# Eliminate a kind of method of error of CNC Machining outline

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Graph 1 graph 2 my factories use FANUC, system of 0T numerical control transformed common lathe of a C6163, when treatment plan shows work 1 times, discover R10mm circular arc produces outline error. After eliminating to produce the other reason of outline error, electrical system lag causes the analysis. Graph 2 to cut the orbit error when the circle. Machine the as a result of servo radial lag when the circle, the outline that cause (appearance) error DR1(unit: Mm) is gain of position of × of 2 2 of DR1= feed speed 2 × radius divides DR1 outside, outline error DR2 is caused when the decelerate after two axes interpolation. DR=DR1+DR2 error is calculated, when machining R10 circular arc, cutting parameter S=100r/min;F=1mm/min, positional gain 1/40, criterion DR1= (1/60)2 =0.

022 2 × (10 graphs of 1/40)2 × the 3 servo block diagram that are function of the make a present of before the belt. VFF, A of coefficient of the make a present of before speed annulus, before coefficient of make a present of pursues 3 control an A as a result of the make a present of before increasing, make systematic position error multiplied a coefficient (1-a) , × of speed of feed of = of accession buy error (1-a2) is the smallest detect after the make a present of before gain of unit × position was joined, machine the as a result of servo radial lag when the circle, the outline that cause (appearance) the error is × of DR2= feed speed (A of hypothesis of 2 × radius takes gain of position of 1-a2) 2 × 0.

8 when, 36% what DR1 will reduce former error. Accordingly, in applying phasic error of the system to compress a function before set of make a present of can reduce outline error. Pass above analysis, when quantity of make a present of is increased before, the appearance error DR1 that can make the lag of servo is caused is reduced, theoretic A=1, appearance error should is 0. But because the torsion of electromotor has the limit, a cannot be taken 1, and cannot take too big, can make DR2 is increased otherwise. Because this must be calculated,choose good parameter, adjust a method to be as follows. Function of the make a present of before set parameter makes PI control is mixed is valid set NO.

1808 parameter PIEN(b3)=1 NO.

NO of coefficient of the make a present of before set of 1833 parameter FEED(b1)=1.

1961, take A=0.

8 speed pulse is counted (8192) 0.

4096 × of 8 × pulse of feedback of one dislocation buy counts 8192/1250=2128 electric machinery (inertia of load of × of VFEIT=(PK2V) of coefficient of the make a present of before annulus of speed of system of the make a present of before annulus of 1250) set rate + rotor inertia × 0.

105 rotor of ≈ of 4 × 2000 A of 8192 theoretical analysises takes inertia 0.

8 when, 36% what appearance error DR1(mm) will reduce original cost. Feed speed F=1mm/min. R=10mm. Positional gain 1/40. × of DR2= (1/60)2 (1-0.

8)2 ≈ 0.

008 2 × (10 basises of 1/40)2 × examine actually, appearance error basically is eliminated. Above is us in be being debugged actually, a basic function that uses a system reduces the outline error of the generation in treatment. If want to reduce outline error further, FANUC system still has set of a few kinds of functions to be able to apply. CNC Milling