Rotating Bell Cup Coating Machine

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 from a tip; a bell cup 3 rotating about a central axis C of the feed tube 22; and a bell hub 5 which is provided on an inner peripheral side of the bell cup 3, and which has a concave cross section in a posture of directing the concavity to the feed tube 22. The bell hub 5 rotates about the central axis C together with the bell cup 3, and thereby the coating material ejected from the feed tube 22 toward an inner bottom surface 51 of the bell hub 5 is transferred to an inner peripheral surface of the bell cup 3 via an inner peripheral surface 52 and an end surface 53 of the bell hub 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed herein relates to a rotary bell cup sprayer. [Background technology]

[0002] Patent Document 1 discloses, as an example of a rotary bell cup coating machine, a rotary atomizing head type coating device that includes 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.

[0003] The bell hub disclosed in Patent Document 1 has a plurality of legs and a plurality of notched grooves on its outer periphery. The notched grooves are formed alternately with the legs, and when fitted into a groove (hub fitting groove) provided in the bell cup, they form a plurality of perforated paint passages between the groove and the notched groove. 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-224593 Summary of the Invention [Problem to be solved by the invention]

[0005] 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 possibility that the paint film will ripple due to factors such as the paint colliding with the inner surface, the paint becoming eccentric relative to the rotation axis after colliding, 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 of the paint is undesirable in terms of miniaturizing and uniforming the paint particle size.

[0006] The technology disclosed herein has been developed in light of these issues, and its purpose is to achieve finer and more uniform paint particle diameters in a rotary bell cup coating machine. [Means for solving the problem]

[0007] The technology disclosed herein relates to a rotary bell cup sprayer that discharges centrifugally atomized paint particles. The 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 center axis of the paint supply pipe, and a paint receiving member that is disposed on the inner periphery of the bell cup and has a concave cross section and is oriented with its recess facing the paint supply pipe. The paint receiving member is cylindrical with its inner bottom surface facing the paint supply pipe, its end surface facing the paint supply pipe, and its inner periphery extending from the inner bottom surface toward the end surface.

[0008] The inner bottom surface of the paint receiving member is a circular plane disposed perpendicular to the central axis, and the inner peripheral surface of the paint receiving member is The inclination angle formed by the inner peripheral surface with respect to the inner bottom surface is an obtuse angle. From the peripheral edge of the inner bottom surface to the inner bottom surface Leaning The paint receiving member extends obliquely, and 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 surface of the bell cup via the inner surface and the end surface.

[0009] After extensive research, the inventors of the present application discovered that when a conventional bell hub is used, the eccentricity of the paint that collides with 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 using legs, etc.

[0010] 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 present inventors, the paint is received on the inner bottom surface of the member having a concave cross section, and the paint flows along its inner circumferential surface, thereby reducing the effects of eccentricity and achieving a uniform thickness for the paint film. This also helps prevent rippling of the paint film.

[0011] Furthermore, 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 taking into account the impact of collisions when transferring from the paint receiving member to the bell cup, which makes it possible to achieve finer and more uniform paint particle diameters.

[0012] The rotary bell cup sprayer may further include a connector provided on the inner peripheral surface of the paint receiving member for connecting the bell cup and the paint receiving member.

[0013] Here, the connector may indirectly connect the bell cup and the paint receiving member via another member, or may connect them directly without using another member.

[0014] With this configuration, the paint flowing along the inner bottom surface becomes a diffused flow due to centrifugal force caused by the rotation of the paint receiver. Meanwhile, the paint flowing along the inner circumferential surface flows approximately parallel to the central axis, resulting in a so-called parallel flow. According to the findings of the present inventors, a parallel flow is less affected by obstacles than a diffused flow. Therefore, by providing the connector on the inner circumferential surface rather than the inner bottom surface, the effect of the connector as an obstacle on the flow is reduced, which is advantageous in realizing finer and more uniform paint particle size.

[0015] The connector may be provided on a part of the inner circumferential surface of the paint receiving member in the circumferential direction around the central axis.

[0016] This configuration can minimize the influence of the connector on the flow.

[0017] In addition, the connectors may be provided at equal intervals at multiple locations along the circumferential direction, and each of the connectors may extend in a direction perpendicular to the inner circumferential surface of the paint receiving member.

[0018] With this configuration, the influence of the connector acting as an obstacle on the flow can be minimized as much as possible.

