Machine tool of aviation numerical control places error of motion of horny head circumgyrate to analyse

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Machine tool of numerical control of 5 axes linkage is aviation industry the main component of advanced production technology, decisive effect is had in production of modern plane development. The precision level of numerical control machine tool is affecting the development of aviation advanced technique directly, what use extensively is complex in restricting modern plane to design especially model the promotion of large whole structural member uses the face. Have the development of the structural member of plane titanium alloy of superior performance, the technology that promoted the machine tool of numerical control of 5 axes linkage that has puissant fabricating characteristics progresses, raised taller and taller requirement to the precision of 5 axes linkage of numerical control machine tool. Of precision of 5 axes linkage detect precision of 5 axes linkage is the mainest index in assessment of performance of numerical control machine tool, can reflect the production technology level of the machine tool integratedly. Machine tool of 5 axes linkage of 5 axes precision check and accept detect the method that adopts treatment of cutting of conic test specimen commonly undertakes examining, if pursue,1 is shown. But this detects process designing of methodological need craft, try cut treatment and test specimen to examine wait for link. This kind of method operates cycle of complex, test to grow not only, and easy belt packs process designing of clip, craft, cutting tool into test specimen dimension and detect wait for multiple error. From this machine tool the actual precision of 5 axes linkage cannot be come out by accurate report, error link is very difficult accurate decide. Graph the 5 rods that 1 Beijing aviation makes project institute A/B place horny vertical machining center try cut RTCP (Rotation Tool CentrePoint, RTCP is machine tool of 5 axes numerical control rotates method of process designing of cutting tool center) the athletic precision of 5 axes linkage detects method, the whirligig process designing that can pass fixed to dimensional either point will realize a machine tool operation of 5 axes interpolation; Centers of each cutting tool of main shaft of implementation of reference axis linkage circle drive appoint a dot to rotate, the precision that realizes interpolation of 5 axes linkage detects. The athletic precision of RTCP, integrated the fixed position precision of each reference axis mixes the machine tool interpolation precision, it is precision of machine tool drive, oriented precision, closed circuit / the concentration of precision of open loop control is reflected, the structural tigidity that also is pair of machine tools, drive tigidity, synthesis that controls the influencing factor such as parameter rationality shows. Of RTCP motion precision detect (graph 2) , be install club of ball head core through be on machine tool main shaft, fasten the detecting element on workbench (like dial gauge or dial gauge) edge law to touch the surface of ball head, whirligig measures the ball heart that through process designing drive each coordinate confuses club of ball head core. This detects the method is carried out convenient and simple, quick, and the interference error that can avoid other factor effectively to be taken, it is at present precision of linkage of machine tool of 5 axes numerical control detects the most commonly used method. Of precision of motion of graph 2 RTCP detect the drive of axis of linear of numerical control machine tool uses gear rack commonly or closed circuit of feet of drive of ball guide screw, grating feedbacks, have the compensation of fixed position precision and retrorse error with laser interferometer, reach exact location easily precision and repeat fixed position precision. The error of reference axis of linear of numerical control machine tool, not be the main component of error of 5 axes linkage commonly. Numerical control machine tool the error of 5 axes linkage, more inadequacy of circumgyrate coordinate precision is brought about. Circumgyrate coordinate error analyses the measurement of precision of coordinate of circumgyrate of numerical control machine tool, in circumgyrate coordinate can polyhedron prism can be used to combine laser interferometer to undertake when 360 ° rotate, in circumgyrate coordinate clinometer cannot be used commonly when 360 ° rotate quite or tall the round grating of precision level (or angle coder) undertake, wait to corresponding transmission system, bearing bearing system next undertake necessary adjustment and control parameter are compensated, get ideal transmission precision. The precision of coordinate of circumgyrate of numerical control machine tool is assessed, general component is fixed position precision, repeat fixed position precision and retrorse error. From the principle analysis of drive of closed circuit of numerical control machine tool, the generation of the error basically is closed circuit round grating (or angle coder) the cooperates bearing of error, bearing and circumgyrate component radial of the backlash of link of the feedback precision, graduation precision that transmission fastens, transmission, rotor beats, turn the heart is apart from (circumgyrate coordinate turns the center