PLATE CROSSBOW CORRECTION DEVICE AND PLATE CROSSBOW CORRECTION METHOD

Abstract

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.

Description

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 in FIG. 16 and FIG. 17.

As shown in FIG. 16 and FIG. 17, in a hot-dip galvanizing line 10, strips 2 are successively infiltrated into molten metal (molten plating bath) 1 and by winding the strips 2 around a sink roll 3 disposed in the molten metal 1, the running direction of the strips 2 is changed to an upward direction. After making in-bath rolls (support rolls) 4a 4b contact both surfaces of the strips 2 (front surfaces and back surfaces of the strips) running in an upward direction, the strips 2 are pulled out from the molten metal 1. Air is sprayed from a wiping nozzle 5 towards both surfaces of the strips 2 which have been pulled out and are running in the upward direction to remove excess molten metal. A plate crossbow correction device 6 is disposed upward of the wiping nozzle 5 and the strips 2 run upward upon passing the plate crossbow correction device 6.

The plate crossbow correction device 6 suppresses vibration of the strips 2 by applying electromagnetic force (suction force) towards the strips 2 and corrects crossbow of the strips 2 in a contactless manner. Details of the plate crossbow correction device 6 will be described later.

Here, explanations will now be made about crossbow occurring in strips 2 and steps for correction the crossbow in such a hot-dip galvanizing line 10.

When the strips 2 are wound around the sink roll 3, C crossbow (plastic crossbow), which is crossbow deformation in a plate width direction, occurs in the strips 2. Therefore, the in-bath rolls 4a, 4b are made to contact both surfaces of the strips 2 in which the C crossbow has occurred for correcting the C crossbow. Further, C crossbow is corrected by the plate crossbow correction device 6 by applying electromagnetic force to the strips 2.

By correcting C crossbow in this manner, the distance of the wiping nozzle 5 and the strips 2 will become substantially identical at respective positions in the plate width direction (horizontal direction) of the strips 2 and the removal amount of molten metal by the wiping nozzle 5 will become substantially identical at respective positions in the plate width direction. Thus, the amount of plating adhering to the strips 2 can be made uniform.

The plate crossbow correction device 6 includes a correction mechanism 6F on the front surface side disposed to be apart from the front surface of a strip 2 and a correction mechanism 6B on the back surface side disposed to be apart from the back surface of the strip 2.

The correction mechanism 6F 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 mechanism 6F on the front surface side, the correction mechanism 6B 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 mechanism 6F on the front surface side and the electromagnets M provided in the correction mechanism 6B on the back surface side are respectively disposed to oppose each other with the strips 2 being interposed between.

The distance sensors S detect distances between themselves and the strips 2. 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 strips 2. With this arrangement, crossbow of the strips 2 is corrected in a contactless manner and vibration of the strips 2 is 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 to FIG. 18 and FIG. 19. In this respect, in FIG. 18 and FIG. 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. 18 shows 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 in FIG. 18 shows a crossbowed state of a strip after crossbow correction and the dotted line in FIG. 18 shows a crossbowed state of a strip when no crossbow correction has been performed.

FIG. 19 shows 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 in FIG. 19 shows a crossbowed state of a strip after crossbow correction and the dotted line in FIG. 19 shows a crossbowed state of a strip when no crossbow correction has been performed.

As shown by the solid lines in FIG. 18 and FIG. 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.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing a hot-dip galvanizing line comprising the plate crossbow correction device according to the first embodiment of the present invention.

FIG. 2 is a side view showing the hot-dip galvanizing line comprising the plate crossbow correction device according to the first embodiment of the present invention.

FIG. 3 is a front view when a correction mechanism on a front surface side in a widened state is seen from the strip side.

FIG. 4 is a front view when the correction mechanism on the front surface side in a narrowed state is seen from the strip side.

FIG. 5 is a sectional view including an A-A section of FIG. 3.

FIG. 6 is a sectional view including a B-B section of FIG. 3.

FIG. 7A is a plan view showing a moving mechanism in a widened state.

FIG. 7B is a plan view showing a moving mechanism in a widened state.

FIG. 8 A is a plan view showing the moving mechanism in a narrowed state.

FIG. 8 B is a plan view showing the moving mechanism in a narrowed state.

FIG. 9 is a characteristic diagram showing a crossbowed state of a strip at a position at which a distance sensor is disposed in the first embodiment.

