JPH04136531A - Frp plate spring and manufacture thereof - Google Patents

Abstract

PURPOSE:To increase the strength, rigidity and at resistance and improve the workability by laminating cloths made of reinforced fiber between roving materials made of reinforced fiber, and using alicyclic epoxy resin as matrix resin. CONSTITUTION:For FW method, carbon fiber 1a of roving material 1 wound around a bobbin is passed through a matrix resin M impregnating device 5, then wound around a core 6, and a laminated structure of cloths 2 is inserted in a specified FW forming process by hand lay up method. After the weight of the resin-impregnated roving material 1, the cloths 2 reach a specified value, they are hot-pressed and formed by upper and lower dies incorporating a sheathed heater. For matrix resin, alicyclic epoxy resin is used, and the resin is mixed with acid anhydride system curing agent to make matrix resin M. Thus, the manufacturing and operating efficiency is enhanced, and a material of high strength and high rigidity exhibiting composite material characteristics can be obtained.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an FRP leaf spring and a manufacturing method thereof. [Prior Art] In recent years, efforts have been made to reduce the weight of vehicles such as automobiles and aircraft, mainly to improve fuel consumption efficiency.
As a means of achieving this, there is a need to reduce the weight of spring materials. In addition, light spring materials are required for various industrial machines for various purposes, and FRP, which has excellent mechanical properties due to the combination of reinforcing fibers and matrix resin, has attracted attention, and has been used as a new industrial material for spring materials. Applications are being expanded to. Conventional FRP leaf springs use epoxy resin or polyester resin as the matrix resin. The spring material was carbon fiber or glass fiber roving material, which was impregnated with matrix resin. [Problem to be solved by the invention] In FRP, the matrix resin integrates the reinforcing fibers and compensates for the physical property defects of the resin through bonding with them, while retaining its properties in the molded product. It plays an important role. In addition, the physical properties required for matrix resins include high toughness and strength, as well as good moldability.
For example, it has heat resistance. However, until now, there has been no leaf spring that has sufficient characteristics such as the selection of matrix resin and the composition of the spring material. In view of the above-mentioned circumstances, it is an object of the present invention to provide an FRP leaf spring that has high strength, high rigidity, excellent heat resistance, and good workability, and a method for manufacturing the same. [Means for Solving the Problems] In order to achieve the above object, the inventors conducted various experiments and research, and found that the matrix resin has well-balanced physical properties, ease of molding, and reinforcement. Based on research results showing good adhesion to materials and good heat resistance, alicyclic epoxy resin was selected and this invention was completed. That is, the configuration of the present invention is as follows. 1) Regarding the FRP leaf spring, a cloth 2 also made of reinforcing fibers is laminated between roving materials 1 made of reinforcing fibers, and the matrix resin M is an alicyclic epoxy resin. 2) Regarding the manufacturing method of the FRP leaf spring, the roving material 1 made of reinforcing fibers is formed by the FW method, and
A cloth 2 made of reinforcing fibers is laminated between roving materials 1, and an alicyclic epoxy resin is used as the matrix resin M. [Function] Since the FRP leaf spring and its manufacturing method are configured as described above, it is possible to increase the work efficiency of manufacturing the FRP leaf spring, and it also has high strength and high rigidity that exhibits the characteristics of a composite material. I was able to obtain a leaf spring. As mentioned above, the primary reason for this is that the alicyclic epoxy resin has well-balanced physical properties, is easy to mold, has good adhesion to reinforcing materials, and has good heat resistance. It can be considered. Therefore, in the structure of the leaf spring S, since the matrix resin M has good affinity with the reinforcing fibers, cracks in the plate thickness direction are improved and reinforcement against torsion is strengthened. In addition, as for the manufacturing method, the leaf spring S can be manufactured particularly efficiently by the FW method. The alicyclic epoxy resin includes a cyclic oxirane type, an aromatic-containing type, a glycidyl ether type, and a glycidyl ester type.Next, examples of the present invention will be described based on the drawings. The example is a case in which compression molding of a mini leaf spring S using carbon fiber roving material 1 and cloth 2 is carried out by the FW method, and the number of cloths 2 inserted is divided into 2 layers and 6 layers. , conducted various evaluation tests on the prototype leaf spring S. Regarding the matrix resin, alicyclic epoxy resin (■
EX-1,9) manufactured by Asahi Chemical Research Institute is used, and an acid anhydride curing agent (the above-mentioned curing agent for EX-19) is mixed therein to prepare matrix resin M. The physical properties of the constituent materials of FRP are shown in Table 1 below. Table I: Types of main physical properties of FRP constituent materials. Among them, glycidyl ether type has low viscosity and
It is most suitable for use due to its excellent adhesiveness and heat resistance. [Example] Regarding the specifications of the carbon fiber cloth 2 used for the purpose of compensating for the drawbacks of the unidirectionally reinforced carbon fiber of the roving material 1, the number of filaments was 1000 and the weight was 119 g/rrr. As shown in FIG. 1, the FW method employs a method in which the carbon fibers 1a of the roving material 1 wound around a bobbin are passed through a resin impregnating device 5 and then wound onto a core 6. For the cross-laminated structure (number of inserted sheets: 72 layers and 6M), the sheets were inserted using the hand-removal method at a predetermined FW molding stage. After the resin-impregnated roving material 1 and cloth 2 reach a predetermined weight, an upper mold (
Hot press molding was performed using a mold consisting of a leaf spring molding section (R900 ma+) and a lower mold. The molding load is gradually applied when the mold temperature reaches 50℃, and the load (approximately 15℃) is applied when there is no gap in the stopper.
