JP4826280B2 - Rotating atomizing head and design method of rotating atomizing head - Google Patents

Description

  The present invention relates to a rotary atomizing head used in a bell type coating machine and a method for designing a rotary atomizing head.

  In recent years, base coating using a bell type coating machine has been generalized. In this coating method, the base paint atomized by the centrifugal force of the rotating rotary atomizing head is struck against the object to be coated with strong shaving air to promote the orientation of the glittering material, and as a result, the color can be ensured ( For example, see Patent Document 1).

  However, since this coating method requires strong shaving air, there are many drawbacks in that the coating particles rebound and high coating efficiency cannot be obtained. For this reason, the bell that has been generally rotated at 30,000 rpm or less is rotated at a higher speed so that the paint is uniformly finely divided, and the splash of the paint particles is suppressed to promote the thinning of the object to be coated. Can do.

However, in such high-speed rotation, an excessive centrifugal force acts on the rotary atomizing head, causing a problem in strength, and a problem that rotation control becomes difficult due to an increase in the moment of inertia.
JP-A-3-30849

  The present invention has been made to solve the problems associated with the above-described prior art, and provides a rotary atomizing head and a rotary atomizing head design method capable of reducing weight while maintaining strength even at high speed rotation. With the goal.

A rotary atomizing head according to the present invention that achieves the above object has a cylindrical cylindrical portion and an inner surface that has the same central axis as the cylindrical portion and that is inclined and extended in a direction away from the central axis from one end of the cylindrical portion. And an outer surface portion having the same central axis as the cylindrical portion and extending from the other end of the cylindrical portion to the extending direction end portion of the inner surface portion, and the outer surface of the inner surface portion is recessed in a bell shape The thickness of the inner surface portion is reduced to less than half from the side closer to the central axis toward the side farther from the central axis.

The design method of the rotary atomizing head according to the present invention that achieves the above object has a cylindrical cylindrical portion and the same central axis as the cylindrical portion, and is inclined in a direction away from the central axis from one end of the cylindrical portion. An inner surface portion that extends, and an outer surface portion that has the same central axis as the cylindrical portion and extends from the other end of the cylindrical portion to an end portion in the extending direction of the inner surface portion, and the plate thickness of the inner surface portion is the center This is a design method for a rotary atomizing head whose outer surface is reduced to less than half from the side closer to the axis toward the far side, and the outer surface of the inner surface is recessed in a bell shape. A step of determining an inclination angle formed by an outer surface of the inner surface portion with respect to a vertical plane of the central axis, a step of performing a structural analysis using the finite element method analysis model, and an evaluation as a result of the structural analysis Modifying the analysis model if the parameter is not within the reference value, And butterflies.

  In the rotary atomizing head according to the present invention configured as described above, the plate thickness of the inner surface portion is decreased from the side closer to the central axis toward the side farther away, so that rotation with a high contribution rate to centrifugal force during rotation is achieved. The outer portion is reduced in weight, and the rotary atomizing head can be reduced in weight while suppressing an increase in centrifugal force during high-speed rotation. Further, by reducing the weight, the rotational speed can be controlled accurately and quickly.

Times Utatekiri Kaatama the inner surface and the outer surface portion lever rib is provided between the strength can be thinner inner surface and an outer surface portion while maintaining, reducing the weight and generating a centrifugal force to it can. Further, by reducing the weight, the rotational speed can be controlled accurately and quickly.

  The design method of the rotary atomizing head according to the present invention configured as described above is designed to correct the finite element method analysis model based on the analysis result. Design becomes possible.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

<First Embodiment>
FIG. 1 is a partial cross-sectional view showing a bell type coating machine, FIG. 2 is a perspective view showing a rotary atomizing head according to the present embodiment, and FIG. 3 is a cross-sectional view showing the rotary atomizing head according to the first embodiment. .

  As shown in FIG. 1, the bell type coating machine 1 has a bell type rotary atomizing head 2 that is rotated at high speed by an air motor (not shown).

  The rotary atomizing head 2 according to the first embodiment has a hollow portion 6 formed therein, and has a cylindrical cylindrical portion 3 and the same central axis as the cylindrical portion 3, from one end of the cylindrical portion 3. An inner surface portion 4 that extends while being inclined away from the central axis, and an outer surface portion 5 that has the same central axis as the cylindrical portion 3 and extends from the other end of the cylindrical portion 3 to an end portion in the extending direction of the inner surface portion 4. , And the outer surface of the inner surface part 4 has a shape recessed in a bell shape. A hub member 8 is attached to the rotary atomizing head 2 so that a space 7 is formed at the center of rotation.

