Use laser interferometer to raise precision of fixed position of numerical control machine tool

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Numerical control machine tool is in moving process, its locate precision can produce certain error, apply laser interferometer correctly, undertake be analyticed scientificly in the round, can raise the fixed position precision of numerical control machine tool effectively. Gain ground as what numerical control machine tool applies, use laser interferometer to undertake what had become current and accepted efficient, high accuracy locating precision detects detect to numerical control machine tool method. The precision curve that different machine tool uses laser interferometer to detect is met somewhat identical, because this needs,offer comprehensive and scientific analysis as a result to disparate test. Locate to numerical control machine tool common error curve undertakes precision below analysis, discuss effective solution jointly with everybody. 1, curve of negative gradient negative gradient moves outwards and run two tests to all appear upcountry the gradient that be down. On 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. Appear the reason has the possibility of negative gradient the following two kinds: (1) collimation of beam of light is adjusted incorrect. If axes is short at 1m may be material heat expands temperature of incorrect, material measures compensation coefficient incorrect or wavelengh compensation is incorrect. (2) a simple move or action and twist place cause Abbe to slant error of buy error, machine tool linear. Be aimed at above problem, the step that can take has: If axes distance is very short, examine the collimation case of laser; Examination EC10 and measure whether the head already joined and respond; The hand that checks an input uses environmental data correct; Examination material sensor is correct the coefficient of expansion of fixed position and input is correct; Lens group does use angle optics to measure afresh, a simple move or action that examines a machine tool and twist place an error. 2, gradient gradient curve is to point to go up in whole axes length, the error shows linear to increasing by degrees. The generation of this kind of phenomenon has the following possibility: (1) material heat expands temperature of incorrect, material measures compensation coefficient incorrect or wavelengh compensation is incorrect. (2) a simple move or action and twist place cause Abbe to slant the buy error, linear error of the machine tool. Be aimed at these problems, can take the following step: 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; Lens group does use angle optics to measure afresh, a simple move or action that examines a machine tool and twist place an error. 3, periodic curve is periodic the curve is the repetition on whole axes length periodic error. A simple move or action of edge axis keeps changeless, but extent may change. The likelihood that brings about periodic curve the problem that the reason basically is machine tool respect, be like guide screw or coder problem or transmission system breakdown, breakdown, long model linearity of axes of orbital of door type machine tool. In the light of above problem the proposal uses very small sampling to nod interval to be measured 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, the pitch that passes the pitch that compares machine tool guide screw, rack next, coder, resolver or a simple move or action of ball bar rule, long model the distance between strong point of door type orbital source of error that will acknowledge a possibility. For example, if error cycle is 20mm, consult we discover machine tool manual of guide screw guide be apart from also is 20mm, very apparent error may rotate with guide screw the problem is concerned, guide screw may be when recent maintenance or machine tool are mobile was bent, or guide screw is prejudicial rotate. 4, deflection deflection is to point to go Cheng and return trip have changeless perpendicular deflection twice between the test. The likelihood that produces deflection curve the problem that the reason basically is machine tool respect, was not compensated like backlash or clearance exists between undeserved compensation, frame and slideway (become loose) etc. Can adopt in the light of above problem solve measure below: Guide screw / ball silk lever actuating device; Check bulbiform nut or guide screw to whether wear away; The case of the float that carry a department that examines guide screw bearing; Group of lens of use angle optics checks the frame angle clearance when axes inverts; The backlash compensation that checks the setting inside controller is correct; Frame and denticulation actuating device; Examination tooth is correct clench the teeth; Whether examination gear case wears away and uniform encoding implement systematic state. 5, swallow end account pursues the circumstance of the 1 gradient that is down to appearing, 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. Generation swallow-tailed is likely the problem that the reason basically is machine tool respect, if ball guide screw is turned round, too close, use error compensation is worth slideway incorrect etc. Graph curve of error of account of 1 swallow end is aimed at above problem, have the following proposal: Examination guide screw and slideway are lubricant; Examine the balance action on vertical axis; Check and adjust slideway is placed; Whether does examination slideway lid bite move and inspection controller compensation. 