JP7108134B2 - Method for manufacturing fiber-reinforced resin fastener - Google Patents

Description

The present invention relates to a method for manufacturing a fiber-reinforced resin fastener and a fiber-reinforced resin fastener.

Conventionally, metal bolts, resin bolts, and the like have been used as fasteners. Metal bolts are prone to corrosion and have the disadvantage of being heavy, while resin bolts do not corrode, but have the disadvantage of insufficient strength.

Therefore, in recent years, bolts made of carbon fiber reinforced plastic (CFRP, hereinafter referred to as CFRP) have been used as fasteners that are resistant to corrosion, lightweight, and have the same strength as metal bolts. Fasteners such as nuts and bolts have been manufactured. Fasteners made of CFRP have both corrosion resistance and high strength, so they can be used under severe usage conditions such as in places where they are easily exposed to water or rain.

A manufacturing method generally known as a method for manufacturing such CFRP fasteners includes CFRP impregnated with resin while arranging carbon fiber long fibers contained in carbon fiber reinforced resin in a predetermined direction. There is a method of manufacturing a CFRP bolt by preparing a CFRP round bar and threading the peripheral surface of the CFRP round bar by cutting to form a screw thread.

Further, as in the method described in Patent Document 1, a thermoplastic carbon fiber reinforced resin in which reinforced carbon fiber is impregnated with a thermoplastic resin, that is, a round bar made of CFRTP (Carbon Fiber Reinforced Thermal Plastic) is placed in a heated mold. It is also known to manufacture bolts made of CFRTP by hot-pressing with .

However, in the method of manufacturing bolts by threading a CFRP round bar by cutting, it is necessary to perform cutting for each bolt, which is inferior in mass productivity. In addition, since the CFRP round bar usually has reinforcing fibers extending in the longitudinal direction of the round bar, the reinforcing fibers on the peripheral surface of the round bar are cut when threading is performed to manufacture the bolt. It is difficult to manufacture high strength bolts.

In addition, even in the method of manufacturing a bolt by hot-press molding a CFRP round bar as described in Patent Document 1, the reinforcing fibers are suddenly deformed and cut at the threaded portion, so this manufacturing method It is difficult to improve the strength of bolts.

Japanese Patent Publication No. 7-86367

SUMMARY OF THE INVENTION An object of the present invention is to provide a fiber-reinforced resin fastener which is excellent in mass productivity and capable of producing a high-strength fastener.

In order to solve the above problems, the method for manufacturing a fastener made of fiber-reinforced resin according to the present invention is a method for manufacturing a fastener made of fiber-reinforced resin, wherein the spread reinforcing fibers are oriented in a predetermined direction. A preparation step of preparing a plurality of chopped materials in which the fiber reinforced resin sheet impregnated with the thermoplastic resin is shredded to a predetermined size, and preparing a chopped sheet by arranging and uniting the plurality of chopped materials in a plane. A chopped sheet producing step, a step of filling the chopped sheet into a mold, and a shape of the fastener is formed by pressing the chopped sheet inside the mold while the mold is heated. and a pressurizing step.

1 is a perspective view of a bolt, a nut, and a washer as specific examples of a fiber-reinforced resin fastener manufactured by the manufacturing method of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a flowchart which shows a series of flows of the manufacturing method concerning embodiment of the manufacturing method of the fastener made from a fiber reinforced resin of this invention. FIG. 4 is an explanatory view showing a process of manufacturing a CFRTP sheet as an intermediate material for manufacturing a CFRTP chopped material that is a material for fasteners. FIG. 3 is an explanatory view showing a process of continuously chopping a CFRTP sheet to produce a CFRTP chopped material. 1 is an exploded perspective view of a mold used in the manufacturing method of the present invention; FIG. FIG. 4 is an explanatory view showing a charging step of charging a plurality of chopped materials or chopped sheets into a mold in the manufacturing method of the present invention; FIG. 4 is an explanatory view showing a process of pushing chopped material into a mold in a charging step; It is explanatory drawing which shows the pressurization process which pressurizes the chopped material in the manufacturing method of this invention inside a metal mold|die, and shape|molds the bolt which is a fastener. It is explanatory drawing which shows the process which disassembles a metal mold|die after a pressurization process. It is explanatory drawing which shows the process which takes out the molded bolt from a metal mold|die. It is explanatory drawing which shows the chopped sheet production process which produces a chopped sheet by impregnating a thermoplastic film with the chopped material which is a modification of the manufacturing method of this invention. 5 is a cross-sectional view of a bolt of Comparative Example 1; FIG. (a) is a 5 mm × 20 mm rectangular chopped material (thickness 50 μm), a PA6 film is used as a matrix (base material), and the fiber volume content of the carbon fiber is 53%. FIG. 8B is a cross-sectional view of a bolt, and FIG. 8B is a cross-sectional view of a bolt of Comparative Example 3; FIG. 4 is a cross-sectional view showing another example of a mold that can be used in the manufacturing method of the present invention; FIG. 4 is a cross-sectional view showing another example of a mold that can be used in the manufacturing method of the present invention; FIG. 4 is a cross-sectional view showing another example of a mold that can be used in the manufacturing method of the present invention; FIG. 4 is a cross-sectional view showing another example of a mold that can be used in the manufacturing method of the present invention; FIG. 4 is an explanatory diagram for evaluating the degree of fiber filling when observing a cross section of a fiber-reinforced resin bolt.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a bolt B, a nut N, and a washer W as specific examples of the fiber-reinforced resin fastener manufactured by the manufacturing method of the present invention. Fasteners such as these bolts B are manufactured by hot-press molding chopped materials obtained by shredding fiber-reinforced resin sheets in which reinforcing fibers are impregnated with a thermoplastic resin.

