JP7576689B2 - Method for manufacturing vehicle wheels - Google Patents

Description

The technology disclosed in this specification relates to vehicle wheels.

Vehicle wheels made of fiber-reinforced resin have been known for some time (see Patent Document 1 below). Such vehicle wheels made of fiber-reinforced resin are formed by stacking multiple sheets of fiber-reinforced resin material in a mold, and heating and pressurizing the fiber-reinforced resin material to cause it to flow, and the multiple sheets of fiber-reinforced resin material are integrated to form the vehicle wheel.

Furthermore, for this vehicle wheel, two different sizes of sheet-shaped fiber-reinforced resin material are alternately laminated, and then heated and pressurized to form a fiber-reinforced resin vehicle wheel. This molding method results in multiple different fiber directions in the fiber-reinforced resin, further improving the strength of the vehicle wheel.

Japanese Patent Application Publication No. 4-31102

In a vehicle wheel made of fiber reinforced resin, the fiber direction contributes to the strength of the vehicle wheel.
As a result of extensive research, the present inventors have discovered a new technique for improving the strength of the outer surface portion of vehicle wheels made of conventional fiber reinforced resin.

This specification discloses technology that can solve at least some of the problems mentioned above.

The technology disclosed in this specification can be realized in the following forms:

(1) The vehicle wheel disclosed in this specification is a fiber-reinforced resin vehicle wheel comprising a substantially cylindrical wheel rim and a wheel disc provided on the inner circumferential side of the wheel rim, the outer surface of the wheel disc having an outer surface layer formed from a first fiber-reinforced resin containing reinforcing fibers and thermoplastic resin oriented so that multiple fiber bundles are overlapped in different directions with regularity, and the main body portion of the vehicle wheel other than the outer surface layer is formed from a second fiber-reinforced resin containing reinforcing fibers and thermoplastic resin in which multiple fiber bundles are irregularly arranged.

In this vehicle wheel, the main body portion is formed from a second fiber reinforced resin, which contains reinforcing fibers in which multiple fiber bundles are arranged irregularly and a thermoplastic resin. The outer surface layer is formed from a first fiber reinforced resin, which contains reinforcing fibers oriented so that multiple fiber bundles are regularly overlapped in different directions and a thermoplastic resin, and has relatively high strength. This makes it possible to improve the strength of the outer surface portion of the vehicle wheel.

(2) In the above vehicle wheel, the outer surface layer may be configured to be present on a side that is visible from outside the vehicle when the vehicle wheel is mounted on the vehicle. With this vehicle wheel, it is possible to improve the strength of the outer surface layer, particularly on the side that is visible from outside the vehicle.

(3) The manufacturing method of the fiber-reinforced resin vehicle wheel of (1) or (2) above includes a first molding step of arranging a first resin material containing reinforcing fibers and a thermoplastic resin oriented so that a plurality of fiber bundles are overlapped in different directions with regularity in a first mold, and heating and pressurizing the first resin material in the first mold to mold an outer surface molded body having the shape of the outer surface of the wheel disc, and a second molding step of arranging the outer surface molded body on the inner surface of at least one of a plurality of second molds having molds, arranging a preheated second resin material containing reinforcing fibers and a thermoplastic resin between the outer surface molded body and the other molds, and heating and pressurizing the outer surface molded body and the laminated second resin material in the second mold to mold the vehicle wheel. According to this manufacturing method of the vehicle wheel, a vehicle wheel having a high-strength outer surface portion can be manufactured.

(4) In the above-mentioned method for manufacturing a vehicle wheel, the outer surface molding may be configured such that the shape of the outer surface of the wheel disc is seamlessly formed from a single first resin material. According to this method for manufacturing a vehicle wheel, an outer surface portion with even higher strength can be formed.

(5) In the above-mentioned method for manufacturing a vehicle wheel, the second molding step may be configured to place the outer surface molded body on the inner surface of a mold corresponding to a lower mold that forms the wheel disc, among the molding dies having the multiple dies, and to arrange the second resin material between the outer surface molded body and the other dies. According to this method for manufacturing a vehicle wheel, placing the outer surface molded body on the lower mold makes it easier to manufacture the vehicle wheel and improves the design.

The technology disclosed in this specification can be realized in various forms, for example, in the form of a vehicle wheel, a manufacturing method thereof, etc.

