PLATE CROSSBOW CORRECTION DEVICE AND PLATE CROSSBOW CORRECTION METHOD

Each of the moving blocks of the plate crossbow correction device includes distance sensors and electromagnets, and plate crossbow is corrected by adjusting electromagnetic force by the electromagnets in accordance with distances to strips. The moving blocks are movable in the horizontal direction and ratios of moving distances of the moving blocks are adjusted to be constant when seen from a central position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plate crossbow correction device and a plate crossbow correction method.

2. Description of the Related Art

A hot-dip galvanizing line is a facility for plating successive steel plates (hereinafter referred to as “strips”) with molten metal. A hot-dip galvanizing line is provided with a plate crossbow correction device. In this respect, a plate crossbow correction device is also referred to as a damping device.

Here, explanations will be made about steps for plating molten metal to the strips in the hot-dip galvanizing line shown inFIG. 16andFIG. 17.

As shown inFIG. 16andFIG. 17, in a hot-dip galvanizing line10, strips2are successively infiltrated into molten metal (molten plating bath)1and by winding the strips2around a sink roll3disposed in the molten metal1, the running direction of the strips2is changed to an upward direction. After making in-bath rolls (support rolls)4a4bcontact both surfaces of the strips2(front surfaces and back surfaces of the strips) running in an upward direction, the strips2are pulled out from the molten metal1. Air is sprayed from a wiping nozzle5towards both surfaces of the strips2which have been pulled out and are running in the upward direction to remove excess molten metal. A plate crossbow correction device6is disposed upward of the wiping nozzle5and the strips2run upward upon passing the plate crossbow correction device6.

The plate crossbow correction device6suppresses vibration of the strips2by applying electromagnetic force (suction force) towards the strips2and corrects crossbow of the strips2in a contactless manner. Details of the plate crossbow correction device6will be described later.

Here, explanations will now be made about crossbow occurring in strips2and steps for correction the crossbow in such a hot-dip galvanizing line10.

When the strips2are wound around the sink roll3, C crossbow (plastic crossbow), which is crossbow deformation in a plate width direction, occurs in the strips2. Therefore, the in-bath rolls4a,4bare made to contact both surfaces of the strips2in which the C crossbow has occurred for correcting the C crossbow. Further, C crossbow is corrected by the plate crossbow correction device6by applying electromagnetic force to the strips2.

By correcting C crossbow in this manner, the distance of the wiping nozzle5and the strips2will become substantially identical at respective positions in the plate width direction (horizontal direction) of the strips2and the removal amount of molten metal by the wiping nozzle5will become substantially identical at respective positions in the plate width direction. Thus, the amount of plating adhering to the strips2can be made uniform.

The plate crossbow correction device6includes a correction mechanism6F on the front surface side disposed to be apart from the front surface of a strip2and a correction mechanism6B on the back surface side disposed to be apart from the back surface of the strip2.

The correction mechanism6F on the front surface side comprises a plurality of (in this example, three) electromagnets M aligned in the plate width direction and a plurality of (in this example, three) distance sensors S aligned in the plate width direction. The distance sensors S are disposed at upward positions of the electromagnets M. Similarly to the correction mechanism6F on the front surface side, the correction mechanism6B on the back surface side is also provided with a plurality of (in this example, three) electromagnets M and a plurality of (in this example, three) distance sensors S.

The electromagnets M provided in the correction mechanism6F on the front surface side and the electromagnets M provided in the correction mechanism6B on the back surface side are respectively disposed to oppose each other with the strips2being interposed between.

The distance sensors S detect distances between themselves and the strips2. A control device (not shown) controls current values supplied to the electromagnets M such that the distances detected by the distance sensors S become a set distance to thereby adjust electromagnetic force of the electromagnets M applied to the strips2. With this arrangement, crossbow of the strips2is corrected in a contactless manner and vibration of the strips2is suppressed.

Now, it might happen that the strips travel while meandering. Therefore, in the technology of Patent Literature 1 (Japanese Utility Model Application Laid-Open Publication No. H 5-30148), the plate crossbow correction device (correction mechanism) is controlled to move in a plate width direction (horizontal direction) to follow the meandering.

Namely, in the technology of Patent Literature 1, plate width edge positions, which are positions of ends in the plate width direction of the strips, are detected and the entire plate crossbow correction device is controlled to move in the plate width direction (horizontal direction) as a whole in accordance with the detected plate width edge positions.

