JP7777926B2 - Rotating Bell Cup Coating Machine - Google Patents

Description

The technology disclosed herein relates to a rotary bell cup sprayer.

Patent Document 1 discloses, as an example of a rotary bell cup coating machine, a rotary atomizing head type coating device equipped with 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 bell hub (hub member) attached to the center of the base end of the bell cup. The bell hub described in this document is formed in the shape of a disk with a conical protrusion in its center, and is oriented so that the protrusion faces the feed tube.

The bell hub disclosed in Patent Document 1 has multiple legs and multiple cutout grooves on its outer periphery. The cutout grooves are alternately formed with the legs, and when fitted into a groove (hub fitting groove) provided in the bell cup, they form multiple perforated paint passages between the grooves. Paint dispensed onto the inner bottom surface of the bell hub is guided to the inner circumferential surface of the bell cup via these perforated paint passages, and the paint particles are released at the inner circumferential surface of the bell cup.

Japanese Patent Application Laid-Open No. 2002-224593

When using a bell hub such as that disclosed in Patent Document 1, as the paint discharged from the feed tube flows along the inner surface of the bell hub, there is a risk of the paint film rippling due to factors such as the paint colliding with the inner surface, the paint becoming eccentric relative to the rotation axis due to such collisions, obstructions to the flow due to obstacles such as the legs disclosed in Patent Document 1, and collisions when transferring from the bell hub to the bell cup. Rippling paint is undesirable in terms of achieving finer and more uniform paint particle size.

The technology disclosed here was developed in light of these issues, and its purpose is to achieve finer and more uniform paint particle diameters in rotary bell cup sprayers.

The technology disclosed herein relates to a rotary bell cup sprayer that discharges centrifugally atomized paint particles. This rotary bell cup sprayer includes a paint supply pipe that discharges paint from its tip, a bell cup that surrounds the tip of the paint supply pipe and rotates around the central axis of the paint supply pipe, and a paint receiving member with a concave cross section that is attached to the inner periphery of the bell cup and oriented with its recess facing the paint supply pipe. The paint receiving member has an inner bottom surface facing the paint supply pipe, an end surface facing the paint supply pipe, and an inner periphery that extends from the inner bottom surface toward the end surface, and is formed into a bottomed cylindrical shape with its inner bottom surface facing the tip of the paint supply pipe.

The inner bottom surface of the paint receiving member is a circular plane arranged perpendicular to the central axis, and the inner circumferential surface of the paint receiving member extends from the peripheral edge of the inner bottom surface at an angle relative to the inner bottom surface so that the inclination angle between the inner circumferential surface and the inner bottom surface is obtuse.The paint receiving member is configured to rotate around the central axis together with the bell cup so that paint ejected from the paint supply pipe toward the inner bottom surface reaches the inner circumferential surface of the bell cup via the inner circumferential surface and the end face.

After extensive research, the inventors of this application discovered that when a conventional bell hub is used, the eccentricity of the paint that strikes the inner surface of the paint receiving member relative to the rotation axis causes the liquid film to flow unevenly on the inner surface of the bell hub, which causes the liquid film to ripple on the inner surface of the bell cup, and that the ripples in the liquid film are caused by the connecting structure of the bell hub, such as the legs.

In contrast, with the above-described configuration, the paint dispensed into the paint receiving member flows along its inner bottom surface and inner circumferential surface before reaching the bell cup. According to the findings of the inventors, in addition to receiving the paint on the inner bottom surface of a member with a concave cross section, by having the paint flow along its inner circumferential surface, it is possible to reduce the effects of eccentricity as described above and to make the paint film uniform in thickness. This makes it possible to suppress rippling in the paint film.

In addition, by suppressing rippling of the paint before it transfers from the paint receiving member to the bell cup, the thickness of the paint liquid film can be kept as uniform as possible, even when taking into account the impact of collisions when transferring from the paint receiving member to the bell cup. This makes it possible to achieve finer and more uniform paint particle diameters.

The rotary bell cup sprayer may also include a connector provided on the inner circumferential surface of the paint receiving member, connecting the bell cup to the paint receiving member.

