JP2013158827A - Method for manufacturing rolled shape steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a corner drop-out shape steel forming rounded sections at flange tips of plural kinds of rolled H-steel having various dimensions without introducing new facilities.SOLUTION: A first intermediate rolled material 25-1 is obtained by subjecting a rough rolled material 22 having a dog bone shape to intermediate universal rolling by a reverse method with plural passes so that the value of draft balance becomes 0.3 or more in the final pass. Next, flanges 25-1f of the first intermediate rolled material is roll-reduced by intermediate rolling of 1 pass by an edger rolling mill having rounded sections for corner drop-out of inner corners of flanges of the first intermediate rolled material at grooved corners, and a second intermediate rolled material 25-2 is obtained in which flange tips 27 are made thicker than flange centers 28. Finally, the second intermediate rolled material is subjected to finish universal rolling of 1 pass by a finish universal rolling mill having vertical rolls in which grooves for corner drop-out of outer corners of flanges 25-2f of the second intermediate rolled material are arranged.

Description

  The present invention relates to a method for producing rolled steel that can be suitably used as a rolled steel for shipbuilding because of its excellent paint adhesion.

  Steel materials used for shipbuilding are painted and used for the purpose of corrosion protection. However, since sharp edges exist at the corners of the flange of the shape steel, the adhesion of the shape steel paint is poor and the coating film is easily peeled off. Currently, the “Guidelines for IMO Coating Performance Standards” use at least a 2mm round edge or three-pass gliding, or an equivalent or better method, on the shape steel before coating to prevent the occurrence of corrosion due to peeling of the coating film. It is stipulated that the edge pretreatment is performed, and the manufacturing cost rise due to the edge pretreatment cannot be denied.

  If the edge of the flange is a rolled shape steel that has been scraped off by rolling (referred to in this specification as a “corner drop shape steel”), the edge pretreatment can be omitted, but the angle drop shape steel can be reliably mass-produced. No manufacturing technology has been established so far.

  Patent Document 1 discloses an invention in which a stepped roller guide for corner dropping is newly disposed on the front surface of a finishing universal rolling mill to form a rounded portion on the outer side of the flange tip of the rolled section steel. Discloses an invention in which a corner-dropping groove is provided on the outer side of the flange end of the saddle roll of the intermediate universal rolling mill to form an R portion on the outer side of the rolled tip steel flange.

JP 2010-274269 A JP 60-162504 A

  Since the invention disclosed by Patent Document 1 cannot be implemented unless a stepped roller guide for corner dropping is newly provided in addition to the existing rolling equipment, there is a problem that it cannot be easily implemented. On the other hand, the invention disclosed in Patent Document 2 is implemented by providing a corner drop groove in the intermediate universal rolling mill group. Here, depending on the dimensions of the material to be rolled, in the intermediate universal rolling mill group, the flange width differs by about 2 to 30 mm between the first pass and the final pass. For this reason, since rolling is always performed in a state where there is a groove with respect to the flange width from the first half pass to the final pass of the intermediate universal rolling, if a material to be rolled that is excessive with respect to the groove width is rolled, If the flange width of the rolled material that has been rolled by the roughing mill is substantially constant due to the occurrence of wrinkles, it cannot be used unless the flange width is substantially constant. Can not form.

  An object of the present invention is to provide a method for producing a corner-drop shaped steel capable of forming an R portion at the flange tip of a plurality of types of rolled steel having various dimensions without introducing new equipment.

  Conventionally, in finishing universal rolling using a finishing universal rolling mill, it has been considered that the R portion cannot be formed outside the flange tip of the material to be rolled because the amount of reduction is small. As a result of intensive studies without being bound by such common technical knowledge, the inventor of the present invention, in a rough rolled material having a dogbone shape manufactured by performing rough rolling with a roughing mill on a heated slab, Intermediate universal rolling by multi-pass reverse method using universal rolling mill and intermediate edger rolling by edger rolling mill are used as intermediate rolling material, and then the intermediate rolling material is finished by one pass finishing rolling by universal rolling mill. The following findings (A) to (C) were obtained when manufacturing the shape steel.

  (A) By increasing the thickness of only the flange end of the intermediate rolled material from the center of the flange and providing a groove for corner dropping on the roll of the finishing universal rolling mill, the intermediate rolled material is finished. On the other hand, by performing finish rolling with only one pass of a finish universal rolling mill, the R portion can be formed on the outer end of the flange of the rolled shape steel.

  (B) Finishing universal rolling mills can be easily machined without providing any new equipment if a lathe machine used for circumferential cutting of rolls is used to form a groove for corner cutting on the rolls. What you can do.

