Additive Holding Assembly Using Fluid Expansion for Fragile Part Blanks
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Solution Overview
Problem
Selective melting or selective sintering processes in powder bed additive manufacturing face challenges in maintaining part blanks, particularly those with low mechanical resistance, such as turbomachine blades, due to difficulties in holding and heating without generating undesirable mechanical stresses.
Innovation Solution
A method involving a holding assembly with a first holding part having an internal cavity containing a fluid, which expands to reduce the space between the part blank and the holding assembly, thereby facilitating easier holding and minimizing mechanical stresses. The internal cavity is hermetically closed, and the holding parts are deformable, allowing for differential expansion to match the shape of the part blank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the part blank is held firmly during heating, then the holding stability is improved, but mechanical stresses on the part blank increase
Solution Approach 1:
The invention changes the physical state of the fluid from liquid to gas through heating, causing expansion that increases the holding force. The parameter change in fluid volume and pressure directly improves holding stability while the distributed nature of the fluid pressure reduces localized mechanical stresses on the part blank
Solution Approach 2:
The invention uses a fluid (preferably gas) contained within the holding portion to create pneumatic pressure for holding the part blank. The fluid expansion upon heating generates distributed pressure throughout the cavity, providing stable holding while minimizing stress concentration points that would occur with rigid mechanical contact
2Ease of manufacture
If the holding portion is made deformable with internal cavity, then the ease of manufacture is improved, but the manufacturing precision is worsened
Solution Approach 1:
The holding portion is pre-manufactured with an internal cavity and fluid containment structure using additive manufacturing. The preliminary inclusion of the cavity and fluid system allows the holding portion to be manufactured as an integrated component, simplifying the manufacturing process while the subsequent heating-induced expansion provides the necessary shape adaptation
Solution Approach 2:
The invention uses parameter changes in the fluid (temperature, pressure, volume) to achieve shape adaptation of the holding portion. The deformable structure allows controlled parameter changes that enable the holding portion to conform to the part blank shape, resolving the conflict between ease of manufacture and manufacturing precision
3Temperature
If heating is applied to the holding assembly, then the fluid expansion is improved, but the mechanical stresses on the part blank increase
Solution Approach 1:
The invention uses pneumatic pressure from heated gas expansion to hold the part blank, distributing the holding force uniformly across the part surface. This pneumatic approach allows temperature increase for fluid expansion while avoiding the localized stress concentrations that would result from direct mechanical heating fixtures
Solution Approach 2:
The invention exploits parameter changes in the fluid (temperature to volume/pressure conversion) to achieve the holding function. The controlled heating causes predictable fluid expansion that increases holding force while the fluid's ability to distribute pressure evenly reduces mechanical stresses on the part blank
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 method effectively holds the part blank while reducing mechanical stresses, facilitates the removal of unfused powder, and enhances the control over the shape and mechanical resistance of the part, particularly for parts with thin walls or low mechanical resistance.
Implementation Method 1
heating the holding assembly and the workpiece blank to deform the first holding portion by fluid expansion in the internal cavity
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a method for holding a part blank (1) inside a holding assembly (20). The holding assembly (20) comprises a first holding portion (30). The first holding portion (30) comprises an internal cavity (31) containing a fluid. The part blank (1) and the first holding portion (30) are at least partially manufactured by additive manufacturing. The holding method includes heating the holding assembly (20) and the part blank (1) in order to deform the first holding portion (30) by expanding fluid in the internal cavity (31) and to reduce a gap (21) between the part blank (1) and the holding assembly (20) by expanding the first holding portion (30).