Method for manufacturing thermoplastic fiber-reinforced resin wheel

Abstract

A resin wheel in which a rim portion and a disk portion are integrated can be manufactured in an extremely short period of time with good moldability. In a method for manufacturing a resin wheel in which a raw material (11) comprising a thermoplastic fiber-reinforced resin is molded using a mold (31), the mold (31) is set to a temperature lower than the melting point of the resin matrix of the raw material (11). As a raw material (11), an ingot-shaped raw material (11b) and a sheet-shaped raw material (11a) are prepared and heated to a temperature higher than the melting point of the resin matrix of the ingot-shaped raw material (11b) and the sheet-shaped raw material (11a). The heated ingot-shaped raw material (11b) is held in a die (31) surrounded by a disk outer surface die (32) and a rim outer diameter die (33), and the sheet-shaped raw material (11a) is held on a die (34)-side surface of the rim outer diameter die (33). A die (34) is lowered, the sheet-like material (11a) is deep-drawn to form a rim portion of a wheel, a portion of the sheet-like material (11a) is pressed against the ingot-like material (11b) to join the sheet-like material (11a) and the ingot-like material (11b), and the ingot-like material (11b) is compression-molded to form a disk portion of the wheel.

Description

Technical Field

[0001] The invention relates to a method for manufacturing an automobile wheel in which a rim part and a wheel disc part are integrally molded by using thermoplastic fiber reinforced resin. Background Art

[0002] Automobile wheels with an integrated rim and disc are typically molded by holding all or part of the raw materials—fiber-reinforced resin (e.g., FRP, SMC) or a fiber base material—along the inner surface of a mold. However, because the rim and disc, which have different shapes and orientations, are integrated, the multiple raw materials that comprise these parts must be formed into different shapes and positioned at different locations.

[0003] The wheel disclosed in Patent Document 1 below is made of thermosetting resin and manufactured as follows. Specifically, the raw material constituting the rim portion uses a sheet-shaped resin molding material (SMC) with a high resin content, which is formed into a cylindrical shape and held inside a rim molding mold. The raw material constituting the disc portion uses a sheet-shaped resin molding material (SMC) with a high fiber volume ratio, which is housed between a lower mold and an upper mold that mold the disc portion. In this example, the cylindrical raw material constituting the rim portion is wound around the outer periphery of the raw material constituting the disc portion as a resin raw material for processing.

[0004] The resin material for processing is placed in a heated mold and then compression molded (hot and cold molding). The molding is completed when the resin matrix of the raw material is solidified by chemical reaction after heating for a specified time and then cooled.

[0005] Due to this manufacturing process, the wheel manufacturing process requires time for proper placement of the raw material in the mold, shaping, and curing of the resin, making it impossible to complete the molding process in a few minutes including the preparation stage.

[0006] Non-Patent Document 1 below discloses a technology for high-speed molding of sheets made of thermoplastic fiber-reinforced resin, rather than thermosetting fiber-reinforced resin. This method aims to shorten cycle time while ensuring sufficient moldability by heating the sheet to a temperature higher than the melting point of its resin matrix and then inserting it into a mold set at a temperature lower than the melting point of the resin matrix for molding. Non-Patent Document 2 below discloses the manufacture of wheels using thermoplastic fiber-reinforced resin. This method uses a thermoplastic fiber-reinforced resin with chopped strands as reinforcing fibers as the raw material, heating it to a specified processing temperature, and then inserting it into a mold for compression molding.

[0007] In this method, a punch is pressed into the raw material to compress and form the disc, while a portion of the raw material is extruded into a cylindrical shape to form the rim. The rim increases in diameter as it extends upward, so ensuring the thickness of the rim requires a larger volume of raw material. To achieve this, the volume of the disc must be increased beyond the necessary level. Furthermore, when the rim is wide, the punch must be pressed deeper and harder, which dramatically increases the forming load. Furthermore, because the rim is formed by extrusion, the reinforcing fibers tend to align in a specific direction. This increases anisotropy, preventing high strength from being achieved, making it difficult to form wheels with wide rims. In other words, even if the reinforcing fibers are isotropic in the raw material before forming, anisotropy increases as they flow upward toward the rim, easily leading to axial strength variations and reduced strength. Consequently, there are limits to the width of the rim.

[0008] To reduce anisotropy, one approach is to slow the molding speed and thereby reduce the flow rate of the reinforcing fibers. However, this increases the molding time and causes a sharp drop in the resin temperature during molding, hindering moldability. Thus, the technique of Non-Patent Document 1 is believed to enable molding in a short time with a single compression operation. However, achieving a satisfactory balance between molding speed and molded product performance is difficult, and there are also limitations on product shape.

[0009] In addition to the molding based on QuickForm as disclosed in Non-Patent Document 2, there is also a technique called HP-RTM (High Pressure Resin Transfer Molding) molding (for example, Patent Document 2).

