Blow-molded rib structure
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Solution Overview
Problem
Blow-molded plastic structures face a trade-off between weight reduction and strength, as hollow interiors reduce weight but also strength, and conventional strengthening ribs increase weight and production costs.
Innovation Solution
A sloping-height rib structure is integrated into the blow-molded plastic panels, with varying heights and widths, using less material and providing greater stiffness while maintaining strength through a gradual slope and wider dimensions in some portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If hollow interior is used to reduce weight, then weight is reduced, but strength is reduced
Solution Approach 1:
The panel is segmented into multiple hollow cells arranged in rows and columns, creating a cellular structure that provides strength while maintaining light weight. The cells are separated by walls that form a grid pattern, distributing structural loads throughout the panel.
Solution Approach 2:
The panel combines hollow cellular structure with integrally formed ribs to create a composite lightweight structure. The ribs extend between cells and provide additional structural support without significantly increasing weight, achieving both weight reduction and strength enhancement.
2Strength
If strengthening ribs made of metal or durable material are added, then load-bearing strength is increased, but weight is significantly increased
Solution Approach 1:
The ribs are formed with varying thicknesses at different locations along their length, optimizing material distribution. The ribs have greater thickness at ends where they attach to the panel and thinner sections in intermediate areas, reducing weight while maintaining load-bearing capacity.
Solution Approach 2:
The rib structure is segmented into multiple cells with walls separating them, creating a lightweight cellular configuration within the ribs themselves. This segmentation provides structural strength while minimizing material usage and weight.
3Strength
If integrally formed ribs with thicker walls are used, then load-bearing capability is increased, but production time is increased
Solution Approach 1:
The rib structures and cellular walls are integrally formed during the blow-molding process itself, rather than being added as separate components. The mold is designed with pre-formed rib structures that are created simultaneously with the panel, eliminating subsequent assembly steps and reducing production time.
Solution Approach 2:
The panel is divided into multiple hollow cells with walls forming a grid pattern, and ribs extend between these cells. This segmented cellular structure provides load-bearing capability while being formed in a single blow-molding operation, maintaining high productivity.
4Strength
If integrally formed ribs with thicker walls are used, then load-bearing capability is increased, but material usage is increased
Solution Approach 1:
The rib walls have varying thicknesses optimized for structural efficiency, with thicker sections at load-bearing locations and thinner sections elsewhere. This parameter variation provides necessary load-bearing capability while minimizing overall material usage.
Solution Approach 2:
The ribs are segmented into cellular structures with internal walls, creating a lightweight lattice configuration that provides strength through geometric arrangement rather than material quantity, reducing overall material usage.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A blow-molded structural panel (10) has a stiffening rib structure (14) in which the height and width of the rib structure varies over its length. For example, the rib structure may have three tall portions (16a-c) separated by two short portions (18a-b), with a gradual slope (22b-e) in height between the various portions. The rib structure is preferably wider in the short portions than it is in the tall portions. The lower height of the rib structure in some portions enhances the stiffness of the panel, while also using less material because the plastic does not have to be drawn so deeply into the mold in the short portions.