JPH0141948Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to an FRP leaf spring using spring plates made of FRP.

[Conventional technology]

This type of FRP leaf spring, for example, as shown in FIG. and is fixed to the axle e using U-bolts d, etc.

However, it was confirmed that if the spring plate a is strongly tightened at the above-mentioned tightening part of the spring plate a, there is a possibility that the spring plate a may cause so-called vertical cracks along the longitudinal direction, and the cause of this was investigated. The following was discovered.

In other words, as is well known, FRP spring plates are made by molding reinforcing fibers impregnated with resin into a desired shape using a mold. If the spring is very long compared to the width and thickness of the spring plate, the curing tends to be uneven, and therefore, as shown in Figure 2 or 3, for example, the hardening may be perpendicular to the longitudinal direction of the spring plate. The dimensional accuracy is generally inferior to that of steel spring plates, as the cross-sectional shape in the direction is difficult to form an accurate rectangle, and some parts are concave or bulge in an arched shape.

According to the inventor's experience, there are differences in the cross-sectional shapes of FRP spring plates depending on the manufacturing method. In other words, if a spring board is formed by a dry molding method mainly using a semi-cured sheet (prepreg), the central part in the width direction of the board tends to have a convex shape, but in a wet molding method using an uncured resin, the resin during curing tends to become convex. Due to shrinkage, an arch-shaped depression is likely to be formed in the middle part of the board in the width direction.

[The problem that the idea attempts to solve]

FRP products are normally used in their hardened form, so when the spring plate made by the wet forming method described above is tightly tightened between washers c and c as shown in Figure 2, this bow When a strong force is applied in the direction to flatten the shaped part, local bending stress is likely to be applied in the direction perpendicular to the longitudinal direction.Especially in the case of FRP spring plates, the reinforcing fibers tend to bend in the longitudinal direction of the spring plate. Since it is arranged in a direction and has a directional property, it has a drawback that vertical cracks are likely to occur when a local stress is applied in a direction perpendicular to the longitudinal direction as described above.

According to experiments conducted by the present inventor, for example, FRP spring plates (plate width
80mm, board thickness 30mm), if there is 0.21mm or more of warpage in the direction perpendicular to the fibers after forming the FRP, if you forcibly tighten it until the warpage is zero, cracks will appear in the direction of the fibers and damage will occur. I know what to do. Therefore, the smaller the warpage, the better.
It is quite difficult to form FRP spring plates so that the warpage is less than 0.21 mm.

Therefore, the purpose of the present invention is to prevent the use of eyelets, washers, auxiliary spring plates, etc. in FRP spring plates made by wet forming, which have a bow-shaped depression in the middle part in the width direction. To prevent vertical cracking of a tightened portion of a spring plate even if the spring plate is strongly tightened with an attached member.

[Means to solve the problem]

In order to achieve the above purpose, the FRP leaf spring of the present invention is a spring plate made of FRP that is formed so that the cross section in the width direction of the plate is rectangular and is reinforced by embedded fibers along the length direction of the plate. A buffer plate is provided at the clamping part with the attached member, and this buffer plate is formed between the arch-shaped recess that exists in the middle part in the width direction created when forming the spring plate and the surface facing the above-mentioned attached member. When the spring plate and the attached member are fastened together, the spring plate is compressed between the recess and the attached member, thereby filling the gap between the recess and the attached member over the entire width direction of the plate. It has rubber-like elasticity that allows it to be easily deformed.

[Effect]

Even if an arch-shaped depression is formed in the middle part of the spring plate in the width direction, such as when an FRP spring plate is formed using the wet forming method, the gap between this depression and the attached member at the clamp part is The buffer plate having rubber-like elasticity is compressed and deformed to fill in the gap without any gaps.

[Embodiment] An embodiment of the present invention will be described with reference to FIGS. 4 to 9. In Figure 4, 1 in the figure is
This spring plate 1 is a main spring plate made of FRP,
The reinforcing fibers impregnated with resin are formed into a curved shape using a mold (not shown). Metal eyepiece members 2, 2 are attached to both ends of the spring plate 1 using bolts 3, 3, and washers 4, 4 and a center bolt 5 are attached to the middle part of the spring plate 1. Auxiliary spring plate 6 is fastened. This auxiliary spring plate 6 is made of FRP like the main spring plate 1 described above.

