Intermediate material for fiber-reinforced materials and method for manufacturing the same

Abstract

This invention provides an intermediate material for fiber-reinforced materials that allows for free design expression while maintaining strength and rigidity, as well as a method for manufacturing the same. [Solution] An intermediate base material 2 is formed by sewing a reinforcing fiber bundle 4 onto a sheet-like base material 3, oriented in the direction of the principal stress, with sewing thread 5. Stitches are continuously applied along the longitudinal direction of the reinforcing fiber bundle 4 on the surface of the base material 3, and the sewing thread 5 has long stitches 6 with a relatively long stitch length L and short stitches 7 with a relatively short stitch length L. Switching points 16 between the long stitches 6 and short stitches 7 are provided along the orientation path of the reinforcing fiber bundle 4, and long stitch assemblies 8 and short stitch assemblies 9 are formed spanning multiple adjacent rows of reinforcing fiber bundles 4. The short stitch assemblies 9 have short stitches 7 that are sewn in a direction intersecting the longitudinal direction of the reinforcing fiber bundle 4, and a pattern or design is represented by multiple switching points 16 lined up at the boundary between adjacent long stitch assemblies 8 and short stitch assemblies 9.

Description

Technical Field

[0001] The present invention relates to an intermediate substrate of a fiber reinforced material and a method for manufacturing the same.

Background Art

[0002] Conventionally, a fiber reinforced material, which is a composite material in which a resin and reinforcing fibers are combined, is known. As one method for forming a preform (intermediate substrate) of a fiber reinforced material, the TFP (Tailored Fiber Placement) method is known. According to the TFP method, reinforcing fibers can be freely arranged on a substrate according to requirements, and an intermediate substrate having required strength in a required direction can be formed. For example, Patent Document 1 discloses a method for manufacturing an intermediate substrate in which reinforcing fibers are oriented in the principal stress direction. In this manufacturing method, reinforcing fibers are arranged in the direction in which stress acts and are sewn with embroidery thread, and improvements in the strength and rigidity of the fiber reinforced material are attempted.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in recent years, the use of fiber reinforced materials by the TFP method has been expanding, and along with this, there has been a tendency for designability to be required. However, although the strength and rigidity of fiber reinforced materials are improved by orienting the reinforcing fibers in the intermediate substrate in the principal stress direction, the design often depends on the arrangement of the reinforcing fibers in the intermediate substrate and the shape of the product. Therefore, in addition to the degree of freedom in the orientation of the reinforcing fibers, an intermediate substrate that can freely incorporate designs such as letters, pictures, and gradations has been demanded.

[0005] This invention was conceived in view of the above points, and the problem that this invention aims to solve is to provide an intermediate material for fiber-reinforced materials that can freely express designs while maintaining strength, rigidity, and the like, and a method for manufacturing the same. [Means for solving the problem]

[0006] One feature of an intermediate substrate for fiber-reinforced materials that solves the above problems is an intermediate substrate in which reinforcing fiber bundles are sewn to a sheet-like substrate, oriented along the principal stress direction corresponding to the required mechanical properties of the fiber-reinforced material, wherein the substrate has stitches that are continuously applied along the longitudinal direction of the reinforcing fiber bundles along at least one surface of the substrate, and the stitches include long stitches with a relatively long stitch length, which is the distance along the longitudinal direction of the reinforcing fiber bundles, and short stitches with a relatively short stitch length, and a switching point between the long stitches and the short stitches provided on the orientation path of the reinforcing fiber bundles, and a plurality of stitch assemblies formed across a plurality of adjacent rows of the reinforcing fiber bundles, which include a long stitch assembly where the long stitches gather and a short stitch assembly where the short stitches gather, and the short stitch assemblies have the short stitches that are sewn across one side and the other side in a direction intersecting the longitudinal direction of the reinforcing fiber bundles, and a pattern or design is represented by a plurality of switching points lined up at the boundary between adjacent long stitch assemblies and short stitch assemblies.

[0007] One of the features and advantages of the above configuration is that, as an intermediate base material for fiber-reinforced materials, reinforcing fiber bundles are oriented along the principal stress direction corresponding to the mechanical properties of the fiber-reinforced material on a sheet-like base material and are sewn in place by stitching. The length of the stitching changes at multiple switching points provided along the orientation path of the reinforcing fiber bundles, resulting in long stitches with longer lengths and short stitches with shorter lengths. Long stitch clusters, where long stitches are clustered, and short stitch clusters, where short stitches are clustered, are formed across multiple adjacent rows of reinforcing fiber bundles. The short stitch clusters have short stitches that span one side and the other side in a direction intersecting the longitudinal direction of the reinforcing fiber bundles, and because these short stitches are more densely arranged on the reinforcing fiber bundles, the exposure of the reinforcing fiber bundles is suppressed. Therefore, there is a difference in the appearance of the material and gloss of the reinforcing fiber bundles exposed on the surface of the base material between adjacent long stitch clusters and short stitch clusters, separated by a boundary line formed by multiple switching points. Therefore, by connecting multiple switching points, the boundary line between the long stitch cluster and the short stitch cluster is represented as the outline of the diagram showing the pattern or design. In other words, the diagram is represented and the pattern or design is expressed without being restricted by the direction of arrangement of the reinforcing fiber bundles on the base material. Thus, it is possible to provide an intermediate base material that allows for free design expression while maintaining the strength and rigidity of the fiber-reinforced material.

[0008] The above-mentioned intermediate material may have a configuration in which the width of the reinforcing fiber bundle in the long stitch assembly portion is wide in the planar direction of the material, and the width of the reinforcing fiber bundle in the short stitch assembly portion is narrow in the narrow region in which the width of the reinforcing fiber bundle is narrower than that of the reinforcing fiber bundle in the wide region.

[0009] One characteristic and advantage of the above configuration is that in the long stitch clusters, the width of the reinforcing fiber bundles is wider, which can emphasize the material and luster of the reinforcing fiber bundles. On the other hand, in the short stitch clusters, the width of the reinforcing fiber bundles is narrower, which can emphasize the stitching of the sewing threads more than the material and luster of the reinforcing fiber bundles. Therefore, it is possible to more easily create a difference in how the material and luster of the reinforcing fiber bundles appear between adjacent long stitch clusters and short stitch clusters, which can express the light and dark shades of a pattern or design.

