JP5228657B2 - Dross adsorption device in hot dipping bath - Google Patents

Description

  The present invention prevents surface defects caused by solid particles such as dross precipitated and floating in the plating bath in the continuous hot dipping process of a steel plate or other metal plate, and are attached to the surface of the plated steel plate or the like. Therefore, the present invention relates to a dross adsorption device that captures solid particles such as dross that rolls up and reduces solid particles such as dross in a plating bath.

  Various types of hot-dip plated metal plates have been developed and put into practical use for a long time. Among them, hot dip galvanized steel sheets are widely used as materials for automobiles, building materials, home appliances and the like because of their excellent corrosion resistance and economy.

  The present invention can be applied to various types of hot dip plating such as aluminum plating and tin plating in addition to hot dip galvanizing, but the case of the most common hot dip galvanizing equipment for steel plates is taken as an example. And will be described as follows.

  In the case of continuously producing a hot dip galvanized steel sheet, a method is generally used in which the steel sheet is moved while being immersed in the hot dip bath and plated.

  At this time, solid particles that are impurities deposited and deposited at the bottom of the hot dipping bath, for example, bottom dross (commonly known as dross that settles at the bottom of the plating bath), rolls up during the plating process as the steel plate moves. It is known that it adheres to the surface of the steel plate and impairs the appearance of the plated steel plate.

  Various preventive measures have been tried at the operation site against the rolling up of the bottom dross in the hot dipping bath, but there is no complete solution at present.

  In FIG. 10, the outline of the continuous hot-dip galvanizing apparatus of the steel plate generally employ | adopted is shown. In the continuous hot dip galvanizing apparatus shown in FIG. 10, the steel sheet 1 is annealed in an annealing furnace (not shown), and then passed through the snout 2 and introduced into the hot dip galvanizing bath 3.

  The introduced steel sheet is turned upward by the sink roll 4 provided in the hot dip galvanizing bath 3, and after the warp is corrected by the support roll 5, the steel sheet is drawn out from the plating bath surface 6.

  Next, a wiping gas is blown from the gas wiping nozzle 7 toward both surfaces of the hot dip galvanized plated steel sheet 1 ′ to adjust the plating adhesion amount.

  Furthermore, after correcting the shape of the plated steel plate 1 ′ and passing it through a vibration damping device 8 that suppresses vibration of the steel plate, an alloying treatment of plating is performed in the alloying heating furnace 9 as necessary.

  In the hot dip galvanizing bath, Fe elutes from the steel sheet into the hot galvanized bath, and granular and powdery substances composed of Fe-Zn intermetallic compounds, so-called dross, are generated.

Among these drosses, those containing FeZn ₇ as a main component have a larger specific gravity than molten zinc, and therefore settle and deposit on the bottom of the plating bath, so they are generally called bottom dross (10 in FIG. 10). .

  The bottom dross starts to wind up due to the accompanying flow generated by the movement of the steel plate that circulates around the sink roll in the galvanizing bath, and eventually adheres to the surface of the plated steel plate, causing an appearance defect of the plated steel plate.

  In particular, when the sink roll or the support roll and the steel plate are in contact with each other, the bottom dross is bitten and crimped, and remains on the plated steel plate as a final product. It becomes.

  In particular, in recent operation sites, attempts have been made to increase the sheet feeding speed in order to improve production capacity, and this causes strong stirring and dross generation in the plating bath. The amount of Fe elution increases and the bottom dross tends to become more intense.

  On the other hand, the appearance quality of plated steel sheets requested by customers is also becoming stricter, and it is necessary to solve the problem of rolling up the bottom dross at the operation site.

  In order to solve the above problems, various proposals have been conventionally made.

  For example, in Patent Document 1 and Patent Document 2, a shielding plate that covers the entire length of the sink roll and suppresses the flow of the plating bath is provided between the sink roll and the bottom of the plating tank. A bottom dross hoisting suppression method that forms a space in which bottom dross accumulates has been proposed.

  Patent Document 3 proposes a continuous hot dip galvanizing apparatus characterized in that a perforated plate that suppresses the flow in the bath is installed between the sink roll and the bottom of the plating tank.

  Further, in Patent Document 4, two plate-like members having a length corresponding to 20 to 40% of the sink roll body length are provided apart from the sink roll surface from both ends of the sink roll toward the center. There has been proposed a bottom dross roll-up preventing device characterized by the above.

  However, in these proposals, as will be described later, it is difficult to completely solve the bottom dross roll-up.

  Regarding the rolling up of the bottom dross in the hot dip galvanizing bath, conventionally, the bottom dross deposited on the bottom of the sink roll before and after the sink roll mainly by a tangential force (11 in FIG. 10) generated with the rotation of the sink roll It was thought to roll up.

  However, the present inventors conducted a three-dimensional flow analysis in the hot dip galvanizing bath to investigate the phenomenon of bottom dross rolling. As a result, it was found that the accompanying flow of the steel plate becomes a strong flow at the portion narrowed by the sink roll.

  That is, the jet generated on the side of the sink roll winding part flows vigorously toward the side bottom part in the hot dip galvanizing bath, so that the bottom dross accumulated at the bottom of the hot dip galvanizing bath is found to roll up. It was.

