JPH07227920A - Coil spring made of fiber-reinforced resin and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the surface of a coil elemental wire of a coil spring made of a fiber-reinforced resin from being brought into contact with the terminal part of the elemental wire. CONSTITUTION:A coil elemental wire is molded by winding up a prepreg 4 prepd. by impregnating a reinforcing fiber with a resin on a mandrel 5. The prepreg 4 is formed into a trapezoidal shape wherein sides 4c and 4c corresponding to the terminal part of the coil elemental wire become oblique sides and this prepreg is rolled up on the mandrel 5 from a long base 4a side. As the result, both ends of the molded coil elemental wire become a head-cut conical shape. In a coil spring formed by winding up spirally this coil elemental wire, there exists no possibility that the surface is damaged even if the terminal part of the elemental wire is brought into contact with the facing elemental wire part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced resin coil spring formed by spirally winding a wire made of resin reinforced with carbon fiber or the like, and a method for manufacturing such a coil spring.

[0002]

2. Description of the Related Art Conventionally, in order to reduce the weight of a coil spring used in, for example, an automobile suspension device, a valve lifter or the like, a fiber reinforced resin coil spring has been proposed instead of a metal coil spring.

For example, Japanese Unexamined Patent Publication No. 56-18136 discloses such a coil spring made of fiber reinforced resin and a method for manufacturing the coil spring. The coil spring is unidirectionally impregnated with a thermosetting resin. Manufactured from a sheet of carbon or graphite fiber (prepreg).

That is, for example, three sheets of the above-mentioned sheet material are continuously wound around a mandrel to form a hollow spring wire (element wire) consisting of three layers. A desired coil spring is obtained by spirally winding another mandrel formed with a spiral groove along the groove and heating and hardening the spiral mandrel.

Since each of the three sheet materials is formed in a rectangular shape having the same length, the end surface of the spring wire obtained by winding these on a mandrel is a plane perpendicular to the axis.

FIG. 1 shows a coil spring 02 obtained by spirally winding such a spring wire 01. The end face perpendicular to the axis is the coil spring shown.
It remains as a plane perpendicular to the axis c of the spring wire 01, as shown as the end face a at the upper end of 02.
After winding, the spring wire may be cut by the required number of windings, but even in this case, the spring wire is usually cut at a right angle to its axis, and therefore the state of the end face a does not change. Alternatively, as shown in the lower end of the illustrated coil spring 02, the bearing surface 03 may be formed by grinding or the like. Even if such bearing surface grinding is performed, a part of the right angle end surface is formed. Remains as the end face b.

The left side of FIG. 1 shows the coil spring 02 in the unloaded state, and the right side shows the coil spring 02 when a compressive load is applied. Such a compression coil spring absorbs the load energy by utilizing the elastic force of the spring wire by contracting due to a compressive load. In many cases, the spring wire portions adjacent to each other in the axial direction of the coil are in close contact with each other. The state in which the energy is absorbed is used as the maximum energy absorption state.

[0008]

When a load is gradually applied to the coil spring 02, the contact between the spring wire portions generally starts from the end portion (see the right side of FIG. 1). By the way, as described above, each end has the end faces a and b perpendicular to the axis c of the spring wire 01, and the edge 04 is formed by the end faces a and b. Therefore, the edge 04 is the surface of the counterpart spring wire portion. There is a problem that the surface is easily scratched by the edge 04 due to contact, and by repeating this, the scratched portion becomes a fatigue starting point, and the coil spring is damaged in a relatively short service life.

In order to prevent such a problem, it is conceivable to chamfer or round the end portion shape with a baby grinder or the like, but it is a single piece machining by hand and the cost is high.

Accordingly, the present invention provides a coil spring made of a fiber-reinforced resin, which is inexpensive and prevents the surface of the spring wire from being damaged by the edge of the terminal even when the terminal contact occurs due to a load, and such a coil spring. The present invention intends to provide a method capable of manufacturing the resin at low cost.

[0011]

Therefore, in the coil spring made of fiber reinforced resin according to the present invention, a coil wire formed by winding a plurality of layers of a prepreg in which a reinforcing fiber is impregnated with resin is spirally wound. By turning the prepreg into a trapezoidal shape in which the side corresponding to the end of the coil wire is a hypotenuse, the end of the coil wire is tapered toward the tip to form a substantially frustoconical shape. It is formed on.

In this fiber-reinforced resin coil spring, even if the terminal contact as described above occurs due to the load, the end of the wire is aligned with the conical surface of the end to engage the surface of the wire. Even if they come into contact with each other, and even if the corner portions formed on both sides of the conical surface come into contact with the surface of the wire, since the corners have a shallow obtuse angle, the surface of the wire is not substantially damaged. Absent.

