JP2022157798A - Rotary bell cup coater - Google Patents

Abstract

To realize micronization and uniformization of coating particle sizes in a rotary bell cup coater.SOLUTION: A rotary bell cup coater 1 includes: a feed tube 22 for ejecting a coating material; a bell cup 3; and a bell hub 5 which receives the coating material ejected from the feed tube 22. The bell cup 3 has a first inner peripheral surface 33a extending along a central axis C direction and surrounding the bell hub 5, and a second inner peripheral surface 33b which is provided on a tip side relative to the first inner peripheral surface 33a, and whose diameter expands toward the tip side. The bell hub 5 has an end surface 53 discharging the coating material ejected from the feed tube 22 toward the bell cup 3, when rotating about the central axis C together with the bell cup 3, and an extension line Le extended outward from this end surface 53 intersects with a base end side portion 33R at the time the first inner peripheral surface 33a along the central axis C direction is divided into the base end side portion 33R and a tip side portion 33T.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The technology disclosed herein relates to a rotary bell cup coating machine.

Patent Document 1 discloses, as an example of a rotary bell cup coating machine, a rotating shaft into which a feed tube is inserted, a bell cup (rotary atomizing head) attached to the tip of the rotating shaft, and a center of the proximal end of the bell cup. A rotary atomizing head coating apparatus is disclosed that includes a bell hub (hub member) mounted on a . The bell hub according to this document is formed in a disc shape with a conical protrusion at the center thereof, and is oriented with the protrusion facing the feed tube side.

The bell hub disclosed in Patent Document 1 has a plurality of legs and a plurality of notch grooves on its outer peripheral portion. Each notch groove is formed alternately with each leg portion, and when fitted into a groove (hub fitting groove) provided on the bell cup, a plurality of hole-like grooves are formed between the groove and the groove. Form a paint passage. The paint discharged to the inner bottom surface of the bell hub is guided to the inner peripheral surface of the bell cup through the perforated paint passages, and the granulated paint particles are discharged from the inner peripheral surface of the bell cup. is configured as follows.

JP-A-2002-224593

When a bell hub such as that disclosed in Patent Document 1 is used, in the process in which the paint discharged from the feed tube flows on the inner surface of the bell hub, the paint collides with the inner surface of the bell hub, and the paint that collides with the inner surface of the bell hub. eccentricity with respect to the rotating shaft, obstruction of flow due to obstacles such as legs disclosed in the above-mentioned Patent Document 1, and collisions when transferring from the bell hub to the bell cup. may stand. The rippling of the paint is not desirable in terms of miniaturization and uniformity of the paint particle size.

The technology disclosed herein has been made in view of the above points, and its purpose is to realize finer and more uniform paint particle diameters in a rotary bell cup coating machine.

The technology disclosed herein relates to a rotary bell cup coating machine that ejects centrifugally atomized coating particles. This rotary bell cup coating machine includes a paint supply pipe for discharging paint from a tip, a bell cup provided so as to surround the tip of the paint supply pipe and rotating around the central axis of the paint supply pipe, and the paint supply. a paint receiving member that faces the tip of the pipe and receives the paint discharged from the tip, wherein the bell cup extends along the central axis direction and surrounds the paint receiving member; and a second inner peripheral surface provided on the tip end side of the first inner peripheral surface and having a diameter increasing toward the tip end side, and the paint receiving member has a It has an end face that discharges the paint discharged from the paint supply pipe toward the bell cup when it rotates around the central axis together with the bell cup.

The extension line extending outward from the end surface is the proximal side portion when the first inner peripheral surface is divided into a proximal side portion and a distal side portion along the central axis direction. intersect with

Here, the term "extending along the central axis direction" also includes a structure extending slightly inclined with respect to the central axis direction.

As a result of extensive studies, the inventors of the present application have found that when a conventional bell hub is used, the liquid film flow on the inner surface of the bell hub is uneven due to the eccentricity of the paint that collides with the inner surface of the paint receiving member with respect to the rotating shaft. As a result, it was found that this caused the ripples of the liquid film on the inner surface of the bell cup, and that the ripples of the liquid film were caused by the connecting structure of the bell hub with legs and the like.

On the other hand, according to the above configuration, the paint flying from the end face of the paint receiving member flows through the first inner peripheral surface and the second inner peripheral surface in order. According to the knowledge obtained by the inventors of the present application, by causing the paint to flow along the first inner peripheral surface extending in the direction of the central axis, the influence of the eccentricity as described above can be reduced, and the liquid film of the paint can be reduced. can be made uniform. As a result, ripples in the liquid film of the paint can be suppressed.

