加工复合地板耐磨层时PCD刀具切削参数的研究

切削参数是影响PCD刀具切削性能的主要因素。本文采用Element Six公司的SYNDITE CTH025型聚晶金刚石(PCD)复合片制成强化复合地板用切削刀具，进行了一系列加工强化复合地板耐磨层的切削实验。通过实验研究了切削参数对刀具切削力的影响，得出了切削力随切削参数的变化规律，指出随着切削深度的增加，PCD刀具切削力增加；进给速度的增加使切削力增加；切削速度的增加将会使切削力降低。同时，分析了切削参数对刀具磨损、工件加工质量以及加工效率的影响。最后，本文总结了采用PCD刀具加工强化复合地板时加工参数的选择原则，认为当n=6000r／min、f=10000mm／min能够实现较高的加工效率，并保证工件的加工质量。     

Thermally enhanced machining of hard-to-machine materials—A review

Thermally enhanced machining uses external heat sources to heat and soften the workpiece locally in front of the cutting tool. The temperature rise at the shear zone reduces the yield strength and work hardening of the workpiece, which make the plastic deformation of hard-to-machine materials easier during machining.This review summarizes the up-to-date progress and benefits of thermally enhanced machining (with a focus on laser and plasma assistance) of ceramics, metals and metal matrix composites. It covers the integration of the external heat source with cutting tools, analysis of temperature distribution around the cutting region, material removal mechanisms, tool wear mechanisms and the improvement in machinability of various engineering materials by the assistance of external heat source.     

Machinability study of tungsten carbide using PCD tools under ultrasonic elliptical vibration cutting

Sintered tungsten carbide (WC) is an extremely hard and brittle material extensively used in tool manufacturing industries. However, the current cutting technologies for shaping this typical hard-to-machine material are still cost ineffective. In this study, polycrystalline diamond (PCD) tools are used to study the machinability of sintered WC (~15% Co) by applying the ultrasonic elliptical vibration cutting (UEVC) technique. Firstly, it presents the UEVC principle and the effects of speed ratio (i.e. the ratio of the nominal cutting speed to the maximum tool vibration speed in the cutting direction) on the tool–workpiece relative motion as the cutting speed greatly influences the UEVC performance. Then UEVC experiments are carried out to analyze the cutting force, tool-wear progression, chip formation and surface quality against the cutting time at different speed ratios. The results show that when the speed ratio decreases, the resultant cutting force and the tool flank wear decrease while the surface finish improves. Average surface roughness, R_a, in a range between 0.030 and 0.050 μm is achieved at speed ratios less than 0.107. The experimental findings suggest that the commercial PCD tools can be used to machine sintered WC to achieve ultraprecision surface by applying the UEVC technique, which will be cost effective for miniature cutting technologies in future.     

Machinability of BN free-machining steel in turning

In the past few years, extensive researches have been done to improve the machinability of work materials in order to increase productivity and reduce the effect on the environment. To satisfy these demands, various free-machining steels have been researched and developed. One of them is BN free-machining steel that contains hexagonal boron nitride (h-BN). However, the machinability was not stable. In this study, machining tests were carried out to clarify the machinability of steels and appropriate chemical composition of work material and tool material to achieve high efficient machining. Tested work materials were plane carbon steel JIS S45C and BN free-machining steels. The JIS S45C was used as the standard. The tool wear in turning BN free-machining steel was smaller than that in turning standard steel. In case of turning BN1 with P30 at 200, 300 m/min, the wear progress rate of flank wear and crater depth were about half as much as that in turning standard steel. BN free-machining steel showed slightly lower cutting temperature and smaller cutting force in comparison with standard steel at the tested cutting speeds. Al and N were detected as a layer at the tool wear region of P grade carbide tools after turning BN free-machining steel at high cutting speed. It is thought that one of the main reasons of outstanding machinability of BN free-machining steel is that the deposited layer containing Al and N acts as diffusion barrier at the tool–chip interface. In turning larger Al content BN-added steel with higher Ti content cutting tools, a larger wear reduction was observed. Therefore, it is said that not only added BN but also appropriate Al is necessary in work material.     

