The backlash of lathe of shallow analyse numerical control reachs his to compensate

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The exercise that error of backlash of １ , foreword is workbench of the machine tool after showing the machine tool is changing athletic way is brief lag rotates at electric machinery, the retrorse deviation that bring about workbench or arises. In machine tool of numerical control of half closed-loop control, backlash will affect a machine tool to locate and repeat fixed position precision in mobile process, affect thereby by the precision of treatment spare parts. If backlash is too big, the part that treatment gives can produce bigger circularity and linearity error, and increase percent defective. 2, when generation reason passes the feed system of workbench of drive of ball guide screw by electric machinery drive, because assemble the machine in the process of catenary of drive of clearance, long-term movement wear away and servo electric machinery and servo motor are retrorse the existence of dead band, when making appropriate machine tool is another direction from inverting of motion of a direction, the instruction of the movement of executive component and numerical control system is different pace, locate and repeat fixed position precision what affect rod of machine tool movement. Final report is the form that be mixed by the dimension of treatment spare parts error. Backlash is the subassembly such as guide screw of feed system ball hind exist objectively, belong to inevitable treatment principle error, but can reduce its to get an effect to treatment through conditional control and error compensation. 3, because the factor that affects backlash error suffers force is hour change deputily in guide screw of the ball in virtual campaign process, its influencing factor is very accordingly much. In the numerous factor that affects backlash of ball guide screw, heat is out of shape and stress deformation is the biggest to the influence of backlash. Heat is out of shape is to show the main composition component of ball guide screw is like guide screw, nut to wait for the heat source that generates in athletic process, its heat source can deliver a machine tool other component, make corresponding component generation is out of shape. It machines what affect a part directly precision. The stress deformation of guide screw is to point to ball guide screw deputy the stress concentration that produces in athletic process, it can make ball guide screw produces displacement in athletic process, the fixed position precision that reduces a machine tool thereby and repeat fixed position precision, bring about easily by the form of treatment spare parts the error is too big. 4, detect the measurement technique of methodological backlash error basically has two kinds big, one kind is to use appearance law to measure, another kind is cut a law to measure through trying. Among them appearance law measures the instrument that basically uses to include interferometer of dial gauge, dial gauge, laser to wait. Among them laser interferometer and ball lever appearance belong to high accuracy instrument, measure data essence to be spent definitely tall, but the price is high; Although dial gauge is low-cost, but its itself sensitivity is low, bring about detect the data accuracy that go out is poor; Dial gauge is better choice, detect precision is more accurate, the price is likely also, it is appearance law detects the tool with commonly used backlash. 0 ｉ of FANUC 　 - system of ｅ of M ａ ｔ provides parameter setting, can compensate the backlash that two kinds of mode issue cutting and fast feed. General choice undertakes metrical below cutting feed means, with the actual condition that more accurate reaction machines. 4. １ appearance law measures backlash to measure X axis in order to be below cutting mode with dial gauge backlash is exemple, concrete move is as follows. (１ ) wind the machine tool reference point. (2) moving program, the machine tool shift decides a dot to, be like G01X100F100. (3) on the machine tool right now mount dial gauge measures X axis, after controlling a list, rotational dial moves watch needle for 0. (4) moving program, continue the machine tool to move forth, be like G01X200F100. (5) moving program, move the machine tool return original measurement point, g01X100F50, right now watch needle can be contacted with the machine tool, feed speed should some slower. (6) observe dial gauge reading right now, its show numerical value is X axis namely the backlash inside 100 ｍ ｍ . The backlash measurement technique of Z direction and X to similar. When the attention is undertaking backlash is compensated first, should be worth its corresponding in numerical control system compensating parameter to clear (1851 parameter are in FANUC system) . 4. 2 try cut a law to measure backlash to measure a law to measure backlash operation to go to the lavatory simply with the watch, but did not include the cutting strength effect to backlash in detect, its have certain limitation as a result. For truer and accurate measure backlash, can use try cut a way. Try cutting a law to measure backlash basically undertake below the condition of imitate finish machining, its are specific move is as follows. (１ ) go out parameter of the backlash in the system initiative value setting to be 0 (1851 parameter are in FANUC system) ; (2) installation good cutting tool and workpiece, treatment is like graph １ (１ ) what show step axis, semifinished product diameter is φ 20, workpiece coordinate fastens the center that is established in workpiece right end panel. Graph １ tries cut a law to measure backlash (3) cooperate with G71 and G70, to this axis outside outline has thick, precision work its are specific the program is as follows: Its finish machining walks along cutter track line to be like graph １ (2) be shown, can see go up in X direction, of measure ① and measure ③ retrorse and contrary, can introduce backlash, the way of measure ③ and measure ⑤ is same, nonexistent backlash. (4) because measure ① is mixed,backlash introduced between measure ③ , and there is backlash between measure ③ and measure ⑤ , bring about diametical dimension φ 12 with φ the dimension deviation of 16 is abhorrent, if oversight is other element not plan, its deviation is X direction backlash namely. (5) same, on Z direction, because the way of measure ② and measure ⑥ is opposite, can introduce backlash, cause error of Z direction size abhorrent, if oversight is other element not plan, its deviation numerical value is Z namely to backlash. (6) the accuracy to assure to measure, can undertake for many times metrical, take average, in inputting measures average corresponding parameter. 