(1) Carburized motorcycle sprockets require a carburized layer on the tooth surface. When the "carburized-warm extrusion" process is used, the distribution of the carburized layer is closely related to the deformation method of gear forming. For the tangential split extrusion process, the carburized layer at the gear teeth is redistributed from the carburized layer on the surface of the cylindrical blank. In the "carburizing-warm extrusion" process of gears, the deformation time is shorter, and the diffusion of the carburized layer can be ignored. Obviously, after the cylinder becomes a gear, the surface area is greatly increased, and the thickness of the carburized layer changes greatly. When the carburized layer is tangentially compressed during the forming process, the thickness of the carburized layer increases, otherwise, the thickness decreases; and the carburized layer The thickness change depends on the amount of tangential deformation. Therefore, the thickness distribution of the carburized layer can be controlled by controlling the tangential deformation of the carburized layer during the warm extrusion of the gear. (2) On the basis of understanding the forming process of motorcycle sprocket teeth, further discussion on the change from the carburized layer of the cylinder to the carburized layer of the gear when forming the gear part: the cylinder pressed by the female teeth The surface carburized layer becomes the carburized layer of the gear root part. The change must be from the cylinder surface to the tooth root surface, and the earlier it participates in the deformation, the greater the extension rate, the thinner the carburized layer; on the contrary, due to the die extrusion When the pressure makes the concave part of the pressure part become the root of the tooth, the metal of the pressure part of the die between the metal and the radial part of the metal becomes the tooth crest part, this part of the metal is compressed by the two adjacent die split teeth at the top, then The thickness of the carburized layer increases; when the deformation increases, if the contact with the female mold is subjected to sufficient friction of the female mold, the thickness of the carburized layer may be reduced when stretching occurs.