The Process Optimization Of High-Speed Milling Of6005A Aluminum Alloy Carbody Structural Part

EMU Aluminum alloy car body is composed of the side wall, roof, body, chassis, floors and other large parts. CNC machining of large parts of the vehicle body is a key process in the body production line. Some problems are found in CNC milling the large parts of the EMU body. One is that cutting air path is longer and time wasting. Another is that the federate which is constant along most of the tool paths, for example, in the canned cycles of milling pockets, results in deterioration of the machining condition sespecially at vertical ribs and weld zones. Consequently small cutting depth must be selected, that results in more milling cycles and longer time. However, cutting deformation still happens sometimes at oblique ribs. So operators must manually adjust the feed rate at any time in order to avoid the occurrence of builtup edge (BUE) or edge breaking. This causes feedrate fluctuation and inaccurate, and program is lack of intelligent. Therefore, it is greater significant to research the machining technology of6005A aluminum body structure.A single factor experiment of milling aluminum structure with different cutting widths, feed rates and milling mode is conducted to measure milling force and observe the deformation of ribs. The influence of various factors on the cutting force is analyzed. Results are found that cutting force increases with the cutting width increases, and becomes constant after certain cutting width, and that cutting.force tends to rise with feed rate increase. But cutting width affects cutting force less than feed rate. Cutting force in the climb milling is bigger than in conventional milling. The rib deformation is resulted from cutting force direction instead of cutting force magnitude. When the direction of total milling force is approximately perpendicular to the direction of the oblique muscle, it is more likely to cause rib deformation.Optimization of machining process is achieved by analyzing the shortcomings of the existed machining process of car body structures. Simple bolt and pressing plate clamping mechanism is used in the fixtures of chassis, both the injury risk of operators and cost is reduced. The workpiece coordinate system of machining chassis is setup automatically by finding the center of standard metal rod to prevent the errors caused by human intervention, and machining efficiency is also improved. The machining program is optimized by applying end-to-end process route for machining C slot of floor structure to keep machining process from discontinuous. When machining pockets in the floor, big cutting depth in first path and small cutting depth in second path are selected to prevent from rib deformation and increase tool life. The automatic measurement procedures is used to dynamically compensate the. cutting depth in milling the windows and door sof side wall, both machining quality and efficiency are improved. NC machining simulation of the side wall of the body structure is also studied by using VERICUT software to prevent from tool interference and optimize tool path, machining cycle and machining efficiency are improved.