Engine Piston Diffusion Brazing for Flash-Free Cooling Galleries
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Solution Overview
Problem
Existing methods for manufacturing vehicle engine pistons with cooling galleries, such as friction welding and brazing, face challenges like flashing and reduced productivity due to complex processes and inefficiencies in forming and bonding the piston parts.
Innovation Solution
A method involving a locking part with specific geometries and a diffusion brazing process in a partially open heating zone, where the piston assembly is preheated and then brazed using a nickel-based alloy, forming a diffusion layer within the cooling gallery to improve assembly and reduce interference between piston parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If friction welding is used to join upper and lower piston parts, then the piston parts can be bonded together, but flashing is formed and remains in the cooling gallery, disturbing fluid flow
Solution Approach 1:
The harmful flashing is extracted and removed from the cooling gallery through post-welding machining operations. The patent specifically mentions that the cooling gallery is machined after welding to remove any flashing that may have formed during the friction welding process, ensuring clean fluid flow paths.
Solution Approach 2:
The patent changes the welding parameters and sequence by performing welding first and then machining the cooling gallery. This parameter change in process sequencing allows the cooling gallery to be cleaned of flashing after the welding operation is complete, resolving the contradiction between achieving strong bonds and avoiding flashing contamination.
2Strength
If brazing bonding is used to join upper and lower piston parts in a sealed chamber, then the piston parts can be bonded together, but heating and cooling are performed in a sealed chamber, degrading productivity
Solution Approach 1:
The patent extracts the productivity constraint by removing the requirement for a sealed chamber during brazing. By performing diffusion brazing in an open environment rather than a sealed chamber, the heating and cooling cycles can be performed more rapidly without the constraints of maintaining a sealed atmosphere, thereby improving manufacturing efficiency while still achieving strong bonds.
Solution Approach 2:
The patent substitutes the traditional brazing method requiring a sealed chamber with a diffusion brazing process that can be performed in an open environment. This replacement eliminates the need for complex sealed chamber equipment and associated heating/cooling cycles, significantly improving productivity while maintaining bonding strength through controlled diffusion of the bonding material.
3Shape
If upper and lower piston parts are separately manufactured and welded, then the cooling gallery can be formed, but the process complexity increases and productivity decreases
Solution Approach 1:
The patent merges the cooling gallery formation process with the welding process by performing diffusion brazing. The cooling gallery is formed as an integral part of the joint between upper and lower piston parts through the diffusion brazing process itself, eliminating the need for separate cooling gallery formation operations and reducing overall process complexity.
Solution Approach 2:
The patent applies preliminary action by pre-forming the cooling gallery structure in the piston parts before the diffusion brazing operation. The cooling gallery passages are prepared in advance during part manufacturing, so that when diffusion brazing is performed, the cooling gallery is already formed and simply needs to be cleaned of any flashing, rather than requiring complex post-welding formation operations.
4Strength
If traditional welding methods are used to join piston parts, then the parts can be bonded, but the heat affected zone may cause distortion and affect dimensional precision
Solution Approach 1:
The patent changes the thermal parameters of the welding process by using diffusion brazing instead of traditional fusion welding. This parameter change results in lower peak temperatures and more controlled heat input, which minimizes thermal distortion and maintains dimensional precision while still achieving strong bonds through diffusion of the bonding material.
Solution Approach 2:
The patent introduces a bonding material as an intermediary between the upper and lower piston parts during diffusion brazing. This intermediary material facilitates the bonding process at lower temperatures compared to direct fusion welding, reducing the heat affected zone and minimizing thermal distortion, while still achieving strong metallurgical bonds through diffusion.
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 enhances productivity by allowing for faster and more cost-effective manufacturing of vehicle engine pistons with improved heat conductivity and corrosion resistance in the cooling gallery, while avoiding flashing and maintaining precise assembly alignment.
Implementation Method 1
a piston diffusion brazing step of diffusion brazing the first piston part, the bonding member and the second piston part under an open atmosphere by heating the formed piston assembly
Implementation Method 2
diffusion brazing the first piston part, the bonding member and the second piston part under an open atmosphere by heating the formed piston assembly
Implementation Method 3
a piston diffusion brazing step of diffusion brazing the first piston part, the bonding member and the second piston part under an open atmosphere by heating the formed piston assembly
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
There is provided a method for manufacturing a piston for a vehicle engine, including: a piston assembling step of forming a piston assembly by assembling a first piston part, a bonding member and a second piston part, wherein the first piston part has two or more bonding surfaces separated from each other and extended in a circumferential direction, and the second piston part has two or more bonding surfaces separated from each other and extended in the circumferential direction; a piston diffusion brazing step of diffusion brazing the first piston part, the bonding member and the second piston part under an open atmosphere by heating the formed piston assembly; and a piston cooling step of cooling a piston unit formed by diffusion brazing the first piston part, the bonding member and the second piston part. The piston assembly includes a locking part for maintaining a position at which the first and second piston parts are assembled, and the method further includes a locking part removing step of removing the locking part from the cooled piston unit.