Turning of glass–fiber reinforced plastics materials with chamfered main cutting edge carbide tools

In this paper, the machinability of high-strength glass–fiber reinforced plastics (GFRP) materials in turning with chamfered main cutting edge of P and K type carbide tools have been investigated experimentally. Chip formation mechanisms have been obtained with respect to tip's geometries and nose radii. Experimental results for cutting forces were also taken with GFRP as the workpiece material. Force data from these tests were used to estimate the empirical constants of the mechanical model and verify its prediction capabilities. The results show good agreement between the predicted and measured forces. In this study, the nose radius R = 0.3 mm induces a decrease of the cutting force and the smallest cutting force values was achieved in the case of C_s = 20°, _S1(_S2) = −10°(10°) and R = 0.3 mm. Comparing the different P and K type of tools, K type tool is better than P type of chamfered main cutting edge tools. The theoretical values of cutting forces were calculated and compared with the experimental results; the forces predicted by this model were consistent with the experimental values.     

PCBN刀具干车淬硬钢时倒棱前角对切削力和刀具磨损的影响

PCBN刀具磨出负倒棱是为了加强刀具的刃口强度，以减少刀具加工时可能出现的破损情况。本文通过对PCBN刀具加工淬硬轴承钢GCr15的一系列试验数据加以分析，得出倒棱前角和切削力、刀具磨损之间的关系，进而得出在实际加工情况下应该采用的最佳倒棱前角值。试验表明：当倒棱前角取15度且切削速度为125m／s时，刀具具有最好的加工效果，不但切削力可以达到最小值，刀具磨损最轻，而且刀具寿命也达到了最大值。     

The effects of chamfered and honed tool edge geometry in machining of three aluminum alloys

The effects of tool edge geometry in machining have received much attention in recent years due to a variety of emerging machining techniques, such as finish hard turning and micro-machining. In these techniques, the uncut chip thickness is often on the same order of magnitude as tool edge dimension. This paper presents and analyses the results of our recent experimental and theoretical study on the effects of tool edge geometry in machining. Both chamfered and honed tools are investigated covering a wide range of cutting speed and feed rate conditions. The three aluminum alloys 7075-T6, 6061-T6, and 2024-T351 are selected as work materials for particular research purposes. The cutting force, the thrust force, the ratio of the cutting force to the thrust force, and the chip thickness are measured. The similarities and differences in machining with a chamfered tool and with a honed tool are compared. A new slip-line model of chip formation for machining with a chamfered tool is proposed. Good agreement has been reached between the predicted and experimental results. The effects of different aluminum alloys and cutting speeds on the cutting forces, especially on the thrust force, are also studied.     

Prediction of the cutting forces for chamfered main cutting edge tools

A new cutting model of various tool geometries for tools with a chamfered main cutting edge has been built. Theoretical values of cutting forces were calculated and compared with the experimental results; the forces predicted by this model were consistent with the experimental values. Special tool holders were designed and manufactured to obtain various tool geometries. Cutting experiments were conducted on a carbon steel to examine the mechanism of secondary chip formation; the relationship between the shapes of secondary chips and tool geometries was observed.     

Turning of stainless steel with worn tools having chamfered main cutting edges

A force model is proposed in this study for a single-point tool with a chamfered main cutting edge incorporating a wear factor. The variations of shear plane areas occurring in the tool-worn situation are also used. Cutting experiments are conducted on stainless steel bars and the experimental data correlated closely with the theoretical values. A preliminary discussion is also made of the design of special tool holders and their geometrical configurations. The tool holders were milled using medium carbon-steel bars and these holders with the mounting tips were ground to fit various specifications.     

A force model for nose radius worn tools with a chamfered main cutting edge

The three-dimensional cutting forces for nose radius tools with a chamfered main cutting edge incorporated with a tool-worn factor are presented in this paper. The variations in shear plane areas occurring in the tool-worn situation are used. The results obtained from the proposed model shows good agreement with the experimental data on both chip formation as well as cutting forces. In the experimental work the throwaway tips are locked onto the pocket of the tool holder. The holders for special tools are designed first. Next, the tool holders are manufactured by using medium carbon-steel bars and the mounting tips are designed based on various specifications. Finally, the nose radius tips mounting in the tool holder are ground to a wear depth, and the worn tool dimensions are measured by using a profile projector. The shear area and the friction area are calculated accordingly. Then the three-dimensional cutting forces will be obtained from those data.     

