JP2003127065A - Method for controlling surface shape of steel plate and steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that can surely adjust the surface shape of a steel plate to meet a target value. SOLUTION: A centrifugal projection device projects solid particles from vanes 42 mounted on a rotor 41 driven by a motor 43 by means of centrifugal force. The revolution speed command to the motor 43 is transmitted from a rotor speed controller 46. On the other hand, the surface shape after projection of the solid particles is measured by surface shape measuring devices 15a and 15b. A surface shape controller 50 compares the target value of the surface shape given by a surface shape control database 53 with the actually measured value of the surface shape, and controls the revolution speed of the motor 43 via the rotor speed controller 46 so as to make the two coincide with each other.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method of projecting fine solid particles onto the surface of a steel sheet using a centrifugal projection device to obtain a steel sheet represented by average roughness Ra and peak count PPI. The present invention relates to a method for controlling surface morphology and a steel sheet whose surface morphology is adjusted using these methods.

[0002]

2. Description of the Related Art Steel sheets generally used in the field of automobile parts and building materials, etc. are obtained by subjecting hot-rolled steel sheets to pickling treatment and then cold rolling to reduce the thickness to a certain value, such as annealing and temper rolling. It is manufactured through a process. Temper rolling does not affect the steel plate.
By giving a light extension rate of about 5 to 2.0%,
The mechanical properties are adjusted by removing the elongation at yield of the steel sheet. However, the function of temper rolling is not limited to that, and it also includes flattening the shape of the steel sheet and adjusting the surface roughness of the steel sheet by transferring the roughness of the rolling roll. The cold-rolled steel sheet manufactured in this manner becomes a product through an inspection process and the like. On the other hand, when a plating treatment such as electrogalvanizing is performed, the product is manufactured after being subjected to temper rolling and then sent to the plating step.

Products such as hot-dip galvanized steel sheets are often manufactured by a continuous line including an annealing process. In the hot dip galvanizing line, after annealing,
It is immersed in a plating bath to form a plating film on the surface of the steel sheet. For galvanized steel sheets, the coating may or may not be alloyed, but a temper rolling mill is located downstream of it to adjust the mechanical properties of the steel strip. At the same time, the surface roughness is adjusted. As described above, in steel sheets such as cold-rolled steel sheets and surface-treated steel sheets, the surface roughness is usually adjusted by transferring the surface roughness of the rolling roll to the steel sheet surface by the temper rolling mill. .

Incidentally, the concept of the surface roughness of a steel plate is usually JISB.
In many cases, it refers to the center line average roughness Ra defined in 0601, but here it represents a broad concept represented by various parameters in terms of functions such as press working and image clarity after painting. For example, a peak count PPI that represents the number of irregularities per unit length, a centerline waviness Wca that represents the average height of irregularities that have been subjected to high-frequency cutoff, and a concept that includes dimple coverage and its distribution form described later. Used as.

From this point of view, Japanese Patent Laid-Open Publication No. Hei 7-136701 discloses a conventional technique in which fine irregularities are formed on a surface of a galvanized steel sheet in order to achieve both slidability and image clarity after coating. Those formed within the range of area and volume are shown, and temper rolling is disclosed as a means thereof.

On the other hand, as a method of adjusting the surface roughness of the steel sheet by means different from temper rolling, a method of projecting solid particles to adjust the surface roughness of the steel sheet can be used. For example, it is known that the maximum roughness Rmax of the steel sheet can be adjusted by changing the projection speed by using solid particles having a particle diameter of 500 μm or more (method and effect of shot peening, published by Nikkan Kogyo Shimbun, 1997, p.39, hereafter referred to as prior art reference 1). The maximum roughness Rmax, like the average roughness Ra, is a parameter that represents the height of the surface irregularities,
It can be used as an index when controlling the average roughness by projecting solid particles.

Further, as a concavo-convex pattern on the surface of the steel sheet, only a long-period concavo-convex pattern is extracted, and the center line waviness Wca is a parameter representing the average height. Center line swell W
ca is specified in JIS B 0610, and it is said that it is desirable to reduce Wca in order to improve the image clarity after painting. As a conventional technique for adjusting such parameters by projecting solid particles, Japanese Patent Laid-Open No. 3-294418 has been proposed.
The technique described in Japanese Patent Publication is cited.

This is intended for cold-rolled steel sheets and has an average particle size of 30 to 10 in order to obtain good press formability and image clarity after coating.
This is a method of projecting 0 μm shot particles onto a steel plate, and controlling the center line waviness Wca of the steel plate within a certain range and controlling the area ratio of the dimples within a certain range.
As a specific manufacturing method, there is disclosed a method in which compressed air is jetted from a nozzle by using an air type shot projection device to accelerate shot particles and project the shot particles onto the surface of a steel sheet.

[0009]

A method for adjusting the surface roughness of a steel sheet is disclosed in JP-A-7-136701.
The generally used temper rolling method has the following problems.

First, in temper rolling, the rate at which the irregularities of the rolling roll are transferred (transfer rate) can be increased by increasing the elongation rate, and the roughness of the steel sheet can be changed. If the ratio is too large, the ductility of the steel sheet will be reduced, and the mechanical properties required as a product cannot be satisfied.
On the other hand, if the elongation is too low, the elongation at yield point after annealing cannot be eliminated, and the original function of temper rolling cannot be achieved. That is, there is an upper limit and a lower limit to the elongation rate that can be given to the steel sheet due to the characteristics of the product, and the elongation rate can be changed only within that range, and the transfer rate is also limited to a certain range, so the surface roughness There is a problem that the controllable range is small.

For example, for a steel sheet whose elongation rate is limited to 0.8 to 1.2%, the average roughness transfer rate is 35 to 45%.
It can be changed only within the range of the degree, and when the average roughness Ra of the rolling roll is 3 μm, the Ra of the steel plate is 1.05 to 1.35.
It can only be changed within the μm range.

Further, the size and the distribution form of the unevenness formed on the surface of the steel sheet, or the parameters such as peak count PPI and waviness Wca are governed by the shape of the unevenness formed on the rolling roll. When added, there is a problem that they cannot be controlled independently in the state of being incorporated in the temper rolling mill.

Further, in temper rolling, the rolling roll and the steel sheet come into contact with each other under high pressure, so that the roughness of the rolling roll changes over time due to wear, and the surface roughness transferred to the steel sheet should be kept constant. Will be difficult. At this time, in order to keep the surface roughness of the steel sheet constant, it is necessary to set the elongation rate to a low level with respect to the rolling roll that is not worn, and increase the elongation rate as the wear progresses. However, changing the elongation rate according to the progress of wear of the rolling roll causes a problem that the range in which the surface roughness can be controlled is further reduced as described above.