6, positive and negative of retrorse across line to alternate line it is point out mistakes so that they can be corrected to (outward) moving generation loses gradient, and retrorse (inward) move to arise gradient. 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. In the light of these the problem can adopt: 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 the work that in axes intermediate position completes much, current compensation can consider as first-rate the means of settlement, 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. Nextpage7, zigzag graph the 2 currents that increase to be shown in the error in whole test process, setting even for fiducial value or the axes of 0 locally the error still is increasing. Appear the reason has this zigzag possibility: (1) the hot drift of group of guide screw error, optical lens. (2) feedback of mechanical failure, coder is fluky. Graph curve of 2 zigzag errors is aimed at above problem, we suggest: If the error is very small (a few micron) , can be in when each other approach optical lens group, set be fiducial value and redo checks. Ensure before beginning a test optical lens group already had sufficient time acclimatization temperature, 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 because secure,cause guide screw error with mobile optics. We should ensure before checking afresh, reduce the possibility of guide screw error as far as possible. Be aimed at the hot drift problem that by optical lens group acclimatization poses, before checking afresh, we should 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 hot drift of guide screw sum of errors is not the cause that causes an error, it is mechanical drift likely. Machine tool axes produces mobile word relative to system of feedback of machine tool position, may cause, such, the quantity of heat of electric machinery is passed in the airframe of the machine tool to make the temperature of the machine tool rises gradually. Because have this kind of possibility, because the package that produces shift namely heats up the distance that expand and moves to be able to be restricted by content reason, if this is planted circumstance, we are OK and reasonable after forecasting the test in fixed number, error (one-way) addition rate will be reduced gradually, mechanical drift produces negative error the most likely and the gradient that produces can be a direction more compressed than another direction; Because coder signal has noise,also be likely additionally, the pulse computation that causes controller increases, or the circumstance with coder signal n and controller incompatible input. 8, the error that petaline contrast figure shows 3 times increases ceaselessly along with time and distance make the line appears petaline form. The reason has the possibility that brings about petaline form: (1) locate in material temperature sensor incorrect or coefficient of expansion is incorrect. (2) during ball guide screw is checking, temperature rises, change of machine tool temperature. Graph the accuracy that curve of error of 3 petaline form checks to assure, the proposal should make a machine tool complete before beginning calibration warm-up. In the graph 3 in, 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. 9, triangular triangle curve is to show the error shows linear to increase, the error is be expert at Cheng is farthermost when the machine tool inverts, end appears jump litre, return in return trip test next return when as initial as axes drop same locally. The likelihood of occurrence triangle the reason is upright ministry wears away because of slideway and appear outside axes deflexion. What ought to notice is, the position of retrorse illuminator has distinct effect to indication error. The proposal uses group of angle optics lens to measure deflexion part directly, so that be opposite,the serious degree of deflexion problem has sufficient knowledge. 10, step form pursues 4 show or the interval with go up or issue length of step edge axes to press certain appears. The reason is in the likelihood of occurrence step form machine tool respect: On big machine tool each rack paragraph alignment not beautiful or assemble not beautiful or uniform encoding implement or inductive type measures measuring implement section to aim not beautiful or assemble not beautiful. Graph on the large machine tool that curve of error of 4 step form has rack and gear drive in equipment, rack by a lot of parting assemble the separate section composition on the machine tool, must ensure every paragraphs of correct ground and other paragraph 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. This kind of problem can pass an inspection every rack paragraph length and relative position, be found out with graphical data quite. The analysis on put together can see, except precision of machine tool itself not beautiful can be brought afore-mentioned all sorts of errors, laser interferometer operation is undeserved (include precision to be stabilized not quite or use oneself to affect more sensitive laser interferometer system to temperature) also can bring bigger error. CNC Milling CNC Machining