Method for producing a resin composite panel and method for producing a three-dimensional object

Abstract

Method for producing a resin composite panel (10), the method comprising: Producing a plurality of resin sheet groups (14), wherein each of the plurality of resin sheet groups (14) is produced by stacking at least one first fiber-reinforced thermoplastic resin sheet (12) having a first thickness on top of a second fiber-reinforced thermoplastic resin sheet (12) having a second thickness that differs from the first thickness, wherein each of the first and second fiber-reinforced thermoplastic resin sheets (12) contains fibers (F) arranged in one direction; Laying the several Harz railway groups (14) side by side in one plane; and Producing the resin composite plate (10) with a desired thickness by heating the majority of resin sheet groups (14) under pressure and thus integrating the majority of resin sheet groups (14) into a resin composite plate (10), wherein at least one resin sheet group (14) among the majority of resin sheet groups (14) arranged in the plane requires strength and differs from another resin sheet group (14) that does not require strength among the majority of resin sheet groups (14) arranged in the plane in a fiber volume fraction of the stacked fiber-reinforced thermoplastic resin sheets (12) in order to increase the strength of the at least one resin sheet group (14) and to weaken the strength of the other resin sheet group (14).

Description

GENERAL STATE OF TECHNOLOGY - Field of invention:

[0001] The present invention relates to a manufacturing process for a resin composite panel and a method for producing a three-dimensional object. Description of the state of the art:

[0002] Japanese patent publication JP 2013-221 114 A discloses a technique for producing a resin sheet by stacking several pieces of carbon fiber composite resin materials, each having a uniform thickness. US 2017 / 0 057 666 A1 describes a manufacturing process for resin composite panels, in which resin sheets of the same thickness are stacked and heated under pressure. WO 2017 / 073 555 A1 shows a composite panel made of cellulose fiber-containing sheets, in which sheets of different thicknesses are used to avoid warping of the finished composite panel. DE 101 53 875 A1 describes an elongated component consisting of layered, essentially parallel sheets made of a fiber-reinforced plastic composite.

[0003] It is an object of the invention to propose methods for manufacturing a resin composite panel or a three-dimensional object. This object is achieved by a manufacturing method according to claim 1 and a manufacturing method according to claim 9. BRIEF SUMMARY OF THE INVENTION

[0004] By reducing the unit thickness of the carbon fiber composite resin materials, it is possible to fine-tune the thickness of the resin sheet. Therefore, it is possible to obtain a resin sheet with a desired thickness. However, this introduces a problem in that manufacturing costs increase because the number of carbon fiber composite resin sheets to be stacked increases, and consequently, so does the number of stacking processes.

[0005] On the other hand, thickening the unit thickness of the carbon fiber composite resin materials used makes it possible to reduce the number of pieces of carbon fiber composite resin required. However, this creates a further problem, as it becomes impossible to precisely control the thickness of the resin sheet.

[0006] The present invention was made to solve the aforementioned problems, and it is an object of the present invention to provide a manufacturing process for a resin composite panel which can reduce the number of fiber-reinforced thermoplastic resin sheets to be stacked and at the same time finely control the thickness of the resin composite panel.

[0007] A manufacturing process according to the invention comprises a manufacturing process for a resin sheet group in which several fiber-reinforced thermoplastic resin sheets are stacked together, thereby integrating the resin sheets into a resin sheet group, wherein each of the fiber-reinforced thermoplastic resin sheets contains fibers arranged in one direction, and wherein the manufacturing process comprises producing each resin sheet group with a desired thickness by stacking the several fiber-reinforced thermoplastic resin sheets having different thicknesses.

[0008] A manufacturing process according to the invention can comprise a manufacturing process of a resin web group by heating a resin web group under pressure, which has several fiber-reinforced thermoplastic resin webs stacked together, and thereby integrating the resin webs into a resin web group, wherein each of the fiber-reinforced thermoplastic resin webs contains fibers arranged in one direction, wherein at least one of the several stacked fiber-reinforced thermoplastic resin webs differs in fiber volume fraction from others of the stacked fiber-reinforced thermoplastic resin webs.

