The difference between single screw extruder and twin screw extruder: one is a screw, the other is two screws. Both are driven by a motor. The power varies with different screw sizes. The power of 50 conical twin screw extruder is about 20kW, and 65 is about 37kW. The output is related to the material and the screw size. The output of 50 conical twin screw extruder is about 100-150kg/h, and 65 conical twin screw extruder is about 200-280kg/h. The output of a single screw is only half than twin screw extruder.
Extruders can be divided into single-screw, twin-screw and multi-screw extruders according to the number of screws. Today, the single-screw extruder is the most widely used and is suitable for extrusion processing of general materials. The twin-screw extruder has the characteristics of less heat generated by friction, relatively uniform shearing of the material, large conveying capacity of the screw, relatively stable extrusion volume, long residence of the material in the barrel, and uniform mixing.
The single-screw extruder occupies an important position both as a plasticizing and granulating machine or a molding and processing machine. In recent years, the single-screw extruder has made great progress. The large-scale single-screw extruder for granulation produced in Germany has a screw diameter of 700mm and an output of 36t/h.
The main sign of the development of single-screw extruder lies in the development of its key part, the screw. In recent years, people have carried out a lot of theoretical and experimental research on screws. There are nearly 100 types of screws. The common ones are separation type, shear type, barrier type, split type and wave type.
From the perspective of single-screw development, although the single-screw extruder has been relatively complete, with the continuous development of polymer materials and plastic products, new and special single-screw extruders with more characteristics will emerge. In general, single-screw extruders are developing in the direction of high speed, high efficiency and specialization.
The twin-screw extruder has good feeding characteristics, is suitable for powder processing, and has better mixing, exhaust, reaction and self-cleaning functions than single-screw extruders, and is characterized by processing plastics and blends with poor thermal stability. It shows its superiority even more.
With the development of modern industry, the underwater pelletizing machine has become an important production equipment used in all aspects of production.
What is the working principle of the underwater pelletizing machine?
What is the operating procedure of the underwater pelletizing machine?
What are the reasons why people choose underwater pelletizing machine?
The material using the underwater pelletizing machine will pass through the feeding port, and under the action of the rotating screw, it will be rolled into a dough and roll forward along the screw groove. Due to the shear, compression and agitation of the screw, the material will be further mixed and plasticized. , The temperature and pressure gradually increase, showing a state of viscous flow, and passing through the machine head with a certain pressure and temperature, and finally a product of the desired shape is obtained.
(1) Check the rotation direction of the impeller of the underwater pelletizing machine. From the feed inlet, the impeller should turn counterclockwise, otherwise the motor connection should be adjusted.
(2) The starting sequence of the underwater pelletizing machine and the material conveying equipment is as follows:
Discharge belt conveyor→PL vertical impact crusher→feeding belt conveyor
The crusher must be started without load, and the material can only be fed after the crusher is running normally.
(3) The feed size is strictly in accordance with the feed size specified by the various models. It is forbidden to enter the underwater pelletizing machine with the size of the material larger than the specified size, otherwise it will cause the impeller imbalance and excessive wear of the impeller, and even block the impeller flow path and The central feed pipe prevents the crusher from working normally. When a large piece of material is found, it should be removed in time.
(4) When the discharge belt conveyor stops running, the feeding should be stopped immediately, so the discharge belt conveyor should be interlocked with the feeding system to open and stop. Otherwise, the impeller will be crushed and the motor will be burnt.
(5) The feeding of the underwater pelletizing machine should be uniform and continuous.
(6) During the operation of the underwater pelletizing machine, there must be no violent vibration or abnormal noise, otherwise, it should be stopped immediately for inspection, and the machine can only be driven in order after the fault is removed.
(7) The observation door should be sealed tightly during the working process of the underwater pelletizing machine.
The difference between the underwater pelletizing machine and other similar products is that it has a steady stream of water flowing through the mold surface, and it is in direct contact with the mold surface. The size of the pelletizing chamber is just enough to allow the pelletizing knife to rotate freely across the die surface without restricting the temperature of the water flow. The molten polymer has been extruded from the die, and the rotating knife cuts the pellets. And then the pellets are taken out of the pelletizing chamber by the temperature-regulated water and enter the centrifugal dryer. In the dryer of the underwater pelletizing machine, the water will be drained back to the storage tank, cooled and recycled; the pellets pass through the centrifugal dryer to remove the water.
