JPS6237131A - Plastic screw material containing reinforcing fiber - Google Patents

Abstract

PURPOSE:To give a screw material having enough binding torque strength, by placing at least one layer of the cylindrical knitting knitted with reinforcing fiber bundles extending over a flight of the outer or inner surface of the screw member and a neighboring screw core part. CONSTITUTION:Two layers 5a, 5b of a cylindrical knitting are placed in a bolt 1 and more than one of fiber bundles 6 consisting of reinforcing-fibers are placed in the core part of the bolt 1. The reinforcing fibers are cured with a resin 7 and the cylindrical knitted string 5a located in the outermost layer extends over a screw part 2 and the position 3a of the core part 3 neighboring to the screw part 2. The fiber bundles constituting the cylindrical knitted strings 5a spread over the screw part 2 and the core part 3 and the screw part 2 is thereby firmly joined with the core part 3. The screw part 2 of the bolt 1 therefore has high shear strength.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a screw member made of fiber reinforced plastic (hereinafter referred to as FRP), and more specifically, the present invention relates to a screw member made of fiber-reinforced plastic (hereinafter referred to as FRP), and more specifically, it has a high thread shear strength during tightening, and is highly efficient. This relates to FRP screw products that can be mass-produced at low cost and of high quality.

[Prior Art] FRP screw products are being put into practical use in various fields because they have excellent corrosion resistance, electrical insulation properties, and are lightweight.

To date, FRP threaded members have been made using a variety of methods.

For example, there is a method in which a rod is produced by impregnating a stretched roving with resin and pulling it out through a cylindrical heating mold, and then threading the rod later by machining.

However, in screw members made using this method, the thread fibers are aligned parallel to the axial direction of the screw, so there is no fiber connection between the unthreaded core and the thread. , only screws with extremely low thread strength can be made.

Another method is to mix chopped strands and resin in a kneader, and press-mold the mixture using a screw-shaped mold to obtain a screw member.

With this method, glass fibers extend from the core of the screw to the threads, improving the strength of the threads.

However, because the fibers are not oriented in the axial direction of the screw, the tensile strength in the axial direction of the screw member is extremely low, and the screw thread itself often breaks rather than the threads breaking due to tensile stress. .

Another method for obtaining a screw member made of FRP is to create a laminate by laminating resin-impregnated yarn cloth by hand lay-up, or by stacking resin-impregnated cloth and press-molding to create a laminate. This method involves carving out rods or blocks from this plate and machining them with screws to obtain bolt nuts.

The FRP screw member made by this method has superior strength compared to the FRP screw member made by the second method described above. However, the production cost of this type of screw member is extremely high, and in addition, the screw member suffers from peeling and has the disadvantage that it cannot have satisfactory strength. Therefore, this type of FRP screw member is actually only used for special purposes.

In order to overcome the weaknesses of these conventional threaded members, one of the inventors of the present invention proposed a method that can improve the strength of threaded members by arranging them using roving or yarn cloth tape. (Japanese Patent Application No. 58-3087E1 and Patent Application No. 58-30877)
.

However, there are some issues that require further quality improvement in screw members made using this method, and we have continued to conduct research and development.

Further, Japanese Patent Application Laid-Open No. 51-12Ei2B2 describes a method of sequentially pultruding various types of FRP members by covering the outermost layer of the member with a cylindrical knitted cloth. The purpose of this invention is to increase the strength of a rod-shaped rod, for example, a T-shaped rod, in the axial direction and perpendicular direction, and is not intended to be used to make a threaded member. Because it is thin, even if a threaded member such as a bolt is made from the resulting bar-shaped member, the cylindrical knitted cloth will be cut into pieces during the thread cutting stage, reducing the strength of the port thread. .

[Problems to be solved by the invention] As mentioned earlier, screw members made of FRP are marketable products due to their excellent corrosion resistance and electrical insulation properties. In reality, its uses are limited due to its poor strength and physical properties and extremely high manufacturing cost.

