Spinning Machine Draft Device Apron Speed Control
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Solution Overview
Problem
The existing methods for manufacturing special yarn with continuous portions of different colors and raw materials result in insufficient yarn strength at the feed start portion due to inadequate intertwining of fibers, leading to the formation of pills and lint.
Innovation Solution
A drafting device with two apron pairs and a controller that adjusts the speed of each apron pair to ensure preferred intertwining of fibers during the switching of roving feed, maintaining constant yarn thickness and strength by controlling the fiber feed amounts and speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If roving feed switching is performed by simultaneously starting one apron and stopping the other, then yarn production continuity is maintained, but yarn strength decreases at the feed start portion due to insufficient fiber intertwining
Solution Approach 1:
The patent applies preliminary action by having the new roving feed portion start feeding fibers before the old feed portion completely stops. The controller is configured to start the new apron at a first speed before the old apron stops, ensuring that fibers from both feed portions are present and can intertwine properly during the transition period. This preliminary overlapping of fiber feeds prevents the insufficient intertwining that would occur with simultaneous switching.
Solution Approach 2:
The patent applies dynamics by varying the speeds of the aprons during the transition period. The controller makes the new apron start at a first speed (lower than normal spinning speed) and then gradually increase to a second speed (normal spinning speed). This dynamic speed adjustment allows fibers to intertwine properly during the transition while maintaining production continuity, resolving the contradiction between continuous production and yarn strength.
2Productivity
If fiber feed switching is performed quickly to maintain production efficiency, then productivity is improved, but fiber intertwining becomes insufficient leading to pills and lint formation
Solution Approach 1:
The controller is configured to start the new apron before the old apron stops, creating an overlapping period where fibers from both feed portions are present. This preliminary action ensures sufficient fiber intertwining occurs during the transition, preventing the formation of pills and lint that would result from abrupt switching, while maintaining production efficiency through continuous fiber feed.
Solution Approach 2:
The patent changes the speed parameter of the aprons during the transition. The new apron starts at a first speed and gradually increases to a second speed, while the old apron simultaneously decreases its speed. This parameter change approach allows sufficient time for fiber intertwining (reducing pills and lint) while minimizing the impact on overall production efficiency.
Data Source
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AI summary
A draft device (10) of a spinning machine comprises a plurality of apron pairs (12, 13) provided so as to correspond respectively to a plurality of fiber feeders, a front roller (11) that is common to the apron pairs (12, 13), and a speed change controller (44) configured so as to change the speed of the apron pairs (12, 13) according to preset conditions. The speed change controller (44) is configured such that, when any one of the plurality of fiber feeders initiates fiber feeding, the controller outputs a drive command to the apron pair (12, 13) corresponding to the fiber feeder that initiates fiber feeding, and causes the apron pair (12, 13) to drive at a lower speed than during steady spinning for a predetermined duration and subsequently shift to a steady spinning speed.