twin screw pvc extruder- China Manufacturers Factory Suppliers

  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.

The high efficiency of the single-screw extruderis mainly reflected in high output, low energy consumption, and low manufacturing cost. In terms of function, the plastic extruder has been used not only for extrusion molding and mixing processing of polymer materials but its use has been broadened to food, feed, electrode, building materials, packaging, ceramics, and other fields. So how to operate the single screw extruder? The following is a detailed introduction.

 

Here is the content list:

• Preparation work before starting the machine

• Start-up operation

• Stop operation

 

Preparation work before starting the machine

1. For single-screw extruder extrusion production of materials, should meet the required drying requirements, if necessary, further drying.

2. According to the variety of products, size, select the head specifications, the machine will be installed in the order of the column, installed head flange, die body, mouth die, porous plate, and filter network.

3. Connect the compressed air pipe, install the core mold electric heating rod head heating ring, check the water system.

4. Adjust the gap evenly in all parts of the mouth die and check whether the centerline of the main machine and the auxiliary machine are aligned.

5. Start the single-screw extruder of each running equipment, check whether the operation is normal, and find faults in time to eliminate.

6. Turn on the electric heater, the head, body, and auxiliary machine evenly heated up, to be the temperature of each part than the normal production temperature of about 10 degrees, constant temperature of 30 ~ 60 minutes so that the machine temperature inside and outside the same.

 

Start-up operation

Start-up is an important part of the production, poor control will damage the screw and head, the temperature is too high will cause plastic decomposition, the temperature is too low will damage the screw, barrel, and head. The start-up steps are as follows.

1. Start the machine at low speed, idle, check the screw for any abnormalities and motor, amperage meter current no overload phenomenon, the pressure gauge is normal. Machine idling should not be too long to prevent the screw and barrel-scraping grinding.

2. Gradually add a small amount of material, wait for the material extrusion out of the die, before the normal addition of material. Before the plastic is extruded, no one should be in front of the mouth die to prevent casualties.

3. After the plastic is extruded, it is necessary to lead the extruded material slowly on the cooling and shaping, traction equipment, and start this equipment beforehand. Then, according to the control instrument indication value and the requirements of the extruded products, each link will be properly adjusted until the extrusion operation reaches the normal state.

4. Cutting and sampling, checking whether the appearance meets the requirements, whether the size meets the standard, quickly testing the performance, and then adjusting the extrusion process according to the requirements of quality, so that the products meet the standard requirements.

 

Stop operation

1. Stop feeding, extrude the plastic in the single screw extruder and turn off the power of the barrel and head for the next operation.

2. Shut off the power of the main machine and the auxiliary machines at the same time.

3. Open the head connection flange, clean the porous plate and various parts of the head, when cleaning, should use copper rods, copper pieces, after cleaning, apply a little oil. Screw, barrel clean up, if necessary, the screw from the end of the machine out of the top, clean up after recovery, in general, available for the transition of material cleanup.

4. Extrusion of polyolefin plastics, usually in the extruder full load shutdown (with material shutdown), when the air should be prevented from entering the barrel, so as not to oxidize the material and affect the quality of the product when continuing production. For polyvinyl chloride plastics, can also stop with material, then close the material door, reduce the temperature at the head connection body (flange) 10 ~ 20 degrees, to stop the machine after the material squeeze net.

5. Close the total power and cooling water main valve.

 

If you still have questions, you can consult our company. Our company's website is https://www.njjyextrusion.com/

 

 

underwater pelletizing machine is similar to airflow granulator and water jet granulator. The equipment part mainly covers: plastic granulator, single and twin screw plastic extruder, plastic film blowing machine, bag making machine, printing machine, coating machine, Adhesive tape machine, tape slitting machine, slitting machine, strapping machine.

• What is the problem of uneven pelletizing by the underwater pelletizing machine?

• What is the workflow of the underwater pelletizing machine?

• What is the technological advantages of the underwater pelletizing machine?

What is the problem of uneven pelletizing by the underwater pelletizing machine?

1. underwater pelletizing machine, the machine head is not evenly heated, and the machine head temperature is stable before starting up;

2. The cooling water of the underwater pelletizing machine is boiled prematurely, and the water should be boiled when the machine head starts to discharge;

3. It is also possible that there is a problem with the hot runner design of the machine head, which is caused by uneven pressure.

What is the workflow of the underwater pelletizing machine?

Before being made into final products, most polymers must be blended and then pelletized to become marketable raw materials. The power required by the underwater pelletizing machine is directly proportional to the extrusion volume and exponentially related to the size of the filter screen. There are many different types of pelletizer designs, but all pelletizers have some common places, and they can be divided into two categories: cold pelletizing system and die face hot pelletizing system. The main difference between the two categories is the time arrangement of the pelletizing process. The cold pelletizing system cuts pellets from the solidified polymer at the end of the process; while in the die-face hot pelletizing system, pellets are cut when the molten polymer emerges from the die, and pellets are processed downstream cool down.

What are the technological advantages of the underwater pelletizing machine?

