JPH02172562A - Apparatus and method for suppressing vibration of strip of continuous coating line - Google Patents

Abstract

PURPOSE:To form a film having no coating irregularity on the surface of a strip by mounting a means for detecting the displacement of the strip in a coating part in a non-contact state and a vibration suppressing means for suppressing the vibration of the strip in a baking zone. CONSTITUTION:A non-contact displacement meter 34 detects the displacement of a strip 10 in an up-and-down direction to input the same to a suppression control part 38. The suppression control part 38 calculates the amplitude of each vibration frequency of the strip from the inputted detected displacement by frequency analysis. At the same time, the detected displacement is differentiated twice to calculate acceleration which is, in turn, subjected to frequency analysis to calculate the acceleration of each frequency. Subsequently, it is judged whether the calculated amplitude and acceleration exceed a tolerance range. In the case exceeding the tolerance range, gas is injected by static pressure pads 44A, 44B to apply pressure to the strip lo and the vibration of the strip 10 is suppressed so as to set the amplitude and acceleration to the tolerance range. When the amplitude and acceleration are within the tolerance range, the supply of gas to the static pressure pads 44A, 44B is reduced to prevent that pressure is unnecessarily applied to the strip 10.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an apparatus and method for suppressing strip vibration in a continuous coating line, and in particular, the present invention relates to a device and method for suppressing strip vibration in a continuous coating line, and in particular, coating the surface of a thin steel plate, such as forming a color film, an insulating film, or chromate treatment, to form a film, and drying and drying the film. The present invention relates to an improved device and method for suppressing strip vibration in a continuous coating line, suitable for use in baking. [Conventional technology]

BACKGROUND ART Conventionally, in factories manufacturing strips such as thin steel sheets, the surface of the strips has been coated with a predetermined film as necessary to improve the appearance quality and characteristics. Coating of such strips is normally carried out in a continuous coating line, and a general configuration of such a continuous coating line is shown in FIG. In the continuous coating line shown in FIG. 8, the strips 10 are conveyed in the direction of arrow A in the figure and are sequentially carried into the coating chamber 12. In this coating chamber 12, first, the strip 1
Deflector roll 14A so that the surface of
, 14B change the traveling direction of the strip 10. Thereafter, a coating liquid (liquid in which film components are dissolved in a solvent as will be described in detail later) is applied to the surface of the strip 10 to form a film using the surface coater 16.
Deflector roll 14C so that the back side of
At 514D, the traveling direction of the strip 10 is changed. Thereafter, a coating liquid is applied to the back surface of the strip 10 using a back coater 18 to form a film. As described above, in the coating chamber 12, the coating liquid is applied to the front and back surfaces of the strip 10 to form a film. In this way, the strip 10 with the film formed thereon is then placed in the drying zone 20 and baking zone 2 in the drying oven 19.
2. The products are transported in the order of cooling zone 24. In the drying zone 20 and baking zone 22, a predetermined amount of heat is applied to the strip 10 to dry and bake the film, and then in the cooling zone 24, a predetermined amount of heat is removed from the strip 10 to perform a cooling treatment. The film is fixed on the strip 10 by carrying out the process and carrying it out of the furnace. In addition, in the drying zone 20, the burning zone 22, and the cooling zone 24, gas at a predetermined temperature is sprayed onto the strip 10 from the lower airflow boxes 26A, 26B, 26C1 and 28A, 28B, and 28C, respectively. The drying, baking, and cooling treatments described above are performed. In addition, at this time, the strip 10 is conveyed in a state where a predetermined tension is applied by a tension applying device (not shown). Further, in FIG. 8, reference numeral 30 indicates the outlet of the drying oven 19;
31 is an exit roll. In the continuous coating line as described above, the strip 10
In order to prevent damage to the film formed on the front and back surfaces of the strip 10, it is necessary to transport the strip 10 in a non-contact manner from the time it is coated in the coating chamber 12 to the furnace outlet 30. There is. Therefore, the dry zone 20
In order to keep the strip 10 in a non-contact state and to prevent patterns from forming on the undried film due to the gas flow, a technique is generally adopted in which the strip 10 is held in a catenary state and supported by tension. (for example, described in Japanese Patent Application Laid-Open No. 57-201562), and a dry zone in which such technology is adopted is called a catenary dry zone. In addition, in the baking zone 22 and cooling zone 24 downstream of the drying zone 20, a float method is generally adopted in which the strip is floated without contact by ejected gas (for example, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 57-1999). 201562), such a float type seizure zone is referred to as a floater type seizure zone. A horizontal floater such as the seizure zone 22 and cooling zone 24 in FIG. 8 is referred to as a horizontal floater. In the continuous coating line as described above, various techniques have been proposed or disclosed for preventing scratches or patterns from forming on the film of the strip. That is, in a continuous coating line, a technique has been proposed in which the slope of the strip in the drying zone is made downward so that the roll coater (corresponding to the back coater 18) can sufficiently contact the strip and obtain the desired coating result. (JP-A-57-201562, JP-A-57-142473, JP-A-61-274769, etc.). Furthermore, a technique has also been proposed in which the baking state of the film is controlled by controlling the catenary amount of the strip in the above-mentioned line (Japanese Patent Laid-Open No. 61-274769). Furthermore, in order to perform high-speed operation in the line, an electric heater is incorporated into the means for generating the gas flow of the horizontal floater, making it possible to control the temperature of the ejected gas, widening the temperature control range and increasing drying efficiency. Furnace (Japanese Patent Laid-Open No. 57-142473), hot air drying zone (
A method for continuous drying and baking of objects to be coated (Japanese Patent Application Laid-Open No. 177375/1983) has been proposed, which enables high-speed threading by controlling the temperature and wind speed in the drying zone 20 (corresponding to the drying zone 20) to specific values.

