Design of a deburring tool for intersecting holes in aluminum alloys

A deburring tool for intersecting holes is proposed. The tool has a hemispherical cutter head mounted on a pivoted shaft which is loaded against the burr edge by a set of springs. The cutter head is inserted into an intersecting hole up to the burr edge and is subsequently rotated counterclockwise with a return stroke. The cutter head size is selected such that the cutter head has maximum accessibility to the three dimensional burr edge. The cutting edge is designed to maintain proper ranges of rake angle and relief angle during deburring. The efficiency of the tool in terms of deburring speed is verified by a set of deburring tests on Al6061-T6. The measured depth of cut on the burr edge confirms the complete removal of burrs.     

Wet blasting as a deburring process for aluminum

Light weight aluminum has shown high applicability in the automobile industry for high fuel efficiency. However, the manufacturing of aluminum is limited by the deburring process owing to the difficulty in employing wet blasting. In this paper, we present experimental and computational studies on the deburring process of wet blasting for aluminum. The process conditions are analyzed to achieve high deburring performance that minimizes the surface damage. Parameters of wet blasting with a significant influence on the deburring process are investigated and a promising deburring technique for aluminum is proposed.     

Development of Drill Geometry for Burr Minimization In Drilling

The researchers carried out drilling tests using drills of various shapes to determine burr minimization. The ultimate objective of this study was to develop a compatible drill shape to minimize burr formation. For the experiment general carbide drills, round drills, chamfer drills and step drills are designed and manufactured. Burrs are generated under various cutting conditions using four different materials. A laser sensor was used to measure the burr dimensions. As a result of the experiments, step drill with specific step angle and step size Is suggested for burr minimization.     

Morphology of metal surface generated by nylon/abrasive filament brush

Nylon/abrasive brushing tools are used in surface finishing processes for a wide range of applications, including blending, polishing and edge-radiusing of both ductile and brittle materials. In this paper, the surface topography and machined materials that are generated during orthogonal brushing of a flat 6061-T6 workpiece are examined using scanning electron microscopy. Also, the microscopic morphology of nylon/SiC filaments is examined in as-received and steady-state configurations. This information is used to postulate a qualitative model for material removal mechanisms and the wear/attrition characteristics of the filament material system.     

Dedicated drill design for reduction in burr and delamination during the drilling of composite materials

In the drilling of composite materials such as carbon fiber reinforced plastic, burrs and delamination occur during machining. This study proposed a design of a drill tool with a shape that suppresses burrs and delamination during the drilling of composite materials. The tool shape (tip, groove, land, etc.) is determined, and a nick shape that cuts off chips and reduces heat generation is adopted. A finite element analysis and an experimental evaluation involving 4600 holes were conducted. The maximum errors in the hole diameter and roundness were 15 μm and 0.016, respectively. Further, the maximum burr height was observed to be 80 μm or less, and delamination was not observed in the experiment.     

Taguchi optimization in drilling of AISI 316L stainless steel to minimize burr size using multi-performance objective based on membership function

Burr in drilling plays an important role on product quality and hence it is essential to minimize the burr size at the production stage. This paper presents the application of Taguchi optimization method for simultaneous minimization of burr height and burr thickness influenced by cutting conditions and drill geometry. The approach of Taguchi design for drilling optimization problem is based on multi-performance objective, which employs the membership functions. In the present work, optimal values of cutting speed, feed, point angle and lip clearance angle are determined for selected drill diameter values to minimize burr height and burr thickness during drilling of AISI 316L stainless steel workpieces. The effectiveness of the proposed approach is demonstrated through simulation results and experimental verifications.     

Study on boring and drilling with vibration cutting

In this paper, vibration cutting (VC) has been applied to boring and drilling processes using a vibration device we developed. We analyzed the effect of vibration in boring by investigating the surface roughness of workpiece with the help of Taguchi method and analysis of variance (ANOVA). It has been shown that the utilization of VC in boring improves the surface roughness prominently. The shading-area method we proposed can be employed as a simple and feasible approach for the analysis of burrs in intersecting holes. High-frequency vibration boring can reduce the burr formation in intersecting holes effectively. The experimental results show that the utilization of VC reduces the burrs in intersecting holes noticeably.     

