混合铝基复合材料钻削工艺参数的优化(英文)

采用Taguchi方法和灰色关联分析对Al356/SiC-云母混合金属基复合材料的钻削工艺参数进行优化。实验采用L18正交阵列,在计算机的控制立式机床上进行。考察的钻削性能指标包括轴向力、表面粗糙度、刀具磨损和毛刺高度,对影响这些性能的钻削工艺参数进行了优化,包括轴转数、给进速度、钻头类型和云母质量分数。结果表明:给进速度和钻头类型是影响钻削过程的重要因素,通过这种方法可以有效地改进钻削工艺的性能。     

航空航天铝合金构件装配孔钻削出口毛刺研究进展

航空航天制造业中存在大量的铝合金装配孔加工需求。装配孔主要通过钻削加工实现,加工中存在铝合金出口毛刺过大的问题。出口毛刺直接影响工件的精度、抗疲劳强度、装配性能,去毛刺工序会极大地增加工时和成本。因此有必要对铝合金装配孔钻削出口毛刺进行研究,实现对出口毛刺的控制。从铝合金钻削出口毛刺的类型和测量方法、形成机理和高度预测以及毛刺控制方法等方面进行了系统性的论述,以期为铝合金钻削加工出口毛刺的研究提供帮助。      

Optimization and control of drilling burr formation of AISI 304L and AISI 4118 based on drilling burr control charts

Control charts for drilling burr formation for stainless, AISI 304L, and low alloy steel, AISI 4118, were developed. Split point twist drills are used for the experiments of this work. A Drilling Burr Control Chart, based on experimental data, is a tool for prediction and control of drilling burrs. Burr classification was carried out based on the geometric characteristics, burr formation mechanisms and sizes of the burrs. New parameters consisting of cutting condition variables and drill diameter were developed, and used to show unique distributions of the burr types. Burr types and the resultant burr size showed great dependence on the new parameters regardless of the drill diameters. Through the chart, burr type can be predicted with given cutting conditions. Also cutting conditions that are believed to create preferred burr types can be selected.     

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.     

5G覆铜板叠层复合材料高效切磨工艺试验研究

为解决5G覆铜板叠层复合材料板材现有的冲压剪切工艺毛刺飞边严重的问题,提出采用烧结金刚石开槽薄片砂轮切磨工艺替代剪切工艺的方法,在分析设计开槽砂轮结构参数的基础上,研制相应的烧结金刚石开槽薄片砂轮,试验研究不同工艺参数对切磨过程上下表面覆铜层加工毛刺的影响规律和磨削区温度的变化规律。试验结果表明:单位Z向磨削力随磨削速度的增大而增大,随进给速度的增大而减小,随砂轮切入角度的增大先增大后减小;且毛刺飞边高度的变化趋势与单位Z向磨削力的变化趋势相反。磨削温度随磨削速度和进给速度的增大而升高,随砂轮切入角度的增大先升高后降低。切磨5G覆铜板的最优参数组合是磨削速度为34.56 m/s,进给速度为1 200 mm/min,砂轮切入角度为22.0°,在此参数下加工既能保证毛刺飞边高度小于300 μm,又能兼顾较低的磨削区温度。      

CFRP/Al叠层材料变进给钻削表面质量分析

为了降低碳纤维增强复合材料(CFRP)/铝合金(Al)叠层制孔产生的纤维撕裂和毛刺高度,提出了一种基于几何函数设定进给量的方法,即当刀具位于叠层材料钻入区、叠层区、钻出区时,主轴进给量按正弦曲线的变化规律进行设定.在相同的加工效率下,将该方法同定进给钻削进行实验对比,分析了变进给钻削对轴向力、复合材料撕裂损伤以及金属孔...     

