JP2000218306A - Temper rolling method of stainless steel strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temper rolling method which can stably roll a stainless steel strip with very high glossiness without requiring large equipment investment. SOLUTION: Rolling is done with upper and lower mill rolls made different in circumferential speed by spraying the temper-rolling agent of fine droplets mixed with gas to the upper and lower surfaces of stainless steel strip 5. Or rolling is done while the mill roll 3 on one side is made higher in circumferential speed than the mill roll 3 on the other side by spraying the temper-rolling agent of fine droplets mixed with gas to only one surface of the stainless steel strip 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temper rolling method for a stainless steel strip, and more particularly to a temper rolling method capable of stably producing a stainless steel strip having excellent surface quality by preventing gloss deterioration due to roll coating. .

[0002]

2. Description of the Related Art After annealing, a cold-rolled stainless steel strip is subjected to so-called temper rolling in which cold working is performed with an elongation of about 0.5% to 1.5%. The purpose of this temper rolling is to eliminate the elongation at yield point of the stainless steel strip after annealing, to correct the shape, and to give gloss, etc. In the stainless steel strip, the emphasis is particularly on giving gloss.

[0003] A temper rolling method for a stainless steel strip (hereinafter, also simply referred to as a "steel strip") includes a lubricant (hereinafter, referred to as a rolling oil).
There are so-called wet rolling using a "temper rolling agent") and dry rolling without using a temper rolling agent. In wet rolling, the temper rolling agent is rolled in a state where it is trapped in minute irregularities of the steel strip. Therefore, oil pits (pit-like flaws) remain on the surface of the steel strip and high gloss cannot be obtained. Therefore, in general, dry rolling for obtaining higher glossiness is performed, and the rolling mill is provided with a large-diameter roll capable of easily removing abrasion powder and foreign matter adhering to the roll surface.
High-speed rolling mills are widely used.

[0004] The mechanism for improving the gloss in temper rolling is that a stainless steel strip is rolled with a large-diameter roll having a roll surface smoothed at an elongation of about 0.5% to 1.5% to make the roll surface smooth. It is intended to further improve the glossiness by transferring to a steel strip and having a long contact arc length by a large-diameter roll.

However, in dry rolling, (1) the coefficient of friction between the roll and the stainless steel strip is so high that high elongation rolling cannot be performed. There is a problem in that fine scale or the like adheres and accumulates on the roll surface, so-called roll coating occurs, and the quality of the steel strip deteriorates. Therefore, in a continuous line incorporating a temper rolling mill in the continuous annealing equipment, the elongation rate of temper rolling is limited to a low level, and it may be necessary to perform temper rolling again in another line to secure the elongation rate. Productivity has been forced to decline.

As a countermeasure, application of wet rolling using a temper rolling agent during temper rolling has been studied. While wet rolling has the advantage of enabling high pressure and cleaning the roll surface with a temper rolling agent, it makes it possible to remove dirt and foreign matter adhering thereto, but as described above, oil There is a problem that it is difficult to secure glossiness due to the generation of pits.

As a method for improving the glossiness, Japanese Patent Publication No.
Japanese Patent No. 393982 discloses a temper rolling method for a stainless steel strip in which dry rolling with an elongation of 0.1 to 0.5% is performed in a first pass of temper rolling and wet rolling is performed in a second pass and thereafter. Have been.

Japanese Patent Application Laid-Open No. 4-333303 discloses that two or three temper rolling mills are provided, a first stand performs wet rolling, and a remaining rolling oil (temper rolling agent) in the second and third stands. A temper rolling method for a stainless steel strip in which temper rolling is carried out only by itself has been proposed.

However, the aforementioned Japanese Patent Publication No. 57-3984
No. 2 and Japanese Patent Application Laid-Open No. 4-333303 each presuppose simple pass rolling simply in a plurality of passes combining conventional dry rolling and wet rolling. Not applicable to one-pass rolling at Further, by performing wet rolling, there is a problem that the mechanism for improving gloss by dry rolling described above is hindered, and high gloss cannot be obtained.

