| Popis: |
Analyzing the features of the design, principle of operation and electric drive of the concrete mixer type SMZH-69A, the authors came to the conclusion that the mechanism of movement of this device and its control system most urgently needed modernization. In order to increase the efficiency of work, it is proposed to use a frequency-controlled electric drive of the mechanism of movement on the basis of an asynchronous motor with a short-circuited rotor. It is recommended to replace the outdated displacement actuator in the form of an engine, gearbox and chain drive on the motor-gearbox, which will allow space for the installation of controllers and other automatic control system equipment. A modern motor-gearbox has been selected for the mechanism of movement of the concrete spreader, a PLC-based electric drive control scheme has been developed. It is proposed to use a tensometric method of weighing the concrete mixture, for which a hopper with a concrete mass is mounted on the strain gauges. When filling the hopper of the concrete spreader to a certain mass, the signal from the load cells is sent to the controller, after which the program starts to work. The input signal is the mass of the concrete mixture fed into the hopper, and the output signal is the voltage applied to the controller and then, via the frequency converter, to the control object the drive of the concrete dispenser. The controlling influence of the control object (CO) is the voltage applied to the gear reducer, and the disturbing influence is the static loading force from the weight of the concrete spreader, the weight of the concrete mixture in the hopper and the resistance force of the damper. An CO computational model was developed to investigate the transients of a control object by changing its control and disturbance influences. Analysis of transients has proven the efficiency and quality of the control system. The algorithm of functioning of the automatic control system of the concrete dispenser is developed, on the basis of which the program for the PLC, is developed. The technical implementation of the ACS was carried out, the necessary elements and devices were selected. The economic efficiency of the modernization carried out by the authors proved its expediency |
