高压冷却下PCBN刀具切削镍基高温合金切屑形成与折断机理
发布时间：2018-09-10 10:07
【摘要】：高温合金具有优良的高温强度、热稳定性和热疲劳性,在高温环境下具有屈服强度高、组织性能稳定等特点,被广泛应用于航空、航天等领域。但由于其导热性差、塑性韧性高、表面加工硬化严重及切屑不易折断等特性,使其切削加工性能较差,是一种典型的难加工材料。PCBN刀具是一种新型超硬刀具材料在高温合金加工方面具有较大优势,但PCBN刀具根据材料特性通常不设有断屑槽,故断屑困难,切削过程中切屑缠绕工件及刀具、不易折断,从而降低刀具寿命和已加工表面质量。高压冷却是金属高效切削加工中一种新型加工技术,可以有效改善断屑性能、提升断屑能力、提高刀具寿命和加工表面质量,故本文通过高压冷却下PCBN刀具切削镍基高温合金GH4169试验研究,对高压冷却下切屑卷曲折断机理进行研究,并对高压冷却切屑折断特性进行分析。首先,通过试验对切削力和切屑形态进行研究,以冷却液压力、切削参数、冷却条件为变量进行试验,对比分析不同切削参数、不同冷却条件和不同冷却液压力下的切削力和切屑形态,研究高压冷却对切削力的影响规律及其原因,同时分析切屑形态在高压冷却加工下的变化规律,对高压冷却下切屑卷曲折断变化规律进行分析。其次,分析镍基高温合金加工过程中切屑形成机理,研究锯齿形切屑形成过程。分析切屑受力情况,根据切削区域应力分布建立切屑卷曲半径预测模型,以最大应变理论为切屑折断判断依据,建立断屑模型。分析高压冷却条件下冷却液压力对高温合金切削加工中切屑所受弯矩影响规律,根据切屑弯矩变化规律进一步分析切屑卷曲半径变化情况和切屑所受应变变化规律,建立高压冷却下切屑卷曲半径模型和断屑模型。然后对切屑微观形态进行研究,具体分析镍基高温合金锯齿形切屑锯齿化表征,分析高压冷却下锯齿微观形态变化规律,并对理论分析进行验证。最后,建立常规冷却及高压冷却下PCBN刀具切削镍基高温合金的有限元仿真模型,仿真分析锯齿形切屑形成过程,分析不同切削参数、不同冷却条件及不同冷却液压力对切屑形态及切削力的影响规律,同时对高压冷却条件下切屑卷曲折断进行仿真分析,研究切屑卷曲半径随冷却液压力变化情况,根据仿真结果对理论分析结果进行验证,并为后续高压冷却加工研究提供理论依据。
[Abstract]:Superalloys are widely used in Aeronautics and Astronautics because of their excellent high temperature strength, thermal stability and thermal fatigue, high yield strength and stable microstructure at high temperature. However, due to their poor thermal conductivity, high plasticity and toughness, severe surface hardening and the fact that the chips are not easy to break, the machinability of superalloys is improved. PCBN cutter is a new type of superhard cutting tool material which has great advantages in superalloy processing. But PCBN cutter usually has no chip breaking groove according to material characteristics, so chip breaking is difficult. It is not easy to break chip winding workpiece and cutter in cutting process, thus reducing tool life and machined table. Surface quality. High-pressure cooling is a new machining technology in high-efficiency metal cutting, which can effectively improve chip breaking performance, enhance chip breaking ability, improve tool life and surface quality. Therefore, this paper studies the chip crimping mechanism of nickel-base superalloy GH4169 with PCBN tool under high-pressure cooling. Firstly, the cutting force and chip morphology are studied by experiments, and the cutting force and chip morphology under different cutting parameters, cooling conditions and cooling conditions are tested. The cutting force and chip morphology under different cutting parameters, cooling conditions and cooling hydraulic pressure are compared and analyzed. The influence of cooling on cutting force and its causes are analyzed. The variation of chip morphology under high pressure cooling is analyzed. The variation of chip crimping and breaking under high pressure cooling is analyzed. Secondly, the chip formation mechanism during the processing of nickel-base superalloy is analyzed, and the formation process of serrated chip is studied. According to the stress distribution in the cutting area, the prediction model of chip crimping radius is established, and the chip breaking model is established on the basis of the maximum strain theory. The chip curl radius model and chip breaking model were established according to the variation of chip strain and the variation of chip curl radius. Then the chip micro-morphology was studied. The serrated chip of nickel-base superalloy was analyzed in detail. The serrated micro-morphology of nickel-base superalloy under high pressure cooling was analyzed and the theoretical analysis was verified. The finite element simulation model of nickel-base superalloy cutting with PCBN tool under conventional cooling and high pressure cooling was established. The forming process of serrated chip was simulated and analyzed. The effects of different cutting parameters, cooling conditions and cooling hydraulic pressure on chip morphology and cutting force were analyzed. The variation of chip curl radius with cooling hydraulic pressure is studied by simulation analysis. The theoretical analysis results are verified by simulation results, and the theoretical basis is provided for the follow-up study of high pressure cooling process.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG506.7
本文编号：2234139
[Abstract]:Superalloys are widely used in Aeronautics and Astronautics because of their excellent high temperature strength, thermal stability and thermal fatigue, high yield strength and stable microstructure at high temperature. However, due to their poor thermal conductivity, high plasticity and toughness, severe surface hardening and the fact that the chips are not easy to break, the machinability of superalloys is improved. PCBN cutter is a new type of superhard cutting tool material which has great advantages in superalloy processing. But PCBN cutter usually has no chip breaking groove according to material characteristics, so chip breaking is difficult. It is not easy to break chip winding workpiece and cutter in cutting process, thus reducing tool life and machined table. Surface quality. High-pressure cooling is a new machining technology in high-efficiency metal cutting, which can effectively improve chip breaking performance, enhance chip breaking ability, improve tool life and surface quality. Therefore, this paper studies the chip crimping mechanism of nickel-base superalloy GH4169 with PCBN tool under high-pressure cooling. Firstly, the cutting force and chip morphology are studied by experiments, and the cutting force and chip morphology under different cutting parameters, cooling conditions and cooling conditions are tested. The cutting force and chip morphology under different cutting parameters, cooling conditions and cooling hydraulic pressure are compared and analyzed. The influence of cooling on cutting force and its causes are analyzed. The variation of chip morphology under high pressure cooling is analyzed. The variation of chip crimping and breaking under high pressure cooling is analyzed. Secondly, the chip formation mechanism during the processing of nickel-base superalloy is analyzed, and the formation process of serrated chip is studied. According to the stress distribution in the cutting area, the prediction model of chip crimping radius is established, and the chip breaking model is established on the basis of the maximum strain theory. The chip curl radius model and chip breaking model were established according to the variation of chip strain and the variation of chip curl radius. Then the chip micro-morphology was studied. The serrated chip of nickel-base superalloy was analyzed in detail. The serrated micro-morphology of nickel-base superalloy under high pressure cooling was analyzed and the theoretical analysis was verified. The finite element simulation model of nickel-base superalloy cutting with PCBN tool under conventional cooling and high pressure cooling was established. The forming process of serrated chip was simulated and analyzed. The effects of different cutting parameters, cooling conditions and cooling hydraulic pressure on chip morphology and cutting force were analyzed. The variation of chip curl radius with cooling hydraulic pressure is studied by simulation analysis. The theoretical analysis results are verified by simulation results, and the theoretical basis is provided for the follow-up study of high pressure cooling process.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG506.7
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