JP2002161347A - Roll for continuous hot-dip metal plating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll for continuous hot-dip metal plating, which is superior in corrosion resistance, heat resistance, and wear resistance, is easy to rotate due to weight reduction of the roll, may not cause a crack when raised from a bath, can make the whole roll longer by employing ceramics, and can prevent destruction of a screw in a screw connected part. SOLUTION: The roll for continuous hot-dip metal plating, which has a roll body and a roll axis part made of ceramics with a hollow shape, and of which the roll axis part is screw connected to the inner face of the roll body, is characterized by forming a flat part on a crest and a root of the screw for the connection. The roll is further characterized by that a cushioning material is interposed between the screws for the connection, that a surface of the screw is plated, and that the surface of the screw is thermally sprayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. 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, which is immersed in a hot-dip metal bath when a steel plate is subjected to metal plating such as zinc plating.

[0002]

2. Description of the Related Art A continuous hot-dip metal plating apparatus performs continuous plating while immersing a steel sheet whose surface has been cleaned and activated in a bath of a molten metal such as zinc and running it. At that time, a roll for continuous molten metal plating such as a sink roll or a support roll is used by being immersed in a molten metal bath.
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, maintains the steel plate pass line, Corrects the warpage of the steel sheet that occurs when the steel sheet passes through the roll.

[0003] Conventional rolls for continuous hot-dip metal plating include:
Steel materials such as stainless steel and chromium-based heat-resistant steel having excellent corrosion resistance have been used. However, when the roll was immersed in the molten metal bath for a long time, the surface was eroded and easily worn. In order to further improve corrosion resistance and abrasion resistance, the surface of the roll base material made of a steel material is provided with a corrosion resistance C.
o base alloys by overlay welding, WC-Co cemented carbide,
Some ceramics, such as l ₂ O ₃ , were sprayed, but due to the difference in the coefficient of thermal expansion between the base material and the sprayed coating, cracks were formed in the thin coating and eroded therefrom, and wear was inevitable.

[0004] When the wear is remarkable, the roundness and cylindricity of the roll cannot be maintained, and the roll and the steel plate vibrate, so that a steel plate having uniform plating characteristics cannot be obtained. For this reason, conventionally, after continuous use for one to two weeks, it was necessary to temporarily stop the plating operation and replace the worn roll.
This significantly reduces the productivity and increases the cost of replacing the rolls, resulting in a high product cost.

In order to solve this problem, there is known a roll for continuous hot-dip metal plating in which a roll body (sheet passing portion) in contact with a steel plate is made of ceramics having excellent corrosion resistance, heat resistance and wear resistance. . For example, as a conventional example, JP-A-5-271887 discloses that a brass retaining ring for holding a ceramic sleeve made of sialon is inserted into a shaft made of heat-resistant steel of SUH309, and a heat-resistant steel retainer is inserted from both ends of the shaft. A support roll in which a ring is fitted and a shaft and a ceramic sleeve are fixed is described.

[0006]

Rolls for continuous hot-dip metal plating, such as sink rolls and support rolls, need to rotate at the same speed as the steel sheet because they are in contact with the steel sheet. For this reason, it is desired that the roll for continuous hot-dip metal plating is easy to rotate as much as possible, and is easy to start up and follow the change in the running speed of the steel sheet. However, in the case of the conventional example, there is a problem that the solid weight of the roll is heavy because it has a solid shaft made of heat-resistant steel, and it is difficult to rotate following the running steel plate.

When the roll is pulled up from the bath in a state where the molten metal has entered the gap between the roll shaft and the ceramic sleeve, the molten metal accumulates in the gap and solidifies as the temperature decreases. On the other hand, the roll that has been thermally expanded during use in the bath is cooled by the temperature drop and starts to contract. For this reason, there is a problem that the ceramic sleeve is subjected to a compressive action by the solidified metal accumulated in the gap to cause cracking.

