MINIMUM QUANTITY LUBRICATION (MQL) APPLICATIONS IN AUTOMOTIVE POWER-TRAIN MACHINING

ABSTRACT

Minimum Quantity Lubrication (MQL) is a near-dry machining method that may be applied to reduce coolant usage in operations such as drilling, which cannot be performed completely dry. Although significant research has been reported on MQL, relatively little information on production applications and experience has appeared in the technical literature. The most common high-volume production application for MQL is cross and oil hole drilling on steel crankshafts. This paper reviews MQL test results for deep hole drilling of forged steel and cast nodular iron under conditions similar to crankshaft oil hole drilling. The results show that MQL can yield tool life equivalent to gun drills at higher penetration rates under these conditions. This result is consistent with production experience with steel crankshafts, and shows that MQL may also be useful for cross and oil hole drilling of cast crankshafts. Limited test and production data for MQL machining of aluminum prismatics is also described. Significant areas for future research and development, including chip management, air quality, capability and robustness, and cost are also discussed.     

MINIMUM QUANTITY LUBRICATION (MQL) APPLICATIONS IN AUTOMOTIVE POWER-TRAIN MACHINING

Minimum Quantity Lubrication (MQL) is a near-dry machining method that may be applied to reduce coolant usage in operations such as drilling, which cannot be performed completely dry. Although significant research has been reported on MQL, relatively little information on production applications and experience has appeared in the technical literature. The most common high-volume production application for MQL is cross and oil hole drilling on steel crankshafts. This paper reviews MQL test results for deep hole drilling of forged steel and cast nodular iron under conditions similar to crankshaft oil hole drilling. The results show that MQL can yield tool life equivalent to gun drills at higher penetration rates under these conditions. This result is consistent with production experience with steel crankshafts, and shows that MQL may also be useful for cross and oil hole drilling of cast crankshafts. Limited test and production data for MQL machining of aluminum prismatics is also described. Significant areas for future research and development, including chip management, air quality, capability and robustness, and cost are also discussed.     

切削过程的分叉与突变

根据非自由切削模型和切削试验研究了切屑流动的分叉突变原理,结果表明：在切削层图形系数gs＝1的两侧有两个分叉点gs1和gs2,形成一个分叉区间（gs1,gs2）;单位切削功率的连续多极值取向是切屑流动分叉的原因;在分叉区间切屑流动状态的改变呈现出典型的尖点突变特征;突变的滞后性对切削力及切屑旋向有明显的影响。     

基于正交切削模拟的零件铣削加工变形预测研究

提出了基于正交切削模拟的零件铣削加工变形的预测方法,建立了三维铣削加工的有限元模型。基于正交切削加工模拟结果,利用铣削温度、铣削力的分析模型求解了三维铣削加工的瞬态温度和瞬态切削力,并将其作为动态载荷应用于三维切削加工的有限元模型,模拟了零件的三维铣削加工过程,预测了零件的变形。通过模拟结果与现场加工情况对比,证明该预测方法是行之有效的。     

EFFECTS OF COOLANT SUPPLY METHODS AND CUTTING CONDITIONS ON TOOL LIFE IN END MILLING TITANIUM ALLOY

Titanium machining poses a great challenge to cutting tools due to its severe negative influence on tool life primarily due to high temperature generated and strong adhesion in the cutting area. Thus, various coolant supply methods are widely used to improve the machining process. On account of this, tool life and cutting force are investigated based on dry cutting, flood cooling, and minimum quantity lubrication (MQL) techniques. The experimental results show that MQL machining can remarkably and reliably improve tool life, and reduce cutting force due to the better lubrication and cooling effect.     

EFFECTS OF COOLANT SUPPLY METHODS AND CUTTING CONDITIONS ON TOOL LIFE IN END MILLING TITANIUM ALLOY

Titanium machining poses a great challenge to cutting tools due to its severe negative influence on tool life primarily due to high temperature generated and strong adhesion in the cutting area. Thus, various coolant supply methods are widely used to improve the machining process. On account of this, tool life and cutting force are investigated based on dry cutting, flood cooling, and minimum quantity lubrication (MQL) techniques. The experimental results show that MQL machining can remarkably and reliably improve tool life, and reduce cutting force due to the better lubrication and cooling effect.     

