The freeboard that faces 21 centuries fast grinding technology

Technology of high speed grinding is grinding craft itself is revolutionary jump change, it is to get used to a when contemporary high-tech needs and development rises burgeoning and integrated technology, contemporary machinery, electron, optical, computer, hydraulic pressure, material reachs its market metric wait for advanced science and technology to accomplish at an organic whole. Make the progress that waits for crucial technology as emery wheel intensity and machine tool, emery wheel rate rises greatly, at present grinding purify rate already jumped S of 3 000mm3/mm · , more even, can rival with the cutting treatment such as car, mill, dig, especially in recent years all sorts of burgeoning hard fragile data, the wide application that waits like optical crystal, optical glass, pottery and porcelain, monocrystalline silicon, promoted the swift and violent development of technology of high speed grinding. International production engineering is met (CIRP) already was technology of high speed grinding the center that faces 21 centuries to study one of way certainly. The grinding of 45m/s of prep above of emery wheel speed calls high speed grinding. Speed of emery wheel of high speed grinding amounts to 60~250m/s now, workpiece feed speed is 1 000~10 000m/min.

60~120m/s is in emery wheel speed inside, use common emery wheel, grinding purify rate can amount to S of 500~1 000mm3/mm · , 120~250m/s is in emery wheel speed inside, use CBN (cubic nitrogen changes boron) emery wheel, grinding purify rate can amount to S of 2 000mm3/mm · .

German A go smoothly (Aachen) industrial university, the freeboard that undertakes 500m/s of emery wheel speed is a target fast grinding experiments, undertake study integratedly to emery wheel and grinding engineering technology. Thought craft of high speed grinding does not agree with in the past machine old plane or cylindrical exterior precision work, basically use at groove and breach grinding and infeed grinding, but the research of Japan, Germany makes clear, raise grinding speed to be able to improve workpiece grinding quality apparently, reduce grinding force, obtain minor on size error and appearance error, raise treatment precision. The freeboard of Japanese research and development fast (emery wheel speed is 160~260m/s) cylindrical grinder, use CBN emery wheel, can obtain circularity error to be 1 μ M, exterior surface roughness is worth R Z=1.

The grinding effect of 2 μ M. One, the characteristic that exceeds high speed grinding exceeds high speed grinding and common grinding photograph to stress a dominant position below than having: (1) grinding force is small, precision of spare parts treatment is tall. When grinding efficiency is identical, 50% what the grinding force when grinding speed amounts to 200m/s is 80m/s for grinding speed only.

But in identical sheet below condition of the excision that wear bead, grinding speed affects minimum to grinding force, raise treatment precision thereby. (2) the workpiece face that can get high quality, low surface roughness is worth. Grind in material except lead changeless condition to fall, raise grinding speed to be able to reduce sheet the grinding deepness that wears bead, reduce grinding force thereby. Reduce workpiece surface surface roughness to be worth and when processing low stiffness work, assure to machine precision easily. If still retain original grinding power when high speed grinding, can raise feed rate, reduce handling time, improve manufacturing efficiency. (3) can improve grinding efficiency substantially, reduce equipment to use a number. Before grinding applies to finish machining only, although treatment precision is tall but mental allowance is very small. Need to arrange a lot of rough machining working procedure before grinding, need to cooperate the machine tool of different type, made a long craft chain. The material of grinding of current high speed is ground except rate already can compare with photograph of turning, milling, for this grinding treatment can make finish machining can make rough machining again already, can reduce machine tool sort greatly so, simplify technological process. To certain for the product that is final treatment working procedure with grinding, high speed grinding can reduce manufacturing cost substantially to reach improve product quality. (4) can prolong emery wheel life substantially, be helpful for implementing the automation that grinding machines. In grinding force changeless condition falls, with grinding of grinding speed 200m/s when, emery wheel life is compared with one times rising when 80m/s grinding, and in grinding efficiency changeless condition falls, emery wheel life can rise 7.

