Study On Water Forced Extrusion Abrasive Waterjet Mechanism And Equipment

The disasters and accidents caused by natural force or mankind have become a worldwide concern. To rescue the survivors after the disasters and accidents, there is a need for a kind of water forced extrusion equipment that is efficient to penetrate various kinds of materials, like steel, concrete and rocks, without disturbing the rubble piles. Supported by the innovative research group project named The study on mechanism of hard rock cutting with high pressure water jet and application of high pressure water jet on underground engineering which is issued by NSFC (No:50621403)and international joint PhD education scholarship issued by China Scholarship Council (No:2008605038), the study on water forced extrusion abrasive waterjet mechanism and equipment is proposed in this thesis. Based on the traditional abrasive waterjet technology, a new water forced extrusion abrasive waterjet technology and system design is brought forward, followed by the study of the new water forced extrusion abrasive feeding mechanism, experimental research on abrasive waterjet nozzle wear mechanism and the manufacture and laboratorial evaluation of one new water forced extrusion abrasive waterjet penetrating equipment.The literature survey about conclusion and mechanism of waterjet and abrasive water jet technology is carried out, also the paperwork investigation about features of rescue operation after the disasters and accidents. By summing up the survey result, the basic technical features of the water forced extrusion abrasive waterjet penetrating mechanism and equipment are obtained, which are: 1) the small figure of the equipment; 2) the easy-operation of the equipment; 3) the anti-dust ability of the equipment. The new water forced extrusion abrasive waterjet technology and system design is brought forward according to the three features. The transient analysis is applied in the study to simulate and analysis the new system. According to the result, the flow rate and pressure contribution in the system is the function of density and elastic factor of fluid and the section area of pipelines.A new type of abrasive feeding cell is applied by new water forced extrusion abrasive waterjet mechanism and system. The turbulence flow dynamic and micro-vortex theories are introduced to analysis the abrasive mixing mechanism of the abrasive feeding cell. According to the study, flow dynamic is the main driving force of abrasive mixing, and the collision among the abrasive particles caused by micro-vortex is the main factor related to the abrasive mixing efficiency. The concept of adding long-chain polymer into abrasive before mixing procedure is adopted by the study, followed by the accordingly experimental research on this issue. The results show that the long-chain polymer improves the fluidity of abrasive and prevents the collision among the abrasive particles and abrasive mixing efficiency. Xanthan is found a preferable long-chain polymer for the water forced extrusion abrasive waterjet technology and system.The experimental research on abrasive waterjet nozzle wear mechanism is carried out in the study, in which garnet and steel grid abrasive is used to test a new kind of diamond coated split carbide nozzles. The nozzles are split along axis and coated by nano-crystalline diamond before use. Serial photos are taken to show the nozzleBased on the academic studies, new water forced extrusion abrasive waterjet penetrating equipment is designed. The design works embodied the three technical features of the water forced extrusion abrasive waterjet penetrating mechanism and equipment. The laboratorial evaluation of the equipment is put forward and affirms the feasibility of the mechanism and equipment.At the end of the thesis, the conclusion of the study and the advice for the further studies are proposed. The study achieves both the miniaturization and simplification of abrasive waterjet mechanism, which broadens the application of the mechanism, and provides a new solution of rescue after disasters and accidents.