The object of the present invention is to provide a threaded member such as a bolt with sufficient shear strength when tightened with a nut.
The object of the present invention is to provide a threaded portion having sufficient tensile strength for the bolt itself, and also to provide a threaded member having sufficient tightening torque strength even in a female threaded member such as a nut.

Another purpose is that such screw members can be effectively mass-produced and that FRP screw members can be provided at low cost.

[Means and effects for solving the problems] An object of the present invention is to provide a screw member made of FRP made of a large number of reinforcing fibers and a thermosetting resin, in which the screw is a male thread when it is on the outside of the member. If it is inside, it will be a female thread. Its characteristic feature lies in the arrangement of the reinforcing fibers, in which the reinforcing fiber bundles are woven into a cylindrical shape in the axial direction of the screw, and each layer is thicker than the height of the screw thread, so the unthreaded core To provide a screw member characterized in that reinforcing fiber bundles exist in a connected form from the threaded part to the threaded part.

That is, according to the present invention, there is provided a screw member made of fiber-reinforced plastic made of a thermosetting resin and a bundle of reinforcing fiber bundles, the axial direction of which is woven by the reinforcing fiber bundles. A fiber-reinforced plastic screw member, characterized in that at least one layer of the tubular knitted material in the same direction as the axis is present across the thread formed on the outer or inner surface of the thread member and the core of the thread adjacent thereto. is provided.

According to the present invention, the reinforcing fibers in the screw member are present as several tube-knit layers. Furthermore, if the threaded member is a rod-shaped threaded member (such as a bolt) or something with a thread cut on the inside like a nut, a cylindrical shape woven with reinforcing fiber bundles is added to the threaded part and the core adjacent to the threaded part. It is characterized by the fact that one layer of knit is straddled and one reinforcing fiber bundle is connected from the core to the threaded part (or it is present from the core to the threaded part). Furthermore, by inserting fiber bundles aligned in the same direction as the axial direction of the screw member into the core of this tubular knitted fabric, it is possible to increase the tensile strength of the screw member.

As is well known, in a knitted structure, the yarns constituting the knitted fabric (<FiAm bundle) are knitted in a loop shape, resulting in a three-dimensional structure. That is, the loops of yarn or fiber bundles regularly rise from the plane of the knitted fabric with an inclination angle that depends on the design of the knitting structure and the thickness of the yarns or fiber bundles.

Therefore, if the braid can be successfully knitted to straddle the threaded thread and the adjacent core, the yarns or fiber bundles of the tubular knit will straddle the thread and the adjacent core. Moreover, it is also possible to make the fiber angle in the braided string of yarn or fiber bundle not in accordance with the thread slope of the threaded member.

In this way, if the yarn or fiber bundle can span the threaded part and the core part adjacent to the thread, it is possible to dramatically increase the shear strength at the threaded part of a threaded member made of fiber-reinforced plastic. .

In order to achieve the object of the present invention, -e of the tubular knitted material is
It is important that it straddles the threaded part and the adjacent core part.

By doing so, the threaded portion hardened with resin and the core portion will be firmly connected by the yarn or fiber bundle.

As the reinforcing fiber used in the screw member of the present invention, glass fiber is preferably used because of its low cost. However, other fibers can be used instead of glass fibers, such as aramid fibers or carbon fibers. These reinforcing fibers are primarily used in the form of bundled strands made up of a large number of filaments.

Furthermore, in order to increase the adhesive strength with the thermosetting resin that forms the matrix of the reinforcing fibers, it is desirable to treat the fibers with a coupling agent or the like.

As the thermosetting resin, resins normally used in fiber-reinforced plastics, such as epoxy resins, unsaturated polyester resins, vinyl ester resins, etc., are used as the resin for the screw member of the present invention.

However, in order to obtain a screw member with high mechanical strength, it is desirable to use epoxy resin.