That is, the method for manufacturing a fastener made of fiber-reinforced resin according to this embodiment includes:
(A) a preparation step of preparing a plurality of chopped materials obtained by chopping a fiber-reinforced resin sheet impregnated with a thermoplastic resin into a predetermined size with the spread reinforcing fibers oriented in a predetermined direction;
(B) an injection step of injecting a plurality of chopped materials into the mold;
(C) a pressurizing step of forming the shape of the fastener by pressurizing the chopped material inside the die while the die is heated.

As the reinforcing fibers, those obtained by opening reinforcing fiber bundles such as carbon fiber bundles, glass fiber bundles, aramid fiber bundles, and ceramic fiber bundles (that is, fiber bundles that are separated and spread into a belt shape) are used. In particular, carbon fiber bundles are preferable in terms of strength and corrosion resistance. Among carbon fibers, PAN (polyacrylonitrile)-based carbon fibers are particularly preferable in that they have higher strength than other materials.

Thermoplastic resins include polypropylene, polyethylene, polystyrene, polyamide (nylon 6, nylon 66, nylon MXD6, nylon 9T, nylon 11, nylon 12, etc.), polyacetal, polycarbonate, acrylonitrile-butadiene-styrene copolymer (ABS), Polyethylene terephthalate, polybutylene terephthalate, polyetherimide, polyether sulfone, polyphenylene sulfide, polyether ketone, polyether ether ketone, polyether ketone ketone, fluorine-based resin, and the like are used. In addition, two or more of these thermoplastic resins may be mixed to form a polymer alloy.

In addition, thermoplastic resins are used in the form of sheets when fabricating fiber-reinforced resin sheets, but are used in the form of woven sheet materials or knitted sheet materials composed of fibers made of thermoplastic resin materials, as well as non-woven fabrics. You may

Specifically, the method for manufacturing a fastener made of fiber-reinforced resin according to the present embodiment is executed according to the procedure shown in the flowchart of FIG. 2 . Here, the bolt B will be described as an example of the manufactured fastener.

First, a sheet made of thermoplastic carbon fiber reinforced resin (CFRTP) (hereinafter referred to as a CFRTP sheet) is manufactured as a fiber reinforced resin sheet (S1 in FIG. 2).

A CFRTP sheet is continuously manufactured using, for example, a sheet manufacturing apparatus for manufacturing a CFRTP sheet as shown in FIG.

The sheet manufacturing apparatus shown in FIG. 3 is an apparatus for continuously manufacturing a CFRTP sheet S using a carbon fiber bundle F1 as reinforcing fibers and a thermoplastic resin sheet R1.

More specifically, the sheet manufacturing apparatus includes a plurality of pairs of heating rolls 1 (two pairs in FIG. 3) arranged in a vertical direction, and a group of heating rolls 1 positioned below the group of heating rolls 1 and positioned above and below each other. A plurality of pairs of cooling rolls 2 (two pairs in FIG. 3) arranged side by side in the vertical direction, and a pair of endless belts respectively wound around two heating rolls 1 and two cooling rolls 2 arranged vertically. 3, a pair of pull-out rolls 4 positioned below the pair of endless belts 3, and a bobbin 5 for winding.

Also, although not shown, a fiber spreading mechanism is provided in the vicinity of the uppermost heating roll 1 for continuously forming the spread fibers F2 by spreading the carbon fiber bundles F1 into a belt shape. there is As the fiber spreading mechanism, for example, any mechanism can be used as long as it is capable of spreading the fiber bundle and flattening the long fibers so as to extend in the same direction. Various mechanisms are used, such as a mechanism for applying and spreading.

The manufacturing apparatus shown in FIG. 3 manufactures a CFRTP sheet S by sandwiching a thermoplastic resin sheet R1 with spread fibers F2 from both sides.

Two pairs of heating rolls 1 are each heated by an electric heater or a heating fluid. The two pairs of heating rolls 1 heat the spread fiber F2 and the thermoplastic resin sheet R1 while sandwiching the spread fiber F2 and the thermoplastic resin sheet R1 in a state of being overlapped with each other via the endless belt 3, thereby heating the spread fiber F2. R1 is continuously impregnated.

The plurality of pairs of cooling rolls 2 are cooled by a cooling fluid or the like. A plurality of pairs of cooling rolls 2 sandwich the thermoplastic resin sheet R1 impregnated with the spread fibers F2 from both sides through the endless belt 3 to cool and feed the CFRTP sheet with a predetermined thickness. Mold S continuously.

A pair of drawing rolls 4 continuously draws down the manufactured CFRTP sheet S while applying tension thereto.