Furthermore, according to the above configuration, the paint flying from the end surface of the paint receiving member reaches the base end side portion of the first inner peripheral surface. By doing so, the paint that has reached the first inner peripheral surface flows not only to the tip side portion but also to the base end side portion. As a result, the flow distance when flowing on the first inner peripheral surface can be made longer, and ripples in the coating liquid film can be more reliably suppressed.

Thus, according to the above configuration, it is possible to suppress the ripples of the coating liquid film, and eventually to achieve finer and more uniform coating particle diameters.

Further, when the inclination angle of the first inner peripheral surface with respect to the central axis direction is θc,
0°≦θc≦20°
It may be assumed that the relationship of is satisfied.

According to this configuration, by configuring the first inner peripheral surface so as to satisfy the above relationship, it is possible to more reliably suppress ripples in the coating liquid film.

In addition, the paint receiving member has a concave cross-sectional shape facing the paint supply pipe, and the paint receiving member includes an inner bottom surface facing the paint supply pipe, and an inner bottom surface facing the end surface from the inner bottom surface. the paint receiving member rotates about the central axis together with the bell cup, so that the paint discharged from the paint supply pipe toward the inner bottom surface moves to the inner circumference. It may be configured to reach the inner peripheral surface of the bell cup through the surface and the end surface.

According to this configuration, the paint discharged to the paint receiving member flows along the inner bottom surface and the inner peripheral surface before reaching the bell cup. According to the knowledge obtained by the inventors of the present application, in addition to receiving the paint on the inner bottom surface of the member formed with a concave cross section, by allowing the paint to flow along the inner peripheral surface, the unevenness described above can be achieved. The effect of the core can be reduced and the thickness of the coating liquid film can be made uniform. As a result, ripples in the coating liquid film can be suppressed.

In addition, by suppressing the waving of the paint in advance before the paint is transferred from the paint receiving member to the bell cup, even if the impact of the collision when transferring from the paint receiving member to the bell cup is taken into consideration, the paint liquid can be reduced. The thickness of the membrane can be kept as uniform as possible. This is advantageous in achieving finer and more uniform paint particle sizes.

Further, the rotary bell cup coating machine includes a connector that is provided on the inner peripheral surface and that connects the bell cup and the paint receiving member, and the connector is configured to extend from the inner peripheral surface in the circumferential direction around the central axis. It may be provided on a part of the surface.

Here, the connector may indirectly connect the bell cup and the paint receiving member via another member, or may directly connect the bell cup and the paint receiving member without another member.

According to this configuration, the paint flowing along the inner bottom surface becomes a diffusion flow due to the centrifugal force caused by the rotation of the paint receiving member. On the other hand, the paint that flows along the inner peripheral surface flows substantially parallel to the central axis, which is a so-called parallel flow. According to the knowledge obtained by the inventors of the present application, the parallel flow is less affected by obstacles than the diffusive flow. Therefore, by providing the connector on the inner peripheral surface instead of the inner bottom surface, the influence of the connector as an obstacle on the flow is suppressed, and in turn, it is advantageous in realizing finer and uniform paint particle diameters. Become.

Further, the outer peripheral portion of the paint receiving member on the side of the end face may be formed so as to taper outward in the radial direction.

The term “radial direction” as used herein refers to a direction extending perpendicularly and radially from the central axis.

According to this configuration, the paint that is about to transfer from the paint receiving member to the bell cup flies from the outer circumference of the end face side of the paint receiving member to the bell cup. The paint will fly from the tip of the affected part. This causes the paint to fly from a specific portion of the outer periphery. As a result, the flow distance of the paint is kept substantially constant, which is advantageous in achieving finer and uniform paint particle diameters. Further, by forming the outer peripheral portion on the end face side to be tapered, it is possible to suppress the wraparound of the coating material to the coating material receiving member due to the surface tension. This also works effectively to achieve finer and more uniform paint particle sizes.

Further, the inner peripheral surface may extend away from the central axis from the inner bottom surface toward the end surface.

According to this configuration, the paint on the inner peripheral surface can be caused to flow from the inner bottom surface side to the end surface side by the centrifugal force caused by the rotation of the paint receiving member. As a result, for example, it is possible to prevent the paint from remaining in the vicinity of the corners where the inner bottom surface and the inner peripheral surface intersect, thereby improving the usability of the rotary bell cup coating machine. This is particularly effective when painting while changing a plurality of types of paint.

The rotary bell cup coating machine includes a rotating shaft into which the paint supply pipe is inserted and which rotates integrally with the bell cup; The paint receiving member is formed in a bottomed cylindrical shape with an opening facing the tip of the paint supply pipe, and the paint receiving member is connected to the support. It may also rotate integrally with the bell cup via the support.

