Classification and precautions of the hottest gran

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Classification and precautions of granulator

underwater granulator is similar to pneumatic granulator and water spray granulator, except that it has a steady water flow through the mold surface and is in direct contact with the mold surface. The size of the pelletizing chamber is just enough to enable the pelletizer to rotate freely across the die surface without restricting the water flow. The molten polymer is extruded from the die, and the granular material is cut by the rotary knife. The granular material is brought out of the pelletizing chamber by the temperature adjusted water and enters the centrifugal dryer. In the dryer, the water is discharged back to the storage tank, cooled and recycled; The pellets are removed by centrifugal dryer

the strip production line is low cost, easy to operate, and convenient to clean. This has its advantages for color mixing, because the replacement of two batches of different colors must thoroughly clean the equipment. However, the disadvantage of the strip making method is that the cooling section needs to occupy space, and its length is determined according to the temperature requirements of the polymer. Most polymers must be mixed before being made into final products, and then granulated to become marketable raw materials. The power required by the granulator is directly proportional to the extrusion volume and exponentially related to the filter size. There are many different granulator designs, but all granulators can be divided into two categories: cold pelletizing system and die surface hot pelletizing system. The main difference between the two is the time arrangement of the granulation process. The cold granulation system cuts particles from the cured polymer at the end of the processing process; In the upper system of the hot-rolled particles on the die surface in the booth of Harbin Institute of technology, when the molten polymer appears from the die, it is necessary to cut the particles, and it is necessary to establish a modern new concept to cool the particles in the downstream. The two pelletizing systems have their own advantages and disadvantages

cold pelletizing system: the cold pelletizing system includes die, cooling area (air cooling or water cooling), drying area (if water cooling is used) and pelletizing chamber. There are two types of cold pelletizing systems, namely, tablet granulator and strip granulator

the molten polymer is extruded from the hot die and cut into pellets by the rotary knife rotating on the die surface. This sweet granule system is characterized by its specially designed water jet pelletizing chamber. The water flows in a spiral until it flows out of the sweet grain chamber. After the granular material is cut, it is thrown into the water flow for preliminary quenching. The granular slurry is discharged into the granular slurry tank for further cooling, and then sent to the centrifugal dryer to remove water

the use history of bar granulator is almost as long as that of tablet granulator. It includes die, cooling section (water bath or blower), drying section (if water cooling is used) and pelletizer. Extrude the molten polymer with an extruder or gear pump and form strips through a horizontally installed die (the modern die is precision machined and evenly heated to produce strips with stable quality). After the strip is discharged from the mouth, it is cooled by blower or air/vacuum facilities, or by water bath. If water cooling is used, the strips need to pass through a drying section, blow out the moisture with forced ventilation, and then send the strips to the pelletizing chamber. Using the shearing action of a pair of fixed knives and rotary knives, the strip is accurately cut into the required length

I. precautions

1. The granulator should operate in a positive direction; Avoid inversion

2. The granulator must not be operated on an empty stomach by the cooler, but must be operated with hot machine feeding, so as to avoid stick bar (shaft holding) phenomenon

3. It is strictly forbidden to enter ironware and other sundries in the feed inlet and vent hole of the granulator. So as not to cause accidents and affect production

it can meet the durability test, the detection of the relationship between tightening range and pressure, and the detection of spring tightening under specific pressure. II. Precautions during the operation of the granulator

1. Pay attention to the temperature change of the machine body at any time. When touching the strip with clean hands, it should be heated immediately. It is normal until the strip touches your hand

2. When the reducer bearing is burned or accompanied by noise, it should be repaired in time and refueled

3. When the bearings at both ends of the main engine bearing room are hot or noisy, stop the machine for maintenance and add butter. During normal operation, add grease to the bearing chamber every other day

4. Pay attention to the operation law of the machine; For example, if the machine temperature is high or low, and the speed is fast or slow, it can be handled in time according to the situation

5. When the fuselage is unstable, pay attention to check whether the gap of the coupling fitting is too tight, and adjust it in time

III. for the first time, Gao Fang et al. Discussed the use of PMMA artificial eye tablets in the beauty of acquired eyeball loss caused by eye trauma, eye tumor and other reasons. The results showed that 1155 cases of artificial eyes made of PMMA materials had no crowding reaction, and could be comparable with healthy eyes in color and transparency. Combined with hydroxyapatite artificial eye platform implantation, it could achieve the effect of simulation activities. Startup operation method

1. Before startup, the temperature should be increased for about 40 or 50 minutes. Raise the temperature until the motor triangle belt is pulled by hand until it is free; Pull it continuously for eight to ten times according to the normal working direction. Then continue to heat up for about ten minutes, and then start the machine, but continue to heat up, because normal production needs to continue to supplement heat; Adjust different temperatures according to different plastics

2. When the granulator works normally, the machine temperature should be kept stable, and should not be high or low. The temperature near the vent hole until the machine head should be maintained at about 200 ℃ (referring to material C and material b)

3. Feed evenly and add enough. The feeding speed of the machine should match the feeding speed properly. Otherwise, the quality and output of particles will be affected

4. When the machine is shut down, the power supply of the main machine should be completely cut off. The head plug (with wrench) must be removed. Preheat separately before the next use

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