Intermittent coating device

Abstract

To provide an intermittent coating device which easily and effectively suppresses, while making a base material and a die relatively travel and forming a coating film on the base material through intermittently discharging a coating material from the die, at least sagging amount at a starting end part where discharging the coating material is started.SOLUTION: An intermittent coating device comprises: a coating pump 10 which supplies a die 3 with coating material 4 sent from a tank 6; a thickness sensor 13 which detects thickness of a coated film on a base material 2 by the coating material just after being formed; and a controller 14 which controls the coating pump based on the thickness of the coating film detected by the thickness sensor. The coating pump is a pump which can compress, suck, and stop the coating material where flow rate can be continuously changed. The controller controls, when starting discharge of the coating material, the coating pump to increase discharge quantity so that the thickness detected by the thickness sensor is to be a defined thickness set in advance and then decrease the discharge quantity.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coating device configured to relatively run (or convey) a sheet- or film-like substrate such as aluminum foil and a die that dispenses a coating material such as slurry toward the substrate in the longitudinal direction of the substrate, and to intermittently dispense (i.e., coat) the coating material from the die during this running (conveying) process, thereby forming coating films at predetermined intervals on the surface of the substrate. [Background technology]

[0002] An example of this type of device is described in Patent Document 1. Briefly, the coating material is pressurized to a predetermined pressure and sent out from a tank through a pipe, which branches, with one end connected to a coating valve and the other connected to a return valve. These valves are so-called rotary valves, with a shaft-shaped valve element having a through-hole formed therethrough in the radial direction, and configured to switch between open and closed states every time the valve element rotates 90 degrees.

[0003] The coating valve is connected to a die facing the substrate, and supplies the coating material sent through the piping to the die and stops the supply. A suckback is provided between the coating valve and the die. The suckback is a device that sucks in the coating material by, for example, stroking a piston or plunger. When stopping the discharge of the coating material, it performs suction, improving the so-called cutting of the coating material and suppressing sagging, which is the gradual thinning of the film thickness.

[0004] On the other hand, the return valve is connected to the tank via a return pipe. This return valve is switched so that its open / closed state is opposite to that of the coating valve. That is, during non-coating periods when the coating valve is closed and no coating is being performed, the return valve is controlled to an open state, returning the coating material to the tank. During coating periods, the return valve is controlled to a closed state, preventing the coating material from returning to the tank and maintaining the pressure of the coating material being discharged from the die. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-063780 Summary of the Invention [Problem to be solved by the invention]

[0006] The intermittent coating described above is performed by discharging the coating material from the die while the substrate and die are moving relative to each other, such as by moving the substrate. Therefore, since the substrate continues to move relative to the die when the coating material starts to be discharged from the die and when the discharging of the coating material is stopped, a so-called transition portion occurs in which the film thickness gradually increases to a predetermined thickness as the discharging rate of the coating material gradually increases from zero. The same applies when the discharging of the coating material is stopped; as the discharging rate of the coating material decreases toward zero, a so-called transition portion occurs in which the film thickness gradually decreases from a predetermined thickness. These transition portions are called sagging, and because they do not function properly as products such as electrodes, the amount of sagging must be kept as small as possible.

[0007] In the intermittent coating device described in Patent Document 1, when the coating material starts to be discharged, the pressure (internal pressure) of the coating material is temporarily increased to increase the discharge rate, thereby increasing the amount of coating material discharged relative to the amount of substrate movement, thereby suppressing sagging. However, while the internal pressure of the coating material is determined by the pressure at which it is sent from the tank to the piping, resistance in the piping from the tank to the coating valve reduces the pressure, and this pressure cannot be accurately determined. Therefore, the amount of coating material discharged when coating begins (i.e., when the starting edge of the coating film is formed) cannot be accurately controlled. As a result, it becomes difficult to reliably suppress sagging, or, contrary to sagging, the film thickness at the starting edge may become thicker.

[0008] Furthermore, to adjust the internal pressure, a valve that adjusts the pressure by changing the opening degree can be installed on the return pipe side. However, since the discharge rate or pressure of the coating material varies depending on the pressure of the coating material from the pipe to the coating valve and the pressure set by this pressure adjustment valve, it is necessary to adjust at least these two valves to eliminate or suppress sagging. Therefore, even if sagging can be improved using a pressure adjustment valve, it may be difficult work that relies on experience and intuition. Furthermore, since the pressure needs to be adjusted depending on the viscosity and temperature of the coating material, the pressure must be adjusted for each lot, such as by readjusting the set pressure for the next coating operation, which necessarily results in poor workability during the coating operation, leaving room for improvement. The same situation applies when forming the end of the coating film. Since sagging at the end is eliminated or suppressed by adjusting the internal pressure of the coating material and the negative pressure due to suckback, this adjustment requires experience and intuition, leaving room for improvement in terms of improving the efficiency of the coating operation.