  When the steel plate is a wide material, as shown in FIG. 11A, the bottom dross is wound upward from the front center of the sink roll 4 upward by the jet generated at the side of the sink roll winding portion. (A in the figure) is generated.

  When the steel plate is a narrow material, as shown in FIG. 11 (b), the bottom dross is forced to wind up the bottom dross between the sink roll 4 and the side wall surface of the hot dip galvanizing bath 3 (in the drawing). B) occurs.

  In any case, as a result, the bottom dross is agitated in a form of drawing a circle in the vertical direction in the plating bath, and becomes a floating state. The present inventors have elucidated the mechanism in which the bottom dross is in a floating state and adversely affects the plating of the steel sheet.

  Assuming this mechanism, the conventional techniques have the following problems.

  First, in the methods disclosed in Patent Document 1 and Patent Document 2, the bottom dross is rolled up by installing a shielding plate against the bottom dross that tends to flow in the tangential direction of the circumference by the rotation of the sink roll. Although it can be effectively prevented, since no shielding measures or rectification measures are taken against the wall surface flow generated on both side portions of the sink roll, the roll-up of the bottom dross cannot be sufficiently suppressed.

  Second, since the apparatus disclosed in Patent Document 3 does not include a solution for the wall surface flow generated on both side portions of the sink roll, the effect of suppressing the rolling up of the bottom dross is not sufficient.

  Further, in the above apparatus, since the porous rectifying plate is provided almost entirely in the width direction of the sink roll, turbulent flow is generated between the sink roll and the porous rectifying plate, and the surface of the steel plate not in contact with the sink roll There is a concern that the bottom dross adheres and the bottom dross accumulates on the porous rectifying plate.

  Further, in the above apparatus, there is a problem that the work of passing the steel plate through a plating apparatus such as a sink roll becomes complicated when exchanging the sink roll or the like.

  Thirdly, in the apparatus disclosed in Patent Document 4, since the two shielding plates are installed on both sides of the sink roll in a separated state, the problem at the time of exchanging the sink roll or the like is solved. For the wall surface flow generated on both side surfaces of the sink roll, no rectification measures are taken, so that the roll-up of the bottom dross cannot be completely suppressed.

  In the above apparatus, when the distance between the sink roll and the plate-like member is wide, bottom dross accumulates on the plate-like member. Therefore, when the steel plate is switched from the narrow material to the wide material, The dross rolling up is encouraged.

  Conversely, when the distance between the sink roll and the plate-like member is narrow, the strong flow including the bottom dross concentrates in this narrow gap space, so the bottom dross is scattered in the plating bath, and the sink roll and support roll There is a risk of bottom dross being caught between the steel plate and the steel plate.

  Based on the accompanying flow analysis in the plating bath by the inventors of the present invention, Patent Document 5 discloses the installation of a rectifying plate in the plating bath in order to suppress the accompanying flow that causes the dross winding. However, it does not reduce the amount of floating dross itself in the plating bath only by suppressing the flow, and there is a limit in reducing defects on the plating surface.

Measures based on the accompanying flow analysis in the plating bath are also disclosed in Patent Document 6. This is because a strong downflow generated along the bathtub wall is a cause of dross hoisting, and a member having a through hole serving as a flow resistance is provided at a portion where the downflow is generated to reduce the flow velocity of the downflow. However, this also does not reduce the amount of dross itself in the plating bath and is not a measure against a strong flow in the portion squeezed by the sink roll, which is the main cause of dross winding.
Japanese Patent Publication No. 6-21331 Japanese Utility Model Publication No. 5-38045 JP-A-6-158253 JP 2001-140050 A PCT / J07 / 061147 JP 2007-204783 A

  In the present invention, the bottom dross, which is an impurity precipitated and deposited on the bottom of the hot dip galvanizing bath, rolls up along with the movement of the steel plate during the plating process in the continuous hot dip galvanizing process of the steel plate, It is an object of the present invention to provide an apparatus capable of preventing adhesion.

  In order to solve the above problems, the present invention reliably captures the bottom dross without greatly changing the flow in the plating bath, and the gist thereof is as follows.

  (1) A bottom dross adsorbing member that is partially separated at the lower part of the sink roll is placed on both side walls of the hot dip bath where the end of the sink roll shaft faces, and the member is in contact with the wall surface or 100 mm or less with the wall surface A bottom dross adsorbing device that adsorbs a bottom dross in hot dipped metal that rises or descends along the wall surface, the member being a plurality of steel plates having openings. A bottom dross adsorbing device, wherein the openings are stacked at a predetermined interval so that the openings of the steel plates do not overlap.

(2) Of the wall surface of the hot dip bath that extends in the axial direction of the sink roll , the steel plate that is the material to be plated enters the front wall surface and / or the hot dip bath located in the exit area where the hot dip detaches from the hot dip bath. The bottom dross adsorbing member is installed on the rear wall surface located in the entrance side area so that the member is in contact with the wall surface or has a gap of 100 mm or less with the wall surface, and rises or descends along the wall surface. A bottom dross adsorbing device that adsorbs bottom dross in hot-dip plated metal,
The bottom dross adsorbing device, wherein the member is formed by stacking a plurality of steel plates having openings at predetermined intervals so that the openings of the steel plates do not overlap.

