Forming tool and forming method for curved-surface hollow fabric composite material

Abstract

The invention relates to a forming tool and a forming method for a curved-surface hollow fabric composite material, and belongs to composite material preparation, the forming tool comprises a core rod array, the core rod array is used for being inserted into a cavity of a hollow fabric prefabricated body to shape the hollow fabric prefabricated body; and the core rod array has a spatial curved surface structure consistent with a target molded surface in an assembly state. The hollow curved surface composite material manufactured by the forming tool provided by the invention is higher in forming precision, better in curved surface effect and fewer in surface layer defects, and can be applied to forming of a composite material with a complex curved surface structure.

Description

Technical Field

[0001] This invention relates to the preparation of composite materials, and in particular to a molding tooling and molding method for a curved hollow fabric composite material. Background Technology

[0002] Against the backdrop of rapid development in electromagnetic detection technology, key component technologies such as complex shapes, lightweight design, large size, and integrated structure and function have become increasingly important, especially in fields such as electromagnetic wave transmission, absorption, and shielding. Currently, foam and honeycomb sandwich materials, which are widely used in the market, suffer from significant challenges such as the difficulty and high cost of molding complex, irregularly shaped structures. Three-dimensional hollow fabrics, with their integral flexible continuous cavity, offer significant advantages over traditional sandwich materials in terms of designability, resistance to delamination, and wave transmission functionality, making them a promising new material for fabricating lightweight, large-size, complex-shaped, and integrated structural and functional components. However, from the perspective of material application itself, the increasing complexity of product shapes poses a significant challenge to controlling the overall precision of the fabric composite molding process.

[0003] Chinese patent CN119329076A utilizes a flexible fixed core plate to prepare single-curvature curved surface hollow fabrics. Its basic principle is to leverage the developability of the single-curvature surface; a straight core plate is placed into the cavity of the unfolded planar fabric, and then it is bent to conform to the shape on a curved mold to form a spatial curved surface. Another method utilizes a flexible core plate to prepare double-curvature hollow fabrics. A straight mandrel is first inserted into the cavity of the planar fabric. Taking advantage of the fabric's flexibility and deformability, and the flexible core plate's toughness, the fabric preform with the inserted straight mandrel is pre-shaped using curved male and female molds to generate the curved surface shape. However, this method has a relatively passive spatial transition. During the pressure shaping process, the core plate faces multi-directional torsional deformation within a limited space, which cannot avoid damage to the hollow fabric reinforcement material. Furthermore, the torsional deformation may further damage the internal structure of the composite material during the demolding process.

[0004] Chinese patent CN119175894A utilizes a curved support frame and a curved flexible fixing core plate to introduce Z-axis free yarns through sewing to prepare hollow fabrics with the same surface shape. These fabrics are then composited with resin to obtain a hollow fabric composite material. However, this method suffers from problems such as long production cycles and high labor costs in actual production, and it is not suitable for achieving curved surface shaping of planar hollow fabrics prepared using existing loom technology.

[0005] Therefore, there is an urgent need for a new tooling and method that can achieve high-precision curved surface forming, be compatible with existing planar hollow fabrics, have strong process adaptability, and effectively protect the fiber reinforcement. Summary of the Invention

[0006] To address one or more technical problems existing in the prior art, the present invention provides a molding fixture and molding method for curved hollow fabric composite materials. The molding fixture provided by the present invention produces hollow curved composite materials with higher molding accuracy, better curved surface effect, and fewer surface defects, and can be applied to molding complex curved surface structure composite materials.

[0007] The present invention provides a molding tooling for curved hollow fabric composite materials in a first aspect, comprising a mandrel array, the mandrel array being used to insert into the cavity of a hollow fabric preform to shape the hollow fabric preform; the mandrel array having a spatial curved surface structure consistent with the target surface in the assembled state.

[0008] Preferably, the mandrel array is prepared by one or more of the following methods: 3D printing, continuous cutting of curved panels with the same shape, and casting; and / or The mandrel array is made of one or more of the following materials: metallic materials, inorganic non-metallic materials, solvent-soluble materials, thermally decomposable materials, photolytic materials, and shape memory polymers.

