does probe ball dia affects the measurent?because i have a probe with 2 mm dia and its giving 3 microns error but as i use the 6 mm ball dia probe , the error goes to 10 microns (its stem length is also bigger than the previous probe).
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; O% A3 @, P; v0 r: q+ d" M! p標準球直徑是否影響測量,？因為我用2毫米直徑產(chǎn)生了3微米誤差.但是當我使用6毫米球形直徑探針，誤差達到了10個微米,。（探針長度比先前大)
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! S' E6 S7 K: L" T" m5 `' sSome things to consider here.: F# c& g* s0 ?. b1 S! L
Every probe ball ( stylus ) has some slight deviation from the nominal size. 7 J1 F+ ^. l. g7 l# _ @) Y6 w4 O2 ^
There is also some pre-travel before the touch trigger probe sends the signal to the controller. How much depends on which touch trigger probe you have (
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Renishaw TP2 , TP 20 , TP200 etc ).
7 d$ |. p" b: NAs long as you are calibrating them against a CALIBRATED masterball , 0 G3 Q* {8 m5 |+ Y. t
AND you have input the CALIBRATED masterball result ( from the certificate )
* B: F, \# L: O: ?3 z/ Zinto your measuring software, you should not have to worry about a difference 1 c2 s( I( _ }& ?% ^9 G5 _, G9 l
of 7 microns between styli.
4 X4 K: j0 c( u* j% V, pRemembering your attempts to calibrate the whole machine with gauge blocks,
, L2 O2 `4 m: F2 a6 |I'd be surprised if you have the masterball calibrated. If you do, I stand corrected.
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在這里需要考慮部分因素1 B# V6 N! z$ u! ^# r
每個實際探針與理論值都有一些微小的偏離,。 # L% @! b5 Z& B5 `% w a" K% D
探針將觸發(fā)信號送到控制器之前，也有一些預行程,。 行程的多少取決于你使用的測頭.（Renishaw TP2,TP20,TP200 及其他）; {4 o3 c$ [' }/ s, h" a
只要你用標準器標準球來校正他們 ,，
3 I- w; @, b9 q- s. {; Q* }輸入標準球的值（從證書）
' q/ U* a/ Z8 M& a3 {- S打開你的測量軟件，你沒必要擔憂探針偏差7個微米,。
0 C8 Z3 a8 L L3 Y, Z B記得嘗試用標準度塊校正整個的機器,，
4 i# p) b- \* I3 @. M如果你校正標準球,我將會感到驚訝。 如果你做了,，我認錯,。 ; r' z% w( _: ?% T+ M
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You need to get the basics of your machine correct 1st before questioning1 ~ A; A/ S# w& ~8 M
any error or any accuracy issues you have.
2 ]4 r) [. S- b% c7 u" q詢問之前你需要第一時間得到你的機器的偏差. w; {, g2 h# s0 u/ s( n
無論任何錯誤或任何精度偏差。 5 ?+ n+ |7 L& M# \" V5 p3 s. j8 O
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Yes! the diameter of the tip ball gives an error which is known as "cosine error" see attached file.
' S$ R3 v9 ~0 b8 C& y, ^I don't know what you are measuring but if you check a gauge block with tip dia. 2/6 it should NOT give you that difference in error!
2 |% x5 R( s" y) H3 n ~2 XClick here for Tip_points.pdf , x. R3 _+ ^9 F _; X
6 ? h+ E/ k9 l4 H; i. X9 W是的,探針標準球給出一個誤差以"cosine error "
% Z( ^0 J7 N; O; C9 F* C( A我不知道你是怎么測量的,，但是如果你用探針檢查一個量塊.但它不能給你偏差的不同,！! N9 c ?0 r0 C% p" r
點擊這 Tip_points.pdf ) A/ y- p, O! { j
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If you're trying to check a 3D cone as a 2D dia at a certain Z level then, yes probe diameter will affect accuracy.
. u% U/ w3 p" ~2 cIf you're look at roundness of a known round item, say a ring gage, then the size of the tip doesn't matter except that larger diameters tend to not be as round as smaller diameters but this is generally a relatively small difference.% }2 G$ \5 i6 {$ I* p8 s
The biggest thing that affects accuracy/repeatability/tri-lobing is the length of the stylus. It's much more complicated but generally speaking, if a 1" long stylus results in .0003 of tri-lobing, a 2" long stylus will be around .0006. The same basic concept applies to articulating probe heads. The longer the distance from the fulcrum to the prope tip, the more variance you will have when indexing the probe head. There are many other factors involved but the probe : H! X$ t3 b' T
length is by far the largest contributor. That is, assuming that cleanliness is under control.
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! I4 L# Y" _- j: [6 q如果你嘗試在其中特定z值平面內(nèi)用一個2維測頭測量一個3D立體圓錐體.那么探針直徑將會影響精度。 3 D, y- L4 p) S) F/ T4 C. u
如果你是檢查已知項目的圓,，例如環(huán)規(guī),，那么與探針的大小是沒有關(guān)系的.除了一點小的不同,結(jié)果中較大的直徑不容易像較小的直徑一樣的圓。
2 \: V& f, o+ q) [0 J對精度/重復度/偏差影響的最大的是探針的長度.這是更多復雜的,但一般來說,，如果這 1" 長的探針誤差為.0003偏差, 2" 長的探針將會是.0006 左右. 相同道理適用于關(guān)節(jié)臂測頭,。 從支點到探針頂端的距離越長,，你標定的測頭偏差越多。還牽涉許多其他的因素,，但是探針長度是顯然最大的因素,。 如果其他因素可控的話 |
發(fā)表于 2009-3-7 20:09:53
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