Basic Research On Bending Springback And Control Of High Strength Steel Polygon Structural Parts

To stand a heavy load, the large auto parts are often made of those steel with highstrength.It has high quantity of bending springback for the reason of high strength.Thepolygon structual parts need to forming several angle,not only with high quantity ofbending springback,but also for different angles have different quantity of springback.Theauto structual parts should be not only of good quality in absorbing energy,but alsocompatible with other parts. The shape and position tolerance of every part is required tobe high since it have a great influence on the auto as a whole. The automobile crane armtrough plate is a very typical polygon structural part.Arm is one of the core parts of automobile crane. Its forming method is bendingforming, belonging to plastic forming. It is ofen made of steel sheet with high stength, suchas HG60and HG70with high quantity of bending springback and long bending line. Inaddition, the special telescopic jib structure of automobile crane puts high requirment onthe forming precision, which adds the difficulty of the forming craft of arm.It is a hardwork to predict accurately the quantity of bending springback of those steel sheet in nearly10meters and ensure a good straightness and identification of angle.The essay focuses on the polygon structural parts like the automobile crane armtrough plate by theoretical analysis, FEM simulation and physics experiments.Theflollowing are main contents：（1）Summaring the formulas of bending stress, strain and bending moment and thequantity of springback by theoretical analysis of bending forming process.Introducing theparameter set for improving precision of simulation for springback.（2）The basic performance parameters of china-made welded steel HG60wasmeasured through the tensile test.Laying the foundation of FEM simulation and its otherforming performance.（3）The influence factors of whole stamping springback of polygon structural partswere studied through FEM simulation.It has important reference value for springbackcontrol of whole stamping of polygon structural parts.（4）The best optimal parameter combination of the control point of springback andimmunity direction height discrepency were got through the orthogonal experiment of along curved line shape V shoulder bending. And the influence factors were sequencedaccording to the degree of their influence on evaluation index.It has important instruction meaning for springback control of multi-step bending forming.（5）Taking the crane arm trough plate as the research object, a FEM simulation wasdone by multi-step bending forming method. And the predicting result was got which waslargely in accordance with the result of the cooresponding physics experiment and whichwas of great reference value to the bending forming of arm trough plate. Then put forwardto bad straightness of the arm trough plate in real production and “saddle” warping. And thesolution standed the practice examination.The aboving research results have very import academic significance and engineeringapplication value of bending forming technology and springback control of polygonstructual parts.