JPH0957166A - Film thickness control method for roll coater type coating equipment - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a film thickness control method capable of controlling the film thickness with high accuracy when continuously coating a strip-shaped material such as a cold rolled steel sheet by a roll coater type coating device. Kind Code: A1 In a roll coater type coating apparatus, a paint viscosity μ, an average peripheral velocity U _{m of} a pickup roll and an applicator roll, and a thickness L of an elastic material on the applicator roll.
And the elastic coefficient E are combined to obtain the coating thickness of the strip-shaped material from the index (μU _m L / E), the pushing amount between the pickup roll and the applicator roll, and the peripheral speed ratio between the applicator roll and the backup roll. Controls the film thickness to be coated based on the model formula.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film thickness control method capable of controlling the film thickness with high accuracy when continuously coating a strip-shaped material such as a cold rolled steel sheet by a roll coater type coating device.

[0002]

2. Description of the Related Art Conventionally, a roll coater type coating apparatus is most widely used for continuously applying a coating material to a strip-shaped material such as a steel plate or paper. Generally, a roll coater type coating device used for continuous coating of steel plates is a steel pickup roll that pulls up the paint in the paint pan and a rubber that receives the paint from the pickup roll and transfers the paint to the surface of the steel plate for coating. It consists of two rolls of lined applicator rolls, or three rolls of metering rolls which are also connected to the applicator roll.

When coating with this roll coater, the coating film thickness is controlled by the peripheral speed ratio of the roll, the pickup roll and the applicator roll, or the applicator roll and the metering roll with respect to the transport speed of the steel sheet. It is performed by appropriately controlling the pressed state and the pressed state between the steel plate and the applicator roll. Recently, coated steel sheets have been widely used in electrical products, automobiles, etc., and due to requirements for rust prevention, workability, weldability, etc., the precision required for coating film thickness has also become extremely high. .

Conventionally, as a method of controlling the coating film thickness when coating with a roll coater, Japanese Patent Publication No. 60-54110, Japanese Patent Publication No. 60-54111, and Japanese Patent Publication No. 61-20.
No. 30, the method of measuring the undried film thickness after coating or the dry film thickness on the outlet side of the drying furnace, and feeding back to the pushing pressure between the pickup roll and the applicator roll, and Japanese Patent Laid-Open No. 4-145975 discloses a method in which the amount of pushing in the past coating conditions is memorized, and the coating is performed by reproducing the amount, and likewise, Japanese Patent Laid-Open No. 58-166959 discloses a pickup roll and an application. A method is disclosed in which the pressing force between the trolls is controlled based on the pressing force applied in the past and data on the coating film thickness. Furthermore, in addition to the above, Japanese Patent Laid-Open No.
Japanese Patent Laid-Open No. 270759 and Japanese Patent Laid-Open No. 5-220441 disclose a method of controlling the pressing force between the pickup roll and the applicator roll or the roll peripheral speed based on a model formula, which corresponds to the required film thickness. ing.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
No. 110, Japanese Patent Publication No. 60-54111, and Japanese Patent Publication No. 61-2030, the undried or dried coating film thickness is measured by a non-contact method, and the results are picked up and an applicator roll. In the method of feeding back the indentation pressure during the measurement, online measurement of the wet film thickness is performed by measuring the material of the material to be coated, the plate thickness or the plating thickness if it is a plated base material, The measurement accuracy varies due to the influence of the type, and constant correction is required.

Further, when an online coating film thickness meter is installed on the outlet side of the drying furnace, the accuracy of film thickness measurement is improved as compared with the undried coating film, but the detected coating film thickness is fed back to the coating film thickness meter. When controlling the thickness, there is a problem in that there is a time lag corresponding to the distance from the roll coater to the coating thickness gauge, and it is not possible to grasp the variation in the coating thickness during this time.

Further, a method of coating by storing the amount of indentation under past coating conditions in Japanese Patent Laid-Open No. 4-145975 and reproducing the same is to deal with changes with time in paint viscosity and rubber elastic coefficient during coating. Can not. Similarly, in the method of controlling the pressing force between the pick-up roll and the applicator roll of JP-A-58-166959 based on the pressing force applied in the past and the data on the coating film thickness, the type of paint and its dilution ratio are used. It is necessary to experimentally find the conditions for making the coating film thickness constant corresponding to all the conditions such as the moving speed of the steel plate, the roll peripheral speed ratio, and the target coating film thickness. It takes time. Also,
As in the case described above, it is not possible to deal with changes over time during operation under each condition.

Further, the pressing force between the pickup roll and the applicator roll and the roll peripheral speed are changed according to the required film thickness in JP-A-3-270759 and JP-A-5-220441 based on the model formula. In this method, the pressing force between the rolls is difficult to control because of the sliding resistance at the roll supporting portion, and the change in the rubber thickness due to the swelling of the rubber roll on the applicator roll cannot be captured. Further, in the film thickness control method by changing the peripheral speed, changing the peripheral speed in order to obtain the required film thickness leads to deterioration of the coating film surface property due to instability of the coating film flow. .

