Grinding of high speed of CBN of engine crankshaft camshaft is machined

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  • source:SHERBURNE CNC Machining
The concept that high speed machines is by Carl of German cutting physicist.

J.

Dr. Salomon put forward above all 1931, he published famous Salomon curve, creativity ground predicted the is not cutting work area existence that surmounts Talor cutting equation, if can raise cutting rate substantially,put forward, the high temperature dead cereal that can cross cutting process to arise and make cutting tool is in exceed high speed area to undertake high speed cutting, reduce cutting man-hour substantially thereby, twice land improves machine tool productivity. The mechanism of high speed grinding is in process of treatment of high speed grinding, in maintain the condition with other changeless parameter to fall, as emery wheel speed rise substantially, the number wearing bead of area of the grinding inside unit time increases, every ply worrying bit that grinds bead to be cut attenuates; The experiment shows in high speed grinding the condition falls, a few what the cut area that worries bit falls for common grinding condition only. Brought about big decrescent of muscularity of grinding of every susceptive that wear bead thereby, so total grinding muscularity is reduced greatly. If make through adjusting parameter the ply that worry bit keeps changeless, because the number wearing bead of cutting is participated in to increase inside unit time, worry the increase worrying bit that eliminate, grinding efficiency can rise greatly. When high speed grinding, because grinding rate is very high, individual the formation that worries bit time is extremely short. The worries bit tall meet an emergency that finishs inside cutty time is led (can think to be equal to grinding speed approximately) form process and common grinding to have very big difference, expression is out of shape for the flexibility of workpiece surface the layer becomes shallow, the apophysis height decrescent that two side form grinding channel mark because of plasticity flow, the plough in grinding bits to fashion a process and slippery brush distance decrescent, workpiece expresses facing sclerosis and leftover stress tendency to reduce. In addition, the floating rate that bead grinds to go up in grinding area when high speed grinding all is accelerated greatly with the feed speed of workpiece, add meet an emergency to lead the impact of response temperature lag, can make temperature of workpiece surface grinding is reduced somewhat, can cross the region of incidental grinding burn consequently, thereby great and patulous the applied limits of grinding craft parameter. Pursue graph of 1 principle of sudden drop grinding pursues emery wheel of 2 treatment of sudden drop grinding and workpiece contact diagram pursue 3 high accuracy essence press columnar slideway to pursue 4 emery wheel and system of grinding juice supply pursue 5 emery wheel located the system pursues at 3 o'clock methods of 6 sudden drop grinding machine main shaft to pursue methods of 7 sudden drop grinding, high speed grinding has the following characteristic: Manufacturing efficiency is tall. Because the number wearing bead of the action inside unit time increases, make material is ground increase except rate twice, highest can amount to 2000mm3/mm · S; , can raise 30% ~ than common grinding 100% . Emery wheel service life is long. Because every grind the bear of bead to reduce, time of the grinding that wear bead is lengthened accordingly, improved emery wheel service life. When grinding power is certain, the life of 200m/s grinding emery wheel is 2 times of 80m/s grinding; When grinding efficiency is certain, 7 the life of 200m/s grinding emery wheel is 80m/s grinding.