FIG. 10 is a characteristic diagram showing a crossbowed state of a strip at a position at which a wiping nozzle is disposed in the first embodiment.

FIG. 11 is a characteristic diagram showing a crossbowed state of a strip after crossbowing correction at the position at which the distance sensor is disposed in a plate crossbow correction device comprising five pairs of electromagnets.

FIG. 12 is a characteristic diagram showing a crossbowed state of a strip after crossbowing correction at the position at which the wiping nozzle is disposed in the plate crossbow correction device comprising five pairs of electromagnets.

FIG. 13 is 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.

FIG. 14 is a plan view showing the plate crossbow correction device according to the second embodiment of the present invention.

FIG. 15 is a front view when the plate crossbow correction device according to the second embodiment of the present invention is seen from the strip side.

FIG. 16 is a front view showing a hot-dip galvanizing line comprising the plate crossbow correction device of the prior art.

FIG. 17 is a side view showing the hot-dip galvanizing line comprising the plate crossbow correction device of the prior art.

FIG. 18 is a characteristic diagram showing a crossbowed state of a strip at a position at which a distance sensor is disposed according to the prior art.

FIG. 19 is a characteristic diagram showing a crossbowed state of a strip at a position at which a wiping nozzle is disposed according to the prior art.

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 line 10a comprising a plate crossbow correction device 100 according to the first embodiment of the present invention will be explained with reference to FIG. 1 which is a front view and FIG. 2 which is a side view.

In the hot-dip galvanizing line 10a, strips 2 successively infiltrated into molten metal 1 are wound around a sink roll 3 and the running direction is changed into an upward direction, similarly to the hot-dip galvanizing line 10 shown in FIG. 16 and FIG. 17. After making in-bath rolls 4a 4b contact both surfaces of the strips 2, the strips 2 are pulled out from the molten metal 1, and air is sprayed from a wiping nozzle 5 towards both surfaces of the strips 2 to remove excess molten metal. A plate crossbow correction device 100 according to the present embodiment is disposed upward of the wiping nozzle 5, and the strips 2 run upward upon passing the plate crossbow correction device 100.

Explaining the outline of the plate crossbow correction device 100, the plate crossbow correction device 100 includes a correction mechanism 100F on the front surface side disposed to be apart from the front surface of a strip 2 and a correction mechanism 100B on the back surface side disposed to be apart from the back surface of the strip 2.

The correction mechanism 100F 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 mechanism 100F on the front surface side, the correction mechanism 100B 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 mechanism 100F on the front surface side and the electromagnets M provided in the correction mechanism 100B on the back surface side are respectively disposed to oppose each other with the strips 2 being interposed between.

Namely, the plate crossbow correction device 100 comprises 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 strips 2 in accordance with meanderings or changes in plate widths of the strips 2 in order to suitably correct crossbowing of the strips 2.

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 sensor 20 is disposed at an upward position of the plate crossbow correction device 100. The plate edge sensor 20 detects plate edge positions which are positions on one end (right end in the example of FIG. 1) in the plate width direction of the strips 2.

As it will be described later, a control device 30 controls positions in the plate width direction of the four pairs of electromagnets M of the plate crossbow correction device 100 in accordance with plate width edge positions detected by the plate edge sensor 20.

Next, details of the plate crossbow correction device 100 will be explained.

FIG. 3 is a front view of the correction mechanism 100F on the front side in a widened state seen from the strip side, FIG. 4 is a front view of the correction mechanism 100F on the front side in a narrowed state seen from the strip side, FIG. 5 is a sectional view including an A-A section of FIG. 3, and FIG. 6 is a sectional view including a B-B section of FIG. 3. In this respect, for easy understanding, components which are not illustrated in FIG. 3 are shown in FIG. 5 and FIG. 6.

In this respect, since machine configurations of the correction mechanism 100F on the front side and the correction mechanism 100B on the back side are identical, explanations will be made of the detailed configuration of the correction mechanism 100F on the front side only while explanations of the detailed configuration of the correction mechanism 100B on the back side will be omitted.

As shown in FIG. 3 to FIG. 6, a frame 102 extending in the plate width direction (horizontal direction) of the strips 2 is fixedly installed at a support beam 101.

The frame 102 is provided with four moving blocks 110-1, 110-2, 110-3 and 110-4 aligned in the horizontal direction. While details will be explained later, the moving blocks 110-1 to 110-4 are provided to be movable in the horizontal direction along the frame 102. In this respect, reference numeral 110 is used when the four moving blocks 110-1 to 110-4 are to be collectively referred to.