[0019] Furthermore, the inner 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 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.

[0020] With this configuration, the paint that has transferred from the end face of the paint receiving member to the bell cup flows over the base end paint diffusion surface as well as the tip end paint diffusion surface of the inner circumferential surface of the bell cup, which ensures a longer paint flow distance and is advantageous in achieving finer and more uniform paint particle diameters.

[0021] The outer periphery of the end face of the paint receiving member may be formed to taper radially outward.

[0022] Here, the term "radial direction" refers to a direction extending perpendicularly and radially from the central axis.

[0023] With this configuration, paint transferring from the paint receiving member to the bell cup flies from the outer periphery of the end face 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 maintains a substantially constant paint flow distance, which is advantageous for achieving finer and more uniform paint particle diameters. Furthermore, tapering the outer periphery on the end face also prevents paint from wrapping around the paint receiving member due to surface tension. This also effectively contributes to achieving finer and more uniform paint particle diameters.

[0024] The inner peripheral surface of the paint receiving member extends away from the central axis from the inner bottom surface side toward the end surface.

[0025] This configuration allows the paint on the inner peripheral surface to flow from the inner bottom surface toward the end surface due to centrifugal force caused by the rotation of the paint receiver. This prevents paint from remaining near the corner where the inner bottom surface and the inner peripheral surface intersect, thereby improving the usability of the rotary bell cup sprayer. This is particularly effective when multiple types of paint need to be changed during painting.

[0026] 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 which is positioned at the tip of the paint supply pipe and inserted into the inner surface of the bell cup, wherein 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 device and rotates integrally with the bell cup via the support device. [Effects of the Invention]

[0027] As described above, the rotary bell cup coating machine can achieve finer and more uniform paint particles. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a longitudinal cross-sectional view illustrating the tip of a rotary bell cup sprayer. [Figure 2] FIG. 2 is a cross-sectional view illustrating the tip of a rotary bell cup sprayer. [Figure 3] FIG. 3 is a perspective view illustrating the configuration of the bell hub. [Figure 4] FIG. 4 is a diagram illustrating the flow of paint in a rotary bell cup sprayer. [Figure 5] FIG. 5 is an explanatory diagram showing the influence of connectors on flow in comparison. [Figure 6] FIG. 6 is a view corresponding to FIG. 1, showing a first modified example of the rotary bell cup sprayer. [Figure 7] FIG. 7 is a view corresponding to FIG. 1, showing a second modified example of the rotary bell cup sprayer. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the following description is for illustrative purposes only.

[0030] (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 AA cross-section in Fig. 1.

[0031] In the following description, the term "base end side" refers to the side of the feed tube 22 in the direction of the central axis C (the side opposite the workpiece S), and the term "tip side" refers to the side opposite 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.

[0032] The rotary bell cup coater 1 shown in Figure 1 is a rotary atomizer coating device for electrostatic coating that is configured to emit centrifugally atomized paint particles. That is, the rotary bell cup coater 1 atomizes paint by centrifugal force from a bell cup 3 attached to a rotating shaft 21 that rotates at high speed, and coats the paint by utilizing the attractive force acting between the negatively charged paint particles and the positively charged object S to be coated, such as an automobile body.

[0033] 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 arranged to surround the tip 22a of a feed tube 22 in the tubular member 2 and rotates around the central axis C of the feed tube 22, a bell hub 5 with a concave cross section arranged on the inner side of the bell cup 3 and oriented with the concave facing the paint supply pipe 2, and a support 4 for attaching the bell hub 5 to the bell cup 3.

[0034] Of these, housing 10 is formed in a cylindrical shape and houses tubular member 2 and a high-voltage power supply (not shown) for charging the paint. Furthermore, the base end of bell cup 3 is inserted into opening 10a provided at the tip of housing 10. Although not shown, air can be ejected from the tip of housing 10 to deflect paint particles.

[0035] The tubular member 2 also has a rotary shaft 21 that rotates integrally with the bell cup 3, and a feed tube 22 that is inserted into the rotary shaft 21 and discharges paint from its tip. The feed tube 22 is an example of the "paint supply pipe" in this embodiment.

[0036] Of these, the rotating shaft 21 is configured as a hollow shaft member, and is inserted into a cylindrical portion 31 on the base end side of the bell cup 3. The 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.