[0009] A manufacturing process according to the invention can comprise a manufacturing process for a resin sheet group by heating several fiber-reinforced thermoplastic resin sheets under pressure, which are laid on a plane, and thereby integrating the fiber-reinforced thermoplastic resin sheets into a composite panel, wherein each of the fiber-reinforced thermoplastic resin sheets contains fibers arranged in one direction, and wherein a connecting surface between the adjacent fiber-reinforced thermoplastic resin sheets is in the form of a curved surface, several planes or a combination of a curved surface and a plane.

[0010] The manufacturing process allows for a reduction in the number of fiber-reinforced thermoplastic resin sheets required compared to stacking multiple sheets of the same thickness. Consequently, the number of stacking processes is reduced, thus lowering production costs. Furthermore, stacking multiple sheets of varying thicknesses allows for precise control of the thickness, facilitating the production of resin sheets with a desired thickness.

[0011] According to the manufacturing process, some of the multiple stacked, fiber-reinforced thermoplastic resin sheets requiring additional strength can be made stronger, while the others requiring relatively little strength can be made weaker. As a result, manufacturing costs can be reduced.

[0012] According to the manufacturing process, compared to the case where the connection surface is in the form of a plane, it is possible to increase the area of ​​the connection surface, and therefore it is possible to prevent the resin composite panel from breaking at the connection surface between the fiber-reinforced, thermoplastic resin sheets.

[0013] The above and other problems, features and advantages of the present invention will become apparent from the following description when taken together with the accompanying drawings, which show preferred embodiments of the present invention by illustrative examples. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1A is a schematic view to explain a manufacturing process for a resin sheet group and shows a state in which several fiber-reinforced thermoplastic resin sheets are stacked; Fig. Figure 1B is a schematic view to explain the manufacturing process of the resin sheet group and shows a resin sheet group produced by heating under pressure a resin sheet group comprising several fiber-reinforced thermoplastic resin sheets stacked together; Fig. Figure 2 is a schematic view showing an example where fiber directions in the resin web group intersect during the manufacturing process of the resin web group; Fig. Figure 3 is a schematic view showing an example where fiber directions of two adjacent stacked, fiber-reinforced, thermoplastic resin sheets intersect during the manufacturing process of the resin sheet group; Fig. Figure 4 is a schematic view to explain forming presses by means of a press device; Fig. Figure 5A is a schematic view to explain a manufacturing process according to the invention for a resin composite panel and shows a state in which several resin web groups are laid on one plane; Fig. Figure 5B is a schematic view to explain the manufacturing process of the resin composite panel according to the invention and shows a resin composite panel which is produced by heating the several resin web groups laid on one plane under pressure; Fig. 6A is a schematic view showing a state in which several resin web groups of different thicknesses are laid on one plane in the inventive manufacturing process of the resin composite panel; Fig. Figure 6B is a schematic view showing a resin composite panel produced by heating under pressure several groups of resin sheets of different thicknesses which are laid on the plane in the inventive manufacturing process of the resin composite panel; Fig. Figure 7 is a schematic view showing an example where the number of fiber-reinforced thermoplastic resin sheets in the resin sheet groups differs in the manufacturing process of the resin composite panel according to the invention; Fig. Figure 8 is a schematic view to explain a further embodiment of the manufacturing process according to the invention for a resin composite panel and shows an example in which connection surfaces between resin sheet groups are in the form of curved lines; Fig. Figure 9 is a schematic view to explain a further embodiment of the manufacturing process for the resin composite panel according to the invention and shows an example in which connection surfaces between resin sheet groups are in the form of several straight lines; and Fig. Figure 10 is a schematic view to explain the further embodiment of the manufacturing process of the resin composite panel according to the invention and shows an example in which each of the resin web groups has a regular hexagon. DESCRIPTION OF PREFERRED EXECUTION FORMS

[0014] Preferred embodiments of a manufacturing process according to the invention for a resin composite panel are described in detail below with reference to the accompanying drawings.

[0015] In a manufacturing process, a resin sheet group 14 is produced by stacking several fiber-reinforced thermoplastic resin sheets 12 and then heating the resin sheet group 14, in which several fiber-reinforced thermoplastic resin sheets 12 are stacked together, under pressure in order to integrate the several resin sheets 12 of the resin sheet group 14.