  The rotary atomizing head 2 is connected to a drive shaft 9 that is driven to rotate by an air motor and has a rotatable structure.

  Further, a supply pipe 10 extending to the space portion 7 of the rotary atomizing head 2 is provided inside the drive shaft 9, and the paint is supplied to the space portion 7 through the supply pipe 10. The coating material supplied to the space portion 7 is leaked to the outside through a plurality of through holes 11 provided in the hub member 8, and moves along the outer surface of the inner surface portion 4 by the centrifugal force accompanying the rotation. It is atomized and sprayed from the outer edge of the shape. A high voltage is applied to the rotary atomizing head 2, and the supplied paint can be charged. The finely charged charged paint particles are in the opening direction of the rotary atomizing head 2 and the rotary atomizing head 2. It moves along the electrostatic field formed between the object to be coated and is applied to the object to be coated.

  A shaving air nozzle 12 formed in a ring shape is provided outside the rotary atomizing head 2 so as to surround the rotary atomizing head 2, and the rotary atomizing head 2 is generated by the shaving air discharged from the shaving air nozzle 12. The paint sprayed from is patterned into an object to be coated.

  As shown in FIG. 3, the inner surface 4 of the rotary atomizing head 2 has a plate thickness t1 far from the central axis that is half or less of a plate thickness t2 near the central axis, and is continuous toward the far side. It is thinner.

  Further, the plate thickness t3 of the outer surface portion 5 of the rotary atomizing head 2 is formed to be less than half of the plate thickness h2 on the side close to the central axis of the inner surface portion 4. In the present embodiment, the plate thickness t3 is constant over the entire outer surface portion 5. Note that the thickness t3 of the outer surface portion 5 may not be constant over the entire surface, and may be formed continuously thin, for example, toward the side far from the central axis.

The centrifugal force (M · R · ω ² ) acting on the rotary atomizing head 2 is proportional to the mass M and the rotation radius R, and is also proportional to the square of the angular velocity ω, so that it is particularly away from the rotation axis (the rotation radius R). If the mass of the part is large, the centrifugal force becomes excessive, which may cause a problem in strength. However, in the rotary atomizing head 2 of the present embodiment, the plate thickness t1 of the portion away from the central axis of the inner surface portion 4 is less than half of the plate thickness t2 on the side close to the central axis. Thus, it is possible to reduce the weight of the rotary atomizing head while suppressing an increase in centrifugal force during high-speed rotation. Further, since the plate thickness t3 of the outer surface portion 5 located farther from the central axis than the inner surface portion 4 is half or less of the plate thickness t2 on the side closer to the central axis of the inner surface portion 4, the weight can be reduced similarly. Generation of excessive centrifugal force can be suppressed. In the present embodiment, the weight can be reduced by about 30% with respect to the conventional model, and at the same time, the position of the center of gravity can be brought closer to the rotating shaft. In the rotary atomizing head 2 having such a structure, the acting centrifugal force can be reduced to less than half that of the conventional product.

  FIG. 4 is a graph showing the relationship between the supply pressure of the rotary atomizing head and the rotational speed according to the present embodiment.

  As shown in FIG. 4, with the conventional rotary atomizing head, the rotational speed was assumed to be used in the vicinity of A1 (30,000 rpm), so the weight was heavy and the rotational speed A2 (60,000 rpm) approaching the speed of sound. Can't reach. However, in the embodiment according to the present invention, since the weight is reduced, the rotation can exceed 60,000 rpm. Therefore, fine particles of the generated paint can be obtained more finely and uniformly, and the coating efficiency of the paint on the object can be improved.

  Furthermore, since the rotary atomizing head 2 is reduced in weight, the moment of inertia is also reduced, and the rotational speed can be controlled quickly and accurately.

  Moreover, since the rotary atomizing head 2 can be reduced in weight, the rotary atomizing head 2 having a large diameter and a maximum discharge amount of about 500 cc / min (usually about 100 to 200 cc / min) is used even in high-speed bell painting. It becomes possible to do.

