Electrical Steel Lamination Stacks with Liquid-Pressure Baking
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Solution Overview
Problem
Existing methods for joining electrical sheet metal lamellas, such as the baking varnish process, face challenges in maintaining constant pressure over complex geometries and compensating for shrinkage, leading to suboptimal results.
Innovation Solution
A method involving a pressure vessel filled with a liquid medium, where the electrical sheet metal lamellas are baked under controlled temperature and pressure, eliminating the need for classic pressing devices and allowing uniform pressure distribution, with optional pre-tacking and alignment using support structures and a welding film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional pressing devices are used to apply pressure during baking, then the baking varnish process can join electrical steel laminations, but consistent pressing pressures cannot be achieved across complex geometries such as circular segments, core discs, pole pieces, or stepped elements
Solution Approach 1:
The patent uses a pressure vessel filled with liquid medium (hydraulic system) to apply uniform pressure to the stacked electrical steel laminations during baking. The liquid medium transmits pressure evenly across the entire stack regardless of geometry, eliminating the need for complex mechanical pressing devices and achieving consistent pressure distribution for all geometric shapes including circular segments, core discs, pole pieces, and stepped elements.
Solution Approach 2:
The pressure vessel with liquid medium serves as a universal pressing system that can handle all types of electrical steel lamination geometries simultaneously. The same hydraulic system works for circular segments, core discs, pole pieces, and stepped elements without requiring geometry-specific adjustments, making the process universally applicable to all lamination shapes.
2Stability of the object's composition
If spring elements are used to compensate for shrinkage in the laminate height during baking, then pressing forces can be maintained, but the process becomes complex and often results in suboptimal work results
Solution Approach 1:
The hydraulic system using liquid medium in a pressure vessel automatically compensates for laminate shrinkage during baking. As the laminations shrink, the liquid medium maintains constant pressure without requiring mechanical spring elements or adjustable mechanisms. The incompressible nature of the liquid ensures stable pressing forces throughout the baking process, simplifying the device while maintaining force stability.
3Reliability
If electrical steel laminations are coated with baking varnish and stacked for self-bonding, then good insulation and corrosion protection are achieved, but the process requires complex pressing equipment that cannot handle all geometries
Solution Approach 1:
The patent combines the benefits of baking varnish self-bonding with a simple hydraulic pressure vessel system. The liquid medium provides uniform pressure during baking, enabling reliable insulation and corrosion protection through full-surface baking, while eliminating the need for complex mechanical pressing equipment. The process maintains high reliability for insulation while significantly simplifying the pressing device.
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 ensures optimal joining of electrical sheet metal lamellas with consistent pressure, preventing shrinkage effects and achieving enhanced strength and insulation, suitable for various geometries without the limitations of traditional methods.
Implementation Method 1
the liquid medium is heated to a predetermined temperature and the electrical steel laminations are baked together
Implementation Method 2
As the temperature increases, the pressure within the vessel also increases, acting constantly and uniformly on the stacked electrical steel laminations
Implementation Method 3
The baking varnish, which softens under the influence of heat, hardens upon cooling, joining the stacked electrical steel sheets into a solid package
Data Source
AI summary
The invention relates to a method for joining a plurality of electrical steel laminations (13) to form a lamination stack, in which electrical steel laminations (13) coated with electrical steel lacquer are stacked and, in the stacked state, are baked together under pressure and heat, characterized in that the stack of laminations (5) to be baked is placed in a vessel (2) designed as a pressure vessel, the vessel (2) is hermetically sealed and, in particular, completely filled with a liquid medium, whereupon the liquid medium is heated to a predetermined temperature and the electrical steel laminations (13) are baked together for a predetermined period of time at a predetermined pressure. The invention further relates to a device (1) for carrying out such a method.