Plastic Expanding Spring for Closure Piston Retention
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Solution Overview
Problem
Existing tube dispensers for viscous products, such as toothpaste, face challenges in cost-effectiveness and safety due to complex manufacturing processes and the risk of injury from metal expanding springs, which require additional costly covers for protection.
Innovation Solution
A plastic expanding spring with a central part and radially extending fingers, connected via a web and potentially filled with elastomeric material, provides a cost-effective and safer solution by achieving clamping force through finger elasticity and radial pretension, preventing the closure piston from moving towards the container's lower end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal expanding spring is used, then the clamping force and reliability are improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the material parameter from metal to plastic, and changes the structural parameter from a separate assembled spring to an integrally molded component. The plastic expanding spring is produced in a single injection molding process as part of the closure piston, eliminating the need for separate manufacturing and assembly steps while maintaining the necessary clamping force through proper geometric design of the fingers and their connection to the central part.
Solution Approach 2:
The patent merges the expanding spring with the closure piston into a single integrally formed component. The spring fingers are directly molded as part of the piston body, with the central part serving as the connection point. This integration eliminates the need for separate assembly operations and reduces the number of parts, thereby simplifying manufacturing while preserving the spring's functional properties.
2Reliability
If a metal expanding spring is used, then the spring action is improved, but the safety deteriorates due to injury risk
Solution Approach 1:
The patent changes the material parameter from metal to plastic, which fundamentally alters the safety characteristics. Plastic material eliminates the sharp edges and metallic sharpness that cause injuries, while still providing the necessary elastic spring action through the geometric design of the fingers. The plastic material is inherently safer for user contact while maintaining the required mechanical functionality.
3Object-affected harmful factors
If a cover is added to protect from the spring, then the safety is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the separate protective cover by integrating the safety function directly into the expanding spring design. The spring fingers are designed with rounded contours and smooth surfaces that are inherently safe for user contact, eliminating the need for an additional protective component. This integration removes the cover from the bill of materials and simplifies the manufacturing process.
4Force
If the expanding spring is made as a separate metal part, then the spring force is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The patent changes the material parameter from metal to plastic, which fundamentally improves ease of manufacture. Plastic injection molding allows for complex three-dimensional spring geometries to be produced in a single step as an integral part of the closure piston. This eliminates the need for separate spring fabrication, heat treatment, surface finishing, and assembly operations required for metal springs, while still achieving the necessary spring force through proper geometric design.
Solution Approach 2:
The patent merges the expanding spring with the closure piston into a single integrally formed component produced by injection molding. The spring fingers are directly molded as part of the piston body, with the central part serving as the connection point. This integration eliminates the need for separate assembly operations and reduces the number of parts, thereby simplifying manufacturing while preserving the spring's functional properties.
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 allows for a cost-effective, injection-molded expanding spring that enhances safety by preventing accidental downward movement of the closure piston, reducing manufacturing complexity and enhancing user safety.
Implementation Method 1
The clamping force of the expanding spring is achieved by the elasticity of the fingers, whereby in the installed state these engage with the inner wall of the container under radial pretension
Data Source
Figure 1
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AI summary
The invention relates to a dispenser (10) having a container (11), one end of which is closed by a closing tap (12) that can be adjusted in a first direction (R) relative to the container. A cup expander spring (13) is arranged on the side of the closing tap facing away from a product space (14) of the container, said spring engaging with the inner wall of the container and preventing displacement of the closing tap in a second direction opposite the first direction. The cup expander spring is made of plastic and has a center part (20) from which a plurality of fingers (15) arranged distributed across the circumference extend radially outward. Each finger is hinged to the center part at the radially inner end of the respective finger and engages with the inner wall of the container at the radially outer end of the respective finger. The center part and the fingers are formed as one piece and each finger is connected to the center part via a web (17), wherein a cutout (16) is formed in the region of the web.