This is how we see the irreplaceable role of underwater pelletizing machine in our daily lives and industrial production. Nanjing JlEYA, the pioneer of underwater pelletizing machine producing company in China, knows that every application is special. You can go and get more information about them
The special refining effect and excellent performance of the single screw extruder have been proved in practice. Practice has proved that the reciprocating single-screw mixing extruder is a new type of plastic extrusion equipment. The emergence of single screw extruder provides a high-performance plastic processing equipment for the majority of users. Made a huge contribution to the development of the plastics industry.
What is the function of the single screw extruder operation screen?
What is the significance of the emergence of a single screw extruder?
What are the application fields of single screw extruder?
The operating panel is installed above the single screw extruder and can be rotated within 60 degrees for easy operation. There is a power indicator and emergency stop button on the right side of the touch screen. In an emergency, press the emergency stop button to stop immediately, which is used to protect the safety of the operator and the single screw extruder. The data recording, parameter setting, operation control and other operations of the entire instrument are all completed in this operation screen.
In the process of polymer processing, in order to give the polymer certain processing characteristics or to give the product specific use performance, it is often necessary to blend different polymers or blend the polymer with various additives and pigments. The single-screw extruder has the characteristics of uniform shearing, high dispersion, high filling, and stretching of the melt. And it combines the advantages of single and twin screw extruders. The unique working principle, coupled with a complete set of threaded components and supporting equipment, makes it more widely used. On a single screw extruder, it can achieve mixing, Mixing, plasticizing, dispersing, shearing, stretching, degassing, and granulation make the interface area of the melt flow in the machine far larger than the general shear flow.
The reciprocating single-screw mixing extruder is a new type of plastic mixing processing equipment, which is widely used in the filling, blending, modification, crosslinking, grafting, color masterbatch, functional masterbatch, and resistance of various plastics. Production of fuel masterbatch, conductive material, degradable masterbatch, reinforcement, toughening and other special plastic materials.
Blending different types of polymers to obtain brand new polymer alloys with specific uses.
Various mineral fillers are added to the polymer melt to make high-filling materials with excellent performance and low price.
Production of various glass fiber reinforced and flame retardant products, with the addition of glass fiber up to 50%.
It is suitable for the production of various cable sheathing materials, insulating materials, cross-linking materials, semiconductors, shielding materials, and conductive materials.
Production of thermoplastic elastomers and hot melt adhesives.
The single screw extruder is increasingly used in industrial production.Nanjing JlEYA has committed itself to offering the best-suited single screw extruders at a reasonable price, and all that is necessary to meet the needs of the customer.
Weigh the complete feeding system (silo, feeder and bulk material) through static scales and control the discharge flow of bulk materials through variable speed motors or electric vibrators. Material is discharged from the system (via screw, vibrating tube or trough), the "loss" measured per unit of time (dv/dt) is compared to the required feed rate (preset value), the actual (measured) The difference between the flow rate and the desired (preset) flow rate generates a corrective signal through the dosing controller, which automatically adjusts the dosing rate to maintain the accurate dosing amount without process lag. When the weight measured in the silo reaches the low level of the silo (refilling), the controller will control the feeding system according to the volumetric feeding, and then the silo will be reloaded quickly (manually or automatically), and the weight loss controller will restart . In a batch loss-in-weight system, the design is similar to a continuous loss-in-weight system, however, the accuracy of the final weight of the feed (batch) cycle is higher than the actual feed amount control. The controller accomplishes fast dosing by providing a high dosing signal to the variable speed drive, then transitions to a low dosing control signal for precise control at the end of the batch. Technical parameter
Metering accuracy ≤0.5%
Ingredient accuracy ≤0.5%
Batching measurement control range 0.01-300t/h
Scope of application
Continuous stabilized soil, cement batching in concrete mixing plants, sintering quantitative control feeding, coal powder quantitative control feeding and batching of various thick slurries, etc.
