The development of technology of coating cutting tool reachs application

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Of cutting tool material choose a decision at cutting condition, also decide the face will be weighed to grind at which. For example, if of cutting tool before knife face is weighed to grind, use contain the high-speed steel that get the meeting is more advantageous, after because be before cutting tool,knife face does not have coating ' , this kind of steel more be able to bear or endure crescent moon wears away depression. The progress of cutting tool material, appeared all sorts of high-speed steel, hard alloy, pottery and porcelain that add pliable but strong, mill radical cermet, get together taste diamond and C, of the material qualitative cutting tool such as BN use, improved the treatment efficiency of metallic cutting greatly. The cutting tool of every kinds of material has respective actor drawback, have specific use consequently. Cutting tool life and film are deep also have particular concern. After be like, knife face wears away for fiducial, along with film thick also can increase cutting tool life, but film is deep saturation is reached when be 5 μ M, namely life increases apparently no longer; But if knife face crescent moon is depression before what deepness is cutting tool life is fiducial, cutting tool life and film are deep into direct ratio, did not discover saturated phenomenon. When velar layer is too thick easy cause come off, the coating ply of lathe tool is M of μ of 5 μ M-10 more now. Coating cutting tool raised new requirement to appearance of cutting tool geometry. Think commonly, the improvement of appearance of cutting tool geometry, the horn before be like, space that discharge bits, should center on the ability that discharge bits, increase in order to get used to what below taller feed and higher rate cutting measures. Coating cutting tool has taller treatment efficiency, the feed with its taller be patient of and cutting speed (can add the times) of 2-3 to former cutting speed. To difficult treatment material, coating is bigger to improvement of cutting tool performance. To the horniness coating of milling cutter, the effect with deep film is not same however. When undertaking to steeliness workpiece milling is machined, no matter use layer of which kinds of film, film is deep life of the cutting tool when M of about 2 μ is the longest, film is deep the life when increasing again drops instead. But lesser to pounding action cast-iron wait when undertaking machining, the direction of optimal film thick Xiang Genghou changes. In milling, tiC coating has best effect, and Al2O3 coating does not show the advantage in going out to be machined in turning however. Hard alloy cutting tool uses CVD law plated film normally, but processing of PVD plated film causes point intensity to drop scarcely, milling cutter of PVD film hard alloy is more durable than CVD film. To the wear-resisting caustic function of cutting tool of general high-speed steel, CVD coating wants excel PVD coat, but accurate, appearance the costly, high-speed steel cutting tool that cannot grind again is complex, price more PVD plated film. The effect that produces horniness coating the use result that should improve coating cutting tool, adequately is one quite sophisticated technology. Optimize combination to achieve, build database of coating cutting tool, to different workpiece, will choose material of cutting tool coating and treatment parameter through the computer, the circumstance becomes simple and effective, achieve the treatment goal of high grade, efficient, low cost truly thereby. The horniness film of cutting tool surface is like next requirements to material: ① hardness performance of tall, wear-resisting is good; ② chemical performance is steady, do not produce chemical reaction with workpiece material; ③ heat-resisting is able to bear or endure oxidation, coefficient of friction is low, adherent and as firm as matrix wait. Onefold coating material achieves afore-mentioned technical requirements very hard entirely. The development of coating material, already by original onefold TiN coating, TiC coating, experienced the development level of the multivariate and compound coating such as TiC-Al2O3-TiN compound coating and TiCN, TiAlN, newest now developed TiN/NbN, TiN/CN, wait for multivariate and complex filmy material, make the function of cutting tool coating had very big rise. In horniness coating material, craft the most mature, application is the widest is TiN. Current, the utilization rate of cutting tool of high-speed steel of coating of TiN of industrial developed country already occupied the 50%-70% of high-speed steel cutting tool, the utilization rate of the complex cutting tool that some cannot grind again already exceeded 90% . Because contemporary metal cutting has very high technology to ask to the knife, tiN coating cannot suit increasingly. Of TiN coating be able to bear or endure oxidisability is poorer, when use temperature amounts to 500 ℃ , velar layer oxidizes apparently and by ablation, and its hardness also cannot satisfy need. TiC has taller microscopical hardness, the wear-resisting performance of this material is consequently better. At the same time of it and matrix adherent and firm, in preparation multilayer when wear-resisting coating, often regard the rock-bottom film that contacts with matrix as TiC, in coating cutting tool it is very commonly used coating material. The development