Further, in the conventional example, only the roll body is made of ceramics, the roll shaft and the holding ring are made of heat-resistant steel, and the retaining ring is made of brass, so that the corrosion resistance and wear resistance to the molten metal bath are not yet achieved. Was not enough. Therefore, it is only necessary that the entire roll can be made of ceramics.
Sintered ceramics are limited in size and shape because, for example, a ceramic raw material powder or the like is placed in a mold, molded by a cold isostatic press, and then fired. In particular, in the case of a long product such as a roll, in order to integrally manufacture the entire roll with ceramics, there are many restrictions on the length dimension.

In order to solve this problem, the present inventor has proposed that corrosion resistance,
After making a hollow roll body and a roll shaft separately from ceramics with excellent heat resistance and abrasion resistance, one roll shaft at one end of the roll body and the other end at the other end of the roll body. We have already proposed a support roll for continuous hot-dip metal plating constituted by assembling another roll shaft by screwing it together.

However, in the support roll proposed above, when the shape of the screw made of ceramic is such that the crests 12 and valleys 13 of the screw 11 are sharp as shown in FIG. Therefore, there is a problem that the screws are only locally contacted, the stress acting on the screw portion is extremely high, and the screw is easily broken.

Accordingly, an object of the present invention is to solve such a problem, and is excellent in corrosion resistance, heat resistance, and abrasion resistance, is easy to rotate by reducing the weight of the roll, and is useful when the roll is pulled up from a bath. An object of the present invention is to provide a roll for continuous hot-dip metal plating that can prevent cracks, can lengthen the entire roll of ceramics, and can prevent breakage of screws during screw joining.

[0012]

The roll for continuous hot-dip metal plating of the present invention has a roll body and a roll shaft formed of ceramics in a hollow shape, and the roll shaft is screw-bonded to the inner surface of the roll body. A metal plating roll,
It is characterized in that flat portions are formed in the ridges and valleys of the screws to be joined. Second, a buffer material is interposed between the screws to be joined. Third, the surface of the screw to be joined is plated. Fourth, the surface of the screw to be joined is thermally sprayed.

[0013]

In the roll for continuous hot-dip metal plating of the present invention, the shape of the screw made of ceramics is formed by forming flat portions at the crests and valleys of the screw as shown in FIG. It becomes difficult to do. Preferably, the corners of the ridges and valleys of the screw are processed into a curved shape to avoid stress concentration.

Further, by interposing a cushioning material between the screws to be joined, local contact between the screws is suppressed to avoid stress concentration. As the cushioning material, a heat-resistant inorganic adhesive having a coefficient of thermal expansion close to that of ceramics is preferably applied to the screw surface or filled between the male screw and the female screw.

Further, by plating or spraying the surfaces of the screws to be joined, local contact between the screws is suppressed to avoid stress concentration. The plating applied to the screw surface is
Those excellent in heat resistance and wear resistance such as nickel-phosphorus plating are preferable, and the plating thickness is desirably 50 μm or less. The thermal spray applied to the surface of the screw is also preferably excellent in heat resistance and wear resistance, and is preferably applied by a known method such as plasma spraying, and the thermal spray thickness is preferably 200 μm or less. The present invention forms a flat portion in the crests and valleys of the screw, interposes a cushioning material, plating the surface of the screw,
Alternatively, it is more desirable to combine thermal spraying on the surface of the screw.

The roll for continuous hot-dip metal plating of the present invention comprises:
Since the roll body and roll shaft are made of ceramics,
It has sufficient corrosion resistance, heat resistance, and abrasion resistance to the molten metal bath. Among the ceramics, silicon nitride ceramics such as silicon nitride and sialon have a thermal expansion coefficient of about 3
It is preferable because it is as small as × 10 ^-6 / ° C and has excellent thermal shock resistance and high strength at high temperatures.