Tool wear characteristics in machining of nickel-based superalloys

Nickel-based superalloy is widely employed in aircraft engines and the hot end components of various types of gas turbines with its high strength, strong corrosion resistance and excellent thermal fatigue properties and thermal stability. However, nickel-based superalloy is one of the extremely difficult-to-cut materials. During the machining process, the interaction between the tool and the workpiece causes the severe plastic deformation in the local area of workpiece, and the intense friction at the tool–workpiece interface. The resulting cutting heat coupled with the serious work hardening leads to a series of flaws, such as excessive tool wear, frequent tool change, short tool life, low productivity, and large amount of power consumption etc., in which the excessive tool wear has become one of the main bottlenecks that constraints the machinability of nickel-based superalloys and its wide range of applications.In this article, attention is mainly focused on the tool wear characteristics in the machining of nickel-based superalloys, and the state of the art in the fields of failure mechanism, monitoring and prediction, and control of tool wear are reviewed. The survey of existing works has revealed several gaps in the aspects of tool self-organizing process based on the non-equilibrium thermodynamics, tool wear considering the tool nose radius, thermal diffusion layer in coated tools, tool life prediction based on the thermal–mechanical coupling, and industrial application of tool wear online monitoring devices. The review aims at providing an insight into the tool wear characteristics in the machining of nickel-based superalloys and shows the great potential for further investigations and innovation in the field of tool wear.     

超硬材料刀具的特性及应用

本文主要介绍了单品金刚石刀具，高温高压合成的聚品金刚石（PCD）刀具，聚晶立方氮化硼（PCBN）刀具及化学气相沉积的金刚石膜（CVD）刀具的特性及应用。我们做了有关CVD刀具与PCD刀具耐磨性的切削试验：通过试验可以看出，CVD刀具确实有较好的耐磨性，但是在切削时间为17min时，由于CVD较PCD脆，在25倍显微镜下观察发现CVD金刚石刀具的刀口有明显的崩刃。另外发现，CVD金刚石刀具在制造及使用过程中也极易出现崩刃现象，所以目前大多数厂家仍以使用PCD刀具为主，CVD金刚石刀具的推广仍需要一个过程。     

基于ABAQUS有限元仿真的硬质合金刀具磨损机制研究

钛合金在切削过程中会产生严重的加工硬化现象,导致切削性下降、刀具磨损加剧,直接影响工件的加工质量.为研究钛合金切削性能和刀具磨损机制,利用ABAQUS软件建立了钛合金的有限元模型,对其切削过程进行仿真分析,研究硬质合金刀具磨损机制;设计Ti6Al4V钛合金车削实验,研究不同加工参数对刀具磨损程度的影响规律.研究结果表明...     

Study on PCD machining

Polycrystalline diamond, PCD, is known for its superior characteristics such as hardness, toughness and wear resistance. However, due to these factors, manufacturing PCD tools is a difficult material removal process. Using quantitative analysis, this study compares the machining effect on a PCD V-cutter including EDM and grinding. The conclusions show that grinding is better than EDM for machining PCD, and with proper parameters, the PCD will be less damaged and retain its superiorities as a cutting tool. In addition, this study presents a beginning for research on understandings of principles in cutting PCD. It may be useful for toolmakers to produce a high quality and reusable PCD tools.     

