Usually the metal detector consists of two parts, the metal detector and the automatic rejection device, where the detector is the core part. There are three groups of coils distributed inside the detector, namely the central transmitting coil and two equal receiving coils. The oscillator connected by the transmitting coil in the middle generates a high-frequency variable magnetic field, and the induced voltage of the receiving coils on both sides in the idle state. Before the magnetic field is disturbed, they cancel each other and reach an equilibrium state. Once metallic impurities enter the magnetic field, the magnetic field is disturbed, the balance is broken, the induced voltages of the two receiving coils cannot be cancelled, and the unsuppressed induced voltage is amplified by the control system and generates an alarm signal (metal impurities are detected. ). The system can use this alarm signal to drive automatic reject devices and the like to remove metal impurities from the production line. Divided by the transported mode of the detected object, the metal detector is usually divided into: channel type, fall type and pipeline type.
Channel Type Metal Detector Gantry Type Metal Detector The most common metal detection device on the market is a channel type metal detector. The detector has a square channel and is generally equipped with a conveyor belt mechanism, with automatic rejection device, or Alarm. When the items on the conveyor pass the detector, they are automatically rejected or stopped once they have metal. Mainly for on-line inspection of finished products and semi-finished products, provide final inspection before shipping. For example: bagged materials, boxed products and so on.
Drop-type metal detector Fall-type metal detectors are generally equipped with an automatic reject device, so it is customary to call a falling metal detector or a metal detector. Metal detectors require that the product be packaged without metal, but considering the high requirements of sealing and light protection, metal composite films must be used for packaging. The metal composite film itself is a metal, so if a channel type metal detector is used, the detection sensitivity will be greatly deviated and even impossible to detect. For these reasons, you can choose to test before packaging. Drop-type metal detectors were developed for these situations. They are mainly used for the detection of tablets, capsules, and granular (plastic particles, etc.) and powdered articles. When these items fall through the fall metal detector, once the metal impurities are detected, the system immediately activates the separation mechanism to remove the suspicious items. It has the characteristics of simple installation, high sensitivity, convenient maintenance, high efficiency, stability and reliability.
Pipeline Metal Detectors General metal detectors cannot monitor the entire production process of a fluid product, such as ham bolognese, chewing gum, oral liquids, etc., real-time online remove metal impurities, to ensure the safe delivery of products to the next process. In general, these products are packaged in metal, and they cannot be detected by metal detectors when they are finished. In addition, the detection of liquid or viscous articles before canning or packaging can effectively improve the detection accuracy. Falling Metal Detectors Whether in the food, pharmaceutical and rubber industries, or in the textile, paper, ore and recycling industries, we can provide metal detectors or separators that meet their requirements. In addition to the above-mentioned three types of channel-type, fall-type, and pipeline-type ideas, there are also pipeline-type, plate-type, etc. that are suitable for air-sending vacuum transmission.
Flat plate type: It is usually used to detect products with a relatively thin thickness but with a large width and length, such as a textile cloth and an extruded sheet. Its primary purpose is to protect downstream equipment, such as cutting tools, calendering systems, etc.; at the same time, improve product quality.
Metal detectors and separators are usually not affected by the installation direction and can be mounted horizontally, vertically and diagonally, and can be installed almost anywhere in the production process. Metal Detector Features and Concepts:
The accuracy and reliability of metal detectors depends on the stability of the frequency of the electromagnetic transmitter. Generally, the operating frequency is from 80 to 800 KHz. The lower the operating frequency, the better the iron detection performance; the higher the operating frequency, the better the detection performance of high carbon steel. The sensitivity of the detector decreases as the detection range increases, and the size of the sensing signal depends on the size of the metal particles and the conductivity.
Due to the pulsation of the current and the current filtering, the metal detector has a certain limit on the speed of detection of the article. If the conveying speed exceeds a reasonable range, the detector's sensitivity will decrease.
In order to ensure that the sensitivity does not drop, a suitable metal detector must be selected to accommodate the corresponding product being tested. In general, the detection range is as small as possible. For high-frequency induction products, the detector channel size should match the product size. The adjustment of the detection sensitivity is determined by referring to the center of the detection coil, and the center position is the lowest. The product's detection value will change with the production conditions, such as changes in temperature, product size, humidity, etc., can be adjusted through the control function to compensate for spherical reproducibility, the smallest surface area, the most difficult for metal detectors Testing. Therefore, the ball can be used as a reference sample for detection sensitivity. For non-spherical metals, the detection sensitivity largely depends on the position of the metal. Different locations have different cross-sectional areas and the detection results are different. For example, when passing longitudinally, iron is more sensitive; high-carbon steel and non-ferrous are less sensitive. When passing laterally, iron is less sensitive, and high-carbon steel and non-ferrous are more sensitive.
In the food industry, systems often use higher operating frequencies. For foods such as cheese, due to its inherent high-frequency induction performance, it will proportionally increase the response of high-frequency signals. Moist fatty or salty substances, such as bread, cheese, sausages, etc., have the same electrical properties as metals. In this case, in order to prevent the system from giving false signals, the compensation signal must be adjusted to reduce the sensitivity of the sensing.
