共查询到20条相似文献,搜索用时 62 毫秒
1.
2.
在能源动力、汽车、航空航天、模具制造等关键零部件的加工过程中,球头铣刀因其特有的刀具几何结构,常作为零件加工的最终成型刀具。考虑到在球头铣刀立铣加工中不同的刀具与工件相对姿态会对切削过程产生不同的影响,本文研究切屑形成和不同走刀方式下切削过程中各物理量(切削力、切削温度等)的变化情况,结合有限元仿真技术在切削加工中的应用,建立硬质合金球头铣刀铣削斜面的有限元模型,模拟相同切削参数下,八种不同走刀方式的球头铣削过程,分析刀具切入切出工件时切屑的形成过程,探究切削力和切削温度的变化规律。仿真结果表明:不同的走刀方式,平均切削合力各不相同,同时切屑和工件的最大切削温度也出现较大差异,而斜坡上坡逆铣的走刀方式所对应的平均切削合力和最大切削温度均最优。 相似文献
3.
4.
根据螺旋刃球头铣刀的几何模型,考虑切削加工时刀齿的有交切削区及再生效应,建立球头铣刀的单刃切削力模型;进行模态实验和参数识别,建立螺旋刃球头铣刀的动力学模型;在Matlab环境下,基于龙格-库塔法对球头铣刀铣削加工过程稳定性进行仿真,结果表明:该模型能很好地描述切削过程中的稳定性及振动等动学特性,对于实际铣削加工过程及实验机的优化设计具有指导意义。 相似文献
5.
针对定尺寸盘形铣刀准对称铣削螺杆定子内螺旋面的切削方法,建立了铣削加工的几何模型,根据塑性理论推导出切削力预测的计算公式。采用有限元方法对切削过程进行了建模仿真。在相同切削参数下,对仿真结果和预测公式计算结果进行比较,为机床传动机构设计和切削参数优化提供了数据支持。 相似文献
6.
7.
8.
9.
目的揭示微细铣削下的切削深度ap、进给量f、切削速度v对不锈钢310S表面完整性的影响规律,为优化不锈钢310S的切削工艺提供参考。方法基于响应曲面方法,采用涂层硬质合金微直径铣刀,对不锈钢310S进行了铣削加工试验,对表面粗糙度、表面形貌和显微硬度的数据和信息进行采集并分析,进行多元非线性回归,建立了表面粗糙度Ra与切削参数之间的映射关系,对多元回归方程进行了显著性检验。结果得到切削参数ap、v、f显著度分别为0.099、0.620、0.011。基于曲面响应法的试验数据及数学模型,直观地绘制了ap、v、f对表面粗糙度Ra、表面形貌和显微硬度的影响规律图。结论在一定的切削加工参数范围内,进给量f对微细铣削不锈钢310S表面粗糙度Ra的影响最显著,其次是切削深度ap,切削速度v的影响最小。表面留有摆线状加工痕迹,顺铣侧的残留物分布多于逆铣侧。切削深度ap对310S试件表层显微硬度的影响最显著,其次是切削速度v。减小进给量f是降低不锈钢310S表面粗糙度的有效加工方法。 相似文献
10.
根据齿轮滚齿时产生的径向误差Fr对剃齿后切向误差Fr影响的分析,指出现场生产中必须加强剃齿前对滚齿径向误差Fr的控制,用以提高齿轮剃齿精度. 相似文献
11.
M.T. Zaman A. Senthil Kumar M. Rahman S. Sreeram 《International Journal of Machine Tools and Manufacture》2006,46(3-4):353-366
In the present day manufacturing arena one of the most important fields of interest lies in the manufacturing of miniaturized components. End milling with fine-grained carbide micro end mills could be an efficient and economical means for medium and small lot production of micro components. Analysis of the cutting force in micro end milling plays a vital role in characterizing the cutting process, in estimating the tool life and in optimizing the process. A new approach to analytical three-dimensional cutting force modeling has been introduced in this paper. The model determines the theoretical chip area at any specific angular position of the tool cutting edge by considering the geometry of the path of the cutting edge and relates this with tangential cutting force. A greater proportion of the helix face of the cutter participating in the cutting process differs the cutting force profile in micro end milling operations a bit from that in conventional end milling operations. This is because of the reason that the depth-of-cut to tool diameter ratio is much higher in micro end milling than the conventional one. The analytical cutting force expressions developed in this model have been simulated for a set of cutting conditions and are found to be well in harmony with experimental results. 相似文献
12.