[0009] Preferably, the mandrel array includes at least one mandrel array unit, and the mandrel array unit includes at least one mandrel; One end of the mandrel is a free end, and the other end is a drawing end; the drawing end is used to connect with a drawing tool to realize the demolding of the mandrel during the composite material molding process.

[0010] Preferably, the pull-out end of the mandrel array is provided with an integrated pull-out structure.

[0011] Preferably, the free end is one or more of a hemispherical shape and a parabolic cone shape; and / or The drawing end is provided with one or more of the following structures: threaded structure, through hole structure, and snap-fit ​​structure.

[0012] In a second aspect, the present invention provides a method for molding a curved hollow fabric composite material, which is achieved using the molding tooling described in the first aspect, and includes the following steps: S1. Provide hollow fabric preforms; S2. After shaping the hollow fabric preform using the molding fixture, impregnate it with resin; or... The molding tooling is used to shape the resin-impregnated hollow fabric preform. S3. The hollow fabric preform treated in S2 is cured and demolded to obtain a curved hollow fabric composite material.

[0013] Preferably, the method for preparing the hollow fabric preform is selected from one or more of weft knitting, warp knitting, weaving, and sewing.

[0014] Preferably, the hollow fabric preform is a planar hollow preform or a curved hollow preform.

[0015] Preferably, the demolding method is selected from one or more of drawing, dissolution, thermal decomposition, photolysis, and thermal deformation.

[0016] In a third aspect, the present invention provides a curved hollow fabric composite material, which is prepared by the molding tooling described in the first aspect or the molding method described in the second aspect.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: The molding fixture provided by this invention uses a mandrel array as an inner mold to shape hollow fabrics. The mandrel array has a spatial curved surface structure consistent with the target shape, and the surface transition is smooth. This allows for active and precise control of the cavity height and curved surface morphology of the hollow fabric, avoiding uncontrollable torsional deformation that can damage the fiber fabric during passive deformation using a mold. This maximizes the protection of the structural integrity and mechanical properties of the hollow fabric. Furthermore, the mandrel array structure design makes the demolding process more efficient and controllable, effectively reducing secondary damage to the internal structure of the cured composite material. The hollow curved surface composite material produced by the molding fixture provided by this invention has higher molding precision, better curved surface effect, and fewer surface defects, and can be applied to molding composite materials with complex curved surface structures.

[0018] The molding tooling provided by this invention has strong process adaptability and can be applied to various types of hollow fabrics (warp knitting, weft knitting, woven, sewn hollow fabrics, etc.) and hollow fabrics with different shapes (flat and curved hollow fabrics). It can significantly improve production efficiency, reduce costs, and has good application prospects. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This invention provides a mandrel array unit; Figure 2 This invention provides a mandrel array.

[0021] Figure label: 1-Mandrel array; 11-Mandrel array unit; 111-Mandrel; 112-Free end; 113-Pull-out end. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a molding fixture for curved hollow fabric composite materials, such as... Figure 1-2 As shown, it includes a mandrel array 1, which is used to insert into the cavity of the hollow fabric preform to shape the hollow fabric preform; the mandrel array 1 has a spatial curved surface structure consistent with the target surface in the assembled state.

[0024] The molding fixture provided by this invention uses a mandrel array as an inner mold to shape hollow fabrics. The mandrel array has a spatial curved surface structure consistent with the target shape, and the surface transition is smooth. This allows for active and precise control of the cavity height and curved surface morphology of the hollow fabric, avoiding uncontrollable torsional deformation that can damage the fiber fabric during passive deformation using a mold. This maximizes the protection of the structural integrity and mechanical properties of the hollow fabric. Furthermore, the mandrel array structure design makes the demolding process more efficient and controllable, effectively reducing secondary damage to the internal structure of the cured composite material. The hollow curved surface composite material produced by the molding fixture provided by this invention has higher molding precision, better curved surface effect, and fewer surface defects. It can be applied to molding composite materials with complex curved surface structures (complex irregular curved surfaces).