A winding bobbin 5 is rotated by a drive source such as a motor, and sequentially winds the CFRTP sheet S pulled out by the pair of pull-out rolls 4 to form a roll-shaped CFRTP sheet S.

A CFRTP sheet can also be manufactured by a method of winding a thermoplastic resin sheet and spread reinforcing fibers together in a predetermined direction without using the endless belt 3 shown in FIG.

Next, as shown in FIG. 4, the produced CFRTP sheet S is shredded to produce chopped material C (S2 in FIG. 2).

Specifically, as shown in FIG. 4, while pulling out the rolled CFRTP sheet S, a cutter having a large number of blades arranged at regular intervals in the width direction of the sheet S is used in section I. is used to continuously cut the sheet S longitudinally into a number of strips having a predetermined width. Next, in section II, the sheet S cut into strips is cut into predetermined lengths by using a rotary cutter or the like having a blade extending in the width direction of the sheet S. As shown in FIG. As a result, chopped material C having a predetermined size can be continuously produced.

The size of the chopped material C is selected in consideration of various conditions such as the size of the bolt B to be molded, the size of the inlet 12 of the mold 11 to be described later, and shapeability during molding.

Next, in the charging step (B), a large number of chopped materials C are charged into the mold 11 through the charging port 12 while the mold 11 shown in FIGS. 5 and 6 is heated.

The mold 11 may have any configuration as long as it can perform pressure molding while heating the chopped material C inside the mold 11. For example, the mold 11 is composed of split molds 11a and 11b divided in the vertical direction. An inlet 12 is formed at the upper end of the mold 11 . A space (cavity) 13 corresponding to the shape of the bolt B (fastener) to be molded is formed inside the mold 11 . The space 13 communicates with the inlet 12 . The space 13 is composed of a shaft side space 13a corresponding to the shape of the shaft portion on which the external thread of the bolt B is formed, and a head side space 13b corresponding to the shape of the hexagonal head of the bolt B. have. Therefore, an internal thread is formed on the inner surface of the shaft-side space 13a, and a hollowed recess in the shape of a hexagonal column is formed in the head-side space 13b.

The two split molds 11a and 11b are joined together with their mating surfaces 14 in contact with each other to form a space 13 corresponding to the shape of the bolt B. As shown in FIG. Specifically, the two split molds 11a and 11b are connected by inserting a bolt into a through hole 15 formed horizontally in the two split molds 11a and 11b and fastening a nut to the bolt.

The mold 11 shown in FIGS. 5 and 6 has two vertically split molds 11a and 11b, and one through hole 12 is formed in the space portion 13 on the bolt head side. However, in the manufacturing method of the present invention, the structure of the mold is not limited, and various shapes of molds can be employed.

For example, as a modification of the present invention, a through-hole 21c communicating with a shaft-side space 21b is formed in a bolt-shaped space 21a like a mold 21 shown in FIG. The structure may be such that the pressure P can be applied from the hole 21c into the space 21a.

As another modified example, a mold 22 shown in FIG. A structure in which a through-hole 22e communicating with the section-side space 22d may be formed. In the structure of FIG. 15, it is possible to apply pressure P into the space 22a from two through holes 22c and 22e.

As still another modification, a horizontally split mold 23 shown in FIG. 16 may be used. The mold 23 has an upper mold 23a and a lower mold 23b as two split molds that can be joined together on a horizontally extending joint surface 23d. A bolt-shaped space 23c is formed by combining the upper mold 23a and the lower mold 23b.

As a further modified example of the horizontally split mold, two through holes 24e and 24f may be formed like the horizontally split mold 24 shown in FIG. In the structure of FIG. 17, a bolt-shaped space 24c is formed by aligning the upper die 24a and the lower die 24b at a horizontal mating surface 24d. Of the space 24c, the shaft-side space 24c1 communicates with the through-hole 24e, and the head-side space 24c2 communicates with the through-hole 24f. A pressure P can be applied to the space 24c from two through holes 24e and 24f.

The method of heating the mold 11 is not particularly limited in the present invention, as long as the method can heat the chopped material C to a melting temperature (for example, 250 to 300° C. around 270° C.). For example, in addition to heating by infrared rays or a burner, induction heating may be used.

The method of charging the chopped material C into the mold 11 is not particularly limited in the present invention, and a predetermined amount of chopped material C may be charged manually or mechanically using a charging device.

When the chopped materials C are fed, the direction in which the carbon fibers inside the chopped materials C extend is not aligned, so that a large number of chopped materials C are oriented in random directions (that is, the orientation of the chopped materials C is random. ), it is possible to ensure the random orientation of the bolt B after molding. Therefore, the size of the chopped materials C should be such that a large number of chopped materials C are oriented in random directions when the chopped materials C are loaded, taking into account the opening area of the inlet 12 and the volume and shape of the space 13. It is preferably set so that

Next, as shown in FIG. 7, the chopped material C is pushed into the mold 11 (S4 in FIG. 2). Specifically, the pressing rod 16 is inserted into the inlet 12 of the mold 11, and the chopped material C introduced into the mold 11 is pushed into the cavity 13 inside the mold 11 by the pressing rod 16. . As a result, the chopped material C is evenly dispersed and packed inside the space portion 13 . When the chopped material C is pushed by the pressing rod 16, the chopped material C may be pushed through a cover having substantially the same size as the inlet 12, or may be directly pushed by the lower end surface of the pushing rod 16. If the chopped material C does not leak when it is pushed in, it can be pushed in by an appropriate method. The step of pushing the chopped material C into the mold 11 (S4) is not essential in the manufacturing method of the present invention and may be omitted.