[0010] The above-mentioned intermediate material may have a first stitch assembly and a second stitch assembly as the short stitch assembly portion, wherein the stitch length of the first stitch assembly portion is set to be shorter than that of the second stitch assembly portion, and the first stitch assembly portion may be formed in the portion representing the outline in the line diagram of the design or pattern.

[0011] One of the features and advantages of the above configuration is that, among the short stitch clusters, the first stitch cluster, which has shorter stitch lengths, is formed in the part that represents the outline of the line diagram that depicts the pattern or design. This makes the stitches of the sewing thread denser and can emphasize the outline. Therefore, the pattern or design can be expressed more effectively, and the design quality can be improved.

[0012] The above-mentioned intermediate material may have a configuration in which the reinforcing fiber bundle has a curved portion in which the orientation path traces a relatively gentle curve, and a curved portion that is bent with a smaller radius of curvature than the curved portion, and the short stitch assembly portion is arranged in the curved portion.

[0013] One of the features and advantages of the above configuration is that, in curved sections where the orientation path of the reinforcing fiber bundles is bent with a relatively small radius of curvature, the stitch length is set to be shorter, making it easier to hold the oriented reinforcing fiber bundles. In other words, displacement of the reinforcing fiber bundles on the substrate can be suppressed.

[0014] Regarding the above-mentioned intermediate material, the sewing thread may be configured to be a different color from the reinforcing fiber bundle.

[0015] One of the features and advantages of the above configuration is that by using different colors for the reinforcing fiber bundles and the sewing thread, the material, luster, and color of the reinforcing fiber bundles can be emphasized in the long stitch clusters. On the other hand, the stitches and color of the sewing threads can be emphasized in the short stitch clusters. In other words, it is easy to create a difference in how the colors appear in adjacent long stitch clusters and short stitch clusters, which can improve the design.

[0016] One feature of a method for manufacturing an intermediate substrate for fiber-reinforced materials that solves the above problems is a method for manufacturing an intermediate substrate in which reinforcing fiber bundles are oriented along the principal stress direction according to the required mechanical properties of the fiber-reinforced material and sewn to a sheet-like substrate, wherein the intermediate substrate has stitches that are continuously applied along the longitudinal direction of the reinforcing fiber bundles along at least one surface of the substrate, and the stitches are configured to have long stitches with a relatively long stitch length, which is the distance along the longitudinal direction of the reinforcing fiber bundles, and short stitches with a relatively short stitch length, and a switching point setting process is used to set a plurality of switching points on the orientation path of the reinforcing fiber bundles, where the stitch length changes by switching between the long stitches and the short stitches, based on a diagram representing a pattern or design. The method includes a stitch length setting step, in which multiple stitch assemblies are arranged to span multiple adjacent rows of reinforcing fiber bundles, such as a long stitch assemblies where the long stitches are gathered and a short stitch assemblies where the short stitches are gathered, and the stitch length in each stitch assemblies is set; and a sewing step, in which the reinforcing fiber bundles are arranged on the base material along an orientation path and the stitches are sewn in place with the sewing thread while switching the stitch length at the switching points, wherein the short stitch assemblies have short stitches that are sewn across one side and the other side in a direction intersecting the longitudinal direction of the reinforcing fiber bundles, and a pattern or design is represented by multiple switching points being lined up at the boundary between adjacent long stitch assemblies and short stitch assemblies.

[0017] One feature and advantage of the above configuration is that an intermediate substrate is formed on a sheet-like base material in which reinforcing fiber bundles are oriented along the principal stress direction corresponding to the mechanical properties of the fiber-reinforced material and sewn together by stitching thread. In the switching point setting process, multiple switching points are provided on the orientation path of the reinforcing fiber bundles, where the stitch length changes by switching between long stitches with a long stitch length and short stitches with a short stitch length. In the stitch length setting process, stitch assemblies are arranged across multiple adjacent rows of reinforcing fiber bundles to set the stitch length. Through these processes, multiple stitch assemblies with different stitch lengths are arranged, including long stitch assemblies where long stitches are gathered and short stitch assemblies where short stitches are gathered. The short stitch assemblies have short stitches that span one side and the other side in a direction intersecting the longitudinal direction of the reinforcing fiber bundle, and by arranging these short stitches more densely on the reinforcing fiber bundle, the exposure of the reinforcing fiber bundle is suppressed. Therefore, adjacent long-stitch assemblies and short-stitch assemblies differ in the material and gloss of the reinforcing fiber bundles exposed on the surface of the substrate, separated by a boundary line formed by multiple transition points. As a result, the boundary line between the long-stitch assemblies and short-stitch assemblies, formed by multiple transition points, is represented as the outline of a line diagram depicting a pattern or design. In other words, the line diagram is represented on the substrate without being restricted by the direction of arrangement of the reinforcing fiber bundles, and a pattern or design is expressed. Therefore, an intermediate substrate can be provided that allows for free design expression while maintaining the strength and rigidity of the fiber-reinforced material.

[0018] In the above-described method for manufacturing the intermediate substrate, a wide region may be formed in the long stitch assembly where the width of the reinforcing fiber bundles is widened in the planar direction of the substrate, and a narrow region may be formed in the short stitch assembly where the width of the reinforcing fiber bundles is narrower than that of the wide region.

[0019] One feature and advantage of the above configuration is that in the long stitch clusters, a wide area is formed where the width of the reinforcing fiber bundles is widened, which can emphasize the material and luster of the reinforcing fiber bundles. In the short stitch clusters, a narrow area is formed where the width of the reinforcing fiber bundles is narrow, which can emphasize the stitches of the sewing thread. Therefore, it is possible to more easily create a difference in how the material and luster of the reinforcing fiber bundles appear between adjacent long stitch clusters and short stitch clusters, which can express the light and dark shades of a pattern or design.

[0020] In the method for manufacturing the above-described intermediate material, the stitch length setting step may be configured such that a first stitch assembly and a second stitch assembly are provided as the short stitch assembly, the stitch length of the first stitch assembly is set to be shorter than that of the second stitch assembly, and the first stitch assembly is provided in the portion representing the contour line in the line diagram of the design or pattern.

