易切削钢Te元素含量对其切削表面形貌的影响研究

采用硬质合金刀具对三种不同Te元素含量的易切削钢12L14,12L14+Te(0.017),12L14+Te(0.05)进行切削实验,研究其已加工表面形貌状态及原因。试验研究结果表明：12L14+Te(0.017)材料的已加工表面最光滑,粗糙度值最小;12L14+Te(0.05)材料的已加工表面最粗糙,微观形貌显示存在较多撕裂;切削不含Te元素的12L14材料时,已加工表面形貌与粗糙度值介于二者之间;添加Te元素材料会生成MnTe等熔点较低的化合物,在切削中起到应力集中源的作用,易导致已加工表面出现微观撕裂现象,但同时减小了刀具积屑瘤形成的可能,所以易切削钢切削表面形貌的生成是二者因素综合影响的结果。     

陶瓷刀具干切削淬硬钢的研究

通过采用陶瓷刀具对８６ＣｒＭｏＶ７淬火态轧辊钢进行干切削试验,分析了干切削淬硬钢的特点,研究了陶瓷刀具材料及刀具几何参数的优选、刀具磨损特性及Ｔ┐Ｖ规律、加工表面粗糙度等,得出了对实际加工具有指导和参考作用的结论。     

陶瓷刀具高速车削铸铁切削性能实验研究

针对陶瓷刀具和铸铁材料的切削特点,从切削力、切削温度、表面粗糙度、切屑形态和刀具磨损5个方面进行铸铁高速车削实验研究。首先采用单因素实验,分析切削参数对切削力、切削温度、表面粗糙度的影响,并对切屑形貌进行分析探讨;进而采用正交实验进一步分析切削参数对切削加工性能影响的显著程度,并优选出最佳切削参数;最后在正交实验的基础上,对刀具磨损情况进行分析,证明陶瓷刀具高速车削铸铁的合理性。实验结果为进一步研究铸铁的高效切削、刀具磨损以及切削参数优化、新型陶瓷刀具的开发提供技术支持。     

YG8硬质合金刀具干切削铝合金表面粗糙度及刀具磨损研究

采用YG8硬质合金刀具对铝合金进行干切削正交试验,采用共聚焦显微镜测量加工表面粗糙度,分析切削参数进给量、切削速度、背吃刀量对铝合金加工表面粗糙度的影响规律。结果表明:进给量对加工表面粗糙度影响较大,其次是切削速度,而背吃刀量的影响相对较小。采用扫描电子显微镜(SEM)观察刀具磨损表面形貌,采用能谱分析仪(EDS)对刀具磨损表面进行元素分析,分析研究了刀具磨损机理。     

绿色加工中刀具磨损对表面粗糙度影响的研究

在切削镍基高温合金材料过程中,由于不稳定因素造成已加工表面粗糙度很难控制,尤其是刀具磨损直接影响着表面粗糙度。通过对冷风油雾、冷风和常温油雾等不同冷却切削条件下刀具磨损和工件表面粗糙度微观形貌的实验,研究了高速切削镍基高温合金材料时,在不同冷却切削条件下刀具磨损对工件表面粗糙度的影响,揭示了用冷风高速切削提高表面加工质量的规律。     

SiC_p/Al复合材料的超精密车削试验

试验研究了碳化硅颗粒增强铝基复合材料(SiCp/Al)的超精密车削加工性能.使用扫描电镜(SEM)对已加工表面、切屑及其根部、刀具前/后刀面磨损带进行观察,使用表面粗糙度轮廓仪对各种切削条件下的加工表面粗糙度轮廓进行测试分析.结果表明,该材料的加工表面常残留微孔洞、微裂纹、坑洞、划痕、残留物突起及基体材料撕裂等微观缺陷,刀具几何参数、切削速度、进给量、增强颗粒尺寸和材料体积分数是影响表面粗糙度的主要因素.由于切削变形区微裂纹动态形成的作用,超精密切削该材料时一般形成锯齿型切屑.刀具-工件的相对振动、基体撕裂增强颗粒拔出、破碎、压入等是该材料超精密车削表面形成的主要机制.单晶金刚石(SCD)刀具主要发生微磨损、崩刃、剥落和磨粒磨损,聚晶金刚石(PCD)刀具主要发生磨粒磨损和粘结磨损.结论表明SiCp/Al的超精密切削加工性较差,但通过选择合适的工艺参数,体积分数为15%的SiCp/2024Al加工表面粗糙度Ra可达24.7 nm.     

1Cr11Ni23Ti3MoB不锈钢切削加工性能试验分析

对1Cr11Ni23Ti3MoB奥氏体热强不锈钢的切削加工性能进行试验分析,采用二次正交旋转组合试验设计方法,研究切削速度、进给量、切削深度等工艺参数对刀具磨损和加工表面粗糙度的影响规律.分析结果表明,采用涂层刀具切削1Cr11Ni23Ti3MoB不锈钢时,磨损机制主要包括磨损初期的前刀面月牙洼磨损和剧烈磨损阶段的涂层剥落.刀具磨损量与切削深度、切削时间为正相关,与进给量、切削速度为负相关,对刀具磨损量影响最大的工艺参数是切削深度.加工表面粗糙度值随切削速度的提高和切削深度的增大而减小,随进给量的增大而增大,对加工表面粗糙度影响最大的工艺参数是切削速度.     

