Helical Gear Wheel Heat Treatment With Interim Positioning Geometry
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Solution Overview
Problem
Existing manufacturing processes for two-row, helically toothed gears, such as those used in aircraft engines, face challenges in achieving heat-treated workpieces with minimal distortion and precise microstructure while maintaining narrow tolerances, often requiring multiple machining steps and realignments between carburizing and quench press hardening.
Innovation Solution
A method that combines carburizing and press hardening processes, using interim geometries as carburization protection to center and position the workpiece during quench press hardening, allowing for reduced machining steps and realignments by maintaining the carburization protection until after press hardening, followed by removal of these geometries to achieve the final geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the workpiece is machined between carburizing and quench press hardening to achieve precise geometry, then manufacturing precision is improved, but the number of machining steps and realignments increases
Solution Approach 1:
Interim geometries are created during the initial turning process before carburizing, serving as positioning features for subsequent press hardening. This preliminary action eliminates the need for additional machining steps between carburizing and quench press hardening, reducing the number of realignments while maintaining manufacturing precision
Solution Approach 2:
The positioning features (interim geometries) are integrated into the gear body itself rather than being separate fixtures. This merging allows the workpiece to self-position during press hardening, eliminating the need for separate alignment operations and reducing manufacturing complexity
2Reliability
If the workpiece is removed from the carburizing container and transported to the quench press hardening, then the processes are separated for quality control, but handling time and distortion risk increase
Solution Approach 1:
The interim geometries act as an intermediary mechanism that enables direct transfer from carburizing to press hardening. These geometries serve as both carburization protection and positioning features, allowing the workpiece to move directly between processes without additional handling or realignment operations
Solution Approach 2:
The interim geometries remain intact throughout the carburizing and press hardening processes, providing continuous positioning capability. This allows for seamless transition between operations without interruption or repositioning, minimizing handling time while maintaining quality control
3Manufacturing precision
If the workpiece is clamped multiple times for different machining operations, then manufacturing precision is maintained, but the number of clamping operations increases distortion
Solution Approach 1:
Interim geometries are pre-formed during the initial turning process to serve as permanent positioning features. This preliminary action eliminates the need for repeated clamping and realignment operations, reducing cumulative distortion while maintaining tolerance requirements
Solution Approach 2:
The workpiece uses its own interim geometries as positioning features during press hardening, rather than requiring external fixtures or multiple clamping operations. This self-service approach minimizes external interference and reduces distortion from repeated handling
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the manufacturing process, reduces distortion, and improves machining quality by minimizing the number of clamping and handling processes, maintaining precise tolerances and optimizing the microstructure of the gear wheel.
Implementation Method 1
the workpiece is heated and carbon diffuses into the workpiece to form a surface layer
Implementation Method 2
the workpiece is subjected to a press hardening treatment, during which the workpiece is clamped and quenched in the clamped state
Data Source
Figure 1
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AI summary
The invention relates to a method for manufacturing heat-treated workpieces in which, during a carburizing process step, the workpiece is heated and carbon diffuses into the workpiece, forming a surface layer. The workpiece is then subjected to a press hardening treatment, during which it is clamped and quenched in a clamped state. The carburizing process encompasses intermediate geometries of the workpiece, which act as absorption zones. These intermediate geometries are subsequently removed during machining steps. The press hardening treatment is carried out after the carburizing of the workpiece and also before the removal of the intermediate geometries. The invention further relates to gears manufactured according to this method.