JPH0261667B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an FRP leaf spring having a center hole and a method for manufacturing the same.

For example, a stacked leaf spring device used for vehicle suspension is constructed by stacking a plurality of leaf springs in the thickness direction. FIG. 1 shows an example of this, in which a plurality of leaf springs 1 are stacked together and a center bolt 2 is inserted through the intermediate portion in the longitudinal direction to stop the leaf springs 1 from moving. 3 and 3 are eyepiece members to be attached to the vehicle body side.

Recently, however, there has been a strong desire for lighter leaf springs made of FRP (fiber-reinforced synthetic resin) to be put into practical use instead of conventional steel leaf springs. FRP leaf springs mainly contain reinforcing fibers along the longitudinal direction, which are hardened with matrix resin. like this
When an FRP leaf spring is used in a stacked leaf spring device such as the one illustrated in FIG. 1, it may be necessary to provide a hole through which the center bolt 2 is inserted, for example.

FIG. 2 shows a conventional FRP leaf spring having a center hole 5. That is, conventionally, the center hole 5 is generally formed by machining with a drill or the like after forming the leaf spring, but in this case, the reinforcement of this part where the reinforcing fibers are cut by the center hole 5 is reduced. In addition, cracks tend to occur along the fibers starting from the center hole 5, and since the reinforcing fibers are unidirectional, the cracks tend to propagate along the direction of the fibers.

The present invention was made based on the above circumstances, and
The purpose is to provide an FRP leaf spring that can prevent the occurrence of cracks in the vicinity of the center hole, as well as prevent the growth of cracks, and a method for manufacturing the same.

The gist of the present invention is that in an FRP leaf spring that contains reinforcing fibers that are continuous in the longitudinal direction of the leaf spring and has a center hole, the reinforcing fibers are arranged on one side on the left and right sides of the center hole for each layer or layers. The FRP leaf spring is characterized by being stacked alternately in the thickness direction of the leaf spring.

According to the above FRP leaf spring, since the reinforcing fibers are not cut around the center hole, it is possible to prevent the occurrence of cracks from the center hole. In addition, even if a crack were to occur, the reinforcing fibers are alternately distributed to the left and right before and after the center hole and intersect, which prevents the crack from propagating along the fibers and maintains durability. Ru.

Furthermore, the gist of the present invention is to provide a method for manufacturing an FRP leaf spring in which a reinforcing fiber bundle continuous in the longitudinal direction and impregnated with resin is passed through an alignment guide member, and then wound around a mold and cured. Before winding the reinforcing fiber bundle around a mold, the alignment guide member is rotated in a plane intersecting the traveling direction of the reinforcing fiber bundle to narrow the width of the reinforcing fiber bundle and avoid the pin for forming the center hole. There is also a method for manufacturing an FRP leaf spring in which the FRP leaf spring is wound around the above-mentioned mold, and the direction in which the pins are avoided is alternately changed for each layer or layers.

According to this manufacturing method, the width of the reinforcing fiber bundle is narrowed by rotating the alignment guide member, and the distances between each fiber can be narrowed to be approximately equal to each other in order to avoid the pin for forming the center hole. In other words, for example, if the reinforcing fiber bundle is forcibly pressed in the horizontal direction by a pressing member that slides in the horizontal direction, or if the mold is slid in the horizontal direction, the width is narrowed to avoid the center forming pin. In this case, some of the reinforcing fibers come into contact with each other, and the resin is not sufficiently distributed between the reinforcing fibers, resulting in cracking along the direction of the reinforcing fiber bundle. However, according to the method of the present invention, such problems occur. Never.

An embodiment of the present invention will be described below with reference to FIGS. 3 to 5. The FRP leaf spring 1 schematically shown in FIG. 3 contains longitudinally continuous reinforcing fibers 6a, 6b, and has a center hole 5. These reinforcing fibers 6a..., 6b... are alternately distributed to the left and right sides of the center hole 5 in one layer or multiple layers and stacked in the thickness direction of the leaf spring.
Generally, it is hardened with a thermosetting matrix resin 7.

