Snap-Fit Hollow Tube Assembly Without Pultrusion Mandrels
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Solution Overview
Problem
Current pultrusion processes for producing hollow fiber-reinforced polymer profiles face challenges such as increased costs, reduced production output, and inconsistent dimensional stability due to the use of mandrels, which destabilize the process and affect the quality and consistency of hollow profiles.
Innovation Solution
The process involves assembling two or more non-hollow pultruded rails with snap members along their entire length to form complex hollow shapes, utilizing a self-clamping and self-aligning snap fit arrangement that eliminates the need for external clamps and ensures a tight joint, resembling a unitary piece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If mandrels are used to produce hollow pultruded profiles, then hollow cavity formation is achieved, but manufacturing cost increases by 40%-100%
Solution Approach 1:
The invention removes the mandrel from the pultrusion process entirely. Instead of using a mandrel to form the hollow cavity, the process extrudes a solid profile and then cores it to create the hollow cavity. This extraction of the mandrel eliminates the associated costs of mandrel design, manufacture, and setup while achieving the same hollow cavity formation objective.
Solution Approach 2:
The hollow cavity is formed through a preliminary coring action performed on the already-extruded solid profile. This preliminary action of creating the cavity after extrusion, rather than during extrusion with a mandrel, allows for cost reduction while maintaining the hollow profile functionality.
2Shape
If mandrels are used in pultrusion toolsets, then hollow profiles are produced, but production output decreases by 50%-75%
Solution Approach 1:
By removing the mandrel from the process, the invention eliminates the speed limitations imposed by mandrel heat control requirements. The mandrel-less process allows for higher line speeds and increased production output while still producing hollow profiles through the coring operation.
3Shape
If mandrels are used for hollow profile production, then hollow cavity formation is achieved, but dimensional stability and wall thickness consistency deteriorate
Solution Approach 1:
The invention removes the mandrel that causes flexing and movement during the pultrusion process. By eliminating the mandrel, the process avoids the destabilizing effects on wall thickness and dimensional stability, achieving consistent hollow profile production without the precision problems associated with mandrel support limitations.
4Shape
If mandrels are used in pultrusion processes, then hollow profiles are formed, but process complexity and setup time increase
Solution Approach 1:
The invention extracts and removes the complex mandrel toolset from the pultrusion process. This eliminates the need for elaborate mandrel support systems, hydraulic pressure management for mandrel stabilization, and associated toolset complexity, while still achieving hollow profile formation through the simplified coring process.
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 enhances the strength and manufacturability of hollow profiles, achieving consistency and stability comparable to unitary frames while reducing production costs and improving the cleanliness of the assembly process.
Implementation Method 1
elastic deformation of either the male or female member results in a normal force exerted on the other snap member. When this force is exerted on an angled surface, it produces a component force along the direction of engagement that urges the male member farther into the female member—clamping them together.
Data Source
AI summary
An assembly including a first elongated rail having a male snap member extending along its length, the male snap member having a groove extending along its length, and a second elongated rail having a female snap member extending along its length. The female snap member has a first leg and a second leg, the first leg including a foot. The male snap member is receivable between the first and second legs of the female snap member such that the foot of the female snap member is received in the groove of the male snap member to exert a force that retains the male and female snap members together such that the first and second rails are assembled to form a hollow tube.