[Problem to be achieved by the invention]

However, in the continuous coating line, the strips are conveyed without contact from the time they are coated to the outside of the drying oven.
When the gas flow ejected from 128A to 28C fluctuates, the strip 10 may vibrate upwardly or downwardly due to the influence of the fluctuation. This vibration does not necessarily occur, but it depends on the flow rate and pressure of the gas flow and the amount of variation thereof,
This may occur depending on factors such as the length of the catenary portion of the strip and the thickness of the strip. Particularly, when the strip is passed through the strip at high speed, it is unavoidable that relatively large period upward and downward vibrations (so-called flapping) occur in the strip. If the strip vibrates as described above and the amplitude exceeds a certain level, uneven coating will occur in the coater, and due to the effects of this unevenness, the coating will not be formed uniformly on the strip, and the coating will have stripes after drying. A problem arises in that a pattern appears. In order to prevent vibrations occurring in the strip, it is possible to deal with this by reducing fluctuations in the waste flow, changing the pressure of the gas flow, or the like. However, even with these methods, there are cases where it is not possible to reduce the amplitude of the strip below a certain value, and it is not possible to reliably reduce the vibration of the strip. The present invention has been made to solve the above-mentioned conventional problems, and is a continuous coating line that can reliably reduce the vibration of the strip, eliminate uneven coating, and prevent the formation of patterns on the film on the surface of the strip. It is an object of the present invention to provide a device and method for suppressing strip vibration.

[Means to achieve the task]

The present invention provides an apparatus for suppressing strip vibration in a continuous coating line for forming a film on a strip, which includes a coater section, a catenary type drying zone, and a floater type baking zone. The above-mentioned problem is achieved by comprising a means for detecting the vibration in a non-contact manner, and a vibration suppressing means for determining strip vibration from the detected displacement and suppressing the vibration of the strip in the seizure zone based on the vibration. This is what I did. The present invention also provides a method for suppressing strip vibration in a continuous coating line, in which the coater is used when forming a film on a strip in a continuous coating line having a coater section, a catenary type drying zone, and a floater type baking zone. The above problem can also be solved by detecting the displacement of the strip at the part without contact, determining at least one of the amplitude and acceleration of the strip vibration from the detected displacement, and suppressing the vibration of the strip based on the determined amplitude or acceleration. has been achieved.

[Operation and effects of the invention]

