JP2023010107A - Method for manufacturing vehicular wheel - Google Patents

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 The technology disclosed herein relates to a method for manufacturing a vehicle wheel.

Conventionally, in order to improve the design, for example, a part of the wheel body is cut to form a bright surface, a colored clear coat layer is formed on the bright surface, and a colored clear coat layer is formed on the colored clear coat layer. , methods of manufacturing vehicle wheels are known in which a matt top clearcoat layer is applied.

JP 2014-221575 A

In the above conventional manufacturing method, when the paint for forming the color clear coat layer is baked and dried, the so-called picture frame phenomenon occurs in the color clear coat layer. That is, in the paint applied near the edge remaining on the edge of the bright surface of the wheel body, the thinner evaporates quickly on the surface portion, so the surface tension increases and the paint inside is pulled. As a result, the film thickness of the portion of the color clear coat layer that is applied to the vicinity of the edge portion of the wheel body is increased. If the thickness of the colored clear coat layer varies in this way, the apparent color depth of the wheel surface varies, for example, and this affects the appearance of the wheel.

In addition, the unevenness in the film thickness of the color clear coat layer caused by such non-uniform surface tension of the paint is not limited to the case where the wheel body has an edge part, for example, the wheel body is complicated and the curved surface suddenly changes. It may also occur when it has a shape that is flat.

This specification discloses a technology capable of solving the above-described problems.

The technology disclosed in this specification can be implemented as the following modes.

(1) A method for manufacturing a vehicle wheel disclosed in the present specification includes a forming step of forming a wheel body of a metal vehicle wheel; a first coating step of applying one paint; and a second coating step of applying a second paint for forming a colorless clear coating film on the area of the wheel body to which the first paint has been applied. and a baking 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. and wherein the fluidity of the first paint during baking and drying is lower than the fluidity of the second paint during baking and drying.

In this vehicle wheel manufacturing method, the fluidity of the first paint for forming the colored clear coating film during baking and drying is the same as the flowability during baking and drying of the second paint for forming the colorless clear coating film. lower than the liquidity of Therefore, a colored clear coating film can suppress variations in film thickness caused by uneven surface tension compared to a colorless clear coating film. In addition, variations in the thickness of the colorless clear coating have less effect on the appearance of the wheel than variations in the thickness of the colored clear coating. Thus, according to the vehicle wheel manufacturing method of the present invention, it is possible to manufacture a vehicle wheel in which the influence of variations in the film thickness of the clear coating film is suppressed.

(2) In the method for manufacturing a vehicle wheel described above, in the forming step, a bright surface is formed on the surface of the wheel body by cutting, an edge portion remains on the edge of the bright surface, and the second In the first coating step, the first paint is applied to a region including at least the bright surface and the edge portion of the wheel body, and in the second coating step, the bright surface and the edge portion are coated. The second paint may be applied over the first paint applied to the area including

When using a wheel having an edge portion formed by cutting, the thickness of the colored clear coating film tends to vary remarkably due to the frame phenomenon, particularly in the vicinity of the edge portion. In addition, the bright surface formed by cutting is likely to be affected by color unevenness due to variations in the thickness of the colored clear coating film due to the light that passes through the colored clear coating film and is reflected by the bright surface. . On the other hand, according to the vehicle wheel manufacturing method of the present invention, even when using a wheel having such an edge part or a bright surface, the variation in the thickness of the clear coating film is effectively suppressed. Wheels can be manufactured.

The technology disclosed in this specification can be implemented in various forms, such as a vehicle wheel and a manufacturing method thereof.

1 is an XZ plan view schematically showing an external configuration of a vehicle wheel 100 according to an embodiment; FIG. 1 is an explanatory diagram schematically showing an XY cross-sectional configuration of a vehicle wheel 100; FIG. 4 is a flow chart showing a manufacturing process of the vehicle wheel 100. FIG. FIG. 4 is an explanatory diagram showing a part of the manufacturing process of the vehicle wheel 100;

A. Embodiment:
A-1. Configuration of vehicle wheel 100:
FIG. 1 is an XZ plan view schematically showing 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 schematically showing the XY cross-sectional configuration of the wheel 100 in this embodiment. FIG. 2 shows the XY cross-sectional configuration of the spoke portion 210 of the wheel 100 at the position II-II in FIG. Each figure shows mutually orthogonal XYZ axes for specifying directions. In this specification, for convenience, the Y-axis direction is the direction parallel to the axis of rotation of the wheel 100, hereinafter referred to as the "wheel axis direction", although the wheel 100 is actually oriented in such a direction. may be oriented differently. Hereinafter, the radial direction of the wheel 100 is referred to as "wheel radial direction".

