The method of polish of shallow low temperature of optical material

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The hard fragile data that place of 1 introductive and modern science and technology uses, if sheet tastes material of silicon, function, pottery and porcelain, gem and optical glass to wait, undertake superprecision to these material, obtain He Chaoguang of very good face form precision slippery surface ministry is very difficult. Latter-day the diamond cutting technology with just tend mature is helpless also to this. The treatment problem that solves these material still is the traditional technique that improves ceaselessly, or be add new technology measure again on traditional technique, because scientific progress is right the demand that machines precision and exterior quality is higher and higher, traditional technique had been dealt with very hard. Machine precision to hard fragile data executes superprecision and rising ceaselessly, improve treatment efficiency, it is we try evasive problem, in using different physical process, different chemical process at machining craft for this people, be like ion bundle treatment is a kind of first-rate treatment method, ionic bundle polishing can reach very high level, but of this technology the research that begins the job to need to a lot of capital are thrown and make development works. The article spends consideration question from additional quoin, from the change treatment environment temperature considers an issue. In the development process of diamond superprecision technology, had researched technology of cutting of diamond low temperature with respect to somebody 5, appeared a few new phenomena, fall in microtherm condition for example, diamond but cutting black metal acquires very good surface quality. So, below microtherm condition, undertake polishing to optical material, can produce those new phenomena again, whether can improve treatment precision and treatment efficiency, we are discussed through what the experiment made certain pitch, summarize below. The notional temperature of polish of 2 low temperature is a physical quantity, all sorts of material on the world are shown in the environment that its are in have constant temperature, the discretion of temperature and physical heat are concerned, hot essence is a kind of expression of the atomic and ceaseless vibration in material, temperature is high state its composition atom is very confused, the atom below microtherm condition is OK well-ordered. High temperature can achieve very high rate, atomic disorder is increased ceaselessly, material becomes a liquid by solid, become gas by the liquid again. And microtherm is finite, - 273.

15 ℃ are absolutely temperature zero, state consequently for 0K normal temperature is controlled in 300K commonly, 0 ℃ are 273K. Microtherm is to show 0 ℃ are the following, namely the temperature limits under 273K. Nature has microtherm material and microtherm environment, refrigeration of microtherm VIP labour is acquired in the lab, do microtherm polish to us for, the optical material that makes be machined namely and treatment space are achieved and maintain requires low temperature. All sorts of material are in microtherm environment, those who follow refrigerant deepness is different, material behaved different character, in the research of microtherm application project, somebody environmental temperature low to 123K(-150 ℃ ) call general cold area, go to 123K OK(-273.

℃ ) call deep cold division. Our job is to be in 0 times - 30 ~ - undertake in the environment of 50 ℃ , we should study the fabricating characteristics that optical material issues in microtherm condition, optical polish undertakes below microtherm condition, the problem such as the microtherm environment that should solve the polishing model below microtherm condition, workpiece and process, because refrigerant deepness is more shallow, so we call method of this kind of polish polish of shallow low temperature. 3 polish model and polishing wave 3.

Layer of 1 polish model uses microtherm technology to be able to be used in cutting treatment dry cut a way, cooling fluid is not added when cutting namely. Microtherm technology is used in grinding treatment, the most difficult issue is possible fluid of grinding of low temperature of nothing is more... than, because find a kind of grinding liquid that still has good liquidity below in 0 ℃ ,be by no means easy thing. Fluid of general water-solubility grinding is in 5 ℃ , fluid of blame water-solubility grinding is in - the fluidity when 5 ℃ is very poor. We search a kind to be able to keep away from in effort all the time the method of this kind of worry, hengchuanheyan is studying Japanese scholar in the process of grinding technology, the purpose that machines an environment from improvement sets out, offerred the think of a way to cold air of treatment region spurt, big dark whole did test of freezing emery wheel, these are very creative have very much to us inspire. In optical cold working. The carrier that water regards abrasive as also is refrigerant at the same time, no matter be to come loose,an abrasive or solid are worn leave in abrasive polish not boiled water, still want to think way on water so. Traditional optical polish is used commonly cast-iron dish, the surface pays polishing model, the most commonly used in dressing is bitumen, still have stannum, flannelette and get together ammoniac fat, teach the polish with bitumen dish can make an accurate exterior geometry appearance, for example planar, sunken spherical with protruding spherical, be in next its apparently sculpture gives freely groove, form make many small diamonds, groove can contain abrasive and polishing juice, make many small diamonds and workpiece connect to touch and make slip motion relatively, below the action of abrasive, the cutting that forms pair of workpiece moves, produce the polishing result that we ask. If polishing falls in microtherm, ambient conditions of indispensible creation low temperature, include a bitumen dish or stannum dish the low temperature that refrigeration asks to place, undertake microtherm issues polishing next, but the bitumen below microtherm and stannum can have those new characteristics, it is the issue that needs us to solve, we do not have such making. What we go is a road: Freeze polishing liquid cooling in cast CD to go up, form the polishing model layer of an ice, such we can get the polishing model layer with a same exact figure, for example a planar polishing model layer. Mix namely cast-iron dish of bitumen model layer the polishing model of just the same, itself contains abrasive similar firm is worn abrasive millstones, when connecting to touch and do opposite exercise with workpiece when layer glacial a model, with respect to generation cutting moves, produce polishing result. In the meantime, can adjust the hardness of layer glacial a model according to machining the diverse mix of material to rectify refrigerant deepness. 3.