On the other hand, in the prior art document 1, there is known a method of projecting solid particles to adjust the average roughness Ra or the maximum roughness Rmax, but in any case, solid particles having a size of 500 μm or more are used. Used. Such projection of solid particles having a large particle diameter is usually used for the descaling treatment of the hot rolled steel sheet, and the obtained average roughness Ra is as large as 3 μm or more. On the other hand, the average roughness Ra of a cold-rolled steel sheet or a galvanized steel sheet is about 0.3 to 2 μm, and the range of Ra to be controlled is required to have an accuracy of about ± 0.2 μm. Therefore, when the particle size of the solid particles is 500 μm or more as in the prior art,
Even if the projection conditions are slightly changed, the average roughness changes significantly, and the surface roughness of the steel sheet cannot be adjusted with high accuracy.

Further, in the prior art document 1, it is shown that, of parameters such as Ra and Rmax representing the form of surface irregularities, a parameter relating to the height of irregularities having a short period can be adjusted. However, not only the parameters related to the height of short-period concavities and convexities but also their pitch and distribution morphology have a great influence on the properties such as press workability and image clarity after painting, and these are controlled. The means are not disclosed.

The technique disclosed in Japanese Patent Laid-Open No. 3-294418, which aims to improve the press workability of a cold-rolled steel sheet and the image clarity after coating, projects fine shot particles to swell the center line of the steel sheet. The present invention relates to a method of controlling the area ratio of Wca and its dimple portion within a certain range. However, the specifically disclosed means is to project shot particles using a pneumatic projection method, and how to change the projection conditions to obtain a target surface morphology is industrially No specific means for imparting roughness is disclosed. In addition, the pneumatic projection method is a method of accelerating shot particles while injecting compressed air from a nozzle, which has poor energy efficiency, and the area that can be projected by a single nozzle is small, so a wide steel plate such as a steel plate is used. There is also a problem that it is not suitable for high-speed processing.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method capable of reliably adjusting the surface morphology of a steel sheet to a target value and a steel sheet having the surface morphology adjusted by the method. It is an issue.

[0018]

[Means for Solving the Problems] A first means for solving the above problems is to use a centrifugal projection device on one or both surfaces of a continuously conveyed steel sheet to obtain an average particle diameter of 30 to 300.
A method of controlling the surface morphology of the steel sheet by projecting solid particles of μm, the actual measurement value of the surface morphology of the steel sheet after projecting the solid particles, so that the target value of the surface morphology of the steel sheet, A method for controlling the surface morphology of a steel sheet (claim 1), characterized in that the projection conditions of particles are adjusted.

The control principle of the surface morphology used in this means is that solid particles having an average particle diameter of 30 to 300 μm are projected onto the surface of a steel plate,
By making a large number of solid particles collide with a steel sheet, a large number of indentations are formed on the surface thereof, and surface roughness is imparted by the unevenness.

The reason why the solid particles having an average particle diameter of 30 to 300 μm are used here is to form as dense as possible unevenness on the surface of a cold rolled steel sheet, a galvanized steel sheet or the like, and if the average particle diameter exceeds 300 μm. When the steel plate collides with the steel plate, the impact is large, so that an action of polishing the surface occurs. When the average particle size is 500 μm or more as in the prior art, the kinetic energy of the projected particles is large, so the size of the indentation formed on the surface of the steel sheet is significantly changed due to slight changes in the projection conditions. This is because the average roughness Ra and the like cannot be controlled with high accuracy. On the other hand, the average particle size is 30μ
Below m, it is not possible to impart sufficient kinetic energy for the projected particles to decelerate in the air and form irregularities on the surface of the steel sheet.

Further, in this means, a centrifugal type projection device is used as a means for projecting solid particles. The centrifugal projection device is a device that accelerates particles by the centrifugal force of a rotor that rotates at a high speed, has higher energy efficiency than the pneumatic projection device disclosed in Japanese Patent Laid-Open No. 3-294418, and the particles are fan-shaped. This is because it is excellent in that the particles can be projected over a wide range by being spread and projected onto.

Here, the morphological feature of the microscopic unevenness formed by projecting solid particles onto the surface of the steel sheet is that concave-shaped indentations are mainly formed on the surface of the galvanized steel sheet. Such a surface morphology has the effect of improving the oil retaining property with the die during press molding.

Therefore, the surface morphology of the steel sheet after the solid particles are projected means a concept having a dimple-like morphological feature formed by the solid matter formed on the surface of the steel sheet colliding with the surface. , The average roughness Ra, the peak count PPI of the steel plate surface, the waviness Wca of the steel plate surface, etc. are included as the parameters of the surface roughness. Further, it is a concept including the coverage of dimples formed by solid particles, the individual shapes and depths of recesses, the distance between adjacent recesses, and the like.

The present means is provided with a means for actually measuring such a surface morphology, which has a target value of the surface morphology of the steel sheet (a target morphological feature or a target value of a parameter expressing the morphological feature). The projection conditions of the solid particles are adjusted so that As described above, in the present means, the surface morphology of the steel sheet after the solid particles are projected (the morphological characteristic corresponding to the target value or the parameter expressing the morphological characteristic) is measured, and this measured value Since the projection conditions of the solid particles are adjusted so that the surface morphology reaches the target value, the surface morphology can be reliably maintained at the target value.

As described above, the present means is provided with the independent surface roughness imparting means, which solves the problem that the control range is narrow in imparting the surface roughness by temper rolling, thereby improving the material quality. It is possible to control over a wide range without restriction. Further, since the surface roughness does not change with time due to wear of the rolling rolls, the surface roughness can be stably imparted.

The solid particles used in this means are preferably spherical shot particles. As a device using a centrifugal projection device, a shot blast having a spherical particle shape or a grid blast having an angular shape is known. The former is usually used to obtain a shot peening effect that hardens the surface of the work piece, and the latter is usually used to grind the surface. Therefore, in imparting the surface roughness targeted by the present invention, it is desirable to use spherical shot particles in order to clean the surface to prevent damage as much as possible. Further, in the case of spherical solid particles, the indentation formed on the surface of the steel sheet is observed as a circle, so that the morphology is clearly discriminated and the dimple coverage is also clearly measured.

Further, it is desirable to use solid particles having a density of 2 g / cm ³ or more as the solid particles. When the density of the solid particles is less than 2 g / cm ³ , the mass of the solid particles is small, the damping in the air is large, and the kinetic energy itself when colliding with the steel sheet is small. Therefore, even if the projection conditions such as the rotor rotation speed are changed, the range in which the surface morphology can be controlled becomes narrow. For example, metal-based fine particles such as carbon steel, stainless steel, and high speed tool steel (high speed steel) are suitable. A cemented carbide such as tungsten carbide may also be used. However, even if alumina, zirconia, or glass beads has a relatively small specific gravity, it can be sufficiently used for the purpose of adjusting the surface roughness in the region where the average roughness Ra is 1 μm or less.