Each moving block 110 is 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 pole 111 of the moving block 110 and the distance sensor S is provided on an upper side of the support pole 111 (see FIG. 6). Namely, the distance sensor S is disposed at an upward position of the electromagnet M.

A lower support plate 112 is fixed to an upper end portion of the support pole 111 and an upper support plate 113 is disposed at an upward position of the lower support plate 112. The upper support plate 113 is attached to the lower support plate 112 via gears (pinions or the like) to be described later.

A linear rail 103 extending in the horizontal direction is provided on a lower surface of the frame 102. A linear slider 104 is attached on an upper surface of the upper support plate 113 of each moving block 110. The linear slider 104 of the moving blocks 110 engages with the linear rail 103 in a freely sliding manner, and the linear rail 103 and the linear sliders 104 constitute a linear guide (guide structure).

The moving blocks 110 are made movable in the horizontal direction by the thus arranged linear guide (guide structure).

In this respect, the wiping nozzle 5 is attached to the frame 102 via a support body 50 and is disposed at a downward position of the moving blocks 110.

Next, a moving mechanism 200 for moving the moving blocks 110 in the horizontal direction will be explained.

The moving mechanism 200 is arranged to transmit driving force of a servomotor to the moving blocks 110 using a rack and pinion mechanism for moving the moving blocks 110. 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. 7A and FIG. 7B are plan views showing the moving mechanism 200 provided in the correction mechanism 100F of the plate crossbow correction device 100 in a widened state, and FIG. 8A and FIG. 8B are plan views showing the moving mechanism 200 provided in the correction mechanism 100F of the plate crossbow correction device 100 in a narrowed state.

Further, in FIG. 7A and FIG. 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. In FIG. 7B and FIG. 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 unit 205 is attached to the frame 102 at a central portion in the horizontal direction of the correction mechanism 100F of the plate crossbow correction device 100. The driving source unit 205 comprises a servomotor 206, and a drive gear 201β is provided at a rotating shaft of the servomotor 206. The driving source unit 205 is provided with a pinion gear 202β and a pinion gear 203β which mesh with the drive gear 201β.

The moving block 110-1 is provided with a pinion gear 211α, an idler gear 212α which is in mesh with the pinion gear 211α and a speed-increasing pinion gear 213α which is a two-stage gear formed of a small-diameter gear and a large-diameter gear. The idler gear 212α is in mesh with the small-diameter gear of the speed-increasing pinion gear 213α.

Lower end sides of rotating shafts of these gears 211α, 212α and 213α are supported by the lower support plate 112 through bearings and upper end sides of the rotating shafts are supported by the upper support plate 113 through bearings.

The moving block 110-1 is provided with a movable rack 214β projecting to the driving source unit 205 side, and the movable rack 214β is in mesh with the pinion gear 202β. Moreover, the movable rack 214β is supported at the frame 102 in a movable manner by means of a linear guide for movable racks.

Moreover, a fixed rack 215α is fixed to the frame 102 proximate of the moving block 110-1. The fixed rack 215α is in mesh with the pinion gear 211α.

The moving block 110-2 is provided with a movable rack 221α projecting to the moving block 110-1 side and the movable rack 221α is in mesh with the large-diameter gear of the pinion gear 213α. Further, the movable rack 221α is supported at the frame 102 in a movable manner by means of the linear guide for movable racks.

The moving block 110-3 is provided with a pinion gear 231α, an idler gear 232α which is in mesh with the pinion gear 231α and a speed-increasing pinion gear 233α which is a two-stage gear formed of a small-diameter gear and a large-diameter gear. The idler gear 232α is in mesh with the small-diameter gear of the speed-increasing pinion gear 233α.

Lower end sides of rotating shafts of these gears 231α, 232α and 233α are supported by the lower support plate 112 through bearings and upper end sides of the rotating shafts are supported by the upper support plate 113 through bearings.

The moving block 110-3 is provided with a movable rack 234β projecting to the driving source unit 205 side, and the movable rack 234β is in mesh with the pinion gear 203β. Moreover, the movable rack 234β is supported at the frame 102 in a movable manner by means of the linear guide for movable racks.

Moreover, a fixed rack 235α is fixed to the frame 102 proximate of the moving block 110-3. The fixed rack 235α is in mesh with the pinion gear 231α.

