JPH09280343A - Fiber-reinforced composite resin gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide heat resistance, a fatigue strength, and wear resistance, being applicable for high load application by a method wherein a modulus of elasticity of a surface part containing a tooth surface is below a specified value and the fatigue strength of the interior continued to the surface part is set to a value exceeding a specified value. SOLUTION: In a fiber-reinforced composite resin gear, reinforcing fibers of a surface part has a modulus of elasticity of 10GPa or less and the reinforced fiber at the interior has strength of 50MPa or more. A gear 1 is formed such that a steel insert 12 is fitted in the core part of a fiber-reinforced composite resin part 11. A premolded product is set in a molding die having an inside size in the same shape as the outer shape of the gear 1, and epoxy resin is injected and cured to form the composite resin part 11 of the gear 1. The composite resin part 11 of the gear 1 is constituted such that, in a surface part 11S, chopped metha aramid fibers are dispersed in a matrix in a single continuous phase consisting of epoxy resin and in an inner part 11C, chopped carbon fibers are dispersed in the matrix. This constitution provides heat resistance, a fatigue strength, and wear resistance, which are applicable for high load application.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fiber-reinforced composite resin gear in which reinforcing fibers are dispersed in a resin matrix.

[0002]

2. Description of the Related Art Since resin gears are effective in reducing noises such as rattling noise and meshing noise, they have been put to practical use in light load applications such as audio products. If this can be used for high-load applications such as camshaft timing gears of automobiles, it is expected to be extremely effective in reducing noise.

It is required to have much higher heat resistance, fatigue strength and wear resistance than those of conventional light load applications. For example, a resin gear containing no reinforcing material as disclosed in Japanese Patent Application Laid-Open No. 1-180056 can be used only for conventional light load applications, and is applicable to the above high load applications. Can not. Conventionally, for the purpose of generally improving heat resistance and fatigue strength, as disclosed in JP-A-60-184456, fiber reinforced by dispersing high strength fibers such as carbon fibers and glass fibers in a resin matrix. Composite resin gears have been proposed.

However, as a result of a detailed study by the present inventor,
Although the fiber-reinforced composite resin gear of the above proposal improves the fatigue strength as a composite material by using the high-strength fiber as described above, the high-strength fiber has a high elastic modulus at the same time in the range of the current practical materials. Therefore, it was found that the meshing contact surface pressure of the gears also increased, and there was a limit to the improvement of wear resistance. Conversely, if the entire gear is reinforced with fibers having a low elastic modulus in order to secure abrasion resistance, the contact surface pressure will decrease due to the low elastic modulus, and abrasion resistance can be improved. In the range of 1, the fiber having a low elastic modulus also has a low strength at the same time, so that the fatigue strength also decreases.

Further, Japanese Patent Application Laid-Open No. 1-104467 proposes a gear in which a cloth made of polytetrafluoroethylene fiber is closely molded on the tooth surface to ensure wear resistance and noise reduction. In this gear, the contact surface pressure is kept relatively low because the tooth surface cloth has a low elastic modulus,
An adhesive interface inevitably exists between the gear body and the fabric, and when a shocking input such as a high load or rotation fluctuation is transmitted, the surface fabric easily peels off at the adhesive interface, It is inevitable that the durability will decrease.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fiber-reinforced composite resin gear having high heat resistance, fatigue strength and wear resistance, which can be applied to high load applications such as automobiles.

[0007]

According to the present invention, the above object is to provide a fiber-reinforced composite resin gear in which reinforcing fibers are dispersed in a resin matrix as a continuous body, and a surface layer portion including a tooth surface has an elastic modulus. It is achieved by a fiber reinforced composite resin gear having a fatigue strength of 50 MPa or more in the interior continuous with the surface layer portion of 10 GPa or less.

The fiber-reinforced composite resin gear of the present invention has a low elastic modulus in the surface layer to lower the contact surface pressure and improve wear resistance. Fatigue strength can be secured, and since the surface layer part and the inside are integrated with a resin matrix as a continuous body, the surface layer does not peel off even under high load or impact load, and high durability is achieved. Can be secured.

Here, the contact surface pressure σ _F is calculated by the following equation,
The elastic moduli E ₁ and E ₂ monotonically increase via the parameter Z _M. Therefore, the contact surface pressure can be reduced and the wear resistance can be improved by using a material having a low elastic modulus.