[0021] One of the features and advantages of the above configuration is that, among the short stitch clusters, the first stitch cluster, which has a shorter stitch length, is positioned in the area representing the outline of the line diagram depicting the pattern or design. This makes the stitches of the sewing thread denser, emphasizing the outline. Therefore, the pattern or design can be expressed more effectively, and the design quality can be improved.

[0022] Regarding the method for manufacturing the above-described intermediate material, the intermediate material has a curved portion in which the orientation path of the reinforcing fiber bundles forms a relatively gentle curve, and a curved portion that is bent with a smaller radius of curvature than the curved portion, and the stitch length setting step may be configured such that the short stitch assembly portion is arranged in the curved portion.

[0023] One feature and advantage of the above configuration is that, in curved sections where the orientation path of the reinforcing fiber bundles is bent with a relatively small radius of curvature, shortening the stitch length makes it easier to hold the reinforcing fiber bundles. In other words, displacement of the reinforcing fiber bundles on the substrate can be suppressed.

[0024] Regarding the method for manufacturing the above-mentioned intermediate material, the sewing thread may be configured to be a different color from the reinforcing fiber bundle.

[0025] One of the features and advantages of the above structure is that by making the colors of the reinforcing fiber bundles and the sewing threads different, the long stitch assembly part can emphasize the material, luster, color, etc. of the reinforcing fiber bundles. On the other hand, the short stitch assembly part can emphasize the stitches and colors of the sewing threads. That is, it is possible to easily create a difference in the appearance of the color combinations between the adjacent long stitch assembly part and the short stitch assembly part, and the designability can be improved.

Effects of the Invention

[0026] By having the above structure, the present invention can provide an intermediate base material of a fiber reinforced material and a method for manufacturing the same, which can freely express designs while maintaining strength, rigidity, etc.

Brief Description of the Drawings

[0027] [Figure 1] It is a schematic diagram showing an example of the orientation of the reinforcing fiber bundles of the intermediate base material according to the present embodiment and the pattern expressed. [Figure 2] It is a schematic diagram showing the form of the reinforcing fiber bundles and the stitches of the sewing threads of the intermediate base material according to the present embodiment. [Figure 3] It is a diagram showing an example of the principal stress curve serving as the orientation path of the reinforcing fiber bundles and the diagram of the pattern, which are set in the creation of the stitch data. [Figure 4] It is a diagram showing an example of the arrangement of the stitch assembly parts, which are set in the creation of the stitch data. [Figure 5] It is a diagram showing an example of the setting of the stitch length of the sewing thread at V in FIG. 4. [Figure 6] It is a diagram showing other design examples expressed on the intermediate base material. [Figure 7] It is a diagram showing other design examples expressed on the intermediate base material. [Figure 8] It is a diagram showing other design examples expressed on the intermediate base material. [Figure 9] It is a diagram showing an example of the change of the stitches of the sewing thread.

Embodiments for Carrying Out the Invention

[0028] <Composition of intermediate material> Embodiments of the present invention will be described with reference to the drawings. The intermediate substrate 2 of the fiber-reinforced material according to this embodiment is formed by the TFP (Tailored Fiber Placement) method. The TFP method is generally a fiber preform technology that applies textile technology, and by continuously and freely arranging reinforcing fibers, it is possible to form a preform (intermediate substrate) with the required strength in the required direction. As shown in Figure 1, the intermediate substrate 2 has reinforcing fiber bundles 4 oriented along the principal stress direction according to the required mechanical properties of the fiber-reinforced material on a sheet-like substrate 3. The reinforcing fiber bundles 4 oriented on the substrate 3 are sewn in place with sewing thread 5, as shown in Figure 2. The formed intermediate substrate 2 is impregnated with, for example, a thermosetting resin or a thermoplastic resin to form a fiber-reinforced plastic.

[0029] The base material 3 is a sheet-like base material on which the reinforcing fiber bundles 4 can be sewn. The base material 3 is not limited to a specific material, and can be selected as a woven fabric, nonwoven fabric, knitted fabric, etc., composed of cotton, glass fiber, or a resin film as the base material.

[0030] The reinforcing fiber bundle 4 is a long fiber bundle formed by bundling together multiple continuous fibers of a certain length; for example, a carbon fiber bundle is selected. The number of single fibers constituting the carbon fiber bundle is not particularly limited and can be appropriately selected depending on the purpose and application, for example, from a bundle of 3,000 fibers to a bundle of 50,000 fibers. For example, when the pattern to which the reinforcing fiber bundle 4 is sewn is small or when producing thin products, a carbon fiber bundle with fewer fibers is used. Also, by using a carbon fiber bundle with a large number of fibers, the production time of the intermediate material 2 can be shortened. Note that a fiber bundle with fewer than 3,000 single fibers may be used, or a fiber bundle with 50,000 or more fibers may be used. The reinforcing fiber bundle 4 is not limited to a specific material; for example, a long fiber bundle composed of carbon fiber, natural fiber, glass fiber, etc. may be selected. Also, a reinforcing fiber bundle 4 composed of multiple reinforcing fibers may be used. The reinforcing fiber bundle 4 may be oriented as a single continuous fiber bundle without interruption from the start point to the end point along the direction of the principal stress.

[0031] The sewing thread 5 used to secure the reinforcing fiber bundle 4 to the base material 3 is, for example, polyester embroidery thread. The sewing thread 5 is not limited to a specific material; it can be embroidery thread made of polyester, thread made of the same type of resin as the base material, etc. The color of the sewing thread 5 can also be any color. For example, it may be a different color from the reinforcing fiber bundle 4, or it may be a similar color to the reinforcing fiber bundle 4.

[0032] As shown in Figure 1, the reinforcing fiber bundles 4 are oriented in multiple rows along at least one surface of the base material 3. The orientation path of the reinforcing fiber bundles 4 is set according to the principal stress direction of the fiber-reinforced material. In other words, the orientation path of the reinforcing fiber bundles 4 is set to trace the principal stress curve 12 of the fiber-reinforced material. The principal stress curve 12 is a line representation of the direction of force flow obtained by structural analysis. The reinforcing fiber bundles 4 oriented on the base material 3 have a curved section 13 in which the orientation path traces a relatively gentle curve, and a curved section 14 that is bent with a smaller radius of curvature than the curved section 13.

