JPS62282766A - Manufacture of composite gear - Google Patents

Abstract

PURPOSE:To improve the accuracy of a product, and to reduce the manufactur ing cost by integrally casting a gear body of a high-grade cast iron material such as graphite cast iron, etc., by a high accuracy casting method, and subse quently, bringing a tooth part to a rolling work. CONSTITUTION:Necessary frames of a coarse material forming cavity 11, an accessory part cavity 12, etc., of a gear body 1 are formed in the upper and lower casting frames 5, 6, and also, packed with quartz sand, by which the upper and lower casting molds 3, 4 are formed. Subsequently, the upper and lower faces of the upper and lower molds 3, 4 are covered with plastic films 7, 8, 9 and 10, and as a vacuum pressure reduction molding casting mold, the gear body 1 is cast by a high-grade cast iron material such as an FCD 70, etc. Next, with respect to this coarse material casting 14, a rolling work is executed by setting a rolling tool 15 having a desired tooth form to a rolling device. In this way, a tooth part 2 having a high accuracy is formed, and as for the gear, its strength and wear resistance are improved. Since the gear can be manufactured by an integral structure, not only the accuracy of a product is improved but also the cost can be reduced.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Industrial Field of Application] The present invention provides a gear that has different properties such as strength and hardness in the vicinity of the tooth portion and other inner portions (this invention lll11! In F, it is called a compound gear), for example, self! The present invention relates to a method of manufacturing a composite gear such as a flywheel gear, which is one of the engine parts of an ALJ vehicle.

[Conventional technology]

For example, a composite gear such as a flywheel gear, where the outer tooth part requires strength and precision, and the inner part is required to have good compatibility (and wear resistance) with the clutch plate in sliding contact, is made of cast iron. The conventional manufacturing method has been to shrink-fit or press-fit a ring gear with teeth formed on a plate by cutting.

[Problem that the invention seeks to solve]

However, as mentioned above, the conventional method for making a composite gear is to separately make the inner ring gear and the outer ring gear, and then combine them to form a gear body.
However, since the ring gear requires all teeth to be formed by cutting, it has not always been satisfactory in terms of manufacturing costs and the like.

The present invention was made in view of the above-mentioned problem, and requires less man-hours and materials51! ! Reduce manufacturing costs, achieve desired accuracy and achieve W1! I! It is an object of the present invention to provide a manufacturing method that can inexpensively supply a composite gear having I.

[Means for solving problems]

The present invention has achieved the above object by combining the conventional basic idea and method of forming the teeth of a composite gear by cutting, and by using cutting and rolling.

In other words, the gear body consisting of the outer teeth and the inner part is integrally made of high-grade rock iron such as spheroidal graphite cast iron or malleable cast iron using a high-precision casting method such as the 7R method using a vacuum molding method or a shell mold. After casting, the manufacturing process includes a step of subjecting the tooth portion to a main-main rolling process of the cast surface. In addition,
It is the same as before or after the rolling process to machine necessary parts other than the tooth portions to finish the product.

[For production]

When the gear body is integrally molded using a high-precision casting method such as the casting method using the main shell mold disappearing model method, the casting surface of the cast product (rough material) is fine and smooth (in the case of the vacuum molding method, the surface The roughness is about 10 to 203), so even if the tooth part is rolled, there will be no damage such as chipping or scratches on the tooth part (the tooth profile can be formed with extremely high precision). .

In addition, since the material used is high-grade cast iron such as spheroidal graphite cast iron, it is possible to satisfy the strength required for the tooth profile, and the inner part also satisfies the strength and wear resistance. It blends well with the board.

Furthermore, since high-grade cast iron material is used, a tooth profile with satisfactory dimensional accuracy can be obtained by rolling, combined with the high-precision casting method mentioned above, and the surface of the tooth profile is work-hardened by rolling to further increase strength. Improves wear resistance.

Note that if further wear resistance of the tooth portion is required, surface treatment such as hardening may be performed.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a flywheel gear *a, which is an automotive engine part, will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view showing an example of a flywheel gear. Conventionally, a clutch disc portion (inner portion) Ia and a ring gear 2a having a tooth portion 2 are separately manufactured, and both are separated. They were fixed to each other by shrink fitting or the like and were integrated into a gear body 1.

Figure 152 is a longitudinal sectional view of the vacuum molding mold used in the present invention.

