Flame retardant research of processability of milling of titanium alloy Ti40

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Because titanium alloy is exceedingly good physics is mechanical with chemical character (like density low, taller than intensity, be able to bear or endure corrode sex is good wait for a characteristic) and be applied extensively the domain such as Yu Hang empty spaceflight [1] . Although its are integrated mechanical performance is good, but the application that its combustibility restricted his to fall in a few harsh ambient conditions greatly however, environment of air current of the high temperature that is like high-powered aviation engine, high pressure, below such setting, flame retardant titanium alloy emerge as the times require [2-3] . 20 centuries 90 time, already developed on international piece a variety of flame retardant titanium alloy, be like alloy of the BTT-1 of Alloy C alloy of the United States, Russia and BTT-3. Home also developed a success 1993 flame retardant titanium alloy Ti40 and Ti14. Among them, ti40 has better integrated and mechanical performance [4] , it is alloy of titanium of photograph of a kind of onefold β , β photograph stabilizes elemental content to be as high as 40% , high temperature capability is good, work for long temperature is controlled in 500 ℃ . What its regard our country as own research and development is flame retardant titanium alloy already studied old, mix in the preparation craft that concerns this alloy, flame retardation flame retardant craft of mechanism, heat treatment, thermal stability and high temperature are out of shape and the respect such as creep mechanism had certain research positive result [5-9] , but did not see the relevant research that waits for main problem about its cutting processability and report. Production carries out discovery, titanium alloy does not suit to issue treatment in dry cutting condition, and Ti40 is alloy of titanium of photograph of a kind of onefold β , to β titanium alloy, cutting processability is poorer, cutting tool life is brief, manufacturing efficiency is low [10-11] . The article regards workpiece as material with titanium alloy Ti40, basically regard material cutting as processability with cutting tool durability measure index, in cutting oil cooling condition falls, use hard alloy cutting tool and method of the experiment that arrange mill, the milling that analysed this data machines function, studied form of cutting tool invalidation is mixed wear away mechanism, undertook the contrast of cutting processability with titanium alloy TC4. 1 test data and function test data choose experiment condition and method the titanium alloy Ti40 that dimension is 50mm of × of 240mm × 90mm, its name composition is Ti-25V-15Cr-0.

2Si, heat treatment condition is quench, dissolve of the solid after high temperature temper ageing treatment, the composition of its and TC4 and performance data contrast see watch 1[12] and watch 2[9 respectively, 12] . From the watch 1 can see, compare with TC4 photograph, ti40 is the alloy of titanium of onefold β photograph that a kind of tall alloy turns, β photograph stabilizes elemental V and Cr content to be as high as nearly 40% , relatively TC4 has better mechanical performance. Material course cut, set appearance, thick cast and essence of life is cast, use metallographic to corrode fluid to deserve to compare for 2%HF+4%HNO3+94%H2O (bulk is compared) , the appearance of metallographic organization body that gets its and TC4 if metallograph pursues 1 (A) and (B) be shown. Can see, ti40 metallographic organization is grain waiting for an axis, grain is bulky, dimension is controlled in 50~200 μ M, the 10~20 of size of grain of photograph of the α in be TC4 about times. 2 experiments method and process milling experiment are on XS5040 vertical milling machine undertake, 13kW of power of electric machinery of this milling machine, 2500r/min of top rotate speed, speed of transverse the biggest feed is workbench 2500mm/min, workbench dimension is 1600mm × 400mm; Workpiece material is titanium alloy Ti40 and TC4. Combine the test result of cutting tool of hard alloy of 3 kinds of different coating, if the watch is shown 3 times, ti (C, n) - Al2O3 coating cutting tool shows better cutting performance, experiment of durability of reason cutting tool chooses Ti (C, n) - Al2O3 is multilayer CVD coating machine places type hard alloy but dislocation razor blade (norms is XOEX120431R-M07, MS2500) , cooperate to use corresponding knife handle (norms is R217.


3-12-3A) undertake sheet ages suitable mill is machined, bit and knife handle see a picture 2. Cutting oil chooses 30# lube; D=25mm of knife handle diameter, the horn before cutting tool installs angle to be 22 ° , hind horn 12 ° , blade is obliquitous radius of circular arc of 11 ° , point of a knife 3.

1mm. Nextpage uses law of trial of cutting rate only factor to undertake experimenting study to cutting tool durability and cutting temperature, fixed axial cuts deep Ap=3mm, radial cuts wide Ae=1mm, fz=0 of every tine feed.

