Stator Core Shrinkage Fitting with Tapered Guide
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Solution Overview
Problem
The challenge lies in evenly shrinking stator cores for rotary electric machines to achieve a uniform diameter, which is essential for ensuring circularity and preventing distortion during the shrinkage fitting process, as segment cores are difficult to evenly shrink radially.
Innovation Solution
A stator manufacturing apparatus featuring a tapered guide unit with a heating unit to thermally expand the outer cylinder and a driving unit that reduces the stator core's diameter by guiding it through a tapered hole, allowing for uniform shrinkage fitting within a single step, while a heat insulating member prevents the guide unit from expanding and pressing units maintain the core's integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If segment cores are used to assemble the stator core, then the stator core can be manufactured by dividing the annular core into pieces for easier assembly, but the stator core becomes difficult to evenly shrink radially, leading to distortion and poor circularity
Solution Approach 1:
The stator core is divided into multiple segment cores that are assembled around the cage-shaped coil. This segmentation allows easier assembly of the core pieces, but creates the challenge of achieving uniform radial shrinkage. The invention addresses this by using a tapered guide unit to ensure even compression during the shrinkage fitting process.
Solution Approach 2:
A tapered guide unit with asymmetric geometry is introduced to apply radial compressive force during shrinkage fitting. The tapered shape (larger diameter at the top, smaller at the bottom) creates a progressive compression effect that evenly shrinks the segment cores radially as they are pressed through the taper, achieving the required circularity of 0.05mm or less while maintaining the assembly advantages of segmented cores.
2Manufacturing precision
If the stator core is evenly shrunk radially during shrinkage fitting, then uniform diameter and circularity are achieved, but it is difficult to accomplish with segmented cores without causing distortion
Solution Approach 1:
A tapered guide unit is introduced as an intermediary component between the pressing mechanism and the segment cores. This guide unit mediates the shrinkage fitting process by providing a controlled tapered path that automatically distributes the compressive force evenly across all segment cores, achieving uniform diameter without requiring complex multi-point pressing mechanisms.
Solution Approach 2:
The tapered guide unit employs a curved tapered surface instead of a flat pressing surface. This curvature (taper) creates a progressive radial compression effect as the segment cores are pressed through, ensuring even shrinkage in all radial directions and achieving the required circularity while simplifying the overall pressing mechanism.
3Length of moving object
If the axial dimension of the stator core is reduced to achieve compactness, then the output and compactness of rotary electric machines are enhanced, but the shrinkage fitting process becomes more difficult to control for uniformity
Solution Approach 1:
The tapered guide unit is designed with pre-calculated taper dimensions that anticipate the required shrinkage amount for reduced axial dimensions. By pre-setting the taper angle and length, the guide unit automatically provides the precise compressive force needed to achieve uniform shrinkage even when the target axial dimension is reduced for compactness, eliminating the need for iterative adjustment.
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 a uniform stator core diameter with a circularity of 0.05 mm or less, facilitating efficient shrinkage fitting and reducing the axial dimension of stator cores, thereby enhancing the compactness and output of rotary electric machines.
Implementation Method 1
a heating unit that heats and thermally expands the outer cylinder to increase an inner diameter of the outer cylinder
Implementation Method 2
a driving unit that inserts the stator core into the outer cylinder while reducing an outer diameter of the stator core by permitting the stator core to pass through the through hole on and along the taper thereof
Data Source
AI summary
A method is provided, for manufacturing a stator for a rotary electric machine by shrink-fitting an outer cylinder to a core assembly where a cage-shaped wound coil is assembled with segment cores. The assembly is inserted into the outer cylinder having a diameter increased by thermal expansion caused by the heat from a heating unit, while the outer diameter of the assembly is being reduced by permitting the assembly to pass through a tapered guide unit. The guide unit has a portion whose diameter is larger than an outer diameter of the assembly, and a portion whose diameter is larger than an inner diameter of the outer cylinder and smaller than an inner diameter of the cylinder in the thermally expanded state, and a tapered through hole vertically passing through the guide unit. Thus, the size of the assembly is radially reduced, with a uniform diameter being obtained throughout the assembly.