The application of polycrystalline diamond (PCD) tool materials when drilling and reaming aluminium based alloys including MMC

Following a review of metal matrix composite (MMC) materials and production methods, the paper outlines the development and application of PCD cutting tools. Experimental data are presented for the drilling and single blade reaming of aluminium-silicon alloys containing 7% and 13% silicon and aluminium 2618 MMC alloy reinforced with 15 vol% silicon carbide (SiC) particulate. Though initially aimed only at aerospace and defence products, MMCs have progressively moved into higher volume applications and are currently under evaluation for volume automotive components. Compared with standard hypoeutectic and hypereutectic cast aluminium-silicon alloys, tool wear when machining MMC is shown to be up to seven times more severe. Tools used for drilling include HSS-M2, diamond plated HSS, WC, TiN coated WC and PCD. Other than when using PCD drills, tool life was extremely short due to the abrasive nature of the (SiC) reinforcement. Similarly, results from PCD reaming tests confirmed that diamond tooling provides the only realistic tooling option.     

Experimental Investigations to Study the Effects of Microwave Treatment Strategy on Tool Performance in Turning Operation

In the present study, microwave treatment has been used to enhance the tribological properties of single-point tungsten carbide (WC) cutting tool inserts such as wear resistance and hardness. The tool hardness and cutting parameters were considered to evaluate the performance of microwave-treated WC inserts in turning operation. The optimum cutting parameters were identified using response surface method (RSM)-based desirability approach. The relationship between cutting parameters and output responses, viz. flank wear, cutting force and surface roughness, was developed using the RSM. The investigations revealed that the increase in tool hardness due to complex carbide formation results in a significant reduction in tool wear, cutting forces and improvement in the surface finish of workpiece. Further, the statistical models results were validated with the experimental results. Metallurgical properties of treated and untreated tool inserts were analyzed using scanning electron microscope, x-ray diffraction method and Vickers microhardness tests. The results highlighted the importance of microwave treatment in enhancing the machining performance in turning operation.     

Comparison of the machinabilities of Ti6Al4V and TIMETAL® 54M using uncoated WC–Co tools

Single-point turning tests of cylindrical bars were undertaken to analyse and compare the machinability of Ti6Al4V, the most common titanium alloy, and TIMETAL^® 54M, a newly developed alloy with similar mechanical properties as Ti6Al4V but with better machinability. Conventional cooling and uncoated WC–Co tool inserts were used in the study, because they are the most recommended for machining these materials. The feed and the depth of cut were maintained constant, and only the cutting speed was varied because it is the most affecting parameter. Adhesion of workpiece material in the form of a built-up edge appeared in all the cutting inserts after machining both alloys, which was removed for flank- and crater-wear measurements. Lower wear rates were observed for the Ti54M alloy, especially at high cutting speeds. In the same manner, cutting-force measurements showed lower specific cutting- and feed-force values for the Ti54M alloy. Adiabatic shear bands, a typical feature in the machining of titanium alloys, were observed in chips from both alloys under all cutting conditions. Finally, scanning electron microscopy observations were carried out to analyse the adhered material on the cutting edges of the worn tools where signs of diffusion and attrition were detected.     

Machinability analysis in turning tungsten–copper composite for application in EDM electrodes

Electro-discharge machining (EDM) is widely used in tooling industry, where it is applied on materials, which are too hard to be machined with conventional techniques. The tungsten–copper is broadly used as an EDM electrode for machining of die steel and tungsten carbide workpieces. As, tungsten–copper electrode is more costly than conventional electrodes, there is a need to understand the machinability aspects in turning of this material. Hence, an attempt has been made in this paper to study the effects of cutting conditions on machinability characteristics such as cutting force, feed force, depth force, machining force, power, specific cutting force, arithmetic average surface roughness and maximum peak to valley height during tungsten–copper turning with K10 carbide cutting tool. The response surface methodology (RSM) based second order mathematical models of machinability aspects are developed using the data obtained through full factorial design (FFD). The adequacy of the machinability models is tested through the analysis of variance (ANOVA). The response surface analysis reveals that a combination of higher cutting speed with low-to-medium feed rate is advantageous in reducing the forces, power and surface roughness, which in turn increases the specific cutting force.     

