Numerical control machine tool locates precision and laser interferometer check a curve

3 document label piles up B one, preface uses laser interferometer to undertake locating precision detects to numerical control machine tool, the precision curve that different machine tool detects each are not identical, want to raise precision of fixed position of numerical control machine tool, offer comprehensive and scientific analysis as a result to disparate test with respect to need. The error source that with respect to Leinishao the product is using the curve of error of a few kinds of machine tools that encounters in the process and solution offer an analysis. 2, precision of fixed position of numerical control machine tool is common error curve and analysis 1. Negative gradient pursues 1 in the curve moves outwards and move upcountry, two tests all appear the gradient that be down. Graph 1 show go up in whole axes length, the error shows linear to lose increase. The distance that the distance weak point that this expresses to laser system is measured indicates at system of feedback of machine tool position. Here attention, firm of Lei Ni carry on is used when analysing above data " all data pursue " the symbolic agreement of graphical type. A few 3 coordinate are measured machine (for example VDI2617) uses contrary symbolic agreement, because of this graph gradient to it contrary. Negative gradient of graph 1 (1) is likely reason. On laser interferometer setting, collimation of beam of light adjusts the likelihood incorrect, if axes is short at Lm, may be material heat expands compensation coefficient is incorrect, material temperature is measured incorrect or wavelengh compensation is incorrect. (The error cause with 2) probable machine tool. A simple move or action and twist place cause Abbe (Abb é ) slant the buy error, linear error of the machine tool. (3) proposal. If axes distance is very short, the EC10 of collimation circumstance examination of clear examination laser and measure whether the head already joined and respond, the hand that perhaps checks an input uses environmental data correct. Examination material sensor is correct the coefficient of expansion of fixed position and input is correct. Group of lens of use angle optics, do afresh measure, a simple move or action that examines a machine tool and twist place an error. 2. gradient pursues 2 show go up in whole axes length, the error shows linear to increasing by degrees. The likelihood is the following kinds of problems: (Setting of 1) laser interferometer may have a problem. Be like: Material heat expands compensation coefficient is incorrect, material temperature is measured incorrect, wavelengh compensation is incorrect. (The problem of respect of 2) machine tool. Be like: A simple move or action and twist place cause Abbe (Abb é ) slant the buy error, linear error of the machine tool. (3) proposal. Whether examination EC10 and sensor already joined and respond, the hand that perhaps checks an input uses environmental data correct. Examination material sensor is correct the coefficient of expansion of fixed position and input is correct. Group of lens of use angle optics, do afresh measure, a simple move or action that examines a machine tool and twist place an error. Graph 2 3. Periodic graph the 3 repetition that show whole axes length to go up are periodic error. A simple move or action of edge axis keeps changeless, but extent may change. Periodic curve is likely reason: (1) laser interferometer sets the issue that go up. The error size of this curve, unlikely that with the instrument the operation is concerned, basically go analysing the error source of machine tool itself. (The problem of respect of 2) machine tool. Coder problem or guide screw or transmission system breakdown, breakdown, long model linearity of axes of orbital of door type machine tool. (3) proposal. Use so small that much sampling nods interval, measure again on cycle of an a simple move or action, acknowledge error of a simple move or action. As a rudder, if you want to check, is a machine tool the periodic influence of some component, can set sampling interval to anticipate the 1/8 of periodic a simple move or action. More the following each, acknowledge likely source of error: The pitch of the pitch of machine tool guide screw, rack, coder, resolver or a simple move or action of ball bar rule, long model the distance between strong point of door type orbital. Graph 3 if a complete cycle is recorded on the graph (a simple move or action) length, will understand cause the cause of the problem somewhat. For example, if error cycle is 20mm, consult machine tool manual, the pitch that discovers guide screw also is 20mm. Apparent, error and guide screw rotate the problem is concerned. Guide screw may be when recent maintenance or machine tool are mobile was bent, or guide screw is prejudicial rotate. On machine tool of large door type, possible reason is rack and positive drive system assemble difference or gear disequilibrium moves. Check the pitch of the effective circumference of gear and rack, compare they and figure. Examine positional feedback system. Size of will periodic error and inductive type measure measuring implement (Inductosyn) the coder section on gage or ball bar rule (Spherosyn) the ball dimension in gage is compared. If periodic error is very small, should consider the possibility of coder interpolation breakdown. Check afresh with dinky sampling interval, in order to reduce the possibility of bogus signal. Nextpage 4. Deflection pursues 4 show go Cheng and return trip check twice between, have changeless perpendicular deflection. Deflection curve is likely reason: (1) laser interferometer sets the issue that go up. The error size of this curve, unlikely that with the instrument the operation is concerned, basically go analysing the error source of machine tool itself. (The problem of respect of 2) machine tool. Backlash was not compensated or undeserved compensation, clearance exists between frame and slideway (become loose) . (3) proposal. To guide screw or actuating