Spinning Frame Drafting Device Apron Pressure Control
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Solution Overview
Problem
Existing drafting devices for spinning frames face challenges in limiting the breaking of a second roving while facilitating the drafting of a first roving, as increased contact pressure between back apron pairs can hinder the feeding of fibers from the first roving, and reducing clearance between tensor bars and tensioners can lead to fiber separation and breaking.
Innovation Solution
A drafting device with a three-roller configuration and a pressing portion on the middle trumpet member that increases contact pressure between back apron pairs without affecting the middle apron pairs, ensuring smooth feeding and drafting of both rovings by maintaining separate contact pressures between different apron pairs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clearance between the tensor bar and the tensioner of the apron cradle is reduced to increase contact pressure between the back bottom apron and the back top apron, then fiber separation and breaking of the second roving is limited, but the contact pressure between the middle bottom apron and the middle top apron is also increased which hinders the feeding of fibers and drafting of the first roving
Solution Approach 1:
The invention divides the contact pressure control into two independent segments: the middle apron pair and the back apron pair. By providing separate tensioning mechanisms (first tensioning device for middle apron, second tensioning device for back apron), each segment can be optimized independently without affecting the other, thus resolving the contradiction between preventing fiber breaking in the back apron and maintaining smooth feeding in the middle apron
Solution Approach 2:
The invention applies different contact pressure levels to different locations: higher contact pressure is applied locally at the back apron pair to prevent fiber separation and breaking, while the middle apron pair maintains lower contact pressure to facilitate smooth fiber feeding and drafting. This localized differentiation of pressure conditions resolves the contradiction by addressing each zone's specific requirements
2Strength
If the contact pressure between the back bottom apron and the back top apron is increased to limit fiber separation and breaking, then the second roving integrity is improved, but the feeding of fibers from the first roving is hindered
Solution Approach 1:
The invention segments the tensioning control system into two independent parts: a first tensioning device for the middle apron pair and a second tensioning device for the back apron pair. This segmentation allows the back apron to exert higher contact pressure for roving integrity while the middle apron maintains lower pressure for efficient fiber feeding, thus resolving the contradiction between strength and productivity
Solution Approach 2:
The invention implements local quality by applying high contact pressure specifically at the back apron pair location to protect the second roving, while maintaining low contact pressure at the middle apron pair location to ensure efficient feeding of the first roving. This spatial differentiation resolves the contradiction between improving roving integrity and maintaining feeding efficiency
Data Source
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Figure 3~4
Figure 5A~5B
AI summary
A drafting device includes a pressing portion that increases the contact pressure between a back bottom apron and a back top apron without changing the contact pressure between a middle bottom apron and a middle top apron. This does not hinder feeding of fibers of a first roving that are held by a front bottom roller and a front top roller. Additionally, separation of fibers from a second roving and breaking of the second roving may be limited between the holding position of the front bottom roller and the front top roller and the holding position of the back bottom roller and the back top roller.