1 is an XZ plan view showing a schematic external configuration of a vehicle wheel 100 according to an embodiment of the present invention; 1 is an explanatory diagram illustrating a schematic XY side configuration of a vehicle wheel 100. FIG. 2 is an explanatory diagram showing a schematic XZ plane configuration of a portion of the vehicle wheel 100; FIG. 4 is an explanatory diagram showing a schematic cross-sectional configuration of the vehicle wheel 100 taken along the line IV-IV in FIG. 3. 4 is a flowchart showing a manufacturing process of the vehicle wheel 100. 1 is an explanatory diagram illustrating a schematic configuration of an outer surface molding 30P in the XZ plane. 3A to 3C are explanatory diagrams showing a part of the manufacturing process of the vehicle wheel 100.

A. Embodiments:
A-1. Configuration of the vehicle wheel 100:
Fig. 1 is an XZ plan view showing a schematic external configuration of a vehicle wheel (hereinafter simply referred to as "wheel") 100 in this embodiment. Fig. 1 shows mutually orthogonal XYZ axes for specifying directions. For convenience, in this specification, the Y-axis direction is taken to be parallel to the rotation axis of the wheel 100, and will be referred to as the "wheel axis direction" hereinafter, but the wheel 100 may actually be disposed in a direction different from this direction. The same applies to Fig. 2 and subsequent figures.

(Configuration of the wheel 100)
The wheel 100 is made of fiber-reinforced resin. Details of the fiber-reinforced resin constituting the wheel 100 will be described later. The wheel 100 includes a substantially cylindrical wheel rim 10 and a wheel disc 20 arranged on the inner periphery of the wheel rim 10. The wheel 100 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 in the wheel axial direction (positive Y-axis direction side) is referred to as the "outer side", and the other side of the wheel axial direction (negative Y-axis direction side) is 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 the opposite side of the vehicle body, and the inner side of the wheel 100 faces the vehicle body. The outer side surface of the wheel 100 is a design surface. The outer side is an example of a side that can be seen from the outside of the vehicle when the vehicle wheel is mounted on the vehicle in the claims.

As shown in FIG. 1, the wheel rim 10 is substantially annular when viewed in the wheel axial direction (Y-axis direction). The wheel disc 20 is disposed at a position closer to the outer side of the wheel rim 10. The wheel disc 20 includes a hub mounting portion 220 and a plurality of spoke portions 210 (10 in this embodiment). The hub mounting portion 220 is substantially disc-shaped and is disposed substantially at the center of the wheel disc 20 when viewed in the wheel axial direction. A hub hole 222 is formed substantially at the center of the hub mounting 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 fix the wheel 100 to the hub of the vehicle body. The plurality of spoke portions 210 are radially disposed between the wheel rim 10 and the hub mounting portion 220.

(Fiber reinforced resin constituting the wheel 100)
FIG. 2 is an explanatory diagram that shows a schematic XY side configuration of a portion of the wheel 100. FIG. 2 shows the outer peripheral surface of the wheel rim 10 (well portion) of the wheel 100. FIG. 3 is an explanatory diagram that shows a schematic XZ plane configuration of a portion of the wheel 100. FIG. 3 shows an enlarged view of a portion of the outer surface of the outer side of the wheel disc 20. FIG. 4 is an explanatory diagram that shows a schematic cross-sectional configuration of the wheel 100 at the position IV-IV in FIG. 3. FIG. 4 shows the cross-sectional configuration of the spoke portion 210, and the cross section is a surface cut approximately perpendicular to the direction in which the spoke portion 210 extends.

As shown in FIG. 2, the wheel 100 includes an outer surface layer 30 and a main body portion 40. The outer surface layer 30 is a portion that constitutes the outer surface (so-called design surface) of the wheel 100. The thickness of the outer surface layer 30 (thickness from the outermost surface of the wheel 100) is 0.5 mm or less, and may be 0.3 mm or less. In addition, the thickness of the outer surface layer 30 is preferably 0.2 mm or more. The main body portion 40 is a portion of the wheel 100 that is adjacent to the outer surface layer 30 and is on the inner side of the outer surface layer 30. In this embodiment, the main body portion 40 is a portion of the wheel 100 other than the outer surface layer 30. As shown in FIG. 4, the outer surface layer 30 continuously covers the side of the main body portion 40 (spoke portion 210) in addition to the outer surface of the main body portion 40 (spoke portion 210). This further improves the strength of the main body portion 40 (spoke portion 210) and enhances the design. The outer surface of the outer surface layer 30 is generally flush with the exposed side surface of the main body portion 40 (spoke portions 210). In addition, since it is sufficient that the side surface of the main body portion 40 (spoke portions 210) is formed to be generally flush with the outer surface, the outer surface layer 30 may cover the entire side surface of the main body portion 40 (spoke portions 210).

