JPH0344899B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing an FRP nut.
For more details, please refer to nuts made of reinforced plastic [hereinafter referred to as FRP (FIBER)], which replaces conventional metal nuts.
REINFORCED PLASTICS (abbreviated as REINFORCED PLASTICS)] relates to the method of manufacturing nuts.The lack of strength of plastic nuts is overcome by using long reinforcing fibers such as glass fibers and carbon fibers, which are then impregnated with thermosetting resin to achieve high strength. The present invention relates to a method for manufacturing an FRP nut. [Prior Art and Problems] Metal bolts and nuts have been widely used as fasteners for various products, from assembling steel structures to assembling toys. However, the major drawbacks of metal nuts and bolts are corrosion and, in some cases, electrical and thermal conductivity. In particular, there have been drawbacks to tightening bolts and nuts for artificial reefs that are in constant contact with seawater and sewage, tightening bolts and nuts for marine structures, and insulating bolts and nuts for railroad cars and the like. Titanium has long been known as a metal that can withstand corrosion from seawater, etc., and has been used in the aircraft field due to its light specific gravity, but its high price and poor workability have prevented its use from expanding. I've become accustomed to it. In addition, plastic bolts and nuts have appeared as a countermeasure against corrosion, but these are far from being as strong as metal bolts and nuts, and cannot be used as fasteners for structures. In the field of heavy electrical equipment that requires electrical insulation,
The FRP nut uses prepreg (impregnated with resin and semi-hardened) made of glass fiber yarn cloth, press-forms this to make a plate, and then drills holes and screws. It has been made using That is, after impregnating glass fiber yarn cloth through a resin layer, it is passed through a squeezing roller and adjusted so that the glass fiber content is around 60% glass.
This method involves semi-curing this resin-impregnated glass cloth, stacking dozens of sheets on a heated press, pressing them, and heat-curing them. According to this method, the thickness of the cross is about 0.1 mm to 0.25 mm, so it is suitable for nuts for bolts with a pitch of 1 mm to 2 mm and a bolt size of M10 to M25 or larger. It is possible to make a very strong nut with the cross inserted. However, the disadvantages are that it is necessary to use expensive yarn cloth, and during press molding, it is necessary to stack dozens of resin-impregnated cloths (hereinafter referred to as prepreg) (usually 30 to 80 sheets). Its disadvantage was that it was very time-consuming. As a result of intensive research, the present inventors have completed a method for manufacturing FRP nuts that is far superior in both strength and cost to the above-mentioned pressing method using prepreg. [Means for Solving the Problem] The present invention provides a tensile modulus material impregnated with a thermosetting resin.
A reinforcing fiber for reinforced plastics consisting of long fibers with a tensile strength of 6000 Kg/mm ² or more and a tensile strength of 100 Kg/mm 2 or ^more is placed on a cylindrical or polygonal mandrel using a filament winding machine, and the winding angle is set relative to the rotation axis of the mandrel. and wrap it at an angle of 45° to 87.5°.
Next, this is cut in the axial direction and cut open into a sheet shape to create a molding material, and multiple sheets of this sheet-like molding material are stacked in different directions and press-molded to create a plate-shaped molded product. The outer shape of the nut is made by cutting this plate-shaped molded product, and a hole is drilled and a screw is cut to form the nut. A hole may be made in the plate-shaped molded product before making the outer shape of the nut. [Example] Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1, FIG. 2, and FIG. 4 are for explaining a method for producing a sheet-like molding material, which is a molding material for a nut in the present invention. FIG. 4 shows an outline of an apparatus for producing a sheet-like molding material in the present invention. In the figure, 7 is a mandrel, 8 is a traverse for shaking the twill, 9 is a resin impregnation tank, and 10 is a roving. The present invention uses glass fiber roving (600~10000Tex) or carbon fiber or aramid fiber as needed instead of conventional glass yarn cloth (which requires a weaving process), and instead of weaving it, filament winding is used. The machine impregnates the resin by passing it through the resin impregnation tank 9, while traversing it with the traverse 8, and placing it on the mandrel 7, which is made of a cylinder, ellipse, or polygon, with a constant twill sensitivity (45° to the rotation axis). 87.5°). FIG. 1 shows an intermediate state of a pattern in which a tape-like roving 10 is wound on a mandrel 7 at a constant winding angle. Line 2 consisting of 3 rovings 10
and a return 1 consisting of three rovings 10 form a twill in the opposite direction and are wound so as to overlap each other. The thickness of the roll varies depending on the diameter of the mandrel, but it is usually desirable to have a thickness of 3 to 10 mm so that wrinkles do not occur when the rolled molding material is cut open in the axial direction to form a sheet. It is very important to wind at this constant winding angle. For example, in a so-called parallel-wound molding sheet that is wound at 90 degrees to the rotation axis, if the sheets are lined up in one direction and pressed, the direction perpendicular to the fiber direction is It has only the strength of resin, and when force is applied to it,
This easily results in cracking along the fiber direction. Also, in this case, the lamination is not made up of dozens of layers like in the case of yarn cloth, so when shearing force is applied to the threads of the nut, the resin layer that adheres the glass fibers to each other easily breaks down. This results in delamination. In addition, if the twill angle is 45° or less with respect to the axial direction, when the sheet is used, the twill angle should be θ with respect to the rotation axis.
= It is the same as winding with a twill angle of 90° - 45°,
It has no meaning. Glass fiber is the cheapest reinforcing fiber for making sheet-shaped molding materials, but carbon fiber, aramid fiber, or other materials with a higher modulus of elasticity may be used as needed.
