Gradient Coil Assembly Cold Pressure Welding Aluminum Copper
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Solution Overview
Problem
The challenge in manufacturing aluminum wire gradient coils for MRI systems lies in the oxidation of aluminum wire when attempting to weld it with copper wire using flux, which hinders large-scale production and results in quality defects.
Innovation Solution
The use of cold pressure welding to connect aluminum wire bodies with copper wire ends, allowing for the formation of gradient coils with concentric main and shield coil sets, thereby avoiding oxidation issues and facilitating mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If aluminum wire is used to reduce cost and weight, then manufacturing cost and weight are reduced, but oxidation occurs during welding with copper wire
Solution Approach 1:
The gradient coil is divided into three separate layers (first layer with first gradient coil, second layer with second gradient coil, third layer with third gradient coil), allowing each layer to be manufactured and welded independently. This segmentation enables the use of aluminum wire in each layer without compromising overall welding quality, as each layer can be processed separately with controlled oxidation prevention measures.
Solution Approach 2:
The gradient coil employs a composite structure combining aluminum wire (for weight reduction and cost savings) with copper wire (for electrical connectivity). The aluminum wire forms the primary gradient coil structure while copper wire provides connection terminals, creating a composite material system that leverages the advantages of both materials while mitigating their individual disadvantages through proper interface design.
2Productivity
If aluminum wire is used for mass production, then productivity increases, but oxidation-related quality defects occur
Solution Approach 1:
The patent applies preliminary protective actions by coating the aluminum wire with conformal coating material before welding operations. This pre-protection measure prevents oxidation from occurring during the welding process, ensuring consistent welding quality across mass production batches. The preliminary coating application enables high-speed automated welding without quality compromise.
Solution Approach 2:
The welding process is conducted in an inert or protected atmosphere environment, preventing aluminum wire oxidation during the welding operation. This controlled environment approach allows for consistent, high-quality welding of aluminum-copper joints in mass production settings, eliminating oxidation-related defects while maintaining high productivity.
3Ease of manufacture
If conventional welding with flux is used, then copper and aluminum can be joined, but oxidation of aluminum wire occurs
Solution Approach 1:
The patent introduces an intermediary protective layer (conformal coating) between the aluminum wire and the oxidizing environment during welding. This intermediary layer acts as a barrier that prevents direct contact between aluminum and oxygen, eliminating oxidation while allowing the welding process to proceed using conventional flux-based methods. The intermediary coating can be applied uniformly and removed or integrated after welding.
Solution Approach 2:
The patent modifies the chemical parameters of the welding environment by controlling atmosphere composition and temperature profiles during the welding process. These parameter changes prevent aluminum oxidation by maintaining reducing conditions or limiting oxygen exposure, while still enabling effective copper-aluminum joint formation through controlled metallurgical bonding.
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 production costs, eliminates oxidation-related defects, and allows for lighter gradient coils and thinner vacuum chambers, making the MRI system more cost-effective and easier to install and maintain.
Implementation Method 1
a copper wire end connected by cold pressure welding to two ends of the aluminum wire body
Data Source
AI summary
The present embodiments provide a gradient coil assembly. The gradient coil assembly includes an aluminum wire body, and a copper wire end connected by cold pressure welding to two ends of the aluminum wire body. Using the gradient coil according to a particular embodiment, it is possible to reduce gradient coil weight as well as reduce the thickness of an outer vacuum chamber used for a magnet, thereby reducing the cost of the magnet and gradient coil, and making it less difficult to install and maintain the magnet and gradient coil. There is no problem of oxidation associated with the cold pressure welding of the aluminum wire body to the copper wire ends, so quality defects arising from such oxidation are avoided.