8 times. Emery wheel life and grinding rate rise into logarithm relation, when nitrogen of grinding of use diamond emery wheel changes silicon pottery and porcelain, grinding rate rises 160m/s by 30m/s, emery wheel grinding is compared by 900 raise 5 100, be helpful for realizing automation grinding. (5) the influence that crossed grinding successfully to heat up raceway groove, workpiece surface layer is attainable remains pressing changes force (advantageous to workpiece stability) . 2, each relevant technology that the graph below the crucial technology that exceeds high speed grinding listed place of fast grinding technology needs freeboard, among them the design of high speed bearing and high speed emery wheel and making is the mainest factor that the influence exceeds technology of high speed grinding to apply. Nextpage 　 　 1.

Exceed emery wheel of high speed grinding (1) the structure that exceeds high speed emery wheel with production freeboard fast grinding emery wheel must satisfy following requirement: The mechanical intensity of emery wheel matrix must can bear the cutting force when high grinding; The exterior is sharp, grind an outstanding height to want namely big, so that can accommodate many length to cut bits; Bond must have very tall wearability, with reducing emery wheel wear away. From the development that exceeds high speed grinding the trend looks, the proportion that diamond and CBN emery wheel hold in exceeding high speed grinding is larger and larger, uses bond can be colophony, pottery and porcelain and metal. As the development of the farther promotion that exceeds high speed grinding and scientific research, grind bead and bond new-styly to also be in ceaseless occurrence. Eletroplate combinative emery wheel is used extensively when exceeding high speed grinding, the outstanding height that its wear bead is very great, can accommodate cut bits in great quantities, form blunt blade cutting not easily, very advantageous to exceeding high speed cutting. Because eletroplate,combinative emery wheel wears bead one layer only, in using a process so, do not need to undertake nap, can save expensive nap plant and nap man-hour thereby. Development of Swiss Winterthur company goes a kind of new CBN emery wheel recently, the basic form that wears bead is tetrahedral, when grinding force increases fixed rate meeting generation breaks up, form new sharp cutting blade thereby. When steel of grinding alloy tool, can drop cutting force and cutting temperature effectively; Hold emery wheel when life is changeless, can improve data grind the precision that divides rate and work. In recent years, because decreased to ground bead layer ply to improve relevant workmanship measure, emery wheel of bond of pottery and porcelain already ran in the safety below 300m/s, monolayer eletroplates the use speed of CBN emery wheel is optional 250m/s.

Europe basically uses monolayer to eletroplate CBN emery wheel undertakes efficient figuration grinding mixes high speed groovy grinding. American Norton company uses the metallic monolayer emery wheel that cupreous solder technology excogitates, its grind bead to highlight than already achieving 70%~80% , the space that hold bit increases greatly, bond tensile strength exceeds 1 500N/mm2, can make below identical grinding condition grinding force is reduced 50% , raised grinding efficiency limit further. Keep sharp in whole service life to assure emery wheel, the structure of emery wheel should be helpful for grinding a dissension, maintain from encourage process. Should reach emery wheel from sharp aim, besides the scale that lowers bond as far as possible, optimize the space that wears bead to distributing even. For this, can pass computer cipher out the action when all sorts of dissension that wear bead is in individual the power that obliterates bead to go up, can decide the scale of bond thereby. Our country still does not have freeboard up to now fast special emery wheel, design the research of theory and the respect such as production installation to just begin around what exceed emery wheel of high speed grinding. (2) the nap that exceeds high speed emery wheel exceeds high speed monolayer to eletroplate emery wheel does not need prune commonly. Kibble bead, low density is used to eletroplate below special situation tool of nap of cup form diamond is only right undertake micron class nap bit higher individually. The experiment makes clear, when nap implement feed is when 3~5 μ M, not only can assure workpiece quality, and can prolong emery wheel life. To grinding of certain high speed, want to have tall grinding efficiency not only, and have high grinding quality even (tall treatment precision and low exterior surface roughness are worth) , for this, due to emery wheel a perfect nap technology. Emery wheel of fast metal bond uses freeboard commonly electroanalysis nap, the nap size that exceeds emery wheel of bond of high speed pottery and porcelain has main effect to grinding quality. The main shaft that machine of work of Japanese abundant field exceeds high speed cylindrical grinder in GZ50 is hind of full automatic nap device, diamond gyro wheel rotates with the speed of 25 000r/min, use emissive sensor to undertake detecting to surface of CBN emery wheel, with 0.