[0010]

[Equation 1]

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the fiber-reinforced composite resin gear of the present invention, typically, the reinforcing fibers in the surface layer portion have an elastic modulus of 60.
It is less than GPa and the reinforcing fiber inside has a strength of 3000MP
It is a or more. However, this is just a typical range, and a fiber that can impart the elastic modulus of the surface layer portion and the internal strength as described above as a composite material by the volume ratio and orientation of the fiber can be used.

Among the fibers currently in practical use, meta-aramid fibers, polyphenylene sulfide fibers, polyoxymethylene fibers, acrylic fibers, polyethylene fibers and the like are particularly suitable as the reinforcing fibers in the surface layer portion, and as the internal reinforcing fibers, , Carbon fiber, para-aramid fiber, glass fiber and the like are particularly suitable.

[0013]

【Example】

Example 1 A fiber-reinforced composite resin gear having the specifications shown in Table 1 was produced. FIG. 1 shows its schematic shape. The gear 1 shown in FIG. 1 has a fiber-reinforced composite resin portion 1 as shown in FIG.
JIS-S450C steel insert 1 in the core of 1
2, the composite resin portion 11 is composed of a surface layer portion 11S including a tooth surface and an interior 11C directly continuous with the surface layer portion 11S.

[0014]

[Table 1]

The gear 1 was manufactured by the following procedure. In the mold having the same inner dimensions as the outer shape of the gear 1, set the preformed compact densely molded with the reinforcing fibers three-dimensionally entangled, and heat the mold to 120 ° C. After drawing a vacuum, epoxy resin was injected and cured to form the composite resin portion 11 of the gear 1.

At this time, the preform of the reinforcing fiber is the inner part 1
1C is 3mm long chopped carbon fiber (Toray "T
300 "), and the surface layer portion 11S having a thickness of 1 mm (the entire circumference of the gear) is made of chopped meta-aramid fiber having a length of 1 mm (" Conex ", Teijin Ltd.). The preform was formed by suctioning from a slurry water in which chopped fibers were suspended into a gear-shaped mold. First, carbon fibers were suction-molded with a mold having a size smaller than the final size, the carbon fibers were set in the mold with the final size, and the meta-aramid fiber was suction-molded in the void of 1 mm outside thereof. This was dried and used for resin molding of gears as described above. There is springback during drying, but the shape is retained due to the fiber entanglement.

The composite resin portion 1 of the gear 1 thus obtained
In No. 1, chopped meta-aramid fibers with a length of 1 mm were dispersed at a volume ratio of 30 vol% in the surface layer portion 11S in a matrix as a single continuous phase made of epoxy resin, and the internal 1
In 1C, chopped carbon fibers having a length of 3 mm were dispersed at a volume ratio of 40 vol%. [Example 2] A fiber-reinforced composite resin gear having the same specifications as in Example 1 was produced.

However, as the reinforcing fibers of the surface layer portion 11S,
The chopped fiber of any one of the following (a) to (d) was used instead of the meta-aramid fiber. (A) Acrylic fiber (b) Polyoxymethylene fiber (c) Polyphenylene sulfide (PPS) fiber (d) Polyethylene fiber The same chopped carbon fiber as in Example 1 was used as the reinforcing fiber inside 11C. The other conditions and the manufacturing procedure were the same as in Example 1.

The composite resin portion 1 of the gear 1 thus obtained
No. 1 has a length of 1 mm (a) in the surface layer portion 11S in a matrix as a single continuous phase made of epoxy resin.
The volume ratio of the chopped fiber of any one of (d) is 30 v
The chopped carbon fibers having a length of 3 mm were dispersed at a volume ratio of 40 vol% in the interior 11C. [Example 3] A fiber-reinforced composite resin gear having the same specifications as in Example 1 was produced.

However, as the reinforcing fiber of the interior 11C, glass fiber having a length of 3 mm (Nitto Boseki "E glass") was used in place of the carbon fiber. The same chopped meta-aramid fiber as in Example 1 was used as the reinforcing fiber of the surface layer portion 11S. The other conditions and the manufacturing procedure were the same as in Example 1. The composite resin portion 11 of the gear 1 thus obtained
In the surface layer portion 11S, chopped meta-aramid fibers having a length of 1 mm are dispersed at a volume ratio of 30 vol% in a matrix as a single continuous phase made of an epoxy resin.
In C, glass fibers having a length of 3 mm were dispersed at a volume ratio of 40 vol%. [Comparative Example 1] A fiber-reinforced composite resin gear having the same specifications as in Example 1 was produced.