Further, the strips might not only meander but also their plate widths might change. Therefore, in the technology of Patent Literature 2 (Japanese Patent Application Laid-Open Publication No. 2001-106405), plate width edge positions on both ends which are both end positions in the plate width direction of the strips are detected, and in accordance with the detected plate width edge positions on both ends, one pair of electromagnets disposed on one end side (for instance, the right end side) and another pair of electromagnets disposed on the other end side (for instance, the left end side) from among electromagnets disposed in the plate crossbow correction device (correction mechanism) are controlled and independently moved in the plate width direction (horizontal direction) in accordance with the detected plate width edge positions. In this respect, a pair of electromagnets indicate a magnet disposed on the front surface side of a strip and a magnet disposed on the back surface side opposing the magnet on the front surface side.

In the technology shown in Patent Literature 2, positions of disposing electromagnets which are disposed at positions other than those at both ends in the plate width direction are fixed and are not moved in the plate width direction (horizontal direction).

In this manner, in the technology shown in Patent Literature 2, a pair of electromagnets disposed on one end side and a pair of electromagnets disposed on the other end side are controlled and independently moved in the plate width direction (horizontal direction) in accordance with the plate width edge positions so that it is possible to suitably correct C crossbow of the strips even though the strips meander or their plate width change.

Now, according to the technology shown in Patent Literature 1, while it is possible to perform plate crossbow correction operations even though the strips meander, it is not possible to suitably correct plate crossbow when plate widths of the strips change.

Further, according to the technology shown in Patent Literature 2, correction operations of plate crossbow are performed even though the stripes meander or plate widths of the strips change.

However, according to the technology shown in Patent Literature 2, positions of disposing electromagnets are fixed and not moved in the plate width direction in case of electromagnets disposed at positions other than the both ends in the plate width direction so that intervals of disposing a plurality of electromagnets aligned in the plate width direction become inappropriate and the crossbow of the strips might become large.

Further, as shown in Patent Literature 2, even when the electromagnets disposed on both end sides (one end side and the other end side) are controlled to be moved in the plate width direction (horizontal direction) in accordance with the plate width edge positions, the crossbow of the strips might become large at both end portions when the electromagnets at both end sides are not correctly opposing the end portions of the strips.

This situation will be explained with reference toFIG. 18andFIG. 19. In this respect, inFIG. 18andFIG. 19, x indicates the plate width direction and z indicates a direction from the front surface side towards the back surface side of a strip.

FIG. 18shows a crossbowed state of a strip at a position of a distance sensor disposed in the plate crossbow correction device, wherein the horizontal axis shows the plate width direction position while the vertical axis shows the plate shape (amount of crossbow). The solid line inFIG. 18shows a crossbowed state of a strip after crossbow correction and the dotted line inFIG. 18shows a crossbowed state of a strip when no crossbow correction has been performed.

FIG. 19shows a crossbowed state of a strip at a position of a wiping nozzle disposed in the plate crossbow correction device, wherein the horizontal axis shows the plate width direction position while the vertical axis shows the plate shape (amount of crossbow). The solid line inFIG. 19shows a crossbowed state of a strip after crossbow correction and the dotted line inFIG. 19shows a crossbowed state of a strip when no crossbow correction has been performed.

As shown by the solid lines inFIG. 18andFIG. 19, it can be understood that the crossbow at both end portions of the strip are large even after performing crossbow correction using electromagnets when the electromagnets on both end sides are not correctly opposing end portions of the strip.

In view of the above prior art, the present invention aims to provide a plate crossbow correction device and a plate crossbow correction method capable of reliably reducing crossbow at positions in the plate width direction of the strips including both end portions of the strips even when strips meander or their plate widths change.

SUMMARY OF THE INVENTION

The plate crossbow correction device according to the first invention of the present application for solving the above subject is a plate crossbow correction device including:

a correction mechanism on a front surface side disposed on a front surface side of a conveyed steel plate which adjusts electromagnetic force applied to the steel plate in accordance with a distance to the steel plate and corrects crossbow of the steel plate, and

a correction mechanism on a back surface side disposed on a back surface side of the conveyed steel plate which adjusts electromagnetic force applied to the steel plate in accordance with a distance to the steel plate and corrects crossbow of the steel plate,

wherein the correction mechanism on the front surface side and the correction mechanism on the back surface side respectively comprise

a plurality of moving blocks comprised with distance sensors detecting a distance to the steel plate and electromagnets applying electromagnetic force to the steel plate,

a guide structure supporting the plurality of blocks to be movable along a plate width direction of the steel plate, and

a moving structure moving a moving block close to an end portion of the steel plate from among the plurality of moving blocks along the guide structure and moving the remaining blocks along the guide structure following the moving block close to the end portion of the steel plate.

