Dual-Modulus Sizing Die for Sintered Body Densification
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Solution Overview
Problem
Conventional surface densification methods for sintered bodies using sizing dies face issues such as die abrasion and breakage due to high pressure, and the formation of burrs, especially when the Young's modulus of the die and sintered body are similar, leading to increased costs and complexity.
Innovation Solution
A sizing die with a dual-material structure, where the upper portions have higher Young's moduli for ironing and the lower portions have lower moduli for compression, preventing die abrasion and burr formation by using cemented carbides and ferrous tool steels, respectively, and optimizing the ironing margin and approach angle to minimize contact and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high pressure is applied when performing sizing, then surface densification is improved, but the die breaks easily
Solution Approach 1:
The die is divided into two distinct portions: an upper portion made of high Young's modulus material (cemented carbide) for ironing and sizing, and a lower portion made of low Young's modulus material (ferrous tool steel) for compression. This segmentation allows each portion to perform its specific function optimally without the other compromising die reliability.
Solution Approach 2:
Different portions of the die are assigned different material properties tailored to their specific functions. The upper portion has high Young's modulus (≥300 GPa) to prevent burr formation during ironing, while the lower portion has lower Young's modulus (<300 GPa) to reduce stress concentration and prevent die breakage during compression.
2Ease of manufacture
If the Young's modulus of the die is similar to the sintered body, then compression is easier, but surface densification becomes difficult
Solution Approach 1:
The die's upper portion is specifically designed with high Young's modulus material to provide the necessary stiffness for effective surface densification and burr prevention during ironing, while the lower portion uses lower modulus material to facilitate easier compression of the sintered body.
3Ease of operation
If a large ironing margin is left, then sizing is easier, but significant burrs are formed on the sintered body
Solution Approach 1:
The approach angle of the upper taper portion is precisely controlled to be less than 10° (preferably 5-8°). This parameter optimization allows the die to effectively prevent burr formation while maintaining ease of sizing operation, eliminating the need for excessive ironing margin.
4Manufacturing precision
If stepwise portions and protrusions are installed in the die, then ironing is improved, but the die becomes more susceptible to abrasion
Solution Approach 1:
The die is constructed as a composite structure combining cemented carbide (upper portion) and ferrous tool steel (lower portion). This composite design provides both the hardness needed for effective ironing and the toughness required to resist abrasion and prevent die breakage.
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
The method effectively prevents die abrasion and burr formation while ensuring sufficient surface densification, reducing costs by allowing for easier replacement of worn die parts and maintaining the integrity of the sintered body.
Implementation Method 1
the sintered body and the die member will mutually undergo elastic deformation at the upper taper portion
Implementation Method 2
The sintered body is ironed by the upper taper portion... the sintered body will be plastically deformed
Implementation Method 3
the sintered body and the die member will mutually undergo elastic deformation at the lower taper portion
Data Source
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AI summary
The invention of the present application is a die for compressing and sizing a sintered body (1) at straight portions (11, 21). Upper taper portions (15, 25) are provided on a die upper portion (13) and a core rod upper portion (23), and the straight portions (11, 21) are provided at a die lower portion (14) and a core rod lower portion (24). The materials of the die upper portion (13) and the core rod upper portion (23) have Young's moduluses higher than those of the materials of the die lower portion (14) and the core rod lower portion (24). The die upper portion (13) and the core rod upper portion (23) are made of materials having Young's moduluses that are at least 50 GPa higher than that of the sintered body (1). Thus, the sintered body (1) can be densified with a smaller ironing margin (s). Further, since the sintered body (1) is ironed without being compressed, by the taper portions of the die upper portion (13) and core rod upper portion (23) that are made of materials having high Young's moduluses, the die can be prevented from breaking, and being abraded due to ironing.