Pilot of contrail of high accuracy of numerical control machine tool a kind of new method

  • Time:
  • Click:241
The summary is aimed at numerical control technology and the demand that equip to develop to high speed high accuracy, research developed a kind of new high accuracy contrail to control a technology. Its core content is with sampling of high frequency high resolution interpolation generates contrail of cutting tool motion, pass new-style corner, the accurate implementation that closed-loop control of double position of displacement of the lines assures hope contrail, and with informatization contrail corrective the effect that removes mechanical sum of errors to disturb pair of orbit precision, in making sure place pilot machine tool is producing an environment thereby, long-term high accuracy moves. The system of new-style numerical control that makes from this already undertook applied on machine tools of a variety of homebred numerical control, obtained favorable result. Descriptor: Contrail of high accuracy of numerical control machine tool controls machine tool of 0 introductive numerical control is the main base equipment that implements advanced production technology, it matters to the strategic position that the country expands. Accordingly, home of base oneself upon is actual, develop the machine tool of numerical control of homebred high accuracy that has stronger competition capacity quickly, enlarge the market to have ceaselessly rate, progressively recover lost territory, become machine tool of our country numerical control to study the main task that development department door and manufacturer home face. To finish this one job, must capture a certain number of crucial technologies, but among them a the most crucial high accuracy contrail that is numerical control machine tool controls a technology. Accordingly, we combine production in recent years actual, be controlled from servo of high accuracy of interpolation of high speed high accuracy, high speed and informatization contrail is corrective wait for all respects, to contrail of high speed high accuracy control technology undertook the system studies, strengthened the development of system of new-style numerical control and machine tool of high accuracy numerical control for the foundation with this. The article will introduce obtains partial result. The basic idea progress as science and technology mixes pilot of contrail of high accuracy of machine tool of 1 numerical control the development of socioeconomy, the demand that machines precision to the machine tool is higher and higher. If rely on completely to raise component to make precision and machine tool assemble the tradition of precision,the method designs machine tool of numerical control of production high accuracy, certainly will raises the cost of the machine tool substantially, impossible even below some circumstances. Face this one reality, we undertook exploration to realizing the way of high accuracy with low cost, put forward a kind to pass information, control and union of photograph of machine tool structure to implement method of pilot of contrail of high accuracy of numerical control machine tool, its core idea is: ① uses the new-style interpolation technology that has high resolution and tall sampling frequency, raise orbit to make precision substantially below the premise that assures speed; ② passes closed-loop control of new-style double position, the high accuracy that assures hope contrail effectively comes true. ③ with informatization contrail corrective the effect that removes mechanical sum of errors to disturb pair of orbit precision, in making sure place pilot machine tool is producing an environment thereby, long-term high accuracy moves. Contrail of high accuracy of 2 high speed generates high accuracy contrail is foundation of pilot of contrail of implementation high accuracy. The article is mixed with frequency of high resolution, tall sampling of syncretic of wide choice interpolation muti_function sampling interpolation generates contrail of cutting tool hope. 2.

1 basic measure by sampling interpolation principle knowable, interpolation error δ (F(Hz) of frequency of Mm) and feed speed Vf(mm/min) , interpolation and by ρ of radius of interpolation curve curvature (next relations are like between Mm) (1) by on type is knowable, to assure high feed rate already, achieve tall orbit precision again, a kind of efficient way increases sampling interpolation frequency namely. Consider in machine tool of contemporary numerical control admiral often comes up against ditty of high speed high accuracy to lead radius to machine a problem. For this, when we are developing system of new-style numerical control, play soft hardware is integrated the advantage increases sampling interpolation frequency 5kHz, namely interpolation cycle is 0.

2ms. Such, although ask feed speed achieves 60m/min, when current curvature radius is 50mm, still can make sure interpolation error is more than 0.

1 μ M. 2.