As described above, each of the conventional methods for controlling the film thickness of the coating film in the roll coater type coating device has some problems. The present invention eliminates these problems and provides a coating film thickness control method capable of always controlling the film thickness with high accuracy.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted various experiments and researches in order to achieve the above-mentioned object. μ, average peripheral velocity Um of pickup roll and applicator roll, and thickness L of elastic material on the applicator roll
And the reciprocal of the elastic modulus (1 / E) can contribute at the same rate. The index that combines these four operating factors and the amount of pushing between rolls and the speed ratio between the applicator roll and the conveyor belt are A model formula is derived from the relationship between the three operating factors and the coating film thickness formed on the strip material, and the coating film thickness is set and controlled based on this model formula. We have found that control is possible. The present invention has been completed as follows based on the above findings.

(1) A roll coater type coating apparatus comprising a pickup roll, an applicator roll whose surface is made of an elastic material, and a backup roll which supports a belt-shaped material, or an applicator where the pickup roll and the surface is made of an elastic material. In a film thickness control method of a roll coater type coating apparatus including a backup roll supporting a roll and a belt-shaped material and a metering roll connected to the applicator roll, a coating viscosity μ, a pickup roll and an applicator roll Average peripheral speed U _m (however, when the device configuration includes a metering roll, average peripheral speed of the applicator roll and the metering roll), an index that combines the thickness L of the elastic material on the applicator roll and the elastic coefficient E and (μU _m L / E), pick-up roll and the applicator roll Derived the coating thickness of the band-shaped material from the pushing amount (however, if the device configuration includes a metering roll, the pushing amount between the applicator roll and the metering roll) and the peripheral speed ratio of the applicator roll and the backup roll. A method for controlling the film thickness of a roll coater type coating apparatus, characterized in that the film thickness to be coated is controlled based on the model formula.

(2) During continuous coating, the viscosity of the paint and the elastic coefficient E and thickness L of the elastic material on the applicator roll are measured, and between the pickup roll and the applicator roll or between the applicator roll and the metering roll. The method for controlling the film thickness of the roll coater type coating apparatus according to (1) above, wherein the film thickness is controlled by inducing an increase / decrease amount by pressing.

(3) Index during continuous coating (μU _m L /
E) and the film thickness measurement value from the on-line coating film thickness gauge, and the pushing amount between the pick-up roll and the applicator roll or between the applicator roll and the metering roll are imported into the control computer, and the correction parameters in the model formula are set. The film thickness control method for a roll coater type coating apparatus as described in (1) or (2) above, which has a learning function in which the corrected correction parameters are corrected and stored in a memory of a computer in correspondence with operation condition data.

According to the present invention, when controlling based on the above model formula, the hardness (elastic coefficient) is reduced and the volume is increased (increase in rubber thickness) and the coating material is reduced by the swelling effect during the coating of the rubber on the applicator roll. The change in viscosity can be collectively captured in the parameters, and feedforward control can be performed.

Further, since the actual physical properties (rheological properties) of the coating material largely change depending on the dilution rate of the coating material, the temperature, and the coating speed (shear rate during flowing), the correction parameters determined by the operating conditions and the coating material type are used. If it is introduced in the model formula, it becomes possible to control the coating thickness with higher accuracy. Therefore,
Rather than evaluating the paint properties using only μ in the model formula index (μU _m L / E), the coating film thickness corresponding to each operating condition is constantly calculated online during operation (before drying and after furnace drying). It is possible to constantly correct the parameter under each condition by measuring at both ends of the side, and to use it as the correction parameter for the next similar condition to enable highly accurate initial setting.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The details of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a configuration of a roll coater type coating apparatus applied to the present invention. This device is a pickup roll 2 for pulling up the paint P in the paint pan 1.
And an applicator roll 3 that receives the paint that adheres to the peripheral surface of the pickup roll 2 and is pulled up, and transfers a part of it to the steel plate S, and the steel plate S when the paint is transferred by the applicator roll 3. Is composed of a backup roll 4 that presses against the applicator roll 3.

The pickup roll 2 is made of, for example, a steel roll having a diameter of 250 mm and rotates at a peripheral speed U _p . Moreover, the applicator roll 3 has, for example, a diameter of 20.
The surface of a 0 mm steel roll is provided with a rubber lining having a thickness L and an elastic coefficient E, and is rotating in the forward direction at a peripheral speed U _a with respect to the pickup roll 2. In contrast,
The backup roll 4 is made of, for example, a steel roll having a diameter of 750 mm, and is configured to rotate together with the steel plate S at a peripheral speed U _b in the opposite direction to the applicator roll 3.

