Mixing Technology of Opener and Internal Mixer
Time: 2019-01-23 08:49:31Copyfrom: Wuxi Tengyu Environmental Protection Technology Co
I. Blending Technology of Opener
The mixing process includes three aspects:
Three processes: the mixing of the refiner can be divided into three stages: roll wrapping, powder feeding and refining.
1. When the wrapped roll unsaturated rubber is processed on the refiner, four different wrapped roll States will appear when the temperature of the roll is changed. Low temperature, hard rubber, high elasticity, rubber mainly stay in the accumulation of rubber sliding, delaying the production process. When the temperature is suitable, the rubber can be wrapped on the roller normally. It has both plastic flow and high elastic deformation, which is conducive to mixing operation. With the increase of temperature, the fluidity increases, the intermolecular force decreases, and the strength decreases. The film can not be wrapped tightly on the roller, and roll-off or breakage occurs. Rubber is wrapped in rollers in viscoelastic fluid at higher temperatures, which produces plastic flow.
2. In order to mix the compounding agent into the glue as soon as possible, proper amount of glue should be accumulated on the roll gap after the powder rubber is rolled. When powder is eaten, when the compound enters the upper layer of the stacked rubber, it is congested and folded due to resistance. Crepe grooves are formed in the front of the stacked rubber. Powder can enter these grooves and be brought into the inner part of the stacked rubber. If there is no accumulated rubber, the mixing agent rubs the powder into the rubber only by the shear force between the back roll and the rubber, which can not make the powder penetrate into the rubber and affect the mixing effect. And the powder that is not rubbed into the rubber will be squeezed into thin sheets by the back roll and the rubber and fall into the feeding tray. If the liquid mixture is used, it will stick to the back roll or flow to the feeding tray, which makes it difficult to mix later. In the process of eating flour, the amount of glue accumulated must be moderate. If there is no rubber accumulation or the amount of rubber accumulation is too small, on the one hand, the mixing agent rubs into the compound only by the shear force between the back roller and the rubber, which can not penetrate into the inside of the compound and affect the dispersion effect; on the other hand, the powder mixing agent that is not rubbed into the rubber will be squeezed into sheets by the back roller and dropped into the feeding plate; if it is a liquid mixing agent, it will stick to the back roller or fall onto the feeding plate, causing mixing difficulties. Hard. If the accumulation of glue is excessive, a part of the glue will rotate and roll at the top of the roll gap, and can not enter the roll gap, so that the mixing agent is not easy to mix.
The third stage of refining and mixing is refining. Because of the high viscosity of rubber, the rubber only flows in the circumferential direction along the rotating direction of the drum, but not in the axial direction, and the rubber only flows in the circumferential direction. Therefore, the rubber layer close to the front drum surface at about 1/3 of the film thickness can not produce flow and become "dead layer" or "dead layer", as shown in the figure. In addition, the accumulated glue on the top of the roll gap will form a part of wedge-shaped "reflux zone". The above reasons make the mixtures in the compound disperse unevenly.
Because of the high viscosity of rubber, the fluidity of rubber in the near layer of roller surface is poor, and the shear force makes the flow of rubber only laminar. About 1/3 of the inner layer of film which is in contact with the surface of the roller can not get in, forming a "dead layer".
In order to compensate for the adverse effect of stacking rubber on mixing, cutting and refining must be supplemented in technology, so that the rubber in "dead layer" is continuously brought to the top of the stacking rubber and into the "living layer", so that the left and right sides of the rubber are blended with each other, in order to destroy the dead layer and reflux zone, make the mixing uniform and ensure uniform texture.
2. Mixer technology:
1. Use of mixer:
Mainly used for rubber plastics and mixing, but also for plastics, asphalt, felt, synthetic resin mixture. It is one of the main rubber mixing equipment in rubber factories. Since the 1970s, foreign countries have developed rapidly in rubber mixing technology and equipment, such as using screw extruder instead of internal mixer and open mixer for plasticizing and mixing, but still can not replace internal mixer. The mixer is still the main equipment in the new modern plant, and the two-stage mixing method is still used in the mixing process.
(1) According to the shape of the cross section of the rotor, it can be divided into elliptical rotor mixer, cylindrical rotor mixer and triangular rotor mixer.
(2) According to the working principle, it can be divided into tangential rotor mixer and meshing rotor mixer.
(3) According to the size and variation of rotor speed, it can be divided into low speed, medium speed, high speed and single speed, double speed and variable speed mixers.
(4) According to the relative speed of rotor: asynchronous and synchronous rotor mixer
(5) According to the structure of mixing chamber, it can be divided into normal mixer and overturning mixer.
(6) According to the relative clearance between the rotors, it can be divided into fixed clearance and adjustable clearance mixer.
2. Specification and technical characteristics of mixer:
In the past, the working capacity of the internal mixer and the rotational speed of the active rotor were used to express the working capacity of the internal mixer; now, the total capacity of the internal mixer and the rotational speed of the active rotor are used to express the working capacity of the internal mixer.
Specification of domestic mixers:
X denotes rubber, M denotes internal mixer, 250 denotes total capacity of internal mixer and 20 denotes rotor speed.
X denotes rubber, S denotes plastics, M denotes mixer, 75 denotes total capacity of mixer, two-speed (35 and 70 rpm)
3. The overall structure of the mixer and the function of each part:
(1) Mixing part: The mixing part mainly consists of rotor, mixing chamber and sealing device.
(2) Feeding part: It mainly consists of right feeding chamber, bucket feeding outlet and turning gate (feeding gate) 11. This part is mainly used for feeding and instantaneous storage.
(3) Pressure part: It mainly consists of the top bolt 9 and the cylinder 14 which drives the top bolt to move up and down reciprocating. Its main function is to give a certain pressure to the rubber, accelerate the rubber refining process and improve the rubber refining effect.
(4) Discharging device: It is mainly composed of a lower top bolt 3 and a lower top bolt locking mechanism installed under the mixing chamber.