  (3) A bottom dross adsorbing member is installed on both side walls of the hot dipping bath so that the member is in contact with the wall surface or has a gap of 100 mm or less from the wall surface, and rises along the wall surface. Alternatively, the bottom dross adsorbing device according to (2), wherein the bottom dross in the descending hot dipped metal is adsorbed.

  (4) In the bottom dross adsorbing apparatus, the bottom dross adsorbing member is installed such that a part of the bottom dross adsorbing member is located at a position where the distance from the bottom of the hot dipping bath does not exceed 0.8 times the distance between the bottom and the lower end of the sink roll. The bottom dross adsorption device according to any one of (1) to (3), wherein:

  (5) The width W of the bottom dross adsorbing member installed on the side wall surface of the hot dipping bath is equal to or less than the distance X from the side wall surface to the end of the steel plate, and from the side wall surface to the sink roll support member. The bottom dross adsorption device for plate-like members according to any one of (1) to (4), wherein the distance Z is equal to or greater than Z.

  (6) The depth dimension L of the bottom dross adsorbing member installed on the side wall surface of the hot dipping bath is 0.7 times or more that of the sink roll and smaller than or equal to the depth size Y inside the hot dipping bath. (1) The bottom dross adsorption | suction apparatus of the plate-shaped member in any one of (5).

  (7) The bottom dross adsorption member has a plurality of openings, and the total area of the openings is 20 to 80% of the total area of the steel plate of the bottom dross adsorption member. (6) The bottom dross adsorption | suction apparatus of the plate-shaped member in any one of.

(8) The bottom dross adsorbing member includes a plurality of openings, and an average area per opening is 5000 mm ² or less, according to any one of (1) to (7) Bottom dross adsorption device for plate-like member of metal plate.

  (9) The bottom dross adsorbing device for a plate-like member according to any one of (1) to (8), wherein the bottom dross adsorbing member has an uneven shape on one or more surfaces.

  (10) The bottom dross adsorbing member is one in which a ball-shaped steel material having a diameter of 20 to 100 mm is filled between a plurality of steel wire meshes, according to any one of (1) to (6). Bottom dross adsorption device for plate-like members.

  (11) The plate according to any one of (1) to (6), wherein the bottom dross adsorbing member is one or a plurality of mesh-like objects having a space ratio of 20 to 80% defined by JISG3556. -Shaped member bottom dross adsorption device.

  (12) The bottom dross adsorbing device according to any one of (1) to (11), wherein the bottom dross adsorbing member is made of carbon steel.

  According to the present invention, when continuous hot dip galvanizing treatment is performed at a high plate speed, it is possible to suppress the rolling up of the bottom dross deposited and accumulated in the plating bath as compared with the conventional case, and the bottom dross is attached to the bottom dross adsorption device. As a result, the amount of bottom dross in the bath can be reliably reduced, so that adhesion of bottom dross to the plated steel sheet can be greatly reduced, and a plated steel sheet or a plated metal material with few surface defects can be provided.

  A first embodiment of the present invention (the invention of claim 1) will be described. In FIG. 1, a plurality of steel plates having openings are overlapped at a predetermined interval (here, two cases will be described as an example), and the openings that do not overlap each other are installed on both side walls. And in order to make this capture the bottom dross which floats in the bathtub, it shall call a bottom dross adsorption member. In FIG. 2, the aspect of the flow (bath flow) in the bathtub at the time of using a bottom dross adsorption member is shown.

  As can be seen from a comparison with the state where the bottom dross adsorbing member shown in FIG. 11 is not installed, even when the adsorbing member is installed, the direction of the bath flow is hardly changed. However, by arranging the opening of the steel plate (perforated plate) having two openings so as not to overlap, for example, in the vertical direction, the direction of the bath flow is changed in the two porous plates, Therefore, the bottom dross having a high specific gravity moving on the flow can be separated from the bath flow, and can be deposited and captured in a portion other than the opening on the porous plate on the downstream side of the bath flow. In other words, in order to separate the bottom dross with a high specific gravity from the bath flow, the direction of the bath flow changes between the two perforated plates, and the two perforated plates are taken into account so that the bottom dross can be deposited and captured. It is necessary to install. FIG. 3 schematically shows such a state.

  Furthermore, such an arrangement of the perforated plate has the same effect as the perforated rectifying plate described in Patent Document 5 according to the invention of the present inventors, and an effect of attenuating the wall surface flow velocity is also obtained. With this action effect, the bottom dross rolling up at the bottom of the bathtub can be suppressed to a low region of the hot dip galvanizing bath, and the bottom dross biting into the steel sheet can be reduced by this suppression effect.

  The “predetermined interval” when the porous plates referred to in the present invention are stacked must be narrow enough to change the direction of the bath flow, and the fluidity of the bath flow is not hindered by the bottom dross deposited and trapped. Must be as broad as possible. This is a matter determined by the shape of the opening of the perforated plate, the shape of the hot dip galvanizing bath, the operating conditions, etc. Since the size of the bottom dross is several μm to several mm, it should be about 1 cm to about 30 cm. Is desirable.