[0010] In this molding method, for example, a dry, unimpregnated fiber substrate or a laminate of fiber substrates is manually placed in a mold to give it a desired shape. After the mold is closed, the mold interior is depressurized and a thermosetting resin, such as epoxy resin, is injected under pressure to impregnate the fiber substrate. The mold is then heated to cure the thermosetting resin. Multiple fiber substrates are prepared depending on the intended application and manually arranged. This offers the advantage of ensuring wheel strength by increasing the number of laminated sheets in locations requiring reinforcement.

[0011] However, the placement and shaping of the fiber base material is time-consuming and requires advanced technical expertise to obtain a homogeneous product.

[0012] Therefore, the pre-molding and molding operations require a considerable amount of time and cannot be achieved in minutes. The wheels thus manufactured are very expensive and can only be used for a limited number of special vehicles such as supercars.

[0013] Prior art literature

[0014] Patent Literature

[0015] Patent Document 1: Japanese Patent Publication No. 6-51308

[0016] Patent Document 2: Japanese Patent No. 6652523

[0017] Non-patent literature

[0018] Non-patent document 1: Sachihiro Isogawa, Yoshio Enomoto, Hisao Kobayashi, Shougo Nasu, "High cycle deep drawing of PA6 matrix carbon fiber reinforced thermoplastics by servo-driven screw press", "Procedia Manufacturing", Available online 11 August 2018, Version of Record 11 August 2018., Volume 15, p.1722-1729

[0019] Non-Patent Document 2: "CFRTP Automobile Tires and Wheels" Rapiit Co., Ltd., product catalog, [retrieved on October 3, 2022], Internet<URL: https: / / www.ipros.jp / catalog / detail / 498804> Summary of the Invention

[0020] Problems to be solved by the invention

[0021] The main object of the present invention is to enable the production of a wheel made of thermoplastic fiber-reinforced resin with good moldability in a short time while ensuring mechanical properties and to enable the production of a wheel having a wide rim portion.

[0022] Means for solving problems

[0023] The method for this purpose is a method for manufacturing a wheel made of thermoplastic fiber reinforced resin, wherein the method for manufacturing a wheel made of thermoplastic fiber reinforced resin uses a mold to shape a raw material composed of thermoplastic fiber reinforced resin to manufacture a wheel with a rim portion and a disc portion integrated therein, wherein the mold is set to a temperature lower than the melting point of the resin matrix as a component of the raw material, and after the billet-shaped raw material and the sheet-shaped raw material as the raw material are heated to a temperature higher than the melting point of the resin matrix as their components, the billet-shaped raw material is maintained in the outer surface mold of the disc and the outer diameter mold of the rim. On the other hand, the sheet raw material is maintained on the surface of the punch side opposite to the disc outer surface mold in the rim outer diameter mold, the outer periphery of the sheet raw material is pressed by a wrinkle-proof plate, and the sheet raw material is deep-drawn by the punch and the rim outer diameter mold to form the rim part of the wheel, and at the same time, a part of the sheet raw material is pressed against the billet-shaped raw material to join the two, and the billet-shaped raw material is compression-molded by the disc outer surface mold, the rim outer diameter mold and the punch to form the disc part of the wheel.

[0024] In this configuration, the sheet material and billet material, each having a different shape, are plastically deformed in a manner that minimizes inconsistencies in their shape matching, and are then joined and integrated while undergoing plastic deformation. Deep drawing of the sheet material allows for the formation of a wide rim portion, while compression molding of the billet material eliminates the need for a rim portion, thus eliminating the need for excessive volume and molding load. Furthermore, the sheet material and billet material, heated to a temperature higher than the melting point of the resin matrix, are rapidly plastically deformed into the desired shape within a mold maintained at a predetermined temperature lower than the melting point of the resin matrix, and the temperature is then reduced.

[0025] Effects of the Invention

[0026] According to the present invention, the wheel can be formed in an extremely short time, on the order of minutes, by organically combining deep drawing of a sheet-like material with compression molding of a billet-like material. The rim and disc parts are rationally molded and joined together in a series of actions. Furthermore, the molding of each material is performed in a manner that minimizes inconsistencies in the shape of the material. Therefore, the flow of the material during molding of the rim and disc parts can be easily controlled, and excessive anisotropy of the reinforcing fibers can be suppressed, thereby ensuring mechanical properties. Furthermore, since the rim part is formed by deep drawing a sheet-like material, a wide rim part can also be formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of a method for manufacturing a thermoplastic fiber-reinforced resin wheel.

[0028] Figure 2 This is the front view of the wheel and its AA section view.

[0029] Figure 3 It is a three-dimensional diagram of sheet-shaped raw materials and billet-shaped raw materials.

[0030] Figure 4 It is a plan view showing the structure of a continuous fiber laminated pseudo-isotropic fabric sheet.

[0031] Figure 5 This is a single-side cross-sectional view of a billet-shaped raw material.

[0032] Figure 6 It is a cross-sectional view showing the structure of the mold.

[0033] Figure 7 This is a cross-sectional view showing the raw material being held in the mold.

