Investigation on Billets and Tools Geometry in Cold Forging of the Straight Bevel Gear

Straight bevel gears are an essential component of mechanical transmissions; they are widely used in the automotive, aerospace, shipbuilding industries and are made by shaping methods such as metal forming, casting, or machining. To market products, with proper function and properties, at a low cost, this gear component is usually fabricated by precise cold forging (the billet is forged in a closed-die at room temperature). In cold forging, the geometry of the billet and the forming tool plays an important role. It determines the ability to fill the die cavity, creating a finished product profile that meets the required geometric parameters. In this study, by 3D numerical simulation, some geometric shapes of workpieces and tools were investigated to find the optimal parameters. The results obtained from the simulation method were determined that a cylindrical workpiece with a tapered end and a die bottom with a convex profile will increase material flow velocity, improving cavity filling, uniform distribution stress in the forming specimen, and forging products without defects. Experimentally also verified the simulation results, which were cold forging with optimized workpiece and tool geometry, the straight bevel gear part was fully shaped, ensuring geometrical accuracy. The result of this study is a suggestion to apply to the design of a cold forging die for similar features