| Currently, the inner cooling machining in high-speed has become the development trend of high-end production lines. The tool cutting fluid mixing zone field in high speed wet milling is very complex, which needs to be studied. The tool rotate in high speed,while cutting fluid is ejected from the inner cooling holes with chips cutting from the tip position from the workpiece. After the cooling holes injected coolant impingement bottom of the hole, which is partially offset by a rebound reflux energy. Swarf particles which are moved out of the cutting area in part of the energy of the coolant and tool rotary joint action, striking surface of the tool and the workpiece. Chip particles impacts and erosion of the cutting fluid will affect to the quality of the workpiece in some extent, exacerbating tool breakage, reducing tool life. At present, the tool flow field research mainly about the following aspects: rotary cutter driven by ambient air flow field, side milling process and flow field around the tool and freely within the flow of the cold tool. Research are relatively simple, the tool failed to rotate within the cooling holes cutting fluid injection into account together. In this paper, Carbide end mills cold cutting process for the study,based on the finite element theory and computational fluid dynamics, combining with helical milling hole experiment, creating mixed fluid field model in high-speed wet milling cutting zone. Comparative experiments with the simulation results analysis and discuss tool breakage mechanism under mixing flow field.First, create a different end mill geometry within the cooling holes. According to the actual milling situation, establish high-speed wet milling cutting zone with mixed fluid field model, extracte the flow channel and set the surface of the tool as moving wall. Using the sliding mesh model simulate the rotating flow field and the discrete phase model for DPM chip particle trajectory simulation, which indicated that the chip, the tool surface and the workpiece often crash.Secondly, simulate the cutting zone mixed fluid field with the help of Fluent. During milling, the flow field enclosed space which is made by cutting edges and the milling cell walls is inconsistency, all cutting edge of the flow field are different. Chip cut from the edge position of the workpiece, with repeated rebound between the flank and the workpiece surface, which is bring out of the cutting area by cutting fluid. Flow field is different with different fluid medium, the tool speed, injection pressure, the cooling holesof different diameters.Again, single factor experiment of high-speed spiral wet milling hole is carried out.Workpiece surface quality was measured and studied after the experiment, getting the various milling parameters on the surface quality. The double helix within the cooling hole machining quality is better than double straight cooling holes. The tool speed to 12000 r /min, milling flow field changes. Flow field space, the milling time also have some impact on the distribution of the flow field.Finally, using Hitachi S-4800 scanning electron microscope for micro damage morphology observation of the end mills surface in the milling experiment and analysis the tool breakage mechanism. By comparative analysis between the resulting image of simulation and the tool breakage microscopic morphology to verify the impact on the flow field of tool breakage.Cutting zone flow field modeling and runner extraction, using the DPM model simulated particle trajectory. On one hand, the influence of flow field on the cutter and workpiece surface quality is got, providing theoretical support on the influence of the flow field on tool life; on the other hand, cutting area mixed fluid field characteristics to further enrich the rotating jet theory. |
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