Coating device

Abstract

To provide a coating device which can perform excellent coating without a trial coating.SOLUTION: A coating device comprises: a coating part including a tank which contains coating material, a die head which discharges the coating material, a supply passage which constitutes a flow channel from the tank to the die head, a volumetric change device which provides the supply passage with volumetric change, and a pressure sensor which detects pressure of internal space of the die head; and a control part which controls behavior of the coating part. The control part determines whether the coating material is discharged from the die head based on pressure change when the volumetric change device provides the supply passage with the volumetric change to start, when discharging is possible, discharging of the coating material toward an object to be coated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a coating device that applies a coating material to an object to be coated. [Background technology]

[0002] Patent Document 1 discloses a coating device that can satisfactorily discharge a coating material while suppressing the inclusion of air bubbles in the coating material discharged from a die head. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-133699 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with conventional techniques, it is not possible to sufficiently remove air bubbles, and there is a risk that the coating material containing a considerable amount of air bubbles will be discharged from the die head. If coating is performed when the coating material contains many air bubbles, uneven coating will occur, so as a countermeasure against air bubbles, a test coating is sometimes performed at the start of coating. However, test coating has the problem of using excess paint. Therefore, a technology that can perform good coating without test coating is desired. [Means for solving the problem]

[0005] (1) According to one aspect of the present disclosure, there is provided a coating device for applying a coating material to a workpiece. The coating device includes a coating unit having a tank for storing the coating material, a die head for discharging the coating material, a supply passageway forming a flow path from the tank to the die head, a volume change device for imparting a volume change to the supply passageway, and a pressure sensor for detecting pressure in the internal space of the die head, and a control unit for controlling the operation of the coating unit. The control unit is configured to determine whether the coating material can be discharged from the die head based on the change in pressure when the volume change device imparts a volume change to the supply passageway, and to start discharging the coating material onto the workpiece if discharging is possible. This coating device can determine whether or not dispensing is possible due to the influence of air bubbles in the supply passage, based on the pressure change caused by a volume change in the supply passage of the coating material, and if it is determined that dispensing is possible, it can dispense the coating material onto the object to be coated. Therefore, good coating can be performed without a test coating. (2) In the coating device, the control unit may be configured to perform a bubble removal process to remove bubbles present in the internal space of the die head when the discharge is not possible. According to this coating device, by removing air bubbles present in the internal space of the die head, it is possible to restore the device to a state in which discharging is possible. (3) In the above coating device, the coating unit may further include a head circulation passage that forms a flow path from the die head to the tank, and the control unit may be configured to be capable of performing a first process as the bubble removal process, in which the coating material contained in the internal space of the die head is returned to the tank via the head circulation passage. According to this coating device, the coating material contained in the internal space of the die head is returned to the tank, thereby removing air bubbles that were present in the internal space of the die head. (4) In the coating device, the control unit may be configured to perform a second process as the bubble removal process, in which the coating material contained in the internal space of the die head is ejected from the die head to the outside. According to this coating device, the coating material contained in the internal space of the die head is discharged to the outside, thereby removing air bubbles that have been present in the internal space of the die head. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 2 is a schematic diagram showing the configuration of a coating device. [Figure 2] 3 is a flowchart of a coating process according to an embodiment. [Figure 3] 10 is a graph showing changes in pressure inside the die head when there are few bubbles. [Figure 4] 10 is a graph showing changes in pressure inside the die head when there are many bubbles. DETAILED DESCRIPTION OF THE INVENTION

[0007] 1 is a schematic diagram showing the configuration of a coating unit 100 according to an embodiment. The coating unit 100 includes a coating section 100 that applies a coating material to a workpiece WK, and a control section 300 that controls the coating unit 100.

[0008] The coating unit 100 includes a tank 110 that stores a liquid or paste-like coating material, a die head 120 that discharges the coating material, a first pipe 210 that forms a flow path from the tank 110 to the die head 120, and a second pipe 220 that branches off from the first pipe 210 and connects to the tank 110. A branching section 190 is provided between the first pipe 210 and the second pipe 220. The coating unit 100 further includes a coating valve 150 that is disposed between the branching section 190 and the die head 120, and a first circulation valve 160 that is disposed in the second pipe 220. A pump 200 is provided in a portion of the first pipe 210 between the branching section 190 and the tank 110. A suck-back valve 180 serving as a volume change device is provided in a portion of the first pipe 210 between the die head 120 and the coating valve 150.

