【摘要】：陶瓷材料的強(qiáng)度大、硬度高、耐熱性能好、耐腐蝕能力強(qiáng),在航天航空、醫(yī)療、微機(jī)械等領(lǐng)域中逐漸得到廣泛應(yīng)用。其中,氧化鋁陶瓷以其優(yōu)良的物理化學(xué)性能及較高的強(qiáng)度成為應(yīng)用最廣泛的陶瓷材料之一。對陶瓷生坯的直接加工容易導(dǎo)致邊緣破損及表面精度降低,而完全燒結(jié)后的陶瓷坯體強(qiáng)度大大提高,加工難度增加。因此采用對陶瓷生坯進(jìn)行低溫?zé)崽幚砑搭A(yù)燒結(jié)的工藝,不僅可以提高其機(jī)械強(qiáng)度,而且加工獲得的結(jié)構(gòu)表面質(zhì)量較好。本文通過在氧化鋁陶瓷坯體上銑削不同深度的微長槽研究了陶瓷坯體在銑削過程中的分離機(jī)理及加工參數(shù)的影響,并在陶瓷表面進(jìn)行微孔鉆削,從而獲得最佳的加工條件。通過單向加壓的方法制備陶瓷生坯,并對其進(jìn)行預(yù)燒結(jié)來提高坯體強(qiáng)度,利用三點(diǎn)抗彎強(qiáng)度測試實(shí)驗(yàn)測試了不同壓力成型下材料的抗彎強(qiáng)度。實(shí)驗(yàn)數(shù)據(jù)表明,陶瓷材料的抗彎強(qiáng)度隨著壓力的增加呈線性增長。由于陶瓷生坯銑削加工中材料呈顆粒狀剝離,導(dǎo)致加工后的結(jié)構(gòu)出現(xiàn)加工間隙,與金屬加工存在很大的不同,另一方面,加工產(chǎn)生的絮狀切屑從坯體與刀具之間的間隙流出時會對結(jié)構(gòu)邊緣產(chǎn)生擠壓導(dǎo)致表面精度降低�；谶@些特點(diǎn),通過在陶瓷坯體上加工不同深度的長槽確定了加工過程中的三種材料分離機(jī)理,并研究了不同加工參數(shù)對材料分離機(jī)理的影響。分析了不同轉(zhuǎn)速下刀具上吸附切屑的情況,結(jié)果表明刀具上吸附切屑的數(shù)量隨著主軸轉(zhuǎn)速的增加而減少。通過線電極電火花磨削(WEDG)技術(shù)在線制備微細(xì)刀具,之后在預(yù)燒結(jié)陶瓷坯體上進(jìn)行微孔鉆削,探討了各種工藝參數(shù)及切屑對加工結(jié)果的影響。實(shí)驗(yàn)結(jié)果顯示,當(dāng)采用D形截面刀具進(jìn)行微通孔鈷削時,預(yù)燒結(jié)溫度應(yīng)選擇800℃,且加工過程中加入切削液(水)。同時,加工過程中加入的切削液會對坯體產(chǎn)生一定的作用力,減弱了坯體加工過程中的應(yīng)力集中現(xiàn)象,使孔出口處的邊緣破損程度降低并減少出口處的切屑堆積。最后研究了切削液對微孔加工間隙的影響,取得了加工間隙明顯降低的良好效果。
[Abstract]:Ceramic materials with high strength, high hardness, good heat resistance and corrosion resistance have been widely used in aerospace, medical, micro-machinery and other fields. Among them, alumina ceramic has become one of the most widely used ceramic materials because of its excellent physical and chemical properties and high strength. The direct machining of raw ceramic billet can easily lead to edge damage and surface precision decrease, while the strength of ceramic billet after sintering is greatly improved, and the processing difficulty is increased. Therefore, the low temperature heat treatment of raw ceramic billet, that is, pre-sintering process, can not only improve its mechanical strength, but also the structure surface quality obtained by processing is better. In this paper, the separation mechanism of ceramic billet and the influence of machining parameters during milling process were studied by milling micro-long grooves with different depths on alumina ceramic billet, and microhole drilling was carried out on ceramic surface to obtain the best processing conditions. Ceramic billets were prepared by unidirectional compression and pre-sintered to improve the strength of the billets. The bending strength of the materials under different pressure forming was tested by three point bending strength test. The experimental data show that the bending strength of ceramic materials increases linearly with the increase of pressure. Because the material is peeled off in the milling process of ceramic billet, the structure after processing appears machining gap, which is very different from metal processing, on the other hand, When the flocculating chip flows out from the gap between the blank and the cutting tool, it will squeeze the edge of the structure and reduce the surface precision. Based on these characteristics, three kinds of material separation mechanisms were determined by machining long grooves of different depths on ceramic billets, and the effects of different processing parameters on material separation mechanism were studied. The results show that the amount of chip adsorbed on the cutting tool decreases with the increase of spindle speed. Micro cutting tools were prepared by wire electrode electrical discharge grinding (WEDG) technique on line and then drilled on pre-sintered ceramic billets. The effects of various technological parameters and chips on the machining results were discussed. The experimental results show that the pre-sintering temperature should be chosen at 800 鈩，

本文編號：2274499