Thermoplastic Handrail Extrusion with Reinforcing Cable Embedding
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Solution Overview
Problem
Conventional handrail manufacturing for escalators and moving walkways is labor-intensive and inefficient, requiring piecewise assembly and compression molding, which limits production rate and flexibility, and does not allow for continuous extrusion of uniform cross-section handrails.
Innovation Solution
A method and apparatus for extruding handrails using thermoplastic material and reinforcing cables, where the cables are embedded within the thermoplastic material in a tube, and the composite extrudate is cooled and solidified to form a continuous handrail with a uniform cross-section, incorporating a slider fabric for smooth operation and improved lip strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If piecewise compression molding is used to manufacture handrails, then the handrail achieves sufficient lateral stiffness and structural integrity, but the production rate is limited and the process is labor-intensive
Solution Approach 1:
The patent implements continuous extrusion of thermoplastic material to form handrails, replacing the discontinuous piecewise compression molding process. The extrusion die continuously forms handrail sections as the material is fed through the die, enabling uninterrupted production and significantly increasing productivity while eliminating manual assembly operations.
Solution Approach 2:
The patent replaces the mechanical compression molding system with a thermal extrusion system. Instead of using mechanical pressure and heat to cure rubber pieces, the process uses heated extrusion to continuously form and bond thermoplastic material, substituting a different physical mechanism that enables continuous operation.
2Strength
If multiple reinforcing plies are incorporated in the handrail, then the lateral stiffness and resistance to derailment are improved, but the manufacturing complexity and assembly difficulty increase
Solution Approach 1:
The patent combines multiple reinforcing plies into a single integrated structure during the extrusion process. The fabric reinforcement is embedded within the thermoplastic material as it is extruded, creating a unified composite structure rather than requiring separate assembly of multiple layers, thereby reducing manufacturing complexity while maintaining the required lateral stiffness.
Solution Approach 2:
The patent uses composite materials consisting of thermoplastic elastomer combined with fabric reinforcement. This composite approach allows the reinforcing plies to be integrated within the handrail body during extrusion, achieving the necessary mechanical properties while simplifying the manufacturing process compared to assembling separate components.
3Ease of operation
If the handrail is formed with a T-shaped slot and slider layer, then the handrail can slide freely on the guide, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The patent forms the T-shaped slot and integrates the slider layer continuously during the extrusion process. The die is designed to create the T-shaped cross-section with the slot already formed, and the slider material is applied or integrated in the same continuous operation, eliminating separate post-processing steps and maintaining high production rates.
4Productivity
If thermoplastic material is used instead of rubber, then continuous extrusion is enabled and production efficiency is improved, but the material selection becomes more constrained regarding hardness and flexibility balance
Solution Approach 1:
The patent utilizes the ability to adjust thermoplastic material parameters such as melt temperature, extrusion rate, and cooling rate to achieve the desired balance between hardness and flexibility. By controlling these processing parameters, the thermoplastic material can be tailored to provide the necessary mechanical properties for handrail applications while enabling continuous production.
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 the production of handrails with enhanced lip strength and flexibility, allowing for continuous manufacturing without the need for extensive manual assembly, with improved production efficiency and tolerance control, achieving lip strength comparable to conventionally molded handrails.
Implementation Method 1
permitting the composite extrudate to cool and solidify
Implementation Method 2
permitting the composite extrudate to cool and solidify
Data Source
Figure 1
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AI summary
A method of and apparatus for extruding an article of uniform cross-section, the article including a thermoplastic material and at least one cable for inhibiting stretch of the article. The cable is supplied to a respective tube and is conveyed between upstream and downstream ends. The thermoplastic material may be supplied to the downstream end of the tube. The thermoplastic material is brought together with the cable to embed the cable within the thermoplastic material, thereby forming a composite extrudate. The tube is configured to at least hinder movement of loose windings of the cable from the downstream end towards the upstream end, which may prevent or at least reduce incidence of "birdcaging".