JP2005248298A - Support roll in non-actuated molten metal bath - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a support roll in a non-actuated molten metal bath which is immersed in a continuous molten metal bath when performing hot dip plating of zinc, aluminum or the like on a steel plate. <P>SOLUTION: In the support roll in the molten metal bath in a hot dip plating line, the support roll is non-actuated, self-fluxing alloy is thermal-sprayed on an outer circumferential part of a sleeve coming into slidable contact with a support roll bearing, and a bush having a projected shape in the cross section with an inner surface being mirror-finished is provided in the support roll in the non-actuated molten metal bath. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a roll used by being immersed in a continuous molten metal bath when a molten metal plating such as zinc or aluminum is applied to a steel sheet, and more particularly to a support roll in a non-driven molten metal bath.

  Conventionally, as a plating apparatus in a continuous molten metal plating line for applying molten metal plating such as zinc or aluminum to a steel sheet, as shown in FIG. 4, a steel sheet having a cleaned and activated surface is immersed in a molten metal plating tank. A method of obtaining a molten metal plated steel sheet by changing the advancing direction with a sink roll in a bath and pulling it upward and controlling the amount of metal adhesion by gas wiping is performed. That is, FIG. 4 is a diagram showing a configuration of a general molten metal plating line facility. As shown in this figure, a sink roll 3 and a pair of support rolls 4 for continuously passing a steel plate 1 to be plated are installed in a molten metal plating bath 2. The sink roll 3 is disposed at the bottom of the molten metal plating bath 2 and changes the traveling direction of the steel plate 1 sent into the bath to the upper bath surface side.

  In general, the driving power is applied to the rotational power of the sink roll 3 by the traveling movement of the steel plate. Moreover, a pair of support roll 4 is provided in the position near the bath surface after passing the sink roll 3, and is driven via the spindle by an external motor. The pair of support rolls 4 holds the steel plate 2 so as to maintain the pass line of the steel plate 1 and corrects the warpage of the steel plate 1 that occurs when it passes through the sink roll 3. A gas wiping nozzle 5 for uniformly controlling the plating thickness is installed in the upper part of the molten metal plating bath 2. In addition, as the bearings for the sink roll 3 and the support roll 4, sliding bearings and rolling bearings are used.

  FIG. 5 is a schematic view showing the structure of a sliding bearing used in a conventional molten metal plating bath. As shown in this figure, the roll shaft 6 of the support roll 4 is configured to be supported by a bearing 8 provided on the arm 7. The roll shaft 6 slides and rotates while being in contact with the inner peripheral surface of the cylindrical bearing 8 over the width L. Since the bearing 8 uses molten metal as a lubricant, the inner diameter of the bearing 8 is made larger than the outer diameter of the roll shaft 6 so that a gap D is formed with the roll shaft 6.

  In the structure as described above, the bearing is subject to significant wear on the upper part due to erosion caused by molten metal and mechanical sliding, requiring replacement of the bearing in a short cycle, resulting in reduced productivity and increased maintenance costs. It was. Furthermore, rotational vibration is generated due to the wear of the bearing, and the gap between the gas wiping nozzle 5 and the steel plate 1 cannot be kept constant. In order to rotate while being eccentric, the steel plate 1 is vibrated. Due to this vibration, the gap between the gas wiping nozzle 5 and the steel plate 1 varies, and there is a problem that the steel plate 1 cannot be plated with a uniform film thickness.

  In order to solve these problems, for example, as disclosed in Japanese Patent Application Laid-Open No. 2002-241915 (Patent Document 1), even if the rotation shaft of the support roll rotates eccentrically, it immediately returns to normal rotation. As a bearing device in a molten metal bath that has an automatic centering function and can follow a high-speed threading plate with a small sliding resistance, the roll shaft on the inner peripheral surface of the bearing that is in sliding contact with the roll shaft There has been proposed a bearing device in a molten metal bath in which a cross-sectional shape including a convex shape is included, and a minimum inner diameter portion of the inner peripheral surface is flattened on an inner peripheral surface having a convex cross-sectional shape.

  On the other hand, as disclosed in JP-A-7-173593 (Patent Document 2), a rolling roller bearing is provided on the inner peripheral surface of the bearing that is in sliding contact with the roll shaft, and this rolling bearing is once thermally expanded. There has been proposed a roll support device in a molten metal plating bath that prevents an excessive force from being applied to the rolling bearing when it is shrunk as the temperature drops when it is pulled out of the molten metal.

Japanese Patent Laid-Open No. 2002-241915 JP 7-173593 A

  However, in the case of the technique disclosed in Patent Document 1 described above, it has an automatic alignment function and a small sliding resistance, but there is a gap between the sleeve and bush of the shaft, so that it swings around during rotation. There is a problem that vibration occurs and the effect for suppressing this is small. Further, Patent Document 2 relates to an improvement of a roll support device using a rolling bearing, and uses a rolling bearing. Therefore, there is a problem that the structure of the bearing is complicated and the number of parts is large.