According to this configuration, it is possible to provide a rotary bell cup coating machine according to the present disclosure.

As described above, according to the rotary bell cup coating machine, it is possible to achieve finer and more uniform coating particle diameters.

FIG. 1 is a vertical cross-sectional view illustrating the tip of a rotary bell cup coating machine. FIG. 2 is a longitudinal sectional view illustrating the configuration of the bell cup. FIG. 3 is a cross-sectional view illustrating the tip of the rotary bell cup coater. FIG. 4 is a perspective view illustrating the configuration of the bell hub. FIG. 5 is a diagram illustrating the flow of paint in a rotary bell cup coater. 6A and 6B are explanatory diagrams showing a comparison of influences on the flow by the coupler. FIG. 7 is a view corresponding to FIG. 1 showing a conventional rotary bell cup coating machine. FIG. 8 is a diagram illustrating the flow of paint in a conventional example. FIG. 9 is a diagram corresponding to FIG. 1 showing a modification of the rotary bell cup coating machine. FIG. 10 is a diagram illustrating the flow of paint in a modified example.

Hereinafter, embodiments of the present disclosure will be described based on the drawings. Note that the following description is an example.

(Configuration of rotary bell cup coating machine)
FIG. 1 is a longitudinal sectional view illustrating the tip of a rotary bell cup coating machine 1, and FIG. 2 is a longitudinal sectional view illustrating the configuration of the bell cup 3. As shown in FIG. Furthermore, FIG. 3 is a cross-sectional view illustrating the tip portion of the rotary bell cup coating machine 1. As shown in FIG. Furthermore, FIG. 4 is a perspective view illustrating the configuration of the bell hub 5. As shown in FIG. 1 is a cross section along the central axis C of the rotary bell cup coating machine 1, and FIG. 3 corresponds to the AA cross section in FIG.

In the following description, the term “base end” refers to the side of the feed tube 22 (opposite side of the object to be coated) in the direction of the central axis C, and the term “distal side” refers to the side opposite to the feed tube 22 in the same direction. It refers to the side (the side of the object to be coated). Further, in the following description, "radial direction" refers to a direction orthogonal to the central axis C and radially extending from the central axis C, and "circumferential direction" refers to a direction orthogonal to the radial direction and extending radially from the central axis C. refers to the direction that circulates around the

A rotary bell cup coating machine 1 shown in FIG. 1 and the like is a rotary atomizing coating device for electrostatic coating, and is configured to discharge centrifugally atomized coating particles. That is, the rotary bell cup coating machine 1 sprays and atomizes paint by centrifugal force from a bell cup 3 attached to a rotating shaft 21 that rotates at high speed, and also sprays negatively charged paint particles and positively charged paint particles. Painting is performed by utilizing the attractive force acting between the object to be painted, such as the body of an automobile.

Specifically, the rotary bell cup coating machine 1 includes a cylindrical housing 10, a tubular member 2 inserted into the housing 10 and discharging paint from the tip, and a feed tube 22 in the tubular member 2 so as to surround the tip 22a. a bell cup 3 that rotates around the central axis C of the feed tube 22; a bell hub 5 that faces the tip 22a of the feed tube 22 and receives the paint discharged from the tip 22a; and a support 4 for mounting 5.

Among them, the housing 10 is formed in a cylindrical shape. A housing 10 accommodates the tubular member 2 and a high voltage power supply (not shown) for electrifying paint. A proximal end of the bell cup 3 is inserted into an opening 10a provided at the distal end of the housing 10. As shown in FIG. Although not shown, air can be discharged from the tip of the housing 10 to deflect the paint particles.

Further, the tubular member 2 has a rotating shaft 21 that rotates integrally with the bell cup 3, and a feed tube 22 that is inserted into the rotating shaft 21 and discharges paint from its tip. The feed tube 22 is an example of the "paint supply tube" in this embodiment.

Among them, the rotating shaft 21 is configured as a hollow shaft member and is inserted into a tubular portion 31 on the base end side of the bell cup 3 . The rotating shaft 21 is configured to receive power from the outside and rotate around the central axis C, and rotate integrally with the bell cup 3 via the cylindrical portion 31 .

The feed tube 22 is configured as a tube-shaped member for circulating the paint, and is inserted into the rotary shaft 21 . A distal end 22 a of the feed tube 22 is configured as an open end capable of discharging paint, and is exposed from the rotating shaft 21 . The feed tube 22 according to the present embodiment circulates the paint from one side (opposite side of the article to be coated) in the direction of the central axis C to the other side (the side of the article to be coated S), and discharges the paint from the tip 22a. It's like The paint discharged from the tip end 22 a collides with the inner bottom surface 51 of the bell hub 5 .

