高速切削切屑折断界限变化规律

为进行高速切削切屑折断界限变化规律研究,采用具有代表性的三维复杂槽型车刀片进行11种常速、高速断屑试验.在分析试验数据基础上,得到切屑折断界限曲线及其共性切屑折断界限曲线.在对三次样条函数插值方法进行分析,以及应用二次、三次多项式拟合方法建立切削速度与极限进给量、断屑范围之间变化规律的数学模型的基础上,优选出误差小、计算简单的数学模型.发现在各种切削速度下极限背吃刀量是定值,并且极限背吃刀量曲线是垂直直线,为此建立新的极限背吃刀量数学模型.结合具有代表性的三维复杂槽型车刀片,研究极限进给量变化规律,并推导出极限进给量理论预报公式.三维复杂槽型切屑折断界限曲线及其数学模型的建立,可为今后高速切削领域里三维复杂槽型车刀片断屑机理及其预报系统的研究打下理论与试验基础.     

基于WTK软件的切屑形成与折断过程虚拟现实的研究

采用虚拟现实 (VR)技术 ,以 VC++6 .0和虚拟现实软件 World Tool Kid9.0为开发平台 ,以切屑折断数学模型为理论研究基础 ,对于给定的切削参数 ,实现了三维复杂槽型刀片在车削加工时切屑形成与折断过程的虚拟现实 ,预报了切屑折断过程 ,从而可评估切削刀片槽型设计质量 ,优选槽型 ,有利于缩短刀片设计和制造周期     

形成切屑上向弯曲非折断插入区的理论研究

切屑控制是现代先进机械制造系统中的基础关键技术 ,切屑控制问题不解决 ,任何一个理想的自动化过程都不能实现。本文以切屑空间运动轨迹理论为基础 ,探讨切屑与工艺系统障碍物的约束关系 ,建立判断其接触与否的约束方程 ;以影响上向弯曲插入区形成的主要因素———主偏角为主线 ,探讨其对切屑卷曲的影响规律 ;最后判断切屑上向弯曲非折断插入区域 ,并给出避免此区域生成的切屑折断条件。     

形成切屑上向弯曲非折断插1入区的理论研究

切屑控制是现代先进机械制造系统中的基础关键技术,切屑控制问题不解决,任何一个理想的自动化过程 都不能实现。本文以切屑空间运动轨迹理论为基础,探讨切屑与工艺系统障碍物的约束关系,建立判断其接触与 否的约束方程;以影响上向弯曲插入区形成的主要因素——主偏角为主线,探讨其对切屑卷曲的影响规律;最后判 断切屑上向弯曲非折断插入区域,并给出避免此区域生成的切屑折断条件。     

复杂槽型车刀片切屑约束与折断预报的研究

在刀片槽型结构对切屑约束的影响研究基础上,建立了复杂槽型车刀片切屑约束与折断预报模型,提出了基于切屑约束的复杂槽型车刀片切屑卷曲与折断预报方法,并进行了三维复杂槽型车刀片切屑约束与折断的试验研究。结果表明:该模型对于复杂槽型车刀片断屑性能的预报和刀片槽型的优选具有实际应用价值。     

蠕墨铸铁铣削过程的研究

本文旨在探讨在VDL-600A立式加工机床上使用KC72S刀具对蠕墨铸铁进行铣削时,铣削速度、进给量和背吃刀量对切削力的影响。通过对当前蠕墨铸铁铣削切削力研究现状的分析,发现铣削速度是对切削力影响最为显著的因素。较高的铣削速度会导致更大的切削力,这可能是由于高速铣削时刀具与工件之间的摩擦力增加所致。相比之下,背吃刀量和进给量对切削力的影响相对较小。这可能是因为这两个因素对切削过程中刀具与工件之间的接触面积变化不大。对蠕墨铸铁进行铣削时,需要着重考虑调整铣削速度,相对而言,背吃刀量和进给量的调整对切削力影响较小。     

超精密车削切削力的试验研究

通过超精密车削试验 ,分析了微薄切削时进给量和背吃刀量对切削力的影响规律 ,指出吃刀抗力Ft的特殊变化将直接影响加工表面粗糙度 ,为保证超精密加工表面质量 ,应在合理范围内选取刀具进给量     

切屑空间运动轨迹及其约束方程的研究

切屑控制技术是现代先进机械制造系统中的基础关键技术,切屑　控制技术不解决,任何一个理想的自动化过程都不能实现。系统研究了切屑的空间运动轨迹　,获得了切屑空间运动轨迹数学模型;建立了切屑在形成过程中与障碍物（工件及刀具）表面　的约束方程。上述研究成果是研究切屑形成与折断过程的有效途径,为进行刀片槽型优选及　设计以及切屑折断预报系统的研制奠定理论基础。     

横向卷曲短螺卷屑折断数学模型与折断判据

借助于高这摄影技术对在金属切削加工中产生的横向卷曲短螺卷悄的形成进行了分析，并根据动力学原理对切用形成过程中的受力与行断进行了研究，建立了数学模型，并提出了切屑折断判据。     

切屑的折断对切削力的影响

通过实验阐述了切屑折断时对Ｘ、Ｙ、Ｚ三向切削力均有影响。所导致力的波动可达到从其它影响力波动因素的波形中分离出的程度，其反映出的高度与其它振动引起的幅宽度近乎相等。走刀抗力（Ｘ向力）对切屑折断反应最敏感。     

IMPULSIVE CHIP BREAKING IN METAL MACHINING: A PROOF-OF-CONCEPT STUDY

An innovative non-conventional technique, called impulsive chip breaking, is developed in the present study to break difficult-to-break chips that are often generated in machining high toughness or soft gummy materials, such as pure aluminum, pure copper, aluminum alloys, copper alloys, low carbon steels, and stainless steels. These materials have a wide variety of engineering applications. In impulsive chip breaking, the machine tool spindle rotational speed periodically increases to a prescribed higher speed within a set short period of time and then resumes to its normal constant speed to continue machining operations. The experimental investigations covering a range of cutting conditions on a selected work material are preformed to confirm the feasibility of impulsive chip breaking and study its basic mechanism as well as the characteristic variations of machining performances, including the chip morphology, the cutting forces, the machining vibrations, and the surface roughness of the machined workpiece. It is demonstrated that as long as the impulsive rotational speed of the machine tool spindle is appropriately selected or optimized, both requirements of breaking chips and maintaining the machined surface quality can be simultaneously satisfied.     

