JPH10263608A - Steel joining method for hot continuous rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable rolling joint in a running finish rolling process in a running joint between a preceding steel material and a following steel material for hot continuous rolling, and to finish rolling. Assuming that the quality of the subsequent product is secured stably, in the case of joining on both the upper side and the lower side, the upper and lower sides are properly shared and the lower joining time is shortened, corresponding to high speed rolling Provide a method of joining steel materials that can be performed. SOLUTION: When performing both-side joining of the upper surface side and the lower surface side,
The bonding rate in the thickness direction on the upper surface side is set in the range of 20 to 40%, and the bonding rate in the thickness direction on the lower side is set in the range of 3 to 10%. Or the joint on the upper side and the joint on the lower side,
Each is a local joint and is arranged alternately in the upper and lower directions. In this case, it is effective to make the joining depth of the joining part on the lower surface side shallower than the joining depth on the upper surface side and to reduce the joining ratio in the plate width direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of joining steel materials, which is applied when a preceding steel material and a following steel material are joined while running for continuous hot rolling in, for example, the steel industry.

[0002]

2. Description of the Related Art In the steel industry, for example, there is a step of joining steel materials conveyed continuously back and forth in a hot continuous rolling line. In order to improve the productivity of the hot continuous rolling, There is an increasing demand for so-called running joining, in which joining is performed during the transfer of steel materials. Conventionally, as a running joining device for performing this running joining, for example, as shown in FIG. 5, a traveling body b equipped with a welding device a and a clamping device ka, kb is driven by a driving device (not shown). And the traveling body b is traversed by a driving device e on a track r laid on a gantry d, and the traveling body b is continuously transported back and forth by the transport rollers c.
And the trailing end of the leading steel sa and the leading end of the trailing steel sb are clamped by the clamping devices ka and kb while running in synchronization with the trailing steel sb. There has been proposed a running welding equipment configured to weld a butt portion between an end face and a leading end face of a following steel material during running. (Reference techniques: JP-A-7-1007, JP-A-7-16611)

[0003] If the joint obtained by running joining by this running welding equipment breaks during the finish rolling process, continuous rolling operation becomes impossible and semi-finished product processing is required, which increases costs. Therefore, the joint is required to have sufficient strength to withstand a load (tension) in the finish rolling process. Conventionally, in order to secure a joining portion having such joining strength, the joining portion is formed only on the upper surface side of the steel material 1 as shown in FIG. The joining is performed at 50 to 60% of the sheet thickness x (joining ratio) over a long time, but there are problems such as that the joining time is too long to cope with high-speed rolling and that joining cost is high.

[0004]

DISCLOSURE OF THE INVENTION The present invention is to provide a continuous rolling of a preceding steel material and a following steel material for hot continuous rolling, which stably secures a joint which does not break during a rolling finish rolling process, and finish rolling. Assuming that the quality of the subsequent product is secured stably, in the case of joining on both the upper side and the lower side, the upper and lower sides are properly shared and the lower joining time is shortened, corresponding to high speed rolling It is intended to provide a method of joining steel materials that can be performed.

[0005]

Means for Solving the Problems The first invention of the present invention is:
In a method of joining a leading steel material and a succeeding steel material by a running joining facility for continuous hot rolling, when performing both-side joining of an upper surface side and a lower surface side, the joining ratio in the thickness direction of the upper surface side is 20 to 40%.
And a joining rate in the thickness direction of the lower side within a range of 3 to 10%. The second invention is a method for joining a leading steel material and a succeeding steel material by a running joining facility for continuous hot rolling, in which the upper surface side and the lower surface side are subjected to double-sided joining, the upper surface side joining portion and the lower surface side are joined. A method for joining steel materials for continuous hot rolling, wherein the joining portions are formed as local joining portions, and are arranged alternately up and down. According to a third aspect, in the second aspect, when the upper surface side and the lower surface side are joined to each other, the joining depth of the joining portion on the lower surface side is made shallower than the joining depth on the upper surface side, and the joining in the sheet width direction is performed. This is a method of joining steel materials for hot continuous rolling, characterized by reducing the rate.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the joining time is shortened by double-sided joining on the premise that a joint that does not break during the finish rolling process is ensured stably and the quality of the product after the finish rolling is ensured stably. Thus, it is possible to cope with high-speed rolling. Also, as shown in FIG. 1, the joining portion is formed by a joining portion wo on the upper surface side and a joining portion wu on the lower surface side, and a joining depth do of the joining portion on the upper surface side and a joining depth du of the joining portion on the lower surface side. Is set in an appropriate range, and the overall joining rate in the thickness direction is reduced, whereby the joining cost can be reduced.

