Rotor Casting Mold Gate Ratio for Porosity Reduction
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Solution Overview
Problem
The existing methods for producing rotors with metal cores, such as those for electric motors, suffer from high porosity in the conductor cages, which reduces their physical and electrical properties and requires additional balancing efforts, and the introduction of multiple gates leads to uneven filling and increased porosity in the upper short-circuit ring.
Innovation Solution
A method and casting mold design where the metal is introduced through a gate on the lower short-circuit ring, with a cross-sectional area ratio optimized to minimize hydraulic resistance, allowing rapid filling of the upper short-circuit ring, and using pressurization to compensate for shrinkage and reduce porosity, ensuring even filling and reduced turbulence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a gate is provided on both upper and lower short-circuit rings to introduce liquid metal simultaneously, then the filling is less turbulent and porosity is reduced, but the formation of two melt fronts leads to uneven filling and makes venting more difficult
Solution Approach 1:
The patent extracts the upper gate from the system, using only a single lower gate for metal introduction. This eliminates the complexity of coordinating two melt fronts while maintaining controlled filling through the optimized lower gate cross-sectional area ratio.
Solution Approach 2:
The patent dynamically adjusts the gate cross-sectional area ratio (AA/AΣL ≥ 0.5) to optimize the filling process. This dynamic parameter optimization allows controlled filling speed and turbulence reduction without requiring multiple gates, achieving uniform filling with simpler gate arrangement.
2Manufacturing precision
If the gate cross-sectional area is small, then the filling is slower and more controlled, but the upper short-circuit ring cannot be filled rapidly enough before metal solidifies in the grooves
Solution Approach 1:
The patent changes the critical parameter of gate cross-sectional area ratio (AA/AΣL ≥ 0.5) to achieve optimal balance between controlled filling and sufficient filling speed. This parameter optimization allows the metal to fill the upper short-circuit ring rapidly enough before solidification while maintaining turbulence control.
Solution Approach 2:
The patent ensures the gate cross-sectional area is preliminarily optimized before the casting process begins, allowing the filling to proceed at the correct speed without requiring real-time adjustments. This preliminary parameter setting ensures both controlled filling and adequate filling speed.
3Productivity
If the gate cross-sectional area is large, then the filling is rapid, but hydraulic resistance causes turbulence and increased porosity
Solution Approach 1:
The patent optimizes the gate cross-sectional area ratio parameter (AA/AΣL ≥ 0.5) to find the optimal balance point. This parameter change ensures rapid filling speed while minimizing hydraulic resistance and turbulence, thereby reducing porosity in the conductor cage.
4Ease of manufacture
If conventional die-casting is used with small gate cross-section, then the filling is controlled, but the conductor cage has high porosity that reduces electrical and mechanical properties
Solution Approach 1:
The patent fundamentally changes the gate cross-sectional area ratio parameter from conventional small values to AA/AΣL ≥ 0.5. This parameter change maintains easy manufacturing and filling control while dramatically improving conductor cage quality by reducing porosity and enhancing electrical and mechanical properties.
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 results in a rotor with lower porosity, improved electrical and mechanical properties, and enhanced efficiency, allowing for higher rotation speeds and reduced balancing efforts, while maintaining a stable conductor cage.
Implementation Method 1
the gate forming a cross-sectional area AA, a sum of the conductors forming a cross-sectional area AΣL, the gate having a ratio AA/AΣL ≥ 0.5... the gate does not represent any significant hydraulic resistance for the metal flowing into a cavity of the casting mold during filling
Implementation Method 2
using pressurization to compensate for shrinkage and reduce porosity
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method and a mold for manufacturing a rotor (10) for an electric machine, wherein the rotor is formed from a metal core (25), at least one lower short-circuit ring (20), an upper short-circuit ring (21), and lamellar conductors (17) connecting the short-circuit rings, wherein the method is carried out with a casting machine and a mold (22), wherein molten metal is applied to the metal core in the mold, the metal being copper, aluminum, or silver, wherein the rotor is formed with its axis of rotation (13) vertically relative to a horizontal plane of the mold, wherein the metal is introduced into the mold at a gate (27) of the mold at the lower short-circuit ring and fills the lower short-circuit ring, the conductors, and the upper short-circuit ring, wherein the gate forms a cross-sectional area AA, and wherein the sum of the conductors forms a cross-sectional area A∑L.wherein the section is used with a ratio AA ≥ 0.5∗A∑L, preferably AA ≥ A∑L.