Film formation method, film formation apparatus, and heat exchanger

Abstract

To form a film that has little difference over the entire length of a communication hole in terms of a state of being formed.SOLUTION: A film formation method sequentially includes: a step S5 of starting suction of gas in a communication hole 103 from an open end 102 side of the other side; a step S10 of starting pressurization and influx of medium gas 91 into the communication hole 103 from an open end 101 side of one side; a step S15 of starting spray of a mixed gas 93, obtained by atomizing and mixing a liquid agent 92 with the predetermined medium gas 91, into the communication hole 103 from the open end 101 side of the one side; steps S20, S30 of stopping atomization, suction, and influx; a step S40 of starting suction of gas in the communication hole 103 from the open end 101 side of the one side; a step S45 of starting pressurization and influx of the predetermined medium gas 91 into the communication hole 103 from the open end 102 side of the other side; a step S50 of starting atomization of the mixed gas 93 into the communication hole 103 from the open end 102 side of the other side; and steps S55, S65 of stopping atomization, suction, and influx.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a coating method and coating device for applying a liquid agent or the like to the inner surface of a communicating hole in a workpiece to form a coating, and to a heat exchanger having a communicating hole on which such a coating is formed. [Background technology]

[0002] Patent Document 1 describes a technology in which a solution is injected into a glass tube in the form of a mist from one opening and then sucked from the other opening, causing the solution to be applied to the inner surface of the glass tube and form a coating. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 58-64246 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional technology, there was a difference in the state of the coating (e.g., the thickness of the coating) between the vicinity of the one opening on the side where the mist-like solution is enclosed and the vicinity of the other opening on the side where the solution is sucked in. This difference was particularly noticeable when the length of the glass tube was large.

[0005] The present invention has been made in consideration of these problems, and has an object to provide a coating formation method and coating formation device that can form a coating with little variation in its formation state over the entire length of a communicating hole, and a heat exchanger having a communicating hole with such a coating formed thereon. [Means for solving the problem]

[0006] In order to solve the above problems, according to one aspect of the present invention, there is provided a coating forming method for forming a coating on an inner surface of a workpiece having a communication hole therein that communicates between a first opening end and a second opening end by applying a predetermined liquid agent to the inner surface of the communication hole, the method including a first suction start step of starting suction of gas in the communication hole from the second opening end side, a first flow start step of starting pressurization and flow of a predetermined medium gas into the communication hole from the first opening end side, and a second flow start step of spraying a mixed gas obtained by mixing the predetermined liquid agent into a mist and mixing it with the predetermined medium gas from the first opening end side into the communication hole. a first spray start process for starting a gas supply from the first opening end side to the communicating hole; a first spray stop process for stopping the spray; a first suction inflow stop process for stopping the suction and inflow; a second suction start process for starting suction of gas in the communicating hole from the first opening end side; a second inflow start process for starting pressurization and inflow of the predetermined medium gas into the communicating hole from the second opening end side; a second spray start process for starting spraying the mixed gas from the second opening end side to the communicating hole; a second spray stop process for stopping the spray; and a second suction inflow stop process for stopping the suction and inflow.

[0007] According to another aspect of the present invention, there is provided a coating forming apparatus for applying a predetermined liquid agent to an inner surface of a communication hole that communicates between a first opening end and a second opening end to form a coating on a workpiece having an internal communication hole that communicates between the first opening end and the second opening end, the coating forming apparatus including a calculation unit that performs a first suction start step of starting suction of gas in the communication hole from the second opening end side, a first flow start step of starting pressurization and flow of a predetermined medium gas into the communication hole from the first opening end side, and a second flow start step of mixing the predetermined liquid agent into a mist and the predetermined medium gas with the mist and flowing the mixture gas into the communication hole from the first opening end side. the first spray start process for starting spraying into the communicating hole from the first opening end side; a first spray stop process for stopping spraying; a first suction / inflow stop process for stopping suction and inflow; a second suction start process for starting suction of gas in the communicating hole from the first opening end side; a second inflow start process for starting pressurization and inflow of the predetermined medium gas into the communicating hole from the second opening end side; a second spray start process for starting spraying of the mixed gas from the second opening end side into the communicating hole; a second spray stop process for stopping spraying; and a second suction / inflow stop process for stopping suction and inflow.