[0007] The joining rate in the present invention indicates the ratio of the joining depth do of the joining portion wo on the upper surface side or the joining depth du of the joining portion wu on the lower surface side to the plate thickness x.
The ratio of the joining depth do of the upper joining portion + the joining depth du of the lower joining portion to the plate thickness x is shown.

According to the experiments by the present inventors, when the joints are formed on the upper and lower surfaces of the joint wo on the upper surface and the joint wu on the lower surface of the steel material 1 as shown in FIG. It was found that the overall joining ratio in the plate thickness direction can be reduced as compared with the case of joining, so that the joining time can be shortened and the joining cost can be reduced.

In the case of double-sided bonding, the bonding ratio between the upper surface side and the lower surface side is 20% in the thickness direction on the upper surface side.
If it is less than 30, sufficient bonding strength cannot be secured on the upper surface side. In this case, in order to secure the joining strength, it is necessary to increase the joining ratio in the thickness direction of the lower surface side to 40 to 50%, and the joining cost cannot be sufficiently reduced because the entire joining ratio cannot be reduced. The joining time cannot be reduced.

Further, the joining ratio in the thickness direction on the upper surface side is 40%.
In the case of super, the joint strength on the upper surface side can be secured, but in order to reliably prevent the occurrence of joint failure due to local cooling of the joint and the presence of scale, the joint ratio in the plate thickness direction on the lower surface side should be 3%. % Or more, the overall joining ratio cannot be reduced so much that the joining time and joining cost cannot be sufficiently reduced.

If the joining ratio in the thickness direction of the lower surface is set to 10% or more, expensive joining means such as a laser beam joining device is required, as in the joining of the upper surface, and the cost increases.
Further, the overall joining ratio exceeds 45%, and the effect of shortening the joining time and the effect of reducing the joining cost are reduced.

In consideration of the above, in the first invention,
The bonding ratio in the thickness direction on the lower surface side is 3 to 10%, the bonding ratio in the thickness direction on the upper surface side is 20 to 40%, and the overall bonding ratio is 45.
% To reduce the bonding time and the bonding cost. In this case, the joining ratio in the thickness direction on the upper surface side (b) and the joining ratio in the thickness direction on the lower surface side (a) can be minimized while reliably preventing the occurrence of defective joints. It is preferable to set

On the other hand, in the second invention, FIGS.
As shown in (c), the joint part ra on the upper surface side and the joint part wa on the lower surface side are each a local joint part in the plate width z direction, and are arranged alternately up and down so that all of the upper surface part in the plate width direction are arranged. The bonding time xr and the total bonding length xw on the lower surface side are shortened to shorten the bonding time.

According to a third aspect of the present invention, in the second aspect, the joining depth du × the total joining length xw of the entire joining portion wa on the lower surface side is defined by the joining depth do × the total joining depth ra of the joining portion ra on the upper surface side. It is smaller than the junction length xr.

The joining ratio in the plate width direction on the upper surface side depends on the joining ratio in the plate thickness direction, but at the joining ratio level of the first invention, by setting the joining ratio to about 40 to 70%, The joining time can be reduced while reliably preventing the occurrence of defects. Also, the bonding depth × bonding length on the lower surface side is 1/10 to 5 times the bonding depth × bonding length of the bonding portion on the upper surface side.
The object of the present invention can be achieved with about / 10. By doing so, the joining time is shortened, the joining cost is reduced, the joint strength balance in the plate width z direction and the plate thickness x direction is secured, and the overall strength is stably secured.

Each of the above-mentioned inventions of the present invention can be implemented by a running joint (example) shown in FIGS.
As shown in FIG. 3, the running joining apparatus (example) hot-rolls a heated steel slab 1 with a rough rolling mill 2, temporarily stores the obtained steel material 1 o in a coil box 3, In the case where the steel sheet 1p is manufactured by hot rolling continuously with this finishing mill, the steel material continuously conveyed back and forth by the conveying roller 4 between the coil box 3 and the finishing mill 5 This is a case where the present invention is applied to a running welding facility 6 for welding 1a and 1b during running.

The traveling joint 9 is a traveling body 9 capable of traveling in synchronism with the steel materials 1a and 1b which are continuously conveyed back and forth by a driving roller 10 on a track 11 by a conveying roller 4.
The traveling body is provided with clamping devices 7a and 7b for clamping the leading steel material 1a and the succeeding steel material 1b, a laser welding device 8o for joining the upper surface side, and an arc welding device for joining the lower surface side. 8u is mounted.