The present invention will be explained in detail below. In a continuous coating line that has a coater, a catenary-type drying zone, and a floater-type baking zone, it is necessary to measure the displacement of the strip in a non-contact manner in order to measure the vibration of the strip while it is running and coated with coating liquid. There is. That is,
This is because the coating liquid is generally a liquid in which components forming the film are dissolved in a solvent (organic solvent, water, etc.), and remains fluid until it hardens after being applied. From the measured displacement in the vertical direction (thickness direction) of the strip
Data on the change in displacement y over time is obtained. By frequency-analyzing the data of this displacement y, the amplitude @A(ω) of each frequency ω (Hz) in the displacement y is obtained. Also, by dividing the data into two machines at time t, the acceleration of vibration d' Y /dt' can be obtained, and if this acceleration d' 111 /dt' is subjected to frequency analysis, the acceleration q 〈ω) of each frequency ω is obtained. In addition, the inventors generated vibrations on the strip, measured the vibrations of the strip, and investigated the patterns generated on the coating film at this time, and found the following: (I) Formation on the film. Patterns can be created in response to only vibrations to the strip or in response to vibrations in the coater.(n) Patterns can be created in response to vibrations in the coater when the strip is vibrated. This is because the force applied to the coater causes the coater to vibrate. Therefore, if the coater has a structure that does not easily vibrate, only the pattern corresponding to the vibration of the strip will be generated. (I) The degree of the pattern is determined by the strip (IV) Coater vibration is proportional to the amplitude of the vibration, and for example, the larger the amplitude, the more severe the pattern will be on the film. Note that this force is proportional to the acceleration of the vibration. Based on the above knowledge, the inventor believes that in order to prevent patterns and flaws from forming on the strip film, if only the strip vibration is a problem, , it is sufficient to control the amplitude of the strip vibration so that it is within the permissible range, and if strip vibration and coater vibration are a problem, it is preferable to control the amplitude and acceleration of the strip vibration so that it is within the permissible range. The present invention has been devised based on the above findings.9 According to the present invention, the vibration of the strip can be suppressed within an allowable range and reliably reduced. , it is possible to dry and bake the film on the surface of the strip without causing uneven coating or scratches, and it is possible to obtain the desired quality of the film on the strip.As mentioned above, the amplitude and acceleration of the strip vibration can be controlled. For control, it is preferable to use a static pressure pad that sprays gas onto the strip from above and below in the floater type burning zone and suppresses the vibration of the strip using the static pressure generated by the gas.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. First, a first example will be explained. In this first embodiment, in a continuous coating line as shown in FIG.
A non-contact displacement meter 34 is provided on the exit side of the strip 10 to detect the displacement of the strip 10 in a non-contact manner.
Static pressure pad 44A for generating pressure by gas at 0
, 44B, and a suppression control unit 38 that measures the change over time y in strip displacement from the output signal of the non-contact displacement meter 34, and controls the static pressure pads 44A and 44B based on this change over time y to suppress strip vibration. have. As shown in FIG. 2, the static pressure pads 44A, 44B are for ejecting gas in a rectangular shape from a pipe 46 for passing gas and a slit in the width direction of the strip 10, facing each other at a certain angle. Two slit nozzles 48 are configured to communicate with each other, and a pressure receiving surface 50 is formed between the slit nozzles 48 facing the strip 10. The static pressure pads 44A and 44B are designed to suppress vibration of the strip 10 by jetting gas from the slit nozzle 48 as shown in FIG. Further, the static pressure pads 44A and 44B are installed at appropriate positions in the burning zone 22 where the gas ejected from the pads will not cause patterns on the film of the strip 10. The rest of the structure is substantially the same as the continuous coating line shown in FIG. 8 above, so similar parts are given the same numbers and explanations thereof will be omitted. The operation of the first embodiment will be explained below. In the continuous painting line shown in FIG. 1, the non-contact displacement meter 34 detects the vertical displacement y of the strip 10, and inputs the detected displacement y to the inhibition control section 38. The inhibition control unit 38 calculates the amplitude A(ω) of each frequency ω of the strip vibration from the detected displacement y by frequency analysis, and at the same time divides the detected displacement y into two parts to calculate the acceleration (d'
y /dt'), frequency-analyze the acceleration, and find the acceleration g (ω) at each frequency ω.Next, check whether the obtained vibration @A (ω) and acceleration g (ω) exceed the allowable range. Determine whether or not. If the obtained amplitude A(ω) or acceleration g(ω) exceeds the allowable range, gas is ejected from the static pressure pads 44A and 44B to apply pressure to the strip 10, and the pressure is adjusted to remove the strip. By suppressing the vibration of 10, the amplitude or acceleration of the vibration is kept within a permissible range. On the other hand, the obtained vibration 1iiiA(ω) or acceleration 9(ω
) is within the allowable range, or when the vibration is suppressed and becomes within the allowable range, the static pressure pads 44A, 4
The gas supply to 4B is reduced so that a minimum pressure is applied to the strip 10. This prevents unnecessary pressure from being applied to the strip 10 and improves quality assurance. Note that the inhibition control unit 38 may determine whether the amplitude or acceleration is greater than or equal to the allowable range, instead of determining whether the amplitude or the acceleration is greater than or equal to the allowable range. Here, the action of suppressing the vibration of the strip 10 by the static pressure pads 44A and 44B when the amplitude A (ω) of the strip vibration exceeds the permissible range or when the acceleration g (ω) exceeds the permissible range will be explained in detail. explain. That is, in the case of suppression, gas is sent from a fan (not shown) to the static pressure pads 44A and 44B through the piping 46, thereby causing the slit nozzle 48 to flow as shown in FIG.