Second Embodiment
FIG. 5 is a cross-sectional view showing a rotary atomizing head according to the second embodiment. In addition, about the site | part which has a function similar to 1st Embodiment, in order to avoid duplication, the description is abbreviate | omitted in order to avoid duplication.

  As shown in FIG. 5, the rotary atomizing head 2 ′ according to the second embodiment has a form in which the plate thickness of the first embodiment is further reduced. In addition, the rotary atomizing head 2 does not limit the plate thicknesses t1 ′, t2 ′, and t3 ′ (corresponding to the plate thicknesses t1, t2, and t3 of the first embodiment), but compensates for insufficient strength due to thinning. For this purpose, ribs 13 are provided in the hollow portion 6. The rib 13 is formed in a cylindrical shape having the same central axis as the inner surface portion 4, and is formed so as to pass between the inner surface portion 4 and the outer surface portion 5 by the hollow portion 6. By providing such a rib 13, it is possible to prevent a decrease in strength while reducing the thickness and weight of the inner surface portion 4 and the outer surface portion 5, for example, when it is necessary to reduce the thickness of the rotary atomizing head 2, This is effective when it is difficult to set the plate thickness distribution difference. A plurality of ribs 13 may be provided.

  Further, as in the first embodiment, ribs 13 may be further provided as in the second embodiment while limiting the plate thicknesses t1 ', t2', and t3 '.

  In addition, since the effect by thickness reduction and weight reduction of 2nd Embodiment is the same as the effect of 1st Embodiment, description is abbreviate | omitted.

  Next, a method for designing a rotary atomizing head according to the present embodiment will be described.

  FIG. 6 is a flowchart for explaining a design method of the rotary atomizing head according to the present embodiment, and FIG. 7 is a cross-sectional view showing a load application position in the analysis of the rotary atomizing head according to the present embodiment. A) shows concentrated load, (B) shows analysis by rotational load, and FIG. 8 is a cross-sectional view showing an analysis result by rotational load of the rotary atomizing head according to the present embodiment. 7 and 8, since the rotary atomizing head 2 has a symmetrical shape, only half of the cross section is shown.

  For the design of the rotary atomizing head 2, a structural analysis method by a finite element method (FEM) is used.

  First, the material constants (for example, specific gravity, Young's modulus and Poisson's ratio) of the materials used, the parameters of the outer surface portion 5 (outer diameter, shape and thickness t3, etc.), the parameters of the inner surface portion 4 (outer diameter, shape and The plate thicknesses t1, t2, etc.) are determined and input to the computer, and an FEM analysis model is created (S1).

  Next, it is determined whether the inclination angle θ of the outer surface of the inner surface portion 4 with respect to the rotation axis vertical surface can be changed in design (S2). If the inclination angle θ cannot be changed due to some restrictions, the process proceeds to step S4 described later.

  If the inclination angle θ can be changed, a plurality of analysis models are created in which the inclination angle θ is changed every one degree within a predetermined α degree with respect to the reference value θi (S3). Here, the angle at which the inclination angle θ is changed does not necessarily have to be 1 degree.

  Next, using the created analysis model, a structural analysis with a concentrated load and / or a structural analysis with a rotational load is performed (S4). In the structural analysis with the concentrated load added, the concentrated load F is applied to the annular outer peripheral end portion of the inner surface portion 4 from the axial direction (see FIG. 7A). Moreover, in the structural analysis to which a rotational load is added, for example, a rotational load for each predetermined rotational speed is applied (see FIG. 7B).

  Next, based on the above analysis result, an inclination angle θ that can reduce the weight most is determined (S5). At this time, the weight of the rotary atomizing head 2 increases as the tilt angle θ increases, and the deformation due to the acting centrifugal force increases as the inclination angle θ decreases.

  Next, it is determined whether the weight (evaluation parameter) of the rotary atomizing head 2 is equal to or less than a target value (S6). If this condition is not satisfied, the design is changed by adjusting the thickness t3 of the outer peripheral portion (S7), and the process returns to step S1. If the condition of step S6 is satisfied, it is determined whether the maximum stress and the maximum deflection amount (evaluation parameter) generated in the rotary atomizing head 2 are equal to or less than the reference value (S8). If the condition of step S8 is satisfied, the optimum design shape of the rotary atomizing head 2 is determined (S9), and the design is completed. When the condition of step S8 is not satisfied, it is selected whether or not the rib 13 is added (S10). When the rib 13 is not added, the design is changed by adjusting the thickness t3 of the outer peripheral portion (S7), and the process returns to step S1. When the rib 13 is added, the most bent portions P1 and P2 of the inner surface portion 4 and the outer surface portion 5 are specified from the analysis result in step S4 (see FIG. 8), and the tubes are provided so as to pass the respective portions. An analysis model to which the shaped ribs 13 are added is created (S11).