(back and forth) continued to be held. The molding temperature is 100℃
After holding for a minute, the temperature was raised to 160°C. After the molded sample was released from the mold, it was subjected to after-cure at 160° C. for 3 hours. FIG. 2 shows the external appearance of the leaf spring S formed in this way, and has a loop shape. An evaluation test piece cut out from a loop-shaped molded sample was subjected to a bending test, etc. using an Instron chamber strain tester. In addition, a small hydraulic vibrator was used for the repeated bending test of the leaf spring S. Next, the experimental results for the above-mentioned prototype leaf spring S will be discussed. FIG. 3 shows a cross-sectional photograph of the leaf spring S in order to examine the dispersibility of fibers and resin. Unidirectional reinforcing fiber of roving material 1 and matrix resin M
In this condition, the dispersibility of the fibers is good overall, and the resin is also impregnated in a manner that wraps the fibers. The same applies to the second cross portion. (]) Bending strength and bending elastic modulus Figure 4 shows the relationship between carbon fiber content, bending strength, and bending elasticity. In the figure, only cross lamination (
The results for the matrix resin (also an alicyclic epoxy resin) are also shown. From the figure, carbon fiber FR by FW method
P (in the case of the temporary spring S of this example, Ol
The bending strength of
~130 kg f/tm'', and no major changes were observed as in the case of only cross lamination.Also, compared to the case of cross lamination, carbon fiber F by the FW method
The bending strength of RP is Vf (reinforced fiber volume content) of 60
We were able to improve the load by approximately 35 to 40 kgf/kaku2 at around 35% to 40%. This is thought to be because the FW method made the fiber stacking direction the same as the direction of force action. In addition, the bending strength reaches its maximum value when Vf is around 60%,
At 70% or more, it tends to decrease. this is. This is thought to be because the matrix resin that surrounds each fiber is expelled, resulting in an insufficient amount of resin to adhere to the fiber at the interface. In addition, the 1 bending elastic modulus increases linearly as Vf increases. This is considered to be because the stiffness of the fiber is directly related to the bending modulus. In addition, the bending elastic modulus is approximately 3 x 10'' compared to the cross lamination method.
〜4×103kgf/m+2 could be improved. When considering application to springs, Vf does not reduce bending strength and has an elastic modulus of approximately 8.5 x 103 kgf/m.
It is desirable to set the content around 65%, which can be around 65%. 0, C, Δ, and Mu in the figure are 0, C, Δ, and Mu in the FW method where Vf is 65% in order to add torsional strength.
Approximately less than 10% is cross (two-layer laminated structure). These are the test results of a sample in which a little less than 30% of the sample was replaced with cloth (6-layer laminated structure). As shown in the figure, there is almost no difference in bending strength and elastic modulus in the two-layer laminated structure of the cloth compared to the FW method. In addition, the 6-layer laminated structure has a bending strength of 15 kgf/■1
, the elastic modulus has decreased by around 700 kgf/tn''. (2) Heat resistance characteristics Figure 5 shows the tensile modulus of elasticity (DMA) at 30°C with the tensile modulus (DMA) tester set at 100%, and when the elastic modulus is 5% lower than that. Temperature and V
This is an example showing the relationship with f. From the figure, the heat resistance temperature is affected by the amount of matrix resin impregnated, so Vf
tends to rise with an increase in 160-170℃ for cross lamination method, 170-180℃ for FW method
There is a difference of about 10°C. Vf
is constant at 65%, FW - 2 crosses 1) and 6 crosses (0)
The laminated structure showed almost the same heat resistance temperature as the FW method, which was around 7180°C. (3) Repeated bending test Table 2 shown in the attached sheet shows the results of the repeated bending test of the leaf spring S. The test was conducted using partial shear bending (span L = 191 degrees), and initial settings were made so that the maximum stress generated during the repeated bending test was 95% of the bending stress of the material, and the test frequency was was controlled under the excitation conditions of 10 Hz and a displacement of ±4 m. Moreover, the number of repeated lifespans was defined as the number of times the leaf spring S suffered fatigue breakage or damage to its appearance. F
In the unidirectionally reinforced material manufactured by the W method, the number of repetitions until breakage tended to increase as Vf increased. On the other hand, in the combination of the FW method and the cross lamination method, peeling of the cross layer occurred an order of magnitude fewer times than in the FW method, but this is because the matrix resin is a resin other than alicyclic epoxy resin. fewer times than in the case of FIG. 6 shows the state of destruction of the leaf spring. However, the material in which the cross layers were combined was forcibly broken by bending after being vibrated up to 106 times. From the figure, when Vf is 75% with only one direction reinforcement, the fibers in the reinforcing direction are separated after rupture, and it is thought that there is not enough matrix resin to sufficiently bundle the carbon fibers. It will be done. By setting Vf to 64%, it is possible to avoid the uneven fracture state that occurs when Vf is 75%. However, 2 perpendicular to the reinforcing direction of the fiber
Cracks were observed in both the thickness direction and the lateral direction. It can be seen that in the case of the present invention, which combines the FW method and the cross lamination method, cracks in the thickness direction are improved and a reinforcing effect against torsion is expected. [Effects of the Invention] As explained above, according to the present invention, since the cloth made of reinforcing fibers is laminated between the roving materials made of reinforcing fibers, it is strong against twisting in the thickness direction, and has high strength and high strength. A rigid heat-resistant leaf spring can be obtained, and
Since the alicyclic epoxy resin is used as the matrix resin, the manufacturing workability is good, and there is an excellent effect that a leaf spring with excellent heat resistance can be manufactured. In the method for manufacturing FRP leaf springs, workability is very good because the FW method-cross lamination method is used, and particularly high strength and high rigidity leaf springs can be manufactured efficiently.