13.
Chatter suppression in micro end milling with process damping 总被引:1,自引:0,他引:1
Ramin Rahnama Mozhdeh Sajjadi Simon S. Park 《Journal of Materials Processing Technology》2009,209(17):5766-5776
Micro milling utilizes miniature micro end mills to fabricate complexly sculpted shapes at high rotational speeds. One of the challenges in micro machining is regenerative chatter, which is an unstable vibration that can cause severe tool wear and breakage, especially in the micro scale. In order to predict chatter stability, the tool tip dynamics and cutting coefficients are required. However, in micro milling, the elasto-plastic nature of micro machining operations results in large process damping in the machining process, which affects the chatter. We have used the equivalent volume interface between the tool and the workpiece to determine the process damping parameter. Furthermore, the accurate measurement of the tool tip dynamics is not possible through direct impact hammer testing. The dynamics at the tool tip is indirectly obtained by employing the receptance coupling method, and the mechanistic cutting coefficients are obtained from experimental cutting tests. Chatter stability experiments have been performed to examine the proposed chatter stability model in micro milling. 相似文献
14.
1 INTRODUCTIONTitaniumdioxideisknowntoexistinthreecrys tallineformsofrutile ,anataseandbrookiteinnature .Rutileisthermodynamicallystablewhileanataseandbrookitecantransformirreversiblyandexothermicallytorutileoverarangeoftemperatures[1] .Inaddition ,therearetwohigh pressurephases ,srilankitewithorthorhombicstructureandTiO2 Ⅲ .Underhighpressure ,anataseandrutilecantransformtosri lankite[2 4 ] .Thesrilankitephasecantransformbacktorutileunderappropriateconditions[5] .Overthepastfew years … 相似文献
15.
球磨工艺对球磨粉末及其烧结组织的微观结构和形态都有重要的影响。本实验采用低能和高能球磨两种方式对Ti-Al-0.2B wt.%合金粉末进行球磨,研究球磨过程中粉末组织和形态的变化,并将球磨后的粉末进行热压烧结,研究不同球磨方式对烧结组织中原位合成TiB增强相形态的影响。研究结果表明:低能球磨过程中粉末颗粒间有机械合金化发生,其烧结组织中生成的TiB为细长态,在基体中分布均匀,没有联结的粗晶或成簇生长现象。对于高能球磨,粉末颗粒细化效果明显,颗粒平均尺寸降至1 μm,球磨过程中除了机械合金化还形成了Ti(Al)过饱和固溶体,并在球磨后期形成了非晶结构。经高能球磨的粉末烧结后,组织中生成了均匀分布的纳米级TiB晶须。 相似文献
16.
QU Shengguan LI Xiaoqiang LI Yuanyuan HU Lianxi WANG Erde 《稀有金属(英文版)》2006,25(1):21-26
A TiAl alloy was fabricated by high-energy ball milling and subsequent reactive sintering from the mixed powders of Ti and Al. High-energy ball milling produced a kind of particular composite powders with an extremely fine altemative Ti and Al lamella structure. The composite powders not only possessed good consolidation and densification characteristics, but also resulted in the augment of nucleation rate of α and γ titanium aluminides during solid-phase reactive sintering After a series of processing, pressing, degassing, extrusion, and sintering, the resultant TiAl alloy presented high relative density and refined grain sizes of (α2 + γ) lamella and γ phases. The compressive yield strength of the sintered TiAl reached 600 MPa at 800℃. 相似文献
17.