[0010] The applicant of the present invention disclosed in JP-A-8-215706, a gas-mixing liquid, and a tempering rolling agent formed into droplets having an average diameter of 30 μm or less, which were sprayed and rolled in one pass to obtain high elongation and high gloss. A temper rolling method of stainless steel strip which can obtain the degree is presented.

[0011]

Problems to be Solved by the Invention
The method disclosed in Japanese Patent Publication No. 6 is to adjust the liquid pressure and the gas pressure of the temper rolling agent to spray the temper rolling agent as fine droplets. It is necessary to control with high accuracy, but there is a problem that the spray amount and the droplet diameter change due to disturbances such as fluctuations in the liquid pressure and gas pressure, and the gloss is reduced and the quality of the steel strip becomes unstable. .
Further, the obtained gloss is comparable to that of the conventional dry rolling, and it is impossible to cope with a case where a higher gloss is required.

An object of the present invention is to provide a temper rolling method capable of stably rolling a stainless steel strip having extremely high gloss without requiring a significant investment in equipment.

[0013]

Means for Solving the Problems The present inventor has conducted a temper rolling (hereinafter, referred to as a conventional wet rolling, which is performed by mixing a gas and spraying a temper rolling agent in the form of fine droplets.
Investigation of gloss improvement by "spray wet rolling") was performed, and the following knowledge was obtained.

A. By spray wet rolling, roll coating and oil pits are suppressed, and high gloss is obtained by high elongation rolling. However, even with this method, the generation of fine oil pits is inevitable, and the gloss is limited to the level of dry rolling.

B. In order to prevent the generation of fine oil pits, if the amount of the temper rolling agent sprayed is reduced and the liquid film between the roll and the steel strip is thinned, it is difficult to secure a high elongation rate.
In addition, the decrease in the elongation reduces the relative slip between the roll and the steel strip, and lowers the gloss.

Therefore, a temper rolling method in which the above-mentioned spray wet rolling and rolling performed by giving a difference in peripheral speed between upper and lower rolling rolls (hereinafter, referred to as “different peripheral speed rolling”) has been conceived. The study was repeated focusing on the relative thinning of the liquid film thickness due to the reduction of the spraying amount and the relative slip between the rolling roll and the steel strip by different peripheral speed rolling, and obtained the following knowledge.

C. Since high elongation can be ensured by different peripheral speed rolling, the liquid film thickness can be made extremely thin, and higher gloss can be obtained as compared with spray wet rolling alone. In particular, the gloss of the steel strip surface on the low-speed side where the roll peripheral speed is slow increases. Further, since the allowable range of the liquid film thickness is widened, the instability of the steel strip quality due to the variation of the spraying amount of the temper rolling agent is eliminated.

D. If the peripheral speed difference between the upper and lower rolling rolls becomes large, the steel strip vibrates and rolling becomes unstable. This unstable rolling phenomenon is eliminated by stopping the spray of the temper rolling agent on the high peripheral speed side where the roll peripheral speed is high and performing spray wet rolling only on the low peripheral speed side.

The present invention has been completed based on the above findings, and the gist thereof is as described in the following items (1) and (2).

(1) When the cold-rolled and annealed stainless steel strip is subjected to temper rolling in one or more passes by a temper rolling device equipped with upper and lower rolling rolls, the stainless steel strip is subjected to at least one pass. Temper rolling of a stainless steel strip, characterized by spraying a temper rolling agent into fine droplets by mixing gas on the upper and lower surfaces of the strip and applying a peripheral speed difference to the upper and lower rolling rolls. Method.

(2) When the cold-rolled and annealed stainless steel strip is subjected to temper rolling in one or more passes by a temper rolling device having upper and lower rolling rolls, at least one pass of the stainless steel strip is performed. One surface of the belt is sprayed with a temper rolling agent into which fine particles are mixed by mixing gas, and the other surface is not sprayed with the temper rolling agent, and the peripheral speed of the rolling roll on the other surface side A tempering rolling method for a stainless steel strip, wherein the rolling speed is higher than the peripheral speed of the rolling roll on the one surface side.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic side view of a temper rolling mill for explaining an example of the method of the present invention, wherein reference numeral 1 denotes a temper rolling mill, 2 denotes a temper rolling mill, 3 denotes a rolling roll, Is the nozzle, 5
Is a stainless steel strip.