After that, as shown in FIG. 8, the hot press machine 17 is used to press the chopped material C inside the mold 11 (S5 in FIG. 2). The hot press machine 17 has a pedestal 17a and a pressurizing part 17b arranged above the pedestal 17a. The pedestal 17a has a heater and heats the mold 11 placed on the pedestal 17a. With the mold 11 placed on the pedestal 17a, the pressure part 17b is lowered, and the pressure part 17b presses the heated chopped material C inside the mold 11 via the pressure rod 16. FIG. As a result, a large number of chopped materials C are melted and deformed inside the space 13 under high temperature and high pressure inside the mold 11 to be molded into the shape of the bolt B. As shown in FIG.

After forming the bolt B, as shown in FIG. 9, the mold 11 is disassembled into two split molds 11a and 11b (S6 in FIG. 2).

Finally, as shown in FIG. 10, the bolt B is removed from the space 13 of one of the split molds 11a of the metal mold 11 (S7 in FIG. The process ends.

The fiber-reinforced resin fastener such as the bolt B according to the embodiment of the present invention is manufactured by the above-described manufacturing method, and the thermoplastic resin and the reinforcement impregnated in the thermoplastic resin in a state in which the orientation is not specified. A fiber-reinforced resin fastener made of fiber, wherein the fiber length of the reinforcing fiber is in the range of 5 to 100 mm, preferably 5 to 40 mm, more preferably 5 to 20 mm. The volume content of the reinforcing fibers in the thermoplastic resin can be in the range of 30-80%, preferably 30-60%.

In the above fastener, the reinforcing fibers are impregnated with the thermoplastic resin in a state in which the orientation of the reinforcing fibers is not specified, that is, in a state having random orientation. It is within the range and the volume content in the thermoplastic resin is within the range of 30 to 80%, so that it is excellent in mass productivity and has high strength.

As shown in the examples below, the above conditions are such that the fiber length of the reinforcing fiber is 5 to 100 mm, preferably 5 to 40 mm, and more preferably about 5 to 20 mm. If the bolt can be manufactured and the volume content of the reinforcing fiber is within the range of 30 to 80%, preferably 30 to 60%, it is possible to ensure high strength and formability of the bolt. based on a point.

(Features of this embodiment)
In the method of manufacturing a fastener made of fiber-reinforced resin according to the present embodiment, as shown in FIGS. A plurality of chopped materials C are prepared by chopping a fiber reinforced resin sheet such as a CFRTP sheet S impregnated with a thermoplastic resin R1 into pieces of a predetermined size. Then, a plurality of chopped materials C are put into the mold 11 and pressure-molded while the chopped materials are heated. The chopped material C has good formability, that is, good conformability to the shape of the cavity of the mold.

That is, the fiber-reinforced resin fastener manufactured by the manufacturing method of the present embodiment can be mass-produced by hot press molding as in the above-described pressure step (C). Further, if the used fastener is reheated to melt the thermoplastic resin, it can be reused for other purposes.

Moreover, since the group of the plurality of chopped materials, which are the materials of the fastener, have random orientation, there is little possibility that the reinforcing fibers contained in the chopped materials will be cut even if pressure molding is performed. Further, since the fastener after molding also maintains a constant fiber length, the strength of the fastener (for example, torsional strength, shear strength, etc.) can be improved. As a result, it becomes possible to manufacture a fiber-reinforced resin fastener having excellent mass productivity and high strength.

Next, as an example of the present invention, the strength and formability of the CFRTP bolt B manufactured by the method for manufacturing a fiber-reinforced resin fastener according to the present embodiment are evaluated. As the bolt B, an M8×30 hexagonal fully threaded bolt (that is, a hexagonally threaded fully threaded bolt having an outer diameter of 8 mm and a shaft portion of 30 mm in length) will be described as an example.

CFRTP chopped material, which is the material of the bolt B, is formed by chopping a CFRTP sheet. A CFRTP sheet consists of a sheet in which a large number of carbon fiber long fibers extend in a single direction, that is, a UD sheet. It is produced by impregnating nylon 6 (PA6), PA9T, PPS, etc., which serves as a matrix (base material) while stretching.

The size of the chopped material formed by shredding the above CFRTP sheet is shaped with respect to the cavity in consideration of the size of the inlet and the cavity of the mold for molding the M8 bolt. It is set to be a good size.

The volume content (Vf) of carbon fibers in the CFRTP sheet and chopped material is 35 to 53%.

When the chopped material (or the chopped sheet in which the chopped material is fixed to a carrier sheet (for example, thermoplastic resin film)) is put into the mold and the bolt B is press-molded, for example, heating at a molding temperature of 270 ° C. Under this condition, the chopped material (or chopped sheet) is pressed with a press pressure of 37 MPa. After that, in a state where heating is stopped, a bolt B having a predetermined shape is formed by further pressurizing with a press pressure of 73 MPa at normal temperature (for example, about 25° C.) as a cold press.