Moreover, the shape of the truncated conical wire terminal is
It is obtained by winding a trapezoidal prepreg, and since it is not necessary to end-process each product after coil spring molding, manufacturing is easy and cost is reduced.

The above fiber-reinforced resin coil spring is
A prepreg impregnated with a resin in a reinforcing fiber is wound around a mandrel in a plurality of layers to form a coil wire, and the coil wire is spirally wound to manufacture a coil spring made of a fiber-reinforced resin. , A trapezoidal shape in which a side corresponding to an end of the coil wire is a slanted side that is inclined inward in the longitudinal direction from a portion that is radially inward when wound around the mandrel to a portion that is radially outward. As a result, it can be manufactured at low cost.

[0015]

2 to 6 show an embodiment of the present invention.
5 and 6 are side views of the completed fiber-reinforced resin coil spring 1, and FIG.
FIG. 6 shows a state when a compressive load is applied.

The coil spring 1 is formed by spirally winding a coil wire 2, and both ends 3 and 3 of the coil wire 2 are formed in a truncated cone shape which is tapered toward the tip as shown in the drawing. Has been done.

As shown in FIG. 2, the coil wire 2 is formed by winding a prepreg 4 around a mandrel 5 in several layers and winding it. The prepreg 4 includes a bottom side 4a, an upper side 4b parallel to the bottom side 4a and relatively short, and these sides 4a,
It has a trapezoidal shape surrounded by oblique sides 4c and 4c connecting both ends of 4b, and sides 4a and 4b are wound around the mandrel 5 in parallel with the axis of the mandrel 5 and from the bottom side 4a side. The hypotenuses 4c, 4c are inclined at substantially the same angle with respect to the base 4a.

By winding the prepreg 4 around the mandrel 5 in this manner, a hollow coil wire 2 as shown in FIG. 3 is formed. The coil wire 2 is gradually wound on both ends of the coil wire 2 as it is wound. The hypotenuses 4c, 4c approaching the center in the longitudinal direction form frustoconical end portions 3, 3. Each end 3 of the coil wire 2 in FIGS. 5 and 6 is formed in this way, and is not formed by performing a special end processing.

The coil wire 2 is then wound around a cylindrical mold 6 as shown in FIG. A spiral groove 7 is formed on the outer peripheral surface of the mold 6, and the coil wire 2 is spirally wound around the outer peripheral surface of the mold 6 while being fitted in the groove 7. Then, in this state, heat treatment is applied to the prepreg 4
The coil spring 1 as shown in FIG. 5 is obtained by hardening the resin of FIG.

If a flexible mandrel 5 is used and the coil wire 2 in which the mandrel 5 is left as it is is wound around the mold 6, the coil wire 2 is formed.
It is advantageous in preventing buckling of. As the material of the flexible mandrel, nylon, silicon, Teflon, polymethylpentene and the like can be used, but polymethylpentene is preferable from the viewpoint of handleability and heat resistance.

The prepreg 4 is formed by cutting a sheet-like body obtained by impregnating reinforcing fibers with an uncured resin in advance into a trapezoidal shape as described above. As the reinforcing fibers, for example, carbon fibers are used. The carbon fiber referred to here is a carbon fiber in the sense of being commonly used, and acrylic, pitch,
Any of rayon type may be used. From the viewpoint of compressive strength, acrylic carbon fiber is particularly preferable.

Further, other fibers such as glass fiber and aramid fiber may be used, or these high elongation fibers may be used in combination with the above carbon fibers depending on the use of the coil spring.

The matrix resin with which the reinforcing fibers are impregnated is a thermosetting resin or a thermoplastic resin. The thermosetting resin is an epoxy resin, a polyimide resin, an unsaturated polyester resin or the like, and the thermoplastic resin is a polysulfone or a polyether. Sulfone, polycarbonate, polyetherketone, polyetheretherketone, aromatic polyamide, polyetherimide, thermoplastic polyimide and the like are used.

In the coil spring 1 according to this embodiment, as described above, the end 3 of the coil wire 2 is formed in a truncated cone shape, so that the coil spring 1 is compressed by a compressive load as shown in FIG. Even if the end portion 3 is compressed until it comes into contact with the end, the conical surface portion 3a of the end portion 3 comes into contact with the wire portion 2a in a state where the conical surface portion 3a is along the surface of the wire portion 2a, which may damage the surface of the wire portion 2a. There is no. Moreover, the corner portions 3b and 3c formed on both sides of the conical surface portion 3a (FIG. 5)
Since each of them has a large included angle and does not form a sharp edge, even if the corner portions 3b and 3c come into contact with the wire portion 2a, the surface thereof is hardly damaged. Therefore, the coil spring 1 hardly breaks from the scratched portion due to the end of the wire as a fatigue starting point.
Durability is significantly improved.

