Rod Preload Mechanical Modeling Of The Structure With Eight Million Tons Of Press Optimization Of The Beam Structure

Heavy die forging hydraulic press is the one whose tonnage exceeds 100MN and which is used to forge overall workpiece. The design and production capacity of heavy die forging press, and the number and level of this type of press possessing, is one of important symbols of comprehensive productivity and technical level of defense industry and machinery manufacturing industry of a country, having specific strategic significance. Whichever developed countries or developing countries in the world pay attention to the development of heavy die forging press. The dissertation, by means of theoretic analysis, numerical simulation, optimization and tests, studies systemically on many key issues such as modeling approach, integrity and stress distribution, etc. of the composite bearing structure, such as up beam, moving beam and fixed press bed of 800MN heavy die forging press developed by China.The modeling approach of composite bearing structure preloaded with a group of tie-rods, based on the theory of 3-D FEM elastic contact, is studied. Some methods of prestressing tie-rod, in the simulated environment, are researched into, and the effects of different methods of prestressing tie-rod, under prestressing and loading, are contrastively analyzed. According to result, methods of prestressing tie-rod suitable to corresponding work-state and the program of optimizing preload of groups of tie-rod, are put forward.The integrity of moving beam is analyzed with FEM, and a viewpoint that its integrity is mainly incarnated by the gaping between two centre beams. Also the effects of the structure parameters of the number of tie-rod, the shape of center beam, the position of taper key, as well as of the force-energy parameters such as pre-tight force of tie-rod, load, on the integrity of moving beam are studied systemically. Based on above studies, some ways of improvement for perfecting the designing of moving beam of the 800MN heavy die forging press are put forward, and then the final designing scheme of moving beam is investigated. As it turned out, the final scheme is markedly superior to original scheme: the maximum of gape falls from 0.36mm to 0.097mm, the drop is 24.9 percent.Stress distribution of every part of three beams of the press is investigated in this dissertation. The cause of stress concentration in the poke-hole of center beam of fixed press bed is studied, and some methods, such as changing shape of region existing stress concentration, removing material and adding technological hole, to decrease the stress concentration factor, are proposed. Through detailed analysis, the optimized design proposal of centre beam structure of fixed press bed is put forward. Analysis shows that the new structure of centre beam gains ascendancy over the old one: the maximal principal stress of its ejection-hole falls from 161.4MPa to 84.37MPa and the stress concentration factor falls from 2.405 to 1.33.During the research, a metal model in the proportion of 1:11.1for the 800MN heavy die forging press is used. Measurements and tests about stress and deformation of key beams of this machine under prestressing and loading are conducted. The results indicate that the stress and displacement of parts of three beams obtained from experiments well coincide with that from calculation.