Research On The Key Technologies Of Seed Cotton Ginning And Lint Cleaning

As labor costs rise, the cotton harvesting trends to be accomplished by cotton-picker, but it adds up many difficulties to the cotton processing. Due to the higher foreign matter content and regain of machine-harvested cotton, that adding mechanical cleaning process has become the only way to make lint reaching qualified level. But excessive mechanical cleaning will cause great damage to cotton fiber. The machine-harvested cotton is poor in integrated quality than hand-picking cotton, so that has led to seriously descending of the lint integrated quality by adding mechanical cleaning process. The poor quality lint is hard to meet the demands of textile enterprises. In order to obtain higher profits and enhance enterprise competitiveness, cotton processing enterprises have to raise the lint quality in cotton processing and reduce the processing cost. Currently, the cotton processing equipments are not suitable for processing machine-harvested cotton with lower automation and intellectualization, and the fine cotton processing will not be carried out smoothly. Over all, the extensive cotton processing is the main cause of this dilemma.In this dissertation, the ginning and lint cleaning were studied, in order to improve the lint integrated quality as processing machine-harvested cotton. Although the process of ginning and lint cleaning is only a part of the cotton processing, but it has play an important role in improving integrated quality of lint. According to the characteristics of ginning and lint cleaning, three effective measures have been taken to improve lint integrated quality. The first is to keep saw ginning stably in case of mechanical and productive failure. The second is to improve cleaning efficiency and lower lint loss for the flow-through air lint cleaner. The third is to take saw lint cleaning as the important way for improving lint integrated quality. The three kind cotton processing techniques, saw ginning, flow-through air lint cleaning and saw lint cleaning, have their own special features and complement each other. The main research contents of the dissertation area as follows:(1) In the study for saw ginning stably, the theoretical analysis was developed of seed cotton roll that was the key factor to affect saw ginning stably, and then the multi-objective model was established according to ginning data. The force and motion analysis of seed cotton roll was helpful to ginning equipment improvement and process parameters optimization. These two parameters, density of seed cotton roll and speed difference between saw type roller and seed cotton roll, were taken as control objective of multi-objective model, in addition, the saw type roller speed and feed roller speed were taken as control variables. The multi-objective model was established by least squares support vector machine, and also could lay the foundation for saw ginning intelligent control.(2) In the flow-through air lint cleaner study for improving cleaning efficiency and lowering lint loss, first of all the force and motion of cotton fiber and foreign matter were analyzed as flow-through air lint cleaning, and then the internal flow field and discrete phase of the flow-through air lint cleaner were analyzed by numerical simulation method. In the theoretical analysis, a dynamic model of cotton fiber and foreign matter was established, and the phenomenon which foreign matter drained out of the notch and cotton fiber drained out of the lint exit was analyzed. The dynamic model could provide a theoretic support for the flow-through air lint cleaner to improve cleaning efficiency and lower lint loss. In the numerical simulation analysis, the effects of inlet air velocity, outlet pressure and notch width on the internal flow field and motion of cotton fiber and foreign matter were studied. Finally, according to the simulating orthogonal experiment results and internal flow field analysis results, the flow-through air lint cleaning process parameters were optimized, and the test results showed that the numerical simulation method to optimize process parameters was feasible.(3) In the saw lint cleaning study for improving lint integrated quality, the cleaning efficiency and cotton fiber damage were analyzed in a theory, and the experiment researches about the roller speed were developed as multi-stage saw lint cleaning. In the theoretical analysis, the force and motion of saw, cotton fiber and foreign matter were analyzed, and the effects of saw lint cleaning process parameters and structure parameters on the cleaning efficiency and cotton fiber damage were studied.The theoretical analysis about saw lint cleaning could provide a theoretic support for equipment improvement and process parameters optimization. The nail type roller speed of the saw gin upper cleaner, and saw type roller speed of the primary and secondary saw lint cleaner, had important effects on the lint integrated quality, so the experiment researches about these three factors were developed by the central composite design method. The lint appearance quality, the area of foreign matter, the number of foreign matter, reflectivity, the length of cotton fiber and the index of short fiber content were modeling by adopting the response surface method. The effects of single factor and coupling factors were analyzed on the six indicators. The multi-objective model could be used for saw lint cleaning intelligent control.(4) The intelligent control researches about saw ginning and saw lint cleaning were carried out based on the established models. For saw ginning, a single-step model predictive control was used, and the least square support vector machine model about saw ginning had been taken as predictive model. An improved particle swarm optimization algorithm was used for the rolling optimization procedure of the system. For saw lint cleaning, the optimization objective function of the lint integrated quality was set up by the multi-objective models, and then the improved particle swarm optimization algorithm was used to optimize the saw lint cleaning process parameters. The intelligent control strategies about saw ginning and saw lint cleaning were used on the control system platform, and the actual operation results showed that the control strategies in the paper were both correct and feasible.In this dissertation, the theoretical analysis and experiment researches about saw ginning and lint cleaning were carried out, and also the modeling and intelligent control were studied. The research results provided theoretic supports for equipment improvement and process parameters optimization in cotton processing. The study improved the level of automation and intellectualization in cotton processing, and also make fine cotton processing possible.