JPH0367458B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing gears.

[Prior art and its problems]

Gear manufacturing has traditionally been carried out using hobbing machines dedicated to gear cutting.
This is done by cutting using a gear cutting machine such as a Ferrous machine. As a result, the product accuracy was high, but it was unsuitable for mass production and had the drawbacks of being extremely expensive.

[Purpose of the invention]

In view of this, it is an object of the present invention to provide a method for manufacturing gears that is suitable for manufacturing relatively small gears such as pinions and that allows mass production of inexpensive gears.

[Summary of the invention]

In order to achieve the above object, the present invention comprises a mold having a tooth pattern on the inner circumferential surface, and a processing rod that is press-fitted into the inner hole of an annular material having an outer diameter slightly smaller than the inner diameter of the mold. The processed rod has an outer diameter that allows the smallest diameter portion to fit into the inner hole of the material as tightly as possible,
The maximum diameter part has an outer diameter equivalent to the inner hole diameter of the product gear, and there are several parallel shaft parts from the minimum diameter part to the maximum diameter part, and the distance between each parallel shaft part is relative to the axis.
They are connected by a tapered shaft part of 20 degrees or less, and the press rod is inserted into the inner hole of the material in the mold from the smallest diameter part, and then the processing rod is press-fitted to gradually release the material. A gear product is obtained by expanding the material and press-fitting the outer periphery of the material into the tooth pattern of a molding die.

[Embodiments of the invention]

The present invention will be described below with reference to embodiments shown in the drawings.

The molding die 1 has a tooth pattern 2 of a gear to be molded formed on its inner circumferential surface, and a protruding edge 1A that supports the lower surface of the outer peripheral edge of the material 3 is formed at the lower part of the tooth pattern 2.

The material 3 has an annular shape having an outer diameter slightly smaller than the inner diameter of the mold 1, and has an inner hole 3A having a sufficient wall thickness required for the tooth forming shape.

The processing rod 4 has a minimum diameter portion 4A at the tip of the material 3.
It has a cylindrical shape with an outer diameter that can fit as tightly as possible into the inner hole 3A of the product gear 5, and the inner cylindrical shape has an outer diameter that corresponds to the inner diameter of the inner hole 5A of the product gear 5. It has a plurality of (two in the illustrated example) parallel shaft parts 4C and 4D from the minimum diameter part 4A to the maximum diameter part 4B,
Between the minimum diameter portion 4A and the parallel shaft portion 4C, the parallel shaft portion 4C,
4D, and between the parallel shaft portion 4D and the maximum diameter portion 4B, the angle θ with respect to the axis is 20° or less (preferably
It is continuous with tapered shaft portions 4E, 4F, and 4G (approximately 8 degrees). Therefore, the diameter difference d of each shaft portion is formed to gradually increase by about 0.5〓 in radius.

In FIG. 1, reference numeral 6 denotes a holding member for fixing the material 3 within the mold 1.

Next, the gear manufacturing process will be explained.

A ring-shaped material 3 is inserted into a mold 1 to form a projecting edge 1.
Place it on A and fix it with the presser member 6. Next, the minimum diameter part 4A of the processing rod 4 is inserted into the inner hole 3A of the material 3 (left side in FIG. 1), and when the processing rod 4 is pressurized in the direction of the arrow by hydraulic or mechanical means, the material 3 is As the inner hole 3A is expanded, the outer circumferential surface of the material 3 is plastically deformed so as to bulge into the tooth mold 2 (Fig. 4A), and the material 3 passes through the next parallel shaft portion 4C and is further expanded by the tapered shaft portion 4F. It is expanded and press-fitted into the tooth mold 2 (Fig. 4B). Further, it is press-fitted by the next tapered shaft part 4F as shown in Fig. 4C, and when it comes to the time when the final maximum diameter part 4B is press-fitted, it is press-fitted into the tooth mold 2 in a full state as shown in Fig. 4D. Ru.

Thereafter, the processed rod 4 is pulled out, the presser member 6 is removed, and the molded material 3 is pulled upward to obtain a gear product 5 as shown in the third figure.

In the process of obtaining the gear product 5 as described above, as shown in FIG. It is precisely molded along the mold 2. Even if the tip of the tooth changes, it will not cause any practical problems.

