Reusable drinking straw
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Solution Overview
Problem
Conventional drinking straws have sharp edges at the user end, posing an injury hazard, and their manufacturing methods are not cost-effective or efficient, particularly in terms of accommodating thermal expansion and reducing bending stress during molding.
Innovation Solution
A drinking straw design with a rounded user end and side apertures, formed by injection molding, which includes a mold with specific cavity inserts and an opening sequence to manage thermal expansion and minimize bending stress on mold components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If straws are formed by extrusion of thermoplastic into a tubular stock with straight cut ends, then manufacturing cost is reduced, but sharp edges are created at the longitudinal ends posing an injury hazard
Solution Approach 1:
The end of the straw is formed with a rounded configuration instead of a straight cut end. The molding process creates a curved surface at the longitudinal end, eliminating sharp edges while maintaining structural integrity and safety for user contact.
2Object-affected harmful factors
If a rounded user end is formed to eliminate sharp edges, then safety is improved, but manufacturing complexity increases
Solution Approach 1:
The rounded end formation and lateral aperture creation are combined into a single injection molding operation. The molding process simultaneously creates the rounded configuration and the lateral apertures in one step, avoiding the need for separate machining or forming operations that would increase complexity.
3Object-affected harmful factors
If lateral apertures are added to reduce sharp edges, then safety is improved, but manufacturing precision requirements increase
Solution Approach 1:
The lateral apertures and rounded end formation are integrated into the same injection molding process. This simultaneous formation ensures proper alignment and dimensional accuracy without requiring additional precision machining steps, as both features are created by the mold cavity geometry in one operation.
4Productivity
If injection molding is used to form the straw with rounded end and lateral channels, then manufacturing efficiency is improved, but mold complexity increases
Solution Approach 1:
The mold is divided into a fixed portion and a movable portion, with the movable portion containing cavity inserts that can be independently actuated. This segmentation allows the complex rounded end and lateral aperture features to be formed by specialized cavity inserts while the main mold structure remains relatively simple and easy to operate.
Solution Approach 2:
The cavity inserts are made movable relative to the main mold body, allowing them to be actuated independently during the molding cycle. This dynamic capability enables the formation of complex features like rounded ends and lateral apertures without requiring the entire mold to be overly complex, as only specific portions need advanced movement capabilities.
5Adaptability or versatility
If a mold with multiple cavity inserts is used to form lateral channels, then manufacturing capability is improved, but bending stress on mold components increases
Solution Approach 1:
The cavity inserts are designed to move independently within the mold assembly, allowing them to be actuated only when needed during the molding cycle. This dynamic design reduces static loading and bending stress on the mold components, as the inserts can be positioned and retracted without requiring the entire mold structure to withstand constant high stress.
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 provides a safe, cost-effective, and efficiently manufactured drinking straw with reduced sharp edges, capable of mass production while addressing thermal expansion and bending stress issues during the molding process.
Implementation Method 1
accommodate thermal expansion of its components
Implementation Method 2
formed by injection molding
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
A drinking straw has an elongated body with a longitudinal flow channel. The user end of the body is closed and rounded for safety. A pair of lateral channels open onto the body adjacent the user end and provide fluid communication to the flow channel. The straw is injection molded, and a mold is provided which accommodates thermal expansion of a rod forming the flow channel. A pair of opposed cavity inserts form the lateral channels. To reduce bending stresses on the rod upon removal of the cavity inserts, one cavity insert is formed longer to the other. This longer cavity insert is removed prior to opening of the mold plates, and as such the straw and rod are supported against bending during this removal.