Method for manufacturing a vehicle wheel

Abstract

To manufacture a vehicular wheel suppressed in color shading caused by a casing phenomenon.SOLUTION: A method for manufacturing a vehicular wheel comprises: a forming step of forming a wheel body of a metal wheel of a vehicle; a first coating step of coating the wheel with first paint for forming a colored clear coating film; a second coating step of coating the wheel with second paint for forming a colorless clear coating film having optical transparency higher than that of the colored clear coating film on a region coated with the first paint; and a printing and drying step of printing and drying the first paint and the second paint applied on the wheel to form the colored clear coating film and the colorless clear coating film. The flowability the first paint during printing and drying is lower than that of the second paint during printing and drying.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a method for manufacturing a vehicle wheel. [Background technology]

[0002] Conventionally, a method for manufacturing a vehicle wheel has been known in which, for example, to enhance the design, a portion of the wheel body is cut to form a shiny surface, a colored clear coat layer is formed on this shiny surface, and a matte top clear coat layer is formed on the color clear coat layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-221575 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional manufacturing method described above, when the paint used to form the color clear coat layer is baked and dried, a so-called "frame effect" occurs in the color clear coat layer. In other words, the paint applied near the edge of the shiny surface of the wheel body has high surface tension due to the thinner volatilizing quickly at the surface, pulling the paint inside. As a result, the thickness of the color clear coat layer near the edge of the wheel body becomes thicker. Such variations in the thickness of the color clear coat layer can result in differences in the apparent color intensity of the wheel surface, affecting the aesthetics of the wheel.

[0005] Incidentally, such variations in the film thickness of the color clear coat layer due to uneven surface tension of the paint are not limited to cases where the wheel body has an edge portion, but can also occur, for example, when the wheel body has a complex shape with suddenly changing curves.

[0006] This specification discloses a technique that can solve the above-mentioned problems. [Means for solving the problem]

[0007] The technology disclosed in this specification can be realized in the following forms.

[0008] (1) The method for manufacturing a vehicle wheel disclosed in this specification includes a forming step of forming a wheel body of a metal vehicle wheel, a first coating step of applying a first paint to the wheel body to form a colored clear coating film, a second coating step of applying a second paint to the area of ​​the wheel body where the first paint has been applied to form a colorless clear coating film, and a baking and drying step of baking and drying the first paint and the second paint applied to the wheel body to form the colored clear coating film and the colorless clear coating film, wherein the fluidity of the first paint when baked and dried is lower than the fluidity of the second paint when baked and dried.

[0009] In this vehicle wheel manufacturing method, the fluidity of the first paint for forming the colored clear coating film during baking and drying is lower than the fluidity of the second paint for forming the colorless clear coating film during baking and drying. Therefore, the colored clear coating film can suppress variations in film thickness caused by uneven surface tension compared to the colorless clear coating film. Furthermore, variations in film thickness of the colorless clear coating film have a smaller impact on the aesthetic appearance of the wheel compared to variations in film thickness of the colored clear coating film. As a result, this vehicle wheel manufacturing method can manufacture vehicle wheels in which the effects of variations in the clear coating film thickness are suppressed.

[0010] (2) In the above-mentioned method for manufacturing a vehicle wheel, in the forming process, a shiny surface is formed on the surface of the wheel body by using cutting processing, and an edge portion remains on the edge of the shiny surface, and in the first application process, the first paint is applied to an area of ​​the wheel body that includes at least the shiny surface and the edge portion, and in the second application process, the second paint is applied on top of the first paint that has been applied to the area that includes the shiny surface and the edge portion.

[0011] When using wheels with edges formed by cutting, variations in the thickness of the colored clear coating film are likely to occur, particularly near the edges, due to the framing phenomenon. Furthermore, shiny surfaces formed by cutting are likely to be significantly affected by color unevenness due to variations in the thickness of the colored clear coating film, caused by light that passes through the colored clear coating film and is reflected by the shiny surface. In contrast, this vehicle wheel manufacturing method makes it possible to manufacture vehicle wheels in which variations in the thickness of the clear coating film are effectively suppressed, even when using wheels with such edges and shiny surfaces.