Algorithm of interpolation of sampling of convention of 2 maths model uses recurrence form generally, general existence error accumulates effect. This kind of effect will cause the effect that cannot ignore to interpolation precision when interpolation of high speed high accuracy. Accordingly, we use algorithm of new very form interpolation when developing system of numerical control of high speed high accuracy, its should nod is: To be built to facilitate by interpolation curve calculative parameter changes mathematical model X=f1(u) , y=f2(u) , the U in Z=f3(u)(2) type -- ginseng is variable, u ∈ [0, 1] function calculation is not involved when   asks to undertake orbit interpolation with its, need to be decreased through the frequency is added rarely only by can finish except operation. For example, to circular arc interpolation, type (the particular form of 2) is (the M in 3) type -- invariable matrix, when interpolation the dot is located in one, 2, 3, when 4 quadrant, its take a value to be respectively 2.

Computation of interpolation of 3 real time changes the foundation of the model to go up in parameter, interpolation contrail computation is OK model coordinate origin is fiducial undertake, can eliminate thereby accumulate an error, assure interpolation calculative speed and precision effectively. Show a process to be as follows actually: Add decelerate to ask to decide interpolation of current sampling cycle is linear according to should advancing to be mixed to speed above all end length spends Δ L. Next, press type calculates what current sampling cycle joins variable to take a cost (the Ui-1 in 4) type -- the extraction that cycle of on one sampling joins variable is worth -- the perturbation that joins variable is measured -- the X with correspondence, y, the perturbation quantity of Z enters Ui era orbit computation formula finally (2) , the coordinate that before computation gives interpolation contrail to be duped, can nod is worth Xi, yi, zi. Till arrive at interpolation terminus,repeat above process ceaselessly, the interpolation contrail that can get whole disperse is changed. Need to explain a bit, press type (the be patient of when 4) computation Ui is certain error, this error can have little effect to feed speed only, won't produce any effects to interpolation contrail precision. Such, the evolution operation in type can use the means that check a watch to be finished quickly. 2.

4 calculate an analysis to express 1 gave out the interpolation computation result that the first quadrantal radius is 50mm circular arc. Interpolation of the first behavior in the watch orders serial number, the extraction with variable ginseng of point of each interpolation point is worth U behavior, the coordinate of each interpolation dot is worth behavior of X, Y. To analyse interpolation error, the real value that linear end length spends the circular arc radius that each interpolation the dot is in and interpolation also together the R travel in rank watch and Δ L go. See by the watch, it is certain that the error that although interpolation process is trapped,arises nods an edge to be had by the accuracy of position of interpolation curve around to interpolation influence (Δ L value has about be less than the error) of 1% , but the R cost that each interpolation dot manages always is 50.

000, spot of this specification interpolation is precise be located in be gotten on by interpolation curve, nonexistent contrail error. Express result of computation of interpolation of 1 circular arc (X, y, r, the unit of Δ L is Mm)normal Align=center> interpolation nods Normal Align=center>unormal Align=center>xnormal Align=center>ynormal Align=center>rnormal MARGIN of Center" Align=center> Δ : 0cm 0cm 0pt; TEXT-ALIGN: Center" Align=center>1normal Align=center>0.

079normal Align=center>49.

383normal Align=center>7.

831normal Align=center>50.

000normal Align=center>7.

855normal Align=center>2normal Align=center>0.

159normal Align=center>47.

543normal Align=center>15.

482normal Align=center>50.

000normal Align=center>7.

869normal Align=center>3normal Align=center>0.

241normal Align=center>44.

526normal Align=center>22.

747normal Align=center>50.

000normal Align=center>7.

866normal Align=center>4normal Align=center>0.

326normal Align=center>40.

410normal Align=center>29.

446normal Align=center>50.

000normal Align=center>7.

863normal Align=center>5normal Align=center>0.

415normal Align=center>35.

297normal Align=center>35.

413normal Align=center>50.

000normal Align=center>7.

858normal Align=center>6normal Align=center>0.

511normal Align=center>29.

319normal Align=center>40.

502normal Align=center>50.

000normal Align=center>7.

851normal Align=center>7normal Align=center>0.

614normal Align=center>22.

625normal Align=center>44.