Prediction of Tool Wear Mechanisms in Face Milling AISI 1045 Steel

Cutting tools have an important role in the machining process, since they are related to workpiece surface quality and production costs. Due to the importance of selecting appropriate cutting parameters during the milling process, this research develops empirical expressions to predict the tool wear mechanisms that a cutting tool will suffer during the milling of AISI 1045. In addition, an expression to predict the critical cutting speed value where the diffusion mechanism starts to appear is developed. AISI 1045 was selected as the workpiece material due to its excellent machinability, good abrasion resistance, and mechanical strength. The Design of Experiments method namely Taguchi was applied to reduce the time and cost of experiments. The results showed that the cutting speed is the parameter with the most influence on tool flank wear which started to appear when using V?=?500?m/min and the diffusion tool wear mechanism at V?=?850?m/min.     

PCD和HTi10刀具铣削CFRP试验研究

针对碳纤维复合材料(CFRP)难加工的特性,文中采用PCD和HTi10刀具进行了CFRP铣削试验,对加工过程中的铣削力、刀具磨损和表面粗糙度进行了分析。结果表明:PCD和HTi10刀具的铣削力和表面粗糙度变化规律一致,均随转速的增大而减小,随进给速度的增大而增大,但PCD刀具的铣削力更小,加工质量更好;与HTi10相比,PCD刀具的铣削力对刀具磨损更加敏感,更适合应用在加工环境较好的条件下。在CFRP加工过程中,粗加工时优选HTi10刀具,精加工时优选PCD刀具,宜选用高转速、低进给的切削参数。     

Using PCD for machining CGI with a CO2 coolant system

Polycrystalline diamond is widely used as a economic cutting material for machining non-ferrous materials such as aluminum. It is perceived that diamond cannot be used for cutting ferrous materials due to the high affinity of carbon to iron. Nevertheless, under certain conditions it is possible to use diamond materials for cutting ferrous metals. In order to avoid graphitization of the diamond matrix, it is necessary to keep the cutting temperature below the critical level of diamond graphitization. This paper presents the influence of a cryogenic CO₂ coolant strategy on the cutting process using PCD tools for cutting high strength compacted graphite iron (CGI). Investigations show, that tool wear behavior strongly correlates with the cutting speed, the cutting forces, cutting temperatures, and surface roughness of the workpiece. The test results show, that the tool life of PCD for cutting cast iron is dependent on the diamond grain size, the binder material, and the cutting parameters.     

Wear behavior of Al2O3/Ti(C,N)/SiC new ceramic tool material when machining tool steel and cast iron

Design, fabrication and application of ceramic cutting tools are one of the important research topics in the field of metal cutting and advanced ceramic materials. In the present study, wear resistance of an advanced Al₂O₃/Ti(C,N)/SiC multiphase composite ceramic tool material have been studied when dry machining hardened tool steel and cast iron under different cutting conditions. Microstructures of the worn materials were observed with scanning electronic microscope to help analyze wear mechanisms. It is shown that when machining hardened tool steel at low speed wear mode of the kind of ceramic tool material is mainly flank wear with slight crater wear. The adhesion between tool and work piece is relatively weak. With the increase of cutting speed, cutting temperature increases consequently. As a result, the adhesion is intensified both in the crater area and flank face. The ceramic tool material has good wear resistance when machining grey cast iron with uniform flank wear. Wear mechanism is mainly abrasive wear at low cutting speed, while adhesion is intensified in the wear area at high cutting speed. Wear modes are dominantly rake face wear and flank wear in this case.     