Further, regarding the particle size distribution of the particles, it is desirable that the weight ratio of the particles included in the particle size range of 0.5d to 2d is 85% or more with respect to the average particle size d. This is because when the particle size distribution is broad, the values of parameters such as average roughness Ra, peak count PPI, and waviness Wca do not change easily even if the projection conditions are changed, and controllability deteriorates. The particle size distribution of the particles may change over time due to crushing of solid particles when the particles are circulated and used, but the particle size distribution can be adjusted by arranging an appropriate classifier. It is easy to maintain within a certain range.

The second means for solving the above-mentioned problems is as follows.
In the first means, the surface morphology of the steel sheet has an average roughness Ra, a maximum roughness Rmax, a ten-point average roughness Rz, and a root mean square roughness.
Rq, peak count PPI, average mountain interval Sm, center line waviness W
It is characterized by being represented by one or more parameters of the coverage of ca and dimples formed by solid particles (claim 2).

The average roughness Ra is a parameter representative of the average height of irregularities of a short period obtained from the roughness curve.
However, not only the average roughness Ra but also the maximum roughness Rmax, the ten-point average roughness Rz, and the root mean square roughness Rq may be used as long as they are parameters indicating the heights of short-period irregularities.

The peak count PPI is the number of peaks and depressions per inch as defined by the SAE911 standard. That is, it is an index showing the length of the pitch of the unevenness of the steel sheet surface. The peak count PPI is also a parameter indicating the press workability of the steel sheet, and even if the average roughness Ra is the same, the oil retention between the steel sheet and the mold is improved as the PPI is increased, and the friction coefficient is reduced. The effect is obtained. However, the average crest interval Sm may be used as another parameter indicating the pitch of the unevenness.

The coverage of the dimples formed by the solid particles is an index showing the ratio of the dimple-shaped recesses formed by the solid particles colliding with the steel sheet to the surface area. It is 100% when the indentation is formed on the entire surface of the steel sheet. The greater the coverage of such dimples, the better the oil retention during press working, and the better the press workability. However, if the projection of solid particles is continued after the coverage rate approaches 100%, damage to the steel plate surface begins to occur, so in order to prevent damage to the plating film like galvanized steel sheet, the coverage rate is May also need to be limited to a certain value or less.

Average roughness Ra and peak count PPI
Can be measured based on the light reflection intensity distribution.
For example, regarding the light reflection characteristic analysis of the cold rolled steel sheet and its online surface roughness measurement, those described in Iron and Steel (70, 1984, p.1095) can be used. Furthermore, for the centerline waviness Wca, the frequency analysis of the light intensity distribution is performed, and the long-period frequency component is extracted to obtain the centerline waviness Wc.
There is a method of estimation based on the correspondence with the value of a.

On the other hand, regarding the coverage of the dimples, CC
The surface of the steel plate can be photographed by a D camera or the like, the dimple portion observed as a circle can be extracted, and the area can be analyzed and obtained by image processing.

Furthermore, by using a plurality of control means,
Not only average roughness Ra, but also maximum roughness Rmax and ten-point average roughness R
z, root mean square roughness Rq, peak count PPI, average crest interval S
Various surface morphologies such as m, center line waviness Wca, coverage of dimples formed by solid particles can be controlled, and important properties as a steel plate such as press formability of the steel plate and image clarity after painting can be controlled. can do.

A third means for solving the above problems is
In the first means or the second means, the adjusted solid particle projection condition is one of a rotor rotation speed of a solid particle projection device, a projection density of solid particles onto a steel plate, and a projection distance. Alternatively, it is a combination of a plurality of conditions (claim 3).

The rotor rotation speed of the solid particle projection apparatus can be changed by adjusting the motor rotation speed of the centrifugal projection apparatus, and the projection speed of particles accelerated by centrifugal force can be changed. The larger the projection velocity, the larger the kinetic energy of the solid particles, and the larger the indentation formed by the collision with the steel sheet. At this time, the average roughness Ra is increased due to the formation of the deep recess. In addition, the peak count PPI on the surface of the steel sheet is slightly reduced due to the increased pitch of the irregularities formed.

Further, the projected solid particles usually have a constant particle size distribution. Even if the initial velocity is the same, small particles are likely to decelerate in air and large particles are difficult to decelerate. . At this time, when the rotor speed is low, small particles among the projected solid particles do not have enough kinetic energy to form indentations on the surface of the steel plate due to deceleration in the air, so only large particles are applied to the surface of the steel plate. An indentation will be formed on.

On the other hand, when the rotational speed of the rotor is high, large particles form larger indentations, and smaller particles also form relatively smaller indentations on the surface of the steel sheet. Therefore, when compared with a constant coverage, the sizes of the indentations tend to be uniform when the rotor rotation speed is low, and the indentation sizes tend to be uneven when the rotor rotation speed is high. When the indentations are uneven in size, a large undulation remains in the surface profile after the short-period component is cut off, and the waviness Wca shows a large value. In other words, the higher the rotor speed, the larger the swell Wca.

On the other hand, the higher the rotor speed is, the larger the indentation formed by the collision of the solid particles is. Therefore, the area occupied by the indentation formed by one particle per unit area is increased. The coverage increases when is projected.

The projection density on the steel plate surface is defined as the weight of solid particles projected per unit area of the steel plate. The larger the projection density, the smaller the distance between the adjacent indentations, the higher the peak count PPI, and the higher the dimple coverage. However, by projecting a certain amount or more of solid particles, the entire surface of the steel sheet is covered with indentations, and the coverage ratio of the dimples becomes 100%.

Further, as the projection density increases, the size of the unevenness also increases and the average roughness Ra increases. However, if the coverage of dimples becomes 100% and unevenness due to indentation is formed on the entire surface and then the projection density is further increased,
Peak count because the irregularities once formed are crushed
PPI is slightly reduced. In addition, the waviness Wca also increases because the long-period unevenness becomes high.

The projection distance refers to the distance between the rotor of the centrifugal projection device and the steel plate, and here is the distance between the rotor rotation center and the steel plate. Usually, a centrifugal projection device is used to project solid particles having a size of about 500 μm to 2 mm. However, the solid particles targeted by the present invention limit the size of the solid particles to 30 to 300 μm in order to form fine irregularities on the surface of the steel sheet.

In this case, since the projected particles are decelerated in the air, if the projection distance becomes long, the kinetic energy of the solid particles colliding with the steel sheet decreases, and it becomes impossible to form sufficient indentations. Therefore, by making the projection distance closer to a certain value or less, an indentation can be formed on the surface of the steel sheet, and by making the distance even closer, a large indentation can be formed, so that the average roughness Ra increases. As a result, the peak count PPI decreases.