8 times. This special be helpful for implementing grinding automation. Grinding surface surface roughness is worth low. Exceed high speed grinding individual the cutting ply decrescent that wears bead, grinding nick is shallow, height of exterior plasticity apophysis is reduced, numerical value of exterior surface roughness is reduced; Because exceed the extremely tall meet an emergency of material of high speed grinding,lead at the same time (can amount to 10-4 ~ 10-6s-1) , grind bits to cut position in heat insulation next formation, material purify mechanism produces change, because this can realize the high-powered treatment of pair of brittleness and difficult treatment material. Grinding force and workpiece suffer force to be out of shape small, workpiece treatment precision is tall. Because cutting ply is small, the law is reduced accordingly to grinding force Fn, be helpful for stiffness thereby of precision of poorer work treatment rise. When cutting close look to be the same as, force of the grinding when the grinding force when grinding of grinding speed 250m/s compares grinding speed 180m/s reduces nearly one times. Grinding temperature is low. The grinding in exceeding high speed grinding heats up the rate that passes into workpiece to reduce, make thermal drop of workpiece surface grinding small, can cross the region of incidental fire damage, degenerative layer decreases be heated getting power thin, have better exterior integrality. Steel of grinding of high speed of 200m/s of use CBN emery wheel deepness of layer of exterior remains stress is not worth 10m. Expanded ground of grinding craft parameter uses range greatly thereby. Make full use of and developed the exceedingly good property of the tall hardness that exceeds hard abrasive and tall wearability. Eletroplate to exceed hard abrasive emery wheel is first selection of high speed grinding to grind with monolayer of drill rod solder. Especially emery wheel of bond of metal of solder of high temperature drill rod, grinding force and temperature are lower, it is current high speed grinding is new-style emery wheel. Have tremendous economic effect and social effect, have capacious green character. Treatment of high speed grinding shortens effectively handling time, improve labor productivity, those who reduce the sources of energy use up the pollution with noise. In treatment of high speed grinding, emery wheel wears away reduce, service life is long, make finished cost is reduced, resource gets be usinged effectively. Because efficiency of high speed grinding is tall, can cancel or replace dig, mill, car to machine, decreased to machine the investment of working procedure, equipment and personnel thereby, reduced resource, the sources of energy and staff use up, the green that realizes workmanship is characteristic. Because the place of the 70% bits that be ground of heat of high speed grinding is taken away, the temperature that machines the surface so is relatively low, the flow that needs grinding fluid and pressure can decrease relatively, the demand of refrigerative fluid decreases, energy demand decreases, pollution decreases. Round grinding raises emery wheel speed to conduce to outside the high speed of treatment of high speed grinding of engine crankshaft camshaft reduce grinding surface surface roughness, can come true efficient grinding of high speed nicety. Round grinding is the emery wheel Zhou Su that uses 80 ~ 200m/s and above and CBN emery wheel outside high speed, deserve to be mixed with high-powered CNC system orgnaization of high accuracy small feed, to camshaft (graph 1) , crankshaft (the method that round circumgyrate surface has grinding machines high speed nicety outside the spare parts such as graph 2) . It can assure tall treatment precision namely, can achieve tall treatment efficiency again. This one technology applies successfully already at auto industry branch in Japan. For example, cylindrical grinder of high speed of company limited GCH63B CNC comes to machine of work of use abundant field the camshaft of nodular cast iron that grinding mental allowance amounts to 5mm, grind except rate can amount to 174mm3/mm · S, grinding comparing can amount to emery wheel 33500. It is upper limit with Rz=3m of exterior surface roughness, emery wheel passes nap but successive grinding 60 workpiece, the surface after grinding presents remains to press stress, can grind directly from semifinished product for finished product, leave out the have enough to meet need between lathe work foreword and working procedure. Cylindrical grinder of high speed of GZ0 of machine of abundant field work CNC equiped bearing of Toyoda State Bearing, what the chip CBN emery wheel that uses 200 M/s undertakes to swing tower spare parts grinding of one-time fore-and-aft contrail completes whole work is flexible treatment. These manage to production and reduce cost to all have important sense. On cylindrical grinder of high speed of RB625 of company of German Guhring Automation, use CBN emery wheel, also but semifinished product wear main shaft, minutely can grind except 2kg metal. Grinding of high speed nicety is to use grinding machine of high speed nicety, pass accurate nap imperceptible abrasive is ground, use inferior micron class cuts deep He Jie to machine an environment to obtain completely inferior the dimension precision under micron class. Sudden drop grinding nods grinding to use metallic bond to exceed hard abrasive commonly quickly (CBN or making synthetic diamond) ultrathin emery wheel, the diameter is 300 ~ 400mm commonly, width is 4 ~ 6mm, ply of radial abrasive layer is 5mm. Junker company nodded grinding machine tool to use multinomial and patent technology quickly, if emery wheel located at 3 o'clock,electron of installation system and online nap system, grinding spindle balances automation system to wait. X direction uses high accuracy static press columnar slideway technology (graph 3) , cut feed accurately in order to raise damp and steadily implementation micron level. Z direction (fore-and-aft) feed is used contain beforehand laden ball guide screw and plane / slideway of V form coating. The machine tool deserves to system of supply of double nozzle of high-pressured grinding fluid waits, in order to assure the treatment function of the machine tool and treatment precision. Graph 4 reach unit of supply of grinding fluid double nozzle for emery wheel. Sudden drop grinding uses what ply is 4 ~ 6mm to exceed hard abrasive thin emery wheel, use " fixed position installed a system at 3 o'clock " patent technology is installed quickly, repeat fixed position precision tall, can solve what cause from mental efforts to go up aperture problem. Emery wheel uses Junker company patent technology in the installation on main shaft " fixed position installed a system at 3 o'clock " finish quickly, repeat fixed position precision tall, the emery wheel aperture that can compensate high speed to fall from mental efforts action goes up big, if pursue,5 are shown. When grinding spindle photograph when anticlockwise to emery wheel roll, 3 cylinder of cloth of the Kong Jun inside the cycloidal outline cant of on body of main shaft star 3 Duan Jun cloth and emery wheel are contacted cheek by jowl, realize the fixed position in arenaceous wheel pair, next by bolt general emery wheel and locking of end panel of main shaft flange. Change when need when emery wheel, need only emery wheel anticlockwise rotate 30 ° , can make emery wheel and main shaft detached, change quickly thereby emery wheel, make change top time is less than 2min, change emery wheel time to be less than 20min. Produce unripe vibration to because emery wheel high speed rotates,be controlled, assure to acquire high exterior quality, in emery wheel every time nap and dynamic balancing should undertake after changing, the electronic self-poise system that the machine tool of sudden drop grinding of Junker company carries a department in main shaft through installation finishs emery wheel automatically online dynamic balancing, emery wheel radial is jumpy precision is controallable in 0.