[0008] According to another aspect of the present invention, there is provided a heat exchanger having a communication hole therein communicating between a first opening end and a second opening end, and a coating formed on an inner surface of the communication hole by applying a predetermined liquid agent, the heat exchanger including a first suction start step of starting suction of gas in the communication hole from the second opening end side, a first inflow start step of starting pressurization and inflow of a predetermined medium gas into the communication hole from the first opening end side, and a first spray start step of starting spraying a mixed gas obtained by mixing the predetermined liquid agent into a mist and mixing it with the predetermined medium gas, from the first opening end side, into the communication hole. the coating is formed by sequentially executing a first spray stop process of stopping spraying, a first suction inflow stop process of stopping suction and inflow, a second suction start process of starting suction of gas in the communicating hole from the first opening end side, a second inflow start process of starting pressurization and inflow of the specified medium gas into the communicating hole from the second opening end side, a second spray start process of starting spraying the mixed gas from the second opening end side into the communicating hole, a second spray stop process of stopping spraying, and a second suction inflow stop process of stopping suction and inflow. Effect of the Invention

[0009] According to the present invention, a coating can be formed with little variation in its state over the entire length of the communicating hole. [Brief description of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram showing an example of the overall configuration of a film forming apparatus according to an embodiment of the present invention; [Diagram 2] 11A to 11C are diagrams illustrating an example of a process for passing a gas mixture through a communication hole from one side of a pipe to the other side. [Diagram 3] 13A to 13C are diagrams illustrating an example of a process for passing a gas mixture through a communication hole from the other side to the one side of a pipe. [Figure 4] 10 is a flowchart showing an example of details of a control procedure executed by a CPU of a control unit to realize a work process of a film forming process. [Diagram 5]FIG. 1 is a diagram showing an example of the configuration of a film forming apparatus in which the direction of a workpiece is changed using a turntable. [Figure 6] FIG. 13 is a diagram showing an example of the configuration of a film forming apparatus that switches the flow direction of a mixed gas. [Figure 7] FIG. 2 is a diagram showing an example of the configuration of a film forming device that vibrates a workpiece. [Figure 8] 1A to 1C are diagrams illustrating a state in which a pinhole is formed and how the pinhole is removed by vibration. [Figure 9] FIG. 2 is a diagram showing an example of the configuration of a film forming apparatus that magnetizes a workpiece; [Figure 10] FIG. 1 is a diagram showing the configurations of two types of field rings: an axial path type and a radial path type. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment will be described with reference to the drawings.

[0012] <1. Overall configuration of the coating formation device> First, an example of the configuration of the coating forming apparatus according to the present embodiment will be described with reference to FIG. 1. FIG. 1 shows an example of the overall configuration of the coating forming apparatus 1 according to the present embodiment. In the illustrated example of the present embodiment, a long annular pipe 100 is used as a workpiece, and a predetermined liquid agent is applied to the inner surface of the workpiece to form a coating. More specifically, the workpiece to be handled by the coating forming apparatus 1 is a workpiece having two opening ends 101, 102 on the outer surface and a communication hole 103 inside that communicates between the two opening ends 101, 102. The communication hole 103 (workpiece) itself is assumed to be made of a material having a certain mechanical strength that does not expand or contract due to some force or heat.

[0013] The coating forming device 1 has a medium gas storage section 2, an inflow pump 3, an inflow adapter 4, a liquid storage section 5, a spray pump 6, a spray nozzle 7, a suction adapter 8, a suction pump 9, a suction gas storage section 10, an operation section 11, and a control section 12.

[0014] The medium gas storage unit 2 is an airtight container that stores the medium gas to be mixed with the liquid. The medium gas is preferably a dry gas (dry air) that is mainly composed of an inert gas such as nitrogen (N2) and is mixed with atmospheric air to adjust the oxygen (O2) concentration to 0-15%, which is lower than the normal atmospheric concentration (18%), and is maintained at a temperature of 5°C to 30°C.

[0015] The inflow pump 3 is a pump that pressurizes the medium gas stored in the medium gas storage section 2 and supplies it into a chamber 4a of the inflow adaptor 4, which will be described later.

[0016] The inflow adaptor 4 is a functional part that is connected to an open end 101 on one side (the right side in the figure) of the workpiece and allows the medium gas supplied from the inflow pump 3 to flow into the open end 101. The inflow adaptor 4 in the illustrated example of this embodiment has a chamber 4a therein that communicates with the inflow pump 3, and the opening of the chamber 4a is configured to be directly fitted and connected to one end of the pipe 100, which is the workpiece.

[0017] The liquid storage section 5 is, for example, a sealed container that stores the liquid. The liquid is preferably an inorganic liquid or fluorine that becomes a coating having functions such as heat resistance of 200°C or more, chemical resistance, or corrosion resistance when dried. In contrast, the material of the workpiece to which the liquid is applied (particularly the inner surface 104 portion that forms the communication hole 103) can basically be either metal or nonmetal, but in the case of metal, stainless steel, copper, aluminum, etc. are particularly preferable.