不同金属夹杂物对曲轴钢加工过程中刀具磨损及表面完整性的影响

研究了六种含有不同夹杂物曲轴钢的车削性能,开展了车削刀具磨损试验,并在线采集切削力,刀具后刀面磨损VB值和工件表面粗糙度每20min记录一次。通过扫描电镜和能谱仪对刀具磨损机理进行研究,同时用光学显微镜测量表面完整性。刀具磨损初期以磨粒磨损和涂层剥落为主;刀具进入稳定磨损阶段,出现崩刃和积屑瘤,崩刃引起的破损是刀具磨损加剧进而失效的主要原因。以氧化铝形式存在的铝夹杂物在车削中加剧了破损,使刀具寿命和表面完整性恶化。选用锰夹杂物作为固体润滑剂,延长了刀具寿命,提高了曲轴钢的切削性能。在曲轴钢的车削过程中,表面完整性与刀具磨损密切相关,刀具磨损越小,表面粗糙度越低,加工质量越好。     

CBN刀具材料的发展及其切削性能研究进展

主要介绍了多晶CBN(PCBN)材料的发展现状和前景以及作为刀具材料的机械性能和切削性能,包括PCBN材料的硬度和横向断裂强度,以及在切削加工中的刀具磨损、切削力和加工工件表面粗糙度。研究发现,切削速度对PCBN刀具切削加工性能的影响较大,其次是刀尖钝圆半径。新型无结合剂PCBN刀具材料的切削性能优于含结合剂的普通PCBN,其切削过程受工艺参数影响较小,刀具磨损和切削力也相对较小,从而能够得到精度更高的加工表面。此外,对PCBN刀具在黑色金属超精密加工中的已有研究结果及发展方向进行了分析。     

奥-贝球墨铸铁加工表面质量的试验研究

用试验的方法研究了奥－贝球墨铸铁的加工表面形态、已加工表面粗糙度，分析了切削用量和刀具几何角度对加工表面粗糙度的影响．结果表明，已加工表面质量与刀具切削刃不平整及材料组织有关。为提高加工表面质置，必须优选切削参数，重视刀具磨损、后刀面粗糙度及工件材料组织的缺陷。     

Experimental study and modelling of tool temperature distribution in orthogonal cutting of AISI 316L and AISI 3115 steels

Cutting tool temperature distribution was mapped using the IR-CCD technique during machining of carbon steel AISI 3115 and stainless steel AISI 316L under orthogonal cutting conditions using flat-face geometry inserts. The effect of work material treatment on tool temperature was investigated, and the results showed that AISI 3115 in heat-treated state displayed higher tool temperature than the as-rolled state. Stainless steel 316L with high sulphur content (0.027?wt.%) and calcium treatment displayed lower cutting tool temperature than the variant with low sulphur (0.009?wt.%). The experimental results were compared with theoretical tool temperature distributions based on a modified version of Komanduri and Hou??s analytical model. In particular, variable frictional heat source and secondary shear were introduced and modelling of the tool stress distribution on rake surface was also considered.     

预硬型塑料模具钢切削加工性的研究

通过选取两种典型的预硬型塑料模具钢——P20钢与718钢,从切削力、刀具磨损、表面粗糙度等方面进行切削性能对比实验,来分析这类模具钢的加工特性。结果表明,这类材料属较难加工材料,这主要是由于钢中存在大量硬质点,且材料具有较高强度和硬度所致。     

微量润滑油润滑和冷风冷却加工法对高硅铝合金切削面的影响

由于高硅铝合金中含有大量硅结晶粒子,硬度较大的硅结晶粒子在切削中会加速刀具的磨损,所以,其被切削性非常不好。为解决这一问题,以往是使用大量切削油进行切削加工。但是,随着环境意识的提高,大量切削油的使用所造成的环境污染的问题不得不被认识并进行改变。使用对切削点进行微量植物性润滑油润滑和冷风冷却的方法进行研究,探讨对高硅铝合金切削面的影响。并因此探讨半干式切削加工的可行性。     

过共晶铝硅合金组织对切削加工性能的影响

为分析过共晶铝硅合金组织对其切削加工性能的影响,对两种化学成分相同但是组织结构不同的过共晶铝硅合金进行了切削试验研究并探讨了其切削机理。试验结果表明：过共晶铝硅合金经变质处理后组织中初晶硅的大小、形状和分布状况对切削刀具寿命和合金的切削加工表面质量影响极大,具有细小、分散而形状圆钝化初晶硅的合金有比较好的切削性能。造成这种影响的主要原因在于细小的硅粒比较容易协同基体塑性变形和被刀具压入切屑和已加工表面,而粗大的硅块往往发生解理破碎、脱落和位移,直接与刀具发生强烈摩擦并使已加工表面存留许多缺陷。     