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

With this configuration, paint flowing along the inner bottom surface becomes a diffused flow due to centrifugal force caused by the rotation of the paint receiver. Meanwhile, paint flowing along the inner circumferential surface flows roughly parallel to the central axis, resulting in a so-called parallel flow. According to the findings of the present inventors, parallel flows are less affected by obstacles than diffuse flows. Therefore, by providing the connector on the inner circumferential surface rather than the inner bottom surface, the effect of the connector acting as an obstacle on the flow is reduced, which is advantageous in achieving finer and more uniform paint particle size.

The connector may also be provided on a portion of the inner circumferential surface of the paint receiving member in the circumferential direction around the central axis.

This configuration minimizes the impact of the connector on the flow.

Furthermore, the connectors may be provided at multiple locations at equal intervals along the circumferential direction, and each connector may extend in a direction perpendicular to the inner circumferential surface of the paint receiving member.

This configuration minimizes the impact of connectors acting as obstacles on the flow.

Furthermore, the inner peripheral surface of the bell cup may have a tip-side paint diffusion surface that does not overlap with the paint supply pipe when viewed in a direction perpendicular to the central axis, and a base-side paint diffusion surface that overlaps with the paint supply pipe when viewed in a direction perpendicular to the central axis, and the inner peripheral surface and the end face of the paint receiving member may overlap with the base-side paint diffusion surface when viewed in a direction perpendicular to the central axis.

With this configuration, paint that transfers from the end face of the paint receiving member to the bell cup flows along the base-end paint diffusion surface as well as the tip-end paint diffusion surface of the bell cup's inner circumferential surface. This ensures a longer paint flow distance, which is advantageous for achieving finer and more uniform paint particle diameters.

The outer periphery of the end face of the paint receiving member may be tapered radially outward.

Here, "radial direction" refers to a direction extending perpendicularly and radially from the central axis.

With this configuration, paint attempting to transfer from the paint receiving member to the bell cup flies from the outer periphery on the end face side of the paint receiving member to the bell cup. However, by tapering the outer periphery, the paint flies from the tip of the tapered portion. This causes the paint to fly from a specific location on the outer periphery. This keeps the paint flow distance approximately constant, which is advantageous for achieving finer and more uniform paint particle diameters. Furthermore, by tapering the outer periphery on the end face side, it is possible to prevent paint from wrapping around the paint receiving member due to surface tension. This also works effectively to achieve finer and more uniform paint particle diameters.

The inner peripheral surface of the paint receiving member extends away from the central axis as it moves from the inner bottom surface toward the end surface.

With this configuration, the centrifugal force caused by the rotation of the paint receiver member causes the paint on the inner peripheral surface to flow from the inner bottom surface toward the end surface. This prevents paint from remaining near the corner where the inner bottom surface and inner peripheral surface intersect, for example, and ultimately improves the usability of the rotary bell cup sprayer. This is particularly effective when changing between different types of paint during painting.

The rotary bell cup sprayer may further include a rotating shaft into which the paint supply pipe is inserted and which rotates integrally with the bell cup, and a support device disposed at the tip of the paint supply pipe and inserted into the inner surface of the bell cup; the paint receiving member may be formed in a cylindrical shape with a bottom and an opening facing the tip of the paint supply pipe; the paint receiving member may be connected to the support device and rotate integrally with the bell cup via the support device.

As explained above, the rotary bell cup sprayer can achieve finer and more uniform paint particles.

FIG. 1 is a longitudinal cross-sectional view illustrating the tip of a rotary bell cup sprayer. FIG. 2 is a cross-sectional view illustrating the tip of a rotary bell cup sprayer. FIG. 3 is a perspective view illustrating the configuration of the bell hub. FIG. 4 is a diagram illustrating the flow of paint in a rotary bell cup sprayer. FIG. 5 is an explanatory diagram showing the influence of connectors on flow in comparison. FIG. 6 is a view corresponding to FIG. 1, showing a first modified example of the rotary bell cup sprayer. FIG. 7 is a view corresponding to FIG. 1, showing a second modified example of the rotary bell cup sprayer.

Embodiments of the present disclosure will be described below with reference to the drawings. Please note that the following description is for illustrative purposes only.

(Configuration of the rotating bell cup coating machine)
Fig. 1 is a longitudinal cross-sectional view illustrating the tip of the rotary bell cup coater 1, and Fig. 2 is a transverse cross-sectional view illustrating the tip of the rotary bell cup coater 1. Furthermore, Fig. 3 is a perspective view illustrating the configuration of the bell hub 5. Note that Fig. 1 is a cross-section taken along the central axis C of the rotary bell cup coater 1, and Fig. 2 corresponds to the A-A cross-section in Fig. 1.