[0034] Figure 8 It is a cross-sectional view showing the molding process.

[0035] Figure 9 It is a cross-sectional view of the formed state.

[0036] Figure 10 This is a cross-sectional view showing a molding state for reinforcing the rim portion as another example.

[0037] Figure 11 It is a perspective view showing the states before and after molding of a raw material on which additional sheet-like raw materials are stacked.

[0038] Figure 12 This is a one-side cross-sectional view of a billet-shaped material including a reinforcing sheet as another example.

[0039] Figure 13 It is a top view of a billet-shaped raw material with a reinforcing sheet.

[0040] Figure 14 It is a cross-sectional view showing a molded state using a reinforcing sheet.

[0041] Figure 15 This is a front view of a molded product with a reinforcement sheet.

[0042] Figure 16 is a front view of a wheel with a reinforcement plate. DETAILED DESCRIPTION

[0043] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0044] The present invention is used for manufacturing an automobile wheel (hereinafter referred to as "wheel") having an integrated rim portion and a disc portion by die molding, using a thermoplastic fiber-reinforced resin as a molding raw material (intermediate base material).

[0045] Thermoplastic fiber-reinforced resins are SMC (Sheet Molding Compound), BMC (Bulk Molding Compound), Carbon Fiber Reinforced Plastic (FRP), stampable sheets, etc., which are called Forged Carbon Sheet (forged carbon sheet), Forged Carbon Fiber Sheet (forged carbon fiber sheet), etc., and are mainly composed of a resin matrix (parent material) and reinforcing fibers (reinforcement material).

[0046] Figure 1 The main part of the automobile wheel manufacturing method is shown in FIG. In this manufacturing method, the prepared raw material 11 is heated and then formed using a mold 31 to obtain a wheel-shaped molded product. After that, if the molded product taken out of the mold 31 is subjected to post-processing such as cutting, the obtained wheel is obtained. Figure 2 An intermediate product 71 of a wheel as shown (hereinafter also referred to as "wheel 71") is shown.

[0047] First, the raw material 11 will be described.

[0048] As raw material 11, use Figure 3 The raw materials are shown in two shapes: one is in sheet form and the other is in billet or block form.

[0049] The sheet-like material 11 (sheet-like material 11a) primarily constitutes the rim portion 72 of the wheel 71. It has a thickness equal to or greater than that of the rim portion 72 and is formed into a circular plate shape extending in the plane. A through-hole 12 is formed in the center of the plane, extending through the thickness. Deep drawing is performed during the forming process. Besides the circular shape shown in the illustration, the through-hole 12 may also have other shapes.

[0050] Furthermore, the sheet-like material 11 a may be formed by laminating two or more sheets instead of being formed by a single sheet.

[0051] The billet or block-shaped raw material 11 (billet-shaped raw material 11b) primarily constitutes the disc portion 73 of the wheel 71. It is formed into a block of a size suitable for compression molding or into a shape having a predetermined size, volume, and capacity. Specifically, it is formed into a short cylindrical shape with a predetermined thickness and diameter to match the mold cavity, and a through-hole 13 in the center. Compression molding is performed during the molding process. This through-hole 13 may have other shapes besides the circular shape shown in the illustration.

[0052] The reinforcing fibers 14 of the raw material 11 can be made of chopped materials (chopped fibers), short chips, continuous fiber cloth (fabric) sheets, etc., and preferably, materials having carbon fibers or glass fibers as fibers can be used. In particular, as for the sheet-like raw material 11a, chopped materials and short chips can also be used, but it is preferable to use materials having continuous fibers as the reinforcing fibers 14. More preferably, it can be a continuous fiber cloth sheet. If the shear deformation of the fabric structure during deep drawing and the deviation of the fibers are taken into consideration, such as Figure 4 As shown, the direction of the continuous fiber cloth sheet 14a can be changed by a certain angle α each time and the isotropic continuous fiber layered pseudo-isotropic cloth sheet 15 with improved strength and deformation can be used as the reinforcing fiber 14. Figure 4 In the example of FIG. 1 , the continuous fiber laminated pseudo-isotropic fabric sheet 15 is formed by stacking the necessary number of continuous fiber fabric sheets 14a composed of warp and weft yarns while rotating them 22.5 degrees at a time.

[0053] Considering the moldability during compression molding, the billet-shaped raw material 11b is a pseudo-isotropic material having chopped material (chopped fiber) and short chips as the reinforcing fiber 14. If the rigidity of the molded product is considered in addition to the moldability, it is more preferable to use a pseudo-isotropic random system sheet SMC16 having short chips as the reinforcing fiber 14. Figure 5 As shown, a plurality of SMC sheets are stacked in the thickness direction to form a billet-shaped material 11b. The thickness direction of the SMC 16 corresponds to the compression direction during compression molding.

[0054] The resin matrix of the sheet-shaped material 11a and the billet-shaped material 11b may be a resin matrix having good compatibility with each other, and the same resin is usually used. For example, thermoplastic epoxy resin, polyamide, etc. can be used as the resin.