Product introduction of loss-in-weight scale: the loss-in-weight feeder consists of a hopper, a feeder (single and double-shaft screw feeder), a weighing system and a regulator. During operation, the hopper, material and feeder are weighed continuously. As the material is delivered, the actual rate of weight loss is measured and compared to the desired rate of weight loss (set point). Automatically corrects for deviations from setpoint by adjusting feeder rates. Thus, the material can be fed continuously and evenly and accurately.
Applicable scope: granule, powder, calcium carbonate, talcum powder, resin film powder, flour, starch, etc. Powder gravimetric feeder: solves the problem of feeding metering and feeding with poor fluidity while pellet gravimetric feeder solve any bridging problems that may occur.
The engineering plastic twin screw extruder consists of a transmission device, a feed device, a barrel, and a screw. The function of each component is similar to that of a single-screw extruder. The difference to the single screw extruder is that in the engineering plastic twin screw extruder two parallel snails are arranged in the "cross-section" of the material.
What is the working principle of the engineering plastic twin screw extruder?
How do you treat a engineering plastic twin screw extruder?
Why is the cooling device particularly important when using engineering plastic twin screw extruders?
From the point of view of the principle of movement, the engineering plastic twin screw extruder distinguishes between the straight and uneven, and non-foaming types.
1. Double screw extruder of technical plastic
This type of engineering plastic twin screw extruder has a low speed and a high speed. The former is mainly used for profile extraction, while the latter is used for special polymer processing operations.
(1) Tightly machined extruder. The slow-running extruder has a closely combining screw geometry, in which the spiral antenna shape of one snail closely matches the spiral antenna shape of the other snail, i.e. the conjugated snail shape.
(2) Self-cleaning extruder. The simultaneous high-speed extruder has a closely tuned spiral shape. This type of snail can be executed with a relatively small snail split so that the snail has a closed self-cleaning effect. This type of engineering plastic twin screw extruder is called a compact self-cleaning engineering plastic twin screw extruder.
The gap between the two screw edges of the closely combining, opposing engineering plastic twin screw extruder is very small (much smaller than the gap in the evenly rotating engineering plastic twin screw extruder) so those positive conveying properties can be achieved.
2. Non-reciprocating double screw extruder of technical plastic
The axis distance between the two snails of the non-foaming engineering plastic twin screw extruder is greater than the sum of the radii of the two snails.
1. After using the engineering plastic twin screw extruder for 500 hours, iron chips or other impurities from the gears are in the gearbox. Therefore, the gears should be cleaned and the gear lubricant replaced.
2. The engineering plastic twin screw extruder should carry out a comprehensive inspection of the extruder after an operating period to check the density of all snails.
3. If the double screw extruder is suddenly switched off during production, the main drive, and the heating stops, if the power supply is restored, each section of the cylinder shall be reheated to the specified temperature and kept for a specified period, before you can start the extruder.
4. If the display and the display of the engineering plastic twin screw extruder are full, check if the contact of the thermocouple, etc. is good.
After the molded plastic extrusion layer has left the engineering plastic twin screw extruder, it should be cooled and formed immediately, otherwise, it will deform under the influence of gravity. The cooling method normally uses water cooling and is divided into quick cooling and slow cooling according to the different water temperatures. Fast cooling is the direct cooling by cold water. Rapid cooling is advantageous for the design of the extruded plastic layer, but in the case of crystalline polymers, due to sudden heat cooling, it is easy to leave internal stresses in the extruded layer structure, which leads to cracks during use. Generally PVC The plastic layer is deterred. Slow cooling should reduce the inner tension of the product. Water with different temperatures is given in the cooling water tank to gradually reduce the temperature and shape of the product. The extrusion of PE and PP takes place under slow cooling, i.e. through hot water, hot water, and cold water, which is called three-stage cooling.
Nanjing JlEYA is the leading manufacturer extruder manufacturer specializing in twin screw extrude. If you want to get more information, just go and connect them.
Nanjing Team sincerely invite you to attend The 15th China Chongqing Rubber, Plastics Industry Exhibition.