[0009] The present invention has been made in light of the above-mentioned technical problems, and aims to provide an intermittent coating device that can easily and effectively suppress the amount of sagging at least at the starting end where the coating material starts to be discharged when the substrate and the die are made to travel relative to each other and the coating material is intermittently discharged from the die to form a coating film on the substrate. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the present invention provides an intermittent coating device that relatively travels between a die that discharges a coating material and a substrate on which a coating film made of the coating material is formed, and intermittently discharges the coating material from the die to form the coating film, the intermittent coating device comprising: a coating pump that supplies the coating material sent from a tank to the die; a thickness sensor that detects the thickness of the coating film immediately after it has been formed on the substrate with the coating material; and a controller that controls the coating pump based on the thickness of the coating film detected by the thickness sensor, wherein the coating pump is configured as a pump that is capable of pressurizing, suctioning, and stopping the coating material and of continuously changing the flow rate, and the controller controls the coating pump so that, when discharge of the coating material starts, the discharge rate is increased and then decreased so that the thickness detected by the thickness sensor becomes a predetermined thickness. [Effects of the Invention]

[0011] In the present invention, the coating material discharged from the die is pressurized and suctioned, and the pressure or amount is adjusted by a coating pump. The coating pump is a pump that can continuously change the flow rate (and therefore the pressure) of the coating material, and its control is based on the thickness of the coating film immediately after coating, detected by a thickness sensor. Therefore, by automatically temporarily increasing the discharge rate or pressure at the so-called starting end of the coating film or temporarily suctioning at the so-called ending end, the film thickness or sagging can be quickly converged to a predetermined thickness or amount. In other words, the overall thickness of the coating film, including the starting and ending ends of the coating film, can be automatically controlled in real time, reducing manual work in the coating process and improving work efficiency. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram illustrating the change in the amount of sagging of a coating film (A), the flow rate of a coating material from a coating pump (B), and its pressure (C) in an embodiment of the present invention. [Figure 3]FIG. 10 is a diagram showing the change in the increase in the amount of coating material at the starting end and the change in the amount of sagging when control is performed using the device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the embodiment described below is merely an example of how the present invention can be implemented, and is not intended to limit the present invention.

[0014] Figure 1 shows a schematic diagram of the overall configuration of an embodiment of the present invention. In this example, a coating material (slurry) 4 is intermittently discharged from a die 3 onto a substrate 2, such as aluminum foil, which is wound around a rotating drum 1 and traveling, to coat a coating film 5 on the surface of the substrate 2. The coating material 4 is, for example, a fluid (viscous material) made by mixing metal powder and a solvent, and is stored in a tank 6. A feed pump 7 is connected to an outlet provided at the bottom of the tank 6. The feed pump 7 is a pump for sending the coating material 4 flowing out of the tank 6 toward the die 3, and in the example shown in Figure 1, a mono pump is used.

[0015] The mono pump is a rotary displacement pump that has a rotor 7a, which corresponds to a smoothly spirally twisted male screw, rotatably housed inside a stator 7b, which corresponds to a female screw. The stator 7b is connected to the tip of a cylindrical pump casing 7c, and the rotor 7a is connected to a motor 7e by a coupling rod 7d housed inside the pump casing 7c. An end stud 7f is provided at the tip of the stator 7b for connection to a specified pipe, and the pump casing 7c is provided with a connection port 7g that extends radially outward. This is a conventionally known pump.

[0016] The tank 6 is connected to an end stud 7f of the feed pump 7, which serves as an intake port, and a supply pipe 8 is connected to a connection port 7g, which serves as a delivery port. A filter 9 is provided in the middle of the supply pipe 8 to remove any aggregates of the coating material 4. The supply pipe 8 is then connected to a coating pump 10.

[0017] The coating pump 10 is a pump that pressurizes and supplies the coating material 4 to the die 3, and in this embodiment of the present invention is configured as a mono pump. That is, the coating pump 10 has a configuration substantially similar to that of the aforementioned feed pump 7, in which a rotor 10a corresponding to a male screw is rotatably housed inside a stator 10b corresponding to a female screw. A coupling rod 10d is housed inside a pump casing 10c, the tip of which is connected to the stator 10b, and the rotor 10a is connected to a motor 10e by this coupling rod 10d.