device of ball guide screw: Check bulbiform nut or guide screw to whether wear away. Bearing of examination guide screw carries a float condition. Group of lens of use angle optics, check the frame angle clearance when axes inverts. The backlash compensation that checks the setting inside controller is correct. To frame and denticulation actuating device: Examination tine tooth is correct clench the teeth. Whether does examination gear case wear away. Uniform encoding implement systematic respect: When the machine tool that uses the frame that deploys coder of feedback of buy of dislocation coming back and pinion or guide screw actuating device when the test, will produce this kind of figure. To this kind of machine tool, when axes haul, when although be in,absorbing backlash, wait for measure time-out of axes general instant, the backlash inside ball guide screw or pinion actuating device still makes record of positional feedback system has shift. Graph 4 5. Swallow end account pursues 5 show, going appearing in Cheng test the gradient that be down, the return trip checks the mirror that to go Cheng checks. Go the deviation between Cheng and return trip test (or lag or backlash) leave to suffer drive to carry and rise gradually along with axes. Figure of swallow end record is likely reason: (1) laser interferometer sets the issue that go up. The error size of this curve, unlikely that with the instrument the operation is concerned, basically go analysing the error source of machine tool itself. (The problem of respect of 2) machine tool. Ball guide screw is turned round, too close, use error compensation is worth slideway incorrect. This kind of graph shows ball guide screw happening is turned round. The torque that needs when place of rotational ball guide screw is too tall, guide screw oneself begins to happen be out of shape (screwy) when, turn round occurrence ball guide screw. Twist angle leaves to suffer drive to carry and rise gradually as the screw cap of ball guide screw. If slideway or bulbiform nut are very close or biting, or intensity of oneself of ball guide screw is insufficient, guide screw of likelihood happening ball is turned round. The balance of vertical axis piece underweight also can pose this problem. Leave gradually when the machine tool when initial drop, the torque that place of rotational ball guide screw needs makes it produces twist. If coder is installed in ball guide screw get drive end, its rotational angle will be righter than be in end wants a bit more largish. Graph 5 for example: On the machine tool that has close slideway or dimension to cross small ball guide screw, the torque that place of rotational guide screw needs, enough makes guide screw screwy 0.

5 ° / M. Accordingly, if the value of error of a simple move or action of ball guide screw is L0mm, this twist is equivalent to Lm having 0.

The error of bus line sex of 014mm. Going in Cheng test, because this is screwy, every Lm will increase the reading of coder of machine tool position 0.

014mm. See return trip test again, run the situation with opposite way namely. When haul of ball guide screw, begin to be loosened gradually until without twist, going to next when opposite way is mobile, it begins again gradually screwy, until bring to bear on till enough torque makes machine tool axes moves afresh. Be loosened in this and in the process of new twist, the machine tool maintains fall asleep, laser record does not have shift, but the positional coder return trip in ball guide screw (get drive) upright ministry, will observe guide screw happening rotates (screwy) . The characteristic graph that this retrorse effect gives out shows, the return trip checks the mirror that to go Cheng checks. (3) proposal. Examination guide screw and slideway are lubricant. Examine the balance action on vertical axis. Check and adjust slideway is placed. Whether is examination slideway lid being bitten. Check controller compensation. 6. Positive and negative pursues to alternate line 6 show to (outward) moving generation loses gradient, and retrorse (inward) move to arise gradient. retrorse across line is likely reason: (The problem with potential on laser interferometer setting 1) : The error size of this curve is unlikely that with the instrument the operation is concerned, basically go analysing the error source of machine tool itself. (The problem of respect of 2) machine tool, this is a when guide screw turns round special case, among them, one-way and linear error is compensated and only retrorse cost already was installed in controller. (3) proposal. Examination guide screw and slideway are lubricant. Examine the balance action on vertical axis. Check and adjust slideway is placed. Whether is examination slideway lid being bitten. Check controller compensation. If the user plans to be among axes,the position completes major work, current compensation can consider as first-rate, because it distributings the biggest error to carry a department in axes, and the smallest error criterion inter position. Delete error compensation to will produce figure of swallow end record. Graph 6 7. Zigzag graph 7 show in whole test process the error shows addition trend. A its main character is, setting even when be fiducial value or the axes position earth of 0, the error still is increasing. (1) is zigzag likelihood reason. The hot drift that there may be group of error of a problem, guide screw, optical lens on laser interferometer setting. The problem of machine tool respect: Feedback of mechanical failure, coder is fluky. (If the error is very small,2) suggests (a few micron) , can be in when each other approach optical lens group, set be fiducial value and redo checks. Ensure optical lens group already had sufficient time acclimatization temperature. Before beginning a test, let machine tool warm-up. If temperature or other ambient conditions produce change during the test, possible reason is, laser is set when be fiducial value, as a result of the guide screw error that secure and causes. Ensure before checking afresh, reduce guide screw to produce the possibility