As shown in FIG. 1, the temper rolling apparatus 1 has a nozzle 4 on the inlet side of a temper rolling mill 2 having rolling rolls 3 above and below a stainless steel strip 5, and the nozzle 4 has a temper. A tempering rolling agent, which is supplied with a rolling agent and a gas to form fine liquid droplets, is sprayed on the stainless steel strip 5 to perform temper rolling.
The spray amount and the droplet diameter of the temper rolling agent are adjusted by the liquid pressure of the temper rolling agent supplied to the nozzle 4 and the gas pressure. The position where the temper rolling agent is sprayed on the stainless steel strip is preferably on the surface of the stainless steel strip or the roll surface on the side of the temper rolling mill. Here, the temper rolling agent is a liquid used for lubrication between the rolling roll and the stainless steel strip during temper rolling, and an aqueous solution in which an organic lubricant is mixed with water at a concentration of several% is usually used. Used. The droplet diameter is preferably 30 μm or less. Air is usually used as the gas mixed with the temper rolling agent. The illustrated example is a two-stage temper rolling mill including only rolling rolls, but may be a four-high rolling mill including a backup roll that supports the rolling rolls. Further, a plurality of temper rolling mills may be provided in tandem.

FIG. 2 is a schematic diagram illustrating the different peripheral speed rolling according to the present invention. Different peripheral speed rolling is a method in which rolling is performed with a difference in peripheral speed between upper and lower rolling rolls, and the rolling load can be reduced by using shear stress in the rolling direction. Rate can be obtained.

As shown in FIG. 2, in the different peripheral speed rolling, the neutral point position where the roll speed and the steel strip speed coincide is different between the upper and lower positions.
That is, the neutral point 6 on the high peripheral speed side is on the exit side of the roll bite (the range where the roll is in contact with the steel strip), and the neutral point 7 on the low peripheral speed side is the entrance side of the roll bite compared to the same peripheral speed rolling. Go to Therefore, on the low peripheral speed side, the advanced region (the region where the steel sheet speed is higher than the roll speed) becomes longer.

Referring to FIG. 1, the method of the present invention sprays a temper rolling agent into fine droplets by mixing a gas on the upper and lower surfaces of a stainless steel strip 5, and furthermore, a difference in the peripheral speed of the upper and lower rolling rolls 3 is obtained. It is characterized by being rolled. By this method, a high elongation rate can be ensured, so that the liquid film thickness of the temper rolling agent can be reduced to such an extent that roll coating can be prevented, the generation of minute oil pits is suppressed, and the gloss is improved. . In particular, on the low peripheral speed side where the advanced zone is long, the relative sliding distance between the roll and the steel strip is long and high gloss is obtained, so the temper rolling method for stainless steel strip where high gloss is required only on one side It is suitable for. The spray amount of the temper rolling agent may be changed on the upper surface and the lower surface.

When the stainless steel strip is subjected to temper rolling in a plurality of passes, the above method may be performed in at least a part of the passes. Also, when performing multiple passes with the above method,
For example, the surface on the high-speed side in the first pass may be rolled on the low-speed side in the second pass, so that a higher gloss can be obtained on both sides of the steel strip as compared with the case of only spray wet rolling.

When the peripheral speed difference becomes large, a slip between the rolling roll and the steel strip occurs due to a disturbance due to a variation in a spraying amount of the temper rolling agent, and as a result, the position of the neutral point is out of the roll bite. Rolling out, vibration of the steel plate called so-called chattering may occur, and rolling may become unstable. In this case, the instability of the rolling is improved by changing the spraying amount of the temper rolling agent on the upper surface and the lower surface and reducing the spraying amount on the high-speed side.