基于磨料流加工技术叶片泵转子去毛刺试验研究

针对叶片泵转子叶片槽两侧面及槽底孔内毛刺不能被彻底去除的问题,提出基于磨料流加工技术的方法,建立磨料流体三维模型,利用Fluent软件模拟分析槽底孔中心及槽道边沿压力分布,设计装夹方案并进行现场试验。加工后的槽道内壁光滑,无毛刺,表面粗糙度值未显著变化,尺寸精度未受影响,表明磨料流加工技术可有效去除转子槽内的毛刺。     

Experimental studies of step drills and establishment of empirical equations for the drilling process

Various sizes of step drills were manufactured by a CNC grinder machine and used in the drilling process with different speeds and feed rates to produce single step holes in S1214 free machining steel. The performance of step drills was compared with that of conventional twist drills in the drilling of the free machining steel for the same task. The influences of drill size, feed rate and cutting speed on the performance of step drills were studied. Experimental results show that for better cutting performance, the small diameter should not be less than 60% of the large diameter. Also, most of the changes in the characteristics of the thrust force were influenced by the smaller drill of the step drill. On the other hand, the small diameter part of the step drill only contributed about 30% of the torque. From the experimental results, empirical equations for drilling thrust force and torque have been established for step drills.     

Geometry prediction of EDM-drilled holes and tool electrode shapes of micro-EDM process using simulation

EDM is an efficient machining process for the fabrication of a micro-metal hole with various advantages resulting from its characteristics of non-contact and thermal process. However, this process has a serious problem caused by the tool wear, which significantly deteriorates the machining accuracy. In this paper, a geometric simulation model of EDM drilling process with cylindrical tool is proposed to predict the geometries of tool and drilled hole. The geometries of tool and workpiece are represented by two-dimensional matrix. For accurate prediction of their geometries, the tool motion, the sparking gap width, the spark frequency, the crater made by a single spark, and the tool wear ratio are considered as simulation parameters. To verify the simulation model the prediction results are compared with the actual experimental ones. Consequently, it is shown that the geometry prediction results match the experimental ones well within the error of 13%. Developed model can be used in offline compensation of tool wear in the fabrication of a blind hole. For the purpose of this, a compensation scheme based on the developed model is introduced, it is then demonstrated that the scheme is successfully applied to an actual micro-hole machining.     

Experimental analysis of drilling fiber reinforced composites

In comparison with metals, long-fiber reinforced composites have a layered structure, with different properties throughout their thickness. When drilling such structures, internal defects like delamination occur, caused by the drilling loads and their uneven distribution among the plies. The current experimental analysis is focused towards determining the cutting loads distribution (axial and tangential) along the work-piece thickness and tool radius by analyzing the thrust and torque curves when drilling with 3 different drills carbon-fiber (CFRP) and glass-fiber (GFRP) reinforced composite plates. A wide range of cutting parameters is tested. The highest loads are found at the tool tip in the vicinity of the chisel edge for all cases. It is also found that the maximum load per ply varies mainly with the axial feed rate and tool geometry, while the spindle speed has little or no influence. The analysis is useful for selecting the cutting parameters for delamination free drilling and also for conducting drill geometry optimizations.     