The metal detector function is divided into: 1) All-metal detector: All metals such as iron, stainless steel, copper and aluminum can be detected. The detection accuracy and sensitivity are relatively high, stable and reliable. 2) Iron metal detector: only detect iron metal, commonly known as needle detector. The detection accuracy and sensitivity are low and easy to interfere. 3) Aluminum Foil Metal Detectors: Only ferrous metals can also be detected, but detection accuracy and sensitivity are still high when testing products with aluminum foil packaging.
Channel Type Metal Detector Gantry Type Metal Detector The most common metal detection device on the market is a channel type metal detector. The detector has a square channel and is generally equipped with a conveyor belt mechanism, with automatic rejection device, or Alarm. When the items on the conveyor pass the detector, they are automatically rejected or stopped once they have metal. Mainly for on-line inspection of finished products and semi-finished products, provide final inspection before shipping. For example: bagged materials, boxed products and so on.
Drop-type metal detector Fall-type metal detectors are generally equipped with an automatic reject device, so it is customary to call a falling metal detector or a metal detector. Metal detectors require that the product be packaged without metal, but considering the high requirements of sealing and light protection, metal composite films must be used for packaging. The metal composite film itself is a metal, so if a channel type metal detector is used, the detection sensitivity will be greatly deviated and even impossible to detect. For these reasons, you can choose to test before packaging. Drop-type metal detectors were developed for these situations. They are mainly used for the detection of tablets, capsules, and granular (plastic particles, etc.) and powdered articles. When these items fall through the fall metal detector, once the metal impurities are detected, the system immediately activates the separation mechanism to remove the suspicious items. It has the characteristics of simple installation, high sensitivity, convenient maintenance, high efficiency, stability and reliability.
Pipeline Metal Detectors General metal detectors cannot monitor the entire production process of a fluid product, such as ham bolognese, chewing gum, oral liquids, etc., real-time online remove metal impurities, to ensure the safe delivery of products to the next process. In general, these products are packaged in metal, and they cannot be detected by metal detectors when they are finished. In addition, the detection of liquid or viscous articles before canning or packaging can effectively improve the detection accuracy. Falling Metal Detectors Whether in the food, pharmaceutical and rubber industries, or in the textile, paper, ore and recycling industries, we can provide metal detectors or separators that meet their requirements. In addition to the above-mentioned three types of channel-type, fall-type, and pipeline-type ideas, there are also pipeline-type, plate-type, etc. that are suitable for air-sending vacuum transmission.
Flat plate type: It is usually used to detect products with a relatively thin thickness but with a large width and length, such as a textile cloth and an extruded sheet. Its primary purpose is to protect downstream equipment, such as cutting tools, calendering systems, etc.; at the same time, improve product quality.
Metal detectors and separators are usually not affected by the installation direction and can be mounted horizontally, vertically and diagonally, and can be installed almost anywhere in the production process. Metal Detector Features and Concepts:
The accuracy and reliability of metal detectors depends on the stability of the frequency of the electromagnetic transmitter. Generally, the operating frequency is from 80 to 800 KHz. The lower the operating frequency, the better the iron detection performance; the higher the operating frequency, the better the detection performance of high carbon steel. The sensitivity of the detector decreases as the detection range increases, and the size of the sensing signal depends on the size of the metal particles and the conductivity.
Due to the pulsation of the current and the current filtering, the metal detector has a certain limit on the speed of detection of the article. If the conveying speed exceeds a reasonable range, the detector's sensitivity will decrease.
In order to ensure that the sensitivity does not drop, a suitable metal detector must be selected to accommodate the corresponding product being tested. In general, the detection range is as small as possible. For high-frequency induction products, the detector channel size should match the product size. The adjustment of the detection sensitivity is determined by referring to the center of the detection coil, and the center position is the lowest. The product's detection value will change with the production conditions, such as changes in temperature, product size, humidity, etc., can be adjusted through the control function to compensate for spherical reproducibility, the smallest surface area, the most difficult for metal detectors Testing. Therefore, the ball can be used as a reference sample for detection sensitivity. For non-spherical metals, the detection sensitivity largely depends on the position of the metal. Different locations have different cross-sectional areas and the detection results are different. For example, when passing longitudinally, iron is more sensitive; high-carbon steel and non-ferrous are less sensitive. When passing laterally, iron is less sensitive, and high-carbon steel and non-ferrous are more sensitive.
In the food industry, systems often use higher operating frequencies. For foods such as cheese, due to its inherent high-frequency induction performance, it will proportionally increase the response of high-frequency signals. Moist fatty or salty substances, such as bread, cheese, sausages, etc., have the same electrical properties as metals. In this case, in order to prevent the system from giving false signals, the compensation signal must be adjusted to reduce the sensitivity of the sensing.
The metal detector function is divided into: 1) All-metal detector: All metals such as iron, stainless steel, copper and aluminum can be detected. The detection accuracy and sensitivity are relatively high, stable and reliable. 2) Iron metal detector: only detect iron metal, commonly known as needle detector. The detection accuracy and sensitivity are low and easy to interfere. 3) Aluminum Foil Metal Detectors: Only ferrous metals can also be detected, but detection accuracy and sensitivity are still high when testing products with aluminum foil packaging.