切削方向毛刺/亏缺的形成及其界限转换

基于切削方向毛刺/亏缺的形成过程,利用最小能量原理,建立切削方向毛刺/亏缺的数学模型,初步确定了切削方向毛刺/亏缺形态界限转换的基本准则。     

金属切削毛刺的预测预报技术研究

系统概括了国内外时金属切削毛刺的预报预测研究现状,分析了有限元法在毛刺形成过程、形态度尺寸大小和界限转换条件的定量或定性预测预报中的具体应用,为系统深入地研究切削毛刺提供了理论基础.     

金属切削毛刺的预测预报技术研究

金属切削毛刺是切削加工中产生的常见现象,它严重地影响着产品的精度和使用性能,有必要对毛刺的预测预报进行深入系统的研究.系统地概括了国内外对金属切削毛刺的预报预测研究现状,分析了有限元法在毛刺形成过程、形态及尺寸大小和界限转换条件的定量或定性预测预报中的具体应用,为系统深入地研究切削毛刺奠定了坚实的理论基础.     

精密加工中切削参数对毛刺尺寸的影响

毛刺的产生是金属切削加工中长期存在的问题,在实验的基础上通过对精密车削中进给方向毛刺的研究,分析了切削参数对毛刺尺寸的影响,为毛刺生成机理的研究以及毛刺的抑制和去除做了部分基础性工作。     

微切削毛刺形成机理及研究进展综述

概述了微切削毛刺的形态、分类及其生成机理;阐述了微切削毛刺的仿真分析研究进展;在微切削毛刺的试验研究进展方面,分析了切削工艺参数、刀具几何、切削方式和辅助工艺对微切削毛刺的影响;介绍了几种常用复合材料加工毛刺的研究现状;根据毛刺的成形机理和加工方式,综述了去除毛刺的工艺方法与设备,提出了去毛刺装置的性能要求;最后总结了微细毛刺研究方面的不足,并指出了将来研究的方向。     

精密加工中切削参数对毛刺尺寸的影响

毛刺的产生是金属切割加工中长期存在的问题,在实际的基础上通过对精密车削中进给方向毛刺的研究,分析了切削参数对毛刺尺寸的影响,为毛刺生成的研究以及毛刺的抑制和去除做了部分基础性工作。     

控制切削毛刺的基本措施

金属零件在切削加工过程中常会产生毛刺，毛刺的存在将严重地影响零件或产品的质量。影响毛刺生成的因素很多，如何防止和减少金属切削毛刺，应根据具体情况，采取相应措施。现就这一问题作一简要探讨性综述。一、从零件设计上避免生成毛刺1．选择合适的工件材料工件材料的物理机械性能对毛利的生成有很大影响，如变形硬化指数，延伸率，硬度和抗拉强度等。因此，在零件设计时，在满足强度要求的条件下，应尽可能的选用变形硬化指数和延伸率较小的材料，以减少金属切削加工时毛刺的生成。2采用合理的零件结构形状在金属切削加工中，毛刺主要…     

金属切削毛刺分类体系的研究及其应用

将金属切削毛刺生成同切削运动联系起来，提出并建立起切削运动－刀具切削刃毛刺分类体系，清晰地给出影响毛刺生成及变化的主要因素。将该分类体系应用于车削、钻削和磨削加工，表明切削运动－刀具切削刃毛刺分类体系定义明确、完整。简便易行。     

毛刺形成中的韧性断裂条件及影响

在不同的切削条件下工件的棱边会形成毛刺与亏缺两种不同的形态。亏缺的形成同样影响着工件的精度与使用性能。基于Normalized CockroftLatham断裂准则建立了毛刺与亏缺形成的有限元热-力耦合模型,通过模拟结果分析,得出毛刺的形成主要由工件终端部材料的大塑性变形而产生,亏缺的形成主要由工件已加工面材料的大塑性变形造成的韧性断裂产生。并通过不同的切削条件模拟,得出了形成亏缺的界限条件。切削实验结果表明:模拟结果中的界限条件与实验结果接近。毛刺、亏缺形成有限元模型的建立为进一步深入研究其形成机理提供了一条有效的途径,其模拟结果为工件棱边质量的控制提供参考。     

