JP2001124180A - Composite gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite gear for improving reliability by forming a tooth part as high strength, reducing operation time noise as high damping capacity, capable of being housed in a prescribed space in a proper width and being applicable to a timing gear of a diesel engine for an automobile. SOLUTION: A tooth part is formed of a steel material, a boss part is formed of a high damping capacity material composed of either of a flake graphite cast iron material, a vermicular cast iron material or a spherical graphite cast iron material, the tooth part and the boss part are frictionally brought into pressure contact with each other, and a main part of a frictional pressure contact part is formed in an almost parallel or taper shape in a shaft directional cross-sectional view.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound gear which is used at a high speed especially in an engine or a motor, and in which one gear is made of a combination of different materials.

[0002]

2. Description of the Related Art Conventionally, carbon steel, alloy steel, and the like have been used for gears used at high speeds such as timing gears of automobile diesel engines. However, these materials have a low damping ability, so that noise is increased when gears are used in combination. Means for reducing such noise have been studied.

For example, as a gear manufactured from a material having a higher damping capacity than carbon steel or alloy steel, "Automotive Technology, Vol. 50, No. 5, 1996.23-28.
Page, there is a description entitled "Development of Austempered Spheroidal Graphite Cast Iron Timing Gears" to manufacture gears by austempering ductile cast iron. According to this, low vibration and low noise can be realized while securing the same toughness as a conventional steel gear.

Further, when a gear is mounted on a shaft, noise is reduced by interposing a material having a high damping capacity between the gear and the shaft. Japanese Unexamined Utility Model Publication Nos. It is disclosed in, for example, JP-A-131155.

[0005] In addition, research has been conducted on a compound gear combining a plurality of parts made of different materials, instead of a gear integrally formed of a single material. For example, a combination of a tooth part made of a material such as carbon steel having excellent strength and a boss part made of a material such as cast iron having a high damping ability is disclosed in Japanese Utility Model Application Laid-Open No. 60-739.
62.

On the other hand, JP-A-6-109101 discloses a shaft-integrated gear in which a tooth portion made of a Cu alloy is friction-welded to a hollow or solid shaft portion. According to this, hydraulic machines that can be joined in a short time and have excellent joining strength
It is said to be a wear-resistant Cu alloy gear that slides on machine structural steel, tool steel and the like in various industrial machines such as machine tools.

[0007]

However, the conventional gear described above has the following problems. First, when gears are manufactured by austempering a ductile cast iron, the strength of the gears is improved, but the effect on fatigue strength and impact strength may be small,
The scope of application may be limited.

Further, when a material having a high damping ability is disposed between the gear and the shaft, the number of parts and the number of processing and assembling steps also increase.

Further, in the conventional compound gear, since it is common to combine the tooth portion and the boss portion by shrink fitting, high machining accuracy is required for the fitting portion of both, and the manufacturing cost is increased. There is.

On the other hand, the gear disclosed in Japanese Patent Application Laid-Open No. 6-109101 has abrasion resistance, but is not high in strength.
Further, although there is no description in the publication, the attenuation ability is still insufficient.
Usually, friction welding is performed by abutting the end faces of both members to be joined. However, when the abutting is performed, the width of the gear is increased, and it may be difficult to fit the gear in a predetermined space.

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned conventional problems, and the reliability is improved by increasing the strength of the teeth.
It is an object of the present invention to provide a compound gear that can reduce noise during operation as a high damping capacity and can be set in an appropriate width to fit in a predetermined space, and can be applied to, for example, a timing gear of an automotive diesel engine.

[0012]

Means for Solving the Problems The present inventors have made intensive studies on the above problems. Then, the tooth portion is made of steel, and the boss portion is made of flaky graphite cast iron material, vermicular cast iron material, or spheroidal graphite cast iron material as a high damping material. The boss has high strength to improve reliability, and the boss has high damping ability to reduce noise during driving. The present inventors have found that a composite gear applicable to the present invention can be obtained, and have arrived at the present invention.

That is, the present invention is characterized in that the teeth are made of a steel material, the bosses are made of a high damping material, and the teeth and the bosses are obtained by friction welding.

