Rotor Pole Core Parallelism Control via Post-Assembly Machining
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Solution Overview
Problem
Conventional rotor manufacturing methods for automotive alternators result in variations in parallelism between pole core end faces, leading to increased axial length, reduced mechanical strength, and increased manufacturing costs due to incomplete contact and potential deformation during assembly.
Innovation Solution
The method involves preparing pole cores with inclined contact surfaces for maximum parallelism and press-fitting the rotary shaft, ensuring the contact surfaces are in complete contact to minimize axial length and secure high strength without additional machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional forging methods are used to manufacture pole cores, then manufacturing cost is reduced, but variations in parallelism between end faces occur leading to increased axial length
Solution Approach 1:
The patent applies preliminary action by performing finish machining of the end faces after assembly but before final pressing. The machining is performed on the assembled rotor structure, allowing the pole cores to be positioned in their final configuration before the end faces are machined to precise parallelism. This eliminates the need for expensive high-precision forging while achieving the required parallelism through post-assembly machining.
2Ease of operation
If conventional pressing methods are used to assemble pole cores, then assembly simplicity is maintained, but incomplete contact between end faces occurs reducing mechanical strength
Solution Approach 1:
The patent performs finish machining of the end faces after the pole cores are assembled on the rotor shaft but before the final pressing operation. This preliminary machining ensures that the end faces are precisely parallel and will make complete contact during pressing, thereby maximizing mechanical strength while maintaining the simplicity of the pressing process itself.
Solution Approach 2:
The patent replaces reliance on mechanical precision of the pressing equipment with a machining process. Instead of depending on the pressing mechanism to achieve perfect alignment and contact, the end faces are machined to precise dimensions after assembly, substituting mechanical precision requirements with a controlled machining operation that guarantees complete contact.
3Manufacturing precision
If additional finish machining is performed to improve parallelism, then manufacturing precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent performs the finish machining operation at a specific stage in the manufacturing process - after assembly but before final pressing. This timing allows the pole cores to be in their final positioned state, enabling machining that achieves high parallelism precision. By doing the machining at this stage rather than requiring high-precision forging from the outset, the patent achieves the desired precision using standard machining equipment, thereby controlling manufacturing costs.
4Loss of time
If pole cores are pressed without precise parallelism, then assembly time is reduced, but deformation occurs during assembly increasing runout
Solution Approach 1:
The patent performs finish machining of the end faces after assembly but before final pressing. This preliminary action ensures that even though the pole cores are quickly assembled without high precision, the subsequent machining corrects any parallelism issues, preventing deformation during pressing and eliminating runout problems while maintaining quick assembly times.
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 the axial length of the rotor, enhances mechanical strength, minimizes runout, and maintains a straight rotary shaft, while reducing manufacturing costs by eliminating the need for additional finish machining.
Implementation Method 1
press-fitting the rotary shaft into the through-hole of the pole core
Data Source
AI summary
A method of manufacturing a rotor for a rotating electrical machine includes the steps of: preparing a first and a second pole core, a rotary shaft, and a field coil; press-fitting the rotary shaft into a through-hole of the first pole core so that the axes of the rotary shaft and the through-hole coincide with each other; mounting the field coil on one of the first and second pole cores; opposing the first and second pole cores to each other so that the axes of the through-holes thereof are in alignment with each other and contact surfaces thereof face each other with a maximum parallelism therebetween; press-fitting the second pole core onto the rotary shaft so that the contact surfaces of the first and second pole cores maximally contact with each other and the axis of the rotary shaft coincides with the axes of the through-holes of the pole cores.