JPH05240325A - Gear made of fiber reinforced resin - Google Patents

Abstract

PURPOSE:To provide a gear made of fiber reinforced resin, the workability in the gear cutting work of which is increased while the strength of the tooth part and the wear-resistance of the engagement surface are secured. CONSTITUTION:A prepreg 1 is used for a gear made of a fiber reinforced resin where the phenol resin is impregnated in the mix-woven cloth which consists of a metha-series aramid fiber (80%) which has low elasticity, and is excellent in the gear-cutting property and the reduction of the engagement noise and a carbon fiber (20%) which has high elasticity, and is excellent in the strength and the wear-resistance in the 0 deg. and 90 deg. orientation. This prepreg 1 is wound to form a stick, and both ends of the stick are put together to form a doughnut shape 3. In addition, this doughnut shape is formed in the heated and compressed condition to obtain a ring-shaped stock. The gear-cutting of the periphery of this ring-shaped stock is implemented, and the fibers are oriented in the growth ring shape in the engagement surface 70 of the tooth part 7. The fibers are oriented in the radial direction at the tooth part 7. The tooth part 7 is reinforced by both the aramid fiber and the carbon fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber reinforced resin gear. This gear can be used, for example, as a camshaft timing gear of an automobile.

[0002]

2. Description of the Related Art Fiber-reinforced resin gears have recently been widely used in various fields because they have advantages such as low meshing noise, light weight, and small rotational inertia. Here, JP-A-6
As disclosed in Japanese Unexamined Patent Publication No. 0-206628, a fiber-reinforced resin gear is known in which a material obtained by kneading reinforcing short fibers and a thermosetting resin is loaded into a mold cavity and heat-pressed. Further, as disclosed in JP-A-60-206629, a denier prepreg consisting of reinforcing short fibers and a thermosetting resin is circumferentially loaded into a mold cavity and heat-pressed. Fiber-reinforced resin gears are known.

Further, as disclosed in JP-A-2-241729, a prepreg obtained by impregnating a woven cloth of meta-aromatic polyamide fiber with a phenol resin is spirally wound into a rod-like shape. There is known a fiber-reinforced resin gear in which a doughnut-shaped preform material having both ends thereof is combined and solidified to form a ring-shaped material, and the outer peripheral portion of the ring-shaped material is gear-cut. However, the fiber-reinforced resin gear disclosed in JP-A-2-241729 has a problem that the strength of the tooth portion and the wear resistance of the tooth portion are small because the reinforcing fiber is the meta-aromatic polyamide fiber.

[0004]

Carbon fibers, glass fibers, aramid fibers and the like are generally used as the reinforcing fibers used in the fiber reinforced resin gears described above. Although it has good wear resistance, carbon fiber is a difficult-to-cut material because the cutting edge of the cutter slips because it has a small coefficient of friction, workability is extremely poor, it is not suitable for mass production, and because carbon fiber has a high elastic modulus The effect of reducing the meshing noise, which is the original purpose of the fiber-reinforced resin gear, is small. Furthermore. Further, a fiber-reinforced resin gear reinforced only with glass fibers has a very high attacking property against a mating gear, so that it is fatal from the viewpoint of wear resistance of the mating gear particularly when aiming for a high load application. On the other hand, a fiber-reinforced resin gear reinforced with a meta-polyamide fiber has good workability, is effective in reducing noise, and has good wear characteristics including its own wear resistance and opponent attack.

By the way, in recent years, in fiber-reinforced resin gears,
It is desired to have good gear cutting, wear resistance of the teeth, strength of the teeth, and load resistance. The present invention has been made in view of the above circumstances, and an object thereof is to provide a fiber-reinforced resin gear having workability during gear cutting, strength of a tooth portion, and wear resistance.

[0006]

A fiber-reinforced resin gear according to the present invention has a rod shape formed by winding a prepreg.
Tooth-cut the ring-shaped material obtained by molding and solidifying the donut-shaped preforming material that is made into a donut shape by combining both ends of the rod shape,
A fiber-reinforced resin gear in which the fibers of the base material that constitutes the prepreg on the meshing surface of the teeth are oriented in the shape of a tree ring, and the base material is a mixture of soft fibers with good workability and hard fibers with high strength. It is characterized by being woven.

