硬质合金刀具使用分析

合理使用和选择硬质合金刀具是为了保证提高刀具的使用寿命,降低加工成本从而提高生产效率和经济效益。

发绣技法“金刀劈发”真实性考辨

金刀劈发"是文献记载中的一种古代发绣技法,是使用薄如蝉翼的金刀将头发纵向剖成细丝用于刺绣的一种方法。这种技法今天已经失传,并在学术界留下众多关于其"真实性"的争议。本文从六个方面对"金刀劈发"技法的真实性进行了论证。

从金刀出鞘拳解析青城派功夫

金刀出鞘拳是青城绿林派的基础拳法。很多人听到基础拳法就不屑一顾，一心想学高级武功，其实万丈高楼平地起，没有基础哪有高级，青城武术还有一句话叫“大道至简”，意即最好的功夫就是最简单的。所以等你练完高级武功再跟人打斗时，你会发现你打败对手往往并不是用的高级功夫中的某一招，恰恰是基础功夫里的某一手。

南北朝隋唐时代的金刀之谶与弥勒信仰

一种观念要影响政治大势,往往需要植根于大众广泛接受的思想或信仰系统。金刀之谶作为一种政治观念,发端于与今文经学结合紧密的谶纬之学,在汉朝灭亡前后与早期道教结合,北魏以后则转向与弥勒信仰结合,深刻地影响了南北朝隋唐时期的政治起伏。"刘氏当王"与"李氏将兴"反映的政治文化传统不同。"道君出世"与"弥勒下生"两种信仰的竞争,和由"刘氏"还是"李氏"统治天下的世俗权力之争纠缠在一起,制约了其时的政治走向。

金刀祸

北风呼啸着,便卷起了漫天的飞雪,天空中像是有千床万床的棉被被当空撕碎,落下千万片棉絮。金刀山中早已是百里冰封,仿佛遁入了神话里的琉璃世界,触目可及都是茫茫的一片白。不过,倘若视线拉近一些,你会发现万白丛中有一点红,一点凄艳的红。视线再拉近些,那点红便慢慢扩大,在无边的白纸中肆意涂抹着,形成了一朵绝美的花朵。而这片红色的主人此时正躺在冰天雪地里。

110kV母线电压合格率分析

220kV金刀营变电站是昆明电网主供昆明北市区的重要变电站,近期发现220kV金刀营变电站110kV母线电压合格率有所降低,夜间110kV电压越上限情况突出,为此,需要对220kV金刀营变电站110kV母线电压合格率进行认真分析,寻找解决措施。

TOOL WEAR PATTERNS AND MECHANISMS OF SOLID CEMENTED CARBIDE IN HIGH-SPEED MILLING OF ALUMINUM ALLOY

The wear patterns and wear mechanisms of solid cemented carbide are analyzed in high-speed milling of aluminum alloy. Results show that the dominant wear patterns are coating damage, crater wear, micro-chipping, breakage, and so on. The main wear mechanisms are adhesion, diffusion and fatigue. Compared with conventional speed machining, the effect and impact of thermal-dynamical coupling field play an important role in the cutting tool wear in high-speed milling of aluminum alloy.

MILLER WEAR IN MILLING Ti ALLOY WITH NITROGEN GAS MEDIA

Milling Ti alloy is a very difficult technology. The primary problem is that the miller wear is very rapid and makes the miller break or rapture. Although cutting fluid is mainly used to reduce friction and temperature in cutting area to enhance tool life, it is the largest source of environmental pollution. To develop a technology for the clean and efficient milling Ti alloys, nitrogen gas is used as a cutting media in this paper. Based on lots of experiments and researches, the tool life and wear mechanism of high speed steel miller is analyzed. A conclusion is drawn that, milling with nitrogen gas media yields much longer tool life than dry milling. Tool life equations (Taylor′s equations) are derived for both milling types.

FABRICATION OF DLC COATED COBALT-CEMENTED TUNGSTEN CARBIDE MICRO-DRILLS AND THEIR CUTTING PERFORMANCE

In machining the particle reinforced aluminum based composite material with high Si content using the cobalt-cemented tungsten carbide micro cutting tools, diamond like carbon （DLC） films are deposited on cobalt-cemented tungsten carbide micro-drills with two-step pretreatment method. Characteristics of DLC coated tools are investigated in bias-enhanced HFCVD system with the optimized hot filament arrangement. The optimization deposition technology is obtained and the wear mechanism of cutting tools is analyzed. The drilling performance of DLC coated tools is verified by the experiments of cutting particle reinforced aluminum based composite material （Si 15% in volume） compared with uncoated ones. Experimental results show that the two-step pretreatment method is appropriate for complex shaped cemented carbide substrates and ensures the good adhesive strength between the diamond film and the substrate. The cutting performance of DLC coated tool is enhanced 10 times when machining the Si particle reinforced aluminum based metal matrix composite compared with that of uncoated ones under the same cutting conditions.