In the roll coater type coating apparatus having the above-mentioned structure, the coating film thickness of the paint transferred from the applicator roll 3 to the steel plate S on the backup roll 4 is such that the thickness between the applicator roll 3 and the steel plate S is Rotate in the opposite direction
Since they are in contact with each other, the influence of the pressing amount between the two is relatively small, and therefore the transfer rate γ can be treated as constant. Therefore, the flow rate is controlled between the pickup roll 2 and the applicator roll 3, and for the film thickness δ _ap existing on the applicator roll 3, the coating film of the paint transferred to the steel plate S on the backup roll 4 Thickness (converted to dry state) δ _f is

Δ _f = (γ / β) (U _a / U _b ) δ _ap (1) Equation where β: volume ratio of non-volatile components in the coating material

It is obtained by Therefore, setting the coating thickness
The control is performed by _obtaining δ _ap in the equation (1).

The value of δ _ap is derived from the index (μU _m L / E), the pressing amount h between the pickup roll 2 and the applicator roll 3 and the peripheral speed ratio. here,

E _s = (μU _m L / E) However, if U _m = (U _p + U _a ) /2.0 U = (U _p ^1.5 + U _a ^1.5 ) / U _a ^0.5

Δ _ap = exp [ε · logE _s + λ] / U Equation (2) where ε = 0.541h + 3.454 λ = 3.224h + 23.117

Therefore, it becomes possible to derive the coating film thickness from the operating conditions based on the relationship of the above equations (1) and (2).

FIG. 2 is an explanatory view showing another structure of the roll coater type coating apparatus applied to the present invention. This roll coater type coating device is an application that picks up a paint P in a paint pan 1 and a paint that adheres to the peripheral surface of the pick-up roll 2 and is pulled up, and transfers a part of it to a steel plate S. The metering roll 5, which is connected to the applicator roll 3 and has the purpose of adjusting the coating thickness by the pushing amount, and the steel plate S when the coating material is transferred from the applicator roll 3. It comprises a backup roll 4 which is pressed against the troll 3.

The pickup roll 2 has a diameter of 250.
In mm steel roll is rotating at a peripheral speed U _p, the applicator roll 3 has a thickness L on the surface of the steel roll having a diameter of 200 mm, and a rubber modulus of elasticity E is lined, the pick-up roll 2 On the contrary, the peripheral speed U _{a in the} opposite direction
Spinning at. Metering roll 5 has a diameter of 100 m
Similar to the backup roll 4 which rotates at a peripheral speed U _b together with the steel plate S, it is a steel roll of m and is adapted to rotate at a peripheral speed U _c in the opposite direction to the applicator roll 3.

In the roll coater type coating device having the above structure, the coating film thickness transferred from the applicator roll 3 to the steel plate S on the backup roll 4 can be derived from the equation (1). Therefore, the setting and control of the coating film thickness can be done by δ in equation (1).
done by getting _ap . The value of δ _ap is the index (μU
_m L / E) (where U _m corresponds to U _a ), the pushing amount h between the applicator roll 3 and the metering roll 5 and the peripheral speed are derived as in the following formula (3),

Δ _ap = exp [ε logE _s + λ] / U _a Formula (3) where ε = 6.908h + 21.644 λ = 0.916h + 3.316

Based on the relationships of the above equations (1) and (3),
It is possible to derive the coating thickness from the operating conditions.

Further, from the relationship of the above equations (1) and (2) or the equations (1) and (3), the film thickness variation Δt with respect to the change of the pushing amount can be derived by the following equation (4).

Δt = f (E _s , U, δ _f ) Equation (4)

Using the above formula (4), the pushing amount between the rolls is adjusted so as to maintain a uniform coating film thickness in accordance with the time-dependent change of E _s during operation (time-dependent change of lining rubber and paint viscosity). can do.

Further, in the relation of the equation (1), by introducing a correction parameter in order to introduce the characteristics of the coating material (dilution ratio, pigment type, rheological characteristics), the accuracy of the film thickness setting at the initial setting can be improved. I tried to improve. Correction parameter α
Is the model equation (1),

Δ _f = α (γ / β) (U _a / U _b ) δ _ap

Introduced in the form of, the film thickness at each coating start is measured by the routine shown in FIG. 3, and the correction parameter α is determined by comparing this with the set film thickness. A database corresponding to line speed, peripheral speed ratio, temperature, etc.) can be built in the control computer and used to set operating conditions.

[0036]

【Example】

Example 1 Application of paint to a steel plate having a plate width of 1200 mm and a plate thickness of 0.8 mm, using three kinds of paints having viscosities of 0.2, 0.3 and 0.4 Pa · s and changing the line speed. The initial conditions in step 1 were set using the above equations (1) and (2). FIG. 4 shows the results. As a result, even if the line speed changes, the error of the initially set film thickness is within 10%, which shows that the film thickness can be set with high accuracy.

