JP2002292408A - Removing method and apparatus for joined protruding portion of hot-rolled blooms - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a removing method and an apparatus for the joined protruding portion of hot-rolled blooms capable of attaining a targeted crown of products by surely preventing a joined portion from breaking during finish rolling. SOLUTION: The removing apparatus 5 for a joined protruding portion of hot-rolled blooms provides a cylinder-shaped rotary removing member 6 rotatably removing a joined protruding portion S4 formed at a joined portion S3 between the back-end portion of a preceding bloom S1 and the front-end portion of a succeeding bloom S2. The cylinder-shaped rotary removing member 6 is formed so as to reduce its outer diameter in proportion to end portions of the preceding bloom S1 and succeeding bloom S2 in a widthwise direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining ridge of a hot slab for removing a ridge formed at a joining portion between a rear end of a preceding slab and a tip of a following slab after rough rolling. The present invention relates to a method for removing a raised portion, and a device for removing a joined raised portion of a hot steel billet having a cylindrical rotation removing member for removing the raised portion while rotating.
Here, the "preceding slab" is a slab such as a sheet bar to be subjected to finish rolling, and includes a slab that is being finish-rolled with its rear end remaining on the finish rolling mill entry side. The "succeeding billet" refers to a billet such as a sheet bar that is subjected to finish rolling following the preceding billet.

[0002]

2. Description of the Related Art In recent hot rolling of steel, poor biting at the tip of a slab, narrowing of the rear end of a slab, trouble running on a run-out table at the tip of a slab, and dimensional defects at the front and rear ends of a slab. In order to prevent such a situation, so-called endless rolling is employed, in which the rear end of the preceding steel slab and the front end of the succeeding steel slab are successively rolled while being successively joined between the rough rolling and the finish rolling. In the endless rolling, a joining device for joining a preceding steel slab and a following steel slab includes a device using induction heating and a device using friction welding.

[0003] In this endless rolling, when the rear end of the preceding slab and the front end of the following slab are joined, a bulge protruding from the front and back surfaces of the slab is generally formed at the joint. It is a target. When the slab joined with this ridge is finish-rolled, the ridge falls down, the base material of the slab becomes extremely thin with the increase in the number of passes, and eventually the plate breaks. There is.

[0004] In order to prevent the plate breakage, various devices have been proposed for removing a raised portion generated at a joint portion before finish rolling. For example, Japanese Patent Application Laid-Open No. 63-160707 discloses that a raised portion and an oxide scale generated at a joint are
There is disclosed a hot rolling facility for cutting and removing a plurality of blades having different heights attached to a vertically movable tool rest. Japanese Patent Application Laid-Open No. Hei 7-241601 discloses a ridge removing device for cutting and removing a ridge formed at a joint by rotating a cylindrical rotation removing member having a plurality of blades extending in the width direction of a steel piece. It has been disclosed.

A ridge removing device for removing a ridge by rotating a cylindrical rotation removing member as disclosed in Japanese Patent Application Laid-Open No. 7-241601 is disclosed in, for example, FIG. Applied to cold rolling equipment. The rolling equipment includes a rough rolling mill 101, a coil box 102 for winding and rewinding a billet after rough rolling, and a crop shear 103 for removing a defective shape portion at a leading end and a trailing end of the billet. And a movable joining device 104 for heating and pressing the rear end of the preceding steel slab S1 and the front end of the following steel slab S2 to join the rear end and the following steel slab S2. A ridge removing device 105 having a cylindrical rotation removing member 106 for removing a ridge formed at a joint with the tip by a rotational drive, and a plurality of rolls for continuously rolling a steel piece after removing the ridge. And a finishing mill 107 composed of stands F1, F2...

Accordingly, the billet roughly rolled by the rough rolling mill 101 is wound and unwound by the coil box 102, and then, the crop shear 103 is used to remove the defective shape at the leading end and the trailing end. And
The trailing end of the preceding preceding billet S1 and the following trailing billet S2
Are joined by the joining device 104. At the time of this joining, a bump is formed at the joint, and the bump is formed by the cylindrical rotation removing member 106 of the bump removing device 105.
To be removed. Then, the slab from which the protruding portions have been removed is rolled to a predetermined plate thickness by the finish rolling mill 107 to be a product.