微细切削毛刺发展研究

微细切削加工中形成的毛刺严重降低了被加工微型零部件的精度和棱边质量,影响了工件的使用性能,对微细切削的毛刺研究有利于推动微细切削技术的发展。系统概述了国内外微细切削毛刺的研究进展,重点阐述了研究者对微细切削毛刺形成机理、影响因素及预测预报技术的研究,并在分析微细切削特殊切削环境的基础上,结合尺度效应理论研究了微细切削毛刺的形成机理,指出了微细切削毛刺研究尚存的主要问题,同时确立了今后深入开展微细切削毛刺研究的发展方向。     

金属切削毛刺数据库系统的设计

毛刺的产生和存在是金属切削加工中普遍存在的问题 ,它直接影响了工件的加工精度及质量。基于数据库和Java ,研究了金属切削毛刺数据库系统的设计 ,实现了切削毛刺数据的管理、切削毛刺类型与尺寸大小及加工参数的查询 ,进一步丰富和完善了金属切削毛刺的预报与控制理论。     

Defining the effects of cutting parameters on burr formation and minimization in ultra-precision grooving of amorphous alloy

Amorphous nickel phosphorus (Ni-P) alloy is a suitable mold material for fabricating micropatterns on optical elements for enhancing their performances. Ultra-precision cutting is preferred to be used to machine the mold material for high precision in a large workpiece. However, burrs and chippings always form and are detrimental especially when fabricating micropatterns. The formation mechanisms of burrs and chippings have not yet been revealed precisely in the cutting processes of amorphous alloys, because their cutting behavior is more complex and less discussed in existing researches than that of crystalline metals. In the present study, the burr formation process of amorphous Ni-P is defined and a three-dimensional cutting model using energy method is proposed to predict and minimize burrs and chippings. Microgrooving experiments were conducted with different undeformed chip geometries using three types of cutting tools to observe burr formation processes. Large burrs and chippings were formed when cutting with a tapered square tool and a tilted triangle tool. These large burrs and chippings were found to be induced by large slippages that are unique to amorphous alloys. It was revealed that burrs and chippings appear when the angle between the chip flow direction and the groove edge is less than a critical value. Energy method was used to predict the chip flow directions and the calculated results agree with the experimental ones, which proved that the energy method is valid for designing an appropriate undeformed chip geometry to reduce burrs and chippings in ultra-precision grooving.     

纳米多晶铜单点金刚石切削亚表层损伤机理

基于Poisson-Voronoi和Monte Carlo方法构建了多晶铜分子动力学模型,研究了纳米切削中多晶铜材料去除、切削力变化及晶界与位错间的相互转化机制。研究结果表明：晶界的阻碍作用使得切屑流向发生了改变,并在已加工表面形成凹槽和毛刺;切削过程中晶界前方材料变形能的逐渐积聚及晶界的最终断裂,造成了切削力发生由最大峰值到最小谷值的大幅波动;晶界附近的材料去除经历了材料变形积聚、位错穿越晶界、晶界转变为位错及晶界最终断裂等过程。通过详细分析多晶铜纳米切削中位错与晶界间的演化过程,揭示了晶界与位错间的相互转化机制,丰富了多晶铜亚表层损伤机理的内涵。     

Study on burr occurrence and surface integrity during slot milling of multidirectional and plain woven CFRPs

Machining carbon fiber reinforced composite (CFRP) is often accompanied with cutting edge defects and surface damage including interlayer delamination, cavities and debonding of fiber-matrix. A detailed understanding of the effect of fiber configuration and cutting parameters on cutting force, burr occurrence/formation and surface integrity is necessary. In this paper, experimental data is presented relating to fiber burrs on entry surface, cutting force, surface roughness and workpiece integrity when slot milling CFRP laminates with varying fiber configurations (0°/90°, 45°/135° and plain woven) at different cutting speed (60 and 120 m/min) and feed rate (0.05 and 0.1 mm/rev). Lateral cutting force is recorded down to 56 N and highly dependent on fiber orientation. The length (up to ~?5.6 mm) and amount of fiber burrs are highly related to fiber orientation and fiber cutting angle. Surface roughness Ra down to ~?1.4 μm was recorded when milling type 2 (45°/135°) and type 3 (plain woven) laminates. Various surface defects predominantly occurred due to different cutting conditions and fiber configurations, which are mainly located in the layers with fibers orientated at 45°/135°. The occurrence and propagation of fiber burrs and surface cavities were also investigated based on different fiber fracture mechanisms.     