  Further, in the present invention, the “part is separated from the lower part of the sink roll” state is that the bottom dross adsorbing member is installed separately at the lower part of the sink roll, or is located below the sink roll of the bottom dross adsorbing member. It means that the part is in a partially cut-out state. FIG. 1 shows a state in which the bottom dross adsorbing members installed on the left and right side wall surfaces are installed apart at the lower part of the sink roll. FIG. 8 shows a state in which the bottom dross adsorbing members are also installed on the front and rear wall surfaces and the four sides are surrounded by the bottom dross adsorbing members, as described later. For example, the bottom dross adsorbing members in FIG. That is, the bottom dross adsorbing member with the inside cut out may be installed on the left and right side wall surfaces, and this state is also included in the state that “a part is separated from the lower part of the sink roll”.

  In the present invention, the bottom dross adsorbing member is installed in the plating bath, as shown in FIG. 1, the bottom dross adsorbing member 22 is in contact with the side wall surfaces 21 in the plating bath 3 or has a gap of 100 mm or less from the wall surface. Install in such a way that

  The form of “installation” on the wall surface in the present invention does not mean only the state in which the bottom dross adsorption member 22 is directly attached to the side wall surface 21, the front wall surface, or the rear wall surface of the plating bath.

  As shown in FIG. 4A, the “installation” mode is a state in which the bottom dross adsorbing member 22 is attached to the support member 23 suspended from above, or as shown in FIG. 4B. It means a state in which the bottom dross adsorbing member 22 is attached to the support member 23 installed at the bottom of the bathtub. The bottom dross adsorbing member 22 is preferably in contact with the wall surface (in the figure, the side wall surface 21 is shown as an example; the same applies hereinafter), but the wall surface 21 and the bottom dross adsorbing member 22 have a thickness of 100 mm or less. If there is a gap, there is no functional problem. If the gap between the bottom dross adsorbing member 22 and the wall surface 21 exceeds 100 mm, the ratio of the bath flow flowing through the gap increases, and the dross flowing on the bath flow cannot be captured.

  In actual operation, when the production is stopped and the cleaning operation for removing the bottom dross accumulated in the plating bath is performed, if the bottom dross adsorbing member 22 is fixed to the side wall surfaces 21 by welding or the like, the cleaning operation is obstructed. It may become.

  On the other hand, as shown in FIGS. 4A and 4B, the bottom dross adsorbing member 22 is suspended by a support member 23 such as a pipe frame, or the bottom dross adsorbing member 22 is installed on the support member 23. If it is set as a mode, attachment and removal of bottom dross adsorption member 22 will become easy, and it will become easy to carry out cleaning work.

  Even if the bottom dross adsorbing member 22 is not completely in contact with the side wall surfaces 21, it can be expected that the side wall surface flow is substantially attenuated. As another attachment method of the bottom dross adsorbing member 22, a method of attaching and integrating with the support member of the sink roll is also possible.

  In the present invention, the installation of the bottom dross adsorbing member in the plating bath is performed such that at least a part of the bottom dross adsorbing member 22 in the plating bath 3 is separated at the lower portion of the sink roll, as shown in FIG. .

  That is, there is no bottom dross adsorbing member in the vicinity of the center of the sink roll, and in other words, a pair or a plurality of pairs of bottom dross adsorbing members installed on both side wall surfaces are arranged at intervals. Means.

  The reason is that if the bottom dross adsorbing member is placed over the entire length of the sink roll, dross drifting near the center of the sink roll may settle and accumulate on the bottom dross adsorbing member and then roll up. is there.

  In the vicinity of the center of the sink roll, the flow of the hot dip metal is slower than in the vicinity of both end portions, so that the risk of the bottom dross rolling up is small even without the bottom dross adsorbing member.

  Also, if the bottom dross adsorbing member lies under the center of the sink roll, when starting the plating operation, the work of winding the tip of the steel plate around the sink roll, so-called threading work becomes complicated.

  The second embodiment of the present invention (the invention of claim 2) is such that the side wall surfaces in the first embodiment are a front wall surface and / or a rear wall surface (hereinafter referred to as a front / rear wall surface). FIG. 7 shows an example in which a bottom dross suction plate is installed on the front wall surface of the sink roll. In the third embodiment (invention of claim 3), as shown in FIG. 8, for example, bottom dross adsorption plates are installed on both side walls and front / rear wall surfaces, that is, four-side wall surfaces around the sink roll. .

  When the moving speed of the steel plate and the rotation speed of the sink roll are increased, the flow of hot-dipped metal is also generated in the front of the hot dipping bath (outside area of the steel plate) and rearward (incoming area of the steel plate). There is a risk of rolling up.

  In addition, as the flow of the side portion is suppressed by the bottom dross adsorbing member, the hot-dipped metal that has been obstructed by the flow loses the escape field and may converge forward or backward to form a new winding loop. .

  These embodiments aim to suppress the flow of hot dipped metal from multiple directions by installing a bottom dross adsorbing member on at least the front wall surface and / or the rear wall surface. Since the principle and function are the same as those of the first embodiment, the first embodiment will be described below as an example.

  5 and 6 show that the distance from the bottom of the hot dipping bath to the both side walls of the hot dipping bath where the shaft end of the sink roll faces exceeds 0.8 times the distance between the bottom and the lower end of the sink roll. It is a figure which shows the aspect which installed the bottom dross adsorption member in which a part of bottom dross adsorption member is located in the position which is not.