Since the roll body and the roll shaft are hollow bodies each having a through hole in the direction of the rotation axis, the weight of the entire roll is reduced. Therefore, the rotational inertia force of the roll is reduced, and the roll can be satisfactorily followed by the start of operation and the change in the traveling speed of the steel sheet.

According to the present invention, there is a small possibility that a gap into which the molten metal can enter is only a portion where the roll body and the roll shaft are joined, and when the roll is pulled out of the bath, the hollow portion is formed. Since the molten metal is smoothly discharged from the openings at both ends of the through hole formed by the roll body and the roll shaft, the roll can be prevented from cracking due to the molten metal accumulating in the gaps and solidifying. Further, it is desirable to provide a hole such as a circle, an ellipse, and a square for discharging the molten metal on the outer periphery of the roll shaft portion, and a large number of holes are equally divided or staggered on the circumference of the roll shaft portion. You may drill.

After the roll body and the roll shaft are separately manufactured, one roll shaft is attached to one end of the roll body.
Since another roll shaft is screwed to the other end of the roll body to assemble the roll, the roll made entirely of ceramics can be easily lengthened.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which sialon ceramics is applied to a support roll of a continuous hot-dip metal plating apparatus will be described below. FIG. 1 schematically shows a continuous hot-dip metal plating apparatus. In FIG. 1, 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. And the steel plate 1 is a molten metal bath 3
The traveling direction is changed by the sink roll 4 suspended from the bottom of the inside, and it 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.

FIG. 2 is a sectional view of a support roll 5 as an example of the present invention. In FIG. 2, the support roll 5
Is formed by screwing a roll shaft 8 and a tightening ring 9 to both ends of a roll body 7, respectively. 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.

In this embodiment, the roll body 7 of the support roll 5 was manufactured as follows. First, average particle size 0.8μ
m-α-Si ₃ N ₄ powder: 87% by weight, average particle size 0.5 μm
m of Al ₂ O ₃ powder: 5% by weight, A having an average particle size of 0.5 μm
1N solid solution powder: 3% by weight, Y _{2 having} an average particle size of 1.0 μm
O ₃ powder: 5 wt% was blended, and a mixture obtained by adding and stirring 0.5 wt% of polyvinyl butyral as a binder per 100 wt parts of the raw material powder was 1000 kg / c.
CIP molding was performed at a pressure of m 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.

The obtained sialon ceramic sintered body had a density of 99.1% 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 and the tightening ring 9 were also made of a sialon ceramic sintered body in the same manner as the roll body 7.

The roll body 7 has an outer diameter of 210 mm and an inner diameter of 1 mm.
It is made of a hollow cylinder having a length of 65 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 in contact. A stepped portion 7 having a different thickness is provided on the inner surface of the roll body 7.
1 was provided. A thread groove 72 used for joining with the roll shaft 8 is provided in the center of the roll body 7 with the stepped portion 71 interposed therebetween. Here, the tightening direction of the screw groove 72 is temporarily referred to as a forward direction. Further, a screw groove 73 used for joining with the tightening ring 9 is provided on the end face side of the roll body 7 with the stepped portion 71 interposed therebetween. The screw groove 73 was formed such that the tightening direction was the negative direction.

The roll shaft 8 is formed of a hollow body and is rotated via a spindle (not shown) by a drive motor (not shown) provided outside the molten metal bath. On the outer surface of the roll shaft 8, there is provided a projecting projection 81 which is a fitting portion with the roll body 7. A screw groove 82 used for joining with the roll body 7 is provided on the end face side of the roll shaft 8 near the protrusion 81.
Was provided. The one roll shaft portion 8 (the right shaft portion in FIG. 2) is a drive shaft, and a clutch member (not shown) for coupling with the spindle is attached to the small-diameter shaft end. In this case, the clutch member was also made of a sialon ceramic sintered body. The other roll shaft 8 is a driven shaft supported by a slide bearing.

The tightening ring 9 is formed of a ring body, and its outer surface has a thread groove 91 used for joining with the roll body 7.
Was provided.