arrives. Feedback among them component, drive deputy the error element with bearing bearing, can be solved effectively through choosing the component with precision higher level, the radial and jumpy error of circumgyrate spare parts can assure through more strict mechanical workmanship, these error elements rely on a machine tool to make a manufacturer increase corresponding manufacturing cost to be able to avoid effectively only. Of rotor cooperate an error, must use more appropriate fits tolerance and proper bearing to be solved closely beforehand, but had cooperated to tighten and had tightened cosmopolitan belt to turn back and forth beforehand additional power loss of motion, make the sky of machine tool rotor carries break-out torque to greaten, affect the dynamic function index of the machine tool. Coordinate of circumgyrate of numerical control machine tool should acquire good moving position, must make rotate through enough experiment test and verify bearing axis is obtained cooperate precision and appropriate bearing suitably to tighten force beforehand. Turn the heart is apart from measure the error of 5 axes linkage that forbids to cause too big, can amend turn the numerical value that the heart is apart from repeats have card of exam of check of precision of 5 axes linkage, turn well and truly in order to obtain the heart is apart from. The athletic error of coordinate of circumgyrate of numerical control machine tool, transmission link causes have quite big factor, basically transmission fastens graduation to all do not cause fixed position to forbid, backlash is brought about greatly too repeat fixed position precision low with retrorse error big. The graduation precision that transmission fastens can pass the precision that increases relevant drive cell to assure; Backlash must undertake adjustment to relevant and rigid structure. The main transfer machinery of rotor of numerical control machine tool is more typical is positive drive deputy with worm drive deputy, can eliminate the backlash of transmission link effectively through all sorts of rigid steps, move in order to realize the coordinate circumgyrate of high accuracy. Turn the measurement that the heart is apart from the machine tool that coordinate of circumgyrate of numerical control machine tool rotates for main shaft, in circumgyrate coordinate can when 90 ° of ± rotate, turn the measurement technique that the heart is apart from is shown 3 times like the graph. Nextpage above all, get on dial gauge solid on machine tool workbench, determine the 0 ° position of main shaft with dial gauge and square chi, make main shaft core strong (diametical D) side generatrix and parallel of square chi flank, the Z that measures end panel of record main shaft with dial gauge is worth Z1 to coordinate, hold dial gauge position changeless, move mode of operation to make main shaft rotates with the hand 90 ° , make the photograph adjacent face of generatrix of good side of main shaft core and square chi parallel; Next, the hand moves manipulator linear reference axis moves related the bed, make nadir of generatrix of good side of main shaft core touchs dial gauge, the Z that records dial gauge is worth Z2 to coordinate, turn the heart is apart from it is namely: Z1-Z2+D/2. Coordinate of circumgyrate of numerical control machine tool gives priority to the machine tool that the axis rotates, in circumgyrate coordinate can when 30 ° of ± rotate, turn the measurement technique that the heart is apart from is shown 4 times like the graph. Above all, get on dial gauge solid on machine tool workbench, determine the 0 ° position of main shaft with dial gauge and square chi, swing main shaft is in + the nadir that 30 ° position makes install the club of ball head core at main shaft touchs dial gauge, record transverse coordinate to be worth X1, hold dial gauge position at the same time changeless; Next, the operation places horn to rotate make main shaft is in - 30 ° position and the hand moves an operation the nadir that motion of transverse reference axis makes install the club of ball head core at main shaft touchs dial gauge, record transverse coordinate to be worth X2, heart of baseball of ball head core is written down to the distance of main shaft end panel for L, turn the heart is apart from it is namely: | X1-X2 | - L. The machine tool of numerical control of 5 axes linkage that the backlash rotor that circumgyrate coordinate drive fastens is mechanical drive, often make because of all sorts of reasons after be used for long backlash greatens, affect the moving precision of rotor, surface roughness of the out of tolerance of spare parts dimension that direct report machines for 5 axes linkage, surface is reduced etc. The elimination with circumgyrate coordinate commonly used drive the machine of backlash, basically have gear wheel deputy with worm deputy 2 kinds. Cent of unoccupied place orgnaization of positive drive disappear is straight gear, helical gear and double positive drive 3 kinds. Unoccupied place orgnaization of straight gear disappear is prejudicial law principle, driving gear installs the take-off at servo electric machinery to go up, driven gear installation is on transmission shaft, of electric machinery stop the mouth is passed prejudicial set with drive-box body Kong Pei closes, through roll prejudicial the center that covers proper point of view to change gear is apart from, reduce tine side