精细陶瓷切削过程中表面形成机理的研究

本文实验研究了用烧结体金刚石单刃刀具微细切削精细陶瓷时,切削沟痕形成过程,阐明了陶瓷材料在切削过程中的变形和破坏特性,解析了切削刃和工件干涉深度不同时出现的弹性滑擦、塑性压入、隆起裂纹和大规模破碎等现象。     

水下切割环境的实现及射流冲蚀性能试验研究

提出了水下射流切割模拟试验装置模型并对其进行了分析与试验。实现了水下切割环境。试验研究了模拟水深、靶距及冲蚀时间对水下射流性能的影响关系,较全面地揭示了水下射流的特性。     

STUDY ON THE CUTTING TEMPERATURE IN GEAR HOBBING

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INFLUENCE OF FRICTION AND PROCESS PARAMETERS ON THE SPECIFIC CUTTING FORCE AND SURFACE CHARACTERISTICS IN MICRO CUTTING

For the production of small quantities of micro devices, machining is a low cost alternative to lithographic processing techniques. However, machining shows process specific size-effects upon miniaturization to the micrometer regime. Hence, the orthogonal turning process is chosen to study the influence of process parameters like uncut chip thickness h, cutting velocity v_c and cutting edge radius r_β on the cutting force and the surface plastification by two-dimensional, thermo-mechanically coupled finite element simulations. A rate-dependent plasticity law is used for investigation of a normalized medium carbon steel (AISI 1045). Furthermore, the characteristics of the influences of the different parameters are analyzed mathematically by similarity mechanics. In particular, the frictional effects on the cutting process are studied in detail using a friction coefficient μ based on experimental results, and the influences of the process parameters on the cutting force and the plastic deformation of the surface layer are determined numerically. These results are compared with experimental measurements. The specific cutting forces are analyzed and discussed in detail. Size-effects observed experimentally are also found by numerical simulations.     

OPTIMAL MQL AND CUTTING CONDITIONS DETERMINATION FOR DESIRED SURFACE ROUGHNESS IN TURNING OF BRASS USING GENETIC ALGORITHMS

The evolving concept of minimum quantity of lubrication (MQL) in machining is considered as one of the solutions to reduce the amount of lubricant to address the environmental, economical and ecological issues. This paper investigates the influence of cutting speed, feed rate and different amount of MQL on machining performance during turning of brass using K10 cemented carbide tool. The experiments have been planned as per Taguchi's orthogonal array and the second order surface roughness model in terms of machining parameters was developed using response surface methodology (RSM). The parametric analysis has been carried out to analyze the interaction effects of process parameters on surface roughness. The optimization is then carried out with genetic algorithms (GA) using surface roughness model for the selection of optimal MQL and cutting conditions. The GA program gives the minimum values of surface roughness and the corresponding optimal machining parameters.     

难加工材料高速切削过程中切削力的非线性特征规律析因研究

综合应用析因试验设计与拉丁超立方抽样试验设计,对难加工材料马氏体不锈钢进行了高速铣削试验。在分析其切削力的非线性特征规律基础上,建立了高速切削难加工材料工艺中切削力与背吃刀量、每齿进给量和切削速度之间的非线性数学模型。试验结果表明,高速切削难加工材料时,背吃刀量和每齿进给量之间的交互作用对切削力有显著影响;切削力与切削用量间确实存在非线性特征规律;切削用量对切削力的影响效应随切削用量的变化而发生改变。     

二烷基二硫代磷酸镧的摩擦化学研究

以稀土元素的摩擦学应用为出发点,用异辛醇、La 2O 3和P 2S 5为原料合成出一种新型油溶性润滑油极压抗磨剂——二烷基二硫代磷酸镧（LaDDP）,对其减磨抗磨性能进行考察,同时还用扫描电子显微镜、X射线光电子能谱仪和俄歇电子能谱仪对边界润滑状态下形成的磨斑和表面膜元素组成及化学状态进行了分析。结果表明：这种添加剂在给定试验条件下使ISOVG68油的摩擦因数明显降低和卡咬负荷提高2.2倍,减摩抗磨性能比二烷基二硫代磷酸锌（ZDDP）好,主要原因是在摩擦过程中发生摩擦化学反应生成了由La、La 2O 3、FeS、硫酸盐和磷酸盐组成的边界润滑膜和镧渗透层。最后,用质谱仪模拟了LaDDP的摩擦分解过程,提出了其摩擦化学反应机理。     

