| Recent years ramie stretch-breaking process technology has been brought forward for solving fiber damnification,nep,super & double long fiber by opening and carding process in tradition spinning course.Fiber damage,nep and super long fiber are decreased by stretch-breaking process instead of opening and carding process,and yarn quality is improved.The study of stretch-breaking technology has made progress for recent years.But the relationship between stretch-breaking technology paramters and fiber length changes is not cleared and definited in theory.Another,because of sticky fiber,quality of stretch-breaking sliver is not satisfied.Above two keypoints are studied emphasizely in this paper.Fiber length changes of stretch-breaking sliver affect quality of sliver and yarn,the relationship between stretch-breaking technology paramters and stretch-breaking sliver quality has been studied by experiment. The relationship between stretch-breaking technology paramters and fiber length changes is disicussed and definite in theory in this paper that provide reference for stretch-breaking technology study and practice.Practically because fiber tangle and sticky are grave, there are many sticky fiber and fiber clusters in stretch-breaking sliver by roller stretch-breaking machine processing that make stretch-breaking sliver quality low.By introducing assistant device,fiber abruption degree is increased and sticky fiber and fiber clusters are decreased that improve stretch-breaking sliver quality and create good condition for successive spinning process and yarn quality.Seeing from the angle of application practically,key device of stretch-breaking machine,stretch-breaking technology parameters and stretch-breaking spinning are studied and explored emphasisly in this paper that make on the basis for extending and applicationg of stretch-breaking technology.The main research contents and relevant research conclusions of this paper are as follows:1.Revealling inner regularity between stretch-breaking technology paramters and fiber length changes by theory study.1.1 Average fiber length after stretch-breaking Fiber average length by weight after stretch-breaking is: Where L is fiber length before stretch-breaking,N[L/(L0)],where=[L/(L0)] is maximum integer less than N. Pi is the probability of fiber breaking-place in stretch-breaking zone,δis the fiber length output from the front rollers nip while the fiber breaks, b is fiber breaking elongation, E is the stretch-breaking ratio, G is distance between the two pair of rollers.Theory calculation and experiment show: stretch-breaking gauge affects fiber average length after stretch-breaking, the average length increases as gauge increases; the average length decreases as stretch-breaking ratio increases.1.2 Fiber length unevenness after stretch-breakingThe square deviation of the treated fiber lengths is: , and the fiber length variation after stretch-breaking is:C= 6/Lx100%.Therefore, length variation is related with stretch-breaking gauge and ratio in theory.Theory calculation and experiment show:stretch-breaking gauge affects fiber length variation after stretch-breaking, the regularity is connected with relationship between gauge and input fiber average length, i.e. different input length need different gauge correspondingly; stretch-breaking ratio has little influence on length variation. 1.3 Short fiber content after stretch-breakingIn this paper, the fibers with length shorter than half of the average length are considered as short fiber. The short-staple fiber content after stretch-breaking is: ,whereStretch-breaking gauge and ratio affect the short-staple fiber content in theory. calculation and experiment show:short-staple fiber content decreases as stretch-breaking gauge and ratio increases, but influence degree is little. Unreasonable fiber distribution that made by improper technology parameter would bring hort-staple fiber. The average length,length variation and short-staple fiber content must be considered at same time.The relationship among fiber length parameters, like mean length, length irregularity and short fiber content, with stretch-breaking technology parameters were constructed quantitatively. The study results reveal inner regularity between stretch-breaking technology paramters and fiber length changes by theory study and provide reference for stretch-breaking technology study and practice.The conclusion is not only for ramie but also any other fiber.2. There are many sticky fiber and fiber clusters in stretch-breaking sliver by roller stretch-breaking machine processing that make stretch-breaking sliver quality low.By introducing assistant device in stretch-breaking machine,fiber abruption