JP2019181516A - Thickness reducing method of welded joint part of metal strip and welding facility of metal strip - Google Patents

Abstract

To provide a method of improving a plate thickness deviation in a metal strip plate width direction of a welded joint part subjected to thickness reduction processing, in a method of performing thickness reduction processing by drafting the welded joint part between end parts of a precedent metal strip and a succedent metal strip by a pressure roller which is moved in a metal strip plate width direction in a continuous line.SOLUTION: A draft load of a pressure roller x which drafts a welded joint part is changed while the pressure roller x is moved in the metal strip S1, S2 plate width direction and, usually, a draft load of the pressure roller x is gradually reduced. Further preferably, surface temperature of the pressure roller x during movement in the metal strip pate width direction is measured and, based on the roller surface temperature, the draft load of the pressure roller x is controlled.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a process line that continuously produces metal strips such as steel strips, after welding the rear end of the preceding metal strip and the front end of the subsequent metal strip, and then determining the thickness of the weld joint. The present invention relates to a method for reducing the thickness of a welded joint, which is performed in order to approach a material, and a metal strip welding facility used for the method.

  In a process line (continuous line) that continuously produces metal strips such as continuous pickling lines, continuous tandem rolling lines, and continuous annealing lines for steel strips, the rear end of the preceding metal strip and the following metal A welding process that joins the strip tips is essential. Laser welding, flash butt welding, seam welding, etc. are used for welding the metal strip in this welding process, but any welding method can be used for welding joints (welded joints). The thickness is larger than the thickness of the base material, and a step is formed. In such a welded joint having a step, stress concentration is likely to occur, and there is a risk that fracture or the like may occur due to bending deformation or rolling deformation in the process of passing the metal strip. Therefore, it is necessary to reduce this welding step.

  As a method for reducing this welding step, Patent Document 1 (Japanese Patent Application Laid-Open No. 5-69151) discloses a method in which an end portion of a preceding material and a subsequent material serving as a joint portion is pressed by a pair of upper and lower rolls before welding. A method of reducing the thickness of the welded joint by rolling down with a roll and thinning is shown. Patent Document 2 (Japanese Patent Laid-Open No. 2000-197979) discloses a method for reducing the thickness of a stepped portion by a pressure roll made of a pair of upper and lower rolls after seam welding. No. 27934) shows a method of reducing the thickness by pressing down a stepped portion with a pressure roll comprising a pair of upper and lower rolls after laser welding.

JP-A-5-69151 JP 2000-197979 A JP 2013-27934 A

  However, in the method described in Patent Document 1, since the process of reducing the end portions of the preceding material and the succeeding material before welding is performed at room temperature, a predetermined thickness reduction (thinning amount) is ensured. There is a problem that the processing reaction force becomes large and the equipment scale becomes large. Moreover, since the metal band edge portion is processed at room temperature, wrinkles are likely to enter the surface of the pressure roll. When the operation with such a roll containing wrinkles is continued, there is a problem that wrinkles are transferred to the metal band, and in seam welding or the like, sparks are likely to occur in the subsequent welding process.

  On the other hand, the methods described in Patent Documents 2 and 3 use heat input at the time of welding to reduce the weld joint that has been softened at high temperature, so that the reaction force is small and it is difficult for wrinkles to enter the roll. There is. However, as a result of investigations by the present inventors, when the welded joint (stepped portion) is reduced by a pressure roll moving in the width direction of the metal strip by the method described in Patent Documents 2 and 3, the thickness is reduced. It has been found that the thickness of the welded joint after the thickness reduction process is not constant in the plate width direction, and that the thickness gradually decreases from the reduction start point to the reduction end point in the metal strip width direction. As will be described in detail later, it has been found that this cause is due to a temperature change of the welded joint caused by contact heat conduction between the pressure roll and the metal strip. Thus, if a difference occurs in the thickness of the welded joint in the width direction of the plate, it tends to be a hindrance to stable operation, such as causing a meandering or breakage of the metal band in a continuous line.

  Accordingly, an object of the present invention is to solve the above-described problems of the prior art, and in a continuous line, the weld joint between the end portions of the preceding metal strip and the subsequent metal strip is moved in the metal strip width direction. In a method of reducing the thickness by reducing with a pressure roll, a method capable of improving the thickness deviation in the metal strip width direction of the welded joint subjected to thickness reduction and a welding facility suitable for the implementation are provided. There is to do.