The main body portion 40 is formed of an irregular fiber reinforced resin. The irregular fiber reinforced resin is composed of reinforcing fibers 42 and a thermoplastic resin (e.g., polypropylene, polyamide resin). The irregular fiber reinforced resin has a structure in which a plurality of fiber bundles of reinforcing fibers 42 are irregularly arranged. FIG. 2 illustrates an example of an irregular fiber reinforced fiber having a random structure in which a plurality of fiber bundles of reinforcing fibers 42 are irregularly arranged, and this random structure is exposed on the outer peripheral surface of the wheel 100 (e.g., the outer peripheral surface of the well portion of the wheel rim 10 or the peripheral portion of the wheel disc 20). The reinforcing fibers 42 constituting the irregular fiber reinforced resin are, for example, carbon fibers or glass fibers. In FIG. 2, a structure in which a plurality of reinforcing fibers 42 having different stretching directions and sizes are arranged in a scattered manner is exposed on the outer peripheral surface of the wheel 100. In addition, the length of the reinforcing fibers 42 is shorter than the length of the fiber bundles 32 and 34 described later. The irregular fiber reinforced resin is an example of a second fiber reinforced resin in the scope of the claims.

The outer surface layer 30 is formed of regular fiber reinforced resin. The regular fiber reinforced resin is composed of regular reinforcing fibers and a thermoplastic resin. The thermoplastic resin constituting the regular fiber reinforced resin may be the same material as the thermoplastic resin constituting the irregular fiber reinforced resin in the main body portion 40, or may be a different material.

The regular reinforcing fiber has a structure in which multiple fiber bundles are oriented so as to overlap with regularity in different directions. In FIG. 2, a regular reinforcing fiber having a mesh-like structure in which multiple fiber bundles 32, 34 are woven to cross each other is exemplified, and this mesh-like structure is exposed on the surface of the outer surface layer 30. More specifically, the regular reinforcing fiber includes multiple fiber bundles 32 oriented in a first direction and multiple fiber bundles 34 oriented in a second direction crossing (substantially perpendicular) the first direction. Each fiber bundle 32 is arranged so that it crosses multiple fiber bundles 34 and is alternately positioned on the front and back sides of the fiber bundle 34 by a predetermined number of bundles. In addition, each fiber bundle 34 is arranged so that it crosses multiple fiber bundles 32 and is alternately positioned on the front and back sides of the fiber bundle 32 by a predetermined number of bundles. The reinforcing fibers constituting the regular fiber reinforced resin are, for example, carbon fibers or glass fibers, and may be the same material as the reinforcing fibers constituting the irregular fiber reinforced resin in the main body portion 40, or may be a different material. The regular fiber reinforced resin is an example of a first fiber reinforced resin in the claims.

A-2. Manufacturing of the wheel 100:
The following describes a method for manufacturing the wheel 100. Fig. 5 is a flow chart showing the manufacturing process for the wheel 100, Fig. 6 is an explanatory diagram showing a schematic configuration in the XZ plane of an outer surface molded body 30P described below, and Fig. 7 is an explanatory diagram showing a part of the manufacturing process for the wheel 100.

First, the outer surface molding 30P shown in FIG. 6 is molded (S110). The outer surface molding 30P is a molding made of regular fiber reinforced resin that has the shape of the outer surface of the wheel disc 20 and constitutes the outer surface layer 30. FIG. 6 shows the inner, outer surface of the outer surface molding 30P. Specifically, a sheet-like first prepreg (not shown) is prepared. The first prepreg is a sheet material formed of regular fiber reinforced resin (for example, a thermoplastic resin sheet having a mesh-like structure in which multiple fiber bundles 32, 34 are woven to cross each other). The first prepreg is an example of the first resin material in the claims.

Next, the mold (not shown) is heated to a predetermined first temperature (e.g., 165°C or higher and 185°C or lower), the first prepreg is placed in the lower mold of the mold, and the upper and lower molds are sandwiched for a predetermined time. This softens the first prepreg. Next, the first prepreg is sandwiched between the upper and lower molds and a predetermined first pressure (e.g., 1t or higher and 100t or lower) is applied, and at the same time, cooling of the mold is started. Then, when the temperature of the mold reaches a second temperature (e.g., 60°C or higher and 80°C or lower) lower than the first temperature, the molded outer surface molded body 30P is removed from the mold. Note that the number of first prepregs placed in the mold may be one, two, or three or more depending on the required strength. The thickness of the outer surface molded body 30P is, for example, 0.2 mm or more and 0.5 mm or less. The step S110 is an example of a first molding step set forth in the claims.