  In order to solve the above-described problems, the inventors have made intensive development. In the present state, the upper support roll has a smaller wrapping angle than the lower support roll, so that the pressing force against the steel plate is small and the driving force from the steel plate is small. In particular, since the thin material does not rotate without being driven, it must be driven. This was made non-driven, and a bearing in a molten metal bath was developed in which the friction coefficient between the rotating part and the fixed part was less than 0.2, and the shaft part and the fixed part kneaded and rubbed even when the hanger or roll was deformed. The present invention provides a support roll in a non-driven molten metal bath to which a centering function is added so as not to increase the coefficient.

The gist of the invention is that
(1) In a support roll in a molten metal bath in a molten metal plating line, the support roll is made non-driven, and a self-fluxing alloy is sprayed on the outer periphery of the sleeve that is in sliding contact with the support roll bearing, and the inner surface is mirror-finished A support roll in a non-driven molten metal bath, characterized in that a bush having a convex cross-sectional shape is provided.
(2) A support roll in a non-driven molten metal bath, characterized in that a gap between the bushing and the surface sprayed with the self-fluxing alloy on the outer peripheral portion of the sleeve according to (1) is 0.5 to 1.0 mm.
(3) A support roll in a non-driven molten metal bath, wherein the roughness Ra of the surface of the outer peripheral portion of the sleeve according to (1) sprayed with the self-fluxing alloy is 0.8 μm or less.

(4) The bush described in (1) to (3) is a spherical bearing, and the clearance between the spherical surface of the bush and the arm is 0.05 to 0.3 mm. Support roll in a driven molten metal bath.
(5) A support roll in a non-driven molten metal bath, wherein the surface of the support roll according to (1) to (4) is subjected to high roughness spraying with a roughness Ra of 2 to 6 μm.
(6) The support roll in the non-driven molten metal bath is characterized in that the inside of the end portion of the support roll described in (1) to (5) is hollow.

  As described above, since it is a non-drive support roll to which the alignment function according to the present invention is added, by preventing roll vibration during driving that occurs at an inconstant speed joint, vibration to the steel plate is eliminated. As a result, the accuracy of adhesion amount control is improved, and a very high quality plated steel sheet by high-speed production can be produced.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing a main part of a non-driving support roll according to the present invention. As shown in this figure, roll shafts 6 provided at both ends of the support roll 4 are supported by bearings, respectively, but only one bearing is shown in FIG. The roll shaft 6 of the support roll 4 is supported by a cylindrical bush 9 installed on the arm 7.

  A convex portion 10 is formed on the outer peripheral surface of the cylindrical bush 9. The convex portion 10 has a uniform convex cross-sectional shape including the roll shaft 6. In the convex portion 10, the apex portion 11 having the highest protrusion height is formed at a substantially central portion in the axial direction of the bush 9. In addition, a self-fluxing alloy was sprayed on the outer peripheral portion of the sleeve 12 that was in sliding contact with the support roll bearing, and a bush having a convex cross-sectional shape in which the inner surface of the bush 9 was mirror finished was provided. In addition, even when stellite is built on the inner surface to extend the life, the same effect can be obtained by mirror polishing similarly.

  The self-fluxing alloy spraying referred to in the present invention is a method in which a self-fluxing alloy powder is sprayed and then heated to the melting point of the material to form a weld coating on the surface of the substrate. Here, the self-fluxing alloy refers to an alloy obtained by adding boron or silicon to a nickel-based, cobalt-based, or nickel-chromium-based alloy. In particular, a Co—Cr—W-based self-fluxing alloy is sprayed on the outer periphery of the sleeve. Stellite build-up stellite applied to the inner surface of the bush is an alloy consisting of Co with Cr and W added, with high hardness, excellent wear resistance, and this characteristic regardless of whether it is hot or cold. Is a wear resistant alloy with almost no change. However, the present invention is not particularly limited to this alloy. The surface roughness Ra is set to 0.8 μm or less by thermal spraying of this alloy. If the surface roughness Ra exceeds 0.8 μm, the friction coefficient between the rotating part and the fixed part cannot be made less than 0.2.

  Further, a high roughness sprayed surface 13 is formed on the surface of the support roll 4 main body. The high-roughness sprayed surface 13 is made of, for example, a WC—Co alloy, and the roughness Ra of the sprayed surface is 2 to 6 μm. If the thickness is not 2 μm, the sliding contact with the steel plate is small, and the support roll 4 body rotates poorly. Further, if the roughness Ra exceeds 6 μm, the steel sheet surface is likely to be damaged, and the appearance of the product is impaired. Therefore, the range is set to 2 to 6 μm.

  Furthermore, by forming a hollow 14 in the inner end of the support roll 4 main body, the support roll main body can be reduced in weight, and its own weight and buoyancy can be balanced to perform automatic rotation according to the steel plate speed smoothly. is there. However, if the inside of the support roll body is all hollow, it will be reduced in terms of strength and the buoyancy in the bath will be too large, so the resistance at the bearing part will increase, so it was limited to both ends. . It is also desirable to make the inner end hollow such that its own weight and buoyancy cancel.

