硬质合金刀具正交车铣TC4钛合金磨损形貌及机制分析

在车铣复合加工中心Mazak Integrex 200Y上,切削速度为v=150、200 m/min及干式切削条件下,采用硬质合金刀具H13A对钛合金TC4进行正交车铣(顺铣)磨损试验。研究表明高速正交车铣钛合金时,正常磨损阶段前刀面出现不同程度切屑黏结及积屑瘤,后刀面主要以黏结磨损为主,磨损相对均匀;急剧磨损阶段,前刀面切屑黏结加剧,形成连续切屑,缠绕刀具;后刀面由于黏结作用刀具材料被切屑黏结物带走,形成黏结凹坑。刀具磨损的主要原因为黏结磨损、氧化磨损,通过X射线电子能谱(XPS)证明刀具磨损表面有TiO_2、WO_3和Co_3O_4等氧化物生成,分析其对刀具磨损的影响。     

铝合金切削过程刀具磨损预测研究

为更精确地研究刀具磨损,建立刀具磨损模型至关重要。目前刀具磨损的模型主要是经典的刀具磨损模型和刀具磨损预测模型,刀具磨损预测模型主要为人工神经网络、隐马尔可夫模型和支持向量机模型。分析铝合金切削过程中的刀具磨损机制,总结经典的刀具磨损模型,梳理刀具磨损预测模型。铝合金切削过程中刀具主要的磨损机制为黏着磨损、扩散磨损和磨粒磨损。结果表明：在黏着磨损和磨粒磨损的基础上考虑扩散磨损的刀具磨损理论模型最接近实际加工。     

An investigation of factors controlling part growth and surface finish of form tools in the automatic screw machine test

In order to investigate factors controlling part growth and surface finish in the automatic screw machine test, a set of eight separate experiments was carried out. It was observed that flank wear is the major factor in controlling rough-form part growth, but does not account for all of it. Other possible factors were reviewed. The elastic deflection of the workpiece estimated from the increase of the taper of rough-formed part with machine time appears to account for most of the difference between the observed part growth and the estimated values from flank wear. BUE overhang and thermal expansion of the workpiece could also contribute to rough-form part growth. The contribution of BUE overhang could be either positive or negative depending on how overhang size changes with machine time. Thermal expansion of the workpiece would give rise to negative part growth. Interestingly, during the initial 30 min of machining, negative part growth for rough-form tool and rapid positive part growth for finish-form tool were observed. Thermal expansion for the rough-form tool and the change in the size of BUE overhang for both tools are believed to be at least partially responsible for these effects. A procedure to start measuring part growth after approximately 30 minutes of machining is thus recommended. For finish-formed surface finish in this investigation, uneven BUE is believed to be the dominant factor in determining surface roughness.     

A SEM and EDS insight into the BUL and BUE differences in the turning processes of AA2024 Al–Cu alloy

When a Built-Up Edge (BUE) and a Built-Up Layer (BUL) are formed on the rake face of a tool, the surface finishing of the workpiece, the tool geometry and other output parameters can be affected. Till a few years ago both effects were considered as two forms of the same phenomenon. More recently, some authors have established differences between BUL and BUE, those related to thickness. The mechanism of BUL and BUE formation is not taken into account by these authors. This work reports on the results of a study using the SEM and EDS of the microstructural features of BUL and BUE formed over TiN turning inserts in machining of an Al–Cu alloy. The results obtained in this study have allowed the establishment of a first hypothesis about the differences between the mechanisms of BUL and BUE formation.     

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.     

Documentation of tool wear progress in the machining of nodular ductile iron with silicon nitride-based ceramic tools

Nowadays, the HPM of cast irons is based on silicon nitride ceramic and CBN cutting tools. This paper characterizes and correlates several outputs of the cutting process of nodular cast iron using uncoated and Al₂O₃/TiN coated Si₃N₄ ceramic tools resulting from wear progress and destruction of tool faces. Investigations include tool wear curves, tribological behaviour of the tool–chip interface and tool wear mechanisms occurring on contact surfaces. The image-based characterization of worn surfaces employs such techniques as SEM, BSE and EDX analysis. The occurrence of various wear mechanisms, such as abrasive, adhesive and chemical wear was revealed.     

Tool grinding of end mill cutting tools made from high performance ceramics and cemented carbides

The paper presents different approaches to improve the process knowledge in tool grinding with a focus on ceramic shank-type end mills. The flute grinding operation was analyzed using a kinematical simulation to acquire an insight into the local distribution of the material removal rate or the microscopic chip parameters. Further investigations cover the cutting edge quality emerging in characteristic tool grinding operations on end mills with helical flutes made from advanced ceramics. Final machining test prove a reliable cutting behaviour without catastrophic failure and a gentle abrasive and adhesive wear observed on the ground cutting tools.     

