Mower Rotor Balancing via Welded Ear Masses
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Solution Overview
Problem
Existing methods for balancing the rotor of a mower, such as welding masses to the rotor tube or using prominent discs, result in unbalance due to thermal expansion and wear, requiring additional correction operations and increasing working time.
Innovation Solution
Attaching balancing masses to the ears of the rotor, out of reach of the flails, allows precise calculation and placement, minimizing the total mass needed for balancing and reducing wear, with the masses welded to the ears to prevent geometry changes and thermal issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If balancing masses are welded to the rotor tube, then the rotor can be balanced, but the welding operation causes unbalance due to thermal expansion and shrinkage, requiring additional correction operations
Solution Approach 1:
The rotor is segmented into the rotor tube and separate ears (which may be integral or separate components). The balancing masses are attached to the ears rather than directly to the rotor tube, separating the balancing function from the rotor structure itself. This allows the ears to serve as dedicated mounting locations that do not interfere with the rotor tube's geometry or welding integrity.
Solution Approach 2:
The ears act as an intermediary component between the rotor tube and the balancing masses. Instead of welding masses directly to the rotor tube (which causes thermal distortion), the ears serve as a mediator that can be welded to the rotor tube and have masses attached to them. This intermediary structure isolates the rotor tube from the thermal effects of welding while still providing secure mass attachment.
2Manufacturing precision
If prominent discs are used to receive balancing masses, then the rotor can be balanced, but the discs are subject to wear degrading the balance
Solution Approach 1:
Different parts of the rotor structure serve different functions with appropriate properties. The ears are designed specifically for mass attachment with features like threaded holes or welding surfaces, while the rotor tube maintains its cutting function. The balancing masses are positioned on the ears away from the flails, creating a localized balancing zone that is not subject to the wear and impact experienced by the cutting components.
Solution Approach 2:
The ears are pre-configured with attachment features (threaded holes, welding surfaces) during rotor manufacturing. This preliminary preparation allows balancing masses to be securely attached in a controlled manner before the rotor is put into service, ensuring proper positioning and preventing wear-related degradation of balance. The ears are designed from the outset to serve as protected mounting locations.
3Manufacturing precision
If balancing masses are placed on the rotor tube, then the rotor can be balanced, but the geometry of the rotor tube is affected by the balancing operation
Solution Approach 1:
The rotor structure is segmented into the rotor tube (for cutting function) and separate ears (for balancing function). This segmentation allows the ears to be modified for mass attachment without affecting the rotor tube's geometry. The ears can be integral to the rotor tube or separate components, but in either case, they provide a dedicated location that does not compromise the rotor tube's shape or cutting performance.
4Manufacturing precision
If larger total mass is used for balancing, then the unbalance can be corrected, but the cutting head becomes heavier and requires stronger materials
Solution Approach 1:
The balancing masses are positioned on the ears, which extend radially outward from the rotor tube. This creates a more favorable moment arm for balancing, allowing smaller masses to achieve the same balancing effect. By utilizing the radial dimension provided by the ears, the system achieves efficient balance correction without requiring large masses that would increase the cutting head's overall weight.
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 achieves precise balancing without affecting the rotor's geometry, reduces the necessary mass, and allows easy disassembly and modification, meeting the ISO 1940 standard for balancing at high speeds, thereby preventing damage and ensuring optimal operation.
Implementation Method 1
This balancing mass is fixed by welding on the external part of the ear
Data Source
Figure 1
Figure 2
AI summary
The rotor has locating lugs (2) arranged on a tube (1) and permitting assembling of flails (3). The flails are utilized for cutting and crushing of plants. Balancing masses (8) arranged around a nut are fixed on outer parts of the locating lugs outside the flails by welding. The masses are pierced with a hexagonal opening greater than the dimension of the nut. The opening permits the placement of the masses, before their fixation, around the nut. An independent claim is also included for a method for balancing a mass of a rotor.