The proportion of reinforcing fibers in the screw member is preferably 55 to 78% by weight, and most preferably 60 to 75% by weight. If this proportion is less than 55% by weight, the contribution of the reinforcing fibers to the physical properties will decrease, making it impossible to obtain a screw member with high mechanical properties. If this ratio exceeds 78% by weight, some reinforcing fibers are not impregnated with resin, resulting in complete loss of bonding between the reinforcing fibers and variations in the mechanical properties of the screw member.

In order to increase the reinforcing effect of the threads, other substances, for example chopped strands or curled strands, can also be added to the reinforcing fibers, ie the tubular braided fiber bundles.

It is also possible to knead an appropriate amount of additional LA fiber reinforcing material into the resin. The amount of fiber reinforcing material added at this time varies depending on the shape and thickness of the cylindrical wire string, the knitting design, etc., the size of the screw member to be made, the use, etc.

To aid in understanding the invention, enhancement #am according to the invention
We will describe in detail the wood-based technical idea behind the plastic screw member using the attached drawings.

As mentioned above, the screw member according to the present invention includes a bolt and a nut, but the bolt according to the present invention will be explained first.

FIG. 1 shows a typical example of a bolt according to the present invention.

The bolt l consists of a threaded portion 2 and a core portion 3. As schematically illustrated in FIG. 2, the threaded portion 2 includes the threaded portion of the bolt, as indicated by the helix 4 in FIG. Two layers (5a, 5b) of cylindrical thread are arranged on the bolt 1 in FIG. have.

The reinforcing fibers are hardened with resin 7. The cylindrical braid 5a located in the outermost layer extends across the threaded portion 2 and the portion 3a of the core portion 3 adjacent to the threaded portion 2. Therefore,
As detailed in the description of FIG. 5 below, the fiber bundles constituting the tubular lace 5a extend from the threaded portion 2 to the core 3, so that the threaded portion 2 is tightly Core part 3
It is connected to. Therefore, the threaded portion 2 of the pole according to the present invention can have strong shear strength.

Cylindrical wire strings can be made by weaving rovings made of single or tens of water strands of several hundred to several hundred filaments. The roving has a diameter of 0.5 on the knitting machine.
There is ~lha.

Figure 3 shows a front photograph of the cylindrical wire string.

In the tubular knitted fabric shown in Fig. 3, the fiber bundles 51, 52, and 53 run tilted to the left in the first course, and the fiber bundles 51', 52', and 53' run tilted to the right in the next course. It is woven at an angle. As can be seen from the fiber bundles 55.58, in each of the fiber bundles 55.58, a
The parts of the cylindrical wire come out outward from the surface of the cylindrical wire, and the part b of each mIn bundle 55.58 extends toward the center of the cylindrical wire. There is. Furthermore, the fiber bundles 55 and 56 intersect at a predetermined angle depending on the thickness of each am bundle and the knit design of the swing angle.

Furthermore, since each part of the fiber bundle is knitted as shown in FIG. 3, the positional relationship of the filament fibers in each fiber bundle changes completely at each position in the rod-shaped molded product.

Figure 4 shows the core part (core part 6), 5a, and 5b.

5C shows a cross section of a rondo made of three layers of tubular knitted fabric before thread cutting.

In FIG. 4, the arrangement of each filament in each fiber bundle, that is, the inclination direction of the fiber bundle constituting the outermost cylindrical braid 5a, changes depending on the position in the circumferential direction of the rod. come.

In FIG. 5, an example of the arrangement of fiber bundles 1a in the thread of a bolt will be schematically explained using fiber bundles 55 and 58.

The X-axis direction is the tangent line passing through the 0 point to the root of the screw,
parallel to the axial direction of the screw. The Y axis indicates the radial direction of the port. The Z axis is a tangential direction passing through the zero point of the root of the thread, but is an axis directed in the circumferential direction of the thread.

