模具高速銑削加工技術(shù)外文文獻(xiàn)翻譯@中英文翻譯@外文翻譯

附錄 Mold high speed milling processing technology First， foreword In the modern mold production, along with to models artistic and the function must obtain more and more high, models the internal structure to design more and more complex, the mold contour design day by day is also complex, the free curved surface accounts for the proportion to increase unceasingly, the corresponding mold structure also designs more and more complex. These all set a higher request to the mold processing technology, not only should guarantee the high manufacture precision and the surface quality, moreover must pursue the processing surface artistic. Along with is unceasingly thorough to the high speed processing engineering research, is processing the engine bed, the numerical control system, the cutting tool system, CAD/ especially Correlation technology and so on CAM software develops unceasingly under the impetus, high speed processes the technology more and more many to apply in the mold cavity processing and the manufacture. The numerical control high-speed cutting processing took in the mold manufacture a most important advanced manufacture technology, is the collection is highly effective, high quality, the low consumption in a body advanced manufacture technology. Is opposite in the traditional machining, its cutting speed, entered to the speed had the very big enhancement, moreover cut the mechanism not to be same. The high-speed cutting caused the machining to have the leap, its specific power metal excision rate enhanced 30%40%, the cutting force reduced 30%, the cutting tool working durability enhanced 70%, remained hotly large scale reduces in the work piece cutting, the low step shudder vanished nearly. Along with the cutting speed enhancement, unit time semi-finished materials material removing rate increased, the cutting time reduced, the processing efficiency enhanced, thus reduced the product manufacture cycle, enhanced the product market competitive power. At the same time, the high speed processing small amount entered quickly causes the cutting force to reduce, the scrap high speed discharged reduced the work piece cutting force and the thermal load distorts, enhances the rigidity to be bad and the thin wall components machining possibility. Because cutting force reducing, the rotational speed enhancement causes the cutting system the operating frequency to be far away the engine bed the low step natural frequency, but the work piece surface roughness is most sensitive to the low step frequency, from this reduced the surface roughness. In mold high hard steel stock (HRC45HRC65) in the processing process, uses the high-speed cutting to be possible to substitute for the working procedure which the electrical finishing and rubs truncates polishes, thus has avoided the electrode manufacture and the time-consuming electrical finishing, large scale reduced fitters polishing with to throw the light quantity. Thin wall mold work piece more and more needs which regarding some markets in, the high speed milling also may smoothly complete, moreover in the high speed milling CNC processing center, a mold attire clamps may complete the multiplex step of processing. The high speed processing technology has had the huge influence to the mold processing craft, changed the traditional mold processing to use the annealing - milling processing - heat treatment - to rub truncates or the electric spark machining - manually polishes, polishes and so on the complex long technical process, even might use the high-speed cutting processing substitution original complete working procedure. The high speed processing technology besides may apply in the hard mold cavity direct processing (in particular half precision work and precision work), in EDM aspect and so on electrode processing, fast type manufacture also obtained the widespread application. The mass productions practice indicated that, the application high-speed cutting technology may save in the mold following processing 80% handwork to grind the time approximately, saves the processing cost expense nearly 30%, the mold face work precision may reach 1 m, the cutting tool cutting efficiency may enhance 1 time. Second, high speed milling processing engine bed The high-speed cutting technology is one of machining technology main development directions, it along with foundation technology the and so on CNC technology, microelectronic technology, new material and new