Dynamic Analysis And Experimental Study Of Pumping Pressure Of Concrete Pump Truck

Concrete pump trucks are widely used in construction construction,railway construction,and national defense construction and construction projects that require pumping concrete.During the construction of the concrete pump truck,the boom and the underframe usually generate vibration.Since the pumping system alternately pumps the concrete into the concrete conveying pipe,the flow of the concrete in the pipeline is unsteady,and the material is fed.The tube and the boom are connected together by the support,so it is important to study the unsteady flow of concrete in the pipeline and calculate the pumping load pressure dynamic load at the concrete pump cylinder outlet to analyze the force and vibration of the boom and the underframe.At present,the pumping pressure is usually only concerned about the pressure loss at home and abroad.Some scholars have studied the hydraulic shock of the main oil pump caused by the commutation of the pumping system through the hydraulic system simulation modeling method.At this time,the pumping load pressure does not change drastically.It is caused by the concrete pulsating flow,and the dynamic change of the main oil pump outlet pressure at this time will not reflect the dynamic characteristics of the pumping load pressure.This paper starts from the pumped load concrete pipeline flow itself,based on the rheological characteristics of concrete and the pumping principle of concrete pump truck,the equation of motion and velocity model of concrete flowing in the pipeline are established.The pumping load pressure dynamic load of concrete outlet is solved.The calculation formula,and the correctness of the model is verified by numerical simulation and experimental methods,and the input dynamic load is provided for the subsequent vibration research of the pump boom,the underframe and the whole vehicle.The specific research contents are as follows:(1)Based on the rheological principle of concrete,the flow state of concrete in one-dimensional pipeline flow is analyzed,and the equation of motion of concrete flowing in straight pipe,cone pipe and elbow is established.The work of pumping system of concrete pump truck is analyzed.Based on the principle,a velocity model characterized by Fourier series is established,and the calculation formula of the pressure dynamics of concrete at the inlet of three pipes is obtained by solving the equation of motion.(2)Combining the research methods of pressure loss calculation in cone and tube,the cone and tube are equivalent to a length of straight pipe to calculate the pressure loss and dynamic change,by combining straight pipe,elbow and cone The pressure loss dynamic load calculation formula establishes a calculation model of the pumping load pressure dynamic load.(3)Based on the fluent fluid calculation and analysis software,the flow of concrete in straight pipe,cone pipe and elbow is analyzed and calculated,and the distribution and change of flow velocity and pressure of concrete in three pipes under steady flow are obtained,which is unsteady.The dynamic curves of the three inlet pressures of the pipelines obtained by inputting the velocity model established in Chapter 2 under flow test verify that the pressure loss dynamic load when the concrete flows in the cone and elbow is converted into the pressure of the equivalent length straight pipe.Reasonableness of loss dynamic load calculation.(4)Through the concrete slump test and the measurement experiment of the main oil pump pressure when pumping concrete,combined with the working principle of the pumping system,the equation of motion of the two cylinder pistons is established,and the linearity between the main oil pump pressure and the pumping load pressure is obtained.The relationship between the main oil pump pressure curve and the actual load pressure curve was calculated and compared with the calculated pump load pressure dynamic load calculation model.The correctness of the pumping load pressure model was verified.