The bell cup 3 has a substantially cup shape as shown in FIG. The bell cup 3 has a tubular portion 31 on the proximal side and a tapered portion 32 on the distal end side.

Among them, the cylindrical portion 31 is formed in a short cylindrical shape extending along the direction of the central axis C, and the rotating shaft 21 is inserted from the base end side, and at the same time, the support 4 is inserted from the distal end side. there is A contacted portion 31 a that protrudes radially inward is provided on the inner peripheral surface of the cylindrical portion 31 . The abutted portion 31 a is configured to position the support 4 by coming into contact with the support 4 inserted into the cylindrical portion 31 .

Among the inner peripheral surfaces of the cylindrical portion 31, a first inner peripheral surface 33a on the tip side of the abutted portion 31a is configured so that paint scattered from the bell hub 5 by centrifugal force flows. The first inner peripheral surface 33a constitutes a paint diffusion surface 33 for diffusing the paint together with a second inner peripheral surface 33b, which will be described later.

Specifically, the first inner peripheral surface 33 a of the bell cup 3 is configured to extend along the central axis C direction and surround at least the bell hub 5 . Specifically, the first inner peripheral surface 33a is slightly inclined with respect to the direction of the central axis C, and gradually expands in diameter toward the distal end side. The first inner peripheral surface 33a includes the tip of the tubular member 2 (specifically, the tip 22a of the feed tube 22), the support 4, and the bell hub 5 (specifically, an inner peripheral surface 52 and an end surface 53 described later). ) and surround the . That is, when viewed along a direction (radial direction) perpendicular to the central axis C, the first inner peripheral surface 33a is the inner peripheral surface 52 and the end surface 53 of the feed tube 22, the support 4, and the bell hub 5. overlap with

More specifically, when the inclination angle of the first inner peripheral surface 33a with respect to the direction of the central axis C is θc, the relationship of preferably 0°≦θc≦20°, more preferably 0°≦θc≦5° is satisfied. be done.

The tapered portion 32 tapers and expands in diameter toward the distal end side. The inner peripheral surface of the tapered portion 32 forms a second inner peripheral surface 33b through which the paint that has passed through the first inner peripheral surface 33a flows. The second inner peripheral surface 33b constitutes the paint diffusion surface 33 together with the first inner peripheral surface 33a.

Specifically, the second inner peripheral surface 33b of the bell cup 3 is provided closer to the distal end than the first inner peripheral surface 33a, and the diameter of the second inner peripheral surface 33b increases toward the distal end. The second inner peripheral surface 33b does not overlap the inner peripheral surfaces 52 and end surfaces 53 of the feed tube 22, the support 4 and the bell hub 5 when viewed along the radial direction.

Further, the support 4 is arranged on the tip 22a side of the feed tube 22 and inserted into the inner peripheral side of the bell cup 3 . Specifically, the support 4 according to the present embodiment is formed in a tubular shape extending in the direction of the central axis C, and the tubular portion 31 of the bell cup 3 is inserted into the tubular portion 31 of the bell cup 3 with the tip 22a of the feed tube 22 inserted therethrough. is inserted in the That is, the inner diameter of the support 4 is larger than the tip 22 a of the feed tube 22 , and the outer diameter of the support 4 is smaller than the cylindrical portion 31 .

Furthermore, the outer surface of the support 4 is provided with a flange portion 4a projecting like a flange. When the support 4 is inserted into the cylindrical portion 31 and pushed in, the collar portion 4 a of the support 4 contacts the contacted portion 31 a of the cylindrical portion 31 . Thereby, the support 4 is positioned with respect to the bell cup 3 , particularly the cylindrical portion 31 .

The bell hub 5 is provided on the inner peripheral side of the bell cup 3 , and is arranged in a posture facing the feed tube 22 . The bell hub 5 has a concave cross section. Specifically, the bell hub 5 has an inner bottom surface 51 facing the feed tube 22 , an end surface 53 facing the feed tube 22 side, and an inner peripheral surface 52 extending from the inner bottom surface 51 toward the end surface 53 . there is The bell hub 5 is an example of the "paint receiving member" in this embodiment.

Specifically, the bell hub 5 according to the present embodiment is formed in a bottomed cylindrical shape with an opening and an inner bottom surface 51 facing the distal end 22a of the feed tube 22. A circular inner bottom surface 51 and a substantially cylindrical It has an inner peripheral surface 52 and an end surface 53 corresponding to the opening edge of the bell hub 5 . The bell hub 5 is connected to the support 4 via a connector 6 which will be described later, and rotates integrally with the bell cup 3 via the support 4 .