Example 2 For a steel plate having a plate width of 1200 mm and a plate thickness of 0.8 mm, three kinds of paints having viscosities of 0.2, 0.3 and 0.4 Pa · s were used, and the line speed was changed, The initial conditions for applying the paint were set using the above equations (1) and (3). The result is shown in FIG. As a result, even if the line speed was changed, the error of the initially set film thickness was within 10%, and the film thickness could be set with high accuracy.

Embodiment 3 With the structure shown in FIG. 1, the pickup roll 2 has a diameter of 250.
mm, the rubber-lined applicator roll 3 had a diameter of 100 mm, and the backup roll 4 had a diameter of 750 mm. A roll coater type coating device was used to control the film thickness during continuous coating. As a result, changes in paint viscosity rubber elastic modulus and rubber thickness are shown in FIG. Further, FIG. 7 shows a comparison with the case where the change in the indentation amount and the change in the coating film thickness in the presence of the change shown in FIG. From these results, it can be seen that the practice of the present invention can suppress the fluctuation of the film thickness due to the change of the paint viscosity and the change of the properties of the rubber to an extremely small amount.

Example 4 The correction parameters are corrected by the routine shown in FIG.
FIG. 8 shows the result of comparison of the film thickness accuracy between the case of coating with a coating material containing fine particles having a characteristic peculiar to the rheological characteristics and the case of coating with a conventional method without correction parameters. In the conventional method, it was not possible to effectively reflect the part of the paint rheological properties that affects the film thickness, which depends on temperature, shear rate, dilution rate, particle content, etc., but under the similar operating conditions by the practice of the present invention. It was possible to improve the setting accuracy by using the model that included the correction parameters.

[0040]

EFFECT OF THE INVENTION By controlling the initial film thickness setting and the film thickness during continuous operation when applying the coating material to the strip-shaped material by the roll coater type coating device based on the model formula of the present invention,
The required film thickness can be obtained easily and with high accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an outline of a roll coater type coating apparatus for carrying out a film thickness control method of the present invention.

FIG. 2 is an explanatory view schematically showing another roll coater type coating apparatus for carrying out the film thickness control method of the present invention.

FIG. 3 is a block diagram showing a film thickness management routine applied to the implementation of claim 3;

FIG. 4 is a graph showing the results of examining the accuracy of the initially set film thickness according to Example 1.

FIG. 5 is a graph showing the results of examining the accuracy of the initially set film thickness according to Example 2.

FIG. 6 is a graph showing changes in paint viscosity, rubber elastic modulus, and rubber thickness when film thickness control is performed during continuous coating according to Example 3.

FIG. 7 is a graph showing a change in the amount of indentation and a change in coating film thickness in the presence of fluctuations in Example 3 in comparison with the case of being controlled by a conventional olepa.

FIG. 8 is a graph showing the results of examining the accuracy of the initially set film thickness according to Example 4.

[Explanation of symbols]

1 Paint Pan 2 Pickup Roll 3 Applicator Roll 4 Backup Roll 5 Metering Roll S Steel Plate P Paint δ _f Coating Thickness

Claims (3)

[Claims] 1. A roll coater type coating device comprising a pick-up roll, an applicator roll whose surface is made of an elastic material, and a backup roll supporting a strip-shaped material, or an applicator roll whose pick-up roll and surface are made of an elastic material. In a film thickness control method of a roll coater type coating apparatus including a backup roll supporting a belt-shaped material and a metering roll connected to the applicator roll, the paint viscosity μ, the average of the pickup roll and the applicator roll Peripheral speed U _m , index (μU _m L / E) that combines elastic material thickness L on the applicator roll and elastic coefficient E, pushing amount between pickup roll and applicator roll, and applicator roll and backup A model formula for deriving the coating thickness of the strip material from the peripheral speed ratio of the roll Zui, the film thickness control method for a roll coater type coating apparatus characterized by controlling the film thickness to be coated. 2. The viscosity of the coating material and the elastic modulus E and thickness L of the elastic material on the applicator roll are measured during continuous coating, and between the pickup roll and the applicator roll or between the applicator roll and the metering roll. The method for controlling the film thickness of a roll coater type coating apparatus according to claim 1, wherein the film thickness is controlled by inducing an increase / decrease amount of indentation. 3. An index (μU _m L / E) during continuous coating, a film thickness measurement value from an online coating film thickness gauge, and indentation between a pickup roll and an applicator roll or between an applicator roll and a metering roll. Import the amount into the control computer, modify the correction parameters in the model formula,
3. A film thickness control method for a roll coater type coating apparatus according to claim 1 or 2, further comprising a learning function in which the corrected correction parameters are associated with operation condition data in a memory of a computer.