Here, the structure of the bump removing device 105 will be described in more detail with reference to FIG. As shown in FIG. 4, the ridge removing device 105 includes cylindrical rotation removing members 1 installed on the upper and lower sides of a preceding steel piece S1 and a following steel piece S2.
06, and a pressure reduction cylinder 110 connected to both ends of the rotation shaft 109 of each rotation removing member 106.
On the surface of each cylindrical rotation removing member 106, there is a preceding billet S1.
And a plurality of blades 108 extending in the width direction of the succeeding billet S2 are provided. The outer diameter of each cylindrical rotation removing member is a billet S
1 and S2 are uniformly formed in the width direction. Each rotation removing member 106 rotates the upper and lower blade gaps by the operation of the screw-down cylinder 110 while rotating in the rotation direction opposite to the conveying direction of the billets S1 and S2 (equally 1 to 5 mm thinner than the plate thickness). The raised portion S4 formed at the joint S3 between the rear end of the preceding steel slab S1 and the front end of the subsequent steel slab S2 is cut and removed by the blade 108.

[0008]

However, the conventional protruding portion removing device 105 shown in FIG. 4 has the following problems. That is, it is desirable that the joint portion S3 between the rear end portion of the preceding steel slab S1 and the front end portion of the subsequent steel slab S2 be joined over the entire width of the steel slabs S1 and S2.
As shown in FIGS. 4B and 5A, unjoined portions S5 often occur at both ends in the width direction. For this reason, when the unbonded portion S5 is removed by the raised portion removing device 105 of the raised portion S4 of the bonded portion S3 generated at the end in the width direction, and when the bonded portion S3 is rolled by the finish rolling mill 107, FIG. As shown in (A), when the work roll 111 of the F1 stand is rolled to extend in a belly direction, an excessive tension T is generated in the unjoined portion S5 at the end in the width direction due to a difference in elongation strain in the width direction during rolling. 5 (B)
As shown in Fig. 7, after the finish rolling, a crack propagated from the unjoined portion S5, and a trouble of breaking the plate occurred.

When such a trouble occurs, a large production loss is caused due to the stop of the line for post-processing. In addition, in order to prevent the plate breakage, the crown ratio change of the F1 stand must be limited so as to perform the elongation rolling, and there is a problem that the target crown of the product cannot be achieved. Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a hot steel capable of reliably preventing a joint break during finish rolling and achieving a target crown of a product. It is an object of the present invention to provide a method and an apparatus for removing a joint ridge of a piece.

[0010]

In order to solve the above-mentioned problems, a method for removing a joint ridge of a hot slab according to claim 1 of the present invention is a method of removing a rear end of a preceding slab and a following slab. In the method for removing a raised portion of a hot slab that removes a raised portion formed at a joint with a tip portion, the removal of the raised portion causes the plate thickness of the bonded portion to be closer to a width direction end of the slab. It is characterized by increasing the thickness as it goes.

According to a second aspect of the present invention, there is provided an apparatus for removing a joint raised portion of a hot billet, wherein the raised portion is formed at a joint portion between a rear end portion of a preceding billet and a distal end portion of a succeeding billet. In the joint ridge removal device for hot billet having a cylindrical rotation removing member that removes while rotating the portion, the cylindrical rotation removing member,
It is characterized in that the outer diameter decreases toward the widthwise end of the preceding and following billets.