[0018] The spray pump 6 is a pump that pressurizes the liquid stored in the liquid storage section 5 and supplies it to a spray nozzle 7 described later.

[0019] The spray nozzle 7 is a nozzle that is connected to the inflow adapter 4 and sprays the liquid agent supplied from the spray pump 6 in the form of a mist from within the chamber 4a toward the open end 101 of the workpiece. The particle size of the spray is adjusted as appropriate according to the liquid agent, the medium gas, the function of the coating, the material of the workpiece, and the like. If the liquid agent is not a solution in which a pigment is dissolved, the liquid agent may be volatilized into a mist by ultrasonic vibration or the like and sprayed (not shown in the figure).

[0020] The suction adapter 8 is a functional part that is connected to an open end 102 on the other side (the left side in the figure) of the workpiece, and sucks gas in a communication hole 103 from the open end 102 by the suction force of a suction pump 9 described later. The suction adapter 8 in the illustrated example of this embodiment has a chamber 8a therein that communicates with the suction pump 9 described later, and the opening of the chamber 8a is configured to be directly fitted and connected to one end of a pipe 100, which is the workpiece.

[0021] The suction pump 9 is a pump that sucks gas from the communication hole 103 of the workpiece through the chamber 8a of the suction adapter 8 and discharges it to a suction gas storage section 10 described later.

[0022] The aspirated gas storage section 10 is an airtight container that stores the gas sucked and discharged by the suction pump 9. When the gas discharged by the suction pump 9 can be discharged to the outside air, the aspirated gas storage section 10 may be omitted and the gas may be directly discharged to the outside air.

[0023] The operation unit 11 is a functional unit that accepts input operations of various commands and parameters from an operator.

[0024] The control unit 12 is composed of a computer equipped with memories such as a CPU, ROM, and RAM, or a PLC (Programmable Logic Controller), and controls the operations of the inflow pump 3, spray pump 6, and suction pump 9 in a predetermined sequence based on various commands and parameters input from the operation unit 11.

[0025] <2. Film formation process> Next, the working steps of the coating process using the coating forming device 1 will be described with reference to Figs. 2 and 3. In this embodiment, an operator manually connects the inflow adapter 4 to one end of the pipe 100 and the suction adapter 8 to the other end. The adapters 4 and 8 may be detachably connected by other mechanical configurations (e.g., configurations using fixing jigs such as clamps) not shown (hereinafter the same). At this time, the open end 101 on one side of the pipe 100 connected to the inflow adapter 4 corresponds to the first open end described in each claim, and the open end 102 on the other side of the pipe 100 connected to the suction adapter 8 corresponds to the second open end described in each claim.

[0026] Then, first, the suction pump 9 starts its suction operation, whereby the gas within the communication hole 103 is sucked in as shown in FIG. 2(a).

[0027] Next, the inflow pump 3 starts its inflow operation, so that the medium gas 91 flows through the entire length of the communication hole 103 as shown in FIG. 2(b).

[0028] Next, by starting the supply operation of the spray pump 6, the liquid agent 92 sprayed from the spray nozzle 7 is mixed with the gas medium 91 as shown in Fig. 2(c), and the mixed gas 93 flows through the communication hole 103 of the pipe 100 and is sucked and discharged from the suction adapter 8. At this time, the mixed gas 93 containing the liquid agent 92 flows smoothly over the entire length of the communication hole 103 due to the positive pressure on the inlet side and the negative pressure on the suction side, so that the liquid agent 92 can be applied to the inner surface 104 of the communication hole 103 over a long range that cannot be reached by the spraying operation only by the normal spray nozzle 7. In addition, due to the flow pressure of the mixed gas 93 itself, the liquid agent 92 applied to the inner surface 104 is applied uniformly without being locally accumulated, forming a coating 94.

[0029] However, for example, when the length dimension of the communication hole 103 is larger than a certain value, the liquid agent 92 in the mixed gas 93 on the suction side mainly passes through the vicinity of the axial center of the communication hole 103, and only the medium gas 91 flows on the outer periphery, and the liquid agent 92 is not applied to the inner surface 104. For this reason, as shown in each of Figures 2(c) to 2(g), a difference may occur in the formation state of the coating 94 (for example, the thickness of the coating 94) between the vicinity of the opening end 101 on the inflow side and the vicinity of the opening end 102 on the suction side.