When viewing FIG. 5 from the left to the right, the fiber bundle 55 comes out from the core 3 of the screw, first reaches the apex 2c of the threaded part 2 along the inclined surface 2b of the threaded part 2, and then the fiber bundle 55 changes its direction downward and approaches the inclined surface 2a of the threaded portion 2 at a point further along the Z-axis. Finally, the screw core RB3 is reached.

Therefore, the fiber bundles are located along the inclined surface of the threaded portion at regular intervals substantially along the circumferential direction of the threaded portion. This situation is shown in FIG. 5, where the #a fibers oriented in a direction inclined to the right are substantially along the inclined surface 2b of the screw and are represented by a circle 55c. or,
The fiber bundles oriented in a right-handed direction substantially follow the sloped surface 2a of the screw and are represented by the cross mark 56c.

As is clear from FIG. 6, the points 55c and 58c are not continuous but are arranged at regular intervals.

However, if we consider one screw thread, at each point, the mMl focus is arranged along the circumferential direction of the thread along the slope of the screw, and each mi focus is located at the core of the screw. (the unthreaded shaft core part). Therefore, even if a bolt is tightened by a nut, or a tensile force is applied to a bolt tightened by a nut, and a shearing force is applied to the threads, this fiber bundle can withstand the shearing force. .

FIG. 7 is a cross-sectional photograph of one thread in the bolt of the present invention.

The fiber bundle at position 55c actually runs along the slope on the right side of the thread, and on the other hand at 5? , 58 actually run in a plane perpendicular to the plane of the figure.

As can be understood from the above, the thickness of the outermost layer (or innermost layer in the case of nuts) of the cylindrical braid used for threaded members, i.e. bolts and nuts, is the height of the thread. For this reason, it is important that the u and male bundles connect from the screw core (the unthreaded part of the screw) to the threaded part.

Figures 8 and 9 show the method for manufacturing a tubular knitted fabric with this type of property.
This will be explained using figures.

For example, a tubular knitted fabric can be produced on a circular knitting machine having twelve knitting needles, as shown schematically in FIG.

FIG. 9A shows a case in which one fiber bundle 51 is knitted by moving back and forth between knitting needles 81 and 82. The knitting structure in this case is schematically shown in FIG. 8A (so-called one stitch swing). FIG. 9B shows that one fiber bundle 51 is connected to knitting needles 91 and 93.
This shows the case in which the yarn is knitted by going back and forth between the two. The knitting structure in this case is shown in FIG. 8B (so-called two-stitch swing).

Further, Fig. 9C shows a case in which one TA fiber bundle 51 is knitted back and forth between knitting needles 91 and 94, and the knitting structure in this case is shown in Fig. 8C (so-called three-needle swing). case). The tubular braid explained in FIG. 3 corresponds to the braid knitted with the knitting structure explained in FIGS. 8C and 9C. In other words, this knitting structure is known as a three-stitch stitch structure. The tubular knitted fabrics knitted based on the knitting structures shown in FIGS. 8C and 9C are as shown in FIGS. 8A and 9.
The knitted fabric is thicker than the knitted fabric shown in Figure c.

And, compared to the tubular knitted fabric based on FIGS. 8A and 9A,
Fiber bundle 5 in Figures 8C and 9C! has a more upright structure than the interior.

FIG. 1O shows an example of a bar according to the present invention. It shows the structure of the reinforcing fibers and the parts hardened with resin.

That is, the fiber bundle 6 is a core material at the center, and the fiber bundle 6 is continuously covered with tubular braids 5a and 5c. The right end portion of the rod-shaped member is hardened with resin.The rod-shaped member of the present invention usually has a structure in which a plurality of cylindrical braids are placed over each other. At this time, it is desirable that the layers of the tube-knitted string be bonded to each other in an appropriate manner.

