The working principle of tea color sorter


Color selection technology refers to the use of special recognition lenses to capture pixel signals on the surface of materials, collect information on the reflected and transmitted light rate signals and other components of materials, and use computer control processing. Realize the exchange of photoelectric signals and compare them with standard signals to analyze the quality of materials. The tea color sorter is the application of color selection technology, which transmits feedback signals from the color selection technology to the overall control system of the color sorter. The overall control system uses an air compression jet gun to remove unqualified impurities from the material. The tea color sorter is a high-tech integrated technology that integrates optics, mechanics, electronics, and pneumatics. The tea color sorter is mainly composed of a swinging feeding hopper, a vibrating feeder, a chute slide, a light source, a background plate, a CCD detection lens, a good product tank, a first defective product tank, a second defective product tank, a jet nozzle, an air compressor, an air purifier, and a filter.

tea color sorter (3)

The feeding system consists of components such as a swinging feeding hopper, a vibrating feeder, and a chute slide. The tea materials to be sorted are fed into a vibrating feeder through a swinging hopper (after two vibrations, the tea leaves can be fully dispersed, making it easy to slide down in a single layer on the slide, which is conducive to detection and sorting). The materials are automatically arranged into continuous linear bundles through vibration and guiding mechanisms, and then accelerated through the material trough before falling into the detection area of the photoelectric sorting at a constant speed.

The photoelectric system is the core part of the color sorter. The light source mainly consists of a light source, a background plate, a CCD lens, and related auxiliary devices to provide stable and uniform illumination for the tested material and background plate. The CCD lens converts the reflected light of the tested material in the detection area into an electrical signal. The background board provides a reference signal for the electronic control system, and its reflective characteristics are basically equivalent to those of qualified products, but differ significantly from those of rejected objects.

The sorting system consists of accessories such as a good product tank, a first defective product tank, a second defective product tank, a jet valve, an air compressor, and an air filter purifier. Experimental results have shown that nozzle size and number of nozzles are one of the key factors affecting the accuracy of color sorting machines. The nozzle is too small, causing problems such as high precision and high processing costs; If the nozzle is too large, it will affect the accuracy and resolution, causing missed detections. The cleaning system consists of components such as cylinders and glass wipers.

Due to the generation of dust and other impurities that can easily adhere to glass during the color selection process of tea leaves. Once too much dust and impurities adhere to the window glass, the photoelectric system that sorts and detects tea materials through the window glass is prone to chain problems such as accidental shooting. Mild cases can have an impact on color selection accuracy and color selection output ratio, while severe cases can cause frequent operation of the nozzle, reduce the lifespan of the nozzle and control system, and even burn out the nozzle control system. The glass wiper is installed on the cylinder, and the central control system controls the cylinder valve switch according to the preset time to push the cylinder piston to slide, achieving the effect of timely cleaning of dust and impurities on the glass.

The swinging discharge system is driven by a motor to swing the discharge bin, allowing the final sorted tea material to be discharged from the machine and enter the next tea making process.

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The operating system adopts a large screen wide viewing angle color touch operation platform, which pre-set multiple color selection modes for customers and establishes a friendly human-machine interface, allowing for convenient and quick adjustment according to the specific situation of tea materials. The tea color sorting machine uses a color sorting photoelectric sensor/CCD lens to screen out objects of different colors in tea materials.

Due to the high susceptibility of tea leaves to breakage after drying, in order to improve color selection accuracy while ensuring the quality of tea materials, tea color selection machines generally choose multi-layer stepped mechanical structures. Before normal operation, the color selection mode and machine output should be set according to the proportion and type of defective tea materials. Then, the tea materials to be sorted are transported to the swinging feeding hopper of the color sorting machine through a dedicated tea elevator. The swinging feeding hopper is then fed to the vibrating feeder, and then the vibrating feeder is used to vibrate and feed the tea materials to the upper chute slide (i.e. the color sorting channel). The tea materials are arranged on the alignment track in the chute slide, forming a relatively uniform flow of tea materials. They slide down to the color sorting photoelectric sensor detection area or CCD lens detection sorting area for scanning, discrimination, and discrimination. Defective products in the tea material flow are removed by high-speed jet nozzles, and the tea materials sorted by the upper layer fall into the lower hopper and enter the lower chute slide. The color sorting photoelectric sensor detection area or CCD lens detection sorting area is used again for scanning, discrimination, and exclusion. After sorting, they are sorted into good products. Enter the next process with the secondary defective goods warehouse.

When selecting green tea stems, the color difference measurement system measures the color composition parameters of the tea leaves to determine the degree of green or yellow color deviation. Generally, the a value represents the degree of green color deviation, the 6 value represents the degree of yellow color deviation, and the L value represents the brightness of the tea leaves. There is a color difference between the tea strips and stems of all famous green teas, known as color difference. Generally, the tea strips have a green green color, while the stems have a yellowish color.

Therefore, when the color difference measurement system is used for measurement, tea leaves with a greenish color- The a value is also relatively high, and the more tender the tea strips, the higher the a value; Tea leaves that meet certain requirements will be captured by a tea camera equipped with a green color signal color difference sensing system using a color CCD lens, and then photographed. The photographed image will be input into a computer, and through calculation, instructions will be issued to allow the tea leaves to enter the second stem picking or discharge machine through the tea channel. In general, tea stems tend to be yellowish, with a higher value of 6. The older the tea stem, the more yellow the color, and the higher the b-value, making it easier to be captured and collected by a high-precision color difference sensing system equipped with yellow color signals, and input into a computer. The computer’s color CCD lens sends signal instructions to photograph the tea stem. Similarly, the photographed image is input into the computer, and through calculation, instructions are issued to turn on the high-speed solenoid valve. High pressure air is blown out through the pipeline and jet nozzle, blowing the tea stem out of the tea leaves, and discharged outside the machine through the tea stem channel and tea stem discharge port. Diagram 10-1 shows the working principle of the green tea color sorter. The color selection machine adopts two sets of mutually perpendicular feeding systems and a flat slide feeder, and can use a simple and easy to recognize touch key operation platform to adjust the color selection accuracy to a satisfactory state according to the different states of picking and grading.

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In tea processing, using a color sorter to pick out impurities such as tea stems not only has a good impurity removal effect and avoids excessive breakage of tea leaves, achieving high picking quality, high efficiency, and reduced tea production costs, but also optimizes the precision processing technology. The processing capacity of a tea color sorter is equivalent to that of a hundred picking workers, effectively activating the enterprise’s production capacity and greatly shortening the processing cycle. In addition, tea leaves are not picked by hand, avoiding potential contamination from manual picking and making them more hygienic and clean, achieving the goal of clean processing

由于茶叶在色选过程中会产生灰尘及其他易附着于玻璃上的杂质。窗口玻璃上一旦附着过多灰尘及杂质,透过窗口玻璃对茶物料进行分选检测的光电系统就会容易产生误枪等连锁问题。轻则对色选精度、色选带出比产生影响重则造成喷气嘴频繁工作,减少喷嘴及控制系统寿命,甚至烧毁喷嘴控制系统。玻璃雨刷器安装于气缸上,由总控系统按预设时间,通过控制气缸阀门开关,推动气缸活塞滑动,达到定时清扫玻璃上灰尘杂质的效果。