Escalator Step Structure for Low-Cost Lightweight Casting
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Solution Overview
Problem
Escalator steps produced by casting processes have high production costs due to complex geometry and require significant machining, and they need to meet mechanical, precision, and safety standards while minimizing weight and deformation.
Innovation Solution
A step design featuring a tread with structure ribs, a riser with recesses and protrusions, and side frames that reduce material usage and weight, incorporating features like inclined surfaces and slide coatings to minimize surface pressure and enhance mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex geometry is used to meet mechanical and safety standards, then reliability and strength are improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The step is divided into modular components: tread, riser, side frames, and reinforcement ribs. Each component can be manufactured separately and assembled, allowing complex geometry to be achieved through simple, standardized parts rather than monolithic complex casting.
Solution Approach 2:
Multiple functions are combined into integrated features: the side frames simultaneously provide lateral support, house the step roller axle, and connect to the step chain. The reinforcement ribs combine structural strengthening with weight reduction by creating optimized load-bearing paths.
2Productivity
If casting process is used for step production, then productivity is improved, but manufacturing precision and surface quality worsen due to required machining
Solution Approach 1:
The design extracts and separates features that require high precision from the main casting body. The step roller axle and step chain connection points are designed as separate components that can be precisely manufactured and assembled, rather than requiring precise casting and machining of complex integrated features.
Solution Approach 2:
The design changes the geometric parameters to be more favorable for casting: rounded corners instead of sharp edges, simplified profiles, and features that can be formed in the mold rather than requiring post-machining. This allows near-net-shape casting with minimal machining.
3Weight of moving object
If material usage is reduced to lower cost and weight, then productivity and weight are improved, but strength and reliability worsen
Solution Approach 1:
The step utilizes composite construction combining the tread and riser materials with reinforcement ribs of optimized cross-section. This creates a composite structure that achieves high strength-to-weight ratio by placing material strategically where loads are applied, rather than using uniform thick sections.
Solution Approach 2:
The riser incorporates curved areas that optimize structural efficiency. Curved geometries distribute stresses more evenly than sharp corners, allowing reduced material usage while maintaining or improving strength. The curved riser profile provides both structural integrity and weight reduction.
Data Source
Figure 1~2
Figure 3a~3c
Figure 4~5
AI summary
The following disclosure refers to a step (1) for an escalator, comprising a tread (2), a riser (3), side frames (4) forming a step roller axle (6) and a c-hole (5) for connecting the step (1) to a step chain and a first rib (8.1) extending between the c-holes (5), wherein an upper tread surface (2.6) comprises structure ribs (10.1) forming tread grooves (10) in between, wherein at least a part of the structure ribs (10.1) have protrusions (11) over the tread rear edge (2.2), each forming a catch (11.1) on a lower side of the protrusion (11), wherein the riser (3) forms recesses (12) for receiving the protrusions (11)of a likewise formed neighboring step (1), wherein the recesses (12) each have a limit stop (12.1) for the catches (11.1) on the bottom of the recess (12) and wherein the catches (11.1) and the limit stops (12.1) each have an inclined surface.