Face the sort on the market to measure a head variously, after all it which kinds measure a head is better that which kinds measure a head? Have a kind of function to measure a head in the round, can you satisfy the measurement of all sorts of diverse demands? This kind of problem is measured in choice coordinate there is an user deeply when machine. The article elaborated all sorts of different types to measure the characteristic of the head and distinction, also analysed its to gauge demand in the light of different application, set out to go out to measure the proposal of a choice from the angle of the person that use, the hope has a few referenced effect to the user. "Touch hairdo to measure head and scanning to measure a head which better? " " does scanning measure a head more definitely? " these problems let not only the first time contact 3 coordinate to measure the user of machine, the old user that even if be,has had many 3 coordinate, it is the personnel that is engaged in 3 coordinate measuring machine sale even also when feeling is bemused. In choosing 3 coordinate to measure the process of the head, often appear final it is by the budget the decision is configured, bring about configuration thereby superfluous the awkward situation that perhaps configures inadequacy. We in configuration 3 coordinate are measured of machine when measuring a head, actual meeting faces the choice difficulty that comes from many respects, for instance " stationary still rotates type " , " scanning measures a head or spark measure a head " , " 3 axes linkage or 5 axes linkage " , " contact measures a head or optics measures a head " etc, and still do not escape finally estimated limitation. Although last element can have the effect that overrules to one ticket sometimes, but we are necessary to understand from technical angle of all kinds the characteristic that measures a head and applicable circumstance and limitation, so that can be chosen below integrated condition most appropriate measure a head, contented gauge a demand. [spark measure head and scanning to measure a head] should make an on-the-spot investigation actually spark measure head and scanning to measure a head both the distinction between, need comes from the characteristic that measures the task proceed. Well-known, 3 coordinate measure function to undertake arriving from dimension quite form of tolerancepublic errand all-around measure, belong to general-purpose detect equipment. But among them, single measure is measured, wait like length, diameter, angle, can be measured basically through simple measure, 3 coordinate do not have not replaceable distinct advantage; And the measurement of behavior public errand criterion drag in arrives a lot of respect, if measure fiducial, plan to close kind, measure a principle to wait, must rely on 3 coordinate to measure machine the whole that serves as a systematization will undertake, this also is 3 coordinate measure machines and tools to have the main reason that cannot replace a gender. Just as its name implies, form the elemental feature that tolerancepublic errand included two kinds to differ actually evaluates content, one kind is appearance public errand, another kind is positional public errand. Appearance public errand includes linearity, flatness, circularity, cylinder to spend in all, line outline spends knead dough outline; And positional public errand includes parallelism, verticality, gradient, position to spend in all, homocentric degree, coaxial is spent and symmetry. Additional, still have a kind of special look tolerancepublic errand calls jumpy, include radial / end panel circle beats and radial / end panel is completely jumpy. Jumpy go up from essence for, also be the appearance error that evaluates the element that be measured, accordingly we might as well its also classify appearance error a kind. We are with measuring a circle exemple, evaluate its diameter, position to spend respectively, circularity. Well-known, those who decide a round place needs is least the amount that measure a place is 3, can plan to close an academic circle so, and this round circularity is 0. In be measured actually, seldom happen to order the case that decides the circle that be measured with 3 only. Even if larger to tolerancepublic errand blame key size, can collect 4 dot in order to to decide the circle that be measured at least, lest get,fugleman of interference element shadow delivers generation bigger error. Indeed, to only place the error distributings evener circle (the curious aspect that does not have mutation) for, measure 4 dot, 8 are nodded or be 12 nod pair of final diameters and position to spend an influence very tiny (in tolerancepublic errand belt not quite little state of affairs falls) , plan to close gotten circle to using a least square method especially; But, the influence of the number that select a site to circularity is truly cannot of oversight. According to systematic analysis and computation, want accurate assessment to be measured what round circularity place needs to measure bit of amount N to not be less than 64[1] . This amount that measure a place gave us very clear instruction, if be measured what the measurement of the spare parts spends about Yu Yuan in the requirement to gauge demand, that need uses scanning to measure a head. Just think, if 64 of a circle measure a dot to use only place to touch hairdo,measure the word that the head will come to to measure, its measure efficiency let a person accept hard apparently. From measure efficiency and rationality to set out, it is circularity not only in fact, tolerancepublic errand measures the appearance of other type to should use successive scanning to measure a head, evaluate the appearance public errand of the element that be measured well and truly hard otherwise. According to above analysis, that is understandable measuring a head for scanning is to spark measure a head upgrade edition, does scanning choose to measure a head as far as possible below the premise that allows in the budget? The answer also is negative. Scanning measures a head undertaking only place sparks when selecting a site, its work way and touch hairdo to measure a head to have very big distinction. Touching what hairdo measures a head to select a site is to measuring a head to spark happen in the begining; And scanning measures a head is the means that uses imitate signal changeover, its are individual selecting a site is to measuring a head to spark end, when measuring a needle to leave object outside, happen. These two kinds of different kind that select a site cause most the distinction of clearly sparks namely measure a speed that select a site scanning of remarkable prep above measures a head. Spark the collects a dot to