技术文章
Technical articles We have talked many times in this column about the advantages air gaging brings to the manufacturing process, especially on the shop floor. In addition to their speed, ease of use and ability to automatically clean part surfaces before measuring, air gages are also capable of measuring to tighter tolerances than mechanical gages. At their very best, mechanical gages can measure down to 50 millionths, but that requires extreme care. Air gages handle 50 millionths with ease, and some will measure to a resolution of 5 millionths.
我们在Gaging Tips(测量技术)这个专栏里多次提到过气动量仪在生产过程尤其是车间里的测量优势:除了速度快、操作简便以及测头的自洁能力外;相较机械量规,气动量仪还能测量更小公差的工件;机械量规佳状况下可测到0.00005’,但测量过程需极其谨慎小心,而气动量仪则可轻松测到0.00005’,有时分辨率甚至可达0.000005’。
When most people think of air gaging, they think of plugs. But a number of air ring and air fork styles provide the same benefits and some additional ones as well.
一提到气动量仪,大部分人脑子里浮现出的是气动塞规,但其实很多气动环规和气动卡规也同样可实现或完成更多测量任务。
An air ring is the opposite of an air plug, and is primarily used to measure ODs. Air rings look quite simple—a steel ring with a pair of jets at a particular location—but there is a lot of engineering built into them. One trick is in calculating the size of the ring in order to achieve a good balance of clearance between the part and the opening in the ring. Too much clearance and your readout will start showing centralizing error. This happens when the part is shifted slightly in the tool and the air ring measures a chord rather than the diameter. Too little clearance and the indicator's range gets limited—or even worse—a geometry error can prevent the operator from inserting the part into the air tool.
与气动塞规测量内径刚好相反,气动环规主要用于外径测量。其外观看上去非常简单——在一个在特定位置有一对喷气孔的钢圈,但其实其内部设计十分复杂。其中一项设计是用来计算环规的大小以确保工件和环规之间的间隙达到合适的平衡:间隙太大读数经常容易出错,因为当工件轻微移动时,环规测量到的数据只是外圆的弦长而并非直径;若间隙太小,显示范围会受限甚至更糟——形位误差容易导致操作者无法将工件插入气动环规中。