The inventors of the present invention have been made as a result of finding out the problems as described above and repeatedly studying them to solve the problems.
[1] In a continuous line, the welded joint between the ends of the preceding metal strip and the subsequent metal strip is reduced by a pressure roll (x) that moves in the width direction of the metal strip. There,
Thickening of welded joints of metal strips, characterized by changing the rolling load of the pressure roll (x) that rolls down the welded joints while the pressure roll (x) moves in the width direction of the metal strip Method.
[2] The metal strip according to [1], wherein the rolling load of the pressure roll (x) is gradually reduced while the pressure roll (x) moves in the width direction of the metal strip. To reduce the thickness of welded joints.

[3] In the thickness reduction method of [1] or [2] above, the surface temperature of the pressure roll (x) moving in the width direction of the metal strip is measured, and the pressure roll (x A method for reducing the thickness of a welded joint of a metal strip, characterized by controlling the rolling load of x).
[4] In the continuous line, equipped with a pressure roll (x) that reduces the thickness of the welded joint between the ends of the preceding metal strip and the trailing metal strip while moving in the width direction of the metal strip. Welding equipment,
A thermometer that measures the surface temperature of the pressure roll (x) that is moving in the width direction of the metal strip, and an optimum reduction load of the pressure roll (x) based on the roll surface temperature measured by the thermometer A metal strip welding facility comprising a calculation control device that calculates and controls a reduction load of a pressure roll (x).

  According to the method of the present invention, in a continuous line, a method of reducing the thickness of a welded joint between the ends of a preceding metal strip and a succeeding metal strip by pressing with a pressure roll moving in the width direction of the metal strip. The thickness deviation in the metal strip width direction of the welded joint subjected to the thickness reduction can be appropriately improved. For this reason, it is possible to prevent plate troubles such as meandering and breaking of the metal strip due to the thickness deviation in the metal strip width direction of the welded joint subjected to thickness reduction, and stable operation of a continuous line is possible. Moreover, according to the welding equipment of this invention, this invention method which has such an effect can be implemented appropriately.

The front view which shows typically one Embodiment of the welding equipment (seam welding apparatus) of the metal strip used for implementation of this invention Side view schematically showing the welding equipment (seam welding apparatus) of FIG. In the examples, a graph showing the thickness distribution of the welded joint and its vicinity where thickness reduction processing was performed by the conventional method In an example, a graph showing the thickness distribution of a welded joint and its vicinity subjected to thickness reduction processing by the method of the present invention

  In a continuous line, by rolling down the welded joint between the ends of the preceding metal strip and the subsequent metal strip with a pressure roll that moves in the width direction of the metal strip while in a high temperature state due to heat input during welding. In the case of thickness reduction processing, in the conventional method as described in Patent Documents 2 and 3, the pressure roll moving in the metal strip width direction reduces the weld joint with a constant reduction load, and this thickness reduction processing is doing. However, the thickness of the welded joint that has been reduced in thickness by such a conventional method is not constant in the metal strip width direction, and the rolling ends from one plate width end that becomes the rolling start position (= welding start position). It was found that the width gradually decreased toward the other end of the plate width, which is the position (= welding end position). It has been found that this cause is due to the temperature change of the weld joint caused by the contact heat conduction between the pressure roll and the metal strip.

  That is, the surface temperature of the pressure roll is low at the reduction start position, and the amount of heat taken by the pressure roll from the weld joint is large, so that the temperature of the weld joint becomes low and hard. On the other hand, when the welded joint is reduced in thickness in the plate width direction with the pressure roll, the surface temperature of the pressure roll gradually increases, and the amount of heat taken by the pressure roll from the welded joint decreases accordingly. Therefore, the temperature of the welded joint becomes high and soft. This degree increases as it approaches the reduction end position. For this reason, when the welded joint is reduced with the same reduction load in the plate width direction, the amount of reduction in thickness gradually increases from the reduction start side to the reduction end side, and the thickness reduction (thickening amount) of the welded joint in the plate width direction. It was found that there was a difference in This phenomenon becomes more prominent as the thickness reduction by the pressure roll is increased in order to reduce a large joint step difference. And when the difference in the thickness of the welded joint occurs in the plate width direction or the amount of reduction on the end of the reduction is excessive, it causes the occurrence of meandering and breaking during rolling in the continuous tandem rolling line, In addition, even in the continuous pickling line and continuous annealing line, the length changes according to the difference in the amount of reduction in the plate width direction of the welded part, which causes the joint part to be deformed into a dogleg shape, resulting in the occurrence of meandering It became a cause, and it turned out that all became the obstruction factors of stable operation.

