Rotor Balancing Using Paramagnetic Sacrificial Blanks
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Solution Overview
Problem
Existing methods for balancing high-speed electrical machine rotors, particularly those operating above 15,000 rpm, are inefficient and unsuitable for industrial manufacture within short cycle times, as they either increase rotor mass or are not applicable due to damage concerns.
Innovation Solution
A method involving the use of paramagnetic metal blanks with specific dimensions, processed to create recesses outside the center of gravity based on the rotor's unbalance magnitude and orientation, which are then mounted on the rotor in defined angular positions to balance the unbalance effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If negative balancing is used to balance the rotor, then the unbalance is eliminated, but the rotor is damaged and cannot be used for high-power machines
Solution Approach 1:
Instead of removing mass from the rotor (negative balancing), the invention inverts the approach by adding sacrificial masses to balancing disks that can be removed. This allows balancing without damaging the rotor itself, solving the contradiction between rotor integrity and unbalance elimination.
Solution Approach 2:
The invention introduces balancing disks with sacrificial masses as an intermediary element. These disks serve as a medium to achieve mass compensation without directly modifying the rotor. The sacrificial masses on the balancing disks can be removed to balance the rotor while leaving the rotor itself undamaged.
2Manufacturing precision
If balancing disks with sacrificial masses are used for negative balancing, then the unbalance can be compensated, but the axial structural length and mass of the rotor are increased
Solution Approach 1:
The invention uses only the necessary amount of sacrificial mass on the balancing disks to achieve unbalance compensation. By carefully controlling the mass and position of these sacrificial elements, the solution achieves effective balancing while minimizing the additional mass and axial length, avoiding excessive addition.
3Weight of moving object
If traditional positive balancing methods are used, then the rotor mass is reduced compared to negative balancing, but these methods are not suitable for high-speed rotors operating above 15,000 rpm within short cycle times
Solution Approach 1:
The invention performs preliminary action by pre-calculating and pre-positioning sacrificial masses on balancing disks at specific locations. This preparation is done before the rotor reaches high operating speeds, allowing the balancing to be completed in advance. The pre-positioned masses enable the system to handle high-speed rotors within short cycle times without requiring time-consuming adjustments during operation.
Solution Approach 2:
The invention changes the parameters of the balancing approach by using sacrificial masses with specific mass values and positions on the balancing disks. By adjusting the mass and angular position of these sacrificial elements, the system can effectively balance rotors operating at high speeds (above 15,000 rpm) while maintaining short production cycle times.
Data Source
AI summary
A method is provided for balancing rotors (10) of electrical machines. Each rotor (10) has a shaft (11) and at least one laminated core (12) is arranged on the shaft. The method includes providing blanks (13) with a length (l) that is smaller than an outside diameter (d) of the laminated core (12) of the rotor (10). A magnitude and orientation of an initial unbalance of the rotor (10) then is ascertained. A recess (15) then is made in each blank (13) spaced from the center of gravity by a distance depending on the magnitude of the ascertained initial unbalance. The blank (13) is mounted by fitting the recess (15) on the shaft (11) of the rotor (10) and mounting the processed blank (13) on the rotor (11) in an angular position that is dependent on the orientation of the ascertained initial unbalance.