Position error of grinding of journal of crankshaft connecting rod is analysed

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Summary: Brief introducing the principle of grinding of journal of crankshaft connecting rod, the formation of phenomenon of common to its position error the reason undertook detailed analysis, put forward corresponding countermeasure and settle way. 1 introductive crankshaft is the core spare parts of engine, its machine precision and treatment difficulty to be in engine the first of all in 5 large parts. Journal of crankshaft connecting rod (neck of abduct of the following abbreviation) join with connecting rod photograph in engine, bear directly all sorts of hand in complexly change load, between journal and plain bearing liner be in high speed for a long time opposite movement condition, because this is right,precision of the appearance of treatment abduct neck, position and exterior surface roughness have very firm demand. In the whole process that machines in crankshaft machine, the foreword of grinding work of essence of life of connecting rod neck is the the most important, most crucial, the treatment quality of this line working procedure is having the effect that hold the balance to quality of crankshaft finished product. Abduct neck grinding is a complex process, demand of equipment precision level is high, adjust safeguard to safeguard difficulty big, production is stronger to timeliness requirement, to all sorts of limitation that produce in treatment and deviation, requirement craft and Electromechanical maintenance technician have stronger processing capacity, should judge the account that the problem arises quite in time, can adopt corresponding settlement measure. Pass old job to carry out, preliminary summary gave the writer a few rules, here stresses the grinding principle that introduces abduct neck, to a few of respect of position error of abduct neck grinding common problem undertakes an analysis, offer corresponding judgement and means of settlement, consult for everybody. The following content all is with treatment of BJ2021 I-4 crankshaft exemple. Graph 1 it is process chart of grinding of neck of abduct of BJ2021 I-4 crankshaft. Among them M1, M2, M3, M4, M5 gives priority to journal, it is crankshaft when the job rotates prop up and centre of turning circle, p1 of connecting rod neck, P2, P3, P4 rotates around main shaft neck, piston and connecting rod drive abduct neck to change linear campaign into circular motion, output motivation for engine. P1, P4 is on same axes, p2, P3 is on another axes, both differs 180 ° . Graph the norms size of 1 crankshaft somewhat difference, but the grinding principle of abduct neck and method are basic and same. What grinding of neck of abduct of BJ2021 I-4 crankshaft uses is the grinder of German NAXOS-unio and company of British BUTLER NEWALL, orientation way is same, both all is to use prejudicial clamping apparatus, semicircle hard alloy covers with tiles radial of a M1 of neck of the main shaft that prop up, M5 locates, the graduation on dividing head is sold extend crankshaft of the drive that sell aperture to finish 180 ° to retroflexion make horn decides to essence of life, part grinding P1, P4 or P2, P3. Axial uses MARPOSS to be opposite in implement, measure sidewall place, surplus of sidewall of neck of abduct of automatic equal apportionment undertakes axial locates. Grinding process is executed measure actively. 2 abduct neck slants grind and error of music abduct radius is in actual grinding process, undertake in kibble end half essence, essence is ground sometimes when, MARPOSS active measurement unit begins the work (measure a head to examine journal, the edge grinds an edge to measure, automatic closed-loop control) when, line out of indication screen glazing shows numerical value acuteness twinkle, grind end to essence of life paragraph grind level to just be stabilized without scintilla even. At this moment, the crankshaft that has ground provides position of neck of aspirant travel abduct to spend in integrated check when detecting, (Sell M1 of neck of aperture, main shaft, M5 to be with graduation commonly measure fiducial) the abduct neck that shows on meeting occurrence dial gauge is actual positional measured value and its are worth theoretically (the dial gauge when detecting is in appearance this value is opposite admiral 0) had differred big (0.

25mm above) , namely the circle outside abduct neck each direction are inhomogenous, produce prejudicial grinding, extreme circumstance falls to exceed grinding surplus range even, cause some angle limits inside outside the circle is not ground, appear " black skin " phenomenon. Such emery wheel can appear discontinuous grinding, the machine tool is in abnormal job status. And the journal surface of out of round of the park that measure a head keeps arising swing and oscillatory, cause the damage that measure a head easily, the influence is measured and machine precision. By the graph 2 can see slant grind or " black skin " form a reason. Neck of the abduct when grinding centre of turning circle namely the centre of turning circle of head rear push frame, it is a fixed axes line, and the abduct neck before grinding also has an axes line, good working position is coincide of the both after holding card, grinding surplus just is met even. Actually, wear away as a result of clamping apparatus or other reason, the line of abduct neck axes after can causing outfit check and line of its centre of turning circle not coincide, the likelihood appears a deflection measures E. Graph 2 in diameter of neck of the abduct before D0 is grinding, d is the diameter after grinding, the circle outside neck of the abduct after F is theoretic grinding comes to did not grind the circle outside the part in radius direction the largest space pursues for F=e-(d0-d)/2 2 graphs 3 when F<0, namely when E<(d0-d)/2, can wear neck of a whole turn is circumferential, but the likelihood has slant grind a phenomenon. When F=0, namely when E=(d0-d)/2, be in critical condition, abduct neck can just wear complete and circumferential. When F<0, namely when E<(d0-d)/2, criterion cannot enough wear neck of a whole turn is circumferential. Optimal condition is E=0, namely centre of turning circle and coincide of abduct neck center. Slant grind or " black skin " appear in different position, form a reason to be distinguished somewhat. Like graph 3(crankshaft of all side view all is initiative outfit to block the position, as a child the head looks) be shown. Slant grind or " black skin " when appearing in A(B) of abduct neck surface to be in, because graduation fixed position sells the position,basically be improper, horn to deviate former, make horn of edge of center of neck of the abduct when fixed position to (left, right) deflection, when bringing about this center and grinding thereby its centre of turning circle not coincide. When be being adjusted actually, can touch dial gauge the head to rely on in lozenge graduation fixed position to sell face of lateral circular arc to go up, according to the quantity of abduct neck deflection of actual measurement, suitable (go against) hour hand adjusts fixed position to sell the position, make abduct neck and its centre of turning circle tend consistent. If blemish appears when C(D) is in, the semicircle that is neck of the main shaft that prop up is made of baked clay height has a problem, make center of neck of the abduct when holding card is on perpendicular direction deviate its grinding centre of turning circle. Can cover with tiles through adjusting corrective semicircle a position on perpendicular direction, make two centers restore to agree. Music abduct radius is line of axes of neck pointing to abduct the distance to space of axes of main shaft neck. Dimension of this line working procedure asks 40.