structure development but steps a higher stair. Because the mold processes particular as well as high speed processing technology own characteristic, (processed engine bed, numerical control system, cutting tool to the mold high speed processing related technology and the craft system and so on) proposed processed a higher request compared to the traditional mold. 1. High stable engine bed strut part The high-speed cutting engine lathe and so on supports the part to be supposed to have very well moves, the static rigidity, hot rigidity and best damping characteristic. The majority of engine beds all use high grade, the high rigidity and Gao Kangzhang the gray iron took the strut part material, some engine bed companies also increase the high damping characteristic in the foundation polymer concrete, by increases its vibration-proof and the thermo-stability, this not only may guarantee the engine bed precision is stable, also may prevent when cutting the cutting tool inspires trembles. Uses the enclosed lathe bed design, the overall casting lathe bed, the symmetrical lathe bed structure and has the densely covered stiffener and so on also enhances the engine bed stable important measure. Some engine bed companies research and development departments in design process, but also uses the modality analysis and the finite element structure computation and so on, optimized the structure, stably causes the engine bed strut part to be reliable. 2. Engine bed main axle The high speed engine bed main axle performance is the realization high-speed cutting processing important condition. The high-speed cutting engine bed main axle rotational speed scope is 10000100000m/Min, the main axle power is bigger than 15kW. Is not bigger than 0.005mm through the main axle compressed air or axial play between the cooling system control hilt and the main axle. Also requests the main axle to have the fast vertical speed, to assign the performance which the position is fast stops (namely to have extremely high angle addition and subtraction speed), therefore the high speed main axle often uses the liquid static pressure bearing type, the air static pressure bearing type, the thermo-compression nitriding silicon (Si3N4) the ceramic bearing magnetism aerosol bearing type iso-structuralism form. Lubricates uses technology and so on oil gas lubrication, splash lubrication. The main axle cools uses the main axle interior water cooling generally or air cooled. 3. The engine bed actuates the system In order to satisfy the mold high speed processing the need, high speed processes the engine bed the actuation system to be supposed to have the following characteristic: (1) high entering for speed. The research indicated that, regarding the minor diameter cutting tool, enhances the rotational speed and each tooth enters for the quantity is advantageous in reduces the cutting tool attrition. At present commonly used entering for the speed range is 2030m/Min, like uses leads greatly the ball bearing guide screw transmission, enters may reach 60m/ min； Uses the straight line electrical machinery then may enable to achieve 120m/min. (2) high acceleration. Has the good acceleration characteristic to the three dimensional complex curved surface silhouette high speed processing request actuation system, the request provides the driver which the high rapid advance or progress gives (to enter speed approximately 40m/ min, the 3D outline processing speed is 10m/Min), can provide 0.4m/S2 to 10m/The s2 acceleration and reduces the speed. The engine bed manufacturer mostly uses the entire closed loop position servo-control slightly to lead, the great size, the high grade ball bearing guide screw or leads greatly many guide screws. Along with the electrical machinery technology development, the advanced straight line electric motor already was published, and the success applied in the CNC engine bed. The advanced straight line direct motor drive enable the CNC engine bed no longer to have the mass inertia, in advance, question and so on lag and vibration, sped up the servo speed of response, increased the servo-control precision and the engine bed processing precision. 