The underwater pelletizing machine treated by standard process has the following significant advantages:

1. The appearance standard of the products produced by the underwater pelletizing machine is exquisite and bright;

   
   

2. The hardness of the wear layer in contact with the material by the underwater pelletizing machine can reach HV 600-800, and the local hardness can reach HV900-1100. The hardness is increased to 2-4 times the original hardness. Compared with the non-standard machine without heat treatment, it is resistant to The wear performance is increased by 3-5 times;

3. The products of the underwater pelletizing machine are not deformed after long-term use, effectively avoiding the screw breaking due to the excessive wear of the barrel, and the stable service life is 2-3 times that of the traditional machine, which greatly reduces the investor's investment in replacement parts;

4. The wear-resistant layer of the barrel screw produced by the underwater pelletizing machine has high hardness, while the base material still retains good toughness and processing performance;

5. The service life of the screw of the underwater pelletizing machine has increased from the hundred-ton level of the ordinary plastic pelletizing machine to the thousand-ton level.

Nanjing JlEYA has focused on the production and development of underwater pelletizing machines for several years, and they have always put the needs of customers as their top priority. Here, you can choose the underwater pelletizing machine that suits your need.

Plastic extruders can be divided into single-screw extruders, twin-screw extruders, and multi-screw extruders according to their number of screws. The following are the details of the types of plastic extruders.

 

Here is the content list:

• Classification of plastic extruders

• Single-screw extruder

• Twin-screw extruder

 

Classification of plastic extruders

1, According to the number of screws, divided into single-screw extruders, twin-screw extruders, and multi-screw extruders.

2, According to the presence or absence of a screw in the extruder, divided into screw extruders and plunger extruders.

3, According to the running speed of the screw to divide:

Ordinary extruder: speed below 100r/min.

High-speed extruder: speed of 100 to 300r/min.

Super high-speed extruder: the speed is 300~l500r/min.

4, According to the extruder assembly structure classification: there are integral extruders and separate extruders.

5, According to the spatial position of the screw in the extruder, can be divided into the horizontal extruder and vertical extruder.

6, According to whether the extruder is in the process of exhaust and can be divided into exhaust type extruder and non-exhaust type extruder

 

Single-screw extruder

The single-screw extruder occupies an important position both as a plasticizing and pelletizing machine and as a molding machine, and in recent years, the single-screw extruder has developed greatly. Single-screw extruders were the first extruders to gain widespread application in the plastic processing and molding field due to their simple structure and high processing efficiency. Similarly, to meet different processing needs, various equipment manufacturers have explored various screw and barrel structures. The single-screw extruder has evolved from the basic pure screw structure to various structures such as damping screw block, exhaust extrusion, slotted screw barrel, pinned barrel, building block structure, etc., thus enabling the single-screw extruder to have a wider range of molding.

 

Due to the small footprint of single-screw extruders, they are almost the only equipment used in the compounding and blown film fields. Single-screw extruder technology has become an important part of the extrusion process market that cannot be ignored.

 

 

Twin-screw extruder

The twin-screw extruder has less heat generated by friction, more uniform shearing of the material, larger conveying capacity of the screw, more stable extrusion volume, long stay of the material in the barrel, and uniform mixing.

 

The twin-screw extruder has good feeding characteristics, is suitable for powder processing, and has better mixing, exhaust, reaction, and self-cleaning functions than the single-screw extruder, characterized by the processing of plastics with poor thermal stability and co-mingled materials show its superiority. Based on the twin-screw extruder, the multi-screw extruder was developed for easier processing of co-blends with poor thermal stability.

 

If you want to buy an extruder, you can consider our cost-effective products. Nanjing JlEYA is the leading manufacturer extruder manufacturer specializing in a twin-screw extruder, mini twin screw extruder, plastic extruder, and parallel twin-screw extruder in China, which is widely used in compounding, modification, polymerization, after 17 years of development, now we have 20,000 square meters workshop with annual sales over 300+ sets, export over 60 countries.

When the single screw extruder is in the extrusion molding process, its extruder screw is divided into 3 sections: feeding section (feeding section), melting section (compression section), metering section (homogenization section), these three sections Correspondingly, three functional areas are composed of materials: solid conveying area, material plasticizing area, and melt conveying area. Each area has different temperature requirements, and specific problems should be analyzed in detail. The temperature of the single screw extruder will be briefly introduced below.

• What is the general temperature of the solid conveying zone in a single screw extruder?

• What is the general temperature in the plasticizing zone of the material in a single screw extruder?

• What is the general temperature of the melt conveying zone in a single screw extruder?

What is the general temperature of the solid conveying zone in a single screw extruder?

The temperature of the barrel in the solid conveying zone of the single screw extruder is generally controlled at 100~1400C. If the feeding temperature is too low, the solid conveying zone will be extended, reducing the length of the plasticizing zone and the melt conveying zone, which will cause poor plasticization of the single screw extruder product and affect product quality.

What is the general temperature in the plasticizing zone of the material in a single screw extruder?