Mechanics of high speed cutting with curvilinear edge tools

High speed cutting is advantageous due to the reduced forces and power, increased energy savings, and overall improved productivity for discrete-part metal manufacturing. However, tool edge geometry and combined cutting conditions highly affects the performance of high speed cutting. In this study, mechanics of cutting with curvilinear (round and oval-like) edge preparation tools in the presence of dead metal zone has been presented to investigate the effects of edge geometry and cutting conditions on the friction and resultant tool temperatures. An analytical slip-line field model is utilized to study the cutting mechanics and friction at the tool-chip and tool–workpiece interfaces in the presence of the dead metal zone in machining with negative rake curvilinear PCBN tools. Inserts with six different edge designs, including a chamfered edge, are tested with a set of orthogonal cutting experiments on AISI 4340 steel. Friction conditions in each different edge design are identified by utilizing the forces and chip geometries measured. Finite-element simulations are conducted using the friction conditions identified and process predictions are compared with experiments. Analyses of temperature, strain, and stress fields are utilized in understanding the mechanics of machining with curvilinear tools.     

Prediction of the cutting temperatures of stainless steel with chamfered main cutting edge tools

The main purpose of this report is to predict the temperature of carbide tip's surface and study the cutting forces of turning stainless steel with sharp chamfered main cutting tools. The friction forces and frictional heat generated on elementary cutting tools are calculated by using the measured cutting forces and the oblique cutting analysis. The heat partition factors between the tip and chip are solved by using the inverse heat transfer analysis, which utilizes temperature on the carbide tip's surface measured by infrared as the input. The temperature of the carbide tip's surface is solved by finite element analysis (FEA) and compared with those obtained from experimental measurements. A good agreement demonstrates the accuracy of the proposed model.     

PCD刀具加工有色金属的研究

本文主要研究PCD刀具加工有色金属时刃口及后刀面的刃磨质量对切削表面质量的影响。首先对PCD刀具切削有色金属模型进行了分析研究,然后分别采用金属结合剂金刚石砂轮、树脂结合剂金刚石砂轮和陶瓷结合剂金刚石砂轮刃磨出三把不同质量的PCD刀具进行了切削对比试验,并用扫描电镜对切削表面微观形貌进行了观察分析,发现加工有色金属时,PCD刀具后刀面与刃口刃磨质量对切削表面质量有着同等重要的影响作用。     

Prediction of flank wear by using back propagation neural network modeling when cutting hardened H-13 steel with chamfered and honed CBN tools

Productivity and quality in the finish turning of hardened steels can be improved by utilizing predicted performance of the cutting tools. This paper combines predictive machining approach with neural network modeling of tool flank wear in order to estimate performance of chamfered and honed Cubic Boron Nitride (CBN) tools for a variety of cutting conditions. Experimental work has been performed in orthogonal cutting of hardened H-13 type tool steel using CBN tools. At the selected cutting conditions the forces have been measured using a piezoelectric dynamometer and data acquisition system. Simultaneously flank wear at the cutting edge has been monitored by using a tool makers microscope. The experimental force and wear data were utilized to train the developed simulation environment based on back propagation neural network modeling. A trained neural network system was used in predicting flank wear for various different cutting conditions. The developed prediction system was found to be capable of accurate tool wear classification for the range it had been trained.     

Development of a new rapid characterization method of hob's wear resistance in gear manufacturing—Application to the evaluation of various cutting edge preparations in high speed dry gear hobbing

Gear hobbing remains a cutting technology mainly dedicated to large-scale productions of gears for the automotive industry. The improvements in hobbing tool design are problematic due to the very long duration of wear tests and due to the application of special machine tools only available in production plants. In order to overcome these limitations and to accelerate the efficiency of the investigations, a new rapid testing method called “flute hobbing” has been developed on a standard five-axes milling machine widely present in research laboratories. This testing method has been associated with a software providing the geometry of each chip in hobbing. The correlation of the chip geometry with the wear of each tooth enables to discriminate the critical teeth of a hob in order to focus the development in this area of the cutting zone. This new methodology has been used to investigate the influence of the cutting edge preparation on the wear resistance of gear hobs made of PM-HSS in the context of dry high speed manufacturing. The application of the AFM technology to generate defined edge preparation has shown its efficiency to improve the tool wear resistance and has confirmed previous results.     

Surface integrity when machining age hardened Inconel 718 with coated carbide cutting tools

Considerable attention has been given to the use of ceramic cutting tools for improving productivity in the machining of heat resistant super alloys (HRSA). However, because of their negative influence on the surface integrity, ceramic tools are generally avoided particularly for finishing applications. As a result the main high end manufacturers are more or less dependent on carbide cutting tools for finishing operations. Still the improper use of carbide cutting tools can also result in poor surface integrity. The objective of this investigation is to develop a set of guidelines, which will assist the selection of the appropriate cutting tools and conditions for generating favorable compressive residual stresses. This paper specifically deals with residual stresses and surface finish components of surface integrity when machining (facing) age hardened Inconel 718 using two grades of coated carbide cutting tools specifically developed for machining HRSAs. The cutting conditions were obtained from investigations based on optimum tool performance. The effect of insert shape, cutting edge preparation, type and nose radius on both residual stresses and surface finish was studied at this optimum cutting condition. This investigation, suggested that coated carbide cutting tool inserts of round shape, chamfered cutting edge preparation, negative type and small nose radius (0.8 mm) and coolant will generate primarily compressive residual stresses.     