[0030] Next, the supply operation of the spray pump 6 is stopped. Here, as shown in FIG. 2(d), the liquid agent 92 just applied to the inner surface 104 generates hydrogen (H2) and other gases from itself to fill the inside of the communication hole 103, but these hydrogen (H2) and other gases themselves are likely to have an adverse effect on the film formation of the liquid agent 92. On the other hand, when the liquid agent 92 just applied to the inner surface 104 comes into contact with a large amount of oxygen (O2) or moisture (H2O), its properties are altered by the so-called sol-gel reaction. For this reason, after the spraying of the liquid agent 92 is stopped, the inflow and suction of the medium gas 91 (in this example, dry air mainly composed of inert gas N2) is continued for a certain period of time or more, as shown in FIG. 2(e), to remove unnecessary gases in the communication hole 103 as much as possible. This duration is appropriately set according to the type and amount of the liquid agent 92 applied, the volume of the communication hole 103, and the like.

[0031] Next, the inflow pump 3 and the suction pump 9 are stopped, so that the communication hole 103 is filled with only the medium gas 91, as shown in Fig. 2(f). At this point, the mixture may be left to dry naturally for a certain period of time.

[0032] Next, in order to eliminate the difference in the formation state of the coating 94 (e.g., the thickness of the coating 94) between the vicinity of the opening end 101 on the inflow side of the pipe 100 and the vicinity of the opening end 102 on the suction side, the opening ends 101, 102 of the pipe 100 are swapped and the mixed gas 93 of the medium gas 91 and the liquid agent 92 is allowed to circulate again.

[0033] That is, as shown in FIG. 2(g), the inflow adaptor 4 and the suction adaptor 8 are attached and detached, and the direction of the pipe 100 is changed by an operator manually.

[0034] Then, by repeating steps similar to those shown in Figures 2(a) to 2(f) above, the liquid agent 92 can be uniformly applied to the inner surface 104 over the entire length of the communicating hole 103, as shown in Figures 3(a) to 3(f), i.e., the formation state of the coating 94 between both opening ends 101, 102 of the communicating hole 103 can be made the same.

[0035] 3(g), the communication hole 103 is filled with the medium gas 91 and left for a certain period of time to allow the liquid agent 92 to dry naturally, thereby forming a stable coating 94. In this drying process, dry air at a relatively high temperature and with an oxygen concentration of 18% to 100%, which exceeds that of normal air, may be circulated as the medium gas 91. Alternatively, instead of natural drying, a general continuous oven or batch drying may be used.

[0036] By carrying out the series of work steps shown in Figures 2(a) to 2(g) and Figures 3(a) to 3(g) above, it is possible to form a uniform coating 94 on the inner surface 104 over the entire length of the workpiece, even for workpieces in which the length dimension of the communicating hole 103 is large.

[0037] <3. Control flow> Next, details of the control procedure executed by the CPU (corresponding to the calculation unit) of the control unit 12 to realize the above-mentioned work steps of the coating formation process will be described with reference to the flowchart of Fig. 4. Note that execution of this flow starts when an operator manually connects the pipe 100 to the inlet adaptor 4 and the suction adaptor 8 in advance and performs an input operation to start the work of the coating formation process via the operation unit 11. In this flow, each step is executed, and then the next step is executed after a certain time interval.

[0038] First, in step S5, the CPU of the control unit 12 controls the suction pump 9 to start its suction operation. Note that the procedure of step S5 corresponds to a first suction start step recited in each claim.

[0039] Next, the process proceeds to step S10, where the CPU of the control unit 12 controls the inflow pump 3 to start its inflow operation. Note that the procedure of step S10 corresponds to a first inflow start step described in each claim.

[0040] Next, the process proceeds to step S15, where the CPU of the control unit 12 controls the spray pump 6 to start its spraying operation. In this step S10, the spraying operation is continued for an operation time that is set particularly depending on the inner diameter and length of the communication hole 103, the type and application amount of the liquid agent 92, etc. The procedure of this step S15 corresponds to the first spray start step described in each claim.

[0041] Next, the process proceeds to step S20, where the CPU of the control unit 12 controls the spray pump 6 to stop the spraying operation. Note that the procedure of step S20 corresponds to a first spray stopping step described in each claim.

[0042] Next, the process proceeds to step S25, where the CPU of the control unit 12 waits in a loop until a preset duration has elapsed. This duration is appropriately set according to the type and application amount of the liquid agent 92, the volume inside the communication hole 103, and the like, so that unnecessary gas can be eliminated by the circulation of the gas medium 91, as described above. The procedure of step S25 corresponds to a first suction inflow continuation step described in each claim.