  (C) Since the groove for corner cutting is provided in the roll of the finishing universal rolling mill, it is not affected by the change in the flange width in the intermediate rolling group as in the invention disclosed in Patent Document 2, and various Able to accommodate the size.

  Accordingly, the present inventor has made various adjustments to the balance of the web and flange reduction amount (rolling balance) in intermediate universal rolling by a multi-pass reverse method, and as a result, (D) flange superiority in intermediate universal rolling. After taking the reduction balance, the reduction by the edger rolling machine is performed after the intermediate universal rolling, so that only the flange tip of the intermediate rolled material after the intermediate rolling can be thicker than the center of the flange, It has been found that by performing finish rolling with only one pass of a finishing universal rolling mill provided with a corner dropping groove, it is possible to produce a corner falling shape steel having a desired R shape outside the flange tip. The present invention is based on these novel findings (A) to (D).

  In the present invention, (i) intermediate universal rolling by a reverse method using a plurality of passes by an intermediate universal rolling mill is performed on a rough rolled material having a dogbone shape by the following formula (1): 2 (ψtf−ψtw) / (ψtf + ψtw) The reduction balance value to be made is 0.3 or more in the final pass of the intermediate universal rolling, so that a first intermediate rolled material having a flange and a web is obtained. (Ii) of the first intermediate rolled material By rolling down the flange by one-pass intermediate edger rolling by an edger rolling mill equipped with an edger roll having an edger roll having a rounded corner at the inner corner of the flange of the first intermediate rolled material. A second intermediate rolled material whose flange tip is thicker than the flange center, and (iii) a second intermediate rolled material is used as the second intermediate rolled material. By performing one-pass finishing universal rolling with a finishing universal rolling mill provided with a vertical roll provided with a groove for corner dropping at the outer corner of the flange, both the inner corner and the outer corner of the flange are rolled by rolling. A rolled section steel manufacturing method characterized by manufacturing a rolled section steel having an R portion formed.

  Here, the sign ψtf in the equation (1) is the rolling reduction of the flange of the shape steel defined as ln (the thickness of the flange of the n−1th pass / the thickness of the flange of the nth pass), and the sign ψtw is It is the rolling reduction of the shaped steel web defined as ln (n-1th pass web thickness / nth pass web thickness).

  According to the present invention, it is possible to manufacture a section steel such as an H-section steel having an R at the end of the flange without introducing new equipment, and it is possible to cope with rough rolling shapes of various sizes.

FIG. 1 is an explanatory view schematically showing an outline of an example of a rolling line of rolled H-section steel. FIG. 2 is an explanatory view schematically showing changes in the cross-sectional shape of the material due to rolling of the rolled H-section steel for each of the conventional method and the method of the present invention. Fig.3 (a) is explanatory drawing which shows schematic shape of the edger rolling mill provided with the edger roll which has the R part for the corner drop of the inner side corner | angular part of the flange of a 1st intermediate rolling material in a hole type | mold corner. FIG.3 (b) is explanatory drawing which shows schematic shape of a finishing universal rolling mill provided with the vertical roll which has the groove | channel for corner dropping.

  The present invention will be described with reference to the accompanying drawings. In the following description, a case where the rolled section steel is a rolled H-section steel will be taken as an example. However, the present invention is not limited to the rolled H-section steel, but a rolled H such as a rolled groove section steel or a rolled angle section steel. The present invention is also applied to a rolled shape steel having a flange and a web other than the shape steel.

  FIG. 1 is an explanatory view schematically showing an outline of an example of a rolling line 10 of rolled H-section steel. FIG. 2 is an explanatory view schematically showing changes in the cross-sectional shape of the material due to rolling of the rolled H-section steel for the rolled H-section steel 24 according to the conventional method and the rolled H-section steel 26 according to the method of the present invention. Further, FIG. 3A includes edger rolls 13a and 13b each having a corner-cutting R portion of the inner corner of the flange 25-2f of the first intermediate rolled material 25-2 in the hole-shaped corner 30. It is explanatory drawing which shows schematic shape of the edger rolling mill 13, and FIG.3 (b) is explanatory drawing which shows schematic shape of the finishing universal rolling mill 14 provided with the vertical rolls 14c and 14d which have the groove | channel 33 for corner dropping. .

  In general, the present invention is performed through a rough rolling process, an intermediate universal rolling process by the intermediate universal rolling machine 12, an intermediate edger rolling process by the edger rolling machine 13, and a finishing rolling process by the finishing universal rolling machine 14 in this order. Therefore, each process will be described sequentially.

