厚度是测量最频繁的尺寸之一，也是非常容易理解的尺寸。所以您可能认为有人会想出一种适用于所有厚度的测量方法，但事实并非如此。根据零件的要求，测量厚度有很多种方法。
Thickness is one of the most frequently measured dimensions, and also one that is very easy to understand. So you might think that someone would come up with a one-style-fits-all measurement approach good for just about every kind of thickness application, but it just isn’t so. There are many approaches to measuring thickness, depending on the requirements of the part.
其中最常见的有：千分尺、厚度规、气动厚度规，自动化的量规和其他各种类似的方式。它们的价格和复杂性各不相同，从几百美元的标准手持工具，到几千美元的定制应用。而每个方案与其他解决方案有所不同的一个重要因素在于量具与工件的接触方式。
Some of the most common include: micrometers, thickness gages, air thickness gages and motorized gages with many variations of each. They range in price and complexity from a few hundred dollars for a standard handheld tool, to a few thousand dollars for ones that are custom-built for the application. One important consideration that makes each of these solutions different from the others is the way the gage makes contact with the part.
无论是一块金属片的厚度，硅片的厚度，乳胶手套还是感光胶片的厚度，我们通常谈论的是测量两个平行表面之间的距离。准确地确定一条垂直于两个平行表面的直线的长度与量具如何与工件接触息息相关。
Whether it's the thickness of a piece of sheet metal, a silicon wafer, a latex glove or photographic film, we are usually talking about measuring the distance between two parallel surfaces. Accurately determining the length of a line that is perpendicular to two parallel surfaces has everything to do with how the gage makes contact with the part.
千分尺 – 手持的千分尺是一种简单、低成本的用于测量例如较厚及坚硬的金属薄板厚度的方法。它提供了很多测量范围，通过平行的平测量面，并在摩擦或棘轮驱动下施加恒定的测量力，千分尺可以自行对准零件，实现快速准确的读数。千分尺的触点的一个潜在问题是，测头会覆盖一个微小的范围并“平均”出厚度。因此，如果需要更高的测量精度，您应该寻找不同的方法。
Micrometer. A handheld micrometer is a simple low-cost method for measuring the thickness of a piece of sheet metal, for example, which is relatively stiff and thick. It certainly provides a lot of measurement range. With flat and parallel contacts and constant gaging force applied with the friction or ratchet drive, the micrometer can self-align to the part for a fast and accurate reading. A potential problem with the self-aligning flat contacts of the micrometer is that they can bridge across and "average out" minute variations in thickness. So if higher resolution is required, you should look for a different approach.
测厚仪 - 便携式测厚仪通过以底部的平砧针为参考面与顶部的圆弧(球)测量触点相结合来提高分辨率。单点测量消除了可能由于接触面不平行而导致的测量误差。对于需要抽检厚度的条状薄膜，这将是一个很好的量规。
Thickness Gage. The portable thickness gage raises the ante on resolution by combining a flat anvil-type reference surface on the bottom with a radiused (ball) measurement contact on top. Making a single point measurement eliminates the possibility of gage error that could be caused by faulty parallelism of the contacts. This would be a good gage for a narrow strip of photographic film where a spot check of thickness is required.
气动测厚仪 - 在某些情况下，有些工件很容易被划伤或损坏，任何种类的接触测量都可能破坏这个工件。一个气动厚度测量系统将细小且精确排列的气流引导到与基准面垂直的工件两侧。压力计测量每个气流的回压。由于压力与接触点与喷嘴之间的距离成正比，因此很容易计算厚度。这种非接触技术为测量厚度变化提供了方法。在放置工件的时候，空气会产生气浮以提供足够的缓冲。差值测头的运用可以提供快速、准确的测量，无论零件如何放置。最重要的是，工件没有被量具的测头损坏。
Air Thickness Gage. In some cases the part may be so susceptible to scratching or marring that any amount of gaging contact could destroy the part. An air thickness gaging system directs thin, precision-aligned, opposing streams to each side of the part which is held perpendicular to the air streams on a ground base. The gage measures back pressure on each of the air streams. Since the back pressure is directly proportional to the distance between the contact point and the nozzle, it is easy for the gage to automatically calculate thickness. This non-contact technique provides a means of sliding the part around for measuring thickness variation. The air provides enough cushion to help float the part as it is repositioned. The use of differential probing provides fast, accurate measurement regardless of where the part is positioned. Most importantly, the part is not damaged by the gage contacts.
定制的测厚仪 - 许多软的、可形变的工件都有严格的、标准化的测量规范。在这种情况下，定制量规的设计通常将考虑到测头的大小和形状以及应用到部件上的压力。通常测力被定义为静态重力，以保证在整个测量范围内的恒定。然而，对于一些可压缩材料，如纸张或橡胶，施加在部件上的载荷的时间也会影响量规的读数。在这种情况下，量规可以与凸轮驱动装置结合在一起，在一段特定的时间后收回接触。这种均匀的负载和短暂的接触防止零件变形和塌陷。
Custom Thickness Gage. Many soft, compressible parts have rigid, standardized specifications for how they are to be measured. In such cases the design of custom gages will frequently take into consideration the size and shape of the contact along with the gaging pressure applied to the part. Usually the gaging pressure is defined as a dead load weight to assure constant force over the full range of measurement. However, with some compressible materials, such as paper or latex rubber, the amount of time that the load is applied to the part will also affect the reading from the gage. In these cases, the gage may incorporate a motorized measuring contact along with the cam actuated device to retract the contact after a specific period of time. This uniform load and dwell measurement prevents the parts from deforming and setting.
正如您所看到的，通过考虑测头的接触方法来考虑如何在广泛的应用中建立厚度测量系统是非常有用的。选择正确的方法可以极大地避免错误测量的机会。
As you can see, the method of probe contact is a very helpful way to consider how to set up thickness gaging systems across a wide range of applications. Choosing the right approach can dramatically decrease the chance of inadvertently making a bad measurement.
|
|
