Mechanical analysis on the cylinder-crown integrated hydraulic press with a hemispherical cylinder

As a new press, cylinder-crown integrated hydraulic press (CCIHP) is analyzed firstly in this paper. The hydraulic cylinder consists of a hemispherical shell, which also functions as a main proportion of press crown. Compared with the conventional hydraulic press which has a hydraulic cylinder mounted in the press crown, the structure and force distribution of CCIHP are significantly different. First, the section modulus of the hemispherical crown is much larger than that of the conventional rectangle crown because the hydraulic cylinder and press crown are manufactured into a solid part and have a higher geometry centroid. Therefore, the hemispherical crown has lower tensile bending stress and a higher safety factor from the strength point of view when the same bending moment is applied. Second, under the conditions of same value in terms of the allowable stress, internal pressure and internal radius, the wall thickness of hemispherical hydraulic cylinder could be much thinner than that of the conventional hydraulic cylinder. Both of the reasons mentioned above can result in a weight reduction of the press. Also, the cylinder and the press crown can be reinforced by each another, as a result, the material strength capacity is better utilized. As a prototype, the 6300 kN CCIHP with hemispherical hydraulic cylinder, which is the first one of this kind press designed and manufactured by Harbin Institute of Technology (HIT) is introduced in this paper. Finite element analysis for CCIHP has shown that both the stress and displacements on the press during the loading process are allowable, even if eccentric force is loaded. Finally the priority application range of CCIHP has also been proposed.