According to the method and the apparatus for removing a raised portion according to the present invention, after the removal of the raised portion by the rotation removing member, the plate thickness near the unjoined portion formed at the width direction end of the joined portion has a width. It becomes larger than the plate thickness at the center in the direction. When the joining portion of the steel slab with the thickness near the unjoined portion at the width direction end portion larger than the thickness at the center portion in the width direction is rolled by a finish rolling mill, after finishing rolling, the joining portion becomes a uniform plate in the width direction. It will be thick,
Before finish rolling, the sheet thickness near the unjoined portion at the end in the width direction is larger than the sheet thickness at the center in the width direction. , Will grow larger. For this reason, the tension acting on the unjoined portion during rolling is smaller than the tension acting on the central portion in the width direction, and the growth of a crack in the unjoined portion is prevented, and the fracture of the joined portion is reliably prevented.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a schematic explanatory diagram of a continuous hot rolling facility to which a method and an apparatus for removing a joint ridge of a hot slab according to the present invention are applied. FIG. 2 is a schematic front view of the ridge removing device in FIG. In FIG. 1, a rolling facility to which the joint ridge removing device of the present invention is applied performs a rough rolling mill 1 and a winding and rewinding of a roughly slab, similarly to the rolling facility shown in FIG. 3. Coil box 2 to be performed, a crop shear 3 for removing a defective shape portion at a leading end and a trailing end of a billet, and a rear end and a trailing billet S of a preceding billet S1.
2 is provided with a movable joining device 4 for heating and pressing the front end portion for joining. In order to heat the joining device 4, an induction heating device for inductively heating the front and rear ends of the steel slabs S1 and S2 with an alternating magnetic field is used. However, the joining may be performed by friction welding. On the exit side of the joining device 4, a cylindrical rotation removing member 6 for removing a raised portion formed at the joining portion between the rear end of the preceding steel slab S1 and the front end of the following steel slab S2 by rotational driving. Is provided. Further, a finishing mill 7 including a plurality of stands F1, F2,... That continuously rolls the steel piece from which the protrusions have been removed is provided on the exit side of the protrusion removal device 5.

After the steel slab roughly rolled by the rough rolling mill 1 is wound and unwound by the coil box 2, the crop shear 3 removes defective portions at the leading end and the trailing end. And the preceding slab S1
Is joined by the joining device 4 to the leading end of the succeeding billet S2 that follows. At the time of this joining, FIG.
Similarly to FIGS. 7A and 7B, a raised portion S4 is formed at the bonded portion S3, and unbonded portions S5 are formed at both ends in the width direction. Then, the raised portion S4 is removed by the cylindrical rotation removing member 6 of the raised portion removing device 5, and the steel pieces S1 and S2 from which the raised portion S4 has been removed are rolled to a predetermined thickness by a finish rolling mill 7, and the product and Become.

Here, the structure of the ridge removing device 5 will be described in detail with reference to FIGS. 1 and 2. The ridge removing device 5 is installed on both the upper and lower sides of the preceding steel piece S1 and the following steel piece S2. Cylindrical rotation removing member 6 and each rotation removing member 6
And a reduction cylinder 10 connected to both ends of the rotary shaft 9. On the surface of each cylindrical rotation removing member 6,
A plurality of blades 8 extending in the width direction of the leading slab S1 and the following slab S2 are provided. Each cylindrical rotation removing member 6 is formed so as to gradually decrease in an R-shape as the outer diameter thereof approaches the both ends in the width direction of the preceding steel piece S1 and the following steel piece S2. Each of the rotation removing members 6 is made up of the billets S1 and S2.
The upper and lower cutter gaps G at the center in the width direction are rotated while rotating in the rotation direction opposite to the conveyance direction of the lower cylinder 1.
By tightening until the thickness becomes 1 to 5 mm thinner than the initial plate thickness by the operation of 0, the rear end of the preceding billet S1 and the succeeding billet S2
The protruding portion S4 formed at the tip of the substrate is cut and removed. When the protruding portion S4 is removed, the thickness of the joining portion S3 of the steel pieces S1 and S2 becomes 1-5 mm smaller than the initial thickness at the center in the width direction according to the outer shape of the cylindrical rotation removing member 6.
1 and gradually increases toward both ends in the width direction to have a plate thickness t2 at both ends. For this reason, the plate thickness near the unbonded portion S5 formed at both ends in the width direction of the bonded portion S3 is larger than the plate thickness at the center portion in the width direction.