Further, the main part of the friction welding part is substantially parallel in an axial sectional view.

Alternatively, the friction welding portion is tapered in a sectional view in the axial direction.

The boss portion is a flaky graphite cast iron material,
It is characterized by being made of either a vermicular cast iron material or a spheroidal graphite cast iron material.

Further, the compound gear is a timing gear of an automotive diesel engine.

If the composite gear is formed by friction welding, processing such as processing before friction welding is simple, and the joining strength is increased to increase reliability.

If the teeth are made of steel, heat treatment such as induction hardening can be easily performed before or after friction welding, and mechanical properties such as tooth root strength and hardness can be imparted according to the use of the gear. .

If the boss is made of any of flaky graphite cast iron, vermiculite cast iron, or spheroidal graphite cast iron, a composite gear having high damping ability is obtained. For example, the flaky graphite cast iron material has about 10 times the damping ability of carbon steel (S450C), and a large damping effect, that is, a noise suppressing effect can be obtained. Also,
The damping ability of vermicular cast iron and spheroidal graphite cast iron is about twice that of carbon steel (S45C) and inferior to flake graphite cast iron, but the tensile strength is more than twice that of flake graphite cast iron. Is preferably used when is required.

The friction welding is a solid-phase welding and can be performed while reducing heat generation. Therefore, when a high carbon material such as a flaky graphite cast iron material, a vermicular cast iron material, and a spheroidal graphite cast iron material is used as the boss portion, this high pressure welding is required. Cementite is not easily generated in the structure of the carbon material, and the tensile strength and the fatigue strength of the joint can be equal to or higher than that of the base material of the high carbon steel material.

If the friction welding portion is substantially parallel or tapered in a sectional view in the axial direction, the gear can be set to an appropriate width and housed in a predetermined space.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG. 1 shows a case in which a tooth portion 2 made of a steel material and a boss portion 3 made of a high damping material are joined together, and the joined portion 1c is viewed in a sectional view in the axial direction. It is sectional drawing of the compound gear 1 formed substantially parallel, (a) is before friction welding,
(B) shows the state after friction welding. Before the friction welding of FIG.
The tooth 2 made of steel has a width 2b, an inner diameter 2d, and an outer circumference 2a.
Are formed with a large number of teeth 2t. On the other hand, the boss portion 3 made of a high damping material has a width 3b which is the same as the width 2b of the tooth portion 2.
The outer diameter is 3d and the inner diameter is 3g. And the boss 3
The outer diameter 3d is slightly larger than the inner diameter 2d of the tooth portion 2. For example, when the inner diameter 2d is 50 mm, the outer diameter 3d is +0.1 to +
1.5 mm larger.

FIG. 3 is a side view of a main part of the friction welding apparatus 5, in which 6 is a main shaft, 7 is a slide, 8 is an electric motor, and 9 is a brake. The friction welding is performed as follows. First, the outer periphery 2a of the tooth portion 2 is fastened by the chuck 6a of the main shaft 6, and the inner diameter 3g of the boss portion 3 is fastened by the chuck 7a of the slide 7. Next, the electric motor 8 is rotated to transmit this torque to the main shaft 6, and the slide 7 is moved to the main shaft 6 side (left side in the drawing) while rotating the main shaft 6, and the inner diameter 2 d of the tooth portion 2 is at the right end surface 2 h. And the outer diameter 3d of the boss 3 is brought into contact with the left end face 3i to generate frictional heat. Then, the boss portion 3 is provided on the left end surface 2i of the tooth portion 2.
The slide 7 is moved until the left end face 3i of the robot arrives to continue the frictional heating. After this friction heating step, the brake 9
The main shaft 6 is suddenly stopped, and is further metallically connected in the upset process. Thereby, as shown in FIG.
The main part of the joint surface 1c is substantially parallel in the axial cross-sectional view, the area of the joint surface 1c is large, the tooth portion 2 has high strength and reliability, and the boss portion 3 is a high damping material so that it can be operated during operation. And the composite gear can be housed in a predetermined space with the width 1b appropriately reduced.

