JPH08155508A - Roll for rolling - Google Patents

Abstract

PURPOSE: To improve the wear resistance and the antiseizure property of a roll by providing a Ni-plated, Cr-plated or Ni-Cr alloy plated layer containing the dispersant on the surface of a body part, and dispersing the high hardness material on the plated layer of a plate passing part of the plate edge of the roll. CONSTITUTION: The matrix of the dispersive composite plating to be provided on the surface of a body part of a roll 1 is made of Ni, Cr or their alloy, the high hardness material 3 is dispersed in the plated layer 2 of the part B to pass the plate edge where the wear of the roll is large while the low hardness material 4 is dispersed in the parts A and C. The high hardness material 3 to improve the wear resistance includes the carbide such as TiC and Wc, while the low hardness material 4 includes the oxide and nitride such a Al2 O3 and Si3 N4 . The density of the dispersant of the part B to pass the plate edge is higher than that of other parts, and the dispersant having the self-lubricability is used in the part where the seizure of the roll is likely to be generated. The wear resistance and the anti-seizure quality of the roll are improved, and the material cost of the roll is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling roll mainly used for hot rolling and cold rolling of metal materials.

[0002]

2. Description of the Related Art When a plate is manufactured by rolling a metal material with a roll, problems such as abrasion of the roll surface and seizure of the roll surface occur as the rolling amount of the roll increases.

The rolling of a steel sheet will be described below as an example. As the cumulative rolling amount using the rolling rolls increases, the surface of the roll wears, and eventually the roll wears, causing flaws in the steel sheet. Will have to be replaced. Fig. 7 shows the state of wear of rolling rolls.
The wear of the portion through which the plate edge passes is increased. In order to prevent flaws and flatness defects of the rolled steel sheet due to the wear portion 10 generated in the plate edge passing portion of this roll, as shown in FIG. 8, the sheet width schedule of the rolled steel sheet is sequentially changed from wide to narrow. It corresponds to the rolling method to be transferred.

Further, as measures for improving the wear resistance of the rolling rolls, it has been studied to increase the hardness of the entire roll base material, Cr plating on the roll body, and surface treatment such as thermal spraying.
Japanese Patent Laid-Open No. 0307 discloses a technique for improving the wear resistance of the roll surface by plating the surface of the roll body with Cr and making the hardness of the edge-passing position of the steel plate higher than other parts. Further, Japanese Patent Publication No. 56-34632 discloses a roll having metal oxide particles dispersed in an alloy matrix on the roll surface by thermal spraying.

However, when the roll base material as a technique for improving the wear resistance is hardened or surface-treated such as Cr plating or thermal spraying, the wear resistance of the whole is improved and the roll life is longer than that of the conventional roll. Although it is improved, there is still a problem in that not only the flaws are generated in the steel sheet but also the flatness of the steel sheet cannot be secured in the end due to the abrasion of the roll. Further, even if the Cr plating conditions are changed only for the positions corresponding to the edges of the steel plate to increase the hardness, the wear resistance is similarly insufficient.

Therefore, when the roll wear exceeds the limit, the roll must be replaced, and a significant improvement in roll life cannot be expected. Further, since edge wear still occurs, there is a problem that perfect strip width schedule-free rolling cannot be achieved.

Further, when a film is formed on the surface of the roll by thermal spraying, the adhesion is low because the roll base material and the film are mechanically joined, and when the thermal spraying roll is used for hot rolling or cold rolling. In addition, there is also a problem that the thermal spray coating is peeled off due to high surface pressure on the roll during rolling.

Next, when a special steel sheet such as stainless steel is rolled, there is a problem that the rolled material is seized on the roll surface, and a seizure flaw is generated on the rolled steel sheet. Roll baking generally occurs frequently at a portion corresponding to a position where the edge portion of the plate material passes. As a measure against seizure, a cast iron roll containing graphite as a roll base material may be used, or Ni, Cr or an alloy plating layer thereof may be provided on the roll surface as in JP-A-61-165212, or JP-A-2 The seizure resistance is improved by providing a Cr plating layer in which a solid lubricant such as boron nitride is dispersed as in Japanese Patent Publication No. 207905. .

