Error of circumgyrate of machine tool main shaft machines the influence of precision to the spare parts
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source:ACHER CNC Machining
Main shaft of 0 foreword machine tool is a on the machine tool main part, because machine tool main shaft is used at installing cutting tool or workpiece, because this photograph that it is cutting tool or workpiece is contrapuntal buy is fiducial with motion fiducial. Precision of circumgyrate of machine tool main shaft is one of main precision index of the machine tool, affecting surface roughness of the surface that be reached by the treatment precision of treatment spare parts directly. The circumgyrate error of machine tool main shaft is an omnibus error, it is main shaft axes of actual in circumgyrate process circumgyrate is opposite the drift at academic circumgyrate axes. The circumgyrate error of machine tool main shaft can divide for 3 kinds of basic forms: The pure axial change of jumpy, main shaft moves the pure radial of main shaft and pure angle swings. Usually, the error of these 3 kinds of basic forms exists at the same time, the machining error of generation also is the overlay that error of 3 kinds of forms affects. The error of main shaft circumgyrate of different form is different to machining the influence of precision, the influence that the error of main shaft circumgyrate of same form machines a method to differring also is different. Pure radial of main analysis main shaft beats below the influence that machines to the spare parts. Pure radial of 1 main shaft beats the pure radial of reason main shaft of generation beats is to show main shaft is actual the revolution motion that rotor line circles average axes to make parallel. Causing the main reason with main shaft pure jumpy radial is the precision error of main shaft journal and bearing. The bearing component that uses on the machine tool is sliding bearing and scroll bearing two kinds, the type of bearing is different, jumpy to pure radial influence also is different. The influence that uses sliding bearing to beat to main shaft pure radial ( of of of of of of of of of of A) (B) pursues the main shaft when 1 turning and boring is jumpy when using sliding bearing to make bearing, main shaft rotates inside bearing aperture with its journal. To lathe kind machine tool, in machining a process, the direction getting power of main shaft is certain, main shaft journal is pressed to the fixed place of bearing aperture surface by cutting force. At this moment the some inside the different position of main shaft journal and bearing aperture secures place to connect touch, so the circularity error of journal can make main shaft circumgyrate produces pure radial to beat, and the appearance error of bearing aperture is very small to the influence of precision of main shaft circumgyrate. If pursue,1(a) place is shown. To boring machine kind machine tool, action is in the cutting force on main shaft is along with the whirl of boring cutter roll, the different position that the some on journal secures place and bearing aperture surface is conterminous touch, because the circularity error of this bearing aperture is met,the pure radial that causes boring machine main shaft beats, and error of appearance of journal of boring machine main shaft is not big to the influence of precision of main shaft circumgyrate, if pursue,1(b) place is shown. When the influence main shaft that uses scroll bearing to beat to main shaft pure radial uses scroll bearing to make bearing, the element that causes main shaft pure radial to beat outside the precision besides bearing itself, still cooperate with bearing photograph precision is concerned. (A) aperture and raceway are not coaxial (B) raceway out of round pursues the raceway appearance precision of the outer lane of influence scroll bearing of appearance of the outer shroud inside 2 scroll bearing and precision of bearing of position error scroll and inner ring and positional precision are pure to main shaft radial and jumpy influence and sliding bearing. If pursue,2 are shown. When turning, the precision impact of inner ring raceway is bigger; When boring, the precision impact of outer lane raceway is bigger. The pure radial that </DIV> rolls the abhorrent meeting of the dimension of appearance sum of errors of body causes main shaft is jumpy. If pursue,3 are shown. When the diameter larger scroll put oneself in another's position is located in when left, can make inner ring right move, namely main shaft place is right move: Contrary, when the diameter larger scroll put oneself in another's position is located in when right, can make inner ring position different move, namely main shaft position is different move. The rotate speed as a result of scroll body cage the rotate speed under inner ring, accordingly, the pure radial and jumpy frequency that it causes is inferior. Graph the dimension of appearance sum of errors of body of scroll of 3 scroll bearing is abhorrent pure to main shaft radial the jumpy space that affects scroll bearing beats to the pure radial of main shaft also is influential. If pursue,4 are shown. Set bearing bear the weight of the area is in right, at this moment inner ring is right move, when scroll body is located in when horizontal position, of inner ring right move the quantity is absent than scroll body when horizontal position should small, make main shaft produces pure radial to beat, the frequency with this kind of pure jumpy radial wants to be gotten high than the rotate speed of inner ring much. Cooperate with scroll bearing photograph influence bearing inner ring is Bao Bi spare parts, suffer force hind to be out of shape very easily, the pure radial that the circularity error of main shaft journal will bring about inner ring to be out of shape and causes main shaft is jumpy. Manage together, bearing outer lane also is thin wall spare parts, after installing casing Kong Zhong, the circularity error of casing aperture also will cause generation