Rapier Wheel Convex Spokes Reduce Bending Stress
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Solution Overview
Problem
Rapier wheels in weaving machines face challenges in achieving a balance between low moment of inertia and high rigidity and durability, as existing designs often result in bending stresses due to tangential and radial forces exerted by the rapier.
Innovation Solution
A rapier wheel design featuring convexly curved spokes in pairs, which counteract forces by being angled towards the outer ring, reducing bending stresses and allowing only pressure or tensile forces to act on the spokes, thereby enhancing durability without increasing the moment of inertia or weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If straight spokes are used in the rapier wheel, then the structure is simpler and easier to manufacture, but bending stresses occur due to tangential and radial forces reducing durability
Solution Approach 1:
The spokes are designed with convex curvature toward the outer ring instead of being straight. This curvature allows the spokes to better withstand tangential and radial forces exerted by the rapier, reducing bending stresses and improving durability while maintaining structural integrity during rotation
2Reliability
If the rapier wheel is made more rigid to withstand forces, then durability improves, but the moment of inertia increases reducing operational efficiency
Solution Approach 1:
The spokes have varying cross-sectional dimensions along their length, with the width and height being different at mid-span compared to the ends. This allows the spokes to have higher strength where needed to withstand forces while reducing material in less critical areas, thereby maintaining durability without significantly increasing the moment of inertia
3Strength
If heavier materials or thicker spokes are used to increase rigidity, then durability improves, but the moment of inertia and weight increase
Solution Approach 1:
The spoke dimensions are optimized with specific width and height parameters that vary along the length. The convex curvature and dimensional variations allow the spokes to achieve necessary rigidity and strength to withstand operational forces while minimizing the overall moment of inertia and weight of the rapier wheel
Data Source
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AI summary
The invention relates to a rapier wheel for a rapier weaving machine having an inner ring (20), an outer ring (21), and a number of spokes (22, 23), wherein the inner ring (20) is configured for mounting the inner ring (20) to a drive shaft (10), wherein the outer ring (21) is provided with teeth (210) configured for engaging with a rapier (6) for driving the rapier (6), wherein the spokes (22, 23) extend between the inner ring (20) and the outer ring (21) and connect the inner ring (20) with the outer ring (21), wherein the spokes (22, 23) are arranged crosswise in pairs of spokes (24) comprising a first spoke (22) and a second spoke (23), wherein the first spoke (22) and the second spoke (23) extend in opposite directions and cross each other at a crossing point (25) between the inner ring (20) and the outer ring (21), and wherein the first spoke (22) and the second spoke (23) are each convexly curved toward the outer ring (21). The invention further relates to a rapier weaving machine with such a rapier wheel.