However, although the cast iron roll and the composite plating in which boron nitride is dispersed, which is the above-described roll seizure countermeasure technology, have improved seizure resistance, but have a problem of poor wear resistance.
Further, it is difficult for a cast iron roll to control the amount of graphite deposited. In addition, a significant improvement in seizure resistance cannot be expected by simply plating the rolls with Ni or Cr, and especially when a similar metal such as stainless steel is rolled, the seizure resistance improvement margin is small. Further, edge wear of the roll occurs and strip width schedule-free rolling cannot be achieved.

It is to be noted that the plate edge passing portion of the rolling roll is apt to be worn or seized because the stress is concentrated on the widened portion or the edge portion of the steel sheet due to rolling, resulting in a large slip with the roll or a high surface pressure. It is thought to be because it becomes. Also,
The reason why seizures often occur in special steel plates such as stainless steel is that the oxide film thickness on the steel plate surface is smaller than that of ordinary steel plates,
It is considered that the rolled steel plate and the rolls are likely to make metal contact with each other.

[0011]

The object of the present invention is to improve the wear resistance and seizure resistance of a rolling roll, reduce the cost of roll materials, and perform rolling of a rolled steel sheet in a schedule-free rolling.
It is to achieve high productivity by reducing the number of roll changes, and to obtain a product having no roll flaw and good flatness.

[0012]

DISCLOSURE OF THE INVENTION The present inventors have paid attention to a dispersion composite plating technique which has excellent adhesion to a roll base material and can contain another material as a dispersant in a plating layer. . Further, in order to improve wear resistance and seizure resistance, the type and amount of the dispersant contained in the plating layer and the position of the dispersant contained in the plating layer were examined, and the present invention was completed.

According to the present invention, Ni, Cr or an alloy plating layer thereof containing a dispersant is provided on the surface of the roll body, and a high hardness material is used as the dispersant in the plating layer of the plate edge of the roll. It is a rolling roll in which the density of the dispersed material in the plated layer of the plate material edge passing portion of the roll is higher than that of other portions.

Further, it is a rolling roll in which a solid lubricant is further dispersed in the plating layer of the plate material edge passing portion of the roll.

[0015]

First, in the present invention, a dispersant such as a high hardness material or a solid lubricant is dispersed in the plating layer on the surface of the body of the roll base material. By using the plating layer, the bond with the roll base material, which is a problem in thermal spraying, is a metal bond, so that the plating layer has good adhesion, and peeling of the plating layer can be prevented.

Ni, Cr and their alloys were used as the matrix of the dispersed composite plating layer provided on the surface of the body of the roll from the viewpoint of wear resistance and seizure resistance.

The dispersant may be Al ₂ O ₃ , SiO ₂ , Zr.
Oxides such as O ₂ , carbides such as WC, TiC, SiC, BN, Si ₃ N ₄
And the like, sulfides such as MoS _{2 and the} like.

The particle size of the dispersant may be such that it can be sufficiently dispersed in the plating solution so that it is dispersed in the plating layer, and the average particle size is preferably 10 μm or less, more preferably 5 μm.
The following is more preferable.

FIG. 1 is a sectional view showing an example of a rolling roll having the dispersed composite plating layer of the present invention. Here, the dispersed composite plating layer 2 is provided on the body of the roll 1, and the roll body is formed. The high hardness material 3 (● in the figure) is dispersed in the plating layer 2 of the B portion, which is the portion through which the plate edge having a large wear amount passes, and the low hardness material 4 is applied to the other A and C portions. (○ in the figure) are dispersed. Here, as the high hardness material 3 dispersed in the plating layer for improving the wear resistance, for example,
Carbides such as TiC (Hv = 3200) and WC (Hv = 2400) can be mentioned. Examples of the low hardness material 4 include Al ₂ O ₃ (Hv = 1800),
Examples thereof include oxides and nitrides such as Si ₃ N ₄ (Hv = 1400).

That is, as described above, the high hardness material 3 is dispersed in the plating layer 2 at the portion through which the plate edge having a large wear amount of the roll body passes, and the low wear is caused in the A and C portions where wear is small. The hardness material 4 may be dispersed.

FIG. 2 is a sectional view showing another example of the rolling roll having the dispersed composite plating layer of the present invention. In the example of FIG. 1, the dispersant is contained in the entire plating layer of the roll body. In FIG. 2, the composite composite plating layer 2 is provided on the body of the roll 1 in FIG. 2, and only in the plating layer 2 of the portion B, which is the position where the edge portion of the plate having a large amount of wear on the body of the roll passes. This is an example in which the dispersant made of the high hardness material 3 is dispersed and the dispersant is not used in the other parts A and C. Large roll wear B
It is also possible to improve the wear resistance as in the case of FIG. 1 by dispersing a dispersing material composed of a high hardness material only in the portion.