Further, in the case of projecting solid particles having a constant distribution, the shorter the projection distance, the smaller the particles have sufficient kinetic energy to form the indentation, and the depth distribution of the indentation becomes smaller. Becomes broader and swell Wca increases. Furthermore, since the size of the indentation is increased as a whole, the coverage of the dimples with respect to the constant projection amount is increased.

In this means, the surface morphology of the steel sheet can be controlled by combining the rotor speed, the projection density and the projection distance. For example, if the projection density is increased within the range where the dimple coverage is less than 100%, the average roughness Ra and the peak count PPI can be increased, and when the rotor speed is increased next, the average roughness Ra can be increased. Since the peak count PPI decreases with increasing, the combination allows fine tuning of the surface morphology.

Further, the projection distance is set to a certain value or more or the rotor speed is set to a certain value or less to prevent small solid particles from forming indentations, while increasing the projection density so that only indentations due to large particles are formed. The size of the unevenness can also be made uniform. That is, the rotor speed,
Average roughness Ra depending on the combination of projection density and projection distance
It is possible to arbitrarily control not only the height of the short-period concavo-convex such as the maximum height Rmax and the parameter representing the surface morphology.

The fourth means for solving the above-mentioned problems is as follows.
Any one of the first to third means is characterized in that an initial projection condition of solid particles is adjusted according to a preset steel plate condition. (Claim 4).

The form of the microscopic asperities formed on the surface of the steel sheet changes depending on not only the conditions on the side where the solid particles are projected, but also the conditions on the side of the steel sheet to be treated. Therefore, in this means, the characteristics of the steel plate to be treated and the operating conditions are reflected in the projection conditions, and the initial projection conditions of the solid particles are adjusted, so that feedback control works and the surface morphology is adjusted to the target value. It is possible to keep the surface condition close to the target value even before the temperature changes.

The fifth means for solving the above-mentioned problems is as follows.
In the fourth means, the preset steel plate condition is one or more of a conveying speed of the steel plate, a surface hardness of the steel plate, and a surface morphology of the steel plate before projecting solid particles. It is a combination (claim 5).

Even if the amount of solid particles supplied to the centrifugal projection device per unit time is constant, if the conveying speed is high, the projection density of the particles projected onto the steel plate is reduced and they are formed on the steel plate surface. The indentation becomes smaller and the average roughness Ra becomes lower. Therefore, the preset information on the transport speed of the steel sheet is reflected in the projection condition of the solid particles. For example, when the preset transportation speed is low, the projection amount of the solid particles is set to be small so that the projection density is not excessively adjusted.

Further, when the surface hardness of the steel sheet is high, even if solid particles are projected under the same conditions, it becomes difficult to form indentations on the surface of the steel sheet. This is because the plastic work required when the particles are pressed into the steel sheet surface increases. Therefore, in the present means, when trying to obtain the target value of the same surface morphology for steel plates having different surface hardness,
In accordance therewith, the projection conditions of the solid particles, that is, the rotor rotation speed, the projection density on the steel plate surface, the projection distance, etc. are changed. For example, when the preset surface hardness of the steel sheet is high, the rotor rotation speed is set to be high so that the indentations formed on the surface of the steel sheet become sufficiently deep.

On the other hand, the surface morphology after the solid particles are projected also changes depending on the surface morphology of the steel sheet before the solid particles are projected. For example, when the swell Wca before projecting the solid particles is large, the swell after projecting the solid particles also becomes large. In particular, in a steel plate that is required to have a high sharpness after painting, it is necessary to control the value of the waviness Wca below a certain value. When the value is relatively large, the projection density of the solid particles is set to be small, and the waviness Wca after the projection of the solid particles is adjusted to be a certain value or less.

Further, in the present means, it is possible to set a combination of a plurality of solid particle projection conditions as follows when the preceding steel plate having a low surface hardness has a high surface hardness. . That is, in principle, when trying to obtain the same average roughness Ra for any of the steel plates, the rotor speed may be increased for the subsequent steel plates. However, if the rotor speed is set to the upper limit of the machine capacity, the rotor speed cannot be increased any further, so it is possible to obtain the target value of the average roughness Ra by shortening the projection distance. it can.

On the other hand, since the average roughness Ra can also be increased by increasing the projection density, the projection density is adjusted when the rotor rotation speed is the upper limit of the capacity and the projection distance cannot be further shortened. In that case, it is possible to take a means of controlling the average roughness Ra to a target value.

The surface morphology of the steel sheet before the solid particles are projected means the average roughness Ra, the maximum roughness Rmax, and the ten-point average roughness in the same manner as the surface morphology of the steel sheet after the solid particles are projected. It
Rz, root mean square roughness Rq, peak count PPI, average crest interval S
It is represented by one or more parameters of m, centerline waviness Wca, and coverage of dimples formed by solid particles. The dimple coverage is taken into consideration when the steel sheet after solid particle projection is treated again, or when the steel sheet on which dimples are formed by another method such as temper rolling is treated.

A sixth means for solving the above-mentioned problems is as follows.
In the fifth means, the preset steel plate condition is one or more of a conveying speed of the steel plate, a surface hardness of the steel plate, and a surface morphology of the steel plate before projecting solid particles. It is a combination (claim 6).

The conveying speed of the steel sheet normally changes during operation due to acceleration, deceleration, etc. Therefore, the conveying speed of the steel sheet is measured online, and the projection condition of the solid particles is changed according to the measured value. For example, when the transport speed is accelerated, it is possible to keep the projection density constant by increasing the projection density, and it is possible to obtain a constant average roughness Ra. However, to change the projection density, it is necessary to change the amount of particles supplied to the centrifugal projection device, and the time from when a command is issued to change the opening of the particle supply valve to when the amount of projection particles actually changes. When the delay is large, the rotor speed, which has a faster response, is temporarily increased to compensate the average roughness so as not to decrease, and the rotor speed is adjusted according to the increase of the solid particle projection amount. The control may be performed such that the set value is gradually returned. In this case, the surface morphology of the steel sheet can be accurately controlled even with more rapid acceleration / deceleration.

It is also effective to measure the surface morphology of the steel sheet before projecting the solid particles online to change the projection conditions of the solid particles. The steel plate surface morphology before projecting solid particles may vary in the longitudinal direction of the steel plate depending on the operating conditions of the previous process. In response to such fluctuations, the surface morphology of the steel sheet is measured before projecting solid particles,
The projection conditions are set accordingly. For example,
The waviness Wca on the surface of the steel sheet before the solid particles are projected may change gently between the front end portion and the rear end portion of the steel sheet. In this case, the swell Wca is measured before the solid particles are projected, and the Wca after the solid particles are projected can be kept at a target value by adjusting the projection conditions of the solid particles in response to changes in the value. it can.