[0012] The techniques disclosed in this specification can be realized in various forms, for example, in the form of a vehicle wheel, a manufacturing method thereof, etc. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an XZ plan view showing a schematic external configuration of a vehicle wheel 100 according to an embodiment. [Figure 2] 1 is an explanatory diagram showing a schematic XY cross-sectional configuration of a vehicle wheel 100. FIG. [Figure 3] 3 is a flowchart showing the manufacturing process of the vehicle wheel 100. [Figure 4] 2 is an explanatory diagram showing a part of the manufacturing process of the vehicle wheel 100. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] A. Implementation: A-1. Configuration of vehicle wheel 100: FIG. 1 is an XZ plan view that schematically shows the external configuration of a vehicle wheel 100 (hereinafter simply referred to as "wheel 100") according to this embodiment. FIG. 2 is an explanatory diagram that schematically shows the XY cross-sectional configuration of the wheel 100 according to this embodiment. FIG. 2 shows the XY cross-sectional configuration of a spoke portion 210 of the wheel 100 at the position II-II in FIG. 1. Each figure shows mutually orthogonal X, Y, and Z axes for specifying directions. For convenience, in this specification, the Y-axis direction is assumed to be parallel to the rotation axis of the wheel 100 and will be referred to as the "wheel axial direction" below, although the wheel 100 may actually be disposed in an orientation different from this orientation. Hereinafter, the radial direction of the wheel 100 will be referred to as the "wheel radial direction."

[0015] As shown in Figure 2, the wheel 100 has a color base coat layer 300, a color clear coat layer 310, and a top clear coat layer 320 formed on the surface of a wheel material 102. After being formed in a molding process (S110 in Figure 3) described below, the wheel material 102 goes through painting processes (S120, S140, S150), a cutting process (S130), and a baking and drying process (S160) to become the wheel 100. Here, for convenience, the material of the wheel 100 used in each process will be referred to as the wheel material 102. The color clear coat layer 310 is an example of a colored clear coating film in the claims, and the top clear coat layer 320 is an example of a colorless clear coating film in the claims.

[0016] The wheel material 102 is formed from a light metal such as an aluminum alloy or a magnesium alloy. The wheel material 102 includes a substantially cylindrical wheel rim 10 and a wheel disc 20 disposed on the inner periphery of the wheel rim 10. The wheel material 102 of this embodiment is a so-called one-piece type wheel in which the wheel rim 10 and the wheel disc 20 are integrally molded. Hereinafter, one side of the wheel 100 (wheel material 102) in the wheel axial direction (positive Y-axis side) will be referred to as the "outer side," and the other side of the wheel axial direction (negative Y-axis side) will be referred to as the "inner side." When the wheel 100 is mounted on a vehicle body (not shown), the outer side of the wheel 100 faces away from the vehicle body, and the inner side of the wheel 100 faces toward the vehicle body. The outer side of the wheel 100 is the design surface.

[0017] (Wheel rim 10) As shown in FIG. 1, the wheel rim 10 is generally cylindrical overall and includes a cylindrical portion (not shown) and a pair of flange portions 110 (only the outer flange portion 110 is shown in FIG. 1). The cylindrical portion is cylindrical and has a well portion and the like formed therein. The pair of flange portions 110 are generally annular when viewed in the wheel axial direction (Y-axis direction), and are located at both ends of the cylindrical portion in the wheel axial direction. The pair of flange portions 110 hold a tire (not shown) mounted on the wheel 100 so that it does not shift in the wheel axial direction.

[0018] (Wheel disc 20) The wheel disc 20 is located on the outer side of the wheel rim 10 and includes a hub attachment portion 220 and a plurality of spoke portions 210 (five in this embodiment). The hub attachment portion 220 is generally disk-shaped and is located approximately in the center of the wheel disc 20 when viewed in the wheel axial direction (Y-axis direction). A hub hole 222 is formed approximately in the center of the hub attachment portion 220 to which a hub (not shown) of the vehicle body is connected. In addition, a plurality of bolt holes 224 are formed around the hub hole 222 to secure the wheel 100 to the hub of the vehicle body.

[0019] The multiple spokes 210 are arranged radially between the wheel rim 10 and the hub attachment portion 220. Each spoke 210 extends in the radial direction of the wheel. An opening (air hole) 12 is formed between adjacent spokes 210. The opening 12 has a substantially triangular shape, but is not limited to this and may have a substantially rectangular shape, for example. Each spoke 210 extends to the flange portion 110 of the wheel rim 10.

[0020] 1, the outer surface (design surface) of the wheel material 102 on the outer side has a shiny surface 230 and a plurality of inclined surfaces 250. The wheel material 102 also has an edge portion 240 where the shiny surface 230 and the inclined surfaces 250 intersect.

