Plastic Washing Tub Rib Structure for Bearing Mount Rigidity
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Solution Overview
Problem
Existing washing machine tubs face challenges in withstanding high rotational and bending forces, especially at startup, due to material property differences between plastic and metal, leading to stress, cracking, and reduced durability, which limits their application in high-spin-speed and high-load scenarios.
Innovation Solution
The tub design features radially aligned Y-shaped ribs branching from the bearing mount, with varying radial spacing and multiple branches for enhanced stability, and optional transverse ribs for improved bending stress management, allowing for even force distribution and increased rigidity without material accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metallic bearing cross is integrated in the plastic end face wall through injection molding, then the tub gains additional stability and rigidity, but significant stresses arise during cooling due to different expansion coefficients and thermal conductivity, causing plastic shrinkage and potential cracking
Solution Approach 1:
The invention removes the metallic bearing cross from the tub structure entirely. Instead, it uses a bearing mount directly integrated into the plastic end face wall with a bearing housing that receives the drum shaft. This extraction of the metal component eliminates the material incompatibility issues while maintaining structural strength through optimized plastic rib design.
Solution Approach 2:
The invention changes the material parameter from metal to plastic for the bearing mount structure. By using plastic throughout (matching the tub material), it eliminates thermal expansion coefficient differences and thermal conductivity mismatches that cause stress during cooling. The design achieves rigidity through geometric optimization of plastic ribs rather than material substitution.
2Strength
If the end face wall is designed with high mechanical rigidity to withstand bearing mount stresses, then the tub can handle high spin speeds and loads, but the manufacturing complexity and cost increase
Solution Approach 1:
The invention merges the bearing mount structure directly into the plastic end face wall through injection molding, eliminating separate metal components and assembly steps. The bearing housing, ribs, and end face wall are formed as a single integrated plastic part, simplifying manufacturing while maintaining rigidity through optimized rib geometry that distributes bearing mount stresses effectively.
Solution Approach 2:
The invention segments the end face wall into functional zones using radially arranged ribs that divide the structure into stress-bearing segments. These ribs are strategically positioned to handle specific load directions from the bearing mount, allowing each segment to be optimized for its function while maintaining overall manufacturing simplicity through single-piece injection molding.
3Stability of the object's composition
If additional stabilizing means such as webs, ribs, or metal bearing cross are used in the end face wall, then the tub stability increases, but the device complexity and material usage increase
Solution Approach 1:
The invention applies local quality by concentrating stabilizing ribs in specific radial positions around the bearing mount where stresses are highest. Rather than uniformly thickening the entire end face wall, ribs are strategically placed to provide localized reinforcement exactly where needed, reducing overall material usage while maintaining tub stability under rotational and bending forces.
Data Source
AI summary
A plastic tub for a washing machine includes a cylindrical casing; and an end face wall sealing the cylindrical casing. The end face including a bearing mount for a shaft of a laundry drum and radially-aligned reinforcing ribs molded into the end face wall. The reinforcing ribs begin at the bearing mount and branch in a Y-shape along their radial extent.