The plate crossbow correction device according to the second invention of the present invention application is characterized in that

in the first invention,

the moving mechanism includes a servomotor and a rack and pinion mechanism transmitting driving force of the servomotor to the plurality of moving blocks and moving the plurality of moving blocks.

The plate crossbow correction device according to the third invention of the present invention application is characterized in that

in the second invention,

the rack and pinion mechanism is arranged in that the gear ratio is determined such that moving distances each of the moving blocks move when seen from a central position of the plate crossbow correction device become a distance which is in accordance with a preliminarily determined stroke ratio.

The plate crossbow correction device according to the fourth invention of the present invention application is characterized in that

any one of the first to third inventions further comprises

a plate edge sensor detecting plate width edge positions which are positions at ends in the plate width direction of the steel plate, and

a control unit controlling moving operations of the moving mechanism such that a moving block close to an end portion of the steel plates from among the plurality of moving blocks opposes the plate width edge position.

The plate crossbow correction device according to the fifth invention of the present invention application is characterized in that it further includes

an overall moving mechanism on the front surface side moving the correction mechanism on the front surface side of any one of the first to fourth inventions along the plate width direction of the steel plate, and

an overall moving mechanism on the back surface side moving the correction mechanism on the back surface side of any one of the first to fourth inventions along the plate width direction of the steel plate.

A plate crossbow correction method according to the sixth invention is a plate crossbow correction method by a plate crossbow correction device,

wherein a correction mechanism on a front surface side disposed on a front surface side of a conveyed steel plate which adjusts electromagnetic force applied to the steel plate in accordance with a distance to the steel plate and corrects crossbow of the steel plate, and

a correction mechanism on a back surface side disposed on a back surface side of the conveyed steel plate which adjusts electromagnetic force applied to the steel plate in accordance with a distance to the steel plate and corrects crossbow of the steel plate, respectively include

a plurality of moving blocks comprised with distance sensors detecting a distance to the steel plate and electromagnets applying electromagnetic force to the steel plate, and

a guide structure supporting the plurality of blocks to be movable along a plate width direction of the steel plate,

wherein a moving block close to an end portion of the steel plate from among the plurality of moving blocks is moved along the guide structure and the remaining moving blocks are moved along the guide structure following movements of the moving block close to the end portion of the steel plate.

The plate crossbow correction method according to the seventh invention is characterized in that

in the sixth invention,

the plurality of moving blocks are moved such that moving distances each of the moving blocks move when seen from a central position of the plate crossbow correction device become a distance which is in accordance with a preliminarily determined stroke ratio.

The plate crossbow correction method according to the eighth invention is characterized in that

in the sixth or seventh invention,

plate width edge positions which are positions at ends in the plate width direction of the steel plate are detected, and

a moving block close to an end portion of the steel plate from among the plurality of moving blocks is moved to a position opposing the plate width edge position.

According to the present invention, since the remaining moving blocks are moved following movements of the moving blocks close to the end portions of the steel plates, it is possible to reliable reduce crossbow of steel plates even when steel plates meander or their plate widths change.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be explained in details based on examples thereof.

First Embodiment

A hot-dip galvanizing line10acomprising a plate crossbow correction device100according to the first embodiment of the present invention will be explained with reference toFIG. 1which is a front view andFIG. 2which is a side view.

In the hot-dip galvanizing line10a, strips2successively infiltrated into molten metal1are wound around a sink roll3and the running direction is changed into an upward direction, similarly to the hot-dip galvanizing line10shown inFIG. 16andFIG. 17. After making in-bath rolls4a4bcontact both surfaces of the strips2, the strips2are pulled out from the molten metal1, and air is sprayed from a wiping nozzle5towards both surfaces of the strips2to remove excess molten metal. A plate crossbow correction device100according to the present embodiment is disposed upward of the wiping nozzle5, and the strips2run upward upon passing the plate crossbow correction device100.

