JPH01249326A - Manufacture of fiber-reinforced resin spring - Google Patents

Abstract

PURPOSE:To enable manufacture of a fiber-reinforced resin spring which makes the most use of a merit of thermoplastic resin, impregnation of the resin into spaces among reinforced fibers and arrangement into a molding tool easy and is superior in productivity by a method wherein a reinforced fiber bundle coated with thermoplastic resin is oriented and arranged within a molding tool, which is pressurized after heating at a temperature of at least the molding point of the thermoplastic resin and the pressurization is continued down to a temperature of the melting point of the thermoplastic resin or less. CONSTITUTION:A reinforced fiber having fixed strength and thickness is coated with thermoplastic resin by making use of an ordinary extruding and tension coating device under a state of a fiber bundle obtained by bundling a large number of the reinforced fibers. The obtained resin coated reinforced fiber bundle is bundled into a plurality of bundles and oriented and arranged within a molding tool. The orientation and arrangement are performed so that the orientation becomes fixed orientation which necessitates fiber-reinforcement by corresponding to a form of a spring and stress. Then the resin coated reinforced fiber bundle oriented and arranged within the molding tool is heated at a temperature of at least the melting point of the thermoplastic resin and pressurization is begun. It is necessary that the pressurization is continued until at least a temperature becomes a melting point of the thermoplastic resin or less.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a fiber reinforced resin spring. More specifically, the present invention relates to a method for manufacturing a fiber-reinforced resin spring using a thermoplastic resin, which has good productivity and allows easy arrangement and placement of reinforcing fibers in a mold.

(Prior Art) In recent years, fiber reinforced resin springs (FRP springs) have been developed and put into practical use because they are lighter than steel springs and have the characteristics of high corrosion resistance and high strain.

Most of these conventional fiber-reinforced resin springs are molded using reinforcing fibers such as carbon fibers and glass fibers, and thermosetting resins such as epoxy resins as matrix resins.

In the case of this conventional resin spring, since a thermosetting resin is used as the matrix resin, the curing time is long and productivity is not good, and the tDl resin has low ductility, so it does not have sufficient spring properties. There was a problem that I could not get it.

Generally, for fiber reinforced resin materials, matrix tM
The use of thermoplastic resins has been considered to overcome the drawbacks of conventional thermosetting resins used as II. The reason for this is that in the case of thermoplastic resins, curing is completed by solidification by cooling, which provides good productivity, and the flow of the resin is also large.

From this point of view, fiber-reinforced resin springs with a thermoplastic resin matrix are expected to provide resin springs with unprecedented high properties.However, on the other hand, there are still issues to be solved regarding the use of thermoplastic resins. There are several important problems that need to be solved, and these problems have remained unresolved, so that it has not yet been put into practical use.

(Problems to be Solved by the Invention) When attempting to manufacture fiber-reinforced resin springs using thermoplastic resin, the first and foremost problem is that the conventional method of using thermosetting resin as a matrix cannot be adopted. be. In other words, when impregnating reinforcing fibers with resin, thermoplastic resins require high heating temperatures and have a high viscosity when melted, so they cannot be completely impregnated with conventional thermosetting resins in an impregnating bath. If you try to wrap reinforcing fibers impregnated with resin around a mold of a predetermined shape during molding, the impregnated reinforcing fibers will break and break at room temperature. If the heating operation is performed in such a way as to prevent the formation of the material, the arranging operation itself becomes difficult.

For this reason, a new manufacturing method for thermoplastic fiber-reinforced resin springs has been developed that takes advantage of the advantages of thermoplastic resin, but also makes it easier to impregnate the resin between reinforcing fibers and place it in the mold. Realization was strongly desired.

This invention was made based on the above-mentioned circumstances, and is a new fiber-reinforced resin material that solves the conventional problems.
(Means for Solving the Problems) In order to achieve the object described in item 1, the present invention is directed to providing a method for manufacturing a reinforcing fiber bundle when manufacturing a fiber-reinforced resin spring. Covering with plastic resin, orienting and arranging this coated fiber bundle in a mold,
After heating to a temperature above the melting point of the thermoplastic resin, pressure is applied,
The present invention provides a method for manufacturing a fiber-reinforced resin spring, characterized in that this pressurization is continued to a temperature below the melting point of the thermoplastic resin.

In addition, in the method of the present invention, as the method 7B, a plurality of spring molded bodies manufactured by the above method are placed in a mold, heated to a temperature equal to or higher than the melting point of the thermoplastic resin, and then pressurized. It also includes a method in which the reinforcing fiber bundles coated with a thermoplastic resin are subjected to secondary processing and arranged in a mold.

The manufacturing method of the present invention will be explained in detail next. First, the reinforcing fibers such as carbon fibers and glass fibers are coated with resin using a large number of reinforcing fibers having a predetermined strength and thickness, for example, a thickness of 5 to 30 μm. A fiber bundle of 500 to 12,000 fibers is coated with a thermoplastic resin using a conventional extrusion or tension type coating device.

The thermoplastic resin can be selected as appropriate depending on the intended use of the spring and the required spring characteristics, and suitable materials such as polyamides such as nylon, polyester, and polyolefin resins can be used. .

