Manufacturing apparatus and manufacturing method for fiber reinforced plastic molded products

Abstract

Provided is an apparatus and method for manufacturing thermoplastic fiber reinforced resin molded products that reduce costs and increase yields. [Solution] A manufacturing apparatus for manufacturing a box-shaped fiber-reinforced plastic molded product consisting of a bottom surface and side surfaces consisting of three or more flat surfaces, the manufacturing apparatus comprising: a lower mold having a convex portion and an upper mold having a concave portion, the convex portion having a first heating means for heating a convex corner portion corresponding to a corner formed between the bottom surface of the fiber-reinforced plastic molded product and two adjacent flat surfaces, and the concave portion having a second heating means for heating a concave corner portion corresponding to a corner formed between the bottom surface of the fiber-reinforced plastic molded product and two adjacent flat surfaces.

Description

[Technical field]

[0001] The present invention relates to a manufacturing apparatus and a manufacturing method for manufacturing a thermoplastic fiber reinforced resin molded product by press processing a prepreg. [Background technology]

[0002] In recent years, due to environmental issues, the automotive and aviation industries have been working to improve fuel efficiency. As part of this effort, there are hopes that fiber-reinforced plastics will be used instead of metals to reduce the weight of car and aircraft bodies, and this has attracted a lot of attention. The resins used in fiber reinforced resins are thermoplastic resins and thermosetting resins, and fiber reinforced resins are made by reinforcing fibers with these resins. Fiber reinforced resins are widely used in various fields due to their characteristics such as being moldable or shaped by heating, having high productivity, being easy to perform secondary processing such as welding, having electrical insulation, not corroding, and having excellent recyclability. In addition, carbon fiber reinforced resin, which uses carbon fiber as the fiber, is lightweight and has high strength and rigidity, so research into its applications has been conducted in a wide range of fields, including the aforementioned automotive and aviation industries, as well as the shipping industry, space field, wind power generation, and sporting goods, and it is already in use.

[0003] Methods for manufacturing fiber-reinforced plastic molded products include autoclave molding, oven molding, press molding, RTM / VaRTM method, pultrusion molding, filament winding, and sheet winding. Of these, press molding is considered to be the most desirable method because it is highly productive and can produce high-quality fiber-reinforced plastic molded products.

[0004] The molding of fiber-reinforced resin molded products is preferably carried out using prepregs as materials, which are made by impregnating a fibrous reinforcing material such as glass cloth or carbon fiber with a resin mixed with additives such as a curing agent and an adhesive, and then heating or drying the prepregs to a semi-cured state.

[0005] However, fiber-reinforced resin prepregs are less malleable than metals, and if they are press-molded at the same speed as metals such as iron, they will tear or wrinkle. In addition, if too much heat is applied to the prepregs during molding, the resin viscosity drops too much, causing the resin to melt and making it impossible to form a clean molded product. Also, if heat is not applied, the viscosity does not drop, resulting in molding defects.

[0006] For example, Patent Document 1 describes a method for producing a fiber-reinforced plastic molded product from a fiber-reinforced plastic prepreg by setting appropriate conditions. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6656702 Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, fiber-reinforced resin molded products have been used in various fields, and their applications, shapes, sizes, and required costs are different. Therefore, press molding that can meet the increasing needs is required. Thermosetting resins such as epoxy resins have been mainly used as the matrix resin of resin-based composite materials due to reasons such as prepreg manufacturability and moldability, but thermoplastic resin composite materials, which have features such as high toughness, recyclability, and mass production, and are being developed to improve prepreg manufacturability and moldability, which were traditional technical issues, are attracting attention. Patent Document 1 is for thermosetting resin prepregs, and there is no mention of thermoplastic resin prepregs. The molding temperature of thermoplastic resin prepregs is higher than that of thermosetting resin prepregs, so it is desirable to mold them using a mold that can handle higher temperatures than the mold used for thermosetting resin prepregs. However, when thermosetting resin prepregs are mainstream and a mold that can handle the molding temperature of thermosetting resin prepregs is used, standard parts such as steel materials, heating devices, and mold-mounted parts exist, but when a mold that can handle higher temperatures is used, there are no standard parts, and costs increase. In addition, a method in which a thermoplastic resin prepreg is heated to a molding temperature and molded in a mold for thermosetting resin prepreg is widespread, but the thermoplastic resin prepreg is heated to a temperature required for molding the resin using an infrared heater or the like, and then moved to a molding facility, but the temperature drops in the tens of seconds it takes to move it to the mold, and in order to further heat it to the temperature required for molding the thermoplastic resin, the entire mold must be heated, which not only requires high electricity costs but also requires heating time. In addition, if the product is not heated sufficiently, whitening occurs on the surface of the fiber-reinforced resin molded product when pressed, or the fibers get caught and the fibers are cut at the corners of the fiber-reinforced resin molded product, resulting in a poor yield. Therefore, an object of the present invention is to provide an apparatus and method for manufacturing a thermoplastic fiber reinforced resin molded product that reduces costs and increases yields. [Means for solving the problem]