In the following description, the term "base end side" refers to the feed tube 22 side in the direction of the central axis C (the side opposite the workpiece S), and the term "tip side" refers to the opposite side of the feed tube 22 in the same direction (the side opposite the workpiece S). In the following description, the term "radial direction" refers to a direction perpendicular to the central axis C and extending radially from the central axis C, and the term "circumferential direction" refers to a direction perpendicular to the radial direction and circulating around the central axis C.

The rotary bell cup applicator 1 shown in Figure 1 etc. is a rotary atomizer coating device for electrostatic coating, configured to emit centrifugally atomized paint particles. That is, the rotary bell cup applicator 1 atomizes paint by using centrifugal force to eject it from a bell cup 3 attached to a rotating shaft 21 that rotates at high speed, and paints using the attractive force acting between the negatively charged paint particles and the positively charged object to be coated S, such as an automobile body.

Specifically, the rotary bell cup sprayer 1 comprises a cylindrical housing 10, a tubular member 2 inserted into the housing 10 and discharging paint from its tip, a bell cup 3 surrounding the tip 22a of a feed tube 22 in the tubular member 2 and rotating around the central axis C of the feed tube 22, a bell hub 5 with a concave cross section that is attached to the inner periphery of the bell cup 3 and oriented with its recess facing the paint supply pipe 2, and a support 4 for attaching the bell hub 5 to the bell cup 3.

The housing 10 is cylindrical and houses the tubular member 2 and a high-voltage power supply (not shown) for charging the paint. The base end of the bell cup 3 is inserted into an opening 10a at the tip of the housing 10. Although not shown, air can be ejected from the tip of the housing 10 to deflect the paint particles.

The tubular member 2 also 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 a "paint supply pipe" in this embodiment.

Of these, the rotating shaft 21 is configured as a hollow shaft member and is inserted into the cylindrical portion 31 on the base end side of the bell cup 3. This rotating shaft 21 is configured to rotate around the central axis C when power is received from the outside, and rotates integrally with the bell cup 3 via the cylindrical portion 31.

The feed tube 22 is configured as a tubular member through which paint flows, and is inserted into the rotating shaft 21. The tip 22a of the feed tube 22 is configured as an open end through which paint can be ejected, and is exposed from the rotating shaft 21. The feed tube 22 in this embodiment allows paint to flow from one side (the side opposite the workpiece S) in the direction of the central axis C to the other side (the side toward the workpiece S), and ejects the paint from the tip 22a. The paint ejected from this tip 22a collides with the inner bottom surface 51 of the bell hub 5.

The bell cup 3 is generally cup-shaped and has a cylindrical portion 31 at the base end into which the rotating shaft 21 and other components are inserted, and a tapered portion 32 at the tip end along whose inner surface paint flows.

Of these, the cylindrical portion 31 is formed in a short cylindrical shape extending along the central axis C, with the rotating shaft 21 inserted from the base end and the support 4 inserted from the tip end. The inner circumferential surface of the cylindrical portion 31 is provided with an abutment portion 31a that protrudes radially inward. This abutment portion 31a is configured to abut against the support 4 inserted into the cylindrical portion 31, thereby positioning the support 4.

The inner circumferential surface of the cylindrical portion 31, located closer to the tip than the abutting portion 31a, is designed to allow paint scattered from the bell hub 5 by centrifugal force to flow. This inner circumferential surface forms a paint diffusion surface 33 (particularly the first diffusion surface 33a on the base end side of the paint diffusion surface 33) for diffusing the paint.

The first diffusion surface 33a of the cylindrical portion 31 gradually expands in diameter toward the tip end and is provided to surround the tip end of the tubular member 2 (specifically, the tip end 22a of the feed tube 22) and the support fixture 4 from the outer periphery. In other words, this first diffusion surface 33a overlaps with the feed tube 22 and the support fixture 4 when viewed in a direction perpendicular to the central axis C (radial direction). The first diffusion surface 33a is an example of a "base end paint diffusion surface."

The tapered portion 32 tapers toward the tip, and its inner circumferential surface allows paint that has flowed along the first diffusion surface 33a to flow along it. This inner circumferential surface, together with the first diffusion surface 33a, forms the paint diffusion surface 33 (particularly the second diffusion surface 33b on the tip side of the paint diffusion surface 33) for diffusing the paint.