5, compensation method is measured through the measure above after backlash, can reduce its through backlash compensation the influence to machining. Backlash compensation can compensate implementation of two kinds of means through software and hardware. 5. Compensation of hardware of １ hardware compensation basically is each mechanical components in adopting chain of pair of feed system drive undertake adjustment be mixinged in order to reduce elimination backlash, because this calls machine again,adjust compensation method. Specific adjust object and measure to be: Adjust ball guide screw deputy, the locking force of its locknut adjusts the join precision that raises its to secure bearing, modulation backlash; Adjust guide screw and electric machinery, advocate if be made to shaft coupling of both connective flexibility,adjust, raise its join precision. Hardware compensation can adjust the backlash that eliminates much to be caused as a result of the opposite displacement between mechanical component through machinery. But this kind adjusts a method to want to undertake installing tearing open handling a trouble to mechanical component, and taller to adjuster technology requirement, just do this to adjust when the machine tool heavies repair only commonly. 5. Compensation method of software of 2 software compensation according to be by the system parameter is compensated or program compensation cent is systematic parameter compensation method and compensation method of numerical control program two kinds. 5. 2. Compensation method of parameter of system of compensation method of １ system parameter is in be worth measures backlash the systematic parameter that inputs a machine tool, undertake compensating (can pass manual of machine tool parameter to be checked specificly compensation date, 1851 parameter are in FANUC system) . After be defeated by compensation to be worth become effective, feed system can move first after inverting given compensation cost, take the space that the program appoints again, will realize backlash compensation with this. Operation of method of this kind of compensation is simple, do not affect Cheng, but the error with constant presence. 5. 2. The basic idea of compensation method of program of numerical control of compensation method of program of 2 numerical control is when writing numerical control program, if this paragraph is put in backlash, a paragraph of small distance moves on direction here first, the reentry after eliminating backlash is machined all right, will eliminate backlash with this. Compensation method of numerical control program avoided a watch to measure law and try those who cut a law to measure backlash is factitious and measure the error that cause, compensation precision is accordingly tall, but raised craft to make the difficulty with process designing at the same time, taller to requirement of process designing personnel, ask with the numerical control machine tool that compensates a function at having space or precision particularly tall spare parts is machined commonly. If the graph is shown 2 times,compensation method of numerical control program machines example. Graph if sketch map of compensation of 2 machine program pursues 2 (１ ) be shown, process one step rod, semifinished product diameter is φ 20, coordinate fastens a setting to be in the center of right end panel, its are specific the program is: By the graph 2 (2) can see, when using method of this kind of treatment, in ① of the measure on X direction and measure ③ retrorse and contrary, can introduce backlash, and the way of measure ③ and measure ⑤ is same, nonexistent backlash, use method of this kind of treatment to be able to bring about diametical dimension φ 12 with φ the dimension deviation of 16 is abhorrent. Same, on Z direction, because the way of measure ② and measure ⑥ is opposite, can introduce backlash. Eliminate backlash with compensation method of numerical control program, increase a block that takes for nothing in the front that generates backlash namely, the change takes knife way, taking backlash the knife for nothing paragraph eliminate. Be aimed at a graph 2 (１ ) step axis, can adopt a plan 2 (3) course taking a knife, its are specific the program is: Pursue quite 2 (2) and (3) can see, graph 2 (3) increased a paragraph of idle stroke, measure ② and measure ③ , among them measure ② is in Z direction inverting hind walked along a paragraph of idle stroke, eliminate Z to backlash; Measure ③ is in X direction inverting hind walked along a paragraph of idle stroke, eliminate X to backlash. 6, a epilogue backlash is precision of treatment of influence spare parts main factor, must cause take seriously, as a result of the component of the machinery in machining a process after adjusting wear away again, can produce new space again, because this backlash needs to be measured regularly and be compensated, in order to assure the treatment precision of the spare parts. Additional, those who attain ideal is to detect when undertaking backlash detects result, the staff member should abide by 　 of GB ／ T seventeen thousand one hundred and twenty-one. 2 - the requirement of 2002. In the meantime, be like temperature, radiate, air to also should satisfy real requirement fluidity to external environment. To open loop and the numerical control machine tool of half closed-loop control system, because its cannot detect directly,the actual displacement of the machine tool is measured, machine precision to raise its further, use backlash compensation to be able to raise its to locate precision is mixed significantly repeat fixed position precision. Practice makes clear, through the error of the machine tool compensation can make machining error reduces 60 ％ ～ 80 ％ . To the numerical control machine tool of closed-loop control system, because its itself is had,detect feedback device, can undertake each error undertakes compensating next detecting going out directly, use backlash to amend the result so not apparent, but the trends that can improve control system further through compensation is characteristic. CNC Milling CNC Machining