Carbon fiber composite material makes a manual bore processing technique

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Carbon fiber composite material (CFRP) it is the composite material that is matrix to enhance material, colophony with carbon fiber, because its are had can as better as taller than stiffness, fatigue resistance than intensity, be able to bear or endure lukewarm performance is good wait for an advantage, the application in aerospace domain is increasingly wide, rapid already development makes one of material of construction of 4 big aerospace after afterwards aluminium, steel, titanium. Bore is carbon fiber composite material is made a very important working procedure in assembling treatment craft. Because carbon fiber composite material has hardness,big, thermal conductivity needs tall, strength, the intensity between anisotropy, layer is low and characteristic, belong to difficult treatment material. Undertake on carbon fiber composite material aperture adds man-hour, appear extremely easily difference of quality of surface of material burn, aperture, statified, tear off wait for blemish, bring about carbon fiber composite material to make thereby discard as useless. Current, be opposite domestic and internationally the bore technology on carbon fiber composite material had begun a lot of experimental research, also reached a few good experience and conclusion, but the technique that these experience and conclusion apply to use machinery equipment to undertake bore only normally. To creating a company character, advanced automation equipment is used to undertake bore is operated on carbon fiber composite material, undoubted meeting brings huge cost investment, the manual bore means that because this more business still chose cost,experience of inferior, skill matures relatively. Because manual bore is in,the respect such as cutting tool stability, feed rate stability controls a gender poorer, because this is manual,Kong Shi is made produce all sorts of aperture more easily to machine blemish on carbon fiber composite material. This already became use composite material to make a difficulty that has constructional by traditional technique and crucial point. The function of composite material of common problem carbon fiber of bore of handiwork of carbon fiber composite material is fragile, intensity is high, carbon fiber hardness is tall, heat conduction ability is poor (the 1/5~1/10 that coefficient of thermal conductivity is austenite stainless steel only) , anisotropy, the intensity between the layer is low, easy below the action of cutting force generation is statified when cutting, tear off wait for blemish, when manual bore especially serious, treatment quality assures hard. Aperture is made basically be put in the following problem on carbon fiber composite material. (1) carbon fiber hardness is tall, the hardness that its hardness is as high as HRC53~65 to be equivalent to high-speed steel (HRC62~65) , because of this bore process medium broach wears away very fast [1] . (2) thermal conductance is small, concentration of quantity of heat of ministry of bore the current political situation is bigger, produce material burn limitation easily. (3) when bore cut bits to be dust shape, pollute an environment, endanger human body health. In the meantime, carbon fiber cuts the conductivity of bits to make electric equipment and electrified wire netting short-circuit easily. (4) the intensity between the layer is low, easy in bore process generation is statified blemish. (5) belong to anisotropy material, the stress concentration that bore is in is bigger, cause extremely easily tear off, the blemish such as Mao Bian. Problem analysis and solution 1 broach wears away the issue fits as a result of the hardness of the hardness of carbon fiber material and high-speed steel, because of the cutting tool of material of this unfavorable use high-speed steel, can choose material of tall hardness cutting tool (include hard alloy, pottery and porcelain, diamond to wait) undertake machining. Contrast explains: Use auger fast the handgun that is 6000r/min is gotten, the handiwork on the carbon fiber composite material that is 7mm in ply is gotten make φ 4.