The second diffusion surface 33b of the tapered portion 32 expands in diameter more steeply toward the tip than the first diffusion surface 33a, and is located closer to the tip of the tubular member 2 (specifically, the tip 22a of the feed tube 22) and the support 4. In other words, this second diffusion surface 33b does not overlap with the feed tube 22 and the support 4 when viewed in a direction perpendicular to the central axis C (radial direction). The second diffusion surface 33b is an example of a "tip-side paint diffusion surface."

The support 4 is positioned on the tip 22a side of the feed tube 22 and is inserted into the inner periphery of the bell cup 3. Specifically, the support 4 according to this embodiment is formed in a cylindrical shape extending in the direction of the central axis C, and is inserted into the cylindrical portion 31 of the bell cup 3 with the tip 22a of the feed tube 22 inserted therethrough. In other words, the inner diameter of the support 4 is larger than the tip 22a of the feed tube 22, and the outer diameter of the support 4 is smaller than the cylindrical portion 31.

Furthermore, a flange-shaped protruding collar portion 4a is provided on the outer surface of the support 4. When the support 4 is inserted and pushed into the cylindrical portion 31, the collar portion 4a of the support 4 abuts against the abutment portion 31a of the cylindrical portion 31. This positions the support 4 relative to the bell cup 3, and particularly the cylindrical portion 31.

The bell hub 5 is formed with a concave cross section facing the feed tube 22, and has an inner bottom surface 51 facing the feed tube 22, an end surface 53 facing the feed tube 22, and an inner circumferential surface 52 extending from the inner bottom surface 51 toward the end surface 53. The bell hub 5 is an example of the "paint receiving member" in this embodiment.

Specifically, the bell hub 5 in this embodiment is formed in a bottomed cylindrical shape with its opening and inner bottom surface 51 facing the tip 22a of the feed tube 22, and has a circular inner bottom surface 51, a substantially cylindrical inner circumferential surface 52, and an end surface 53 that corresponds to the opening edge of the bell hub 5. The bell hub 5 is connected to the support 4 via the connector 6 (described below), and rotates integrally with the bell cup 3 via this support 4.

The inner bottom surface 51 is formed as a circular flat surface and is positioned perpendicular to the central axis C, with the center of the inner bottom surface 51 (the part that corresponds to the center when the inner bottom surface 51 is considered to be a circle) facing the tip 22a of the feed tube 22. By positioning it in this way, the paint ejected from the feed tube 22 collides with the center of the inner bottom surface 51.

Next, the inner circumferential surface 52 is formed as a substantially cylindrical curved surface, extending substantially perpendicularly from the periphery of the inner bottom surface 51 toward the base end. Here, the inclination angle θ formed by the inner circumferential surface 52 with respect to the inner bottom surface 51 is slightly obtuse than 90 degrees. That is, the inner circumferential surface 52 in this embodiment extends away from the central axis C (i.e., radially outward) as it extends from the inner bottom surface 51 toward the end surface 53. In addition, as shown enlarged in Figure 1, the corner where the inner bottom surface 51 and the inner circumferential surface 52 intersect is rounded, providing a smooth connection between the inner bottom surface 51 and the inner circumferential surface 52.

The inner circumferential surface 52 is provided with connectors 6 for connecting the feed tube 22 to the bell hub 5, which serves as a paint receiving member. As shown in FIG. 2, the connectors 6 are provided on a portion of the inner circumferential surface 52 in the circumferential direction. Specifically, the connectors 6 in this embodiment are bolt-shaped fastening members, and are provided at multiple equally spaced locations (in the example shown in FIG. 2, three locations spaced 120 degrees apart) along the circumferential direction around the central axis C. Each connector 6 extends in a direction substantially perpendicular to the inner circumferential surface 52.

When connected to the support 4 by the connector 6, the inner circumferential surface 52 faces the outer circumferential surface of the support 4 (particularly the outer circumferential surface distal to the flange 4a), as shown in Figure 1. This allows paint to flow through the gap between the inner circumferential surface 52 of the bell hub 5 and the outer circumferential surface of the support 4.