[0025] The molding tooling provided by this invention has strong process adaptability and can be applied to various types of hollow fabrics (warp knitting, weft knitting, woven, sewn hollow fabrics, etc.) and hollow fabrics with different shapes (planar and curved hollow fabrics). It can significantly improve production efficiency, reduce costs, and has good application prospects. For example, it can be applied to various integrated radar antenna covers, buildings, equipment, vehicles, weight-reducing shells, and other fields.

[0026] According to some preferred embodiments, the preparation method of the mandrel array 1 is one or more of 3D printing, continuous cutting of curved panels with the same shape, and casting.

[0027] This invention allows for the selection of mandrel array fabrication methods based on actual conditions. Fabrication of the mandrel array using 3D printing includes: determining the spatial structure of the mandrel array based on a three-dimensional model of the target composite material and according to the cavity dimensions of the target composite material, followed by 3D printing. Fabrication of the mandrel array using a continuous cutting method with a curved surface of the same shape as the target composite material includes: using a substrate with a curved surface of the same shape as the target composite material, and continuously cutting at positions corresponding to the cavities of the target composite material according to the cavity dimensions of the target composite material, resulting in a mandrel array with a spatial curved surface structure consistent with the surface of the target composite material. The cutting methods include, but are not limited to, wire cutting, water jet cutting, laser cutting, and ultrasonic vibration cutting; the appropriate cutting method is selected based on the hardness and strength of the substrate.

[0028] According to some preferred embodiments, the material of the mandrel array 1 is one or more of the following: metallic materials, inorganic non-metallic materials, solvent-soluble materials, thermally decomposable materials, photolytic materials, and shape memory polymers.

[0029] According to some preferred embodiments, the mandrel array 1 includes at least one mandrel array unit 11, and the mandrel array unit 11 includes at least one mandrel 111; One end of the mandrel 111 is a free end 112, and the other end is a drawing end 113; the drawing end 113 is used to connect with a drawing tool to realize the demolding of the mandrel during the composite material molding process.

[0030] According to some preferred embodiments, the pull-out end 113 of the mandrel array unit 11 is provided with an integrated pull-out structure.

[0031] In some preferred embodiments of the present invention, each mandrel array unit includes only one mandrel, both ends of which are free ends. One end of the mandrel serves as the insertion end before or during molding (ensuring it can be smoothly inserted into the cavity of the hollow fabric). To facilitate insertion, the insertion end is machined into a hemispherical or parabolic conical head; the other end is provided with a pull-out structure, serving as a pull-out end during demolding, which can be connected to a pull-out tool to achieve demolding of the mandrel during the composite material molding process.

[0032] In some preferred embodiments of the present invention, each mandrel array unit includes multiple mandrels, one end of each mandrel being a free end, serving as an insertion end before or during molding. For ease of insertion, the mandrels are machined into hemispherical or parabolic conical heads. The other end of the multiple mandrels in the mandrel array unit is an integrated pull-out structure, serving as a pull-out end during demolding, which can be connected to a pull-out tool to achieve one-time demolding of multiple mandrels or the entire mandrel array during composite material molding.

[0033] In some preferred embodiments of the present invention, the mandrel array includes one or more mandrel array units with their free ends facing the same direction. In this case, each mandrel array unit is inserted along the same direction of the fabric cavity channel to form a mandrel array that conforms to the target profile.

[0034] In some other preferred embodiments of the present invention, the mandrel array includes multiple mandrel array units with their free ends facing different directions. In this case, some mandrel array units are inserted along a first direction of the fabric cavity channel, and other mandrel array units are inserted along a second direction of the fabric cavity channel, ultimately forming a mandrel array that conforms to the target profile. This method can achieve simultaneous pull-out demolding in two directions, resulting in higher efficiency.

[0035] According to some preferred embodiments, the free end 112 is one or more of a hemispherical shape and a parabolic cone shape.

[0036] According to some preferred embodiments, the pull-out end 113 is provided with one or more of the following: threaded structure, through-hole structure, and snap-fit ​​structure.