大型装置起竖过程的电液比例控制研究

以机动导弹发射架为例,研究了大型液压驱动机械装置起竖过程的控制问题,分析了起竖过程中液压缸的载荷情况,给出了进入多级缸油液的压力、流量与起竖角度间的关系曲线,提出了基于电液比例技术的起竖过程控制方案,实现了对液压油源和起竖速度的灵活控制,仿真结果表明该方案可以用于快速起竖系统设计。     

考虑活塞裙部润滑状态的活塞二阶运动分析及活塞设计参数的研究

将活塞的动力学方程与活塞裙部一缸套间流体动力润滑分析相结合,分析了活塞的二阶运动。并从减小活塞的二阶运动和摩擦功耗两个方面研究了活塞结构参数的设计。所获得的结果对实际具有指导意义。     

进给方向毛刺抑制技术的研究

在对金属切削中进给方向毛刺生成机理进行试验研究和理论分析的基础上，给出了表示产生Ⅰ型微小进给方向毛刺的重要物理量──刀具临界主偏角β_（ｒＩ）。讨论了有关主要因素对临界主偏角的影响，进而开发出了几种抑制或减小进给方向毛刺的新工艺和新方法。     

二维切削中切削方向毛刺与亏缺的界限转换条件

建立了二维切削中切削方向毛刺与亏的生成模型,给出了切削方向毛刺与亏缺的判别准则,并对影响切削方向毛刺与亏缺转换的主要因素进行了实验研究和相应的理论分析,提示出切削方向毛刺与亏缺的界限转换条件为：剪切应变ε≤3,为亏缺;3＜ε＜4,为过渡区;ε＞4,为毛刺。并且,切削方向毛刺与亏缺的界限转换条件因切削条件变化而变化。为进一步深入研究切削毛刺的生成与抑制理论提供了科学的基础。     

EXPERIMENTAL INVESTIGATION ON PARTICLE EFFECT IN PISTON RING-CYLINDER LUBRICATION

To study the tribological properties of the piston ring-cylinder liner in liquid-solid lubrication, the experiment is carried out on a modified piston ring-cylinder liner tester. Two kinds of liquid-solid lubricants are used, one with ultra-dispersed diamond (UDD) nano-particles suspending in pure lubricant, the other with micro-sized M0S2 particles. The particle concentrations are 0%, 0.02% and 0.1% by weight. The experimental temperature is 30℃ and 75℃ respectively. The results show that with the presence of ultra-dispersed diamond particles, the load when scuffing failure occurs is increased.For the lubricant contains MoS2 particles, the scuffing load is decreased. The liquid-solid lubricant also affects the thermal behavior of piston ring-cylinder liner. The surface bulk temperatures of cylinder liner specimen are measured. It has been seen that liquid-solid lubricant used in this research tends to improve the thermal properties generally and the measured friction forces also decreases with the presence of UDD nano-particles. The surface bulk temperature when scuffing occurs is also measured. The results show that the size effect and environment temperature have obvious influence on scuffing load and scuffing temperature. With some new findings, this work is an important complement to the existing research on particle effect on lubrication, because the existing results only show one aspect of this problem.     

FUZZY STABILITY ANALYSIS OF MODE COUPLING CHATTER ON CUTTING PROCESS

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STUDY ON NEAR DRY CUTTING OF ALUMINUM ALLOYS

Series of orthogonal cutting tests of aluminum alloys with different amount of silicon content have been carried out to investigate the chip formation process and adhesion of the work material to the rake face of the cutting tool under near dry cutting conditions. No adhesion is observed when cut with the sintered diamond tool regardless of the amount of the silicon content. On the other hand, the amount of adhesion increases with an increase in the silicon content in the aluminum alloys when cut with the cemented carbide and DLC-coated tools. No adhesion is formed when the nominal coefficient of friction on the rake face is 0.3 or less, and adhesion is formed when the nominal coefficient of friction is 0.4 or more. The amount of adhesion decreases with an increase in the rake angle when cut with the cemented carbide tools and the DLC-coated tool.