The end face 53 is formed as a generally annular flat surface, extending from the base end of the inner circumferential surface 52 along a plane perpendicular to the central axis C. When connected to the support 4 by the connector 6, this end face 53 faces the flange 4a of the support 4 with a gap therebetween, as shown in Figure 1. This allows paint to flow through the gap between the end face 53 of the bell hub 5 and the flange 4a of the support 4.

The bell hub 5 in this embodiment is positioned radially inward of the bell cup 3, and is inserted in the direction of the central axis C up to the cylindrical portion 31, which is closer to the base end than the tapered portion 32. In other words, the inner peripheral surface 52 and end face 53 of the bell hub 5 overlap with the first diffusion surface 33a when viewed in a direction perpendicular to the direction of the central axis C.

The outer periphery 54 on the end face 53 side of the bell hub 5 is tapered radially outward. Specifically, in this embodiment, the outer periphery 54 on the end face 53 side refers to the outer periphery on the base end side of the bell hub 5 around the opening. This outer periphery 54 tapers along the entire circumferential direction. The tip of the outer periphery 54 forms an acute angle of less than 90 degrees.

(Rotating bell cup sprayer in operation)
FIG. 4 is a diagram illustrating the flow of paint in the rotary bell cup sprayer 1, and FIG. 5 is an explanatory diagram showing the influence of the connector 6 on the flow in comparison.

The bell hub 5, which serves as a paint receiving member, rotates around the central axis C together with the bell cup 3, so that paint ejected from the feed tube 22 toward the inner bottom surface 51 of the bell hub 5 reaches the inner surface of the bell cup 3 (paint diffusion surface 33) via the inner circumferential surface 52 and end surface 53 of the bell hub 5.

This configuration will be explained in detail below. First, when the rotating shaft 21 rotates around the central axis C, the bell cup 3 rotates integrally with it. As the bell cup 3 rotates, the support 4, and therefore the bell hub 5, also rotate integrally.

When paint is ejected toward the rotating bell hub 5, the ejected paint reaches the center of the inner bottom surface 51 of the bell hub 5, as shown by arrow A1 in Figure 5. Once the paint reaches the center of the inner bottom surface 51, it forms a diffusing 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 shown by arrow A2.

The paint flowing along the inner bottom surface 51 passes through this inner bottom surface 51 and reaches the inner circumferential surface 52. Upon reaching the inner circumferential surface 52, the paint flows in parallel, generally along the direction of the central axis C, and flows toward the base end along the inner circumferential surface 52, as shown by arrow A3.

The paint flowing along the inner circumferential surface 52 is impeded by the connector 6, passing through the inner circumferential surface 52 and reaching the end surface 53. Once the paint reaches the end surface 53, it again diffuses and flows radially outward along the end surface 53, as shown by arrow A4.

The paint flowing along the end surface 53 is scattered from the tapered outer periphery 54 and reaches the first diffusion surface 33a of the paint diffusion surface 33. After reaching the first diffusion surface 33a, the paint passes through the first diffusion surface 33a and then the second diffusion surface 33b in turn toward the tip side in the direction of the central axis C. The paint becomes thread-like at the tip of the second diffusion surface 33b of the paint diffusion surface 33, and the thread-like paint is broken down into fine particles and released.

(Effects, etc.)
After extensive research, the inventors of the present application have discovered that the eccentricity of the paint that collides with the inner surface of the bell hub 5, which serves as a paint receiving member, relative to the rotation axis 21 causes the liquid film to flow unevenly on the inner surface of the bell hub 5, which in turn causes the liquid film to ripple on the inner surface, and that the connecting structure of the bell hub 5, such as the legs, causes the liquid film to ripple.

In contrast, in this embodiment, paint ejected onto the inner bottom surface 51 of the bell hub 5 flows along its inner circumferential surface 52 before reaching the bell cup 3 via its end surface 53 (see arrow A3 in Figure 5). According to the findings of the inventors, by making the paint flow along the inner circumferential surface of a member formed with a concave cross section, the effects of eccentricity with respect to the rotating shaft 21 can be reduced and the thickness of the paint film can be made uniform. This makes it possible to suppress rippling of the paint film caused by flow obstruction due to eccentricity with respect to the central axis C of the impinging paint.

In addition, by suppressing wavy paint before it transfers from the bell hub 5 to the bell cup 3, the thickness of the paint liquid film can be kept as uniform as possible, even when taking into account the impact of collisions when transferring from the bell hub 5 to the bell cup 3. This makes it possible to achieve finer and more uniform paint particle diameters.