[0037] The present invention provides a method for molding curved hollow fabric composite materials in a third aspect, which is achieved by the molding tooling described in the first aspect, and includes the following steps: S1. Provide hollow fabric preforms; S2. After shaping the hollow fabric preform using the molding fixture, impregnate it with resin; or... The molding tooling is used to shape the resin-impregnated hollow fabric preform. S3. The hollow fabric preform treated in S2 is cured and demolded to obtain a curved hollow fabric composite material.

[0038] In the molding process of the curved hollow fabric composite material of this invention, before shaping the hollow fabric preform using molding fixtures, a pretreatment of the mandrel array is included. Specifically, this includes labeling, cleaning, and applying release agent and release wax to the mandrels in the array. Because the curvature of individual mandrels differs, each mandrel in the array is numbered and marked according to the transition sequence of the curved surface to ensure the accuracy of the insertion order. After numbering, the surface of the mandrels is wiped with alcohol 1-2 times to remove any foreign matter and ensure surface cleanliness. Then, release agent and release wax are applied 3-4 times. When the mandrel mold is used for the first time, release agent is evenly applied to the surface of the mandrels 8-10 times using a soft cloth wiping method or immersion method. After the release agent dries, release wax is applied 3-4 times.

[0039] The molding process of the curved hollow fabric composite material of the present invention can be carried out in the following two ways: The first method involves shaping the hollow fabric preform using molding fixtures, impregnating it with resin, and finally curing and demolding. Specifically: First, the hollow fabric is cut to the required size and laid flat on a platform mold. A scraper is used to evenly smooth the fabric surface against the direction of the pile warp, observing the core's condition to ensure the pile warp core stands upright and the cavity pathways formed by the pile warp are clear. Then, utilizing the fabric's flexibility, mandrels are slowly inserted one by one into the cavities of the hollow fabric. After the entire mandrel array is inserted, the support and shaping effect of the mandrel array forms a curved hollow fabric structure with a spatial curved surface consistent with the target profile. The shaped hollow fabric preform is transferred to a rigid mold with a corresponding profile. Before impregnation with resin, other layers can be applied to the surface of the hollow fabric as needed. Then, composite molding methods such as vacuum flow technology, hand lay-up technology, autoclave technology, and molding technology are used to fully impregnate the shaped curved hollow fabric preform with resin. Finally, following the resin curing procedure, the resin-impregnated curved hollow fabric preform (hollow fabric and mandrel array) is subjected to bag-press heating curing or male-female mold-jointing heating curing, and then demolded to obtain the curved hollow fabric composite material.

[0040] The second method involves first impregnating the hollow fabric preform with resin, then shaping the resin-impregnated preform using molding fixtures, and finally curing and demolding. Specifically: First, the hollow fabric preform is cut to the required size and laid flat on a mold platform. A scraper is used to evenly smooth the fabric surface against the direction of the pile warp, observing the core's condition to ensure the pile warp core stands upright and the cavity pathways formed by the pile warp are clear. Then, a composite molding method using vacuum flow (vacuum breaking) technology, hand lay-up technology, and impregnation technology is employed to fully impregnate the hollow fabric preform with resin. After removing related auxiliary materials, the impregnated hollow fabric undergoes a secondary finishing process to ensure the core stands upright and the cavity pathways formed by the pile warp are clear. Mandrels are then slowly inserted one by one into the cavities of the hollow fabric. After the entire mandrel array is inserted, the support and shaping effect of the mandrel array forms a curved hollow fabric with a consistent spatial curved surface structure. Finally, the shaped curved hollow fabric preform is transferred to a rigid mold with a corresponding surface. Other layers (resin-impregnated fiber fabric layers) can also be laid on the surface of the shaped curved hollow fabric as needed. According to the resin curing procedure, the resin-impregnated curved hollow fabric preform is bag-pressed and heated for curing or molded for curing. After demolding, the curved hollow fabric composite material is obtained.

[0041] Both of the above molding methods require the use of metal mold clamping or a combination of a rigid mold on one side and bag pressing to achieve overall height control, and the use of the support and shaping effect of the mandrel array to control the cavity size and overall shape.

[0042] According to some preferred embodiments, the method for preparing the hollow fabric preform is selected from one or more of weft knitting, warp knitting, weaving, and sewing.

