JPH09150107A - Roll coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent the occurrence of stripe patterns on the surface of a material to be coated. SOLUTION: Two rolls, a pickup roll 1 and an applicator roll 2, are intervened between a paint pan 3 filled with a coating material and a steel sheet 5. The pickup roll 1 and the applicator roll 2 are rotated in a direction where a reverse coating system is attained. The circumferential speed VP of the pickup roll 1, the circumferenctial speed VA of the applicator roll 2 and the line speed LS of the steel sheet 5 are respectively detected. A controller 13 outputs command signals I1 , I2 to the respective driving devices 1A, 2A of the pickup roll 1 and the applicator roll 2 in such a manner that the ratio of VA/VP of the circumferential speed attains a prescribed rate or above and that the circumferential speed VA is increased on decreased is accordance with the increase or decrease of the line speed 1S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll coating method suitable for producing coated steel sheets,
In particular, it is intended to surely suppress the generation of streak patterns and obtain a beautiful painted surface.

[0002]

2. Description of the Related Art Conventional roll coating methods include, for example, those shown in FIGS. 3 (a) to 3 (d). That is, FIGS. 3 (a) and 3 (b) are views showing an example of a coating method called "natural coating", in which the pickup roll 1 and the applicator roll 2 are in the same direction at their opposing positions as indicated by arrows. The applicator roll 2 and the steel plate 5 also move in the same direction at their facing positions, as indicated by the arrow. Then, the paint in the paint pan 3 is scooped up by the pickup roll 1, the paint on the circumference of the pickup roll 1 moves to the applicator roll 2, and the paint on the circumference of the applicator roll 2 is applied to the surface of the steel plate 5. It is supposed to be done. Note that FIG.
3A is a type having the backup roll 4, whereas FIG. 3B is a type in which the backup roll 4 is omitted, but both are essentially the same.

On the other hand, FIGS. 3 (c) and 3 (d) are views showing an example of a coating method called "reverse coating", in which the applicator roll 2 and the steel plate 5 are at opposite positions as indicated by arrows. It is characterized in that it moves in different directions. It should be noted that, while FIG. 3C is a type having a backup roll 4, FIG.
(D) is a type in which the backup roll 4 is omitted, but both are essentially the same.

[0004]

Here, in the above-mentioned natural coating method, the paint adhered to the applicator roll 2 and the steel plate 5 is not torn at the nip outlet between the applicator roll 2 and the steel plate 5. Therefore, the coating film thickness on the steel plate 5 becomes non-uniform in the width direction, and a streak pattern (usually also called roll stitch, striation or roping) is likely to occur. . Since such streak patterns are generated substantially parallel to the traveling direction of the steel sheet 5 and at substantially equal intervals, the appearance of the surface of the steel sheet 5 is impaired, which is a fatal defect in a coated steel sheet that requires particularly good finish. Will be.

On the other hand, in the reverse coating method, unlike the natural coating method, the applicator roll 2 and the steel plate 5 flow in opposite directions, so that the above-mentioned tearing phenomenon does not occur. However, even with this reverse coating method, since natural rotation occurs between the pickup roll 1 and the applicator roll 2 in order to appropriately control the coating film thickness, a tearing phenomenon similar to the above occurs at this portion and the applicator roll 2 The thickness of the coating film on the roll 2 becomes non-uniform in the width direction and is transferred to the steel plate 5, so a streak pattern is generated on the surface of the steel plate 5, although it is slight. Therefore, it becomes a problem when particularly good finish is required.

After all, the above problems arise as a result of a small relative speed ratio between the delivery side and the reception side when the paint moves, so if simply considered, in the reverse coating method, It seems that this can be solved by sufficiently increasing the ratio V _A / V _P of the peripheral speed V _P of the pickup roll 1 and the peripheral speed V _A of the applicator roll 2. However, according to the experiments by the present inventors, even if the ratio V _A / V _P is simply increased, the streak pattern cannot be completely eliminated.

