JPH08294706A - Online hot rolled steel joining method - Google Patents

Abstract

PURPOSE: To improve a productivity, and to improve a product quality by rolling while pressurizing a joint by the rear end part of a preceding material and the tip part of a succeeding material. CONSTITUTION: At least a part of the rear end part of a preceding material 2 and the front and the rear side surfaces of the tip part of a succeeding material 3 are covered by a joint 6. And also, at least a part of the rear end face of the preceding material 2 and the tip face of the succeeding material 3 are covered by the joint 6. The joint material 6 is allowed to exist between the preceding material 2 and the succeeding material 3, and has been pressurized. In this state, these materials are joined by biting and rolling with a rolling mill. The material of a steel is, for instance, a low carbon Al killed steel, and for its dimensions, a plate thickness is 50mm, and a plate width is 2200mm. These are hot rolled steel products whose preceding material and the succeeding material run on a pass line while going ahead before and behind each other. Consequently, special preliminary joining is not necessary, and the materials can be joined in a finish rolling first stand.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining materials to be rolled (sheet bar, bar, etc.) on-line between a rough rolling step and a finish rolling step when performing complete continuous hot rolling.

[0002]

2. Description of the Related Art For example, in hot tandem rolling of a thin plate, a slab sent from a steelmaking process is roughly rolled into a sheet bar (rough bar), and this sheet bar is rolled by a hot rolling mill with multiple stands. Then, it is wound into a coil to form a thin plate coil having a predetermined size.

However, in finish rolling, since the sheet bar has a finite length, unsteady rolling is inevitable when the front end of the sheet bar is caught and the rear end of the sheet bar is slipped out. Therefore, from the viewpoint of preventing passing defects such as narrowing of the plate, a method of slowing the passing speed at the time of passing the front and rear ends of the sheet bar is adopted, which is a factor that hinders productivity. There is.

As a countermeasure against this, it has been considered to join a sheet bar having a finite length between a rough rolling mill and a finish rolling mill to perform so-called endless rolling. That is, it is usually a problem to join the sheet bars at the portion surrounded by the dotted line 5 in FIG. Here, 1 is a roll for finish rolling, 2 is a preceding material of a sheet bar which is a material to be rolled, 2-1
Is the trailing edge of the preceding material, 3 is the trailing material, 3-1 is the leading edge of the trailing material, 4 is the table roller, and 5 is the joining position.

Japanese Unexamined Patent Publication (Kokai) No. 57-109574 discloses a process comprising a rough rolling mill, a coil box, a heat retaining device, an unwinding device, a movable joining machine (swing roller table), and a finishing rolling mill. . In this method, joining is done by welding. Therefore, it takes time to join the entire rear end portion of the preceding material and the leading end portion of the following material, and the traveling distance of the mobile joining machine becomes long.

[0006] As an example of a fixed type welding machine, Japanese Patent Laid-Open No. 61-1
No. 58285 and JP-A-61-242768 show processes using electric heating and upset.
In this method, since a fixed welding machine is used, a swing roller type table is unnecessary. However, considering that a seat bar storage device such as a looper is required, and the minimum bending radius of curvature that does not cause plastic deformation of the seat bar is often on the order of about 25 m, enlargement of equipment such as a looper is required. It has the drawback of inevitably increasing costs.

[0007]

In the above-mentioned prior art, since it takes a long time to join the sheet bars, there is a problem that the line length becomes long and the equipment cost becomes high.
In order to solve this problem, it is necessary to develop a technology capable of joining in a short time and having a low equipment cost.

The present invention has been made in order to meet such a demand, and is an online system capable of joining the trailing end portion of the preceding material and the leading end portion of the following material of the hot rolled steel material in a short time and at a low equipment cost. An object is to provide a joining method.

[0009]

The joining method according to the present invention includes a front end portion and a rear end portion of a leading material and a trailing material of a hot rolled steel material running on a pass line in front of and behind each other. , With a joint that covers the upper and lower surfaces of both ends and a part of both end surfaces,
In this method, the joint is joined by rolling while pressing the joint between the trailing end of the preceding material and the leading end of the trailing material, followed by continuous finishing rolling.

Hereinafter, this method will be described in detail.
FIG. 1 is a perspective view showing an example in which the preceding material 2, the joint 6 and the following material 3 are combined and rolled by this method. Joint 6
Covers at least a part of the upper and lower surfaces of the trailing end of the preceding material 2 and the leading end of the trailing material 3, and covers at least a part of the trailing end surface of the leading material 2 and the leading end surface of the trailing material, This joint material is interposed and pressed between the leading material and the trailing material. In this state, they are joined by being bitten into a rolling mill and rolled. The inventors performed rolling under the following conditions using a joint having a shape as shown in FIG.