Further, the amount of the II1 fat to be coated can be determined as appropriate so as to have enough flexibility to allow alignment within the mold.

The obtained resin-coated reinforcing fiber bundles are then bundled into a plurality of bundles and arranged in a mold. The coating with the resin described in item 1 coats the outer peripheral surface of the fiber bundle without impregnating the single fibers with resin as in the conventional method, so it is extremely easy to orient the fiber bundle in the mold. It can be done.

This orientation arrangement is carried out so that fiber reinforcement is required in a predetermined orientation corresponding to the shape and stress of the spring. For example, in the case of a coil spring, the resin-coated reinforcing fibers are The bundle can be oriented and arranged by winding it. Alternatively, in the case of a disc spring, for example, as shown in FIG. By winding the reinforcing fiber bundle (3) around the fiber and adjusting its thickness (1) within a predetermined range, it is possible to orient and arrange the reinforcing fiber bundle (3) covered with one finger in the circumferential direction.

In this orientation arrangement, resin-coated reinforcing fiber bundles that have been subjected to secondary processing such as mating and weaving can be arranged in advance.

Next, the resin-coated reinforcing fiber bundles oriented and arranged in the mold are heated to a strength higher than the melting point of the thermoplastic resin, and pressurization is started. Since the thermoplastic resin becomes a :/B molten state by heating above the melting point -L, by applying pressure in this state, the resin can be sufficiently impregnated between the single fibers in the fiber bundle. It goes without saying that the heating intensity and pressurizing conditions can be appropriately selected in consideration of the type of thermoplastic resin used, required spring characteristics, etc.

This pressurization needs to be continued at least until the temperature reaches the melting point of the thermoplastic resin or lower.

This molding process by heating and pressurizing ends with solidification by cooling, so there is no need for several hours of curing (polymerization) as in the case of conventional thermosetting resins, making it highly productive and producing the desired resin spring. can be manufactured.

In addition, if the shape of the spring is complicated or if a complicated orientation is required, it can be divided into several shapes by the method described above, taking advantage of the advantage of using one thermoplastic resin. Temporary molded body in a state where it is! ! ! built,
This is rearranged in the mold so that it has a predetermined shape, and similarly heated to a temperature higher than the melting point of the thermoplastic resin and pressurized.
A fiber-reinforced resin spring can also be manufactured by applying pressure to a temperature below this temperature.

Next, examples of the present invention will be shown, and further a manufacturing method of the present invention will be explained.

Implementation @l Tensile strength 360kirf/round 2, tensile modulus 23000
1qr f/+u”, thickness 7 μrn PAN
The outer peripheries of 6,000 carbon fibers were coated with 12 nylon using a wire coating device. In this case, the ratio of fiber to nylon resin was 63:37 by weight.

The obtained coated fiber bundle was further bundled into 6.1 bundles and wound around a coil mold. It was heated in a far-infrared furnace at a temperature of 210°C for 5 minutes, and immediately after being removed from the furnace, it was pressurized with a press machine at a pressure of 20 kg/-.
Pressurization was continued while cooling to 10°C.

After depressurizing and demolding at a temperature of 110'C, the coil spring was taken out. The obtained spring has 3 strands of wire.
uAa X 9.5 ii+ square rod-shaped,
The weight of a steel spring of the same size was 175.

Example 2 Sixteen fiber bundles coated with the same 12-17 resin as in Example 1 were braided, and four of the resulting braids were heated and pressure-molded in the same manner as in Example 1 to form a predetermined shape. I got a coil of J2.

Example 3 A fiber bundle coated with the same 12 nylon resin as in Example 1 was wrapped circumferentially around the mold half as shown in Figure 1, and heated in the same manner as in Example 1. Apply pressure to the specified plate b
I got it.

(Effects of the Invention) As explained in detail above, the present invention provides a method for manufacturing fiber-reinforced resin springs using a thermoplastic resin that has extremely good productivity and allows for easy arrangement of strong fibers in a mold. is provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional perspective view showing an example of the orientation arrangement of reinforcing fiber bundles in the manufacturing method of the present invention. 1... Molding mold 2... Shaft part 3... Resin-coated reinforcing fiber bundle

Claims (3)

[Claims] (1) In manufacturing fiber-reinforced resin springs, reinforcing fiber bundles are coated with thermoplastic resin, the coated fiber bundles are oriented in a mold, heated to a temperature equal to or higher than the melting point of the thermoplastic resin, and then pressurized. A method for manufacturing a fiber-reinforced resin spring, characterized in that this pressurization is continued to a temperature below the melting point of the thermoplastic resin. (2) A plurality of spring molded bodies manufactured by the method described in claim (1) are placed in a mold, heated to a temperature equal to or higher than the melting point of the thermoplastic resin, and then pressurized, and this pressurization is applied to the thermoplastic resin. A method for producing a fiber-reinforced resin spring characterized by its ability to last up to a temperature below its melting point. (3) The method for producing a fiber-reinforced resin spring according to claim (1) or (2), wherein reinforcing fiber bundles coated with thermoplastic resin are subjected to secondary processing and arranged in a mold.