As described above, the unjoined portions S5 at both ends in the width direction are formed.
When the joining portion S3 of the steel pieces S1 and S2 in which the thickness in the vicinity is larger than the thickness in the center in the width direction is rolled by the finishing mill 7,
After finish rolling, the joining portion S3 has a uniform thickness in the width direction. Before finish rolling, the unjoined portions S5 at both ends in the width direction
Since the plate thickness in the vicinity is larger than the plate thickness in the center in the width direction, the plate thickness in the vicinity of the unjoined portion S5 is larger than that in the center in the width direction, the plate thickness is reduced, and the plate is further expanded. For this reason, the tension T acting on the unjoined portion S5 during rolling is smaller than the tension T acting on the central portion in the width direction. Is prevented. Thus, it is not necessary to limit the change in the crown ratio of the F1 stand of the finishing mill 7, and the target crown of the product can be achieved.

The size of R, which determines the outer diameter of the cylindrical rotation removing member 6, is determined based on the fact that the billets S1 and S2 after rough rolling have a thickness of about 30 mm and a width of about 1200 mm. , 50,000 mm to 1500,000 mm. When the size of R is within this range, the joint S3 is obtained even if the crown ratio of the F1 stand is changed in a range of ± 1% (-change for belly extension, + change for ear extension).
It has been confirmed by experiments that the breaking length at the end in the width direction is small and does not change much.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various changes can be made. For example, the cylindrical rotation removing member 6 is not only formed when the outer diameter thereof is gradually reduced in an R-shape as it goes to both ends in the width direction of the preceding steel piece S1 and the following steel piece S2, As long as the plate thickness in the vicinity of the unjoined portion S5 can be made larger than the plate thickness at the center in the width direction of the slab, the outer diameter becomes linear, parabolic, trapezoidal or the like as it goes to the end in the width direction. It may be formed to decrease. Further, as the cylindrical rotation removing member 6, not only the case where the blade 8 is provided on the surface but also a rotating grindstone, the raised portion S4 may be ground.

[0019]

As described above, according to the method and the apparatus for removing a joint raised portion of a hot billet according to the present invention, the cylindrical rotation removing member has an outer diameter of the leading billet and the trailing billet. Since the protrusion is reduced toward the width direction end side, after the removal of the protruding portion by the rotation removing member, the plate thickness in the vicinity of the unbonded portion formed at the width direction end of the bonded portion is in the width direction center. Part thickness. Thereby, the tension acting on the unjoined portion during rolling is smaller than the tension acting on the central portion in the width direction, and it is possible to prevent the crack from developing in the unjoined portion and reliably prevent the plate from breaking at the joined portion. . Therefore, it is not necessary to limit the change in the crown ratio of the F1 stand of the finishing mill, and the target crown of the product can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a continuous hot rolling facility to which a method and an apparatus for removing a joint ridge of a hot slab according to the present invention are applied.

FIG. 2 is a schematic front view of the ridge removing device in FIG. 1;

FIG. 3 is a schematic explanatory view of a continuous hot rolling facility to which a conventional hot slab joining ridge removing device is applied.

4A and 4B show a raised portion removing device in FIG. 3, wherein FIG. 4A is a schematic side view, FIG. 4B is a schematic front view, and FIG. 4C is a schematic plan view.

5A and 5B show a state of a billet rolled by the continuous hot rolling equipment of FIG. 3, wherein FIG. 5A is a perspective view illustrating a state of tension acting on the billet during finish rolling, and FIG. It is a top view explaining the state of the crack which propagates from an unjoined part later.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Rough rolling mill 2 Coil box 3 Crop shear 4 Joining device 5 Ridge removing device 6 Cylindrical rotation removing member 7 Finish rolling mill 8 Blade 9 Rotating shaft 10 Rolling cylinder S1 Leading steel slab S2 Trailing steel slab S3 Joining S4 Raising Part S5 Unjoined part

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4E002 AD02 BA01 BD05 CB08

Claims (2)

[Claims] 1. A method for removing a raised portion of a hot billet for removing a raised portion formed at a joint between a rear end portion of a preceding billet and a distal end portion of a succeeding billet. The method according to claim 1, wherein the thickness of the joint is increased toward the end in the width direction of the steel slab. 2. A joining ridge of a hot slab having a cylindrical rotation removing member for removing a ridge formed at a joining portion between a rear end portion of a preceding slab and a leading end portion of a following slab while rotating. In the portion removing device, the cylindrical rotation removing member is formed such that its outer diameter decreases as it goes to the width direction end side of the preceding steel slab and the following steel slab. Stripping ridge removal device.