The abrasive that 2 polish wave uses in optical polish is very much, for example Al2O3, CeO2, Gr2O3 and SiO2 are waited a moment, the appearance of particle of the abrasive size that polishing uses, abrasive affects polishing result directly, grind the appearance of bead, different abrasive is different, abrasive granuality is fine still good, had better choose accept rice (Nm) class abrasive, basis by polishing material different, what ask to exterior quality is different, choose the abrasive of different sort, distinct size appropriately. Abrasive adds the suspension juice that water forms, it is the polishing wave that uses in our polish job. Fluid of this kind of in suspension may show alkalescent or weak acidity, PH value can be adjusted at any time, basically be to make unapt in polishing process corrode workpiece. Abrasive of the requirement in suspension fluid has good dispersive sex, cannot written guarantee round, want to add dispersive agent in suspension fluid so. Agreeing of abrasive granuality equably is more inaccessible, basically be limitative big grain, avoid the appearance by cut. Fluid of refrigerant abrasive in suspension, become microtherm solid to need a refrigerant time course by the liquid, this time course should shorten as far as possible, in case the deposit place of the abrasive in refrigerant process is caused refrigerant the abrasive of ground floor of layer of glacial polish model after very concentration, and superstratum abrasive is opposite less. Wear bead to be more than what μ M measures level, uniform motion is made in dispersive medium, press Stokes law, : of its settling speed? of school washing with watercolors is grain radius, g attachs most importance to force acceleration, μ is dispersive medium viscosity, δ , δ is grain and dispersive medium density respectively. When grain very hour, settling speed is very slow, for example grain radius is for 1 μ M in different dispersive medium, its settling speed is 3, S of / of 5 μ M. In refrigerant process, because time is very short, will not produce deposit phenomenon. To accept rice (Nm) class abrasive, theoretic belong to colloid grain, always be suspension is in liquid medium actually, without deposit action. So, we can make grain the layer of model of microtherm solid polish with even, dispersive good sex. The collosol that develops in recent years -- gel (Sol -- the abrasive that Gel) technology gave us to offer place to need, this experiment uses SiO2 to make grind shake wave of the polish that make. Test of test of polish of 4 low temperature has inside normal temperature lab, temperature of layer of Pan Bing model is in polishing - 30 ~ - between 50 ℃ , workpiece does microtherm pretreatment, treatment area adds a shade and connect CO2 to enrage or put temperature of dry ice environment to be in - 20 ℃ left and right sides, if machine an area not to do temperature to control, have microtherm polish test in the Yi Ke below normal temperature, what the layer glacial a model that is polishing only uses up is very fast. The optical material of polishing experiment has glass of single crystal silicon chip, glass-ceramics, Zerodtur, K9 to reach layer of nickel of metallic radical plating to wait. 4.

After prior operation of silicon chip of 1 single crystal, by the exterior surface roughness of the silicon chip of polishing Ra measures level in 10nm, for example Ra = 14.

87nm is shown 1 times like the graph, undertake microtherm polish next, 250-300rpm of main shaft rotate speed, polishing is 70 minutes about, the polishing effect of a few workpiece is Ra=3 respectively.

03nm, ra=2.

98nm, ra=1.

29nm, if pursue,2 are shown. Nextpage4.