The seventh means for solving the above-mentioned problems is as follows.
Any one of the fourth to sixth means, wherein the initial solid particle projection conditions are the preset steel plate conditions, and the surface morphology of the steel plate after the solid particles are projected, It is determined based on a database that stores the relationship with the projection condition of the solid particles (claim 7).

The surface morphology of the steel sheet after the solid particles are projected differs depending on the steel sheet conditions to be treated and the solid particle projection conditions. This means measures these relationships in advance and accumulates them in a database, retrieves the steel plate conditions of the steel plate to be newly processed and the projection conditions corresponding to the target surface morphology from past performance values, and The projection condition is set. In the database, information on the surface morphology of the steel sheet after projecting solid particles (for example, average roughness Ra, peak count PPI, dimple coverage, etc.), steel sheet conditions to be processed (for example, plate thickness, yield stress) , Surface hardness, plating film composition, etc.) and solid particle projection conditions (rotor speed, projection density, projection distance, etc.) are stored separately as table values. A method of searching for a projection condition that matches the table classification is simple.

The eighth means for solving the above-mentioned problems is as follows.
The seventh means, wherein the database is updated based on the relationship between the preset steel plate conditions, the surface morphology of the steel plate after the solid particles have been projected, and the solid particle projection conditions. (Claim 8).

As the number of processed steel sheets increases, the number of record data accumulated in the database increases. At this time, more appropriate projection conditions can be set by updating the information in the database based on the latest data. For example, it is possible to update the data for each table section by simple learning such as exponential smoothing.
Further, recently, a new learning method such as just-in-time modeling has been developed, which is effective in processing a large amount of accumulated data in a short time.

The ninth means for solving the above problems is as follows:
It is a steel sheet whose surface morphology is adjusted by using the surface morphology control method according to any one of the first to eighth means.

The steel sheet whose surface roughness is controlled by the steel sheet surface morphology control method according to any one of the first to eighth means, has a dimple-like surface morphology and is mainly formed with a large number of recesses. Become. In order to form a similar surface morphology by the method of transferring the microscopic unevenness of the roll in the conventional temper rolling, it is necessary to form a large number of microscopic convex portions on the surface of the rolling roll. However, in general, shot blasting, electric discharge machining, laser machining, electron beam machining, etc., which are general roll surface processing means, are means for imparting concave portions to the roll surface in principle, and microscopic convex portions are used. Is difficult to form. Even if such processing is possible, the convex portions of the roll surface are preferentially worn during the temper rolling process, and the change in surface roughness over time is large.

On the other hand, in a steel sheet whose surface morphology is controlled by the surface morphology control method for a steel sheet according to any one of the first to eighth means, such a change with time does not occur. Also, the surface has a uniform surface roughness in the longitudinal direction. Therefore, even when it is used for press molding, the problem that the press moldability changes for each product does not occur.

A tenth means for solving the above-mentioned problems is the steel plate which is the ninth means, and is characterized in that information on the surface morphology of the steel plate after the solid particles are projected onto the steel plate is attached. It is a steel plate (claim 10).

The steel sheet whose surface roughness has been adjusted by the above means has a surface morphology greatly different from that of the conventional steel sheet to which the surface roughness has been imparted by temper rolling, and due to its dimple-like shape, press forming is performed. It has excellent properties. Therefore, when it is used for press forming, it can be selected and used for more severe press forming by managing it by distinguishing it from the steel plate by the conventional temper rolling method. Therefore, the steel plate with the surface morphology adjusted by this means and the information attached thereto facilitates the management when the user uses it for press forming, and the steel plate with appropriate characteristics can be used for appropriate press forming. it can.

[0069]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a diagram showing an outline of equipment for carrying out an example of the present invention. While continuously transporting the steel sheet 1, the surface roughness of the steel sheet 1 is measured by a plurality of centrifugal projection devices 3a to 3d. The equipment for adjusting is shown. As the steel sheet 1, a cold rolled steel sheet, a galvanized steel sheet, or the like is used. In the case of a cold rolled steel sheet, it is desirable that cold rolling, continuous annealing, and temper rolling be performed to adjust mechanical properties. Further, in the case of imparting the surface roughness to the hot-dip galvanized steel sheet, it is suitable that it is cold-rolled, annealed, plated, and temper-rolled. However, it is also possible to pass through this line before applying temper rolling to impart surface roughness, and then to temper rolling. Further, the steel sheet 1 is not limited to the cold rolled steel sheet or the galvanized steel sheet, and other surface-treated steel sheets may be used.

FIG. 4 shows a type of equipment in which a steel plate is loaded on the pay-off reel 30 and wound on the tension reel 31. At this time, the steel plate is continuously conveyed in a state where tension is applied between the entrance-side bridle roll 11 and the exit-side bridle roll 13.

The centrifugal projection devices 3a to 3d are arranged in the blast chamber 2 surrounded by the chamber. The particles projected from the centrifugal projection devices 3a to 3d are collected in the blast chamber 2 and transferred to the classifier 6. The particles from which foreign substances and crushed particles have been removed by the classifier 6 are sent to the centrifugal projection devices 3a to 3d through the storage tank 5.
Although not shown in the figure, the dust selected by the classifier is sent to the dust collector for dust collection processing. In addition, on the downstream side of the blast chamber, the surface morphology measuring devices 15a and 15b are provided.
By arranging, it becomes possible to compare the target surface morphology with the actual value. However, it is not always necessary to arrange them on the front and back surfaces, and they may be arranged on either the front surface or the back surface.

1 and 2 are views showing a centrifugal projection device for controlling the surface morphology of a steel plate and a system for controlling the surface roughness, which is an example of the embodiment of the present invention. 4 is a detailed view of the periphery of the centrifugal projection devices 3a to 3d shown in FIG. 1 shows a side view of the centrifugal projection device, and FIG. 2 shows a front view of the centrifugal projection device.

The centrifugal projection device projects solid particles from a vane 42 attached to a rotor 41 driven by a motor 43 by centrifugal force. Motor 43
The command of the rotation speed is given from the rotor rotation speed control device 46.

The solid particles are supplied from the storage tank to the rotor 41 through the particle supply pipe 43, and an opening adjustment valve 44 is arranged in the middle thereof, and the opening is adjusted to control the supply amount of the solid particles. can do. The opening of the opening adjustment valve 44 is controlled by the projection amount control device 47. If the relationship between the supply amount of solid particles and the opening degree is obtained in advance by an experiment or the like, the opening degree corresponding to the target supply amount can be determined.

Further, the centrifugal projection device is integrally arranged on the elevating frame 45, and the projector height control device 49 is provided.
The height is adjusted based on the command of the projection distance. The range of the projection distance is 1500 mm or less, preferably 700 mm or less. Even if you increase the projection distance too much,
This is because the fine particles in the air slow down and cannot effectively give the surface roughness. Also, the particle size is 150 μm
When projecting the following solid particles, as the projection distance,
It is desirable that the distance can be varied from a distance slightly larger than the vane radius to a distance about twice the vane outer diameter with reference to the same distance as the vane outer diameter. This is because finer particles are easier to decelerate in the air, and it is useless even if the projection distance is a certain distance or more.

