本文關(guān)鍵詞： 拋光 剪切增稠拋光 剪切增稠 超精密加工 高效加工 剪切增稠拋光液 材料去除率 表面粗糙度　出處：《湖南大學(xué)》2015年博士論文　論文類型：學(xué)位論文

【摘要】：如何實現(xiàn)目標(biāo)工件的高效、高質(zhì)量、低成本加工是目前精密與超精密加工領(lǐng)域的研究熱點。為此,本文提出一種基于非牛頓冪律流體剪切增稠效應(yīng)的新型加工方法——剪切增稠拋光(Shear-thickening Polishing,STP):利用非牛頓冪律流體拋光液的剪切增稠流變特性達(dá)到增強(qiáng)把持磨粒的約束力而形成類似“柔性固著磨具”、增大接觸區(qū)域面積而具有良好的面形適應(yīng)性,從而可實現(xiàn)工件表面的高效精密拋光。針對剪切增稠拋光方法的材料去除機(jī)理和工藝技術(shù)進(jìn)行研究,圍繞高性能拋光液的制備及其流變性能、加工過程中的材料去除率、表面質(zhì)量等關(guān)鍵技術(shù)問題展開探索,建立了擁有自主知識產(chǎn)權(quán)的高效精密剪切增稠拋光理論基礎(chǔ)及工藝技術(shù)。主要研究內(nèi)容包括:(1)對STP加工方法的可行性進(jìn)行研究。分析加工過程的主要影響因素,并通過FLUENT軟件對具有剪切增稠效應(yīng)的拋光液(一種非牛頓冪律流體)流場CFD仿真,對加工原理的有效性進(jìn)行對比仿真驗證。在此基礎(chǔ)上,采用剪切增稠拋光液對GCr15軸承鋼工件進(jìn)行拋光的材料去除率(Material Removal Rate,MRR)約為對照組(相同初始黏度的非剪切增稠流體拋光液)的10倍,且表面粗糙度由Ra 101.33 nm降至Ra7.80 nm,遠(yuǎn)低于對照組(僅下降至Ra 96.81 nm),證明剪切增稠拋光加工方法的可行性,為后續(xù)深入研究提供理論基礎(chǔ)。(2)對剪切增稠拋光液(Shear-thickening Polishing Slurry,STPS)的制備方法及性能進(jìn)行研究。在實現(xiàn)STP加工原理的前提下,確定原料易獲取、環(huán)境友好、合適的剪切增稠拋光基液(Shear-thickening Based Fluid,STBF),構(gòu)建了STPS的制備工藝流程。采用上述工藝制備出Al_2O_3基STPS,其具有剪切稀化和可逆的剪切增稠效應(yīng),隨著剪切應(yīng)力變化而實現(xiàn)Al_2O_3“粒子簇”形成與消失,從而能夠達(dá)到STP技術(shù)所需拋光液的流變特性。(3)對STPS的流變行為進(jìn)行深入研究,確定剪切增稠條件和各粘性參數(shù)的數(shù)值計算。研究發(fā)現(xiàn),隨著剪切速率的增大,STPS存在著3個明顯的黏度區(qū)域:剪切稀化區(qū)域I、剪切增稠區(qū)域II、剪切稀化區(qū)域III。STPS發(fā)生剪切增稠的閾值為變化范圍10~1000 s-1,尤其在剪切速率變化范圍200~1000 s-1可達(dá)到剪切增稠效應(yīng)而實現(xiàn)工件的高效拋光。隨后,計算得到STPS本構(gòu)方程中的粘性參數(shù)(包括稠度系數(shù)K和粘性指數(shù)n)的精確解,為STP的材料去除率模型的建立等后續(xù)研究提供了理論基礎(chǔ)。(4)針對STP加工的材料去除機(jī)理進(jìn)行理論研究。依據(jù)Preston方程和流體動力學(xué)理論,構(gòu)建了STP加工的MRR模型。經(jīng)試驗研究,由MRR模型得出的理論值與試驗的測量值的相對誤差僅為6.12%,證明MRR模型具有一定的有效性。對MRR和表面粗糙度Ra的試驗研究顯示:隨著拋光速度(U)、磨粒濃度(w%)的增大,MRR隨之增大,但其隨磨粒粒徑(d)的減小而增大;隨著U、w%的增大,表面粗糙度Ra減小,表面質(zhì)量提升,但在本試驗條件下,d的變化對工件表面粗糙度Ra的影響較小。(5)對STP加工工件的表面粗糙度模型及表面演化進(jìn)行研究。依據(jù)工件布氏硬度(BHN)的計算、剪切增稠機(jī)制和塑性壓痕的磨料磨損理論,建立了STP的表面粗糙度預(yù)測模型。通過試驗驗證了表面粗糙度預(yù)測模型的有效性,工件表面粗糙度的理論值與試驗值的最大誤差僅為8.29%。該模型的建立,有利于對塑性工件加工的表面質(zhì)量控制,并開展了STP加工Cr12Mo1V1的表面演化研究。延伸研究了STP加工單晶硅片,為脆性材料的表面粗糙度預(yù)測模型的建立提供基礎(chǔ)。(6)對STP加工工藝進(jìn)行研究。通過田口法的正交實驗,獲得了本加工條件下的優(yōu)化工藝參數(shù):拋光速度300rpm、磨料粒度4000#、磨料濃度23 wt%為最佳參數(shù)組合。利用優(yōu)化的STP加工工藝對Cr12Mo1V1進(jìn)行試驗加工,其MRR達(dá)到13.69μm/h;加工0.5 h,表面粗糙度由Ra 105.95 nm快速下降至Ra 5.1 nm。采用STP、雙平面方式研磨拋光(結(jié)合化學(xué)機(jī)械拋光)圓柱工件進(jìn)行對比研究,STP工藝的MRR是雙平面方式研磨工藝的2倍以上,為化學(xué)機(jī)械拋光的4倍;工件經(jīng)STP后的表面粗糙度從Ra 125 nm下降到Ra 5.1 nm,而雙平面方式研磨拋光的工件表面粗糙度由Ra 76 nm下降至Ra 16.6 nm;同等條件下,前者所獲工件圓度誤差為RONt 0.376mm,后者所獲圓度誤差為RONt 0.390mm,說明STP具有良好的拋光效率和加工質(zhì)量。利用STP對Si_3N_4陶瓷進(jìn)行加工,150 min后表面粗糙度由Ra 110.90 nm降至Ra 7.20 nm,且MRR為2.04μm/h;在STP-1型試驗樣機(jī)上應(yīng)用小拋光工具頭對拋物面反射面(HPM38模具鋼)進(jìn)行STP加工的探索研究,120 min后獲得表面粗糙度Ra 4.73 nm,面形誤差PV值達(dá)到0.86μm。試驗表明,STP不僅能高效拋光硬脆性材料,并具有復(fù)雜曲面超精密拋光的應(yīng)用潛力。上述結(jié)果表明,剪切增稠拋光(STP)是一種基于非牛頓冪律流體剪切增稠效應(yīng)的新型高效、高質(zhì)量、低成本加工方法。
[Abstract]:How to achieve the goal of workpiece efficient, high quality, low cost of processing is currently hot research fields of precision and ultra precision machining. Therefore, this paper proposes a new polishing - shear thickening processing method of thickening effect of non Newtonian power-law fluid shear based on (Shear-thickening Polishing, STP): the use of shear non Newtonian fluid slurry thickening rheological properties to enhance the control of particle binding and the formation of similar "flexible fixed abrasive, contact area increases and the surface has good adaptability, which can achieve high efficiency and precision polishing of the workpiece surface. According to the removal mechanism and technology of shear thickening polishing method was studied, and its preparation rheological properties on high performance liquid polishing system, in the process of material removal rate, surface quality and other key technical problems to start exploring the established with independent intellectual property Thickening polishing theory and technology of high precision shearing power. The main research contents include: (1) to study the feasibility of STP processing method. The main factors affecting the analysis process, and through the FLUENT software with the shear thickening effect of the polishing liquid (a non Newton power-law fluid flow field CFD simulation) comparison of the results of simulation, the validity of the processing principle. On this basis, the shear thickening liquid polishing polishing of GCr15 bearing steel workpiece material removal rate (Material Removal, Rate, MRR) about the control group (the same initial viscosity of non shear thickening fluid polishing liquid) 10 times, and the surface roughness from Ra 101.33 nm to Ra7.80 nm, much lower than the control group (only 96.81 down to Ra nm), to demonstrate the feasibility of shear thickening polishing method, provide a theoretical basis for further research. (2) the shear thickening liquid polishing (Shear-t