Among them, the inner bottom surface 51 is formed as a circular plane, and is perpendicular to the central axis C and the central portion of the inner bottom surface 51 (the portion corresponding to the center when the inner bottom surface 51 is regarded as a circle). ) is arranged to face the tip 22 a of the feed tube 22 . With this arrangement, the paint discharged from the feed tube 22 collides with the central portion of the inner bottom surface 51 .

Subsequently, the inner peripheral surface 52 is formed as a substantially cylindrical curved surface, and extends substantially vertically from the peripheral portion of the inner bottom surface 51 toward the base end side. Here, the inclination angle θh formed by the inner peripheral surface 52 with respect to the inner bottom surface 51 is slightly obtuse than 90 degrees. That is, the inner peripheral surface 52 according to the present embodiment extends away from the central axis C (that is, radially outward) from the inner bottom surface 51 side toward the end surface 53 . Further, as shown in an enlarged view in FIG. 1, the corners where the inner bottom surface 51 and the inner peripheral surface 52 intersect are rounded so that the inner bottom surface 51 and the inner peripheral surface 52 are smoothly connected. .

Here, the inner peripheral surface 52 is provided with a connector 6 for connecting the feed tube 22 and the bell hub 5 as a paint receiving member. As shown in FIG. 3, the coupler 6 is provided at a part of the inner peripheral surface 52 in the circumferential direction. Specifically, the connecting device 6 according to the present embodiment is made of a bolt-shaped fastening member, and is arranged at a plurality of locations along the circumferential direction around the central axis C at equal intervals (in the example shown in FIG. 3, every 120 degrees). ) are provided in three places. Each connector 6 extends in a direction substantially orthogonal to the inner peripheral surface 52 .

In the state where the inner peripheral surface 52 is connected to the support 4 by the connector 6, as illustrated in FIG. ) are facing each other with a space between them. By doing so, the paint can be circulated in the gap between the inner peripheral surface 52 of the bell hub 5 and the outer peripheral surface of the support 4 .

Further, the end face 53 discharges the paint discharged from the feed tube 22 toward the bell cup 3 when the bell hub 5 as a paint receiving member rotates around the central axis C together with the bell cup 3 .

Here, the end face 53 according to the present embodiment is arranged outward (radially) from the end face 53 so as to discharge the paint toward the first inner peripheral face 33a of the bell cup 3 instead of the second inner peripheral face 33b. The extension line Le extending toward the outer side of the first inner peripheral surface 33a intersects with the first inner peripheral surface 33a. Specifically, as shown in FIG. 2, an extension line Le extending outward from the end surface 53 of the bell hub 5 extends along the direction of the central axis C to extend the first inner peripheral surface 33a from the base end portion 33R to the tip end. It intersects with the proximal side portion 33R when it is divided into the side portion 33T and the side portion 33T.

Specifically, the end surface 53 of the bell hub 5 is formed as a substantially annular flat surface. The end surface 53 extends along a plane perpendicular to the central axis C from the proximal end of the inner peripheral surface 52 of the bell hub 5 . When the end face 53 is connected to the support 4 by the connector 6, the end surface 53 faces the flange 4a of the support 4 with a space therebetween, as shown in FIG. . By doing so, the paint can flow between the end face 53 of the bell hub 5 and the flange portion 4 a of the support 4 .

The bell hub 5 according to this embodiment is arranged on the inner peripheral side of the bell cup 3 in the radial direction, and is inserted up to the cylindrical portion 31 on the base end side of the tapered portion 32 in the direction of the central axis C. there is That is, the inner peripheral surface 52 and the end surface 53 of the bell hub 5 overlap the first inner peripheral surface 33a when viewed along the direction perpendicular to the central axis C direction.

Further, the outer peripheral portion 54 of the bell hub 5 on the side of the end face 53 is formed so as to taper toward the outside in the radial direction. Specifically, the outer peripheral portion 54 on the side of the end face 53 in this embodiment refers to the outer peripheral portion of the bell hub 5 on the base end side and around the opening. As shown in FIG. 4, the outer peripheral portion 54 is tapered over the entire circumference. The tip of the outer peripheral portion 54 forms an acute angle of less than 90°.

(Operation of rotary bell cup coating machine)
FIG. 5 is a diagram illustrating the flow of paint in the rotary bell cup coating machine 1. As shown in FIG. 6A and 6B are explanatory diagrams showing a comparison of the effects of the coupler 6 on the flow.

The bell hub 5 as a paint receiving member rotates around the central axis C together with the bell cup 3, so that the paint discharged from the feed tube 22 toward the inner bottom surface 51 of the bell hub 5 is spread over the inner peripheral surface 52 of the bell hub 5 and the inner bottom surface 51 of the bell hub 5. It is configured to reach the inner peripheral surface (paint diffusion surface 33 ) of the bell cup 3 through the end surface 53 .