As shown in FIG. 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 the wheel material 102 . Note that the wheel material 102 is molded in a molding process (S110 in FIG. 3), which will be described later, and then undergoes a painting process (S120, S140, S150), a cutting process (S130), and a baking and drying process (S160) into the wheel 100. Become. Here, the material of the wheel 100 used in each process is described as the wheel material 102 for convenience. The color clear coat layer 310 is an example of a colored clear coat in the scope of claims, and the top clear coat layer 320 is an example of a colorless clear coat in the scope of claims.

The wheel material 102 is made of light metal such as aluminum alloy or magnesium alloy. The wheel blank 102 includes a substantially cylindrical wheel rim 10 and a wheel disc 20 arranged on the inner peripheral side 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 (Y-axis positive direction side) of the wheel 100 (wheel material 102) in the wheel axial direction is referred to as an "outer side", and the other side in the wheel axial direction (Y-axis negative direction side) is referred to as an "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 the vehicle body. The surface on the outer side of the wheel 100 is the design surface.

(Wheel rim 10)
As shown in FIG. 1, the wheel rim 10 is generally cylindrical as a whole 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 has a cylindrical shape in which a well portion and the like are formed. The pair of flange portions 110 has a substantially annular shape when viewed in the wheel axial direction (Y-axis direction), and is positioned at both ends of the cylindrical portion in the wheel axial direction. A tire (not shown) mounted on the wheel 100 is held by the pair of flanges 110 so as not to shift in the axial direction of the wheel.

(Wheel disc 20)
The wheel disc 20 is positioned on the outer side of the wheel rim 10 and includes a hub mounting portion 220 and a plurality of (five in this embodiment) spoke portions 210 . The hub attachment portion 220 has a substantially disc shape and is positioned substantially in the center of the wheel disc 20 when viewed in the wheel axial direction (Y-axis direction). A hub hole 222 to which a hub (not shown) of the vehicle body is connected is formed substantially at the center of the hub mounting portion 220 . A plurality of bolt holes 224 are formed around the hub hole 222 for fixing the wheel 100 to the hub of the vehicle body.

A plurality of spoke portions 210 are radially arranged between the wheel rim 10 and the hub attachment portion 220 . Each spoke portion 210 extends in the wheel radial direction. Openings (air vents) 12 are formed between the spokes 210 adjacent to each other. Although the opening 12 has a substantially triangular shape, it is not limited to this, and may have, for example, a substantially rectangular shape. Each spoke portion 210 extends to the flange portion 110 of the wheel rim 10 .

As shown in FIG. 1 , the outer surface (design surface) of the wheel material 102 on the outer side has a bright surface 230 and a plurality of inclined surfaces 250 . Further, the wheel material 102 has an edge portion 240 where the bright surface 230 and the inclined surface 250 intersect.

The bright surface 230 is a surface in which the normal line of the bright surface 230 extends in a direction parallel to or crossing the wheel axial direction. Specifically, the bright surface 230 is the outermost surface of the hub mounting portion 220 and the spoke portion 210 of the outer surface of the wheel material 102 . The bright surface 230 is a flat surface substantially perpendicular to the wheel axial direction. Each inclined surface 250 is a frame-shaped portion defining the opening 12 of the outer surface of the wheel material 102 on the outer side. Each inclined surface 250 is a surface that is inclined with respect to the bright 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. Note that the inclined surface 250 may be flat or curved.

The color base coat layer 300 is a colored (for example, black-based) layer formed by coating the inclined surface 250 of the wheel material 102 with a base paint. The color base coat layer 300 may be a chromatic layer or an achromatic layer. The color base coat layer 300 is not formed on the bright surface 230 of the wheel material 102 . Base paints are, for example, colored pigments.

The colored clear coat layer 310 is a colored layer formed by painting with color paint, and is formed on the entire outer surface of the wheel 100 on the outer side (the bright surface 230 and the inclined surface 250). Color clear coat layer 310 may be a chromatic layer or an achromatic layer. In this embodiment, the colored clear coat layer 310 is a colored and light-transmitting layer, and the surfaces of the bright surface 230 and the inclined surface 250 (color base coat layer 300) are visible through the colored clear coat layer 310. It is possible.

The top clear coat layer 320 is a light-transmitting layer formed by coating with a clear paint, and the entire outer surface (the bright surface 230 and the inclined surface 250) of the wheel 100 is coated with a colored clear coat layer. 310 is formed.

