Segmented Diffusion Welding for Complex Metal Part Accuracy
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Solution Overview
Problem
Current methods for manufacturing metal parts with complex shapes face challenges such as deformation, internal stresses, and surface quality issues, particularly in achieving dimensional accuracy and material quality comparable to forged materials, while also being cost-effective and efficient.
Innovation Solution
The method involves segmenting the metal part into easily producible pieces that are stacked and welded using diffusion or hot isostatic compression, with a negative mold made from materials that can be chemically dissolved or mechanically extracted, ensuring minimal deformation and high material quality by using materials with similar thermal expansion coefficients to the final part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If casting methods are used to produce complex-shaped parts, then the geometric complexity is achieved, but material quality deteriorates with heterogeneities and defects
Solution Approach 1:
The complex-shaped part is divided into multiple simple-shaped forged or machined pieces that are then stacked and joined together. Each piece maintains the high material quality of forged/machined components while the stacked assembly achieves the complex geometry that would be difficult or impossible to obtain through casting alone.
2Shape
If casting methods are used to produce complex-shaped parts, then the geometric complexity is achieved, but dimensional accuracy and surface finish deteriorate
Solution Approach 1:
The part is segmented into multiple precision-forged or machined components, each with controlled dimensional accuracy and surface finish. These precision pieces are then stacked and joined, preserving the high manufacturing precision in the final assembly while achieving complex geometry.
Solution Approach 2:
A negative mold is introduced as an intermediary tool during the stacking process. The negative mold receives the stacked pieces and defines the final external geometry through diffusion welding, allowing precise control of dimensional accuracy and surface finish without requiring complex casting operations.
3Shape
If fusion welding is used to join machined elements, then complex geometry is achieved, but dimensional accuracy and cost worsen due to weld inspection requirements
Solution Approach 1:
The mechanical fusion welding process is replaced with diffusion welding, which joins materials through atomic diffusion at the interface. This substitution eliminates the harmful thermal effects of fusion welding that cause distortion and dimensional inaccuracies, while still achieving strong joints in complex geometries.
Solution Approach 2:
The welding parameters are fundamentally changed from high-temperature fusion welding to lower-temperature diffusion welding. By controlling temperature, pressure, and time parameters in the diffusion process, the method achieves joint strength without the dimensional accuracy deterioration and inspection costs associated with fusion welding.
4Reliability
If Hot Isostatic Compression is used to densify powder, then material quality improves, but core deformation occurs during the process
Solution Approach 1:
Instead of using a single large core that deforms during HIC, the part is segmented into multiple smaller pieces that are stacked. These segmented pieces maintain their shape better during the densification process, and the negative mold compensates for any minor deformations to achieve the final precise geometry.
Solution Approach 2:
The negative mold serves as an intermediary that compensates for core deformation. During HIC, the flexible or adjustable negative mold can accommodate and correct shape changes in the powder or cores, ensuring the final part achieves the desired dimensional accuracy despite deformations occurring during densification.
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 allows for the production of complex metal parts with reduced deformation and internal stresses, achieving a surface quality comparable to forged materials and ensuring precise dimensional accuracy, while avoiding the limitations of traditional casting methods.
Implementation Method 1
diffusion welding, known as friction stir welding
Implementation Method 2
the sealed container is subjected to a hot isostatic compression cycle. This consists of a heat treatment under high gas pressure below the melting temperature of the materials used. Under the effect of the pressure, typically 500 to 2000 bar, and the temperature, typically 500 to 1500°C, the container deforms and transmits the pressure and heat to the noble alloy powder, which is then fully densified.
Implementation Method 3
The chemical dissolution technique consists of immersing the part in a chemical bath made up of acids which dissolves the core material and possibly the container, without attacking the noble material.
Implementation Method 4
since the core material is different from the constituent material of the part, internal stresses due to differential contraction develop during cooling
Data Source
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AI summary
The application relates to a process for manufacturing a complex-shaped metal part (1). Initially, the rough or desired shape of the final metal part is created by segmentation in several pieces to be stacked, the stack being fitted together without significant gaps with a stack of pieces which constitute the negative mold by segmentation, thus forming a dense assembly to which diffusion welding is applied.