Research On Spinning Forming Mechanism And Contorl Optimization Of The Grid Rib Cylindrical Parts

Spinning forming technology as one of the best forming methods for metal cylindrical part is widely used in industries as aviation,aerospace,weapons and civilian automobiles.With the increasing requirement of military industry and the civil transportation industry on lightweight and toughened metal cylindrical parts,the demand for structural improvement and manufacturing process improvement of related parts has become increasingly strong.Compared with equal-wall-thickness shell parts,the work-piece with inner reinforcing ribs can effectively reduce its own weight while ensuring the strength of the parts,and the corresponding lightweight advantage is more obvious for complex internal rib structure with grid-like reinforcement ribs.In this thesis,the spinning forming technology of complex inner rib shell parts is the research topic,the inner shell part with reinforcing rib is research object.Based on theory of metal plastic forming and strong spinning forming,the thesis adopts method of combining numerical simulation and experimental verification,carrying out researches from the direction of spinning forming mechanism,control and optimization of spinning process parameters,optimization design and manufacture of supporting tooling molds and spinning forming test of grid rib parts.For the problem of determining the combination of optimal process parameters under the condition of multiple evaluation indexes,uses the combining analysis method of orthogonal test optimization design and gray correlation.For the difficulty of unloading due to the existence of ring inner rib parts after spinning,designs dedicated seven-part core mold.At last,uses the spinning process to complete the processing of shell parts with inner ribs,which provides a new option for the processing of such kind of inner rib shell parts.The main research contents of this thesis are summarized as follows:Research on spinning plasticity theory and simulation mathematical principles of grid rib cylindrical parts.Based on the traditional metal plastic deformation theory,the concepts of crystal slip and dislocation,combining with the metal flow characteristics of grid bar spinning forming to analyze the corresponding forming mechanism.On the basis of establishment of the grid rib metal flow model,metal flowing discipline is analyzed by metal particle velocity;Uneven change degree of different wall thickness layers is summarized according to the distribution of stress and strain;The calculation method of the spinning force of grid rib parts is analyzed and the corresponding calculation formula is given to provide theoretical support for the subsequent spinning force calculation.This thesis briefly analyzes the mathematical theoretical foundation of the grid rib parts simulation modeling and the corresponding solver selection principles,which lays the foundation for the subsequent simulation test data analysis.Simulation analysis on spinning forming of grid rid cylindrical parts.Take the technical parameters of the grid rib cylindrical part as input,set the working angle of the spinning wheel,thinning rate of the blank and feeding speed of the spinning wheel as changing process parameters,spinning simulation model in ABAQUS software is established.25 sets of test parameter combinations are designed through orthogonal experiment in simulation test,stress cloud map,strain cloud map and forming effect of each set parameter models are used for judgment basis,the simulation test are performed respectively on grid-rib part quality inspection index as longitudinal inner rib,transverse internal rib and forming effect of inner wall ellipticity.According to simulation test result,the trend changes of each quality assessment index under different parameters are drawn for each process parameter,and the best process parameters under a single assessment index are analyzed and obtained.Spinning processing parameters control optimization of grid rib cylindrical parts.To insure the accuracy of the spinning process simulation parameters of the grid rib cylindrical parts,the range analysis of the orthogonal simulation experimental data of the grid rib parts is carried out.For the problem of different influence significance order of process parameters resulting in different optimal process combinations under different optimization objectives,the grey correlation analysis method is introduced to optimize the process parameters.By analyzing the simulation results of longitudinal rib height difference,transverse rib height difference and inner wall ellipticity,the influence order of each factor on the evaluation index is obtained.Then,by analyzing the multi-objective correlation degree of grid-rib parts with gray correlation analysis method,the optimal combination of multi-objective optimization process parameters is obtained,which provides the process data support for subsequent tests.Experimental study on spinning forming of grid rib cylindrical parts.According to process requirements of the grid-rib-part spinning test,the dedicated split core mold for the grid rib parts spinning is designed and manufactured.The split core mold has good rigidity and strength,meanwhile can achieve rapid split disassembly,so as to solve the unloading problem of the grid rib parts after spinning.With the support of dedicated mold,using the optimized process parameter combinations,the grid rib parts are spun at room temperature and heated temperature,finally,target-size grid rib parts with 2.5 mm and 4 mm inner rib height are successively obtained by heating spinning process.For the defects detected during the spinning process test,such as rib forming quality,forming height,shell-part forming accuracy and surface roughness,etc.,a detailed quality control analysis is performed,laws summarized,then corresponding solutions put forward.Dimension inspection and performance analysis of grid rib spinning shell parts.High-precision optical measurement experiment is carried out to verify the complex shape of the inner wall of the grid rib parts.The measured data verifies that the grid rib part has good accuracy,meanwhile,also proves that optical detection method can be applied to measuring the inner wall surface dimension of the grid rib.Based on this conclusion,the feasibility of the application of optical automatic measurement technology is preliminarily explored.Mechanical tensile test is conducted and microstructure metallography is observed on the spinning and post-annealing spinning samples of grid rib parts respectively,the experimental data proved that the material properties of the grid rib samples after spinning are greatly improved.