JP2004244658A - Roll for continuous hot dip metal plating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roll for continuous hot dip metal plating in which the fall-off of roll axis parts from a roll barrel part during use is prevented, and the generation of cracks on the joints between each roll axis part and the roll barrel part is suppressed by improving the conventional roll for continuous hot dip metal plating. <P>SOLUTION: In the roll for continuous hot dip metal plating in which the roll barrel part and the roll axis part are formed so as to be a hollow shape by ceramics, and the roll axis parts are jointed to both the end parts of the roll barrel part, a projecting part and a spiral screw part are formed on the joints in the outer circumferential faces of the roll axis parts, recessed parts corresponding to the projecting parts and spiral screw parts are formed on the joints in the inner circumferential faces of the roll barrel part, the respective screw parts are fitted, and the projecting part of each roll axis part is fitted and joined to each recessed part of the roll barrel part. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a roll for continuous hot-dip metal plating such as a sink roll or a support roll that is immersed in a hot-dip metal bath when a steel plate is subjected to metal plating such as zinc plating.
[0002]
[Prior art]
The continuous hot-dip metal plating apparatus performs continuous plating while immersing a steel sheet whose surface has been cleaned and activated in a molten metal bath such as zinc and running. At that time, a roll for continuous molten metal plating such as a sink roll or a support roll is immersed in a molten metal bath for use. In the case of molten zinc, the bath temperature will be about 480 ° C. The sink roll is disposed at the bottom of the molten metal bath and changes the traveling direction of the steel sheet sent into the bath toward the upper surface of the bath. Usually, a driving torque is given to the rotational power of the sink roll by the traveling movement of the steel plate. The support roll is composed of a pair of rolls and is provided at a position near the bath surface after passing through the sink roll, is driven by an external motor via a spindle, sandwiches the steel plate, keeps the steel plate pass line, and Corrects the warpage of the steel sheet that occurs when the steel sheet passes through the roll.
[0003]
As a conventional roll for continuous hot-dip metal plating, for example, in Patent Document 1, a roll body and a roll shaft are formed in a hollow shape using silicon nitride ceramics, and the roll shaft is fitted to both ends of the roll body. A roll for continuous hot-dip metal plating joined by screwing is described. This has the advantages of being excellent in corrosion resistance, heat resistance, and abrasion resistance, making the roll lightweight and easy to rotate, preventing cracking when the roll is pulled up from the bath, and making the entire roll longer with ceramics.
[0004]
Patent Document 2 discloses that a roll body and a roll shaft are formed in a hollow shape by using silicon nitride ceramics, and the roll shaft is screwed to the inner surface of the roll body, and flat portions are formed at the crests and valleys of the screw. A roll for continuous hot metal plating is described. It also describes that a buffer material such as a heat-resistant inorganic adhesive having a coefficient of thermal expansion close to that of ceramics is interposed between screws, or plating or spraying is performed on the surface of the screws. This has the advantage that the breakage of the screw can be prevented in addition to the advantages of the aforementioned documents.
[0005]
[Patent Document 1]
JP 2001-89836 A [Patent Document 2]
JP-A-2002-161347
[Problems to be solved by the invention]
In the case of a support roll for continuous hot-dip metal plating, the drive shaft of the roll is rotated by a spindle shaft that drives the roll, while the roll body also receives frictional force from the steel plate and is rotated in the traveling direction of the steel plate. However, since the spindle shaft for driving the roll and the clutch portion of the roll take the form of a universal joint, even if the spindle shaft always rotates uniformly, the roll drive shaft does not rotate uniformly, causing speed fluctuation.
[0007]
Due to the speed fluctuation, the conventional continuous hot-dip metal plating roll has a problem in that the screw connection of the roll body is loosened, and the roll shaft is easily detached from the roll body.
[0008]
Also, when assembling the roll body and the roll shaft, bonding the roll in a metal plating bath, or when applying torque during actual use, the screw connection between the roll body and the roll shaft is performed. However, there still remains a problem that stress concentration occurs in the joint and cracks are likely to occur in the screw joint.
