如何測量孔、管和筒內(nèi)徑的軸向直線度

How to measure axial straightness of bore, tube, and barrel IDs

如何測量孔、管和筒內(nèi)徑的軸向直線度

Axial (or axis) straightness is a tolerance that controls how much a part’s axis is allowed to curve.

軸向（或軸線）直線度是一個公差，用于控制零件的軸線允許彎曲的程度。

Measuring axial straightness of bore, tube, and barrel IDs is often critical to ensuring proper component function. While
measurements in such tight spaces can be challenging for many instruments, Novacam 3D metrology systems obtain these measurements rapidly, in a non-contact automated manner, and with micron (and often sub-micron) precision.

測量孔、管和筒 ID 的軸向直線度通常對于確保正確的零件功能至關(guān)重要。雖然在如此狹小的空間中進(jìn)行測量對于許多儀器來說可能具有挑戰(zhàn)性，但 Novacam 3D 計量系統(tǒng)以非接觸式自動方式快速獲得這些測量值，并且具有微米（通常是亞微米）的精度。

How is this done?

這是怎么做到的？

Small probes for narrow spaces

適用于狹窄空間的小型探頭

Novacam provides two 3D metrology systems for measuring inside diameters (IDs): the
BoreInspect
and
TubeInspect.
Both systems use small-diameter side-looking optical probes that come in a range of sizes and lengths. (As of today, the thinnest probe, with 0.5 mm diameter, measures IDs as small as 1 mm.)

Novacam 提供兩種用于測量內(nèi)徑 (ID) 的 3D 計量系統(tǒng)：BoreInspect和TubeInspect。兩種系統(tǒng)都使用具有各種尺寸和長度的小直徑側(cè)視光學(xué)探頭。（截至目前，直徑為 0.5 毫米的最細(xì)探頭可測量小至 1 毫米的內(nèi)徑。）

To acquire surface measurements, the side-looking probe shines a beam of light at the ID surface and collects the signal reflected back from the surface.
While the probe traces a predetermined path through the ID, measurements are done in a point-by-point manner at a rate of up to 100,000 3D points per second.
The path may be linear, circular or spiral.

為了獲得表面測量值，側(cè)視探頭將一束光照射到 ID 表面并收集從表面反射回來的信號。當(dāng)探頭追蹤通過 ID 的預(yù)定路徑時，測量以每秒高達(dá) 100,000 個 3D 點的速度逐點進(jìn)行。該路徑可以是線性的、圓形的或螺旋形的。

For the fastest axial straightness measurement, the operator would request 3 distinct circular profiles of the ID.

對于最快的軸向直線度測量，操作員會要求 3 個不同的 ID 圓形輪廓。

TubeInspect small-diameter probe about to enter a 5.6-mm diameter bore

TubeInspect 小直徑探頭即將進(jìn)入 5.6 毫米直徑的孔

Axial straightness calculation

軸向直線度計算

Axial straightness is a 3D tolerance. The axis being controlled must lie within the volume of a cylinder defined by the tolerances.

軸向直線度是 3D 公差。被控制的軸必須位于由公差定義的圓柱體內(nèi)。

From the 3D point cloud data generated by Novacam 3D metrology systems, the component axial straightness is calculated by
geometrical dimensioning and tolerancing (GD&T) software (typically PolyWorks InspectorTMsoftware).

根據(jù) Novacam 3D 計量系統(tǒng)生成的 3D 點云數(shù)據(jù)，通過幾何尺寸和公差 (GD&T) 軟件（通常是 PolyWorks Inspector TM軟件）計算零件軸向直線度。

The two images below show axial straightness measurements calculated from 1)
3 circular profiles, which is the most time-efficient method, and 2) from a high-density spiral scan of the ID.

下面的兩張圖片顯示了通過 1) 3 個圓形輪廓計算的軸向直線度測量值，這是最省時的方法，以及 2) 通過 ID 的高密度螺旋掃描計算得出。

Bore ID straightness from 3 profiles

來自 3 個剖面的孔徑直線度

Straightness deviation map generated from a high density spiral scan.

由高密度螺旋掃描生成的直線度偏差圖。

Precision of measurement

測量精度

With Novacam ID measurement systems, the repeatability (standard deviation of type1 Gauge R&R) of straightness measurements is typically better than 0.5 μm (0.00002”). Here is an example:

使用 Novacam ID 測量系統(tǒng)，直線度測量的可重復(fù)性（1 型量規(guī) R&R 的標(biāo)準(zhǔn)偏差）通常優(yōu)于 0.5 μm (0.00002”)。這是一個例子：

The TubeInspect was used to measure GD&T straightness of two bores. The operator repeated the measurement 10 times for each bore and then used PolyWorks InspectorTM
software for straightness calculation and reporting.
Here are the results:

TubeInspect 用于測量兩個孔的 GD&T 直線度。操作員對每個孔重復(fù)測量 10 次，然后使用 PolyWorks Inspector
TM軟件進(jìn)行直線度計算和報告。以下是結(jié)果：

Repeatability (standard deviation of type1 Gauge R&R) of axial straightness measurement

軸向直線度測量的重復(fù)性（type1 Gauge R&R 的標(biāo)準(zhǔn)偏差）

All measurements can be automated

所有測量都可以自動化

Parts with tight GD&T straightness tolerances include automotive or aerospace valves valves, shafts, hydraulic cylinders, medical tubes, zirconium tubes,
safety valves, fuel rails, defense bores and barrels, and extruder dies.

具有嚴(yán)格 GD&T 直線度公差的零件包括汽車或航空航天閥門、軸、液壓缸、醫(yī)療管、鋯管、安全閥、燃料導(dǎo)軌、防御孔和桶以及擠壓機(jī)模具。

With both
BoreInspect
and
TubeInspect,
users easily automate the entire process of ID scanning, straightness calculation, and the reporting, with go-no-go value assignment. The same goes for the measurement of other GD&T parameters such as ID or OD roundness, concentricity, cylindricity, etc. But we will leave discussions of those parameters for another day.

借助BoreInspect和TubeInspect，用戶可以輕松地實現(xiàn) ID 掃描、直線度計算和報告的整個過程的自動化，并通過 go-no-go 賦值。這同樣適用于其他 GD&T 參數(shù)的測量，例如 ID 或 OD 圓度、同心度、圓柱度等。我們將改期討論這些參數(shù)。

文件：AN-THICKNESS-1.2（2021-06-03）

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