The tensile breaking load, formability, and fiber filling degree of the CFRTP bolt B manufactured by the manufacturing method of the present embodiment are evaluated as follows.

In addition, the tensile breaking load test is performed by a test method based on JIS B 1051.

As shown in Table 1, as a CFRTP bolt B manufactured by the method for manufacturing a fiber-reinforced resin fastener of the present embodiment, under the conditions of Examples 1 to 7, a hexagonal full screw with a size of M8 × 30 of bolts. In addition, under the conditions of Example 8, a nut of M8 corresponding to the bolt is manufactured.

In Example 1, a rectangular chop material (50 μm thick) of 5 mm×10 mm (that is, 5 mm wide and 10 mm long) and a PA6 film are used as a matrix (base material). The fiber volume content (Vf) of the carbon fibers is 53%.

In Example 2, a 5 mm×20 mm rectangular chopped material (50 μm thick) and a PA6 film as a matrix (base material) are used, and the fiber volume content of the carbon fibers is 35%.

In Example 3, a 5 mm×100 mm rectangular chopped material (50 μm thick) and a PA6 film as a matrix (base material) are used, and the fiber volume content of carbon fibers is 53%.

In Example 4, a square chop material of 40 mm square (that is, 40 mm in both length and width) and a PA6 film as a matrix (base material) are used, and the fiber volume content of carbon fibers is 53%.

In Example 5, a rectangular chop material of 5 mm × 20 mm (thickness 50 µm) and a PA9T film, which has better physical properties than PA6, were used as the matrix (base material), and the fiber volume content of the carbon fibers was 53%.

In Example 6, a rectangular chop material of 5 mm×10 mm and a PPS film are used as the matrix (substrate). Incidentally, the fiber volume content of the carbon fibers is 47.7%.

In Example 7, a chopped sheet (that is, a sheet in which a chopped material is fixed to a carrier sheet (thermoplastic resin film)) and a PA6 film as a matrix (base material) are used, and the fiber volume content of carbon fibers is 53%.

Example 8 is an M8 nut corresponding to the bolt manufactured under the conditions of Examples 1 to 7 above, and is a 5 mm × 20 mm rectangular chopped material (thickness 50 μm) and a matrix (base material) A PA6 film is used and the fiber volume content of carbon fibers is 53%.

On the other hand, in Table 2, in order to compare with Examples 1 to 8, under the conditions of Comparative Examples 1 to 7, M8×30 size hexagonal fully threaded bolts were manufactured. In addition, under the conditions of Example 8, a nut of M8 corresponding to the bolt is manufactured.

In Comparative Example 1, a UD sheet (thickness 180 μm) and a PA6 film are used as the matrix (base material).

In Comparative Example 2, a 5 mm×1000 mm tape material (thickness: 50 μm) is rounded and put into a mold. A PA6 film is used as the matrix (base material), and the fiber volume content of the carbon fibers is 53%.

Furthermore, in Comparative Example 3, a 5 mm × 20 mm rectangular chopped material (50 μm thick) and a PA6 film were used as the matrix (base material), and the fiber volume content of the carbon fibers was 53%. Threads are machined after the bolt is manufactured.

Comparative Example 4 is an injection product of a short fiber reinforced product material containing glass fibers, and PPS is used as the matrix (base material). The content of glass fiber (GF) is 40% (% by weight).

Comparative Example 5 is an injection product of a short fiber reinforced product material containing glass fibers, and MXD6 is used as the matrix (base material). The content of glass fiber (GF) is 50% (% by weight).

Comparative Example 6 is an injection product made of a resin material, and PC (polycarbonate) is used as the matrix (base material).

Comparative Example 7 is an injection product made of a resin material, and PEEK (polyetheretherketone) is used as the matrix (base material).

In Comparative Example 8, a nut of M8 corresponding to the bolt manufactured under the conditions of Comparative Example 4 is an injection product of short fiber reinforced material, and PPS is used as the matrix (base material). The content of glass fiber (GF) is 40% (% by weight).

As a result of performing a prescribed number of tensile tests on the bolts and nuts manufactured in Examples 1 to 8 and Comparative Examples 1 to 8, the tensile tensile breaking load for each example was determined, and the moldability and fiber filling were determined. The degree was evaluated. The results are shown in Tables 1-2.

As shown in Tables 1 and 2 above, the tensile breaking load of the CFRTP bolt manufactured by the manufacturing method of the present embodiment (that is, the manufacturing method in which pressure molding is performed using CFRTP chopped material) is It is in the range of 4921-7890N as shown in Examples 1-7. Moreover, in Examples 1 to 7, the moldability was evaluated as Δ (molding completed at a rate of about 70%) and ◯ (molding completed in all cases). In addition, in Examples 1 to 7, the degree of fiber filling was evaluated as ◯ (filling completed to the entire screw thread at a rate of about 70%) and ◎ (filling complete to the tip of the screw thread) (fibers in FIG. 18 (See diagram for evaluation of degree of filling). FIG. 18 shows a cross-sectional view of the thread 31 of the bolt, where 31a indicates the tip of the thread, 32 indicates carbon fiber, and 33 indicates the matrix resin.