4. Numerical control system The advanced numerical control system is guaranteed the mold complex curved surface high speed processing quality and the efficiency key aspect, the mold high-speed cutting processing to the numerical control system basic request is: (1) high speed numerical control return route (Digital control loop), including: 32 or above 64 bit parallel processors and 1.5Gb hard disk； Extremely short straight line electrical machinery sampling time. (2) speed and acceleration feed-forward control (Feed forward control)； Digital actuation system crawling control (Jerk control). (3) advanced inserts makes up the method (to insert based on the NURBS transect makes up), by obtains the good surface quality, the precise size and the high geometry precision. (4) pretreats (Look-ahead) the function. The request has the large capacity cushion register, may read in advance and inspects many segments (for example the DMG engine bed to be possible to reach 500 segments, the Simens system may reach a 10002000 segment), in order to when is processed the superficial shape (curvature) changes may promptly adopt changes for measure and so on speed by avoids cutting and so on. (5) the error compensatory function, including because the straight line electrical machinery, the main axle and so on gives off heat the hot error which causes to compensate, the quadrantal error compensates, the measurement system error compensates and so on the function. In addition, the mold high-speed cutting processing very is also high to the data transmission speed request. (6) the traditional data connection, like the RS232 serial mouth transmission speed is 19.2kb, but many advanced processings centers have used the ether local area network (Ethernet) to carry on the data transmission, the speed may reach 200kb. 5. Cooling lubrication The high speed processing uses the belt coating the hard alloy tools, in high speed, the high temperature situation does not need the cutting compound, the cutting efficiency to be higher. This is because: The milling main axle high speed revolves, the cutting compound if achieved the cutting area, first must overcome the enormous centrifugal force； Even if it overcame the centrifugal force to enter the cutting area, also was possible as a result of the cutting area high temperature but to evaporate immediately, the cooling effect very small did not even have； At the same time the cutting compound can cause the cutting tool edge of a sword the temperature intense change, is easy to cause the crack the production, therefore must pick the oil used/Gas cooling lubrication dry type cutting way. This way may use the compressed gas rapidly the cutting which the cutting area produces, thus the massive cuttings hotly will carry off, at the same time might forms extremely thin microscopic protective film after the atomization lubricating oil in the cutting tool edge of a sword and the work piece surface, but effectively will lengthen the cutting tool life and enhances the components the surface quality. Third, high-speed cutting processing hilt and cutting tool Because time high-speed cutting processing the centrifugal force and the vibration influence, requests the cutting tool to have the very high geometry precision and the attire clamps the repetition pointing accuracy as well as the very high rigidity and the high speed transient equilibrium security reliability. Because time high-speed cutting processing big characteristic and so on centrifugal force and vibration, the traditional 7:24 taper hilt system is carrying on the high-speed cutting to watch appears the obvious rigidity insufficient, the redundant pointing accuracy is not high, the axial size not steadily grades the flaw, the main axle inflation causes the cutting tool and clamps the organization nature heart the deviation, affects the cutting tool the transient equilibrium ability. At present applies many is the HSK high speed hilt and the overseas nowadays popular fastening -like hilt. the fastening -like hilt has the heating system, the hilt all uses the awl department to contact generally with the main axle end surface also, its rigidity is good, but the cutting tool commutactivity misses, a hilt only can install one kind of connection diameter the cutting tool. Because this kind of heating system quite is expensive, when initial period uses the HSK kind of hilt system then. When enterprises high speed engine bed quantity surpasses above 3, uses the fastening -like hilt quite to be appropriate. The cutting tool is in the high-speed cutting processing one of most active important factors, it is affecting the processing efficiency, the production cost and the product processing precision directly. The cutting tool must withstand load and so on high temperature, high pressure, friction, impact