JPS611439A - Production of spiral bevel gear by rotary forging method - Google Patents

Abstract

PURPOSE:To form a blank material to be formed into the titled gear having no defects in the tooth parts by inserting the blank material between an upper die presser connecting to a spindle and a bottom die having a tooth die in the base of an engraving space and rotating and screwing down the spindle in the helix direction toward the radial outside of the tooth trace of the tooth die thereby rolling the material. CONSTITUTION:The blank material 8 to be formed is inserted between the upper die presser 2 connecting to the spindle 1 and the lower die 4 having the spiral tooth die 6 in the base of the engraving space 5. The spindle 1 is inclined in the axial center by an angle theta and is rotated and screwed down in the helix direction toward the radial outside of the tooth trace of the die 6. The blank material is subjected to rotary forging by a working face 3. The meterial 8 enters thoroughly the tooth 6 and is thus made into the satisfactory spiral bevel gear without having the defects such as under fill and laps in the tooth parts.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a spiral bevel gear, and more particularly to forging a spiral bevel gear by a rotary forging method.

Various forging methods have been attempted for spiral bevel gears, but when using a press forming machine, a large capacity press machine is required, and since the gears are twisted in the direction of the teeth, they have the disadvantage of placing a large load on the mold. In addition, in powder forging, there is a concern that strength may be insufficient due to variations in powder density in the tooth die cross section.

Furthermore, it is also known to manufacture the gear by a rolling method using a rotary forging machine, as in Japanese Patent Publication No. 49-47621, but the disadvantage of this rolling method is that the plunger cannot move forward or backward depending on the specifications of the gear. It is also necessary to change the specifications of the means (helical spline) for forcing rotation around the axis.

Therefore, in order to solve the above-mentioned drawbacks, the inventor developed an upper mold indenter 2 connected to the main shaft 1 of a rotary forging machine as shown in FIG.
and a lower mold 4 in which a toothed part 6 is formed at the bottom of the mold engraving space 5 facing the upper mold indenter, and a material 8 to be formed is inserted between
We came up with the idea of forging so that the toothed part 6 of the lower die is filled with material by applying pressure with the upper die indenter 2.

However, as shown in FIG. 2, when forging is performed by rotating the main shaft 1 in the direction indicated by the arrow, which is opposite to the direction in which the teeth traces of the tooth pattern portion 6 of the lower mold are twisted outward in the radial direction, the molded product 8a is formed. As can be seen in FIG. 4, which shows the cross section IV-IV in FIG. 3, and FIG. 5, which shows substantially the same portion, the tooth portion 9a has a large underfill portion 10. 11 occurs, and a satisfactory product cannot be obtained.

However, as shown by arrow B in FIG. 2, when the main shaft 1 is rotated so as to coincide with the radially outward twisting direction of the tooth line of the tooth pattern portion 6 of the lower mold 4, and the material 8 to be formed is rotary forged,
The molded tooth portion 9b of the molded product 8b has a spiral shape that is sufficiently satisfactory without defects such as underfilling and overburden, as shown in FIG. A molded product 8b of a bevel gear can be obtained.

Embodiments of the present invention will be described in detail below. First, a description of the rotary forging machine will be given. Rotary forging machines that perform forming by the cutting motion of an upper die have been known for a long time, and only the main parts thereof are shown in FIG. This first
The main shaft 1 shown in the figure and the upper mold indenter 2 connected to the main shaft are mounted so as to move at an angle θ by a drive mechanism (not shown), and the lower mold 4 is not shown. It can move forward and backward with respect to the upper mold indenter 2 by means of an elevating and lowering mechanism.

In the lower die 4, numeral 7 is a knockout whose upper end surface constitutes a part of the bottom surface of the die engraving space 5. The knockout 7 is raised after completion of molding and is provided so as to push out the molded product.

The engraving space 5 of the lower mold 4 is carved opposite the pressure surface 3 at the tip of the upper mold indenter 2, and a desired spiral tooth pattern is formed on the outer periphery of the bottom thereof, as shown in FIG. The toothed part 6 is formed in an annular shape.

Next, the process of forming the spiral bevel gear will be explained.

The material 8 to be formed, which has been cut in advance to a predetermined volume or preformed after cutting, is inserted into the die carving space 5 as shown on the left side of FIG. 1, and then the lower die is raised.

At this time, the main shaft 2 is rotated in accordance with the helical direction toward the outside in the radial direction of the tooth trace, and as a result, the blank 8 is molded to fill the molding space as shown in FIG. 9.

Note that the surface marked with 12 in FIG. 9 is the indenter contact surface that is in contact with the pressing surface 3 of the upper die indenter 2.

As described above, according to the present invention, the material to be formed is inserted between the upper mold indenter connected to the main shaft and the lower mold in which the toothed part is formed at the bottom of the mold engraving space opposite to the upper mold indenter. Then, since rotational forging is carried out by aligning the direction of rotation of the spindle with the radially outward helical direction of the tooth trace of the tooth profile, the spiral bevel can be formed without defects such as underfill or fog in the formed tooth part. Gears can be molded.

[Brief explanation of drawings]

Figure 1 is a sectional view of the main parts of a rotary forging machine. Figure 2 is an explanatory plan view of the die engraving space. Figure 3 is an explanatory diagram of a molded product molded by rotating the main shaft in the opposite direction to the direction of the tooth trace. FIG. 4 is an enlarged cross-sectional view taken along the line ■-■ in FIG. FIG. 5 is a reference diagram showing the external appearance at approximately the same position as FIG. 4, using a photograph. FIG. 6 is an explanatory diagram of a molded product molded with the main axis aligned with the twist direction of the tooth trace. Figure 7 is the pigeon-vu in Figure 6.
An enlarged sectional view showing the cross section. FIG. 8 is a reference diagram showing the external appearance at approximately the same position as FIG. 7, using a photograph. FIG. 9 is a sectional view of the spiral bevel gear after rotational molding. (Explanation of symbols) l... Main axis. 2... Upper die indenter. 3...Pressure surface. 4...Bottom mold. 5・・・・・・Mold engraving space. 6・・・・・・・・・
・Tooth mold part. 8 (8a, 8b)... Molded product. 9 (9a, 9b
)...Molded tooth part.

Claims (1)

[Claims] A material to be formed 8 is inserted between an upper mold indenter 2 connected to the main shaft 1 and a lower mold 4 in which a toothed part 6 is formed at the bottom of a mold engraving space 5 facing the upper mold indenter 2. A method for manufacturing a spiral bevel gear by a rotary forging method, characterized in that the rotational forging is performed by aligning the direction of one rotation of the main shaft with the radially outward helical direction of the tooth line of the tooth pattern portion 6.