The design of forged gears must account for both transmission functionality and the specific material and structural requirements of the forging process to ensure reliability under load and during operation. Key design aspects include gear parameters, material selection, structural configuration, and machining allowances.
Gear Parameter Design
Gear design begins with determining geometric parameters such as the number of teeth, module, pressure angle, face width, and addendum height; these directly determine the gear ratio, meshing accuracy, and load-bearing capacity. For forged gears, considerations must also include forging blank allowances and compensation for post-heat-treatment deformation to ensure the final precision meets design specifications.
Material and Structural Design
Forged gears typically utilize alloy steels or carbon steels, such as 20CrMo or 42CrMo. Material selection must balance strength, toughness, wear resistance, and hardenability to withstand high loads, high rotational speeds, or impact conditions. Structural design should focus on tooth root fillets, face width distribution, and tip thickness to minimize stress concentrations and prevent root fatigue cracking, thereby extending the gear's service life.
Process and Machining Design
The design phase must also consider the impact of the forging process on the gear blank's geometry-such as the feasibility of die-forging the bore diameter, blank outer diameter, and tooth profile. Sufficient machining allowance must be provided to achieve the final dimensions and precision after heat treatment and finishing operations. Furthermore, the design must ensure the maintenance of coaxiality and tooth profile accuracy following heat treatment, preventing deformation or warping.