In the fiber-reinforced resin gear according to the present invention, the fibers are oriented on the meshing surfaces of the teeth in the shape of a tree ring. Here, the annual ring shape of a tree means that the fibers are orientated in multiple directions, and includes a mode in which they are oriented in a ring shape, a mode in which they are oriented in a semi-circular shape, and a mode in which they are oriented in a partial ring shape. The base material is formed by mixing and weaving soft fibers having good processability and hard fibers having high strength.
The degree of mixed weaving can be appropriately selected according to the required characteristics of the gear, but when the total fiber amount is about 30 to 70% in volume%, the soft fiber is about 95 to 40% in the total fiber amount, and the hard fiber is 5%. It can be about 60%.

The soft fiber used in the fiber-reinforced resin gear of the present invention means a fiber having an elastic modulus lower than that of the hard fiber. The soft fiber is basically not limited to any particular one as long as it can form a gear, but a meta-aramid fiber is preferable from the viewpoints of its machinability and reduction of meshing noise. Hard fiber means a fiber having a higher elastic modulus than a soft fiber. Carbon fibers, para-aramid fibers, and glass fibers can be used as the hard fibers. Carbon fiber has a high elastic modulus, high strength, and excellent wear resistance.

In the fiber-reinforced resin gear of the present invention, the total amount of fibers is not particularly limited and may be arbitrarily set according to the required characteristics of the gear. Considering this, the total volume ratio of the fibers is preferably around 50%, particularly preferably 40 to 60%. The matrix resin used in the fiber-reinforced resin gear of the present invention may be various thermosetting resins such as phenol resin, epoxy resin and polyimide resin, or various thermoplastic resins such as PES, PEEK and PAI. That is, any resin may be used as long as it can be combined with the soft fiber or the hard fiber by some method.

[0010]

The function of the tooth portion is that it has the characteristics of a soft fiber having good workability and the characteristics of a hard fiber having high strength.

[0011]

【Example】

(Example 1) (1) Production of prepreg A phenolic resin melted in a varnish form with a solvent is used, and a plain weave woven fabric in which aramid fibers and carbon fibers are integrally mixed and woven is used as a base material. .. Then, the phenolic resin was impregnated into the mixed woven cloth, and then the solvent was dried and removed. Thus, a prepreg sheet made of aramid fiber, carbon fiber and phenol resin was prepared. Then, this prepreg sheet was cut into parallelogram shapes as shown in FIG. The prepreg 1 has sides 1a to 1d, and the side 1a is inclined at an angle θ (5 °) with respect to the direction perpendicular to the side 1c. Here, the prepreg 1 has a length L1 of 235 mm and a width L2 of 228.
mm, thickness 0.2 mm. In this prepreg 1, as shown in FIG. 2, the fiber orientations of the fibers 1x and 1y are 0 ° and 90 ° with respect to the side 1c.

In the prepreg 1 described above, the aramid fiber is 80% and the carbon fiber is 20% in volume%,
The basis weight is 140 g / m ² . The characteristics of the aramid fiber that constitutes the above prepreg 1 will be described. That is, the fiber material is meta-aramid ("Conex", Teijin Ltd.), and the filament property is a strength of 80 kg.
/ Mm ² , elongation 27%, elastic modulus 1250 kg / mm
² , yarn count is 20 tex.

The characteristics of the carbon fiber constituting the above prepreg 1 will be described. That is, the fiber material is graphite (“Besfight” from Toho Rayon Co., Ltd.)
The strength of the filament is 380 kg / m.
m ² , elongation 1.6%, elastic modulus 23500 kg / mm
² , yarn count is 67 tex. Here, the meta-aramid fiber has a low elastic modulus as described above, is excellent in machinability, and has a feature of suppressing the generated sound of the meshing surface of the gear etc. to be low. Further, the carbon fiber has a high elastic modulus as described above, is excellent in strength, has a small friction coefficient, and is excellent in wear resistance.