However, as the reinforcing fibers of the surface layer portion 11S,
Para-aramid fibers (Dupont “Kevlar”) were used in place of the meta-aramid fibers. The same carbon fiber as in Example 1 was used as the reinforcing fiber of the interior 11C. The other conditions and the manufacturing procedure were the same as in Example 1. The composite resin portion 11 of the gear 1 thus obtained has the surface layer portion 1 in the matrix made of epoxy resin as a single continuous phase.
In 1S, chopped para-aramid fibers having a length of 1 mm were dispersed at a volume ratio of 30 vol%, and in the interior 11C, carbon fibers having a length of 3 mm were dispersed at a volume ratio of 40 vol%. [Comparative Example 2] A fiber-reinforced composite resin gear having the same specifications as in Example 1 was produced.

However, the same chopped carbon fiber as the reinforcing fiber inside 11C of Example 1 was used as the entire reinforcing fiber without distinguishing the surface layer portion and the inside of the composite resin portion 11 of the gear 1. At that time, the preform was molded by suctioning from the slurry water in which the chopped carbon fibers were suspended into the gear-shaped final size die.

In the gear 1 thus obtained, the entire composite resin portion 11 is formed by dispersing chopped carbon fibers having a length of 3 mm at a volume ratio of 40 vol% in a matrix of epoxy resin as a single continuous phase. Was there. [Comparative Example 3] A fiber-reinforced composite resin gear having the same specifications as in Example 1 was produced.

However, the same chopped meta-aramid fiber as the reinforcing fiber of the surface layer portion 11S of Example 1 was used as the entire reinforcing fiber without distinguishing the surface layer portion and the inside of the composite resin portion 11 of the gear 1. At that time, the preform was formed by suctioning from the slurry water in which the chopped meta-aramid fiber was suspended into the final dimension die of the gear shape.

In the gear 1 thus obtained, the entire composite resin portion 11 is formed by dispersing chopped meta-aramid fibers having a length of 3 mm at a volume ratio of 40 vol% in a matrix of epoxy resin as a single continuous phase. Was there. Example 1,
Table 2 shows the fibers used, the strengths, and the elastic moduli of the fiber-reinforced composite resin gears produced in Nos. 2 and 3 and Comparative Examples 1, 2, and 3.

[0026]

[Table 2]

As shown in Table 2, the fiber-reinforced composite resin gears of Examples 1, 2, and 3 are the same as the inside 11C of the composite resin portion 11.
Carbon fiber or glass fiber, which is a high-strength fiber having a strength of 3000 MPa or more, is used as the reinforcing fiber, and the bending fatigue strength as the composite material is 50 MPa or more within the range of the present invention, and the reinforcing resin of the surface layer portion 11S of the composite resin portion 11 is The elastic modulus of the composite material is set to 10 GPa or less within the range of the present invention by using meta-aramid fiber or the like which is a low elastic modulus fiber having an elastic modulus of 60 GPa or less.

On the other hand, in the fiber-reinforced composite resin gear of Comparative Example 1, the inside 11C of the composite resin portion 11 has a strength of 3000.
Although the bending fatigue strength was set to 50 MPa or more within the range of the present invention by using carbon fiber which is a high strength fiber of MPa or more, the surface layer portion 11S of the composite resin portion 11 has an elastic modulus of 190 GP.
The elastic modulus was set to 15 GPa, which exceeds the range of the present invention, by using the para-aramid fiber having a high elastic modulus of a.

In the fiber-reinforced composite resin gears of Comparative Examples 2 and 3, the composite resin portion 11 was made without distinguishing between the surface layer portion and the inside.
The same reinforcing fibers were used for the whole, Comparative Example 2 used carbon fibers which were high strength fibers, and Comparative Example 3 used meta-aramid fibers which are low elastic modulus fibers. The fiber-reinforced composite resin gears manufactured in Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 were replaced with steel gears of the same tooth shape (JIS-
S450C), mesh at 120 ℃, 6000rp
A motoring durability test was conducted at m and torque of 20 Nm. These test conditions assume a high load when used as an automobile camshaft timing gear.
In the case of light load applications such as audio products where conventional fiber reinforced composite resin gears were used, the torque is on the order of 1/10 to 1/100 with respect to 20 Nm used in the above test, and the temperature is room temperature. The rotation speed is low, which is a fraction of the above test or less.

