JP2873334B2 - Manufacturing method of wear-resistant gear - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a wear-resistant gear that has improved wear resistance as well as surface pressure strength and corrosion resistance.

(Prior Art) As a conventional wear-resistant gear, a gear whose surface is hardened by carburizing treatment or the like to improve wear resistance and strength resistance is known. Gear cutting process as shown in the manufacturing process diagram of FIG.
In 11 the gear base material of high carbon steel is gear-cut and carburized 12
To form a carburized layer on the surface of the base material,
The required surface grinding is performed to obtain a wear-resistant gear.

(Problems to be Solved by the Invention) As described above, conventional wear-resistant gears are subjected to surface hardening treatment by carburizing treatment to achieve wear resistance and strength resistance. However, conventional wear-resistant gears that are only carburized due to an increase in gear transmission torque have the disadvantage that the surface pressure strength of the tooth surface is insufficient, and they are liable to be damaged during use, such as pitting and scoring. Further, although the gear surface is hardened only by the carburizing treatment, the internal strength, particularly the strength of the tooth root portion is not sufficient, and there is a problem that the tooth portion is damaged when used in a high torque gear transmission portion.

An object of the present invention is to provide a method of manufacturing a wear-resistant gear that is excellent in surface pressure strength as well as wear resistance, improves the hardness inside a base material, and can also improve corrosion resistance.

(Means for Solving the Problems) A wear-resistant gear according to the present invention comprises a carburized gear base material in which Ti is deposited on the base material surface by chemical vapor deposition and C in the base material is diffused to form a TiC layer. On the surface of the base material.

(Examples) Next, the present invention will be described with reference to the drawings with respect to examples.

FIG. 1 is a partial cross-sectional view of a wear-resistant gear manufactured by a gear manufacturing method according to an embodiment of the present invention. A carburized layer (C content: 0.6 to 0.8%) 2 is formed on the surface of a gear base material 1 made of high carbon steel having a C content of 0.2% or more, and a carburized layer 2
The TiC layer 3 of 5 to 10 μm is formed on the surface of the substrate. In this case, C diffused in the carburized layer 2 reacts with Ti on the surface to generate a TiC layer by a method described later. T
iC is a material having a high hardness of Hv3000 (Vickers hardness) and suitable for abrasion resistance. As described above, the adhesion of the TiC layer is high due to the TiC generation reaction.

FIG. 2 (a) is a block diagram showing a manufacturing process of the wear-resistant gear according to the present invention. It is possible to form a carburized layer on the surface of the base material by performing gear cutting on the gear base material of high carbon steel in the gear cutting process 11, performing carburizing process 12, and then performing the required surface grinding in the grinding process 13. It is the same as the conventional case of FIG.
In the present invention, thereafter, a TiC treatment 14 by chemical vapor deposition (CVD) is further performed (about 1000 ° C.). In the TiC treatment 14, the CVD
Ti is precipitated on the surface of the carburized layer of the base material, and C in the carburized layer is diffused and reacted with Ti on the surface to form the TiC layer 3 of 5 to 10 μm as described in FIG. The surface roughness at this time is about Rmax = 3 to 5 μm. This ensures the abrasion resistance of the surface layer, but in the TiC treatment 14, C moves and diffuses at the boundary of the TiC layer, so that a portion with a small amount of C is formed locally, for example, at the root of the tooth. A layer may appear and the strength of this part may be impaired. In addition, the strength of the boundary is weakened, such as peeling caused by the compressive residual stress of the TiC layer and the tensile residual stress of the boundary. Therefore, in this embodiment, Ti
After the C treatment 14, a QT treatment 15, ie, a quenching and tempering treatment, is performed to increase the hardness inside the base material, and to improve the wear resistance of the tooth surface and the strength of the root portion. In some cases, the last QT process 15 may be omitted. Also QT processing
After 15, grinding process 17 with a diamond whetstone is performed, and Rm
When ax = 0.6 μ, the wear resistance increases about twice. Further, as in the embodiment shown in FIG. 2 (b), a grinding process 13a using a diamond grindstone is performed before the TiC process 14, and a diamond grinding process 17 is performed again after the QT process 15 to obtain an Rm.
When ax = 0.4 μ, the wear resistance is further improved by about 20%.

FIG. 3 is a block diagram showing a manufacturing process according to another embodiment of the present invention. In this embodiment, a tooth root coating 16 is added between the carburizing treatment 12 and the TiC treatment 14, and the surface of the tooth root 5 of the base material 1 is coated with a heat-resistant material as shown by reference numeral 4 in FIG. Then, diffusion and movement of C in this portion are prevented in the subsequent TiC processing, so that the QT processing 15 can be performed more effectively. It is confirmed that the hardness is improved three times or more by the QT treatment.

(Effects of the Invention) As described above, according to the present invention, in addition to the conventional carburizing treatment, a TiC treatment by CVD is performed, and Ti is diffused by utilizing C diffusion.
And the TiC layer is formed on the surface, thereby increasing the surface pressure strength, and has an effect of easily obtaining a gear having increased wear resistance, strength resistance and corrosion resistance.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a wear-resistant gear manufactured by a gear manufacturing method according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) show a manufacturing process of the wear-resistant gear according to the present invention. FIG. 3 is a block diagram showing a manufacturing process of another embodiment of the present invention, and FIG. 4 is a partial cross-sectional view showing a coated state of a gear base material in the manufacturing process shown in FIG. FIG. 5 is a block diagram showing a manufacturing process of a conventional wear-resistant gear. 1 ... gear base material, 2 ... carburized layer, 3 ... TiC layer, 4 ...
Coating layer, 11 ... gear cutting process, 12 ... carburizing process, 13
…… grinding, 14… TiC, 15… QT, 16 ……
Tooth base coating treatment.

Claims (2)

(57) [Claims] 1. A carburized gear base material is made of Ti by chemical vapor deposition.
Characterized in that Ti is deposited on the surface of the base material and C is diffused in the base material to form a TiC layer on the surface of the base material. 2. The method for manufacturing a wear-resistant gear according to claim 1, wherein a quenching and tempering treatment is performed in addition to the TiC layer formation treatment by the chemical vapor deposition method.