  In the present invention, the bottom dross is captured by the upflow or downflow of the bath flow, so that the bath flow generated by the rotation of the sink roll is installed at a position where the downflow or upflow flows along the side wall surface. It is desirable. That is, the bottom dross adsorbing member is installed at a position lower than the lower end of the sink roll, preferably at a position where the distance from the bottom of the hot dipping bath does not exceed 0.8 times the distance between the bottom and the lower end of the sink roll. It is preferable.

  FIG. 5 shows a mode in which the bottom dross adsorbing member provided with a step is installed such that the portion in contact with the side wall surface is higher than the lower end of the sink roll. However, as shown in FIG. 5, even if a part of the bottom dross adsorbing member is installed at a position exceeding 0.8 times, at least the other part may be installed at a position not exceeding 0.8 times. Thus, it is possible to effectively capture and suppress the upward flow or the downward flow along the wall surface. In particular, it is more preferable that a part of the bottom dross adsorbing member located below the sink roll is installed at a position not exceeding 0.8 times.

  The embodiment shown in FIG. 6 is also based on the same idea as the embodiment shown in FIG. 5, except that the bottom dross adsorbing member is arranged on the support member of the sink roll.

  As described above, the bottom dross adsorbing member of the present invention is intended to capture the upward flow or the downward flow along the wall surface and separate and capture the bottom dross. There is no need to be single.

  The shape and arrangement of the openings of the porous plate used for the bottom dross adsorbing member used in the present invention are not particularly limited. A material having a regular circular opening, such as a punching metal, or a wire mesh shape can be appropriately selected. In order to prevent the captured bottom dross from flowing out again, the member may be subjected to processing such as turning over.

However, the total area of the openings is 20 to 80% (opening ratio) of the area of the bottom dross adsorbing member facing the bath (area including the openings), and the average area per opening is It is preferable to be 5000 mm ² or less.

  This is because if the open area ratio is less than 20%, the bath flow is excessively suppressed, and the amount of plating metal passing through the bath flow itself is reduced, and the bottom dross cannot be captured accordingly.

  On the other hand, if the hole area ratio exceeds 80%, the function of changing the direction of the bath flow is small even if the openings are shifted and the bottom dross cannot be captured.

If the average area per opening exceeds 5000 mm ² , it is difficult to uniformly attenuate the flow rate of the bath flow, which is not preferable.

The lower limit of the average area per opening is not particularly limited, but the size of the bottom dross is usually about several μm to several mm, so the area of the opening is such that the bottom dross can easily pass through. The area may be, for example, 100 mm ² or more.

  Various types of steel plates can be used as the steel plate used for the porous plate of the bottom dross adsorbing member. In particular, if a steel plate with an uneven surface (for example, an embossed steel plate with an uneven surface or a corrugated steel plate with a corrugated surface) is used, the direction of the bath flow can be changed even with one sheet. Can be captured. Of course, it goes without saying that bottom dross can be captured more effectively by stacking two or more sheets.

  Further, the bottom dross adsorbing member is not limited to being composed of a perforated plate. For example, members that have the effect of attenuating the flow rate by changing the direction of the bath flow, such as fibrous members, cotton-like members, mesh-like members, members filled with a plurality of balls or pellets in a basket If so, it can be used freely.

  For example, when a ball-shaped steel material having a diameter of 20 mm to 100 mm is filled between a wire mesh made of a steel material, the bottom dross in the bath flow can be captured while passing through the ball-shaped steel material. However, if the diameter of the ball-shaped steel material is smaller than 20 mm, the amount of plating metal passing through the bottom dross adsorbing member decreases, and the bottom dross cannot be captured sufficiently. On the other hand, if the diameter of the ball-shaped steel material is larger than 100 mm, the function of changing the direction of the bath flow is small, and the bottom dross cannot be separated and captured sufficiently.

  Further, for example, if the bottom dross adsorbing member is made of one or a plurality of mesh objects having a space ratio of 20 to 80% defined by JISG3556, the bottom dross in the bath flow can be sufficiently captured by the mesh objects by the filtering function. it can.

  The size of the bottom dross adsorbing member of the present invention may be a size that can effectively capture and rectify an upward flow or a downward flow flowing along the wall surface, and is appropriately determined according to the size of the hot dipping equipment to be used. It becomes.

  A method for determining the size of the bottom dross adsorbing member installed on the side wall surface will be described with reference to FIG.

  The width dimension W of the bottom dross adsorbing member is preferably set shorter than the distance X from the side wall surface to the steel plate end and longer than the distance Z from the side wall surface to the sink roll support member. In the case of W ≧ X, there is a risk of hindering the sheet passing work of the steel sheet performed when the sink roll is replaced. On the other hand, in the case of W ≦ Z, the upward flow or the downward flow flowing along the wall surface in the bathtub cannot be captured effectively, and a sufficient rectifying effect may not be obtained. Therefore, it is desirable that the width dimension W of the bottom dross adsorption member satisfies Z <W <X. In addition, the width | variety of the steel plate at the time of calculating | requiring the distance X shall be the narrowest width | variety among process target steel plates.

