Improved Design Of Control System For Paper And Yarn Compounding Bag Bottom-Pasting Machine

With the country vigorously promoting the construction of ecological civilization,the people's awareness of environmental protection has also begun to strengthen.It is bound to become the development trend of packaging industry to replace the non-decomposable plastic packaging with packaging materials that are easy to be degraded,low pollution and high strength.Paper yarn compounding bag has been widely used in agriculture and chemical industry due to strong bearing capacity,easy degradation and low breakage rate.However,China's packaging industry began to develop in the direction of semi-mechanization in the early 1950 s,and the production process of paper yarn compounding bag bottom pasting is complicated.And there was a lack of related complete production equipment in China.Although foreign related technologies have been matured,due to the high cost of introduction and the inconvenience of later maintenance,it is of great value to independently develop a set of paper and yarn compounding bag bottom-pasting equipment.In this thesis,based on the analysis of the technological process in the production process of paper yarn composite bag paste bottom,combined with the actual production demand of an enterprise,a set of control system of paper and yarn compounding bag bottom-pasting machine with PLC as the core is designed by using modern industrial control technology.The main research contents are as follows:1.Overall scheme design of paper and yarn compounding bag control system.Based on the analysis of the technological process of paper and yarn compounding bag bottom-pasting machine,and taking into account the stability,reliability and performance-price ratio of the control system,the overall scheme of the control system of the paste bottom machine is designed.2.The main hardware selection in the control system.In the process of production of the bottom gluing machine,the vibration of the equipment is too large due to the great fluctuation of pressure in vacuum system,and it is easy to damage the parts of vacuum pump vane and vacuum sucker.Through the calculation of the pipeline flow guiding in the vacuum system and the leakage flow rate of the vacuum system in the production process during the working process,the pumping speed of the vacuum pump in the vacuum system,the time of vacuum establishment and the volume of the vacuum chamber to make the vacuum system are designed,which make the pressure in the vacuum system fluctuate stably within the allowable range,shorten the working cycle of the vacuum pump,and meet the demand of vacuum gas source in the production process.3.I/O allocation and control loop design.According to the actual control requirements of the bottom gluing machine,the type and quantity of the input and output signals required in the control system are firstly determined,and the addresses of input and output ports of the control unit are assigned.Then,the main circuit of control system of the bottom gluing machine,the PLC input number and output circuit,the I/O expansion module and the analog input module circuit,the servo system control circuit and the stepping motor drive circuit are designed respectively which complete the hardware design of control system of the bottom gluing machine.4.System control program design.According to the process flow and control index of the bottom gluing machine,the overall control flow of the bottom gluing machine was designed.Then according to the control logic relationship between each module,the control flow and control program are designed for each control subsystem.Among them,in view of the problem that the position of the glue is inaccurate due to the relative sliding of the paper bag and the drive roller during the rubber coating process,a glue coating control subsystem with high precision of coating position and matching with the overall control system of the bottom gluing machine is designed.The gluing control system adopts a closed-loop control scheme,and uses a least squares method to perform nonlinear regression analysis on the test data of the gluing position without compensation speed,and the compensation speed of the servo motor is calculated in the end.According to the PLC logic operation detected by the photoelectric sensor,the speed of the servo motor is controlled by the PTOx MAN command to perform speed compensation.At the same time,the high-speed counter in the PLC is used to count the pulse signal from the servo motor incremental encoder to achieve precise control of the glue position.In the production process of the paper yarn composite bag,the precision of the glue application position is improved.Tests on the gluing system show that the pass rate of the gluing can exceed 98% within the allowable range of the gluing position error.