The configuration as described above will be specifically described below. First, when the rotary shaft 21 rotates around the central axis C, the bell cup 3 rotates integrally with the rotary shaft 21 . As the bell cup 3 rotates, the support 4 and, in turn, the bell hub 5 also rotate together.

When paint is discharged toward the rotating bell hub 5, the discharged paint reaches the center of the inner bottom surface 51 of the bell hub 5 as indicated by arrow A1 in FIG. The paint that has reached the central portion of the inner bottom surface 51 forms a diffusion flow due to the centrifugal force caused by the rotation of the bell hub 5, and flows radially outward along the inner bottom surface 51 as indicated by arrow A2.

The paint flowing along the inner bottom surface 51 passes through the inner bottom surface 51 and reaches the inner peripheral surface 52 . The paint that has reached the inner peripheral surface 52 forms a parallel flow substantially along the direction of the central axis C, and flows along the inner peripheral surface 52 toward the base end side as indicated by an arrow A3.

The paint flowing along the inner peripheral surface 52 passes through the inner peripheral surface 52 and reaches the end surface 53 while being prevented from flowing by the connector 6 . The paint that has reached the end face 53 forms a diffusion flow again and flows radially outward along the end face 53 as indicated by arrow A4.

The paint flowing along the end surface 53 scatters from the tapered outer peripheral portion 54 and reaches the first inner peripheral surface 33a of the paint diffusion surface 33, particularly the base end portion 33R of the first inner peripheral surface 33a. do. The paint that has reached the proximal end portion 33R is directed toward the distal end side in the direction of the central axis C as indicated by arrows A5 and A6 on the first inner peripheral surface 33a (specifically, the first inner peripheral surface 33a). , and the second inner peripheral surface 33b in order. At the tip of the second inner peripheral surface 33b in the paint diffusion surface 33, the paint becomes thread-like, and the thread-like paint is atomized and discharged.

(Refinement and homogenization of paint particle size)
As a result of extensive studies, the inventors of the present application have found that the liquid film flow on the inner surface of the bell hub 5 becomes uneven due to the eccentricity of the paint that collides with the inner surface of the bell hub 5 as the paint receiving member with respect to the rotating shaft 21. , that it causes the ripples of the liquid film on the inner surface, and that the ripples of the liquid film are caused by the connection structure of the bell hub 5 by the legs and the like.

On the other hand, according to the present embodiment, the paint flying from the end surface 53 of the bell hub 5 is applied to the first inner peripheral surface 33a and the second inner peripheral surface 33b in order, as indicated by the arrow A5 in FIG. will flow. According to the knowledge obtained by the inventors of the present application, by flowing the paint along the first inner peripheral surface 33a extending in the direction of the central axis C, the influence of eccentricity on the rotating shaft 21 is reduced, and the liquid of the paint is reduced. The film can be made uniform. As a result, ripples in the liquid film of the paint can be suppressed.

Furthermore, according to this embodiment, the paint flying from the end surface 53 of the bell hub 5 reaches the base end portion 33R of the first inner peripheral surface 33a. By doing so, the paint that has reached the first inner peripheral surface 33a flows not only through the tip side portion 33T but also through the base end side portion 33R. As a result, it is possible to further increase the flow distance when flowing on the first inner peripheral surface 33a, and it is possible to more reliably suppress ripples in the coating liquid film.

Thus, according to the above configuration, it is possible to suppress the ripples of the coating liquid film, and eventually to achieve finer and more uniform coating particle diameters.

Further, as illustrated in FIG. 2, when the inclination angle of the first inner peripheral surface 33a with respect to the direction of the central axis C is θc, the first inner peripheral surface is inclined so as to satisfy the relationship of 0°≦θc≦20°. By configuring 33a, it is possible to more reliably suppress ripples in the coating liquid film.

Further, as illustrated in FIG. 5, the paint discharged onto the inner bottom surface 51 of the bell hub 5 once flows along the inner peripheral surface 52 before reaching the bell cup 3 via the end surface 53 thereof. (see arrow A3 in FIG. 5). According to the knowledge obtained by the inventors of the present application, by flowing the paint along the inner peripheral surface of the member formed with a concave cross section, the influence of eccentricity on the rotating shaft 21 is reduced, and the liquid film of the paint is reduced. can be made uniform. As a result, it is possible to suppress ripples of the coating liquid film caused by obstruction of flow due to eccentricity of the colliding coating material with respect to the central axis C, or the like.