[Rough rolling process by rough rolling machine 11]
As shown in FIG. 1 and FIG. 2, the slab 21 extracted after being heated to a predetermined temperature in a heating furnace (not shown) is subjected to rough rolling by a roughing mill 11 to become a base of H-section steel. A rough rolled material 22 having a dogbone shape is used.

  Conditions for rough rolling by the rough rolling mill 11 may be well-known and conventional conditions, and are not limited to specific conditions. Since such conditions are well known to those skilled in the art, further explanation regarding the rough rolling process is omitted.

[Intermediate rolling process by intermediate universal rolling mill 12]
A first intermediate rolled material 25-1 having a product thickness is obtained by subjecting the rough rolled material 22 having a dogbone shape to intermediate universal rolling by a reverse method of a plurality of passes (ten and several passes) by the intermediate universal rolling mill 12. To do.

  In the intermediate universal rolling process by the intermediate universal rolling mill 12, the reduction balance value defined as the above formula (1): 2 (ψtf−ψtw) / (ψtf + ψtw) is 0.3 or more in the final pass of the intermediate universal rolling. And so on.

  The reduction balance value is the reduction ratio ψtw of the web of the first intermediate rolled material 25-1 having an approximately H-shaped cross-sectional shape (= ln (n-1th web thickness / nth web thickness)). And the rolling reduction ratio ψtf (= ln (thickness of the flange of the n−1th pass / thickness of the flange of the nth pass)), and the reduction of the web and the flange in any pass of intermediate universal rolling. It is an index indicating the state.

  If the rolling balance value in the final pass of the intermediate rolling by the intermediate universal rolling mill 12 is not more than 0.3, it is not possible to sufficiently increase only the flange tip, and the flange tip is made into a corner drop shape only by finish rolling. Becomes difficult.

  In the present invention, by setting the reduction balance value in the final pass of the intermediate universal rolling to 0.3 or more, a flange strong reduction state is created, and thereby it is possible to promote the flange widening more excessively than the conventional method. It becomes.

  By the intermediate universal rolling by the intermediate universal rolling mill 12, a first intermediate rolled material 25-1 having a flange and a web is manufactured.

[Intermediate edger rolling process by edger rolling mill 13]
The flange of the first intermediate rolled material 25-1 is reduced by one-pass intermediate rolling by the edger rolling mill 13. In this way, the second intermediate rolled material 25-2 is manufactured by reducing the flange 25-1 f of the first intermediate rolled material 25-1 by the edger rolling mill 13.

In the second intermediate rolled material 25-2, the tip 27 of the flange 25-2f is thicker, for example, by 1.0 mm or more than the center 28 of the flange 25-2.
In addition, at the hole corners of the upper and lower edger rolls 13a and 13b of the edger rolling mill 13, the R portion 30 for corner dropping of the inner corner 29 of the flange 25-1f of the first intermediate rolled material 25-1. Is provided. Thereby, R part is formed inside the front-end | tip 27 of the flange 25-2f of the 2nd intermediate rolling material 25-2.

  On the other hand, in the conventional method, as shown in FIG. 2, the rolling balance value in the final pass of the intermediate universal rolling by the intermediate universal rolling mill is about 0.12 to 0.18, which is not less than 0.3 specified by the present invention. Therefore, the width expansion of the flange of the first intermediate rolled material (not shown) by the conventional method is less than that of the method of the present invention. For this reason, even if the flange of the first intermediate rolled material is reduced by one-pass intermediate rolling by the edger rolling mill 13, the second intermediate rolled material 23 has the tip 31 of the flange 23f at the center of the flange 23. No increase in thickness relative to 32.

  The edger rolling mill of the intermediate universal rolling mill group carries out a reduction in every pass. However, it is possible to reliably drop the corners inside the flange by firmly expanding the width in the final pass of the intermediate universal rolling. In addition, it is necessary to make the final path wider in order to cut off the corners of the flange in the finish rolling mill.

[Finish universal rolling process by finish universal rolling mill 14]
In the present invention, the second intermediate rolled material 25-2 is subjected to one-pass finish universal rolling by the finishing universal rolling mill 14, and the rolled H-section steel 26 is manufactured.

  The finishing universal rolling mill 14 has horizontal rolls 14a and 14b and trough rolls 14c and 14d. The trough rolls 14c and 14d are provided with corner dropping grooves 33 at the outer corners of the flange 25-2f of the second intermediate rolled material 25-2. Thereby, R part is also formed in the outer side of the front-end | tip 27 of the flange 25-2f of the 2nd intermediate rolling material 25-2.