[0055] Next, an apparatus used in the production method will be described.

[0056] The manufacturing method is to heat the billet-shaped material 11b and the sheet-shaped material 11a to a temperature higher than the melting point of the resin matrix as their constituent elements, and then perform high-speed molding using a mold 31 set at a temperature lower than the melting point of the resin matrix.

[0057] Therefore, as a device, Figure 1 As shown, in addition to the mold 31 for forming, heating devices 51 and 52 for heating the sheet material 11a and the billet material 11b are also provided. The heating devices 51 and 52 can use any appropriate heating method, but from the perspective of achieving ideal heating without internal and external heating unevenness in a short time, IR (infrared) heating is preferably used.

[0058] The heating device 51 for heating the sheet material 11a has heaters 53 above and below, and has an input port 54 serving as an inlet and an output port 55 serving as an outlet for the conveyance path between the heaters 53. The sheet material 11a is input and output by an automatic conveyor.

[0059] The heating device 52 for heating the billet-shaped material 11b is similar to the heating device 51 for the sheet-shaped material 11a. The billet-shaped material 11b is heated while being transported and stacked. A heat-insulating tank 56 is provided downstream of the heating device 52. The heat-insulating tank 56 holds the billet-shaped material 11b, formed by stacking the sheets (SMC 16), and uniformly heats it.

[0060] The heating temperature of the sheet-shaped material 11a and the billet-shaped material 11b is higher than the melting point of their resin matrix. When the resin matrix is, for example, polyamide, the temperature can be heated to approximately 280°C. This temperature also takes into account the temperature drop during molding and is approximately 30°C to 70°C higher than the melting point.

[0061] The mold 31 for forming is composed of a disc outer surface mold 32, a rim outer diameter mold 33 and a punch 34. The disc outer surface mold 32 serves as a lower mold and mainly forms the outer surface of the disc portion 73 of the wheel 71. The rim outer diameter mold 33 moves radially on the upper surface of the disc outer surface mold 32 to form the outer peripheral surface of the rim portion 72 of the wheel 71, and is divided into multiple parts in the circumferential direction. The punch 34 serves as an upper mold and mainly forms the inner peripheral surface of the rim portion 72 and the inner surface of the disc portion 73. It is supported so as to be able to move up and down from the side of the rim outer diameter mold 33 opposite to the disc outer surface mold 32 toward the disc outer surface mold 32.

[0062] A wrinkle prevention plate 35 is provided above the closed rim outer diameter die 33, which moves up and down in the same manner as the punch die 34. The wrinkle prevention plate 35 allows the outer periphery of the sheet material 11a placed on the upper surface of the rim outer diameter die 33 to be drawn in while simultaneously pressing it, thereby preventing wrinkles from forming on the sheet material 11a during deep drawing.

[0063] The structure of the mold 31 will be described. It should be noted that, for example, the wheel 71 can have various shapes, including those with bulging, flat, or concave outer surfaces, such as positive offset, zero offset, and negative offset, depending on the distance from the centerline of the wheel (rim width) to the mounting surface. The shape of the mold 31 also varies depending on the wheel shape, and the mold 31 shown in the figure is one example. The manufacturing method of the present invention is not limited to the shapes shown in the figure.

[0064] like Figure 1 、 Figure 6 As shown, the disk outer surface mold 32 is generally flat and has a shaft portion 36 formed in the center, facing vertically upward. The shaft portion 36 is located at a position corresponding to the center hole 74 of the wheel 71 and has an undulating surface 37 along its entire circumference corresponding to the outer surface of the disk portion 73. The portion further outward from the shaft portion 36 serves as a support surface 38 for supporting the rim outer diameter mold 33.

[0065] The front end of the shaft 36 forms a fitting portion 36a that engages with the die 34 and is the thinnest portion of the shaft 36. Below the fitting portion 36a, a large-diameter portion 36c is formed via a step 36b. The diameter of the large-diameter portion 36c is smaller than the diameter of the through-hole 13 of the billet-shaped material 11b. At its base, or lower end, the large-diameter portion 36c has an inclined portion 36d, whose diameter increases downward, like the foot of a mountain. The diameter of the inclined portion 36d at its lower end is larger than the diameter of the through-hole 13 of the billet-shaped material 11b.

[0066] The rim outer diameter mold 33 has a recess 39 at its lower end, which forms the portion where the tire is assembled from the outer flange 75 of the wheel 71. A concave-convex portion 41 is formed upward from the recess 39, extending inward and outward along the shape of the rim portion 72. A rounded portion 42 is formed at the upper end, above the portion 41a that forms the inner flange 76 of the wheel 71.

[0067] The wrinkle preventing plate 35 presses the upper surface of the rim outer diameter mold 33 , that is, the portion on the outer peripheral side of the fillet portion 42 . The wrinkle preventing plate 35 is plate-shaped and is formed in an annular shape as a whole.