588normal Align=center>50.

000normal Align=center>7.

842normal Align=center>8normal Align=center>0.

728normal Align=center>15.

385normal Align=center>47.

574normal Align=center>50.

000normal Align=center>7.

832normal Align=center>9normal Align=center>0.

855normal Align=center>7.

782normal Align=center>49.

391normal Align=center>50.

000normal Align=center>7.

818normal Align=center>10normal Align=center>1.

000normal Align=center>0.

000normal Align=center>50.

000normal Align=center>50.

000normal Align=center>7.

After   of plan of double closed-loop control of pilot of contrail of 8063 implementation high accuracy achieves orbit of accurate cutting tool hope through interpolation of high speed high accuracy, next the task is how to make sure cutting tool moves actually the hope contrail of orbit and interpolation generation is consistent. The high accuracy seat that needs to solve each motion coordinate above all for this controls a problem. 3.

If the dynamic structure that 1 system forms system of control of position of machine tool of groovy complete closed circuit pursues 1 is shown. Its devise an idea is positional outer shroud is added to form position of complete closed circuit to control a system on the foundation of speed annulus. Pull the project that uses a system to devise a method according to electric power, when designing this kind of system, positional controller should choose PI or PID adjuster, in order to make the system is obtained faster follow function. However, because this kind of system is high-ranking Ⅱ system, frequency of its open loop is characteristic will with nonlinear of link lose a curve to intersect, make the system appears thereby nonlinear control oneself oscillation and cannot work normally. This makes this kind of system is in hard actual in wide application. Graph the dynamic structure Ni of system of control of position of 1 groovy complete closed circuit, no -- instruction of timing system input and Ki of output rotate speed -- the blemish that gain of main transfer machinery controls a system to exist to overcome position of groovy complete closed circuit, must break the tradition that is position of fundamental construction complete closed circuit to control a system with speed core to be manacled theoretically, seek the way that wins high accuracy newly on the foundation that assures reliable stability. Through old exploration, we excogitate a kind of new corner - position of double closed circuit of displacement of the lines controls a method, if the dynamic construction that controls a system by the place that its make pursues 2 are shown. The characteristic of this system is: Whole system by inside and outside two positions annulus is comprised. Among them in-house closed circuit is corner position closed circuit, its detecting element codes to install the photoelectricity on electric machinery axis dish, actuating device is communication servo, the corner that composes one input to output the O that it is θ for θ I from this is followed use a system. External position closed circuit uses the detecting element of displacement of the lines such as synchronized of grating, induction to get the displacement information of machine tool workbench directly, follow with the corner of core move a system to move for workbench of actuating device drive. The displacement precision of workbench is decided by detecting element of displacement of the lines. Graph 2 corner, the dynamic structure of system of control of position of double closed circuit of displacement of the lines the design train of thought of this system is, annulus of inside and outside is reasonable divide the work, core is in charge of dynamic function, stability of environmental protection card is mixed outside follow precision. It is those who improve a system to follow function, passageway of the make a present of before introducing what comprise by Gc(s) , make compound control system. 3.

