Rolling Contact Member Manufacturing via Selective Hot Forging Cutting
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Solution Overview
Problem
Conventional processes for manufacturing rolling contact members and bearings face increased manufacturing costs due to extensive cutting and yield reduction, while also failing to adequately address issues related to decarburized layers and scale formation, which affect durability and hardness.
Innovation Solution
A process involving hot forging, selective cutting to remove scale and decarburized layers, followed by cold forging, and subsequent minimal cutting to avoid irregularities, allowing for reduced manufacturing costs and improved durability by eliminating decarburized layers and scale-related problems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extensive cutting is performed after hot forging and annealing to remove scale and decarburized layers, then durability and hardness are improved, but manufacturing costs increase and material yield decreases
Solution Approach 1:
The patent applies preliminary action by performing selective cutting immediately after hot forging while the workpiece is still hot and more ductile. This timing allows for easier removal of scale and decarburized layers with less material loss and lower cutting forces, thereby improving durability while reducing manufacturing costs and increasing material yield.
Solution Approach 2:
The patent applies local quality by performing selective cutting only on specific surfaces where scale and decarburized layers form (typically outer surfaces), rather than removing material from the entire workpiece. This targeted approach removes harmful layers to improve durability while minimizing material waste and maintaining high yield.
2Reliability
If extensive cutting is performed after hot forging and annealing to remove scale and decarburized layers, then durability and hardness are improved, but manufacturing productivity decreases
Solution Approach 1:
The patent performs selective cutting immediately after hot forging while the material is still hot and more ductile, which reduces cutting forces and tool wear. This preliminary action at an optimal time point streamlines the manufacturing process and improves productivity while ensuring durability through proper removal of defective layers.
Solution Approach 2:
By applying selective cutting only to specific surfaces where scale and decarburized layers are present rather than performing comprehensive machining, the patent minimizes processing time and maximizes productivity while still achieving the durability improvement needed for reliable performance.
3Ease of manufacture
If minimal cutting is performed after hot forging to reduce manufacturing costs, then manufacturing cost and material yield improve, but decarburized layers and scale remain causing durability issues
Solution Approach 1:
The patent performs selective cutting immediately after hot forging as a preliminary action to remove scale and decarburized layers before subsequent processing steps. This timing is critical because the material is still hot and more ductile, allowing for easier removal of defective layers with minimal cutting, thereby improving durability while maintaining cost-effectiveness.
Solution Approach 2:
The patent applies local quality by performing selective cutting only on surfaces where scale and decarburized layers form, rather than removing material from the entire workpiece. This targeted approach ensures durability is improved by eliminating defective layers while minimizing material waste and maintaining manufacturing cost-effectiveness.
4Ease of manufacture
If hot forging is performed in air, then the process is simple and cost-effective, but scale and decarburized layers form on the surface
Solution Approach 1:
The patent applies the taking out principle by performing selective cutting to remove the harmful scale and decarburized layers that form during hot forging in air. Rather than changing the simple and cost-effective atmospheric hot forging process, the patent extracts the harmful surface layers through targeted cutting, maintaining process simplicity while eliminating the harmful effects of scale formation.
Solution Approach 2:
The patent converts the harm of scale and decarburized layer formation during atmospheric hot forging into a benefit by using selective cutting to precisely remove these layers. The hot forging process in air remains simple and cost-effective, and the resulting scale and decarburized layers serve as clear indicators of where cutting is needed, transforming a harmful byproduct into a useful guide for selective material removal.
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 reduces manufacturing costs by minimizing cutting regions after hot forging and annealing, while ensuring sufficient hardness and durability by removing decarburized layers and scale issues, thus enhancing the quality and cost-effectiveness of rolling contact members and bearings.
Implementation Method 1
a hot-forging step of hot-forging the steel member prepared in the steel member preparation step so that a first forged member is prepared
Implementation Method 2
a cutting step of cutting the first forged member prepared in the hot-forging step so that a part of the first forged member is removed
Implementation Method 3
a cold-forging step of cold-forging the first forged member cut in the cutting step so that a second forged member is prepared
Data Source
AI summary
A process for manufacturing a rolling contact member comprises preparing a steel member consisting of a steel containing 0.7 mass % or more of carbon; performing hot forging of the steel member prepared in the steel member preparation step to thereby obtain a blank ring as the first forged member; performing turning of the blank ring obtained in the hot forging step to thereby remove part of the blank ring; and performing cold forging of the blank ring wrought in the first turning step to thereby obtain a stepped ring. In the steps subsequent to the cold forging step, on the stepped ring, the area wrought in the first turning step is not subjected to cutting.