The temperature of the material plasticizing zone in the single screw extruder is controlled at 170~1900C. Controlling the vacuum degree of this section is an important process index. If the vacuum degree is low, it will affect the exhaust effect, resulting in bubbles in the pipe, and seriously reducing the mechanical properties of the pipe. In order to make the gas inside the material easily escape, the plasticization degree of the material in this section should be controlled not to be too high, and the exhaust pipe of the single screw extruder should be cleaned frequently to avoid blockage. The vacuum degree of the barrel is generally 0.08~0.09MPa.

What is the general temperature of the melt conveying zone in a single screw extruder?

The temperature of the melt conveying zone in the single screw extruder should be slightly lower, generally 160~1800C. Increasing the screw speed in this section, reducing the head resistance and increasing the pressure in the plasticizing zone are all conducive to the improvement of the conveying rate. For heat-sensitive plastics such as PVC, the residence time should not be too long in this section. The screw speed is generally 20 ~30r/min. The head of the single screw extruder is an important part of extruded product molding. Its function is to generate a higher melt pressure and make the melt shape into a desired shape. The process parameters of each part of the single screw extruder are: die connector temperature 1650C, die temperature 1700C, 1700C, 1650C, 1800C, 1900C.

This is some information related to the use of single screw extruders. The use of single screw extruders is also closely related to the quality of its products. If you need more information, please contact Nanjing JlEYA.

The basic mechanism of the twin screw extrusion process is simply that a screw rotates in the barrel and pushes the plastic forward. The screw structure is a bevel or ramp wrapped around a central layer, the purpose of which is to increase the pressure to overcome the higher resistance. What do I need to pay attention to when using a twin screw extruder? The following is a detailed description.

 

Here is the content list:

l Structural principles

l Temperature principles

l Speed reduction principle

 

Structural principles

For the extruder, there are three kinds of resistance to overcome when working: one is friction, which contains the friction of the solid particles (feed) on the barrel wall and the mutual friction between them during the first few turns of the screw (feed area); the second is the adhesion of the melt on the barrel wall, and the third is the resistance of the internal logistics of the melt when it is pushed forward.

According to Newton's theorem, if an object is at rest in a certain direction, then the object is in a state of equilibrium balance of forces in this direction. For the circumferential movement of the screw, it is no axial motion, that is, the axial force on the screw is in equilibrium. So if the screw exerts a large forward thrust on the plastic melt, it also exerts a backward thrust on another object of the same magnitude but in the same direction. The thrust is exerted on the thrust bearing behind the feed opening. Most single screws have right hand threads, and if viewed from the back, they rotate backward, and they spin backward out of the barrel by rotational motion. In some twin screw extruders, however, the two screws rotate backward and cross each other in both barrels, so one must be right handed and one left handed, and in the case of an occluding twin screw, both screws rotate in the same direction and must therefore have the same orientation. However, in either case, there are thrust bearings that withstand backward forces and still comply with Newton's theorem.

 

Temperature Principle

Plastics extruded by twin screw extruders are thermoplastics, which melt when heated and solidify again when cooled. Thus, heat is needed during the extrusion process to ensure that the plastic can reach the melting temperature. So where does the heat to melt the plastic come from? First of all, the pound feed preheat and barrel/die heaters may play a role and are very important at startup. In addition, the motor feed energy, the frictional heat generated in the barrel as the motor overcomes the resistance of the viscous melt and turns the screw, is the most important heat source for all plastics, except for small systems, low speed screws, high melt temperature plastics, and extrusion coating applications. In operation, it is important to recognize that the barrel heater is not the primary heat source and that it may play a smaller role in extrusion than we might expect. The post barrel temperature is more important because it affects the rate of solids transport in the dentition or feed. In general, except for a specific purpose (such as varnishing, fluid distribution, or pressure control), the die head and die temperature should be at or near the temperature required for the melt.

 

Speed reduction principle

In most twin screw extruders, the screw speed is varied by adjusting the motor speed. The drive motor usually turns at a full speed of about 1750 rpm, which is too fast for an extruder screw. If it turns at such a fast speed, too much frictional heat is generated and a uniform, the well mixed melt cannot be prepared because the retention time of the plastic is too short. A typical speed reduction ratio should be between 10:1 and 20:1, with either a gear or pulley set for the first stage, but with a gear and a screw positioned in the center of the last large gear for the second stage. For some slow running machines (eg. twin screws for UPVC), there may be three reduction stages and the maximum speed may be as low as 30 rpm or less (ratio up to 60:1). On the other hand, some very long twin screws for mixing can run at 600 rpm or faster, thus requiring a very low reduction rate and more deep cooling. If the reduction rate is incorrectly matched to the job, too much energy will be wasted. It may be necessary to add a pulley set between the motor and the first deceleration stage where the maximum speed is changed, which either increases the screw speed even beyond the previous limit or reduces the maximum speed. This increases the available energy, reduces the current value, and avoids motor failure, in both cases, the output may increase due to the material and its cooling needs.

 

If you still have questions, you can consult our company. Nanjing JlEYA is the leading professional manufacturer of twin screw extruders in China.

2022 CIM: Compounding Intelligent Manufacturing Conference is coming.
Nanjing Jieya team warmly welcome your visiting.
Booth no.: E10
Date: 2022.9.14-16
Address: Suzhou, China

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