Experimental Research On Dry Cutting/a Little Quantity Lubricant Cutting Of Aluminum Alloy And Process Fuzzy Monitoring

Due to the increased awareness of environmental protection and sustainable development, greenmanufacturing has been becoming an important feature and a basic production style in modernmanufacturing industry. In order to improve productivity, workpiece quality and to prolong tool life, alarge quantity of cutting fluid is used in metal cutting process. However, extensive use of cutting fluidwill cause serious negative impact on human health and the environment, and the costs of cutting fluidare heavy. From the aspects of human health, the environment, and economics, it’s necessary todecrease the use of cutting fluid as much as possible in metal cutting process.Dry cutting and LQL (A Little Quantity Lubricant) cutting of aluminum alloy are researched inthis paper, supported by the National Natural Science Foundation of China (50875120). Mechanism ofdry cutting and LQL cutting is studied. Compared with previous studies, the characteristic of this paperis that the research of dry cutting and LQL cutting is conducted in a more abstract level through theanalysis of vibration signals and AE (Acoustic Emission) signals. An experimental research isconducted in order to understand the effects of LQL on machining. In addition, in order to providecutting fluid adaptively in metal machining process, the feasibility of cutting temperature control basedon cutting fluid is discussed, and an experimental validation is conducted. The main achivements in thedissertation are summarized as follows:(1) The thermal mechanism of dry cutting and LQL cutting is discussed by applying heat trasfertheory. Cooling mechanism is revealed by applying convective heat transfer boundary layer theory ofPrandtl. The improvement of tool-chip friction model which is suggested by Zorev is conducted inorder to give a more reasonable explanation to the friction behavior between the tool and chip underlubricant condition in machining process, the formula of minimum cutting fluid flow rate when thecooling capacity is the maximm is derived out under the heat transfer condition of liquid forcedconvection. The cutting heat transfer mechanism is researched on dry cutting and LQLcutting from theaspect of heat transfer process. The effect of cutting fluid applying direction and heat trasferparameters on cutting heat trasfer process is researched through heat trasfer model of cutting fluid.(2) A signal acquisition platform is established based on virtual instrument platform. Thevibration signals and AE signals are sampled in milling process of aluminum alloy7050-T7451. Thecharacteristics of signals in dry cutting are researched through the methods of time domain and energydistribution under different process conditions. In time domain, the relationship between process parameters and RMS (Root Mean Square) values is obtained in milling process. By means of waveletpacket decomposition, the energy distribution in different frequency bands of vibration signals and AEsignals in dry milling process is analyzed under different process conditions, revealing the law ofenergy distribution in different frequency bands for different cutting speed, feed per tooth, and cuttingwidth.(3) In order to conduct an experimental research on LQL, a signal acquisition platform isestablished based on virtual instrument platform. A cutting fluid supply system for LQL is built basedon VC6.0. The effects on cutting process of cutting fluid flow rate in LQL milling process foraluminum alloy7050-T7451are researched through the analysis of vibration and AE signals in timedomain, frequency domain, time-frequency domain, and energy distribution in different frequencybands based on wavelet packet decomposition. The characteristics of effects of cutting fluid flow rateto vibration and AE signals are concluded through RMS value, frequency distribution, and energydistribution.(4) Based on the tests of milling of aluminum alloy7050-T7451and tool steel, the comparativeresearch of machining effects of dry cutting and LQL cutting under different cutting fluid flow rate isconducted from aspects of workpiece quality, tool, and chips. The research reveals the advantage ofLQL in metal machining process.(5) By applying fuzzy control theory, a cutting temperature control system for aluminum alloy7050-T7451milling process is established based on LQL in order to decrease the use of cutting fluidwhile assuring the quality of cutting process. A practicability study is conducted. Simulation andexperiment show that the proposed control system can conduct an effective control of cuttingtemperature, and has high control accuracy. The effectiveness of cutting temperature control based oncutting fluid on improving machining quality and decreasing the use of cutting fluid is verified throughmachining experiment.The promising achivements of this dissertation enrich green cutting theory and give a helpfulguide to the application of dry cutting and LQL cutting.