On the other hand, in Comparative Example 1, the tensile breaking load of the bolt manufactured by pressing the UD sheet as it is was only 2537N, which is far below the minimum value of 4921N within the above range in Examples 1-7. Furthermore, the evaluation of the degree of filling of the fiber is also x (filling up to the tip of the thread is not possible) (see FIG. 18).

In Comparative Example 1 above, it is possible to form a bolt using the UD sheet, but the tensile breaking load is only 2537 N, and the tensile breaking of Examples 1 to 4 and 7 using the same material (PA6 film) matrix Significantly lower than load (4921-7890N). The reason for this is that in the bolt B molded according to Comparative Example 1, in the cross section of the bolt B shown in FIG. It is believed that there is. The voids V are considered to be caused by the continuous fibers in the UD sheet (that is, a layer of reinforcing fibers of long fibers oriented in a predetermined direction) blocking air escape paths during bolt molding. The void V shown in FIG. 12 was confirmed by observing the cut surface of the bolt B with a laser microscope. On the other hand, in the bolts B of Examples 1 to 4 and 7, no voids V were found even when the cross section was observed.

When the tape material was rolled and pressure-molded as in Comparative Example 2, the bolt could not be molded, and the tensile breaking load could not be measured, and the moldability and fiber filling degree could not be evaluated.

Comparative Example 3 uses a rectangular chopped material (50 μm thick) of 5 mm×20 mm, a PA6 film as a matrix (base material), and the fiber volume content of carbon fibers is 53%. The M8 bolt (diameter 8mm) is further processed to shave the threads. As a result, the tensile breaking load (2084 N) of Comparative Example 3 is significantly lower than those of Examples 1-4 and 7 (4921-7890 N). The reason for this is that compared to the state in which the reinforcing fibers F continuously extend inside the bolt B1 before the cutting process shown in FIG. It is considered that the reason for this is that the reinforcing fiber F was cut inside the bolt B2 of No. 3 and the tensile strength decreased.

Looking at the respective tensile breaking loads (3215 N and 4386 N) when using an injection product of PPS containing glass fibers as in Comparative Example 4 and an injection product of MXD6 containing glass fibers as in Comparative Example 5, It can be seen that the tensile breaking load (4921-7890N) of Examples 1-4 and 7 is sufficiently lower.

In addition, as examples of resin injection products that do not contain fibers, a PC injection product as in Comparative Example 6 and a PEEK injection product as in Comparative Example 7 were used. ), it can be seen that it is sufficiently lower than the tensile breaking load (4921-7890N) of Examples 1-4 and 7.

Further, as shown in Example 8, the tensile breaking load of the CFRTP nut manufactured by the manufacturing method of the present embodiment (that is, the manufacturing method in which pressure molding is performed using CFRTP chopped material) is 9292 N. , which is a very high value. Moreover, in Example 8, the moldability was evaluated as ◯ (completely molded), and the fiber filling degree was also evaluated as ⊚ (filled up to the tip of the thread).

On the other hand, the tensile breaking load of the nut manufactured in Comparative Example 8, that is, the nut that is an injection product of PPS containing glass fibers, is only 3290 N, which is much lower than the tensile breaking load (9292 N) of the nut of the above example. ing.

Furthermore, as shown in Table 3 below, the weight of the carbon fiber (CF) M8 bolts manufactured in Examples 1 to 7 was 3 g, and the weight of the stainless steel (SUS) M8 bolts Less than 1/5 compared to (16g) and very light. In addition, the weight of the carbon fiber (CF) M8 nut manufactured in Example 8 is 1.2 g, which is 1 /4 to 1/5 smaller and very light.

Looking at the test results in Table 1 above, the fiber length of the reinforcing fibers contained in the chopped material is 5 to 100 mm, preferably 5 to 40 mm, more preferably 5 to 20 mm. It is conceivable that bolts and nuts can be manufactured. In addition, considering that the bolts and nuts manufactured according to Examples 1 to 8 are excellent in tensile strength, it is presumed that the torsional strength is also high.

Here, it is thought that the longer the fiber length of the chopped material, the better the strength of the bolt. /10 min, preferably 5 to 30 g/min. With this numerical value, it is possible to maintain good formability.

Also, the volume content of the reinforcing fibers contained in the matrix of the chopped material is preferably within the range of 30 to 80%. If it is less than 30%, the strength of the bolt will be low, and if it exceeds 80%, the shapeability will decrease and molding will become difficult. The ratio is preferably within the above range, more preferably 30-60%.

(Modification)
(A)
In the above embodiment, as shown in FIG. 6, a large number of chopped materials C obtained by shredding a CFRTP sheet are put into a mold 11, and the chopped materials C are hot-pressed to fasten bolts B and the like. However, the present invention is not limited to this. good.

That is, as a modification of the manufacturing method of the present invention, in this manufacturing method, after the above-described (A) chopped material preparation step, (D) a chopped sheet is produced by arranging and uniting a plurality of chopped materials in a plane. It further includes a chopped sheet production step (S21 in FIG. 2), and is characterized in that the chopped sheet is stuffed inside the mold in the above-mentioned (B) charging step.