【Attachment】

Table 2 Results of repeated bending test

[Brief explanation of drawings]

The drawings relate to embodiments of the invention, and FIG.
Figure 2 is a perspective view of a leaf spring, Figure 3 is a cross-sectional photograph of a leaf spring, Figure 4 is a graph showing the relationship between carbon fiber volume content, bending strength, and bending modulus. Fig. 5 is a graph showing the relationship between carbon fiber content and heat resistance temperature, and Fig. 6 is a photograph showing the state of destruction of the leaf spring. M... Matrix resin S... Leaf spring 1...
Roving material 2...Cross (Note 1) Number of times peeling of cloth was recognized Procedural amendment (method) June 12, 1991 1990 Patent Application No. 258429 2 Name of invention Address name 4 Agent 1-7 Shinsokuruwa, Toyama City, Toyama Prefecture Toyama Prefectural Governor Yutaka Nakaoki 930 fi0764-33-04736, Subject of amendment 7, Contents of amendment 1) On page 8, line 10 of the specification, there is a ``Cross-sectional photograph of spring S'' has been corrected to ``Cross-sectional view of leaf spring S.'' 2) In the 11th line of page 13 of the specification, the phrase "Fig. 3 is a cross-sectional photograph of a leaf spring" is replaced with "Fig. 3 is a cross-sectional view of a leaf spring showing the dispersibility of fibers and resin. 3) On page 13, lines 14 to 15 of the specification, the statement ``Figure 6 is a photograph showing the state of destruction of the leaf spring.'' has been corrected.
Figure 6 is a perspective cross-sectional view showing the fractured cross section of various leaf springs, and Figure (a) is one made of only one-way reinforced roving material and with a Vf (volume content of reinforcing fibers) of 75%; (b
) is one-way reinforced roving material with Vf64%,
Figure (e) shows the fracture cross section of a unidirectionally reinforced roving material with two layers of cloth plus Vf of 65%, and Figure (d) shows the fracture cross section of a unidirectionally reinforced roving material with six layers of cloth plus Vf of 65%. This is a diagram. 4) Figures 3 and 6 of the drawings will be corrected as shown in the attached sheet.

Claims (1)

[Claims] 1) A cloth 2 also made of reinforcing fibers is laminated between roving materials 1 made of reinforcing fibers, and matrix resin M
An FRP leaf spring characterized in that is an alicyclic epoxy resin. 2) A roving material 1 made of reinforcing fibers is formed by the FW method, a cloth 2 made of reinforcing fibers is laminated between the roving materials 1, and an alicyclic epoxy resin is used as the matrix resin M. Manufacturing method for FRP leaf springs.