Flow impregnation apparatus

Abstract

To suppress the variation of a coating boundary without the need for complicated data collection for a fluidization immersion device 1.SOLUTION: A device 1 includes the following operation body 7. That is, the operation body 7 is immersed in a fluidized layer 4 and driven to sweep an upper side surface 3a of a porous wall 3. Then, the device 1 performs coating by immersing a workpiece 2 in the fluidized layer 4 so that a portion is exposed to the air while driving the operation body 7. As a result, since it is possible to reduce bubbles that burst on an upper surface 4a of the fluidized layer 4, it is possible to suppress the variation of a coating boundary by reducing the fluctuation of the upper surface 4a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a fluidized bed coating apparatus for coating a workpiece by a fluidized bed coating method. [Background technology]

[0002] A fluidized bed coating method has been known for some time, in which a fluidized bed of powder paint is formed by ejecting gas upward from a porous wall made of a porous material, and a preheated workpiece is immersed in the fluidized bed of powder paint to be coated. This method is used, for example, to paint rotors and stators of automobile motors.

[0003] Furthermore, in such applications, there is a demand for coating only one side of a specific boundary line on the workpiece surface (hereinafter, this boundary line may be referred to as the coating boundary.) To establish the coating boundary, one possible method is to immerse the workpiece in the fluidized bed so that a part of it is exposed to the air, and then coat the upper surface of the fluidized bed, i.e., the part immersed below the solid-gas interface. However, the top surface of the fluidized bed is constantly fluctuating due to the bursting of gas bubbles, so simply immersing a workpiece in the fluidized bed so that part of it is exposed to the air results in large variations in the position of the coating boundary for each workpiece.

[0004] Therefore, various methods have been devised to reduce such variations (see, for example, Patent Documents 1 and 2). First, according to Patent Document 1, a fluidized bed immersion apparatus is equipped with a vibration mechanism that vibrates the fluidized bed. Then, the particle size of the powder that forms the fluidized bed is estimated, and the frequency of the vibration applied to the fluidized bed from the vibration mechanism is calculated based on the estimated particle size, and the fluidized bed is vibrated at the calculated frequency. This makes it possible to suppress fluctuations in the upper surface of the fluidized bed.

[0005] According to Patent Document 2, the fluidized bed immersion apparatus is equipped with the following inner cylinder. That is, the inner cylinder is held so that the solid-gas interface on its inner periphery is elevated above the upper surface of the fluidized bed, and the powder overflows from the upper opening of the inner cylinder. This allows the formation of a solid-gas interface at the upper opening that is less susceptible to fluctuation than the upper surface of the fluidized bed.

[0006] However, with the fluidized bed immersion apparatus of Patent Document 1, it is necessary to measure the vibration frequency at which the upper surface of the fluidized bed becomes stable for each particle size of the powder and collect data, and such data collection must be performed for various factors such as the type of powder and the shape of the inner wall that forms the fluidized bed. Furthermore, according to the fluidized bed immersion apparatus of Patent Document 2, the fluctuation of the solid-gas interface formed at the upper opening of the inner cylinder is suppressed as it rises higher above the upper surface of the fluidized bed.

[0007] However, since the fluidity is thought to worsen as the container is raised, it is necessary to provide a mechanism that makes it easier for the gas to be blown out toward the inner circumference of the inner cylinder. Furthermore, the introduction of such a mechanism increases the fluctuation of the solid-gas interface on the inner circumference of the inner cylinder, making it difficult to effectively suppress the variation in the coating boundary. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2019-084514 [Patent Document 2] Japanese Patent Application Publication No. 2019-093338 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, an object of the present disclosure is to suppress variations in the coating boundary in a fluidized bed immersion device without requiring cumbersome data collection. [Means for solving the problem]

[0010] The fluidized immersion apparatus of the present disclosure comprises the following storage container and fluidizing means. The storage container has a storage space for storing powder paint, and the bottom side of the storage space is partitioned by a porous wall made of a porous material. The fluidizing means sprays gas upward from the porous wall to form a fluidized layer of powder paint in the storage space. The fluidized bed immersion device then immerses the workpiece as the coating object into the fluidized bed to coat it.