[0033] As shown in Figure 2, the reinforcing fiber bundles 4 oriented on the base material 3 are sewn to the base material 3 using a zigzag stitch. The stitches of the sewing thread 5 span across one side and the other side in a direction intersecting the longitudinal direction of the reinforcing fiber bundles 4, and are applied continuously along the longitudinal direction of the reinforcing fiber bundles 4. The stitch length L of the sewing thread 5 varies depending on the pattern or design expressed on the base material 3, and includes long stitches 6 with a relatively long stitch length L and short stitches 7 with a relatively short stitch length L. The stitch length L is the distance along the longitudinal direction of the reinforcing fiber bundles 4 as the sewing thread 5 is sewn. The stitch width W of the sewing thread 5 is set as appropriate. The stitch width W of the sewing thread 5 is the distance along a direction perpendicular to the longitudinal direction of the reinforcing fiber bundles 4 as the sewing thread 5 is sewn across one side and the other side of the reinforcing fiber bundles 4.

[0034] Figure 1 is a schematic plan view of an intermediate substrate 2 on which reinforcing fiber bundles 4 are oriented on a base material 3. The intermediate substrate 2 has multiple stitch assemblies formed across multiple adjacent rows of reinforcing fiber bundles 4. The area in which each stitch assembly is formed includes regions extending in directions along the principal stress curve 12 and in directions intersecting the principal stress curve 12. The stitch assemblies have long stitch assemblies 8 where long stitches 6 are assembled and short stitch assemblies 9 where short stitches 7 are assembled. The intermediate substrate 2 displays a pattern or design because the long stitch assemblies 8 and short stitch assemblies 9 on the base material 3 are arranged based on stitch data described later.

[0035] Figure 3 shows an example of placing a pattern or design diagram 15 on the principal stress curve 12 in the stitch data. The pattern or design diagram 15 broadly includes diagrams representing the external shape of the depicted object, characters, etc. The contour lines of the diagram 15 in this embodiment include the peripheral contour line 17a representing the main body of the pattern, i.e., the external shape of the pattern, and the internal contour line 17b represented inside the main body. Figure 4 shows an example of placing a long stitch assemblies 8 and short stitch assemblies 9 on the principal stress curve 12 in the stitch data based on the pattern or design diagram 15. Figure 5 is a magnified view of Figure 4, showing the vicinity of the boundary between the long stitch assemblies 8 and short stitch assemblies 9 on the stitch data. Multiple switching points 16 between long stitches 6 and short stitches 7 are provided on the principal stress curve 12 of the reinforcing fiber bundle 4. The switching points 16 are set near the boundary points 18, which are the intersections of the principal stress curve 12 and the contour lines 17a and 17b of the diagram 15. As a result, multiple switching points 16 are connected at the boundary between the adjacent long stitch assemblies 8 and short stitch assemblies 9 of the intermediate material 2, representing the contour lines 17a and 17b in the diagram 15.

[0036] As shown in Figures 1 and 2, the long stitches 6 have a relatively long stitch length L, so the reinforcing fiber bundles 4 are not restricted by the sewing thread 5, and are more easily compressed and spread out in the planar direction of the base material 3 when, for example, the intermediate base material 2 is solidified with resin. In other words, the long stitch aggregate portion 8, where the long stitches 6 are gathered, is configured as a wide region where the width of the reinforcing fiber bundles 4 is spread out in the planar direction of the base material 3. The short stitches 7 have a relatively short stitch length L, so the spreading of the reinforcing fiber bundles 4 is suppressed by the sewing thread 5. Therefore, the short stitch aggregate portion 9, where the short stitches 7 are gathered, is configured as a narrow region where the width of the reinforcing fiber bundles 4 is narrower than that of the reinforcing fiber bundles 4 in the wide region.

[0037] As shown in Figure 4, in this embodiment, a long stitch cluster 8 is arranged in the main body region 20 inside the peripheral contour line 17a representing the outer shape of the pattern, and a short stitch cluster 9 is arranged in the background region 25 surrounding the main body. In the main body region 20 of the pattern, the long gloss of the reinforcing fiber bundles 4 is intermittently generated, and its gloss and color are visible on the surface of the intermediate material 2. In contrast, in the background region 25, the gloss of the reinforcing fiber bundles 4 is suppressed by the dense stitching of the sewing threads 5 that cross over the reinforcing fiber bundles 4. In other words, there is a difference in how the gloss and color of the reinforcing fiber bundles 4 are displayed in the long stitch cluster 8 and the short stitch cluster 9.

[0038] The intermediate material 2 has a short stitch collection section 9, which includes a first stitch collection section 9a and a second stitch collection section 9b. The stitch length L of the sewing thread 5 in the first stitch collection section 9a is set to be shorter than that of the second stitch collection section 9b. The first stitch collection section 9a includes short stitches 7 with the shortest possible stitch length L. In this embodiment, the first stitch collection section 9a is formed in the first region 21, which is set within the main body region 20 to include the internal contour line 17b and its surroundings, and in the region where multiple curved sections 14 are lined up. The internal contour line 17b is represented by a series of switching points 16 at the boundary between the first stitch collection section 9a and the adjacent long stitch collection section 8. Furthermore, the first stitch collection section 9a may also be formed in the portion representing the peripheral contour line 17a. In addition, the second stitch collection section 9b is formed in the second region 22, which is set within the main body region 20 to represent the difference in brightness, and in the background region 25.

[0039] The intermediate material 2 has a long stitch junction 8, which includes a third stitch junction 8a and a fourth stitch junction 8b. The stitch length L of the sewing thread 5 in the third stitch junction 8a is set shorter than that of the fourth stitch junction 8b. The third stitch junction 8a is formed in the third region 23, which is a section of the curved portion 13 within the main body region 20 where the radius of curvature of the principal stress curve 12 is slightly smaller. The fourth stitch junction 8b is formed in the portion of the main body region 20 excluding the first region 21, the second region 22, and the third region 23. The fourth stitch junction 8b includes a long stitch 6 with the longest possible stitch length L.

