CFC Workpiece Carrier with Channel Depressions for Uniform Gas Quenching
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Solution Overview
Problem
High-temperature processes, such as low-pressure carburizing followed by high-pressure gas quenching, often result in inadequate gas contact with workpiece surfaces due to shadowing, leading to incomplete hardening and warping, especially when using metallic workpiece carriers, which are also prone to dimensional changes and brittleness.
Innovation Solution
A workpiece carrier with a point-shaped support surface featuring channel-shaped depressions that direct process gases evenly across the workpiece surface, reducing shadowing and allowing for uniform cooling, while maintaining stability and automatability through a grid-like structure with alternating narrow support areas and recesses, potentially arranged in a checkerboard pattern with truncated pyramids or pyramids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat workpiece support surface is used on the workpiece carrier, then the workpiece carrier structure is simple, but the process gas cannot reach the workpiece surface evenly, leading to shadowing and insufficient hardening
Solution Approach 1:
The flat support surface is segmented into multiple point-shaped support areas arranged in a grid pattern, with channel-shaped depressions between them. This segmentation allows process gas to flow through the depressions and reach all workpiece surfaces evenly, eliminating shadowing while maintaining structural simplicity
Solution Approach 2:
The workpiece carrier support surface is designed with a porous-like structure consisting of point-shaped support areas separated by channel-shaped depressions. This allows gas permeation through the carrier surface, ensuring 100% gas contact with the workpiece surface for uniform carburizing
2Manufacturing precision
If support aids with narrow edges are placed on the workpiece carrier to enable gas contact, then the process gas can reach the workpiece surface, but the support becomes unstable and prevents automation
Solution Approach 1:
Instead of using narrow-edged support aids, the support surface is segmented into multiple point-shaped support areas formed directly on the carrier. This provides stable point contact for workpiece positioning while maintaining gas flow channels between the points, enabling both stability and automation
Solution Approach 2:
The channel-shaped depressions act as intermediaries that guide process gas from the carrier interior to the workpiece surface. This intermediary structure ensures gas reaches all surfaces without requiring external support aids that would interfere with automation
3Strength
If metallic workpiece carriers are used, then the carriers have high strength, but they undergo dimensional changes and embrittlement at high temperatures
Solution Approach 1:
The workpiece carrier uses a composite structure combining CFC (carbon fiber reinforced carbon) material with a specific geometric design of point-shaped supports and channel depressions. This composite approach provides both high-temperature dimensional stability and the required mechanical strength
4Manufacturing precision
If a grid-like structure with many parts is used to enable gas contact, then the process gas can reach the workpiece surface, but the manufacturing process becomes complex and time-consuming
Solution Approach 1:
The support function and gas flow channel function are merged into a single integrated structure. The point-shaped support areas and channel-shaped depressions are formed as one unified component, simplifying manufacturing while achieving both stable workpiece support and uniform gas distribution
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
Ensures 100% gas contact with the workpiece surface, achieving surface hardness of 60 to 64 HRC, significantly higher than prior art, with improved uniformity and stability, and enables rapid and uniform cooling during gas quenching.
Implementation Method 1
the process gas can diffuse into all areas of the workpiece surface, preventing any shadowing of the workpiece surface
Implementation Method 2
enables rapid and uniform cooling during the subsequent high-pressure gas quenching
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Workpiece carrier (1) made of carbon fiber reinforced carbon with a flat workpiece support surface, wherein the workpiece support surface is traversed by channels for a process gas formed as trough-shaped depressions (5).