[0016] Fig. 1A and Fig. 1B are schematic views to explain the manufacturing process of the Harz Railway Group 14. Fig. Figure 1A shows a state in which the multiple fiber-reinforced thermoplastic resin sheets 12 are stacked. Fig. Figure 1B shows a resin sheet group 14, which is produced by heating the resin sheet group 14, in which the several fiber-reinforced thermoplastic resin sheets 12 are stacked together, under pressure.

[0017] Each of the fiber-reinforced thermoplastic resin sheets 12 is a sheet made of thermoplastic resin containing fibers F (for example, fibers such as carbon fibers, glass fibers, or the like). The fibers F of the fiber-reinforced thermoplastic resin sheet 12 are arranged in one direction (see Fig. 2 and Fig. 3).

[0018] The resin sheet groups 14 are heated under pressure by applying an upper press die and a lower press die (not shown). Furthermore, the produced resin composite sheet 10 is pressed into a shaped object by a press PA with press dies (upper press die D1 and lower press die D2) (see Fig. 4) That is, the upper press die D1 and the lower press die D2 sandwich-like enclose or clamp the resin composite sheet 10 between them and press the resin composite sheet 10 to form a shaped object of three-dimensional form. Furthermore, the production of the resin composite sheet 10 by heating the resin web groups 14 under pressure and the production of the shaped object by compression molding can be carried out by a single press device PA. For example, the resin web groups 14 can be heated under pressure and compression molded simultaneously.

[0019] In the manufacturing process, the resin composite sheet 10, which has a desired thickness, is produced under pressure by heating the resin sheet groups 14, which contain several fiber-reinforced, thermoplastic resin sheets 12 of different thicknesses stacked together.

[0020] Fig. 1A and Fig. Figure 1B shows an example in which three fiber-reinforced thermoplastic resin sheets 12 are stacked to facilitate understanding of the description. Fig. 1A and Fig. In 1B, the fiber-reinforced thermoplastic resin sheets 12 of the top layer and the bottom layer have the same thickness (for example, 0.05 mm), while the fiber-reinforced thermoplastic resin sheet 12 of the intermediate layer (middle layer) has the greatest thickness (for example, 0.5 mm). Alternatively, the fiber-reinforced thermoplastic resin sheets 12 of the top layer and the bottom layer can have different thicknesses.

[0021] Since the resin sheet group 14 is produced by stacking several fiber-reinforced thermoplastic resin sheets 12 of varying thicknesses, the number of fiber-reinforced thermoplastic resin sheets 12 required can be reduced compared to stacking several fiber-reinforced thermoplastic resin sheets 12 of the same thickness. Consequently, the number of stacking processes for the fiber-reinforced thermoplastic resin sheets 12 is reduced, and therefore the manufacturing costs can be lowered. Furthermore, the thickness can be precisely controlled as a result of stacking the several fiber-reinforced thermoplastic resin sheets 12 of varying thicknesses, making it easy to produce the resin sheet group 14 with a desired thickness.

[0022] According to the prior art method, for example, in a case where a resin composite sheet 10 with a thickness of 0.6 mm is produced by using several fiber-reinforced thermoplastic resin sheets 12, each with a thickness of 0.1 mm, it is necessary to stack six sheets of the fiber-reinforced thermoplastic resin sheets 12. Consequently, when adjusting the thickness of the resin composite sheet 10, the adjustment can only be carried out in increments of 0.1 mm. On the other hand, to prioritize the fine adjustment of the fiber-reinforced thermoplastic resin sheets 12 in a case where the resin composite sheet 10 with a thickness of 0.6 mm is produced by using fiber-reinforced thermoplastic resin sheets 12, each with a thickness of 0.05 mm, the fine adjustment of the thickness of the resin composite sheet 10 can be carried out in increments of 0.05 mm.However, it is necessary to stack no fewer than twelve sheets of the fiber-reinforced thermoplastic resin sheets 12.

[0023] Furthermore, in the manufacturing process, the resin sheet group 14 of a desired thickness can be produced by stacking several fiber-reinforced, thermoplastic resin sheets 12 of different thicknesses, such that the fiber directions (the directions of the fibers F) of the resin sheet group 14 intersect (preferably perpendicularly), as shown in Fig. 2 shown. As a result, it is possible to reduce the directional dependence of the Harz railway group 14, and therefore the Harz railway group 14 shows an improved strength.