A-2. Method of manufacturing wheel 100:
A method of manufacturing the wheel 100 described above will be described. FIG. 3 is a flow chart showing the manufacturing process of the wheel 100, and FIG. 4 is an explanatory diagram showing a part of the manufacturing process of the wheel 100. As shown in FIG.

First, as shown in FIG. 3, a light metal wheel material 102 before processing is molded (S110). The wheel blank 102 before processing is formed by, for example, a known casting method or forging method using a light metal material. FIG. 4A shows an XY cross section of the wheel material 102 before processing.

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

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

Next, the entire outer surface (shiny surface 230, inclined surface 250) of the wheel material 102 after cutting is coated with the color clear paint 310P by, for example, spray coating (S140). FIG. 4(D) shows an XY cross section of the wheel material 102 after cutting in which the colored clear paint 310P is applied over the entire bright surface 230 and the inclined surface 250. FIG. The color clear paint 310P is an example of the first paint in the scope of claims, and the step of S140 is an example of the first coating step in the scope of claims.

Next, the colorless clear paint 320P is applied by, for example, spray coating to the entire outer surface (shiny surface 230, inclined surface 250) of the wheel material 102 after the application of the color clear paint 310P (S150). FIG. 4(E) shows an XY cross section of the wheel material 102 after cutting, in which the colorless clear paint 320P is applied over the color clear paint 310P over the entire bright surface 230 and the inclined surface 250. . The colorless clear paint 320P is an example of the second paint in the claims, and the step of S150 is an example of the second coating step in the claims.

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

Here, 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. Fluidity here means the ease with which the paint flows, and whether the fluidity of the color clear paint 310P or the colorless clear paint 320P is high or low depends on the degree of fluidity when both paints are applied to an object under the same conditions and then baked and dried. Judging by the ease of flow. For example, the color clear paint 310P contains a colored pigment and a rust preventive agent, and the colorless clear paint 320P contains a light-transmitting pigment and a less rust preventive agent than the color clear paint 310P. (including those containing no antirust agent).

（式（１）中、Ｒ^１は水素原子又はＣＨ_３を表し、Ｒ^２は水素原子又は炭素数１～６のアルキル基を表す） The color clear paint 310P can be produced by, for example, mixing compositions 1 and 2 with a coloring pigment, an extender pigment, a metallic pigment, and the like, and further diluting with an organic solvent as necessary. As a result, the paint applied to the edge portion 240 does not flow during baking, and the edge portion 240 has good coating film formation properties, transparency, weather resistance, smoothness, adhesion, physical properties, and the like. Excellent colored coatings can be obtained.
<Composition 1>: A coating composition for aluminum wheels disclosed in JP-B-6-89295 (A) Per 100 parts by weight of thermosetting resin, (B) transparent fine powder silica having a particle size of 50 to 50 mμ and (or) a paint containing 5 to 35 parts by weight of alumina, and (C) the organic solvent composition in the paint is 10 to 70% by weight of a polar organic solvent having a boiling point of 130° C. or less and a boiling point of 105 C. to 250.degree. C., comprising 90 to 30 wt.
<Composition 2>: A nitrogen-containing radically polymerizable unsaturated monomer represented by the following formula (1) with respect to the total monomers constituting the aluminum wheel coating composition disclosed in Japanese Patent No. 6270728 5 to 35% by mass of the monomer (a1), 1 to 10% by mass of the carboxyl group-containing radically polymerizable unsaturated monomer (a2), and 55 to 94% by mass of the other radically polymerizable unsaturated monomer (a3) 1 to 30 parts by mass of fumed silica (B) with respect to the total 100 parts by mass of the copolymer resin (A) and the solid content of the copolymer resin (A) obtained by reacting a mixture of A primer coating composition for aluminum wheels, containing 0.1 to 10 parts by mass of a phosphoric acid compound (C) containing magnesium.

(In formula (1), R ¹ represents a hydrogen atom or CH ₃ and R ² represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms)

A-3. Effect of this embodiment:
As described above, in the method for manufacturing wheel 100 of the present embodiment, color clear paint 310P is applied to wheel material 102 after cutting (S140), and colorless clear paint 320P is applied on color clear paint 310P. It is applied (S150) and then 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 cause a difference in surface tension during baking and drying than the colorless clear paint 320P, thereby suppressing the occurrence of the picture frame phenomenon. As a result, variations in thickness of the color clear coat layer 310 are smaller than variations in thickness of the top clear coat layer 320 . Also, the top clear coat layer 320 has higher light transmittance than the color clear coat layer 310 . Therefore, even if the thickness of the top clear coat layer 320 varies, it is less noticeable than the thickness of the color clear coat layer 310 . Therefore, according to the present embodiment, the clear coating film (color clear coat It is possible to manufacture the wheel 100 in which the effect on design due to variations in the film thickness of the layer 310 and the top clear coat layer 320) is suppressed.