碳纤维/树脂基复合材料高速铣削的刀具磨损机理

采用涂层(Ti CN,Ti Al N)与无涂层超细晶粒硬质合金立铣刀对碳纤维/树脂基复合材料进行高速铣削试验,研究了刀具后刀面磨损带扩展及刀具磨损规律,并探讨了切削力、毛刺随着刀具磨损的变化趋势,观察了刀具的微观磨损形貌,分析了刀具的磨损机理。结果表明:在相同的切削条件下,无涂层刀具的后刀面磨损量及切削力最大,毛刺扩展严重,后刀面主要发生磨粒磨损,由于黏着磨损和氧化磨损对切削刃的弱化作用,主切削刃发生了微崩刃;Ti CN涂层刀具后刀面主要发生磨粒磨损,并伴随有黏着磨损和轻微的氧化磨损,失效形式为剥落和微崩刃;Ti Al N涂层刀具的后刀面磨损量及切削力最小,毛刺扩展缓慢,更适合碳纤维复合材料的加工。其后刀面主要发生了磨粒磨损,其失效形式为剥落。     

Machinability of hardened steel using alumina based ceramic cutting tools

Alumina based ceramic cutting tool is an attractive alternative for carbide tools in the machining of steel in its hardened condition. These ceramic cutting tools can machine with high cutting speed and produce good surface finish. The wear mechanism of these ceramic cutting tools should be properly understood for greater utilization. Two types of ceramic cutting tools namely Ti[C,N] mixed alumina ceramic cutting tool and zirconia toughened alumina ceramic cutting tool are used for our investigation. The machinability of hardened steel was evaluated by measurements of tool wear, cutting forces and surface finish of the work piece. These alumina based ceramic cutting tool materials produce good surface finish in the machining of hardened steel. In this paper an attempt is made to analyse the important wear mechanisms like abrasive wear, adhesive wear and diffusion wear of these ceramic cutting tool materials and the performance of these ceramic cutting tools related to the surface finish is also discussed here.     

喷焊镍基材料切削加工过程的研究

通过选用一批有代表性的典型刀具对喷焊镍基高温合金材料进行刀 具耐用度切削对比试验,找出了各自的耐用度公式,并且还借助于扫描电镜和电子探针观察刀具磨损区,切屑底面和工件已加工表面,由微区形貌和微区成份分析得出其刀具主要为磨粒磨损的结论,这与通常高温镍基合金材料切削时的刀具磨损规律不同。     

铍铜合金断续切削后刀面磨损机理研究

目的研究断续切削过程温度变化对刀具粘结现象、涂层剥落和刀具磨损的影响。方法搭建了仿铣削加工的断续车削实验平台,采用热电偶法测量了断续切削过程中刀具后刀面在不同速度下的切削温度,利用带有能谱仪(EDS)的扫描电镜(SEM)观察后刀面随速度变化的磨损形貌并分析后刀面磨损区域的元素组成,阐述了后刀面温度和刀具磨损之间的联系,研究了Ti AlN涂层硬质合金刀具断续切削铍铜合金C17200时的后刀面磨损机理。结果随着切削速度的增加,刀具温度在v=500 m/min出现峰值,温度越高,后刀面的涂层剥落和粘结磨损现象越严重,涂层剥落和粘结磨损现象在切削速度为500 m/min时最严重,而后随着刀具温度的降低而减缓,切削速度600 m/min时的涂层剥落和粘结磨损现象相比500 m/min时有所减轻。结论断续切削过程中,刀具持续性地经受"负载-卸载"、"升温-降温"产生的高温、冲击和加工环境的不稳定性,是引起粘结现象、涂层剥落和刀具磨损的主要原因。涂层剥落和粘结磨损是导致铍铜合金断续切削刀具失效的主要磨损形式。     

The study on the chip formation and wear behavior for drilling forged steel S48CS1V with TiAlN-coated gun drill

The solid carbide gun drill was coated with TiAlN, and a comprehensive evaluation on the wear behavior and chip formation had been performed on it for machining forged steel S48CS1V at a cutting speed of 12.66 mm/s (4400 rpm) with a continuous Minimum Quantity Lubrication (MQL). Cutting torque had been measured versus with the quantity of the machined crankshaft. The cutting torque curves revealed the three wear stages that were the initial stage, the semi-steady stage and the disastrous stage. Gun drill with TiAlN coating suffered from adhesive wear on the wear pad and chemical diffusion wear on flank face. Additionally, sliding wear and chipping were the wear forms. The high temperature and stress played the important roles in the adhesive and chemical diffusion wears. The high alternative stress produced the plastic deformation and cold welding for the atomic absorption and thus it made the grains of carbide substrate tearing-off from deforming cobalt bond, therefore adhesive wear took place.     