As shown in FIG. 5, buffer plates 7, 7 are attached to the ends of the main spring plate 1 at the positions where the eyepiece members 2, 2 are attached using an adhesive or the like. Buffer plates 7 are also attached to the fastening portions of the plate 1 and the auxiliary spring plate 6 using adhesive or the like. These buffer plates 7 are each made of rubber or a synthetic resin having appropriate elasticity, and are designed to be elastically deformable to some extent. Then, as shown in FIG. 6, if the buffer plate 7 is opposed to the bow-shaped recess 1a on the surface of the spring plate and the washers 4, 4 are tightened, the buffer plate 7 will be tightened as shown in FIG. Since the plate 1 is deformed according to the surface shape of the plate 1 and comes into close contact between the spring plate surface and the washer 4, it becomes easier for the load to act evenly on the spring plate surface.
Therefore, stress concentration due to bending as described above (see FIG. 2) can be alleviated, and longitudinal cracks can be prevented. The buffer plate 7 may be a flat plate of uniform thickness as shown in FIG. 8, but for example, as shown in FIG. 9, at least one surface 7a may be curved. If 7a is made to correspond to the arcuate depression 1a of the spring plate 1, a more favorable result can be obtained in terms of alleviating stress concentration in the depression 1a.

Moreover, since the buffer plates 7, 7 are also provided between the eyeball members 2, 2 and the spring plate 1, the bolts 3, 3
When the eyepiece members 2, 2 are tightened by the above, the buffer plates 7, 7 deform in accordance with the surface shape of the spring plate 1 and come into close contact with the spring plate 1, so that this portion The stress concentration can be alleviated, and vertical cracks in the spring plate 1 can be prevented. Similarly, the buffer plates 7, 7 interposed between the spring plate 1 and the auxiliary spring plate 6 can prevent stress concentration on the mutual fastening surfaces of the spring plates, thereby preventing vertical cracking in this area. It is possible.

In the above embodiment, the buffer plates 7 are each attached to the spring plate with adhesive or the like, but for example, as shown in FIG.
The spring plate 1 and the buffer plate 7 may be integrally formed during molding.

Further, as shown in FIG. 11, a pad 10 is used at the attachment part of the eyepiece member 2, and a buffer plate 7 having the same principle as above is also provided between the pad 10 and the spring plate 1. Good too.

In short, the present invention provides an FRP spring plate with attached members such as eyepieces, washers, auxiliary spring plates, clips, etc. that are fastened together in the thickness direction of the spring plate, and the attachments between these attached members and the spring plate. Since it is sufficient to provide a buffer plate at the tightening portion between the parts, the shape and structure of the attached member, the shape of the buffer plate, etc. can be modified in various ways without departing from the gist of the present invention. Needless to say.

[Effect of idea]

According to the present invention, even if an arch-shaped recess is formed in the center of the width direction when an FRP spring plate is molded, when the spring plate and attached member are strongly tightened together, this tightened part will be bent. Since stress and stress concentration can be prevented from occurring, it is a practical product that can prevent vertical cracks from occurring due to attachment of attached parts in materials such as FRP spring plates, where reinforcing fibers have directionality and are prone to vertical cracks. It has a big effect.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an example of a conventional FRP leaf spring, Fig. 2 is a sectional view of the spring plate taken along the - line in Fig. 1, and Fig. 3 is a sectional view of the spring plate showing another conventional example. Figures 4 to 9 show one embodiment of the present invention, Figure 4 is a side view of the FRP leaf spring, Figure 5 is a side view of the spring plate, and Figure 6 is the state of the buffer plate before tightening. 7 is a sectional view showing the state after tightening, FIGS. 8 and 9 are perspective views of the buffer plate, respectively, and FIG. 10 is a sectional view showing a modified example of the mounting state of the buffer plate. 11 are side views showing a modified example of the attachment structure for the eyepiece member. 1... Spring plate, 1a... Arch-shaped recess, 2...
Eyepiece member (attached member), 4...Washer (attached member),
6...Auxiliary spring plate (attached member), 7...Buffer plate,
10...Piece (attached member).

Claims (1)

[Scope of utility model registration request] A spring plate made of FRP is formed so that the cross section in the plate width direction is rectangular and is reinforced with embedded fibers along the longitudinal direction of the plate, and a bolt is stacked on this spring plate in the plate thickness direction. and a plate-shaped accessory member that is fastened to the spring plate by tightening in the plate thickness direction with a nut, the part where the spring plate and the accessory member are tightened is provided with a plate-like attachment member of the FRP spring plate. It is interposed between the bow-shaped recess that exists in the middle part in the width direction that occurs as the resin hardens during molding, and the opposing surface of the attached member, and when the spring plate and the attached member are fastened together, the recess and An FRP leaf spring characterized by being provided with a buffer plate having rubber-like elasticity that fills the gap between the recess and the accessory member over the entire board width direction by being compressed with the accessory member.