玻璃钢圆锥管螺纹的车削加工

圆锥管螺纹连接在玻璃钢制品中应用非常普遍，许多制品的连接都离不开它。由于玻璃钢材料的特殊性，导致其螺纹加工质量难以保证，其中突出的问题是螺纹掉尖、掉扣、掉渣、表面烧蚀等，刀刃烧伤和磨损也比较严重，有时达到无法切削的程度。圆锥管螺纹加工是玻璃钢切削加工最难以掌握的工序之一。通过长期的切削加工实践，逐步地对玻璃钢圆锥管螺纹切削加工有了一些认识，初步掌握了玻璃钢圆锥管螺纹加工的一般规律。1 刀具的选择与加工方法 加工玻璃钢圆锥管螺纹的刀头材料一般采用ＹＧ８，正刃倾角λ０°－３°较为合适，两侧刃还应磨成大…     

车刀几何角度对切削的影响及选择

车刀几何角度是确定车刀切削部分几何形状,保证刀具切削性能的重要参数,合理选择车刀几何角度是保证加工质量、提高效率、降低成本的有效途径,本文从车刀几何角度对切削力、切削热和耐用度等方面的影响,分析车刀几何角度选择的一般原则。     

金刚石复合片刀具磨损机理研究

选用平均粒度10微米的金刚石复合片制成刀具,对高硅铝合金(Al-30wt%Si)进行切削实验。通过扫描电子显微镜分析了工件的形貌以及金刚石刀具前后刀面磨损的微观形貌。其磨损程度与切削路程为线性关系,金刚石刀具的磨损主要是后刀面机械摩擦磨损以及前刀面的粘接磨损,而没有出现像立方氮化硼刀具的化学磨损以及月牙洼磨损。     

UPC-T超精金刚石刀具加工

UPC-T是一种采用三角切削刃的UPC超精金刚石刀具，主要用于菲涅尔透镜模具和液晶导光板等衍射光栅模具的超精加工。近年来，光学元件的高精密化、小型化和集成化发展迅速，从非球面透镜到能够实现薄型轻量化、集成化的菲涅尔透镜，对超精加工技术的要求越来越高。本加工模式是用1把UPC-T超精金刚石刀具超精加工微细光栅部分和非球面形状的实例，因此要求车刀刀尖切削刃R〈100nm并具有优异的切削性能。UPC-T的刀尖切削刃为50nm的微小切削刃，能够实现超精加工。     

钢铁冶金用炭素材料(二)(续15)

钢铁冶金用炭素材料（二）（续１５）刀具及其切削参数加工石墨电极时使用硬质合金（如牌号ＹＧ８）或高速钢（如牌号Ｗ１８Ｃｒ４Ｖ）制成的车刀及铣刀进行切削。高速钢刀具坚韧性好、刃磨方便、价格较低，但红硬性稍差，只能耐５００－６００℃。硬质合金刀具具有良好的...     

PcBN刀具在干切削中的应用研究

文章探讨了干切削对刀具、工件和机床的要求,并从PcBN刀具干切削金属软化效应、加工表面质量以及刀具磨损等方面介绍了PcBN刀具在干切削中的适应性研究方面的进展情况,以期引起重视,更充分发挥PcBN刀具的潜在性能。     

弹簧式角度可调节机夹车刀研究与应用设计

涉及一种车床用切削大螺旋升角的弹簧机夹式螺纹刀具。此车刀通过旋转刀头的角度,可以车削不同螺距或旋向的螺纹,具有良好的技术经济效果,因此得到了方泛的应用。下面详细的介绍一下这把刀的结构及实施方法。     

基于CVD金刚石涂层刀具的CFRP高速铣削切削力的试验研究

碳纤维增强复合材料(CFRP)是一种典型的难加工材料,文章利用化学气相沉积(CVD)金刚石涂层刀具以及Kistler 9129AA型测力仪,基于单因素实验法,探索了切削参数对CFRP加工过程中切削力、工件表面质量、刀具磨损的影响。实验结果显示：提高主轴转速可有效降低CFRP加工时的切削力,但随着切削深度和进给量的增加,切削力仍显著增加;CVD金刚石涂层刀具在切削42 m后,涂层出现剥落,主要原因是刀具表面与切屑产生磨粒磨损,并且刀具硬质合金基体与涂层热膨胀系数不同,在刀具温度升高的情况下使涂层出现裂纹,加快了涂层的剥落;如果想获得较好的表面质量和更少的加工缺陷,应该选用顺铣、大转速、小进给量及小切削深度。     

