Induction Motor Spindle Shaft Sleeve for High-Speed Rotor Cooling
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Solution Overview
Problem
High-speed machining spindles with AC induction motors face conductor portion breakdown and adherence issues due to heating and centrifugal effects at high rotational speeds, compromising torque performance and resilience.
Innovation Solution
A machining spindle shaft with a carbon fibre or Inconel alloy retaining sleeve is used over the squirrel cage winding to enhance resilience and maintain torque performance, allowing increased spacing between the rotor and stator for improved cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductor portions are plated onto the shaft to form the rotor, then good adherence is achieved, but breakdown occurs due to heating and centrifugal effects at high rotational speeds
Solution Approach 1:
The patent combines plated copper conductor portions with a carbon fibre retaining sleeve to create a composite structure. The carbon fibre sleeve reinforces the plated conductors, preventing breakdown under centrifugal forces and thermal stress while maintaining electrical conductivity and adhesion to the shaft.
2Power
If clearance between rotor and stator is reduced to improve torque performance, then motor torque increases, but cooling performance deteriorates
Solution Approach 1:
The carbon fibre retaining sleeve acts as an intermediary component between the rotor and stator. It allows maintenance of a larger air gap for improved cooling while the sleeve itself provides structural reinforcement, effectively decoupling the torque generation function from the mechanical strength requirement.
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
The solution significantly increases the resilience of the induction motor rotor to high-speed rotation while maintaining acceptable torque performance and enhancing cooling efficiency.
Implementation Method 1
an AC induction motor is formed by providing driving windings as the stator in the main body of the spindle and providing conductor portions inlayed into the material of the shaft to act as the winding of the induction rotor
Implementation Method 2
there can be a breakdown of the conductor portions themselves or of the adherence between the conductor portions and the material of the shaft due to heating and/or centrifugal effects
Implementation Method 3
breakdown of the conductor portions themselves or of the adherence between the conductor portions and the material of the shaft due to heating
Data Source
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AI summary
A machining spindle shaft (1b) for a machining spindle (1) having an ac induction motor (4) for rotatingly driving the shaft relative to a main body (1a) of the spindle (1). The shaft comprises a tool holder (2) for holding a tool (D) and comprises the rotor for the ac induction motor and the rotor comprises a winding (42) comprising conductor portions (42a, 42b) inlayed into material of the shaft and the shaft further comprises a retaining sleeve (5) provided over at least a portion of the winding for holding the conductor portions in place against heating and/or centrifugal effects during rotation of the shaft in use.