[0021] The shiny surface 230 is a surface whose normal extends parallel to or intersects with the wheel axial direction. Specifically, the shiny surface 230 is the outermost surface of the outer surface of the wheel material 102 between the hub attachment portion 220 and the spoke portion 210. The shiny surface 230 is a flat surface that is approximately perpendicular to the wheel axial direction. Each inclined surface 250 is a frame-shaped portion of the outer surface of the wheel material 102 that defines the opening 12. Each inclined surface 250 is a surface that is inclined with respect to the shiny surface 230. Specifically, as shown in FIG. 2, the inclined surface 250 is inclined with respect to the wheel axial direction (Y-axis direction) so that the opening area of ​​the opening 12 expands toward the outer side. The inclined surface 250 may be flat or curved.

[0022] The color base coat layer 300 is a colored layer (e.g., a black-based color) formed by applying a base paint to the inclined surface 250 of the wheel material 102. The color base coat layer 300 may be a chromatic colored layer or an achromatic colored layer. The color base coat layer 300 is not formed on the shiny surface 230 of the wheel material 102. The base paint is, for example, a colored pigment.

[0023] The color clear coat layer 310 is a colored layer formed by painting with a color paint, and is formed on the entire outer surface (shiny surface 230, inclined surface 250) of the wheel 100. The color clear coat layer 310 may be a chromatic or achromatic layer. In this embodiment, the color clear coat layer 310 is a colored and light-transmitting layer, and the surfaces of the shiny surface 230 and inclined surface 250 (color base coat layer 300) can be seen through the color clear coat layer 310.

[0024] The top clear coat layer 320 is a light-transmitting layer formed by painting with clear paint, and is formed on the color clear coat layer 310 on the entire outer surface of the wheel 100 (shiny surface 230, inclined surface 250).

[0025] A-2. Manufacturing method of the wheel 100: A description will now be given of a method for manufacturing the above-mentioned wheel 100. Fig. 3 is a flowchart showing the manufacturing process of the wheel 100, and Fig. 4 is an explanatory diagram showing part of the manufacturing process of the wheel 100.

[0026] First, as shown in Figure 3, a pre-processed wheel blank 102 made of light metal is formed (S110). The pre-processed wheel blank 102 is formed using a light metal material by, for example, a known casting method or forging method. Figure 4(A) shows an XY cross section of the pre-processed wheel blank 102.

[0027] Next, a base paint is applied to the entire outer surface (top surface 230X, inclined surface 250) of the wheel material 102 before processing, and then baked and dried to form a color base coat layer 300 (S120). The color base coat layer 300 may be a chromatic or achromatic layer. Figure 4(B) shows an XY cross section of the wheel material 102 before processing, with the color base coat layer 300 formed on both the top surface 230X and the inclined surface 250. The base paint is, for example, a colored pigment.

[0028] Next, a portion of the wheel blank 102 before processing, including the outermost surface 230X, is cut to form a shiny surface 230 (cut surface) (S130). FIG. 4(C) shows an XY cross section of the wheel blank 102 after the portion including the outermost surface 230X has been cut from the wheel blank 102 before processing in FIG. 4(B). The shiny surface 230 is a substantially flat surface. By forming the shiny surface 230, an edge portion 240 where the shiny surface 230 and the inclined surface 250 intersect is formed in the wheel blank 102 after cutting. The cutting can be performed using a machining machine such as a milling machine or a lathe. The wheel blank 102 after cutting is an example of a wheel main body formed in a forming step as defined in the claims, and the steps S110 to S130 are an example of a forming step as defined in the claims.

[0029] Next, a color clear paint 310P is applied to the entire outer surface (shiny surface 230, inclined surface 250) of the cut wheel blank 102, for example by spray coating (S140). Fig. 4(D) shows an XY cross section of the cut wheel blank 102, in which the color clear paint 310P has been applied to the entire shiny surface 230 and inclined surface 250. The color clear paint 310P is an example of the first paint in the claims, and the step of S140 is an example of the first application step in the claims.

[0030] Next, colorless clear paint 320P is applied by, for example, spray painting to the entire outer surface (shiny surface 230, inclined surface 250) of the wheel blank 102 after the application of color clear paint 310P (S150). Figure 4(E) shows an XY cross section of the wheel blank 102 after cutting, in which colorless clear paint 320P is applied over color clear paint 310P over the entire shiny surface 230 and inclined surface 250. Note that colorless clear paint 320P is an example of a second paint in the claims, and the step of S150 is an example of a second application step in the claims.