巴氏合金轴瓦内表面镜面加工

轴瓦刮削加工不同于车削加工,它是在主、副偏角均为0°,即在主、副切削刃成为一条切削刃,刮削刀刃微量吃刀深度的情况下,在被加工表面的全长上,同时去除材料的一种加工方法,因此理论上在加工表面没有残余面积存在。在刮削加工过程中,刀刃对已加工表面还产生挤压,碾压光刮削刃产生的鳞刺,使被加工表面质量进一步提高。刮削后的表面可达到镜面(粗糙度值Ra0.1μm)。     

少无毛刺切削技术的研究进展

在系统概述国内外少无毛刺切削加工技术研究进展的基础上,根据机械加工实际需要,给出了主动控制或减小金属切削毛刺的基本原则,探索出少无毛刺的主要途径。此外,分析了几种切削加工技术的具体应用。指出了目前尚需解决的一些主要问题,确立了今后深入开展金属切削毛刺研究的方向。     

考虑左旋切削刃切削连续性的碳纤维增强树脂基复合材料铣削研究

采用右旋切削刃铣刀加工碳纤维增强树脂基复合材料（CFRP）时,纤维层受单向轴向力作用而易产生分层、毛刺等损伤,采用左右旋切削刃共存的多刃微齿铣刀对纤维层施加双向轴向力能有效抑制损伤,但如何保证每层纤维都受到左右旋切削刃的切削作用成为抑制损伤的关键。以多刃微齿铣刀为研究对象,通过设计不同的分屑槽螺旋角,获得左旋切削刃切削面积连续、重叠及未连续三种类型的铣刀。通过实验研究发现：切削面积连续时,CFRP加工表面有少量毛刺及翻边;切削面积重叠时,CFRP加工表面无毛刺及撕裂损伤,效果最好;切削面积未连续时,加工表面有大量毛刺和撕裂损伤;此外,表面粗糙度值会随着分屑槽螺旋角的增大而增大。     

Effects of cutting edge radius and fiber cutting angle on the cutting-induced surface damage in machining of unidirectional CFRP composite laminates

Carbon fiber reinforced polymer composite laminates are anisotropic, inhomogeneous, and mostly prepared in laminate form before undergoing the finishing operations. The edge trimming process is considered as one of the most common finishing operations in the industrial applications. However, the laminate surface is especially prone to damage in the chip formation process, and the most common damage mode is burrs. Burrs may increase cost and production time because of additional machining; they can also damage the surface integrity. Many studies have been done to address this problem, and techniques for reducing burr size in material removal process has been the focus of the research. Nonetheless, the combined effects of the cutting edge radius and the fiber cutting angle on the burr formation have seldom been conducted, which in turn restricts to find out the mechanism of burr formation. The purpose of the present paper is to study the particular mechanism that leads to burr formation in edge trimming of CFRP laminates and investigate the effects of fiber cutting angle and cutting edge radius on burr formation. The results indicate that the burrs are prone to form in the fiber cutting angle range of 0° < χ < 90° when a large cutting edge radius of the tool is used for both milling and drilling of CFRP composites.     

PTFE材料正交切削切屑成形特性研究

为了研究PTFE材料在切削过程中的成屑机理,设计了单因素正交切削实验以及准静态力学实验。首先,基于剪切平面理论和断裂理论,以切削速度、切削厚度为变量,提出了PTFE材料的连续切屑及切屑毛边成形机理;然后通过分析毛边高度和间距,探究切削参数对毛边形态的影响规律;最后,利用分形理论对切削力稳定性进行分析,揭示了毛边数量、出现频率与切削力稳定性的关系。结果表明,PTFE连续切屑的产生是因为切削过程中材料真实压缩应变未超过断裂屈服应变,毛边的产生则是因为切屑边缘片层状结构处裂纹的形核与扩展。此外,切削参数会影响毛边生成,在切削速度100 mm/min、切削厚度0.3 mm工况下,切屑毛边数量最少、出现频率最小,切削力最稳定。研究结果可为PTFE材料切削过程毛边抑制和表面加工质量优化提供参考。