[0011] The fluidized bed immersion device is also , and the driven body That is, the working body is driven to be immersed in the fluidized bed and to sweep the upper surface of the porous wall. The driven body has an operating body attached thereto and is driven to rotate about an axis perpendicular to the upper surface of the porous wall. The fluidized bed immersion device then drives the moving body to immerse the workpiece in the fluidized bed so that a portion of the workpiece is exposed to the air, thereby coating the workpiece. The working body also sweeps the upper surface of the porous wall by rotating around the central axis. As described above, the fluidized bed immersion apparatus of the present disclosure can suppress variations in the coating boundary without requiring complicated data collection. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is an explanatory diagram showing the overall configuration of a fluidized bed immersion apparatus. [Figure 2] FIG. 2 is a plan view of the fluidized bed immersion apparatus. [Figure 3] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, the mode for carrying out the invention will be described based on examples. Note that the examples disclose specific examples, and it goes without saying that the present invention is not limited to the examples. [Example]

[0014] [Configuration of the Example] A fluidized bed immersion apparatus 1 according to an embodiment will be described with reference to the drawings (hereinafter, the fluidized bed immersion apparatus 1 may be abbreviated to apparatus 1). First, the apparatus 1 is used to coat a workpiece 2 as a coating object by the fluidized bed method. That is, in the apparatus 1, a fluidized bed 4 of powder paint is formed by ejecting gas upward from a porous wall 3 made of a porous material, and the preheated workpiece 2 is immersed in the fluidized bed 4 to be coated. The workpiece 2 is, for example, a rotor or stator of an automobile motor. The device 1 will now be described in detail.

[0015] The device 1 includes a storage container 5, a flow means 6, a driving body 7, and a driven body 8 as follows. First, the storage container 5 has a storage space 5a for storing powder paint, and the bottom side of the storage space 5a is partitioned by a porous wall 3 (hereinafter, the storage container 5 may be referred to as a tank 5). Here, the tank 5 has a tubular portion 5b having a cylindrical inner circumferential space, and a flange portion 5c provided at the lower end of the tubular portion 5b, and the inner circumferential space of the tubular portion 5b forms the storage space 5a.

[0016] The bottomed container 9 has a cylindrical inner circumferential space with the same diameter as the inner circumferential space of the tubular portion 5b, and has a flange portion 9a at its upper end. The tank 5 and the bottomed container 9 are firmly fastened together with the porous wall 3 sandwiched between the flange portions 5c and 9a by fastening a predetermined fastener 10 with the porous wall 3 sandwiched between them. The porous wall 3 is made of a porous plate or glass wool woven fabric, etc., and allows gas to pass up and down without allowing powder paint to pass underneath, and is supported so as not to sag due to the weight of the powder paint.

[0017] As a result, the space formed by the porous wall 3 and the bottomed container 9 forms a gas chamber 11 in which gas mainly flows. The inner space of the cylindrical portion 5b and the inner space of the bottomed container 9 are arranged coaxially, and the upper and lower surfaces of the porous wall 3 form circular exposed surfaces to the storage space 5a and the gas chamber 11, respectively (hereinafter, the upper surface of the porous wall 3 may be referred to as the upper surface 3a).

[0018] Next, the fluidization means 6 sprays gas upward from the porous wall 3 to form a fluidized layer 4 of powder paint in the storage space 5a, and the device 1 immerses the preheated workpiece 2 in the fluidized layer 4 to coat it. Specifically, the flow means 6 comprises a well-known air supply unit 6a which is composed of an air compressor, an air filter, a valve, etc., a pipe 6b which connects the air supply unit 6a to the gas chamber 11, and the above-mentioned gas chamber 11, etc.

[0019] Next, the moving body 7 is immersed in the fluidized bed 4 and driven to sweep the upper surface 3a of the porous wall 3. Then, while driving the moving body 7, the device 1 immerses the workpiece 2 in the fluidized bed 4 so that a portion of the workpiece 2 is exposed to the air, and coats it. Furthermore, the driven body 8 has an operating body 7 attached thereto, and is driven to rotate about a central axis α that is perpendicular to the upper surface 3a of the porous wall 3 (hereinafter, the driven body 8 may be referred to as a rotating table 8). The operating body 7 sweeps the upper surface 3a of the porous wall 3 by rotating around the central axis α. The rotating table 8 is provided in an annular shape, and the operating body 7 is attached so as to extend below and toward the inner periphery of the rotating table 8, and is immersed in the fluidized bed 4.