[0031] Next, the color clear paint 310P and the colorless clear paint 320P applied to the wheel material 102 are baked and dried to form the color clear coat layer 310 and the top clear coat layer 320 (S160). The step of S160 is an example of the baking and drying step defined in the claims. By forming the top clear coat layer 320 on the wheel material 102, corrosion of the wheel 100 is prevented.

[0032] Here, the fluidity of color clear paint 310P when baked dry is lower than the fluidity of colorless clear paint 320P when baked dry. Fluidity here refers to the ease with which a paint flows, and the fluidity of color clear paint 310P and colorless clear paint 320P is determined by the ease with which both paints flow when baked dry after being applied to an object under the same conditions. For example, color clear paint 310P may be a colored pigment blended with a rust inhibitor, while colorless clear paint 320P may be a light-transmitting pigment blended with a lower proportion of rust inhibitor than color clear paint 310P (including paints that do not blend with a rust inhibitor).

[0033] Color Clear Paint 310P can be prepared by blending color pigments, extender pigments, metallic pigments, etc. with Compositions 1 and 2, and then diluting with organic solvents as needed. This prevents the paint applied to the edge 240 from flowing during baking, and produces a colored coating that has excellent film-forming properties on the edge 240 and is excellent in transparency, weather resistance, smoothness, adhesion, and physical properties. <Composition 1>: A coating composition for aluminum wheels disclosed in Japanese Patent Publication No. 6-89295 (A) A coating composition for aluminum wheels, which contains, per 100 weight parts of a thermosetting resin, (B) 5 to 35 weight parts of transparent finely powdered silica and / or alumina having a particle size of 50 to 50 mμ, and (C) an organic solvent composition in the coating composition consisting of 10 to 70 weight % of a polar organic solvent having a boiling point of 130°C or less and 90 to 30 weight % of a non-polar organic solvent having a boiling point of 105°C to 250°C, and (D) a solids content at the time of coating is adjusted to 20 to 50 weight %. <Composition 2>: Aluminum wheel coating composition disclosed in Patent No. 6270728 A primer coating composition for aluminum wheels, comprising a copolymer resin (A) obtained by reacting a mixture of 5 to 35 mass% of a nitrogen-containing radically polymerizable unsaturated monomer (a1) represented by the following formula (1), 1 to 10 mass% of a carboxyl group-containing radically polymerizable unsaturated monomer (a2), and 55 to 94 mass% of other radically polymerizable unsaturated monomer (a3), relative to the total of the constituent monomers, and 1 to 30 mass parts of fumed silica (B) and 0.1 to 10 mass parts of a magnesium-containing phosphate compound (C), relative to 100 mass parts of the total solids content of the copolymer resin (A): [ka] (In formula (1), R 1 represents a hydrogen atom or CH3, and R 2 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms)

[0034] A-3. Advantages of this embodiment: As described above, in the manufacturing method of the wheel 100 of this embodiment, the color clear paint 310P is applied to the cut wheel blank 102 (S140), the colorless clear paint 320P is applied on top of the color clear paint 310P (S150), and then the colored clear paint 310P is baked and dried (S160). The fluidity of the color clear paint 310P when baked and dried is lower than the fluidity of the colorless clear paint 320P when baked and dried. Therefore, the color clear paint 310P is less likely to experience a difference in surface tension when baked and dried compared to the colorless clear paint 320P, thereby suppressing the occurrence of the framing phenomenon. As a result, the variation in film thickness of the color clear coat layer 310 is smaller than the variation in film thickness of the top clear coat layer 320. Furthermore, the top clear coat layer 320 has higher light transmittance than the color clear coat layer 310. Therefore, even if variations in film thickness occur in the top clear coat layer 320, they are less noticeable than variations in film thickness in the color clear coat layer 310. Therefore, according to this embodiment, it is possible to manufacture a wheel 100 in which the impact on design caused by variations in film thickness of the clear coatings (color clear coat layer 310, top clear coat layer 320) is reduced, compared to when, for example, the fluidity of the color clear paint 310P when baked and dried is higher than the fluidity of the colorless clear paint 320P when baked and dried.

[0035] When using a wheel material 102 in which the edge portion 240 is formed by cutting, variations in the thickness of the color clear coat layer 310 due to the frame phenomenon are likely to occur, particularly near the edge portion 240. Furthermore, the shiny surface 230 formed by cutting is likely to be significantly affected by color unevenness resulting from variations in the thickness of the color clear coat layer 310 due to light that passes through the color clear coat layer 310 and is reflected by the shiny surface 230. In contrast, according to this embodiment, even when using a wheel material 102 having such a shiny surface 230 and edge portion 240, it is possible to manufacture a wheel 100 in which variations in the thickness of the color clear coat layer 310 are effectively suppressed.