Gas is ejected from the strip 10. Then, the gas is trapped between the strip 10, the pressure-receiving surface 50, and the jet stream (flow of gas) 52, pressure is generated there, and this pressure generates a force that pushes the strip 1o. According to the investigation by the inventors, the distance h (nn
It has been found that there is a relationship as shown in FIG. 4 between the pushing force F of the static pressure pads 44A and 44B against the pressure pads 44A and 44B. From FIG. 4, it can be seen that the larger the pressure pn or the smaller the distance, the larger the pushing force F becomes. In addition, in FIG. 4, the pushing force F is shown as a ratio based on the pushing force when the distance is 2 On. Also, the amplitude of the strip 10 is adjusted by adjusting the upper and lower static pressure pads 44A.
, 44B are the same pressure Pn. The results of investigation are shown in FIG. In this case, the distance between the upper and lower static pressure pads 44A and 44B is 5
0 um, the width of the slit nozzle is 20 at+, the area of the pressure receiving surface is about 2 f, the thickness of the strip is 0° 51 m
The X width was 1400 u. From FIG. 5, it was found that the larger the pressure Pn is, the more effective it is to reduce the amplitude of the strip vibration, and if this pressure Pn is too large, the effect of reducing the amplitude becomes weaker. This is because if the pressure Pn is too large, the jet flow of the static pressure pad will pulsate, and the effect of amplitude reduction will be weakened. Further, in order to control the amplitude of the strip 10, the pressures Pnu and Pnd of the upper and lower static pressure pads 44A and 44B can be individually controlled to different values. FIG. 6 shows the results of an investigation into this case. In this case, the distance between the upper and lower pads 44A and 44B is 501
1. Slit nozzle width is 20u, pressure receiving area is approximately 21]
2. The dimensions of the strip 10 are thickness 0.51 and width 1400.
It was u. In addition, in FIG. 6, the static pressure P of the pressure pad
Pressure Pnu (mlAq) of the upper static pressure pad 44A using the ratio P nd / P nu of nu, Pnd as a parameter
2 shows the relationship of the amplitude of the strip 10 to . From FIG. 6, if each pressure Pnu, Pnd is controlled so that P nu) P nd, the pressures Pnu, Pn
It can be seen that a similar or greater amplitude reduction effect can be obtained at a lower pressure than when d is the same. This is because when the pressure of the lower static pressure pad 44B is lowered, the strip 1
0 approaches the static pressure pad 44B due to its own weight, and the pushing force of the static pressure pad 44B increases rapidly. Therefore, if vibrations are suppressed under the condition of pressure P nu > P nd, a sufficient vibration suppressing effect can be obtained with a low pressure, and less power is required to generate pressure, which is highly economical. Note that the vertical distance between the static pressure pads 44A and 44B is preferably narrower from the viewpoint of vibration suppression, but wider is better from the viewpoint of operation, and can be selected as appropriate. Next, a second embodiment will be explained. In this second embodiment, a roll 36 for vibration prevention is provided in place of the static pressure pads 44A and 44B of the first embodiment. In detail, the roll 36 is movable up and down in the thickness direction of the strip 10 as shown in FIG. 7, and its contact pressure is controlled by the output signal of the inhibition control section 38. . Further, the roll 36 prevents the formation of scratches on the film coated on the surface of the strip 10, so that the seizing zone 22
One is installed at a predetermined location. That is, it is best to transport the film-coated strip 10 in a non-contact state, but if it comes into contact with one or two rolls, scratches are unlikely to occur, and even if scratches occur, That's because it's mild. Further, from the standpoint of preventing scratches, the predetermined position is set after the film to be coated is completely cured. Further, the roll 36 is raised and lowered by a roll lifting section 42 in accordance with an output signal from the inhibition control section 38, and is rotationally driven by a drive device (not shown). In this second embodiment, in the same manner as in the first embodiment, it is determined whether the amplitude A(ω) and the acceleration g(ω) found in the inhibition control section 38 exceed the permissible range. If the obtained amplitude A(ω) or acceleration g(ω) exceeds the permissible range, the roll 36 is raised by the roll lifting section 42 to contact the strip 10, and the contact pressure is adjusted to remove the strip. By suppressing the vibration of 10, the amplitude or acceleration of the vibration is kept within a permissible range. On the other hand, when the obtained amplitude A(ω) or acceleration q(ω) is within the permissible range, or when the vibration is suppressed and becomes within the permissible range, the roll 36 is lowered and is brought out of contact with the strip 10. state. This makes it possible to prevent the roll 36 from unnecessarily contacting the strip 10 and causing defects, thereby improving quality assurance. Note that the other configurations and operations are the same as those in the first embodiment, and therefore their explanations will be omitted. Next, an example in which the present invention is implemented on a continuous coating line will be described with specific numerical values. In this case, the length of the continuous coating furnace is 60 m, of which the lengths of the floater type baking zone and cooling zone are 40 m, and the length of the catenary type drying zone is 20 m. In addition, rolls and static pressure pads were alternately used as vibration suppression means. When a roll is used, its installation position is 29 m from the coater in the strip traveling direction. Further, the diameter of the roll was 120 oua. In addition, when using static pressure pads, the installation positions of the static pressure pads are 22 m and 30 m from the coater in the strip traveling direction.
The distance between the upper and lower pads is set at 50 stops.
The width of the slit nozzle is 20 nn, the area of the pressure receiving surface is approximately 2 m' (on one side), and the pad pressure is set to 601IIIA Q for the upper static pressure pad and 30 mmA for the lower static pressure pad.
I named it Q. Furthermore, the strip to be coated has dimensions of
Thickness 0.51111. It was opened at @1400. The tension at the time of coating was 2.0 kg/min, and the coating was conveyed at a speed of 60 m/min. The vibration suppression effect at this time is shown in Table 1. From Table 1, it can be seen that the present invention sufficiently suppresses the vibration of the strip. In the above embodiments, static pressure pads and rolls as shown in FIG. 2, FIG. 3, and FIG. 4 are shown as vibration suppressing means, but the vibration suppressing means according to the present invention is It is not limited to the configuration as shown in the figure, but any appropriate configuration can be selected and used depending on the conditions of use.