[0037] The feed tube 22 is configured as a tubular member that allows paint to flow through it, and is inserted into the rotary shaft 21. The tip 22a of the feed tube 22 is configured as an open end that can eject paint, and is exposed from the rotary shaft 21. The feed tube 22 according to this embodiment allows paint to flow from one side (the opposite side of the workpiece S) in the direction of the central axis C to the other side (the side of 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.

[0038] Bell cup 3 is generally cup-shaped and has a cylindrical portion 31 at the base end into which rotary shaft 21 and the like are inserted, and a tapered portion 32 at the tip end along whose inner surface paint flows.

[0039] Of these, 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 tool 4 is inserted from the tip side. An abutment portion 31a that protrudes radially inward is provided on the inner peripheral surface of the cylindrical portion 31. This abutment portion 31a is configured to abut against the support tool 4 inserted into the cylindrical portion 31, thereby positioning the support tool 4.

[0040] The inner circumferential surface of the cylindrical portion 31, which is closer to the tip than the abutted portion 31a, is adapted to allow paint scattered from the bell hub 5 by centrifugal force to flow onto this inner circumferential surface. This inner circumferential surface forms a paint diffusion surface 33 (particularly, a first diffusion surface 33a on the base end side of the paint diffusion surface 33) for diffusing the paint.

[0041] The first diffusion surface 33a of the cylindrical portion 31 gradually expands in diameter toward the tip end, and is provided so as to surround the tip end of the tubular member 2 (specifically, the tip end 22a of the feed tube 22) and the support 4 from the outer periphery. In other words, this first diffusion surface 33a overlaps with the feed tube 22 and the support 4 when viewed in a direction (radial direction) perpendicular to the central axis C. The first diffusion surface 33a is an example of a "base end side paint diffusion surface."

[0042] The tapered portion 32 has a diameter that tapers toward the tip, and the paint that has flowed along the first diffusion surface 33a flows along its inner circumferential surface. 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.

[0043] The second diffusion surface 33b in the tapered portion 32 expands in diameter more steeply toward the tip side than the first diffusion surface 33a, and is provided closer to the tip side than the tip of the tubular member 2 (specifically, the tip 22a of the feed tube 22) and the support 4. In other words, the second diffusion surface 33b does not overlap with the feed tube 22 and the support 4 when viewed in a direction (radial direction) perpendicular to the central axis C. The second diffusion surface 33b is an example of a "tip-side paint diffusion surface."

[0044] Furthermore, support 4 is disposed on the tip 22a side of feed tube 22, and is inserted into the inner peripheral side of bell cup 3. Specifically, support 4 according to this embodiment is formed in a cylindrical shape extending in the direction of central axis C, and is inserted into cylindrical portion 31 of bell cup 3 with tip 22a of feed tube 22 passing through it. In other words, the inner diameter of support 4 is larger than tip 22a of feed tube 22, and the outer diameter of support 4 is smaller than cylindrical portion 31.

[0045] Furthermore, a flange-like protruding collar portion 4a is provided on the outer surface of support device 4. When support device 4 is inserted and pushed into tubular portion 31, collar portion 4a of support device 4 abuts against abutment portion 31a of tubular portion 31. This positions support device 4 relative to bell cup 3, and particularly tubular portion 31.

[0046] 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 inner bottom surface 51 toward end surface 53. Bell hub 5 is an example of the "paint receiving member" in this embodiment.

[0047] Specifically, bell hub 5 according to this embodiment is formed in the shape of a cylinder with a bottom, with its opening and inner bottom surface 51 facing the tip 22a of 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 edge of the opening of bell hub 5. Bell hub 5 is connected to support 4 via connector 6, which will be described later, and rotates integrally with bell cup 3 via support 4.

[0048] Of these, the inner bottom surface 51 is formed as a circular flat surface and is disposed perpendicular to the central axis C, with the center of the inner bottom surface 51 (the portion corresponding to the center when the inner bottom surface 51 is considered as a circle) facing the tip 22a of the feed tube 22. By disposing it in this manner, the paint discharged from the feed tube 22 collides with the center of the inner bottom surface 51.