[0009]
In view of such circumstances, the present invention has been made to improve a conventional roll for continuous hot-dip metal plating, prevent the roll shaft from coming off the roll body during use, and improve the roll shaft and the roll body. It is an object of the present invention to provide a roll for continuous hot-dip metal plating that suppresses occurrence of cracks at a joint with a portion.
[0010]
[Means for Solving the Problems]
The roll for continuous hot-dip metal plating according to the first aspect of the present invention is a roll for continuous hot-dip metal plating in which a roll body and a roll shaft are formed in a hollow shape by using ceramics and a roll shaft is joined to both ends of the roll body. A convex portion and a helical screw portion are formed at the joint portion on the outer peripheral surface of the roll shaft portion, and a concave portion and a helical screw portion corresponding to the convex portion are formed at the joint portion on the inner peripheral surface of the roll body portion. The screw portions are fitted to each other, and the convex portion of the roll shaft portion is fitted and joined to the concave portion of the roll body portion.
[0011]
The roll for continuous hot-dip metal plating of the second aspect of the present invention has a concavo-convex portion reversed from that of the first aspect of the present invention. The roll body and the roll shaft are formed in a hollow shape by using ceramics. In a continuous molten metal plating roll in which a roll shaft is joined to both ends, a convex portion and a helical screw portion are formed at the joint at the inner peripheral surface of the roll body, and at the joint at the outer peripheral surface of the roll shaft. A helical screw portion is formed with a concave portion corresponding to the convex portion, the respective screw portions are fitted to each other, and the convex portion of the roll body portion is fitted to and joined to the concave portion of the roll shaft portion. And
[0012]
In the present invention, the screw portion is formed to have a gentle curved cross section. The screw portion has a maximum height of 10 to 1000 μm. Further, the convex portion has a corner portion formed into a curved surface. The convex part has a maximum height of 10 to 1000 μm. Further, the ceramic is a silicon nitride ceramic.
[0013]
[Action]
The roll for continuous hot-dip metal plating of the present invention can prevent the roll shaft from rotating once even when a rotational torque is applied during use, and can prevent the roll shaft from coming off the roll body. As the means for fitting the roll shaft and the roll body, shrink fitting or cold fitting is desirable.
[0014]
Further, in order to avoid stress concentration, it is desirable that the helical screw portion is formed with a gentle curved surface with a sharp corner removed. Thereby, it is possible to prevent the occurrence of cracks at the joint between the roll shaft and the roll body. It is desirable that the maximum height of the threaded portion is 10 to 1000 μm. If the maximum height is less than 10 μm, the bonding and fixing effect is not sufficient.
[0015]
Further, it is preferable that the convex portion has a curved surface (R portion) from which sharp corners are removed in order to avoid stress concentration on the joint. Thereby, it is possible to prevent the occurrence of cracks at the joint between the roll shaft and the roll body. Further, it is desirable that the maximum height of the convex portion is 10 to 1000 μm. If the maximum height is less than 10 μm, the bonding and fixing effect is not sufficient.
[0016]
The roll for continuous hot-dip metal plating of the present invention has sufficient corrosion resistance, heat resistance, and abrasion resistance to the molten metal bath since the roll body and the roll shaft are made of ceramics. Among the ceramics, silicon nitride ceramics such as silicon nitride and sialon are preferable because they have a small thermal expansion coefficient of about 3 × 10 ⁻⁶ / ° C., have excellent thermal shock resistance, and have high temperature and high strength.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example in which sialon ceramics is applied to a support roll of a continuous hot-dip metal plating apparatus will be described. FIG. 3 schematically shows a continuous hot-dip metal plating apparatus. In FIG. 3, a steel sheet 1 delivered from an annealing furnace passes through a snout 2 for preventing oxidation and is immersed in a molten metal bath 3 of zinc. Then, the traveling direction of the steel sheet 1 is changed by the sink roll 4 suspended on the bottom in the molten metal bath 3 and the steel sheet 1 rises to the bath surface side. Next, the steel plate 1 is sandwiched between support rolls 5 composed of a pair of rolls immersed and supported near the bath surface to prevent the steel plate 1 from warping or vibrating. Subsequently, a high-speed gas is blown by the gas wiping 6 above the surface of the molten metal bath 3, and the thickness of the deposited plating is uniformly adjusted by the gas pressure and the spray angle. The plated steel sheet 1 is sent to the next step. This continuous hot-dip metal plating apparatus was equipped with a support roll 5 having the features of the present invention.