Explaining the outline of the plate crossbow correction device100, the plate crossbow correction device100includes a correction mechanism100F on the front surface side disposed to be apart from the front surface of a strip2and a correction mechanism100B on the back surface side disposed to be apart from the back surface of the strip2.

The correction mechanism100F on the front surface side comprises a plurality of (in this example, four) electromagnets M aligned in the plate width direction and a plurality of (in this example, four) distance sensors S aligned in the plate width direction. Similarly to the correction mechanism100F on the front surface side, the correction mechanism100B on the back surface side also comprises a plurality of (in this example, four) electromagnets M aligned in the plate width direction and a plurality of (in this example, four) distance sensors S aligned in the plate width direction. Moreover, the electromagnets M provided in the correction mechanism100F on the front surface side and the electromagnets M provided in the correction mechanism100B on the back surface side are respectively disposed to oppose each other with the strips2being interposed between.

Namely, the plate crossbow correction device100comprises four pairs of electromagnets M. While details will be explained later, the four pairs of electromagnets M are arranged to move in the plate width direction (horizontal direction) of the strips2in accordance with meanderings or changes in plate widths of the strips2in order to suitably correct crossbowing of the strips2.

In this respect, when the distance sensors S on the front surface side and the distance sensors S on the back surface side perform measurement at identical positions in the plate width direction, it is also possible to omit either ones on one side of the distance sensors S on the front surface side and the distance sensors S on the back surface side.

A plate edge sensor20is disposed at an upward position of the plate crossbow correction device100. The plate edge sensor20detects plate edge positions which are positions on one end (right end in the example ofFIG. 1) in the plate width direction of the strips2.

As it will be described later, a control device30controls positions in the plate width direction of the four pairs of electromagnets M of the plate crossbow correction device100in accordance with plate width edge positions detected by the plate edge sensor20.

Next, details of the plate crossbow correction device100will be explained.

FIG. 3is a front view of the correction mechanism100F on the front side in a widened state seen from the strip side,FIG. 4is a front view of the correction mechanism100F on the front side in a narrowed state seen from the strip side,FIG. 5is a sectional view including an A-A section ofFIG. 3, andFIG. 6is a sectional view including a B-B section ofFIG. 3. In this respect, for easy understanding, components which are not illustrated inFIG. 3are shown inFIG. 5andFIG. 6.

In this respect, since machine configurations of the correction mechanism100F on the front side and the correction mechanism100B on the back side are identical, explanations will be made of the detailed configuration of the correction mechanism100F on the front side only while explanations of the detailed configuration of the correction mechanism100B on the back side will be omitted.

As shown inFIG. 3toFIG. 6, a frame102extending in the plate width direction (horizontal direction) of the strips2is fixedly installed at a support beam101.

The frame102is provided with four moving blocks110-1,110-2,110-3and110-4aligned in the horizontal direction. While details will be explained later, the moving blocks110-1to110-4are provided to be movable in the horizontal direction along the frame102. In this respect, reference numeral110is used when the four moving blocks110-1to110-4are to be collectively referred to.

Each moving block110is provided with an electromagnet M and a distance sensor S of eddy current type. Namely, the electromagnet M is provided on a lower side of a support pole111of the moving block110and the distance sensor S is provided on an upper side of the support pole111(seeFIG. 6). Namely, the distance sensor S is disposed at an upward position of the electromagnet M.

A lower support plate112is fixed to an upper end portion of the support pole111and an upper support plate113is disposed at an upward position of the lower support plate112. The upper support plate113is attached to the lower support plate112via gears (pinions or the like) to be described later.

A linear rail103extending in the horizontal direction is provided on a lower surface of the frame102. A linear slider104is attached on an upper surface of the upper support plate113of each moving block110. The linear slider104of the moving blocks110engages with the linear rail103in a freely sliding manner, and the linear rail103and the linear sliders104constitute a linear guide (guide structure).

The moving blocks110are made movable in the horizontal direction by the thus arranged linear guide (guide structure).

In this respect, the wiping nozzle5is attached to the frame102via a support body50and is disposed at a downward position of the moving blocks110.

Next, a moving mechanism200for moving the moving blocks110in the horizontal direction will be explained.

The moving mechanism200is arranged to transmit driving force of a servomotor to the moving blocks110using a rack and pinion mechanism for moving the moving blocks110. Moreover, the rack and pinion mechanism is comprised of gear elements in mesh with other gear elements on an upper plane and gear elements in mesh with other gear elements on a lower plane with respect to the vertical direction.