[0009] As a result of extensive research, the inventors have discovered an apparatus and method for manufacturing a reinforced plastic molded product that reduces costs and increases yields by providing a mold with a cartridge heater that locally heats areas corresponding to corners formed by three or more faces of a box-shaped fiber-reinforced plastic molded product. [1] A manufacturing apparatus for manufacturing a fiber-reinforced plastic molded product having a box shape composed of a bottom surface and a side surface composed of three or more planes, A lower die having a protrusion; an upper die having a recess; The convex portion has a first heating means for heating a convex corner portion corresponding to a corner portion formed by the bottom surface of the fiber-reinforced plastic molded product and two adjacent flat surfaces, The manufacturing apparatus includes a second heating means for heating a recessed corner portion corresponding to a corner portion formed by the bottom surface of the fiber-reinforced resin molded product and two adjacent flat surfaces. [2] The manufacturing apparatus according to [1], wherein the fiber-reinforced resin molded product contains a thermoplastic resin. [3] The manufacturing apparatus according to [1], wherein during press molding, the difference in temperature between the center of gravity of the top surface of the convex portion corresponding to the center of gravity of the bottom surface and the temperature of the convex corner portion is 30°C or more. [4] A method for producing a fiber-reinforced plastic molded product by the manufacturing apparatus according to [1], A step of heating a convex corner portion corresponding to a corner portion formed by the bottom surface of the fiber reinforced resin molded product and two adjacent flat surfaces by the first heating means; A step of heating a recessed corner portion corresponding to a corner portion formed by the bottom surface of the fiber reinforced resin molded product and two adjacent flat surfaces by the second heating means; placing a fiber reinforced resin prepreg in the lower mold; A step of sandwiching and pressing the fiber reinforced prepreg between the upper mold and the lower mold; and separating the upper die and the lower die to remove the fiber reinforced resin molded product. [5] The manufacturing method described in [4], wherein the temperature of the convex corner heated by the first heating means and the temperature of the concave corner heated by the second heating means are higher than the mold temperature other than the convex corner and the concave corner. Effect of the Invention

[0010] By using a manufacturing device equipped with a mold for thermosetting resin prepregs that has a cartridge heater that heats the areas corresponding to the corners formed by three or more faces of the fiber-reinforced resin molded product, it is possible to reduce costs and produce reinforced resin molded products with a high yield. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating press molding using a die. [Diagram 2] FIG. 2 is a perspective view of a fiber-reinforced resin molded product 4 molded by press molding. [Diagram 3] FIG. 3 is an oblique view (a: upper mold, b: lower mold), a plan view (c: upper mold, d: lower mold), and a cross-sectional view (e: surface D of the upper mold, f: surface E of the lower mold) of the mold of Example 1. [Figure 4] FIG. 4 is a perspective view (a: upper mold, b: lower mold), a plan view (c: upper mold, d: lower mold), and a cross-sectional view (e: surface F of the upper mold, f: surface G of the lower mold) of the mold of Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described in detail with reference to the drawings of the embodiments. Note that the present invention is not limited to the embodiments, and appropriate design modifications and the like are possible within the scope known to those skilled in the art.

[0013] In this specification, a fiber-reinforced plastic molded product refers to a molded product obtained by heating and cooling a prepreg in which fiber bundles, such as fiber bundles of carbon fiber, glass fiber, or the like, are impregnated with a thermoplastic resin or a thermosetting resin and dried to harden the prepreg, and a thermoplastic fiber-reinforced plastic molded product refers to the above-mentioned fiber-reinforced plastic molded products in which the resin is made of a thermoplastic resin. In the present invention, the thermoplastic fiber reinforced resin molded product is made of a thermoplastic resin or a resin composition containing one of the thermoplastic resins. Examples of thermoplastic resins include polypropylene, polyethylene, polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, Teflon (registered trademark), acrylic, polyamide, polyacetal, polycarbonate, polyphenylene sulfide (PPS), polyether (polyetheretherketone, polyetherketone, polyethersulfone, etc.), polyester, and combinations thereof. These may be used alone or in combination. In this embodiment, a prepreg containing a thermoplastic resin is used for explanation. However, the manufacturing method and manufacturing apparatus described in this specification are applicable not only to the molding of thermoplastic resin prepregs, but also to prepregs made of thermosetting resins.