[0040] The intermediate material 2 may be made by selecting a carbon fiber bundle for the reinforcing fiber bundle 4 and white embroidery thread for the sewing thread 5. In the long stitch clusters 8, the black color of the carbon fiber is more visible on the surface, while in the short stitch clusters 9, the white color of the sewing thread 5 is more visible on the surface. In other words, the pattern can also be expressed by the difference in brightness between the colors of the reinforcing fiber bundle 4 and the sewing thread 5.

[0041] Figure 6 shows another example of a pattern or design, where a pattern is expressed on the intermediate material 2. On the orientation path of the reinforcing fiber bundles 4, i.e., the principal stress curve 12, switching points 16 between long stitches and short stitches are set based on the diagram of the pattern. Differences in the material and gloss of the reinforcing fiber bundles 4 occur at the long stitch aggregate area 8c and the short stitch aggregate area 9c, resulting in the appearance of a pattern.

[0042] Figure 7 shows an example in which alphabetical characters are represented on the intermediate material 2. Along the orientation path of the reinforcing fiber bundle 4, i.e., the principal stress curve 12, switching points 16 between long stitches and short stitches are set along the alphabetical characters. Long stitch clusters 8d are formed in the parts representing the alphabetical characters, and short stitch clusters 9d are formed around the characters.

[0043] Figure 8 shows an example of a gradient being represented in the intermediate material 2. Multiple switching points 16 are set to be regularly arranged on the orientation path of the reinforcing fiber bundle 4, i.e., the principal stress curve 12. The stitch length L is set to become progressively shorter or longer at each switching point 16, forming long stitch assemblies 8e, 8f and short stitch assemblies 9e.

[0044] The long stitch cluster 8 may be configured such that the long stitches 6 are sewn without crossing over the reinforcing fiber bundle 4, as shown in Figure 9. Furthermore, the long stitch cluster 8 and the short stitch cluster 9 may each include in part stitches that are sewn without crossing over one side and the other side in a direction intersecting the longitudinal direction of the reinforcing fiber bundle 4.

[0045] <Method for manufacturing intermediate materials> Next, a method for manufacturing the intermediate material 2 according to this embodiment will be described. The manufacturing process for the intermediate material 2 includes a switching point setting step, a stitch length setting step, and a stitching and securing step. The switching point setting step and the stitch length setting step are steps for creating stitch data for the sewing thread 5.

[0046] <Steps for creating stitch data> The stitch data for the sewing thread 5 is determined by arranging long stitches 6 and short stitches 7 on the orientation path of the reinforcing fiber bundles 4, i.e., on the principal stress curve 12, based on a line diagram 15 representing a pattern or design. The orientation of the reinforcing fiber bundles 4 in the base material 3 is determined by a known method. First, as shown in Figure 3, a line diagram 15 of the pattern expressed on the intermediate base material 2 is created and superimposed on the principal stress curve 12 of the stitch data. The line diagram 15 may be created based on a photograph or drawing. For example, a photograph or drawing that serves as the basis for the pattern is converted into a black and white image, and the line diagram 15 is created based on the contours and brightness of the shape shown in the image. In addition to contour lines 17a and 17b, the line diagram 15 shows a second region 22 that represents the difference in brightness in the main body of the pattern.

[0047] As shown in Figures 4 and 5, boundary points 18 are set on the principal stress curve 12. The boundary points 18 are defined as the intersections of the principal stress curve 12 and the contour lines 17a and 17b of Figure 15. In other words, the boundary points 18 are uniquely determined when Figure 15 is superimposed on the principal stress curve 12 of the stitch data. The boundary points 18 are not limited to the contour lines 17a and 17b of Figure 15, but may be set appropriately at locations where the stitch length L is to be changed, depending on the characteristics of the pattern or the radius of curvature of the principal stress curve 12.

[0048] The switching point setting process is a process of setting multiple switching points 16 on the orientation path of the reinforcing fiber bundle 4 based on a diagram 15 representing a pattern or design. As shown in Figure 5, the switching points 16 are the points where long stitches 6 and short stitches 7 switch over, and are located near boundary points 18 set on the principal stress curve 12. Here, the stitch located at the boundary between the long stitch assembly 8 and the short stitch assembly 9 is defined as the boundary stitch 26. The boundary stitch 26 is a long stitch 6 or short stitch 7, with one end of the stitch becoming a switching point 16. The switching point 16 is set such that the boundary point 18 is located between one end (switching point 16) and the other end of the boundary stitch 26.

[0049] The stitch length setting process, as shown in Figure 4, involves arranging multiple stitch assemblies, namely long stitch assemblies 8 and short stitch assemblies 9, which span multiple adjacent rows of reinforcing fiber bundles 4, in the creation of stitch data, and setting the stitch length L for each stitch assemblies 8 and 9. The arrangement of long stitches 6 and short stitches 7 at the boundary between stitch assemblies 8 and 9 is related to the setting of switching points 16, and multiple switching points 16 are connected in the stitch data to set the boundary between stitch assemblies 8 and 9. Then, data for the principal stress curve 12, which is the orientation path of the reinforcing fiber bundles 4, and the data for the multiple stitch assemblies 8 and 9 and their stitch lengths L arranged on the principal stress curve 12 are created.

[0050] In this embodiment, the short stitch assembly section 9 consists of a first stitch assembly section 9a and a second stitch assembly section 9b, and the long stitch assembly section 8 consists of a third stitch assembly section 8a and a fourth stitch assembly section 8b.

[0051] The first stitch assemblies 9a are stitch assemblies whose stitch length L is set shorter than that of the second stitch assemblies 9b, and which have the shortest stitch 7 with the shortest stitch length L. The first stitch assemblies 9a are located in the first region 21 described above. The second stitch assemblies 9b are stitch assemblies whose stitch length L is longer than that of the first stitch assemblies 9a and shorter than that of the third stitch assemblies 8a. The second stitch assemblies 9b are located in the second region 22 described above. The first stitch assemblies 9a may also be located in both the peripheral contour line 17a and the internal contour line 17b of the figure 15. The parts of the figure 15 representing the contour lines 17a and 17b can be appropriately represented using the boundary between the long stitch assemblies 8 and the short stitch assemblies 9, or represented using the first stitch assemblies 9a, etc.