In addition, by suppressing the waving of the paint in advance before transferring from the bell hub 5 to the bell cup 3, the thickness of the paint liquid film can be reduced even if the impact of collision when transferring from the bell hub 5 to the bell cup 3 is taken into account. It can be kept as uniform as possible. As a result, it becomes possible to achieve finer and more uniform paint particle sizes.

Further, as described with reference to FIG. 5 , the paint flowing along the inner bottom surface 51 of the bell hub 5 becomes a diffusion flow due to the centrifugal force caused by the rotation of the bell hub 5 . On the other hand, since the paint flowing along the inner peripheral surface 52 of the bell hub 5 flows substantially parallel to the central axis C, it becomes a so-called parallel flow. According to the knowledge obtained by the inventors of the present application, the parallel flow is less affected by obstacles than the diffusive flow. That is, as shown in FIG. 6, in the case of diffusion flow, the flow of paint that collides with the connector 6 as an obstacle is relatively difficult to merge because the flow around the connector 6 is diffused. Become. On the other hand, in the case of parallel flow, since the flow around the connector 6 is substantially parallel, the paint flows colliding with the connector 6 are relatively easier to merge than in the case of the diffusion flow. Become.

Therefore, as illustrated in FIGS. 1 and 3, by providing the connector 6 on the inner peripheral surface 52 instead of the inner bottom surface 51 of the bell hub 5, the influence of the connector 6 as an obstacle on the flow is suppressed. In addition, it is advantageous in achieving finer and uniform paint particle diameters.

5, the paint transferred from the end surface 53 of the bell hub 5 to the bell cup 3 is applied to the second inner peripheral surface 33b on the tip side of the inner peripheral surface of the bell cup 3, and The first inner peripheral surface 33a on the base end side also flows. This first inner peripheral surface 33 a exhibits the same function as the inner peripheral surface 52 of the bell hub 5 . As a result, it is more advantageous to achieve finer and uniform paint particle sizes.

As described with reference to FIG. 5, the paint that is about to transfer from the bell hub 5 to the bell cup 3 flies from the outer peripheral portion 54 on the side of the end face 53 of the bell hub 5 to the bell cup 3, as shown in FIG. Thus, by tapering the outer peripheral portion 54, the paint will fly from the tip of the tapered portion.

If the outer peripheral portion 54 were to have a rounded shape, the paint adhered to the outer peripheral portion 54 due to surface tension would fly from the rounded portions. In this case, the flow distance of the paint becomes non-uniform, which is disadvantageous in achieving finer and uniform paint particle diameters.

On the other hand, according to this embodiment, as shown in FIG. 5, the paint flies from a specific portion (tip of the tapered portion) of the outer peripheral portion 54 . As a result, the flow distance of the paint is kept substantially constant, which is advantageous in achieving finer and uniform paint particle diameters.

Further, as shown in FIG. 1 , the inner peripheral surface 52 of the bell hub 5 extends away from the central axis C as it goes from the inner bottom surface 51 side of the bell hub 5 toward the end surface 53 . According to this, the paint on the inner peripheral surface 52 can be caused to flow from the inner bottom surface 51 side to the end surface 53 side by the centrifugal force caused by the rotation of the bell hub 5 . As a result, for example, it is possible to prevent the paint from remaining in the vicinity of the corner where the inner bottom surface 51 and the inner peripheral surface 52 intersect, thereby improving the usability of the rotary bell cup coating machine 1. - 特許庁This is particularly effective when painting while changing a plurality of types of paint.

(Modified example of rotary bell cup coating machine)
FIG. 7 is a diagram corresponding to FIG. 1 showing a conventional example of a rotary bell cup coating machine, and is a diagram illustrating the flow of paint in the conventional example. 9 is a diagram corresponding to FIG. 1 showing a modification of the rotary bell cup coating machine 1, and FIG. 10 is a diagram illustrating the flow of paint in the modification.

In the above-described embodiment, the bell hub 5 having a concave cross section and the bell cup 3 having the first inner peripheral surface 33a extending in the direction of the central axis C are used in order to achieve finer and uniform paint particle diameters. Although a synergistic configuration has been described, the present disclosure is not limited to that configuration.

For example, like the rotary bell cup coating machine 101 according to the modification, the bell cup 103 configured similarly to the above-described embodiment and the bell hub 305 configured similarly to the conventional example may be combined.