and vibration in the high speed processing process, the high-speed cutting cutting tool should have the good machine capability and the thermostability, namely has the good anti- impact, the wearability and resists heat the weary characteristic. The high-speed cutting processing cutting tool technological development speed is very quick, application many like diamonds (PCD), cubic boron nitride (CBN), ceramic cutting tool, coating hard alloy, (carbon) titanium nitrides hard alloy TIC (N) and so on. In the processing cast iron and in the alloy steel cutting tool, the hard alloy is the most commonly used cutting tool material. Hard alloy tools resistance to wear good, but the solidity ratio cube boron nitride and the ceramics are low. In order to enhance degree of hardness and the superficially attractive fineness, uses the cutting tool coating technology, the coating material for the titanium nitrides (TIN), the aluminium nitride titanium (TIALN) and so on. The coating technology causes the coating by the sole coating development for multilayered, the many kinds of coating material coating, has become one of enhancement high-speed cutting ability essential technical. The diameter in the 1040mm scope, also has the carbon titanium nitrides coating the hard alloy bit to be able to process the Luo river degree of hardness to be smaller than 42 materials, but the titanium nitrides aluminum coating cutting tool can process the Luo river degree of hardness is 42 even higher materials. When high-speed cutting steel products, the cutting tool material should select the hot rigidity and the fatigue strength high P kind of hard alloy, the coating hard alloy, the cubic boron nitride (CBN) and the CBN compound cutting tool material (WBN) and so on. Cuts Truncates the cast iron, should select the fine grain K kind of hard alloy to carry on the rough machining, selects the compound nitrided silicon ceramics or the crystal combination cube boron nitride (PCNB) the compound cutting tool carries on the precision work. When precise processing non-ferrous metal or nonmetallic material, should select crystal combination diamond PCD or the CVD diamond coating cutting tool. When choice cutting parameter, in view of the circular shear blade and a ball milling cutter, should pay attention to the effective diameter the concept. The high speed milling cutting tool should press the balance design manufacture. The cutting tool front angle must be smaller than the conventional cutting tool front angle, the clearance angle is slightly big. The host vice- cutting edge attachment point should the cavetto or the lead angle, increases the vertex angle, prevents the knife point place hot attrition. Should enlarge nearby the knife point the cutting edge length and the cutting tool material volume, enhances the cutting tool rigidity. Is safe in the guarantee and satisfies the processing request under the condition, the cutting tool hangs extends as far as possible short, cutter body central toughness is friends with. The hilt must be sturdier than the cutting tool diameter, connects the handle to assume but actually the pyramidal, by increases its rigidity. As far as possible central the refrigerant hole in the cutting tool and the cutting tool system. A ball end mill must consider effectively cuts the length, the cutting edge must be as far as possible short, two spiral grooves balls end mill usually uses in the thick mill complex curved surface, four spiral grooves balls end mill usually uses in the fine mill complex curved surface. Fouth, mold high speed processing craft and strategy The high speed processing including take removes the remainder as the goal rough machining, the residual rough machining, as well as take gains the high grade processing surface and the slight structure as the goal half precision work, the precision work and the mirror surface processing and so on. 1. Rough machining The mold rough machining essential target is pursues in the unit time material removing rate, and is half precision work preparation work piece geometry outline. In the high speed processing rough machining should adopt the craft plan is the high cutting speed, Gao Jin giving rate and the small cutting specifications combination. The contour processing way is one processing way which the multitudinous CAM software uses generally. Using is spiral contour and so on the Z axis contour two ways which are many, also is in processes the region only time to feed, in does not lift the knife