give a person feeling that measures a head is " touch retreat namely " , and scanning measures a head to select a site is to measure a needle to come up against workpiece hind, the meeting is brief stick sluggish to be in workpiece surface, next slow time retreat to leave workpiece outside. Accordingly, when gauging demand without scanning, with touch hairdo to measure a head measuring efficiency to go up to want prep above scanning to measure a head instead. What be worth to be carried additionally is, a few specific functions must rely on scanning to measure head ability to come true, for example " from centering " . "From centering " the bottom that applied circumstance is the center that is used at searching alveolus, chamfer commonly is waited a moment, this measures a head to have search function with respect to the requirement, till measure the ability after the imitate signal of the head reachs a steady state that accords with a condition to undertake,select a site, this function is " touch retreat namely " spark measure a head to cannot come true. [stationary is measured head and rotate measure a head] same, this also is not the proposition of bad of what of actor of a what, is design original intention merely is different the difference that causes applied situation. And rotate type measures a photograph comparing, stationary measures a the most distinct advantage is its measure a needle to carry ability. Because its structure designs the congenital advantage on,stationary measures a head, the greatest weight measuring a needle that allows to carry commonly and length should are more than apparently rotate type measures a head. Be in so the situation that deep aperture measures quantity, large part to gauge demand, choice stationary measures a head more general. But we are undertaking relatively complex measurement when the task, because measure a head to cannot alternate angle, with respect to need basis the different way that measure a needle configures sucking disk. Accordingly, the 3 coordinate that measure a head to configuring stationary are measured machine, double deck even three-layer changes a needle to wear very general, and the movement changing a needle in measuring a process is quite frequent also. Rotate this weakness that type measures the emerge as the times require of the head to measure a head to overcome stationary namely, measure a head metrical flexibility increases greatly below the condition that a simple move or action and deflexion function are not changing a needle, but, rotate the part sacrificed to measure a needle to carry ability however while type measures head flexibility to rise. The viewpoint thinks, the precision that stationary measures a head wants prep above to rotate type measures a head, such view some in order to slant without exception complete. Really, measure to metric class geometry (inferior micron class) for, high accuracy stationary measured a head to hold absolutely dominant position really; But to convention application, and do not have such as of deep aperture and so on gauge a demand, that stationary measures head photograph to type measures a head and do not have the advantage on any precision than rotating. [3 axes linkage and 5 axes linkage] here the performance that we must compare two kinds of different systems, and more it is right 5 shaftings all does knowledge to gain ground. Above all, so called " 5 axes survey head system " not be to show itself of the system that measure a head has 5 axes, 2 when survey head system however runner shaft coming back and coordinate measure 3 of machine straight bobbin to form 5 shaftings tube-shaped part jointly. Actually, 5 axes measure a head to also be belonged to rotate the category that measures a head, it and common rotate the distinction that measures a head depends on runner shaft coming back whether " linkage " . Common rotate the A/B axis that measures a head can offer deflexion (Yaw) and a simple move or action (Pitch) two kinds of angle, but the commutation of its angle can be in only blame measure condition next undertaking, and 3 of other linear axes also must keep dormant, accordingly this kind of system also is called " 3+2 system " . 5 shaftings all can rotate 2 axial motion is taken in be being measured in real time, with 3 linear axis works in coordination, implementation measures head part " the edge measures an edge to move " the effect. Because this photograph compares 3 shaftings,all can bring bigger flexibility. As the progress of current technology, 5 axes machine equipment to begin to be applied generally to the treatment of complex part, but this one trend still was not measuring a domain to be able to gain ground, the coordinate of great majority is measured machine on the 3 axes that still stay in the tradition or four-axle technology level. "5 axes are machined " with " 3 axes are measured " between not quits will naturally give measure the difficulty with be brought certain, cause measure blind area. Photograph of 5 shaftings all differs another times than 3 shaftings all to turn in Yu Jixuan axial graduation, the runner shaft coming back of 3 shaftings all is used at commutation measures brilliance to spend and be not being participated in to measure only, because this has fair angle scale division value; But runner shaft coming back participates in the linkage of 5 shaftings all measure a process, its measure brilliance to spend be successive change, in other words, the angle measuring a head of 5 shaftings all is stepless graduated. Our just think this kind of next one case: When the work out measures an order, be aimed at the attitude azimuth of the spare parts that be measured, we are configured and calibration became good the needs point of view that measure a head. Instantly the spare parts puts workbench to go up, when position of Dan Jizi state and a spare parts are abhorrent, the angle measuring a head before may no longer applicable. Accordingly, when doing batch to measure, we have the demand of certain level to azimuth of the position of the spare parts, attitude. And to 5 shaftings all, the requirement of this respect will be comfortable much, the stepless graduation character that measures a head makes measure what the head can fasten according to spare parts coordinate to search to be being made adjust accordingly, avoided to appear case of inapplicable of the angle that measure a head. [contact measures head and optics to measure a head] in recent years popularity is worn a few conduct propaganda that contain misdirect sex, bring about partial user to measure a head to have exorbitant expectation to optics, for example " measure a head to be swept with optics, all dimension of the spare parts came out " etc, this measures a misunderstanding