross section are reduced. Then it will be the workpiece is introduced into the next roll stand without edges, which is a four-roll stand with horizontally and vertically arranged Rolling according to Fig. 4 - (2) is. The second four-roll stand is arranged so that in this second stitch Four edge areas formed in the first stitch can be reduced to a corresponding cross-sectional shape in the same way as in the first stitch. This will be in every stitch the edge areas of the cross-section formed in the previous stitch are reduced until the desired Receives finished cross-section.

According to Fig. 4 (A), the caliber of the odd-numbered stitches 4 _ (-1), 4 _ (5) ... 4 - (13) are designed so that the four-high roll stands have inclined rolls, the roll axes being a square or a Form a rectangle within a plane perpendicular to the rolling direction, the sides of which are inclined at an angle to the horizontal axis XX and the vertical axis Y - J of the assembled pass. As a result, the workpiece is reduced in the direction of the diagonal lines of the cross section in the starting position of the workpiece M. The caliber of the even-numbered stitches 4 - (2), 4 - (4) ... 4 - (14p are aligned so that the four-high-roll stands have horizontally and vertically aligned rolls, the roll axes being a rectangle or a square in a plane perpendicular to the Form rolling direction, the side surfaces of which run parallel to the horizontal axis and the vertical axis of the pass cross-section.

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Figures 4- (14b), 4- (15b) and 4- (14c) show, respectively modified finished caliber according to the invention using four-roll stands. Mainly for the production of Steel bars and rods of small dimensions is a roller arrangement according to Fig. 4 - (14b) following the stitch 4 - (13) provided to which a four-roll finishing stand 4 - (15 "b) which carries out the finish rolling. You can after the Invention also produce rods with four webs in the longitudinal direction, by making small changes in the lateral distance of the gap between adjacent rollers according to Fig. 4 - (14c) undertakes.

The method according to the invention is for reducing a workpiece M with a square cross-section simultaneously in all Determined corner areas. The workpiece is reduced in the direction of the diagonal to an approximately square cross-section. This is followed by a reduction in the same way, with all corner areas of the previously obtained cross-section be reduced. This process is repeated in the same way with respect to the previously formed cross-sectional shape, to the finished cross-section is obtained.

Investigations into the preferred cross-sectional shape of each caliber within the caliber series, where a compound Caliber has a cross-section with a large average cross-section reduction and small width when passing through the Caliber results have shown that the cross-sectional shape of FIG. 5 is preferable. One recognizes a roughly square one there Cross-section, the four sides of which are curved outwards and each form a section of an arc of a circle Center point at intersection 0 of the two sides of the starting cross-section M, which do not touch the side of the obtained cross-section. The radius of this circle is the distance between the point 0 and the center M of the two sides of the starting cross-section which do not go through the intersection point 0. The starting cross-section is the cross-section in each case

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before starting your tap in the relevant caliber. the The side of the square cross-section formed in a stitch extends in each case between the centers of adjacent sides of the initial cross-section.

However, other cross-sectional shapes are also possible. A square cross-section with straight sides, each of the centers Joining adjacent sides of the output cross-section can also be useful. The caliber cross-section can also be approximately be square with slightly inwardly curved sides, the I in each case the centers of adjacent sides of the starting cross-section;

associate. ;

I The invention avoids two successive stitches j is aligned caliber. As a result, one can work | Roll pieces with a round, square or irregular cross-section into a desired finished profile by adjusting the distance between opposing folds in each pass of the rolling program. j

6 shows the result of studies on the plastic j see deformation within the scope of the invention using! Cross-sectional elements. Fig. 6 (B) shows the respective elastic deformation when rolling a workpiece ¥ with a square cross section according to Fig. 6 (B) with a reduction in the corner areas of the cross section. The workpiece with the cross-section of FIG. 6 (B) is then reduced to a round cross-sectional shape as shown in FIG. 6 (C). These diagrams clearly show that a broadening due to the reduction within the scope of the invention is very small. The rolling pressure exerted on the workpiece is distributed in such a way that the workpiece is worked through evenly in the four directions with respect to the corners of the various workpiece cross-sections, so that better forging is obtained compared with a conventional process.