499.

0.

063mm, exceed this limits to be able to affect piston route, produce undesirable effect to the working status of engine then. The reason of out of tolerance of music abduct radius and C, D slants the argument that grind is same, can adopt same way to adjust processing, repeat no longer here. 3 graduation error the grinding order of each journal is P4-P1-P2-P3. Grind P4, P1 first, loosen next clip, the lozenge graduation that goes up by dividing head sells drive crankshaft to retroflexion 180 ° , position of grinding of park of P2, P3, clamp grinding. The graduation error of abduct neck is the error that shows relative position is spent between P2, P3, P4 and P1. This working procedure is 0.

36mm. Because P1, P4 is same axes to hold card, p2, P3 holds card 2 times for another axes, the odds that bigger error presents between P2, P3 is reached between P1, P4 very small. P1, P4 and P2, P3 basically discusses here the error of position of actual on 180 ° direction graduation and academic position. When actual measurement, locate with radial of M1, M5, graduation sells Kong Jiao to fixed position, measure P1 place with dial gauge first and set for null, next crankshaft retroflexions 180 ° , same position measures neck of abduct of P2, P3, show numerical value is graduation error on dial gauge. When the watch of dial gauge the needle is in " one " when direction loses a value, abduct neck is in converse deflection position, line of abduct neck axes is nodded in H (graph 4) , t value is graduation error value namely () of dial gauge reading. After be being ground as a result of P1, P4, suitable hour hand of index plate of motion of unit of dividing head hydraulic pressure rotates 180 ° , rely on on pawl to locate instead, graduation sells drive crankshaft to also should turn same point of view, at this moment good position P2, P3 should be in E of below grinding position, p1, P4 should be in main shaft neck place of upper part F, namely of F of center of main shaft neck, abduct neck, J get on even the line. Actually, the B angle that index plate has turned is not worth 180 ° , graduation does not reach the designated position, the abduct neck that brings about grinding produces same error. The cause that causes apparently is because of face of the fixed position on index plate M place wears away or N is in tower above (graph 5) , the correct square law of the error is index plate M place is added fill up or repair in N place grind. Add mat carry out rise have difficulty, it is commonly tear open index plate next is in on grinder to undertake repairing grinding to N face. The radius that is in because of index plate M, N and abduct neck radius (abduct neck center is apart from to center of main shaft neck) dimension close, so M wears away value and numerical value of abduct neck deviation also answer approximate. Can repair by the deviation reading of the dial gauge when measuring grind. Make M and N maintain 180 ° graduation. If appear,arrange to deviation, behave form and converse deviation as it happens contrary, can undertake adjustment through nap M face. Graph 4 graphs 5 graphs the parallelism that the parallelism here is neck of crankshaft main shaft and space of abduct neck axes, this working procedure public errand asks to be 0.

0064mm, it is an extremely strict project (need to measure) on ADECOLE measuring instrument. And improper of clamping apparatus of fixed position of main shaft neck can cause abduct neck parallelism alignment error, its behave means to see a picture 6. If locate after clamp, m1, M5 is opposite to photograph of grinding centre of turning circle the position is abhorrent, namely semicircle of M1, M5 is made of baked clay in twist of horizontal way amlposition, differ in discretion of perpendicular direction position, can produce this kind of situation. Corrective method is to use the straight appearance bar with a diameter and main shaft same neck (length and crankshaft close) , clamp covers with tiles in M1, M5 on, suck dial gauge position is secured in the machine tool, of the watch touch a head to be hit in shape fine face, can make a list respectively in the generatrix on appearance club and side generatrix, along shuttle table of direction of appearance marvellous generatrix, the reading that observes a watch changes, adjust M1, M5 to cover with tiles repeatedly in position of level, perpendicular direction, make in appearance club the reading that expresses inside full-length limits tends consistent. In front enumerated all sorts of errors do not exist alone certainly, it is cross correlation across appears likely very. Graduation error is brought about likely also greatly too slant grind or " black skin " , parallelism is improper the error that also can cause music abduct radius. CNC Milling CNC Machining