  Therefore, in the present invention, the reduction load of the pressure roll x that reduces the weld joint is changed while the pressure roll x moves in the metal strip width direction, and the thickness reduction amount of the weld joint in the plate width direction ( This is to prevent a difference in the amount of thinning). In the basic mode of changing the rolling load of the pressure roll x, for the reason described above, it is usual to gradually reduce the rolling load of the pressure roll x while the pressure roll x moves in the metal strip width direction. . In this case, the reduction load of the pressure roll x may be gradually decreased from the reduction start position to the reduction end position, or may be gradually reduced in stages. Further, in the metal strip width direction, the starting point position for gradually reducing the rolling load of the pressing roll x may be gradually decreased from the pressing start position of the pressing roll x. You may make it reduce gradually from the position which advanced a fixed distance in the width direction. On the other hand, the end point position for gradually reducing the rolling load of the pressure roll x may be up to the rolling end position of the pressure roll x, or may be a position before reaching the rolling end position.

  For the reasons described above, the ease of thickness reduction depending on the temperature of the welded joint can be estimated from the surface temperature of the pressure roll x. Therefore, in carrying out the present invention, a metal strip is used. It is preferable to measure the surface temperature of the pressure roll x that is moving in the width direction, and to control the rolling load of the pressure roll x based on the measured roll surface temperature. In performing such control, the optimum value of the rolling load varies depending on the material and thickness of the metal strip in addition to the roll surface temperature, so at least the material and thickness of the metal strip to be joined (material between the metal strips)・ Including the combination pattern of plate thickness) and the pressure roll surface temperature, the relationship between the rolling load and the thickness of the welded joint after thickness reduction is obtained in advance, and the measured The optimum rolling load of the pressure roll x corresponding to the pressure roll surface temperature is obtained, and the thickness of the welded joint that has been reduced in thickness is reduced as much as possible in the metal strip width direction. It is preferable to control the rolling load.

1 and 2 schematically show an embodiment of a metal band welding facility (seam welding apparatus) used for carrying out the present invention. FIG. 1 is a front view, and FIG. 2 is a side view. It is.
This welding equipment includes a carriage frame 1 provided so as to be horizontally movable in a direction perpendicular to the metal band passing plate direction, a welding electrode w composed of a pair of upper and lower electrode wheels 2a and 2b held by the carriage frame 1, Similarly, a pressure roll x consisting of a pair of upper and lower rolls 3a and 3b held by the carriage frame 1 and an apparatus installed on the entry side and the exit side of the apparatus in the direction of the metal band to fix the metal band during welding joining. It is composed of clamp devices 4A and 4B.

The carriage frame 1 is U-shaped as a whole and includes a support roller 6 at the bottom, and the support roller 6 causes a direction on the base 5 to be orthogonal to the metal band passing plate direction (metal band plate width direction). It can be moved horizontally. Reference numeral 7 denotes a driving device (cylinder device or the like) for moving the carriage frame 1 on the base 5.
The upper electrode wheel 2a constituting the welding electrode w is connected via the electrode wheel pressing device 8a, and the lower electrode wheel 2b is connected via the electrode wheel pressing device 8b to the upper and lower portions of the carriage frame 1, respectively. Is supported rotatably. The electrode rings 2a and 2b constituting the welding electrode w are welded to the overlapping portions of the metal bands while being pressed against the metal bands by the electrode wheel pressing devices 8a and 8b with the overlapping portions of the metal bands to be welded joined. Join.

The pressure roll x is disposed adjacent to the rear side of the welding electrode w (electrode wheels 2a, 2b) in the welding progress direction, and is a weld joint in a high temperature state immediately after being formed by welding with the welding electrode w. The thickness is reduced by rolling down with a pair of upper and lower rolls 3a and 3b. The upper roll 3a constituting the pressure roll x is provided via a pressure roll pressing device 9a, and the lower roll 3b is provided via a pressure roll pressing device 9b. It is rotatably supported on the side part.
The electrode wheel pressing devices 8a and 8b and the pressure roll pressing devices 9a and 9b are each composed of a hydraulic cylinder or the like, the main body of which is fixed to the carriage frame 1, and the movable portion (for example, the operating rod of the hydraulic cylinder) is electroded. The wheels 2a and 2b and the rolls 3a and 3b are rotatably supported.