To obtain the FRP leaf spring 1 described above, an apparatus shown in FIG. 4 is used as an example. In the figure, code 1
Reference numeral 0 denotes a resin impregnation tank in which matrix resin 7' before curing is accommodated. Further, 11 is a mold, and a groove 12 corresponding to the shape of the leaf spring to be molded is formed on the outer periphery of the mold 1.
A pin 13 for forming a center hole is provided protrudingly at a predetermined position. In the case of this illustrated example, the mold 11 is divided into three equal parts in the circumferential direction and can be divided into three parts.
Pins 13 are provided on each of the divided pieces 11a, 11b, 11c. Therefore, in the illustrated example, three leaf springs can be molded at the same time.

By rotating the mold 11, the reinforcing fiber bundle 6 is wound around the groove 12 in a plurality of layers. This reinforcing fiber bundle 6 is continuous in the longitudinal direction of the leaf spring, and is made of known fibers such as glass fibers, carbon fibers, and organic fibers, and is supplied from the roving bundles 14, respectively.

After the reinforcing fiber bundle 6 is let out from the roving bundle 14, it passes through the impregnation tank 10 and is impregnated with the matrix resin 7', and is further impregnated with the alignment guide member 1.
After passing through the groove 12, it is wound up into the groove 12. The alignment guide member 15 is designed to be able to rotate within a plane intersecting the traveling direction of the reinforcing fiber bundle 6, as shown by arrow A in FIG.

The direction in which the guide member 15 rotates is generally perpendicular to the traveling direction of the fibers, but in some cases, the direction is not limited to the perpendicular direction. It may be made to be rotatable with an inclination in consideration of the point of contact with the resin, etc. Further, the width W of the hole through which the fiber bundle 6 passes in the guide member 15 (see FIG. 4) is made substantially equal to the width of the groove 12.

This is shown in FIG. 3 using the above embodiment device.
To manufacture the FRP leaf spring 1, when winding the reinforcing fiber bundle 6 impregnated with resin through the impregnation tank 10 around the mold 11, a portion 1 away from the pin 13 is wound.
6, 17, that is, the alignment guide member 15 is kept in a non-rotating position (see FIG. 4) so that the reinforcing fiber bundle 6 spreads across the entire width of the groove 12 at the end portion of the leaf spring.

As the mold 11 rotates, the position at which the fiber bundle 6 is wound approaches the pin 13, and the guide member 15
is gradually rotated as shown in FIG. 5, and the width of the fiber bundle 6 wound around the groove 12 is narrowed. Then, when the width becomes almost the minimum, one side of the pin 13 is passed through. Next, the guide member 15 is rotated in the direction to return to its original position, and the width of the fiber bundle 6 is widened, and the fiber bundle 6 is further wound. In the illustrated example, the above operation is repeated three times during one rotation of the mold 11. As illustrated in FIG. 4, when the mold 11 is used, the fiber bundle is passed through the right side of the pin in the illustration for the first pin 13a, and the fiber bundle is passed through the left side of the pin in the illustration for the second pin 13b. It is preferable to alternately change the direction in which the fiber bundles are brought together for each pin during rotation.
If the direction of avoiding the pins is alternately switched in the circumferential direction of the mold 11 in this way, the fiber bundles will not be biased only to one side during one revolution of the mold 11, and the fiber bundles will not be biased to one side only in the parts 16 and 17 away from the pins. Groove the fiber bundle 1
This makes it easy to spread out the width of 2.

