Cast Coil Forming with Permanent Mold and Compact Windings
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Solution Overview
Problem
Existing methods for producing cast Al and Cu coils are unsuitable for series manufacture due to short tool life, complex processes, and poor geometric control, leading to inefficient use of installation space and reduced power or torque density in electric machines.
Innovation Solution
A method involving the use of a reusable permanent mold to cast an elongate conductor into a cavity with a rosette shape, followed by plastic deformation to form windings closer together, eliminating undercuts and allowing easy demolding, and a guide rod to shape the coil into a compact form.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional lost core methods are used to produce cast coils, then complex geometries can be achieved, but tool service life is very short and production cost is high
Solution Approach 1:
The patent replaces expensive, short-lived lost cores with reusable permanent molds. The permanent mold can be used repeatedly for series production, eliminating the need to create new cores for each casting operation. This resolves the contradiction by providing both complex geometry capability and long tool service life through the reusable mold system.
Solution Approach 2:
The patent changes the fundamental parameter of mold reusability from single-use (lost cores) to multi-use (permanent molds). By modifying the material properties and structural design of the molding tool to withstand repeated high-temperature casting cycles, the tool service life is dramatically extended while maintaining the ability to produce complex coil geometries.
2Ease of manufacture
If conventional tool steels are used for casting tools, then manufacturing is simpler, but thermal stress causes rapid aging and damage
Solution Approach 1:
The patent employs composite material structures for the permanent mold, combining materials with high thermal resistance and mechanical strength. This allows the tool to withstand the thermal stress and temperature shocks of copper casting (above 1100°C) without rapid aging or damage, while remaining manufacturable through specialized processes.
Solution Approach 2:
The patent designs the permanent mold with pre-engineered thermal management features and stress-resistant structures that cushion against thermal shock before damage occurs. This preventive design approach allows conventional or specially treated steels to withstand repeated thermal cycling without rapid degradation.
3Ease of manufacture
If wire of constant cross-section is used for windings, then manufacturing is simple, but heat dissipation is impaired and maximum current density is limited
Solution Approach 1:
The patent implements variable cross-section conductors where the wire diameter changes along the length of the conductor. Regions with higher current density or poorer heat dissipation have larger cross-sections, while other regions have smaller cross-sections. This local optimization improves heat dissipation and allows higher maximum current density while remaining manufacturable through the permanent mold casting process.
4Volume of moving object
If complex manually produced coils are wound to improve filling degree, then power density increases marginally, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent replaces the mechanical winding process with a direct casting process using permanent molds. The mold cavity is designed to form the final coil geometry directly, eliminating the need for complex winding machinery and manual assembly. This achieves high installation space utilization through optimized mold design while dramatically reducing manufacturing complexity and enabling series production.
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
Enables efficient production of coils that maximize installation space utilization, suitable for series manufacture, with improved heat dissipation and reduced material waste, enhancing power density in electric machines.
Implementation Method 1
a semi-finished product in the form of an elongate conductor (5) is formed by casting in a cavity (2) of a casting tool
Implementation Method 2
the semi-finished product (5) is shaped in order to form a coil (6), wherein windings (10) of the coil already present in the semi-finished product (5) are brought closer to one another
Data Source
AI summary
A method for producing a coil includes casting; a semi-finished product in a cavity of a casting tool and the coil is formed following a demolding of the semi-finished product by shaping this semi-finished product, wherein the form of the semi-finished product may be derived from a shape of the finished coil by stretching along a longitudinal axis of the coil and/or by bending this longitudinal axis, and wherein the semi-finished product, during the shaping, is bent and compressed so that windings of the coil already present in the semi-finished product are brought closer to one another at least in some regions and are brought into an arrangement along the longitudinal axis of the finished coil, wherein the product, whilst being shaped, is twisted or bent by no more than a right angle over the course of each individual turn.