of outer lane raceway to be out of shape, the pure radial that causes main shaft is jumpy. Graph the affects pure radial of 2 main shaft to beat maths expression with jumpy to main shaft pure radial clearance of 4 scroll bearing studies to facilitate main shaft pure radial is jumpy the influence that machines precision to the spare parts, in the process that machining a spare parts suppose, machine tool main shaft on one hand with rotation of angular velocity W, at the same time axes of circumgyrate of main shaft instantaneous is in with average axes relatively again two perpendicular direction (coordinate of Y, Z) go up simple harmonic vibration. Building inertial rectangular coordinates is (OXYZ) , o chooses the place of ideal axle center that gives priority to an axis, building the right angle with couplet of firm of main shaft bearing to move coordinate again is (O1WMN) , o1 chooses the instantaneous axes place that gives priority to an axis. Use coordinate translation and after rotating attainable the coordinate commutation that two coordinate fasten concerns. If pursue,5 are shown. Graph basis of plan of concern of 5 coordinate commutation rule of simple harmonic vibration, the mathematical expression with jumpy radial of O1 of main shaft axes is: Y of of of of of of O1=AYcosfZO1=AZcosf (1) pursues signal of 6 boring treatment is schematic in: FGive priority to axial corner: F= Wt: AY, AZ is axes is in respectively Y, Z the amplitude of the simple harmonic vibration on two coordinate direction. (The influence that pure radial of main shaft of 2) (3)3 beats the influence that machines to the spare parts is machined to boring bores hole on boring machine when, boring cutter makes whirligig together along with boring machine main shaft. When main shaft makes pure radial beat, will make some of axes line edge secures direction to make simple harmonic motion. The aperture look that boring gives is the decision of athletic contrail place of point of a knife of the boring cutter in be being fastened by inertial coordinate. Set boring cutter point of a knife to be in the position that uses coordinate department: M=R, n=0, among them the radius that R machines aperture for place. If pursue,6 are shown. The positional coordinate cutting tool and type (1) generation enters type (2) , can get the orbit parameter equation in point of a knife of the boring cutter in inertial coordinate department: Y=YO1+ Rcosf=(AY+R)cosfZ=ZO1+ Rsinf=AZcosf+Rsinf (4) will (arrange after 4) type square: Type of Y2 + Z2 =1 (R+AY)2 (R+AYctgf)2(5)(5) is elliptical parameter equation, its grow axis and short axis it is R+AY and R+AYctgf respectively. Accordingly, in bore hole in the process, when main shaft has simple radial and jumpy error, so the opening that boring gives will be elliptic, the error of generation is circularity error, its value is: The influence that D=AY+AZ machines to turning is round outside be machined on lathe or when boring hole, workpiece makes whirligig together along with lathe main shaft. Because this workpiece is machined,geometrical appearance of the surface is the opposite contrail decision in moving coordinate to fasten by cutting tool. The coordinate position in setting lathe tool point of a knife to be fastened in inertial coordinate is Z=0, y=-R. Among them, r is treatment radius, if pursue,7 are shown. Graph sketch map of 7 turning treatment mixes the positional coordinate of cutting tool type (1) generation enters type (3) , can get cutting tool the orbit parameter equation in moving coordinate to fasten: M=(R-AYcosf)cosf-AZcosfsinfN=(AYcosf-R) Sinf-AZcos2f (6) by type (6) can get workpiece to be by the instantaneous curvature radius of appearance of treatment surface geometry: R= (M2+N2)½=[(R-AYcosf)2+A2Zcos2f]½ (7) because the numerical value of amplitude AZ is very little, can skip, criterion type (7) becomes: R ≈ R-AYcosf (8) by type (8) is knowable, the geometrical figure of workpiece cross section is similar at graph of line of a heart. If pursue,8 are shown. Graph if attempt of line of look of heart of 8 turning treatment takes R1=R-Acosf, r2=R-Acos(p+f) , criterion D=r1+r2=2R, showing this heart line is first-class diameter curve, namely the appearance of cross section geometry of workpiece does not have diametical error. When F=0, r=R-A, when F=p, r=R+A. So O1 is not the center of the real profile of end panel of the workpiece after treatment, of workpiece actual the distance of round of corridor center and O1 is A. Can you conclude accordingly: ? Lei swings Bo of Xiang of instruct of heart of the that collect administer enlighten Xun of sole children's hair breaks Liu of postscript of of Tao of Jia to need ぜ is able to bear or endure caves hold the post of Peng farsighted to complain ぜ to catch Wan holding the post of Peng to flinch circle of Ju of courtyard of postscript brighting tip suffers from Pi? conclusion to pass to main shaft, error of main shaft circumgyrate is very big to the influence of precision of spare parts treatment. Because this is in machining, should take effective measures to reduce error of main shaft circumgyrate to machine the influence of precision to the spare parts. Adopted step can consider from two respects. Want to raise the circumgyrate precision of main shaft above all. Main shaft bearing is the crucial part that affects precision of main shaft circumgyrate, to nicety the machine tool can use accurate scroll bearing, also use dynamic pressure of much oilier wedge bearing and static press bearing. Rise to cooperate the precision of the spare parts with bearing photograph even at the same time. Want to reduce the effect that error of main shaft circumgyrate machines to the spare parts next. Can use motion and the main shaft structure with separate fixed position, the circumgyrate precision in making workpiece is machining a process does not suffer the effect of error of circumgyrate of machine tool main shaft, make error of main shaft circumgyrate is not mirrorred to workpiece. CNC MillingCNC Machining