As described above, while the mold 11 rotates once, the pin 13
If the fiber bundle is wound while alternating the direction to avoid the pins, the number of pins is odd (3) in the example in Figure 4, so the direction to avoid the pins in the second rotation is opposite to the above. Become. In other words, the fiber bundles 6 are alternately distributed to one side of the pin 13 for each layer and overlap in the thickness direction. After the fiber bundle 6 is stacked several times to several tens of times in this manner, it is heated by a heater built into the mold 11 or placed in a heating furnace to be heated and hardened. After curing, it is cut into an appropriate length to obtain the FRP leaf spring 1.

According to the above FRP leaf spring 1, since the center hole 5 can be formed without cutting the reinforcing fibers, cracks are less likely to occur even in the area around the center hole where high stress occurs. Further, even if a crack should occur, since the reinforcing fibers 6a and 6b in different directions cross each other in the thickness direction before and after the center hole 5, the crack can be prevented from progressing and durability can be maintained.

In addition, when obtaining this FRP leaf spring 1, the width of the reinforcing fiber bundle 6 is narrowed by rotating the alignment guide member 15 to avoid the pin 13, so that the gaps between each fiber are narrowed almost uniformly. This can prevent local shifting of the fibers and unnecessary contact. For example, when the width of the fiber bundle is narrowed by forcibly pressing the fiber bundle in the horizontal direction using a pressing member that slides in the horizontal direction, or by sliding the mold 11 in the horizontal direction to avoid the pin 13. In some cases, the fibers may come into contact with each other unnecessarily, resulting in weak points in terms of strength. However, according to the method of this embodiment, since the width of the fiber bundle is narrowed overall, it is possible to prevent such problems from occurring.

In the above embodiment, the reinforcing fibers are alternately distributed one layer at a time in the board thickness direction, but they may be alternately distributed in multiple layers by stacking two or more layers in the same direction. Furthermore, as a means for rotating the alignment guide member 15, it may be automatically rotated back and forth by mechanical force, or it may be rotated manually.

Further, as illustrated in FIG. 6, the reinforcing fibers may be distributed to the left and right only in the peripheral portion of the center hole 5.

As described above, according to the present invention, it is possible to prevent the occurrence and propagation of cracks around the center hole, and it is possible to obtain a highly durable FRP leaf spring.

[Brief explanation of drawings]

Fig. 1 is a front view showing a stacked leaf spring device, Fig. 2 is a perspective view showing a part of a conventional FRP leaf spring in cross section,
Fig. 3 is a perspective view showing a partial cross section of an FRP leaf spring according to an embodiment of the present invention, Fig. 4 is a perspective view schematically showing an apparatus for manufacturing the same FRP leaf spring, and Fig. 5 shows an alignment guide member. FIG. 6 is a perspective view of a rotated state, and a plan view schematically depicting an FRP leaf spring showing another embodiment of the present invention. 1...FRP leaf spring, 5...center hole, 6...
Reinforced fiber bundle, 6a, 6b... Reinforced fiber, 7... Matrix resin, 10... Resin impregnation tank, 11...
Mold, 12...Groove, 13...Pin, 15...Alignment guide member.

Claims (1)

[Claims] 1. In an FRP leaf spring containing reinforcing fibers continuous in the longitudinal direction of the leaf spring and having a center hole,
An FRP leaf spring characterized in that the reinforcing fibers are stacked in the thickness direction of the leaf spring by alternately distributing each layer or layers to the left and right sides of the center hole. 2. In a method for manufacturing an FRP leaf spring in which a reinforcing fiber bundle continuous in the longitudinal direction and impregnated with resin is passed through an alignment guide member and then wound around a mold and cured, the reinforcing fiber bundle is wound around a mold, Before attaching the reinforcing fiber bundle, the alignment guide member is rotated in a plane intersecting the traveling direction of the reinforcing fiber bundle to narrow the width of the reinforcing fiber bundle while avoiding the center hole forming pin and winding the reinforcing fiber bundle around the mold. A method for manufacturing an FRP leaf spring, characterized in that the direction in which the spring is avoided is alternately changed for each layer or multiple layers.