A decision fusion algorithm for tool wear condition monitoring in drilling

Tool wear monitoring of cutting tools is important for the automation of modern manufacturing systems. In this paper, several innovative monitoring methods for on-line tool wear condition monitoring in drilling operations are presented. Drilling is one of the most widely used manufacturing operations and monitoring techniques using measurements of force signals (thrust and torque) and power signals (spindle and servo) are developed in this paper. Two methods using Hidden Markov models, as well as several other methods that directly use force and power data are used to establish the health of a drilling tool in order to avoid catastrophic failure of the drill. In order to increase the reliability of these methods, a decision fusion center algorithm (DFCA) is proposed which combines the outputs of the individual methods to make a global decision about the wear status of the drill. Experimental results demonstrate the effectiveness of the proposed monitoring methods and the DFCA.     

电化学对微小孔毛刺去除的仿真及试验

钻削微小通孔产生的孔口毛刺严重影响了其表面质量,且微小孔因直径小导致其入口和出口毛刺去除困难,为此提出基于电化学的微小通孔双面毛刺的同步去除方法。以0.35 mm厚的304不锈钢板的钻孔毛刺为研究对象,建立电化学毛刺去除仿真模型,分析电流密度与微小孔不同区域材料去除速率间的对应关系,研究电极位置及工艺参数对毛刺去除效果的影响,并开展相关试验研究。结果表明,孔口表面电流密度大小表征了材料去除能力的强弱,毛刺尖端电流密度大,孔内壁电流密度小且分布均匀;电极位置对出口毛刺去除速率影响大,伸出型电极毛刺去除效果最好;随加工电压、电解质浓度及电极直径增大,毛刺去除效率增高,但扩孔率增大,且电极直径越大入口倒角越明显;试验基于伸出型电极位置,采用4 V加工电压、12%NaNO₃电解质、0.2 mm电极半径,实现了孔口毛刺的精准去除,加工后的倒角宽度为38μm,扩孔率仅1.99%,验证了仿真的准确性。研究结果可为微小通孔双面毛刺的高效、精准去除奠定研究基础。     

In-process drill wear and breakage monitoring for a machining centre based on cutting force parameters

There are many physical parameters in the cutting process that could be used for the in-process monitoring of cutting tools' working conditions. Of these parameters, cutting forces are strongly recommended by the investigators to be used because of their higher sensitivity and more rapid response to the changes in cutting states. In this paper, the variation in the dynamic behaviour of drilling thrust force and torque with drill wear, breakage and other kinds of fault forms have been investigated experimentally. The results and associated theoretical investigations indicate that, to make the monitoring system more reliable and suitable for a wider range of cutting conditions, both thrust force F_z and torque T arising from drilling operations should be taken as associated monitoring quantities, rather than choosing just one of them. The methodology of signal signature extraction and data processing techniques are discussed and a practical monitoring strategy proposed.     

Prediction of Parameters for the Burr Dimensions in Short-Hole Drilling

The following paper presents a method for the determination of the burr dimensions to be expected in short-hole drilling, simultaneously taking the parameters into consideration which influence the burr formation. These parameters are yield stress, forces and the geometry of the inserts. The method is based on empirical cutting examinations and takes account into the correlation between different burr parameters and the machining conditions such as cutting speed, feed and tool geometry. Using Schaefer's burr value g, it is possible to make a quantitative evaluation of the burr dimensions. The method was verified for the materials 16 MnCr 5 and Ck 45 in case of dry machining.     

Automatic gap detection in friction stir butt welding operations

Friction stir welding (FSW) is a new solid-state welding technology that has been used successfully in many joining applications. A common problem that arises when welding two sheets is the presence of a gap between the sheets. Gaps may be due to improper fixturing, imprecision in the processes used to manufacture the sheets, etc. When the FSW tool encounters a gap, material can possibly escape from the processing zone and the welded part's effective cross-sectional area around the gap will decrease. Both of these effects can possibly cause an unsuitable weld. This paper develops a monitoring algorithm to detect gaps in friction stir butt welding operations in real time (i.e., during the operation). Experimental studies are conducted to determine how the process parameters (e.g., tool rotation rate and tool traverse speed) and the gap width affect the welding process; particularly, the plunge force (i.e., the force acting vertically down on the part). The proposed monitoring algorithm examines the filtered plunge force in the frequency domain to determine the presence of a gap. Several experimental studies are conducted for 2024 aluminum with a variety of process parameters and the monitoring algorithm is shown to be able to reliably detect the presence of gaps in friction stir butt welding operations for tool traverse speeds below 4.233 mm/s and gap sizes above 0.3048 mm.     