  Next, after an analysis model is created in step S11, a structural analysis with a concentrated load and / or a structural analysis with a rotational load is performed using the analysis model (S12). Then, it returns to the process of step S6 and it is judged again whether the weight of the rotary atomizing head 2 is below a target value (S6).

  By using such a design method, it is possible to optimally design any material and shape of a high rotation paint bell.

  Next, an analysis example of the rotary atomizing head designed by the rotary atomizing head design method according to the present embodiment is shown.

  FIG. 9 is a cross-sectional view showing an analysis model of a rotary atomizing head, where (A) is a rotary atomizing head, (B) is an analytical model 1 corresponding to the rotary atomizing head according to the first embodiment, and (C). Shows an analysis model 2 corresponding to the rotary atomizing head according to the second embodiment. In FIG. 9, since the rotary atomizing head has a symmetrical shape, only half of the cross section is shown.

  The material of the rotary atomizing head 2 of each analysis model is titanium, and the outer diameter D1, the inner diameter D2, D3, and the length L are the same.

<Analysis example 1>
First, as an analysis example 1, an example in which a concentrated load is applied to the rotary atomizing head 2 of the above-described conventional model and analysis models 1 and 2 will be described.

  Table 1 shows the analysis result by the concentrated load of the rotary atomizing head according to this analysis example.

  As analysis conditions for analysis by concentrated load, the concentrated load was set to 10 kgf and added to the annular outer peripheral end portion of the inner surface portion 4 from the axial direction (see FIG. 7A).

  In the analysis by concentrated load, the maximum stress must be below the fatigue limit of the material (650 Mpa for titanium in this analysis example), and the maximum displacement must be below the reference value (0.02 mm in this analysis example). .

  From Table 1, the maximum stress of the analysis models 1 and 2 is 650 MPa or less, which is the fatigue limit, and the maximum displacement is lower than the reference value of 0.02 mm. As described above, the maximum stress and the maximum displacement can be set to the reference value or less even if the rotary atomizing heads 2, 2 'are thinned as in the analysis models 1, 2 (first and second embodiments). It is.

<Analysis example 2>
Next, as an analysis example 2, an example in which a rotational load is applied to the rotary atomizing heads of the above-described conventional model and analysis models 1 and 2 will be described.

  Table 2 shows an analysis result based on the rotational load of the conventional rotary atomizing head (conventional model). Table 3 shows an analysis result based on the rotational load on the rotary atomizing head (analysis model 1) corresponding to the first embodiment. These are the analysis results by the rotational load of the rotary atomization head (analysis model 2) corresponding to 2nd Embodiment.

  In Analysis Example 2, a rotational load of 10,000 rpm was applied from 60,000 rpm to 100,000 rpm (see FIG. 7B).

  In the analysis by the rotational load, the maximum stress is below the fatigue limit of the material (650 Mpa for titanium in this analysis example), and the maximum displacement is a reference value (in this analysis example, 0.1 mm at 80,000 rpm, 80,000 rpm) 0.2 mm) or less.

  As shown in Tables 2 to 4, it was confirmed that the maximum stress and the maximum displacement amount of the analysis models 1 and 2 satisfied the design criteria. As described above, even when the rotary atomizing heads 2 and 2 'are thinned, the maximum stress and the maximum displacement can be set to be equal to or less than the reference values.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. For example, as shown in the plan view of the rotary atomizing head shown in FIG. 10, the plurality of ribs 23 may be formed radially so as to pass between the inner surface portion 4 and the outer surface portion 5 by the hollow portion 6.