[0014] FIG. 1 is a schematic cross-sectional view for explaining press molding using a mold. 1 is an upper mold having a recess. 2 is a lower mold having a protrusion. 3 is a prepreg. 4 is a fiber-reinforced resin molded product. As shown in FIG. 1, in press molding using a mold, a prepreg 3 is placed between an upper mold 1 and a lower mold 2, the prepreg 3 is sandwiched between the upper mold 1 and the lower mold 2, and a load is applied between the upper mold 1 and the lower mold 2 to deform the prepreg 3 and obtain a fiber-reinforced resin molded product 4. In FIG. 1, the part surrounded by a line and marked A is a corner formed by the bottom and side of the fiber-resin reinforced molded product 4. The part surrounded by a line and marked B is a convex corner in the lower mold 2 corresponding to the corner formed by the bottom and side of the fiber-resin reinforced molded product 4. The part surrounded by a line and marked C is a concave corner in the upper mold 1 corresponding to the corner formed by the bottom and side of the fiber-resin reinforced molded product 4.

[0015] FIG. 2 is a perspective view of a fiber-reinforced plastic molded product 4 formed by press molding, and the part surrounded by a line and marked A is a corner formed by two adjacent flat surfaces on the bottom and side. 3 and 4, the area surrounded by a line and marked with B is a convex corner corresponding to the corner formed by the bottom surface of the fiber-reinforced plastic molded product 4 and two adjacent flat surfaces. The area surrounded by a line and marked with C is a concave corner corresponding to the corner formed by the bottom surface of the fiber-reinforced plastic molded product 4 and two adjacent flat surfaces. EXAMPLES

[0016] Example 1 (composition) The manufacturing device for the fiber-reinforced plastic molded product 4 of the present invention includes a lower mold 2 having a convex portion and an upper mold 1 having a concave portion. As shown in FIG. 3B, the lower mold 2 has a cartridge heater 5 as a heating means for heating the convex corner B corresponding to the corner formed by the bottom surface of the fiber-reinforced plastic molded product 4 and two adjacent flat surfaces in the convex portion. For example, the cartridge heater 5 is provided at a right angle below the top surface along the intersection line between the convex top surface and the convex side surface of the convex corner B. Here, the cartridge heater 5 is composed of 521 arranged parallel to the convex top surface and 522 arranged perpendicular to the convex top surface. The heating means may be composed of only the cartridge heater 521 arranged parallel to the convex top surface, or may be composed of only the cartridge heater 522 arranged perpendicular to the convex top surface, or may be composed of both the cartridge heaters 521 and 522. In the present invention, the first heating means for heating the convex corner is cartridge heater 521 or cartridge heater 522, and may include both cartridge heater 521 and cartridge heater 522 as necessary. As shown in FIG. 3A, the upper mold 1 has a cartridge heater 5 as a heating means for heating a recessed corner C corresponding to a corner formed by two planes adjacent to the bottom surface of the fiber-resin reinforced molded product 4 in the recess. For example, the cartridge heater 5 is provided at a right angle below the bottom surface along the intersection line between the bottom surface of the recess and the side surface of the recess. Here, the cartridge heater 5 is composed of 511 arranged parallel to the top surface of the recess and 512 arranged perpendicular to the top surface of the recess. The heating means may be composed of only the cartridge heater 511 arranged parallel to the top surface of the recess, or may be composed of only the cartridge heater 512 arranged perpendicular to the top surface of the recess, or may be composed of both the cartridge heaters 511 and 512. In the present invention, the second heating means for heating the recessed corner portion is cartridge heater 511 or cartridge heater 512, and may include both cartridge heater 511 and cartridge heater 512 as necessary. Although not shown in the figure, the upper mold 1 and the lower mold 2 can be equipped with a heater that can raise the temperature of the entire mold to a predetermined temperature so that fiber-reinforced resin prepreg can be molded, or heaters can be placed around the mold to raise the temperature of the entire mold.

