Steering Rack Tooth Cold Forming for Dimensional Accuracy

The patent applies preliminary action by cutting the teeth to a preliminary shape with adequate tolerances before final forming. The cutting process creates a pre-formed structure that is then refined through cold forming in a die, eliminating the need for high-precision machining while achieving tight dimensional tolerances. This two-stage approach (cutting then forming) resolves the contradiction by performing preliminary shaping that accommodates subsequent forming operations.

The patent replaces thermal processing (warm/hot forming) with a mechanical cold forming process. By using a die and press to cold-form the teeth after cutting, the process eliminates heat treat distortion while maintaining manufacturing feasibility. The mechanical cold forming system substitutes for the thermal field, resolving the contradiction between precision and ease of manufacture.

The patent changes the temperature parameter from warm/hot conditions to ambient (cold) conditions during the final forming operation. This parameter change eliminates thermal gradients and associated residual stresses while still achieving the desired tooth profile through cold plastic deformation in the die. The cold forming process maintains shape accuracy without introducing thermal stress.

The patent converts the potential harm of cold forming (which can induce stress) into a benefit by using a controlled die-forming process that distributes stress uniformly. The die cavity design ensures that the cold forming operation produces the desired shape while minimizing residual stresses through proper tooling design and forming parameters.

The patent merges the cutting and final shaping operations into an integrated two-stage process where cutting creates the preliminary form and cold forming in the die completes the shaping in a single manufacturing flow. This merged process eliminates the need for separate heat treatment and multiple machining operations, achieving high precision while reducing total manufacturing time.

The cutting operation performs preliminary action by creating a pre-formed structure with adequate tolerances that is ready for final cold forming. This preliminary shaping eliminates the need for multiple corrective machining operations, as the cold forming step directly achieves the final precise dimensions in one operation, reducing overall manufacturing time.