WC粉体的高能球磨超细化 总被引:2,自引:1,他引:2
采用高能球磨工艺对WC粉体进行超细研磨。研究了粉体颗粒度及晶粒度的大小随球磨时间的变化关系。发现随球磨时间的增加 ,粉体颗粒度不断细化 ,最后趋于稳定 (0 .4μm) ;粒度分布曲线出现明显的三峰特征 ,分别位于细 (微米 )区、超细 (亚微米 )区和极细 (纳米 )区。研磨细化的WC粒子具有纳米晶 (1 0nm)结构。探讨了WC粉体高能球磨细化机理与纳米晶结构特性。 相似文献
18.
Won Tae Kwon Deokki Choi 《International Journal of Machine Tools and Manufacture》2002,42(15):1649-1655
Radial immersion ratio is an important factor to determine the threshold for tool conditioning monitoring and automatic force regulation in face milling. In this paper, a method of on-line estimation of the radial immersion angle using cutting force is presented. When a tooth finishes sweeping, a sudden drop of cutting force occurs. This force drop is equal to the cutting force that acts on a single tooth at the swept angle of cut and can be obtained from the cutting force signal in feed and cross-feed directions. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the immersion angle is a function of the immersion angle and the ratio of radial-to-tangential cutting force. In this study, it is found that the ratio of radial-to-tangential cutting force is not affected by cutting conditions and axial rake angle. Therefore, the ratio of radial-to-tangential cutting force determined by just one preliminary experiment can be used regardless of the cutting conditions for a given tool and workpiece material. Using the measured cutting force during machining and a predetermined ratio, the radial immersion ratio is estimated in the process. Various experiments show that the radial immersion ratio and instantaneous ratio of the radial to tangential direction cutting force can be estimated very well by the proposed method. 相似文献
19.
研究了不同球磨时间条件下CNTs辅助球磨对Zr粉形貌和氧化性能的影响。采用XRD和SEM分析了球磨过程中Zr粉的物相组成和形貌演变,采用热重(TG)法评估了Zr粉的氧化性能。结果表明:添加CNTs辅助球磨对Zr粉的物相组成没有影响,但是会影响Zr粉的形貌和氧化性能。不添加CNTs时,随着球磨时间的增加(1 h~3 h),Zr粉粒径持续减小,球磨3 h后,Zr粉粒径由十几 μm减小到2~3 μm。添加CNTs辅助球磨后,Zr粉的颗粒细化过程滞后,球磨初期(1 h~2h),Zr粉粒径没有显著变化,直到球磨时间延长到3 h时,Zr粉粒径才开始明显减小。这是因为CNTs在Zr颗粒表面的黏附和CNTs在Zr粉中的团聚阻碍了磨球对Zr颗粒的机械冲击和破碎作用。与直接球磨Zr粉相比,当所得Zr粉粒径相差不大时,添加CNTs辅助球磨使Zr粉的起始氧化温度和峰值氧化温度降低了11 ℃ ~37 ℃,这是因为CNTs的良好导热性促进了Zr粉氧化过程中的传热。另一方面,球磨时间少于2 h时,Zr/CNTs混合物中Zr粉的氧化增重量比纯Zr粉的增重量略有降低,但球磨时间超过2 h时,这种趋势出现反转。前者是因为短时间球磨时,CNTs引起Zr粉的局部团聚,阻碍了团聚体中Zr粉与氧气的接触,并且混合物中的Zr粉颗粒还没有被明显细化,这都降低了Zr粉的氧化程度;随后的反转趋势是因为球磨时间增加后,混合物中的Zr粉开始明显细化,促进了其氧化反应的进行,但是纯Zr粉由于颗粒尺寸提前细化而发生了显著的自发氧化,降低了活性Zr的含量。 相似文献
20.
1 INTRODUCTIONSincethediscoveryoftheuniaxialNd2 Fe14 Bcompoundin 1983[1,2 ] ,theNdFeBalloyshavebeenwidelyusedforpermanentmagnetapplicationsowingtotheirexcellentmagneticproperties ,suchashighcoercivity ,high energy products[3,4 ] .Intheserareearthpermanentmagnets ,afurtherexcitingrecentdevelopmentisthesuggestionofnano compositeex changemagnetscombiningthelargecoercivitiesinhardmagnetswithlargeinductionsfoundinsoftertransitionmetalmagnets[5,6 ] .Indeed ,thenano com positemagnetshavebeent… 相似文献