degree is increased and improve stretch-breaking sliver quality. Influence of assistant device to stretch-breaking sliver quality is studied and analysed and quality is compared with no-assistant device stretch-breaking machine.2.1 Assistant device of gill bar and porcupine roller is discussed.Experiment shows fiber abruption degree is increased and stretch-breaking sliver quality is improved by needle of gill bar and porcupine roller. Sticky fiber proportion is reduced by 41.9% and fiber clusters proportion is reduced by 60.9% after installing gill bar assistant device; and sticky fiber proportion is reduced by 20.9% and fiber clusters proportion is reduced by 56.3% after installing porcupine roller assistant device porcupine.But because fiber tangle and sticky are grave,fiber are blocked up behind gill bar.When porcupine roller is used,fiber wind needle and lapping that make needle bended and broken.Consequently producing continuity is affected.2.2 Knife wheel assistant device is designed and made on the basis of gill bar and porcupine roller. Knife wheel is composed of some parallel blades that are fitted on one roller. Knife wheel assistant device is an ensemble unit and installed at drafting-zone in stretch-breaking machine. Knife wheel splits fibers of sliver and oscillates that make fiber link weak.Below roller makes sliver embed knife wheel that give play to effect of knife wheel better.Assistant device resolve the problem of blocking up behind gill bar and winding needle.Meanwhile stretch-breaking are processed to the full because fiber bundle which are opened utmost are more loose and straight before reach stretch-breaking zone. Quality of stretch-breaking sliver is improved clearly after installing knife wheel assistant device.Sticky fiber proportion is reduced by 32.6% and fiber clusters proportion is reduced by 55.7%3.Technology experiment and spinning are processed on the stretch-breaking machine which contain knife wheel assistant device.3.1 Quality of stretch-breaking sliver which is affected by stretch-breaking technology parameters (knife wheel speed ratio,input weight,moisture regain,top roller pressure, stretch-breaking ratio, stretch-breaking gauge) is analysed.The main technology paranmeters are optimized.Study results show that stretch-breaking gauge and stretch-breaking ratio are chief effect factor by optimization experiment of fiber length variation, long fiber content, short-staple fiber content, sticky fiber proportion.Combining experiment results of single factor and optimization, optimum technology parameters of stretch-breaking sliver are: speed ratio of knife wheel and back roller is 1.1, output weight is 6.5g/m, top roller pressure is 0.45MPa, stretch-breaking gauge is 110mm, pre-stretch-breaking gauge is 170mm, stretch-breaking ratio is 4.5, pre-stretch-breaking ratio is 3.5. The experiment results provide reference for stretch-breaking production.3.2 Spinning is processed on the stretch-breaking machine which contain knife wheel assistant device.Semi-manufactured and end product quality of ramie stretch-breaking and traditional spinning are tested and analysed.Measurement results show that compared with carding sliver, quality of knife wheel stretch-breaking sliver is better excepting sticky fiber and clusters proportion.Fiber length variation is reduced by 51.2%, long fiber content is reduced by 85.7%, short-staple fiber content is reduced by 35.0%, nep is reduced by 66.7%. Compared with two processes stretch-breaking sliver, sticky fiber proportion is reduced by 35.3% and fiber clusters proportion is reduced by 46.1%. Sticky fiber and fiber clusters proportion are decreased by introduced knife wheel assistant device that make quality of stretch-breaking yarn improve and diminish appearance of blocking up condenser funnel that made by fiber clusters.Compared with two processes stretch-breaking yarn and carding yarn respectively, knife wheel stretch-breaking yarn breaking strength is increased by 6.5% and 18.7%, strength irregularity is reduced by 12.8% and 13.1%, yarn irregularity is reduced by 4.0% and 16.6%, nub is reduced by 12.3% and 63.6%, snicks is reduced by 14.0% and 63.0%, nep is reduced by 3.1% and 58.9%,3mm hairiness is reduced by 40.5% and 43.9%.In conclusion practicality of stretch-breaking is improved by adopting knife wheel and roller blend ramie stretch-breaking device that is also in favor of improving the quality of stretch-breaking sliver and yarn.The research results provide crucial basis for theory and experiment and have positive guidance meaning for ameliorating ramie stretch-breaking technology and device and improving yarn quality. |
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