Although an example in which a large number of teeth 2t of the tooth portion 2 are formed before the friction welding is shown, a machining allowance is provided, and after the friction welding, the teeth 1t, the width 1b, and other shafts into which the boss portions are fitted. A hole, a keyway or the like may be formed, and attachment of the tooth portion 2 and the boss portion 3 to the main shaft 6 or the slide 7 by the friction welding device 5 can be appropriately selected. (Embodiment 2) FIG. 2 shows a composite gear 1 in which a tooth portion 2 made of a steel material is joined to a boss portion 33 made of a high-damping material, and the joint portion 4 is formed to be tapered in a sectional view in the axial direction. It is sectional drawing, (a) shows before friction welding and (b) shows after friction welding. Before the friction welding of FIG. 2A, the tooth portion 2 made of steel is
The width 2b and the inner diameter are tapered gradually from 2e to 2f, and a large number of teeth 2t are formed on the outer circumference 2a. On the other hand, the boss portion 3 made of a high damping material has a width 3b which is the same as the width 2b of the tooth portion 2 and has an outer diameter gradually increasing from 3e to 3f. Then, the outer diameter 3e to 3f of the boss 3
Is slightly larger than the inner diameter 2e to 2f of the tooth portion 2, for example, when the inner diameter 2e is 50 mm and the inner diameter 2f is 55 mm, the outer diameter 3e and the outer diameter 3f are respectively +0.1 to +1.5 mm.
I'm making it big.

The friction welding is performed by the friction welding apparatus 5 shown in FIG. 4 as in the first embodiment. First, the outer circumference 2 of the tooth portion 2
a with the chuck 6a of the spindle 6
3 g of the inner diameter of the slide 7 is fastened by the chuck 7 a of the slide 7. next. By rotating the electric motor 8 to transmit this rotational force to the main shaft 6, the slide 7 is moved to the main shaft 6 side (left side in the figure) while rotating the main shaft 6, and the inner diameters 2 e to 2 f of the tooth portion 2 are obtained.
The boss 3 is brought into contact between the outer diameters 3e to 3f to generate frictional heat. Then, the slide 7 is moved until the left end surface 3i of the boss portion 3 reaches the left end surface 2i of the tooth portion 2 to continue frictional heating. After the friction heating step, the main shaft 6 is suddenly stopped by the brake 9 and further metallically connected in the upset step. As a result, as shown in FIG. 2 (b), the main part of the joint surface 1d becomes a taper 5 when viewed in the cross section in the axial direction, the area of the joint surface 1d is large, and the tooth portion 2 has high strength and reliability. In addition, the boss 3 has a high damping capacity and the noise during operation is reduced,
Further, the composite gear can be housed in a predetermined space by appropriately reducing the width 1b.

[0027]

EXAMPLE Spur gears shown in Table 1 were produced with a module of 2.5, 50 teeth, a pitch circle diameter of 125, and a tooth width of 25 mm. In Table 1, in Example 1, the tooth portion was S45C and the boss portion was flaky graphite cast iron material (JIS) FC200. According to the first embodiment, the main portion of the joint surface between the tooth portion and the boss portion after the friction welding was performed. Example 2 is a composite gear manufactured with its parts being substantially parallel in an axial cross-sectional view. In Example 2, the teeth are S45C, and the boss is vermiculite graphite cast iron (JIS) FCV300. The compound gear manufactured in such a manner that the main part of the joint surface between the tooth part and the boss part is substantially parallel in the axial cross-sectional view. In the third embodiment, the tooth part is S45C, and the boss part is spheroidal graphite cast iron material (JIS) FCD370. According to the second embodiment, there is provided a composite gear in which a main portion of a joint surface between a tooth portion and a boss portion after friction welding is tapered in an axial sectional view. On the other hand, Comparative Example 1 is not a compound gear in which the tooth portion and the boss portion are combined, but a gear integrated with S45C. (Table 1) Tooth boss joining method Joint section axial section Example 1 S45C FC200 Friction welding almost parallel Example 2 S45C FCV300 Friction welding almost parallel Example 3 S45C FCD370 Friction welding Taper Comparative example 1 S45C integrated

Next, after the acceleration pickup sensor is attached to the tooth portion 2, the opposing portion is hit with an impulse hammer to give an impact, and the vibration waveform of the ratio of the voltage value to the impulse with respect to the passage of time is measured. The decay capacity was measured with. The results are shown in FIGS.