A cam plate 12 is provided below the traveling body 9, and the transport roller 4 is moved by the cam plate via a cam lever 13 to the clamping device 7.
a, 7b, laser welding device 8o, arc welding device 8u
The clamp device 7 is retracted to a position where it does not interfere with the
a, 7b clamp the leading steel member 1a and the following steel member 1b,
The laser welding device 8o is driven by the driving device 16o, and the arc welding device 8u is driven by the driving device 16u synchronously in the width direction of the leading steel member 1a and the rear steel member 1b.
The upper surface side and the lower surface side of the butted portion of the a and the rear steel material 1b can be simultaneously joined while running.

In the drawing, 14 is a hydraulic cylinder for retracting and returning the transport roller 4, and 15 is a hydraulic cylinder connected to the clamping devices 7a and 7b.
a, which is used to butt-press the rear steel material 1b, and is operated by a hydraulic pump 20 controlled by an arithmetic unit 17 via an output control unit 19.

The laser welding device 8o for joining the upper surface side and the arc welding device 8u for welding the lower surface side include a traveling distance of the traveling body, a line speed, a plate thickness, a plate width, and rolling conditions set in the arithmetic unit 17 in advance. Conditions such as laser output (current, voltage), bonding speed, etc., the bonding rate that does not cause breakage, and the bonding range (bonding depth,
It is controlled via the control devices 18o and 18u according to the joining start point, the joining distance, the joining end point) and the movement pattern.

Then, while the rear end of the preceding steel material 1a and the front end of the following steel material 1b clamped by the clamping devices 7a and 7b are abutted on each other, the laser welding device 8o and the arc welding device 8u are driven by the driving devices 16o and 16u. While moving synchronously at a predetermined speed in the width direction, a predetermined range on the upper surface side and the lower surface side of the butted portion can be simultaneously bonded at a predetermined bonding rate. In this case, the welding condition may be set and controlled by creating a table without using the arithmetic unit.

The present invention can be carried out using the running joining equipment configured as described above. In addition, the running joining equipment for implementing the present invention is not limited to the above-described running joining equipment example. For example, a joining device (joining means), a clamp structure, a conveying roller, a cam plate, a conveying roller, a retracting / returning structure, and the like that constitute the running joining equipment are changed according to a joining object, rolling conditions, and the like. .

[0023]

【Example】

(Embodiment 1) Using the running joint equipment as shown in FIGS. 3 and 4, the temperature continuously supplied from the coil box 3 is 1000 ° C., the thickness is 25 mm, and the width is 1500 mm. Finishing mill 5
In the previous stage, both surfaces were butt-joined with a laser welding device 8o on the upper surface side and an arc welding device 8u on the lower surface side. Then, in finish rolling, heat was applied at a reduction rate of 35% and a rolling speed of 50m / min. Finish rolling was performed to produce a steel sheet having a thickness of 2 mm. The presence or absence of joint breakage during the finish rolling process was investigated. The results are described below.

[Implementation conditions] Joining conditions Upper surface side (laser welding device) Laser beam output: 45 kw (constant) Joining speed: 10 m / min Joining depth: 8 mm Joining distance z: 1500 mm Lower surface side (arc welding device) Welding current: 30 A (constant), voltage 220 V (constant) Joining speed: 3 m / min Joining depth du: 1 mm Joining distance z: 1500 mm Chemical components (weight%) of leading and trailing steel C: 0.058, Si: 0.016 , Mn: 0.23
0, P: 0.019 S: 0.014, Al: 0.033, Ti: 0.00
1, Fe and others: 99.629

In this example, as shown in FIG. 1, the upper and lower surfaces are continuously welded. In this case, the joining ratio in the thickness direction of the upper surface is 32%, and the thickness of the lower surface is In the example of the present invention in which the joining ratio in the direction is 4% and the joining ratio is satisfied, the overall joining ratio in the thickness direction is 36%, and the joining time is 20 seconds (the entire width on one side is 50%). %, The bonding time is 40 seconds). In the obtained joint, there was no occurrence of joint failure, no breakage of the steel material (steel plate) during the finish rolling process, and no occurrence of defects due to the joint was observed in the steel plate after finish rolling. .

On the other hand, in the example in which the bonding is performed on both surfaces, but the bonding is performed at a bonding rate that does not satisfy the range of the bonding rate sharing rate defined in the present invention, the bonding rate on the upper surface side is set to 1 near the lower limit of the present invention.
When it is set to 8% and the joining ratio on the lower surface side is set to 2.5% near the lower limit of the present invention, occurrence of defective joints is observed in the obtained joints, and during the finish rolling process, Breakage often occurred due to insufficient bonding strength.

