本文選題：PCBN刀具負(fù)倒棱　切入點(diǎn)：粉末冶金氣門(mén)座圈　出處：《合肥工業(yè)大學(xué)》2016年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：采用粉末冶金技術(shù)制備的氣門(mén)座圈以其良好的耐磨性及耐高溫性得到廣泛使用,但這種氣門(mén)座圈硬度高,難以加工,且其內(nèi)部結(jié)構(gòu)多微孔,切削過(guò)程中對(duì)刀具的沖擊大,使用普通的硬質(zhì)合金刀具進(jìn)行切削加工時(shí),刀具耐用度低。近年來(lái),采用聚晶立方氮化硼(Polycrystalline Cubic Boron Nitride,簡(jiǎn)稱(chēng)PCBN)刀具硬態(tài)切削粉末冶金氣門(mén)座圈,大大提高了加工效率,降低了加工成本,且能獲得較高的加工表面質(zhì)量。本文旨在探究在硬態(tài)切削粉末冶金氣門(mén)座圈時(shí)PCBN刀具負(fù)倒棱對(duì)刀具切削性能的影響,為PCBN刀具負(fù)倒棱參數(shù)及其他工藝參數(shù)的選擇提供參考,具有較大的理論價(jià)值和實(shí)踐意義。主要研究?jī)?nèi)容及成果如下：首先使用PCBN刀具對(duì)粉末冶金氣門(mén)座圈進(jìn)行了外圓硬態(tài)切削試驗(yàn),利用Kistler9257B型三向測(cè)力儀測(cè)量切削力,發(fā)現(xiàn)了切削力隨著PCBN刀具負(fù)倒棱角度和負(fù)倒棱寬度及進(jìn)給量的變化規(guī)律。研究發(fā)現(xiàn)：切削過(guò)程中主切削力Fz始終大于Fx和Fy；隨著負(fù)倒棱角度的增加,切削力Fx,Fy和Fz都出現(xiàn)增大的趨勢(shì)；而隨著負(fù)倒棱寬度增加,切削力Fx,Fy和Fz呈現(xiàn)先增大后減小最后再增大的規(guī)律,其中切深抗力Fy變化較為明顯。然后通過(guò)測(cè)量氣門(mén)座圈已加工表面粗糙度研究了PCBN刀具負(fù)倒棱角度和負(fù)倒棱寬度及進(jìn)給量對(duì)于加工表面質(zhì)量的影響規(guī)律。結(jié)果表明：隨著PCBN刀具負(fù)倒棱角度增大,工件表面粗糙度增大；隨著負(fù)倒棱寬度增加,工件表面粗糙度呈先增大后減小最后增大的趨勢(shì)；對(duì)于不同負(fù)倒棱寬度的PCBN刀具,進(jìn)給量對(duì)已加工表面粗糙度的影響并不一致。最后試驗(yàn)研究了PCBN刀具負(fù)倒棱角度和負(fù)倒棱寬度對(duì)于刀具耐用度的影響,總結(jié)了生產(chǎn)中PCBN刀具的主要失效形式,觀(guān)察了PCBN刀具的磨損形態(tài),并對(duì)其磨損機(jī)理進(jìn)行了分析。結(jié)果表明：PCBN刀具失效形式有正常磨損和破損失效；主要磨損形式為微崩刃、后刀面磨損以及前刀面磨損,磨損機(jī)理主要為磨粒磨損、粘結(jié)磨損、擴(kuò)散磨損和氧化磨損；破損失效主要形式包括崩刃、剝落和碎斷等。
[Abstract]:The valve seat ring made by powder metallurgy technology has been widely used for its good wear resistance and high temperature resistance. However, the valve seat ring is hard to be machined because of its high hardness, and its internal structure has many micropores. In recent years, the polycrystalline cubic boron nitride Cubic Boron nitride (PCBN) tool has been used to cut hard the powder metallurgy valve seat ring in hard state, which greatly improves the machining efficiency. The machining cost is reduced and the machining surface quality is obtained. This paper aims to investigate the influence of negative chamfering of PCBN tool on cutting performance of the cutting tool in hard cutting of powder metallurgy valve seat. It provides a reference for the selection of negative chamfering parameters and other technological parameters of PCBN cutting tools. It has great theoretical value and practical significance. The main research contents and results are as follows: firstly, the outside circle hard cutting test of powder metallurgy valve seat ring is carried out by using PCBN tool, and the cutting force is measured by Kistler9257B three-way dynamometer. The variation law of cutting force with negative chamfering angle, negative chamfering width and feed rate of PCBN cutting tool is found. It is found that the main cutting force Fz is always larger than FX and Fyin cutting process, and with the increase of negative chamfer angle, The cutting forces Fxy and Fz both tend to increase with the increase of the width of negative chamfering edges, and the cutting forces FxFy and Fz increase at first and then decrease at last. The change of tangent resistance Fy is obvious. Then the influence of negative chamfering angle, negative chamfering width and feed rate on the surface quality of PCBN cutter is studied by measuring the machined surface roughness of the valve seat ring. With the increase of the negative inverse angle of the PCBN tool, The surface roughness of workpiece increases with the increase of negative chamfering width, the surface roughness of workpiece increases first and then decreases and then increases. For PCBN tool with different negative chamfering width, The effect of feed rate on the machined surface roughness is not consistent. Finally, the influence of the negative chamfering angle and the negative chamfering width of the PCBN cutter on the tool life is studied, and the main failure modes of the PCBN tool in production are summarized. The wear pattern of PCBN tool is observed and its wear mechanism is analyzed. The results show that the failure mode of PCBN tool has normal wear and damage failure, and the main wear forms are micro-disintegrating edge, back face wear and front tool surface wear. The wear mechanism is mainly abrasive wear, bond wear, diffusion wear and oxidation wear, and the main failure modes include breakage, flaking and breaking.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：TG506

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本文編號(hào)：1608838