The mold (upper mold 3, lower mold 4) is prohibited (upper mold 5, lower mold 6)
Inside, necessary spaces such as a rough material cavity 11 for forming the rough material of the gear body 1 and an accessory cavity 12 necessary for deaf construction such as sprues and runners are formed and filled with silica sand. Type 3
and the upper and lower surfaces of the lower mold 4 are covered with a plastic film 7.
．． 8 and 9.10, respectively, and each mold is sealed. The inside of each mold is designed to be vacuum-suctioned in the direction of the arrow, and the raw material cavity 11 and attached cavity 12 are in communication with a ventilation hole 13, and the ventilation hole 13 is kept open during pouring of the molten metal. Atmospheric pressure is applied through it.

When the rough material of the gear body 1 shown in FIG.

Thereafter, as shown in the schematic diagram of Fig. 3, the rough material 14 and the rolling material 15 having the desired tooth profile are set in the rolling device ID (not shown), the rolling process is performed, and the teeth are rolled. Part 2 was finished into the desired shape.

As a result, the target highly accurate tooth portion 2 was obtained, the surface portion was work-hardened, the hardness increased, and the tooth portion had excellent strength and wear resistance.

Figure 5 shows the microscopic structure of the tooth area before rolling and Figure 6 shows the microscopic structure near the tooth after rolling. It can be seen that the rolling process is effective. Furthermore, the surface hardness increased from HRC=17 before rolling to HRC=29 after rolling, indicating sufficient work hardening.

(Example 2) Using the same vacuum molding mold as in Example 1, the rough material of the gear body 1 shown in FIG. A rough material with .

Thereafter, this raw material was subjected to rolling processing in the same manner as in Example 1, and the tooth portion 2 was shaped into a desired shape.

As a result, the target highly accurate tooth portion 2 was obtained, the surface portion was work-hardened, the hardness increased, and the tooth portion had excellent strength and wear resistance.

Figures 7 and 18 are micrographs of the vicinity of the teeth before and after rolling, and the rolling process shows that the surface layer S has a base material (pearlite, pearlite,
ferrite) and carbon are rolled out to form a layered structure, and it can be seen that the rolling process has the same effect as in Example 1.

Furthermore, the surface hardness was HRC 12 before rolling, but it increased to HRR 23 after rolling, indicating sufficient work hardening.

According to the present invention, in the same manner as in the above embodiment, the PI
The gear body 1 having the reinforcing lip 16 on the side surface of the tooth portion 2 as shown in Fig. S4 can be easily manufactured (
Because of the reinforcing lip 16, manufacturing using the conventional method by gear cutting is impossible).

〔Effect of the invention〕

As described above, according to the method of the present invention, it is possible to easily manufacture a composite gear with different properties between the teeth and the inner part, such as a 7-line wheel gear, with high precision and high efficiency. It is possible to save on materials and materials, reduce manufacturing costs, and provide inexpensive products.

Although the above description has mainly been given to a flywheel gear for an automobile engine, the present invention is not limited to this, but can also be applied to composite gears used for various purposes, and the industrial effects are extremely large. be.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a composite gear, Pt52 is a longitudinal sectional view of a vacuum forming mold, Fig. 3 is a schematic diagram of rolling process, and Fig. 4 is a partial perspective view showing another example of a compound gear. , FIG. 5, FIG. 6, Pt47, and FIG. 8 are micrographs showing the metal structure in the vicinity of the tooth portion before and after rolling. 1: Gear body, 1a: Inside part, 2: Tooth part, 3:
Upper mold for vacuum molding, 4: Lower mold, 5: Bond frame, 6: Lower frame, 7.8.9.10 Niblastic film, 11: Raw material cavity,
13: Ventilation hole, 14: Rough material, 15:
Matsuyuki Engineer Agent Patent Attorney Honma Takashi ζI; Σ /lgo', ≦2 箭72%,? Figure, sJX iθ and

Claims (6)

[Claims] (1) A method for manufacturing a composite gear, comprising the steps of integrally casting a gear body including teeth using high-grade cast iron using a high-precision casting method, and rolling the teeth. (2) The method for manufacturing a composite gear according to claim 1, wherein the high-precision casting method is a vacuum molding method or a vanishing model method. (3) The method for manufacturing a composite gear according to claim 1, characterized in that at least the tooth portions are cast using a shell mold. (4) The method for manufacturing a composite gear according to any one of claims 1 to 3, wherein the high-grade cast iron is spheroidal graphite cast iron or malleable cast iron. (5) Claims 1 to 4, characterized in that the surface of the tooth portion after rolling is hardened by surface hardening treatment.
A method for manufacturing a composite gear according to any one of paragraphs. (6) The method for manufacturing a composite gear according to claim 5, characterized in that hardening is performed by quenching.