The cam when camshaft grinder grinding turns gearshift rule studies

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  • source:FARSUN CNC Machining
Home uses having grinder of camshaft of profiling numerical control is costly entrance equipment almost. The cam outline grinding that fast control leaves the numerical control system that the article developed the grinding machine of numerical control camshaft that is control equipment with the PC and software and constant line machines data processing method. Cam grinding is the special grinding that be not a circle. When grinding, besides dispenses of basic circle ministry round grinding machines a state identical, the grinding condition of other part all produces change ceaselessly. Above all, because cam curve is,become by a few kinds of simple or complex curve joining together, bring about cam outline to form campaign thereby discontinuous, speed, acceleration " dash forward jump " acuteness. Next, by the instantaneous career that grinding chooses, the osculatory arc length of emery wheel and workpiece and the appearance that grinding dot all follows cam curve relative to the polar coordinates position at cam center change, make grinding force, emery wheel - the flexibility of workpiece system is out of shape, grinding quantity of heat also produce change ceaselessly. For this, adopt following technology measure. 1) grinding machines the data processing in the process to all use batten function 3 times to plan to close. 3 times batten function can maintain each model the place that be worth a dot one, 2 rank derivative is successive, each model the value nods a flowing join, make cam rises Cheng curve thereby successive and flowing change, the speed in grinding process, acceleration makes the same score glide to cross. 2) uses gearshift constant to grind except rate control. Make workpiece is in in different grinding point, workpiece rotate speed is different, grinding nods the linear velocity that is in cam outline to keep basically changeless, in order to make sure the process in grinding cam a week is medium, the metal is ground except rate is basic keep changeless, grinding force change is not big, reduce the exterior ripple of cam outline and burn. 3) uses software to compensate a technology. One, before current model machines the maths of linkage coordinate, by conventional input cam number of axle is occupied (camshaft dimension, cam data of number, watch rising Cheng) , cam processes data (feed of grinding surplus, grinding) , emery wheel data (time-interval of nap of quantity of emery wheel nap, emery wheel) , parameter of machine tool system, computation gives the real profile coordinate of cam, grinding to machine linkage coordinate, undertake constant is ground then except rate processing, pass batten function interpolation 3 times, the pulse that interpolation gives of number and servo of pulse frequency input accuse board, and drive servo electric machinery moves, achieve X-C linkage. The machine tool uses form of X-C2 axis linkage to produce cam outline curve, by the polar coordinates of cam real profile nap of radius of value, emery wheel, emery wheel is measured, the maths that the parameter such as grinding feed decides X-C linkage coordinate is general model. 2, model of maths of coordinate of the linkage below fast control condition is in constant line when C axis undertakes grinding with constant rotate speed, because cam outline promotes the constant change of Cheng, the linear velocity that cam outline nods each also changes ceaselessly, those who cause grinding is inhomogenous, the metal in grinding process is ground except rate as change of curve of cam outline face change, cause surface wave of burn, cam to spend thereby. The metabolic rule inside grinding cam a week: Press " basic circle, rise Cheng, peach is pointed, very round, return trip, basic circle " ordinal metal is ground except rate change. Cam width B and grinding deepness Ap all can consider as one changeless quantity, the ω of V of instantaneous linear velocity that dot of reason cam grinding is in decides to grind except rate. Want to control C axis rotate speed only, make V ω is one constant value, can realize constant to grind except rate grinding. CNC Milling