[0043] Next, the process proceeds to step S30, where the CPU of the control unit 12 controls the inflow pump 3 and the suction pump 9 to stop their operation. Note that the procedure of step S30 corresponds to a first suction / inflow stopping step described in each claim.

[0044] Next, the process proceeds to step S35, where the CPU of the control unit 12 loops into standby mode until an operation to instruct the operator to resume work is input via the operation unit 11. During this time, the operator can change the direction of the pipe 100.

[0045] Next, the process proceeds to step S40, where the CPU of the control unit 12 controls the suction pump 9 to start its suction operation in the same manner as in step S5 above. Note that the procedure of step S40 corresponds to a second suction start step described in each claim.

[0046] Next, the process proceeds to step S45, where the CPU of the control unit 12 controls the inflow pump 3 to start the inflow operation in the same manner as in step S10. Note that the procedure of step S45 corresponds to the second inflow start step described in each claim.

[0047] Next, the process proceeds to step S50, where the CPU of the control unit 12 controls the spray pump 6 to start the spray operation in the same manner as in step S15. The procedure of step S50 corresponds to the second spray start step described in each claim.

[0048] Next, the process proceeds to step S55, where the CPU of the control unit 12 controls the spray pump 6 to stop the spraying operation in the same manner as in step S20. Note that the procedure of step S55 corresponds to the second spray stopping step described in each claim.

[0049] Next, the process proceeds to step S60, where the CPU of the control unit 12 waits in a loop until a preset duration time has elapsed, similar to step S25. The procedure of step S60 corresponds to the suction inflow continuing step described in each claim.

[0050] Next, the process proceeds to step S65, where the CPU of the control unit 12 controls the inflow pump 3 and the suction pump 9 to stop their operation in the same manner as in step S30. Then, this flow ends. Note that the procedure of step S65 corresponds to the second suction inflow stopping step described in each claim.

[0051] 4. Effects of this embodiment As described above, in the coating forming apparatus 1 of this embodiment, the CPU included in the coating forming apparatus 1 executes the following steps: step S5, which starts suction of the gas in the communication hole 103 from the opening end 102 on the other side; step S10, which starts pressurizing and flowing the predetermined medium gas 91 into the communication hole 103 from the opening end 101 on one side; step S15, which starts spraying the mixed gas 93, which is obtained by mixing the predetermined liquid agent 92 into a mist and mixing it with the predetermined medium gas 91, into the communication hole 103 from the opening end 101 on one side; Step S20 of stopping the gas supply, step S30 of stopping the suction and inflow, step S40 of starting the suction of the gas in the communication hole 103 from the opening end 101 on one side, step S45 of starting the pressurization and inflow of a predetermined medium gas 91 into the communication hole 103 from the opening end 102 on the other side, step S50 of starting the spraying of the mixed gas 93 from the opening end 102 on the other side into the communication hole 103, step S55 of stopping the spraying, and step S65 of stopping the suction and inflow are executed in this order. As a result, even for a workpiece having a large length dimension of the communication hole 103, the coating 94 can be formed uniformly on the inner surface 104 over its entire length. Note that the execution of the above-mentioned work steps is not limited to automatic control by the control unit 12, and may be controlled in the same procedure by manual operation by an operator via an operation panel or the like not shown in the figure.

[0052] In this embodiment, in particular, between steps S20 and S30, and between steps S55 and S65, steps S25 and S60 are executed to continue suction and inflow for a predetermined period of time or more, respectively. This allows hydrogen (H2) and other gases that are generated from the liquid agent 92 just applied to the inner surface 104 and that adversely affect the formation of the coating to be sufficiently removed by the flow of the medium gas 91.

[0053] Particularly in this embodiment, the medium gas 91 is dry air (low humidity dry gas) at a temperature of 5° C. to 30° C. This makes it possible to prevent the liquid agent 92 just applied to the inner surface 104 from deteriorating in properties by suppressing the so-called sol-gel reaction that occurs when the liquid agent 92 comes into contact with oxygen or moisture.

[0054] <5. Modifications> The disclosed embodiment is not limited to the above, and various modifications are possible without departing from the spirit and technical concept of the present invention. Such modifications will be described below.

[0055] <5-1. When changing the direction of the workpiece using a turntable> In the above embodiment, a configuration has been described in which the direction of the workpiece is manually changed by an operator, but it is also possible to use a configuration that includes a turntable (corresponding to a workpiece setting table) that can change the direction of the workpiece by fixing the workpiece and rotating it.

