如何测量孔、管和筒内径的轴向直线度

2023-07-03 18:03

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

如何测量孔、管和筒内径的轴向直线度

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

轴向(或轴线)直线度是一个公差,用于控制零件的轴线允许弯曲的程度。

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.

测量孔、管和筒 ID 的轴向直线度通常对于确保正确的零件功能至关重要。虽然在如此狭小的空间中进行测量对于许多仪器来说可能具有挑战性,但 Novacam 3D 计量系统以非接触式自动方式快速获得这些测量值,并且具有微米(通常是亚微米)的精度。

How is this done?

这是怎么做到的?


Small probes for narrow spaces

适用于狭窄空间的小型探头

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 提供两种用于测量内径 (ID) 的 3D 计量系统:BoreInspectTubeInspect。两种系统都使用具有各种尺寸和长度的小直径侧视光学探头。(截至目前,直径为 0.5 毫米的最细探头可测量小至 1 毫米的内径。)

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.

为了获得表面测量值,侧视探头将一束光照射到 ID 表面并收集从表面反射回来的信号。当探头追踪通过 ID 的预定路径时,测量以每秒高达 100,000 个 3D 点的速度逐点进行。该路径可以是线性的、圆形的或螺旋形的。

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

对于最快的轴向直线度测量,操作员会要求 3 个不同的 ID 圆形轮廓。

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

TubeInspect 小直径探头即将进入 5.6 毫米直径的孔

Axial straightness calculation

轴向直线度计算

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

轴向直线度是 3D 公差。被控制的轴必须位于由公差定义的圆柱体内。

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 Inspector
TMsoftware).

根据 Novacam 3D 计量系统生成的 3D 点云数据,通过几何尺寸和公差 (GD&T) 软件(通常是 PolyWorks Inspector TM软件)计算零件轴向直线度。

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.

下面的两张图片显示了通过 1) 3 个圆形轮廓计算的轴向直线度测量值,这是最省时的方法,以及 2) 通过 ID 的高密度螺旋扫描计算得出。

Bore ID straightness from 3 profiles

来自 3 个剖面的孔径直线度

Straightness deviation map generated from a high density spiral scan.

由高密度螺旋扫描生成的直线度偏差图。

Precision of measurement

测量精度

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 测量系统,直线度测量的可重复性(1 型量规 R&R 的标准偏差)通常优于 0.5 µm (0.00002”)。这是一个例子:

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 用于测量两个孔的 GD&T 直线度。操作员对每个孔重复测量 10 次,然后使用 PolyWorks Inspector
TM软件进行直线度计算和报告。以下是结果:

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

轴向直线度测量的重复性(type1 Gauge R&R 的标准偏差)

All measurements can be automated

所有测量都可以自动化

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.

具有严格 GD&T 直线度公差的零件包括汽车或航空航天阀门、轴、液压缸、医疗管、锆管、安全阀、燃料导轨、防御孔和桶以及挤压机模具。

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BoreInspectTubeInspect,用户可以轻松地实现 ID 扫描、直线度计算和报告的整个过程的自动化,并通过 go-no-go 赋值。这同样适用于其他 GD&T 参数的测量,例如 ID 或 OD 圆度、同心度、圆柱度等。我们将改期讨论这些参数。


文件:AN-THICKNESS-1.22021-06-03

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