gap. Unoccupied place orgnaization of helical gear disappear is axial displacement principle, through changing the spacer ply on gear axis, reduce the gap of clench the teeth of teeth of a cogwheel, raise transmission precision. Another kind of orgnaization with unoccupied place disappear of helical gear spacer (graph 5) , a cent in the helical gear that is will mutual clench the teeth becomes two valve structure, produce change through adjusting the ply of intermediate spacer to make the axial of two valve gear is apart from, the teeth of a cogwheel that sticks gear of close clench the teeth respectively two side, eliminate the gap of gear clench the teeth. Graph 5 spacer disappear is unoccupied place unoccupied place orgnaization of disappear of double gear of helical gear of two valve type (graph 6) , it is the helical gear with the 2 helix opposite way that goes up in an axis with installation, through be the same as output of clench the teeth of additionally two helical gear closely respectively beforehand, at the same time with driven rack (or gear) two side joint undertakes teeth of a cogwheel drive of clench the teeth. Graph unoccupied place orgnaization of disappear of positive drive of above of Nextpage of unoccupied place orgnaization of disappear of 6 pairs of gear, the structure is simple, adjust convenient, but the production precision that must assure gear, and the clearance after wearing away cannot be compensated automatically. Main transfer machinery of worm wheel worm often is used change lead worm worm wheel worm wheel of deputy, double worm deputy wait for a method with fission worm deputy structure. Because change,the treatment cutting tool of lead worm worm wheel creates difficulty, precision is not tall, use less. Graph it is good that A/B of institute of production project of 7 Beijings aviation places precision of orgnaization of worm wheel of double worm of horny vertical machining center, deliver torque big, but take up the space is large, the cost that the design uses is higher. The 5 coordinate A/B that institute of Beijing aviation production project develops places horny vertical machining center (graph 7) with machine tool of Italian RAMBAUDIRAMMATIC series (graph 8) the drive that place part all adopts pass the time in a leisurely way of double worm worm wheel unoccupied place main transfer machinery, all apply successfully in treatment of aviation structural member. Both distinction is former use in worm axis end adds certain and stretch preload, make sure accurate drive can avoid the transmission catenary rigid impact when cutting force is unusual effectively again already, can ensure the drive that place part uses the transmission precision that still can keep good for a long time, obtain " the takes mechanical main shaft A/B of mechanical drive form places horny numerical control all-purpose milling head " have letter only; Latter uses one worm wheel to rotate the means of the rigid fastening after tiny angle eliminates the gap of clench the teeth with worm undertakes accurate circumgyrate moves, this kind eliminates clearance method to be used for a long time as the machine tool easily wear away and the effect becomes poor. Graph if structure of drive of worm of fission of machining center of vertical of coordinate of 8 Italy RAMBAUDI5 pursues show 9 times, worm creates two system structure 1 with 2, the tine of intermediate part is mixed by C D2 half tine composition, the worm when assembling is covered 1 fixed, worm axis 2 turn by graphic representation direction tiny angle, the tine side B that D of side of the tine side A that assures to make age side C sticks close worm wheel, tine sticks close worm wheel, eliminate gap of clench the teeth. Because changed the integral sex that worm drive ages, transverse tooth thickness of the clench the teeth when transmission reduced an in part relatively, deliver torque lesser. Current, spanish PM-60 and machine tool of German UNISPEED3 series use this kind of structure. Above machinery structure is theoretic can eliminate transmission error and backlash effectively, but the requirement of CNC Machining precision that still cannot satisfy aviation structural member completely, the relevant parameter that still needs to control a system through be opposite in actual project application undertakes compensating correction, obtain precision of taller transmission fixed position and smaller retrorse error. Of the circumgyrate motion error of machine tool of last word numerical control detect with adjust, it is an unusually complex system project, need is produced in the development of the machine tool and explore ceaselessly in applied practice. Article author basis works actually experience, shallow the analysis of the error of rotor of numerical control machine tool that talked to be used at aviation domain, for relevant type machine tool the platoon of corresponding error element is checked provide referenced basis, for prospective machine tool the development of advanced production technology exhausts scanty power. The error of 5 axes linkage of numerical control machine tool is analysed, still a lot of problems need to consider and tackle key problem. High-grade machine tool of numerical control of 5 axes linkage is in what the function of advanced production domain develops aviation to apply a standard with the project to rise, allow to weigh and the path is far. CNC Milling CNC Machining