[0036] B. Variations: The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified into various forms without departing from the spirit thereof, for example, the following modifications are also possible.

[0037] In the above embodiment, the wheel 100 (wheel material 102) is a one-piece type wheel, but it is not limited to this and may be a so-called two-piece type wheel in which the wheel rim 10 and the wheel disc 20 are separate bodies. Also, in the above embodiment, the wheel 100 having the spoke portion 210 is exemplified as a vehicle wheel, but it is not limited to this and may be a wheel without spoke portions.

[0038] The materials constituting each component in the above embodiment are merely examples, and each component may be made of other materials. The first paint may be a colorless paint, as long as it forms a colored clear coating film by baking and drying. The second paint may be an opaque paint, such as a matte paint, as long as it forms a colorless clear coating film with optical transparency by baking and drying.

[0039] The manufacturing method of the wheel 100 in the above embodiment is merely an example and can be modified in various ways. For example, the cutting process (S130) may be performed using a cutting machine such as a known machining center.

[0040] In the above embodiment, the wheel (wheel body in the claims) to which the first paint is applied is the wheel material 102 formed by the forming steps (S110 to S130), but this is not limiting and the wheel material 102 may be one that has not undergone at least one of the formation of the color base coat layer 300 (S120) and the formation of the shiny surface 230 by cutting (S130). Also, the wheel to which the first paint is applied may be one that has undergone processing other than cutting or that has been painted with a paint other than a base coat.

[0041] In the above embodiment, the wheel to which the first paint was applied was a wheel material 102 having an edge portion 240, but this is not limited to this. Any wheel having a shape that has a ridge portion where two adjacent surfaces that have different inclination angles relative to the wheel axial direction intersect, a sharply pointed portion, or a curved surface may be susceptible to framing, and therefore, by applying the present invention, it is possible to manufacture vehicle wheels in which variations in the film thickness of the colored clear coating due to framing are suppressed.

[0042] In the above embodiment, the color clear coat layer 310 may be formed on only a portion of the outer surface of the wheel 100. The color clear coat layer 310 may also be an opaque layer. The top clear coat layer 320 may also be formed on only a portion of the outer surface of the wheel 100.

[0043] In the above embodiment, the color clear coat layer 310 and the top clear coat layer 320 are formed on the wheel material 102 by a so-called two-coat, one-bake method (see FIG. 3). However, the color clear coat layer 310 and the top clear coat layer 320 may also be formed on the wheel material 102 by a so-called two-coat, two-bake method. That is, in FIG. 3, a color clear paint 310P may be applied to the wheel material 102 (S140), followed by a step of drying the applied color clear paint 310P, and then a colorless clear paint 320P may be applied to the wheel material 102 (S150) and dried. Note that the drying step of the color clear paint 310P and the drying step of the colorless clear paint 320P in this two-coat, two-bake method are examples of the drying step within the scope of the claims. [Explanation of symbols]

[0044] 10: Wheel rim 12: Opening 20: Wheel disc 100: Wheel 102: Wheel material 110: Flange portion 210: Spoke portion 220: Hub mounting portion 222: Hub hole 224: Bolt hole 230: Cutting surface 230X: Outermost surface 240: Edge portion 250: Inclined surface 300: Color base coat layer 310: Color clear coat layer 310P: Color clear paint 320: Top clear coat layer 320P: Colorless clear paint

Claims

1. forming a wheel body of a metal vehicle wheel; a first coating step of coating the wheel body with a first paint to form a colored clear coating film; a second coating step of coating a second paint on the area of ​​the wheel body to which the first paint has been applied to form a colorless clear paint film; a baking and drying process of baking and drying the first paint and the second paint applied to the wheel body to form the colored clear coating film and the colorless clear coating film; A method for manufacturing a vehicle wheel, comprising: a fluidity of the first paint when baked and dried lower than a fluidity of the second paint when baked and dried.

2. 2. A method for manufacturing a vehicle wheel according to claim 1, comprising: In the forming step, a shiny surface is formed on the surface of the wheel body by cutting, and an edge portion remains on the edge of the shiny surface, In the first coating step, the first paint is applied to an area of ​​the wheel body that includes at least the shiny surface and the edge portion, In the second coating step, the second paint is applied onto the first paint that has been applied to the area including the shiny surface and the edge portion.

Images