Blow-molded plastic structures
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Solution Overview
Problem
Conventional blow-molded plastic structures are limited by their low strength and thickness, requiring additional materials and longer manufacturing times due to the need for thicker walls and strengthening ribs, which increase cost and weight, and restrict design flexibility.
Innovation Solution
The development of large, thin blow-molded plastic structures with a nominal thickness less than 12.7 mm, achieved by maintaining sufficient gas flow and pressure during the blow-molding process while keeping opposing surfaces separated by a minimal distance, allowing for the formation of closely spaced depressions that provide additional support and reduce material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If strengthening ribs are added to increase the strength of blow-molded plastic structures, then the strength increases, but the thickness of outer walls must be increased and manufacturing time increases
Solution Approach 1:
The patent divides the hollow interior space into multiple separate cavities instead of using a single large cavity with strengthening ribs. This segmentation allows the structure to achieve sufficient strength through the multi-chamber design without requiring additional thickening of outer walls or addition of strengthening ribs, thereby reducing manufacturing time while maintaining or improving strength characteristics.
Solution Approach 2:
The patent transitions from adding strength in the horizontal dimension (through strengthening ribs extending along the length/width) to achieving strength through vertical dimensioning (multiple cavities stacked or arranged within the thickness). This dimensional shift allows the structure to gain strength without increasing overall thickness or requiring additional cooling time for thicker walls.
2Strength
If outer wall thickness is increased to properly form strengthening ribs, then the strength increases, but additional plastic materials are required increasing cost and weight
Solution Approach 1:
The patent achieves strength enhancement through segmentation of the hollow space into multiple cavities, which provides structural reinforcement without requiring increased outer wall thickness. This approach maintains the original material quantity and weight while improving strength characteristics through the multi-chamber configuration.
Solution Approach 2:
The patent utilizes thin-walled blow-molded structures with multiple internal cavities to achieve high strength-to-weight ratio. The thin outer walls combined with the multi-cavity internal structure provide sufficient strength without requiring thick walls, thereby maintaining low weight and material consumption.
3Strength
If outer wall thickness is increased, then the strength increases, but more heat is retained during manufacturing requiring longer cooling time
Solution Approach 1:
The patent segments the hollow interior into multiple cavities, which provides structural strength without increasing outer wall thickness. Since the outer walls remain thin, heat dissipation during manufacturing is efficient, and cooling time is reduced compared to designs requiring thick walls for strength.
Solution Approach 2:
The patent achieves strength enhancement by utilizing the internal cavity arrangement rather than increasing wall thickness. This approach keeps the outer walls thin, allowing rapid heat dissipation and short cooling cycles during the blow-molding manufacturing process.
4Strength
If the number of strengthening ribs is increased to increase strength, then the strength increases, but more plastic materials and larger area on underside are required
Solution Approach 1:
The patent achieves strength enhancement by segmenting the hollow space into multiple cavities rather than adding numerous strengthening ribs. This approach uses the existing plastic material more efficiently to create structural reinforcement, avoiding the need for additional material to form extra ribs.
Solution Approach 2:
The patent transitions from horizontal strengthening (adding ribs that extend across the surface area) to vertical/cavity-based strengthening (multiple internal cavities). This dimensional shift provides strength enhancement without requiring additional plastic material or increasing the area occupied on the underside.
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 approach enables the creation of lightweight, high-strength blow-molded plastic structures with reduced thickness and weight, shorter manufacturing times, and increased design flexibility, while maintaining uniform properties and characteristics across the surface.
Implementation Method 1
During the blow-molding process, air or gas is injected into the hollow interior space and the gas helps mold the plastic into the desired shape by facilitating engagement of the plastic with the faces of the mold. The gas also keeps opposing surfaces separated during the molding process
Implementation Method 2
the thicker outer walls retain more heat during the manufacturing process. Thus, a longer cooling time is required during the manufacturing process in order to allow the thicker outer walls to cool
Data Source
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AI summary
A large, thin, generally planar panel constructed from blow-molded plastic may include a first surface, a second surface, and a hollow interior portion disposed between the first and second surfaces. The panel may include a nominal panel thickness (PT), which may be the distance between the first surface and the second surface, and a nominal wall thickness (WT), which may be the thickness of the outer wall of the blow-molded plastic structure. A plurality of depressions may be integrally formed in the second surface and a nominal distance (D) separating adjacent depressions may be measured from an edge of one depression to an edge of the adjacent depression. The relationship between the nominal panel thickness, the nominal wall thickness, and the nominal distance between adjacent depressions is shown by the equation WT · PT · D ≤.030.