金属探测器是如何工作的？

How does a metal detector work?

工业金属探测器可有两种方式安装。可以在传送带上输送的产品上面或下面安装板式线圈。但更灵敏的探测器则应该让产品穿过线圈并将线圈安装于金属壳内。这种更灵敏的线圈型，其中通常装有3个线圈——1个中心发射线圈和2个绕向相反的接收线圈装在一个探头内。与中心线圈相连的振荡器产生一个高频磁场。而两个绕向相反接收线圈相互连接，以便在磁场未受干扰时可将它们所产生的感应电压自相抵消。

Industrial metal detectors can be installed in two ways. Can be transported on the conveyor belt are above or below the mounting plate coil. But a more sensitive detector should let the product pass through the coil and install the coil inside the metal shell. This kind of more sensitive coil type is usually equipped with 3 coils - 1 central transmitting coils and 2 opposite receiving coils mounted in one probe. The coil is connected with the central oscillator generates a high frequency magnetic field. The two opposite receiving coils are connected to each other so that the induced voltage can be automatically counteracted when the magnetic field is not disturbed.

为了获得最佳灵敏度，金属探测器的孔径尺寸应该与特定的产品大小相匹配。孔径太大，会有„削弱‟信号的危险；而孔径太小会不便于产品在传送带上通行。探测器的灵敏度通常是从由孔径的几何中心测量得来的 —— 最不敏感的几何点。当被金属污染的产品通过时，隐含的金属物对探测器的磁场产生干扰现象，两个接收线圈的输出信号不能相互抵消，从而探测出金属杂质的存在。

In order to obtain the best sensitivity, the aperture size of the metal detector should be matched with the specific size of the product. The aperture is too large, there will be a "dangerous" weakened signal; and the aperture is too small will not easily pass products on the conveyor belt. The sensitivity of the detector is usually measured from the geometric center of the aperture -- the least sensitive geometric point. When the metal contamination product passes, the hidden metal object interferes with the magnetic field of the detector, and the output signals of the two receiving coils can not cancel each other, so as to detect the existence of metal impurities.