MACHINING OF METAL MATRIX COMPOSITES

Two types of aluminium-based composites reinforced respectively with 20 vol short fibre alumina and with a hybrid of 15 vol SiC particle and 5 vol short alumina fibre are machined with different tool materials:cemented carbide,ceramic,cubic boron nitride(CBN)and polycrystalline diamond(PCD).The analysis on tool wear shows that the various tool materials exhibite different tool wear behaviours,and the tool wear mechanisma are discussed.Apparently,PCD tools do not necessarily guarantee dimensional stability but they can provide the most economic means for machining all sorts of composites.Consequently,a suitable tool material is suggested for machining each metal matrix composite(MMC) from the standpoints of tool wear and machined surface finish.

An Analysis of the Structure of Carbide-tool Utilization Expert System

The necessity and feasibility of an expert system for carbide-tool utilization are analyzed and a practical system named CUES(carbide-tool utilization expert system ) is developed and realized. The system concept, module structure, data management, inference strategy and the interface design of the system are discussed in.detail. The system would be useful not only for the preparation of tool bank of FMS or CIMS, but the for the proper application of cemented carbide tools in conventional machining Processes.

Failure Mechanism of CVD Coated Carbide Tools

Through systematically theoretical analysis and experimental research,the failure mechanism,of CVD(chemical vapor deposition) coated carbide tools in wear and fracture conditions was studied.On the basis of mechanism analysis,the specific suitability of the coated tools for cutting conditions was revealed and clarified.

Experimental and FEM Study of Coated and Uncoated Tools Used for Dry Milling of Compacted Graphite Cast Iron

Compacted graphite cast iron （CG1） has been the material for high-power diesel engines recently, but its increased strength causes poor machinability. In this study, coated and uncoated carbide tools were used in dry milling experiment and FEM simulation to study the machinability of CGI and wear behaviour of tools. The experimental and FEM simulation results show that coated tool has great advantage in dry milling of CGI. SEM and EDS analysis of tool wear indicate the wear morphology and wear mechanism. Adhesive wear is the main mechanism to cause un- coated tool wear, while abrasive wear and delamination wear are the main mechanism to cause coated tool wear. Stress and temperature distribution in FEM simulation help to understand the wear mechanism including the reason for coat- ing peeled off.

Failure analysis of polycrystalline diamond compact cutters for breaking rock by bending waves theory

The breakage mechanism of the polycrystalline diamond compact(PDC) cutters was analyzed by the energy theory of bending waves. The cutting tests of granite block were conducted on a multifunctional testing device by using the cutter at three kinds of negative fore angles of 30°, 45° and 60°. The results show that, when the edge of the PDC layer is broken, the layer of tungsten cobalt is broken a little under the angle of 30°, while the layer of tungsten cobalt is broken continuously under the angle of 60°, their maximum depths are about 2 and 7 mm respectively in the two cases. The eccentric distance mainly depends on the negative fore angle of the cutter. When the cutter thrusts into the rock under an attack angle of 60°, the energy of bending waves reaches the maximum since the eccentric distance is the maximum. So the damage of cutter is the most serious. This test result is consistent with the conclusion of theoretical analysis well. The eccentric distance from the axial line of cutter to the point of action between the rock and cutter has great effect on the breakage of the cutter. Thus during the process of cutting, the eccentric distance should be reduced to improve the service life of PDC cutters.

Milling Machinability of TiC Particle and TiB Whisker Hybrid Reinforced Titanium Matrix Composites

The milling machinabilities of titanium matrix composites were comprehensively evaluated to provide a theoretical basis for cutting parameter determination. Polycrystalline diamond （PCD） tools with different grain sizes and geometries, and carbide tools with and without coatings were used in the experiments. Milling forces, milling temperatures, tool lifetimes, tool wear, and machined surface integrities were investigated. The PCD tool required a primary cutting force 15 % smaller than that of the carbide tool, while the uncoated carbide tool required a primary cutting force 10% higher than that of the TiA1N-eoated tool. A cutting force of 300 N per millimeter of the cutting edge （300 N/mm） was measured. This caused excessive tool chipping. The cutting temperature of the PCD tool was 20%-30% lower than that of the carbide tool, while that of the TiA1N-coated tool was 12% lower than that of the uncoated carbide tool. The cutting temperatures produced when using water-based cooling and minimal quantity lubrication （MQL） were reduced by 100 ~C and 200 ~C, compared with those recorded with dry cutting, respectively. In general, the PCD tool lifetimes were 2--3 times longer than the carbide tool lifetimes. The roughness Ra of the machined surface was less than 0.6μm, and the depth of the machined surface hardened layer was in the range of 0.15-0.25 mm for all of the PCD tools before a flank wear land of 0.2 mm was reached. The PCD tool with a 0.8 mm tool nose radius, 0% rake angle, 10% flank angle, and grain size of （30＋2） μm exhibited the best cutting performance. For this specific tool, a lifetime of 16 rain can be expected.