Further, when a plurality of projectors are arranged in order to control the surface roughness of a wide steel plate, a mechanism capable of independently adjusting the projector height of each projector is adopted, It is also possible to adjust the surface roughness at each position. Since the equipment structure of the elevating frame for adjusting the projection distance is complicated, a device for fixing the same may be used as a system in which only the rotor speed or the projection density is changed. Although FIG. 1 shows a form in which solid particles are projected onto the front surface of the steel sheet, the same form may be adopted when projecting onto the back surface.

On the other hand, the surface morphology after solid particle projection is measured by the surface morphology measuring devices 15a and 15b. Further, as shown in FIG. 1, surface morphology measuring devices 15c and 15d for measuring the surface morphology before solid particle projection may be arranged. Further, a speedometer 52 for measuring the transport speed of the steel sheet may be arranged.

Further, the information indicating device 51 for the material to be treated has the target average roughness Ra, peak count PPI, center line waviness W.
Target values such as the coverage of dimples formed by ca and solid particles are given, and information such as steel type and surface hardness is given as steel plate conditions.

In the embodiment shown in FIG. 1, the information by the information indicating device 51 of the material to be processed is sent to the surface morphology control database 53 together with the actual measurement data by the surface morphology measuring devices 15a to 15d and the speedometer 52, and the past It is stored together with the data of. The surface morphology control device 50 searches the data stored and updated in the surface morphology control database 53 for the corresponding projection conditions such as the rotor rotation speed, the projection density, and the projection distance. However, it is not always necessary to use a database, and the projection conditions may be set based on a physical model for indentation formation by the projection of solid particles. Conditions may be set.

FIG. 3 shows a control flow of the method for controlling the surface roughness of the steel sheet as described above. The processing in each step of this control flow will be described below. The flowchart is activated each time a new coil (steel plate) reaches the device.

(S1) Setting of Information on Steel Plate to be Processed Steel plate conditions of a steel plate to be processed are preset. These values are given from the information indicating device 51 of the steel to be treated. Steel plate conditions include surface hardness of steel plate, conveying speed of steel plate,
The surface morphology of the steel sheet before the solid particles are projected. The surface morphology of the steel sheet before projecting the solid particles, the average roughness Ra,
Peak count PPI, center line waviness Wca, dimple coverage, etc. The information is input as the information of the steel sheet to be processed under one or more of these conditions.

The dimple coverage is taken into consideration when the steel sheet after solid particle projection is treated again or when the steel sheet on which dimples are formed by another method such as temper rolling is treated. As for these pieces of information, information measured online or information measured in advance is input to the surface morphology control database.

(S2) Setting of Target Value of Steel Plate Surface Morphology after Solid Particle Projection A target value of steel plate surface morphology after solid particle projection is set and input to the surface morphology control database. This value is given from the information indicating device 51 of the steel material to be treated.

(S3) Determination of solid particle projection conditions Of the rotor speed, the projection density on the steel plate, and the projection distance, 1
Alternatively, a plurality of conditions are set as initial solid particle projection conditions. Based on the preset information of the steel plate to be treated set in (S1) and the target value of the steel plate surface morphology after the solid particle projection set in (S2), the most preferable condition is set as the initial solid particle projection condition. Set.

(S4) Surface morphology measurement after solid particle projection The surface morphology after solid particle projection is measured, and the measured value is input to the surface morphology control database.

(S5)-(S6) Comparison of Measured Value and Target Value of Steel Plate Surface Morphology The measured value and target value of the steel plate surface morphology are compared, and if the error is below a certain value, the projection condition is set. When the error is large, the projection condition of the solid particles is corrected and the control is performed so as to match the target value.

Regarding how to combine the command values of the actuators as the projection condition of the solid particles, the priority order of the actuators to be operated is set in advance for the parameter to be adjusted, and the independent actuators are set. When the control cannot be performed only by itself, a method of operating another actuator can be adopted.

For example, in order to adjust the average roughness Ra, there is a method of preferentially adjusting the rotor rotation speed and changing the projection density when the rotor rotation speed alone cannot be adjusted. Also, in order to adjust the peak count PPI, the rotor speed is adjusted preferentially, the projection density is changed when the rotor speed alone cannot be adjusted, and the projection distance is changed when the rotor speed cannot be adjusted. You may take the method.

Further, a method of presetting a combination of the changing amounts of the actuators to be operated with respect to the parameters to be adjusted may be adopted. For example, the amount of change in the rotor rotation speed and the projection density for changing the waviness Wca by a certain amount is set in advance, and for the waviness Wca to be changed,
This is a method of giving a change command while holding the change ratio of each actuator.

Furthermore, average roughness Ra and peak count PPI
In the case of controlling both of them to the target values, it is possible to adopt a method of previously setting the actuator to be operated corresponding to each parameter. For example, the average roughness Ra is controlled by changing the rotor speed, and the peak count PPI
For, the projection density is changed.

When the difference between the target value and the measured value of the steel plate surface morphology exceeds the allowable range, the process returns to (S3), and the solid particle projection condition is re-determined according to this difference (this re-determination The method can use normal feedback control such as PID control).

(S7) Judgment of Completion of One Coil It is judged whether one coil is completed, and if not completed, the procedure returns to (S4) to measure the steel plate surface morphology. If one coil is completed, the process is ended and the process for a new coil is started.

FIG. 5 shows equipment for carrying out the control of the surface morphology of the steel sheet which is another embodiment of the present invention. Figure 5
FIG. 4 is a diagram showing a continuous hot-dip galvanizing line. The temper rolling mill 20 is arranged on the downstream side of the plating bath 34 of the hot dip galvanizing line, and the forced drying device 22 is further arranged on the downstream side thereof.
It is an equipment row in which the blast chamber 2 is arranged. In the hot-dip galvanizing line, the cold-rolled steel sheet is charged into the payoff reel 30, and recrystallization annealing is performed in the annealing furnace 33.

Then, after forming a zinc plating film in the plating bath 34, the film thickness is adjusted by the air wiper 35. Then, in the case of producing an alloyed hot-dip galvanized steel sheet, the alloying furnace 36 is operated to perform alloying treatment. However, a galvanized steel sheet whose film produced mainly without using the η layer is also produced in the same line.