[0056] For example, as shown in Fig. 5 (omitting the inflow pump 3, suction pump 9, etc.), when the workpiece is a large structure such as a heat exchanger 110 for use in a vehicle or air conditioning, it is a very cumbersome task for an operator to manually lift the workpiece and change its direction. In contrast, in this modified example, a turntable 14 is provided that can be rotated by driving a motor M via a reducer 13, and the workpiece is fixed on the turntable 14 by being held by a clamp 15 or the like. Both the inflow adaptor 4 and the suction adaptor 8 are mechanically attachable to and detachable from the two open ends 101, 102 of the workpiece, respectively.

[0057] As a result, for example, during the standby loop of step S35 shown in FIG. 4, a procedure for controlling the motor M to rotate the turntable 14 by 180 degrees in response to a separate input operation from the operation unit 11 may be executed.

[0058] In this manner, this modified example is provided with a turntable 14 that can fix the workpiece and change the position of the workpiece so that the positions of the opening end 101 on one side and the opening end 102 on the other side can be interchanged. This allows the direction of the workpiece to be automatically changed without manual labor by the worker even for a workpiece that is heavy or large in volume, and makes it easy to re-spray the liquid agent 92.

[0059] In addition, the heat exchanger 110 given above as an example of the workpiece often has a small inner diameter of the communicating hole 103 provided therein and a bent shape as shown in the figure. In that case, it is difficult to apply the liquid agent 92 to the entire length of the communicating hole 103 by simply spraying directly from the open end 101 with a spray gun or the like, and even if the liquid agent 92 is allowed to flow in as a liquid, it will quickly become clogged. For this reason, it is particularly useful to apply the present invention to the heat exchanger 110, which can apply the liquid agent 92 uniformly to the inner surface 104 over the entire length of the communicating hole 103 even if the communicating hole 103 has a small inner diameter and a bent shape, and form a coating 94.

[0060] <5-2. When changing the flow direction of the mixed gas> In the above embodiment, the configuration in which the direction of the workpiece is switched has been described, but it is also possible to use a configuration in which the flow direction of the mixed gas 93 is switched while keeping the direction of the workpiece the same.

[0061] For example, as shown in Fig. 6, two inflow suction adapters 16 (corresponding to a first flow section and a second flow section) having the same configuration are connected to two open ends 101, 102 of the workpiece, each of which communicates with the inflow pump 3 and the suction pump 9 via a chamber 16a, and each chamber 16a is provided with a spray nozzle 7 connected to a spray pump 6. Each of the inflow pump 3, the suction pump 9, and the spray pump 6 is connected to one of the inflow suction adapters 16 (spray nozzle 7) by the flow path switching control by the control unit 12 via a three-way valve 17. As for the switching combination, the inflow pump 3 and the spray pump 6 are always connected to the inflow suction adapter 16 on the same side, and only the suction pump 9 is connected to the inflow suction adapter 16 on the opposite side.

[0062] As a result, for example, during the standby loop of step S35 shown in FIG. 4, a control procedure may be executed to switch the flow paths of the pumps 3, 6, and 9 to the opposite directions from those until then.

[0063] In this manner, in this modified example, the inflow suction adapter 16 on one side is capable of switching between suction of the gas in the communication hole 103, pressurization and inflow of the medium gas 91 into the communication hole 103, and spraying of the liquid agent 92 into the communication hole 103 for the opening end 101 on one side, and the inflow suction adapter 16 on the other side is capable of switching between suction of the gas in the communication hole 103, pressurization and inflow of the medium gas 91 into the communication hole 103, and spraying of the liquid agent 92 into the communication hole 103 for the opening end 102 on the other side. This allows the flow direction of the mixed gas 93 to the communication hole 103 to be switched without attaching or detaching each adapter 16 or changing the attitude direction of the workpiece. Therefore, it is possible to easily re-spray the liquid agent 92 automatically without the operator having to do the manual work, particularly for a workpiece having a large weight or volume.

[0064] <5-3. When vibrating the workpiece> Even when the gas mixture 93 is passed through the communication hole 103 as in the present invention, pinholes may be formed on the inner surface 104 where the liquid agent 92 is not locally applied (see FIG. 8(a) described later). In order to prevent the formation of such pinholes, it is effective to vibrate the communication hole 103 together with the workpiece.

[0065] 7, for example, a vibration unit 19 is provided on a mounting table 18 that fixes a workpiece (a pipe 100 in the illustrated example) via a clamp 15 or the like, and the control unit 12 controls the operation of this vibration unit 19. The vibration unit 19 may be configured with a variety of components, such as an eccentric motor or ultrasonic generator (not shown), and the control unit 12 may appropriately set and control the vibration amplitude and frequency depending on the type of liquid agent 92, the material of the workpiece, etc.