The moving block 110-4 is provided with a movable rack 241α projecting to the moving block 110-3 side and the movable rack 241α is in mesh with the large-diameter gear of the pinion gear 233α. Moreover, the movable rack 241α is supported at the frame 102 in a movable manner by means of the linear guide for movable racks.

In the moving mechanism 200, the diameter of the pinion gears 202β, 203β, 211α and 231α is D1, and in the speed-increasing pinion gears 213α, 233α, the diameter of the large-diameter gears is D1 while the diameter of the small-diameter gears is D2. Namely, the gear ratio of the rack and pinion mechanism of the moving mechanism 200 is determined by the diameter D1 and the diameter D2.

Next, operations of moving the moving blocks 110 in the horizontal direction by driving the moving mechanism 200 will be explained.

When the driving gear 201β is rotated leftward by the servomotor 206 of the driving source unit 205 in the widened state as shown in FIG. 7A and FIG. 7B , the pinion gear 202β is rotated rightward and pulls the movable rack 214β to the driving source unit 205 side. With this arrangement, the moving block 110-1 moves to the left.

When the moving block 110-1 moves to the left, the pinion gear 211 a in mesh with the fixed rack 215α rotates leftward, the idler gear 212α rotates rightward and the speed-increasing pinion gear 213α rotates leftward. The leftward rotation of the speed-increasing pinion gear 213α pulls the movable rack 221α to the moving block 110-1 side. With this arrangement, the moving block 110-2 moves to the left.

Further, when the driving gear 201β is rotated leftward by the servomotor 206 of the driving source unit 205 in the widened state as shown in FIG. 7A and FIG. 7B , the pinion gear 203β is rotated rightward and pulls the movable rack 234β to the driving source unit 205 side. With this arrangement, the moving block 110-3 moves to the right.

When the moving block 110-3 moves to the right, the pinion gear 231α in mesh with the fixed rack 235α rotates leftward, the idler gear 232α rotates rightward and the speed-increasing pinion gear 233α rotates leftward. The leftward rotation of the speed-increasing pinion gear 233α pulls the movable rack 241α to the moving block 110-3 side. With this arrangement, the moving block 110-4 moves to the right.

In this manner, with the moving blocks 110-1, 110-2 moving to the left and the moving blocks 110-3, 110-4 moving to the right, the narrowed state as shown in FIG. 8A and FIG. 8B is achieved.

When the driving gear 201 α is rotated rightward by the servomotor 206 of the driving source unit 205 in the narrowed state as shown in FIG. 8A and FIG. 8B , the gear elements move in reverse directions to make the moving blocks 110-1, 110-2 move to the right and the moving blocks 110-3, 110-4 move to the left to achieve the widened state as shown in FIG. 7A and FIG. 7B.

With respect to the plate width direction (horizontal direction) of the strips, in the widened state of FIG. 3, when the distance from the central position CL of the plate crossbow correction device 100 to the moved position of the moving block 110-1 is defined as L12 and the distance from the central position CL to the moved position of the moving block 110-2 is defined as L22, and in the narrowed state of FIG. 4, when the distance from the central position CL to the moved position of the moving block 110-1 is defined as L11 and the distance from the central position CL to the moved position of the moving block 110-2 is defined as L21, the stroke ratio of the moving block 110-1 and the moving block 110-2 can be expressed by the following equation (1).

Stroke ratio=1+(D1/D2)=(L22−L21)/(L12−L11)   (1)

Similarly, the stroke ratio of the moving block 110-3 and the moving block 110-4 can also be expressed by the equation (1).

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

Namely, the gear ratio of the rack and pinion mechanism of the moving mechanism 200 is determined such that the moving distances of the moving blocks 110-1, 110-2, 110-3 and 110-4, 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, in FIG. 3, W indicates a widened strip width and in FIG. 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 strip 2 detected by the plate edge sensor 20 is input to the control device 30.

In that case, the control device 30 controls the servomotor 206 to move the moving blocks 110-4 of the correction mechanisms 100F, 100B such that from among the plate crossbow correction device 100, a pair of electromagnets at which one end side in the plate width direction of the strip 2 is located, more particularly, an electromagnet M provided in the moving block 110-4 which is a moving block close to an end portion of the steel plate (strip 2) from among the moving blocks 110 of the correction mechanism 100F and an electromagnet M provided in the moving block 110-4 which is a moving block close to an end portion of the steel plate (strip 2) from among the moving blocks 110 of the correction mechanism 100B, opposes the one end portion of the strip 2.