Thermometers 10a and 10b for measuring the surface temperatures of the rolls 3a and 3b constituting the pressure roll x are provided on the carriage frame 1. The thermometers 10a and 10b may be either a non-contact type or a contact type. In the present embodiment, the thermometers are constituted by non-contact type thermometers. In addition, as this thermometer, you may provide the thermometer 10 which measures the surface temperature of only one roll of roll 3a, 3b.
Reference numeral 11 denotes an arithmetic control device for calculating and controlling the optimum rolling load of the pressure roll x based on the surface temperatures of the rolls 3a and 3b measured by the thermometers 10a and 10b.
The clamp devices 4A and 4B installed on the entry side and the exit side of the device are a support frame 12 and a pair of upper and lower clamp members 13a and 13b supported by the support frame 12 via pressing cylinder devices 14a and 14b. It has. Each of the clamp devices 4A and 4B drives the pressing cylinder devices 14a and 14b and clamps both metal bands with a pair of upper and lower clamp members 13a and 13b when the ends of the two metal bands are welded together. , Fix the position.

  When joining the end portions of the preceding metal strip S1 and the succeeding metal strip S2 with this seam welding apparatus, first, the end portions of the metal strips S1 and S2 are overlapped, and in this state, the entrance side and the exit side are overlapped. The clamps 4A and 4B clamp the metal bands S1 and S2 to fix the positions. Subsequently, the carriage 7 is moved in the welding direction (metal strip width direction) on the base 5 by the driving device 7, so that the metal strip is welded by the welding electrodes w (electrode wheels 2 a and 2 b) supported by the carriage frame 1. The overlapped portion of the end portions of S1 and S2 is welded in the metal strip width direction, and a welded joint portion in a high-temperature state immediately after welding with the pressure roll x (rolls 3a and 3b) supported by the carriage frame 1 as well. Reduce the thickness by rolling down. That is, in the metal strip width direction, welding joining by the welding electrode w and reduction (thickening processing) of the welding joint immediately after welding by the pressure roll x are performed.

  Here, as described above, the surface temperature of the pressure roll x is low at the reduction start position, and the amount of heat taken by the pressure roll x from the weld joint is large, so that the temperature of the weld joint becomes low and hard. . On the other hand, when the welded joint is successively reduced in thickness in the sheet width direction by the pressure roll x, the surface temperature of the pressure roll x gradually increases, and the amount of heat taken by the pressure roll x from the welded joint accordingly. Therefore, the temperature of the welded joint becomes high and soft. Therefore, when the welded joint is reduced with the same reduction load in the plate width direction as in the prior art, the amount of thickness reduction gradually increases from the reduction start side to the reduction end side, and the thickness reduction of the weld joint in the plate width direction ( There will be a difference in the amount of thinning).

  On the other hand, in the present invention, the welding load in the plate width direction is reduced by gradually reducing the rolling load of the pressure roll x that rolls down the weld joint while the pressure roll x moves in the metal strip width direction. The difference in thickness reduction (thickness reduction) is made to reduce the thickness deviation (thickness distribution) of the weld joint in the plate width direction, but it depends on the temperature of the weld joint. Since the ease of thickness reduction can be estimated from the surface temperature of the pressure roll x, in this embodiment, the surface temperature of the pressure roll x is measured by the thermometers 10a and 10b, and this measurement is performed. Based on the roll surface temperature, an optimum reduction load of the pressure roll x is obtained, and the reduction load of the pressure roll x is controlled. The measurement of the surface temperature of the pressure roll x may be performed for only one of the rolls 3a and 3b, but the surface temperature of the rolls 3a and 3b is measured by the thermometers 10a and 10b as in the present embodiment. In the case of measurement, for example, an average value of the surface temperatures of the rolls 3a and 3b within a predetermined time pitch is obtained, and this is set as the roll surface temperature. Here, since the optimum value of the rolling load varies depending on the material and thickness of the metal strip in addition to the roll surface temperature, at least the material and thickness of the metal strip to be joined (the combination pattern of the materials and thickness of the metal strips) And the relationship between the reduction load and the thickness of the welded joint after the thickness reduction processing corresponding to the pressure roll surface temperature is obtained in advance and stored in the arithmetic and control unit 11. Then, in this arithmetic and control unit 11, the optimum rolling load is calculated from the material / sheet thickness information of the metal strip to be actually welded and the measured surface temperature of the pressure roll x, and the pressurization load is calculated based on the calculation output result. By controlling the roll pressing devices 9a and 9b, the rolling load of the pressure roll x is controlled. This makes it possible to reduce the thickness deviation (plate thickness distribution) of the welded joint in the metal strip width direction.