A simple analytical model for burr type prediction in drilling of ductile materials

This paper proposes a new analytical model to predict the type of burr at drilling exit. The model is based on the theory of slip-planes and is specially developed to predict burr type formation in drilling of ductile materials. First the analytical model is set up, based on mechanical and geometrical considerations. Then it has been validated through experimental drilling tests on aeronautical aluminum by predicting burr type and thickness. The experimental results show that the model is suitable in the drilling of ductile materials and its validity domain has been established.     

基于零件冲裁毛刺高度的冲压模具磨损预测

冲压模具的磨损会引起冲裁间隙的增大,导致零件冲裁毛刺高度的增加。利用DEFORM-2D软件对0.8 mm料厚的CK75弹簧钢板料的冲裁过程进行有限元仿真,分析了冲裁模具的磨损过程,深入研究了冲裁工艺参数对冲裁毛刺高度与模具磨损的影响变化趋势。研究结果表明:在研究的冲裁工艺参数范围内,零件冲裁毛刺的高度随着冲裁间隙与冲裁速度的不断增加而增大,而随着模具刃口圆角半径的增大则表现出先增加后减小的变化规律;冲裁凸模的磨损深度伴随着冲裁间隙的增大而逐渐减小,随着冲裁速度的增加而增大,而随着模具刃口圆角半径的增加表现出先增大后减小的变化规律。此外,借助冲压模具进行冲裁试验,冲裁毛刺高度的仿真值与试验值之间的最大相对误差为17.7%,从而为衡量模具磨损状况提供了一种比较直接的方法。     

An analytical model to predict interlayer burr size following drilling of CFRP-metallic stack assemblies

A novel analytical model to describe entrance burr formation when drilling ductile metals as a function of tool geometry (point/helix angles, diameter), operating parameters (cutting speed, feed rate) and workpiece material properties, was initially formulated. The model was further developed to account for interlayer burr dimensions when drilling CFRP-metallic stack arrangements. Data from validation trials performed on Ti–6Al–4V, AA7010 and AA2024 workpieces together with their associated CFRP stack assemblies over 4 different combinations of cutting speed and feed rate showed that the predicted sizes of entrance and interlayer burrs were all accurate to within 20% of the experimentally measured results.     

二重顶角钻头抑制钻出毛刺的应用研究

从精益生产的角度强调在加工过程中主动控制钻孔毛刺的重要性,进一步充实了少无毛刺切削三原则的内涵;重点分析了二重顶角钻头在抑制钻孔出口处毛刺的5个优势,初步总结了二重顶角钻头主要参数的确定方法。     

An experimental study of burr formation in square shoulder face milling

Previous research on burr formation in face milling operations has usually been limited to the study of the rollover burr in the cutting direction and/or to a few machining parameters. This paper presents the results of an experimental study on the influence of the main cutting parameters on the formation of the more important burrs produced in face milling operations, namely exit burr in the cutting direction, exit burr in the feed direction and the burr formed at the top edge in a square shoulder face milling operation. Feed per tooth (Sz), cutting velocity (V), axial depth of cut (a) and exit angle (EXA) were the cutting parameters investigated. The effects of mode of milling, tool nose geometry and tool coating were also investigated to a lesser extent. The results show that exit angle and depth of cut are the cutting parameters which have a major influence on the exit burr in the cutting direction, whereas the exit burr in the feed direction is mainly affected by depth of cut. The top burr is very small and only slightly influenced by cutting conditions. It is also shown that down-milling can effectively eliminate the formation of burrs in some cases, whereas an unfavourable tool nose geometry can double the size of buns.     