FIG. 3 is a sectional view showing still another example of the rolling roll having the dispersed composite plating layer of the present invention. The type of the dispersant is not changed, and the plating layer of the B portion where the roll wear is large is shown. The density of the dispersion material consisting of the high hardness material 3 in 2 is
The wear resistance can also be improved by making the height higher than that of the portion or the portion C. The density difference required to suppress the wear of the plate edge is also related to the hardness of the dispersant, but it is sufficient to increase the density of the dispersant in the B part by 5% or more compared to the other parts (A and C parts). Is.

Further, the hardness of the plating layer containing the dispersion material is changed by changing the density of the dispersion material corresponding to FIG. 3 together with the change of the type of the dispersion material corresponding to FIGS. Is also possible.

The high hardness material mentioned here means a material having a higher hardness than Ni, Cr and their alloys which are the matrix of the plating layer. Further, the expressions of high hardness material and low hardness material described in FIG. 1 are relative, and for example, TiC can be used as the high hardness material and WC can be used as the low hardness material. Further, Al ₂ O ₃ exemplified as the low hardness material above is dispersed in the B portion, which has a large amount of wear, and the other A portion and C are dispersed.
A dispersant having a hardness lower than that of Al ₂ O ₃ may be dispersed in the part.

On the other hand, in the case of the example of FIG. 2, a dispersant having a hardness higher than that of the matrix of the plating layer is dispersed in the portion B,
The other parts A and C may not contain the dispersant. In the case of the example of FIG. 3, the hardness of the B part may be relatively higher than that of the A part and the C part, regardless of the type of the dispersant.

As described above, the wear resistance of the roll body is improved, the wear of the portion where the roll wear is large can be suppressed, and the wear amount can be made uniform, thereby improving the life of the roll.
Sheet width schedule free rolling becomes possible.

Next, the seizure resistance of the roll can be improved by using a dispersant having a self-lubricating property in a portion where the seizure of the roll is likely to occur. Ni, Cr and their alloys can be applied to the roll body to improve seizure resistance, but in order to ensure wear resistance and even excellent seizure resistance, In addition to the above-mentioned abrasion resistance improving technique, a solid lubricant is dispersed in the edge threaded portion of the plate material where seizure is likely to occur.

That is, if the type and density of the dispersant are changed as described above and the solid lubricant is added as a dispersant to prevent seizure in order to make the amount of wear of the roll body uniform, seizure will occur. It is possible to obtain a rolling roll that can be prevented and has excellent wear resistance. As a solid lubricant, B
N, MoS ₂ , (CF) _n, etc. can be used.

FIG. 4 is a sectional view of an example of a rolling roll for improving both the wear resistance and seizure resistance of the present invention. The dispersed composite plating layer 2 is provided on the body portion of the roll 1, and the high hardness material 3 (● in the figure) is added to the plating layer 2 at the portion B where the plate edge where the wear amount of the roll body portion is large passes. A large amount of the dispersant is dispersed in the other parts, and a small amount is dispersed in the other parts A and C to improve the wear resistance by changing the density of the dispersant, and further to the part B where seizure easily occurs. This is an example in which a solid lubricant 4 (▲ in the figure) is added for prevention.

As a result, not only the wear resistance of the roll body but also the seizure resistance is improved, the wear of the portion where the roll wear is large can be suppressed, the wear amount can be made uniform, and the seizure can be prevented. Along with further improvement, strip width schedule-free rolling becomes possible.

Further, regarding the metal to be the matrix of the plating layer, the type and the plating conditions may be changed depending on the part of the roll, but it is more efficient to use one type from the viewpoint of plating workability.

Further, the local wear and local seizure of the roll described above are generally liable to occur in the plate edge threading part, so that part is formed as a plating layer having higher hardness than other parts or a plating layer having high lubricity. To do. Its width (roller axial length) is
It may be determined in consideration of the width change schedule of the steel sheet to be rolled and the variation in the width direction of the sheet material during rolling. The width range of the plate and the edge range where the scale of the steel plate surface falls and wears are about 50 mm, and the upper limit of the amount of change in the plate width when rolling plate materials from wide to narrow is about 450 mm. Therefore, 50 to 450 mm in the roll axis direction around the plate edge passing plate
It is preferable that the width portion is a plating layer having high hardness and high lubricity.