Such a roll body 7, a roll shaft 8,
After preparing the tightening ring 9, the support roll 5 of the present invention was assembled. First, the roll shaft 8 is screwed to the inner surface of the roll body 7 so that the end surface of the projection 81 of the roll shaft 8 contacts the stepped portion 71 of the roll body 7 at the center of the roll body 7. The roll shaft 8 was positioned in the roll shaft direction. The roll shaft 8 and the roll body 7 were screwed together so as to be tight in the direction of rotation of the roll. On the other hand, a gap was provided between the outer surface of the roll shaft 8 and the inner surface of the roll body 7 on the end face side of the roll body 7, and the tightening ring 9 was inserted into the gap. Then, the tightening ring 9 was screwed to the inner surface of the roll body 7 such that the distal end surface of the tightening ring 9 was in contact with the projection 81 of the roll shaft 8. Tightening ring 9
And the roll body 7, the roll shaft 8 and the roll body 7
The screw connection was made in the reverse screw direction, which is the direction of tightening rotation opposite to the screw connection of.

In joining the roll body 7 and the roll shaft 8, the screw joining shown in FIG. 3 was performed. In FIG.
The ridges 12 and the valleys 13 of 1 had a flat portion 14, and the corners 15 were processed into a curved shape. The gap 16 between both screws was filled with a heat-resistant adhesive. In joining the roll body 7 and the tightening ring 9, the roll body 7 and the roll shaft 8 are also connected.
The joining structure was the same as that of the screw joining.

In the continuous hot-dip metal plating apparatus shown in FIG. 1, the SUS300 stainless steel sheet having a thickness of 2 mm and a width of 1300 mm was zinc-plated with the support roll 5 of the present invention having the above-described structure. After continuous use, the support roll 5 showed almost no erosion and wear and the service life was remarkably improved. In addition, the screws provided on the roll body, the roll shaft and the tightening ring did not break during use. 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 well, and suppresses the occurrence of vibration of the roll and the steel sheet due to abrasion. .

Although the embodiment of the support roll has 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 a sink roll.

[0031]

The roll for continuous hot-dip metal plating of the present invention can prevent the screw formed on each member from being broken during use. 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 light, it rotates well following changes in the running speed of the steel plate. When the roll is lifted out of the bath, the molten metal hardly penetrates into the gap, so that the roll can be prevented from cracking. Therefore, a steel sheet having high quality plating characteristics can be stably produced.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a continuous hot-dip metal plating apparatus.

FIG. 2 is a diagram showing a cross-sectional view of a support roll as an example of the present invention.

FIG. 3 is a schematic cross-sectional view of a screw shape of the present invention.

FIG. 4 is a diagram showing a schematic sectional view of a conventional screw shape.

[Description of Signs] 1 steel plate, 2 snout, 3 molten metal bath, 4
Sink roll, 5 support roll, 6 gas wiping, 7 roll body, 8 roll shaft, 9 tightening ring, 11 screws, 12 peaks, 13 valleys,
14 flat part, 15 corner part, 16 gap

Claims (5)

[Claims] 1. 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 screwed to an inner surface of the roll body. A roll for continuous hot-dip metal plating, wherein a flat portion is formed in a valley. 2. A roll for continuous molten 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 screwed to an inner surface of the roll body. Roll for continuous hot-dip metal plating, wherein 3. A continuous molten metal plating roll in which a roll body and a roll shaft are formed in a hollow shape by using ceramics and a roll shaft is screwed to an inner surface of the roll body, and the surface of a screw to be bonded is plated. Roll for continuous hot metal plating. 4. 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 the roll shaft is screw-joined to the inner surface of the roll body, and the surface of the screw to be joined is sprayed. Roll for continuous hot metal plating. 5. The roll for continuous hot metal plating according to claim 1, wherein the ceramic is a silicon nitride ceramic.