There is also a conventional method for reducing the streak pattern by setting the number of rolls interposed between the paint pan 3 and the steel plate 5 to 3 or 4 (for example, Japanese Patent Laid-Open No. 63-63).
-4869 and Japanese Patent Laid-Open No. 63-143962), since there is also a portion that naturally rotates,
It is very difficult to eliminate the streak pattern, and as a result of the increase in the number of rolls, there is another problem that maintenance is deteriorated and cost is increased.

The present invention has been made by paying attention to the unsolved problems of the conventional technique, and requires only two rolls to be interposed between the paint pan and the object to be coated, and It is an object of the present invention to provide a roll coating method in which a streak pattern does not occur on the surface of an object to be coated.

[0009]

In order to achieve the above object, the present invention has two rolls, a pickup roll and an applicator roll, interposed between a paint pan and an object to be coated, and The coating material is picked up by the pickup roll, the coating material on the pickup roll surface is transferred to the applicator roll surface, and in the roll coating method of applying the coating material on the applicator roll surface to the object surface, the applicator roll and the While rotating the applicator roll so that they both move in opposite directions at the facing position of the object to be coated, both of them move in the same direction at the facing position of the applicator roll and the pickup roll. By rotating the pickup roll, the line speed LS of the object to be coated, A circumferential speed V _A of the replicator roll, a circumferential speed V _P of the pick-up roll to recognize each
The line speed L _A is set so that the ratio V _A / V _{P of the} peripheral speeds V _A and V _P is equal to or higher than a predetermined ratio α and the peripheral speed V _A increases or decreases according to the increase or decrease in the line speed LS.
At least one of S, the peripheral speed V _A , and the peripheral speed V _P is controlled.

According to the observation of the present inventors, the shape of the meniscus at the nip outlet of the naturally rotating portion at the time of roll coating is as follows:
Flatness → waviness generation → irregular protrusion generation → concavity and convexity at regular intervals → the pitch and height of the concavity and convexity decrease and the streak pattern disappears. Therefore, the line speed LS and circumferential speed V _A, the V _P by adjusting as above or a state is obtained,
It can be seen that the generation of streak patterns can be avoided.

Therefore, when coating the steel sheet by the reverse coating method, the present inventors have compared the peripheral speed V _P of the pick-up roll and the applicator roll with respect to the pick-up roll and the applicator roll that rotate naturally. Peripheral speed V _A ratio V _A / V
_{When P} was made sufficiently large and other conditions were changed appropriately, experiments were conducted, and it was confirmed that the streak pattern disappeared completely and that it did not disappear.

[0012] When I examined this in detail,
It was a necessary condition to make the ratio V _A / V _P sufficiently large, but this is not enough, and if the peripheral speed V _A of the applicator roll is increased as the line speed LS of the steel plate is increased, a streak pattern will appear. The conclusion is that the occurrence of can be avoided. That is, as in the present invention, the line speed L of the object to be coated is
S, the peripheral speed V _A of the applicator roll, and the peripheral speed V _P of the pickup roll are respectively recognized, and the peripheral speed V
As the ratio V _A / V _P of _A and V _P is the circumferential speed V _A is increased or decreased depending on the increase or decrease of and the line speed LS be more than a predetermined ratio alpha, their line speed LS, circumferential speed V _A, By controlling at least one of the peripheral speeds V _P , it is possible to avoid the generation of streak patterns on the surface of the object to be coated.

The ratio α, the proportional coefficient between the line speed LS and the peripheral speed V _A , etc. are values individually set for each roll coating apparatus and are experimentally obtained before actual operation. It is a number to set.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which the roll coating method according to the present invention is applied to a coated steel sheet production line in the steel industry. First, the structure will be described. Between a paint pan 3 filled with paint and a steel plate 5 as an object to be coated, two rolls, a pickup roll 1 and an applicator roll 2, which can be independently driven to rotate, are provided. Intervenes. The backup roll 4 is in contact with the surface of the steel plate 5 opposite to the surface facing the applicator roll 2.

Of these, the rotation directions of the applicator roll 2 and the backup roll 4 are set so that the applicator roll 2 and the steel plate 5 move in opposite directions at the opposing positions, as indicated by arrows. That is, in this embodiment, reverse coating is performed. On the other hand, the rotation direction of the pickup roll 1 is set so that the pickup roll 1 and the applicator roll 2 move in the same direction at the facing position, as indicated by the arrow.

Further, by detecting the respective rotation speeds of the pickup roll 1 and the applicator roll 2 and considering the diameters of the rolls 1 and 2, the peripheral speed V _{P of} the pickup roll 1 and the applicator roll 2 are detected. There are provided peripheral speed detecting devices 10 and 11 for detecting the peripheral speed V _A. Further, by detecting the rotation speed of the backup roll 4 and considering the diameter of the backup roll 4, the peripheral speed of the backup roll 4,
That is, the line speed detection device 12 that detects the line speed LS that is the traveling speed of the steel plate 5 is provided.

The peripheral speeds V _P and V _A detected by the peripheral speed detecting devices 10 and 11 and the line speed LS detected by the line speed detecting device 12 include a microcomputer (not shown), necessary interface circuits and the like. It is supplied to the controller 13 constituted by. The controller 13 monitors the supplied peripheral velocities V _P and V _A and the line velocity LS, and at the same time, satisfies the condition that the steel plate 5 does not have a streak pattern, and the drive device 1A and the applicator of the pickup roll 1. The peripheral speed adjusting signals I ₁ and I ₂ are output to the driving device 2A of the roll 2, respectively.

Here, the controller 13 of the present embodiment
Outputs the peripheral speed adjustment signals I ₁ and I ₂ to the driving device 1A and the driving device 2A so as to satisfy the following condition: V _A = a + b × LS (1) V _P = c (2) It is supposed to do. However, in the above formulas (1) and (2), a,
b and c are constants.

That is, the controller 13 of the present embodiment
Is the peripheral speed V of the pickup roll 1. _PTo a constant peripheral speed c
The peripheral speed V of the applicator roll 2_ARye
Control to increase / decrease based on the control speed LS
It is supposed to. Next, the operation and effect of this embodiment
Will be explained. That is, each roll 1, 2, 4 is in a rotationally driven state.
If so, the paint in the paint pan 3 must first be picked up.
Picked up by Prowl 1 and picked up
Paired with the applicator roll 2 while being attached to the peripheral surface of 1.
The applicator roll 2 at the opposite position.
To the side, and then to the applicator roll 2 circumference
Head to the facing position of the steel plate 5 in the adhered state, and the facing position
Then, it adheres to the surface of the steel plate 5 and is coated there.

On the other hand, the controller 13 controls each sensor 10
Based on the peripheral velocities V _P and V _A and the line velocity LS supplied from ˜12, the command signals I ₁ and I ₂ are given to the drive devices 1A and 2A so that the above expressions (1) and (2) are satisfied. Is output. Specifically, the controller 13 controls the peripheral speed V _P
So that the detected peripheral speed V _P is slower than the constant peripheral speed c so that the detected peripheral speed V _P becomes equal to the constant peripheral speed c, the command signal I ₁ in the acceleration direction is output and the detected peripheral speed V _P becomes When the peripheral speed c is higher than the constant peripheral speed c, feedback control is performed to output the command signal I ₂ in the deceleration direction, while the detected line speed LS is substituted into the above equation (1) to obtain the target peripheral speed V _A. The same feedback control as for the peripheral speed V _P is executed so that the actual peripheral speed V _A calculated and detected matches the target peripheral speed V _A.

Here, the present inventors have the same configuration as that of the present embodiment, and appropriately change the line speed LS and the peripheral speed V _A while keeping the peripheral speed V _P of the pickup roll 1 constant. When the presence or absence of streak patterns on the surface of the steel plate 5 was examined, the results shown in FIG. 2 (a) were obtained with the water-based paint, and the results shown in FIG. 2 (b) were obtained with the solvent-based paint. That is, considering this, the ratio V _A of the peripheral speeds between the pickup roll 1 and the applicator roll 2 which rotate in the same direction is _VA.
/ V _P is made sufficiently large (V _A / V _P is 2 or more in both examples of FIGS. 2A and 2B), and the peripheral speed V _A of the applicator roll 2 is proportional to the line speed LS. It can be seen that the streak pattern does not occur on the surface of the steel plate 5 by increasing the number of lines.