[0009] The die head 120 and the tank 110 are further connected by a third pipe 230 that forms a flow path from the die head 120 to the tank 110. A second circulation valve 170 is disposed in the third pipe 230. The third pipe 230 is preferably connected to the upper surface of the die head 120 so as to extend vertically upward from the die head 120.

[0010] 1, the operating directions of the coating valve 150, the first circulation valve 160, the second circulation valve 170, and the suck-back valve 180 are indicated by arrows. The first pipe 210 corresponds to the "supply passage" in this disclosure. The third pipe 230 corresponds to the "head circulation passage" in this disclosure.

[0011] The tank 110 stores a coating material in a fluid or paste state. The coating material is, for example, a catalyst ink for a fuel cell. The pump 200 is used to supply the coating material from the tank 110 to a first pipe 210. The pump 200 is also used to return the coating material from the first pipe 210 to the tank 110 via a second pipe 220 or a third pipe 230.

[0012] The coating valve 150 is generally cylindrical and has a hole 151 that extends from the outer periphery of the cylinder, through the central axis, and to its end face. The hole 151 is connected to a first pipe 210. The coating valve 150 is driven by a first motor 191 connected to the coating valve 150 to rotate around the central axis of the generally cylindrical cylinder as the rotation axis. When the coating valve 150 rotates so that the position of the upstream opening of the hole 151 coincides with the position of the first pipe 210, the coating valve 150 enters an open state (open state) in which the coating material can pass through the hole 151. As a result, the coating material flows toward the die head 120, and the coating material is discharged from the die head 120. On the other hand, when the coating valve 150 rotates so that the position of the upstream opening of the hole 151 does not coincide with the position of the first pipe 210, the coating valve 150 enters a closed state (closed state) in which the coating material cannot pass through. In FIG. 1, the dispensing valve 150 is in an open state.

[0013] The first circulation valve 160 is disposed vertically above the coating valve 150. The first circulation valve 160, like the coating valve 150, is generally cylindrical and has a hole 161 that penetrates from the outer circumferential surface of the generally cylindrical cylinder, through the central axis of the generally cylindrical cylinder, to the outer circumferential surface at a diagonal line. The first circulation valve 160 is driven by a second motor 192 connected to the first circulation valve 160 to rotate around the central axis of the generally cylindrical cylinder as the rotation axis. When the first circulation valve 160 rotates and the position of the opening of the hole 161 coincides with the position of the second pipe 220, the first circulation valve 160 enters an open state (open state) in which the coating material can pass through the hole 161. This allows the coating material to flow through the second pipe 220. On the other hand, when the first circulation valve 160 rotates and the position of the opening of the hole 161 does not match the position of the second pipe 220, the first circulation valve 160 enters a closed state in which the coating material cannot pass through. In Fig. 1, the first circulation valve 160 is in a closed state.

[0014] The second circulation valve 170 is disposed in the third pipe 230 as a circulation passage for the head. The second circulation valve 170 has a configuration similar to that of the first circulation valve 160, and has a hole 171. The second circulation valve 170 is driven to rotate by a third motor 193 connected to the second circulation valve 170. In FIG. 1, the second circulation valve 170 is in a closed state.

[0015] A portion 211 of the first piping 210 from the branching portion 190 to the coating valve 150 extends vertically downward from the branching portion 190. A portion 221 of the second piping 220 from the branching portion 190 to the first circulation valve 160 extends vertically upward from the branching portion 190. This portion 221 of the second piping 220 functions as an air reservoir that accumulates air contained in the coating material flowing from the branching portion 190 to the coating valve 150.