[0020] The operating body 7 and the rotating table 8 will be described in detail below. First, the operating body 7 has the following opposing portion 7a and sidewall portion 7b. That is, the opposing portion 7a is a portion that faces the upper surface 3a of the porous wall 3, and the sidewall portion 7b extends upward from the opposing portion 7a along the inner circumferential surface of the cylindrical portion 5b. Then, the workpiece 2 is inserted from above into the inner periphery of the rotating body formed by the rotation of the opposing portion 7a and the sidewall portion 7b, and is immersed in the fluidized bed 4. In addition, a fastening piece 7c that is screwed to the rotating table 8 is provided at the upper end of the sidewall portion 7b.

[0021] More specifically, the facing portion 7a and the sidewall portion 7b of the operating body 7 are made of, for example, a flush metal plate, and appear L-shaped when viewed perpendicularly to the surface. When viewed from above, the facing portion 7a and the sidewall portion 7b have a radial direction. A predetermined clearance is formed between the lower edge of the facing portion 7a and the outer peripheral edge of the sidewall portion 7b and the upper surface 3a of the porous wall 3 and the inner peripheral surface of the cylindrical portion 5b, respectively.

[0022] The inner periphery of the rotor formed by the rotation of the facing portion 7a and the sidewall portion 7b is cylindrical. Furthermore, the length of the facing portion 7a is slightly longer than the radius of the inner circumferential space of the cylindrical portion 5b, i.e., the radius of the upper surface 3a. Furthermore, the central axis α of rotation of the turntable 8 substantially coincides with the central axes of the inner circumferential space of the cylindrical portion 5b and the inner circumferential space of the bottomed container 9.

[0023] The rotating table 8 also has a base portion 8a to which the fastening piece 7c is screwed and a pulley 8c around which a drive belt 8b is stretched, and is driven to rotate via the drive belt 8b by a drive portion 12 arranged on the outer periphery of the rotating table 8. Here, a bearing 13 is provided between the lower end of the base portion 8a and the upper end of the tank 5, and the rotating base 8 is supported by the tank 5 so as to be freely rotatable.

[0024] The drive unit 12 is composed of a pulley 12a around which a drive belt 8b is wound, and a motor 12b that rotates and drives the pulley 12a. The bearings 13 are formed by providing a circumferential groove at the bottom end of the base 8a and at the top end of the tank 5 so as to surround the central axis α, and arranging a sphere in the groove, with the groove shaped to restrict circumferential movement of the sphere. The base 8a is further provided with a plurality of screw holes 8d at equal angular intervals that can be used to fasten the fastening pieces 7c.

[0025] [Operation of the embodiment] The operation of the device 1 of the embodiment will be described. With powder paint stored in the tank 5, the air supply unit 6a is operated to form a fluidized layer 4 of powder paint. In this state, the drive unit 12 is operated to rotate the turntable 8 and the moving body 7. Thereafter, the preheated workpiece 2 is lowered into the fluidized layer 4 on the inner periphery of the rotating body, which is formed by the rotation of the opposing portion 7a and the sidewall portion 7b, and is immersed so that a part of the workpiece 2 is exposed to the air.

[0026] [Effects of the Example] The device 1 of the embodiment includes a tank 5 and a flow means 6 as follows. First, the tank 5 has a storage space 5a for storing powder paint, and the bottom side of the storage space 5a is partitioned by a porous wall 3. Next, the fluidizing means 6 forms a fluidized layer 4 of powder paint in the storage space 5a by ejecting gas upward from the porous wall 3. Then, the device 1 immerses the workpiece 2 in the fluidized layer 4 to coat it.

[0027] The apparatus 1 also includes the following operating body 7. That is, the operating body 7 is immersed in the fluidized bed 4 and driven to sweep the upper surface 3a of the porous wall 3. While driving the operating body 7, the apparatus 1 coats the workpiece 2 by immersing it in the fluidized bed 4 so that a portion of the workpiece 2 is exposed to the air. As a result, the device 1 of the embodiment can reduce fluctuations in the upper surface 4a of the fluidized bed 4 and suppress variations in the coating boundary without requiring complicated data collection.

[0028] Here, the reason why fluctuations in the upper surface 4a can be reduced is not clear, but it is assumed as follows. That is, the upper surface 4a fluctuates due to the bursting of gas bubbles. It is thought that in the device 1, in response to the bursting of bubbles on the upper surface 4a, the operating body 7 sweeps the upper surface 3a of the porous wall 3, thereby making the bubbles finer and preventing them from coalescing and becoming larger. As a result, the bubbles that burst on the upper surface 4a can be made smaller, thereby reducing fluctuations in the upper surface 4a and suppressing variations in the coating boundary.