Any plastic reinforcing fiber with a tensile strength of 6000 Kg/mm ² or more and a tensile strength of 100 Kg/mm ² may be used. When the winding angle of the roving 10 becomes an acute angle with respect to the axis of the mandrel 7, it is preferable to provide a pin P on the mandrel 7 as shown in FIG. 2 in order to prevent the roving 10 from slipping. After winding the roving 10 around the mandrel 7 to a predetermined thickness in the above process, the tube formed by winding the roving 10 is cut along a straight line parallel to the axis of the mandrel 7 and expanded to form a sheet. Materials are obtained. A plurality of sheet-shaped molding materials thus formed are stacked in different directions, press-heat-molded to form a plate-shaped product, and the plate-shaped molded product is cut to form the desired external shape of the nut. Drill a hole in it and cut a thread to make a nut. Holes for screws may be made in the plate-shaped molding before making the outer shape of the nut. The feature of the sheet made by filament winding is that the directions of the longs 10 wound on the mandrel in the axial direction and the return direction are opposite to each other as shown in Figure 1, and the mandrel surface is
At the point when it is completely covered, this layer in the opposite direction is 1
Since the entire surface is covered only in pairs, the minimum unit sheet can only be made with two layers of rovings in opposite directions. At this time, a twill angle of 45° to 87.5° is desirable, but as seen in the example, there is no advantage of increased strength even if the laminated sheets are stacked at right angles, so a twill angle of 75° to 85° is optimal. It is. In other words, when winding the filament at a winding angle of 45° to 60°, due to slippage at both ends of the mandrel, it is necessary to hit the pin P and hook the roving 10 being wound onto it (see Figure 2). Further, if the angle is larger than 87.5°, the winding becomes close to parallel, and the effect of pressing each layer against each other as described above is lost. In addition, the formed sheet rolled at a twill angle of 75° to 85° reduces the charge in the fiber direction by 100% during pressing.
However, in the direction perpendicular to the fibers, the advantage is that even if the charge amount in the mold is 80% to 90%, it will spread evenly and cover the entire surface. A thermosetting resin is used as the resin in the resin impregnation tank 9 in order to obtain a plate-shaped molded plate by stacking sheet-shaped molding materials and heat-molding them. Epoxy resin is the easiest to use, but unsaturated polyester resin, vinyl ester resin, and other thermosetting resins can also be used if necessary. [Functions and Effects] This method of producing sheet-shaped molding materials by filament winding was disclosed in
Publication No. 30422, Japanese Patent Publication No. 54-35232, and Japanese Patent Application Publication No. 1988
Although disclosed in Japanese Patent Application Laid-open No. 55-103925 and Japanese Patent Application Laid-open No. 55-103926, the present invention uses a method that uses yarn cloth or roving cloth to perform lamination pressing.
A sheet-like molded product formed by stacking two layers of long fibers that are wound in layers at a constant winding angle, and are symmetrical with respect to a plane where the winding angle is 90 degrees with respect to the axial direction, and are placed above and below each other. Using a plate-shaped molded product made by stacking multiple sheets of material and press forming,
By manufacturing FRP nuts, it is possible to manufacture FRP nuts with strength that exceeds nuts conventionally made by laminating yarn cloth or roving cloth. The reason for this high strength is that the glass fiber roving enters the screw thread, and the next layer of roving with the opposite heel angle holds down the inserted roving layer. This is because layers with opposite winding angles alternately hold down each layer, which is effective in increasing the strength of the delamination that occurs when the screw thread breaks. Furthermore, in the conventional yarn cloth prepreg method, a yarn cloth is produced using a spinning machine, which requires a weaving process, and the yarn itself requires nearly twice the raw material cost as compared to the roving according to the present invention. However, according to the present invention, the weaving process can be omitted, and there is no need for twisting yarn etc. as reinforcing fibers.
Since a thick thread of 2000TEX can be used as TEX, FRP nuts can be manufactured at a very low cost. [Example] 24 glass fiber rovings made of 2000Tex were prepared, 100 parts of epoxy resin (AER354...Asahi Kasei Corporation product number), 75 parts of methyltetrahydrophthalic anhydride, N-(4'-methoxybenzylidene)- By impregnating the resin through a resin layer consisting of 2 parts of 4-alkyl (C _4-7 alkyl group) aniline and passing it through a diaphragm, the resin thickness is 23±1.
Narrow it down to weight%, align it to a width of 6.4cm, and make it a diameter
The material was evenly wound around a 92 cm mandrel at a winding angle of 85 degrees to produce a molding sheet weighing 12 kg/m ² . This sheet was cut into 30 cm squares, three sheets were stacked in the same direction, and a plate was produced by press molding with a press mold (this was named plate A). The molding conditions are
The temperature was 125° C. for 1 hour, and the pressing pressure was 50 kg/cm ² . On the other hand, the central one of the three sheets was stacked perpendicularly to the fiber direction and press-formed under the same conditions as above to create a board (this was named board B). The thickness of the molded plates was 15 mm and 15.5 mm, respectively. A 22cm square nut was cut out from this plate, and a thread for an M10 bolt (pitch 1.5mm) was tapped. Similarly, use a commercially available yarn cloth laminate (thickness 15
mm, 64 sheets of yarn cloth were laminated and prepreg was pressed) to produce a nut under the same conditions as above (this was named C plate). In order to measure these strengths, a round bar (diameter
10φ) was machined with an M10 (pitch 1.5mm) screw thread using a die to create an FRP nut (length 120mm).
mm). A tensile strength test was conducted using these. Figure 3 is a schematic diagram showing the strength test method, where 3 is a bolt, 4 is a nut for testing, 5 is a test jig, and 6 is a schematic diagram showing a strength test method.
is a spacer for stopping the nut, and the test jigs 5 and 5 are pulled in opposite directions to perform the test. The results were as shown in Table 1.