When the aperture of 85mm, high-speed steel broach is being gotten make 3~4 phenomenon of difficulty of aperture hind occurrence feed, hard alloy broach can be gotten make 50~70 aperture, contain diamond film (PCD film) hard alloy broach can be gotten make 100~120 aperture. Because cutting tool is sharp,problem of 2 material burn is on one hand degree insufficient, the feed when causing manual bore is slow, lengthened auger cut the attrition time between time and cutting tool and material, produced more quantity of heat thereby, make the temperature of buy of material bureau place and cutting tool rises quickly, cause material burn. Because this should choose sharper cutting tool to undertake bore, with shortening attrition time reduces quantity of heat. Because fried dough twist broach is getting the existence of pointed blade is in a horizontal stroke, make the cutting circumstance of here very abominable, actually horizontal blade does not produce cutting effect, just boil to coil and smash fiber, the main source that is axial force not only [2] , also be the caloric in bore process basically produces position at the same time. If choose,get accordingly model twist drill head undertakes bore, reduce the horizontal blade size of twist drill head appropriately, it is to increase cutting tool sharp degree, improve the good method of bore quality. A kind of when company of American HP cutting tool produces straight blade gets bore with a reamer compound auger (also call dagger to get) , as a result of its helix angle is 90 ° , exist without horizontal blade in the place that get a tip, cutting tool and material contact area are small, because this bore process is medium the quantity of heat that produces is little, can avoid material burn appearance effectively. But this kind of cutting tool discharges bits chamfer to be straight chamfer as a result of its, cannot effective eduction metal cuts bits, because this applies to the bore on interlining of pure composite material only, do not agree with composite material and metallic stuff interlining. Because itself of carbon fiber material is hot conductibility is poor on the other hand, the quantity of heat that produces in bore process cannot send out in time and create material of local temperature ascendant burn, because this is OK,cooling fluid is joined in bore process, make the quantity of heat of the generation in bore process is taken away in time by cooling fluid, avoid generation to local quantity of heat is centered and create burn appearance thereby. 3 dust problem is aimed at the issue that makes Kong Hui produce dust on carbon fiber composite material, can use cooling fluid to take away the dust of the generation when bore in bore process likewise, make dust does not distribute in air, avoid to produce a harm to environment and human body thereby. Additional, still can use robot drill, make handlers is far from the environment that has dust pollution on one hand; On the other hand, still can undertake monitoring to bore process, ensure further bore quality. The one-time devoted cost as a result of use robot bore and follow-up maintenance cost are extremely high, use limitation is bigger, and treatment efficiency does not see higher than conventional technology, because this seldom has a company,the choice uses robot drill. To manual bore, cooling fluid is added in bore process very no-go, and after carbon fiber dust and cooling fluid mix, disadvantageous Yu Qing manages, because this also can use the bore tool that contains aspiration accessory, join with cleaner of high negative pressure when bore, a large number of air that produce through cleaner of high negative pressure flow quickly, the dust that produces bore place is inspiratory in cleaner. Additional, avoid dust to wave in air medicinal powder. 4 statified what the problem arises in bore process is statified it is to show effect of strength of the axial in bore process causes hole wall all round the detached phenomenon between material happening layer. Its evaluate index to be statified factor Fd, the definition is as follows: Fd =Dm/Do, among them, dm destroys section between the layer for aperture the biggest diameter; Do is by the nominal diameter of treatment aperture. Statified the relation that there are linear or section linear between factor Fd and Fz of average axial force, fz is bigger, fd is bigger, statified more serious also. And the size of axial force suffers the feed speed in bore process, cutting tool to get again fast, material of ply of parameter of geometry of blade of broach diameter, cutting, material, CFRP is qualitative the influence that waits for a variety of elements. Pledge in material of ply of parameter of geometry of blade of broach diameter, cutting, material, CFRP particular case falls, feed speed and cutting tool are gotten fast the main factor that will be volume of influence axial power. Graph 1 it is φ 4mm hard alloy broach getting is cut 3.

The relation curve of force of the axial when 5mm thick composite material and rotate speed N and feed I [3] . From the graph 1 can see, axial force is reduced as the accretion of rotate speed, because higher cutting rate produces more heat in metal cutting,this is, make the intensity of workpiece material and hardness drop, axial force drops somewhat; Axial force increases as the addition of feed, because increase as feed,this is, cut ply increases, can make axial force increases so. The effect that can see feed at the same time is far the influence that is more than rotate speed, so feed is a crucial factor that commands axial force. Nextpage is when manual bore, feed speed is controlled completely by worker handiwork, because this is very flabby,decide, this also is the main factor that causes quality of manual bore aperture to be not stabilized. Accordingly, the feed speed when controlling manual bore became the key in success or failure of the bore on carbon fiber composite material. The feed rate that controls manual bore can be connected in general one increases on pneumatic drill adjustable system of type hydraulic pressure, will offset through adjusting the pressure of hydraulic pressure manual thrust of the worker, control the feed rate of cutting tool thereby. A kind of high speed that company of American Hishear tool produces is gotten (Lap Drill, graph 2) the tool that uses level control apparatus to control rate of cutting tool feed namely. In addition, of cutting tool get fast the size that also affecting axial force. To manual bore, when the tool get fast particularly tall when, hand will assure the stability of the tool in bore process and cutting tool very hard, bore quality can give the trend that glides now instead, because this controls cutting tool,get fast very important also. To manual bore, of cutting tool auger fast depend on completely pneumatic tool offers auger fast, and the effect that the rotate speed that pneumatic tool can offer gets the respect such as precision of wind pressure, tool again. Because this improves the pneumatic work with improve wind pressure stability and choice quality wind road condition, better,provide quality of manual to rising also bore to be helped somewhat. The pneumatic tool that uses 1500r/min, 3300r/min and 6000r/min by hand through be on the carbon fiber composite material with thick 7mm is gotten make φ 4.