with very actually large presence to optics. From current condition for, contact and optics are measured basically is mutual between the head additional relation, and rather than competes. Do that contact and optics measure a head to be in after all what respect can come true complementary? The sort that this still want to measure a head from optics speaks of. Three-dimensional optics measures a head to have different classification, for instance illuminant of point light source, line, face illuminant, measure an its application circumstance differently to have remarkable distinction. We measure optics the application of the head to divide two kinds roughly: The surface is digitlized and three-dimensional measure. Somebody can'ts help can having doubt: Is the surface digitlized and three-dimensional is measuring one and the same? Actually, divisional the key of two kinds of application depends on whether building digital surface model (Digital Surface Model) , namely the dot cloud that we often say or it is trigonometry reseau. It is of course among a lot of actual application, follow-up of generated digital surface model also can be used at the surface or diagnostic element is measured, but this kind measures mode is the spare parts model after be based on digitlization, measure diagnostic element with the tradition directly or have essential distinction. To exterior digitlization, its purpose is to should get outline of spare parts surface, the space that this needs to get outline in great quantities nods coordinate. And measure a head to contact for, the way that successive of many a dot gets is to cannot be competent of the requirement of check the number of hundred volume level, even if be successive scanning,measure a head, the way that just also does not leave spare parts outside through measuring a head will raise rate extraction a place, still be only place is collected substantially. Among this kind of application, illuminant of line illuminant knead dough measures a head very good the inadequacy that made up for contact to measure a head, line scanning measures a head to pass to move in workpiece surface by the laser of a certain number of dots, can scan give an area; And the face takes a picture measuring a head is the radial bar case that codes through a group, one-time get the dot cloud inside extent of a specific size. After getting digitlizing exterior model, the user can use data at all sorts of purposes, make contrast with CAD model for instance, get spare parts whole / the deviation of local outline, three-dimensional dimension is measured or converse project is waited a moment. But when this kind measures means to be used at dimension and behavior public errand to measure, cannot accord with the demand that gauges technological process normally (if build,measure element of fiducial, choice to plan to add up to a method, choose evaluation reference to wait a moment) . But, some spare partses or stem from spare parts characteristic, be like soft material the qualitative, surface that does not permit a contact, tiny feature, or stem from the demand that gauges efficiency, need to be not contact to measure really. To this kind of application, point light source measures a head very good also the inadequacy that made up for contact to measure a head. Actually, optics measures head photograph to measure a head to still have than contact on the other hand advantage. When contact measures a head to select a site, those who survey a record is the dimensional coordinate of the center that measure a ball, undertake compensating next according to measuring ball radius, reach bit actualer coordinate. But when the three-dimensional curve that should measure specific place, if do not select a site according to the normal way that measures a place, meeting existence radius compensates cosine error; And if go collecting according to the normal way that measures a place,nod, can arise to measure the situation of bit of position occurrence deviation actually again. When this kind of case is measuring turbine lamina particularly common. The reflection signal that is not contact optics to measure a head to use spot directly will get the coordinate that is measured to nod, link of nonexistent radius compensatory, because this can put an end to the fountainhead of cosine error generation completely. Moreover, when measuring mutability part, although measure power not quite, but spare parts or meeting are caused below the action of force be out of shape certainly (the thin lamina in laying a plan for example, measure when coping is sectional, the lamina when foliaceous basin is measured force to affect Chao Xie to carry direction on the back to bend, vice versa) . Although curve deflection not quite, but consider blade itself is paper-thin, it is very considerable that its are returned relative to deflection, can spend to the outline that reach spend with the position cause very big effect. Measure a head except the dot beyond, face illuminant takes a picture type measures a head to also can be had three-dimensional measure ability, but take a picture type measures a head to be in use as three-dimensional when measuring, do not be based on obtained dot cloud to undertake, rely on caught three-dimensional picture to extract the element that be measured directly however. And, should take a picture type measures a head to be used at three-dimensional when measuring, do not use alone, cooperate contact to measure a head one case however, measure a head to be in charge of building by contact measure fiducial, and take a picture type measures a head is to be aimed at feature of a few special elements (for example aperture, chamfer) undertake metrical. Although a few contact measure the advantage that the head cannot offer,optics measures a head, but cannot replace contact completely to measure a head, its reason depends on the light can touch the gender measures a head as contact. Measure each places of the ball can contact the object that be measured to select a site, but smooth transmission is the edge is sharp, we cannot let light " turn " , necessarily a few features let radial force place cannot be reached, for instance diameter compares very small hole greatly, or it is the need L situation that measures a needle, contact measures a head to measure a head than optics more convenient. [epilogue] did not measure a head best, do not have more measure a head all-purposely, how to choose to still depend on finally after all gauge demand. Before the sort measuring a head with complex numerous and complicated, do not be with the budget oriented, do not beg all-round model measure a head, ability finds truly right product, make good quality control very quickly again already. CNC Milling