  FIG. 2 is an overall plan view of the non-driving support roll according to the present invention. As can be seen from this figure, the inside of the support roll 4 main body is formed with the hollow 14 at the end as described above, so that the weight of the entire support roll main body can be reduced by this partial hollow. I can do it. This makes it possible to balance the weight and buoyancy in the metal plating bath.

  FIG. 3 is a detailed view of a support portion on which the roll shaft according to the present invention is supported by a bearing. As shown in FIG. 3, a self-fluxing alloy layer 15 having a surface roughness Ra of 0.8 μm or less as described above is obtained by spraying a self-fluxing alloy on the outer periphery of the sleeve 12 that is in sliding contact with the support roll bearing. Formed. On the other hand, the inner surface of the bush 16 having a convex cross-sectional shape is mirror-finished after the inner surface of the bush is built up to form the inner cylinder portion 16. In this case, the gap d between the self-fluxing alloy layer 15 and the inner cylinder portion 16 is set to 0.5 to 1.0 mm. The reason why the gap is set to 0.5 to 1.0 mm is that if it is less than 0.5 mm, the difference in expansion due to the difference in thermal expansion coefficient between the self-fluxing alloy layer 15 and the inner cylinder portion 16 cannot be absorbed. Biting of dross occurs due to the relationship of the dross particle size in the plating bath. On the other hand, if it exceeds 1.0 mm, vibration during rotation cannot be sufficiently suppressed. Therefore, the range is set to 0.5 to 1.0 mm.

  Next, the outer periphery of the bush is a spherical bearing, and the gap d ′ between the outer periphery of the bush and the arm is 0.05 to 0.3 mm. That is, by forming a convex spherical bearing on the outside of the bush 9, the gap d 'with the arm can be reduced. On the other hand, when the gap d ′ is as small as possible, the core of the roll is determined, and it is effective in preventing vibration from the roll to the steel sheet by suppressing the swing of the roll. Therefore, the minimum gap is 0.05 mm, and if it exceeds 0.3 mm, the vibration preventing effect on the steel sheet is not sufficient. In addition, double sliding occurred with the inner sliding portion, and as a result of the rotation experiment, the wear coefficient increased on the contrary. Therefore, the range was set to 0.05 to 0.3 mm.

  As described above, the support roll is a non-driving support roll, a self-fluxing alloy layer is formed on the outer periphery of the sleeve that is in sliding contact with the support roll bearing, and the regulation of the roughness Ra and the inner surface of the self-fluxing alloy layer are defined. The gap between the mirror-finished bush is restricted, the gap between the outer peripheral spherical surface of the bush and the arm is restricted, the roughness Ra of the surface of the support roll body is restricted, and the end of the roll body is hollow. This prevents roll vibration during driving that occurs at unequal speed joints, eliminates vibrations on the steel sheet, improves the accuracy of molten metal adhesion control, and provides high-quality plated steel sheets by high-speed production. Could be manufactured.

It is the schematic which shows the principal part of the non-driving support roll which concerns on this invention. It is a plane whole view of the non-drive support roll concerning the present invention. It is detail drawing of the support part by which the roll axis | shaft which concerns on this invention is supported by a bearing. It is a figure which shows the structure of a general molten metal plating line equipment. It is the schematic which shows the structure of the sliding bearing used for the conventional molten metal plating bath.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Molten metal plating bath 3 Sink roll 4 Support roll 5 Gas wiping nozzle 6 Roll shaft 7 Arm 8 Bearing 9 Bush 10 Convex part 11 Apex part 12 Sleeve 13 High-roughness sprayed surface 14 Hollow 15 Self-fluxing alloy layer 16 Inside Tube portion L Width D, d, d 'Clearance
Patent applicant: Nippon Steel Corporation
Attorney Attorney Shiina and others 1

Claims (6)

In a support roll in a molten metal bath in a molten metal plating line, a cross-sectional shape in which the support roll is non-driven, and a self-fluxing alloy is sprayed on the outer peripheral portion of a sleeve that is in sliding contact with the support roll bearing, and the inner surface is mirror-finished A support roll in a non-driven molten metal bath, characterized in that a convex bush is provided. A support roll in a non-driven molten metal bath, wherein a gap between the bushing and the surface of the sleeve outer peripheral portion sprayed on the sleeve outer periphery according to claim 1 is set to 0.5 to 1.0 mm. A support roll in a non-driven molten metal bath, wherein the roughness Ra of the surface of the sleeve outer peripheral portion sprayed with the self-fluxing alloy according to claim 1 is 0.8 μm or less. In the non-driven molten metal bath, the outer periphery of the bush according to claim 1 is a spherical bearing, and the gap between the outer periphery of the bush and the arm is 0.05 to 0.3 mm. Support role. A support roll in a non-driven molten metal bath, wherein the surface of the support roll according to claim 1 is sprayed with a high roughness of a roughness Ra of 2 to 6 μm. A support roll in a non-driven molten metal bath, wherein the inside of the end portion of the support roll according to claim 1 is hollow.

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