2 stability and error analysis   (1) stability analysis does not include space as a result of in-house corner closed circuit nonlinear link, because this adopts reasonable design this local and linear system, can make its are become follow quickly without what exceed tone use a system, its trends character can express to be approximately (θ of the K in 5) type -- θ of T of   of   of gain of corner closed circuit -- although outer shroud of system of constant of time of corner closed circuit was included nonlinear link, but design controller makes (the Kp in 6) type -- integral link time is invariable the system corrective for gain of system of Ⅰ logical choice, the frequency character curve that can prevent a system and nonlinear of link negative pour a curve to intersect or surround its, make sure the system stabilizes the job thereby [2] . Become apparently θ of K of ≈ of I(s) of θ of O(s)/ of the θ when T θ is lesser, the system will have stronger stability. (2) follows error analysis uses afore-mentioned plan to be able to assure a plan 2 systems stabilize the job, accordingly but oversight is nonlinear the influence of the element, the transfer function that demands this system (when 7) system is designed, make feedback coefficient Kf=1, before passageway of make a present of (8) has specification of the type on   of 1 (9) of Φ X(s) ≡ , the dynamic property that system of double closed circuit has ideal and follow precision. School of error of 4 informatization contrail is below double position closed-loop control, the precision that machine tool coordinate moves basically depends on detect the exact rate that device gets information. Accordingly, rise effectively through information compensation further detect the influence that the precision of device makes its do not suffer external environment, will offer a new approach to raise coordinate motion precision further. Take the following step for this: To detecting the error of device and the relation of its and systematic condition undertake determining accurately and build the mathematical model that describes error relationship, state information is concerned by basis of numerical control system in machining a process (if workbench is actual the position, detect the temperature of device) by mathematical model computational error compensates a value, and to detecting accordingly the measured value of device has real time corrective, make sure component of machine tool motion has very tall motion precision along respective reference axis thereby. Go up for the foundation that moves in high accuracy coordinate, the much coordinate that obtains high accuracy synthesizes orbit, use method of correction of geometrical error informatization further. For example, to workbench of machine tool X, Y not verticality error, can undertake through the following process corrective: Measure one nicety the head to load machine tool main shaft, the master body that goes up on workbench to solid (circular arc outline) undertake metrical. Should exist between coordinate of the X of the machine tool, Y not when verticality error, measures contrail will not be an accurate circle. Compare contrail of this actual measurement and standard contrail photograph, can beg coordinate of a X, Y not verticality error value. The motion that is worth coordinate of pair of X, Y by this error undertakes corrective, can make X, Y synthesizes athletic contrail to achieve taller precision. What use this principle at other geometry error is corrective, the synthetic contrail precision that can raise much coordinate effectively to move. If afore-mentioned corrective processes are inserted in machining a process, the heat that still can cause to temperature change is out of shape the error undertakes be compensatinged effectively. 5 application example controls a technology to be a foundation with contrail of high speed high accuracy, developed system of a kind of new-style computerized numerical control [3] . Some user controls SKY1632CNC Milling with this system, its machined function to have rise apparently. For example, have part of a kind of mixed pattern, by treatment surface not only curvature change is acuteness, and the curvature radius value of a lot of place is very little, when controlling a machine tool to undertake machining with old model system in the past, must use very small feed speed talent to assure to machine precision, productivity is very low. After using system of new-style numerical control, because its are opposite,big curvature and the height that curvature changes get used to ability, make feed rate rises multiple hind, still can machine the part that gives qualification, improved productivity substantially thereby. In addition, pass the control of new-style system, restrained mechanical transmission error effectively, when change the element such as cutting force and temperature change is right the influence that machines precision, better solved large order quantity, long (successive a few hours of above) the orbit sideslip problem that exists in treatment, improved the treatment quality of complex part. The article is aimed at 6 conclusion to send the demand of machine tool of high accuracy numerical control, excogitate a kind of new high accuracy contrail to control a method, developed system of new-style numerical control for the foundation with this. In this kind of new-style system, with high frequency high resolution algorithm of very form interpolation generates contrail of cutting tool hope, to achieve high accuracy orbit control laid information foundation. Through moving to the machine tool the component has double position closed-loop control, restrained effectively already nonlinear the influence of the element, made sure the machine tool stabilizes the job reliably, can acquire taller dynamic property again, make the displacement precision of each coordinate by detect plant decision, excluded the transmission error effect to precision of contrail of cutting tool motion thoroughly, made sure actual contrail and hope contrail are consistent effectively. On this foundation, pass informatization error corrective, rose effectively to detect the precision of device restrained the geometrical error effect to orbit precision, in making the new-style machine tool that makes from this is producing an environment thereby, long-term high accuracy moves. Apply a proof actually, in complex nicety by machine tool of numerical control of pilot of new-style control system the spare parts machines a respect to have favorable effect. This achievement gives an efficient way to increase the treatment precision of numerical control machine tool and speed exploration. CNC Milling