[0052] The third stitch assembly 8a is a stitch assembly whose stitch length L is longer than that of the second stitch assembly 9b and shorter than that of the fourth stitch assembly 8b. The third stitch assembly 8a is located in the third region 23 described above. The fourth stitch assembly 8b is a stitch assembly whose stitch length L is longer than that of the third stitch assembly 8a and has the longest stitch 6 with the longest stitch length L. The fourth stitch assembly 8b is located in the main body region 20 excluding the first region 21, the second region 22, and the third region 23.

[0053] <Stitching process> The stitching process involves arranging reinforcing fiber bundles 4 on the base material 3 along an orientation path and stitching them in place with sewing thread 5 while switching the stitch length L at a switching point 16. For example, carbon fiber bundles are selected for the reinforcing fiber bundles 4, and polyester embroidery thread is selected for the sewing thread 5. The color of the sewing thread 5 may be different from the color of the reinforcing fiber bundles 4, or it may be a similar color. In the stitching process, a sewing machine (embroidery machine) specifically for reinforcing fibers is used, and the reinforcing fiber bundles 4 are sewn using a zigzag stitch where the stitches cross in a direction intersecting the longitudinal direction. The stitch length L of the sewing thread 5 is switched at the switching point 16 based on the arrangement of the long stitch collection section 8 and the short stitch collection section 9 set in the stitch length setting process, and the data of the stitch length L in each of the stitch collection sections 8 and 9.

[0054] The intermediate material 2 manufactured by the above process has multiple switching points 16 connected at the boundary between adjacent long stitch assemblies 8 and short stitch assemblies 9, which represent the outlines 17a, 17b, etc. in the diagram 15, and thus a pattern or design is displayed.

[0055] The intermediate base material 2 is molded by impregnating it with, for example, a thermosetting resin. In this case, in the long stitch junction 8, because the stitch length L is relatively long, the reinforcing fiber bundles 4 are not restricted by the sewing thread 5 and are easily compressed and spread out in the planar direction of the base material 3. That is, the long stitch junction 8 is configured as a wide region in which the width of the reinforcing fiber bundles 4 is spread out in the planar direction of the base material 3. In the short stitch junction 9, because the stitch length L is relatively short, the spreading of the reinforcing fiber bundles 4 is suppressed by the sewing thread 5, and the width of the reinforcing fiber bundles 4 is configured as a narrow region in which the width of the reinforcing fiber bundles 4 is narrower than that of the reinforcing fiber bundles 4 in the wide region.

[0056] As another example of a design or pattern, a pattern may be represented on the intermediate material 2, as shown in Figure 6. On the principal stress curve 12 of the reinforcing fiber bundle 4, switching points 16 between long stitches and short stitches are set based on the diagram of the pattern. Then, long stitch assemblies 8c and short stitch assemblies 9c are arranged corresponding to the lightness and darkness of the colors in the pattern.

[0057] As shown in Figure 7, letters may be represented on the intermediate material 2. On the principal stress curve 12 of the reinforcing fiber bundle 4, for example, switching points 16 between long stitches and short stitches are set along the contour lines of alphabet letters. Then, long stitch clusters 8d are arranged in the part representing the alphabet letter, and short stitch clusters 9d are arranged around the part representing the letter.

[0058] As shown in Figure 8, a gradient may be expressed in the intermediate material 2. Multiple switching points 16 are set to be regularly arranged on the principal stress curve 12 of the reinforcing fiber bundle 4. Then, multiple stitch assemblies, namely long stitch assemblies 8e, 8f and short stitch assemblies 9e, are arranged so that the stitch length L changes in steps at the switching points 16.

[0059] The fiber-reinforced material comprising the intermediate substrate 2 according to this embodiment has a variety of applications, including, for example, automobile parts, aircraft parts, interior and exterior materials for vehicles, as well as sporting goods, building materials, furniture, and electrical appliances.

[0060] <Effects of the Embodiment> In the intermediate substrate 2 according to the above embodiment, reinforcing fiber bundles 4 are oriented along the principal stress direction corresponding to the mechanical properties of the fiber-reinforced material on a sheet-like substrate 3, and are sewn in place by stitches of sewing thread 5. The stitch length L of the sewing thread 5 changes at a plurality of switching points 16 provided on the orientation path of the reinforcing fiber bundles 4, and has long stitches 6 with a long stitch length L and short stitches 7 with a short stitch length L. A long stitch assemblies 8, where the long stitches 6 are gathered, and a short stitch assemblies 9, where the short stitches 7 are gathered are formed across a plurality of adjacent rows of reinforcing fiber bundles 4. The short stitch assemblies 9 have short stitches 7 that span one side and the other side in a direction intersecting the longitudinal direction of the reinforcing fiber bundles 4, and the exposure of the reinforcing fiber bundles 4 is suppressed by the denser arrangement of these short stitches 7 on the reinforcing fiber bundles 4. Therefore, there is a difference in the appearance of the material and gloss of the reinforcing fiber bundles 4 exposed on the surface of the substrate 3 between adjacent long stitch assemblies 8 and short stitch assemblies 9, separated by a boundary line formed by a plurality of switching points 16. Therefore, by connecting multiple switching points 16, the boundary line between the long stitch cluster 8 and the short stitch cluster 9 is represented as the outline lines 17a and 17b of the diagram 15 representing the pattern or design. In other words, the diagram 15 is represented and the pattern or design is expressed without being restricted by the direction of arrangement of the reinforcing fiber bundles 4 on the base material 3. Thus, an intermediate base material 2 can be provided that allows for free expression of designs while maintaining the strength and rigidity of the fiber-reinforced material.

[0061] In the long stitch cluster 8, the width of the reinforcing fiber bundle 4 is wider, which can emphasize the material and luster of the reinforcing fiber bundle 4. On the other hand, in the short stitch cluster 9, the width of the reinforcing fiber bundle 4 is narrower, which can emphasize the short stitches 7 of the sewing thread 5 more than the material and luster of the reinforcing fiber bundle 4. Therefore, it is possible to more easily create a difference in how the material and luster of the reinforcing fiber bundle 4 are displayed in adjacent long stitch cluster 8 and short stitch cluster 9, which can express the light and dark shades of a pattern or design.