(2) Manufacture of ring-shaped material Next, as shown in FIG. 1 (A), a prepreg 1 cut into parallelograms is used, and the prepreg 1 is spirally wound from one side 1c to form a rod shape. To do. Next, as shown in FIG. 1 (C), a mating portion 3a is formed so that one end and the other end of the rod-shaped prepreg 1 are aligned with each other, and the prepreg 1 is curved to form the doughnut-shaped preform 3. Obtained. Here, the mating part 3a of the doughnut-shaped preform material 3 (coil bar matching)
Has an overlapping structure in order to avoid a decrease in strength of the same portion. The length of overlap can be arbitrarily set by devising the shape of the prepreg 1 shown in FIG.

As shown in FIG. 3, two doughnut-shaped preforms 3 thus obtained are stacked on each other so that the mating portions 3a are opposed to each other by 180 °, and the doughnut-shaped preform 3 is placed in the mold 4 shown in FIG. set. At this time, a ring-shaped steel insert 5 having a central hole 5e is arranged in the mold 4. This mold 4
Is a lower die 40 having a positioning protrusion 40a at the bottom of the cavity, a cylindrical pressure punch 41 having a ring-shaped pressure surface 41a inserted into the cavity of the lower die 40, and a central hole of the pressure punch 41. It is composed of a core 42 inserted through 41b. Then, the insert 42 is held by the core 42, and the doughnut-shaped preforming material 3 which is vertically arranged in the cavity is pressed by the pressure punch 41 in the arrow E direction to perform heat compression molding. As a result, the resin component in the prepreg 1 was solidified to form the ring-shaped material 6 shown in FIG. The molding conditions at this time are a temperature of 180 ° C., a pressure of 250 kgf / cm ² , and a pressing time of 15 minutes.

In the ring-shaped material 6 shown in FIG. 5, the concave portions 5a and the convex portions 5b of the steel insert 5 and the inner peripheral portion of the fiber reinforced resin portion are firmly bonded. Ring-shaped material 6 in Figure 6
The cross section of FIG. The fiber-reinforced portion 6a of the ring-shaped material 6 is
It is reinforced with both uniformly dispersed aramid fibers and carbon fibers. Here, the ring-shaped material 6 has an inner diameter L
7 is 40.0 mm, outer diameter L9 is 79.0, and thickness t is 10
mm, and the outer diameter L8 of the insert 5 is 55 mm. Further, in the fiber-reinforced portion 6a of the ring-shaped material 6, the total fiber amount is 50% by volume, and the total fiber amount is 80% by volume%.
Is aramid fiber and 20% is carbon fiber.

(3) Gear cutting processing The ring-shaped material 6 shown in FIG. 5 is used.
The outer peripheral portion was subjected to tooth cutting by cutting with a cutter to obtain a fiber reinforced resin gear 8 having tooth portions 7 on the outer peripheral portion as shown in FIGS. 7 and 8. At this time, some of the fibers are cut off by cutting during the gear cutting process. The specifications of the fiber-reinforced resin gear 8 are as follows. That is,
The type is an involute helical gear with a tip diameter of 7
9.0 mm, root diameter 66.9 mm, pitch circle diameter 73.9 mm, total tooth depth 6.05 mm, number of teeth 32,
Right angle module is 2.0, tooth pressure angle is 18.0 °,
The twist angle is 30 °.

The orientation form of the fibers according to this embodiment is shown in FIG.
It shows in FIG. FIG. 7 mainly shows the annual ring-shaped fiber orientation of the tree on the meshing surface 70 of the tooth portion 7. Further, FIG. 8 omits the fibers oriented in a tree ring shape, and shows another fiber orientation in the meshing surface 70. As shown in FIG. 7, in the fiber-reinforced resin gear 8 according to this embodiment, the fibers 100 are oriented in a tree ring shape at the meshing surface 70 of the tooth portion 7. Further, on the tooth top surface 75 as the outermost peripheral surface of the tooth portion 7, the fiber 101 extending substantially in the circumferential direction and the fiber 1 extending along the axis K of the gear are provided.
02 intersects with each other and is oriented. Further, on the shaft end surface 76 of the tooth portion 7, a fiber 103 extending substantially in the circumferential direction and a fiber 104 extending substantially in the radial direction with respect to the shaft axis K of the gear are oriented to intersect. Further, as shown in FIG. 8, in the meshing surface 70 of the tooth portion 7, the cut end surface 103 a of the fiber 103 extending in the circumferential direction, which is cut during gear cutting, is meshed with the meshing surface 70.
It is exposed on the surface of.