[Brief explanation of the drawing]

FIG. 1 is a layout diagram, including a partial block diagram, showing the overall configuration of a continuous coating line according to an embodiment of the present invention. FIG. 2 is a diagram of a static pressure pad according to a first embodiment of the present invention. FIG. 3 is a perspective view of main parts showing a configuration example; FIG. 3 is a layout diagram of main parts for explaining the action of the static pressure pad; FIG. 4 is a line showing an example of the relationship between the pressure of the static pressure pad and the pushing force. Figure 5 is a diagram showing an example of the relationship between the static pressure of the static pressure pad and the amplitude reduction effect, and Figure 6 is a diagram showing an example of the relationship between the static pressure of the static pressure pad and the amplitude reduction effect. A diagram showing an example of the amplitude reduction effect on the static pressure of the pressure pad, FIG. 7 is a layout diagram of main parts showing an example of the configuration of a roll according to the second embodiment of the present invention, and FIG. 8 is a diagram showing an example of a conventional continuous coating line. FIG. 4... Cooling zone, 26A to 26C... Down wind box, 8 A to 28 C... Down wind box, 4... Non-contact displacement meter, 36... Roll, 8...
Inhibition control unit, 4A, 44B... Static pressure pad, 6... Piping, 48... Slit nozzle, 0... Pressure receiving surface, 52... Jet stream.

Claims (2)

[Claims] (1) In a continuous coating line that has a coater section, a catenary-type drying zone, and a floater-type baking zone, and for forming a film on the strip, a method for detecting the displacement of the strip in the coater section in a non-contact manner. A method for suppressing strip vibration in a continuous coating line, comprising: means for determining strip vibration from detected displacement and suppressing strip vibration in the burning zone based on the vibration. Device. (2) When forming a film on a strip in a continuous coating line having a coater section, a catenary type drying zone, and a floater type baking zone, the displacement of the strip in the coater section is detected in a non-contact manner, and the detected displacement is detected. 1. A method for suppressing strip vibration in a continuous coating line, the method comprising: determining at least one of the amplitude and acceleration of strip vibration, and suppressing the vibration of the strip based on the determined amplitude or acceleration.