Fig. 7 shows the small increase in the cross-section reduction

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according to the invention as an excellent feature. As an example, the cross-section is reduced to a square shape. According to Fig. 7, the central region undergoes compression deformations in four directions, so that there occurs a lateral constriction. Assuming the total lateral constriction of a small cross-sectional element as S ^ (%) and the total lateral spread of a cross-sectional _{element as S 2} (%), the relative total spread is (-S ^ + S ₂ ) (%). If one specifies the workpiece width on the entry side with 2B and that of a small cross-sectional element on this side with Bo, then the workpiece width on the exit side results in

2B + (-S ₁ + S ₂ ) χ Bo ν 100.

When rolling with four-roll stands within the scope of the invention, the relationship can apply S _x ,> S ₂ ; this means that overall no broadening occurs, which is very important in the context of the invention.

The small width in the context of the invention makes it possible that the width hp of the roll gap is almost the distance b ^ between opposing 7 / alzenoberf laughs according to Fig. 4 (A) is the same. This means that overcrowding is on is reduced by a negligible fourth. This result cannot be achieved with conventional rolling processes with incised gauges and also with three-roll stands. This is the most important and surprising advantage of the invention. This contributes to the surface improvement of the V / alzgutes at.

Fig. 4 (A) shows a pass series using a roller mill with composite gauges of four-roll stands, after which a cross-section reduction of 20 - 50% is in one Stitch possible, whereby this is the mean value. In this way one obtains a greater concentration of the force of the VJalzdruck the cross-sectional center of the workpiece, as this is

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cut calibers is possible. Therefore, the invention represents the best rolling process for workpieces that are round or uneven Cross-section available without the need for preliminary stitches.

The invention brings about an increase in the mean reduction in cross-section. As a result, you can use a roll a smaller number of stitches. This enables the Vi'alzwerk to be reduced in size. In addition, the invention brings only one very thing small width, so that a good surface of the salt is guaranteed. The method according to the invention enables thus a rolling of high-quality steel bars with a high output.

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Claims (6)

- 12 claims 1. ^ Procedure for rolling steel bars from a square "" initial workpiece, characterized in that in a four-roll stand, whose roll axis is arranged on the sides of a rectangle oriented perpendicular to the rolling direction are, the starting cross-section in each case at the same time in the square areas along the respective diagonals for training an approximately square cross-section is reduced, the sides of which are approximately the centers of adjacent sides of the initial cross-section connect that this reduction is repeated several times until the end cross-section is obtained and that the Final shaping of the cross-section by reducing in a compound caliber of the desired shape within one Four-roll stand takes place. 2. The method according to claim 1, characterized in that the reduction to a cross section with outwardly curved Sides of squares takes place, each of which forms part of a circular arc, the center of which is at the intersection of neighboring ones Sides of the output cross-section and the centers of the connects the two remaining adjacent sides of the output cross-section (Fig. 5) 3. The method according to claim 1 or 2, characterized in that the cross-section reduction of the workpiece amounts to an average of 20 to 50 % . 4-. Rolling train for rolling steel bars with four-roll stands whose Y / alzenachsen each on the sides of a perpendicular to Rectangles aligned with the rolling direction are arranged, characterized in that several one behind the other in the rolling direction Four-roll stands are arranged, the rolls of which are a composite ' Form calibers with a roughly square cross-section, and that the diagonals of the square cross-sections are immediately consecutive Roll stands are offset from one another by 45 809851/0484 and that finally a four-roll ready-made grust afterwards is arranged on the rolling train, the composite caliber is shaped according to the finished cross-section. 5 · V / alzenstrasse according to claim 4-, characterized in that the four rolls of each four-roll stand are driven. 6. V / Alzenstraße according to claim 4-, characterized in that two rolls of each four-roll stand are driven and that the pressed length of the driven rolls is greater than the non-driven rollers, with the axis lines of the four folds forming a rectangle. 809851/0484 Blank page