Plastic Sheet Living Hinges With Constant-Depth Grooving
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Solution Overview
Problem
Existing methods for creating living hinges in plastic sheets, such as injection molding and using elongate tools, are limited to small objects and struggle with controlling groove depth in thinner sheets, especially when forming curved hinges.
Innovation Solution
A method and device using a gouge with a curved blade edge and guide elements to maintain constant groove depth while gouging, allowing for precise control and formation of both curved and linear living hinges on plastic sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a gouge is used to cut a groove in the pre-heated plastic sheet, then a living hinge can be formed, but the cutting edge causes a pulling force that makes groove depth control difficult
Solution Approach 1:
A support surface is introduced as an intermediary element between the gouge and the plastic sheet. The gouge is supported onto the support surface, which prevents the gouge from penetrating deeper into the plastic sheet due to pulling forces. This intermediary structure enables precise groove depth control while maintaining the living hinge formation capability.
2Ease of manufacture
If an elongate edge tool is pressed into pre-heated plastic to deform it, then linear living hinges can be provided, but curved living hinges cannot be produced
Solution Approach 1:
The gouge is made movable relative to the support surface, allowing it to follow curved or linear paths. This dynamic capability enables the formation of both linear and curved living hinges using the same tooling approach, eliminating the limitation of fixed linear tools while maintaining ease of manufacture.
3Ease of manufacture
If injection molding is used to provide a living hinge, then small plastic objects can have living hinges, but the method is not suitable for extruded plastic sheets
Solution Approach 1:
The injection molding process is replaced with a mechanical gouging process using a gouge tool. This substitution allows living hinges to be created in extruded plastic sheets through direct mechanical deformation, making the method applicable to sheet materials while maintaining the integration of the living hinge into the plastic object.
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
Enables precise control of groove depth and prevents galling, facilitating the creation of both curved and linear living hinges on various sheet thicknesses, including thin plastic sheets.
Implementation Method 1
deforming the material under pressure by a tool
Implementation Method 2
supporting the gouge onto the surface of the plastic sheet in which the groove is gouged
Data Source
Figure 1
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AI summary
The invention relates to a method for providing a living hinge in a plastic sheet, which method comprises the steps of: - providing a plastic sheet supported on a support surface; - providing at least one gouge movable relative and parallel to the plastic sheet; - gouging a groove in the plastic sheet with the at least one gouge, by moving the at least one gouge relative to the plastic sheet while maintaining the depth of the groove constant by supporting the gouge onto the surface of the plastic sheet in which the groove is gouged. The invention further relates to a device for providing a living hinge in a plastic sheet.