This development case study highlights the formation of a bevel gear using cold forging, where the serration portion was also formed in a single-shot process.

Product Name	Bevel Gear
Application	Automotive Parts
Manufacturing Method	Cold Forging
Forming Load	650tonf
Development Period	3ヶ月

Development Background and Challenges

Traditionally, bevel gears were manufactured by forging the outer teeth and then machining the internal serrations (splines). Because this method required two separate processes—forging and machining—the high number of steps hindered productivity improvements. Furthermore, since the inner and outer geometries were processed in separate stages, ensuring the coaxial alignment between the outer teeth and the internal serrations required significant man-hours, posing another major challenge.

Achieving Superior Concentricity with Ease via Single-Shot Simultaneous Forming

To solve these issues, we developed a single-shot simultaneous forming process utilizing a multi-axis double-action press.
In this new method, the outer bevel gear teeth and the internal serrations are formed simultaneously using the same die and the same process. By forming both geometries at once, deviations in coaxiality between the outer teeth and inner serrations are easily kept within specifications during mass production, minimizing the required management man-hours.
To achieve this complex simultaneous forming, it is essential to determine the optimal motion and timing to control the material flow during the process. We have established and accumulated sophisticated forming know-how through extensive past development achievements and meticulous trial-and-error using CAE analysis.
Additionally, the single-shot process completely eliminates the need for machining the internal serrations, leading to a significant boost in productivity.

Development System for Achieving High-Precision Bevel Gears

Forming high-precision bevel gears requires advanced “tooth profile compensation technology” to accurately predict and back-calculate the die design that account for die deformation under high forming loads and “heat treatment dimensional change.” Furthermore, our ability to integrate CAE visualization of the filling process and empirical evaluation using gear-meshing testers all in-house is a unique strength of Yamanaka Eng, thanks to our proprietary know-how and facilities. This thorough verification system is the key to achieving the targeted quality in the shortest possible time.

Integrated Development System and Reliable Quality Assurance to Meet Sophisticated Demands

Our strength lies in an integrated development system that merges state-of-the-art equipment, such as multi-axis double-action presses, with extensive development experience, forming know-how, and advanced CAE analysis.
In particular, our expertise in complex single-shot simultaneous forming is backed by advanced CAE technology, allowing us to identify optimal forming conditions in a short period and drastically reduce trial-and-error. Furthermore, our ability to provide high-precision geometries through proprietary tooth compensation and verify part accuracy using in-house gear-meshing testers ensures the highest quality requested by our customers. This is what sets our responsiveness to customer requirements apart.

If you are considering forging for any parts aimed at weight reduction, increased strength, or higher precision, please contact us. We offer high-level solutions to solve your challenges and provide powerful support for your product commercialization.