Crankshaft stops analysis of craft of burn of the grinding that choose a side
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04, to photograph adjacent the round jumpy public errand of two journal is 0.
02; Stop the width that turn a neck is 260+0.
05mm; Stop push opposite side to ask to be opposite the jumpy public errand of common spool thread 0.
02, verticality public errand 0.
01, flatness public errand 0.
013; Stop the protruding outside pushing right side to ask flatness public errand asks does not exceed 0.
005, inside sunken do not exceed 0.
01; Stop push Rz1 of journal surface surface roughness.
5 μ M, stop M of μ of Rz3 of surface roughness of the surface that choose a side, stop the diameter that turns journal is φ 50mm, stop the external diameter that choose a side is φ 85mm, its area is as high as odd side 3 848mm2. Below large quantities of conditions that estimate production, want to stop choose a side (include to stop turn journal) achieve so tall precision, sheet relies on common grinding craft is very difficult implementation, should use the grinding of numerical control grinder of high accuracy, and use a series of severe measure ability satisfies blueprint to ask. My company is in crankshaft treatment process, came up against stop burn of the grinding that choose a side such treatment blemish, although each field size and appearance position public errand achieved blueprint requirement, but crankshaft stops blemish of the burn that choose a side is solved hard from beginning to end however. Pass investigation and study, we from theory and practice two respects undertake tackling key problem, solved this problem finally. The physical machinery property that quality of surface of grinding burn grinding includes grinding surface surface roughness and grinding surface layer two respects. Because grinding adds man-hour to grind bead to include to slip to the action of workpiece,brush, score and cutting, and great majority wears bead be the horn before losing is mixed small hind horn, it is so in whole grinding process, the grinding with meeting many generation is hot, make the instantaneous temperature of grinding area can amount to left and right sides of 1 000 ℃ . So high temperature can make the metallographic organization of workpiece surface layer produces change, cause grinding burn. Grinding burn can destroy crankshaft to stop organization of metallographic of the surface layer that choose a side, make strength of surface layer metal and hardness are reduced, accompany have leftover stress generation, appear even microcosmic crackle, and make workpiece surface quality exasperate, affect crankshaft to stop severely the wearability that chooses a side and service life. Burn of this kind of grinding is in arenaceous belt when polishing cannot purify, because this must avoid grinding burn. Quench in grinding steel crankshaft stops when choosing a side, the possibility arises the following 3 kinds of burn: 1.
If the temperature of grinding area did not quench the photograph of steel changes more than,answer igneous burn temperature, but the transition temperature that already exceeded martensite, stop the temper martensite organization of metal of the surface layer that choose a side becomes change the temper with inferior hardness to organize (body of all alone family name or the body that ask a family name) , this kind of burn calls temper burn. 2.
If area temperature exceeded grinding to change,baked wheaten cake of temper by dipping in water is hurt temperature, plus the urgent cold action of cooling fluid, surface layer metal happens 2 times to quench, make surface layer metal appears 2 times to quench martensite is organized, what its hardness compares original temper martensite is tall, in its lower level, because refrigeration is slower, appeared the temper with lower than former temper martensite hardness is organized (body of all alone family name or the body that ask a family name) , this kind of burn calls baked wheaten cake of temper by dipping in water to hurt. 3.
If area temperature exceeded grinding to change,retreat igneous burn temperature, and grinding area is entered without cooling fluid again, surface layer metal will produce anneal organization, exterior hardness will drop quickly, this kind of burn calls anneal burn. In crankshaft figuration grinding, belong to this kind of burn more. The way grinding heat that improves grinding burn is the source that creates grinding burn, reason improves grinding burn to have two ways: It is the generation that reduces grinding heat as far as possible; 2 it is to improve cooling condition, the quantity of heat that makes arise as far as possible is little pass into workpiece. 1.
Have heavy the crankshaft that cuts groove stops push journal to be in graph 2 in, crankshaft stops push journal to have deeper heavy cut groove, and heavy cut groove to already was in working procedure treatment is good before, when grinding need not grinding is heavy cut groove, need grinding to stop only push journal stops with two choose a side. Below this kind of circumstance, even if grinding of use figuration emery wheel, should use parameter of good emery wheel of puissant refrigeration, reasonable grinding surplus and choice only, can avoid the occurrence of grinding burn blemish usually. Using narrow emery wheel grinding stops when turning journal, adoptable plan is: Adjust the angle grinding of program and emery wheel, make emery wheel from journal on the right side of with inclined cut means to enter, grinding comes requirement measure, exit along former angle square syncline quickly again; Make emery wheel from journal left with inclined cut means to enter, grinding comes requirement measure, exit along former angle square syncline quickly again; Make emery wheel comes from the intermediate fast infeed grinding of journal requirement measure, exit quickly again. When afore-mentioned grinding, want to apply puissant refrigeration. So far, stop push journal and two flank grinding to end. Graph 2 crankshaft stop push journal to contain heavy cut groove 2.