含三元烧结助剂的氮化硅陶瓷刀具切削性能研究

利用三元烧结助剂MgO-Lu_2O_3-Re_2O_3(Re代表La、Gd、Er、Yb)对Si_3N_4陶瓷粉体进行热压烧结制成刀具,对一部分SN-Lu Yb样品再进行热处理,以使Si_3N_4陶瓷晶间玻璃相转变为结晶相。对以上所有样品进行断裂韧性、维氏硬度和XRD测试,然后在同工况下切削铸铁HT250。采用SEM和EDS分析切削后刀具的磨损表面形貌和元素成分。研究表明,利用三元烧结助剂MgO-Lu_2O_3-Re_2O_3烧结制备的Si_3N_4陶瓷样品完全满足切削刀具的使用要求,在切削铸铁HT250实验中,刀具磨损形式主要为磨粒磨损和粘结磨损,所有样品的切削寿命均超过了进口同型号Si_3N_4刀具,另外,经过热处理的SN-LuYb的切削寿命大幅提高了137%,说明晶间第二相对Si_3N_4陶瓷的抗磨损能力有决定性影响。     

Si3N4陶瓷刀具在切削淬硬钢时的磨损行为

采用两种Ｓｉ２Ｎ４刀具在普通车床上对ＣｒＷＭｎ和４５钢进行切削试验，并用ＳＥＭ，ＥＤＡＸ，ＸＰＳ等方法对刀具的磨损进行分析。结果指出：试验的陶瓷刀具材料在切削不同淬硬钢时均存在最佳切削速度。在ＦＤ０１相比，ＦＤ０２陶瓷刀具有更佳的切削性能，最佳切削速度可提高７８％。在最佳速度以下切削，刀具侧面将发生粘着磨损；在最佳速度以上，则被加工材料产生微区熔化，导致材料大面积转移，发生剥层磨损，最佳速度以下切     

Segment wear characteristics of diamond frame saw when cutting different granite types

An experimental study was carried out to determine the influence of rock properties on segment wear during the cutting of granite using an innovative diamond frame saw prototype. Wear is the main cost of frame saws with diamond-impregnated segments. Ten different granite types with a large market demand were cut by a stone-processing company. The diamond segment topography was studied. The microscopic appearance and a statistical analytical method were used to study the wear characteristics. The main diamond particle abrasion types are whole and micro-fractured crystals. No polished diamond particles resulted from using the frame saw prototype cutting stone. The frame saw cuts only in a half-cycle within a reciprocating stroke. The principal wear mechanisms of the diamond particles and the matrix are impact abrasion and flushing abrasive erosion, respectively. The statistical analysis indicated that uniaxial compressive strength, bending strength and quartz content were the first three rock properties that affected segment wear. The developed mathematical model can predict segment wear for manufacturers and users.     

Cutting performance of microwave-sintered sub-crystal Al2O3/SiC ceramic tool in dry cutting of hardened steel

Tool life and failure mechanisms of a microwave-sintered sub-crystal Al₂O₃/SiC ceramic tool (AS) in dry turning hardened steel were studied. The AS tool with plane face shows better cutting performance and wear resistance than the commercial ceramic tool SW500 and cemented carbide tool YG8 at both low and high cutting speeds. It's suitable for dry cutting at high speed (210–270 m/min), the cutting distance is 5–8 times longer than that of other two tools. The results indicate that the ceramic tool fabricated by this pressureless sintering technology can satisfy the requirements of high-speed machining. Wear forms of AS tool at low cutting speed are slight crater wear and groove wear, which were mainly caused by abrasion. At high cutting speed, tool failure forms are cater wear, groove wear and slight chipping caused by severe abrasion and adhesion.     

Tool life and wear of WC–TiC–Co ultrafine cemented carbide during dry cutting of AISI H13 steel

WC–5TiC–10Co ultrafine cemented carbides were prepared and used for the cutting tool for AISI H13 hardened steel. The effect of cutting parameters on the tool life and tool wear mechanism was investigated, and conventional cemented carbide with the same composition and medium grain size were prepared for comparison. The results showed that WC–5TiC–10Co ultrafine cemented carbides possess higher hardness and transverse rupture strength, and showed better cutting performance than conventional insert with the same cutting condition. Tool life was analyzed by an extended Taylor's tool life equation, indicating that cutting speed played a profound effect on the tool life and wear behavior of both cutting inserts. SEM and EDS analysis revealed that there were major adhesive wear and minor abrasive wear on the rake of WC–5TiC–10Co ultrafine inserts, and increase of cutting speed resulted in a transition from abrasion predominant wear mechanism to adhesive wear on the flank face. As for the conventional inserts, there were combination of more serious abrasive and adhesive wear on the rake and flank. The favorable cutting performance of ultrafine WC–5TiC–10Co inserts was attributed to the higher hardness and less thermal softening during machining.     

