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).
, \3 t4 @0 m. p6 V" s5 N0 y2 D5 ybillabong/ }. R0 o. _7 m! l4 {
标准球直径是否影响测量？因为我用2毫米直径产生了3微米误差.但是当我使用6毫米球形直径探针，误差达到了10个微米。（探针长度比先前大)
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Some things to consider here.9 W, n1 O% \% }& M; v9 a
Every probe ball ( stylus ) has some slight deviation from the nominal size.
5 W6 R# _4 a, s2 w+ f4 s3 gThere 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 (
3 u, X$ g8 C2 f, V! \8 n7 f$ h! T, G+ Q, |: V
Renishaw TP2 , TP 20 , TP200 etc ).
4 F' ~$ I$ J4 i* jAs long as you are calibrating them against a CALIBRATED masterball , ( o& J. T3 _0 |. ]( H
AND you have input the CALIBRATED masterball result ( from the certificate )
3 e3 T- ]' m* {5 Z0 |into your measuring software, you should not have to worry about a difference
% r" T' ? k; Iof 7 microns between styli.
2 |8 g# A$ E. j6 H3 SRemembering your attempts to calibrate the whole machine with gauge blocks, 2 J5 C% Y% W- ^& m! z( m- Q
I'd be surprised if you have the masterball calibrated. If you do, I stand corrected.
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在这里需要考虑部分因素
$ v0 [9 [0 l$ G每个实际探针与理论值都有一些微小的偏离。
9 p0 f/ L- Y: ]( r5 t/ r0 N探针将触发信号送到控制器之前，也有一些预行程。 行程的多少取决于你使用的测头.（Renishaw TP2,TP20,TP200 及其他）
$ G/ P2 t3 W+ F. J& j7 m, a. n0 i只要你用标准器标准球来校正他们 ，
0 X/ ]$ _+ D7 q7 R. D' s" m6 m5 L输入标准球的值（从证书） + x+ Y# O; R+ ~4 H9 h
打开你的测量软件，你没必要担忧探针偏差7个微米。 ' r# N3 p* K( p9 M& s' ~5 Z
记得尝试用标准度块校正整个的机器， $ T5 i5 I/ r( j1 p! O' q0 k
如果你校正标准球,我将会感到惊讶。 如果你做了，我认错。
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You need to get the basics of your machine correct 1st before questioning
o" G& k+ V/ b0 i I N' sany error or any accuracy issues you have.
! K2 _: j d- I5 g询问之前你需要第一时间得到你的机器的偏差
6 \7 |* ^" P# f- J5 J( \3 r无论任何错误或任何精度偏差。 1 I) u* L' p. u, d& t$ p
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Yes! the diameter of the tip ball gives an error which is known as "cosine error" see attached file.) D- \, J; e5 k$ E" I, c
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!
7 d& ]- z: w7 y B# PClick here for Tip_points.pdf
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. r$ U& M0 }8 n3 q是的,探针标准球给出一个误差以"cosine error " * Q' k# ]7 x4 B$ ]
我不知道你是怎么测量的，但是如果你用探针检查一个量块.但它不能给你偏差的不同！
$ Y! T; k5 n: C5 I" m点击这 Tip_points.pdf
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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. 7 P% G& P, y( R* C0 V
If 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.# V3 o g% t! k2 c3 E3 |9 t
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 3 V' F8 \$ U7 y2 @
length is by far the largest contributor. That is, assuming that cleanliness is under control.8 w3 @. F8 Y1 }) s( Q" I
) V( h- U2 y8 |1 j如果你尝试在其中特定z值平面内用一个2维测头测量一个3D立体圆锥体.那么探针直径将会影响精度。
6 i# X! R6 c# {' b: x& P如果你是检查已知项目的圆，例如环规，那么与探针的大小是没有关系的.除了一点小的不同,结果中较大的直径不容易像较小的直径一样的圆。
( y8 j, X1 a7 m. F对精度/重复度/偏差影响的最大的是探针的长度.这是更多复杂的,但一般来说，如果这 1" 长的探针误差为.0003偏差, 2" 长的探针将会是.0006 左右. 相同道理适用于关节臂测头。 从支点到探针顶端的距离越长，你标定的测头偏差越多。还牵涉许多其他的因素，但是探针长度是显然最大的因素。 如果其他因素可控的话 |
发表于 2009-3-7 20:09:53
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