Response surface methodology-based approach to CNC drilling operations

Drilling operation is fundamental in the manufacturing industry to drill holes especially in sheet metal parts. This paper presents a mathematical model for correlating the interactions of some drilling control parameters such as speed, feed rate and drill diameter and their effects on some responses such as axial force and torque acting on the cutting tool during drilling by means of response surface methodology. For this exercise, a three-level full factorial design was chosen for experimentation using a PC-based computer numerically controlled drilling machine built in-house. The significance of the mathematical model developed was ascertained using Microsoft Excel^® regression analysis module. The results obtained show that the mathematical model is useful not only for predicting optimum process parameters for achieving the desired quality but for process optimization. Using the optimal combination of these parameters is useful in minimizing the axial force and torque of drilling operations; by extension, other drilling parameters such as cutting pressure, material removal rate, and power could be optimized since they depend on the combination of drilling parameters which affect the axial force and torque.     

Light emission, chip morphology, and burr formation in drilling the bulk metallic glass

The chip light emission, chip morphology, burr formation and machined surface in drilling of Zr-based bulk metallic glass (BMG) material are investigated. This study demonstrates that the work- and tool-material as well as the feed rate and spindle speed, two drilling process parameters, all affect the onset of chip light emission. Slow feed rate and high spindle speed increase the specific cutting energy and promote the exothermic oxidation and light emission of the chip. Six types of chip morphology, powder, short ribbon, long ribbon, long spiral, long ribbon tangled, and fan, are observed in BMG drilling. The long ribbon tangled chip morphology is unique for BMG material. On the machined surface under quick stop condition, the fracture topography unique to metallic glass with tributary, void, and vein patterns is observed. Different burr formations are observed: the roll-over shape in the entry and the crown shape in the exit edge. The size of burr in the exit edge is typically larger than that in the entrance edge. High feed rate helps to reduce the size of burr in both entrance and exit edges. This study concludes that the WC–Co tool-material, due to its high thermal conductivity and hardness, performs better in drilling BMG than the high speed steel tool.     

Development of an analytical scheme to predict the need for tool regrinding in shearing processes

This paper describes an analytical scheme for the prediction of the tool wear and the need for tool regrinding in the sheet metal shearing process. The finite element program developed is used for the analysis of the shearing process in this study. In order to predict tool wear, Archard's wear model is reformulated in an incremental form and then the wear depth on the tool is calculated at each step in the deformation using the result of finite element analysis, taking consideration of the sliding velocity and normal pressure over the contact area. In general, the need for regrinding of the shearing tool is determined on the basis of allowable burr height on the final product. Therefore, based on this criterion, the analysis of the shearing process is iteratively performed using the worn profile on the tool in order to predict the need for tool regrinding. To analyze the quantitative wear of the tool, the parameters included in the wear model are determined by the result using a wear test, such as a pin-on-disk wear test for the material of the shearing tool and sheet metal. The effectiveness of the proposed scheme is verified by comparison with experimental results. It is shown that the simulation results are in good agreement with those obtained experimentally and the need for regrinding of the shearing tool can be determined for an allowable burr height.     

An Integrated Force Sensor Solution for Process Monitoring of Drilling Operations

Two piezo electric force sensor rings were developed and integrated into a direct driven motor spindle for online process monitoring of machining processes. Experimental results are presented which demonstrate the performance of the integrated force sensor during drilling operations. Performance comparisons are made between the integrated force sensors and traditional monitoring sensors such as motor power and acoustic emission. The non cutting influences such as spindle dynamic loading contained in the integrated sensor signals are identified. The potential application of the integrated force sensors for process monitoring encompassing tool condition monitoring, spindle condition monitoring and collision detection is demonstrated.