As explained using Figure 4, paint flowing along the inner bottom surface 51 of the bell hub 5 becomes a divergent flow due to the centrifugal force caused by the rotation of the bell hub 5. On the other hand, paint flowing along the inner circumferential surface 52 of the bell hub 5 flows approximately parallel to the central axis C, resulting in a so-called parallel flow. According to the findings of the present inventors, parallel flows are less affected by obstacles than divergent flows. That is, as shown in Figure 5, in the case of divergent flows, paint flows that collide with the connector 6 as an obstacle are relatively less likely to merge because the flows around the connector 6 are divergent. On the other hand, in the case of parallel flows, paint flows that collide with the connector 6 are relatively more likely to merge than in the case of divergent flows because the flows around the connector 6 are approximately parallel.

As shown in Figures 1 and 2, by providing the connector 6 on the inner peripheral surface 52 of the bell hub 5 rather than on the inner bottom surface 51, the effect of the connector 6 acting as an obstacle on the flow is reduced, which is advantageous in achieving finer and more uniform paint particle diameters.

Furthermore, as explained using Figure 4, paint that has transferred from the end surface 53 of the bell hub 5 to the bell cup 3 flows not only over the second diffusion surface 33b on the tip side of the inner circumferential surface of the bell cup 3, but also over the first diffusion surface 33a on the base side. This first diffusion surface 33a performs the same function as the inner circumferential surface 52 of the bell hub 5. As a result, this is even more advantageous in achieving finer and more uniform paint particle diameters.

As explained using Figure 4, paint attempting to transfer from the bell hub 5 to the bell cup 3 flies from the outer periphery 54 on the end face 53 side of the bell hub 5 to the bell cup 3. However, by tapering the outer periphery 54, the paint flies from the tip of the tapered portion.

If the outer periphery 54 were to have a rounded shape, the paint adhering to the outer periphery 54 would fly off from each of the rounded points due to surface tension. In this case, the paint would flow unevenly, which would be detrimental to achieving finer and more uniform paint particle diameters.

On the other hand, according to this embodiment, as shown in Figure 4, the paint is ejected from a specific location on the outer periphery 54 (the tip of the tapered portion). This keeps the paint flow distance approximately constant, which is advantageous in achieving finer and more uniform paint particle diameters.

Also, as shown in FIG. 1, the inner circumferential surface 52 of the bell hub 5 extends away from the central axis C from the inner bottom surface 51 toward the end surface 53 of the bell hub 5. This allows the paint on the inner circumferential surface 52 to flow from the inner bottom surface 51 toward the end surface 53 due to the centrifugal force caused by the rotation of the bell hub 5. This prevents paint from remaining near the corner where the inner bottom surface 51 and the inner circumferential surface 52 intersect, for example, and ultimately improves the usability of the rotary bell cup sprayer 1. This is particularly effective when painting while changing multiple types of paint.

(First Variant of Bellhub)
FIG. 6 is a view corresponding to FIG. 1 and showing a first modified example of the rotary bell cup sprayer 1. In FIG.

In the above embodiment, the connector 6 was provided on the inner peripheral surface 52 of the bell hub 5, but this configuration is not limited to this. For example, in the rotary bell cup sprayer 101 of the first modified example, the bell hub 105 and the support 104 are connected via the connector 106, as in the above embodiment. However, the connector 106 of the first modified example is provided on the inner bottom surface 151 of the bell hub 105, rather than on the inner peripheral surface 152 of the bell hub 105. With this configuration, the insertion direction of the bell hub 105 and the insertion direction of the connector 106 are both in the direction of the central axis C, making it easier to assemble the rotary bell cup sprayer 101.

(Bellhub's second variant)
FIG. 7 is a view corresponding to FIG. 1 and showing a second modified example of the rotary bell cup sprayer 1. In FIG.

In the above embodiment, the paint was sprayed from the end face 53 of the bell hub 5 and reached the inner surface of the bell cup 3, but this configuration is not limited to this. For example, in the rotary bell cup sprayer 201 of the second modified example, the end face 253 of the bell hub 205 is shaped to fit the inner surface 233 of the bell cup 203, and faces the bell cup 203 with a small gap between them. This configuration allows the paint to be smoothly guided from the end face 253 of the bell hub 5 to the inner surface 233 of the bell cup 203.