In FIG. 4, the teeth are S45C and the boss is FC2.
The vibration waveform of the compound gear subjected to friction welding at 00 is converged in about 0.05 seconds. In FIG. 5, the vibration waveform of the composite gear in which the teeth are S45C and the boss is friction-welded with FCV300 is converged in about 0.13 seconds. In FIG. 6, the vibration waveform of the compound gear friction-welded with the teeth being S45C and the boss being FCD370 is converged in about 0.13 seconds. On the other hand, in FIG. 7, the vibration waveform of the gear having the teeth and the boss integrated with S45C is converged in about 0.2 seconds. From the above results, the compound gears of Examples 1 to 3 have a high damping effect, have an effect of suppressing vibration, and have excellent damping ability. The compound gears according to the first to third embodiments are used for a timing gear of an automotive diesel engine to suppress noise.

[0030]

According to the compound gear of the present invention, the reliability is improved by increasing the strength of the teeth, the noise during operation can be reduced by increasing the damping capacity of the boss, and the width is appropriately reduced. It can be stored in a predetermined space. Such a compound gear can be applied to a timing gear of an automotive diesel engine.

[Brief description of the drawings]

FIG. 1 is a composite gear in which a tooth portion made of a steel material and a boss portion made of a high damping material are friction-welded, and a main portion of the joined portion is formed substantially parallel in a sectional view in the axial direction. FIG. 2B is a cross-sectional view before friction welding, and FIG. 2B is a cross-sectional view after friction welding.

FIG. 2 is a composite gear in which a tooth portion made of a steel material and a boss portion made of a high damping material are friction-welded, and a main portion of the joint is tapered in a sectional view in the axial direction. FIG. 3B is a cross-sectional view before the friction welding, and FIG.

FIG. 3 is a side view of a main part of the friction welding device.

FIG. 4 is a diagram showing a vibration waveform of a compound gear that is friction-welded with a tooth portion being S45C and a boss portion being FC200.

FIG. 5 is a diagram showing a vibration waveform of a compound gear frictionally pressed by using a tooth portion of S45C and a boss portion of FCV300.

FIG. 6 is a diagram illustrating a vibration waveform of a compound gear that is friction-welded with a tooth portion being S45C and a boss portion being FCD370.

FIG. 7 is a diagram illustrating a vibration waveform of a gear in which a tooth portion and a boss portion are integrated with S45.

[Explanation of symbols]

1: compound gear, 1b: tooth width, 1c: joining surface (parallel), 1d: joining surface (taper), 2: tooth part, 2
d, 2e, 2f: inner diameter, 3: boss, 3d, 3e,
3f: outer diameter, 5: friction welding device, 6: spindle, 6
a: chuck, 7: slide, 7a: chuck,
8: motor, 9: brake.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiki Yoshida 11 Kinuigaoka, Moka City, Tochigi Prefecture Hitachi Metals Co., Ltd.Material Research Laboratory (72) Inventor Seiichi Endo 11 Kinuokaoka, Moka City, Tochigi Prefecture F term in Shikisha Materials Research Laboratory (reference) 3J030 AA01 BB02 BC10 CA10 4E067 AA04 BG00 EB00

Claims (5)

[Claims] 1. A compound gear obtained by forming a tooth portion of a steel material, a boss portion of a high damping material, and frictionally pressing said tooth portion and the boss portion. 2. The compound gear according to claim 1, wherein main parts of the friction welding are substantially parallel in an axial sectional view. 3. The compound gear according to claim 1, wherein a main part of the friction welding is tapered in a sectional view in an axial direction. 4. The composite according to claim 1, wherein the boss portion is made of one of a flake graphite cast iron material, a vermicular cast iron material, and a spheroidal graphite cast iron material. gear. 5. The timing gear according to claim 1, wherein the compound gear is a timing gear of an automotive diesel engine.
The compound gear according to claim 4.