Specifically, the bell hub 305 of the rotary bell cup coating machine 301 according to the conventional example has a cross-sectional shape with a raised central portion. Further, in the conventional bell cup 303, the dimension of the cylindrical first inner peripheral surface 333a (in particular, the dimension in the direction of the central axis) is shorter than the first inner peripheral surface 33a in the above embodiment. It is

Therefore, the extension line extending from the end surface of the bell hub 305 according to the conventional example does not intersect with the cylindrical first inner peripheral surface 333a, and is substantially flush with the second inner peripheral surface 333b formed in a tapered shape. is extended to become

Therefore, the paint in the conventional example flows only through the second inner peripheral surface 333b without flowing through the first inner peripheral surface 333a, as indicated by the arrow in FIG. In this case, it is not possible to make the paint particle size finer and uniform.

On the other hand, the rotary bell cup coating machine 101 according to the modified example is configured to use the same bell cup 103 as in the above-described embodiment, although the shape of the bell hub 305 is substantially the same as that of the conventional example.

In this case, in the modified example, an extension line Le′ extending outward from the end surface of the bell hub 305 extends along the direction of the central axis C to extend the first inner peripheral surface 133a to the base end portion 133R, as in the above-described embodiment. and the distal side portion 133T, which intersects the proximal side portion 133R (see FIG. 10).

Therefore, as indicated by the arrows in FIG. 10, the paint in the modified example flows through the base end portion 133R of the first inner peripheral surface 333a, the tip end portion 133T, and the second inner peripheral surface 133b in this order. It is designed to flow to By causing the paint to flow over the entire first inner peripheral surface 133a, it is possible to make the paint particle size finer and more uniform, as in the above-described embodiment.

1 rotary bell cup coating machine 2 tubular member 21 rotary shaft 22 feed tube (paint supply tube)
3 Bell cup 33 Paint diffusion surface 33a First inner peripheral surface 33b Second inner peripheral surface 33R Base end side portion 33T of first inner peripheral surface Tip side portion 4 Support tool 5 Bell hub (paint receiving member)
51 inner bottom surface 52 inner peripheral surface 53 end surface 54 outer peripheral portion 6 connector C central axis

Claims (7)

A rotating bell cup coating machine for ejecting centrifugally atomized paint particles,
a paint supply pipe for discharging paint from the tip;
a bell cup that surrounds the tip of the paint supply pipe and rotates around the central axis of the paint supply pipe;
a paint receiving member facing the tip of the paint supply pipe and receiving the paint discharged from the tip;
The bell cup is
a first inner peripheral surface extending along the central axis direction and surrounding the paint receiving member;
a second inner peripheral surface provided on the tip side compared to the first inner peripheral surface and having a diameter increasing toward the tip side;
The paint receiving member has an end face that discharges the paint discharged from the paint supply pipe toward the bell cup when the paint receiving member rotates around the central axis together with the bell cup,
An extension line extending outward from the end surface intersects the proximal side portion and the distal side portion when the first inner peripheral surface is divided into a proximal side portion and a distal side portion along the central axis direction. A rotary bell cup coating machine characterized by: In the rotary bell cup coating machine according to claim 1,
Assuming that the inclination angle of the first inner peripheral surface with respect to the central axis direction is θc,
0°≦θc≦20°
A rotary bell cup coating machine characterized by satisfying the relationship of In the rotary bell cup coating machine according to claim 1 or 2,
The paint receiving member is configured to have a concave cross section facing the paint supply pipe,
The paint receiving member has an inner bottom surface facing the paint supply pipe and an inner peripheral surface extending from the inner bottom surface toward the end surface,
The paint receiving member rotates about the central axis together with the bell cup, so that the paint discharged from the paint supply pipe toward the inner bottom surface flows through the inner peripheral surface and the end surface into the bell cup. A rotary bell cup coating machine characterized in that it is configured to reach the inner peripheral surface of the. In the rotary bell cup coating machine according to claim 3,
A connector provided on the inner peripheral surface and connecting the bell cup and the paint receiving member,
A rotary bell cup coating machine, wherein the connecting member is provided on a part of the inner peripheral surface in a circumferential direction around the central axis. In the rotary bell cup coating machine according to claim 3 or 4,
A rotary bell cup coating machine, wherein an outer peripheral portion of the paint receiving member on the side of the end surface is formed so as to taper outward in a radial direction. In the rotary bell cup coating machine according to any one of claims 3 to 5,
A rotary bell cup coating machine, wherein the inner peripheral surface extends away from the central axis from the inner bottom surface toward the end surface. In the rotary bell cup coating machine according to any one of claims 1 to 6,
a rotating shaft into which the paint supply pipe is inserted and which rotates integrally with the bell cup;
a support arranged on the tip side of the paint supply pipe and inserted into the inner peripheral side of the bell cup,
The paint receiving member is formed in a bottomed cylindrical shape with an opening facing the tip of the paint supply pipe,
A rotary bell cup coating machine, wherein the paint receiving member is connected to the support and rotates integrally with the bell cup via the support.

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