[0068] The die 34 has a fitting recess 43 at the center of its lower surface that fits with the fitting portion 36a of the shaft portion 36 in the disk outer surface mold 32. Furthermore, the die 34 has an outer peripheral surface 44 shaped to fit within the rim outer diameter mold 33 when closed, with a gap corresponding to the thickness of the rim portion 72. The portion 44a of the outer peripheral surface 44 that forms the inner flange 76 of the wheel 71 is particularly formed to create a molding space of a desired shape with consideration for mechanical properties between the portion 44a and the corresponding portion of the rim outer diameter mold 33.

[0069] The depth of the fitting recess 43 is set so that a gap d1 is formed between the bottom of the fitting recess 43 and the front end of the shaft portion 36 even at the bottom dead center of the die 34. Furthermore, the dimensions of the periphery of the shaft portion 36 are designed so that a relief portion 45 is formed near the edge of the fitting recess 43 so that the billet-shaped material 11b does not reach it when the die 34 reaches the bottom dead center.

[0070] The portion of the wheel 71 on the outer circumference of the fitting recess 43 is an annular recess 46 formed on the outer circumference of the center hole 74. The portion of the wheel 71 on the outer circumference of the fitting recess 43 is an extension 47 formed on the spokes 77 of the wheel 71 and the portion between the spokes 77 corresponding to the window 78. The extension 47 protrudes downward from the annular recess 46. The portion of the extension 47 corresponding to the window 78 is formed so that the thickness becomes thinner after molding between the extension 47 and the undulating surface 37 of the wheel outer surface mold 32.

[0071] Such a mold 31 is equipped with a temperature control mechanism (not shown) for maintaining a constant temperature of the mold 31. The temperature control mechanism is configured by providing a flow path for a medium such as water to flow, and is configured to maintain a predetermined temperature by monitoring and adjusting the flow rate and temperature of the medium. The temperature control mechanism can also be configured by inserting a cartridge heater into the mold 31.

[0072] The temperature of mold 31 is lower than the melting point of the resin matrix of sheet material 11a and billet material 11b, and preferably lower than the glass transition temperature. Specifically, when the resin matrix is ​​a thermoplastic epoxy resin, the temperature can be 100°C to 130°C, particularly below 120°C, and can also be below 80°C, around 50°C. A temperature above a certain required temperature is preferred because lower temperatures can suppress adhesion of the resin matrix to mold 31, shorten the hold time, and further reduce cycle time.

[0073] The above-described apparatus forms the sheet-shaped material 11 a and the billet-shaped material 11 b as follows to manufacture the wheel 71 .

[0074] The mold 31 is closed, and its temperature is set to a predetermined temperature lower than the melting point of the resin matrix of the raw material.

[0075] While preparing this, the thermoplastic fiber-reinforced resin is cut by water jetting or the like, thereby preparing the sheet material 11a and the sheet material (SMC 16) for forming the billet material 11b. These are placed in heating devices 51 and 52 and heated to a predetermined temperature. The heated sheet material (SMC 16) is then stacked on the billet material 11b and uniformly heated in a heat-retaining tank 56.

[0076] Then, the punch 34 is raised to open the mold 31, as shown in FIG. Figure 7As shown, the billet-shaped material 11b is placed in the die 31. At this time, the shaft portion 36 and the inclined portion 36d of the disk outer surface die 32 align the center of the billet-shaped material 11b with the center of the disk outer surface die 32.

[0077] Immediately thereafter, the sheet material 11a is placed on the upper surface of the rim outer diameter mold 33, and the wrinkle preventing plate 35 is lowered to press the outer periphery of the sheet material 11a. The wrinkle preventing plate 35 is heated and kept at a lower temperature than the sheet material.

[0078] At this time, the temperature of the mold 31 is lower than the heating temperature of the sheet material 11a and the billet material 11b. Therefore, the temperature of the sheet material 11a and the billet material 11b, which have been cooled after coming out of the heating device 51 and the heat-insulating tank 56, further decreases.

[0079] After the sheet-like material 11a and the billet-like material 11b are placed in the mold 31, Figure 8 If the die 34 is immediately lowered as shown, high-speed forming is possible. Specifically, when the die 34 is lowered, the lower end of the protruding portion 47 first contacts the upper surface of the sheet material 11a, pressing the abutting portion downward. As the die 34 descends, the sheet material 11a is drawn into the mold 31 and deep-drawn, gradually forming the rim portion 72 along the rim outer diameter mold 33 and the die 34. At this point, the rim portion 72 cools and solidifies.

[0080] The inner peripheral portion of the sheet material 11a, which is pressed down by the lower end of the protruding portion 47, contacts the upper surface of the billet material 11b from above and is pressed against the billet material 11b by the die 34. As a result, the sheet material 11a and the billet material 11b are joined and integrated with each other, and further deform. When the die 34 reaches the bottom dead center, Figure 9 As shown, the desired shaping of the sheet-shaped raw material 11 a and the billet-shaped raw material 11 b is completed.