When using multiple tube-knitted strings, it is best to use a small number of thick fiber bundles for the inner layer to knit coarsely, and for the outer layer to knit finely by using many thin strings. The rod member having the structure described above, which is made up of multiple cylindrical knitted layers, will not cause the peeling phenomenon between the cylindrical braids even if tensile stress is applied to the tightened threaded part.
Even if torque stress is applied, it will not occur. This is because when the rod-shaped member is made by the pultrusion method, the uneven portions of the inner layer engage with the uneven portions of the outer layer.

The taM1 bundle used in the core portion is substantially aligned in a direction parallel to the axis of the screw member. Further, the fiber bundle used for the cylindrical braid or the shaft core may or may not be twisted. Usually, slightly twisted IA bundles are used to facilitate their handling.

FIG. 11 shows the specific structure of the nut 8. The nut 8 is also made from resin-impregnated tubular braid. In this case, the fiber bundles of the tubular braid 5 extend from the exposed part of the nut to the threaded part 2 in the same way as described in the case of the port 1.

Nuts are required to have high shear strength in their threaded portions, but usually tensile strength in the axial direction of the thread is not required. Therefore, it is usually not necessary to orient the fiber bundles parallel to the axial direction of the nut.

The method of making the thread of a nut will be explained using FIGS. 13 to 16. Each of the figures in FIGS. 13 to 16 represents each step in making a hexagonal nut. First, a cylindrical braid having the required thickness is produced (if the required thickness cannot be achieved in one layer, multiple layers are stacked).

The core 13 is passed through the hole in the center of the tubular braid (or when knitting the tubular braid, the core may be passed through the center and knitted around it). Next, this is immersed in a resin liquid of thermosetting resin 11, and the cavity of the cylindrical braid is filled with the resin.In this case, it is preferable that the rod inserted into the core be coated with a mold release agent. The tubular braid 5 impregnated with the curable resin 11 is then pressed into a hexagonal shape. It is then hardened by applying heat.

This molding step may be carried out by making a press mold as schematically shown in FIG. 18.

The press molding die 17 consists of a male die 18a and a female die 18b, and has a shape necessary for making a hexagonal nut.

And it has @a according to the size of the nut to be manufactured.

The molding method is to mold using a hollow mold or a split mold, and then heat and harden each mold, and the inside of the hollow heating mold is filled with reinforcing fibers impregnated with resin. A method of continuously drawing out and molding is possible. The ratio of reinforcing fibers to the total weight of the screw member can be controlled by adjusting the process of filling the mold with reinforcing ta fibers and resin.

For example, during pultrusion, the tubular braid is stretched by 5 to 15%. Therefore, it is necessary to determine the amount of resin in consideration of the elongation of the cylindrical braid so as to obtain a predetermined value. Furthermore, it is necessary to fill the spaces between the reinforcing fibers with resin so that no air pockets occur in the rod-shaped member.

After curing, the mold 17 and core 13 are removed from the rod-shaped member 16, and the rod-shaped member is cut into a predetermined length. Then a screw 15 is cut into the central hole of the cut piece.

If an easily cuttable material, such as a resin rod, is used as the core, it becomes possible to manufacture the nut by cutting the core and simultaneously threading the rod-like member.

Furthermore, apply mold release agent to the iron core with screws cut on the outer periphery □
It is also possible to create a rod-like member with an internal thread by coating it, creating a rod-like member using it as a core, and then turning the core in a spiral and pulling it out. The female thread produced using this method has strong thread strength because the reinforced #am on the thread is not damaged by cutting or the like. Furthermore, since there is no loss of reinforced TA fibers or resin, it can be manufactured at a low cost.

When manufacturing a tubular braid from a bundle of glass fiber filaments, it is preferable to satisfy the following conditions.

- The desirable range of the number of glass fiber filaments in the fiber bundle is 800 to 30,000.

・The desirable unit weight of Fi&m bundle is 0-1g/m to 1
It is in the range of 0 g/m.