The feed precision of 1 μ M undertakes nap to exceeding high speed emery wheel. In view of the confine of traditional nap law, people developed a variety of exceeding to grind way of nap of bead emery wheel forcedly, have online electroanalysis nap law (ELID) , law of nap of vibration of online nap law, stretch nap law, ultrasonic mixes double electrode laser nap law, among them laser nap law is to solve exceed a kind of good method that grinds nap of bead emery wheel forcedly. It has nap rate fast, work efficiency realizes automation material of tall, economic emery wheel, easily to carry out the advantage such as online nap. Exceed photograph of hard emery wheel to compare with nap of filing of common emery wheel especially, of laser nap super- grind an emery wheel forcedly to have good grinding performance, below identical grinding condition, the grinding force when grinding pottery and porcelain reduces 10%~15% .

The experiment already made clear, value and power density are surface roughness of the grinding power that the emery wheel that diamond nap crosses produces, surface 6.

The emery wheel of nap of 0 × 1010W/m2 laser is close to basically. But the continuance as grinding process, after a certain number of grinding journeys, the emery wheel that laser nap crosses presents better metabolic trend: Grinding force keeps long inside stable, exterior surface roughness is worth inferior. (3) because the emery wheel that exceeds the dynamic balancing technology of high speed emery wheel to exceed place of high speed grinding to use is made make the error such as outfit clip with tone, changing start afresh after jockey even after emery wheel or nap emery wheel when, grinding spindle must undertake dynamic balancing. For this, high grinding main shaft must have system of successive and automatic dynamic balancing, the minorrest rate lowers vibration in order to make when grinding, obtain taller treatment precision and inferior workpiece surface surface roughness to be worth thereby. According to the balance principle of device of automatic dynamic balancing and different configuration, technology of automatic dynamic balancing can distribute emery wheel the following kinds of forms: Technology of Electromechanical type dynamic balancing: 20 centuries 80 time end, production of company of American Schmitt Industries gave a kind to be known as: System of the world's most advanced dynamic balancing of online grinder emery wheel- - emery wheel of SBS computerization grinder balances a system. This system is by personal computer control small electromotor moves of equalizer interior tiny heavy piece, thereby the counterbalance of nap emery wheel. Japanese development goes a kind of light to accuse balancer, the main transfer machinery that dominates equalizer interior through personal computer and drive original will move the counterbalance of emery wheel of balance piece nap. The liquid is spoon-fed dynamic balancing technology: German Hofmann company (technology of special development dynamic balancing and device) put forward emery wheel liquid device of automatic dynamic balancing, this kind of device is in the flange of emery wheel dish get on 4 installation size is certain store water antrum, distributing equably at different quadrant, every are entered cistern and with pilot of electromagnetism a powerful person gush water mouth is opposite should, pass different gush water mouth but to what differ store the liquid that water antrum infuse measures certainly, change the quality with different and quadrantal emery wheel thereby, realize the automatic dynamic balancing of emery wheel. Technology of dynamic balancing of fluid steam type: Development of American Balance Dynamics Corporation uses fluorine Lyons one kind successfully to regard the fluid steam that balances medium as equalizer of type emery wheel. The characteristic of this device is a structure simple, wait for athletic spare parts without mouth, nozzle, valve and gear, function is reliable, do not need to maintain, use convenient. After Lyons of steam condition fluorine is cooling reductive for liquid state, reservation is inside antrum, although emery wheel stops,turn, still can poise condition. 2.