The experimental conditions are as follows. Plate size: plate width 100 mm, plate thickness 14 mm Joint material size: w = 80 mm, l = 80 mm, p = 20 mm, t = 3 mm, s = 15 mm (see Fig. 2) Material: Both plate and joint materials are low carbon steel As material
Temperature of plate materials 2 and 3 and joint 6: 1030 ° C. Plate material reduction rate: 10% Plate thickness after rolling was 12.6 mm.

FIG. 4A is a plan view showing the shape of the vicinity of the joint after rolling. FIG. 4B is a schematic view of an AA cross section of FIG. In this figure, the preceding material 2, the following material 3 and the joint 6
The boundary is clearly shown, but the adhesion was so excellent that it was difficult to appear even if macro-corrosion occurred. Immediately after this rolling and joining, the plate was not broken even if it was rolled by applying a front / rear tension of 1/3 of the deformation resistance. Immediately after this rolling and joining, a tensile test was conducted at 1000 ° C., and the tensile strength was 14 tons. Estimated joint cross-section = 80 x 12.6 = 10
Since it is 08 (mm ² ), the nominal breaking stress is 13.9 kg /
mm ² , which is almost the same as the base metal, considering that the deformation resistance at the same temperature is about 15 kg / mm ² . In addition, this estimated joint cross-sectional area (= total width of flange portion of joint material × plate thickness of plate material after rolling) is referred to as an effective joint area. Although the joint shape and the rolling reduction were variously changed, good joint strength was obtained in all cases. Also, the higher the rolling reduction, the higher the bonding strength.

When the joint and the rolled material are combined and rolled in this way, they are joined very strongly. This is because not only the contact surfaces are joined due to the high pressure during rolling, but also the surface area of the contact surfaces increases due to rolling deformation. However, it is considered that this is because a new surface is formed and the activity of this portion is high, which has been advantageous for bonding.

As shown in FIG. 2, the joint 6 includes a flange portion 6F which covers a part of upper and lower surfaces of both ends of the preceding material 2 and the following material 3, a rear end surface of the preceding material 2 and the following material 3. The web portion 6W covers at least a part of both end surfaces of the tip end surface. The joint material is interposed between the trailing end portion of the preceding material 2 and the leading end portion of the trailing material, and the joint portion 6 has a flange portion 6F having a length 1 in the rolling direction as shown in FIG. And this length is
It can be selected according to the bonding strength, but it is usually 100-300 mm
It is a degree.

Further, the width w of the flange portion may be selected so as to cover the upper and lower surfaces of both ends of the preceding material 2 and the following material 3 so as to cover at least a part in the width direction. The cross-sectional area (of the surface perpendicular to the longitudinal direction) should be about 0.3 times or more. This is because the front and rear tensions work in the latter stage of the finish rolling mill, and the maximum deformation resistance is about 0.3 times. The plate thickness of the flange of the joint material may be selected according to the required joint strength of the materials to be joined. Usually, it is about 1/5 to 1/2 of the plate thickness of the materials to be joined.

The web portion 6W has a width that covers at least a part of the trailing end surface of the preceding material 2 and the leading end surface of the trailing material 3, and the upper and lower flange portions 6F are located substantially at the center in the longitudinal direction. It is the one to combine. Therefore, the height of the web s
Defines the distance between the upper and lower flange portions, which must be equal to or greater than the plate thickness of the preceding and following materials to be joined. Further, the thickness p of the web portion may be a thickness sufficient to indicate the upper and lower flange portions, and is usually about 10 to 50 mm.

FIG. 3 shows another example of the shape of the joint. In FIG. 3A, the width of the flange portion 6F is divided into two flange portions 6F, 6F which are narrower than the width of the web portion 6W. It has been formed. Further, (b) shows that the web portion 6W is divided into two web portions 6W, 6W narrower than the width of the flange portion.

The joint may be integrally formed by rolling, forging or cutting the web portion and the flange portion, or may be formed by separately processing the web portion and the flange portion and assembling them by welding or the like.

A method of interposing the joint material between the preceding material and the following material will be described. FIG. 5 is a view showing a rolling line, 7 is a finishing rolling mill, 8 is a joint material heating furnace provided close to the rolling line, 9 is a table roller in front of the finishing rolling mill, and 10 and 11 are pinch rollers. , 12 is a joint material insertion device, and 13 is a joint material slide connecting the heating furnace 8 and the rolling line.

The heating furnace 8 is composed of rolled materials (preceding materials,
The joint 6 having a shape capable of obtaining the required joint strength according to the size (width, thickness) of the following material) is heated to near the rolling temperature in the heating furnace.

