This paper focuses on the uniformity of fiber web output by roller cards, because control of uniform carded fiber webs becomes very important when we want faster and more accurate textile spinning. It will theoretically build the model of the dynamic system, and experimentally verifies the model with an implemented sensor. The system analysis, according to working properties and the active region, is divided into three parts: feed input, main carding, and doffer output. The system input is the mass flow rate of the fiber web per unit area. Firstly, the mathematical model of fibers at the main carding will be obtained, and then the mathematical models of the mass flow rate of fiber web at the input and output will be deduced. The mathematical model of the entire roller card system is finally derived by integrating the aforementioned three parts. The computer simulation confirms that the roller card is a stable system, as was shown in the real system. In the experimental verification, this paper measures the output of fiber web at the doffer with an infrared ray sensor, finds the relationship between the sense signals and mass flow rate of the fiber web, and compares the simulated output of the mathematical model with actual output, in order to verify the accuracy of the theoretical modeling of this system. This theoretic model of the roller card system will be used to control the quality and uniformity of the fiber web, as shown in the subsequent parts of this series of papers.
This study aimed to develop a dynamic model of a roller carding machine. The roller carding machine used in this study comprised one set each of feed conveyors, feed rollers, licker-in rollers, clothing rollers, a set consisting of a cylinder and doffer and two sets of carding rollers/stripping rollers. In order to establish a dynamic mathematical model of a roller carding machine, this study derived the transfer rate and collecting power of cotton web from the mode of movement, relative velocity, clothing tooth angle and friction force of the main rollers of the system. The transfer delay time of the cotton web was deduced from the clearance among working rollers, corresponding angle of roller center, and angular velocity. Finally, the correctness of the dynamic mathematical model of the roller carding machine derived in this study has been proved from the experiment.
The current roller carding machine control methods lack in the theoretical basis of using an auto-leveler, and are limited to the control of the cotton web layer thickness or the input amount of fibers. When the input amount changes, the output response is relatively slow, thus resulting in considerable impact on fiber web quality. Therefore, this study first established the theoretical modeling, and validated the dynamic mathematical model of the roller carding machine. This study used the sliding mode control in the design of the controller to control uniformity of the output fiber web of the roller carding machine. The sliding mode control used in this study was to allow the system to move in the dynamic process according to the pre-determined sliding mode trajectory, and then use the preset approximation conditions and switching conditions as the control law to navigate the system, in order to achieve the control objectives. Under the sliding mode control, with robust performance to suppress external disturbances and appropriate design of the sliding surface and boundary layer, dynamic model analysis and control adjustment for the system can be implemented to achieve the control objectives and uniform fiber web output. The experimental results confirmed that sliding mode control can effectively control fiber web uniformity of the roller carding machine.
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