When the wheel material 102 having the edge portion 240 formed by cutting is used, the film thickness of the color clear coat layer 310 is likely to vary significantly in the vicinity of the edge portion 240 due to the frame phenomenon. In addition, the bright surface 230 formed by cutting is significantly affected by color unevenness caused by variations in the film thickness of the color clear coat layer 310 due to the light that passes through the color clear coat layer 310 and is reflected by the bright surface 230. easy to appear. In contrast, according to the present embodiment, even when using the wheel material 102 having such a bright surface 230 and edge portion 240, the variation in the film thickness of the color clear coat layer 310 is effectively suppressed. Wheel 100 can be manufactured.

B. Variant:
The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified in various forms without departing from the scope of the invention. For example, the following modifications are possible.

In the above-described embodiment, the wheel 100 (wheel material 102) is a one-piece type wheel, but not limited to this, a so-called two-piece type wheel in which the wheel rim 10 and the wheel disc 20 are separate bodies. It may be Further, in the above-described embodiment, the wheel 100 having the spoke portion 210 is illustrated as the vehicle wheel, but the wheel is not limited to this and may be a wheel that does not have a spoke portion.

The materials constituting each member in the above embodiment are merely examples, and each member may be made of another material. The first paint may be a colorless paint as long as it forms a colored clear coating film when baked and dried. The second paint may be, for example, an opaque paint such as a matte paint as long as it is a paint that forms a colorless clear coating film having light transmittance by baking and drying.

The manufacturing method of the wheel 100 in the above embodiment is merely an example, and various modifications are possible. For example, cutting (S130) may be performed using a cutting machine such as a known machining center.

In the above embodiment, the wheel to be coated with the first paint (the wheel body in the claims) was the wheel material 102 formed by the forming steps (S110 to S130), but this is not the only option. The wheel material 102 may not be subjected to at least one of the formation of the base coat layer 300 (S120) and the formation of the bright surface 230 by cutting (S130). Further, the wheel to be coated with the first coating material may be processed other than cutting, or may be coated with a coating other than a base coat.

In the above-described embodiment, the wheel to be coated with the first paint is the wheel material 102 having the edge portion 240. However, the present invention is not limited to this. If the wheel has a ridge line where the surfaces intersect with each other, a sharply pointed part, or a curved surface, the frame phenomenon may occur. It is possible to manufacture a vehicle wheel in which variations in film thickness are suppressed.

In the above embodiment, the colored clear coat layer 310 may be formed only on a portion of the outer surface of the wheel 100 on the outer side. Alternatively, the colored clearcoat layer 310 may be an opaque layer. Also, the top clear coat layer 320 may be formed only on a portion of the outer surface of the wheel 100 on the outer side.

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 the so-called two-coat one-bake method (see FIG. 3). A color clearcoat layer 310 and a top clearcoat layer 320 may be formed. That is, in FIG. 3, a color clear paint 310P is 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 is applied to the wheel material 102. It may be applied (S150) and dried. The drying process for the color clear paint 310P and the drying process for the colorless clear paint 320P in this two-coat two-bake method are examples of the drying process in the scope of claims.

10: Wheel rim 12: Opening 20: Wheel disc 100: Wheel 102: Wheel material 110: Flange part 210: Spoke part 220: Hub mounting part 222: Hub hole 224: Bolt hole 230: Cutting surface 230X: Top 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 (2)

a forming step of forming a wheel body of a metal vehicle wheel;
a first coating step of coating the wheel body with a first coating for forming a colored clear coating;
a second coating step of coating a second coating for forming a colorless clear coating on the area of the wheel body coated with the first coating;
a baking 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;
A method for manufacturing a vehicle wheel comprising
The method for manufacturing a vehicle wheel, wherein the fluidity of the first paint when baked and dried is lower than the fluidity of the second paint when baked and dried. A method for manufacturing a vehicle wheel according to claim 1,
In the forming step, a bright surface is formed on the surface of the wheel body by cutting, and an edge portion remains on the edge of the bright surface,
In the first coating step, the first paint is applied to a region of the wheel body that includes at least the bright surface and the edge portion,
In the second coating step, the second coating is applied on top of the first coating applied to the region including the bright surface and the edge portion.

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