The fiber composition ratio of the composite reinforcing portion 7b can be arbitrarily set by changing the basis weight of the fiber cloth used. By the way, in using the gear, the tooth base 72 is the most severe stress portion of the tooth portion 7. In this regard, in this embodiment, the fibers 104 extending substantially in the radial direction are oriented with respect to the axis K of the gear, and the fibers 104 are also carbon fibers having a high elastic modulus. Therefore, the tooth base 72 of the tooth portion 7
The strength can be increased.

Further, in using the gear, a portion requiring wear resistance is a pitch circle 73 of the meshing surface 70 of the tooth portion 7.
A portion near or slightly inward of the pitch circle 73,
That is, it is a portion between the pitch circle 73 and the root 72 in the radial direction. In this respect, in this embodiment, as can be understood from FIG. 7, annual ring-shaped fibers 100 are oriented on the entire surface of the meshing surface 70, and since the fibers 100 are also carbon fibers excellent in wear resistance and strength, It is also possible to improve wear resistance.

(Other Examples) Using the prepreg 1 in which the aramid fiber and the carbon fiber used in Example 1 are mixed and woven,
In the prepreg 1, the total volume ratio of fibers is
Although it was set to 50% as in the above case, only the mixed weaving ratio of aramid fiber and carbon fiber was changed as shown in Table 1. Then, through the same forming process and gear cutting process as in Example 1, fiber-reinforced resin gears (NO.a to NO.f) having exactly the same outer shape as in Example 1 were created.

[0022]

[Table 1] Here, NO. a-NO. Also in the fiber-reinforced resin gear according to f, the aramid fiber and the carbon fiber are oriented in a tree ring shape at the meshing surface 70 of the tooth portion 7.

(Comparative Example) As Comparative Example 1, a fiber-reinforced resin gear having exactly the same appearance as in Example 1 was used, in which the total volume ratio of the fibers was 50% and the fibers were aramid fibers only. Formed (NO.g). In addition, Comparative Example 2
As a result, a gear having only carbon fibers was prepared (NO.h).

[0024]

[Table 2] (Test) Using the fiber-reinforced resin gear of Example 1, the fiber-reinforced resin gear of other Examples, and the fiber-reinforced resin gears of Comparative Examples 1 and 2, the following (1) Bending strength of tooth tips of tooth portions is described below. ,
(2) Abrasion resistance of the meshing surface of the tooth portion and (3) Gear cutting workability test were conducted.

(1) Bending Strength Test of Tooth Tip of Tooth 7 In this test, a gear was fixed and a bending load was applied to the tooth 7 in the vicinity of the pitch circle to measure the breaking load. The result is shown in FIG. The vertical axis of FIG. 9 represents the bending load, and the horizontal axis represents the carbon fiber content volume ratio in the fiber. That is, FIG. 9 shows the case where the left end is only aramid fibers and the right end is only carbon fibers.

According to the test results shown in FIG. 9, the bending load is the smallest, that is, NO. g
Is. And NO. a, NO. b, NO. c, N
O. d, NO. e, NO. f, NO. The bending load increases in the order of j, that is, as the carbon fiber content increases. Among them, NO. In h,
The bending load is the largest.

(2) Abrasion resistance test In this test, a drive gear made of steel (SCr20) whose surface was nitrided was used, and a driving torque of 3 kg-m was applied to the above various gears at a rotation speed of 2000 rpm. The amount of wear of the meshing surface 70 of the tooth portion 7 after driving for 50 hours was measured. The test results are shown in FIG. The vertical axis in FIG. 10 represents the amount of wear on the meshing surface, and the horizontal axis represents the volume fraction of carbon fibers contained in the fibers.