- The preferred filament diameter range for glass fibers is 6 lm to 28 lm.

- The desirable range of the number of #a fibers used to knit the tubular braid (ie, preferred needle a) is 3 to 24.

Bolts according to the invention can also be made by means similar to the method of making nuts. However, in this case, in order to make a bolt with strong tensile strength, it is preferable to use a long fiber bundle such as a roving in the center (core part) of the rod-shaped member.

Furthermore, since a string such as a cylindrical wire string is highly flexible, it can be used, for example, as shown in FIG.
Even things like molded bolts can be freely obtained by impregnating a cylindrical wire string with resin and hardening it in a mold shaped like the bolt you want to make.

If necessary, it is also possible to use this method to make special bolts such as ■-shaped ports or bolts with uneven surfaces. Regarding the method of cutting the threads in the threaded member, it is important that the threads are cut within one layer of the cylindrical wire string. In other words, it is important that the end of the fiber bundle in the loop of the braid exits from the unthreaded core and enters the threaded part, and one end of the fiber bundle exits from the unthreaded core. You will need one bar that is firmly connected to the string at the end. As a result, the shear strength of the thread is significantly improved.

The mechanical properties when glass fiber bundles are used as reinforcing fibers in the present invention will be described below.

The torque strength described below is measured by fitting a washer to a bolt passed through a hole in an iron block, fitting an iron nut to the bolt, tightening it with a normal torque meter, and measuring the torque strength at the time of failure.

Regarding the tensile strength described below, an ordinary tensile tester was used to test the bolt 1 with washers 22a, 22b and iron nut 23a on both ends of the bolt 1, as shown in FIG.
, 23b and pull it into the jig holder 21a.

21b and pull it up and down to measure its breaking strength.

As mentioned above, the cylindrical wire string woven from reinforcing fiber bundles extends from the threaded part to the unthreaded part, so the shear strength of the threaded part according to the present invention is Stronger than normal FRP screw members. Furthermore, since the cylindrical wire string used as the reinforcing material is highly flexible, it is possible to easily make various bolts with special shapes.

Furthermore, by using a cylindrical wire string, continuous production becomes possible, manufacturing costs are reduced, and as a result, the uses of FRP screw members are expanded.

Because the screw member according to the present invention has the remarkable features described above, it can be used as a screw member for chemical plants, as an anchor bolt in tunnels, as a bolt for concrete formwork, and as an electrical insulation bolt. It is possible.

[Example] The present invention will be further explained by Examples, but the present invention is not limited to the following.

Example 1 A braid consisting of a core layer of TAM bundles aligned in the center and two layers of cylindrical wire string outside was prepared for making a bolt according to the present invention.

Core part: Glass fiber roving 712 manufactured by PP0 in the US (
88007e 3 inner layer tubular knitted fabric; US PP0 company 10E! 2 (1100Tex) Using 12 rovings, cylinder inner diameter 17 mm, cylinder knitting machine with 12 needles, cylinder knitting was performed on the previous core part.Tubular knitted fabric of outer layer: Also made by US company PP0 (7) 1082 (1100Te
x) using 12 rovings, cylinder inner diameter 25
mm, tube knitting was performed on the inner layer tubular knitted fabric using a tube knitting machine with 12 needles.If the core part is inserted in this way, the diameter of the triple structure will be 10 mm.
．． A braided cord having a length of 5 to 11.0 mm+ and a weight of 125 g/m was produced. This braided cord was immersed in a uniformly mixed resin composition liquid having the following composition.

The braided string impregnated with this resin was heated to 120°C and inserted into a hole with an inner diameter of 10.5 mm in a 1.5 m long mold.
It was passed at a speed of 0 cfflZ to create a cup with an outer diameter of 10.5 mm. Hold this rod at 120° for 3 hours.
After further post-curing at 150°C for 5 hours, a rod with a diameter of 10+ am was made using a centerless machine. From this rod, a bolt corresponding to Example 1 (see Table 1) was threaded using 10 dies.