[0081] At this time, the front end of the shaft portion 36 of the wheel outer surface mold 32 does not contact the bottom of the fitting recess 43 of the punch 34, and a space, i.e., a relief portion 45, is formed near the edge of the fitting recess 43 where the compression-molded billet-shaped material 11b does not reach. Therefore, although the forming load increases after the sheet-shaped material 11a and the billet-shaped material 11b come into contact, an extreme increase in the forming load can be avoided.

[0082] While molding with mold 31 depends on the size of the molded product, even holding it at bottom dead center for 15 seconds can take less than a minute. Furthermore, unlike the meticulous placement of large quantities of material, holding the raw material 11 within mold 31 can be performed quickly and easily. Consequently, the molding process, including removal of the molded product, can be completed in under a minute.

[0083] The molded product removed from the mold 31 is left to cool at room temperature, and then subjected to post-processing such as cutting of the portion protruding from the inner flange 76 and the window portion 78 to form the wheel 71 (see FIG. Figure 2 ).

[0084] As described above, during the molding process using the mold 31, the sheet material 11a is deep-drawn, while the billet material 11b is compression-molded, and the two are joined during the molding process. Furthermore, since the inner circumference of the sheet material 11a is pressed down to form a cylindrical shape, the desired rim portion 72 can be efficiently obtained, and the rim portion 72 can also be formed to a wider width. In the case of the billet material 11b, only the disc portion 73 is formed, eliminating the need for the rim portion 72, thus eliminating the need for excessive volume and molding load. The formation of the relief portion 45 also reliably prevents a sudden increase in the molding load.

[0085] This forming process can be described as an organic combination of deep drawing of the sheet material 11a and compression molding of the billet material 11b. Through a series of operations, the rim portion 72 and the disc portion 73 are optimally formed and joined together. Consequently, the wheel 71 can be formed in an extremely short time, on the order of minutes, with excellent formability. Furthermore, since the forming process minimizes mismatches in the shapes of the sheet material 11a and the billet material 11b, the flow of the materials during forming can be easily controlled. By suppressing excessive anisotropy in the reinforcing fibers 14, the mechanical properties of the wheel can be maintained.

[0086] Furthermore, there is no excessive deformation during molding, and the flow of the raw material can be easily controlled, so local reinforcement can be performed, thereby achieving sufficient mechanical properties.

[0087] For example, during molding, in order to make the thickness of the portion of the rim portion 72 corresponding to the inner flange 76 thicker than other portions of the rim portion 72 or to increase the strength, the following is performed.

[0088] That is, Figure 10As shown, a material with an additional sheet material 11c laminated on a portion of the sheet material 11a is used. The additional sheet material 11c can be made of a material having chopped material as reinforcing fiber, a continuous fiber cloth sheet 14a, a continuous fiber laminated pseudo-isotropic cloth sheet 15, etc., depending on the purpose. In order to improve the strength, it is preferable to use a fiber-reinforced resin sheet having a continuous fiber cloth sheet as the additional sheet material 11c. It should be noted that Figure 10 In the figure, for the sake of convenience, the anti-wrinkle plate 35 is omitted.

[0089] The additional sheet material 11c is formed into a circular ring of appropriate width. Its stacking position is set to a location on the upper surface of the sheet material 11a where deformation during deep drawing causes it to move to a portion where thickness, rigidity, and strength are to be increased after forming, such as the portion 41a forming the inner flange 76. The additional sheet material 11c can be stacked on the sheet material 11a not only on the upper surface but also within the sheet material 11a, that is, between the sheets that comprise the sheet material 11a, or on the lower surface of the sheet material 11a.

[0090] When forming using this sheet material 11a, the stacked additional sheet material 11c is drawn and formed while being integrally drawn with the sheet material 11a, reaching the portion 41a forming the inner flange 76. It then flows as indicated by the arrows, forming into the desired final, thicker shape. Therefore, even if the inner flange 76 portion is thicker than the other portions, sufficient forming is possible. If the additional sheet material 11c comprises a continuous fiber cloth sheet, the stacking of the sheet materials 11a and 11c can achieve increased rigidity and strength.

[0091] Figure 11 Another example of an additional sheet material 11c is shown in . This additional sheet material 11c is used to reduce changes in fiber orientation during deep drawing and to improve strength in the circumferential and width directions.

[0092] Specifically, the additional sheet material 11c is a sheet material having a continuous fiber cloth as reinforcing fibers, and has a notch 23 formed at a position 45 degrees relative to the horizontal and vertical directions of fiber extension in the peripheral portion 22 surrounding the central portion 21. The notch 23 has a shape that increases in width toward the outer periphery. Furthermore, the contour lines 24 forming the notch 23 are formed to be joined during deep drawing.

[0093] Specifically, the additional sheet material 11c is sized to fit within the disk-shaped sheet material 11a and has a shape roughly like the petals of an open flower. In other words, the disc-shaped sheet material 11c has cutouts 23 formed at equal intervals along the circumference, and has petal-shaped portions 25 separated by the cutouts 23. A through-hole 26, similar to the through-hole 12 in the sheet material 11a, is formed in the center.