In a normal hot-dip galvanizing line, after the temper rolling is performed by the temper rolling mill 20, the case where the chemical conversion film is applied by the chemical conversion treatment device 37 and the case where the rust preventive oil is applied and the winding is performed as it is. May be taken. On the other hand, FIG.
In the embodiment, the nozzles 25a to 25d for injecting water or the temper rolling liquid are arranged on the inlet side and the outlet side of the temper rolling, and the forced drying device 22 is arranged further downstream thereof.
This is because after pre-drying the water attached to the steel plate,
This is for projecting solid particles.

By arranging in the equipment row as described above, in the temper rolling mill, the temper rolling is performed using the bright roll in order to adjust the mechanical characteristics of the material, and the centrifugal type is arranged on the downstream side. A projection device can be used to adjust the surface roughness of the galvanized steel sheet. The detailed diagram and control block diagram of the centrifugal projection device may be the same as those shown in FIGS.

[0097]

<Example 1> As a first example of the present invention,
With a cold-rolled steel sheet with a thickness of 0.8 mm as a base, hot-dip galvanized steel sheet whose plating film mainly consists of η phase, the centrifugal projection device shown in FIG. The control result will be described.

The steel sheet before the projection of solid particles was used after hot dip galvanizing and then subjected to temper rolling to give an elongation of 0.8%. The purpose of imparting the elongation rate in temper rolling was to adjust the material quality, and a bright roll was used. The steel plate after temper rolling had an average roughness Ra of 0.25 μm and a peak count PPI of 48.

The centrifugal projection device used had a rotor diameter of 33
It is a device with 0 mm and maximum projection speed of 92 m / s. As solid particles, spherical stainless steel with an average particle size of 65, 12
Particles adjusted to 0, 220 μm were used. In this embodiment,
The rotor speed was changed while controlling the projection density to 8 kg / m ² and the projection distance to 350 mm.

FIG. 6 shows the relationship among the rotor speed, the average roughness Ra, the peak count PPI, and the waviness Wca. The average roughness Ra increases almost linearly as the rotor speed increases. The larger the average particle diameter is, the higher the average roughness is, and the change amount of the average roughness with respect to the change of the rotor rotation number is increased. In conventional technology, particle size is 50
Since a large one of 0 μm or more is used, even if the rotor rotational speed is slightly changed, the average roughness is greatly changed, and it is not possible to control with high accuracy.

Further, the peak count PPI tends to gradually decrease with the increase of the rotor rotation speed except for the case of the average particle diameter φ65 μm. This is because the indentation of the particles becomes large and the interval between the indentations increases as the number of rotations of the rotor increases. When the average particle diameter is 65 μm, the dimples formed on the surface become finer as the rotor rotation speed becomes lower, and their pitch is obviously shorter, but the average roughness Ra itself becomes smaller, Since the irregularities exceeding the peak count PPI count level of ± 0.635 μm are reduced, the PPI value itself decreases. Therefore, if the average roughness Ra is too small, the dimples with a short pitch may be formed, but the PPI may be small, and as the rotor speed increases, the PPI tends to rise and then decrease. .

On the other hand, the waviness Wca tends to increase with an increase in the number of rotations of the rotor, and is particularly remarkable when the average particle size is large. This is because when the average particle size is small, fine dimples are formed with a short pitch, and it is difficult for undulations with a long period to appear.

As described above, the parameters such as the average roughness Ra can be controlled by adjusting the rotor rotation speed. Taking advantage of this property, using the equipment as shown in FIG. 1, the parameters indicating the surface morphology are the average roughness Ra, the peak count PPI, and the center line waviness Wca, respectively, and the rotor rotation is used as the projection condition of the solid particles. As a result of performing feedback control by taking a number, in each case, each parameter could be maintained at the target value.

Example 2 In this example, the same test as in Example 1 was conducted, and the average roughness was determined by the projection density of solid particles.
Controlled Ra etc. With the projection distance kept constant at 350 mm, the rotor rotation speed was 3600 rpm for the average particle diameter φ65 μm, and the rotor rotation speed was 3000 rpm for the average particle diameter φ120 μm.
In addition, the rotor rotation speed is 2200 for the average particle diameter of 220 μm.
set to rpm.

FIG. 7 is a diagram showing the influence of the projection density on the surface morphology. The average roughness Ra tends to increase as the projection density increases. However, when the projection density becomes a certain value or more, the increasing method becomes gentle. Further, the peak count PPI increases with an increase in the projection density, and a region where the peak count PPI becomes almost constant appears even if the projection density changes. When the projection density is further increased, the peak count tends to decrease because the solid particles are repeatedly projected on the irregularities of the surface once formed.

On the other hand, the waviness Wca increases as the projection density increases. When the average particle size is small, the waviness increases slowly, but when the average particle size is large, the waviness Wca tends to increase rapidly. When the image clarity after painting is required for steel sheets for automobiles, etc.
Since it is necessary to reduce Wca, it is necessary to use one having a small average particle diameter or to control the surface morphology in a region where the projection density is small.

As for the dimple coverage, the image shown in FIG. 10 can be obtained by extracting the region covered with the dimples from the surface of the steel sheet shown in FIG. 9 formed by the projection of solid particles. The filled portion in FIG. 10 is the dimple covered portion, and the coverage can be defined as the area ratio. From FIG. 7, the coverage increases with the increase of the projection density, and when the projection density becomes a certain value or more, the coverage becomes almost 100%. When the coverage of the dimples is large, the number of indentations formed is large, so that the oil retaining property at the time of press working is improved and the workability is improved. However, if the projection density is increased too much, the peak count will decrease. Therefore, the target value of the coverage is set and controlled so that the peak count does not decrease.

Utilizing this property, using the equipment as shown in FIG. 1, the parameters showing the surface morphology are average roughness Ra, peak count PPI, and center line waviness Wca, respectively.
As a result of performing the feedback control by taking the projection density of the solid particles as the projection condition of the solid particles, in each case, the respective parameters could be maintained at the target values.

Example 3 In this example, the same test as in Example 1 was conducted, and the average roughness Ra etc. was controlled by the projection distance. With the projection density kept at 8 kg / m ² and the rotor rotational speed kept constant at 3800 rpm, particles with average particle diameters of 65, 120 and 220 μm were used, and the average roughness etc. when the projection distance was changed were investigated.

FIG. 8 is a diagram showing the influence of the projection distance on the surface morphology. The average roughness Ra tends to decrease as the projection distance increases. This is because the kinetic energy at the time of colliding with the steel plate decreases due to the deceleration in the air. In addition, the peak count PPI is
Although it tends to increase with the increase of the projection distance, in the case of fine particles having an average particle size of 65 μm, the peak count once increases with the increase of the projection distance and then tends to decrease. This is because as the projection distance increases, the height of the unevenness provided on the steel plate surface decreases, and the number of unevennesses that do not exceed the count level of the peak count increases.