In the following explanations, gear elements in mesh with other gear elements on the upper plane are marked with “reference numerals which are numbers added with α” while gear elements in mesh with other gear elements on the lower plane are marked with “reference numerals which are numbers added with β”.

FIG. 7AandFIG. 7Bare plan views showing the moving mechanism200provided in the correction mechanism100F of the plate crossbow correction device100in a widened state, andFIG. 8AandFIG. 8Bare plan views showing the moving mechanism200provided in the correction mechanism100F of the plate crossbow correction device100in a narrowed state.

Further, inFIG. 7AandFIG. 8A, gear elements in mesh with other gear elements on the upper plane are shown by solid lines while gear elements in mesh with other gear elements on the lower plane are shown by dotted lines. InFIG. 7BandFIG. 8B, gear elements in mesh with other gear elements on the lower plane are shown by solid lines while gear elements in mesh with other gear elements on the upper plane are shown by dotted lines.

A driving source unit205is attached to the frame102at a central portion in the horizontal direction of the correction mechanism100F of the plate crossbow correction device100. The driving source unit205comprises a servomotor206, and a drive gear201β is provided at a rotating shaft of the servomotor206. The driving source unit205is provided with a pinion gear202β and a pinion gear203β which mesh with the drive gear201β.

The moving block110-1is provided with a pinion gear211α, an idler gear212α which is in mesh with the pinion gear211α and a speed-increasing pinion gear213α which is a two-stage gear formed of a small-diameter gear and a large-diameter gear. The idler gear212α is in mesh with the small-diameter gear of the speed-increasing pinion gear213α.

Lower end sides of rotating shafts of these gears211α,212α and213α are supported by the lower support plate112through bearings and upper end sides of the rotating shafts are supported by the upper support plate113through bearings.

The moving block110-1is provided with a movable rack214β projecting to the driving source unit205side, and the movable rack214β is in mesh with the pinion gear202β. Moreover, the movable rack214β is supported at the frame102in a movable manner by means of a linear guide for movable racks.

Moreover, a fixed rack215α is fixed to the frame102proximate of the moving block110-1. The fixed rack215α is in mesh with the pinion gear211α.

The moving block110-2is provided with a movable rack221α projecting to the moving block110-1side and the movable rack221α is in mesh with the large-diameter gear of the pinion gear213α. Further, the movable rack221α is supported at the frame102in a movable manner by means of the linear guide for movable racks.

The moving block110-3is provided with a pinion gear231α, an idler gear232α which is in mesh with the pinion gear231α and a speed-increasing pinion gear233α which is a two-stage gear formed of a small-diameter gear and a large-diameter gear. The idler gear232α is in mesh with the small-diameter gear of the speed-increasing pinion gear233α.

Lower end sides of rotating shafts of these gears231α,232α and233α are supported by the lower support plate112through bearings and upper end sides of the rotating shafts are supported by the upper support plate113through bearings.

The moving block110-3is provided with a movable rack234β projecting to the driving source unit205side, and the movable rack234β is in mesh with the pinion gear203β. Moreover, the movable rack234β is supported at the frame102in a movable manner by means of the linear guide for movable racks.

Moreover, a fixed rack235α is fixed to the frame102proximate of the moving block110-3. The fixed rack235α is in mesh with the pinion gear231α.

The moving block110-4is provided with a movable rack241α projecting to the moving block110-3side and the movable rack241α is in mesh with the large-diameter gear of the pinion gear233α. Moreover, the movable rack241α is supported at the frame102in a movable manner by means of the linear guide for movable racks.

In the moving mechanism200, the diameter of the pinion gears202β,203β,211α and231α is D1, and in the speed-increasing pinion gears213α,233α, the diameter of the large-diameter gears is D1while the diameter of the small-diameter gears is D2. Namely, the gear ratio of the rack and pinion mechanism of the moving mechanism200is determined by the diameter D1and the diameter D2.

Next, operations of moving the moving blocks110in the horizontal direction by driving the moving mechanism200will be explained.

When the driving gear201β is rotated leftward by the servomotor206of the driving source unit205in the widened state as shown inFIG. 7AandFIG. 7B, the pinion gear202β is rotated rightward and pulls the movable rack214β to the driving source unit205side. With this arrangement, the moving block110-1moves to the left.

