Closure Liner Venting via Lip Channels
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Solution Overview
Problem
Existing compression molding processes for sealing liners in closure shells often result in air bubbles due to clogged vent passages in the mold tooling, leading to increased production scrap rates and costs.
Innovation Solution
Incorporating vent passages through the closure shell, specifically a channel system on the lip that extends radially inwardly from the skirt, allowing air to escape during molding, thereby bypassing potential obstructions in the mold tooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vent passages are provided in the liner compression mold tooling, then air can be vented from the mold cavity, but the passages can become clogged or obstructed preventing proper ventilation
Solution Approach 1:
The patent extracts the venting function from the mold tooling and relocates it to the closure shell structure itself. The vent passages are formed as channels in the lip of the closure shell, separating the venting function from the compression mold tooling. This eliminates the risk of clogged passages in the mold tooling while maintaining effective air venting from the mold cavity during liner compression molding.
2Manufacturing precision
If vent passages are provided in the liner compression mold tooling, then air can be vented from the mold cavity, but air bubbles are still entrapped in the liner
Solution Approach 1:
The patent introduces the closure shell lip with its integrated channels as an intermediary structure between the mold cavity and the external environment. These channels serve as dedicated air escape paths that guide air bubbles away from the liner material during compression molding. The channels open at the radially inner edge of the lip and extend axially, providing a reliable intermediary pathway that prevents bubble entrapment in the liner while maintaining manufacturing precision.
3Productivity
If traditional mold tooling venting is used, then the process is simple, but the production scrap rate increases due to air bubble entrapment
Solution Approach 1:
The patent merges the venting function with the closure shell structure by forming channels directly in the lip during shell manufacturing. This integration combines the structural component with the venting function, eliminating the need for separate vent passages in the mold tooling. The result is a more reliable process that reduces air bubble entrapment and minimizes production scrap rates, thereby improving overall productivity and reducing material waste.
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 effectively reduces air bubble entrapment in the liners, lowers production scrap rates, and decreases the overall cost of producing plastic closures by ensuring proper ventilation of the mold cavity.
Implementation Method 1
at least one passage that extends through the lip... The channel preferably opens at a radially inner edge of the lip and at axially spaced surfaces of the lip
Data Source
AI summary
A plastic closure includes a shell having a base wall with a skirt for securement to a container finish and a lip that extends radially inwardly from the skirt at a position adjacent to and spaced from the base wall. A liner is compression molded in situ against the base wall, and between the base wall and the lip. The lip has a plurality of circumferentially spaced passages that extend through the lip for venting air during compression molding of the liner.