Laser-assisted machining of Inconel 718 with an economic analysis

Superalloys have high strengths at elevated temperatures, which make them attractive toward various applications and also make these materials difficult to machine at room temperature due to excessive tool wear and poor surface finish. Laser-assisted machining (LAM) offers the ability to machine superalloys more efficiently and economically by providing the local heating of the workpiece prior to material removal by a single point cutting tool.An existing transient, three-dimensional heat transfer model is modified for modeling LAM of Inconel 718. Suitable coating conditions are determined for increasing the laser absorptivity in metals and an approximate absorptivity value is determined. The thermal model is validated in axial and circumferential directions by temperature measurement using an infrared camera.The machinability of Inconel 718 under varying conditions is evaluated by examining tool wear, forces, surface roughness, and specific cutting energy. With increasing material removal temperature from room temperature to 620 °C, the benefit of LAM is demonstrated by a 25% decrease in specific cutting energy, a 2–3-fold improvement in surface roughness and a 200–300% increase in ceramic tool life over conventional machining. Moreover, an economic analysis shows significant benefits of LAM of Inconel 718 over conventional machining with carbide and ceramic inserts.     

High Speed Face Milling of a Aluminium Silicon Alloy Casting

High speed machining of aluminium silicon alloy castings has gained significant interest from automotive industry involved in the development of the new generation of lightweight vehicles. This paper investigates the influence of workpiece microstructure, namely the secondary dendritic arm spacing (SDAS), tool material and geometry on tool wear mechanisms, cutting forces and surface integrity when face milling at cutting speeds of 5,000 m min⁻¹. It was found that the SDAS is the parameter with the main influence on tool wear rate; higher SDAS values require polycrystalline diamond (PCD) tooling due to the lower wear rates when compared with carbide tools. Finite Element Analysis (FEA) was employed to study the influence of tool wear on temperature and shear stress distribution in the workpiece material.     

A study on the effect of tool nose radius in ultrasonic elliptical vibration cutting of tungsten carbide

Nowadays, ultrasonic elliptical vibration cutting (UEVC) technique is being successfully applied for ultraprecision machining of difficult-to-cut materials. Previous study reported that the tool geometry especially tool nose radius notably influences the performance of 1D ultrasonic vibration cutting (UVC). However, the effect of tool nose radius in the UEVC technique is yet to be studied. This study aims to investigate the effects of tool nose radius on the UEVC performance in terms of cutting force, tool wear and surface finish when machining a hard-to-cut material, sintered tungsten carbide (WC), using PCD tools. The experimental results show that the UEVC technique performs remarkably better in all aspects at a 0.6 mm nose radius compared to a lower (e.g. 0.2 or 0.4 mm) and a higher nose radius (e.g. 0.8 mm). When machining about 412 mm² surface area, an average surface roughness, R_a of 0.010 μm is achieved with a 0.6 mm nose radius. Analyses are conducted to justify the findings in this study.     

A study of the diamond tool wear suppression mechanism in vibration-assisted machining of steel

Inability of machining steel strongly inhibits the application of diamond machining in manufacturing industry, especially in the fields of ultra-precision and micro machining. In recent years, vibration-assisted machining (VAM) has been proved to be capable of efficiently suppressing the diamond tool wear in cutting steel. Currently, the prevailing speculation claimed by most researchers for such suppression is that the tool–workpiece flash temperature was reduced in VAM, which would slow the chemical reaction between iron on steel and carbon on diamond. However, the correctness of this speculation has not been proved by any experimental or theoretical research. In this paper, in order to understand the true wear suppression mechanism of diamond tools in VAM of steel, a study is conducted by measuring the workpiece temperatures and modeling the cutting energy consumption in both VAM and conventional cutting (CC). Based on the comparison results, it is concluded that the cutting temperature and energy consumption in VAM are not smaller than in CC, and hence the reduced diamond tool wear in VAM should not be caused by the claimed reduced temperature, especially when the material removal rate is very small. Finally, based on the EDS analysis and the comparison of experimental results under different air pressure, two probable reasons are proposed for the significantly reduced diamond tool wear in VAM of steel: (i) increase of gas pressure at the tool–workpiece interface and (ii) generation of an oxide layer on the freshly machined surface.