On the other hand, the waviness Wca decreases as the projection distance increases. When the average particle size is small, the absolute value of the waviness is originally small, and therefore the decrease is gentle, but when the particle size is large, a remarkable change occurs. Taking advantage of this property, using the equipment as shown in FIG. 1, the parameters showing the surface morphology are the average roughness Ra, the peak count PPI, and the centerline waviness Wca, respectively. As a result of performing the feedback control by taking the projection distance of, each parameter could be maintained at the target value in any case.

Example 4 As a fourth example of the present invention, as a cold rolled steel sheet having different yield stress and a galvanized steel sheet having different coating hardness, a galvanized steel sheet having a zinc coating mainly composed of an η layer, an alloy The average roughness is changed by changing the rotor speed while adjusting the projection density to the condition that the coverage of the dimples is 90% or more, using a hot-dip galvanized steel sheet and a steel sheet with an aluminum-zinc alloy coating. The following is an example. The projection distance was constant at 350 mm.

FIG. 11 shows the relationship between the Vickers hardness Hv of the steel sheet surface and the average roughness Ra. The higher the hardness, the more difficult it is to form indentations due to solid particles, and the average roughness tends to decrease. At this time, when controlling the average roughness Ra in the range of 0.7 ~ 0.8 μm, even if the type of steel plate to be processed in a wide range of Vickers hardness Hv of 60 ~ 185 changes, the rotor speed of 2300 ~ 3600 rpm The average roughness can be controlled to be constant by adjusting the range. Also, Vickers hardness Hv
Shows that the average roughness Ra can be changed in a wide range of 0.6 to 1.1 μm by adjusting the rotor rotation speed in the same range for a steel plate of 100.

Utilizing this property, parameters such as the surface morphology are averaged by Ra using the equipment as shown in FIG. 1, and the rotor rotation speed is taken as the projection condition of the solid particles, and the feedback is performed. Control was performed. As a result, the average roughness Ra could be maintained at the target value even if the Vickers hardness of the steel sheet changed.

[0115]

As described above, according to the present invention,
It is possible to change the surface morphology such as average roughness in a wider range as compared with the conventional technique, and it is possible to provide a uniform surface morphology that does not change with time.

[Brief description of drawings]

FIG. 1 is a front view of a centrifugal projection apparatus used for implementing the present invention and a view showing a control system.

FIG. 2 is a side view of a centrifugal projection device used for implementing the present invention and a diagram showing a control system.

FIG. 3 is a diagram showing a control flow that is an example of an embodiment of the present invention.

FIG. 4 is a diagram showing an outline of an example of equipment for implementing the present invention.

FIG. 5 is a diagram showing an outline of another example of equipment for implementing the present invention.

FIG. 6 is a diagram showing the relationship between the rotational speed of a centrifugal projection device rotor and the average roughness of a steel plate.

FIG. 7 is a diagram showing the relationship between the projection density of solid particles and the average roughness of a steel sheet.

FIG. 8 is a diagram showing a relationship between a projection distance of solid particles and an average roughness.

FIG. 9 is a diagram showing an example of a surface photograph of a steel sheet obtained by the present invention.

FIG. 10 is a diagram showing a processing result for obtaining a dimple coverage.

FIG. 11 is a diagram showing the relationship between the surface hardness of a steel sheet and the average roughness.

[Explanation of symbols]

1: Steel plate, 2: Blast chamber, 3a to 3d: Centrifugal projection device, 5: Storage tank, 6: Classifier, 7: Cleaner blower, 10, 11, 13: Bridle roll, 1
4: Inspection table, 15a to 15d: Surface morphology measuring device, 2
0: Temper rolling mill, 22: Forced drying device, 25a to 25
d: injection nozzle of water or temper rolling liquid, 30: payoff reel, 31: tension reel, 33: annealing furnace, 3
4: plating bath, 35: air wiper, 36: alloying furnace,
41: rotor, 42: vane, 43: motor, 44:
Opening adjustment valve, 45: Projector table, 46: Rotor speed control device, 47: Projection amount control device, 49: Projector height control device, 50: Surface form control device, 51: Information indication of steel plate to be processed Device, 52: Speedometer, 53: Surface morphology control database

Continued front page    (72) Inventor Masayasu Ueno             1-2-1, Marunouchi, Chiyoda-ku, Tokyo             Main Steel Pipe Co., Ltd. (72) Inventor Shogo Tomita             1-2-1, Marunouchi, Chiyoda-ku, Tokyo             Main Steel Pipe Co., Ltd.

Claims (10)

[Claims] 1. An average particle size of 30 to 300 μm is applied to one or both sides of a continuously conveyed steel sheet by using a centrifugal projection device.
A method for controlling the surface morphology of a steel sheet by projecting solid particles, wherein the actual measurement value of the surface morphology of the steel sheet after projecting the solid particles becomes a target value of the surface morphology of the steel sheet, A method for controlling the surface morphology of a steel sheet, which comprises adjusting the projection conditions of. 2. The surface morphology of the steel sheet has an average roughness Ra, a maximum roughness Rmax, a ten-point average roughness Rz, a root mean square roughness Rq, a peak count PPI, an average mountain interval Sm, a center line waviness Wca, and a solid. 1 out of the coverage of dimples formed by particles
Alternatively, the method for controlling the surface morphology of the steel sheet according to claim 1, wherein the method is represented by a plurality of parameters. 3. The projection condition of the solid particles to be adjusted is
A combination of one or a plurality of conditions among the number of rotations of the rotor of the solid particle projection device, the projection density of the solid particles on the steel plate, and the projection distance.
The method for controlling the surface morphology of the steel sheet according to. 4. The surface morphology of the steel sheet according to claim 1, wherein the initial projection conditions of solid particles are adjusted according to preset steel sheet conditions. Control method. 5. The steel plate condition set in advance is a combination of one or a plurality of conditions among a conveying speed of the steel plate, a surface hardness of the steel plate, and a surface morphology of the steel plate before projecting solid particles. The method for controlling the surface morphology of a steel sheet according to claim 4. 6. The surface morphology control of the steel sheet according to claim 5, wherein the transport speed of the steel sheet and the surface morphology of the steel sheet before projecting the solid particles are measured online. Method. 7. The initial solid particle projection conditions store the relationship between the preset steel plate conditions, the surface morphology of the steel plate after the solid particles have been projected, and the solid particle projection conditions. It determines based on a database, The surface form control method of the steel plate of any one of Claim 4 to 6 characterized by the above-mentioned. 8. The database is updated based on the relationship between the preset steel plate conditions, the actual surface morphology of the steel plate after the solid particles are projected, and the actual projection conditions of the solid particles. The method of controlling the surface morphology of a steel sheet according to claim 7, wherein 9. A steel sheet whose surface morphology is adjusted using the surface morphology control method according to any one of claims 1 to 8. 10. The steel sheet according to claim 9, wherein information on the surface morphology of the steel sheet after projecting the solid particles is attached.