Moreover, the frustoconical end 3 is formed by winding the trapezoidally cut prepreg 4 around the mandrel 5, and it is not necessary to end-process each product after coil spring molding. This coil spring 1 can be manufactured at a low cost with man-hours which are almost the same as those of the conventional one.

7 to 9 show another embodiment of the present invention. In these figures, the same parts as those in the above embodiment are designated by the same reference numerals.

FIG. 7 is a view similar to FIG. 2, but in this embodiment, the hypotenuses 4c and 4c on both sides of the prepreg 4 are curved in an arc shape at the portion 4d on the upper side 4b side. . When this prepreg 4 is wound around the mandrel 5 in the same manner as described above, the arcuate portion 4d of the prepreg 4 causes the end portion 3 of the coil wire 2 to be attached to the end 3 of the prepreg 4, as shown in FIGS. , A portion 3d having an arcuate vertical cross-sectional shape is formed. The outer surface of the arcuate portion 3d having a vertical cross section has a spherical shape and is continuously and smoothly connected to the peripheral surface of the coil wire 2, so that the surface of the mating wire on the mating side can be more effectively scratched at the time of contact with the terminal. Can be prevented.

In each of the above embodiments, one prepreg 4 was wound around the mandrel 5 to form the coil wire 2. However, as shown in FIG. 10, a plurality of trapezoidal prepregs 4a and 4b are formed. , 4c ... may be sequentially wound around the mandrel 5.

The attached drawings are qualitative to explain the present invention. Further, the number of turns of the coil spring 1 and the like can be appropriately increased / decreased, and therefore, the present invention is not limited to the illustrated embodiment, and it goes without saying that various modifications can be made within the scope of the present invention.

[0030]

According to the present invention, the durability of the coil spring can be improved by preventing damage to the coil wire of the fiber reinforced resin coil spring due to the end of the coil wire. A fiber-reinforced resin coil spring can be manufactured at low cost without increasing the number of steps.

[Brief description of drawings]

FIG. 1 is a side view showing an unloaded state and a loaded state of a conventional fiber-reinforced resin coil spring.

FIG. 2 is a plan view for explaining a coil wire forming process in an example of the present invention.

FIG. 3 is a diagram showing a molded coil wire.

FIG. 4 is a perspective view for explaining a step of spirally winding a coil wire.

FIG. 5 is a side view showing an unloaded state of a product coil spring.

FIG. 6 is a side view showing a loaded state of the coil spring.

FIG. 7 is a plan view similar to FIG. 2, showing another embodiment of the present invention.

FIG. 8 is a diagram showing a coil element wire in the example.

9 is a partially enlarged view of FIG.

FIG. 10 is a plan view similar to FIG. 2, showing still another embodiment of the present invention.

[Explanation of symbols]

1 ... Coil spring, 2 ... Coil wire, 3 ... End part, 4
... prepreg, 5 ... mandrel, 6 ... mold, 7 ... groove.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical indication location B29L 31:00 (72) Inventor Kazushi Oguri 234 Toho Rayon, Takaishi, Uechikari, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture Mishima Plant Co., Ltd. (72) Inventor Kazunobu Wakita 234 Takaishi, Kamichikari, Nagaizumi-cho, Sunto-gun, Shizuoka Toho Rayon Co., Ltd. Mishima Plant

Claims (4)

[Claims] 1. A coil spring made of fiber reinforced resin, which is formed by spirally winding a coil wire formed by winding a plurality of layers of a prepreg in which reinforcing fibers are impregnated with a resin, and forming the prepreg into the coil wire. A coil spring made of a fiber-reinforced resin, characterized in that the coil wire end portion is formed into a substantially truncated cone shape with its end facing toward the tip by forming a trapezoidal shape whose side corresponding to the end portion of the coil spring is a hypotenuse. . 2. The frusto-conical coil wire end portion comprises:
The fiber-reinforced resin coil spring according to claim 1, wherein the coil spring has an arcuate vertical cross-section at least partially. 3. A method for producing a coil spring made of fiber-reinforced resin by winding a plurality of layers of a prepreg in which reinforcing fibers are impregnated with a resin, to form a coil wire, and spirally winding the coil wire. In the prepreg, the side corresponding to the end of the coil wire is a slanted side that is inclined inward in the longitudinal direction from a portion that is radially inward when wound around the mandrel to a portion that is radially outward, A method for manufacturing a coil spring made of fiber reinforced resin, which is characterized by forming a trapezoid. 4. The method for manufacturing a fiber reinforced resin coil spring according to claim 3, wherein the shape of the hypotenuse in at least a portion on the outer side in the radial direction of the prepreg has an arc shape.