Other Embodiments
Furthermore, in the above embodiment, the first diffusion surface 33a of the bell cup 3 is configured to perform the same function as the inner peripheral surface 52 of the bell hub 5, but the technology disclosed herein is not limited to this configuration. For example, the bell hub 5 may protrude from the bell cup 3. In this case, paint that has scattered from the outer peripheral portion 54 of the bell hub 5 will reach the second diffusion surface 33b rather than the first diffusion surface 33a.

1 Rotary bell cup coating machine 2 Tubular member 21 Rotary shaft 22 Feed tube (paint supply pipe)
3 Bell cup 33 Paint diffusion surface 33a First diffusion surface (base end side paint diffusion surface)
33b Second diffusion surface (tip-side paint diffusion surface)
4 Support 5 Bell hub (paint receiving member)
51 Inner bottom surface 52 Inner peripheral surface 53 End surface 54 Outer peripheral part 6 Connector C Central axis S Object to be painted

Claims (8)

A rotary bell cup coating machine that discharges centrifugally atomized paint particles,
a paint supply pipe that discharges paint from its tip;
a bell cup provided to surround the tip of the paint supply pipe and rotates around the central axis of the paint supply pipe;
a paint receiving member having a concave cross section, which is provided on the inner circumferential side of the bell cup and is oriented with its concave facing the paint supply pipe,
The paint receiving member has an inner bottom surface facing the paint supply pipe, an end surface facing the paint supply pipe, and an inner circumferential surface extending from the inner bottom surface toward the end surface, and is formed into a bottomed cylindrical shape with the inner bottom surface facing the tip of the paint supply pipe,
The inner bottom surface of the paint receiving member is a circular flat surface that is disposed perpendicular to the central axis,
The inner peripheral surface of the paint receiving member extends from a peripheral edge of the inner bottom surface at an incline relative to the inner bottom surface so that the inclination angle of the inner peripheral surface relative to the inner bottom surface is an obtuse angle,
The paint receiving member rotates around the central axis together with the bell cup, so that paint ejected from the paint supply pipe toward the inner bottom surface reaches the inner surface of the bell cup via the inner peripheral surface and the end surface. 2. The rotary bell cup sprayer according to claim 1,
a connecting member provided on the inner peripheral surface of the paint receiving member for connecting the bell cup and the paint receiving member; 3. The rotary bell cup sprayer according to claim 2,
The rotary bell cup sprayer is characterized in that the connector is provided on a portion of the inner circumferential surface of the paint receiving member in the circumferential direction around the central axis. 4. The rotary bell cup coating machine according to claim 3,
The connectors are provided at a plurality of locations at equal intervals along the circumferential direction,
A rotary bell cup sprayer, characterized in that each of the connectors extends in a direction perpendicular to the inner peripheral surface of the paint receiving member. The rotary bell cup sprayer according to any one of claims 1 to 4,
The inner peripheral surface of the bell cup is
a tip-side paint diffusion surface that does not overlap with the paint supply pipe when viewed along a direction perpendicular to the central axis;
a base end paint spreading surface that overlaps with the paint supply pipe when viewed along a direction perpendicular to the central axis,
A rotary bell cup sprayer characterized in that the inner surface and the end surface of the paint receiving member overlap with the base end paint spreading surface when viewed along a direction perpendicular to the central axis direction. The rotary bell cup sprayer according to any one of claims 1 to 5,
A rotary bell cup sprayer, characterized in that the outer periphery of the end face of the paint receiving member is formed so as to taper radially outward. The rotary bell cup sprayer according to any one of claims 1 to 6,
A rotary bell cup sprayer, characterized in that the inner peripheral surface of the paint receiving member extends so as to move away from the central axis as it moves from the inner bottom surface side toward the end surface. The rotary bell cup sprayer according to any one of claims 1 to 7,
a rotating shaft into which the paint supply pipe is inserted and which rotates integrally with the bell cup;
a support member that is disposed at the tip side of the paint supply pipe and inserted into the inner circumferential side of the bell cup,
The paint receiving member is formed in a cylindrical shape with a bottom and an opening facing the tip of the paint supply pipe,
A rotary bell cup sprayer, characterized in that the paint receiving member is connected to the support and rotates integrally with the bell cup via the support.