IMPULSIVE CHIP BREAKING IN METAL MACHINING: A PROOF-OF-CONCEPT STUDY

An innovative non-conventional technique, called impulsive chip breaking, is developed in the present study to break difficult-to-break chips that are often generated in machining high toughness or soft gummy materials, such as pure aluminum, pure copper, aluminum alloys, copper alloys, low carbon steels, and stainless steels. These materials have a wide variety of engineering applications. In impulsive chip breaking, the machine tool spindle rotational speed periodically increases to a prescribed higher speed within a set short period of time and then resumes to its normal constant speed to continue machining operations. The experimental investigations covering a range of cutting conditions on a selected work material are preformed to confirm the feasibility of impulsive chip breaking and study its basic mechanism as well as the characteristic variations of machining performances, including the chip morphology, the cutting forces, the machining vibrations, and the surface roughness of the machined workpiece. It is demonstrated that as long as the impulsive rotational speed of the machine tool spindle is appropriately selected or optimized, both requirements of breaking chips and maintaining the machined surface quality can be simultaneously satisfied.     

A STUDY ON CHIP BREAKING LIMITS IN MACHINING

Prediction of chip breaking in machining is an important task for automated manufacturing. This paper presents a study on chip breaking limits. Based on the chip breaking curve, the critical feed-rate is modeled through an analysis of up-curl chip formation, and the critical depth-of-cut is formulated through a discussion of side-curl dominant chip formation processes. Factors affecting chip-breaking limits are also discussed.

In order to predict the chip breaking limits, semi-empirical models are established. Although the coefficients that occur in the model are estimated through machining tests, the models are applicable to a broad range of machining conditions. The model parameters include machining conditions, tool geometry, and workpiece material properties.     

A STUDY ON CHIP BREAKING LIMITS IN MACHINING

Abstract

Prediction of chip breaking in machining is an important task for automated manufacturing. This paper presents a study on chip breaking limits. Based on the chip breaking curve, the critical feed-rate is modeled through an analysis of up-curl chip formation, and the critical depth-of-cut is formulated through a discussion of side-curl dominant chip formation processes. Factors affecting chip-breaking limits are also discussed.

In order to predict the chip breaking limits, semi-empirical models are established. Although the coefficients that occur in the model are estimated through machining tests, the models are applicable to a broad range of machining conditions. The model parameters include machining conditions, tool geometry, and workpiece material properties.     

正交切削中切屑温度分布的研究

为了获得比较切合实际的模型,假定切屑流向与剪切面成一定的角度,将几何条件加以简化并用红外测温仪测温.实际切屑温度分布表明这个假定模型是可行的.在研究模型中引入较为实际的边界条件可以得到相对满意的结果.     

超高速磨削冲击成屑机理试验研究

根据超高速冲击理论,从磨粒与工件材料碰撞的角度研究了超高速磨削现象。为研究在超高速磨削条件下的磨屑形成机理,使用真实的人造金刚石和CBN颗粒作为磨料,将其粘接在7.62 mm的子弹头部,利用81式步枪作为加速、加载装置,分别对碳素钢、天然大理石、弹簧钢和高速工具钢四种材料进行了720 m/s的超高速冲击磨削试验,得到了若干有价值的超高速磨削的试验结果,并对试验结果进行了详细的分析。试验结果表明,在超高速冲击作用下,弹着点会产生瞬间高温,达到或超过材料的熔点,从而使子弹与钢板相接触区域的材料形成流动相,流动物质在磨粒和冲击波的作用下离开基体而形成磨屑。由此发现了超高速磨削冲击成屑现象,从更深的层面研究和揭示了超高速磨削的成屑机理,验证了“超高速磨削准流动相冲击成屑模型”的正确性。     

用于大型CAD/CAE/CAM软件Anvil-5000中的贝齐尔曲面设计

着重研究Ｂｅｚｉｅｒ曲线、曲面的性质，进而提出了一种简易的Ｂｅｚｉｅｒ曲面边界联接方法，并借助大型ＣＡＤ／ＣＡＥ／ＣＡＭ软件Ａａｖｉｌ－５０００，使这种方法在计算机辅助几何设计（ＣＡＧＤ）领域得到了成功的应用。     

EXPERIMENTAL STUDY ON THE HOT EMBOSSING POLYMER MICROFLUIDIC CHIP

Experiments are used to study the fabrication of polymer microfluidic chip with hot embossing method. The pattern fidelity with respect to the process parameters is analyzed. Experiment results show that the relationship between the imprint temperature and the microchannel width is approximately exponential. However, the depth of micro channel isn＇t sensitive to the imprint temperature. When the imprint pressure is larger than 1 MPa and the imprint time is longer than 2 min, the increasing of imprint pressure and holding time has little impact on the microchannel width. So over long holding time is not needed in hot embossing. Based on the experiment analysis, a series of optimization process parameters is obtained and a fine microfluidic chip is fabricated. The electrophoresis separation experiment are used to verify the microfluidic chip performance after bonding. The results show that 100bp-ladder DNA sample can be separated in less than 5 min successfully.