刀具钝化非对称刃口对铣削温度场影响的研究

刀具刃口通过钝化可以去除刃口缺陷,提高刀具使用寿命和切削过程的稳定性。刀具钝化刃口可以是对称的,也可以是非对称的。通过建模软件SolidWorks建立不同形状因子的非对称刃口二维模型,采用切削仿真软件ThirdWave建立硬质合金刀具钝化非对称刃口对铣削45钢过程的有限元模型,分析形状因子对温度场的分布规律,揭示刀具钝化非对称刃口对切削温度的影响规律,研究结果对于实现刀具钝化刃口优化,提高加工水平具有重要意义。     

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。     

精密切削纯铁材料硬质合金刀具刃口磨损特征演化

为研究纯铁材料精密切削时刀具刃口磨损特征演化规律,以涂层硬质合金刀具为研究对象进行纯铁材料精密切削试验。结果表明：涂层硬质合金刀具精密切削纯铁材料的磨损特征有后刀面均匀磨损带、主沟槽磨损、副沟槽磨损、刀尖磨损;主、副沟槽磨损长度都随着切削时间增加而增大且大于后刀面磨损量,沟槽磨损深度与沟槽磨损长度大致呈线性正相关;刀尖退化与后刀面磨损变化规律相互对应,切削初期磨损率大,随后磨损缓慢。     

织构刀具高速干式切削Al7075-T6的性能研究

表面微织构能够改善刀具的切削性能。为了研究织构刀具高速干切削Al7075-T6时织构参数对切削性能的影响,利用仿真软件建立正交二维切削仿真模型。对比了所选织构参数范围内的最优织构刀具与无织构刀具的主切削力、刀具温度、刀具应力,分析了织构参数对主切削力的影响程度。结果表明:合理的织构参数,可以减小刀具的主切削力,使刀具表现出更好的温度及应力分布梯度;所选织构参数范围内,织构宽度为60μm、织构间距为90μm、织构深度为30μm、织构刃边距为100μm的织构刀具切削性能最好;织构参数对主切削力影响程度从大到小依次为织构刃边距、织构宽度、织构间距、织构深度。     

Effects of the friction coefficient on the minimum cutting thickness in micro cutting

In the ultra precision diamond cutting process, the rake angle of the tool is likely to become negative because the edge radius of tool is considerably large compared to the sub-micrometer depth of cut. The round edge of the tool might sometimes cause plowing results in a poor surface, or burnishing which results in a shiny surface depending on the depth of cut. This study deals with the relationship between the friction of a tool-workpiece and the minimum cutting thickness in micro cutting. Proposed is an ultra precision cutting model in which the tool edge radius and the friction coefficient are the principal factors determining the minimum cutting thickness with a continuous chip. According to the model, a smaller edge radius and a higher friction coefficient make the cutting depth thinner. The experimental results verify the proposed model and provide various supporting evidence.     

Effects of the cutting edge microgeometry on tool wear and its thermo-mechanical load

Tailored cutting edge micro geometries lead to a significant enhancement of the cutting tool performance and increase its tool life. This paper presents the influence of honed cutting edge geometries on the tool wear behavior, process forces and thermal load of the inserts during turning operations. Tool life maps, which show the influence of the honed cutting edge on the wear behavior, are developed for different thermomechanical load profiles of the cutting tool. Furthermore, an approach for space resolved temperature measurements near the cutting edge via two-color ratio pyrometer is presented.     

Design of hob cutters for generating helical cutting tools with multi-cutting angles

This paper studies the design of hob cutters for generating the multi-cutting angles (radial rake angle, relief angle, and clearance angle) of helical cutting tools in one hobbing process. The current manufacturing process can be greatly improved if the cutting edges in the normal section profile, the rack profile, of a hob cutter are designed with several cutting edges with different pressure angles, so that the helical cutting tools with multi-cutting angles can be formed in one generating process. This paper, therefore, designs a rack profile of a hob cutter consisting of three straight cutting edges with different pressure angles and a curved cutting edge. By applying the equations of designed rack profiles of hob cutters, the principle of coordinate transformation, the theory of differential geometry, and the theory of gearing, the mathematical models of the helical cutting tool can be derived. In addition, the formulas for the radial cutting angle, relief angle, and clearance angle can be derived. Meanwhile, solid modelling of the helical cutting tool can be carried out with computer graphics programming. The results of this paper will contribute to the improvement of the design technology of hob cutters, to enhance the manufacturing processes of helical cutting tools, and to assist tool-related industries in upgrading their technology and competitive abilities.