The chopped sheet production step is sufficient to produce a chopped sheet CS in which a plurality of chopped materials C are arranged and united in a plane, and the use of a film for uniting a plurality of chopped materials C is not particularly limited in the present invention. .

As an example of the chopped sheet production process, for example, a chopped sheet is produced by impregnating a thermoplastic resin film with a plurality of chopped materials dispersed in at least one surface thereof. Specifically, as shown in FIG. 11, the thermoplastic resin film R2 is continuously fed, and a large number of chopped materials C are dispersed on both sides of the thermoplastic resin film R2 as shown in section XI. The chopped sheet CS in which the chopped material C is dispersed on both sides is manufactured by applying pressure while heating with a heating roll or the like. The chopped material C may be impregnated into only one of the two surfaces of the thermoplastic resin film R2.

If the thermoplastic resin film R2 is the same material (for example, nylon 6 (PA6)) as the thermoplastic resin sheet R1 (see FIG. 3) used in manufacturing the chopped material C, the matrix of the chopped material C Since it is the same material as the (base material), the chopped material C is easily impregnated into the thermoplastic resin film R2.

The thicknesses of the thermoplastic resin sheet R1 and the thermoplastic resin film R2 are appropriately selected in consideration of manufacturing conditions for manufacturing the chopped material C and the chopped sheet CS.

The manufactured chopped sheet CS is deformed so as to be easily introduced into the inlet 12 of the mold 11, and packed into the mold 11 in a rolled state, for example (see FIG. 6). If the chopped sheet CS is large, it may be cut into a size corresponding to the volume of the bolt B to be formed, and then rolled.

In the above-described manufacturing method, a plurality of chopped materials C are arranged in a plane and combined to form a chopped sheet CS, and the chopped sheet CS is packed into the mold 11, thereby forming a plurality of chopped materials C. It becomes possible to easily disperse and put them into the space (cavity) 13 of the mold 11 . As a result, separate work for uniformly dispersing the chopped material C after charging into the space 13 of the mold 11 is no longer necessary, and mass productivity is further improved.

Moreover, since the chopped material C inside the chopped sheet CS also maintains a constant fiber length, it is possible to manufacture fasteners such as bolts B having long fibers, thereby improving the strength of the fastener. is possible.

In addition, in the above modification, the chopped sheet CS can be easily produced by impregnating at least one surface of the thermoplastic resin film R2 with a plurality of chopped materials C in a dispersed state. In addition, the risk of separation of the chopped material C from the chopped sheet CS after production is reduced.

(B)
Moreover, as another modification, the chopped sheet CS produced in FIG.

That is, in the manufacturing method as another modified example of the present invention, after the chopped sheet manufacturing step (D), as shown in sections XII to XIII in FIG. It further includes a chopped sheet shredding step for shredding into large predetermined sizes, and in the above-mentioned (B) loading step, the chopped sheet T (see FIGS. 6 and 11) is packed inside the mold 11. It is characterized by

In the above manufacturing method, the chopped sheet T chopped into a predetermined size larger than the chopped material C is packed inside the mold 11, so the chopped sheet is rolled or deformed before being packed inside the mold 11. Separate work becomes unnecessary, and it is easy to put into the mold. In addition, the chopped material C can be dispersed more uniformly in the space 13 of the mold 11 than when the chopped material C is put into the mold 11 as it is. As a result, mass productivity is further improved.

(C)
In addition, in the manufacturing method of the above-described embodiment, an example is shown in which a chopped sheet is produced by arranging a plurality of chopped materials on a plane and united, and the chopped sheet is stuffed inside a mold. There is no limitation to what shape the plurality of chopped materials are packed together in the mold. Therefore, as a modification of the present invention, a plurality of chopped materials shaped like rods may be put into a mold and pressurized.

<Summary of embodiment>
It is as follows when the said embodiment is put together.

The method for manufacturing a fastener made of fiber-reinforced resin according to the above-described embodiment is a method for manufacturing a fastener made of fiber-reinforced resin, wherein spread reinforcing fibers are impregnated with a thermoplastic resin while being oriented in a predetermined direction. a preparation step of preparing a plurality of chopped materials obtained by shredding a fiber-reinforced resin sheet into a predetermined size ; Including a step of filling a chopped sheet into a mold, and a pressing step of molding the shape of the fastener by pressing the chopped sheet inside the mold while the mold is heated. characterized by

In this manufacturing method, as a material for the fastener, a fiber-reinforced resin sheet impregnated with a thermoplastic resin in a state in which the spread reinforcing fibers are oriented in a predetermined direction is cut into pieces of a predetermined size. Prepare multiple chop materials. Then, a chopped sheet is produced by arranging and uniting a plurality of chopped materials in a plane, the chopped sheet is stuffed into a mold, and the chopped sheet is pressure-molded in a heated state. The chopped material that makes up the chopped sheet has good formability, that is, the ability to follow the shape of the cavity of the mold, so it is more mass-producible than the conventional case of cutting and manufacturing a bar-shaped member made of fiber-reinforced resin. Excellent.