切削Inconel718时新型陶瓷刀具JX-2-Ⅰ的切削性能研究

JX－2－Ⅰ是最新研制的碳化硅晶须（SiCw）增韧和碳化硅颗粒（SiCp）弥散增强氧化铝（Al2O3）新型陶瓷刀具。本文详细研究了该刀具加工Inconel718时的切削性能，结果表明，在低速干切时的刀具抗磨损能力为YG8＞JX－2－Ⅰ＞JX－1＞JX－2－Ⅱ；在105m／min的高速湿式切削时，JX－2－Ⅰ的切削性能与JX－1差不多，但是在42m／min的速度时JX－2－Ⅰ的切削性能好于JX－1（Al2O3＋SiCw）。同时发现在用JX－2－Ⅰ中高速切削Inconel718时必须使用冷却液。由于切削温度对工件材料加工硬化的影响，以及对工件材料高温强度屈服拐点的影响而存在一个切削速度的最佳选取范围。SEM分析表明，刀具磨损的主要形式是后刀面磨损、边界磨损、切深沟槽磨损和前刀面月牙洼磨损；刀具磨损的主要机理是粘结磨损、磨粒磨损和塑性变形磨损。     

Chip formation and tool wear in turning of aluminum-alloyed UHC-steels

Aluminum-alloyed ultra-high-carbon steels (UHC-steels) display outstanding mechanical properties combined with a reduced density compared to conventional steels. Consequently, these steels show high potential for industrial applications. A widespread use of UHC-steels containing aluminum depends strongly on efficient machining processes. Since material processing has been restricted to laboratory scale until recently, only few empirical values exist on machining. This paper is focused on the chip formation and tool wear in external turning of aluminum-alloyed UHC-steels. The mechanical loads on the tool are presented and compared to C70MnVS4, which is commonly used for powertrain components. Furthermore, recommendations for optimized cutting tools are given. The results indicate that adhesive wear and chipping are the predominant tool wear mechanisms due to high cutting temperatures and the distinct microstructure of the investigated UHC-steel.     

Machinability of titanium alloys (Ti6Al4V and Ti555.3)

Near-beta titanium alloys like Ti555.3 are increasingly being used in aeronautics replacing in some critical applications the most common Ti6Al4V. However, these near-beta titanium alloys have a poor machinability rating which needs to be overcome so as to maintain at least the same productivity levels as in Ti6Al4V.This paper presents the machinability results carried out for Ti555.3 compared with the commonly used Ti6Al4V. The aim of this research work is to understand tool wear mechanisms when machining Ti555.3. Analysis of variables such as cutting forces, chip geometry and tool wear shows that: (I) greater difficulty is encounterd when machining Ti555.3 alloy compared with Ti6Al4V alloy which can be machined at higher speeds up to 90 m min^?1; (II) there was a correlation between the mechanical properties of work material, tool wear, and component forces; (III) the occurrence of the diffusion process leads to the formation of a layer of adhered material composed of Ti and TiC on the tool's rake face for both Ti alloys.     

切削奥氏体不锈钢(1Cr18Ni9Ti)时JX-2新型陶瓷刀具的切削性能

此文研究了新型陶瓷刀具JX－2（JX－2－Ⅰ和JX－2－Ⅱ）切削不锈钢（1Cr18Ni9Ti）时的切削性能，并同JX－1刀具进行了比较，结果表明，其抗磨损能力次序为：JX－2－Ⅲ＞JX－2－1＞JX－1，但JX－2－1和JX－1的磨损相差不大；同时研究了切削速度v和送给量f，对JX－2－Ⅰ刀具磨损的影响，发现u＝20m／min，f＝0．15～0．25mm／r时刀具磨损最小；SEM分析表明，刀具的主要失效形式为后刀面磨损、前刀面月牙洼磨损和刀刃微崩，刀具磨损的主要讲理是粘结磨损和磨粒磨损。     