无毛刺冲孔反顶装置液压动力系统研究

对无毛刺冲孔反顶装置的液压动力系统进行了分析、比较，为工程实际应用提供了系统设计依据。     

斜底大圆角盒形件拉深成形工艺与模具设计

从变形区单元体的应力状态方面叙述了斜底、大底部圆角盒形拉深件的拉深工艺与模具设计,重点是如何控制拉深过程中的材料变薄。生产实践证明,改进后的模具和工艺生产的产品完全达到质量要求。     

Experimental observation and analysis of burr formation mechanisms in face milling of aluminum alloys

The purpose of this paper is to study the burr formation mechanisms in face milling process, and to investigate the influence of cutting conditions on burr formation in face milling of aluminum alloys. The fly milling cutter is used to carry out single-tooth face milling tests. Three aluminum alloys were tested: Al 1100 (cold drawn), Al 2024-T4 and Al 6061-T6. It is found that the burr geometry is strongly dependent upon the in-plane exit angle. Five types of burrs were observed in the experiments: knife-type, wave-type burr, curl-type, edge breakout and secondary burr. Formation mechanisms of each type of these burrs are discussed in details. The relationship between their existence and the machining condition is indicated. The machining guideline in face milling is given at the end of the paper to reduce burr size effectively through the formation of secondary burr.     

CFRP drilling: Fundamental study of local feed force and consequences on hole exit damage.

Carbon Fiber-Reinforced by Plastic (CFRP) is now commonly used in the aircraft industry. The main challenge is to manufacture this difficult-to-cut work material, considering its quality criteria and economical aspects. Drilling is the main machining operation required for the assembly of the aircraft structure. In this paper, results are presented and discussed regarding exit delamination studied at a local scale. Because of the anisotropic properties of CFRP, the fiber cutting modes change with the composite sequence combined with the drill revolution parameters. The local feed forces generated by the cutting edge on the hole bottom may be correlated with delaminating aspects. A posttreatment method is proposed to analyze precisely these feed force and cutting torque distributions. Appropriate ply sequences are identified in order to limit the mechanical load concentration and the risk of delamination or uncut fibers     

Experimental study of burrs formed in feed direction when turning aluminum alloy Al6061-T6

The paper represents an experimental study of the burr formation mechanism in feed direction. The influence of tool angles and workpiece angles, as well as and other cutting conditions on burr dimensions is considered. The work contains experimental graphs of burr cross-sections obtained using a laser measurement system at various stages of burr formation. The analysis of the experimental work shows that, depending on the cutting conditions, a few mechanisms of burr formation can be discerned: sideward burr formation, bending of the uncut part of allowance, and the shearing of residuary material at the final stage. This study could be useful in the search for optimal tool geometry for burr minimization and for the modeling of a burr formation mechanism.     

基于数控机床孔加工的刀具应用及工艺分析

根据数控机床孔加工的各种加工工序，提出了孔加工刀具的应用要点及工艺分析。     

圆盘剪去毛刺装置的气动控制新装置

介绍了一种新型的圆盘剪去毛刺装置的气动控制装置,该装置将压缩空气分别通入去毛刺压辊气缸的两腔,两腔各装一个减压阀。无杆腔的推力和去毛刺装置的重力向下,杆腔的压缩力向上,通过调节各腔减压阀的出口压力,保证去毛刺辊的压靠力在一个较合理的使用范围内;根据来料的不同,通过调节杆腔支路的比例减压阀,自动控制去毛刺压辊的压靠力,并在上位机的画面上显示。该气动控制装置已经成功应用于生产实践。     

斜壁盒形件滚动拉深成形工艺的有限元分析

提出了一种斜壁盒形件的滚动拉深成形新工艺,该工艺利用凸凹模成形辊相对转动,金属板料从成形辊中间穿过,实现斜壁盒形件的滚动拉深成形,能够提高零件的成形效率,易于实现生产自动化。基于MSC.Marc有限元软件对斜壁盒形件的滚动拉深成形过程进行了有限元模拟,分析了斜壁盒形件滚动拉深成形的变形特点,揭示了成形过程中斜壁盒形件的应力、应变和壁厚分布规律。研究表明:滚动拉深工艺能够较好地成形带有一定斜度的盒形件,成形过程中凸模与板料成形部位始终保持线接触,成形接触区两侧金属处于自由状态,金属流动不均匀且补料较困难。局部区域胀形特征明显,缺陷形式主要以破裂为主。