1mm/z, cutting temperature uses clip silk (constantan) the law undertakes half artificial thermocouple measure, combine calibrational curve of temperature of Ti40- constantan thermocouple, get the real numerical value of cutting temperature, analyse condition of different cutting speed to be opposite then cutting tool durability, wear away the influence rule of form and cutting temperature, graph 3 with the graph 4 survey lukewarm scene for Ti40 milling treatment respectively, measure lukewarm place to be collected with temperature get stuck and measure lukewarm primitive signal. To increase material purify rate, improve treatment efficiency, choose rough machining dosage to be: Cutting speed V=30m/min, axial cuts deep Ap=1.

5mm, radial is cut wide anthology for Ae=D=25mm of complete Dao Kuan, fz=0 of every tine feed.

1mm/z, below same parameter at the same time milling machines TC4, with contrast the cutting of two kinds of material machines function. Benefit watchs form of cutting tool point with optical microscope appearance and before, hind of knife face wear away configuration, wear away through cutting tool face of the knife after measuring software wears away average VB and maximum VBmax, finish machining and rough machining serve as cutting tool to grind blunt judge standard with VB and VBmax respectively, the regulation is become VB=0.

2mm and VBmax=0.

Think namely when 6mm cutting tool invalidation. At the same time electron microscope of Hitachi S-3400 of company of electron of Japan of have the aid of scanning (SEM) with X ray can chart appearance (EDS) observation cutting tool wears away configuration, analyse composition of material of cutting tool surface, wear away in order to analyse cutting tool mechanism. Test result and analyse 1 cutting tool to wear away with durability of durability cutting tool it is the main index that measures material cutting processability, to cutting tool wear process undertakes dogging in the experiment, get V=30m/min, 60m/min, 80m/min, 100m/min 4 is planted is in the cutting tool wear curve below cutting speed condition is shown 5 times like the graph. Can see, on one hand, cutting tool durability rise and drop of speed significantly as cutting, on the other hand, after knife face wears away equably achieve about 0.

Generation of the cutting tool when 14mm is fierce wear away, it is even wear away in initial stage level is in generation to flake with respect to advanced knife face or cutting blade or small collapse blade, produce the damaged of different level inside short time then. In cutting speed taller condition falls to produce serious groove even, the felt of cutting tool material is torn off caused large area to flake, temperature of the cutting in cutting treatment process is high at the same time, bit whole is aglow, because high temperature evaporates and cutting oil produces many oily mist. Because cutting tool damaged is serious, cutting process already turned into the attrition of pure cutting tool and workpiece squashs, cutting process undertakes hard. Arrived for V=100m/min condition make known to lower levels in cutting speed highest the material purify rate that is 375mm3/min, but the requirement that inferior durability still cannot satisfy material cutting to machine far apparently. Case of severe cutting tool damaged mirrorred the cutting processability with Ti40 titanium poorer alloy. Nextpage experiment discovers, the durability of the cutting tool below condition of 4 kinds of different speed and condition of complete Dao Kuan is inferior, invalidation form is given priority to with damaged, see a table 4. Below the low speed condition of V=30m/min, face of the knife after cutting tool wears away relatively even, but in the distance point of a knife is 3mm, cut dark line position namely, wear away serious, see a picture 6 (A) ; As the addition of speed, knife durability drops quickly, do not exceed 25min commonly, after speed achieves 100m/min, damaged phenomenon is more serious, see a picture 6 (B) , right now durability relatively V=30m/min dropped 55% . Complete Dao Kuanxi cuts a condition to fall, serious groove wears away make cutting tool durability even under 5min, if pursue,7 are shown. Clip silk is used in experiment of 2 milling temperature the milling temperature that the law issues to different speed undertook half artificial thermocouple measure, temperature of the milling when discovering in cutting speed is 30m/min already achieved nearly 360 ℃ , the temperature when rate increases 100m/min rises to 560 ℃ , if pursue,8 are shown. Study according to Geng Guocheng [13] is knowable, titanium alloy TC4 falls in same treatment condition, when speed is 100m/min, cutting temperature is 150~200 ℃ about, far the cutting temperature under Ti40 alloy. Because cutting tool and workpiece coefficient of friction are big,high cutting temperature is on one hand, the friction work that when cutting bits to shed face of the knife before classics, does is great, make temperature of its contact surface higher; On the other hand, material hot conductivity is low, the heat in metal cutting that cutting process produces is accumulative at cutting blade around send out not easily, cause temperature to rise quickly around cutting area. And, workpiece flexibility model measures small conference to bring about already machined exterior spring back, make face of the knife after cutting tool and workpiece attrition more serious. In the meantime, ti40 is alloy of titanium of a kind of high temperature, high temperature capability is good, compare common titanium alloy to be able to retain higher strength more below high temperature condition, and right now, cutting tool material can produce bate accordingly, cutting process change becomes the extruding process of cutting blade and workpiece, cause cutting tool material to be able to fall to be come off easily in the action of attrition force cutting tool matrix, see a picture 9. Nextpage3 cutting tool wears away the vibration that treatment of mechanism analysis milling produces as interrupted cutting and concussion make cutting tool surface is handed in the stress that change to action and the periodic stroke that cut bits, attrition warms up and cut refrigeration for nothing, in cutting oily cooling action falls, cutting tool surface changes quickly to heat up and become cold, stress of the thermal stress that is relapsed thereby, attrition. The position of dark to be being cut on cutting blade line, persistent stress concentration produces in machining a process, cutting blade produces attrition score with workpiece surface ceaselessly, make wear away here most serious, groove tatty generation accelerated cutting tool to wear away speed, reduced durability greatly. Hardness of hard alloy razor blade is tall at the same time, brittleness is big, textural may be inhomogenous, machining sclerosis and hand in the stress action that change to fall, place of meeting interiorly crystal boundary produces micro-crack, progressively and patulous, see a picture 10. The formation of crackle makes cutting tool is in local form stress concentration, cause cutting tool to material flakes and die then blade, make finally cutting tool invalidation. The crackle that thermal stress produces is one of reasons of cutting tool invalidation. Besides, workpiece material is in the felt of cutting tool surface also is to cause cutting tool to wear away acuteness main factor, graph content of felt of face of the 11 knives after be cutting tool and graph of scanning of felt content EDS. By the graph 11 (A) see not hard, titanium alloy data exists in face of the knife after cutting tool serious sticking knife phenomenon. Ti40 of alloy of the titanium in the experiment besides contain Ti besides, still contain the main element such as V and Cr. Graph 11 (B) for the graph 11 (A) in the EDS of felt content can chart analyses a result. Felt is in can the result that chart analyses makes clear, cutting tool surface contains many Ti, V and Cr element, and by the watch 5 visible, content of scanning area element and Ti40 name composition (Ti-25V-15Cr) special close, face of knife of around of demonstrative cutting tool all felt has workpiece stuff. In cutting process, felt is material happening after plasticity is out of shape and the phenomenon of alleged cold welding of generation, basically happen in enough great pressure and enough below fast temperature action. As a result of titanium alloy taller chemistry is active, inside certain high temperature limits, workpiece material and cutting tool material happen stronger kiss and action, meeting felt reachs the grain in cutting tool cut bits and work in the center, be cut then bits and workpiece material are taken away, cause felt to wear away. As cutting speed rise, cutting tool and workpiece move relatively aggravate, cutting temperature is elevatory, the binder in cutting tool material drops in the bonding strength below high temperature, cutting tool material produces bate accordingly, the particle such as carbonization tungsten departs easily a cutting tool matrix, cause more serious felt, make cutting tool durability is reduced further. For the processability of comparative and different material, mix in same cutting parameter in research undertook to titanium alloy TC4 complete Dao Kuan is machined below cooling condition. The result makes clear, cutting tool undertakes 30min in cutting hind hind knife face wears away to be only 0.

