【摘要】：干式硬態(tài)車削加工時(shí),已加工表面受高溫、高壓以及高應(yīng)變率的影響,發(fā)生塑性變形,會(huì)在工件表面產(chǎn)生殘余應(yīng)力,對(duì)工件機(jī)械性能和疲勞壽命影響很大。已加工表面殘余應(yīng)力的形成是一個(gè)受多因素影響的復(fù)雜過程,不同的切削參數(shù)、不同的材料硬度都會(huì)影響到殘余應(yīng)力的形成和分布,為揭示殘余應(yīng)力的產(chǎn)生及分布規(guī)律,需要結(jié)合理論和試驗(yàn),對(duì)其不同影響因素進(jìn)行深入分析和研究。由于干式硬態(tài)車削試驗(yàn)中,需要多次試驗(yàn)采集數(shù)據(jù)分析,對(duì)刀具、工件材料消耗很大,試驗(yàn)成本較高。隨著有限元法在金屬切削加工以及殘余應(yīng)力建模仿真中的廣泛應(yīng)用,利用ABAQUS等有限元軟件進(jìn)行模擬試驗(yàn),不僅省時(shí)省力、節(jié)約成本,而且表現(xiàn)力強(qiáng)、可靠性高,具有實(shí)際的參考價(jià)值。殘余應(yīng)力作為已加工表面質(zhì)量的重要影響指標(biāo),對(duì)其產(chǎn)生過程及分布規(guī)律進(jìn)行深入研究和揭示,可為合理選擇切削參數(shù)、提高工件表面質(zhì)量提供重要的理論依據(jù)。本論文通過對(duì)干式硬態(tài)車削Cr12Mo V表面殘余應(yīng)力進(jìn)行有限元仿真分析,揭示了不同因素對(duì)工件表面殘余應(yīng)力大小及分布的影響機(jī)理,并提出了最優(yōu)切削方案。主要工作內(nèi)容和研究成果如下:(1)進(jìn)行了SHPB試驗(yàn),根據(jù)試驗(yàn)數(shù)據(jù)和Johnson-Cook本構(gòu)方程,計(jì)算出了Cr12Mo V材料不同淬硬狀態(tài)對(duì)應(yīng)的A、B、C、m、n模型參數(shù)值,并運(yùn)用ABAQUS有限元分析軟件,建立了PCBN刀具切削Cr12Mo V的干式硬態(tài)車削模型。(2)采用單因素正交試驗(yàn)設(shè)計(jì)法,進(jìn)行了干式硬態(tài)車削Cr12Mo V的有限元仿真試驗(yàn),對(duì)其加工表面殘余應(yīng)力進(jìn)行分析,揭示了不同材料淬硬程度、不同切削參數(shù)對(duì)已加工表面殘余應(yīng)力大小及分布的影響規(guī)律。(3)通過多因素正交試驗(yàn)設(shè)計(jì),對(duì)不同切削參數(shù)進(jìn)行了優(yōu)化分析,提出了最優(yōu)切削方案,并通過干式硬態(tài)車削實(shí)驗(yàn)對(duì)優(yōu)化結(jié)果進(jìn)行了驗(yàn)證。研究結(jié)果表明:在一定工件層深范圍內(nèi),干式硬態(tài)車削Cr12Mo V表面0~0.16mm處均出現(xiàn)了殘余壓應(yīng)力,且隨著表面層深的遞增,殘余壓應(yīng)力先是逐漸增大,后又逐漸減小,最后趨近于0;在選取的5種不同影響因子中,隨著工件硬度、背吃刀量、刀具后角的增加,已加工表面殘余壓應(yīng)力逐漸增大,隨著切削速度、刀具前角的增加,已加工表面殘余壓應(yīng)力逐漸減小;在選取的4種不同切削參數(shù)中,對(duì)殘余應(yīng)力影響大小程度依次為:刀具后角最大,背吃刀量次之,切削速度第三,刀具前角最小;4種不同切削參數(shù)優(yōu)化后的最優(yōu)組合為:切削速度v=400 m·min-1,背吃刀量pa=0.20 mm,刀具前角γ_0=-5°,刀具后角α_0=10°。
[Abstract]:During dry hard turning, the machined surface is affected by high temperature, high pressure and high strain rate, and plastic deformation occurs, which will produce residual stress on the surface of the workpiece, which has a great influence on the mechanical properties and fatigue life of the workpiece. The formation of residual stress on machined surface is a complex process affected by many factors. Different cutting parameters and different material hardness will affect the formation and distribution of residual stress. In order to reveal the generation and distribution of residual stress, it is necessary to analyze and study the different influencing factors in combination with theory and test. Because of the need for many tests to collect data analysis in dry hard turning test, the material consumption of cutting tool and workpiece is very large and the test cost is high. With the wide application of finite element method in metal cutting and residual stress modeling and simulation, using ABAQUS and other finite element software to carry out simulation test not only saves time and labor, saves cost, but also has strong expressive force and high reliability, so it has practical reference value. As an important influence index of machined surface quality, the generation process and distribution law of residual stress are deeply studied and revealed, which can provide an important theoretical basis for the reasonable selection of cutting parameters and the improvement of workpiece surface quality. In this paper, the finite element simulation analysis of the residual stress on the surface of Cr12Mo V in dry hard turning is carried out, and the influence mechanism of different factors on the residual stress on the surface of the workpiece is revealed, and the optimal cutting scheme is put forward. The main contents and research results are as follows: (1) according to the test data and Johnson-Cook constitutive equation, the parameters of A, C, m, n model corresponding to different hardened states of Cr12Mo V material are calculated, and the dry hard turning model of PCBN tool cutting Cr12Mo V is established by using ABAQUS finite element analysis software. (2) the single factor orthogonal experimental design method is used. The finite element simulation test of dry hard turning Cr12Mo V is carried out, and the residual stress on the machined surface is analyzed, and the influence of different material hardening degree and different cutting parameters on the residual stress size and distribution of the machined surface is revealed. (3) through the multi-factor orthogonal experimental design, the different cutting parameters are optimized and the optimal cutting scheme is put forward. The optimization results are verified by dry hard turning experiment. The results show that the residual compressive stress appears at 0~0.16mm on the surface of Cr12Mo V in dry hard turning in a certain range of workpiece depth, and with the increase of surface depth, the residual compressive stress increases gradually, then decreases gradually, and finally approaches to 0. Among the five different influencing factors, with the increase of workpiece hardness, back feeding amount and tool rear angle, the residual compressive stress on the machined surface increases gradually, and with the increase of cutting speed and the front angle of the tool, the residual compressive stress on the machined surface decreases gradually. Among the four different cutting parameters, the influence on the residual stress is as follows: the rear angle of the tool is the largest, the number of tools fed on the back is the second, the cutting speed is the third, and the front angle of the tool is the smallest, and the optimal combination of the four different cutting parameters is as follows: cutting speed v 鈮，

本文編號(hào)：2500245