Without heavy the crankshaft that cuts groove stops turn journal the graph shows crankshaft 3 times to stop push journal to not have heavy cut groove, grinding needs to stop when grinding push journal stops with two choose a side, still have two figuration round part additionally. Below this kind of circumstance, even if use narrow emery wheel grinding, use puissant refrigeration, avoid the occurrence of grinding burn blemish very hard also. Kind of grinding means divides to divide below narrate a solution: Graph 3 crankshaft stop push journal to be not taken heavy cut groove (1) figuration grinding. In figuration grinding, the main reason that its produce burn is grinding heat is many the anneal burn that accumulate and causes, anneal burn causes crankshaft to stop the hardness that choose a side drops, surface layer produces anneal organization, stop the wearability that chooses a side becomes poor, affect the moving stability of engine badly. Cause the main factor of burn according to its, we part from 3 respects proceed with: The grinding surplus with the emery wheel with right choice, logical choice and improvement are cooling condition. ① chooses right emery wheel. Quench steel crankshaft stops the hardness that choose a side tall, area is large, arenaceous bead is ground easily blunt. Grind to avoid arenaceous bead blunt and generation is many grinding is hot, appropriate of emery wheel hardness is chosen some softer, so that grind blunt arenaceous bead to fall off in time, hold emery wheel from acute sex. The emery wheel stoma with softer organization is much, can accommodate among them cut bits, avoid emery wheel to jam, can enter cooling fluid or air area grinding area again, make grinding area thermal drop small thereby. In make sure crankshaft stops below the premise that the surface roughness that choose a side asks, appropriate chooses the emery wheel of thicker granuality, in order to achieve higher purify rate; Additional, emery wheel must be balanced subtly, so that good balance position is in when emery wheel job; Emery wheel must seasonable nap in order to maintain its sharp; Frequency of nap of influence emery wheel second the element is very much, those who include the purity of the material that be ground and type, cooling fluid is clean degree wait; The diamond pedestal of nap emery wheel must firm, if diamond has 0 apparently.
5 ～ 0.
The wear extent of 6mm, mark diamond already was ground blunt, answer to change in time; Control the clearance of system of emery wheel transmission and emery wheel arbor strictly; Emery wheel drive takes degree of tightness to adjust appropriate. ② chooses reasonable grinding surplus and grinding parameter. In producing practice, often be versed in in order to rise a speed, reduce radial feed to reduce workpiece surface burn and crackle. Have a kind of experience for 0.
1mm filing, 0 what machine finally namely.
In 1mm surplus, drop off feed, the appearance that can produce before take out two times in grinding journey injures a layer, in order to reduce grinding burn. According to above theory, we use crankshaft to stop in producing practice push grinding of journal multitask foreword, cent is ground for kibble, half essence and static grind wait for working procedure. After passing multitask foreword grinding, crankshaft stops push journal diameter surplus for 0.
15 ～ 0.
25mm, stop surplus of the unilateral that choose a side is 0.
04 ～ 0.
07mm, figuration grinding deserves to wait for measure with puissant refrigeration again, can avoid the generation of burn blemish effectively. Be worth what carry is, choose reasonable grinding surplus, still can push figure of occurrence horn mouth with preventing to stop (because prevent burn, choose softer emery wheel commonly, surplus is too large, grind bead to fall off relatively piece, appear easily cone) . ③ improves cooling condition, carry out puissant refrigeration. Cooling fluid must effective and sufficient, cooling fluid must gush arrives grinding area; Discharge is 40 ～ 45L/min commonly, in order to realize sufficient refrigeration; Pressure is commonly 0.
8 ～ 1.
2N/mm2, go to those who be stuck on emery wheel in order to rush cutting bits; Those who maintain cooling fluid is pure, appropriate ground filters, with cleared cooling fluid cut bits, wear the dirty thing such as bead; The container of cooling fluid wants enough big, lest mix into has entered much gas or bubble; The temperature that prevents cooling fluid lifts quickly or reduce, control the room temperature of the cubage of cooling system and workshop commonly, control the temperature of cooling fluid with respect to enough, be in however special store besides below ought to use radiator. (2) narrow emery wheel grinding (emery wheel width under stop push journal archives broad measure) . Using narrow in emery wheel grinding, figuration grinding uses defend burn measure all applicable is planted hereat methodological grinding, just narrow emery wheel grinding can have more choices on means of emery wheel feed. One kind is radial cuts law grinding, if this kind of grinding is adjusted undeserved the horn mouth appearance that can create preamble place to narrate; Another kind is inclined cut means grinding, the first pace, make emery wheel from journal on the right side of with inclined cut means to enter, grinding comes requirement measure, exit along former angle square syncline quickly again; The 2nd pace, make emery wheel from journal left with inclined cut means to enter, grinding comes requirement measure, exit along former angle square syncline quickly again; The 3rd pace, make emery wheel comes from the intermediate fast infeed grinding of journal requirement measure, roll out quickly again. Surplus of grinding of its working procedure and cooling means and figuration grinding use consistent parameter. The last word is on the foundation that draws lessons from domestic and international relevant data, practice of article union production puts forward to understand definitely crankshaft stops the method of burn of the grinding that choose a side, to improving product quality, optimize craft parameter to have certain help. CNC Milling