HICKENING Polishing Slurry, STPS) preparation and performance research. In the premise of realizing the principle of STP processing, easy to obtain raw materials to determine, environmentally friendly, the appropriate shear thickening liquid (Shear-thickening Based polishing Fluid, STBF), the construction process of the preparation of STPS prepared Al_2O_3 based STPS used. The above process, with shear thinning and shear thickening effect reversible, with the shear stress change and the realization of Al_2O_3 clusters forming and disappearing, the rheological properties of STP technology so as to achieve the required polishing. (3) studied the rheological behavior of STPS, numerical determination of shear thickening conditions and the viscosity parameter calculation. The study found that with the increase of shear rate, STPS has 3 distinct regions: the viscosity shear thinning region I, shear thickening region II, shear thinning region of III.STPS. The threshold for shear thickening The change range of 10~1000 s-1, especially in the high polishing shear rate range of 200~1000 S-1 can achieve the shear thickening effect and workpiece. Then the calculated viscous constitutive parameters in the equations of STPS (including K viscosity coefficient and viscosity index n) exact solutions, provides a theoretical basis for the STP model of material removal rate the establishment of a follow-up study. (4) for the processing of the material removal mechanism of STP theory research. Based on the Preston equation and the theory of fluid dynamics, constructs a MRR model of STP machining. Through experimental research, obtained by the MRR model. The relative error measurement and test the value of only 6.12%, we proved that the MRR model has the effectiveness of MRR. And the experimental research on surface roughness of Ra showed: with the polishing speed (U), particle concentration (w%) increased, MRR increased, but with the particle size (d) decreases with increasing U, the increase of w%, The surface roughness of Ra decreases, the surface quality improvement, but under the conditions of this experiment, the change of D has little effect on the surface roughness of Ra. (5) of STP on the surface roughness of the workpiece surface model and evolution are studied. On the basis of the Brinell hardness (BHN) calculation, the abrasive wear theory of shear thickening the mechanism and plastic indentation, establishes the prediction of STP rough surface model. The test results validate the prediction model of surface roughness, the surface roughness of the workpiece to establish the theoretical value of the maximum error and the experimental value is only 8.29%. of the model, is conducive to the control of the surface quality of the plastic workpiece, and Research on evolution of STP surface processing of Cr12Mo1V1. On the STP wafer processing extension, surface roughness prediction of brittle materials provide a basis model. (6) to study the STP processing technology. Through the orthogonal Taguchi Nori The optimized parameters are obtained under the condition of the processing speed: polishing abrasive particle size 300rpm, 4000#, abrasive concentration 23 wt% was the best combination of parameters. Experiments were carried out on Cr12Mo1V1 processing using STP process optimization, the MRR reached 13.69 m/h; 0.5 h processing, the surface roughness by Ra 105.95 nm rapid decline to Ra 5.1 nm. by STP, double plane polishing (combined with chemical mechanical polishing) cylindrical workpiece were studied and compared with STP process MRR is a dual plane lapping process for more than 2 times, 4 times for chemical mechanical polishing; workpiece by surface roughness after STP Ra from 125 nm down to 5.1 nm and Ra. Double plane polishing workpiece surface roughness by Ra 76 nm down to 16.6 nm Ra; under the same conditions, the former received a degree error of workpiece circle is RONt 0.376mm, the latter the roundness error is RONt 0.390mm, indicating that STP has a good polishing Efficiency and processing quality. The processing of the Si_3N_4 ceramics with STP rough surface after 150 min degree from Ra 110.90 nm to Ra 7.20 nm and MRR 2.04 m/h; application of small polishing tool head of the parabolic reflector in STP-1 experimental prototype (HPM38 steel) STP processing research, 120 min obtained after the surface roughness Ra of 4.73 nm, the surface shape error of the PV value reached 0.86 mu m. test shows that STP can not only hard brittle materials, polishing, and has the potential application of complex surface in ultra precision polishing. The results show that the shear thickening polishing (STP) is a kind of high quality efficient thickening effect. Non Newtonian power-law fluid shear based on low cost processing method.