The physical properties of the bolts obtained in this way are shown in Table 1.A commercially available MI is made by threading a rod obtained by mixing thermosetting resin L050% glass fiber by a rolling method.
Shown in comparison to O volts.

Table 1 Example 2 In order to produce a nut according to the present invention, a braided cord having a three-layer structure was produced under the following conditions.

The glass fiber roving used in each layer was a roving manufactured by PP0 Company in the United States, product number 10B2 (2000Tex).

Inner layer cylindrical knitted fabric; inner diameter 1 ha on iron rod coated with mold release agent.
Tube knitting was performed using a tube knitting machine having a diameter of 7 mm and 12 needles using 12 of the above-mentioned rovings.

Middle layer cylindrical knitted fabric; Cylinder inner diameter 23II1m on top of the inner layer cylindrical knitted fabric;
Using a tubular knitting machine with 12 needles, a tubular knitted fabric produced using 12 of the rovings described above was further covered.

Outermost layer tubular knitted fabric: A tubular knitted fabric is placed on the thus obtained double tubular knitted fabric using a tubular knitting machine having a cylinder inner diameter of 25+++ m and a needle count of 12, and 12 of the above-mentioned rovings. I made it and covered it.

The diameter obtained in this way is approximately 20.0 to 21.0 mm.
A triple-structure braided cord having a weight fi of 373 g/m was immersed in the same resin solution as in Example 1, and then placed in a mold as shown in FIG. 1B at a mold temperature of 120°C and a pressure of 50°C.
Pressure molding was performed under the conditions of kg/c+s2 for 1 hour to produce a hexagonal bar.

This rod was post-cured at 120° C. for 3 hours and at 150° C. for 5 hours, and then cut into a thickness of IElmm.

The central iron core was removed by tapping, and a thread was cut using a 12 tap in this hole to produce the nut of Example 2. Table 2 shows the physical properties of this nut.

Example 3 The nut of Example 3 was manufactured using an M12 bolt as a core material instead of the iron core of Example 2. The glass fiber composition and manufacturing method are exactly the same as in Example 2. The obtained hexagonal rod was cut to a thickness of If (am), and the bolt used as the core material was rotated and removed. The physical properties of the nut thus obtained as Example 3 are shown in Table 2. Indicated.

