Know internal mixer and daily operation process
Time of issue：
2022-11-29
The closed rubber mixer is referred to as the internal mixer, which is mainly used for plasticizing and mixing of rubber.
1. Know the internal mixer
The closed rubber mixer is referred to as the internal mixer, which is mainly used for plasticizing and mixing of rubber. the
Internal mixer is a kind of machine with a pair of rotors with specific shape and relative rotation, which intermittently plasticizes and kneads polymer materials in a closed state with adjustable temperature and pressure. It is mainly composed of a mixing chamber, a rotor , Rotor sealing device, feeding and pressing device, unloading device, transmission device and machine base and other parts. the
The internal mixer is a high-strength intermittent mixing equipment developed on the basis of the open mixer. Since the emergence of the real Banbury (Benbury) type internal mixer in 1916, the power of the internal mixer has gradually been recognized by people. It shows a series of characteristics superior to the open mixer in the rubber mixing process. Such as: large mixing capacity, short time, high production efficiency; better overcome dust flying, reduce loss of compounding agents, improve product quality and working environment; safe and convenient operation, reduce labor intensity; beneficial to realize mechanical and automatic operation, etc. . Therefore, the emergence of the internal mixer is an important achievement of rubber machinery, and it is still a typical important equipment in mastication and mixing, and it is still developing and improving.
Basic knowledge of internal mixer Basic structure
The internal mixer is generally composed of a mixing chamber, two relatively rotating rotors, an upper top bolt, a lower top bolt, a temperature measurement system, a heating and cooling system, an exhaust system, a safety device, a discharge device and a recording device. There are spiral ribs on the surface of the rotor, and the number of ribs is two-sided, four-sided, six-sided, etc. The cross-sectional geometry of the rotor is triangular, cylindrical or elliptical, and there are two types: tangential type and meshing type. . The temperature measurement system is composed of thermocouples, which are mainly used to measure the temperature change in the mixing chamber during the mixing process; the heating and cooling system is mainly to control the temperature of the rotor and the surface of the mixing chamber wall.
Working principle of open mill
When the internal mixer is working, the two rotors rotate relative to each other, and the material from the feeding port is clamped and brought into the roll gap to be squeezed and sheared by the rotors. After passing through the roll gap and touching the sharp edge of the lower top bolt, it is divided into two parts, Return to the top of the roll gap along the gap between the front and rear chamber walls and the rotor. During the cycle of flowing around the rotor, the material is subjected to shearing and friction everywhere, so that the temperature of the rubber material rises sharply, the viscosity decreases, and the wettability of the rubber on the surface of the compounding agent is increased, so that the rubber and the surface of the compounding agent are in full contact. Compounding agent agglomerates pass through the gap between the rotor and the rotor, the gap between the rotor and the upper and lower top bolts, and the inner wall of the mixing chamber together with the rubber, and is broken by shearing, surrounded by stretched and deformed rubber, and stabilized in a broken state. At the same time, the ribs on the rotor make the rubber material move along the axial direction of the rotor, which plays a role of stirring and mixing, so that the compounding agent is evenly mixed in the rubber material. The compounding agent is repeatedly sheared and broken in this way, the rubber material is repeatedly deformed and restored, and the rotor ribs are constantly stirred to make the compounding agent evenly dispersed in the rubber material and reach a certain degree of dispersion. Since the shearing effect on the rubber material in the internal mixer is much greater than that in the open mixer, and the temperature of the rubber mixing is high, the efficiency of the rubber mixing in the internal mixer is much higher than that in the open mixer.
Preparations before dry running test of internal mixer
1: The dry running test of the internal mixer must be carried out after the foundation is completely dry. the
2: Check whether there is any foreign matter in each part of the internal mixer, and whether there is any looseness in the joints and fasteners. the
3: Check whether the lubricating pipelines and hydraulic pipelines of the internal mixer are connected correctly, whether the amount of lubricating and hydraulic oil used is appropriate, whether the oil level is appropriate, and whether the lubrication of the lubricating parts is in place. the
4: The auxiliary equipment of the internal mixer needs to be inspected and tested separately before running dry to verify whether its performance meets the specified requirements. the
5: Check whether the coordination between the electrical equipment of the internal mixer and the hydraulic system and air control system is correct. the
6: Before the internal mixer is connected to the coupling, first idle the main motor for 20 minutes, and then install the coupling and install the protective cover after there is no abnormality.
7: At the high-speed shaft end of the main reducer of the internal mixer or at the coupling, manually rotate the transmission system to make the rotor rotate for two weeks, and confirm that there is no abnormal phenomenon.
Precautions for daily operation of internal mixer
1. In the first week of production, the fastening bolts of each part of the mixer need to be tightened at any time, and then tightened once a month. the
2. In the case of low temperature, in order to prevent the pipeline from freezing, it is necessary to drain the cooling water from each cooling pipeline of the machine, and spray the cooling water pipeline clean with compressed air. the
3. Shut down according to the requirements of refining the last car material during the load test run. After the main motor stops, turn off the lubricating motor and the hydraulic motor, cut off the power supply, and then turn off the air source and cooling water source. the
4. When the weight of the machine is in the upper position, the discharge door is in the closed position and the rotor is rotating, the feeding door can be opened to feed materials into the mixing chamber. the
5. When the internal mixer is temporarily stopped for some reason during the mixing process, the main motor must be started after the rubber material in the internal mixing room must be discharged after troubleshooting. the
6. The feeding volume of the mixing chamber shall not exceed the design capacity, the current at full load shall generally not exceed the rated current, the instantaneous overload current shall generally be 1.2 to 1.5 times the rated current, and the overload time shall not exceed 10s. the
7. For large-scale internal mixers, the mass of rubber blocks should not exceed 20kg when feeding, and the temperature of raw rubber blocks must be above 30°C during plasticizing.
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