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

Simultaneously, the control device 30 controls 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 strip 2. With this arrangement, crossbow of the strips 2 is correct in a contactless manner and vibration of the strips 2 is suppressed.

Therefore, even when the strips 2 meander or their plate width changes, a pair of electromagnets M on one end side of the plate crossbow correction mechanism 100 and a pair of electromagnets M on the other end side correctly oppose the one end portion and the other end portion of the strip 2.

FIG. 9 shows a crossbowed state of the strip 2 at a position at which the distance sensor S of the plate crossbow correction device 100 is 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 in FIG. 9 shows a crossbowed state of a strip 2 after crossbow correction and the dotted line in FIG. 9 shows a crossbowed state of a strip 2 when no crossbow correction has been performed.

FIG. 10 shows a crossbowed state of the strip 2 at a position at which the wiping nozzle 5 of the plate crossbow correction device 100 is 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 in FIG. 10 shows a crossbowed state of a strip 2 after crossbow correction and the dotted line in FIG. 10 shows a crossbowed state of a strip 2 when no crossbow correction has been performed.

As shown by the solid lines in FIG. 9 and FIG. 10, when performing plate crossbow correction using electromagnets M in the plate crossbow correction device 100 according to the first embodiment, at least a pair of electromagnets M on one end side will correctly oppose an end portion of the strip 2 so that crossbow at both side portions of the strip 2 can 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 blocks 110 move, the disposing positions of the electromagnets M of the moving blocks 110 will be suitable, and plate crossbow of the strip 2 can be reliably suppressed also at positions other than both end portions of the strip 2.

In the above first embodiment, while the plate crossbow correction device 100 is 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. 11 shows 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. 12 shows 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. 13 is 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 in FIG. 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 line 10a comprised with the plate crossbow correction device 100 of the above-described first embodiment comprises in-bath rolls 4a, 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 device 100.

Second Embodiment

A plate crossbow correction device 1000 according to the second embodiment will be explained with reference to FIG. 14 which is a plan view and FIG. 15 which is a front view when the device on the front surface side is seen from the strip side.

In FIG. 14 and FIG. 15, the configuration of the correction mechanism 100F on the front surface side and the correction mechanism 100B on the back surface side are identical to that shown in the first embodiment.

The correction mechanism 100F on the front surface side is arranged to be movable along the plate width direction of the strip by means of an overall moving mechanism 1100 on the front surface side. The correction mechanism 100B on the back surface side is arranged to be movable along the plate width direction of the strip by means of an overall moving mechanism 1200 on the back surface side.

The overall moving mechanism 1100 on the front surface side is comprised of a main frame 1101 and moving and supporting devices 1102, 1103 for supporting the main frame 1101 at both ends of the main frame 1101 to be movable along the plate width direction of the strip. The main frame 1101 supports the correction mechanism 100F.

Therefore, when the main frame 1101 moves along the plate width direction of the strip, the correction mechanism 100F moves as a whole in the same direction.

The overall moving mechanism 1200 on the back surface side is comprised of a main frame 1201 and moving and supporting devices 1202, 1203 for supporting the main frame 1201 at both ends of the main frame 1201 to be movable along the plate width direction of the strip. The main frame 1201 supports the correction mechanism 100B.

Therefore, when the main frame 1201 moves along the plate width direction of the strip, the correction mechanism 100B moves as a whole in the same direction.

In this case, moving operations of the moving and supporting devices 1102, 1103, 1202, and 1203 are controlled such that moving directions and moving distances of the main frame 1101 and the main frame 1201 become identical.

In the second embodiment, since the correction mechanisms 100F, 100B can be moved in the plate width direction of the strip as a whole, the correction mechanisms 100F, 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.

Claims

1. 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.

2. The plate crossbow correction device according to claim 1,

wherein 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.

3. The plate crossbow correction device according to claim 2,

wherein 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.

4. The plate crossbow correction device according to claim 1, further comprising

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.

5. A plate crossbow correction device further including

an overall moving mechanism on the front surface side moving the correction mechanism on the front surface side according to claim 1 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 according to claim 1 along the plate width direction of the steel plate.

6. 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.

7. The plate crossbow correction method according to claim 6,

wherein 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.

8. The plate crossbow correction method according to claim 6,

wherein 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.