Performance of cryogenically treated M35 HSS drills in drilling of austenitic stainless steels

In this study, performance of cryogenically treated M35 high speed steel (HSS) twist drills in drilling of AISI 304 and 316 stainless steels was evaluated in terms of thrust force, surface roughness, tool wear, tool life, and chip formation. To present the differences in tool performance between untreated and treated drills, and machinability between AISI 304 SS and AISI 316 SS, a number of experiments were performed at different combinations of cutting speed, and feed rate. As the results of the conducted experiments, the treated drills showed better performance than untreated drills in terms of thrust force, surface roughness, and tool wear and tool life for both types of stainless steels. Tool lives of treated HSS drills in drilling of AISI 304 SS and AISI 316 SS improved 32% and 14%, respectively, when compared with untreated drills. Experimental results also showed that machinability of AISI 304 SS was harder than the machinability of AISI 316 SS.     

车轴钢冶炼过程中影响氢含量的主要因素分析及其控制

为了提高车轴的抗疲劳性能,改善其质量和使用寿命,对车轴钢中氢气含量提出了要求。本文分析了影响车轴钢中氢含量的众多因素如大气水分、大气相对湿度、废钢和生铁、炉渣性质及渣量、合金添加剂、钢中脱氧剂、钢中氧含量等,提出了在冶炼过程中从各个环节抑制氢气增加的相应措施。     

Influence of cutting condition on white layer induced by high speed machining of hardened steel

White layer formed on machined surface during dry and hard high speed machining has great influence on workpiece performance. Studying machined surface white layer is significant to improve the machinability and surface quality of workpiece. Experiments of dry and hard high speed machining of GCr15 bearing steel and 40CrNiMoA alloy steel were carried out with PCBN inserts, the phase composition and the thickness of white layer were studied experimentally; the formation mechanism of the white layer were studied; effects of cutting parameters, carbon content of substrate material on white layer thickness were analyzed; effects of cutting speed on retained austenite content in machined surface were also summarized. Results show that the microstructure of white layer consists of cryptocrystalline martensite, retained austenite and carbide; the white layer is formed by martensitic transformation; the white layer thickness and the retained austenite content of machined surface increase firstly and then decrease with cutting speed; the white layer thickness increases with flank wear and carbon content.     

EFFECTS OF CUTTING SPEED WHEN TURNING AGE HARDENED INCONEL 718 WITH PCBN TOOLS OF BINDERLESS AND LOW-CBN GRADES

Application of polycrystalline cubic boron nitride (PCBN) tools as an alternative for ceramic and cemented carbide tools in machining superalloys has been frequently identified as a solution for enhancing process efficiency but only a limited number of studies has been done in this area. The current study explores the effect of the cutting speed, which was varied in a wide range (2–14 m/s), on machinability of age hardened Inconel 718 with PCBN tools. Performance of binderless PCBN grade and grade with low-cBN content was evaluated in terms of tool life, tool wear, cutting forces and surface quality. Chip formation and process dynamics were analyzed as well. It was found that low-cBN grade provided 70–90% better surface finish and tool life than the binderless at moderate speeds (5–8 m/s). Performance of both grades at low and high speed ranges was non-satisfactory due to notching and flaking respectively. At low cutting speed adhesive wear plays a major role while as the speed increases a chemical wear becomes dominant.     

高合金不锈钢的干车削和近干车削研究

高合金不锈钢具有强度高、韧性好、耐腐蚀等优良性能而得到日益广泛的应用,但是其难加工性同时也对切削技术提出了更高的要求.干切削因具有对环境和人体无害、经济性好等优点成为金属加工技术的主要发展方向之一.文中对高合金不锈钢Y12Cr17和16Cr17Ni3的干车削和近干车削中,切削参数和切削材料对刀具磨损和工件表面质量的影响进行了深入研究.结果表明,通过选择适当的切削参数、刀具材料以及刀具涂层,可以很好地实现高合金不锈钢的干车削加工,并能获得比传统乳化剂加工更小的磨损值和更好的工件表面质量.     

Machining of sintered steel under different lubrication conditions

Cutting experiments of sintered steel Fe–2Cu–0.8C under different lubrication/cooling conditions and with different tool materials were performed in order to clarify the reasons for the low machinability of the sintered steel, and investigate the applicability of minimum quantity of lubricant (MQL) to the machining of sintered steel. As a theoretical approach to the short tool life in machining sintered steel, the impacts to the cutting edge caused by micro-voids were theoretically modeled, and it was revealed that the cutting edge suffered from impacts at a very short interval causing high cycle fatigue. Extremely short tool life in dry machining of sintered steel already used for wet machining proved that coolant definitely increased the stress amplitude in high cycle fatigue. Application of the air jet to a tool showed the positive effect in reducing tool wear. This indicated the possibility that micro-cracks nucleated by high cycle fatigue were healed by oxidation. MQL cutting with small amount of oil and air jet is proved to be acceptable for machining sintered steel from the results of cutting experiments using uncoated and coated carbide and cermet tools. Finally, it is confirmed that thick coating of a carbide tool is effective for dramatically improving the machinability.