2 glass-ceramics, zerodur, k9; glass Zerodur is German glass-ceramics brand, k9 is brand of Chinese optical glass, be equivalent to the BK7 of foreign brand, it is a kind of commonly used optical glass, homebred glass-ceramics also got applied extensively in recent years, these are to have representative commonly used optical glass. Microtherm polish experiment makes clear, to these basic optics material trembles, the effect of microtherm polish is very good, ra can break exterior surface roughness Nm measures level, enter A to measure level, the ZerodurRa=0 in exemple if.

4nm, if pursue,3 are shown. By the workpiece of polishing it is a diameter is 30mm circle base piece, flatness is λ / 20. 4.

3 metals base speculum of plating nickel layer often chooses the metal with light quality of a material, the surface makes illuminator use after silver-gilt polish, nickel layer polish is optical common technology, we did microtherm polish test. After pretreatment of work semifinished product, ra=2.

11nm, do microtherm polish next, we are in respectively T = 40, 100, 150, 210, 390, 500 the test was done to exterior surface roughness when mixing 560 minutes, eventuate Ra = 1.

73, 1.

34, 1.

12, 0.

88, 0.

73, 0.

68 with 0.

62nm, the lengthen Ra that can see exterior surface roughness lets polishing time is in drop, if the graph is shown 4 times,be final measured value. (Because this experiment checks instrument malfunction to did not continue at that time) the actor of 5 comparative experiments for polish of evaluation low temperature bad, we made same work material, with same size abrasive, current and commonly used bitumen dish the comparative experiment of polishing and microtherm polish. Single crystal silicon chip: The surface roughness Ra=12 of semifinished product.

Surface of the workpiece after 60rpm of rotate speed of 04nm main shaft passes 16 hours of polish achieves Ra=3.

16nm, if pursue,5 are shown. Glass-ceramics: Same, through longer polish, also can approach the level of exterior surface roughness of microtherm polish. Layer of nickel of metallic radical plating: The experiment makes clear bitumen dish the purify rate of the polish of low temperature of purify rate prep above of groovy craft, surface roughness can reach same amount level. Comparative test result analyses: Look from experimental result, shallow low temperature put modular layer polish on the ice to get better polishing result, polishing efficiency also compares tall experimental result, we think: (When polish of 1) shallow low temperature, polishing abrasive is worn to be in layer glacial a model by solid, be " solid " , can increase the rotate speed of workpiece main shaft appropriately so, rise for example minutely hundreds of turn, and rotate speed of machine of common and traditional polish is restricted, otherwise the excessive outside abrasive, instead the result is bad. (Layer of 2) ice model and workpiece connect to touch and make opposite motion produce cutting effect, constant purify workpiece data. Put modular layer and heat build-up of workpiece contact attrition on the ice on the other hand, layer glacial a model is ceaseless and fused, film of a water is formed between ice and workpiece. Mix at this moment groovy polish is similar, abrasive undertakes purify to material with fluctuant means, in the meantime, what contain in not fused ice grind bead to return move having firm the cutting action of abrasive, until grind bead to fall off. So, the cutting action of microtherm polish is more than common bitumen dish the purify action of polishing, so, effect of polish of layer glacial a model and purify rate are better. (Polish of 3) shallow low temperature, the polishing model that we use dish temperature is in - 30 ~ - 50 ℃ . In polishing process, polishing model dish, workpiece creates vacuum of that small low temperature artificially in us inside, but on the interface of workpiece and iced layer, some kind of forms as a result of heat build-up high temperature, reductive the liquid condition of polishing wave, polishing fluid undertakes to the hydrolysis action as usual of workpiece, hydrolysis action is helpful for the purify of material, mix so groovy polish is same, microtherm polish is mechanical and chemical polish likewise. Rate of Nextpage6 material purify determines to optical polish craft, measuring the material purify that gives a condition to fall to lead is very not easy thing, because optical polish is after a paragraph of process, exterior purify amount is very small, appliance of instrument of requirement of this certainly will has very high resolution and very strict measure repeatability, this groovy to using method is very difficult undoubtedly. Difficult wave used Knoop in their polishing experiment (Knoop) sclerometer will measure purify rate, hader and Weis put forward a kind to be in appearance on cut a micron (the method of the flowing groove of level of μ M) volume 14, be in namely every time after polishing, the change that goes measuring groove depth with contourgraph is calculated then give material to be led by the purify of polishing. We the condition according to us, purify of microtherm polish material leads determining is in MVK, E microscopical undertake on sclerometer. Microscopical sclerometer basically is to be used those who test all sorts of material is microscopical hardness (its measure Hv) the head is pyramid of pyramid type all directions, silver-colored horn is 136 ℃ on the photograph, when pressing material with different bear, surface of the material that be measured forms to have the opening of the form of all directions pyramid of certain deepness. So, we are in the appearance of polishing go up to be pressed first on the impress of aperture of form of all directions pyramid, every time after polishing, measure the change of length of taper hole diagonal, with respect to the change that can get taper hole deepness, final conversion gives the purify of polishing material to lead. Set diagonal length to be Di, the side of taper hole of all directions form is long for Ai, criterion every time is the taper hole height after polishing: ?  abundant  puts in order see I of Mo of Shan of Jie of Zhuang of Wen Zhui Liao can be calculated accordingly a Hi, can seek its change, if the graph is shown 6 times, final computation gives the purify of material to lead. We are in a workpiece dish different position chooses 3 model, every appearance choose 3 different positions to do pyramid aperture impress again (do together among them everywhere) , every time polishing hind is metric Di, in all 10 burn statistical average. Here has two problems, 1.