  The depth dimension L of the bottom dross adsorbing member is desirably set longer than 0.7 times the sink roll diameter D and shorter than the depth dimension Y inside the plating bath. In the case of L ≦ 0.7D, the side jet generated from the winding portion of the sink roll cannot be covered, and the upflow or the downflow may not be sufficiently effectively captured. On the other hand, when L ≧ Y, the bottom dross adsorbing member cannot be physically stored in the plating bath. Therefore, it is desirable that the depth dimension L of the bottom dross adsorption member satisfies 0.7D <L <Y.

  In addition, about the installation position of the front-back direction of a bottom dross adsorption member, it is especially preferable to install in the position which the center of the bottom dross adsorption member shifted | deviated to the front side (steel plate exit side) rather than just under a sink roll.

  The material of the steel material used for the bottom dross adsorption member is not particularly limited. However, from findings from experiments conducted by the inventors, materials with high corrosion resistance such as stainless steel and ceramics have less erosion by plating metal than ordinary steel materials and have a longer equipment life. Compared to the depositability on stainless steel, ordinary steel material, so-called carbon steel, is better, and it is desirable to use carbon steel from the viewpoint of the ability to capture dross. The reason is not clear, but when the bottom dross starts to be captured by the adsorption apparatus of the present invention, the amount of the bottom dross adsorbed within the same time increases at an accelerated rate. This is thought to be because it reacts with the Fe content in the dross and is easily adsorbed.

  When the amount of bottom dross trapped in the bottom dross adsorbing member increases, the adsorbing member becomes clogged and the plated metal does not pass through, but since the purpose is to capture the bottom dross, it is captured rather quickly and clogged. Need to be replaced before. Therefore, it is not necessary to consider the life of the bottom dross adsorbing member so much, and it is sufficient to manufacture it with ordinary steel.

  In the present invention in which the bottom dross adsorbing member is installed as described above, as shown in FIGS. 2 (a) and 2 (b), the bottom dross can be obtained regardless of whether the steel plate to be processed is a wide material or a narrow material. The adsorbing member can effectively capture the upward flow or downward flow that flows along the wall surface in the bathtub, and a sufficient rectifying effect can be obtained to attenuate the flow velocity of the bath flow. The bottom dross can be separated and supplemented, and the bottom dross that has settled on the bottom of the bathtub can be remarkably prevented from rolling up.

Hereinafter, the present invention will be described based on examples.
The bottom dross adsorption member of the following conditions was installed in the continuous hot dip galvanizing bath, the continuous hot dip galvanization process was performed, and the bottom dross adhesion incidence rate to the plated steel plate by the rolling up of the bottom dross was measured. The results are shown in Table 1.

[Specifications of bottom dross adsorption member]
Shape / material: Two layers of 8 mm thick austenitic stainless steel plate. Presence / absence of holes: Implemented in two levels: “porous” and “no hole”. In the case of porous, the opening ratio is 50%, and the average area per hole is 2.0 × 10 ³ mm ² .
Installation conditions: In the plating bath (width 3600 mm x depth 4000 mm), the distance (distance) from the bottom of the plating bath to the lower end of the sink roll is 1200 mm, and the bottom dross adsorbing member is 600 mm from the lower end of the sink roll as a standard. .
The bottom dross adsorption member installed on the side wall surface is in contact with the side wall surface (gap = 0 mm), the gap between the wall surface = 10 mm, and the gap between the wall surface = 100 mm.
The bottom dross adsorbing member installed on the side wall is implemented under the conditions of “separation” and “no separation”.
For example, “1600 mm apart” refers to a state in which a pair of bottom dross adsorbing members installed on both side wall surfaces are installed at an interval of 1600 mm below the sink roll. “No separation” means that the bottom dross adsorbing members are connected to each other without being spaced apart.

〔Test conditions〕
Plating bath: Hot-dip zinc Plate speed: 150 m / min Test coil: Plate thickness 0.6 mm x Plate width 1,200 mm Cold rolled ordinary carbon steel coil (narrow material)
Plate thickness 0.6mm x Plate width 1,800mm Cold rolled ordinary carbon steel coil (wide material)

About 40 test coils were plated on the hot rectifying plates having different conditions, respectively, on the hot dip galvanizing line, and the bottom dross adhesion occurrence rate of the steel sheet was determined by the following formula. The presence or absence of bottom dross adhesion was determined by visual inspection.
Rate of occurrence of bottom dross adhesion (%) = (number of coils with bottom dross adhesion / number of coils tested) x 100

The pass / fail determination regarding the bottom dross adhesion was performed according to the following criteria based on the average value of the bottom dross adhesion occurrence rate in the narrow and wide materials.
Pass (excellent): Less than 6% Pass (good): 6% or more and less than 8% Pass (possible): 8% or more and less than 12% Fail: 12% or more

  Nos. 1 to 3 in Table 1 represent the case where the end of the bottom dross adsorbing member is installed on the side wall surface, and the bottom dross adsorbing member is installed separately at the lower part of the sink roll. In the first embodiment of the present invention, Applicable. The dross adhesion occurrence rate of the steel plate at this time is within the acceptable range. In No.4, since the gap with the side wall surface was too wide, most of the bath flow seems to have passed through this gap and the bottom dross could not be captured. No. 8 had no holes in the current plate, so that it was considered that the bottom dross was rolled up during the plating process of the wide material. In No5, No6, No7, and No12, the installation conditions of the bottom dross adsorbing member were those with no separation, and the installation height was too high, and none of the bottom dross roll-up could be sufficiently suppressed. No13 was a case where a bottom dross adsorbing member was not installed, and the result was inferior. No. 9 is a case where the porous rectifying plate is installed on the side / front wall surface, and No. 10 is a case where the porous rectifying plate is installed on the side / front / rear wall surface, and the second embodiment shown in FIGS. Applicable. Thus, it was confirmed that the effects of the present invention can be sufficiently obtained even when the bottom dross adsorbing member is installed on a side wall other than the side wall surface.

