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With regard to the double hoisting gantry crane

visits:   time:2016/5/19 17:37:36

Establishment of finite element model of the crane. LME80T+80T Gantry crane is box girder structure, in actual work, main beam subjected to bend, tension and compression, shear load; steel leg subjected to bend, tension and compression; bottom beam subjected to tension and compression. So using Unit Shell 63 to simulate plate component of bending, tension and compression, shear. Modeling process: set up central plane of box girder structure in space , there are cut lines at connecting place of different sections. Set up coupling relationship at connecting place between soft leg and main beam, release rotational degree of freedom along crane moving direction; trolley indicated by concentrated mass unit. When the mesh, in addition to the main beam and leg joints manually division unit, the rest are free mesh. Treatment of boundary constraints. When the crane work, the hinge between the cart and the track, just the legs and soft-sided carts between the rails and legs bound three translational degrees of freedom, on the other side constraint two translational degrees of freedom, the release of carts along the running direction translational degrees of freedom.

Model in the process has been properly simplified, and the spacer ribs are not reflected in the model, so the model is less than the weight of the actual weight of the crane, the weight is increased to compensate for the acceleration of gravity, the gravitational acceleration g = 11.78m now / s2, the material density is δ = 7.85t / m3, modulus of elasticity E = 206GPa, Poisson's ratio μ = 0.3. Modal calculation and modal analysis method to extract the text selection BlockLanczos method, this method to calculate the precise, fast, works often use this method to extract modal. Gantry cranes span more than 30 meters, generally using just the legs and soft legs bound structure, the overall structure, the flexible high, so the higher modes is negligible, often use dynamic stiffness of the first few natural frequency evaluation crane structure . Into the ANSYS solver, modal analysis, the gantry crane 20 before order frequency. Order before gantry crane 20 from the frequency modal analysis results, the former sixth-order mode shapes are typical modes, the first mode reflects the vibration gantry crane trolley along the running direction of the vibration is mainly composed of a trolley system in this direction dynamic load caused by wind, second, third, fourth and fifth-order modes of vibration along the main beam reflected the transverse direction, the direction of vibration is mainly caused by wind load and hoist yaw; sixth vibration mode reflects the main beam vertical vibration direction of gravity, the direction of vibration is mainly caused by reciprocating movement of the weight and vibration of the direction of gravity of the car.

Analysis of structural rigidity and strength. Structural strength calculation. Combining these dual gantry crane lifting machine is mainly dangerous working conditions, the three conditions of the overall strength and rigidity to be checked. By deck crane Static Strength Finite Element calculation of three kinds of working conditions, the overall stress distribution, the maximum stress for local. Stiffness of the Structure Calculation. Three kinds of conditions, under the main beam of the order of about 69mm, 66mm and 68mm, under the weight of the beam generated by the primary winding is 18mm, the maximum main beam as a whole under control in about 38 500 / (69-18) = 755, to meet the Lord beam stiffness control requirements. Structural strength calculation. Three kinds of conditions, gantry cranes of the main interface of the maximum stress. The main components of the stress distribution (in Mpa) shows that the major cross-section crane girder can meet strength requirements. The emergence of the main beam maximum stress conditions a maximum stress conditions appear in the legs three main girder connections with just three kinds of conditions and soft leg leg stress concentration, after analysis, in compliance with the main beam leg the connection may be bolted in place due to the stress concentration hinge. The maximum stress occurs in two conditions, stress concentration is 252MP. Analysis calculated for LME80T + 80T gantry crane, the conclusions are as follows: yaw hoist, crane and trolley brake and wind loads is an important factor affecting gantry crane instability just legs and leg joints supple and the main beam stress is large.