The test results are summarized in FIG. 2 in relation to the test time and the tooth surface wear depth. As can be seen from FIG. 2, the gears of Examples 1, 2, and 3 of the present invention had a tooth surface wear depth of less than 0.1 mm for a test time of up to 200 hours and exhibited excellent durability. . On the other hand, in the fiber-reinforced composite resin gear of Comparative Example 1, the inner surface 11C has high strength within the range of the present invention, but the surface layer portion 11S has a high elastic modulus exceeding the range of the present invention, and therefore the contact surface pressure is high. And the tooth surface wear gradually progressed as the test time passed, and the wear depth increased to 0.45 mm at 200 hours.

Further, in Comparative Example 2, since the entire composite resin portion 11 was reinforced with carbon fiber which is a high-strength fiber, although the overall strength is high, the contact surface pressure becomes higher than that of Comparative Example 1, and Comparative Example 1 Wear progresses more rapidly than that, and the wear depth reaches 1 mm after 75 hours. On the other hand, in Comparative Example 3, since the entire composite resin portion 11 was reinforced with the meta-aramid fiber having the low elastic modulus fiber, the fatigue strength was inevitably low as a whole, and the fatigue fracture occurred at the time of about 40 hours.

As described above, according to the present invention, the surface layer portion 11S has a low elastic modulus of 10 GPa or less and the inner portion 11C has 50 M.
Only when the fatigue strength is higher than Pa, it is possible to simultaneously suppress tooth surface wear and fatigue fracture. Next, in the fiber-reinforced composite resin gear of the present invention, the desired thickness of the surface layer portion 11S in order to suppress tooth surface wear was examined. [Example 4] A fiber-reinforced composite resin gear having the same specifications as in Example 1 was produced.

However, the thickness of the surface layer portion 11S reinforced by the meta-aramid fiber is 0.1 mm, 0.3 mm, 0.5.
mm, 1 mm, and 1.5 mm were used for the production. This fiber-reinforced composite resin gear was subjected to a motoring durability test for 200 hours under the same conditions as above. The obtained results are shown together in FIG. 3 in relation to the surface layer thickness and the 200-hour tooth surface wear depth.

As can be seen from FIG. 3, the effect of suppressing the tooth surface wear becomes particularly remarkable when the surface layer thickness is 0.3 mm or more, and further when the surface layer thickness is 0.5 mm or more. Becomes noticeable. However, if the surface layer having a low elastic modulus is too thick, the high-strength portion that constitutes the inside of the tooth will be relatively small, and the original fiber-reinforced effect will be reduced. It is considered appropriate to set the thickness of the surface layer portion to about 1/4 of the tooth root thickness.

[0035]

As described above, according to the present invention,
A fiber-reinforced composite resin gear having high heat resistance, fatigue strength, and wear resistance that can be applied to high-load applications such as automobiles can be obtained.

[Brief description of drawings]

1A is a perspective view and FIG. 1B is a partial sectional view showing a schematic shape of a fiber-reinforced composite resin gear manufactured in Examples and Comparative Examples.

FIG. 2 is a graph showing a relationship between a test time and a tooth surface wear depth in a motoring durability test for Examples and Comparative Examples.

FIG. 3 is a graph showing the relationship between the thickness of the low elastic modulus surface layer portion and the 200-hour tooth surface wear depth in the fiber-reinforced composite resin gear of the present invention.

[Explanation of symbols]

 1 ... Gear 11 ... Composite resin part 11S ... Surface layer part 11C ... Inside 12 ... Steel insert

Claims (3)

[Claims] 1. In a fiber-reinforced composite resin gear in which reinforcing fibers are dispersed in a resin matrix as a continuous body, the surface layer portion including the tooth surface has an elastic modulus of 10 GPa or less, and the interior continuous to the surface layer portion has fatigue strength. A fiber-reinforced composite resin gear having a pressure of 50 MPa or more. 2. The reinforcing fiber in the surface layer portion has an elastic modulus of 60 GP.
a or less, and the reinforcing fiber inside has a strength of 3000MP
The fiber-reinforced composite resin gear according to claim 1, which is a or more. 3. The reinforcing fibers in the surface layer are selected from the group consisting of meta-aramid fibers, polyphenylene sulfide fibers, polyoxymethylene fibers, acrylic fibers, and polyethylene fibers, and the internal reinforcing fibers are carbon fibers and para-aramid fibers. And a fiber-reinforced composite resin gear according to claim 2, selected from the group consisting of: