JPH0357839B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for controlling the coating thickness of a metal strip, and in particular, it is suitable for use when uniformly controlling the coating thickness of a metal strip on-line. The present invention relates to an improvement in a method for controlling the coating film thickness of a strip, in which the excess is removed using a squeeze roll to adjust the film thickness to a set thickness.

[Conventional technology]

Generally, electromagnetic steel sheets used in electric motors, transformers, etc. are coated with an insulating coating, but the thickness of the coating must be controlled within a certain target range according to customer requirements. In other words, if the film thickness is too thick, the electromagnetic properties may deteriorate due to a decrease in the space factor, or
Welding efficiency decreases due to blowholes occurring during welding after lamination, or costs increase due to large consumption of coating chemicals.
If the film thickness is too thin, problems such as poor insulation and poor punching properties may occur. In addition, it is necessary to control the film thickness uniformly not only in the longitudinal direction of the strip but also in the width direction.
In a conventional squeeze roll type coating device, as shown in FIG. 4, for example, the upper and lower squeeze rolls 14A, 14B are rolled down using chock at both ends of the rolls as shown by arrow C. There was a film thickness distribution in the strip width direction. That is, the end of the roll shaft becomes a kiss roll D, and the gap becomes larger at the center portion δ, and the film thickness at the center portion becomes thicker. As a method to make the film thickness distribution uniform in the width direction,
A roll coater method has already been proposed, but it is rarely adopted because the equipment cost is higher than the squeeze roll method and the width cannot be returned from a narrow width to a wide width. Therefore, the applicant has already proposed a method of attaching a crown to a squeeze roll iron core in U.S. Pat. No. 59-143921.

[Problems to be solved by the invention]

However, the method of attaching a crown to a squeeze roll core has a problem in that it cannot completely respond to changes in coating conditions. That is, in order to keep the deflection of the squeeze roll constant, the rolling force cannot be changed significantly, and therefore, when changing the coating film thickness, the concentration of the coating liquid must be adjusted. However, in order to change the rolling force by adjusting the concentration of the coating solution, it is necessary to make the specific gravity of the coating solution smaller than necessary, which increases the loss of heat of evaporation of water and increases the energy consumption. There is the problem of inviting. On the other hand, a method of using a squeeze roll iron core as a variable crown roll is also conceivable, but there are problems in that the equipment is complicated, the equipment cost is high, and it takes time and effort to replace the rolls.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method for controlling the coating film thickness of a strip, which can easily control the coating film thickness in the width direction of the strip at low equipment costs. purpose.

[Means to solve the problem]

The present invention provides a method for controlling the coating film thickness of a strip, in which an excess coating liquid is deposited on the surface of a running strip, and then the excess is removed by at least a pair of squeeze rolls to adjust the coating thickness to a set thickness. The above object is achieved by tilting the axis of the squeeze roll in the strip conveying direction in accordance with the deflection of the squeeze roll, thereby controlling the coating film thickness in the width direction of the strip. Further, in an embodiment of the present invention, the squeeze roll whose axis is tilted is a squeeze roll on the upper side of the strip.

[Effect]

In the present invention, after depositing an excess amount of coating liquid on the surface of a running strip, when removing the excess with a squeeze roll and adjusting the film thickness to a set thickness, the axial center of the strip is adjusted according to the deflection of the squeeze roll. is tilted in the direction of strip conveyance.
When the axis of the squeeze roll is tilted in the strip conveying direction by, for example, θ, as shown in Fig. 2, the center E has a lower rolling force (contact pressure) than the shaft end.
becomes larger and the film thickness at the center becomes smaller. Therefore, as shown in FIG. 4, when the inclination θ is 0, the excessive film thickness at the center of the strip due to the deflection of the squeeze roll is canceled out, so that by balancing the deflection of the squeeze roll and the inclination θ, The film thickness in the width direction can be easily controlled with low equipment costs. Also, by using the squeeze roll that tilts the axis as the squeeze roll on the upper side of the strip,
It is possible to prevent the strip from meandering in the catenary furnace when the coating film is continuously dried and baked while the strip whose surface is coated with the coating liquid is run in the catenary furnace.

