Analysis And Study On The Cutting Force And Vibration Characteristics In The Water Chamber Head Milling Process

With Chinese rapid economic development in recent years, the demand forenergy increased sharply, in order to alleviate the contradiction caused by energydemand growing, development and use of nuclear energy is one of the mainmeasures to solve the energy problem in our country. Nuclear island AP1000evaporator water chamber head is the third generation nuclear core components,which is also the most widely used in the world, with largest difficulty ofmanufacturing. As container of a loop of nuclear island in nuclear power station,Water chamber head part is a key component of steam generator (SG), becausethe molding forging technology cannot be achieved, so we have to forge anapproximate rectangular column, all finished by mechanical processing, the metalremoval rate reached to about70%. The milling processing is the mainprocessing method in machining head water chamber, the508III steel hascharacteristics of high strength, high hardness and high section shrinkage, underthe large feeding rate, back engagement of the cutting edge and cutting force, thespindle and cutting tool produce tremendous vibration under the limit overhungstate, severely reducing and affecting the production efficiency and the surfaceprocessing quality; the spindle is often in the critical state of overhang in millingprocess, under the common effects of increasing axial cutting depth and theextreme instantaneous cutting thickness, serious vibration and shock occur in themilling process, causing serious tool breakage in the machining process, whichseriously affects the machining quality and production efficiency of the part. Inorder to improve the producing efficiency in the actual machining process, andimprove the machining quality of parts and the tool life, it is necessary to conduct research on the cutting force analysis and the vibration characteristics in thewater chamber head milling.First of all, conduct modal analysis on the cutter and the spindle of waterchamber head milling machine, then analyze milling vibration characteristics,carry on three dimensional modeling for special machine (TK6920CNC floortype boring-milling machine) cutter (Φ200R8arc blade cutter) and spindlesystem, conduct finite element modality and simulation analysis; then carry onthe modal experiment on the production site, collect and deal with data, andconduct experimental modal analysis; through the comparison of experimentaldata and simulation modal analysis results, the modal parameters of the cutter andthe spindle are obtained, which lays the foundation for the study of millingvibration characteristics in the milling process.Secondly, conduct research on the vibration characteristics in milling waterchamber head; through the investigation and analysis, find the reason of vibrationin machining process, and analyze the machined surface quality briefly under thevariable overhang state, through measuring idling, idle combined with space andcutting vibration signal, carrying on the analysis, obtain that the vibration causedby alternating cutting force is the main component of systematic vibration, finally,analyze variable overhang and experimental vibration signals, then obtain theimpact of overhanging changes on the vibration, and find that the water chamberhead milling vibration is a complex coupling vibration.Thirdly, analyze the cutting force model in water chamber head processing,combined with earlier vibration characteristic analysis, carry on the modelanalysis aimed at the water chamber head milling system, through the analysis ofmilling cutter eccentricity run out model, slight deformation model of millingcutter and spindle system and the stiffness model of feeding system, so as to getthe actual cutting radius in the machining process, and then establish the cuttingforce model taking instantaneous cutting thickness, and finally through thenumerical simulation analysis of milling vibration based on cutting tool breakage,eventually obtain the relationship between extreme cutting force and nominalcutting force under extreme eccentricity run out.Finally, we has carried on simple analysis of technology optimization andvibration prevention in milling water chamber head, combined with the tool breakage and wear condition, analyze that the milling system in water chamberhead milling process has certain stability. Consider vibration characteristics ofwater chamber head milling and cutting force analysis, put forward a briefoptimization for milling system and process parameters, meanwhile, introducethe new tool selection and optimization strategy in the water chamber headmilling process specially, which provides certain theoretical basis and practicalbasis for complete solutions to address extreme cutting force and vibrationinfluence in water chamber head milling process.