The material removal process of a flexible workpiece has a great effect on the stability limits and chatter-free machining time, as the sequence of material removal can be altered to obtain a better workpiece dynamic behaviour. Therefore, the uncut material can be better designed to get chatter-free machining conditions and a shorter machining time. With this as the objective, a material removal process optimization method is presented to design the uncut material distribution. Different from existing methods, the presented approach begins from the last machining step, the maximum stable cutting depth is calculated, and the removed material is virtually added to the design model. Therefore, beginning from the design part, the material is virtually added to the part and the stock model of the part is finally obtained. Based on this approach, the optimized uncut material can provide support for the part in the semi-finish or finish machining processes, and the machining process is stable. Optimization results show that while machining plate-like structures, step removal methods can be used and the arc or triangle shape machining allowance can be used to get better machining results. Cutting experiments were carried out to show the effectiveness of the presented approaches.
A novel scroll type multiphase pump was proposed to transport gas-liquid two-phase mixture. There is a pressure unloading gap from compression chambers to the discharge port by constructing scroll wrap profile with variational meshing clearance in this scroll multiphase pump. In the working process when the volume of working chamber decreases, the pressure of gas-liquid mixtures increases gradually, at the same time small amounts of gas-liquid mixture are pushed to the discharge port from compression chambers through the pressure unloading gap. Therefore, this multiphase pump has an advantage of unloading pressure method automatically, and the frequently problem of liquid impacting in volume multiphase pump is solved. The safety and reliability of volumetric multiphase pump are improved, and the scope of multiphase pump of the gas-liquid ratio is expanded. The working process and the performance characteristics of scroll multiphase pump were analyzed too, and the generation method of scroll wrap profile with variational meshing clearance was investigated. The equations of the profile were obtained, and the changing principle of the working volume and the meshing clearance were analyzed. The geometric theory of scroll multiphase pump was formed. All of that lay the theoretical foundation for engineering design of this novel scroll.
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