[0017] (Mold) There is no particular limitation on the upper mold 1 and the lower mold 2 as long as they are molds that can withstand the molding temperature of the resin. For example, molds that can withstand a temperature of 160° C. can be used.

[0018] (Cartridge heater) The cartridge heater 5 is not particularly limited as long as it can heat the recessed corner C of the upper mold 1 and the convex corner B of the lower mold 2 to the molding temperature of the thermoplastic resin prepreg 3. If the cartridge heater 5 is used to heat the recessed corner C of the upper mold 1 and the convex corner B of the lower mold 2 to the molding temperature of the thermoplastic resin prepreg 3 (for example, 220°C) by applying a load between the upper mold 1 and the lower mold 2 while the prepreg 3 is being deformed, the prepreg 3 will soften and be drawn into the upper mold 1 and the lower mold 2 while forming a corner A. This makes it difficult for fibers to be cut without being caught by the convex corner B and the recessed corner C of the mold corresponding to the corner A of the fiber reinforced resin molded product of the mold. In addition, the whitening phenomenon generally occurs most frequently at corners formed by three or more faces of a fiber reinforced resin molded product, but such whitening phenomenon can also be prevented. Furthermore, if the whitening phenomenon occurs in other parts, the cartridge heater 5 may be added to the corresponding parts of the mold to heat them. The number of cartridge heaters 5 is not particularly limited as long as it is capable of heating the concave corner of upper mold 1 and the convex corner B of lower mold 2 to the molding temperature of thermoplastic resin prepreg 3 . In addition, in this embodiment, a rod-shaped cartridge heater is used as the heating means, but this is not limited as long as it can heat the corners.

[0019] During press molding, the difference in temperature between the center of gravity of the top surface of the convex portion, which corresponds to the center of gravity of the bottom surface of the fiber reinforced plastic molded product, and the temperature of the convex corner B is 30° C. or more. If the temperature is less than 30° C., the temperature is too low and there is a risk that the prepreg will not deform, and there is also a possibility that whitening will occur on the surface of the fiber reinforced plastic molded product, or that the fibers will get caught and cause fiber cutting at the corners of the fiber reinforced plastic molded product. Here, for example, when the plane is a quadrangle, the center of gravity is the midpoint of a line segment connecting the midpoints of two line segments made from pairs of two of the four vertices.

[0020] (Method of manufacturing fiber-reinforced plastic molded products) The manufacturing method of the present invention for a box-shaped fiber-reinforced plastic molded product 4 composed of a bottom surface and side surfaces consisting of three or more flat surfaces includes a step of heating a convex corner corresponding to a corner formed by the bottom surface of the fiber-reinforced plastic molded product and two adjacent flat surfaces by a first heating means, a step of heating a concave corner corresponding to a corner formed by the bottom surface of the fiber-reinforced plastic molded product and two adjacent flat surfaces by a second heating means, a step of placing a fiber-reinforced plastic prepreg in a lower mold, a step of sandwiching and pressing the fiber-reinforced plastic prepreg between an upper mold and a lower mold, and a step of separating the upper mold and the lower mold and removing the fiber-reinforced plastic molded product.

[0021] First, the upper mold 1 and the lower mold 2 are heated to a first temperature. The first temperature is not particularly limited as long as it is a temperature that a typical mold material can withstand (for example, a temperature at which a thermosetting resin prepreg can be molded), but is, for example, 140 to 180° C. The upper mold 1 and the lower mold 2 may be heated to the first temperature by a heater provided in the mold that can raise the entire mold to a predetermined temperature, or a heater may be disposed around the mold to heat it to the first temperature.

[0022] Next, the convex corner B of the lower mold 2 having a convex portion, which corresponds to the corner A formed by the bottom surface of the fiber-reinforced resin molded product 4 having a box shape and two adjacent flat surfaces, is heated to a second temperature by a cartridge heater 5. The second temperature is not particularly limited as long as it is higher than the first temperature, but is, for example, a temperature at which a thermoplastic resin prepreg can be molded, for example, 200 to 250°C. In addition, the convex corner B of the lower mold 2 and the concave corner C may be heated to the second temperature by a cartridge heater 5. By heating both the convex corner B and the concave corner C, the accuracy of the corner A can be further improved and the product yield can be increased. Note that there is no boundary between the first temperature and the second temperature, and the temperature changes gradually. Therefore, the temperatures of the convex corner B and the concave corner C are higher than the temperatures at other positions in the mold.