[0094] The cutouts 23 in the peripheral portion 22 are roughly fan-shaped, with two contour lines extending radially outward from the corners of the fan near the central portion 21. If the fiber extension is defined as the east, west, south, and north in the horizontal and vertical directions, the cutouts 23 are arranged in the northeast, southeast, southwest, and northwest directions. Furthermore, the two opposing contour lines 24 forming the four cutouts 23 are formed to meet during deep drawing, i.e., to abut or overlap each other, in accordance with the shape of the rim.

[0095] When this additional sheet material 11c is stacked on the sheet material 11a and formed, the stacked additional sheet material 11c is drawn and formed while being drawn integrally with the sheet material 11a. At this point, the petal-shaped portions 25 of the additional sheet material 11c, separated by the cuts 23, approach each other, and the contour lines 24 are joined. This joined portion is pressed into place by the surrounding material, ensuring strength. Figure 11 27 is a joining line where the contour lines 24 join each other.

[0096] The fibers of the continuous fiber cloth sheet, which serves as reinforcing fibers and constitutes the additional sheet-like material 11c, extend in the circumferential and width directions, enhancing strength in these directions. During deep drawing, the petal-shaped portions 25 are deformed so as to fold along the rim outer diameter mold 33, resulting in little change in the intersecting angle of the fibers in the continuous fiber cloth sheet. This results in high strength.

[0097] In the forming of the disk portion 73 , since there is no complicated and excessive deformation, the flow of the billet-shaped material 11 b is also easily controlled, and sufficient mechanical properties can be locally ensured.

[0098] For example, when it is desired to reinforce the space between the spokes 77 and the outer flange 75 of the disc portion 73 during molding, the following is performed.

[0099] That is, when the billet-shaped material 11b is a material in which a plurality of pseudo-isotropic random sheets SMC16 having short pieces as reinforcing fibers 14 are stacked in the thickness direction, as shown in FIG. Figure 12As shown, a material with reinforcement sheets 17 between SMCs 16 is used. Reinforcement sheets 17 can be made of continuous fiber cloth. Alternatively, a material with three-ply woven sheets (quasi-isotropic cloth) as reinforcing fibers, such as "QISO" (registered trademark) from A&P Technology, can be used.

[0100] The reinforcing sheet 17 has the same thickness as the SMC 16 and is sandwiched between the SMCs 16 .

[0101] The reinforcing sheet 17 moves in the outer peripheral direction along with deformation during compression molding of the billet-shaped material 11 b . To achieve this movement, the reinforcing sheet 17 is located on the outer peripheral side of the billet-shaped material 11 b and is divided in the circumferential direction.

[0102] Figure 12 (a) shows an example in which the reinforcing piece 17 is provided on the outer surface side of the disk portion 73 , and (b) shows an example in which the reinforcing piece 17 is provided on the inner surface side in addition to the outer surface side.

[0103] Specifically, if Figure 13 As shown, the reinforcement tabs 17 of the billet-shaped material 11b are formed into a generally fan-shaped shape, with multiple tabs 17 arranged at equal intervals to match the number of spokes 77. When the billet-shaped material 11b is housed in the die 31, its circumferential orientation is determined so that the spokes 77 are formed in the portion having the reinforcement tabs 17. This is facilitated by providing a restrictive structure between the tab 36 and the through-holes 13 of the billet-shaped material 11b, as the wheel outer surface die 32 includes the shaft portion 36.

[0104] And, if forming is performed, Figure 14 As shown, when the billet-shaped material 11b is compressed and deformed to expand in the outer and inner circumferential directions, the reinforcing sheet 17 moves in the outer circumferential direction and is located between the outer flange 75 and the outer circumferential end of the spoke 77. Figure 14 The diagram depicts the Figure 12 An example of forming a billet-shaped material 11b shown in (a).

[0105] Figure 15 FIG1 shows a front view of the molded product 18. In the post-processing of the molded product 18, the portion corresponding to the window 78 including the reinforcing sheet 17 is cut to open the window 78. Figure 16 As shown, the T-shaped reinforcement piece 17 in a front view remains so as to connect the outer flange 75 and the spoke 77, thereby improving the strength of this portion.

[0106] The above configuration is one embodiment of the present invention, and the present invention is not limited to the above configuration, but may employ other configurations.

[0107] For example, instead of using the aforementioned annular material as the additional sheet material 11c, the structure for overlay welding and reinforcing a portion of the rim portion 72 may employ a circumferentially discontinuous material for local reinforcement. Extending the additional sheet material 11c along the rim width after molding can improve strength. Furthermore, the additional sheet material 11c may have a shape that combines both circumferentially discontinuous and circumferentially continuous portions.

[0108] The billet-shaped material 11b may also include a reinforcement sheet (not shown) that is not intended to move during molding. The reinforcement sheet may be a continuous fiber cloth sheet 14a or a continuous fiber laminated pseudo-isotropic cloth sheet 15. In this case, since it is not intended to move, a circumferentially continuous annular shape may be used.