In order to ensure that the tooth tip is sufficiently formed, a protrusion 2A is formed in the portion corresponding to the tooth tip, as shown in FIG. 5, one of the tooth molds 2. By allowing the material to enter both sides of 2A, it is possible to form a tooth in which the material reaches the tip of the tooth. In addition, as shown in FIG. 6, the tooth 5B of the gear
When manufacturing a partially toothed gear 5', the cross-sectional shape of the working rod 4 is not a perfect circle like the shape of the inner hole 5'A of the partially toothed gear 5' in the same figure. It is sufficient that only the range forming 5B can be expanded. Further, the tooth profile of the gear is not limited to a straight line, and even a helical gear can be manufactured as long as the material can be rotated and extracted from the molding die 1. The number of tapered shaft portions and parallel portions of the processing rod 4 can be appropriately selected depending on the size and hardness of the material 3.

〔Effect of the invention〕

As explained above, the present invention includes a mold having a tooth pattern on the inner circumferential surface, and a processing rod that is press-fitted into the inner hole of an annular material having an outer diameter slightly smaller than the inner diameter of the mold. The working rod has an outer diameter that allows the smallest diameter part to fit into the inner hole of the material as tightly as possible, and the largest diameter part has an outer diameter corresponding to the inner hole diameter of the product gear. It has several parallel shaft parts from the smallest diameter part to the largest diameter part, and the distance between each parallel shaft part is relative to the axis.
They are connected by a tapered shaft part of 20 degrees or less, and the pressure rod is inserted into the inner hole of the material in the mold from this minimum diameter part, and then the processing rod is press-fitted to gradually release the material. By expanding the material and press-fitting the outer periphery of the material into the tooth pattern of the molding die, a gear product was obtained.
Gear products can be completed in a single process of loading the annular material into the mold and then pushing the processing rod into it.
Compared to cutting using a conventional gear cutter, the time required for machining is much shorter, and the equipment used for machining requires only a mold, a processing rod, and a means for pressing the processing rod, making it inexpensive. In addition, since the material is pressurized and expanded sequentially using the tapered shaft section and the parallel shaft section provided in stages on the processing rod, unreasonable internal stress is not generated in the material, allowing for smooth expansion. This method has the advantage of being suitable for mass production and producing gear products at low cost, such as being able to manufacture any type of gear in one step as long as it has a tooth shape that can be extracted from a mold.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, in which the left half is a cross-sectional view showing the state before processing and the right half shows the state after processing;
Fig. 2 is a sectional view taken along the - line in Fig. 1, Fig. 3 is a plan view of the gear product obtained by the processing shown in Fig. 1, and Fig. 4 is a plan view of the gear product obtained by the processing shown in Fig.
Figures A to D are explanatory diagrams showing the process of forming the tooth profile, Figure 5 is a sectional view showing a modification of the tooth profile of the mold, and Figure 6 is a plan view showing another example of the gear product. 1...Molding mold, 1A...Protrusion, 2...Tooth mold,
3...Material, 3A...Inner hole, 4...Processing rod, 4A
...Minimum diameter part, 4B...Maximum diameter part, 4C, 4D...
...Parallel shaft part, 4E, 4F, 4G...Tapered shaft part, 5...Gear product, 6...Press member.

Claims (1)

[Claims] 1. Using a molding die with teeth on the inner peripheral surface and a working rod that is press-fitted into the inner hole of an annular material having an outer diameter slightly smaller than the inside diameter of this mold, this working rod is
The minimum diameter portion has an outer diameter that allows it to fit into the inner hole of the material as tightly as possible, the maximum diameter portion has an outer diameter that corresponds to the inner hole diameter of the product gear, and from these minimum diameter portions to the maximum diameter portion It has several parallel shaft parts, and each parallel shaft part is connected with a tapered shaft part of 20 degrees or less with respect to the axis, and the pressure rod is inserted into the material in the mold from this minimum diameter part. A method for manufacturing gears, which comprises inserting the material into a hole, then press-fitting a processed rod to expand the material step by step, and press-fitting the outer periphery of the material into the teeth of a molding die to obtain a gear product.