[0062] In the intermediate material 2, the first stitch cluster 9a, which has a shorter stitch length L than the short stitch cluster 9, is formed in the portion representing the outline (e.g., internal outline 17b) of the line diagram 15 that represents the pattern or design. This makes the short stitches 7 of the sewing thread 5 denser, and the internal outline 17b (outline) can be emphasized. Therefore, the pattern or design can be expressed more effectively, and the design quality can be improved.

[0063] In the intermediate substrate 2, the stitch length L is set shorter in the curved portion 14 where the orientation path of the reinforcing fiber bundle 4 is bent with a relatively small radius of curvature, thereby making it easier to hold the oriented reinforcing fiber bundle 4. In other words, displacement of the reinforcing fiber bundle 4 on the substrate 3 can be suppressed.

[0064] The intermediate material 2 can be configured to highlight the material, luster, and color of the reinforcing fiber bundles 4 and sewing threads 5 by using different colors. In the long stitch cluster 8, the material, luster, and color of the reinforcing fiber bundles 4 can be emphasized. On the other hand, in the short stitch cluster 9, the stitches and color of the sewing threads 5 can be emphasized. In other words, it is possible to easily create a difference in how the colors appear in the adjacent long stitch cluster 8 and short stitch cluster 9, thereby improving the design.

[0065] According to the manufacturing method of the intermediate substrate 2 according to the above embodiment, an intermediate substrate 2 is formed by aligning reinforcing fiber bundles 4 on a sheet-like substrate 3 along the principal stress direction corresponding to the mechanical properties of the fiber-reinforced material, and sewing them together with stitches of sewing thread 5. In the switching point setting step, a plurality of switching points 16 are provided on the orientation path of the reinforcing fiber bundles 4, where the stitch length L changes by switching between long stitches 6 with a long stitch length L and short stitches 7 with a short stitch length L. In the stitch length setting step, the stitch length L is set by arranging stitch clusters that span multiple adjacent rows of reinforcing fiber bundles 4. Through these steps, a plurality of stitch clusters with different stitch lengths L are arranged, such as a long stitch cluster 8 where long stitches 6 are clustered and a short stitch cluster 9 where short stitches 7 are clustered. The short stitch cluster 9 has short stitches 7 that span one side and the other side in a direction intersecting the longitudinal direction of the reinforcing fiber bundles 4, and by arranging the short stitches 7 more densely on the reinforcing fiber bundles 4, the exposure of the reinforcing fiber bundles 4 is suppressed. Therefore, the adjacent long stitch assemblies 8 and short stitch assemblies 9 differ in the material and gloss of the reinforcing fiber bundles 4 exposed on the surface of the base material 3, separated by a boundary line formed by multiple switching points 16. As a result, the boundary line between the long stitch assemblies 8 and short stitch assemblies 9, formed by the multiple switching points 16, is represented as the outlines 17a and 17b of the diagram 15 representing the pattern or design. In other words, the diagram 15 is represented and the pattern or design is expressed without being restricted by the direction of arrangement of the reinforcing fiber bundles 4 on the base material 3. Therefore, an intermediate base material 2 can be provided that allows for free design expression while maintaining the strength and rigidity of the fiber-reinforced material.

[0066] In the manufacturing process of the intermediate material 2 described above, a wide area is formed in the long stitch cluster 8 where the width of the reinforcing fiber bundle 4 is widened, which can emphasize the material and luster of the reinforcing fiber bundle 4. In the short stitch cluster 9, a narrow area is formed where the width of the reinforcing fiber bundle 4 is narrowed, which can emphasize the stitches of the sewing thread 5. Therefore, it is possible to more easily create a difference in how the material and luster of the reinforcing fiber bundle 4 are displayed in the adjacent long stitch cluster 8 and short stitch cluster 9, which can express the light and dark shades of a pattern or design.

[0067] In the manufacturing process of the intermediate material 2 described above, the first stitch cluster 9a, which has a shorter stitch length L among the short stitch clusters 9, is placed in the portion representing the internal contour line 17b (contour line) of the line drawing 15 that represents the pattern or design. As a result, the stitches of the sewing thread 5 become denser, and the internal contour line 17b (contour line) can be emphasized. Therefore, the pattern or design can be expressed more effectively, and the design quality can be improved.

[0068] In the manufacturing process of the intermediate substrate 2 described above, by shortening the stitch length L in the curved portion 14 where the orientation path of the reinforcing fiber bundle 4 is bent with a relatively small radius of curvature, the reinforcing fiber bundle 4 can be more easily held. In other words, displacement of the reinforcing fiber bundle 4 on the substrate 3 can be suppressed.

[0069] In the manufacturing process of the intermediate material 2 described above, by using different colors for the reinforcing fiber bundles 4 and the sewing threads 5, the material, luster, and color of the reinforcing fiber bundles 4 can be emphasized in the long stitch clusters 8. On the other hand, the stitches and color of the sewing threads 5 can be emphasized in the short stitch clusters 9. In other words, it is possible to easily create a difference in how the colors appear in the adjacent long stitch clusters 8 and short stitch clusters 9, thereby improving the design.

[0070] The intermediate substrate for fiber-reinforced materials and its manufacturing method according to the present invention are not limited to the appearance and configuration described in the above embodiments, and can be implemented in various other forms by various modifications, additions, deletions, and combinations of configurations without altering the essence of the present invention.

[0071] For example, if the color of the reinforcing fiber bundle and the color of the sewing thread are different, this includes cases where the hue, saturation, or brightness are different, allowing for a variety of color combinations to be chosen.

[0072] The intermediate material may also be constructed by sewing the reinforcing fiber bundles onto the long stitch clusters with stitches of another embroidery thread and then pressing them down. This allows the reinforcing fiber bundles to spread out more along the surface direction of the material.

[0073] The design or pattern displayed on the intermediate material may be in which a portion of the outline of the line drawing is represented by a collection of short stitches.

