Metallic Card Wire Hunch Geometry for Resharpening
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Solution Overview
Problem
Existing card wires suffer from reduced carding performance after re-sharpening due to the creation of flat surfaces at the tip, leading to decreased fibre capture and increased fibre rolling, resulting in lower quality fibre webs and higher nep formation.
Innovation Solution
A metallic card wire design featuring an elongated rib portion with teeth comprising a front segment, a top segment with one or more hunches or flattened hunches, and a back segment, where the hunches or flattened hunches are positioned close to the tip to minimize height difference and angle, enhancing fibre retention and penetration, and the re-sharpening process maintains or even improves fibre capture capabilities by creating a leading edge and scratches on the flat land.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the card wire tip is re-sharpened to restore sharp leading edges, then the tooth sharpness is improved, but a flat surface is created at the tip which reduces carding performance and fibre capture capability
Solution Approach 1:
The tooth is segmented into multiple functional zones: a front segment with a sharp leading edge for fibre penetration, a top segment with hunches for fibre retention, and a back segment for fibre release. This segmentation allows each zone to perform its specific function optimally, with the sharp leading edge maintaining carding performance after re-sharpening while the hunches compensate for the flat surface creation.
Solution Approach 2:
Different parts of the tooth are given different geometric properties: the front segment has a sharp, angled leading edge for penetration, while the top segment features rounded hunches for fibre retention. This local differentiation ensures that the sharp leading edge maintains carding effectiveness after re-sharpening, while the hunches provide compensation for the flat surface created at the tip.
2Strength
If the platform or hump is positioned at a distinctly lower position than the tip, then the tooth tip strength is increased and fibre-holding capacity is improved, but the distance between the wire and carding surface increases causing fibre rolling and nep formation
Solution Approach 1:
Instead of creating a single large platform far from the tip, the invention uses multiple smaller hunches positioned very close to the tip (within 0.5mm). This partial action approach provides sufficient fibre retention support without creating excessive distance that would cause fibre rolling, thereby maintaining both tooth strength and preventing harmful fibre rolling.
Solution Approach 2:
The invention transitions from a two-dimensional platform concept to a three-dimensional arrangement of multiple hunches at different positions along the tooth length. By distributing hunches in both longitudinal and transverse dimensions, the design provides comprehensive fibre support close to the tip without requiring a single large platform that would increase distance from the carding surface.
Data Source
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AI summary
The first aspect of the invention relates to a metallic card wire (200) that is having an elongated rib portion and teeth. The teeth are comprising a front segment (220), a top segment (240) and a back segment (260). The front segment (220) comprises the connection of the tooth from the elongated rib portion and the front segment (220) includes a tip (230) which is actively taking fibres in carding. The top segment (240) is comprising at least one hunch (270) after the tip (230) in the direction of the back segment (260). If more than one hunch is present the first hunch is the hunch positioned closest to the tip; if only one hunch is present this hunch is the first hunch. The first hunch has in the hunch a minimum radius of curvature of more than 0.1 mm. The deepest point of the valley (275) between the tip (230) and the first hunch (270) has a distance from the tip in the direction perpendicular to the length of the card wire of minimum 0.03 mm. The highest point - or the middle of the zone that is highest - of at least one of the hunches lies within the two fictitious lines through the tip of the card wire that make an angle of -5 degrees and of +3 degrees with the longitudinal direction of the card wire. The back segment (260) is forming the connection of the top segment towards the elongated rib portion and the front segment (220) of the next tooth. The second aspect of the invention relates to a similar card wire as in the first aspect of the inventions, but with one or more flattened hunches (642, 644). The depth of the valley between tip and first flattened hunch (642) is preferably less than 0.15 mm. Card wires according to the first or two the second aspect of the invention can e.g. be used for cylinder and for lickerin rollers.