  Table 2 shows the result of the test conducted on the bottom dross adsorbing member having a step shown in FIG. 5 in the present invention. The height of the higher part of the baffle plate is defined as “installation height 1” and the height of the lower part is defined as “installation height 2”. It represents the height of each.

[Specifications of bottom dross adsorption member]
Shape / material: 2 layers of 8 mm thick austenitic stainless steel plates. Presence / absence of holes: Use a porous rectifying plate with an aperture ratio of 50% and an average area of 2.0 × 10 ³ mm ² per hole.
Installation conditions: Installation test conditions and the like were performed in the same manner as described above while in contact with both side wall surfaces (gap = 0 mm).

  No. 14 to No. 18 in Table 2 set the installation height 2 to a certain value (the ratio of the installation height from the bathtub bottom to the distance from the bathtub bottom to the roll (hereinafter “height ratio”) = 0.4). The effect of height 1 was investigated. Even if installation height 1 exceeds 0.8 in height ratio, No17 and No18 are acceptable ranges, but when installation height 2 exceeds 0.8 in height ratio as in No23 I found out that it would fail.

  Table 3 shows the results of tests performed on the dimensions of the bottom dross adsorption member installed on the side wall surface.

[Specifications of bottom dross adsorption member]
Shape / material: 2 layers of 8 mm thick austenitic stainless steel plate. Presence / absence of holes: 50% open area, average area of 2.0 × 10 ³ mm ² per hole
Installation conditions: Installed at a height of 600 mm from the bottom end of the sink roll and 600 mm from the bottom of the plating bath. A bottom dross adsorbing member, part of which is separated from the lower part of the sink roll, is installed on both side walls of the hot dipping bath so that the member is in contact with the wall surface.
Other test conditions are the same as in Table 1.

  FIG. 9 shows where each symbol indicates. No24-No33 is the result of having fixed the dimension (Y, L, D) regarding the depth direction of a bathtub, and having investigated the relationship of the dimension (Z, W, X) of the width direction.

  As described above, in the case of W ≦ Z as in No. 24 and 25, it is not possible to effectively capture the upward flow or the downward flow flowing along the wall surface in the bathtub, and a sufficient rectifying effect is obtained. Therefore, it seems that dross adhesion to the steel plate increased. In the case of W ≧ X of No. 32 and 33, the dross adhesion to the steel plate is within the range of acceptance, but this also interferes with the plate passing work of the steel plate performed at the time of replacing the sink roll as described above. Conceivable.

  No34-No43 is the result of having fixed the dimension (Z, W, X) regarding the width direction of a bathtub, and investigated the relationship of the dimension (Y, L, D) of a depth direction.

  As described above, when L <0.7D, the lateral jet generated from the winding portion of the sink roll cannot be covered, and the upward flow or the downward flow cannot be captured effectively. It was confirmed from the experimental results that

  Table 4 shows the results of tests performed on the hole area ratio of the bottom dross adsorbing member and the type of adsorbing member.

[Specifications of bottom dross adsorption member]
Shape / material: 2 layers of 8 mm thick austenitic stainless steel plate Installation conditions: Installed at a height of 600 mm from the bottom of the sink roll and 600 mm from the bottom of the plating bath. A bottom dross adsorbing member, part of which is separated from the lower part of the sink roll, is installed on both side walls of the hot dipping bath so that the member is in contact with the wall surface.
Other test conditions are the same as in Table 1.

  No44-No51 investigated the influence by the aperture ratio of a perforated plate. As described above, if the hole area ratio is less than 20%, the bath flow is excessively suppressed, so the amount of plating metal flowing through the bath flow itself decreases, and the bottom dross cannot be captured accordingly. Therefore, dross adheres to the steel plate. On the other hand, when the hole area ratio exceeds 80%, even if the opening is shifted, the function of changing the direction of the bath flow is small, and therefore it is assumed from the experimental results that the bottom dross cannot be captured. .

  Nos. 52 and 53 are the results of the experiment using corrugated steel plates, and Nos. 54 and 55 are the results obtained by providing openings in the staggered Yamaya steel plate. It was confirmed that there was a predetermined effect even when those having irregularities on the surface were used.

  No. 56 to No. 59 use ball-shaped steel materials as adsorbing members. It can be estimated from the experimental results that the dross in the bath flow is captured in the range of the ball diameter of 20 to 100 mm. Moreover, No60 shows the experimental result when a fibrous steel material is used instead of a ball-shaped steel material. It was confirmed that even when the fibrous steel material was used for the adsorbing member, there was a predetermined effect.