[0024] Furthermore, the resin sheet group 14 of a desired thickness can be produced by stacking several fiber-reinforced thermoplastic resin sheets 12 of different thicknesses such that the fiber directions F of two adjacently stacked fiber-reinforced thermoplastic resin sheets 12 intersect, as shown in Fig. Figure 3 shows that, as a result, it is possible to eliminate the directional dependency of the Harz Railway Group 14, and consequently the strength of the Harz Railway Group 14 is further improved.

[0025] As the fiber volume fraction (Vf) increases, the fiber-reinforced thermoplastic resin sheets 12 become stronger, but also more expensive. To counteract this cost increase, at least one of the stacked fiber-reinforced thermoplastic resin sheets 12 of the resin sheet group 14 can differ in fiber volume fraction from the other fiber-reinforced thermoplastic resin sheets 12. For example, the fiber volume fraction of the fiber-reinforced thermoplastic resin sheet 12 of the intermediate layer can be made larger than the fiber volume fraction of the fiber-reinforced thermoplastic resin sheets 12 of the top and bottom layers.With this structure, some of the multiple stacked, fiber-reinforced, thermoplastic resin sheets 12 that require strength can be made stronger, while other fiber-reinforced, thermoplastic resin sheets 12 that require relatively no strength can be made weaker.

[0026] As a result, manufacturing costs can be reduced.

[0027] Fig. 5A and Fig. Figure 5B shows schematic views to explain a manufacturing process according to the invention of the resin composite panel 10 according to a first embodiment. Fig. Figure 5A shows a state in which several Harz railway groups 14 are laid on one level. Fig. Figure 5B shows a resin composite plate 10, which is produced by heating several resin sheet groups 14 laid on the plane under pressure. Although the several resin sheet groups 14 are in predetermined spaces in Fig. The components arranged in 5A are indeed arranged on the same plane without any gaps. Furthermore, the same reference numbers are given to the components mentioned previously, and a description is only given for components that differ from those mentioned previously.

[0028] Furthermore, reference number 30 designates connecting parts between the resin sheet groups 14 (the fiber-reinforced, thermoplastic resin sheets 12) that are laid on the plane. Reference number 30a designates connecting surfaces (intersecting surfaces of the connecting parts).

[0029] In the manufacturing process according to the invention of the resin composite panel 10 of the first embodiment, a resin composite panel 10 is produced by laying or arranging the several resin web groups 14 tightly without any gap between them (see Fig. 5A) and then, under pressure, the several resin sheet groups 14 laid close together on the plane are heated in order to integrate the resin sheet groups 14 into the resin composite plate (see Fig. 5B). As a result, it is possible to easily manufacture the resin composite sheet 10, which is suitable for the size and shape of a molded object to be formed by pressing.

[0030] As the thickness and fiber content (fiber F content) of the entire resin sheet group 14 increase, the strength of the resin sheet group 14 also increases, but the costs rise. To suppress such a cost increase, at least one of the several resin sheet groups 14 laid flat differs from the others in at least one aspect of its thickness and fiber F content. By partially changing the thickness or fiber F content of the resin sheet groups 14 as described above, it is possible to increase the strength of the resin sheet group 14 that requires strength and to reduce the strength of the resin sheet group 14 that does not require strength. As a result, the manufacturing costs can be reduced.

[0031] In this case, at least one of the thickness and fiber content F of the resin sheet groups 14 can be modified depending on a part of a molded object to be compression-molded from the resin composite sheet 10. Therefore, a part of the molded object requiring strength can be made stronger, while a part not requiring strength can be made weaker. Accordingly, the manufacturing costs can be reduced. Furthermore, it is possible to easily produce the resin composite sheet 10 suitable for a molded object to be obtained by compression molding.

[0032] Incidentally, Fig. 6A a schematic view showing a state in which several resin track groups 14 of different thicknesses are laid on one plane, and Fig. Figure 6B is a schematic view showing a resin composite plate 10 produced by heating under pressure several resin sheet groups 14 of varying thicknesses laid on the plane. Although the several resin sheet groups 14 are arranged at predetermined intervals in Fig. When arranged in 6A, they are actually placed or arranged on the plate without any gap.