in the situation to produce continuously the smooth cutting tool way, enters, draws back the knife way to use the circular arc to cut into, to cut. The spiral contour way characteristic is, has not waited the high level between the knife road migration, may avoid frequently lifting the knife, feeding to the components surface quality influence and mechanical device nonessential consuming. To is steep and the flat site processes separately, the computation suits contour and suits the use similar 3D bias the region, and may use the spiral way, in very little lifts the cutting tool way which the knife in the situation produces optimizes, obtains the better surface quality. In the high speed processing, certainly must adopt the circular arc to cut into, to cut the connection way, as well as the circular arc transition, avoids changing the cutting tool to enter suddenly for the direction, the prohibition use direct under knife connection way, avoids burying the cutting tool the work piece. When processes the mold cavity, should avoid the cutting tool vertical insertion work piece under, but should use inclines the knife way (commonly used angle of bank for 2030), best uses the screw type under knife by to reduce the cutting tool load. When processes the mold core, should under the knife then level cut into the work piece as far as possible first from the work piece. The cutting tool cuts into, cuts when the work piece should use as far as possible inclines the type (or round arc-type) cuts into, cuts, vertically avoids cutting into, cutting. Uses climbs up the type cutting to be possible to reduce the cutting heat, reduces the cutting tool stress and the work hardening degree, improves the processing quality. 2. Half precision work The mold half precision work essential target is causes the work piece outline shape smoothly, surface finish remainder even, this especially is important regarding the tool steel mold, because it will affect time the precision work cutting tool layer of cutting area change and cutting tool load change, thus influence cutting process stability and precision work surface quality. The rough machining is based on the volume model, the precision work then is based on the face mold. Before develops CAD/The CAM system to the components geometry description is not continual, after because has not described in front of the rough machining, the precision work processes the model the average information, therefore the rough machining surface surplus processing remainder distribution and the great surplus processing remainder is unknown. Therefore should fifty-fifty the precision work strategy carry on the optimization after to guarantee half precision work the work piece surface has the even surplus processing remainder. The optimized process includes: After the rough machining the outline computation, the great surplus processing remainder computation, the biggest permission processing remainder determination, is bigger than the biggest permission processing remainder the profile district (for example transition radius and so on scoop channel, corner is smaller than rough machining cutting tool radius region) as well as when half precision work the knife heart path computation to the surplus processing remainder and so on. The existing mold high speed processes C A D/The CAM software has the surplus processing remainder analysis function mostly, and can act according to the surplus processing remainder the size and the distribution situation uses the reasonable half precision work strategy. After like the MasterCAM software provided has tied the shape milling (Pencil milling) and the surplus milling (Rest milling) and so on the method eliminates the rough machining the surplus processing remainder big quoin by to guarantee the following working procedure even processing remainder. 