Design And Research Of Four-degree-of-freedom Loading Device

Cement is an important infrastructure raw material and plays an extremely important role in the construction of various national infrastructures.Nowadays,the demand for cement production is increasing,and the traditional manual loading method can no longer meet the demand for bagged cement packaging into trucks.In order to adapt to the trend of national promotion of manufacturing industry upgrading,and to improve the intelligence and greening of the manufacturing industry,and to improve the efficiency of cement loading,the research and development of cement automatic loading machine has become an inevitable trend.The most important technical index of automatic loading machine is loading speed,this article proposes a single vehicle(AGV Vehicle,that is,four-degree-of-freedom loading device)double-pack automatic loader overall design scheme,the single vehicle makes the overall structure of the automatic loader simple,and the double-package package scheme improves the loading speed.In addition,in view of the complex loading environment such as the complex models of domestic transportation vehicles and the diversification of the external dimensions of bagged cement bales,in order to ensure the highly adaptable loading requirements between the external dimensions of bagged cement bales of any specification and any model,this paper proposes a "stacked bag fill-in-the-blank" stack package scheme to solve the problem of highly adaptable loading stack package.According to the innovative design ideas of the two key technologies of the overall design scheme of "single vehicle double package" and the "stacked bag fill-in-theblank" stack packaging vehicle scheme,the paper focuses on the design of the core device in the automatic loader to realize these two innovative design ideas-the fourdegree-of-freedom loading device,and completes the structural design of the fourdegree-of-freedom bag dropping device by modular design method,and carries out the kinematics and dynamics theoretical analysis and simulation optimization analysis of its key modules.First of all,the overall scheme design of bagged cement automatic loading machine was carried out.In view of the complexity of the domestic bagged cement loading environment,in order to ensure the high-speed loading speed and the adaptability of dense stack bags between any cement package and any compartment space,two innovative design schemes of "single vehicle double package" overall structure mode and "stacked bag fill-in-the-blank" stack bags and packaging into truck are proposed.A four-degree-of-freedom AGV vehicle(four-degree-of-freedom loading device)is adopted,and two packages of cement are transported into the carriage each time,and the round-trip cycle of the AGV vehicle is lengthened each time by stacking two bags,and the operating indicators and difficulty of the mechanism design are reduced to the feasible range.Only two packs of cement are stacked each time,and it is easy to realize the stacking mode stack package when the two stacks are adjacent to each other,and the volume of the two packs of cement is still very small relative to the cabin space,and the pits generated after stacking the bags are easy to be filled with fillin-the-blank stacking bags.This innovative design scheme solves the complex system problem of the current mainstream multi-stack package mechanism to improve the loading speed,and solves the adaptability problem of highly dense stack packaging vehicles with complex domestic models,and makes the productized design of automatic loading device possible.Secondly,according to the design idea proposed by the overall scheme,the overall design of the core device is completed(the four-degree-of-freedom loading device)to realize its function.The four-degree-of-freedom loading device is composed of four main functional modules:the positioning and moving mechanism for bag positioning along the width direction of the carriage,the lifting and moving mechanism for adjusting the height of cement bag,the ± 90° rotating mechanism for the conversion of horizontal and vertical attitude of the cement bags,and the control mechanism for bag dropping that finally puts the two bags of cement from the AGV Vehicle into the carriage.Using the modular design method,each functional module has an independent single degree of freedom,which is convenient for individual commissioning,upgrading and maintenance.The dead center technology in the plane linkage,which ensures the reliability of the mechanism,is used to design the control mechanism for bag dropping that bears strong impact.The ± 90° rotating mechanism is installed inside the lifting and moving mechanism,so that the whole mechanism is compact and the AGV Vehicle has the smaller external dimensions.The thesis completed the design of the four-degreeof-freedom loading device.Then,the kinematic and dynamic analysis studies of the most important the positioning and moving mechanism for dropping bags in the four-degree-of-freedom loading device are studied.The working conditions of the positioning and moving mechanism were analyzed,the motion process of the bags positioning stage and return stage were analyzed,the change of the center of gravity of the mechanism during the movement process was calculated,the bending moment and shear force of the steel beam bearing the main load were calculated,and the dangerous section and deformation are analyzed.The stiffness and strength of the static structure before the cement bags enter are verified.Based on the nonlinear problem of impact of cement package and the large model of the positioning and moving mechanism,the full method and the modesuperposition method were used to analyze impact force of cement bag and the impact response of the positioning and moving mechanism,which simplified the model and reduced the calculation difficulty.Through Ansys finite element simulation,the stress,deformation and vibration were numerically solved,which verified the rationality of the initial design and proposed further optimization measures.Furthermore,the fatigue life of the mechanism under random vibration was simulated using the power spectral density analysis method.Finally,the reliability of the control mechanism for bag dropping under strong impact load is studied,the kinematics and dynamics of the pack feeding and dropping processes are analyzed,and the relevant structural optimization design is carried out.By analyzing the motion and force of the falling bag,the kinematics model of the falling of the cement clad is established,and it is verified that the actual drop time is less than the design drop time of the running sequence,and the loading speed is guaranteed.The trajectory planning of the pulling back of the drop board was carried out,the kinematics model was determined,the motion model of piston rod was obtained by kinematic inverse solution,and the cylinder tension was determined by dynamic analysis,which verified the feasibility of the motion trajectory.The contact constraint method was used to analyze the contact and collision process between cement bag and drop board,and to solve the nonlinear problem of collision of flexible cement packages.Using ANSYS/LS-DYNA,the stress changes in the drop board under impact loads were simulated.In order to explore the unclear relationship between the structural parameters of the drop board,local stress and mass,the response surface design method is used to establish the relevant functional relationship,and the implicit relationship is transformed into an explicit model.In order to optimize strength and quality at the same time,and to avoid the mutual constraints of targets during optimization,and to obtain multiple optimal structural parameters,the optimal solution is obtained by using multiobjective algorithm,and the structure optimization of the drop board is realized.