[0018] A servo motor is used as this motor 10e, and is configured to continuously change the rotation speed and switch the rotation direction as appropriate. An end stud 10f is provided at the tip of the stator 10b, to which the die 3 is connected via a coating pipe 11. The pump casing 10c is provided with a connection port 10g extending radially therefrom, to which the above-mentioned supply pipe 8 is connected. The pump casing 10c is further provided with another connection port 10h, to which a return pipe 12 is connected. This return pipe 12 is a pipe for returning excess coating material 4 to the tank 6, and is connected to the above-mentioned tank 6.

[0019] A thickness sensor 13 is provided on the front side in the direction in which the substrate 2 is fed by the rotating drum 1, for detecting the thickness of the coating film 5 formed on the substrate 2 and outputting a detection signal. The thickness sensor 13 is connected to a controller 14.

[0020] The controller 14 mainly has the function of controlling the motor 10e of the coating pump 10 to start and stop the discharge of the coating material 4, i.e., the function of essentially controlling coating. The controller 14 is an electronic control device mainly composed of a computer equipped with a processing element (CPU), memory elements (RAM, ROM), and various interfaces, and is configured to perform calculations according to a pre-prepared program using pre-stored data and data input from the outside, and to output the results of the calculations as control signals.

[0021] The coating film 5 has a constant length in the running direction of the substrate 2 and is formed at regular intervals. Therefore, data representing the running length of the substrate 2, such as the rotation angle of the rotating drum 1, is input to the controller 14 so that the coating material 4 is discharged based on the position or running length of the substrate 2. Furthermore, a detection signal from the thickness sensor 13 is input to the controller 14 to temporarily change the discharge amount (or pressure) of the coating material 4 at the coating start end (starting end) and the coating end end (ending end) of the coating film 5. Then, a control signal is output from the controller 14 to the motor 10e of the coating pump 10 to control the discharge, suction, and stopping of the coating material 4, as well as the discharge amount. The pre-stored data includes the amount of coating material 4 dispensed to set the coating film 5 to a predetermined thickness, the initial value (nominal value) when temporarily increasing the amount of coating material 4 dispensed at the start of the coating film 5, the initial value (nominal value) for the amount of suction when temporarily sucking in the coating material 4 at the end, and the amount of change from the nominal value each time.

[0022] The coating device according to an embodiment of the present invention is characterized in that, when performing intermittent coating, the discharge or suction amount of coating material 4 at the starting and ending ends is controlled or adjusted based on the thickness detected by thickness sensor 13. To perform this control, controller 14 calculates the amount of sagging at the starting end based on the thickness detected by thickness sensor 13. The configuration that performs this function can be referred to as a sagging amount calculation unit. The discharge amount or pressure of coating material 4 is controlled by coating pump 10 so that the amount of sagging is equal to or less than a predetermined amount. The configuration that performs this function can be referred to as pump control means.

[0023] Here, the sag amount is the length in the running direction of the substrate 2 of the portion where the thickness of the coating film 5 slopes from zero to a predetermined thickness. Therefore, the sag amount will be shorter if the discharge rate of the coating material 4 rises abruptly, and conversely, it will be longer if the discharge rate of the coating material 4 rises slowly. This sag amount is determined by detecting the thickness at the starting end of the coating film 5.

[0024] Next, an example of sag control implemented in an embodiment of the present invention will be described. In Figure 2, (A) shows the film thickness at each point in the longitudinal direction (the direction of travel of the substrate 2, the direction of transport of the coating film 5) of the coating film 5 formed by intermittent coating, (B) shows the discharge flow rate of the coating material 4 by the coating pump 10 that performed the intermittent coating (e.g., the flow rate in the coating pipe 11), and (C) shows the change in the pressure of the coating material 4 (e.g., the pressure in the coating pipe 11). In an embodiment of the present invention, the rotation speed of the motor 10e of the coating pump 10 is temporarily increased and then decreased at the start of coating, thereby temporarily increasing the discharge rate and pressure of the coating material 4 and then decreasing them. This allows the discharge rate of the coating material 4 to be increased to a predetermined amount within a short period of time while the substrate 2 is traveling (transported). In this case, the length (measured in the direction of travel of the substrate 2) of the portion where the film thickness gradually increases to the predetermined thickness is the amount of sag.

[0025] After temporarily increasing the discharge rate and pressure at the starting end, the rotation speed of the motor 10e of the coating pump 10 is controlled so that the discharge rate and pressure reach the predetermined film thickness. Then, after a predetermined length of coating has been performed, that is, at the end of the coating film 5, the coating pump 10 is temporarily rotated in reverse to generate negative pressure, which sucks in the coating material 4 and quickly stops its discharge. The coating pump 10 is then stopped. Since the substrate 2 is still moving during this process, the film thickness gradually decreases from the predetermined thickness to zero, causing sagging.