Our booth no.: S2544
Time: May 27-30, 2021
Address: Chongqing International Expo Center
Wish to meet you at there ;)
A plastic extruder performs all of the following processes through a barrel with a screw and auger channel. The plastic pellets enter the barrel through a hopper at one finish of the barrel and are then transferred through the screw to the opposite finish of the barrel. What are the working principle and molding principles of a plastic extruder? The following is a detailed description.
Here is the content list:
Pressure and shearing, etc., convert the solid plastic into a uniform and consistent melt and send the melt to the next process. The production of the melt involves processes such as mixing additives such as masterbatches, blending resins, and re-crushing. The finished melt must be homogeneous in consistency and temperature. The pressurization must be high enough to extrude the viscous polymer.
To have sufficient pressure, the depth of the threads on the screw decreases as the distance to the hopper increases. The external heating and the internal heat generated in the plastic and the screw due to friction softens and melts the plastic. The design requirements for plastic extruders often vary from polymer to polymer and from application to application. Many options involve discharge ports, multiple loading ports, special mixing devices along the screw, cooling and heating of the melt with or without an external heat source (adiabatic plastic extruders), the relative size of the gap variation between the screw and the barrel, and the number of screws. For example, twin-screw plastic extruders allow for more thorough mixing of the melt than single-screw plastic extruders. Tandem extrusion uses the melt-extruded from the first plastic extruder as feedstock for the second plastic extruder, which is typically used to produce extruded polyethylene foam.
D L the characteristic dimensions of plastic extruders are the diameter of the screw (D) and the ratio of the length of the screw (L) to the diameter D L/D (D) (L/D. Plastic extruders usually consist of at least three segments. The first section, near the L/D) filling hopper, is the filling section. Its function is to allow the material to enter the plastic extruder at a relatively smooth rate. In general, this section will be kept at a relatively low temperature to avoid clogging the charging channels. The second section is the compression section, where the melt is formed and the pressure is increased. The transition from the charging section to the compression section can be abrupt or gradual (gentle). The last half, the metering section, is adjacent to the plastic extruder outlet and its main operate is that the uniformity of the fabric flowing out of the plastic extruder. In this section, the material should have sufficient residence time to ensure uniformity of composition and temperature.
At the end of the barrel, the plastic melt leaves the plastic extruder through a head that is designed in an ideal shape for the extruded melt stream to pass through.
Another important part is the drive mechanism of the plastic extruder. It controls the rotational speed of the screw, which determines the output of the plastic extruder. The power required is determined by the viscosity (flow resistance) of the polymer. The viscosity of the polymer depends on the temperature and flow rate and decreases with increasing temperature and shear. Plastic extruders are equipped with screens that keep impurities out of the screen. To avoid downtime, the screens should be able to be changed automatically. This is especially important when processing resin with impurities, such as recycled material. The extruder's screw is divided into feeding section, plasticizing, melting section, temperature according to the process parameters of the plastic particles, the model according to the diameter of the screw 20, 36, 52, 65, 75, 95, 120, 135. Plastic particles heated by the movement of the screw to change the original state, there are many types, depending on the specific application. The capacity of the frequency conversion is proportional to the diameter of the screw and then adjusted according to the different raw materials.
The extrusion method of plastic extruders generally refers to the melting of plastic at a high temperature of about 200°C. The melted plastic is then passed through a die to form the desired shape. Extrusion molding requires a deep understanding of the characteristics of plastics and extensive experience in mold design and is a technically demanding molding method.
Extrusion molding is a method of a continuous flow of material through a die by heating and pressurizing in an extruder, also known as "extrusion molding". Compared with other molding methods, it has the advantages of high efficiency and low unit cost.
Extrusion is mainly used for molding thermoplastics, but it can also be used for some thermosets. Extruded products are continuous profiles, such as tubes, rods, wires, sheets, films, wire, and cable cladding, etc. In addition, it can also be used for mixing, plasticizing and granulating, coloring, blending, etc. plastics.
The extruded products can be called "profiles", which are also called "profiles" because of their irregular cross-sectional shape.