[0016] The suck-back valve 180 is a generally cylindrical piston disposed between the die head 120 and the coating valve 150, and is configured to be insertable into a valve chamber 181 provided in the first pipe 210. The valve chamber 181 is also referred to as the "suck-back chamber." A fourth motor 194 is connected to the suck-back valve 180. The suck-back valve 180 advances into the valve chamber 181 and retreats from the valve chamber 181 using power received from the fourth motor 194. When the suck-back valve 180 advances, the volume of the coating material supply passage decreases, increasing the pressure within the supply passage. On the other hand, when the suck-back valve 180 retreats, the volume of the coating material supply passage increases, decreasing the pressure within the supply passage. The suck-back valve 180 corresponds to a volume change device that imparts a volume change to the coating material supply passage. However, a volume change device other than the suck-back valve 180 may also be used.

[0017] The die head 120 is a component with a discharge slit 121 formed at its tip, and is connected to the first pipe 210 and the third pipe 230. The tip of the die head 120 is positioned to face the roll-shaped workpiece WK to be coated. The die head 120 discharges the coating material that has flowed in via the first pipe 210 from the slit 121, and forms a coating film of the coating material on the surface of the workpiece WK, which is rotating in a position opposite the tip of the die head 120.

[0018] A storage chamber 122 for storing the coating material is provided inside the die head 120. The storage chamber 122 is a type of internal space of the die head 120. A pressure sensor 123 for measuring the pressure in the internal space of the die head 120 is installed in the storage chamber 122.

[0019] The coating unit 100 further includes a cap 124 that can be attached to the tip of the die head 120 and a cap drive mechanism 125 that attaches and detaches the cap 124. Attaching the cap 124 to the tip of the die head 120 makes it possible to close the slit 121 of the die head 120. For example, when a volume change is applied to the coating material supply passage using the suck-back valve 180, attaching the cap 124 to the die head 120 makes it possible to more accurately measure the pressure change in the supply passage caused by the volume change. Sealing the die head 120 in this manner is particularly useful when the thickness of the slit 121 is 0.05 mm or less. The cap 124 and the cap drive mechanism 125 can be omitted.

[0020] The coating device 10 of this embodiment can utilize the discharge state and two circulation states described below. <Discharge state> In the discharge state, the coating material stored in the tank 110 reaches the die head 120 via the first pipe 210 and is discharged from the die head 120 to the outside in response to the operation of the suck-back valve 180. In the discharge state, the coating valve 150 is set to an open state, and the first circulation valve 160 and the second circulation valve 170 are set to a closed state. The dotted arrows in FIG. 1 indicate the flow of the coating material in the discharge state. When the suck-back valve 180 advances into the valve chamber 181 while the coating material is stored in the storage chamber 122 of the die head 120, the pressure Pc in the internal space of the die head 120 increases, and the coating material is discharged from the slit 121 of the die head 120 to the outside.

[0021] <First circulation state> The first circulation state is a state in which the coating material in the first pipe 210 returns to the tank 110 from the branching portion 190 via the second pipe 220. In the first circulation state, the coating valve 150 and the second circulation valve 170 are set to a closed state, and the first circulation valve 160 is set to an open state.

[0022] <Second circulation state> The second circulation state is a state in which the coating material in the die head 120 returns to the tank 110 via the third pipe 230. In the second circulation state, the coating valve 150 and the second circulation valve 170 are set to an open state, and the first circulation valve 160 is set to a closed state. This second circulation state can be used in the air bubble removal process described below.

[0023] In either the discharge state or the two circulation states described above, the coating material is driven by the pump 200 to flow through the first pipe 210 in a direction toward the branching portion 190. Therefore, the first pipe 210 is maintained in a state filled with the coating material.

[0024] The control unit 300 acquires the pressure Pc in the internal space of the die head 120 measured by the pressure sensor 123 and controls the operation of the pump 200 and the motors 191-194. As will be described later, the control unit 300 determines whether or not to perform coating in response to a change in pressure in the internal space of the die head 120 that occurs with the operation of the suck-back valve 180. The control unit 300 may be configured as a computer having a processor and memory, or may be configured as a hardware circuit. In the former case, a computer program that realizes the functions of the control unit 300 is stored in the memory.

[0025] Fig. 2 is a flowchart of a coating process according to an embodiment. The process of Fig. 2 may be performed periodically when coating a product, or may be performed at any timing in response to an instruction from an operator.