  Further, as shown in FIG. 1, the welding equipment of the present invention reduces the welding joint between the ends of the preceding metal strip and the succeeding metal strip while moving in the width direction of the metal strip in a continuous line. A thermometer 10 (10a, 10b) for measuring the surface temperature of the pressure roll x moving in the width direction of the metal strip, and a thermometer 10 (10a, 10b). The optimal control load of the pressure roll x is calculated on the basis of the roll surface temperature measured in step 1, and the calculation control device 11 for controlling the reduction load of the pressure roll x is provided. The calculation control device 11 performs the calculation and control as described above. For this reason, at least the material and plate thickness of the metal bands to be joined (including the combination pattern of the material and plate thickness of the metal bands) and A storage unit that stores the relationship between the reduction load and the thickness of the welded joint after thickness reduction corresponding to the pressure roll surface temperature, and the welded joint after the reduction load and thickness reduction stored in the storage unit Based on the relationship with the thickness of the metal, the calculation unit that calculates the optimum reduction load from the information of the material and thickness of the metal strip actually welded and the measured surface temperature of the pressure roll x, and the calculation output from this calculation unit Based on the result, the pressure roll pressing devices 9a and 9b are controlled to control a pressing load of the pressure roll x.

  There is no particular limitation on the type of continuous line to which the present invention is applied, for example, a continuous pickling line for steel strips, a continuous tandem rolling line, a continuous annealing line, or a continuous treatment line for metal strips other than steel strips, etc. It can be applied to various continuous lines. Further, the welding machine used in the continuous line is not limited to the seam welding machine as shown in FIG. 1, and any system such as a laser welding machine or a flash butt welding machine can be applied.

In a steel strip continuous pickling line equipped with the welding equipment shown in FIG. 1 on the inlet side, the steel strip was subjected to a welding test, and the welded joint portion subjected to thickness reduction processing with a pressure roll was investigated. The test material is a high-tensile steel plate containing C: 0.08%, Si: 0.03%, Mn: 2.0% by mass%, having a plate thickness of 4.0 mm and a plate width of 1000 mm.
In this welding test, welding was performed after removing the scale formed on the surface of the end of the steel strip to be joined with a grinding brush. The welding conditions are such that the overlap margin of the rear end of the preceding steel strip and the front end of the subsequent steel strip is 4 mm, a welding electrode composed of an electrode ring having an outer diameter of 270 mm and a width of 20 mm is used, the electrode wheel pressure is 55 kN, and the current is The density was 400 A / mm ² and the welding speed was 5 mpm.

  A roll with an outer diameter of 220 mm and a width of 22 mm is used as the pressure roll, and the thickness reduction processing of the welded joint by the pressure roll is performed by the conventional method (conventional example) and the method of the present invention (invention example), respectively. did. In the conventional method, the rolling load of the pressure roll is set to a constant 50 kN. On the other hand, in the method of the present invention, the surface temperature of the pressure roll is measured with a thermometer (the surface temperature of the rolls 3a and 3b is measured with the thermometers 10a and 10b, and the surface of the rolls 3a and 3b within a predetermined time pitch. Based on this measurement result, the rolling load of the pressure roll was controlled to gradually decrease while the pressure roll moved in the metal strip width direction. Specifically, the rolling load was gradually decreased from 50 kN at the pressing start point at a substantially constant rate, and the rolling load at the pressing end point was set to 40 kN. This reduction load is the result of the pre-bonding experiment conducted by changing only the set reduction load without changing the reduction load in the plate width direction in advance. Determined from the relationship of values.