These are figures which show the 1st embodiment of this invention. These are figures which show the aspect of the bath flow which arises in 1st Embodiment of this invention. (A) shows the case of a wide material, and (b) shows the case of a narrow material. These are the schematic diagrams which show the separation capture of the bath flow and bottom dross in the bottom dross adsorption member in the first embodiment of the present invention. These are figures which show the installation aspect of a porous baffle plate. (A) shows the aspect which suspends a porous rectification | straightening plate via a support member, (b) shows the aspect which installs a porous rectification | straightening plate via a support member. These are figures which show the example of the bottom dross adsorption member which provided the level | step difference. These are figures which show the example of the bottom dross adsorption member which provided the level | step difference. These are figures which show the example of the 2nd embodiment of this invention. These are figures which show the example of the 3rd embodiment of this invention. These are the figures explaining the method of determining the dimension of the rectification | straightening member installed in a side wall surface. (A) shows the side of a continuous hot dip galvanizing apparatus, (b) shows the front. These are the figures which show the outline of a general continuous hot dip galvanizing apparatus. These are figures which show the aspect of the bath flow produced in the apparatus shown in FIG. (A) shows the case of a wide material, and (b) shows the case of a narrow material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 1 'Plated steel plate 2 Snout 3 Hot dip galvanizing bath 4 Sink roll 5 Support roll 6 Plating bath surface 7 Gas wiping nozzle 8 Damping device 9 Alloying heating furnace 10 Bottom dross 11 Power acting in the radial tangential direction 21 Hot dip galvanizing bath Side wall 22 Bottom dross adsorbing member 23 Support member 24 Perforated plate A, B Bath flow direction

Claims (12)

A bottom dross adsorbing member partially spaced apart at the lower part of the sink roll is provided on both side wall surfaces of the hot dip bath facing the end of the sink roll shaft, and the member is in contact with the wall surface or has a gap of 100 mm or less from the wall surface. A bottom dross adsorption device that adsorbs bottom dross in hot dipped metal that is installed to have a state and rises or falls along the wall surface,
The bottom dross adsorbing device, wherein the member is formed by stacking a plurality of steel plates having openings at predetermined intervals so that the openings of the steel plates do not overlap. Of the wall surface of the hot dip bath that extends in the axial direction of the sink roll , the steel plate that is the material to be plated enters the front wall surface located in the exit area where the hot dip plate separates from the hot dip bath and / or enters the hot dip bath. On the rear wall surface located in the region , the bottom dross adsorbing member is installed so that the member is in contact with the wall surface or has a gap of 100 mm or less from the wall surface, and the hot dipping is performed along the wall surface. A bottom dross adsorption device that adsorbs bottom dross in metal,
The bottom dross adsorbing device, wherein the member is formed by stacking a plurality of steel plates having openings at predetermined intervals so that the openings of the steel plates do not overlap.   The bottom dross adsorbing member is installed on both side wall surfaces of the hot dipping bath so that the member contacts the wall surface or has a gap of 100 mm or less with the wall surface, and rises or descends along the wall surface. The bottom dross adsorbing device according to claim 2, wherein the bottom dross in the hot dipped metal to be adsorbed is adsorbed.   In the bottom dross adsorption device, the bottom dross adsorption member is installed such that a part of the bottom dross adsorption member is located at a position where the distance from the bottom of the hot dipping bath does not exceed 0.8 times the interval between the bottom and the sink roll lower end. The bottom dross adsorption device according to any one of claims 1 to 3.   The width W of the bottom dross adsorbing member installed on the side wall surface of the hot dipping bath is not more than the distance X from the side wall surface to the end of the steel plate, and not less than the distance Z from the side wall surface to the sink roll support member. The bottom dross adsorption device for a plate-like member according to any one of claims 1 to 4.   The depth dimension L of the bottom dross adsorbing member installed on the side wall surface of the hot dipping bath is 0.7 times or more the diameter of the sink roll and less than or equal to the depth y inside the hot dipping bath. Item 6. A bottom dross adsorption device for a plate-like member according to any one of Items 1 to 5.   The bottom dross adsorption member has a plurality of openings, and the total area of the openings is 20 to 80% of the total area of the steel plate of the bottom dross adsorption member. A bottom dross adsorption device for plate-like members according to claim 1. The plate of the metal plate according to any one of claims 1 to 7, wherein the bottom dross adsorbing member has a plurality of openings, and an average area per opening is 5000 mm ² or less. -Shaped member bottom dross adsorption device.   The bottom dross adsorbing device for a plate-like member according to any one of claims 1 to 8, wherein the bottom dross adsorbing member has an uneven shape on one or a plurality of surfaces.   The plate-like member according to any one of claims 1 to 6, wherein the bottom dross adsorbing member is a ball-shaped steel material having a diameter of 20 to 100 mm filled between a plurality of steel meshes. Bottom dross adsorption device.   The bottom dross adsorbing member according to any one of claims 1 to 6, wherein the bottom dross adsorbing member is one or a plurality of net-like objects having a space ratio of 20 to 80% defined by JISG3556. apparatus.   The said bottom dross adsorption member is made of carbon steel, The bottom dross adsorption apparatus of the plate-shaped member in any one of Claims 1-11 characterized by the above-mentioned.

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