The dispersed composite plating layer of the present invention can be obtained by adding a dispersant to a plating solution and performing electroplating or electroless plating while stirring the solution.

FIG. 5 shows a sectional view of an example of an electroplating apparatus for obtaining the rolling roll shown in FIG. The roll 1 is immersed in the plating tank 6, and a weir 8 is provided in the roll axial direction to divide the plating bath. Then, the plating bath 7 is filled with a plating solution 7 in which different kinds of dispersion materials (high hardness material 3 in the plate passing portion of the plate material, and low hardness material 4 in other portions) are added to the divided sections of the plating tank 6, The roll 1 and the electrode 9 are energized to perform electroplating while rotating the roll 1 and while facilitating the dispersion liquid to be taken into the plating layer by stirring the plating solution 7 with an inert gas or the like. It is possible to obtain the dispersed composite plating layer of sasa.

FIG. 6 shows a sectional view of an example of an electroless plating apparatus for obtaining the rolling roll shown in FIG. The roll 1 is immersed in the plating tank 6, and a weir 8 is provided in the roll axial direction to divide the plating bath. After that, the addition amount of the dispersion material made of the high hardness material 3 is changed for each of the divided sections of the plating tank 6, and the solid lubricant 5 is added to the section corresponding to the portion where seizure easily occurs. Fill with 7 and roll 1
It is possible to obtain a dispersed composite plating layer having a predetermined thickness by performing electroless plating while rotating the plating solution 7 and making it easier for the dispersant to be taken into the plating layer by stirring the plating solution 7 with an inert gas or the like. it can.

[0036]

【Example】

(Example 1) The present invention was applied to a work roll of a cold rolling mill (roll size: diameter 580 mmφ x body length 1730 mm).
The roll base material is 0.8% C-3% Cr forged steel and the hardness is Hs.
Was 90.

As for the plating method, an electroplating apparatus shown in FIG. 5 was used, and since a large amount of wear of 200 mm width at the plate edge portion passing position of the roll was large, weirs were provided on both sides of the portion to separate it from other portions. In the Cr plating solution shown in Table 1, SiC (Hv = 2800, average particle size 2 μm) was used as a high hardness material in the plate edge passage area, and Al ₂ O ₃ was used as a low hardness material in the other areas.
(Hv = 1800, average particle size 2 μm) was added and Cr electroplating was performed under the conditions shown in Table 1 to obtain a dispersion composite plating roll shown in FIG. The dispersant had a density of about 3 g / cm ³ and a plating layer thickness of 20 μm.

(Example 2) Al ₂ O ₃ (Hv = 1800, particle size 2 μm) 1 was used as the dispersion material in the same roll and plating apparatus as in Example 1.
Type, increase the amount of addition to the plate edge through the plate,
Plating was performed under the conditions shown in Table 1 to obtain the dispersed composite plating roll shown in FIG. The density of the dispersed material, 4g / cm ³ at the plate edge through the plate portion, other parts are 3 g / cm ^3, the plating layer thickness was 20 [mu] m.

Example 3 The present invention was applied to a work roll of a hot rolling mill (roll size: diameter 750 mmφ × body length 1860 mm). The roll base material was 2.3% C-18% Cr cast iron and the hardness was 70 in Hs.

The plating method is carried out by the electroplating apparatus shown in FIG. 5. When stainless steel (SUS430) is rolled, wear and seizure occur at a width of 50 mm at the plate edge passing position of the roll. Weirs were installed on both sides to separate from other parts. In the Ni-W alloy plating solution shown in Table 1,
Dispersing material is Al ₂ O ₃ (Hv = 180
(0, particle size 2 μm) 1 type, increasing the amount of addition to the plate edge threading part of the roll, and further adding BN (Hv = 25, average particle size 3 μm) as solid lubricant to the section of the plate edge threading part. ) Was added and plating was performed under the conditions shown in Table 1 to obtain the dispersed composite plating roll shown in FIG. The density of the dispersant is
The plate edge passing plate portion was 5 g / cm ³ , the other portions were 3 g / cm ³ , the density of the solid lubricant in the plate edge passing plate portion was 2 g / cm ³ , and the plating layer thickness was 25 μm.