[0109] In the above example, the sheet material 11a is set to a disk shape, but the sheet material 11a may be in other shapes. Figure 11 The additional sheet material 11c shown in the example is similarly formed in a shape with cutouts having contour lines that are joined to each other during deep drawing, i.e., a shape in which petals are opened. When using the sheet material 11a of this shape, the additional sheet material 11c can be omitted. In this case, the additional sheet material 11c can also be omitted. Figure 4 Similarly, from the perspective of strengthening the joint portion, the directionality of the sheet material in the shape of open petals is preferably staggered at a certain angle each time. Figure 11 In the case of the sheet material shown as an example, a plurality of sheets are stacked so as to be shifted by 45 degrees each time.

[0110] Explanation of symbols

[0111] 11…raw materials

[0112] 11a…Flake raw materials

[0113] 11b…Bill-shaped raw materials

[0114] 11c…Additional sheet material

[0115] 13…Through hole

[0116] 14…Reinforcement fiber

[0117] 14a…continuous fabric

[0118] 15…Continuous fiber laminated fabric

[0119] 16…SMC

[0120] 17…Reinforcement sheet

[0121] 31…Mold

[0122] 32…Rotary disc outer surface mold

[0123] 33…Rim outer diameter mold

[0124] 34…die

[0125] 35…anti-wrinkle plate

[0126] 36…Shaft

[0127] 71…Intermediate products of wheels

[0128] 72…Rim

[0129] 73…Roulette section.

Claims

1. A method for manufacturing a wheel made of thermoplastic fiber reinforced resin, wherein a raw material made of thermoplastic fiber reinforced resin is molded using a mold to manufacture a wheel having a rim portion and a disc portion integrated therein, wherein: The mold is set to a temperature lower than the melting point of the resin matrix which is a component of the raw material. After heating the billet-shaped raw material and the sheet-shaped raw material as the raw materials to a temperature higher than the melting point of the resin matrix as their constituent elements, The billet-shaped raw material is held in a die formed by a disc outer surface die and a rim outer diameter die. On the other hand, the sheet-shaped raw material is held on the die side opposite to the disc outer surface die in the rim outer diameter die, and the outer periphery of the sheet-shaped raw material is pressed by a wrinkle-proof plate. The sheet raw material is deep-drawn by the punch and the rim outer diameter mold to form the rim portion of the wheel, and at the same time, a portion of the sheet raw material is pressed against the billet-shaped raw material to join the two, and the billet-shaped raw material is compression-formed by the wheel disc outer surface mold, the rim outer diameter mold and the punch to form the wheel disc portion.

2. The method for manufacturing a thermoplastic fiber reinforced resin wheel according to claim 1, wherein: The billet-shaped raw material has a through hole in the center, The shaft portion provided at the center of the wheel disc outer surface mold is inserted into the through hole and retained.

3. The method for manufacturing a thermoplastic fiber reinforced resin wheel according to claim 1 or 2, wherein: As the sheet-like raw material, a sheet having a continuous fiber cloth sheet as reinforcing fibers is used.

4. The method for manufacturing a thermoplastic fiber reinforced resin wheel according to claim 1 or 2, wherein: As the sheet-like raw material, a sheet having a continuous fiber-laminated pseudo-isotropic cloth sheet as reinforcing fibers is used.

5. The method for manufacturing a thermoplastic fiber reinforced resin wheel according to claim 1 or 2, wherein: As the sheet-like raw material, a sheet having chopped material as reinforcing fibers is used.

6. The method for manufacturing a thermoplastic fiber reinforced resin wheel according to claim 1 or 2, wherein: As the sheet-like material, a material having an additional sheet-like material made of a thermoplastic fiber-reinforced resin layered on a portion thereof is used. The stacking position of the additional sheet-like material is set so as to be moved to a position where the thickness, rigidity, and strength should be higher than other portions after forming due to deformation during deep drawing.

7. The method for manufacturing a thermoplastic fiber reinforced resin wheel according to claim 6, wherein: The additional sheet-like raw material is a sheet having a continuous fiber cloth sheet as a reinforcing fiber, and A notch is formed at a position at 45 degrees relative to the horizontal and vertical directions of fiber extension in the peripheral portion surrounding the central portion of the additional sheet-like material, with the notch becoming wider toward the outer peripheral side. The contour lines forming the cutouts are shapes that engage with each other during the deep drawing process.

8. The method for manufacturing a thermoplastic fiber reinforced resin wheel according to claim 1 or 2, wherein: As the billet-shaped raw material, a material in which a plurality of sheets having short chips as reinforcing fibers are stacked in the compression direction of the die is used.

9. The method for manufacturing a thermoplastic fiber reinforced resin wheel according to claim 8, wherein: Between the sheets there is a reinforcement sheet made of a continuous fiber cloth sheet. During compression molding, the reinforcing sheet is moved in the outer peripheral direction.

Images