Detection head and sensitivity of food metal detector
The typical structure of the detector head of the food metal detector is rectangular shape. The main parts of the metal detector are filled in a box made of metal (generally stainless steel), which plays a protective role for the detection coil. Then the four surfaces of the channel are lined with non-metallic materials (generally plastic materials) to ensure that there is a closed, anti-interference and insulated working environment for the internal components of the detector head.
At present, for the vast majority of food metal detector, its working principle is basically the same, generally using the principle of electromagnetic induction. In order to obtain a good detection sensitivity when purchasing metal detection instruments, the manufacturer should customize the metal detection system (such as the opening size of the detection head) according to your specific application requirements.
Generally, the food metal detector is installed and used in two different ways as required:
1) transport the product through the conveyor belt on the assembly line, and place the plate type detection coil on or below it. In this way, check whether the product has been mixed with metal foreign matters. The disadvantage of this detector is that it is not sensitive enough.
2) another installation method is to let the product pass through the detection area. The food metal detector should install the detection coil inside the metal shell. This installation method belongs to the sensitive coil structure. Three groups of coils are usually fixed in the shell, one of which is the intermediate transmitting coil, and two receiving coils are installed in a detection head. The high frequency magnetic field is generated after the oscillator connected with the intermediate coil is electrified, while the other two reverse winding receiving coils are respectively connected with each other, so as to ensure that the static induction voltage generated by them can cancel each other when there is no interference from the surrounding magnetic field.
As for the sensitivity of the food metal detector, it is very important to ensure that it can achieve the best detection effect, so that the channel size of the metal detector and the size of the product to be tested are in the appropriate proportion. The middle position is the weakest point of the instrument detection accuracy (sensitivity), so the empty machine sensitivity of the instrument is measured with the geometric center of the channel as the reference point. The accuracy that the instrument can achieve is inversely proportional to the opening size of the channel size, and the main influencing factor is that the channel height (that is, the smaller one of the channel size) affects the detection sensitivity.
When ordering food metal detector, in order to obtain the best sensitivity, the aperture size of metal detector should match the product size of its own enterprise. If the aperture is too large, the signal will be weakened, so as to reduce the detection sensitivity. If the aperture is too small, the product will not pass through the conveyor belt smoothly.