[0018]
FIG. 1 is a schematic sectional view of a support roll 5 which is an example of the present invention. In FIG. 1, a support roll 5 is configured by fitting a roll shaft 8 in one end of a hollow cylindrical roll body 7 and another roll shaft 8 in the other end of the roll body 7. . The support roll 5 was formed of sialon ceramics having excellent corrosion resistance, thermal shock resistance, and high-temperature high-strength characteristics with respect to a molten metal bath.
[0019]
In this embodiment, the roll body 7 of the support roll 5 was manufactured as follows. First, α-Si ₃ N ₄ powder having an average particle diameter of 0.8 μm: 87% by weight, Al ₂ O ₃ powder having an average particle diameter of 0.5 μm: 5% by weight, AlN solid solution powder having an average particle diameter of 0.5 μm: 3 % By weight, Y ₂ O ₃ powder having an average particle diameter of 1.0 μm: 5% by weight, and a mixture obtained by adding 0.5% by weight of polyvinyl butyral as a binder per 100 parts by weight of the raw material powder and stirring the mixture, CIP molding was performed at a pressure of 1000 kg / cm ² . Next, sintering was performed at 1750 ° C. for 5 hours under a normal pressure and a nitrogen atmosphere to obtain a sialon ceramic sintered body.
[0020]
The obtained Sialon ceramics sintered body had a density of 99% of the theoretical density, a Vickers hardness Hv at room temperature of 1580, and a bending strength by three-point bending at room temperature of 100 kgf / mm ² . The sintered body was machined into a predetermined shape to produce a hollow cylindrical roll body 7. The roll shaft 8 was also made of a sialon ceramic sintered body, similarly to the roll body 7.
[0021]
FIG. 2 is an enlarged schematic sectional view of the roll body 7 and the roll shaft 8 of the present invention. In FIG. 2, a convex portion 9 having a flat apex and a curved corner is formed on the outer peripheral surface of the roll shaft portion 8. The maximum height of the projection 9 was 200 μm. Further, a spiral screw portion 11 was formed in connection with the convex portion 9.
[0022]
The roll body 7 was formed into a hollow cylindrical body having an outer diameter of 210 mm, an inner diameter of 165 mm, and a length of 1500 mm. The outer peripheral surface of the roll body 7 is a surface through which the steel sheet 1 comes into contact and is passed. Then, a concave portion 10 was formed on the inner peripheral surface of the roll body portion 7 so that the fitting position and size corresponded to the convex portion 9 of the roll shaft portion 8. Further, a spiral screw portion 12 was formed in connection with the concave portion 10.
[0023]
After preparing the roll body 7 and the roll shaft 8, the entire roll body 7 was first heated to about 600 ° C. in an induction heating furnace and held for a predetermined time. Thereafter, the roll shaft 8 brought to the normal temperature state is inserted into the opening end of the roll body 7, and the positions of the protrusion 9 of the roll shaft 8 and the recess 10 of the roll body 7 are adjusted. The support roll of the present invention was assembled by aligning the screw portion 11 and the screw portion 12 of the roll body 7 and shrink-fitting them.
[0024]
The shrink fitting temperature is preferably from 500 to 900C. If the temperature is lower than 500 ° C., it is difficult to perform shrink-fitting operation. If the temperature exceeds 900 ° C., ceramics may be broken by thermal shock due to contact with the roll shaft 8 at room temperature during shrink-fitting. When the roll shaft 8 is joined to the roll body 7, the fitting ratio is preferably set to 0 to 0.02% in order to minimize shrink-fit stress.