[0023] In this embodiment, the prepreg 3 is a thermoplastic fiber reinforced resin prepreg made of carbon fiber and polypropylene, but is not limited to this. In this embodiment, the prepreg manufactured by Mitsubishi Chemical (twill weave, 0.23 mm per sheet) was used, and multiple sheets were laminated so that the thickness of the completed thermoplastic fiber reinforced resin molded product was 1.6 mm. The technology disclosed in this specification can be used for a thermoplastic fiber reinforced resin molded product with a thickness of 0.2 to 5.0 mm, and the thickness of the finished product can be adjusted by the number of prepregs laminated. Furthermore, when laminating the prepregs, an adhesive and / or an adhesive resin sheet can be placed between the prepregs to increase the lamination strength of the prepregs (to make the prepregs less likely to peel off from each other). For example, an acrylic adhesive or an acrylic adhesive resin sheet can be used as the adhesive resin sheet, and it may be placed between all the prepregs to be laminated, or an adhesive resin sheet may be placed only at the necessary places between the prepregs.

[0024] The temperature required to mold the thermoplastic fiber reinforced resin prepreg used in this embodiment is 220°C. The second temperature is a temperature close to the temperature for molding the material, and is a temperature at which the resin of the prepreg 3 to be placed later can be sufficiently softened and shaped between the concave corner of the upper mold 1 and the convex corner of the lower mold 2. The molding temperature and the holding temperature are, for example, in the range from the thermoplastic resin melting point of the prepreg 3 to the thermoplastic resin melting point + 100°C, and in one example, from the thermoplastic resin melting point to the thermoplastic resin melting point + 60°C. If the molding temperature or holding temperature is too high, it may cause burning or poor gloss of the thermoplastic fiber reinforced resin molded product, and if the holding temperature is too low, the fluidity of the resin may be poor, causing distortion or whitening.

[0025] A fiber reinforced resin prepreg 3 is placed in the lower mold 2. It is preferable that the fiber reinforced resin prepreg 3 is preliminarily heated to a molding temperature of the thermoplastic resin prepreg.

[0026] A fiber reinforced resin prepreg 3 is sandwiched between an upper mold 1 and a lower mold 2 and pressed. After placing the prepreg 3, the upper die 1 and / or the lower die 2 are moved while maintaining the temperatures of the upper die 1, the lower die 2 and the convex corners or the convex corners and the concave corners to sandwich the fiber reinforced resin prepreg 3. In the case of lowering the upper die 1, the upper die 1 comes into contact with the prepreg 3 and then further descends until it reaches the bottom dead center. When the upper die 1 reaches the bottom dead center, the load reaches its maximum value.

[0027] After the upper die 1 reaches the bottom dead point, the load and temperature are held in that state for a predetermined time. The holding time at the bottom dead point is adjusted mainly depending on the thickness of the prepreg 3. Usually, the holding time is between 0.3 and 2 minutes per 1 mm of thickness of the prepreg 3. In this embodiment, the holding time is about 2 minutes to manufacture a thermoplastic fiber reinforced resin molded product of 1.6 mm. If the holding time is short, the heat is not transferred to the entire material, so it is difficult to obtain the desired shape. In particular, the corners are not sufficiently molded. Also, if the holding time is too long, the fluidity and color of the resin change.

[0028] The load applied to the upper die 1 at the bottom dead center is not particularly limited, but is preferably 800 to 1500 KN, and more preferably 900 to 1400 KN.

[0029] The upper mold 1 and the lower mold 2 are separated, and the fiber reinforced resin molded product 4 is taken out. After the upper die 1 is at the bottom dead center and the temperature and load are maintained, the temperatures of the upper die 1 and the lower die 2 are reduced. When the temperature has dropped to the point where the thermoplastic resin solidifies, the pressure on the upper die 1 is stopped and the upper die 1 is raised to its original position. The fiber-reinforced resin molded product 4 is then demolded from the upper die 1, and the press molding is completed.

[0030] When pressing is performed continuously, the temperature of the entire mold does not need to be returned to room temperature, and may be, for example, 60 to 90° C. If the temperature is relatively high, the reheating time can be shortened, and the required energy can be reduced.