1mm, cutting tool still is in initial stage to wear away level, and cutting process temperature is inferior, cutting tool wears away even, all happen without damaged phenomenon, if the graph is shown 12 times, the cutting processability that shows Ti40 is far poor at TC4. The article collects conclusion to be opposite with cutting tool of coating hard alloy new-style and flame retardant Ti40 of β titanium alloy undertook milling processability studies, use cutting tool to wear away measure system and scanning report lens to reach can the method such as chart analysis, undertake contrasting study with titanium alloy TC4 at the same time, form of invalidation of analytic cutting tool and wear away configuration, mechanism. Research discovery is flame retardant processability of cutting of titanium alloy Ti40 is far poor at titanium alloy TC4, durability of cutting tool of coating hard alloy is low, form of main be no longer in force is damaged, flake at the same time and collapse blade phenomenon is outstanding. In cutting tool wear process, wear away belt be not even development, and groove wears away serious, enter generally after initial stage wears away acuteness wear away level, be in only cutting speed is shown below very low requirement wear away normally, raise cutting speed and requirement of cutting of complete Dao Kuan cutting tool of can remarkable aggravate wears away, lower cutting tool life; On the other hand, the temperature in process of treatment of Ti40 material milling is high, it is groovy α + the 3~4 below condition of coequal treatment of TC4 of β titanium alloy times. Temperature concussion makes cutting tool in-house stress is too great and generation crackle, cause cutting tool material to fall off then. The place on the knot is narrated, can discover, below existing experiment condition, taller cutting speed and complete Dao Kuan do not suit to machine titanium alloy Ti40, appropriate cutting speed is 60m/min the following. Treatment efficiency is low with cutting tool damaged serious the main problem that is existence of Ti40 milling treatment. In view of this, be necessary to be in in follow-up research already had research over gain base, from optimize parameter of cutting tool geometry and improvement cooling condition proceed with, optimize cutting dosage, in order to improve manufacturing efficiency. CNC Milling CNC Machining