Next, the molding die 200 having multiple dies is heated to a predetermined third temperature (for example, 150°C or higher and 170°C or lower), and the outer surface molded body 30P is placed on the inner surface of at least one of the dies of the molding die 200 (S120). FIG. 7 shows the molding die 200, which has an upper die 202, a lower die 204, and a horizontal die 206. Next, as shown in FIG. 7(A), the outer surface molded body 30P is placed so that the outer surface of the outer surface molded body 30P faces the inner surface (upper surface) of the lower die 204. When placing the outer surface molded body 30P, the horizontal die 206 may be placed in a closed position or an open position. The outer surface molded body 30P may also be placed at room temperature.

Next, a plurality of resin materials made of fiber-reinforced resin containing irregularly arranged reinforcing fibers and thermoplastic resin are heated to a predetermined fourth temperature (e.g., 190°C or higher and 210°C or lower) and placed between the outer surface molding 30P and the other molds 202, 206 (S130). Specifically, sheet-shaped second prepregs 43, 44 are prepared. The second prepregs 43, 44 are sheet materials formed of irregular fiber-reinforced resin (e.g., thermoplastic resin sheets having a structure in which multiple reinforcing fibers are irregularly arranged or a structure in which multiple bundles of reinforcing fibers are irregularly arranged). The second prepregs 43, 44 are an example of a second resin material in the claims.

As shown in Fig. 7(A), a plurality of second prepregs 43 are laminated on the outer surface molding 30P. A plurality of second prepregs 44 are stacked and placed on the inner peripheral surface of the horizontal mold 206. Each of the second prepregs 43, 44 may be configured by laminating a plurality of resin materials made of fiber-reinforced resin containing a plurality of reinforcing fibers oriented in a predetermined direction and a thermoplastic resin, so that the fiber bundles of each reinforcing fiber are irregular.

Next, the upper mold 202 and the horizontal mold 206 are closed, and a predetermined second pressure (e.g., 1150t or more and 1250t or less) is applied to the outer surface molded body 30P and the second prepregs 43, 44, and at the same time, cooling of the mold 200 is started. After that, when the temperature of the mold 200 reaches a fifth temperature (e.g., 70°C or more and 90°C or less) lower than the third temperature, the wheel 100 is removed from the mold 200 (S140). That is, the second prepregs 43, 44 are softened by preheating, and the irregular fiber reinforced resin flows between the outer surface molded body 30P and the other molds 202, 206 by heating and pressurizing them with the mold 200. On the other hand, the outer surface molded body 30P almost retains its shape, and the flowing irregular fiber reinforced resin and the regular fiber reinforced resin of the outer surface molded body 30P are entangled. Then, when the temperature of the molding die 200 reaches a fifth temperature, the outer surface molding 30P hardens to form the outer surface layer 30, and the second prepregs 43, 44 harden to form the main body portion 40. The outer surface layer 30 and the main body portion 40 are integrally molded to form the wheel 100. In step S140, the molding formed by heating and pressing may be subjected to a predetermined post-treatment (such as chamfering or coating). The steps S120 to S140 are an example of a second molding step in the claims.

A-3. Advantages of this embodiment:
As described above, in the wheel 100 of this embodiment, the outer surface layer 30 is formed of regular fiber reinforced resin. The regular fiber reinforced resin contains reinforcing fibers oriented such that the multiple fiber bundles 32, 34 overlap in different directions with regularity, and a thermoplastic resin (see FIG. 3). The main body portion 40 is formed of irregular fiber reinforced resin, which contains reinforcing fibers 42 in which multiple fiber bundles are irregularly arranged, and a thermoplastic resin (see FIG. 2).

Here, the irregular fiber reinforced resin has a random structure in which the fiber bundles of the multiple reinforcing fibers 42 are arranged irregularly. For this reason, the irregular fiber reinforced resin has the same strength in any direction and has a high degree of freedom of relative movement between the reinforcing fibers 42. As a result, the body portion 40 (particularly the wheel rim 10) can be molded with relatively high moldability and high dimensional accuracy. However, the irregular fiber reinforced resin has a limit to the improvement of strength because of the high degree of freedom of relative movement (deformation) between the reinforcing fibers 42. On the other hand, the regular fiber reinforced resin has a structure in which the multiple fiber bundles 32, 34 are oriented so as to overlap with regularity in different directions. For this reason, the regular fiber reinforced resin has a low degree of freedom of relative movement (deformation) between the fiber bundles 32, 34, so it has low moldability but high strength compared to the irregular fiber reinforced resin. This makes it possible to improve the strength of the outer surface layer 30 (outer surface portion) while ensuring the dimensional accuracy of the body portion 40 of the wheel 100.

