Study On Working Process Of Hydraulic Impacting Piling Hammer And Structure Analysis

Hydraulic hammer using hydraulic oil as medium to work is a kind of pile-driving machinery which drives precast pile into foundation soil with hydraulic energy. It has a series advantages during working such as low pollution, low librations, low noise, quiet building construction, and etc, therefore it has been applied extensively in infrastructure projects. Hammer, anvil and pile are acted upon by alternate impact forces during impact process, and interaction forces between various components are complicated. To analyze kinematics and dynamic properties of system, it is necessary to research work process. Besides, in the actual work the hammer continuously impacts anvil, and fatigue cracks are found on the surface of stress concentration of anvil. With the expansions of cracks, finally fatigue fracture stops the anvil from working normally. In this situation, the impact process was analyzed on the basis of studying the structure and composition, operation principle, structural characteristics of 800s hydraulic pile hammer. The impact force which anvil was subjected to during the impact process and motion laws of various components were obtained by establishing mechanical model and solving differential equation. With the impacts between hammer and anvil, anvil and pile as dependent variable and with the rigidity of hammer, the mass of hammer and the range of stroke as independent variable, their relationships were established. Then their curves were drawn using simulation software. Based on the theory of finite element and using professional finite element analyzing software, the finite element model of anvil was established and impact load was applied. Then the stress changes of anvil during impact process were imitated by solving. The variation laws of critical points stress of anvil were obtained, and research shows that stress concentration exists on the outside surface of anvil through hole and stress values are lager than yield limit. By optimizing shape, the stress values there were decreased significantly. The study provides references for product upgrade and the further development.