From the test results shown in FIG. 10, NO. In g, the wear amount exceeds 80 μm, and the wear amount is the largest. And NO. a, NO.
b, NO. c, NO. d, NO. e, NO. f, NO.
The wear amount decreases in the order of j, that is, as the carbon fiber content increases. Among them, the NO. In h, the amount of wear is the smallest.

(3) Test of Workability of Gear Cutting A gear cutting machine having a toothing tool whose cutting edge is composed of a diamond tip was used to judge the workability by the number of teeth which can be processed by one toothing tool. The judgment is based on JI
It was set to S4 grade, and when it was out of this accuracy range, it was set as the processing limit. The test results are shown in FIG. Here, the vertical axis of FIG. 11 represents the number of machinable materials, and the horizontal axis represents the carbon fiber content volume ratio in the fiber. As shown in FIG. 11, the best workability for gear cutting is N reinforced only with aramid fibers.
O. It is g. And NO. a, NO. b, NO.
c, NO. d, NO. e, NO. f, NO. in the order of j,
That is, the processable number decreases as the carbon fiber content increases. Among them, N reinforced only with carbon fiber
O. It can be seen that in h, the number of machinable is the smallest and the machinability is poor.

(Comprehensive Evaluation) In view of gear cutting workability and gear meshing noise (backlash noise), it is preferable that the amount of high elastic modulus carbon fiber is small. Further, considering the bending strength of the tooth portion 7 and the wear resistance of the tooth portion 7, the larger the amount of carbon fiber, the better. Therefore, when the total amount of fibers is 50% by volume, the carbon fibers are preferably 5 to 50% in the total amount of fibers, and 10 to 40% in order to reduce gear meshing noise, wear resistance, and gear cutting workability. More preferable.

[0031]

According to the fiber-reinforced resin gear of the present invention, the tooth portion has both the characteristics of the soft fiber having good workability and the characteristics of the hard fiber having high strength. Therefore, it is possible to secure the strength and wear resistance of the tooth portion while improving the workability in gear cutting. In particular, when the hard fibers are oriented substantially in the radial direction with respect to the shaft center of the gear, it is advantageous to increase the strength of the root of the tooth portion.

[Brief description of drawings]

1A, 1B, and 1C are diagrams showing a process of forming a doughnut-shaped preform by using a prepreg of a base material in which aramid fibers and carbon fibers are mixed and woven.

FIG. 2 is a development view of a prepreg of a base material in which aramid fibers and carbon fibers are mixed and woven.

FIG. 3 is a perspective view of a state where two doughnut-shaped preforming materials are stacked.

FIG. 4 is a cross-sectional view at the time of compression-molding two donut-shaped preforms stacked in a mold.

FIG. 5 is a perspective view of a ring-shaped material.

FIG. 6 is a diagram schematically showing a cross section of a ring-shaped material.

FIG. 7 is a partial perspective view of a tooth portion of a fiber-reinforced resin gear, which is shown together with the orientation of annual ring-shaped fibers of a tree.

FIG. 8 is a partial perspective view of a tooth portion of a fiber-reinforced resin gear showing a part of fiber orientation.

FIG. 9 is a graph showing the relationship between bending load and carbon fiber content.

FIG. 10 is a graph showing the relationship between the amount of wear and the carbon fiber content.

FIG. 11 is a graph showing the relationship between the number of machinable and the carbon fiber content.

[Explanation of symbols]

In the figure, 1 is a prepreg, 3 is a doughnut-shaped preform, 4
Is a die, 6 is a ring-shaped material, 7 is a tooth portion, and 70 is a meshing surface.

Claims (1)

[Claims] 1. A prepreg is wound to form a rod,
Tooth-cut the ring-shaped material obtained by molding and solidifying the donut-shaped preforming material that is made into a donut shape by combining both ends of the rod shape,
A fiber-reinforced resin gear in which the fibers of the base material forming the prepreg on the meshing surfaces of the teeth are oriented in a tree ring shape. The base material is a mixture of soft fibers with good processability and hard fibers with high strength. A fiber reinforced resin gear characterized by being woven.