[0033] Furthermore, in the manufacturing process of the first embodiment according to the invention, at least one of the several resin sheet groups 14 laid on a plane can differ from the other resin sheet groups 14 with respect to the number of stacked, fiber-reinforced, thermoplastic resin sheets 12, the thickness, the fiber content (F), or the fiber volume fraction. By partially modifying the thickness, the fiber content (F), the fiber volume fraction, or the number of fiber-reinforced thermoplastic resin sheets 12 that form the resin sheet group 14, it is possible to increase the strength of some of the resin sheet groups 14 that require strength and to reduce the strength of the other resin sheet groups 14 that do not require strength. Accordingly, the manufacturing costs can be reduced.

[0034] In this case, the thickness, the fiber content F, the fiber volume fraction or the number of fiber-reinforced thermoplastic resin sheets 12 of the resin sheet group 14 can be changed depending on a part of a molded object that is to be compression-molded from the resin composite sheet 10.

[0035] Furthermore, Fig. Figure 7 shows a schematic view illustrating an example where the number of fiber-reinforced thermoplastic resin sheets 12 of the resin sheet groups 14 differs from one another. As in Fig. As shown in Figure 7, the number of fiber-reinforced thermoplastic resin sheets 12 of one of the resin sheet groups 14 is three, while the number of fiber-reinforced thermoplastic resin sheets 12 of the other resin sheet group 14 is five.

[0036] To cause the thickness, fiber content F or fiber volume fraction of the fiber-reinforced thermoplastic resin sheets 12 of one resin sheet group 14 to differ from those of another resin sheet group 14 means that the thickness, fiber content F or fiber volume fraction of at least one of the several fiber-reinforced thermoplastic resin sheets 12 of one resin sheet group 14 differs from the thickness, fiber content F or fiber volume fraction of each of the several fiber-reinforced thermoplastic resin sheets 12 of the other resin sheet group 14.For example, a case is included in which the three fiber-reinforced thermoplastic resin sheets 12 forming one resin sheet group 14 have respective thicknesses of 0.05 mm, 0.06 mm and 0.5 mm, while the three fiber-reinforced thermoplastic resin sheets 12 forming another resin sheet group 14 have respective thicknesses of 0.05 mm (two sheets) and 0.5 mm (one sheet).

[0037] As described in the first embodiment, the rectangular resin sheet groups 14 (each containing the fiber-reinforced, thermoplastic resin sheets 12) are laid on the plane. In this structure, the connecting surfaces 30a between the resin sheet groups 14 each have the form of a plane (a flat or straight surface), and the multiple connecting surfaces 30a adjoin each other and are arranged linearly (see Fig. 5A and Fig. 5B). Therefore, the resin composite plate 10 breaks easily at the connecting parts 30 between the resin strip groups 14.

[0038] To address this, in a second embodiment the connecting surfaces 30a between adjacent resin sheet groups 14 have the form of a curved surface, several planes or a combination of a curved surface and planes.

[0039] Fig. Figure 8 shows an example where connecting surfaces 30a between the Harz railway groups 14 each have the form of a curved line. Fig. Figure 9 shows another example where the connecting areas 30a between the Harz railway groups 14 are all in the form of several straight lines.

[0040] With this structure it is possible to increase the area of ​​the connection surface 30a compared to the case in which the connection surfaces 30a are in the form of a plane, and therefore it is possible to prevent the resin composite plate 10 from breaking at the connection parts 30 between the resin sheet groups 14.

[0041] Furthermore, the Harz railway groups 14 can have a polygonal shape. Fig. Figure 10 is a schematic view showing an example where the resin band groups 14 are each formed in a regular hexagonal shape. Although each of the connecting surfaces 30a between the resin band groups 14 is in the form of a plane, in the example shown in Fig. In the example shown, several connection surfaces 30a are arranged in different directions without being linearly adjacent to one another. Therefore, it is possible to prevent the resin composite panel 10 from breaking at the connection points 30 between the resin layer groups 14. By forming the resin layer groups 14 in the polygonal shape shown above, it is possible to prevent the resin composite panel 10 from breaking at the connection points 30 between the resin layer groups 14, which would otherwise be caused by loads applied in different directions. Furthermore, it is possible to reduce the amount of material and the weight while maintaining the strength.

