JPS5814931B2 - Manufacturing method for fiber-reinforced resin coil springs - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a coil spring using a fiber wire and a thermosetting resin.

In general, resin springs have various characteristics compared to metal springs, such as lower specific gravity, higher strength, corrosion resistance, and chemical resistance.
They can be used in places where metal springs are inconvenient, and depending on the degree of spring properties, they can be a promising alternative.

This trend is particularly noticeable in automobiles, etc., which have become lighter in weight in recent years.

However, because resin springs possess only a small amount of elastic energy required for springs, conventional springs lacked practicality.

The present invention was made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a method for manufacturing a coil spring impregnated with a thermosetting resin that can retain large elastic energy by using a fiber wire.

The present invention will be explained below with reference to illustrated embodiments.

A fiber wire such as carbon fiber or glass fiber (hereinafter simply referred to as fiber) is used as the material, and the fiber wire diameter is selected according to the required spring characteristics.

Then, as shown in FIG. 1, a plurality of the fiber wires selected in this manner are bundled and formed to obtain the required wire diameter of the coil spring.

That is, in order to increase the wire diameter of the coil spring, the number or wire diameter of the fiber wire 1 is changed.

On the other hand, a certain amount of methyl ethyl ketone peroxide as a curing agent and cobalt naphthenate as a curing accelerator are added to the thermosetting resin, and the mixture is mixed and stirred to obtain a thermosetting resin solution.

As the thermosetting resin, polyester or epoxy resin is used.

These resins have high tensile strength after molding and are excellent in performance, so they are suitable for springs.

Then, the fiber bundle 2 bundled as described above is immersed in the thermosetting resin solution to impregnate it.

Next, as shown in FIG. 2, this fiber bundle is twisted and pulled in either the left or right direction to form a resin-impregnated twisted fiber bundle 3.

This twisting squeezes out some of the resin impregnated into the fiber bundle, but the fiber content increases.
The load becomes higher.

Also, since the spring characteristics vary depending on the amount of twist, it is necessary to determine the amount of twist depending on the desired spring characteristics.

Subsequently, as shown in FIG. 3, the water-soluble polyvinyl alcohol tape 4 is wound in a direction opposite to the twisting direction of the fiber bundle 3.

This prevents the fiber bundle 3 from becoming untwisted.

Next, as shown in FIG. 4, a fiber bundle 5 in which a water-soluble polyvinyl alcohol tape 4 is wound around a core bar 11 made of metal or resin in which coiled grooves 10 of a constant pitch are formed is inserted into the coiled grooves 10. Coil it into a coil by winding it along the .

The water-soluble polyvinyl alcohol tape 4 is formed into a coil shape while being wound.

If the coiling direction is opposite to the twisting direction of the fiber bundle 3 when forming a compression spring, and in the same direction as the twisting direction when forming a tension spring, a spring with high load characteristics can be formed.

After wrapping the core metal 11 a certain number of times, the front and rear terminals are cut off, and stoppers (not shown) are attached to both terminals to prevent them from opening, and are immovably fixed.

Next, it is heated at a temperature of around 100°C for a certain period of time.

By this heating, the fiber bundle 5 is solidified, and a coiled spring along the coiled groove 10 of the core metal 11 is formed.

Subsequently, the coiled spring formed in this manner is removed from the core metal 11 and left in water.

As a result, the water-soluble vinyl alcohol tape 4 is naturally dissolved and removed, and the thermosetting resin-impregnated fibers are exposed in a coiled form.

A coil spring is thus obtained.

The compression spring seat can be easily formed by the following method.

That is, as shown in FIG. 5, both ends 7 of the coil spring 6 are fixed using fixing jigs 13, 13, which are formed into upper and lower halves and provided with a coil groove 12, 12 in which the coil spring 6 fits. , 7 are fixed so that one turn is in a free state.

When left in a slightly high temperature atmosphere in this state, the free ends 7.7 at both ends contract inward to form seats 8, 8 as shown in FIG.

This is because residual torsional stress is imparted by twisting the fiber bundle, and if the fiber bundle is temporarily fixed with resin at a low temperature and then left in a high temperature atmosphere, the residual stress will be released and the fiber will untwist.

Therefore, the free ends 7, 7 are pulled toward the center of the spring by the untwisting force, and as a result, the pitch is reduced and the seats 8, 8 are formed in close contact.

After the resin is completely cured in a high-temperature atmosphere, no pitch fluctuation is observed even in a high-temperature atmosphere again.

Based on the above formed coil, we investigated the spring constant when the coil wire diameter is 5 mm and the number of turns is 4.5.We found that when a straight glass fiber bundle is formed into a coil as shown in Figure 1, Spring constant is 0.
32, but as shown in FIG. 2, the spring constant which was twisted was 0.79, which was a significantly large spring constant.

Furthermore, when carbon fiber bundles were used, the value was almost twice as high.

As is clear from the above explanation, according to the method of manufacturing a thermosetting resin coil spring according to the present invention, a fiber bundle impregnated with a thermosetting resin is twisted and then formed into a coil shape. A spring with high load can be obtained.

Moreover, the manufacturing method is very simple and the manufacturing cost can be reduced.

However, the compression spring has the characteristic that the seats at both ends can be easily formed by leaving only both ends in a free state and heating in a high temperature atmosphere.

[Brief explanation of the drawing]

Figures 1, 2, 3, and 4 are explanatory diagrams showing the process order of manufacturing a coil spring according to the present invention, and Figure 5 shows a method for forming a seat of a compression spring according to the present invention. The explanatory diagram, FIG. 6, is a front view of a compression spring obtained by the method of FIG. 5. 1...Glass fiber wire, 2...Glass fiber bundle,
3... Resin-impregnated twisted fiber bundle, 4... Water-soluble polyvinyl tape, 5... Tape-wound fiber bundle, 6... Coil spring, 7... End, 8... Seat, 11... Core metal, 13... Fixing jig.

Claims (1)

[Claims] 1. Glass or carbon fiber wires are bundled and impregnated with a thermosetting resin, the resin-impregnated fiber bundle is twisted, and then a water-soluble polyvinyl alcohol tape is applied in a direction opposite to the twist direction of the fiber bundle. The fiber bundle around which the tape has been wound is wound around a core metal having a coiled groove formed therein along the coiled groove, and then the fiber bundle is wound around the core metal by heat treatment. A method for manufacturing a fiber-reinforced resin coil spring, which comprises solidifying a fiber bundle, forming it into a coil spring, and then leaving it in water. 2. Bundle glass or carbon fiber wires and impregnate them with a thermosetting resin, then twist this resin-impregnated fiber bundle, and then wrap a water-soluble polyvinyl alcohol tape in the opposite direction to the twist direction of the fiber bundle. , the fiber bundle around which the tape has been wound is wound around a core metal in which a coiled groove is formed, and then heated to solidify the fiber bundle wound around the core metal and formed into a coil spring; This fiber-reinforced resin is characterized in that the coil spring is removed from the core bar, attached to a fixing jig with approximately one turn at both ends free, and heated at high temperature to form a seat for the compression coil spring. How to manufacture coil springs.