Injection Molded Meter Pit With Ribbed Sidewalls and Footing Cutouts
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Solution Overview
Problem
Existing meter pits are inefficient in material usage, prone to settling due to uniform wall thickness, and require post-molding processing, leading to material waste and increased costs, while also needing to withstand significant crush forces without optimal structural integrity.
Innovation Solution
An injection molded meter pit with varying wall thickness and ribs for enhanced compressive resistance, featuring cutouts in the footing to reduce material usage and eliminate post-processing cutting requirements, and a mold design that allows for efficient production with reduced cycle time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If roto-molding process is used to manufacture meter pits, then the walls achieve uniform thickness, but this results in excessive material usage and increased cost
Solution Approach 1:
The patent applies local quality by varying the wall thickness of the meter pit according to specific structural requirements. The injection molding process enables different sections of the pit to have different wall thicknesses - thicker walls where structural strength is needed and thinner walls where less support is required - thereby eliminating the material waste inherent in uniform thickness designs while maintaining manufacturing precision through controlled injection molding parameters
2Ease of manufacture
If uniform wall thickness is used in meter pits, then manufacturing is simplified, but the pits become prone to settling into the ground
Solution Approach 1:
The patent uses local quality by concentrating thicker wall sections at the bottom of the meter pit where the footing contacts the ground, providing enhanced resistance to settling forces. The upper portions of the pit can have thinner walls since they bear less structural load. This localized variation in wall thickness maintains ease of manufacture through injection molding while significantly improving reliability against settling
Solution Approach 2:
The patent applies segmentation by dividing the pit into distinct zones with different wall thickness characteristics - a thicker footing section at the bottom for structural support and resistance to settling, and thinner wall sections above. This segmentation allows each zone to be optimized for its specific function while being manufactured as an integrated component through injection molding
3Ease of operation
If post-molding cutting operations are performed to create holes, then plumbing access is achieved, but material waste increases and production time extends
Solution Approach 1:
The patent applies preliminary action by incorporating the plumbing access holes directly into the mold cavity before injection molding. The holes are formed as integral features of the mold, allowing plastic to flow through and create hollow passages during the molding process itself. This eliminates the need for post-molding cutting operations, thereby preventing material waste and reducing production time while maintaining ease of plumbing installation
4Shape
If roto-molding with two colors is used, then aesthetic requirements are met, but reusability of scrap material is eliminated
Solution Approach 1:
The patent applies parameter changes by transitioning from a two-color roto-molding process to a single-color injection molding process. This parameter change in the manufacturing method eliminates the creation of multi-colored scrap material that cannot be reused, while still achieving aesthetic requirements through proper gating design, rib formation, and surface finish control in the injection molded part. The scrap material from this process can be fully reused in subsequent production runs
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
The solution results in a meter pit that uses less material, resists settling, and maintains structural integrity to withstand 20,000-pound loads, while minimizing waste and production time, thus being more cost-effective and reliable.
Implementation Method 1
The wall and the footing are formed by injection molding
Data Source
AI summary
A pit defining an opening and having a footing. Cutouts are located in the footing and are created in mold to avoid secondary cutting operations. The wall of the pit above the footing is narrower than the footing and includes ribs extending from the wall for added compressive resistance. The ribs may vary in size both in length and extension into the center of the pit.