The joint material slide 13 is provided from the heating furnace 8 to the roller table of the rolling line so as to be orthogonal to the rolling line. In addition, the joint material insertion device 12 is
The insertion shaft 12b is capable of moving forward and backward, the insertion jig 12a attached to the tip thereof, and a drive device (not shown) for moving the insertion shaft forward and backward.

On the other hand, when the trailing end of the preceding material reaches the position of the joint insertion device 12, the joint 6 heated in the heating furnace 8 is extracted on the joint material slide 13 by the extraction device (not shown). Then, the driving device of the joint material inserting device 12 is driven to advance the insertion shaft 12b to move the joint material on the joint material slide to the rolling line.

After retracting the insertion device, the pinch roll 1
0 is driven to advance the trailing material, the joint material on the rolling line is pinched by the trailing end of the leading material and the leading end of the trailing material, and the state is maintained and sent to the finish rolling mill 7 for rolling. Is. At this time, the greater the pushing force of the pinch roll, the stronger the coupling between the preceding material and the following material by the joint material.

The upper and lower surfaces of the preceding material and the following material are introduced between the upper and lower flange portions of the joint material so that the end surfaces of the preceding material and the following material contact the surface of the web portion of the joint material, for example, as shown in FIG. As shown in FIG. 6, it is preferable that the slide 13 of the rolling line is supported via a hydraulic cylinder 14 so as to be able to move up and down so that the position of the joint material in the height direction on the rolling line can be adjusted.

Since the joint material and the rolled material run on the rolling line, the table roller 9 from the material insertion device to the rolling mill 7 has a central portion 15 of the roller through which the joint material passes, as shown in FIG. It is preferable that the radius of is reduced at least by the amount corresponding to the plate thickness of the flange portion of the joint material from the end portion.

[0026]

Example A joint rolling test was conducted under the following conditions. <Sheet bar> Material: Low carbon Al killed steel Dimensions: Plate thickness 50 mm, Plate width 2200 mm End face size: The cut surface shape by shear is shown in FIG. In the figure, t is the plate thickness. The approximate size of the end face is x ₁ = 25 mm y ₁ = 10 mm x ₂ = 10 mm y ₂ = 26 mm. <Joint shape> Dimensions: w = 1000mm, l = 500mm, p = 40m
m, t = 10mm, s = 55mm Material: Low carbon Al killed steel Heating temperature: 1000 ° C <Finishing rolling conditions> Rolling mill: 7-stand continuous rolling mill Speed: 60mpm (at the entry side of finishing rolling mill) Temperature: 1000 ° C (On the entry side of the finishing rolling mill) 1st pass rolling reduction: 40% Finishing plate thickness: 2.5mm Pinch roll pushing force: 0.2kg / mm ^{2 No} plate breakage during rolling, good rolling work It was possible.

[0027]

As described above, according to the present invention, since no special pre-joining is required and joining can be performed by the first stand of the finishing mill, it can be applied to all existing hot rolling processes.
It can greatly contribute to productivity improvement and product quality improvement.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a combination of a leading material, a joint, and a trailing material.

FIG. 2 is a symbol explanatory view of joint dimensions.

FIG. 3 is a perspective view showing a specific example of a joint shape.

FIG. 4 shows a shape of a joint combination portion after joint rolling,
(A) is a top view and (b) is an AA cross-sectional view.

FIG. 5 is a schematic diagram showing an example of equipment arrangement for carrying out the present invention.

FIG. 6 is a view showing an example of an apparatus for adjusting the height position of a joint material.

FIG. 7 is a diagram showing an example of the shape of a roller of a table roller for conveying a rolled material while pressing it after interposing a joint material.

FIG. 8 is a cross-sectional view showing the shape of the cut portion of the rolled material after shear cutting.

FIG. 9 is an explanatory view showing an arrangement position of a normal joining device.

[Explanation of symbols]

 1 Finishing Roller 1st Stand 2 Seat Bar (Preceding Material) 2-1 Preceding Material Rear End 3 Sheet Bar (Rearward Material) 3-1 Trailing Material Tip 4 Table Roller 5 Joining Position 6 Joint 7 Finishing Rolling Machine Group 8 Joint heating furnace 9 Table roller and pinch roll 10, 11 Pinch roller 12 Joint material insertion device 13 Joint material slide 14 Hydraulic cylinder 15 Table roller center part

Claims (1)

[Claims] 1. Between the front and rear end portions of the leading and trailing material of the hot-rolled steel material running on the pass line in front of and behind each other, the upper and lower surfaces of both end portions and both end surfaces An on-line joining method for hot-rolled steel products, characterized in that a joint that covers a part is interposed, and the joint is carried out by rolling while pressing the joint between the trailing end portion of the preceding material and the leading end portion of the following material.