Research On PLC-based Control System Of Cotton Baling Press

The cotton baling press is an important and irreplaceable equipment in the modern cotton production industry. The control system, on which the cotton packing process was realized automatically, takes a decisive part in the function of the cotton press. With the development of cotton quality inspection in China, traditional control system of cotton press couldn't meet the practical requirements of the production, and to improve the control system is extremely urgent.This subject is based on the electrification transforming for the control system of double box down-packing hydraulic cotton press. After investigating and analyzing on the the production process of cotton packing, the structure and composition of cotton press and the production environment, a control system scheme, in which a programmable programmable logical controller(PLC) was applied as the main control unit to replace the existing relay-contactor system, was put forward. The subject focus on the realization of PLC-based control system, and the control requirements of cotton press were analyzed carefully. Then, the design of a integrated PLC-Based control system was carried out, including hardware design, control software developing and HMI design.Cotton weight controlling and adjusting methods and their realization were analyzed in this thesis, and a means by measuring the pressure was adopted to achieve the weight control. In this system, pressure signal was collected by a pressure transmitter, transformed by the A/D module, and then sent to the PLC and compared with a value set. And the outcome of the comparison indicates that whether the cotton inside is enough. Besides, considering the influence of moisture regain to cotton weight, the moisture regain testing was carried out, and the cotton weight would be regulated according to the testing result.The factors, which affect the control system of cotton press actually, were analyzed based on the reliability theories of mechatronic systems. According to the analyzing result, the factors were divided into two types:on-site disturbance and system failures. To improve the reliability of control system, several measurements were proposed combined with the production environment, and the reliability design of the control system was actualized.