發(fā)布時(shí)間：2018-07-09 23:51

  本文選題：氣中電火花線(xiàn)切割 + 有限元仿真分析　； 參考：《哈爾濱理工大學(xué)》2017年碩士論文

【摘要】：Cr12MoV模具鋼經(jīng)過(guò)淬火處理后具有良好的耐磨性和抗腐蝕性,同時(shí)具有較高的硬度,利用傳統(tǒng)方法很難進(jìn)行加工,并且對(duì)刀具損傷較大。為了減小刀具損傷以及獲得較好工件表面質(zhì)量,通常采用氣中電火花線(xiàn)切割工藝對(duì)Cr12MoV模具鋼進(jìn)行加工。因?yàn)樵摴に嚺c液中電火花線(xiàn)切割加工技術(shù)相比,不易產(chǎn)生有害氣體和難分解的物質(zhì),并且具有較好成型特性。但由于受到現(xiàn)有實(shí)驗(yàn)條件的限制,氣中電火花線(xiàn)切割加工技術(shù)還處于理論與實(shí)驗(yàn)研究階段。通過(guò)氣中電火花線(xiàn)切割加工機(jī)理的研究,本文建立了氣中移動(dòng)單脈沖火花放電傳熱模型,確定了溫度場(chǎng)與應(yīng)力場(chǎng)的初始與邊界條件,并對(duì)傳熱模型的熱傳導(dǎo)方程、彈性塑性本構(gòu)方程以及熱應(yīng)力與應(yīng)變關(guān)系進(jìn)行了求解。在有限元理論基礎(chǔ)上,利用ABAQUS有限元軟件,建立了氣中移動(dòng)單脈沖火花放電有限元仿真模型,并對(duì)其進(jìn)行了仿真分析,揭示了氣中移動(dòng)單脈沖火花放電過(guò)程中Cr12MoV模具鋼表面?zhèn)鳠徇^(guò)程演化規(guī)律以及溫度場(chǎng)、應(yīng)力與應(yīng)變場(chǎng)分布及變化規(guī)律。并對(duì)熱源不同狀態(tài)下的電蝕坑形貌進(jìn)行分析,獲得了動(dòng)態(tài)下的單個(gè)電蝕坑幾何模型為半雙橢球形。根據(jù)實(shí)際加工情況,建立并修正了單個(gè)電蝕坑幾何模型,并對(duì)其進(jìn)行了體積計(jì)算,進(jìn)而探討了峰值電流、脈沖寬度等電參數(shù)對(duì)氣中電火花線(xiàn)切割工件表面電蝕坑幾何形貌的影響。在理論研究與仿真分析的基礎(chǔ)上,制定了多次氣中電火花線(xiàn)切割加工試驗(yàn)方案,并對(duì)Cr12MoV模具鋼進(jìn)行了電火花線(xiàn)切割加工試驗(yàn),對(duì)氣液電火花線(xiàn)切割工件表面形貌進(jìn)行了分析。通過(guò)單因素法獲得峰值電流、脈沖寬度、偏移量以及工作臺(tái)進(jìn)給速度等工藝參數(shù)下材料蝕除率與工件表面質(zhì)量的變化規(guī)律。將仿真數(shù)據(jù)與實(shí)際數(shù)據(jù)進(jìn)行對(duì)比,所得誤差在允許范圍內(nèi),從而驗(yàn)證所建模型的合理性。進(jìn)而說(shuō)明通過(guò)對(duì)該模型進(jìn)行有限元仿真分析,來(lái)探討工件表面電蝕坑幾何形貌及其影響因素是有效的。這對(duì)預(yù)測(cè)電火花線(xiàn)切割加工速率和工件表面質(zhì)量具有重要的意義。
[Abstract]:Cr12MoV die steel has good wear resistance, corrosion resistance and high hardness after quenching, so it is difficult to process by traditional method and has great damage to cutting tools. In order to reduce tool damage and obtain better surface quality of workpiece, gas WEDM is usually used to process Cr12MoV die steel. Compared with WEDM, it is difficult to produce harmful gas and difficult to decompose, and it has better forming characteristics. However, due to the limitation of the existing experimental conditions, the WEDM technology in gas is still in the stage of theoretical and experimental research. By studying the mechanism of WEDM in gas, the heat transfer model of moving single pulse spark discharge in gas is established, the initial and boundary conditions of temperature field and stress field are determined, and the heat conduction equation of heat transfer model is given. The elastoplastic constitutive equation and the relationship between thermal stress and strain are solved. On the basis of finite element theory, the finite element simulation model of moving single pulse spark discharge in gas is established by using Abaqus finite element software, and the simulation analysis is carried out. The evolution law of heat transfer on the surface of Cr12MoV die steel during moving single pulse spark discharge in gas and the distribution and variation of temperature field, stress and strain field are revealed. The morphologies of the etched pits in different states of the heat source were analyzed and the geometric model of the single etched pit was obtained as a semi-double ellipsoid. According to the actual machining conditions, the geometric model of a single electroetching pit is established and modified, and the volume of the model is calculated, and the peak current is discussed. The effect of pulse width and electrical parameters on the geometry of electroetching pits on the surface of WEDM workpiece in gas. On the basis of theoretical research and simulation analysis, the test scheme of WEDM in gas has been established, and the WEDM test of Cr12MoV die steel has been carried out, and the surface morphology of the workpiece of WEDM with gas-liquid EDM has been analyzed. The changes of material erosion rate and workpiece surface quality are obtained by single factor method under the process parameters such as peak current pulse width offset and feed speed of worktable. By comparing the simulation data with the actual data, the error is within the allowable range, which verifies the rationality of the model. It is proved that it is effective to study the geometric morphology of the surface of the workpiece and its influencing factors by the finite element simulation analysis of the model. It is of great significance to predict the WEDM rate and the surface quality of the workpiece.
【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(lèi)號(hào)】：TG484

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