[0026] In step S11, the control unit 300 executes preparation for coating. In preparation for coating, for example, the pump 200 is operated in the circulation state described above to supply the coating material from the tank 110 to the die head 120 via the first pipe 210. It is also preferable to operate the pump 200 in each of the first and second circulation states described above to fill the second pipe 220 and the third pipe 230 with the coating material.

[0027] In step S12, the control unit 300 applies a volume change to the supply passage for the coating material. In this embodiment, the volume change of the supply passage is performed by advancing and retracting the suck-back valve 180. The volume change is preferably performed in the second circulation state described above. In addition, it is preferable to attach a cap 124 to the tip of the die head 120.

[0028] In step S13, the control unit 300 calculates a pressure change ΔPc in the internal space of the die head 120 due to a change in the volume of the supply passage. The pressure change ΔPc is the difference between the maximum and minimum values ​​of the pressure Pc in the internal space of the die head 120.

[0029] In step S14, the control unit 300 compares the pressure change ΔPc in the internal space of the die head 120 with a preset reference value ΔPr1.

[0030] Fig. 3 is a graph showing the pressure change ΔPc inside the die head 120 when there are few air bubbles in the internal space of the die head 120, and Fig. 4 is a graph showing the pressure change ΔPc inside the die head 120 when there are many air bubbles in the internal space of the die head 120. In these examples, the suck-back valve 180 is advanced and retracted three times. The advancement amount and retraction amount of the suck-back valve 180 in Figs. 3 and 4 are each constant values ​​that have been set in advance.

[0031] In the example of Fig. 3, the internal space of the die head 120 contains few air bubbles, so the pressure change ΔPc in the internal space of the die head 120 is large. On the other hand, in the example of Fig. 4, the internal space of the die head 120 contains many air bubbles, so the volume change of the supply passage is absorbed by the volume change of the air bubbles, and the pressure change ΔPc in the internal space of the die head 120 is small. Thus, the pressure change ΔPc in the internal space of the die head 120 tends to be larger as the number of air bubbles contained in the coating material supply passage increases, and tends to be smaller as the number of air bubbles increases.

[0032] In step S14, if the pressure change ΔPc is equal to or smaller than the reference value ΔPr1, it is determined that the coating is affected by air bubbles, and the process proceeds to step S15, where the control unit 300 executes a bubble removal process. As the bubble removal process, for example, the following first process and second process can be used.

[0033] <First process for removing bubbles> The first process is a process in which the coating unit 100 is set to the second circulation state described above, and the coating material in the internal space of the die head 120 is returned to the tank 110 via the third pipe 230. By performing the first process, air bubbles contained in the coating material in the internal space of the die head 120 can be removed. To efficiently remove air bubbles in the first process, the third pipe 230 is preferably connected to the upper surface of the die head 120, and particularly preferably is provided so as to extend vertically upward from the upper surface of the die head 120.

[0034] <Second process for removing bubbles> The second process is a process in which the coating material present in the internal space of the die head 120 is discharged to the outside through the slit 121. In this second process, the coating unit 100 is set to the discharge state described above. Because the coating material discharged in the second process is not applied to the workpiece WK, the second process is also called a "blank discharge process." In this second process, air bubbles contained in the coating material in the internal space of the die head 120 can be released to the outside.

[0035] From the viewpoint of reducing unnecessary consumption of coating material, the first process is preferable to the second process. On the other hand, from the viewpoint of shortening the processing time, the first process may be preferable. As the bubble removal process, only one of the first process and the second process may be performed, or both may be performed. Also, other types of bubble removal processes may be performed. After performing step S15, the process returns to step S12, and the processes from step S12 onward are performed again.

[0036] In step S14, if the pressure change ΔPc is greater than the reference value ΔPr1, it is assumed that there is no effect of air bubbles on the coating, and the process proceeds to step S16, where the control unit 300 carries out coating of the product. That is, the coating material is discharged from the die head 120 onto the workpiece WK to form a coating film of the coating material on the surface of the workpiece WK.