【table】

[Table] As a result of the above test, in the case of the A plate prepared by the method of the present invention, up to three out of five test specimens broke, indicating that the nut strength was sufficient. On the other hand, all but one example of the samples cut from the B board had crushed screw threads, but the average nut strength of 1.48 tons was obtained, which is almost the same as the average nut strength of the A board, 1.54 tons. The nut strength is not affected much. If all the sheets are stacked and pressed in the fiber direction of the sheets, a product with slightly better strength can be obtained. In addition, in the case of nuts made from press-formed products (C plate) using prepreg made from yarn cloth, which were produced as a comparison, the average value was as low as 1.15 tons, and all of the nuts were damaged due to crushed threads. As described above, the product made by the method according to the present invention
The advantages of FRP nuts are obvious.

[Brief explanation of drawings]

FIG. 1 shows an intermediate state of a pattern on a mandrel wound by the method of the present invention. FIG. 2 is a conceptual diagram when the winding angle becomes an acute angle with respect to the axis. FIG. 3 is a schematic diagram showing a method for testing the strength of nuts made by this method. FIG. 4 shows an outline of an apparatus for producing a sheet-like molding material in the present invention. 1... Going, 2... Returning, 3... Bolt for testing, 4... Nut for testing, 5... Test jig, 6... Spacer, 7... Mandrel, 8
... Traverse, 9 ... Resin impregnation tank, 10 ... Roving.

Claims (1)

[Claims] 1 Tensile modulus 6000Kg/impregnated with thermosetting resin
A reinforcing fiber for reinforced plastics consisting of long fibers with a length of mm ² or more and a tensile strength of 100 Kg/mm ² or more is placed on a cylindrical or polygonal mandrel using a filament winding machine, and the winding angle is 45 with respect to the rotation axis of the mandrel. Wrap it around an angle of 87.5° to 87.5°, then cut it in the axial direction and cut it open into a sheet to create a molding material.Multiple pieces of this sheet-like molding material are stacked in different directions and press-molded. A method for producing an FRP nut, which is characterized in that a plate-shaped molded product is created using a metal mold, and the plate-shaped molded product is cut, holes are drilled, and screws are cut to form a nut.