of the error as far as possible. Another kind may be, by the hot drift that acclimatization poses optical lens set. Before checking afresh, ensure optical lens already had enough time acclimatization temperature. (the possibility that Leinishaoguang learns lens group to cause this kind of error is lesser, because the making material of lens group is aluminous, can compare steel quickly acclimatization. ) if guide screw sum of errors heats up drift,not be the cause that causes an error, it is mechanical drift likely. Likelihood machine tool axes feedbacks relative to machine tool position systematic happening is mobile, this may be by coder or linear metric appearance is installed not firm cause. The quantity of heat that may be electric machinery is passed in the airframe of the machine tool to make the temperature of the machine tool rises gradually. If this is planted circumstance, OK and reasonable after forecasting the test in fixed number. Error (one-way) addition rate will be reduced gradually, because have this kind of possibility, because the component that suspects generation shift namely heats up the distance that expand and moves to be able to be restricted by physical sex. Mechanical drift produces negative error the most likely, and the gradient of place generation can be a direction compare another direction compressed. The likelihood is the pulse computation that coder signal noise causes controller increases, likely also coder signal n and controller input are incompatible. Graph 7nextpage 8. Petaline form pursues 8 indication errors raise petaline form ceaselessly as time and distance likelihood reason: (The likelihood on setting of 1) laser interferometer has a problem, fixed position of material temperature sensor is incorrect or coefficient of expansion is incorrect. (The reason of respect of 2) machine tool. Ball guide screw is in test period asks temperature rises, change of machine tool temperature. If the ball guide screw of the machine tool is during the test,temperature rises, will produce this kind of figure. The characteristic graph that checks every time shows the error lets time and increase. To assure the accuracy of the test, the proposal should make a machine tool complete before beginning calibration warm-up. Pursue medium in above exemple, the likelihood carrying a department that installs ball guide screw as it happens and journey are bit more initiative coincide, and axial can arise in another end drift. If ball guide screw is in,be restricted to end, the graph will show negative gradient. Graph 8 9. The triangle pursues 9 indication errors show linear to increase, the error is be expert at Cheng is farthermost when the machine tool inverts, end appears jump litre. Next, when return trip test returns as initial as axes drop, return same locally. The triangle is likely reason: (The likelihood on setting of 1) laser interferometer has a problem. The error size of this curve, unlikely that with the instrument the operation is concerned, basically go analysing the error source of machine tool itself. (The reason of respect of 2) machine tool. Outside axes upright ministry wears away because of slideway and appear deflexion. The typical case of this kind of error is shown 10 times like the graph. Graph 9 slideway wear away cause deflexion, if pursue,the A dot of 10 is shown. Going in Cheng mobile ① , the torque of drive system makes frame relies on left slideway closely, frame edge walks relative to straighter path. But, when drive system haul, torque counterforce produces a change, frame will produce deflexion in tatty slideway place. This makes generation laser reading happens dash forward jump B. Go to when frame time the initiative direction that nod ② moves and walk out of serious tatty slideway to axes paragraph when, error drop off (if C is nodded) till 0. What ought to notice is, the position of retrorse illuminator has distinct effect to indication error. The proposal uses form of angle optics lens, measure deflexion part directly, so that be opposite,the serious degree of deflexion problem has sufficient knowledge. (note: In this exemple, because laser reading is read,take inadequacy, accordingly, the graph is to go up the mirror of legend. ) graph 10 10. Step form pursues the 11 chance to extricateoneself from an awkward position with show clear, or go up or fall, edge axes length appears by certain interval. Step form is likely reason: (The likelihood on setting of 1) laser interferometer has a problem, the error size of this curve, unlikely that with the instrument the operation is concerned, basically go analysing the error source of machine tool itself. (The reason of respect of 2) machine tool. On big machine tool each rack paragraph alignment not beautiful or assemble not beautiful, uniform encoding implement or inductive type measures measuring implement (Inductosyn) section is aimed not beautiful or assemble not beautiful. On the large machine tool of equipment rack and gear drive, rack by a lot of parting assemble the separate section composition on the machine tool. Must ensure carefully every paragraphs of correct ground and other paragraph of alignment, assure below one paragraph to gear can turn smoothly from a paragraph. If rack Duan Weizheng is aimed truly, transmission gear is aimed in the course deflexion may not happen when the joint of beautiful is nodded. This kind of deflexion can bring about measured value to appear dash forward jump step, if pursue,11 are shown. This kind of problem can pass an inspection every rack paragraph length and relative position, compare with graphical data, can find out very quickly. Graph 11 3, the analysis on summary put together can see, precision of machine tool itself not beautiful can be brought afore-mentioned all sorts of errors, but also cannot eliminate interferometer of laser of under certain circumstance the operation is undeserved (included to use precision is stabilized not quite or use oneself principle to affect more sensitive laser interferometer system to temperature) also be to be able to bring bigger error. CNC Milling