Moreover, since the group of chopped materials, which are the materials of the fastener, has random orientation (that is, the property that the orientation of the reinforcing fibers is not specified), even if pressure molding is performed, the reinforcing fibers contained in the chopped materials Less chance of disconnection. Further, since the fastener after molding also maintains a constant fiber length of the reinforcing fibers, the strength of the fastener can be improved. As a result, it becomes possible to manufacture a fiber-reinforced resin fastener having excellent mass productivity and high strength.

Further, in the manufacturing method according to the above-described embodiment, the plurality of chopped materials are arranged in a plane and combined into a chopped sheet state, and the chopped sheet is stuffed inside the mold, thereby forming the plurality of chopped materials into the mold. It becomes possible to easily disperse and put in the space of. As a result, there is no need for a separate operation for uniformly dispersing the chopped material in the space of the mold after charging, and mass productivity is further improved.

Moreover, since the chopped material inside the chopped sheet also maintains a constant fiber length, it is possible to manufacture a fastener having long fibers, and to improve the strength of the fastener.

In the above method for manufacturing a fastener made of fiber-reinforced resin, the chopped sheet producing step includes impregnating the chopped sheet with the plurality of chopped materials dispersed on at least one surface of a thermoplastic resin film. is preferably made.

In this case, the chopped sheet can be easily produced by impregnating the thermoplastic resin film with a plurality of chopped materials dispersed on at least one surface thereof. In addition, the risk of separation of the chopped material from the chopped sheet after production is reduced.

The method for manufacturing the above-described fiber-reinforced resin fastener further includes a chopped sheet shredding step of shredding the chopped sheet to a predetermined size larger than the chopped material after the chopped sheet fabricating step. Preferably, in the charging step, the chopped sheets are stuffed into the mold.

In this manufacturing method, the chopped sheet cut into a predetermined size larger than the chopped material is stuffed inside the mold, so there is no need for separate work of rounding or deforming the chopped sheet before stuffing it inside the mold. It becomes easy to put it into the mold. At the same time, it is possible to distribute the chopped material more uniformly in the space of the mold than when the chopped material is put into the mold as it is. As a result, mass productivity is further improved.

In the above method for manufacturing a fastener made of fiber-reinforced resin, it is preferable that the fiber length of the reinforcing fibers contained in the chopped material is 5 to 100 mm. Within this range, it is possible to ensure high strength of the fastener.

In the above method for manufacturing a fastener made of fiber-reinforced resin, it is preferable that the volume content of the reinforcing fibers contained in the thermoplastic resin in the chopped material is 30 to 80%. Within this range, it is possible to ensure high strength and formability of the fastener.

The fiber-reinforced resin fastener according to the present embodiment is a fiber-reinforced resin fastener formed of a thermoplastic resin and reinforcing fibers impregnated in the thermoplastic resin in an unspecified orientation, The fiber length of the reinforcing fibers is in the range of 5 to 100 mm, and the volume content of the reinforcing fibers in the thermoplastic resin is in the range of 30 to 80%.

In the above fastener, the reinforcing fibers are impregnated with the thermoplastic resin in a state where the orientation of the reinforcing fibers is not specified, that is, the reinforcing fibers have long fibers, and the fiber length is in the range of 5 to 100 mm as a condition for the reinforcing fibers. and the volume content in the thermoplastic resin is within the range of 30 to 80%, so that the mass productivity is excellent and the strength is high.

According to the method for manufacturing a fiber-reinforced resin fastener and the fiber-reinforced resin fastener according to the present embodiment, it is possible to manufacture a fastener having excellent mass productivity and high strength.

Claims (5)

A method for manufacturing a fastener made of fiber-reinforced resin, comprising:
A preparation step of preparing a plurality of chopped materials obtained by shredding a fiber-reinforced resin sheet impregnated with a thermoplastic resin into a predetermined size with the spread reinforcing fibers oriented in a predetermined direction;
A chopped sheet producing step of producing a chopped sheet in which the plurality of chopped materials are arranged in a plane and united;
A step of filling the chopped sheet into a mold;
A method of manufacturing a fastener made of fiber-reinforced resin, comprising a pressurizing step of molding the shape of the fastener by pressurizing the chopped sheet inside the mold while the mold is heated. The fiber-reinforced resin fastener according to claim 1 , wherein in the chopped sheet manufacturing step, the chopped sheet is manufactured by impregnating the plurality of chopped materials dispersed on at least one surface of a thermoplastic resin film. manufacturing method. After the chopped sheet producing step, further comprising a chopped sheet shredding step of shredding the chopped sheet into a predetermined size larger than the chopped material,
In the charging step, the shredded chopped sheet is packed inside the mold,
A method for manufacturing the fiber-reinforced resin fastener according to claim 1 or 2 . The fiber length of the reinforcing fibers contained in the chopped material is 5 to 100 mm,
A method for manufacturing a fiber-reinforced resin fastener according to any one of claims 1 to 3 . The volume content of the reinforcing fibers contained in the thermoplastic resin in the chopped material is 30 to 80%.
A method for manufacturing a fiber-reinforced resin fastener according to any one of claims 1 to 4 .

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