That is, the peripheral speed ratio V _A / V _P is set to a predetermined ratio α.
(Α = 2 in the experimental examples of FIGS. 2A and 2B) or more, and the peripheral speed V _A may be increased or decreased according to the increase or decrease of the line speed LS. More specifically, as in this embodiment, the constants a, b, and c in the above equations (1) and (2) are calculated based on the experimental results shown in FIGS. It is determined in advance, and at the time of actual operation, the peripheral speed V _P of the pickup roll 1 and the applicator roll 2 is
_VA and the line speed LS are detected, and the command signals I ₁ and I ₂ are output according to the detection results so that the expressions (1) and (2) are satisfied, and the pickup roll 1 and the applicator roll are output. By controlling the peripheral speeds V _P and V _A of 2 even if the line speed LS changes due to other operating conditions,
It is possible to prevent the generation of streak patterns on the surface of the steel sheet 5, and it is possible to manufacture a high-quality coated steel sheet.

In the case of the configuration of this embodiment, 2
Since it is a roll system, the number of parts does not particularly increase, so that maintenance is not deteriorated and cost is significantly increased. In the above embodiment, the peripheral speed V _P of the pickup roll 1 is fixed, and control is performed such that the peripheral speed V _A of the applicator roll 2 is changed based on the line speed LS. The embodiment of the invention is not limited to this. For example, the line speed LS
Based on the circumferential speed V _A, it may be controlled such as to change both V _P.

Further, the application of the present invention is not limited to the production line of coated steel sheet, and it is naturally applicable as long as the coating is performed using the pickup roll 1 and the applicator roll 2.

[0025]

As described above, according to the present invention,
In addition to adopting the reverse coating method, the line speed LS of the object to be coated and the peripheral speed V _{A of the} applicator roll
When, a circumferential speed V _P of the pick-up roll to recognize each and the ratio V _A / V _P of the peripheral speed V _A and V _P is in accordance with and the line speed LS increases and decreases not less than a predetermined ratio α peripheral speed The line speed LS and the peripheral speed V are set so that V _A increases and decreases.
_Since at least one of _A and the peripheral speed V _P is controlled, it is possible to avoid the generation of streak patterns on the surface of the object to be coated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a graph showing the results of experiments conducted by the present inventors.

FIG. 3 is an explanatory diagram illustrating a conventional roll coating method.

[Explanation of symbols]

 1 Pick-up roll 2 Applicator roll 3 Paint pan 5 Steel plate (object to be coated) 10, 11 Peripheral speed detection device 12 Line speed detection device 13 Controller

Front page continuation (72) Ichiro Tanoguchi Ichiro Mizushima Kawasaki-dori, Kurashiki City, Okayama Prefecture (without street number) Inside the Mizushima Works, Kawasaki Steel Co., Ltd. (72) Tomoyuki Ota 1-chome, Mizushima Kawasaki Street, Kurashiki City, Okayama Prefecture (number) None) Inside Kawashima Steel Co., Ltd. Mizushima Steel Works

Claims (1)

[Claims] 1. A pick-up roll and an applicator roll are interposed between a paint pan and an object to be coated, the paint in the paint pan is scooped by the pick-up roll, and the paint on the surface of the pick-up roll is In a roll coating method of transferring to the surface of an applicator roll and applying the paint on the surface of the applicator roll to the surface of the object to be coated, both of them move in opposite directions at the position where the applicator roll and the object to be coated face each other. As described above, the applicator roll is rotated, and the pickup roll is rotated so that both of the applicator roll and the pickup roll move in the same direction at a position where the applicator roll and the pickup roll face each other. , The peripheral speed V _A of the applicator roll and the pickup speed Le peripheral speed V _P and the recognized respectively, and the peripheral speed ratio V _A / V _P of the peripheral speed V _A and V _P is in accordance with the increase or decrease of and the line speed LS be more than a predetermined ratio α As V _A increases and decreases,
_A roll coating method comprising controlling at least one of the line speed LS, the peripheral speed V _A , and the peripheral speed V _P.