【摘要】：高溫合金具有優(yōu)良的高溫強(qiáng)度、熱穩(wěn)定性和熱疲勞性,在高溫環(huán)境下具有屈服強(qiáng)度高、組織性能穩(wěn)定等特點(diǎn),被廣泛應(yīng)用于航空、航天等領(lǐng)域。但由于其導(dǎo)熱性差、塑性韌性高、表面加工硬化嚴(yán)重及切屑不易折斷等特性,使其切削加工性能較差,是一種典型的難加工材料。PCBN刀具是一種新型超硬刀具材料在高溫合金加工方面具有較大優(yōu)勢(shì),但PCBN刀具根據(jù)材料特性通常不設(shè)有斷屑槽,故斷屑困難,切削過程中切屑纏繞工件及刀具、不易折斷,從而降低刀具壽命和已加工表面質(zhì)量。高壓冷卻是金屬高效切削加工中一種新型加工技術(shù),可以有效改善斷屑性能、提升斷屑能力、提高刀具壽命和加工表面質(zhì)量,故本文通過高壓冷卻下PCBN刀具切削鎳基高溫合金GH4169試驗(yàn)研究,對(duì)高壓冷卻下切屑卷曲折斷機(jī)理進(jìn)行研究,并對(duì)高壓冷卻切屑折斷特性進(jìn)行分析。首先,通過試驗(yàn)對(duì)切削力和切屑形態(tài)進(jìn)行研究,以冷卻液壓力、切削參數(shù)、冷卻條件為變量進(jìn)行試驗(yàn),對(duì)比分析不同切削參數(shù)、不同冷卻條件和不同冷卻液壓力下的切削力和切屑形態(tài),研究高壓冷卻對(duì)切削力的影響規(guī)律及其原因,同時(shí)分析切屑形態(tài)在高壓冷卻加工下的變化規(guī)律,對(duì)高壓冷卻下切屑卷曲折斷變化規(guī)律進(jìn)行分析。其次,分析鎳基高溫合金加工過程中切屑形成機(jī)理,研究鋸齒形切屑形成過程。分析切屑受力情況,根據(jù)切削區(qū)域應(yīng)力分布建立切屑卷曲半徑預(yù)測(cè)模型,以最大應(yīng)變理論為切屑折斷判斷依據(jù),建立斷屑模型。分析高壓冷卻條件下冷卻液壓力對(duì)高溫合金切削加工中切屑所受彎矩影響規(guī)律,根據(jù)切屑彎矩變化規(guī)律進(jìn)一步分析切屑卷曲半徑變化情況和切屑所受應(yīng)變變化規(guī)律,建立高壓冷卻下切屑卷曲半徑模型和斷屑模型。然后對(duì)切屑微觀形態(tài)進(jìn)行研究,具體分析鎳基高溫合金鋸齒形切屑鋸齒化表征,分析高壓冷卻下鋸齒微觀形態(tài)變化規(guī)律,并對(duì)理論分析進(jìn)行驗(yàn)證。最后,建立常規(guī)冷卻及高壓冷卻下PCBN刀具切削鎳基高溫合金的有限元仿真模型,仿真分析鋸齒形切屑形成過程,分析不同切削參數(shù)、不同冷卻條件及不同冷卻液壓力對(duì)切屑形態(tài)及切削力的影響規(guī)律,同時(shí)對(duì)高壓冷卻條件下切屑卷曲折斷進(jìn)行仿真分析,研究切屑卷曲半徑隨冷卻液壓力變化情況,根據(jù)仿真結(jié)果對(duì)理論分析結(jié)果進(jìn)行驗(yàn)證,并為后續(xù)高壓冷卻加工研究提供理論依據(jù)。
[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.
【學(xué)位授予單位】：哈爾濱理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG506.7

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