Research On Numerical Control Technology Of Precast Concrete Distributing Machine

Prefabricated buildings are mainly composed of prefabricated components.The advantages of this kind of building are fast construction speed,little restriction by climatic conditions,reducing the dependence of traditional construction industry on labor,and promoting the sustainable development of construction industry.Prefabricated concrete distributing machine is the key equipment for concrete pouring in the production line of prefabricated components,and its distributing method greatly affects the quality of prefabricated components.In recent years,with the continuous development of prefabricated buildings,the requirements for prefabricated components have also gradually increased.However,the production line of prefabricated components is complicated and has many work stations.Currently,the distribution process is mostly in the form of manual input of distribution areas.However,due to the instability of manual operation,the amount of materials dropped during the distribution process is directly unstable.The produced prefabricated concrete components cannot be standardized and can't meet the market demand.The traditional concrete distribution method needs to be improved.On the basis of a comprehensive inspection of the prefabricated component production line,this paper compares the new automatic production process with the traditional process,optimizes the distribution mode of the original prefabricated concrete distributor,and adopts the digital control mode for the distribution system and walking system.In order to realize accurate distribution of the distribution system of the precast concrete distributor,firstly,the prefabricated components to be poured are " meshed",and eight distribution openings of the distributor are respectively provided with a thickness detection device for measuring the thickness of the prefabricated components in each " grid".The thickness detection device transmits the measured distance to a central controller(PLC S7-200),the interface mode is RS-485,and the data transmission protocol is Modbus-RTU.The central controller(PLC)calculates the amount of concrete to be poured in each " grid" according to the measured thickness information,and controls the motor to adjust the rotating speed of the screw conveyor at each distributing opening,so that the " grids" with different capacities finish the pouring task in the same time.When the walking system is positioned,the method of combining laser ranging and encoder is adopted.The encoder mainly calculates the path traveled by the distributing machine by calculating the number of turns of the wheels of the distributing machine.In order to prevent the wheels from slipping when walking on the cloth,the laser ranging device detects the position of the distributing machine every 5 s.If there is an error with the distance measured by the encoder,the distributing machine slips when walking and corrects the encoder.The brake system model of the distributor is established by Simulink software,and the influence of PID controller on the brake distance and brake slip ratio of the distributor is simulated.The positioning device has been tested in a prefabricated component factory.The combination of encoder and laser rangefinder can effectively reduce the walking error of the material distributor and improve the positioning accuracy.