[0074] A sewing thread can express a pattern or design if at least two different stitch lengths are set. Alternatively, the sewing thread may have three or more different stitch lengths. In this case, the "long stitch clusters" and "short stitch clusters" are appropriately defined based on the relative stitch lengths within each cluster. Furthermore, "switching between long and short stitches at a switching point" includes switching to different stitch lengths at that point.

[0075] The arrangement of the long stitch clusters and short stitch clusters is not limited to the configuration in the above embodiment, and can be changed as appropriate in the expressed design or pattern. For example, the arrangement of the long stitch clusters and short stitch clusters may be swapped.

[0076] The type of stitch used to secure the reinforcing fiber bundles to the base material with sewing thread is not limited to the zigzag stitch; other stitches can also be applied. [Explanation of Symbols]

[0077] 2. Intermediate substrate 3 Base material 4 Reinforcement fiber bundles 5 Sewing thread 6 Long stitches 7 Short stitches 8 Long stitch cluster 8a Third stitch junction 8b Fourth stitch junction 9. Short stitch cluster 9a First stitch junction 9b Second stitch junction 12 Principal stress curves 13 Curved section 14 Curved section 15 Diagram 16 switching points 17a Peripheral contour line (contour line) 17b Internal contour lines (contour lines) 18 Boundary points 20 Body area 21 First area 22 Second area 23 Third area 25 Background area 26 Boundary Stitch L Stitch length W Stitch width

Claims

1. An intermediate material is formed by sewing together reinforcing fiber bundles to a sheet-like base material, oriented along the principal stress direction corresponding to the required mechanical properties of the fiber-reinforced material. The sewing thread has stitches made along at least one surface of the base material in a continuous manner in the longitudinal direction of the reinforcing fiber bundle, The aforementioned stitches include long stitches, in which the stitch length, which is the distance along the longitudinal direction of the reinforcing fiber bundle, is set to be relatively long, and short stitches, in which the stitch length is set to be relatively short. A switching point between the long stitch and the short stitch provided on the orientation path of the reinforcing fiber bundle, The multiple stitch assemblies formed across the reinforcing fiber bundles in multiple adjacent rows include long stitch assemblies where the long stitches are gathered and short stitch assemblies where the short stitches are gathered. The short stitch assembly has short stitches that are sewn across one side and the other side in a direction intersecting the longitudinal direction of the reinforcing fiber bundle. An intermediate material in which a pattern or design is represented by a series of switching points at the boundary between adjacent long stitch clusters and short stitch clusters.

2. An intermediate material according to claim 1, In the long stitch aggregate portion, the width of the reinforcing fiber bundle is wide in the planar direction of the substrate, An intermediate material having a narrow region in which the width of the reinforcing fiber bundle in the short stitch aggregate is narrower than the width of the reinforcing fiber bundle in the wide region.

3. An intermediate material according to claim 1 or claim 2, The aforementioned short stitch collection section includes a first stitch collection section and a second stitch collection section. The stitch length of the first stitch assembly is set to be shorter than that of the second stitch assembly. An intermediate substrate in which the first stitch cluster is formed in the portion representing the outline of a line drawing of a pattern or design.

4. An intermediate material according to claim 1 or claim 2, The reinforcing fiber bundle has a curved portion in which the orientation path forms a relatively gentle curve, and a curved portion that is bent with a smaller radius of curvature than the curved portion, and the short stitch assembly portion is arranged in the curved portion, an intermediate material.

5. An intermediate material according to claim 1 or claim 2, The sewing thread is an intermediate material having a different color from the reinforcing fiber bundle.

6. A method for manufacturing an intermediate substrate, comprising sewing a bundle of reinforcing fibers onto a sheet-like substrate, oriented along the principal stress direction corresponding to the required mechanical properties of the fiber-reinforced material, The intermediate substrate has a sewing thread in which stitches are continuously applied along the longitudinal direction of the reinforcing fiber bundle along at least one surface of the substrate, and the stitches are configured to include long stitches, which have a relatively long stitch length, which is the distance along the longitudinal direction of the reinforcing fiber bundle, and short stitches, which have a relatively short stitch length. A switching point setting step, in which a plurality of switching points are set on the orientation path of the reinforcing fiber bundle based on a line diagram representing a pattern or design, such that the stitch length changes by switching between the long stitch and the short stitch, A stitch length setting step is provided in which multiple stitch assemblies are formed across multiple adjacent rows of reinforcing fiber bundles, including a long stitch assembly where the long stitches are assembled and a short stitch assembly where the short stitches are assembled, and the stitch length in each stitch assembly is set. The process includes arranging the reinforcing fiber bundle on the substrate along an orientation path, and sewing it in place with the sewing thread while switching the stitch length at the switching point, The short stitch assembly has short stitches that are sewn across one side and the other side in a direction intersecting the longitudinal direction of the reinforcing fiber bundle. A method for manufacturing an intermediate substrate, wherein a pattern or design is represented by a series of switching points at the boundary between adjacent long stitch clusters and short stitch clusters.

7. A method for producing an intermediate substrate according to claim 6, A method for manufacturing an intermediate substrate, wherein a wide region is formed in the long stitch aggregate where the width of the reinforcing fiber bundle is extended in the planar direction of the substrate, and a narrow region is formed in the short stitch aggregate where the width of the reinforcing fiber bundle is narrower than that of the wide region.

8. A method for producing an intermediate substrate according to claim 6 or claim 7, The stitch length setting step is performed by arranging a first stitch assembly section and a second stitch assembly section as the short stitch assembly section. The stitch length of the first stitch assembly is set to be shorter than that of the second stitch assembly. A method for manufacturing an intermediate substrate, wherein the first stitch assembly is arranged in the portion representing the outline in the line diagram of a design or pattern.

9. A method for producing an intermediate substrate according to claim 6 or claim 7, The intermediate material has a curved portion in which the orientation path of the reinforcing fiber bundle forms a relatively gentle curve, and a curved portion that is bent with a smaller radius of curvature than the curved portion. The stitch length setting step is a method for manufacturing an intermediate substrate, wherein the short stitch collection portion is arranged in the curved portion.

10. A method for producing an intermediate substrate according to claim 6 or claim 7, A method for manufacturing an intermediate material, wherein the sewing thread is of a different color from the reinforcing fiber bundle.

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