Microscopical the impress of sclerometer is very shallow, but of material be out of shape make there is apophysis to appear in brim place after impress, so, begin in first time metric before, must apophysis take out. 2.

MVK, E microscopical the multiple of observation microscope enlarge of sclerometer is 400 × , value of displacement scale division is 1 μ M, this brings difficulty and resolution to observation not tall. So, our every time polishing operation is sure to make the metabolic quantity of Di is more than 1 μ M, inspect value error in order to decrease, in the meantime, return extrude the impress of different deepness makes calibration with, reduce accidental error as far as possible, handsome test result is basic and accurate. Experimental data: Our experiment is to part to be mixed to glass-ceramics layer of nickel of metallic radical plating undertakes, express the data of 1 a group of tests that is glass-ceramics. Change after abrasive, continue to do a test, the purify height of material of another kind of abrasive is 1.

52nm/min purify rate is 14.

54 × 10-3mm3/min. Polish of low temperature of silver-gilt layer workpiece measures a group of metal radical so that the purify height of material is 0.

2nm/min is lower than glass-ceramics. For contrast, the test of polish of layer of groovy bitumen model that we did silver-gilt layer and glass-ceramics respectively again, the result is bitumen model dish polishing metal base rate of the purify height of plating nickel layer, purify compares polish of low temperature of layer glacial a model tall. On the other hand, bitumen dish the purify height of polishing glass-ceramics, purify is led not as good as microtherm polish. This one result is very interesting. Test result we think glass-ceramics of polish of layer of microtherm ice model is mixed layer of nickel of metallic radical plating, its purify rate is very low, can cast favorable balance of trade consequently slick surface. The purify of optical material polish is strung together, below the rotate speed, condition that places horn and pressure to change originally, still be a variable is not invariable, for example, should change by a kind of abrasive when be another kind of abrasive, or abrasive by thick attenuate when, the purify rate that just measured in the begining and the purify rate that measure later are different. 7 conclusion add temperature effect in groovy and optical technology, use polishing wave to add water-cooling to freeze ice, form " solid " polishing model layer, the bitumen that replaces a tradition dish or stannum dish wait for polishing model layer, this is a kind of new trial. From the point of the polishing effect of to a few kinds commonly used optical material: (The test of polish of shallow low temperature of layer of glacial polish model that we have 1) , show method of this kind of polish is had medicinal powder bead abrasive and solid are worn two kinds of effects of abrasive polish, can improve work efficiency, control face form easily and got Ra is in what A measures level to exceed slick surface. (2) method of this kind of polish because microtherm is refrigerant deepness is very shallow, layer glacial a model is made simple, do not add equipment in groovy craft, condition of proper creation low temperature can come true, the in some way has economic value. (Physics of 3) low temperature is in recent years very active research domain, the physical award 1998 is the research achievement of behavior of the quanta below microtherm condition. Below microtherm condition, it is especially inside the area of deep cold temperature near OK, can produce a lot of new phenomena, be worth to study exploration deep, to engineering technology worker, below the condition of deep cold division, the optical data that is processed can have those new property, treatment to be able to quality of those new phenomena, surface has those new effects, it is the new issue that deserves thorough research conditionally. This project funds a project to apply optical state key laboratory. CNC Milling