[0043] According to some preferred embodiments, the hollow fabric preform is a planar hollow preform or a curved hollow preform.

[0044] According to some preferred embodiments, before shaping the hollow fabric preform using molding fixtures, the hollow fabric is pre-treated to ensure that its cavity pathways are clear. Specifically, a scraper is used to evenly flatten the fabric surface in the opposite direction of the pile warp, and the core condition is observed to ensure that the pile warp core stands upright as a whole and that the cavity pathways formed by the pile warp are clear.

[0045] According to some preferred embodiments, the impregnation resin is applied using one or more of the following processes: vacuum flow process, hand lay-up process, autoclave process, and molding process.

[0046] According to some preferred embodiments, the curing is performed by bag pressure heating curing or male-female mold bonding heating curing.

[0047] According to some preferred embodiments, the demolding method is selected from one or more of drawing, dissolution, thermal decomposition, photolysis, and thermal deformation.

[0048] When the pulling end is threaded or has a hole, demolding is performed by pulling. Specifically, the thread or hole at the pulling end of the mandrel is connected by a lifting eye nut or U-shaped clip. Then, mechanical or manual pulling is used to apply force slowly and evenly to pull out the mandrel one by one to complete the demolding.

[0049] When the pull-out end is a single or integral snap-fit, after installing the corresponding snap-fit, apply force slowly and evenly using mechanical or manual pulling to pull out the mandrel one by one or as a whole to complete the demolding.

[0050] When the mandrel is a solvent-soluble material, the corresponding solvent is applied to dissolve the mandrel, thus completing the demolding process.

[0051] When the mandrel is made of a thermally decomposable or photolytic material, the mandrel is decomposed by applying the appropriate temperature / light, thus completing the demolding process.

[0052] In a third aspect, the present invention provides a curved hollow fabric composite material, which is prepared by the molding tooling described in the first aspect or the molding method described in the second aspect.

[0053] To more clearly illustrate the technical solution and advantages of the present invention, the present invention will be further described below in conjunction with the embodiments. However, the scope of protection of the present invention is not limited to the following embodiments.

[0054] Example 1 A molding tooling for curved hollow fabric composite materials includes a mandrel array, which has a spatial curved surface structure consistent with the target surface in the assembled state; the mandrel array 1 includes two mandrel array units 11, each mandrel array unit 11 includes multiple mandrels 111 with a spatially curved shape; one end of the mandrel array unit 11 is a free end 112, and the other end is a pull end 113; the free end 112 is hemispherical, and the pull end is an integral pull structure.

[0055] A method for manufacturing a molding fixture for curved hollow fabric composite materials includes: using laser cutting to continuously cut a mandrel array with dimensions of 4 (width) * 4.4 (height) mm at corresponding positions on a 304 stainless steel substrate with the same shape but different curved surface as the target. The length is slightly larger than the product size. After cutting, the insertion end of the mandrel array is machined into a hemispherical shape, and the pull-out end is threaded with an M3 external thread.

[0056] A method for molding a curved hollow fabric composite material, achieved by employing the aforementioned molding fixture, includes: (1) Prepare hollow fabric preforms Select a 5mm thick flat woven hollow fiberglass fabric (with a cavity warp height of 4.4mm, an upper and lower layer thickness of 0.3mm each, and a lateral spacing of 4mm between the cavities formed by the warp) produced by Nanjing Fiberglass Research and Design Institute Co., Ltd. Lay the cut flat hollow fabric flat on a platform mold, then use a scraper to evenly smooth the fabric surface against the direction of the warp fall, observing the core condition to ensure that the warp core stands upright and the cavity pathways formed by the warp are clear.

[0057] (2) Processing and preparation of mandrel array tooling Wipe the mandrel surface with alcohol 1-2 times to remove foreign matter and ensure a clean surface. Then, apply a release agent evenly to the mandrel surface 8-10 times with a soft cloth. After the release agent dries, apply release wax 3-4 times. After processing, number the mandrel array from left to right according to the target surface transition sequence, and mark the number on the mandrel drawing end.