3 and 4 show the measurement results of the welded joint thickness-reduced by the respective methods and the plate thickness in the vicinity thereof. FIG. 3 shows the conventional method, and FIG. 4 shows the method according to the present invention.
The plate thickness of the welded joint was measured at a measurement pitch of 1 mm in the longitudinal direction of the steel strip around the welded joint at five locations in the plate width direction of the steel strip. This plate thickness measurement was performed using a contact displacement meter that sandwiched the upper and lower sides of the steel strip. Here, among the measurement positions A to E shown in FIG. 3 and FIG. 4, the position A is a position 5 mm from one plate width end that becomes a welding start point, and the position B is one plate width end that becomes a welding start point. From 250 mm position, position C is the center position of the plate width, position D is 250 mm position from the other plate width end which is the welding end point, position E is 5 mm position from the other plate width end which is the welding end point, The plate thickness was measured at each position in the plate width direction.

  According to FIG. 3 and FIG. 4, the thickness of the welded joint is larger than the thickness of the base steel strip by either method. The thickness deviation is within 20% from the thickness of 4.0 mm. Here, looking at the plate thickness change in the plate width direction, in the case of the conventional method of FIG. 3, the plate thickness of the weld joint gradually decreases from the position A near the welding start point to the position E near the welding end point. It can be seen that a large thickness deviation of about 0.5 mm at maximum occurs in the plate width direction. This is because, as the pressure roll progresses in the plate width direction, the roll surface temperature rises due to heat input from the steel strip, and as a result, the amount of heat removed from the steel strip by the pressure roll decreases, so that This is because the part temperature increases from position A toward position E. On the other hand, in the case of the method of the present invention shown in FIG. 4, welding control is performed so that the rolling load of the pressure roll gradually decreases according to the surface temperature of the pressure roll, compared with the conventional method shown in FIG. 3. It can be seen that the thickness deviation in the plate width direction of the portion is remarkably reduced.

Next, in order to confirm the effect of reducing operational troubles by improving the thickness deviation in the plate width direction of the weld joint, in the continuous pickling line of the steel strip provided with the welding apparatus shown in FIG. The thickness of the welded joint was reduced by applying the conventional method and the method of the present invention, and the occurrence rate of meandering troubles in the pickling line was examined. The meandering trouble occurrence rate was obtained by operating each method for one month, and dividing the number of meandering troubles occurring near the weld joint at that time by the number of coils produced in that period.
Table 1 shows the meandering trouble occurrence rate when the conventional method and the method of the present invention are applied. According to this, by improving the plate thickness deviation in the plate width direction of the welded joint by the method of the present invention, the incidence of meandering trouble is reduced to 1/6, confirming the effectiveness of the present invention. be able to.

x Pressure roll w Welding electrode 1 Carriage frame 2a, 2b Electrode wheel 3a, 3b Roll 4A, 4B Clamp device 5 Base 6 Support roller 7 Drive device 8a, 8b Electrode wheel pressing device 9a, 9b Pressure roll pressing device 10a, 10b Thermometer 11 Calculation control device 12 Support frame 13a, 13b Clamp member 14a, 14b Cylinder device for pressing S1, S2 Metal strip

Claims (4)

In a continuous line, a method of reducing the thickness of a welded joint between end portions of a preceding metal strip and a subsequent metal strip by reducing with a pressure roll (x) moving in the metal strip width direction,
Thickening of welded joints of metal strips, characterized by changing the rolling load of the pressure roll (x) that rolls down the welded joints while the pressure roll (x) moves in the width direction of the metal strip Method.   The thickness reduction of the welded joint of the metal strip according to claim 1, wherein the rolling load of the pressure roll (x) is gradually reduced while the pressure roll (x) moves in the width direction of the metal strip. Method.   The surface temperature of the pressure roll (x) moving in the width direction of the metal strip is measured, and the rolling load of the pressure roll (x) is controlled based on the roll surface temperature. 2) Thickening method for welded joints of metal strips. A welding facility equipped with a pressure roll (x) that reduces the thickness of the welded joint between the ends of the preceding metal strip and the trailing metal strip while moving in the width direction of the metal strip in a continuous line. There,
A thermometer that measures the surface temperature of the pressure roll (x) that is moving in the width direction of the metal strip, and an optimum reduction load of the pressure roll (x) based on the roll surface temperature measured by the thermometer A metal strip welding facility comprising a calculation control device that calculates and controls a reduction load of a pressure roll (x).

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