JPH0159060B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a helical gear by rolling.

Conventionally, in order to roll a gear, as shown in FIGS. 1a and 1b, a gear machining section with a width b approximately equal to the face width shown in the design drawing is created between a pair of opposing gear tools 1 and 2. 3a is rotatably supported, and the gear tools 1 and 2, which are rotatably driven, are pressed against the gear material 3 by hydraulic mechanisms 4 and 5 or a cam mechanism, and a tooth shape is formed on the surface of the gear material 3. I was trying to create.

Therefore, in the rolling process, each gear tool 1,
2 starts to come into contact with the gear material 3, the teeth of each gear tool 1, 2 gradually bite into the surface of the gear material 3, and the teeth are subjected to a large compressive force and bending moment. At this time, the gear tool 1,
The pushing force that should be maintained at 2 is related to the amount of metal volume that the tool teeth can bite into and displace.
As shown in FIG. 2, the pushing force changes cyclically for each tooth pitch of each gear tool 1, 2. This variation mode is caused by the fact that when the number of teeth of the gear to be rolled is even, the biting state of the gear tools 1 and 2 into the gear material 3 becomes symmetrical with respect to the center of the material 3.
When the number of teeth of the gear to be rolled is odd, as shown in FIG. 3, both the left and right gear tools 1 and 2 pulsate alternately without synchronization. In any case, this pulsation phenomenon in the pushing force adversely affects the rolling stroke of the gear tool as well as the tool shaft, and deteriorates the accuracy of the manufactured gear. That is, as shown in FIG. 4, it is not only possible to obtain a tooth trace curve B with respect to the desired correct tooth trace line A, but also to create depressions 3b and 3c on both surfaces of the teeth as shown in FIG. Become. As is well known, the above-mentioned pulsation phenomenon that causes these problems, that is, the fluctuation of the pressing force of each gear tool 1, 2 against the gear material 3, greatly increases the meshing ratio between the gear tool 1, 2 and the gear to be rolled. However, it can be reduced by making the simultaneous contact length constant during their engagement. In this respect, helical gears are said to be more advantageous than spur gears because they can increase the meshing ratio, especially the overlap meshing ratio.
The simultaneous contact length can also be made constant by setting the overlapping engagement ratio to an integer. To do this, as is clear from the formula below, the face width b of the helical gear to be manufactured may be set to be an integral multiple of the axial pitch t (see FIG. 7).

ε _sp = b/t ε _sp : Overlap contact ratio b : Helical gear face width t : Axial pitch However, conventional rolled helical gears do not match the design from the time they are made of raw material. Because it is set to the tooth width, the overlapping meshing ratio is not necessarily an integer,
It has been difficult to stably obtain gears with highly accurate tooth traces and tooth profiles.

In view of the above-mentioned points, the present invention provides a method for manufacturing helical gears that improves the accuracy of the manufacturing process.The present invention provides a manufacturing method for manufacturing helical gears with improved precision, in which the overlapping meshing ratio is an integer value and the required teeth are formed by rolling the gear material. The feature is that after creating a helical gear larger than the width, the end portions are removed to create the desired tooth width.

The invention will now be described with reference to illustrated embodiments.
In FIG. 6, reference numeral 6 denotes a gear material, and the axial dimension b ₁ of the gear processed portion 6 a is larger than the target tooth width dimension b ₂ or b ₃ . This gear material 6 is rolled in the same manner as described above to create the helical gear ₇ shown in FIG. It is set to be an integral multiple of the axial pitch t of the helical gear 7. Therefore, the variation in the pushing force of the gear tool (not shown) against the gear material 6 is expressed as follows:
It can be reduced more stably and effectively than before. Then, the end 7a or both ends 7b of the helical gear 7 created as described above is
The helical gear 8 with the desired face width b ₂ or b ₃ is removed by removing the gear shaft portion 8a or 9a shown in the figure.
Or form 9.

According to the method for manufacturing a helical gear of the present invention, which involves the above-described process, a stable and effective tendency to reduce the fluctuation of the pushing force can be obtained, and the accuracy of the tooth profile and tooth trace can be significantly improved compared to the conventional method. To obtain a helical gear with an extremely good finish by not only improving the gear width but also simultaneously removing incomplete teeth and burrs at the tooth end caused by rolling when forming the above-mentioned face width b ₂ or b ₃ . Can be done.

Although the helical gears in the above embodiments are those in which the helical gear manufacturing method of the present invention is applied to a double push hydraulic rolling machine, the present invention is not limited to this, and for example, a segment die, etc. internal gear type tool,
Alternatively, it can also be applied when using a rack-shaped tool.

As described above, according to the method for manufacturing a helical gear of the present invention, it is possible to stably and effectively reduce fluctuations in the pushing force of the rolling gear tool against the gear material. The tooth profile and tooth trace accuracy can be significantly improved.

[Brief explanation of drawings]

Figures 1a and b are plan and front views showing the conventional gear manufacturing method by rolling, Figure 2 is a graph showing the pulsation phenomenon of tool pushing force in the manufacturing method of Figure 1, and Figure 3 is Fig. 1 is an explanatory diagram showing the rolling mode when the number of teeth of the rolled gear is an odd number in the manufacturing method, and Figs. 4 and 5 are tooth trace curve diagrams and tooth profiles in the manufacturing method of Fig. 1. The figures shown, FIGS. 6 to 8, are all explanatory diagrams showing the process of forming a helical gear by the manufacturing method of the present invention. 1, 2... Gear tool, 3, 6... Gear material,
4, 5...Hydraulic mechanism, 7, 8, 9...Helical gear.

Claims (1)

[Claims] 1. After rolling the gear material to create a helical gear with an integer overlap mesh ratio and larger than the required face width, the ends are removed to create the required face width. Features: Manufacturing method for helical gears.