When the moving block110-1moves to the left, the pinion gear211a in mesh with the fixed rack215α rotates leftward, the idler gear212α rotates rightward and the speed-increasing pinion gear213α rotates leftward. The leftward rotation of the speed-increasing pinion gear213α pulls the movable rack221α to the moving block110-1side. With this arrangement, the moving block110-2moves to the left.

Further, when the driving gear201β is rotated leftward by the servomotor206of the driving source unit205in the widened state as shown inFIG. 7AandFIG. 7B, the pinion gear203β is rotated rightward and pulls the movable rack234β to the driving source unit205side. With this arrangement, the moving block110-3moves to the right.

When the moving block110-3moves to the right, the pinion gear231α in mesh with the fixed rack235α rotates leftward, the idler gear232α rotates rightward and the speed-increasing pinion gear233α rotates leftward. The leftward rotation of the speed-increasing pinion gear233α pulls the movable rack241α to the moving block110-3side. With this arrangement, the moving block110-4moves to the right.

In this manner, with the moving blocks110-1,110-2moving to the left and the moving blocks110-3,110-4moving to the right, the narrowed state as shown inFIG. 8AandFIG. 8Bis achieved.

When the driving gear201α is rotated rightward by the servomotor206of the driving source unit205in the narrowed state as shown inFIG. 8AandFIG. 8B, the gear elements move in reverse directions to make the moving blocks110-1,110-2move to the right and the moving blocks110-3,110-4move to the left to achieve the widened state as shown inFIG. 7AandFIG. 7B.

With respect to the plate width direction (horizontal direction) of the strips, in the widened state ofFIG. 3, when the distance from the central position CL of the plate crossbow correction device100to the moved position of the moving block110-1is defined as L12and the distance from the central position CL to the moved position of the moving block110-2is defined as L22, and in the narrowed state ofFIG. 4, when the distance from the central position CL to the moved position of the moving block110-1is defined as L11and the distance from the central position CL to the moved position of the moving block110-2is defined as L21, the stroke ratio of the moving block110-1and the moving block110-2can be expressed by the following equation (1).

Similarly, the stroke ratio of the moving block110-3and the moving block110-4can also be expressed by the equation (1).

Ultimately, the ratio of the moving distance of the moving blocks110-2,110-4with respect to the moving distance of the moving blocks110-1,110-3is constant (a preliminarily determined constant ratio).

Namely, the gear ratio of the rack and pinion mechanism of the moving mechanism200is determined such that the moving distances of the moving blocks110-1,110-2,110-3and110-4, when seen from a central position of the plate crossbow correction device, become a distance which is in correspondence with a preliminarily determined stroke ratio.

In this respect, inFIG. 3, W indicates a widened strip width and inFIG. 4, W indicates a narrowed strip width.

A plate width edge position which is a position of one end in the plate width direction of the strip2detected by the plate edge sensor20is input to the control device30.

In that case, the control device30controls the servomotor206to move the moving blocks110-4of the correction mechanisms100F,100B such that from among the plate crossbow correction device100, a pair of electromagnets at which one end side in the plate width direction of the strip2is located, more particularly, an electromagnet M provided in the moving block110-4which is a moving block close to an end portion of the steel plate (strip2) from among the moving blocks110of the correction mechanism100F and an electromagnet M provided in the moving block110-4which is a moving block close to an end portion of the steel plate (strip2) from among the moving blocks110of the correction mechanism100B, opposes the one end portion of the strip2.

Accompanying movements of the moving blocks110-4, the other moving blocks110-1,110-2and110-3are also moved while maintaining the relationship of the stroke indicated by the equation (1).

Simultaneously, the control device30controls a current value supplied to the electromagnets M such that the distances detected by the distance sensors S become a set distance to thereby adjust the electromagnetic force of the electromagnets M applied to the strip2. With this arrangement, crossbow of the strips2is correct in a contactless manner and vibration of the strips2is suppressed.

Therefore, even when the strips2meander or their plate width changes, a pair of electromagnets M on one end side of the plate crossbow correction mechanism100and a pair of electromagnets M on the other end side correctly oppose the one end portion and the other end portion of the strip2.

FIG. 9shows a crossbowed state of the strip2at a position at which the distance sensor S of the plate crossbow correction device100is disposed, wherein the horizontal axis shows the plate width direction position while the vertical axis shows the plate shape (amount of crossbow). The solid line inFIG. 9shows a crossbowed state of a strip2after crossbow correction and the dotted line inFIG. 9shows a crossbowed state of a strip2when no crossbow correction has been performed.

