At present, the most common metal detection equipment on the market is the channel metal separator. The channel of the detector is square. Generally, it is equipped with conveyor belt mechanism, with automatic eliminating device, or provides alarm signal.
When the goods on the conveyor belt pass through the detector, once there is metal, they will automatically remove or stop conveying. Mainly for on-line inspection of finished and semi-finished products, provide final inspection before shipment.
Ferromagnetic metals entering the detection area will affect the distribution of magnetic lines in the detection area, and then affect the flux in a fixed range. Non-ferromagnetic metals entering the detection area will produce eddy current effect and change the magnetic field distribution in the detection area. Usually the metal separator consists of two parts, namely, metal separator and automatic removal device, in which the detector is the core part.
There are three groups of coils inside the detector, namely the central transmitting coil and two equivalent receiving coils. The high frequency variable magnetic field is generated by the oscillator connected by the middle transmitting coil. In idle state, the inductive voltage of the receiving coils on both sides cancels each other before the magnetic field is disturbed and reaches the equilibrium state.
Once the metal impurities enter the magnetic field area, the magnetic field is disturbed, the balance is broken, the inductive voltage of the two receiving coils can not be offset, the uncoupled inductive voltage is amplified by the control system, and an alarm signal is generated (metal impurities are detected). The system can use the alarm signal to drive the automatic eliminating device and so on, so as to exclude metal impurities from the production line.