[0042] In a case where at least one of the several fiber-reinforced thermoplastic resin sheets 12 forming a resin sheet group 14 is manufactured such that its fiber volume fraction differs from that of the other fiber-reinforced thermoplastic resin sheets 12, the several fiber-reinforced thermoplastic resin sheets 12 of the resin sheet group 14 can have the same thickness. Even in this case, some of the fiber-reinforced thermoplastic resin sheets 12 that require strength can be made stronger, while the others that require relatively little strength can be made weaker, and therefore the manufacturing costs can be reduced.

[0043] In a case where a piece of resin composite panel 10 is manufactured with several resin sheet groups 14 arranged on a plane, and where the connecting surfaces 30a between the adjacent resin sheet groups 14 are in the form of a curved surface, several planes, or a combination of curved surfaces and planes (as described in the second embodiment), the several fiber-reinforced thermoplastic resin sheets 12 forming the resin sheet groups 14 can have the same thickness. Furthermore, even in the case where the resin sheet groups 14 are each formed in a polygonal shape, the several fiber-reinforced thermoplastic resin sheets 12 forming the resin sheet groups 14 can have the same thickness.Even in these cases it is possible to increase the area of ​​the connection surfaces 30a, and therefore it is possible to prevent the resin composite plate 10 from breaking at the connection parts 30 between the resin sheet groups 14.

[0044] Furthermore, a resin composite panel 10 can be produced by laying several fiber-reinforced thermoplastic resin sheets 12 on a plane and then heating the multiple fiber-reinforced thermoplastic resin sheets 12 under pressure. In this case, connecting elements 30a between the adjacent fiber-reinforced thermoplastic resin sheets 12 can be in the form of a curved surface, several planes, or a combination of curved surfaces and planes. Furthermore, the fiber-reinforced thermoplastic resin sheets 12 can each be formed in a polygonal shape (for example, as a regular hexagon). Even in this case, it is possible to increase the area of ​​the connecting surfaces 30a, and therefore it is possible to prevent the resin composite panel 10 from breaking at the connecting elements 30 between the fiber-reinforced thermoplastic resin sheets 12.

[0045] In a fifth embodiment, a three-dimensional object can be formed by stacking several manufactured resin composite sheets 10 and then heating the several stacked resin composite sheets 10, wherein the sheets 10 are placed between press molds (upper press mold D1 and lower press mold D2) of the Fig. The PA components can be inserted or clamped in a sandwich-like manner as shown in the 4 press device. [Technical concepts derived from embodiments]

[0046] The following is a description concerning technical concepts that can be derived from the above explanations.

[0047] In a manufacturing process of a resin sheet group (14) by heating a resin sheet group (14) with several stacked, fiber-reinforced, thermoplastic resin sheets (12) under pressure and thereby integrating the resin sheet group into a resin composite sheet, wherein the fiber-reinforced, thermoplastic resin sheets have each fiber (F) arranged in one direction, the resin sheet group (14) which has a desired thickness is produced by stacking the several fiber-reinforced, thermoplastic resin sheets (12) which have different thicknesses.

[0048] With this configuration, the number of fiber-reinforced thermoplastic resin sheets (12) required can be reduced compared to a case where a resin sheet group (14) is produced by stacking several fiber-reinforced thermoplastic resin sheets (12) of the same thickness. Accordingly, the number of stacking processes for the fiber-reinforced thermoplastic resin sheets (12) is reduced, and therefore it is possible to lower the manufacturing costs. Furthermore, the thickness of the resin sheet group (10) resulting from the stacking of several fiber-reinforced thermoplastic resin sheets (12) of different thicknesses can be finely controlled, and therefore it is possible to easily produce the resin sheet group (14) with a desired thickness.

[0049] The resin sheet group (14) with a desired thickness can be produced by stacking several fiber-reinforced thermoplastic resin sheets (12) of different thicknesses such that the fiber directions of the fiber-reinforced thermoplastic resin sheets intersect. As a result, it is possible to reduce the directional dependence of the thickness of the resin sheet group (14), and therefore the strength of the resin sheet group (14) is improved.