Wear mechanisms of PVD ZrN coated tools in machining

Medium-frequency magnetron sputtered PVD ZrN coatings (ZrN, ZrN/Zr) were deposited on YT15 (WC + 15%TiC + 6%Co) cemented carbide. Microstructural and fundamental properties of these ZrN coatings were examined. Dry machining tests on hardened steel were carried out with these coated tools. The wear surface features were examined by scanning electron microscopy. Results showed that deposition of the PVD ZrN coatings onto the YT15 cemented carbide causes great increase in surface hardness. The ZC-1 coated tool (ZrN/YT15 without interlayer) has the highest surface hardness; while the ZC-2 (ZrN/Zr/YT15 with a Zr interlayer) shows the highest adhesion load for the coatings to the substrate. The ZrN coated tools exhibit improved rake and flank wear resistance to that of the YT15 tool. The coated tools with a Zr interlayer (ZC-2) have higher wear resistance over the one without Zr interlayer (ZC-1). The rake wear of the ZrN coated tools at low cutting speed was mainly abrasive wear; while the mechanism responsible for the rake wear at high cutting speed was determined to be adhesion. Extensive abrasive wear accompanied by small adhesive wear were found to be the predominant flank wear mechanisms for the ZrN coated tools.     

小直径磨棒磨削加工TiC颗粒增强钢基复合材料GT35

为探究TiC颗粒增强钢基复合材料GT35合理的加工参数和冷却润滑条件,研究其对切削力、表面质量及刀具磨损的影响规律,采用小直径磨棒以侧面磨削方式开展试验。结果表明：干磨削会引起磨棒烧伤,极压磨削油的润滑效果优于水基合成磨削液的;磨棒在极压磨削油润滑下,磨削工件12 min后进入稳定磨损状态,其主要磨损形式为磨粒破碎、磨粒磨耗和磨粒脱落;主轴转速对切削力的影响大于进给速度的,且转速越高,切削力越小;工件表面粗糙度主要与磨棒磨粒出露高度的平整度有关,受加工参数的影响较小。用小直径磨棒磨削加工GT35材料时,应选择极压磨削油润滑,高主轴转速、中速进给的加工方式,以获得良好的刀具寿命、工件加工表面质量及适当的加工效率。     

Wear patterns and wear mechanisms of cutting tools used during the manufacturing of chopped carbon fiber

Chopping carbon fiber is an efficient way to manufacture short carbon fiber reinforced plastic (SCFRP). Drastic wear of cutting tools during this process has been observed because of the highly abrasive nature of carbon fiber. Wear patterns and wear mechanisms need to be investigated to reduce tool wear and prolong tool life. This paper presents the formation and transition of wear patterns during the chopping process. The chopped rate is less than 95% after 21k cuts; thus, tool specimens and data are collected from the initial 21k cuts. Overall, the wear forms a crescent shape along the tool edge at one cutting position. This wear pattern is due to an uneven wear volume caused by the uneven distribution of filaments in the fibers, which forms an oval profile of the chopped carbon fiber. The oval profile results in more crescent shaped wear, which causes a more uneven filaments distribution, leading to a high wear rate. Conical structures at the ends of the chopped carbon fiber and micro scratches on the tool edge are observed. Thus, the abrasive wear mechanism during chopping is verified. The wear pattern on the tool profile is a combination of cutting edge rounding (CER) and rake face wear. Two wear stages divided by 8k cuts are introduced: the CER wear stage (before) and rake face wear stage (after). In the CER wear stage, the wear rate is basically stable at 32 μm/2k cuts and the wear pattern is an increasing CER up to 20 μm. The rake angle is approximately stable at 79°. In the rake face wear stage, the wear rate begins to increase and the wear pattern transitions from the CER wear to massive rake face wear in which the CER decreases and leans towards the flank face and the rake angle rapidly decreases. The CER decreases to 4 μm, and the rake angle decreases to 14° at the end. The wear pattern includes a groove that appears on the tool rake face in this stage, which is similar to crater wear on the rake face of a traditional turning tool because of the low hardness of the tool interior. Moreover, analytical models based on 3-body abrasive wear theory are developed to explain these wear patterns and wear mechanisms.     

Influence of the direction and flow rate of the cutting fluid on tool life in turning process of AISI 1045 steel

High-pressure coolant (HPC) delivery is an emerging technology that delivers a high-pressure fluid to the tool and machined material. The high fluid pressure allows a better penetration of the fluid into the tool–workpiece and tool–chip contact regions, thus providing a better cooling effect and decreasing tool wear through lubrication of the contact areas.The main objective of this work is to understand how the tool wear mechanisms are influenced by fluid pressure, flow rate and direction of application in finish turning of AISI 1045 steel using coated carbide tools.The main finding was that when cutting fluid was applied to the tool rake face, the adhesion between chip and tool was very strong, causing the removal of tool particles and large crater wear when the adhered chip material was removed from the tool by the chip flow. When cutting fluid was not applied to the rake face, adhesion of chip material to the face did occur, but was not strong enough to remove tool particles as it moved across the face, and therefore crater wear did not increase.