It is a fragmentary sectional view which shows a bell type coating machine. It is a perspective view which shows the rotary atomization head which concerns on this embodiment. It is sectional drawing which shows the rotary atomization head which concerns on 1st Embodiment. It is a graph which shows the relationship between the supply pressure and rotational speed of the rotary atomization head which concern on this embodiment. It is sectional drawing which shows the rotary atomization head which concerns on 2nd Embodiment. It is a flowchart for demonstrating the design method of the rotary atomization head which concerns on this embodiment. It is sectional drawing which shows the load addition position in the analysis of the rotary atomization head which concerns on this embodiment, (A) shows the concentrated load and (B) shows the analysis by a rotational load. It is sectional drawing which shows the analysis result by the rotational load of the rotary atomization head which concerns on this embodiment. It is sectional drawing which shows the analysis model of a rotation atomization head, (A) is a rotation atomization head, (B) is the analysis model 1 corresponding to the rotation atomization head which concerns on 1st Embodiment, (C) is 2nd. The analysis model 2 corresponding to the rotary atomization head which concerns on embodiment is shown. It is a top view which shows the other example of the rotary atomization head which concerns on this invention.

Explanation of symbols

1 Bell type coating machine,
2,2 'rotating atomizing head,
3 cylinder part,
4 inner surface,
5 outer surface,
6 hollow part,
7 Space part,
8 Hub member,
9 Drive shaft,
10 supply pipe,
11 Through hole,
12 Shaving air nozzle,
13 ribs,
t1, t1 ′ the thickness of the inner surface (the side far from the inner surface),
t2, t2 ′ thickness of the inner surface (side closer to the inner surface),
t3, t3 ′ Thickness of the outer surface portion.

Claims (11)

A cylindrical tube portion, an inner surface portion having the same central axis as the cylindrical portion, extending from the end of the cylindrical portion so as to be inclined away from the central axis, and a cylindrical tube having the same central axis as the cylindrical portion An outer surface portion extending from the other end of the portion to the end portion in the extending direction of the inner surface portion, and a rotary atomizing head having a shape in which the outer surface of the inner surface portion is recessed in a bell shape,
The rotary atomizing head characterized in that the plate thickness of the inner surface portion is reduced to less than half from the side closer to the central axis toward the side farther from the central axis. Thickness of the outer surface portion, the rotary atomizing head according to claim 1, wherein less than half of the side plate thickness close to the center axis of the inner surface portion. Between the front Symbol inner surface and an outer surface portion, the rotary atomizing head according to claim 1 or 2, characterized in that the ribs are provided. The rotary atomizing head according to claim 3 , wherein the rib has a cylindrical shape having the same central axis as the inner surface portion and the outer surface portion. The rotary atomizing head according to claim 3 , wherein the rib extends in a direction away from a central axis of the inner surface portion and the outer surface portion. A cylindrical tube portion, an inner surface portion having the same central axis as the cylindrical portion, extending from the end of the cylindrical portion so as to be inclined away from the central axis, and a cylindrical tube having the same central axis as the cylindrical portion An outer surface portion extending from the other end of the inner portion to the end portion in the extending direction of the inner surface portion, and the thickness of the inner surface portion is reduced to less than half from the side closer to the central axis to the far side, and the inner surface portion Is a method of designing a rotary atomizing head having a bell-shaped outer surface,
Creating a finite element analysis model of the rotary atomizing head;
Determining an angle of inclination formed by an outer surface of the inner surface portion with respect to a central axis vertical plane;
Performing structural analysis with the finite element method analysis model;
And a step of correcting the analysis model when an evaluation parameter as a result of the structural analysis is not within a reference value. The step of determining the tilt angle is performed by preparing a plurality of finite element method analysis models having tilt angles within a predetermined angle range and comparing the analysis results of the respective finite element method analysis models, The method for designing a rotary atomizing head according to claim 6 . The rotary atomization according to claim 6 or 7 , wherein the step of performing the structural analysis by the finite element method analysis model performs at least one of a structural analysis with a rotational load and a structural analysis with a concentrated load. Head design method. The method for designing a rotary atomizing head according to any one of claims 6 to 8 , wherein the evaluation parameters are weight, maximum stress, and maximum amount of deflection. The method for designing a rotary atomizing head according to any one of claims 6 to 9 , wherein the step of correcting the analysis model adjusts a plate thickness of an outer surface portion. The method of designing a rotary atomizing head according to any one of claims 6 to 9 , wherein in the step of correcting the analysis model, a rib is provided between the inner surface portion and the outer surface portion.

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