[0050] The resin sheet group (14) with a desired thickness can be produced by stacking several fiber-reinforced thermoplastic resin sheets (12) of different thicknesses such that the fiber directions of two adjacent stacked fiber-reinforced thermoplastic resin sheets (12) intersect. As a result, it is possible to eliminate the directional dependence of the thickness of the resin sheet group (14), and therefore the strength of the resin sheet group (14) is further improved.

[0051] At least one of the multiple fiber-reinforced thermoplastic resin sheets (12) can differ in fiber volume fraction from the others of the stacked fiber-reinforced thermoplastic resin sheets (12). With this configuration, some of the multiple stacked fiber-reinforced thermoplastic resin sheets (12) that require strength can be made stronger, while the other fiber-reinforced thermoplastic resin sheets (12) that require relatively little strength can be made weaker.

[0052] As a result, manufacturing costs can be reduced.

[0053] The resin composite sheet (10) can be produced by heating several resin sheet groups (14) laid on a plane under pressure and integrating the resin sheet groups into a resin composite sheet, wherein in each of the resin sheet groups the several fiber-reinforced, thermoplastic resin sheets (12) are stacked together, and wherein the fiber-reinforced, thermoplastic resin sheets have different thicknesses. As a result, it is possible to easily produce a resin composite sheet (10) suitable for the size and shape of a molded object obtained by compression molding.

[0054] At least one of the several resin sheet groups (14) laid on the plane differs from other resin sheet groups (14) in at least one aspect of its thickness and fiber content (F). By partially changing the thickness or fiber content (F) of the resin sheet groups (14) as described above, it is possible to increase the strength of a resin sheet group (14) that requires strength and to reduce the strength of another resin sheet group (14) that does not require strength. Accordingly, the manufacturing costs can be reduced.

[0055] At least one of the thickness and fiber content (F) of the resin sheet groups (14) can be varied depending on the part of an object to be formed from the resin composite sheet (10). Therefore, in a molded object to be formed by pressing, a part requiring strength can be made stronger, while another part not requiring strength can be made weaker. Accordingly, the manufacturing costs can be reduced. Furthermore, it is possible to easily produce the resin composite sheet (10) suitable for a molded object to be formed by pressing.

[0056] At least one of the multiple resin sheet groups (14) laid on the plane differs from the other resin sheet groups (14) in the number of stacked, fiber-reinforced, thermoplastic resin sheets (12), the thickness, the fiber content (F), or the fiber volume fraction. Therefore, by partially changing the number of fiber-reinforced, thermoplastic resin sheets (12) forming the resin sheet groups (14), their thickness, fiber content (F), or fiber volume fraction, it is possible to increase the strength of a resin sheet group (14) requiring strength and to weaken the strength of another resin sheet group (14) that does not require strength. Accordingly, the manufacturing costs can be reduced.

[0057] The number of fiber-reinforced thermoplastic resin sheets (12) of the resin sheet groups (14), their thickness, fiber content (F), or fiber volume fraction can be varied depending on the specific part of a molded object to be formed from the resin composite sheet (10). Therefore, a part of the molded object requiring strength can be made stronger, while a part not requiring strength can be made weaker. Accordingly, manufacturing costs can be reduced. Furthermore, it is possible to easily produce the resin composite sheet (10) suitable for molded objects formed by pressing.

[0058] A connecting surface (30a) between the adjacent resin sheet groups (14) can be in the form of a curved surface, several planes, or a combination of a curved surface and a plane. With this structure, it is possible to increase the area of ​​the connecting surface (30a) compared to a case where the connecting surface (30a) is in the form of a plane, and therefore it is possible to prevent the resin composite panel (10) from breaking at the connecting part (30) between the resin sheet groups (14).

[0059] The resin sheet groups (14) can each have a polygonal shape. This structure makes it possible to prevent the resin composite panel (10) from breaking at the connection (30) between the resin sheet groups (14), which is subjected to loads in different directions. Furthermore, it is possible to reduce the amount of material and the weight while maintaining the strength.

[0060] Furthermore, a three-dimensional shaped object can be produced by heating one or more manufactured resin composite plates (10) under pressure, wherein the one or more resin composite plates (10) are arranged sandwich-like or clamped between the press molds.

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