[0026] The control device of the embodiment of the present invention controls the flow rate of the coating pump 10 so that the amount of sagging is equal to or less than a predetermined amount. Specifically, it controls the motor 10e. This control is performed by controlling the rotation speed and direction of the motor 10e based on the value detected by the thickness sensor 13. Figure 3 shows how the flow rate and the amount of sagging converge when this control is performed.

[0027] When a series of intermittent coatings is started, the first coating is performed by temporarily increasing the flow rate of the coating material 4 to a predetermined flow rate (nominal value) when coating the starting edge, then immediately decreasing it to a flow rate that allows the desired film thickness to be set. At the end of the coating, the flow rate is further decreased to suck (pull back) the coating material 4 using a predetermined negative pressure. Figure 3 also shows the amount of sagging when this control is performed. Because the increase in the flow rate of the coating material 4 used for the first coating at the starting edge is a nominal value that is not based on the film thickness, the increase in flow rate is delayed, resulting in a large amount of sagging. This means that the film thickness is insufficient.

[0028] Therefore, during the second coating, the flow rate of coating material 4 applied to the starting edge is increased based on the detected thickness. By doing so, the amount of sagging is reduced somewhat during the second coating, but not to the target amount. Therefore, during the third coating, the flow rate of coating material 4 applied to the starting edge is increased again. In this manner, the amount of coating material 4 (discharge rate) applied to the starting edge is gradually increased with each coating run, and this increase is repeated until the amount of sagging is reduced to a predetermined value or less. In the example shown in Figure 3, the amount of sagging converges to a predetermined value or less during the fourth coating run, so for the fifth and subsequent coating runs, the increase in the amount of coating material 4 applied to the starting edge is set to the same amount as the increase in the fourth coating run.

[0029] As described above, in the embodiment of the present invention, the item to be adjusted for managing the amount of sagging is the discharge rate (or pressure) of the coating material 4 by the coating pump 10 (specifically, its motor 10e). Because the number of adjustment items is small, adjustments can be made easily and quickly to keep the amount of sagging below a predetermined value (standard range). Furthermore, feedback control of the coating pump 10 is performed based on the value detected by the thickness sensor 13, eliminating the need for manual work and improving the efficiency of the coating operation. Furthermore, if the amount of sagging changes during intermittent coating due to changes in the properties of the coating material 4, such as viscosity, the amount of coating material added when coating the starting edge can be automatically adjusted accordingly. In other words, the amount of sagging can be optimized without interrupting intermittent coating.

[0030] Although the above describes an embodiment of the present invention, the present invention is not limited to the configuration described in the above embodiment and may be modified as appropriate within the scope of the present invention. For example, while a mono pump was used as an example of a coating pump, the coating pump of the present invention may be any pump capable of pressurizing, suctioning, and stopping the coating material, as well as continuously changing the flow rate. Furthermore, when increasing the amount of coating material in the first coating at the starting end, the so-called nominal value is reduced to increase the amount of sag, and the amount is then gradually increased. However, in the present invention, the nominal value may be set high and then gradually decreased. Furthermore, in the present invention, the amount of coating material may be adjusted to a predetermined value or less not only at the starting end but also at the end, in the same manner as in the above embodiment. In this case, instead of increasing the amount or pressure of the coating material, the amount or pressure of the coating material is reduced, and the reduction is gradually converged to an appropriate value through feedback control. [Explanation of symbols]

[0031] 1 rotating drum 2 Base material 3 Die 4 Coating materials 5 Coating 6 Tank 7. Feed pump 7a rotor 7b Stator 7c Pump casing 7d Coupling rod 7e motor 7f end stud 7g connection port 8 Supply piping 9 Filters 10 Coating pump 10a rotor 10b Stator 10c Pump casing 10d coupling rod 10e motor 10f end stud 10g connection port 10h connection port 11 Coated piping 12 Return piping 13 Thickness sensor 14 Controller

Claims

[Claim 1] An intermittent coating device in which a die that discharges a coating material and a substrate on which a coating film is formed by the coating material are moved relative to each other, and the coating material is intermittently discharged from the die to form the coating film, a coating pump that supplies the coating material sent from a tank to the die; a thickness sensor for detecting the thickness of the coating film immediately after it is formed on the substrate with the coating material; a controller that controls the coating pump based on the thickness of the coating film detected by the thickness sensor; Equipped with the coating pump is configured by a pump that can pressurize, suck, and stop the coating material, and can continuously change the flow rate; The controller controls the coating pump so that, when the discharge of the coating material starts, the discharge rate is increased and then decreased so that the thickness detected by the thickness sensor becomes a predetermined thickness. An intermittent coating device characterized by:

Images