[0029] The device 1 also includes a rotating table 8. The rotating table 8 has a moving body 7 attached thereto and is driven to rotate about a central axis α that is perpendicular to the upper surface 3a of the porous wall 3. The moving body 7 sweeps the upper surface 3a of the porous wall 3 by rotating around the central axis α. This allows the upper surface 3 a of the porous wall 3 to be swept by the rotation of the operating body 7 .

[0030] The rotating table 8 is provided in an annular shape, and the moving body 7 is attached so as to extend below and toward the inner periphery of the rotating table 8 and is immersed in the fluidized bed 4. As a result, the turntable 8 is rotated and the upper surface 3a of the porous wall 3 is swept by the operating body 7, while the workpiece 2 is immersed from above in the area below and on the inner periphery of the turntable 8.

[0031] Furthermore, the storage space 5a is cylindrical, and the operating body 7 has the following opposing portion 7a and sidewall portion 7b. That is, the opposing portion 7a is a portion that faces the upper surface 3a of the porous wall 3, and the sidewall portion 7b is a portion that extends upward from the opposing portion 7a along the inner circumferential surface that forms the storage space 5a. The workpiece 2 is inserted from above into the inner periphery of the rotating body formed by the rotation of the opposing portion 7a and sidewall portion 7b, and is immersed in the fluidized bed 4. This allows the inner periphery of the passage area caused by the rotation of the facing portion 7a and the sidewall portion 7b to be widened, so that the area in the fluidized bed 4 where the workpiece 2 can be immersed can be expanded.

[0032] [Modification] The present invention can be modified in various ways without departing from the spirit of the invention. For example, according to the device 1 of the embodiment, the turntable 8 is rotated by the motor 12b via the drive belt 8b, but the manner of rotating the turntable 8 is not limited to this. For example, the turntable 8 may be provided with externally toothed gears, and the turntable 8 may be rotated by the meshing of the gears.

[0033] Furthermore, according to the device 1 of the embodiment, only one operating body 7 is screwed to the base portion 8a, but a plurality of operating bodies 7 may be screwed to the base portion 8a. Furthermore, according to the device 1 of the embodiment, the upper surface 3a of the porous wall 3 is swept by rotating the moving body 7, but for example, if the upper surface 3a is rectangular, the upper surface 3a may be swept by moving the moving body 7 in a straight line. [Explanation of symbols]

[0034] REFERENCE SIGNS LIST 1 Apparatus (fluidized immersion apparatus) 2 Workpiece 5a Storage space 3 Perforated wall 3a Upper surface 4 Fluidized bed 5 Tank (storage vessel) 6 Flow means 7 Operating body

Claims

1. a storage container having a storage space for storing powder paint, the bottom side of the storage space being partitioned by a porous wall made of a porous material; a fluidizing means for forming a fluidized layer of the powder paint in the storage space by ejecting gas upward from the porous wall, In a fluidized bed immersion apparatus in which a workpiece as a coating object is immersed in the fluidized bed to be coated, a moving body that is immersed in the fluidized bed and driven to sweep the upper surface of the porous wall; a driven body to which the operating body is attached and which is rotationally driven about an axis perpendicular to the upper surface of the porous wall, While driving the moving body, the workpiece is immersed in the fluidized bed so that a portion of the workpiece is exposed to the air, and is then coated; The fluidized bed immersion apparatus is characterized in that the moving body sweeps the upper surface of the porous wall by rotating around the central axis.

2. The fluidized bed immersion apparatus according to claim 1, the driven body is provided in an annular shape, The fluidized bed immersion apparatus is characterized in that the operating body is attached so as to extend to the inner periphery and below the driven body and is immersed in the fluidized bed.

3. The fluidized bed immersion apparatus according to claim 2, The storage space is cylindrical; The operating body has a facing portion facing the upper surface of the porous wall and a side wall portion extending upward from the facing portion along an inner circumferential surface that forms the storage space, A fluidized bed immersion apparatus characterized in that the workpiece is inserted from above into the inner periphery of a rotating body formed by the rotation of the opposing portion and the sidewall portion, and is immersed in the fluidized bed.

Images