The cooling and lubricant system that exceeds high speed grinding is in in exceeding process of high speed grinding, the advantage of cooling and lubricant system often can decide the success or failure of whole grinding process. Cooling and lubricant function is the material excision rate that raises grinding, prolong the service life of emery wheel, reduce workpiece surface surface roughness to be worth. Cooling and lubricant system must finish lubricant, refrigeration in exceeding process of high speed grinding, clean emery wheel to reach deferent cut bits 4 big jobs. Still need to temperature controls a system to cool in order to ensure to grinding of high accuracy, high speed the temperature of lubricating fluid is constant. To exceeding high speed grinding, the feed flow that needs to use above of 7 × 106Pa controls force and large flow, choose to exceed method of feed flow of fluid of high speed grinding suitably, can make the space holding bit of emery wheel gets be cleaninged adequately so, avoid emery wheel to jam, cause grind bead to give out heat wear away reach grinding force to increase. In exceeding high speed grinding, it is a target in order to come true without grinding fluid, can implement dry form (green) grinding method. Grinding of grinding of the refrigeration that be like wind, liquid nitrogen refrigeration. 3.

Exceed high speed main shaft and freeboard fast bearing technology (1) exceed technology of main shaft of high speed report to exceed high speed grinding to basically use high-power to exceed main shaft of high speed report currently, the advantage is main shaft inertial torsion is small, oscillatory noise is little, high speed performance is good, can shorten increase slowdown time. But look from precision respect, how abate electromotor is calorific and medicinal powder heat will become henceforth the task of research and development. Current, german Hofmann company is undertaking grinding experiments exceeding high speed, use most the high frequency main shaft that high-power is 25kW, will achieve the emery wheel rate of 500m/s, can leave regular job in 30 000r/min and 40 000r/min rotate speed. Plant of a bearing of Japanese is used inside assembled servo electromotor to develop a kind to exceed high speed wheelhead, in 25 × 104r/min high speed leaves can steady job. Nextpage 　 　 (2) exceeding bearing of nicety of high speed of technology of high speed bearing is the core part that exceeds system of main shaft of high speed grinding. It divides ball bearing, liquid static press bearing, air static press bearing of bearing and magnetism float 4 kinds big. Because roll bearing has a lot of advantages, at present foreign majority exceeds on purpose high speed grinder uses scroll bearing, but cannot use steel ball bearing. To increase its limited speed, often adopt following measure: ① increases production accuracy class. Material of ② logical choice. To choose the mixture ball bearing of ball of pottery and porcelain and circle of steeliness bearing inside and outside, can make its life raises 3~6 times, limited speed increases 60% , and temperature rise reduces 30%~60% , its DN value achieves 3 million above. ③ improves bearing composition. The new-style freeboard that firm of German FAG bearing develops bearing of fast main shaft, narrow ball diameter to 70% , increased ball number, raised the stiffness of bearing thereby, if lubricate sufficient and reasonable, the DN value when its work continuously can be achieved 2.5 million. Use hollow scroll body to be able to reduce scroll quality, reduce centrifugal force and top moment of force thereby. The CNC that Japanese northeast university develops exceeds grinding machine of high speed plane, ball bearing of use pottery and porcelain, main shaft rotate speed is 3 × 104r/min.

The G250 that machine of abundant field work develops in its CNC exceeded jacket of high speed cylindrical grinder to have the bearing of Toyoda State Bearing of newest development, use speed is the emery wheel of CBN of bond of pottery and porcelain of 200m/s, undertook to circumgyrate body spare parts efficient, high accuracy and Gao Rou sex are machined. Company of Japanese Toshiba machinery is on ASN40 machining center, used improvement air bearing to realize rotate speed of 3 × 104r/min main shaft below high-power. Japanese light modern essence of life is versed in Ceng Chenggong land of company of Kapp of company limited, Germany is on grinder of its high speed used magnetism float bearing. Power comsumption of drive of magnetism float bearing is small, maintain cost low, do not need complex, costly sealed parts of an apparatus, but bearing itself cost is too high, control system is complex. The grinding spindle of magnetism float bearing that German Kapp company uses, rotate speed can achieve 6 × 104r/min.

The rotate speed of the main shaft of magnetism float bearing of German GMN company is top can achieve 104r/min above. Additional, bearing of liquid quiet dynamic pressure already also applied at high speed, efficient grinder gradually. 4.