[0025]
Further, if metal plating or the like is applied as a cushioning material between the fitting surfaces of the roll shaft portion and the roll body portion, the concentration of stress generated at the joining portion can be further reduced.
[0026]
In the continuous hot-dip metal plating apparatus shown in FIG. 3, the SUS300 stainless steel sheet having a thickness of 2 mm and a width of 1300 mm was subjected to a galvanizing treatment with the support roll 5 of the present invention configured as described above. After that, the support roll 5 showed almost no erosion and wear, the roll shaft did not come off from the roll body during use, and no crack was observed at the joint between the roll shaft and the roll body. . In addition, since the roll's own weight is light, it is easy to rotate, follows the start-up and changes in the running speed of the steel sheet, and suppresses the occurrence of vibration of the roll and the steel sheet due to abrasion. .
[0027]
Although the embodiments of the support roll have been described above, it goes without saying that the present invention can be applied to various rolls for continuous hot-dip metal plating such as sink rolls.
[0028]
【The invention's effect】
ADVANTAGE OF THE INVENTION The roll for continuous hot-dip metal plating of this invention can prevent a roll axis | shaft part coming off from a roll trunk | drum during use, and can prevent that the crack generate | occur | produces in the junction part of a roll axis | shaft part and a roll trunk | drum. Further, it has excellent corrosion resistance, heat resistance, abrasion resistance and the like, and has a long service life. Since the roll's own weight is lightweight, it rotates well following changes in the running speed of the steel plate. Therefore, a steel sheet having high quality plating characteristics can be stably produced.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a support roll as an example of the present invention.
FIG. 2 is an enlarged schematic sectional view of a roll body and a roll shaft of the present invention.
FIG. 3 is a view schematically showing a continuous hot-dip metal plating apparatus.
[Explanation of symbols]
1 steel plate, 2 snout, 3 molten metal bath, 4 sink roll,
5 support roll, 6 gas wiping, 7 roll body,
8 roll shaft part, 9 convex part, 10 concave part, 11 screw part of roll shaft part,
12 Roll body thread

Claims (7)

A roll body and a roll shaft are formed of ceramics in a hollow shape, and in a continuous molten metal plating roll in which a roll shaft is bonded to both ends of the roll body, a convex portion is formed on a bonding portion of an outer peripheral surface of the roll shaft. A helical screw portion is formed, a concave portion corresponding to the convex portion and a helical screw portion are formed at a joint portion on the inner peripheral surface of the roll body portion, and the respective screw portions are fitted with each other and a roll shaft is formed. A roll for continuous hot-dip metal plating, wherein a convex portion of the portion is fitted to and joined to a concave portion of the roll body. In a continuous molten metal plating roll in which the roll body and the roll shaft are formed in a hollow shape with ceramics and the roll shaft is bonded to both ends of the roll body, a convex portion is formed at the joint on the inner peripheral surface of the roll body. And a helical screw portion, a concave portion corresponding to the convex portion and a helical screw portion are formed at a joint portion on the outer peripheral surface of the roll shaft portion, and the respective screw portions are fitted with each other, and the roll cylinder is formed. A roll for continuous hot-dip metal plating, wherein a convex portion of the portion is fitted into and joined to a concave portion of the roll shaft portion. The roll for continuous hot-dip metal plating according to claim 1, wherein the screw portion has a gentle curved surface in cross section. The roll according to any one of claims 1 to 3, wherein the screw portion has a maximum height of 10 to 1000 µm. The roll for continuous molten metal plating according to claim 1, wherein the convex portion has a corner portion formed into a curved surface. The roll for continuous hot-dip metal plating according to any one of claims 1, 2, and 5, wherein the convex portion has a maximum height of 10 to 1000 µm. The roll for continuous hot metal plating according to claim 1, wherein the ceramic is a silicon nitride-based ceramic.

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