3. Precision work The mold high speed precision work strategy is decided by the cutting tool and the work piece contact point, but the cutting tool and the work piece contact point but changes along with the processing surface curved surface slope and the cutting tool effective radius change. Regarding by the complex curved surface processing which many curved surface combination but becomes, should carry on the continuous treating as far as possible in a working procedure, but is not carries on the processing separately to each curved surface, by reduces lifts the knife, under the knife number of times. However, because processes the superficial slope change, if only defines the processing the side to eat the knife quantity (Step over), possibly creates on the slope different surface the actual step of distance non-uniformity, thus influence processing quality. In the ordinary circumstances, the precision work curved surface radius of curvature should be bigger than the cutting tool radius 1.5 times, by evades the no admittance to the direction suddenly transformation. In the mold high speed precision work, when each time cuts into, cuts the work piece, enters for the direction change should as far as possible use the circular arc or the curve switches over, avoids using the straight line to switch over, by maintains the cutting process the stability. High speed precision work strategy including three dimensional strategy and so on bias, contour precision work and best contour precision work, spiral contour precision work. These strategies may guarantee the cutting process light along, is stable, guarantees can fast excise on the work piece the material, obtains the high accuracy, the smooth cutting surface. The precision work basic request is needs to obtain the very high precision, the smooth components surface quality, relaxed realization fine region processing, like small fillet, trench and so on. Said to many shapes that, the precision work most effective strategy is the use three dimensional spiral strategy. Uses this kind of strategy to be possible to avoid the frequent direction change which uses the parallel strategy and in the bias precision work strategy can appear, thus the enhancement processing speed, reduces the cutting tool attrition. This strategy may in very little lift the knife in the situation to produce continuously the smooth cutting tool way. This kind of processing technology synthesized the spiral processing and the contour processing strategy merit, the cutting tool load stabler, proposes the knife number of times to be less, may reduce the process period, reduces the cutting tool damage probability. It also may improve the processing surface quality, after the most predestined time of death reduces the need which the precision work manually polishes. Needs unifies in many situations the steep region contour precision work and the flat site three dimensional equal-space precision work method the use. The numerical control programming also must consider the geometry design and the craft arrangement, when uses the CAM system carries on the high speed processing numerical control programming, besides the cutting tool and the processing parameter basis special details choice, the programming strategy which the processing method choice and uses has become the key. Splendid use CAD/The CAM workstation programs engineer to be supposed at the same time also to be a qualified design and the technologist, he should have a correct understanding to the components geometry structure, has knowledge and concept which designs regarding the ideal working procedure arrangement as well as the reasonable cutting tool path. Fifth, high-speed cutting numerical control programming The high speed milling processing is more and more high to the numerical control programming system request, the price expensive high speed processing equipment proposed a higher secure and the valid request to the software. The high-speed cutting has compared to the traditional cutting special technological requirement, besides must have the high-speed cutting engine bed and the high-speed cutting cutting tool, has the appropriate CAM programming software also is very important. The numerical control processing numerical control instruction has contained all technological process, outstanding high speed processes the CAM programming system to be supposed to have the very high computation speed, strong inserts makes up the function, the entire journey is automatic has cut the inspection and the handling ability, the automatic hilt and the jig interference inspection, enters for rate the optimized processing function, treats the processing path monitoring function, the cutting tool path edition optimization function and the processing remaining analysis function and so on. The high-speed cutting programming first must pay attention to the processing method the security and the validity； Next, must guarantee with utmost effort the cutting tool path smooth is steady, this can affect components the directly and so on processing quality and engine bed main axle life； Finally, must cause the cutting tool