The slip drive system that system of drive of high speed feed exceeds machine tool of high speed grinding is in what 20 centuries use drive of guide screw of big lead ball and the rotate speed that increase servo feed electromotor to come true mostly at the beginning of 90 time, general feed speed can amount to 60m/min.

To can achieve higher feed rate, appeared in last few years system of linear electromotor drive, because its very close to each other is unoccupied place, inertial small, stiffness range of big, speed is wide, repeat precision to be mixed high without wear away, through control circuit can realize high rate and high drive, 1997 feed speed already amounted to 120m/min. Anorad company of the United States is the world on most move the linear electromotor of the name produces business, this company was rolled out 1988 without brush dc linear electromotor, win American patent. Company main production is not had brush dc linear electromotor (permanent magnetism synchronism is linear electromotor) , newest without core LZ series linear electromotor has 48 kinds of type, active force is 350~4 000N, fashioned a series of products of different structure, different power, apply extensively at all sorts of domains. Current, the linear motor production that abroad is comparing a name and supplier besides Anorad company, still have industrial giant Parker of the United States- - company of Hannifin, Aerotech, Kollmorgen, company of German Siemens, Indramat, the ETEL company of company of 3 water chestnut of Japanese, FANUC and Switzerland. Indramat company of Germany produces inductive type already linear electromotor, produce magneto again linear electromotor, in all a variety of 50 model. Magneto is had efficient (highest 1.

72N/W) reach the characteristic such as tall thrust density. According to the report, its product rate can achieve 600 M/min, thrust amounts to 22kN. Linear electromotor suits the magneto of Swiss ETEL company very much make system of feed of high speed machine tool, its are main the characteristic is: Have very tall electromotor constant K M, conformity of water refrigeration system in electromotor winding, eliminated flow to the steam of the machine tool from electromotor, force density is very high, can achieve 4.

9~7.

8N/cm2, acceleration can amount to 300m/s2, taller even, have very tall servo stiffness, 300N/ μ M is inside 30~60Hz. 3, the development trend that exceeds technology of high speed grinding (1) the high speed main shaft that develops high-power should develop main shaft of high-power high speed energetically, only main shaft can output greater power when high rotate speed, the economic benefits ability of high speed grinding fills minute of play. (2) the new-style emery wheel that development gets used to high grinding and outside machining intelligence to change a technology to wear bead new-styly except research and development, still must reach bond and the groove of the system that wear bead to have sufficient research to applying to the bond of high speed grinding. In addition, grind an emery wheel forcedly to the price exceeds costlily, want to develop its adequately to produce the advantage that tall, service life grows efficiency, should reduce its to use up as far as possible and raise nap efficiency and precision. For this, the testing system grinding that should develop grinding database and knowledge base to be a foundation machines intelligence to change a technology. (3) improve existing grinder structure and development because emery wheel is lopsided,machine tool of the 3rd acting high speed is in to be reduced as far as possible when high speed the vibration that cause, should deploy system of online and automatic dynamic balancing, in order to make the machine tool is when different rotate speed, be in first-rate movement condition from beginning to end. Produce efficiency and treatment precision to rise, should use high speed, efficient the system of linear feed drive with high accuracy. Of shunt-wound kinematic machine tool appear, it is when 90 time machine tool designs 20 centuries and make a technology revolutionary change, because its have the distinct advantage that place of a lot of general accuracy machine tool do not have, reason caused extensive attention. Shunt-wound machine tool regards the 3rd generation as the machine tool, want to be developed actively, make its enter applied phase stage by stage. (4) positive development does type (green) cooling and lubricant technology is in in exceeding high speed grinding, want to continue to optimize cooling and lubricant system. In addition, as a result of the need of environmental protection, should develop dry type energetically (green) cooling and lubricant technology, namely the technology such as grinding of grinding of wind refrigeration high speed, high speed of liquid nitrogen refrigeration. (5) the next target that stride of high speed of Xiang Chao of high speed grinding exceeds high speed grinding to use research is to break through velocity of sound to close greatly, raise grinding rate to 350m/s above, make the grinding speed of 500m/s becomes a possibility on industrial application then. CNC Milling