of Nextpage TiCN and TiAlN, make again on the function of coating cutting tool a step. TiCN can reduce the internal stress of coating, raise the tenacity of coating, increase the ply of coating, prevent crackle diffuse, reduce blade of cutting tool collapse. Be TiCN setting coating cutting tool advocate wear-resisting layer, can improve the life of cutting tool significantly. TiAlN chemical stability is good, fight oxidation to wear away, when machining alloy of tall alloy steel, stainless steel, admire, nickel alloy, improve life than TiN coating cutting tool 3, 4 times. If have higher Al concentration,be in in TiAlN coating, when cutting coating surface can generate a very thin blame to taste voice Al2O3, form diaphragm of laziness of a horniness, this coating cutting tool can be used effectively at treatment of high speed cutting. The TiCNO of azotic carbonization titanium of mix into oxygen is had very tall microscopical hardness and chemical stability, can produce the effect that is equivalent to TiC+Al2O3 compound coating. A few transfer metallic nitride, carbide, boride and their multivariate and compound compound, some has quite tall hardness, these material can develop cutting tool of layer of applied Yu Tu, will make the function of coating cutting tool has new breakthrough. In afore-mentioned horniness film stuff, microscopical hardness HV can exceed 50GPa have 3 kinds: Diamond film, cubic nitrogen changes boracic CBN, nitrogen to change carbolic β - C3N4. The occurrence of the material of freeboard hardness film with these not much amount to, developed filmily to monarch for horniness of coating cutting tool the need that very exiguous and costly natural diamond cannot satisfy modern industry far. 20 centuries 50 time metaphase, company of American general motors synthesized diamond artificially, get grain shape and pulverous shape diamond. Because grain shape diamond machines difficulty, besmear it very hard to cutting tool surface. Mechanical industry gets together commonly usedly taste diamond razor blade (PCD) also because geometrical figure is single, do not have bits chamfer and reasonable geometrical parameter, restricted the play of its function. Method of deposit of low-pressure and chemical gas phase was used to synthesize diamond film at the beginning of 70 time, tackle key problem through 20 old techniques, low-pressure gas phase synthesized the technology of diamond to have major breakthrough eventually, study diamond makes cosmopolitan popular task. Diamond and black lead are body of the abnormity that be the same as element, diamond savors put oneself in another's position is cubic strain, belong to Fd3m space group; And black lead is 6 horn strain, belong to R3m space group. Because the bond kind between atom is different, make its function difference very vast. From the point of thermodynamic theory, black lead is stabler than diamond. Low-pressure gas phase grows diamond, in carbolic phasor, it is the area that in black lead for stable state diamond is metastable state undertakes inside the country. However, because the chemical situation of two-phase is very adjacent, two-phase can be generated. The crucial technology of diamond of synthesis of low-pressure gas phase is to control black lead appearance, stimulative diamond grows. Commonly used synthesis method has heater way, plasma enhances deposit of chemical gas phase (PECVD) , include microwave PCVD, electron whirly resonance ECR, the method such as dc and PCVD, radio frequency PCVD, dc and law of hot plasma of discharge of high frequency electric arc. The energy of the input in reaction process (wait like radio frequency power, microwave power) , the activation condition of reaction gas and optimal deserve to compare, the nucleate mode of deposit process, have conclusive effect to making diamond film. The brilliant of underlay material grow to diamond film nucleate with latticedot matrix constant the impact is very big, be in when diamond photograph and black lead photograph on underlay in the meantime when nucleate, black lead photograph is met mushroom. If be put in tall pH indicator to be met at hydrogen formerly,action is corroded since the black lead look that gives to growing and eliminate of black lead photograph, although it also can is opposite,action is corroded since diamond photograph, but speed is gotten slow however much, achieve the goal that restrains black lead photograph to grow thereby. The temperature of a lot of deposit diamond film asks to be 600 ℃ - 900 ℃ , this technology is accordingly commonly used at film of diamond of deposit of surface of hard alloy cutting tool. The commercialization of cutting tool of diamond hard alloy, be in last few years the great success of coating technology. With artificial synthesis diamond film is compared, the research work that synthesizes CBN film artificially is begun later. BN has 3 kinds of isomer: Structure of blende of ① CBN cubic strain, f43m space group; ② H, structure of black lead of BN6 square strain, p6/mmc space group; ③ W, construction of mine of zinc of fine of BN6 square strain, p63mc space group. The function difference of 3 kinds of isomer is very big, h, BN has very as similar as black lead structure, texture is very soft. And W, in BN and CBN, atom of B, N should be formed by this 4 match a structure, they are to exceed hard data. The CBN that gets with method of high temperature high pressure is grain shape crystal, highest and microscopical hardness can be amounted to 84.