Table 2 [Effects of the Invention] The plastic screw member of the present invention has reinforcing fibers in the form of a tubular knitted fabric extending over the threaded portion and the unthreaded bare portion adjacent thereto. shows large shear strength. In addition, since the reinforcing fibers are used in the form of a tubular knitted fabric, each process such as impregnation of the reinforcing fibers with thermosetting resin, molding, curing, and mold release can be performed continuously, making mass production possible. Manufacturing costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a plan view, partially in section, of a bolt according to the invention. FIG. 2 shows an axial and diametrical cross-section of the bolt. FIG. 3 is an enlarged photograph of a cylindrical braid used as a reinforcing fiber for a bolt according to the present invention. FIG. 4 is an enlarged cross-sectional photograph of a rod for a threaded member prepared by impregnating and curing the cylindrical braid of the present invention with an epoxy resin. FIG. 5 is a perspective view of the threaded portion of the bolt according to the present invention, drawn to schematically explain how the #J1m bundle enters the threaded portion. FIG. 6 is a cross-sectional view of the bolt to schematically show that the reinforcing TA fibers are oriented alternately with an inclination along the inclination of the threaded portion. FIG. 7 is a 35 times enlarged photomicrograph of the threaded portion of the bolt cut in the axial direction. FIG. 8 is a front view showing three examples of knitting designs for making a tubular braid for making a screw member according to the present invention. FIG. 9 is a plan view schematically showing the relationship between knitting needles and fiber bundles in a knitting machine for making a cylindrical knitted string necessary for manufacturing a screw member according to the present invention. FIG. 1θ is a front photograph of a rod-shaped article according to the present invention, which is a three-layered braid partially cured with resin. FIG. 11 is a partial sectional view of a nut according to the invention. FIG. 12 is a perspective view showing a U-shaped port as an example of the screw member according to the present invention. 13 to 15 are perspective views schematically showing the nut manufacturing process according to the present invention. Here, FIG. 13 shows the first stage of manufacturing the rod-shaped object, FIG. 14 shows the shape of the rod-shaped object having a hexagonal outer surface, and FIG. 15 shows a nut cut out from the rod-shaped object. FIG. 16 is a sectional view showing a mold for molding a hexagonal rod-shaped object. FIG. 17 is a perspective view showing an apparatus for measuring the tensile strength of a screw member according to the present invention. DESCRIPTION OF SYMBOLS 1... Bolt, 2... Threaded part, 2a, 2b... Inclined surface of threaded part, 2C... Vertex of threaded part. 3... Core part, 4... Helix, 5.5a, 5b... Cylindrical braid (however, 5a and 5b indicate different layers), 6... Fiber bundle of core part. 7...Thermosetting resin. 8... Nut, 91, 92.93.94... Knitting needle, 10... Portion hardened with thermosetting resin, 11...
Thermosetting resin, 12...Hollow rod, 13...Core, 14...Mold, 15...Screw, 16...Bar-shaped member, 17...Mold, 18a...Male Mold, 18b... Female mold, 21a, 21b... Tension jig holder, 22a,
22b... washer, 23a, 23b... iron nut.

Claims (11)

[Claims] (1) A threaded member made of fiber-reinforced plastic made of a thermosetting resin and a bundle of reinforcing fiber bundles, the axial direction of which is woven with the reinforcing fiber bundles and whose axis is in the same direction as the axis of the threaded member. A fiber-reinforced plastic screw member, characterized in that at least one layer of the tubular knitted material is present across a screw thread formed on the outer or inner surface of the screw member and the core of the screw adjacent thereto. (2) Multiple tubular knitted fabrics made of reinforcing fiber bundles are layered,
The fiber-reinforced plastic screw member according to claim 1, which has a multilayer structure. (3) The fiber-reinforced plastic screw member according to claim 2, which has a structure in which tubular knitted fabrics forming a multilayer structure are connected to each other. (4) The fiber-reinforced plastic screw member according to claim 1, wherein the core portion of the fiber-reinforced plastic screw member has a bundle of reinforcing fiber bundles aligned parallel to the axial direction of the screw member. (5) The fiber-reinforced plastic screw member according to claim 1, wherein the total weight of the reinforcing fibers is 55 to 78% by weight in the fiber-reinforced plastic screw member. (6) A patent claim in which the reinforcing fiber bundle is composed of a plurality of filaments of reinforcing fibers, the number of the filaments is in the range of 800 to 30,000, and the fiber bundles are arranged in parallel to form a tubular knitted fabric. A fiber-reinforced plastic screw member according to scope 1. (7) The fiber-reinforced plastic screw member according to claim 6, wherein the weight of the reinforcing fiber bundle is within the range of 0.1 to 10 g/m. (8) The fiber-reinforced plastic screw member according to claim 6, wherein the reinforcing fiber filaments have a diameter in the range of 6 to 28 μm. (9) The number of fiber bundles (number of needles) in the tubular knitted fabric is 3 to 24
A fiber-reinforced plastic screw member according to claim 6, which is woven with. (10) The fiber-reinforced plastic screw member according to claim 1, wherein the fiber-reinforced plastic screw member is a rod-shaped or bolt-shaped screw member partially formed with an external thread. (11) The fiber-reinforced plastic screw member according to claim 1, wherein the fiber-reinforced plastic screw member is a cylindrical or nut-shaped screw member partially formed with a female thread.