FIG. 3 is a schematic side view of a temper rolling mill illustrating an example of another method of the present invention. In FIG.
1 are denoted by the same reference numerals. In FIG. 3, another method of the present invention is a method of spraying a temper rolling agent into fine droplets by mixing a gas on one surface 10 of a stainless steel strip 5 and applying the temper rolling agent on the other surface 11. Rolling is performed without spraying an agent, with the peripheral speed of the rolling roll 13 on the other surface 11 being higher than the peripheral speed of the rolling roll 12 on the one surface 10.

According to this method, the one surface on the low peripheral speed side can obtain high gloss for the same reason as described above, and the other surface on the high peripheral speed side can realize dry rolling with a high coefficient of friction. Even under the condition where the difference is large, the vibration of the steel sheet is suppressed, and the rolling stability is obtained. This method is particularly suitable for a temper rolling method for a stainless steel strip requiring high gloss on only one side.

When the stainless steel strip is subjected to temper rolling in a plurality of passes, the above method may be performed in at least a part of the passes. When performing multiple passes using the above method,
For example, the surface on the high-speed side in the first pass may be rolled on the low-speed side in the second pass, so that a higher gloss can be obtained on both sides of the steel strip as compared with the case of only spray wet rolling.

Next, the conditions for different peripheral speed rolling will be described. The different peripheral speed ratio α is defined as the ratio (ΔV / V) between the roll speed difference ΔV and the low-speed roll peripheral speed V, and the reduction ratio β of the steel strip is defined as the thickness reduction ΔH (= inlet thickness H1-outlet thickness H0). Discharge side plate thickness H0
(ΔH / H0), the different peripheral speed ratio α is preferably larger than 0 and equal to or smaller than the plate thickness ratio β. When the different peripheral speed ratio α exceeds β, the positions of the upper and lower neutral points are both outside the roll bite, and the rolling becomes unstable. Preferably, α is 0.05%
This is 90% or less of the plate thickness ratio β. More preferably,
α is 0.3% or more and 70% or less of the plate thickness ratio β.

[0033]

(Embodiment 1) A two-stage temper rolling mill 2 having the basic structure shown in FIG. 1 and a nozzle 4 for jetting a temper rolling agent as fine droplets above and below the entrance side of the temper rolling mill 2. The temper rolling of a cold-rolled ferritic stainless steel strip (SUS430) having a sheet thickness of 0.5 mm and a sheet width of 1000 mm was performed using the temper rolling apparatus 1 equipped with The number of passes for temper rolling is 1-2 passes,
In some or all of the passes, a temper rolling agent was sprayed on both the upper and lower surfaces of the steel strip to perform spray wet rolling, and in the other passes, the spraying of the temper rolling agent was stopped and dry rolling was performed. Tables 1 and 2 show the main specifications of the temper rolling mill and the conditions for spraying the temper rolling agent, respectively.

[0034]

[Table 1]

[0035]

[Table 2]

As shown in Table 1, the temper rolling mill is of a single-drive mechanical connection type and has an upper roll diameter of 700 mm.
mm and lower roll diameters of 703 and 706 mm, and different peripheral speed rolling was performed. The roughness of the upper and lower rolls was 0.02μ.
m, the number of rotations of the upper and lower rolls is 68 rpm, and the longitudinal tension is 15
kgf / mm ² .

As shown in Table 2, an aqueous solution containing 10% of an organic lubricant was used as the temper rolling agent, air was used as the gas, the liquid pressure of the temper rolling agent was 2 kgf / cm ² , and the air pressure was 5 kg
f / cm ² and the spray amount of the temper rolling agent is 50 cc /
min.

For comparison, the same peripheral speed rolling was performed with the upper and lower roll diameters being 700 mm. Table 3 shows the glossiness, the occurrence of surface flaws, and the rolling state of the steel strip obtained together with the temper rolling conditions.