load to be even as far as possible, this can affect the cutting tool directly the life. 1. The CAM system should have the very high computation programming speed In the high speed processing uses extremely small entering and cuts the depth for the quantity, its NC procedure must be much bigger than to the traditional numerical control processing procedure, thus requests the software computation speed to have to be quick, by saves the cutting tool path edition and the optimized programming time. 2. The entire journey automatically guards against has cut the handling ability and the automatic hilt interference inspection ability The high speed processing processes the nearly 10 time of cuttings speeds by the tradition to carry on the processing, once will occur has cut to the engine bed, the product and the cutting tool has the calamity consequence, therefore will request its CAM system to have to have the entire journey automatically to guard against has cut processing the ability and the automatic hilt and the jig interference inspection, circles evades the function. The system can automatically prompt short supports on both sides the cutting tool length, and automatically carries on the cutting tool interference inspection. 3. Rich high-speed cutting cutting tool path strategy The high speed processing to processes the craft to feed the way to have the special request compared to the traditional way, in order to can guarantee the maximum cutting efficiency, also guaranteed when high-speed cutting processes the security, the CAM system ought to be able to act according to processes the instantaneous remainder the size automatically to enter for rate carries on optimized processing, can automatically carry on the cutting tool path edition to optimize, the processing remaining analysis and the treatment processing path monitoring, by guarantees the high speed processing cutting tool stressful condition the stability, enhances the cutting tool the service life. After uses the high speed processing equipment, will be able to increase to programmers demand, because high speed will process the technological requirement strictly, has cut the protection to be more important, therefore will have to spend the much time to carry on the simulation examination to the NC instruction. In the ordinary circumstances, high speed processes the programming time the to be ordinary than processing programming time to have to be much longer. In order to guarantee the high speed processing equipment enough utilization ratio, must dispose the more CAM personnel. The existing CAM software, like PowerMILL, MasterCAM, UnigraphicsNX, Cimatron and so on have all provided the correlation function high speed milling cutting tool path strategy. Sixth, concluding remark The high-speed cutting technology is one of machining technology main development directions, at present mainly applies in the automobile industry and the mold profession, in the processing complex curved surface domain, work piece itself or the cutting tool system rigidity request high processing domain and so on, is the many kinds of advanced processings technology integration in particular, its is highly effective high grade, esteems for the people. It not only involves to the high speed processing craft, moreover also includes high speed processes the engine bed, the numerical control is systematic, the high-speed cutting cutting tool and CAD/CAM technology and so on. The mold high speed processing technology generally has applied at present in the developed country mold manufacturing industry, but still waited for in our countrys application scope and the application level the enhancement, because it had the tradition to process the incomparable superiority, still will be the next processing technology inevitable development direction. 中文翻譯 模具高速銑削加工技術(shù) 一、前言 在現(xiàn)代模具生產(chǎn)中，隨著對(duì)塑件的美觀度及功能要求得越來越高，塑件內(nèi)部結(jié)構(gòu)設(shè)計(jì)得越來越復(fù)雜，模具的外形設(shè)計(jì)也日趨復(fù)雜，自由曲面所占比例不斷增加，相應(yīng)的模具結(jié)構(gòu)也設(shè)計(jì)得越來越復(fù)雜。這些都對(duì)模具加工技術(shù)提出了更高要求，不僅應(yīng)保證高的制造精度和表面質(zhì)量，而且要追求加工表面的美觀。隨著對(duì)高速加工技術(shù)研究的不斷深入，尤其在加工機(jī)床、數(shù)控系統(tǒng)、刀具系統(tǒng)、 CAD/CAM 軟件等相關(guān)技術(shù)不斷發(fā)展的推動(dòng)下，高速加工技術(shù)已越來越多地應(yīng)用于模具型腔的加工與制造中 。 數(shù)控高速切削加工作為模具制造中最為重要的一項(xiàng)先進(jìn)制造技術(shù)，是集高效、優(yōu)質(zhì)、低耗于一身的先進(jìn)制造技術(shù)。相對(duì)于傳統(tǒng)的切削加工，其切削速度、進(jìn)給速度有了很大的提高，而且切削機(jī)理也不相同。高速切削使切削加工發(fā)生了本質(zhì)性的飛躍，其單位功率的金屬切除率提高了 30%40%，切削力降低了 30%，刀具的切削壽命提高了 70%，留于工件的切削熱大幅度降低，低階切削振動(dòng)幾乎消失。