【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TG580.692

【參考文獻(xiàn)】

相關(guān)期刊論文 前5條

1 彭巖;呂冰海;紀(jì)宏波;孫磊;董晨晨;袁巨龍;;非牛頓流體材料在工業(yè)領(lǐng)域的應(yīng)用與展望[J];輕工機(jī)械;2014年01期

2 張銀霞;郜偉;康仁科;郭東明;;單晶硅片磨削的表面相變[J];光學(xué)精密工程;2008年08期

3 肖保其;雷紅;;納米SiO_2/CeO_2復(fù)合磨粒的制備及其拋光特性研究[J];摩擦學(xué)學(xué)報;2008年02期

4 李霞章;陳楊;陳志剛;陳建清;倪超英;;納米CeO_2顆粒的制備及其化學(xué)機(jī)械拋光性能研究[J];摩擦學(xué)學(xué)報;2007年01期

5 袁巨龍;王志偉;文東輝;呂冰海;戴勇;;超精密加工現(xiàn)狀綜述[J];機(jī)械工程學(xué)報;2007年01期

相關(guān)博士學(xué)位論文 前2條

1 劉國躍;電化學(xué)磁力研磨復(fù)合加工工藝及機(jī)理研究[D];廣東工業(yè)大學(xué);2012年

2 呂冰海;陶瓷球雙轉(zhuǎn)盤研磨方式及成球機(jī)理的研究[D];哈爾濱工業(yè)大學(xué);2007年

相關(guān)碩士學(xué)位論文 前2條

1 王晨升;基于彈性變形原理的非球面工件加工真空吸附夾具研究[D];湖南大學(xué);2012年

2 田虹;電磁流變效應(yīng)微砂輪研拋加工機(jī)理研究[D];廣東工業(yè)大學(xué);2008年

，

本文編號：1525357