3GPa, of CBN film highest and microscopical hardness is 61.

8GPa, its integral performance and no less than diamond are filmy. CBN is next to diamond in hardness and respect of heat conduction rate, thermal stability is wonderful, heat to also do not produce oxidation to 1000 ℃ in atmosphere. CBN to iron accessory of a group of things with common features gold has very stable chemical property, with diamond unfavorable treatment steel products differs, the precision work that it can use extensively at steely goods, abrade wait. CBN coating is divided outside having good wear-resisting caustic performance, still can issue treatment in quite high cutting rate alloy of refractory steel, titanium, quench steel, can carbon of the cold hard roll of cutting tall hardness, mix into quenchs material is mixed wear away to cutting tool very serious Si-Al alloy. Low-pressure gas phase synthesizes the method of CBN film to basically have CVD and PVD way. CVD includes chemical transport PCVD, heater is auxiliary heat PCVD, ECR-CVD; PVD criterion respond is ionic plating of bundle of plating, active reaction evaporate, laser evaporate plating is ionic bundle of auxiliary and deposit law. The synthetic technology of Nextpage CBN, there still are many jobs to want to do in basic research and applied technology respect, include to react the mechanism is mixed velar process, plasma is diagnosed and of condition of mass spectra analysis, optimal craft affirmatory, efficient the development of equipment. Have the cutting tool that exceeds hard coating wear extent is small, because velar layer exceeds the hardness of hard compound,be tall, melting point stability of tall, thermochemistry is excellent be caused by. Exceed hard compound to be more transfer metallic nitride, carbide and boride place composition. They are united in wedlock with powerful covalent bond, have very low level to create freedom can, made very stable system, below high temperature hardness also is not reduced significantly. These velar layers are shown than the cutting tool material such as hard alloy and high-speed steel taller be able to bear or endure mechanical wear and heat-resisting wear away the ability that waits for a respect. Pretreatment of the matrix before parameter of plated film condition, craft, plating to high grade coating make taking is special important. The position of cutting tool surface is crucial to the adherent force of coating, must be done not have by plating workpiece surface other film layer, burn spot, rusty spot, smeary or other flyblow. Workpiece should pass strict gush arenaceous and go oil is cleaned, undertake before horniness film grows in vacuum ionic bombard is cleaned even. The cutting tool of different coating material, use effect is different. Low speed cutting, tiC coating has an advantage; High speed cutting, tiN is more appropriate; The thermochemistry stability of HfN is taller than TiN, agree with to work below higher cutting rate. TiN and A1203 coating photograph are compared, coating of the A1203 when high speed cutting has clear advantage, and the service life of cutting tool of coating of the TiN when low speed cutting is longer. Coating cutting tool and not photograph of coating cutting tool is compared, have distinct advantage: It can improve treatment efficiency, raise treatment precision, prolong cutting tool service life, assure to add the quality of workpiece thereby, reduce finished cost. Modern metallic cutting is machined, it is tall cutting speed, tall feed speed, high reliability, macrobian life, high accuracy and good cutting to the requirement of cutting tool control a gender. The occurrence of coating cutting tool, make function of cutting tool cutting had major breakthrough, it combines cutting tool matrix and look of horniness film surface layer, because matrix retained good tenacity and higher strength, horniness film surface layer has tall wearability and low coefficient of friction again, make the function of cutting tool rises greatly thereby. CNC Milling