[0049] Next, the inner circumferential surface 52 is formed as a substantially cylindrical curved surface, and extends substantially perpendicularly from the periphery of the inner bottom surface 51 toward the base end. Here, the inclination angle θ that the inner circumferential surface 52 forms with respect to the inner bottom surface 51 is slightly obtuse than 90 degrees. That is, the inner circumferential surface 52 according to this embodiment extends so as to become increasingly distant from the central axis C (i.e., toward the radially outward direction) as it extends from the inner bottom surface 51 toward the end surface 53. In addition, as shown enlarged in FIG. 1, a radius is provided at the corner where the inner bottom surface 51 and the inner circumferential surface 52 intersect, and the inner bottom surface 51 and the inner circumferential surface 52 are smoothly connected.

[0050] Here, connectors 6 for connecting the feed tube 22 and the bell hub 5, which serves as a paint receiving member, are provided on the inner circumferential surface 52. 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 according to this embodiment are bolt-shaped fastening members, and are provided at multiple locations at equal intervals (in the example shown in FIG. 2, at three locations every 120 degrees) along the circumferential direction about the central axis C. Each connector 6 extends in a direction substantially perpendicular to the inner circumferential surface 52.

[0051] 1, when the inner circumferential surface 52 is connected to the support 4 by the connector 6, it faces the outer circumferential surface of the support 4 (particularly the outer circumferential surface further towards the tip than the flange 4a) with a gap therebetween. 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.

[0052] Furthermore, end face 53 is formed as a substantially annular flat surface, and extends from the end portion on the base end side of inner circumferential surface 52 along a plane perpendicular to central axis C. When connected to support 4 by connector 6, this end face 53 faces flange 4a of support 4 with a gap therebetween, as shown in FIG. 1. This allows paint to flow through the gap between end face 53 of bell hub 5 and flange 4a of support 4.

[0053] Bell hub 5 according to this embodiment is disposed radially inward of bell cup 3, and is inserted in the direction of central axis C up to cylindrical section 31 on the base end side beyond tapered section 32. In other words, inner peripheral surface 52 and end face 53 of bell hub 5 overlap first diffusion surface 33a when viewed in a direction perpendicular to the direction of central axis C.

[0054] Additionally, the outer periphery 54 on the end face 53 side of the bell hub 5 is formed so as to taper 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 all around in the circumferential direction. The tip of the outer periphery 54 forms an acute angle of less than 90 degrees.

[0055] (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.

[0056] The bell hub 5, which serves as a paint receiving member, is configured to rotate 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 surface 52 and end surface 53 of the bell hub 5.

[0057] This configuration will be described in detail below. First, when the rotary shaft 21 rotates around the central axis C, the bell cup 3 rotates integrally therewith. As the bell cup 3 rotates, the support 4, and therefore the bell hub 5, also rotate integrally.

[0058] 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. The paint that has reached the center of the inner bottom surface 51 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.

[0059] The paint flowing along the inner bottom surface 51 passes through this inner bottom surface 51 and reaches the inner circumferential surface 52. The paint that has reached the inner circumferential surface 52 forms a parallel flow that flows approximately in the direction of the central axis C, and flows toward the base end along the inner circumferential surface 52 as shown by arrow A3.

[0060] The paint flowing along inner circumferential surface 52 is impeded by connector 6, and passes through inner circumferential surface 52 to reach end surface 53. Upon reaching end surface 53, the paint again forms a diffusive flow and flows radially outward along end surface 53 as indicated by arrow A4.

[0061] 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. The paint that has reached the first diffusion surface 33a passes through the first diffusion surface 33a and the second diffusion surface 33b in that order 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 atomized and released.

[0062] (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.

[0063] In contrast, in this embodiment, the 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 of the present application, 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 liquid film can be made uniform. This makes it possible to suppress rippling of the paint liquid film caused by flow obstruction due to eccentricity with respect to the central axis C of the impinging paint.

[0064] Furthermore, by suppressing rippling of the paint before it transfers from the bell hub 5 to the bell cup 3, it is possible to keep the thickness of the paint liquid film as uniform as possible, even 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.

[0065] As explained with reference to FIG. 4, the 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, the paint flowing along the inner peripheral surface 52 of the bell hub 5 flows substantially 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 FIG. 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 diverged. 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 substantially parallel.

[0066] Therefore, as illustrated 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 as an obstacle on the flow is suppressed, which is advantageous in achieving finer and more uniform paint particle diameters.