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a metal strip coating equipment employing the strip coating thickness control method according to the present invention will be described in detail below with reference to the drawings. In this embodiment, as shown in FIG. 1, an excess coating liquid is applied to a running strip 10 using sprayers 12 placed above and below it.
Excess coating liquid adhering to the front and back surfaces of the strip 10 is removed by a pair of horizontal squeeze rolls consisting of an upper squeeze roll 14A and a lower squeeze roll 14B, and the strip 10 is further supported by rollers in the furnace. Rather, the present invention is applied to coating equipment for strips 10 which are dried and baked in a catenary-type baking furnace 16 in which the center portion in the conveying direction hangs down in a catenary shape due to the action of gravity. be. Both ends of the lower squeeze roll 14B are rotatably supported by a pair of lower squeeze roll yoke 18A, 18B. The lower squeeze roll chock 18A, 18B has a lower squeeze roll adjusting motor 20A, 20B for adjusting the lower squeeze roll 14B, and detects the lower squeeze force applied to the lower squeeze roll chock 18A, 18B. Load detector 2 such as a load cell for
2A and 22B are arranged. Both ends of the upper squeeze roll 14A are rotatably supported by a pair of upper squeeze roll jocks 24A and 24B. The left and right chock positions of the upper squeeze roll chock 24A, 24B can be changed by a pair of chock positioning motors 26A, 26B. On the exit side of the baking furnace 16, film thickness detectors 28A, 28B, and 28C are arranged to detect the coating film thickness at the center in the width direction and near both ends of the strip surface. These film thickness detectors 28A to 28C are
Both have a known configuration, and the film thickness detector 2
8A detects the film thickness at the right end in the strip traveling direction, film thickness detector 28B detects the film thickness at the center of the strip, and film thickness detector 28C detects the film thickness at the left end in the strip traveling direction. It is designed to detect the thickness. Note that the film thickness detectors 28A to 28C may be individual fixed types as in the example of this embodiment, or one film thickness detector disposed on the surface of the strip 10 may be used. The measurement may be performed while moving in the width direction. A control device 30 for controlling the squeeze rolls 14A, 14B according to the outputs of the film thickness detectors 28A to 28C includes
and 28C, a difference calculation circuit 30B that calculates the difference in the central film thickness between the output of the average value calculation circuit 30A and the output of the film thickness detector 28B, and the difference calculation circuit 30B. A chock position calculation circuit 30C calculates the left and right chock positions of the upper squeeze roll 14A so that the film thickness at the center and end portions is uniform according to the output of the circuit 30B; 24A, 24B for left and right upper squeeze rolls
In order to set each to a predetermined horizontal position,
A chock position command circuit 3 that outputs commands to the chock positioning motors 26A and 26B, respectively.
It mainly contains 0D and 30E. Although not shown, the load detectors 22A, 22B and the rolling force adjustment motors 20A, 20B are used so that the average value of the total film thickness detected by the film thickness detectors 28A to 28C is constant. Of course, the overall film thickness was also adjusted. The operation of the embodiment will be explained below. First, in order to keep the average value of all the film thicknesses detected by the film thickness detectors 28A to 28C constant, the overall The film thickness has been adjusted. In this embodiment, the widthwise film thickness is further controlled by the chock positioning motors 26A, 26 in accordance with the difference between the center film thickness and the average film thickness at the end parts.
B moves the axis of the upper squeeze roll 14A in the horizontal direction, which is the strip conveying direction, by θ (see Fig. 2).
This is done by tilting only. The reason why the upper squeeze roll 14A is moved here is because if the lower squeeze roll 14B is moved, the strip 10 tends to meander because it has a catenary in the baking oven 16 after the squeeze roll. be. In this way, not only the overall film thickness but also the film thickness distribution in the width direction can be adjusted to be uniform. Results of uniform control of the edge film thickness and center film thickness using a comparative example of a squeeze roll (coating roll) using a crowned iron core roll proposed by the applicant in Utility Model Application No. 59-143921, and this example The results of the control are shown in FIG. 2 for comparison. The broken line A in Fig. 2 is the control result using the crowned iron core roll.
Solid line B is the control result according to this embodiment. As is clear from the figure, the squeeze roll using the crowned iron core roll cannot cope with large changes in the rolling force of the coating roll, but this example can sufficiently cope with it. In the above embodiments, the coating film thickness in the strip width direction was controlled to be uniform, but the method of application of the present invention is not limited to this. For example, when it is desired to make a difference in film thickness in the strip width direction, It is clear that the same applies to Further, in the above embodiments, the present invention is applied to control the coating thickness of a metal strip that is baked and dried after painting, but the present invention is not limited to this.

【Effect of the invention】

As explained above, according to the present invention, the film thickness in the strip width direction can be easily controlled at low equipment costs and without depending on changes in rolling force. Therefore, it has an excellent effect in that it is easy to make the film thickness uniform in the width direction of the strip.

[Brief explanation of drawings]

FIG. 1 is a perspective view, including a partial block diagram, showing the configuration of an embodiment of a metal strip coating equipment in which the strip coating thickness control method according to the present invention is adopted, and FIG. A plan view of the squeeze roll viewed from above, 3rd to explain the function of the invention.
The figure is a diagram comparing and showing the control results of the above-mentioned embodiment and the comparative example proposed in Utility Model Application No. 59-143921. Figure 4 is for explaining the problems of the conventional example using a simple squeeze roll. FIG. 10...Strip, 12...Spray, 14
A...Upper squeeze roll, 14B...Lower squeeze roll, 24A, 24B...Chick for upper squeeze roll, 26A, 26B...Chock positioning motor, 28A, 28B, 28C...Film thickness detector, 30... Control device.

Claims (1)

[Scope of Claims] 1. The coating film thickness of the strip, which is adjusted to a set film thickness by depositing an excess coating liquid on the surface of the running strip and then removing the excess with at least a pair of squeeze rolls. A method for controlling the coating film thickness of a strip, characterized in that the coating film thickness in the width direction of the strip is controlled by tilting the axis of the squeeze roll in the strip conveying direction in accordance with the deflection of the squeeze roll. 2. The method for controlling the coating film thickness of a strip according to claim 1, wherein the squeeze roll that tilts the axis is a squeeze roll on the upper side of the strip.