隨著切削速度的提高，單位時(shí)間毛坯材料的去除率增加了，切削時(shí)間減少了，加工效率提高了，從而縮短了產(chǎn)品的制造周期，提高了產(chǎn)品的市場(chǎng)競(jìng)爭力。同時(shí)，高速加工 的小量快進(jìn)使切削力減少了，切屑的高速排出減少了工件的切削力和熱應(yīng)力變形，提高了剛性差和薄壁零件切削加工的可能性。由于切削力的降低，轉(zhuǎn)速的提高使切削系統(tǒng)的工作頻率遠(yuǎn)離機(jī)床的低階固有頻率，而工件的表面粗糙度對(duì)低階頻率最為敏感，由此降低了表面粗糙度。在模具的高淬硬鋼件 (HRC45HRC65)的加工過程中，采用高速切削可以取代電加工和磨削拋光的工序，從而避免了電極的制造和費(fèi)時(shí)的電加工，大幅度減少了鉗工的打磨與拋光量。對(duì)于一些市場(chǎng)上越來越需要的薄壁模具工件，高速銑削也可順利完成，而且在高速銑削 CNC 加工中心上，模具 一次裝夾可完成多工步加工。 高速加工技術(shù)對(duì)模具加工工藝產(chǎn)生了巨大影響，改變了傳統(tǒng)模具加工采用的“退火銑削加工熱處理磨削”或“電火花加工手工打磨、拋光”等復(fù)雜冗長的工藝流程，甚至可用高速切削加工替代原來的全部工序。高速加工技術(shù)除可應(yīng)用于淬硬模具型腔的直接加工 (尤其是半精加工和精加工 )外，在 EDM 電極加工、快速樣件制造等方面也得到了廣泛應(yīng)用。大量生產(chǎn)實(shí)踐表明，應(yīng)用高速切削技術(shù)可節(jié)省模具后續(xù)加工中約 80%的手工研磨時(shí)間，節(jié)約加工成本費(fèi)用近 30%，模具表面加工精度可達(dá) 1 m，刀具切削效率可提高 1 倍。 二、高速銑削加工機(jī)床 高速切削技術(shù)是切削加工技術(shù)的主要發(fā)展方向之一，它隨著 CNC 技術(shù)、微電子技術(shù)、新材料和新結(jié)構(gòu)等基礎(chǔ)技術(shù)的發(fā)展而邁上更高的臺(tái)階。由于模具加工的特殊性以及高速加工技術(shù)的自身特點(diǎn)，對(duì)模具高速加工的相關(guān)技術(shù)及工藝系統(tǒng) (加工機(jī)床、數(shù)控系統(tǒng)、刀具等 )提出了比傳統(tǒng)模具加工更高的要求。 1. 高穩(wěn)定性的機(jī)床支撐部件 高速切削機(jī)床的床身等支撐部件應(yīng)具有很好的動(dòng)、靜剛度，熱剛度和最佳的阻尼特性。大部分機(jī)床都采用高質(zhì)量、高剛性和高抗張性的灰鑄鐵作為支撐部件材料，有的機(jī)床公司還在底座中添加高阻尼特性的 聚合物混凝土，以增加其抗振性和熱穩(wěn)定性，這不但可保證機(jī)床精度穩(wěn)定，也可防止切削時(shí)刀具振顫。采用封閉式床身設(shè)計(jì)，整體鑄造床身，對(duì)稱床身結(jié)構(gòu)并配有密布的加強(qiáng)筋等也是提高機(jī)床穩(wěn)定性的重要措施。一些機(jī)床公司的研發(fā)部門在設(shè)計(jì)過程中，還采用模態(tài)分析和有限元結(jié)構(gòu)計(jì)算等，優(yōu)化了結(jié)構(gòu)，使機(jī)床支撐部件更加穩(wěn)定可靠。 2. 機(jī)床主軸 高速機(jī)床的主軸性能是實(shí)現(xiàn)高速切削加工的重要條件。高速切削機(jī)床主軸的轉(zhuǎn)速范圍為 10000100000m/min，主軸功率大于 15kW。通過主軸壓縮空氣或冷卻系統(tǒng)控制刀柄和主軸間的軸向 間隙不大于 0.005mm。還要求主軸具有快速升速、在指定位置快速準(zhǔn)停的性能 (即具有極高的角加減速度 )，因此高速主軸常采用液體靜壓軸承式、空氣靜壓軸承式、熱壓氮化硅（ Si3N4）陶瓷軸承磁懸浮軸承式等結(jié)構(gòu)形式。潤滑多采用油氣潤滑、噴射潤滑等技術(shù)。主軸冷卻一般采用主軸內(nèi)部水冷或氣冷。 3. 機(jī)床驅(qū)動(dòng)系統(tǒng) 為滿足模具高速加工的需要，高速加工機(jī)床的驅(qū)動(dòng)系統(tǒng)應(yīng)具有下列特性： (1) 高的進(jìn)給速度。研究表明，對(duì)于小直徑刀具，提高轉(zhuǎn)速和每齒進(jìn)給量有利于降低刀具磨損。目前常用的進(jìn)給速度范圍為 2030m/min，如采用大導(dǎo)程滾珠絲杠傳動(dòng)，進(jìn)給速度可達(dá) 60m/min；采用直線電機(jī)則可使進(jìn)給速度達(dá)到120m/min。 (2)高的加速度。對(duì)三維復(fù)雜曲面廓形的高速加工要求驅(qū)動(dòng)系統(tǒng)具有良好的加速度特性，要求提供高速進(jìn)給的驅(qū)動(dòng)器 (快進(jìn)速度約 40m/min， 3D 輪廓加工速度為 10m/min)，能夠提供 0.4m/s2 到 10m/s2 的加速度和減速度。 機(jī)床制造商大多采用全閉環(huán)位置伺服控制的小導(dǎo)程、大尺寸、高質(zhì)量的滾珠絲杠或大導(dǎo)程多頭絲杠。隨著電機(jī)技術(shù)的發(fā)展，先進(jìn)的直線電動(dòng)機(jī)已經(jīng)問世，并成功應(yīng)用于 CNC 機(jī) 床。先進(jìn)的直線電動(dòng)機(jī)驅(qū)動(dòng)使 CNC 機(jī)床不再有質(zhì)量慣性、超前、滯后和振動(dòng)等問題，加快了伺服響應(yīng)速度，提高了伺服控制精度和機(jī)床加工精度。 4. 數(shù)控系統(tǒng) 先進(jìn)的數(shù)控系統(tǒng)是保證模具復(fù)雜曲面高速加工質(zhì)量和效率的關(guān)鍵因素，模具高速切削加工對(duì)數(shù)控系統(tǒng)的基本要求為： (1) 高速的數(shù)字控制回路 (Digital control loop)，包括： 32 位或 64 位并行處理器及 1.5Gb 以上的硬盤；極短的直線電機(jī)采樣時(shí)間。 (2)速度和加速度的前饋控制 (Feed forward control)；數(shù) 字驅(qū)動(dòng)系統(tǒng)的爬行控制 (Jerk control)。 (3) 先進(jìn)的插補(bǔ)方法 ( 基于 NURBS 的樣條插補(bǔ) )，以獲得良好的表面質(zhì)量、精確的尺寸和高的幾何精度。 (4)預(yù)處理 (Look-ahead)功能。要求具有大容量緩沖寄存器，可預(yù)先閱讀和檢查多個(gè)程序段 (如 DMG 機(jī)床可多達(dá) 500 個(gè)程序段， Simens 系統(tǒng)可達(dá) 10002000 個(gè)程序段 )，以便在被加工表面形狀 (曲率 )發(fā)生變化時(shí)可及時(shí)采取改變進(jìn)給速度等措施以避免過切等。 (5)誤差補(bǔ)償功能，包括因直線電機(jī)、主軸等發(fā)熱導(dǎo)致的熱誤差補(bǔ)償、象限誤 差補(bǔ)償、測(cè)量系統(tǒng)誤差補(bǔ)償?shù)裙δ堋?此外，模具高速切削加工對(duì)數(shù)據(jù)傳輸速度的要求也很高。 (6) 傳統(tǒng)的數(shù)據(jù)接口， 如 RS232 串行口的傳輸速度為 19.2kb，而許多先進(jìn)的加工中心均已采用以太局域網(wǎng) (Ethernet)進(jìn)行數(shù)據(jù)傳輸，速度可達(dá) 200kb。 5. 冷卻潤滑 高速加工采用帶涂層的硬質(zhì)合金刀具，在高速、高溫的情況下不用切削液，切削效率更高。這是因?yàn)椋恒娤髦鬏S高速旋轉(zhuǎn)，切削液若要達(dá)到切削區(qū)，首先要克服極大的離心力；即使它克服了離心力進(jìn)入切削區(qū)，也可能由于切削區(qū)的高溫而立即蒸發(fā)，冷卻 效果很小甚至沒有；同時(shí)切削液會(huì)使刀具刃部的溫度激烈變化，容易導(dǎo)致裂紋的產(chǎn)生，所以要采用油 /氣冷卻潤滑的干式切削方式。這種方式可以用高壓氣體迅速吹走切削區(qū)產(chǎn)生的切削，從而將大量的切削熱帶走，同時(shí)經(jīng)霧化的潤滑油可以在刀具刃部和工件表面形成一層極薄的微觀保護(hù)膜，可有效地延長刀具壽命并提高零件的表面質(zhì)量。 三、高速切削加工的刀柄和刀具 由于高速切削加工時(shí)離心力和振動(dòng)的影響，要求刀具具有很高的幾何精度和裝夾重復(fù)定位精度以及很高的剛度和高速動(dòng)平衡的安全可靠性。由于高速切削加工時(shí)較大的離心力和振動(dòng)等特點(diǎn)，傳統(tǒng) 的 7:24 錐度刀柄系統(tǒng)在進(jìn)行高速切削時(shí)表現(xiàn)出明顯的剛性不足、重復(fù)定位精度不高、軸向尺寸不穩(wěn)定等缺陷，主軸的膨脹引起刀具及夾緊機(jī)構(gòu)質(zhì)心的偏離，影響刀具的動(dòng)平衡能力。目前應(yīng)用較多的是 HSK 高速刀柄和國外現(xiàn)今流行的熱脹冷縮緊固式刀柄。熱脹冷縮緊固式刀柄有加熱系統(tǒng)，刀柄一般都采用錐部與主軸端面同時(shí)接觸，其剛性較好，但是刀具可換性較差，一個(gè)刀柄只能安裝一種連接直徑的刀具。由于此類加熱系統(tǒng)比較昂貴，在初期時(shí)采用HSK 類的刀柄系統(tǒng)即可。當(dāng)企業(yè)的高速機(jī)床數(shù)量超過 3 臺(tái)以上時(shí)，采用熱脹冷縮緊固式刀柄比較合適。 刀具是高 速切削加工中最活躍重要的因素之一，它直接影響著加工效率、制造成本和產(chǎn)品的加工精度。刀具在高速加工過程中要承受高溫、高壓、摩擦、沖擊和振動(dòng)等載荷，高速切削刀具應(yīng)具有良好的機(jī)械性能和熱穩(wěn)定性，即具有良好的抗沖擊、耐磨損和抗熱疲勞的特性。高速切削加工的刀具技術(shù)發(fā)展速度很快，應(yīng)用較多的如金剛石 (PCD)、立方氮化硼 (CBN)、陶瓷刀具、涂層硬質(zhì)合金、 (碳 )氮化鈦硬質(zhì)合金 TIC(N)等。 在加工鑄鐵和合金鋼的切削刀具中，硬質(zhì)合金是最常用的刀具材料。硬質(zhì)合金刀具耐磨性好，但硬度比立方氮化硼和陶瓷低。為