Example 4 The same roll as in Example 3 was plated with the electroless plating apparatus shown in FIG.
A weir in the plating tank was provided in the same manner as in Example 3, and the dispersant and the solid lubricant were added in the same manner as in Example 3 under the conditions shown in Table 1.
Ni-W alloy electroless plating was performed. The densities of the dispersant and the solid lubricant were the same as in Example 3, and the plating layer thickness was 25.
μm.

[0042]

[Table 1]

The rolls obtained in Example 1 (No. 1) and Example 2 (No. 2) and, as a comparative example, the roll not subjected to the plating treatment (No. 3) were work rolls of a cold rolling mill. The ordinary steel plate with a width of 900 to 1250 mm equivalent to SPCC was cold-rolled at room temperature at a rolling reduction of 30% per pass. The sheet width schedule was set to be free of sheet width schedules in which No. 1 to No. 3 are not rolled in order from wide width to narrow width as shown in FIG. At that time, the amount of rolling until the occurrence of flaws and poor flatness on the steel sheet due to roll edge wear was compared.

Moreover, Example 3 (No. 4) and Example 4 (No.
The roll obtained in 5) and the roll (No. 6) not subjected to plating treatment as a comparative example were incorporated into a work roll of a hot rolling mill, and a stainless steel plate equivalent to SUS430 with a width of 1000 to 1200 mm was heated to 1000 ° C. Hot rolling was carried out at a rolling reduction of 40% per pass. The board width schedule is No. 4 to N.
o.6 Both board width schedule free as in the above. At that time, the amount of rolling until seizure occurred on the roll or the amount of rolling until scratch and flatness failure occurred on the rolled steel sheet due to roll edge wear was compared.

The results are shown in Table 2.

[0046]

[Table 2]

As is clear from Table 2, the rolls of Examples 1 and 2 of No. 1 and No. 2 showed no defects on the rolled steel sheet due to roll edge wear up to the rolling amount of 100,000 tons or 90,000 tons. In addition, strip width schedule-free rolling could be performed without causing flat defects. On the other hand, in Comparative Example No. 3 which was not plated, at 10,000 tons, defects due to roll edge wear and poor flatness occurred, and it was necessary to replace the roll.

In the rolls of Examples 3 and 4 of No. 4 and No. 5, the rolling amount up to 4,000 tons did not cause flaws on the rolled steel sheet due to roll edge wear, and did not cause flat defects. Sheet width schedule-free rolling was completed. Furthermore, there were no steel plate defects due to baking on the rolls. On the other hand, in Comparative Example No. 6 which was not plated, the roll was required to be replaced because the roll was seized at 500 tons and the rolled steel sheet had a flaw.

[0049]

EFFECTS OF THE INVENTION To improve the wear resistance and seizure resistance of rolling rolls, to reduce the cost of roll materials, to make rolling widths of rolling steel sheets free of schedule, and to improve productivity by reducing roll replacement. It is possible to obtain a product with no flaws and good flatness.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a rolling roll having a dispersed composite plating layer of the present invention.

FIG. 2 is a cross-sectional view showing another example of a rolling roll having a dispersed composite plating layer of the present invention.

FIG. 3 is a cross-sectional view showing still another example of a rolling roll having the dispersed composite plating layer of the present invention.

FIG. 4 is a cross-sectional view of an example of a rolling roll that improves both wear resistance and seizure resistance of the present invention.

5 is a sectional view of an example of an electroplating apparatus for obtaining the rolling roll of FIG.

6 is a sectional view of an example of an electroless plating apparatus for obtaining the rolling roll of FIG.

FIG. 7 is a diagram showing a state of wear of a rolling roll.

FIG. 8 is a diagram showing a plate width schedule of rolled steel plates.

[Explanation of symbols]

 1: Roll 2: Plating layer 3: High hardness material 4: Low hardness material 5: Solid lubricant 6: Plating tank 7: Plating liquid 8: Dam 9: Electrode

Claims (3)

[Claims] 1. A Ni, Cr or an alloy plating layer thereof containing a dispersant is provided on the surface of the roll body, and the dispersant in the plating layer of the plate material edge through plate of the roll is a high hardness material. Characteristic rolling roll. 2. A Ni, Cr or an alloy plating layer thereof containing a dispersant is provided on the surface of the roll body, and the density of the dispersant in the plating layer of the plate edge portion of the roll is higher than that of other parts. Roll for rolling characterized by high price. 3. A rolling roll characterized in that a solid lubricant is further dispersed in the plating layer of the plate material edge passing portion of the roll according to claim 1 or 2.