Example 2 A steel sheet was manufactured using the same running material as shown in FIGS. 3 and 4 using the same steel material as in Example 1 under the same rolling conditions. In this embodiment, the joints are alternately arranged vertically as shown in FIG. The welding time, the fracture of the joint during the finish rolling process, and the presence or absence of steel sheet defects after the finish rolling were investigated. The results are described below.

[Conditions] Joining conditions Upper surface side (laser joining apparatus) Laser output: 45 kw (constant) Joining speed: 9 m / min Joining depth dr: 9 mm Joining distance xr (set value): 30 mm × 3 Lower side (arc Welding equipment) welding current: 30A (constant), voltage 220V (constant) joining speed: 3m / min joining depth dw: 2mm joining distance xw (set value): 20mm x 4

The upper surface side and the lower surface side are locally joined and arranged alternately in the vertical direction, the joining length with respect to the sheet width z on the upper surface side is 6%, the joining depth with respect to the sheet thickness x is 36%, and the sheet width on the lower surface side. In the embodiment of the present invention in which the joining length with respect to the thickness was set at 5.3% and the joining depth with respect to the plate thickness x was set at 8%, the joining ratio in the plate width direction was 5% larger than in the case of Example 1. , Joining time is 35
Seconds could be further reduced. In the obtained joint, there was no occurrence of joint failure, no breakage of the steel material (steel plate) during the finish rolling process, and no occurrence of defects due to the joint was observed in the steel plate after finish rolling. .

As described above, in the embodiment of the present invention, the joining time is shortened, the occurrence of joint failure is prevented, the joint is broken in the finish rolling process, and the steel sheet defect after the finish rolling is generated. In addition, the joining time can be reduced by 40% as compared with the current single-sided full-width joining, and the joining cost can be reduced.

[0031]

According to the present invention, the bonding time is reduced by double-sided bonding on the premise that a joint that does not break during the finish rolling process is stably ensured and the quality of the product after the finish rolling is stably ensured. Applicable to high speed rolling. In addition, the joining ratio in the thickness direction on the upper surface side and the joining ratio in the thickness direction on the lower surface side are set within an appropriate range, and the overall joining ratio in the thickness direction is reduced to 45% or less, or the joining in the width direction is reduced. By reducing the rate, the joining time can be further reduced, and the joining cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a joint showing an example of an arrangement of joints on an upper surface side and a lower surface side in the present invention.

FIGS. 2A to 2C are vertical cross-sectional conceptual views of joints showing another example of arrangement of joints on the upper surface side and the lower surface side in the present invention.

FIG. 3 is a partial cross-sectional side schematic explanatory view showing an example of an arrangement of a hot continuous rolling facility provided with a running joining facility for carrying out the present invention.

FIG. 4 is a partially enlarged cross-sectional side view schematically showing an example of the structure of the running joint equipment for implementing the present invention.

FIG. 5 is a schematic side view showing an example of a conventional running welding equipment.

FIG. 6 is a conceptual explanatory view of a longitudinal section of a joint showing an example of a conventional joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Billet 1a, 1b Steel material 1p Steel plate 2 Rough rolling mill 3 Coil box 4 Transport roller 5 Finishing rolling mill 6 Running welding equipment 7a, 7b Clamping device 7c Hydraulic cylinder 7o Upper clamp plate 7u Lower clamp plate 8o Laser welding device 8u Arc Welding device 9 Traveling body 10 Drive device 11 Track 12 Cam plate 13 Cam lever 14 Hydraulic cylinder 15 Hydraulic cylinder 16o, 16u Driving device 17 Computing device 18o, 18u Control device 19 Output control device 20 Pump

Claims (3)

[Claims] In a method for joining a leading steel material and a succeeding steel material by a running joining facility for continuous hot rolling, when joining both surfaces of an upper surface side and a lower surface side, a joining ratio in a thickness direction of the upper surface side is reduced. A method for joining steel materials for hot continuous rolling, wherein the joining ratio in the thickness direction of the lower side is within a range of 3 to 10%. 2. A method for joining a leading steel material and a following steel material by a running joining facility for continuous hot rolling, in a case where the upper surface side and the lower surface side are joined on both sides, the joining portion on the upper surface side and the joining on the lower surface side. A method for joining steel materials for hot continuous rolling, wherein the parts are each locally joined and arranged alternately up and down. 3. In a method of joining a leading steel material and a following steel material by a running joining facility for continuous hot rolling, when performing both-side joining of an upper surface side and a lower surface side, a joining depth of a joining portion on a lower surface side is reduced. 3. The method for joining steel materials for hot continuous rolling according to claim 2, wherein the joining depth is made shallower than the joining depth on the upper surface side and the joining ratio in the sheet width direction is reduced.