Drafting Unit Output Roller Control for Fiber Strip End Combing
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Solution Overview
Problem
Existing drafting devices for air-jet spinning machines fail to reliably prepare the fiber strip end before the spinning process, leading to thread defects and interruptions, and known methods do not adequately address the need for precise fiber conditioning during the spinning process.
Innovation Solution
The output roller pair is driven independently of the other drafting rollers, operating at a predetermined combing speed while the upstream rollers are stationary or at a low holding speed, followed by a combing process to condition the fiber strip end, ensuring optimal preparation for the spinning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the output roller pair is operated at a high combing speed while upstream rollers are stopped or held at low speed, then the fiber strip end is properly conditioned for spinning, but the fiber strip feed towards the vortex chamber is reduced or stopped
Solution Approach 1:
The drafting unit is divided into functionally independent roller pairs: the output roller pair (26) that combs the fiber strip end, and upstream drafting roller pairs (42, 43) that feed the fiber strip. This segmentation allows each segment to operate at different speeds for their respective functions - combing at high speed while feeding is reduced or stopped.
Solution Approach 2:
The system dynamically adjusts the speed of different roller pairs based on the operational phase. During combing operations, the output roller pair operates at high speed while upstream rollers are stopped or held at low speed. During normal spinning, all rollers operate at coordinated speeds to maintain continuous fiber feed.
2Manufacturing precision
If the output roller pair is driven independently from upstream drafting rollers, then precise control of fiber strip end preparation is achieved, but the device complexity increases
Solution Approach 1:
The output roller pair is designed to perform multiple functions: it acts as both a drafting element during normal spinning operations and as a combing device during fiber strip end preparation. This multi-functionality reduces the need for separate dedicated combing mechanisms, thereby limiting the increase in device complexity.
3Productivity
If the fiber strip is continuously fed during combing, then productivity is maintained, but the fiber strip end cannot be properly conditioned for seamless connection
Solution Approach 1:
The drafting unit operates in periodic cycles, alternating between combing mode (where fiber feed is reduced or stopped) and normal spinning mode (where continuous feed is restored). This periodic switching allows proper fiber strip end conditioning during combing while maintaining overall productivity through rapid transition back to continuous operation.
Data Source
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AI summary
The invention relates to a drawing unit for conveying a fiber strip towards an inlet opening of a vortex chamber of an air spinning device and to a method for operating a drawing unit comprising an output roller pair and at least one further drawing unit roller pair and/or belt roller pair, by means of which a fiber strip for the production of a thread is fed to a vortex chamber of an air spinning device at a spinning station of an air spinning machine, wherein the output roller pair can be driven independently of the at least one further drawing unit roller pair and/or belt roller pair.In order to provide a method for operating a drafting unit comprising a pair of output rollers and at least one further pair of drafting rollers and/or belt rollers, as well as a drafting unit which enables reliable preparation of the fiber strip end before the spinning process, it is provided that the pair of output rollers for combing the fiber strip end after a spinning interruption is driven at a predetermined combing speed and that the at least one pair of drafting rollers and/or belt rollers upstream of the pair of output rollers in the fiber strip direction is stopped or operated at a holding speed corresponding to the combing speed, which is a maximum of 10% of the combing speed.