Performance and wear mechanism of spark plasma sintered WC-Based ultrafine cemented carbides tools in dry turning of Ti–6Al–4V

Cutting performance and failure mechanisms of spark plasma sintered (SPS) ultrafine cemented carbides in dry turning Ti–6Al–4V were studied. The tools of UYG8 (WC-8wt%Co) and UYG8V2B10 (WC-8wt%Co-0.2 wt%VC-1.0 wt%cBN) exhibited higher lifetime and better processing quality than the commercial YG8 cemented carbide tool. The cutting distance of UYG-8 and UYG8V2B10 tools are 1.8 and 1.6 times longer than that of YG8, respectively. Cutting-edge breakage was found as the main failure forms of the SPS cemented carbide tools containing low Co content (≤6 wt%), whereas the SPS cemented carbide tools containing high Co content (≥8 wt%) exhibited flank and rake wear as main failure forms caused by abrasion, adhesion, diffusion, and oxidation. UYG8V2B10 tool wear mechanism was affected by cutting speed and depth. Wear mechanisms of UYG8V2B10 tool are mainly adhesive wear and oxidative wear at low cutting speed, but follow adhesive wear and diffusive wear at higher cutting speed. Moreover, with increasing cutting depth, tool failure forms are mainly breakage and chipping, largely induced by high cutting temperature and severe cutting vibration.     

Enhancing cutting performance of Ti(C,N)-based cermet tools on nodular cast iron by incorporating high-entropy carbide

In this study, we investigated the cutting performance and wear mechanisms of Ti(C,N)-based cutting tools containing varying weight percentages (0%, 5%, 10%, and 15%) of high-entropy carbide (HEC) (V_0.2Nb_0.2 Mo_0.2Ta_0.2W_0.2)C phase, when used for turning nodular cast iron. According to the turning test results, the cermet cutting tools containing 0 wt%, 5 wt%, 10 wt%, and 15 wt% HEC phases demonstrated effective cutting lives of 402, 720, 632, and 465 s, respectively. The tool with 5 wt% HEC phase showed the best cutting performance. When cutting nodular cast iron with cermet cutting tools, the main wear mechanisms observed were diffusion, oxidation, adhesion, and abrasion on the flank surface, along with diffusion, oxidation, and abrasion on the rake surface. The results of this study indicated that (V_0.2Nb_0.2Mo_0.2Ta_0.2W_0.2)C could be adopted as an effective reinforced phase in the cermet cutting tools.     

Abrasion studies of nylon 6/montmorillonite nanocomposites using scanning electron microscopy,fourier transform infrared spectroscopy,and X‐ray photoelectron spectroscopy

In this article, abrasion performance of commercial nylon 6 and nylon 6/montmorillonite (MMT) nanocomposites was studied. The polymer nanocomposites showed poor abrasion resistance compared to the neat polymer. The wear loss increased linearly with clay concentration. Changes in surface morphology, composition, and structure were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR)‐attenuated total reflection spectroscopy, and X‐ray photoelectron spectroscopy (XPS). SEM images showed that all the abraded surfaces contained fractured particles. However, the abraded nanocomposite surfaces had much deeper grooves compared to the homopolymer. FTIR results showed an increase in the amount of α crystals and a decrease in the amount of γ crystals on all the surfaces after abrasion. This was attributed to the strain‐induced γ to α crystal transformation. The largest amount of α crystals was formed in the abraded surface of pure nylon 6, and the amount of α crystals formed decreased with increasing MMT content. XPS results showed an increase in the [Si]/[N] elemental ratio for all nanocomposites after abrasion, indicating an increase in the clay content of the surface. Abrasive wear mechanism is as follows: (1) tensile tearing is the dominant wear mechanism for all the samples; (2) the cutting mechanism becomes more important when MMT content increases; (3) the polymer matrix is easier to be removed than clay during the abrasion process; (4) in nylon 6/MMT systems, the poor abrasion resistance is attributed to defects at the clay‐polymer interface, resulting in greater wear of the polymer matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Tool life and wear mechanism of WC–5TiC–0.5VC–8Co cemented carbides inserts when machining HT250 gray cast iron