FIG. 10shows a crossbowed state of the strip2at a position at which the wiping nozzle5of the plate crossbow correction device100is disposed, wherein the horizontal axis shows the plate width direction position while the vertical axis shows the plate shape (amount of crossbow). The solid line inFIG. 10shows a crossbowed state of a strip2after crossbow correction and the dotted line inFIG. 10shows a crossbowed state of a strip2when no crossbow correction has been performed.

As shown by the solid lines inFIG. 9andFIG. 10, when performing plate crossbow correction using electromagnets M in the plate crossbow correction device100according to the first embodiment, at least a pair of electromagnets M on one end side will correctly oppose an end portion of the strip2so that crossbow at both side portions of the strip2can be suppressed.

Further, since the moving positions of the moving blocks move while maintaining the relationship indicated by the equation (1) at the time the moving blocks110move, the disposing positions of the electromagnets M of the moving blocks110will be suitable, and plate crossbow of the strip2can be reliably suppressed also at positions other than both end portions of the strip2.

In the above first embodiment, while the plate crossbow correction device100is provided with four pairs of electromagnets M, it might also be provided with five pairs of electromagnets M and also six or more pairs of electromagnets M.

When the number of pairs of electromagnets M is an odd number, a configuration is employed in which electromagnets M at a central position (a block provided with electromagnets) are not moved.

FIG. 11shows a crossbowed state of a strip at the time of crossbow correction at a position at which a distance sensor is disposed in the plate crossbow correction device provided with five pair of electromagnets.

FIG. 12shows a crossbowed state of a strip at the time of crossbow correction at a position at which the wiping nozzle is disposed in a plate crossbow correction device provided with five pair of electromagnets.

As shown in both drawings, it can be understood that crossbow can be further suppressed at particularly the central portion in the plate width direction by increasing the number of pairs of electromagnets.

FIG. 13is a characteristic diagram showing a relationship between numbers of pairs of electromagnets and plate crossbow at the position at which the wiping nozzle is disposed.

As shown inFIG. 13, it can be understood that plate crossbow can be effectively suppressed when four or more pairs of electromagnets are provided.

In this respect, while the hot-dip galvanizing line10acomprised with the plate crossbow correction device100of the above-described first embodiment comprises in-bath rolls4a,4b, it is also possible to configure a hot-dip galvanizing line without in-bath rollers when plate crossbow correction can be reliably performed using the plate crossbow correction device100.

Second Embodiment

A plate crossbow correction device1000according to the second embodiment will be explained with reference toFIG. 14which is a plan view andFIG. 15which is a front view when the device on the front surface side is seen from the strip side.

InFIG. 14andFIG. 15, the configuration of the correction mechanism100F on the front surface side and the correction mechanism100B on the back surface side are identical to that shown in the first embodiment.

The correction mechanism100F on the front surface side is arranged to be movable along the plate width direction of the strip by means of an overall moving mechanism1100on the front surface side. The correction mechanism100B on the back surface side is arranged to be movable along the plate width direction of the strip by means of an overall moving mechanism1200on the back surface side.

The overall moving mechanism1100on the front surface side is comprised of a main frame1101and moving and supporting devices1102,1103for supporting the main frame1101at both ends of the main frame1101to be movable along the plate width direction of the strip. The main frame1101supports the correction mechanism100F.

Therefore, when the main frame1101moves along the plate width direction of the strip, the correction mechanism100F moves as a whole in the same direction.

The overall moving mechanism1200on the back surface side is comprised of a main frame1201and moving and supporting devices1202,1203for supporting the main frame1201at both ends of the main frame1201to be movable along the plate width direction of the strip. The main frame1201supports the correction mechanism100B.

Therefore, when the main frame1201moves along the plate width direction of the strip, the correction mechanism100B moves as a whole in the same direction.

In this case, moving operations of the moving and supporting devices1102,1103,1202, and1203are controlled such that moving directions and moving distances of the main frame1101and the main frame1201become identical.

In the second embodiment, since the correction mechanisms100F,100B can be moved in the plate width direction of the strip as a whole, the correction mechanisms100F,100B can be moved in accordance therewith even if the strips largely meander so that crossbow of the strips can be reliably suppressed.

INDUSTRIAL APPLICABILITY

The present invention can be used for correcting crossbow of strips in molten metal plating facilities.