本文選題：連鑄結(jié)晶器 + 渣道形狀��； 參考：《東北大學(xué)》2012年碩士論文

【摘要】：結(jié)晶器是連鑄機中最重要的組成部分,過熱鋼液在其內(nèi)由液態(tài)轉(zhuǎn)變?yōu)楣虘B(tài),完成初始凝固過程,其彎月面行為直接決定了連鑄坯的表面質(zhì)量。探索保護渣在彎月面處結(jié)晶器銅板與初始凝固坯殼間的潤滑機理及規(guī)律對完善漏鋼預(yù)報,提高鑄坯表面質(zhì)量等都有著極其重要的意義。由于檢測手段和現(xiàn)場生產(chǎn)條件的限制,要直接獲得彎月面處的保護渣潤滑狀態(tài)幾乎不可能。因此,通過數(shù)值模擬手段研究彎月面處保護渣潤滑行為就顯得尤為重要。為此,本文以某鋼廠寬厚板坯連鑄結(jié)晶器為研究對象,建立結(jié)晶器彎月面區(qū)域保護渣動壓潤滑理論模型,優(yōu)化結(jié)晶器振動參數(shù),主要研究內(nèi)容和獲得結(jié)論如下： (1)結(jié)晶器彎月面處保護渣分布規(guī)律研究。通過建立的結(jié)晶器銅板三維熱-力耦合模型和二維鑄坯非穩(wěn)態(tài)傳熱模型,得到結(jié)晶器銅板熱面溫度場和法向變形量分布以及凝固坯殼表面溫度分布和凝固坯殼厚度,從而計算得出保護渣厚度分布。液態(tài)渣膜厚度沿結(jié)晶器高度方向逐漸降低,在距彎月面200mm處液態(tài)渣消失,滿足收斂性形狀要求。取距彎月面80mm的范圍,對保護渣厚度作線性擬合,建立彎月面處的結(jié)晶器保護渣動壓潤滑模型。 (2)結(jié)晶器彎月面動壓潤滑行為理論研究。在動壓潤滑理論建立的基礎(chǔ)上,根據(jù)保護渣動量、質(zhì)量守恒方程,推導(dǎo)出液態(tài)保護渣渣道內(nèi)的速度、壓力、摩擦力分布計算公式。計算結(jié)果表明：黏度為0.1Pa-s的保護渣在正弦振動條件下,在彎月面區(qū)域內(nèi)液態(tài)渣的相對速度呈連續(xù)分布,越靠近鑄坯界面速度梯度越大,且同一位置處振動速度越大,相對速度梯度越大；因振動形成的壓力分布在研究范圍內(nèi)先增大后減小,正滑脫時期內(nèi)產(chǎn)生相對正壓,發(fā)揮承載作用抵抗鋼水靜壓,形成動壓潤滑,負滑脫時期內(nèi)產(chǎn)生的相對壓力為負壓,將保護渣吸入渣道；摩擦力隨距彎月面的距離和結(jié)晶器振動速度的增大而增大,且摩擦力增大幅度與振動速度增加幅度一致。 (3)結(jié)晶器彎月面動壓潤滑效果主要影響因素研究。①改變結(jié)晶器保護渣黏度時,對渣道內(nèi)速度分布影響較小,壓力分布和液態(tài)摩擦力影響較大。保護渣黏度分別為1.0Pa-s,0.5Pa.s和0.1Pa.s,結(jié)晶器以1.25m/min的最大上振速度運動時,隨著保護渣黏度的增大,渣道內(nèi)產(chǎn)生的壓力越大,抵抗鋼水靜壓力作用越強；潤滑狀態(tài)越差,液態(tài)摩擦力變化越劇烈。②改變拉速時,液態(tài)渣道內(nèi)的速度分布變化趨勢、壓力以及液態(tài)摩擦力分布方式基本不變,隨著拉速的增大,渣道內(nèi)產(chǎn)生的壓力減小,摩擦力增大。 (4)結(jié)晶器振動參數(shù)優(yōu)化準則研究。動壓潤滑理論分析表明：非正弦振動時,在最大上振速度盡量大的前提下,延長正滑動時間是維持良好潤滑效果的首要考慮因素。在保證結(jié)晶器順行的前提下,可以適當(dāng)增大非正弦因子a,振動頻率f和振幅s,提高動壓潤滑效果,利于鑄坯的脫模、裂紋愈合和增加液渣消耗。
[Abstract]:The mold is the most important part in the continuous casting machine. The superheated steel changes from liquid state to solid state and completes the initial solidification process. Its meniscus behavior directly determines the surface quality of continuous casting billet. It is of great significance to explore the lubrication mechanism and regularity of mould copper plate and initial solidified shell at the meniscus for improving the prediction of steel breakout and improving the surface quality of billet. It is almost impossible to obtain the lubrication state of mold powder directly because of the limitation of testing means and production conditions. Therefore, it is very important to study the lubrication behavior of mold powder at meniscus by numerical simulation. In this paper, a theoretical model of hydrodynamic lubrication for mold meniscus is established to optimize the vibration parameters of mould. The main research contents and conclusions are as follows: (1) in this paper, the mould for wide and thick slab continuous casting is taken as the research object, and the theoretical model of hydrodynamic lubrication of mold meniscus is established, and the vibration parameters of mold are optimized. 1) study on the distribution of mold powder at the meniscus of the mould. Based on the three-dimensional thermal-mechanical coupled model and the two-dimensional unsteady heat transfer model, the temperature field and normal deformation distribution on the hot surface, the surface temperature distribution and the thickness of the solidified billet shell are obtained. The thickness distribution of mold powder is calculated. The thickness of liquid slag film decreases gradually along the direction of mold