[0058] (3) Shaping of curved hollow fabric preforms According to the numbering sequence of the mandrels in the mandrel array tooling, the mandrels are slowly inserted one by one into the cavity of the corresponding position of the fabric, and with the support and shaping effect of the mandrel array, a curved hollow fabric preform is obtained.

[0059] (4) Molding of curved hollow fabric composite materials First, the prepared curved hollow fabric preform is placed in a mold. Local wrinkles on the fabric surface are smoothed using a scraper or manual pulling. Vacuum-guided molding is then used to fully impregnate the curved hollow fabric preform with resin. Next, the entire preform is bagged and heated for curing. After curing, the vacuum bag and vacuum guide material are removed sequentially. An M3 eyelet nut is used to connect the threads of the mandrel pulling end. Mechanical pulling is then performed with uniform and slow force to pull out the mandrel array units one by one, thus obtaining the curved hollow fabric composite material blank. Finally, the blank is trimmed to obtain the curved hollow fabric composite material.

[0060] It should be noted that the above embodiments are only for illustrating the technical solution of the present invention and are not intended to limit it. The present invention can select a corresponding mandrel array based on the design surface of the target. If the target is a complex irregular curved surface, the irregular curved surface can be divided into multiple parts, and composite materials can be formed separately for each part. Finally, the entire part is molded together, and a continuous inner and outer skin is prepared at the seam connection. Specifically: First, each part is shaped using different mandrel array tooling to obtain a preform of a hollow fabric on a local curved surface. The obtained preforms of hollow fabric on local curved surfaces are then impregnated with resin, cured, and demolded to obtain a composite material of hollow fabric on a local curved surface. Then, the composite materials of hollow fabric on each local curved surface are molded together, and a fiber fabric impregnated with resin is laid at the seam connection. After heating and curing, a continuous inner and outer skin can be prepared. Finally, demolding yields the composite material of hollow fabric on an irregular curved surface.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A forming tool for a curved hollow fabric composite material, characterized in that The core rod array is used for inserting into the cavity inside the hollow fabric preform to shape the hollow fabric preform; the core rod array has a spatial curved surface structure consistent with a target profile in an assembled state.

2. The forming tool of claim 1, wherein The preparation method of the core rod array is one or more of 3D printing, continuous cutting with an outer curved surface plate, and casting molding; and / or The material of the core rod array is one or more of a metal material, an inorganic non-metal material, a solvent-soluble material, a thermal decomposition material, a photodecomposition material, and a shape memory polymer.

3. The forming tool of claim 1, wherein The core rod array includes at least one core rod array unit, and the core rod array unit includes at least one core rod. One end of the core rod is a free end, and the other end is a pulling end; the pulling end is used for connecting with a pulling tool to realize demolding of the core rod in a composite material forming process.

4. The forming tool of claim 3, wherein The pulling end of the core rod array is provided with an integrated pulling structure.

5. The forming tool of claim 3, wherein The free end is one or more of a hemispherical shape and a parabolic conical shape; and / or The pulling end is provided with one or more of a threaded structure, a through-hole structure, and a buckle structure.

6. A method of forming a curved hollow fabric composite material, characterized by, The forming tool of any one of claims 1-5 is realized, including the following steps: S1. providing a hollow fabric preform; S2. impregnating resin after shaping the hollow fabric preform by using the forming tool; or, shaping the hollow fabric preform impregnated with resin by using the forming tool; S3. curing and demolding the hollow fabric preform after S2 processing to obtain a curved surface hollow fabric composite material.

7. The molding method according to claim 6, characterized by The preparation method of the hollow fabric preform is selected from one or more of weft knitting, warp knitting, weaving, and sewing.

8. The molding method according to claim 6, characterized by The hollow fabric preform is a planar hollow preform or a curved surface hollow preform.

9. The molding method according to claim 6, wherein The demolding mode is selected from one or more of pulling, dissolution, thermal decomposition, photodecomposition, and thermal induced deformation.

10. A curved hollow fabric composite material, characterized by, The forming tool of any one of claims 1-5 or the forming method of any one of claims 6-9 is used.

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