本文選題：微擠壓　切入點：微成形　出處：《哈爾濱工業(yè)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：微系統(tǒng)技術(shù)和微機(jī)電系統(tǒng),在近期快速發(fā)展并逐步投入到實際應(yīng)用當(dāng)中,微型零件在應(yīng)用中更加受重視。微型熱交換器、微型反應(yīng)器、微型電機(jī)、光學(xué)傳感器等微機(jī)電系統(tǒng)的重要零件,在微機(jī)電系統(tǒng)中的微結(jié)構(gòu)的制造技術(shù)成為廣大科研工作者的關(guān)注重點,超精密機(jī)械加工、LIGA、刻蝕等微器件制造技術(shù)在可加工材料種類、成本、加工效率方面存在不同程度的進(jìn)步空間。塑性微擠壓具有著重復(fù)性好、成形件機(jī)械性能優(yōu)異、成本低、效率高、工藝簡單等特點,因此研究微擠壓技術(shù)有著充足的必要性。本課題利用等通道轉(zhuǎn)角擠壓法制備微擠壓實驗原始坯料,并通過顯微硬度測量和電子背散射衍射顯微觀察研究材料組織性能,發(fā)現(xiàn)晶粒的細(xì)化是主要通過發(fā)生在凹模內(nèi)拐角處的剪切變形使材料內(nèi)部形成小角晶界、大角晶界。對實驗坯料進(jìn)行壓縮實驗發(fā)現(xiàn)與粗晶相比超細(xì)晶材料對壓縮速率更為敏感,同時其成形精度更高�；谟邢拊獢�(shù)值分析模擬軟件DEFORM-3D10.2對微擠壓過程進(jìn)行三維數(shù)值模擬,發(fā)現(xiàn)隨著凹模錐角越來越大,擠壓力越來越大,錐角區(qū)域塑性流動越來越差;另外對微擠壓過程應(yīng)力應(yīng)變速度場進(jìn)行分析,發(fā)現(xiàn)應(yīng)力在錐角區(qū)域集中,在已變形區(qū)外端應(yīng)變值較大,坯料上部的速度值是大于坯料下部速度值的。通過進(jìn)行微擠壓實驗,介紹了實驗?zāi)＞吆蛯嶒炘O(shè)備在實驗中作用,研究了不同坯料幾何尺寸、不同坯料晶粒情況、不同擠壓速度對實驗結(jié)果的影響并分析,發(fā)現(xiàn)當(dāng)坯料直徑減小時,單位擠壓力曲線下降,當(dāng)坯料直徑減小到1mm時,出現(xiàn)了單位擠壓力上升的尺度效應(yīng)現(xiàn)象,并給予了合理解釋。在對微擠壓件的電子背散射衍射顯微組織分析中發(fā)現(xiàn),擠壓件可被劃分為未變形區(qū)、變形區(qū)、已變形區(qū),擠壓件接近錐角部分晶粒變形劇烈,晶粒尺寸和模具尺寸之比越大則變形協(xié)調(diào)性越差的規(guī)律,連續(xù)擠壓棒料在熱處理溫度300℃以上時其熱穩(wěn)定性下降。
[Abstract]:Micro-system technology and micro-electromechanical system, in the recent rapid development and gradually put into practical applications, micro-parts in the application of more attention to micro-heat exchangers, micro-reactors, micro-motor, The important parts of MEMS, such as optical sensors, have become the focus of scientific research. The manufacturing technology of micro-structure in MEMS has become the focus of scientific research. The manufacturing technology of micro-devices such as ultra-precision machining, etching and so on, is in the category of machinable materials. The plastic micro-extrusion has the advantages of good repeatability, excellent mechanical properties, low cost, high efficiency, simple process and so on. Therefore, it is necessary to study the micro-extrusion technology. In this paper, the raw blank of micro-extrusion experiment is prepared by equal channel angular extrusion method, and the microstructure and properties of the material are studied by microhardness measurement and electron backscatter diffraction microscopy. It is found that the grain refinement is mainly caused by shearing deformation at the corner of the die to form the small angle grain boundary and the large angle grain boundary. The compression experiment of the experimental blank shows that the ultrafine grain material is more sensitive to the compression rate than the coarse grain material. At the same time, the forming accuracy is higher. Based on the finite element numerical analysis software DEFORM-3D10.2, the three-dimensional numerical simulation of micro-extrusion process is carried out. It is found that with the increasing conical angle of the die, the extrusion force is increasing, and the plastic flow in the cone-angle region is getting worse and worse. In addition, the stress-strain velocity field of micro-extrusion process is analyzed. It is found that the stress is concentrated in the cone angle region, and the strain value is large at the outside end of the deformed area, and the velocity value of the upper part of the blank is larger than the velocity value of the lower part of the blank. This paper introduces the function of experimental die and experimental equipment in the experiment, studies the influence of different blank geometry size, different blank grain condition and different extrusion speed on the experimental results, and finds out that when the blank diameter is reduced, The unit extrusion pressure curve decreases, when the blank diameter decreases to 1 mm, the scale effect of unit extrusion pressure rise appears, and the reasonable explanation is given. The extrusion part can be divided into undeformed zone, deformed zone, deformed zone, and the deformation of the part of the extruded part near the cone angle is severe. The bigger the ratio of grain size to die size is, the worse the compatibility of deformation is. The thermal stability of the continuous extrusion bar decreases when the heat treatment temperature is above 300 鈩，

本文編號：1588063