[0067] 4, paint that has transferred from the end surface 53 of the bell hub 5 to the bell cup 3 flows over the first diffusion surface 33a on the base end side of the inner circumferential surface of the bell cup 3, in addition to the second diffusion surface 33b on the tip 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 realizing finer and more uniform paint particle diameters.

[0068] As explained using Figure 4, paint attempting to transfer from bell hub 5 to bell cup 3 flies from outer periphery 54 on the end face 53 side of bell hub 5 to bell cup 3, but by tapering outer periphery 54, the paint flies from the tip of the tapered part.

[0069] If the outer periphery 54 were rounded, the paint adhering to the outer periphery 54 would fly off from each of the rounded portions due to surface tension. In this case, the paint would flow unevenly, which would be disadvantageous in terms of achieving finer and more uniform paint particle diameters.

[0070] On the other hand, according to this embodiment, as shown in Fig. 4, the paint flies from a specific portion (the tip of the tapered portion) on the outer circumferential portion 54. This keeps the paint flow distance approximately constant, which is advantageous in realizing finer and more uniform paint particle diameters.

[0071] 1, the inner circumferential surface 52 of the bell hub 5 extends away from the central axis C as it moves 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.

[0072] (Bellhub's first variant) FIG. 6 is a view corresponding to FIG. 1, showing a first modified example of the rotary bell cup sprayer 1. In FIG.

[0073] In the above embodiment, the connector 6 is 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 according to 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 according to 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 both coincide with the direction of the central axis C, making it easier to assemble the rotary bell cup sprayer 101.

[0074] (Bellhub's second variant) FIG. 7 is a view corresponding to FIG. 1, showing a second modified example of the rotary bell cup sprayer 1. In FIG.

[0075] In the above embodiment, the paint is sprayed from the end face 53 of the bell hub 5 and reaches the inner circumferential surface of the bell cup 3, but this configuration is not limited to this. For example, in the rotary bell cup sprayer 201 according to the second modified example, the end face 253 of the bell hub 205 is shaped to fit the inner circumferential surface 233 of the bell cup 203, and they face each other 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 circumferential surface 233 of the bell cup 203.

[0076] Other Embodiments Furthermore, in the above embodiment, the first diffusion surface 33a of the bell cup 3 was 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 splashes 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. [Explanation of symbols]

[0077] 1 Rotating Bell Cup Painter 2 Tubular member 21 Rotation axis 22 Feed tube (paint supply pipe) 3 Bell Cup 33 Paint diffusion surface 33a First diffusion surface (base end paint diffusion surface) 33b Second diffusion surface (tip side paint diffusion surface) 4 Supports 5 Bell hub (paint receiving part) 51 Inner bottom surface 52 Inner surface 53 End face 54 Outer periphery 6 Connectors C center axis S Object to be painted

Claims

1. 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 is configured to rotate around the central axis together with the bell cup so that paint discharged from the paint supply pipe toward the inner bottom surface reaches the inner peripheral surface of the bell cup via the inner peripheral surface and the end surface. A rotary bell cup coating machine characterized by:

2. 2. The rotary bell cup sprayer according to claim 1, a connector provided on the inner peripheral surface of the paint receiving member for connecting the bell cup and the paint receiving member; A rotary bell cup coating machine characterized by:

3. 3. The rotary bell cup sprayer according to claim 2, The connector is provided on a part of the inner circumferential surface of the paint receiving member in the circumferential direction around the central axis. A rotary bell cup coating machine characterized by:

4. 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, The connectors each extend in a direction perpendicular to the inner circumferential surface of the paint receiving member. A rotary bell cup coating machine characterized by:

5. 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, The inner peripheral surface and the end surface of the paint receiving member overlap with the base end side paint spreading surface when viewed in a direction perpendicular to the central axis direction. A rotary bell cup coating machine characterized by:

6. The rotary bell cup sprayer according to any one of claims 1 to 5, The outer periphery of the end face of the paint receiving member is tapered radially outward. A rotary bell cup coating machine characterized by:

7. The rotary bell cup sprayer according to any one of claims 1 to 6, The inner peripheral surface of the paint receiving member extends away from the central axis from the inner bottom surface side toward the end surface. A rotary bell cup coating machine characterized by:

8. 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, The paint receiving member is connected to the support and rotates integrally with the bell cup via the support. A rotary bell cup coating machine characterized by:

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