Rotor Casting Mold Single-Gate Pressure Compensation
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Solution Overview
Problem
The production of electric machine rotors with metal cores and conductor cages often results in high porosity due to casting methods, which reduces physical and electrical properties, increases balancing efforts, and leads to inefficient rotor performance and higher porosity, especially when using a second gate on the upper short-circuit ring.
Innovation Solution
A method and casting mold design where molten metal is introduced solely through a gate on the lower short-circuit ring, with pressure applied via a ram to compensate for shrinkage in both the lower and upper short-circuit rings, ensuring even filling and reducing porosity by controlling flow velocity and using a variable chamber on the upper short-circuit ring to displace liquid metal back into the ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a second gate is provided on the upper short-circuit ring to introduce liquid metal simultaneously, then the filling is less turbulent and porosity is reduced, but the cavity is filled unevenly and venting becomes more difficult
Solution Approach 1:
The invention removes the second gate from the upper short-circuit ring, extracting the problematic element that caused uneven filling and venting difficulties. Only a single gate on the lower short-circuit ring remains, simplifying the gate arrangement while maintaining effective porosity reduction through the pressure compensation chamber mechanism.
2Productivity
If metal is introduced at a high flow rate to fill the upper short-circuit ring before solidification, then filling is completed in time, but porosity increases due to turbulent filling
Solution Approach 1:
The invention prepares the pressure compensation chamber in advance by introducing liquid metal into it before the main filling process. This preliminary action ensures that when turbulent filling occurs in the upper short-circuit ring, the chamber can immediately compensate by displacing metal back into the ring, maintaining low porosity despite high filling speeds.
Solution Approach 2:
The pressure compensation chamber acts as an intermediary between the gate and the upper short-circuit ring. It receives metal from the gate and mediates the filling process by allowing turbulent flow into itself while compensating for shrinkage and displacing metal back into the ring, thus decoupling the turbulent filling from direct ring filling.
3Manufacturing precision
If pressure is applied to compensate for shrinkage during solidification, then porosity is reduced, but the casting process becomes more complex
Solution Approach 1:
The invention merges the pressure compensation function with the existing casting mold structure by integrating the pressure compensation chamber directly into the mold. The chamber is formed as part of the mold cavity, eliminating the need for separate external pressure compensation devices and simplifying the overall system while maintaining effective porosity reduction.
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 significantly reduces porosity in the conductor cage, enhancing the electrical and mechanical stability of the rotor, allowing for higher rotation speeds and improved efficiency of electric machines by ensuring even filling and minimizing the formation of voids.
Implementation Method 1
the metal located in the chamber being subjected to pressure by means of a ram of the casting mold connected to the chamber
Implementation Method 2
the metal being melted and being introduced into the casting mold
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) on the lower short-circuit ring and fills the conductors and the upper short-circuit ring, wherein the metal is introduced into a variable chamber (29) on the upper short-circuit ring.wherein, by means of a plunger (30), the metal located in the chamber is subjected to pressure and displaced into the upper short-circuit ring.