In the above embodiment, the outer surface layer 30 is present on the outer side of the wheel 100. This makes it possible to improve the strength of the outer surface layer located on the outer side of the wheel 100, which is likely to become the starting point of cracks when high stress is applied. In addition, by exposing a mesh-shaped oriented fiber pattern on the outer surface of the wheel 100, the design of the wheel 100 can be improved.

5 in the above embodiment, a high-strength outer surface layer 30 can be molded using a relatively strong regular fiber reinforced resin, while a main body portion 40 can be molded with high dimensional accuracy using a relatively highly moldable irregular fiber reinforced resin. In addition, by placing the outer surface molding 30P on the lower mold 204 of the molding die 200 (see FIG. 7), the wheel 100 can be easily manufactured and the design can be improved. In addition, the outer surface molding 30P is seamlessly formed into the shape of the outer surface of the wheel disc 20 using a single first prepreg. This allows an outer surface portion with even higher strength to be molded.

B. Variations:
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 spirit of the invention. For example, the following modifications are also possible.

In the above embodiment, the wheel 100 is a one-piece type wheel, but it is not limited to this, and it may be a so-called two-piece type wheel in which the wheel rim 10 and the wheel disc 20 are separate. 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 it may be a wheel without a spoke portion.

In the above embodiment, both the outer and inner surface portions of the wheel 100, or only the inner surface portion, may be formed from regular fiber-reinforced resin.

The materials constituting each component in the above embodiment are merely examples, and each component may be made of other materials.

The manufacturing method of the wheel 100 in the above embodiment is merely one example and can be modified in various ways.

10: Wheel rim 20: Wheel disc 30: Outer surface layer 30P: Outer surface molding 32, 34: Fiber bundle 42: Reinforced fiber 40: Main body portion 43, 44: Second prepreg 100: Wheel 200: Molding mold 202: Upper mold 204: Lower mold 206: Horizontal mold 210: Spoke portion 220: Hub mounting portion 222: Hub hole 224: Bolt hole

Claims (3)

A vehicle wheel made of fiber reinforced resin, comprising a substantially cylindrical wheel rim and a wheel disc provided on an inner peripheral side of the wheel rim,
The outer surface of the wheel disc is provided with an outer surface layer formed of a first fiber reinforced resin including reinforcing fibers oriented so that a plurality of fiber bundles are regularly overlapped in different directions and a thermoplastic resin,
A method for manufacturing a vehicle wheel, wherein a main body portion other than the outer surface layer of the vehicle wheel is formed of a second fiber reinforced resin including reinforced fibers having a plurality of fiber bundles irregularly configured and a thermoplastic resin,
a first molding step of arranging a first resin material, which includes a thermoplastic resin and reinforcement fibers oriented so that a plurality of fiber bundles are overlapped in different directions with regularity, in a first mold, and heating and pressurizing the first resin material in the first mold to mold an outer surface molded body having a shape of the outer surface of the wheel disc;
a second molding step of arranging the outer surface molded body on the inner surface of at least one of a second molding die having a plurality of dies, arranging a sheet-like second resin material containing reinforcing fibers and a thermoplastic resin, which has been heated to a predetermined temperature , between the outer surface molded body and the other dies, and heating and pressurizing the outer surface molded body and the laminated second resin material in the second molding die to mold the vehicle wheel;
wherein the predetermined temperature is a temperature at which the second resin material softens.
A method for manufacturing a vehicle wheel. 2. A method for manufacturing a vehicle wheel according to claim 1, comprising the steps of:
The outer surface molding is formed seamlessly into the shape of the outer surface of the wheel disc by a single first resin material.
A method for manufacturing a vehicle wheel. A method for manufacturing a vehicle wheel according to claim 1 or 2, comprising the steps of:
The second molding step includes placing the outer surface molded body on an inner surface of a die corresponding to a lower die for forming the wheel disc among the second molding dies, and disposing the second resin material between the outer surface molded body and the other dies.
A method for manufacturing a vehicle wheel.

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