[0039]

[Table 3]

As shown in Table 3, when compared at the same elongation rate, all of the examples of the present invention showed higher gloss than the comparative example, and particularly high gloss was obtained on the upper surface. It is presumed that the gloss was improved by performing at least one pass of spray wet rolling on the upper surface on the low speed side of the different peripheral speed rolling. NO. In No. 7, the upper and lower surfaces of the steel strip were inverted by rolling in the second pass (the upper surface in the first pass was defined as the lower surface in the second pass), and high gloss was obtained on both the upper surface and the lower surface. Regarding surface flaws, In the cases of Nos. 5 and 6, slight flaws were observed, which was good without practical problems. Further, in the example of the present invention, no. In No. 3, micro vibrations of the steel plate were intermittently observed due to the high peripheral speed ratio, but there was no problem in practical use. In addition, No. of a comparative example. Nos. 11 to 13 were defective due to generation of surface flaws.

(Embodiment 2) A two-stage temper rolling mill having the basic structure shown in FIG. 3 and a temper provided with a nozzle for spraying a temper rolling agent as fine droplets on the upper side of the entrance side of the temper rolling mill. Temper rolling of a cold-rolled ferritic stainless steel sheet (SUS430) having a thickness of 0.5 mm and a width of 1000 mm was performed using a temper rolling device. The number of passes of the temper rolling is 1 to 2 passes, and in some or all of the passes, a temper rolling agent is sprayed only on the upper surface of the steel strip to perform spray wet rolling, and the different peripheral speed rolling in which the upper surface is on the lower speed side. Was done. The main specifications of the temper rolling mill and the conditions for spraying the temper rolling agent are the same as those in Tables 1 and 2, respectively.

For comparison, the same peripheral speed rolling was performed with the upper and lower roll diameters being 700 mm. Table 4 shows the glossiness, the occurrence of surface flaws, and the rolling conditions of the steel strip obtained together with the temper rolling conditions.

[0043]

[Table 4]

As shown in Table 4, when compared at the same elongation, the present invention example showed higher gloss on the upper surface than the comparative example.
It should be noted that NO. No. 27 is the one in which the upper and lower surfaces of the steel strip were inverted by rolling in the second pass (the upper surface in the first pass was defined as the lower surface in the second pass), and high gloss was obtained on both the upper surface and the lower surface. Regarding surface flaws, In Examples 25 and 26, slight flaws were recognized, which was good without practical problems. Further, in each of the examples of the present invention, the rolling was extremely stable and excellent without generation of micro vibration of the steel sheet. In addition, No. of a comparative example. Nos. 31 to 33 were defective due to surface flaws.

[0045]

According to the method of the present invention, roll coating can be prevented while securing a high elongation, and a stainless steel sheet having a surface gloss superior to that of the conventional dry rolling can be stably manufactured. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a temper rolling apparatus illustrating an example of the method of the present invention.

FIG. 2 is a schematic diagram illustrating different peripheral speed rolling according to the present invention.

FIG. 3 is a schematic side view of a temper rolling device illustrating another method of the present invention.

[Explanation of symbols]

1: Temper rolling device 2: Temper rolling mill 3, 12, 13:
Rolling roll, 4: Nozzle, 5: Stainless steel strip, 6: Neutral point on high peripheral speed side, 7: Neutral point on low peripheral speed side, 10: One surface, 11: Other surface.

Claims (2)

[Claims] When a cold-rolled and annealed stainless steel strip is subjected to temper rolling in one or more passes by a temper rolling device having upper and lower rolling rolls, the stainless steel strip is subjected to at least one pass. A method of temper rolling a stainless steel strip, characterized in that a temper rolling agent is formed by mixing gas on the upper and lower surfaces of the steel strip and spraying a temper rolling agent in the form of fine droplets, and performing rolling with a peripheral speed difference between the upper and lower rolling rolls. . 2. When the cold-rolled and annealed stainless steel strip is subjected to temper rolling in one or more passes by a temper rolling device having upper and lower rolling rolls, the stainless steel strip is subjected to at least one pass. One surface is sprayed with a temper rolling agent that is a mixture of gas and formed into fine droplets, the other surface is not sprayed with the temper rolling agent, and the peripheral speed of the rolling roll on the other surface is further reduced. A temper rolling method for a stainless steel strip, wherein the speed is higher than the peripheral speed of the one side roll.