Analysis and optimization of drilling parameters for tool wear and hole dimensional accuracy in B_4C reinforced Al-alloy

Cutting parameters were evaluated and optimized based on multiple performance characteristics including tool wear and size error of drilled hole. Taguchi＇s L27, 3-level, 4-factor orthogonal array was used for the tests. It is shown that generally abrasive wear and built up edge （BUE） formation were seen in the tool wear, and the comer wear was also of major importance. Flank wear of the cutting tool was found to be mostly dependent upon particle mass fraction, followed by feed rate, drill hardness and spindle speed, respectively. Among the tools used, TiAlN coated carbide drills showed the best performance with regard to the tool wear as well as hole size. Grey relational analysis indicated that drill material was the more influential parameter than feed rate and spindle speed. The results revealed that optimal combination of the drilling parameters could be used to obtain both minimum tool wear and diametral error.

Effect of Radial Depth on Vibration and Surface Roughness During Face Milling of Austenitic Stainless Steel

This paper studies the influence of radial depth on vibration, chip formation and surface roughness during face milling of AISl3O4 austenitic stainless steel with indexable cemented carbide milling cutters. The amplitude of vibration acceleration increased with the increasing radial depth up to 80 mm. And the domain vibration frequency varied with the radial depth. In this paper, three types of chips were found： C shape, long shape and spiral shape. The minimum surface roughness value occurred when the radial depth equalled 40 mm in the experiment. Irregular changes of chip curl radius and chip thickness could be attributed to different numbers of alternately engaged teeth when the feed and speed were fixed. Surface roughness is related to forced vibration and chip formation. Radial depth with different numbers of alternately engaged teeth could significantly influence the forced vibration, chip formation, and surface roughness.

Wear of CVD thick film diamond cutter while machining laminated flooring

The wide application of high pressure laminated (HPL) flooring has an insistent need for cutting tools with an excellent performance and fine cutting quality. Chemical vapor deposition (CVD) thick film diamond is a promising material for the machining of HPL flooring. In the present work, CVD thick film diamond tools were used to mill the wear resistance layer of HPL flooring. Wear volumes of flank face were examined by optical microscopy, and micro wear morphologies were observed by scanning electron microscopy (SEM). The experiments revealed that the predominant wear characteristics of CVD diamond tools were transgranular cleavage wear and intergranular peeling of the CVD diamond. Experimental results also showed that twin characteristic, cavity defect, micro crack and grain size of CVD thick film diamond contributed greatly to the wear process of CVD thick film diamond tools. The effects caused by the factors were also analyzed in detail in the paper.

Thermal residual stress of polycrystalline diamond compacts

Thermal residual stresses in polycrystalline diamond compact(PDC)cutter arising from the difference in thermal expansion between the polycrystalline diamond(PCD)and the supporting tungsten carbide substrate after sintering at high pressure and high temperature were investigated using finite element simulation,laboratory tests and theoretical analysis.The obtained results show that although compressive residual stresses exist both in the interface of PCD table and in the most region of PCD table surface, the tensile residual stress,which is a fatal shortage to PDC,can also occur near the outer diameter area of PCD table,and the maximum value is 690 MPa.Distribution of tensile stress in the PCD table is given through experimental results,which is well consistent with the numerical results.This finding may be significant in designing new PDC cutters with lower residual stress and high cutting behavior.

Characterization of shear stresses in nickel-based superalloy Mar-M247 when orthogonal machining with coated carbide tools

Mar-M247 is a nickel-based alloy which is well known as difficult-to-machine material due to its characteristics of high strength, poor thermal diffusion and work hardening. Calculation of shear stress by an analytical force model to indicate the effect of coating material, cutting speed, feed rate on tool life and surface roughness was conducted experimentally. Cutting tests were performed using round inserts, with cutting speeds ranging from 50 to 300 rn/min, and feed rates from 0.1 to 0.4 mm/tooth, without using cooling liquids. The behavior of the TiN and TiCN layers using various cutting conditions was analyzed with orthogonal machining force model. Cutting results indicate that different coated tools, together with cutting variables, play a significant role in determining the machinability when milling Mar-M247.