The aperture of 85mm undertakes contrasting experimenting making clear, when the tool of use 6000r/min can more effective decrease statified the occurrence of blemish. 5 tear off and wool side issue is torn off and wool edge blemish is the commonnest breakdown in treatment of carbon fiber composite material, and the export a side that produces in aperture more. Because plunge knife,tearing off the generation with Mao Bian is sharp degree insufficient, composite material fiber was not cut off completely to cause. Because this raises the sharp sex of cutting blade,solve this kind of blemish effectively. In manual bore, use plated film of diamond of gas phase deposit commonly (CVD) or get together brilliant diamond plated film (PCD) hard alloy cutting tool undertakes getting cutting machining. Diamond cutting tool has extremely sharp cutting blade, good cutting can undertake below the state of affairs with very little feed. In the meantime, sharp cutting blade also makes get the decrescent that cut force, the coefficient of friction that adds diamond is small, can reduce cutting force further, reduce axial force thereby, prevent the happening of all sorts of blemish. Because home is at present rare,technology of coating of enterprise control diamond is mixed own corresponding facility, because this uses azotic aluminium mostly in practice,the hard alloy cutting tool of titanium coating undertakes Kong Jia is versed in. Practice is comparative, of cutting tool of coating of azotic aluminous titanium sharp degree a bit poorer than diamond coating, and service life is briefer also. Because this is,ensure aperture quality, need to stipulate according to interlining ply bore amount fills up glue block in the exit of aperture, ensure get impartiality of fiber of the composite material in cutting a course to fall, this also is to decrease tear off the efficient way with Mao Bian. The other method that aperture quality improves when manual bore and photograph of mechanical and automatic bore are compared, manual bore has a lot of not certain factors and factitious effect, because this carries high manual drill,reduce these inaccuracy to decide the effect of element and factitious element, achieve to get cut course smoothly thereby. To score the hole of high quality, adopting reasonable technology measure is necessary. The method that the 1 technique that uses the drill that divide a pace divides pace bore is namely when bore and do not make Kong Zuan eventually aperture, the means that reaming or opening of bore with a reamer use after bore however machines aperture eventually the method of aperture. The method that uses the drill that divide a pace can reduce the amount of penetration of a cutting tool in bore process, reduce axial force thereby, reduce the odds that blemish produces. Penetration of a cutting tool measures decrease to still can reduce cutting tool wear away, improve cutting tool service life. And opening of bore with a reamer is used after bore, can reduce the surface roughness of aperture surface and the circularity that increase opening effectively. 2 use perpendicular implement or in getting course of bore of pattern plate handiwork, if material interlining ply is thicker when, the stability of manual bore is reduced further, the generation that increases aperture to machine blemish greatly. Accordingly, in interlining thicker circumstance falls, manual bore should be used perpendicular implement or with jig board cooperates bore, in order to have the effect to stable cutting tool, increase the stability in bore process thereby. When the bore way with 3 right choices should have carbon fiber composite material to have metallic stuff again already in bore interlining, choosing right bore way also is the main factor that affects aperture quality. Normally the circumstance falls, when the bore on composite material and metallic stuff interlining, should choose to close material drill from metallic stuff Xiang Fu, cut the hole on bits attaint composite material in order to avoid a metal in bits process. If structural space is restricted, can make hole to metallic spare parts from composite material only, can choose to increase the size of the chamfer that discharge bits of broach so, in order to ensure the ability discharging bits with good cutting tool reduces the odds that the metal cuts bits to injure composite material; Or choose left reamer coming back, the metal the Xiang Dao that cut bits provides exit direction to push, in order to assure the quality of final aperture. Composite material of last word carbon fiber is a kind of burgeoning material, home is gotten to what go up in carbon fiber composite material cut processing technique to consider to still be in start level. The bore technique that the article adopts adversary labour to go up in carbon fiber composite material is preliminary research, reach the following conclusion. (1) sharper cutting tool should choose when manual bore. (2) should choose to get fast the tool with taller, better stability. (3) should choose appropriate technique in order to reduce the instability when manual bore. CNC Milling CNC Machining