height and disappears at the distance from meniscus to the meniscus 200mm to meet the requirements of convergent shape. Taking the range of 80mm from meniscus, the thickness of mold slag is fitted linearly, and the dynamic lubrication model of mold slag at meniscus is established. (2) theoretical study on the dynamic lubrication behavior of the meniscus of the mould. Based on the theory of hydrodynamic lubrication and the conservation equation of the momentum and mass of the mold slag, the formulas for calculating the velocity, pressure and friction force in the channel of the liquid mold slag are derived. The results show that the relative velocity of liquid slag in the region of meniscus is continuous under the condition of sinusoidal vibration with viscosity of 0.1Pa-s. The closer the velocity gradient is to the interface of the billet, the greater the velocity of vibration is at the same position. The larger the relative velocity gradient is, the larger the pressure distribution due to vibration first increases and then decreases within the range of study, and the relative positive pressure is produced during the period of positive slip, which exerts the bearing capacity to resist the hydrostatic pressure of molten steel and forms hydrodynamic lubrication. The relative pressure produced during the period of negative slippage is negative pressure, and the friction force increases with the increase of the distance from the meniscus and the vibration velocity of the mould, and the increase of the friction force is consistent with the increase of the vibration velocity. The main factors affecting the hydrodynamic lubrication effect of mold meniscus 1. When the viscosity of mold flux is changed, the velocity distribution in slag channel is less affected, and the pressure distribution and liquid friction force are greatly affected. The viscosity of mold slag is 1.0 Pa-sn 0.5 Pa.s and 0.1 Pa.s.When the mould moves at the maximum upswing velocity of 1.25m/min, with the increase of the viscosity of mold slag, the greater the pressure produced in the slag channel, the stronger the resistance to the static pressure of molten steel, and the worse the lubricating state is. When the liquid friction force changes sharply, the velocity distribution in the slag channel changes, and the pressure and the distribution mode of the liquid friction force basically remain unchanged. With the increase of the drawing speed, the pressure in the slag channel decreases and the friction force increases. The optimization criteria of mould vibration parameters are studied. The theoretical analysis of hydrodynamic lubrication shows that the extension of the positive sliding time is the primary factor to maintain the good lubricating effect under the premise of the maximum up vibration speed when the vibration is not sinusoidal. On the premise of ensuring the mold running smoothly, the non-sinusoidal factor a, vibration frequency f and amplitude s can be increased appropriately, and the hydrodynamic lubrication effect can be improved, which is beneficial to the release of casting billet, crack healing and increasing the consumption of liquid slag.
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TF341.6;TH117.2

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