[0066] As shown in Fig. 8(a), if the communication hole 103 (workpiece) is not vibrated and the mixed gas 93 is only flowing, pinholes 95 that make it difficult for the liquid 92 to adhere locally may be formed due to the surface tension of the liquid 92 itself adhering to the inner surface 104. These pinholes 95 may become points of corrosion or stress concentration for the workpiece. In contrast, if the communication hole 103 is vibrated with an appropriate amplitude and frequency as shown in Fig. 8(b), the surface tension of the liquid 92 itself can be broken and the formation of pinholes 95 can be suppressed.

[0067] In this manner, this modified example is provided with the vibration unit 19 that applies vibration to the workpiece from the outside. This makes it possible to suppress the formation of pinholes 95 on the inner surface 104 of the communication hole 103, thereby improving the durability of the workpiece.

[0068] <5-4. When the workpiece is magnetized> For example, when a liquid agent 92 containing magnetic powder can be used, the liquid agent 92 can be more effectively adhered to the inner surface 104 by generating a magnetic field around the communication hole 103 together with the workpiece while the mixed gas 93 is flowing.

[0069] 9, for example, an annular field ring 20 (corresponding to a field magnet portion) is configured to surround the outer periphery of the workpiece, and the field ring 20 is configured to be reciprocally movable along the flow direction of the mixed gas 93 via a feed screw 21 driven and controlled by a motor M. As a result, in a communication hole 103 through which the mixed gas 93 flows, particularly at a position locally magnetized by the moving field ring 20, an inner surface 104 of a pipe or the like forming the communication hole 103 is strongly magnetized (magnetized) itself, and a liquid agent 92 containing magnetic powder is likely to adhere thereto. In this case, it is assumed that the pipe or the like forming the communication hole 103 itself is a magnetic material that is easily magnetized.

[0070] Conversely, even if the piping or the like forming the communication hole 103 is made of a non-magnetic material, it itself can pass magnetic flux. Therefore, the liquid agent 92 containing magnetic powder and flowing through the communication hole 103 is stirred by the locally generated magnetic field, and is mixed again with the medium gas 91 downstream thereof, promoting adhesion to the inner surface 104.

[0071] The field ring 20 is configured to include a permanent magnet or an electromagnet and generate a magnetic flux path on the inner circumference side. When an electromagnet is included, the field is generated by field power supplied from a separate field power supply 22. The path of the magnetic flux generated by the field ring 20 may be configured to generate a magnetic flux path in an arrangement parallel to the central axis CL1 direction of the annular field ring 20 as shown in Fig. 10(a), or may be configured to generate a magnetic flux path mainly in the radial direction of the field ring 20 as shown in Fig. 10(b).

[0072] When generating magnetic flux using electromagnets, in the case of the axial path type shown in Fig. 10(a) above, a large field coil 23 may be formed around the central axis CL1 inside the field ring 20. In the case of the radial path type shown in Fig. 10(b) above, a plurality of field coils 24 may be provided at equal intervals in the circumferential direction on the inner peripheral surface of the field ring 20. Each field coil 24 is fixed with its respective central axis CL2 parallel to the radial direction of the field ring 20.

[0073] In the case of the axial path type, by passing current through a single field coil 23, a magnetic flux path can be generated in an arrangement parallel to the direction of the central axis CL1 of the field ring 20. Also, it is possible to supply AC power at a low frequency, and the polarity direction of the magnetic flux can be periodically switched.

[0074] In the case of the radial path type, for example, by providing three field coils 24 (or a multiple of three) and supplying three-phase AC of UVW to each, it is possible to generate a rotating magnetic field around the central axis CL1 of the field ring 20. Although not particularly shown, the polarity direction of the magnetic flux can also be effectively switched by rotating the field coil 24 around the central axis CL1 by mechanical drive.

[0075] In either configuration, when AC power is supplied, it is desirable to supply power at a low power and a low frequency, taking into consideration the magnetic effect on the workpiece and inductance.

[0076] In this manner, this modified example is provided with a field ring 20 that applies a field magnet to the workpiece from the outside. As a result, by applying a field magnet to the periphery of the communication hole 103 together with the workpiece while the mixed gas 93 of the liquid agent 92 containing magnetic powder is being circulated, it is possible to effectively adhere the liquid agent 92 to the inner surface 104 even if the amount of the liquid agent 92 is small.

[0077] In particular, in this modified example, at least one of the polarity direction of the field magnet and the field magnet position can be changed in the field ring 20. This promotes the stirring of the liquid agent 92 containing the magnetic powder and flowing through the communication hole 103 and the adhesion of the liquid agent to the inner surface 104, and allows the coating 94 to be formed effectively.