002 Mm less than. Because emery wheel is paper-thin, dropped emery wheel weight and lopsided degree, also make wrap the air current pressure that is added in periphery of high speed emery wheel to be reduced greatly, the whirl that reduced high speed emery wheel obstruction, and can grinding is common emery wheel cannot the stricture of grinding face and section dimension change are bigger model face. High speed nods speed of grinding emery wheel to be able to amount to 90 ~ 160m/s. Grind high to obtain except rate, do not make emery wheel generation too large at the same time leave mental efforts and happen destroy, workpiece also high speed rotates, be in normally 1000r/min above, highest can amount to 12000r/min. Because this receives the actual grinding that hits bit of point,speed should be emery wheel and workpiece the overlay of both linear velocity, be close to 200m/s, in order to realize the purify of the material below rate of taller meet an emergency. Because the car grinds working procedure to incorporate, to assure the exterior quality of workpiece, radial is cut mix greatly the fore-and-aft feed rate of edge X axis is average very small, when camshaft of the grinding that be like a dot, fore-and-aft feed speed is in commonly 0.

01 ~ 2mm/s, radial is cut deep 0.

002 ~ 0.

2mm. With main shaft of grinding of method of sudden drop grinding (graph 6) , hold clip achievable outside shoulder of round, axis, groove and close solid whorl the grinding of 4 place; Grind camshaft (graph 7) , hold clip but journal of grinding cam face, main shaft, two upright journal, stop push face of journal side shoulder and cam to adjust seat surface external diameter, dimension precision achieves IT6, ra ≤ 0.

8µm, periodic time 150s, compare with conventional technology, big political integrity restricted cost (on watch) . Limited company of one steam masses car applies camshaft of engine of grinding of this one technology (graph 8) , 4300r/min of emery wheel rotate speed, emery wheel nap but grinding 3000. Numerical control nods grinding quickly also is the development way that uses half permanent tool to undertake CNC Turning. As a result of grinding temperature low, abrasive and the sources of energy are used up little, technology of sudden drop grinding also accords with green to create a demand, can predict technology of this new-style grinding has huge to expand latent capacity. Purify of material of grinding of sudden drop grinding basically relies on emery wheel side to finish, and periphery removes light to grind action only. Accordingly, emery wheel is circumferential wear away extremely slow, service life is long (the longest can amount to 1 year of) , grinding comparing can amount to 16000 ~ 60000, one sudden drop grinds emery wheel but abrasion counts ton of steel, rate of emery wheel nap is low (every time nap can machine 2 × ) of 105 spare partses, manufacturing efficiency raises 6 times than common grinding. This shows, technology of sudden drop grinding is equivalent to using half permanent tool to undertake numerical control the car is adjusted and be machined, accord with the development trend of advanced production technology, also accord with the demand that green creates, because this grinding is new,the technology has development latent capacity extremely. Production company of individual car of conclusion our country introduced equipment of high speed grinding to be used at the car to start crankshaft at present kind the treatment of the spare parts (basically be) of treatment of engine camshaft, crankshaft, gained apparent benefit. But applied domain is very small, the complete set equipment that machines with respect to onefold spare parts only and craft are broken by foreign ridge in a field custom-built, spot treatment just finishs fixed unit operation of cargo handling by the worker, full treatment process is finished automatically by CNC control; Emery wheel nap just also undertakes according to treatment work measure of the regulation, and take no account of use a situation actually. Producing what the workshop faces is " black box " technology. The enterprise did not master its core technology and craft theory truly, also cannot undertake its craft parameter design and technology of process designing of development numerical control, cannot emery wheel of production of form a complete set reachs his relevant accessory. All craft and equipment all rely on an entrance. Accordingly, dog international advanced technique, begin the theory of technology of high speed grinding and applied research deep, be popularized to be in our country and develop it is this advanced technique, important to raise workmanship technology and equipment to make a level have meaning. CNC Milling CNC Machining