Cutter development has drawn a lot of attention for cast iron machining in recent years. In this study, a special cemented carbide of WC–5TiC–0.5VC–8Co (WTVC8) was used for a comprehensive HT250 gray cast iron machining test. Compared with the baseline plain WC–8Co(WC8) carbides, WTVC8 shows significantly higher tool life under the same cutting conditions due to significantly higher hardness and red hardness. The worn flank face observation shows that adhesion wear and oxidation are the main wear mechanisms and there is no apparent chipping/breakage and abrasion wear for both WTVC8 and WC8. Based on Taylor's equation, the accurate tool life models for both WTVC8 and WC8 have been constructed, which shows clearly that cutting speed has the most significant effect on tool life, followed by depth of cut and feed rate. The tool life models can serve as a quantified guidance for cutting performance optimization.     

PVD-CrAlN and TiAlN coated Si3N4 ceramic cutting tools —1. Microstructure,turning performance and wear mechanism

In this work, CrAlN and TiAlN coatings were produced on silicon nitride cutting inserts via physical vapor deposition. The microstructure and hardness of the coatings, as well as the adhesive strength between the coating and the substrate were studied using a scanning electronic microscope, a micro hardness tester and a scratch tester, respectively. Continuous turning tests of the obtained CrAlN and TiAlN-coated silicon nitride cutting inserts were performed on gray cast iron to evaluate the cutting performances and the machining quality. The results show that the surface hardness of the Si₃N₄ cutting inserts could be improved by 87% and 50%, respectively, when applying the CrAlN and TiAlN coatings, thereby enhancing the abrasion resistance of the cutting inserts. At different tested cutting speeds, abrasive wear under compressional deformation and adhesive wear were identified as the main failure mechanisms for the two cutting inserts during continuous turning of gray cast iron. The machining quality of the gray cast iron workpieces machined using the uncoated, the CrAlN- or the TiAlN-coated inserts increased with the increment of the cutting speed.     

Cutting performance and wear mechanism of Sialon ceramic tools in high speed face milling GH4099

This work aims to reveal the cutting performance and wear mechanisms of Sialon ceramic tools for the high-speed face-milling of GH4099, with the goal of improving this process as well as designing more advanced ceramic cutting tools in the future. At the outset of this study, several single-factor experiments were designed with speed as a variable to gather various data on such tools. Failure patterns and tool life curves were first obtained through cutting tests. Afterwards, the tools were split at their place of wear (middle of notch and 1/2 depth of cut) to prepare for further analysis. Wear morphology and element composition distribution in the depth direction of the corresponding interface were then analyzed using a field emission scanning electron microscope (FE-SEM) and energy dispersive spectrometer (EDS) to explore potential diffusion and/or chemical wear. Finally, studies were conducted into the tools’ chemical wear under specific cutting conditions, finishing with a theoretical verification based on the thermodynamic principle of chemical reactions. This research discovered that notch wear was the main failure pattern for the high-speed face-milling of GH4099 under the suitable cutting conditions. Overall, the optimal cutting speed was 1000 m/min, with a tool life of about 3 min. Compared with cemented carbide tools, the machining efficiency for Sialon ceramic tools increased by over a factor of 16. The wear mechanisms for such tools demonstrated a mixture effect of abrasive, adhesive, diffusive and chemical wear. Diffusive wear mainly occurred in their flank faces, but did not constitute the main mechanism of notch wear; chemical wear proved to be a key reason for notch wear at higher temperatures. Based on the aforementioned research, this paper concludes with a proposed comprehensive model for notch wear.     

遥传脉冲器磨损机理研究

遥传脉冲器转子在使用过程中存在磨损现象,这些磨损直接导致泥浆脉冲器无法实现随钻仪器采集的各种井下参数的上传。根据泥浆脉冲器转子本体磨损标准,分析泥浆脉冲器转子橡胶材质的性能、泥浆中岩屑摩擦以及外围部件缺陷所导致的泥浆脉冲器转子磨损。从设备管理过程中增加动平衡测试、改进橡胶性能、改进生产到应用过程中橡胶的存放等方法被提出,这些方法有助于降低磨损风险。研制了新型金属耐磨套替换方案,水循环和角度测试表明新型泥浆脉冲器转子性能明显改进。