[0078] In the above description, when terms such as "vertical," "parallel," and "plane" are used, the terms are not used in their strict sense. In other words, "vertical," "parallel," and "plane" mean "substantially vertical," "substantially parallel," and "substantially plane," allowing for design and manufacturing tolerances and errors.

[0079] In addition, in the above description, when the external dimensions or sizes are described as "same", "equal", "different", etc., the description does not mean in the strict sense. In other words, "same", "equal", and "different" mean "substantially the same", "substantially equal", and "substantially different", allowing for design and manufacturing tolerances and errors.

[0080] However, when there is a description of a value that serves as a specific judgment criterion or a dividing line, such as a threshold value or a reference value, the terms "same," "equal," "different," etc., used in relation to such a value are used in the strict sense, different from the above.

[0081] In addition to the above, the methods according to the above embodiments and their modifications may be used in appropriate combination.

[0082] Although not specifically illustrated, the present invention can be implemented with various modifications without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0083] 1 Film forming device 2. Medium gas storage section 3 Inflow pump 4 Inlet Adapter 5 Liquid storage section 6 Spray Pump 7 Spray nozzle 8 Suction adapter 9. Suction Pump 10. Suction gas storage section 11 Control section 12 Control section 13 Reducer 14 Turntable (equivalent to workpiece placement table) 16 Inlet / suction adapter (corresponding to the first and second flow sections) 17 3-way valve 19. Vibration section 20 Field ring 22 Field power supply 23 Field coil 24 Field coil 91 Medium gas 92 Liquid 93 Gas Mixtures 94 Coating 95 Pinhole 100 Pipe (equivalent to work) 101 Open end on one side (corresponding to the first opening end) 102 Open end on the other side (corresponding to the second opening end) 103 Communication hole 104 Inner surface 110 Heat exchanger (equivalent to the work) Medium motor

Claims

1. A coating forming apparatus for forming a coating on an inner surface of a workpiece having a communication hole therein that communicates between a first opening end and a second opening end by applying a predetermined liquid agent to the inner surface of the communication hole, A calculation unit included in the coating forming apparatus, a first suction start step of starting to suction gas from within the communication hole from the second opening end side; a first flow-initiating step of initiating pressurization and flow of a predetermined medium gas into the communication hole from the first opening end side; a first spray start step of starting spraying a mixed gas obtained by mixing the predetermined liquid agent into the predetermined medium gas from the first opening end side into the communication hole; a first spray stopping step of stopping spraying; a first suction and inflow stop step of stopping the suction and inflow; a second suction start step of starting suction of gas in the communication hole from the first opening end side; a second flow-initiating step of starting pressurization and flow of the predetermined medium gas into the communication hole from the second opening end side; a second spray start step of starting spraying the mixed gas from the second opening end side into the communication hole; a second spray stopping step of stopping spraying; a second suction and inflow stop step of stopping the suction and inflow; In a coating forming apparatus which sequentially performs the above steps, A coating forming apparatus comprising a field magnet part which applies a field magnet to the workpiece from the outside, the field magnet part being capable of changing at least one of a polarity direction of the field magnet and a field magnet position.

2. A coating forming apparatus as described in claim 1, comprising a vibration unit that applies vibrations to the workpiece from outside.

3. a workpiece setting table that fixes the workpiece and changes the posture of the workpiece so that the first opening end and the second opening end are interchangeable; 2. The coating forming apparatus according to claim 1, further comprising:

4. a first circulating portion capable of selectively performing, with respect to the first opening end, a suction of gas in the communication hole, a pressurization and inflow of the predetermined medium gas into the communication hole, and a spray of the liquid agent into the communication hole; a second circulating portion capable of selectively performing, with respect to the second opening end, a suction of gas in the communication hole, a pressurization and inflow of the predetermined medium gas into the communication hole, and a spray of the liquid agent into the communication hole; 2. The coating forming apparatus according to claim 1, further comprising:

5. In the coating forming apparatus, a suction and inflow continuing step of continuing the suction and inflow for a predetermined time or more at least one of between the first spray stopping step and the first suction and inflow stopping step and between the second spray stopping step and the second suction and inflow stopping step; 2. The coating forming apparatus according to claim 1, further comprising:

6. 2. The coating forming apparatus according to claim 1, wherein the medium gas is dry air having a temperature of 5 to 30.degree.

7. A method for manufacturing a heat exchanger having an internal communication hole connecting a first opening end and a second opening end, in which a coating is formed by applying a predetermined liquid agent to the inner surface of the communication hole using a coating forming apparatus described in any one of claims 1 to 6.

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