[0031] In the manufacturing device for fiber-reinforced resin molded products 4 of the present invention, a mold that corresponds to the molding temperature of thermosetting resin prepreg for which standard parts exist is used, so costs are kept down, and the yield can be increased by heating the convex corners of the mold that correspond to the corners of the molded product that are significantly affected by the drop in prepreg temperature and hardening due to the drop in temperature when molding the thermoplastic resin prepreg heated to the molding temperature, to the molding temperature of the thermoplastic resin prepreg. Thermoplastic resin prepreg requires less time to mold than thermosetting resin prepreg, so the convex corners of the mold can be used for a long time without softening or deterioration.

[0032] Example 2 The manufacturing device for the fiber-reinforced plastic molded product 4 of the second embodiment is particularly effective when the molding depth is deep. The lower mold 2 of the second embodiment has a cartridge heater 5 as heating means for heating a convex corner portion corresponding to a corner portion formed by two adjacent flat surfaces of the bottom surface and side surface of the fiber-reinforced plastic molded product 4, as shown in FIG. 4b. For example, similar to the first embodiment, a cartridge heater 5 is provided under the top surface along the intersection line between the convex top surface and the convex side surface of the convex corner portion, and in addition, a cartridge heater 5 is provided in the middle and lower parts of the side surface in the height direction along a line parallel to the intersection line between the convex top surface and the convex side surface of the convex corner portion. The upper mold 1 has a cartridge heater 5 as heating means for heating a concave corner portion corresponding to a corner portion formed by two adjacent flat surfaces of the bottom surface and side surface of the fiber-reinforced plastic molded product 4, as shown in FIG. 4a. For example, similar to the first embodiment, a cartridge heater 5 is provided under the bottom surface along the intersection line between the concave bottom surface and the concave side surface of the concave corner portion, and in addition, a cartridge heater 5 is provided under the side surface along the intersection line between the concave bottom surface and the concave side surface of the concave corner portion. This makes it possible to heat not only the corner A but also the portion formed by the two flat surfaces of the side surface. In the second embodiment, multiple cartridge heaters 5 are provided parallel to the top surfaces of the convex portions or the bottom surfaces of the concave portions, but cartridge heaters 512 or 522 may be provided that are arranged perpendicular to the top surfaces of the convex portions or the bottom surfaces of the concave portions of the first embodiment. [Explanation of symbols]

[0033] 1: Upper mold 2: Lower mold 3: Prepreg 4: Fiber-reinforced plastic moldings 5: Cartridge heater A: Corner B: Convex corner C: Concave corner

Claims

1. A press manufacturing apparatus for manufacturing a box-shaped fiber-reinforced plastic molded product from a prepreg, the press manufacturing apparatus comprising a bottom surface and a side surface consisting of three or more flat surfaces, A lower die having a protrusion; an upper die having a recess; The convex portion has a first heating means for heating a convex corner portion corresponding to a corner portion formed by the bottom surface of the fiber-reinforced resin molded product and two adjacent flat surfaces, The recess has a second heating means for heating a recessed corner portion corresponding to a corner portion formed by the bottom surface of the fiber-reinforced resin molded product and two adjacent flat surfaces, At least one of the first heating means and the second heating means is a press manufacturing apparatus comprising a linear cartridge heater parallel to a bottom surface connected to the convex corner portion or a bottom surface connected to the concave corner portion, and a linear cartridge heater perpendicular to the bottom surface connected to the convex corner portion or a bottom surface connected to the concave corner portion.

2. A method for manufacturing a fiber-reinforced plastic molded product by the press manufacturing apparatus according to claim 1, A step of heating a convex corner portion corresponding to a corner portion formed by the bottom surface of the fiber reinforced resin molded product and two adjacent flat surfaces by the first heating means; A step of heating a recessed corner portion corresponding to a corner portion formed by the bottom surface of the fiber reinforced resin molded product and two adjacent flat surfaces by the second heating means; placing a fiber reinforced resin prepreg in the lower mold; A process of sandwiching and pressing a prepreg, which is a material of the fiber reinforced resin molded product, between the upper mold and the lower mold; and separating the upper die and the lower die to remove the fiber reinforced resin molded product.

3. The manufacturing method according to claim 2 , wherein a temperature of the salient corner portion heated by the first heating means and a temperature of the reentrant corner portion heated by the second heating means are higher than a mold temperature other than the salient corner portion and the reentrant corner portion.

4. The method according to claim 2 , wherein the fiber-reinforced resin molded product contains a thermoplastic resin.

5. The method according to claim 2 , wherein during press molding, a temperature of the convex corner portion is higher by 30° C. or more than a temperature of a center of gravity of a top surface of the convex portion corresponding to a center of gravity of the bottom surface.

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