[0037] 3 and 4, in addition to the first reference value ΔPr1, a second reference value ΔPr2 greater than the first reference value ΔPr1 may be used as the reference value for the pressure change ΔPc. In this case, when the pressure change ΔPc is equal to or greater than the second reference value ΔPr2, the continuous execution length of product coating may be increased compared to when the pressure change ΔPc is greater than the first reference value ΔPr1 but less than the second reference value ΔPr2. The "continuous execution length of product coating" refers to the total relative distance traveled by the slit 121 over the surface of the workpiece WK while discharging the coating material when product coating is performed continuously or intermittently without performing the bubble checking process in steps S12 to S14.

[0038] The volume change of the supply passage in step S12 is preferably performed multiple times, as illustrated in Figures 3 and 4. Furthermore, the volume decrease of the supply passage is preferably performed so as to prevent the coating material from being discharged from the die head 120. For example, if the volume change of the supply passage is performed with the cap 124 attached to the tip of the die head 120, the coating material can be prevented from being discharged from the die head 120. Alternatively, if the volume change of the supply passage is performed without the cap 124 attached to the tip of the die head 120, the advancement amount of the suck-back valve 180 in step S12 may be set smaller than that during coating in step S16 to prevent the coating material from being discharged from the die head 120.

[0039] According to the processing procedure in Figure 2, it is possible to perform good coating without performing test coating. For example, when test coating is performed to check the coating condition, there is a problem that coating material is wasted for the test coating, which increases production costs. On the other hand, the present embodiment has the advantage that good coating can be performed without performing test coating.

[0040] As described above, in this embodiment, it is possible to check whether or not air bubbles are affecting the coating from the pressure change that occurs when a volume change is applied to the coating material supply passage. Furthermore, it is possible to determine whether or not dispensing is possible based on the pressure change, and if it is determined that dispensing is possible, the coating material can be dispensed onto the workpiece WK. Therefore, it is possible to perform good coating without performing a trial coating.

[0041] Other forms: The present disclosure is not limited to the above-described embodiments and can be realized in various forms without departing from the spirit thereof. For example, the present disclosure can also be realized in the following aspects. The technical features in the above embodiments corresponding to the technical features in each aspect described below can be appropriately replaced or combined to solve some or all of the problems of the present disclosure or to achieve some or all of the effects of the present disclosure. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0042] The present disclosure may be realized in various forms other than a coating device, such as a coating method, a control method for a coating device, a computer program for executing processing by a coating device, or a non-transitory storage medium on which a computer program is recorded. [Explanation of symbols]

[0043] 10...coating device, 100...coating section, 110...tank, 120...die head, 121...slit, 122...storage chamber, 123...pressure sensor, 124...cap, 125...cap drive mechanism, 150...coating valve, 151...hole, 160...first circulation valve, 161...hole, 170...second circulation valve, 171...hole, 180...suckback valve, 181...valve chamber, 190...branch section, 191-194...motor, 200...pump, 210...first piping, 211...portion of first piping, 220...second piping, 221...portion of second piping, 230...third piping, 300...control section

Claims

1. A coating device that applies a coating material to an object to be coated, a coating unit including a tank for storing the coating material, a die head for discharging the coating material, a supply passage constituting a flow path from the tank to the die head, a volume change device for applying a volume change to the supply passage, and a pressure sensor for detecting a pressure in an internal space of the die head; a control unit that controls the operation of the coating unit; Equipped with The control unit is configured to determine whether or not the coating material can be ejected from the die head based on the change in pressure when a volume change is applied to the supply passage by the volume change device, and to start ejecting the coating material onto the workpiece if ejection is possible.

2. The coating device according to claim 1, The control unit is configured to perform a bubble removal process to remove bubbles present in the internal space of the die head when the discharge is not possible.

3. The coating device according to claim 2, the coating unit further includes a head circulation passage that forms a flow path from the die head to the tank, The control unit is configured to perform a first process as the bubble removal process, which returns the coating material contained in the internal space of the die head to the tank via the head circulation passage.

4. The coating device according to claim 2, The control unit is configured to be able to execute a second process as the bubble removal process, in which the coating material contained in the internal space of the die head is ejected from the die head to the outside.

Images