Ladder Tube Cross-Section Design for Bending Resistance
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Solution Overview
Problem
The manufacturing process of ladder tubes in collapsible ladders is prone to errors, leading to lower durability due to the construction of the tubes, which affects the overall performance and reliability of the ladders.
Innovation Solution
The ladder tube features a cross-sectional shape with at least one straight section connected at an angle greater than 90 degrees to additional convex sections, enhancing durability and reducing material costs while simplifying the manufacturing process by providing a stable reference point during extrusion and hole drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the ladder tube has a complex cross-sectional shape to increase bending resistance, then the durability is improved, but the manufacturing process becomes more difficult and material costs increase
Solution Approach 1:
The cross-sectional shape is divided into distinct segments: a straight section and multiple convex sections connected at angles greater than 90 degrees. This segmentation allows each part to serve its specific function - the straight section provides manufacturing stability while the convex sections provide bending resistance, resolving the contradiction between strength and ease of manufacture.
Solution Approach 2:
Different parts of the cross-section have different geometric properties tailored to their specific functions. The straight section has properties optimized for manufacturing stability and reference during drilling, while the convex sections have properties optimized for bending resistance. This local differentiation resolves the contradiction by assigning specific qualities to specific locations.
2Quantity of substance
If the ladder tube cross-section area is reduced to lower material costs, then the cost is decreased, but the bending resistance may be compromised
Solution Approach 1:
The convex sections in the cross-sectional shape provide curvature that efficiently resists bending forces. This curved geometry allows the tube to achieve high bending resistance with a relatively small cross-sectional area, as the curvature distributes stress more effectively than flat sections would, thus resolving the contradiction between material quantity and strength.
3Ease of manufacture
If the ladder tube lacks a straight section to simplify the cross-sectional shape, then the manufacturing process is easier, but the manufacturing precision and reference accuracy during hole drilling deteriorate
Solution Approach 1:
The straight section serves as a self-providing reference element that automatically establishes accurate positioning and orientation during manufacturing. It acts as its own measurement and alignment reference, eliminating the need for external reference tools or complex positioning procedures, thus resolving the contradiction between manufacturing simplicity and precision.
4Quantity of substance
If the connecting angles between sections are smaller than 90 degrees to reduce material usage, then the material cost is decreased, but the structural stability and resistance to deformation increase
Solution Approach 1:
The use of asymmetric angle connections (greater than 90 degrees) creates a stable geometric configuration that inherently resists deformation. This asymmetric angular design provides structural stability while the overall compact shape maintains reasonable material usage, resolving the contradiction between material quantity and structural stability.
Data Source
AI summary
A ladder tube (10, 12) for use in a ladder section of a collapsible ladder (1) is provided. The collapsible ladder comprises several ladder sections (5, 5a-5j), where each ladder section comprises two ladder tubes (10, 12) arranged parallel to each other and interconnected by a rung (20) to form the respective ladder section, and where each ladder tube (10, 12) is telescopically inserted into a ladder tube (10, 12) of a lower section to form the collapsible ladder (1). The ladder tube (10, 12) is characterized in that it has a cross-sectional shape comprising at least one straight section (16) which at each end is connected at an angle larger than 90 degrees to at least one additional section (18) of the cross-sectional shape.