The electric control of coordinate of motion of numerical control machine tool

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Numerical control machine tool moves the electric control of coordinate by electric current (torsion) operating ring, speed operating ring and composition of series connection of positional operating ring. (Annulus of 1) electric current is the circuit that supplies torsion for servo electric machinery. Usually of it and electromotor match adjust already had made by maker perhaps appointed match parameter accordingly, its feedback signal also is finished in the connection inside servo, because this does not need wiring and adjust. (2) speed annulus is the circuit that controls traversal speed of reference axis of i.e. of electromotor rotate speed. Speed adjuster is scale integral (PI) adjuster, its P, I adjusts a value to depend on completely the laden size of place drive reference axis and mechanical transmission system (slideway, main transfer machinery) the physical characteristic such as transmission stiffness and transmission clearance, when once these character happen,changing apparently, need to undertake to mechanical transmission system repair works above all, next adjuster of PI of readjust speed annulus. The optimal adjustment of speed annulus issue ability to finish in the condition of positional annulus open loop, the reference axis that this moves to the level and rotational reference axis undertake more easily, and the meeting when positional open loop falls automatically and produce risk to athletic reference axis to hanging down, can adopt pick next electromotor sky to carry first adjust, reload good electromotor and positional annulus are adjusted together or take positional annulus to be adjusted together directly next, the experience with need to have certain at this moment and attentive. The feedback link of speed annulus sees in front " speed is measured " . (3) position annulus is to control each reference axis to press the operating ring item that statement position locates accurately. Positional annulus will affect the positional precision of reference axis and working precision finally. This has the job of two respects among them: It is the position the precision that measures component and CNC system pulse are equivalent match a question. The pulse amount course that measures component odd displacement to move a distance to give out is times more exterior frequency circuit and / or the resolution conform to that CNC interior wants to set with numerical control system after the times frequency of times frequency coefficient. For example the position measures component 10 pulse / Mm, resolution of numerical control system namely pulse equivalent is 0.

001mm, measure component missive pulse to must pass 100 times frequency to just can match. The 2 correct set that are value of Kv of coefficient of positional annulus gain and adjust. Normally Kv value is set as machine tool data, the setting address that Kv is worth and numeric unit were appointed respectively to each reference axis in numerical control system. The set that after speed annulus maximize adjusts Kv is worth makes stand or fall of function of reflective machine tool, impact the main factor of final precision. Kv value is bad of actor of function of oneself of coordinate of machine tool motion is direct behave and be not OK and aleatoric enlarge. The setting that is worth about Kv should note two problems, want to satisfy following formula above all: The V in type of Kv=v/ Δ   -- coordinate traversal speed, Δ of M/min     -- tracking error, mm   notices, the unit that different numerical control system uses may be different, the unit that numerical control system sets should notice when the setting. For example, the unit of coordinate traversal speed is M/min, criterion Kv value unit is M/(mm · Min) , if the unit of V is Mm/s, criterion the unit of Kv should be Mm/(mm · S) . The Kv that should satisfy each linkage reference axis next is worth must identical, in order to assure the precision when synthesis moves. It is the reference axis that is worth lowest with Kv normally to allow. Positional feedback has 3 kinds of cases: One kind is to do not have the position to measure component, for positional open loop control feedbacks without the position namely, the pace is open loop; namely commonly into electric machinery drive one kind is half closed-loop control, accession buy measures component not to move finally in reference axis on the component, that is to say still partial transmission link is in besides positional closed-loop control, part of the drive outside annulus of requirement of this kind of circumstance is due the transmission stiffness that comparative and transmission precision, after adding backlash compensation and pitch error compensation, can getting the 3rd kind very high position controls precision; is full closed-loop control, accession buy measures component installation to be on the final motion component of reference axis, theoretic circumstance of precision of position of this kind of pilot is best, but it is taller to the requirement of system of whole and mechanical transmission and not be low, if otherwise, can affect the dynamic precision of two coordinate badly, and make the machine tool can be mixed in slowdown annulus only the job below the circumstance of positional precision. Another when affect precision of full closed-loop control serious problem is the accurate installation issue that measures component, never despise. (Control of the make a present of before 4) and feedback are contrary, it is to will dictate the value takes out a part to add the adjustment from the back beforehand circuit, its main effect is to reduce tracking error to answer character in order to raise trends to raise the position to control precision thereby. Because most machine tool did not set this function, reason the article is not expatiatory, just want to notice, the affiliation of make a present of must be before in 3 afore-mentioned operating ring all optimal debug end rear can undertake. CNC Milling CNC Machining