  If it is a normal punch roll of a finishing universal rolling mill, as shown to Fig.3 (a), the inner corner | angular part 34 and outer corner | angular part of the front-end | tip of the flange 24f of the rolling H-section steel 24 shape | molded only by finishing 1 pass | pass Since No. 35 does not have the target R shape, the paintability of this rolled H-section steel 24 is unsatisfactory.

  Further, when rolling in one pass of the finishing universal rolling mill provided with the scissors rolls 14c and 14d provided with the groove 33 for corner dropping, only the tip of the flange 25-2f is thickened as described above. If the second intermediate rolled material 25-2 is not passed, the target flange tip shape cannot be obtained.

  In the present invention, only the tip 27 of the flange 25-2f of the second intermediate rolled material 25-2 is thickened by 1.0 mm or more from the center 28, so that the outer side of the tip 27 of the flange 25-2f is a roll. 14c and 14d are preferentially crushed by the corner-dropping grooves 33 provided on the corners 14c and 14d, so that the corners are sufficiently dropped. Therefore, an R portion is also formed by rolling at the outer corner of the flange 26f of the rolled H-section steel 26. can do.

  Since a desired R portion is formed by rolling in both the inner corner portion 36 and the outer corner portion 37 of the flange 26f of the rolled H-section steel 26 manufactured in this manner, the paintability of the rolled H-section steel 26 is improved. Is good.

  In addition, the first intermediate rolled material 25 is formed in the processing of providing the groove 33 for corner dropping in the punch rolls 14c and 14d of the finishing universal rolling mill 14, or in the hole corners of the edger rolls 13a and 13b of the edger rolling mill 13. -1 of the flange 25-1f of the inner corner portion of the flange 25-1f, the processing to provide any corner, without using any new equipment, if using a lathe machine that is used for normal roll turning, Since it can carry out simply, this invention can be implemented without introducing a new installation.

  In addition, the present invention is applicable to various sizes of H-section steel because it is difficult to be affected by the deformation behavior of the material during rolling in the intermediate rolling group because the corners on the outside of the flange can be cut only by a finishing mill. Since it is possible, R part can be formed now in the outer corner | angular part and inner corner | angular part of the front-end | tip of the flange 26f of multiple types of rolled H-section steel 26 which has various dimensions.

DESCRIPTION OF SYMBOLS 10 Rolling line 11 Rough rolling mill 12 Intermediate universal rolling mill 13 Edger rolling mill 13a, 13b Upper and lower edger rolls 14 Finishing universal rolling mill 14a, 14b Horizontal roll 14c, 14d 竪 roll 21 Slab 22 Rough rolled material 23 Second intermediate rolled material 24 Rolled H-section steel 24f by conventional method Flange 25-1 First intermediate rolled material 25-1f First intermediate rolled material flange 25-2 Second intermediate rolled material 25-2f Second Intermediate rolled material flange 26 Rolled H-section steel 26f according to the present invention Flange 27 Second intermediate rolled material flange tip 28 Second intermediate rolled material flange center 29 First intermediate rolled material flange inner side Corner portion 30 R portion 31 for corner dropping Second end of flange of intermediate rolled material 32 Center 33 of flange of second intermediate rolled material Corner drop groove 34 Flange inner corner 35 Flange outer corner 36 Flange inner corner 37 Flange outer corner

Claims (1)

A rough rolling material having a dogbone shape is subjected to intermediate universal rolling by a reverse method of a plurality of passes by an intermediate universal rolling mill, and a reduction balance value defined by the following equation (1) is 0.3 in the final pass of the intermediate universal rolling. By performing as described above, a first intermediate rolled material having a flange and a web is obtained.
The flange of the first intermediate rolled material is subjected to one pass by an edger rolling mill provided with an edger roll having an R portion for corner dropping of an inner corner portion of the flange of the first intermediate rolled material at a hole-shaped corner portion. By rolling down by intermediate edger rolling, the second intermediate rolled material whose flange tip is thicker than the flange center,
Performing one-pass finish universal rolling by a finish universal rolling mill provided with a vertical roll provided with a groove for dropping corners at the outer corners of the flange of the second intermediate rolled material on the second intermediate rolled material To produce a rolled section steel having an R portion formed by rolling at both the inner corner portion and the outer corner portion of the flange.
Reduction balance value = 2 (ψtf−ψtw) / (ψtf + ψtw) (1)
However, the sign ψtf in the equation (1) is a reduction ratio of the flange of the shape steel defined as ln (thickness of the flange of the n−1th pass / thickness of the flange of the nth pass), and the sign ψtw is ln It is a rolling reduction ratio of the shaped steel web defined as (thickness of the web of the (n-1) th pass / thickness of the web of the nth pass).

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