XJD-150×16D Pin Barrel Cold Feed Extruder For Extruding Tire Tread And Rubber

Product Specification

XJD-150×16D Pin Barrel Cold Feed Extruder For Extruding Tire Tread And Rubber Sheet

Extruder Introduction:

1; Pin barrel: The outer barrel is made of high-quality carbon structural steel, with a 38CrMoAlA high-quality nitrided steel bushing embedded in it. The bushing is tempered and surface nitrided. The surface hardness of the inner hole is HRC65-70, and the hard layer depth is 0.5-0.7mm. The outer barrel is drilled with an axial channel on the circumference for heating and cooling the barrel.
2; Screw: It is made of 38CrMoAlA high-quality nitrided steel, tempered and surface nitrided. The surface hardness of the spiral part is HRC60-65, and the hard layer depth is 0.5-0.7mm. The spiral structure adopts equal-depth segmented variable pitch in the extrusion and plasticizing sections, and adopts a composite form of spiral ridges with four heads and grooves and double heads in the feeding section. This spiral form has the characteristics of high strength, strong feeding capacity, sufficient shearing and plasticizing mixing, stable extrusion pressure, low temperature and high output, and strong adaptability to various rubber materials.
3; Feeding device: It consists of a feeding roller, a roller cover, a bearing seat, a gear pair, a bearing, a scraper, etc. The special design structure can effectively prevent the rubber from entering the feed roller support bearing, ensuring the normal use of the feeding device. After surface quenching, the surface hardness of the feed roller surface and the anti-rubber groove part is HRC50-55, the hard layer depth is 0.6-0.8mm, and the gear pair has an independent lubrication system. The feeding device is installed on one side of the fuselage.
4; Feeding section barrel: It consists of the fuselage, front bushing, and rear bushing. The materials of the front and rear bushings are 38CrMoAlA high-quality nitrided steel, which is tempered and surface nitrided. The surface hardness of the inner hole is HRC65-70 and the hard layer depth is 0.5-0.7mm. The fuselage material is ZG270-500, and it is cast with a sandwich cavity for heating and cooling the fuselage.
5; Pins: Made of 38CrMoALA, the surface is nitrided after tempering, which is wear-resistant and tough. There are 10 rows of pins, 8 in each row, and a total of 80 pieces.
6. Reducer: A three-stage reducer with hard-hard tooth surface specially used for extruder is used. The gear pair is completely immersed in lubricating oil to ensure full lubrication of the gear pair. The gear shaft and gear are made of two different high-quality high-strength low-carbon alloy steels. The tooth surface is carburized, quenched and ground. The gear meshing accuracy is 6. The reducer has a forced lubrication system.
7. Main motor: The traction motor adopts the Y series AC variable frequency motor of Wannan Motor Co., Ltd., which cooperates with the variable frequency speed regulator to form motor over-temperature protection to meet the production needs at different speeds.
8. The electrical system of the unit consists of the AC speed control system and other parts, including the AC speed control cabinet and the corresponding actuators.

 

Technical Parameters:
 

Advantages of Pin-Type Cold Feed Extruder:

1. Working Principle
 Cold Feed Principle : Unlike the hot feed method, the cold feed extruder directly feeds the unpreheated rubber material (such as rubber strips or rubber pellets) into the barrel. This is because its screw has a strong conveying and plasticizing capacity and can process rubber at a lower temperature. The rubber is pushed forward along the screw by the rotation of the screw in the barrel.
 Pin Action Mechanism: The barrel is equipped with pins, and there are corresponding annular grooves on the screw. When the rubber passes through the pin area, the pin will shear, stir and divert the rubber. The rubber is continuously divided into small parts by the pin, so that it produces complex flows under the push of the screw, including lateral flow, vortex and rotational motion. This special flow mode allows the various parts of the rubber to be fully mixed, and the compounding agents (such as carbon black, vulcanizer, etc.) can be more evenly dispersed in the rubber, while accelerating the plasticization process of the rubber.
 Extrusion molding process: Under the continuous push of the screw, the fully plasticized and mixed rubber is squeezed through a die of a specific shape at the die head, thereby extruding into a rubber strip with the shape of the tread of the retreaded tire. The pressure control at the die head is very important for the dimensional accuracy and quality stability of the tread. The extrusion pressure can be controlled by reasonably adjusting the screw speed and the die resistance.

2. Structural composition
 Transmission system:
- It is usually composed of a high-performance motor and a precision reducer. The motor provides power, and the reducer is used to adjust the speed of the screw. For example, the use of a variable frequency speed motor can accurately control the screw speed to meet different production process requirements. The speed range can generally range from a few revolutions to tens of revolutions per minute, so that the extrusion speed of the rubber can be adjusted according to actual needs.
- The coupling is used to connect the motor and the reducer, as well as the reducer and the screw, to ensure the smoothness and efficiency of power transmission.
 Feeding system
- The feeding hopper is the entrance for the rubber to enter the extruder. Its shape and size design should take into account the shape of the rubber and the smoothness of the feeding. For rubber strip feeding, the bottom of the feed hopper usually has a suitable inclination angle to facilitate the smooth entry of the rubber strip into the barrel.
- Some advanced feeding systems are also equipped with forced feeding devices, such as screw feeders, which can ensure that the rubber enters the barrel at a stable rate to avoid uneven feeding, especially when processing rubber materials of different hardness and shape.
- **Barrel and screw**:
- The barrel is a cylindrical metal part with a screw inside. There is usually a heating or cooling device on the outside of the barrel. In a cold feed extruder, the barrel may need to be properly heated in the initial stage to help the initial plasticization of the rubber, but the temperature control is relatively low compared to hot feed extruders. The inner wall of the barrel is specially hardened to improve wear resistance, because the movement of the rubber in the barrel may cause wear on the inner wall.
- The screw is the core component of the extruder and its structure is relatively complex. There are different thread structures on the screw, including the conveying section, the plasticizing section and the metering section. In the pin cold feed extruder, the screw is also provided with an annular groove that matches the pin. Its parameters such as length, pitch and thread depth are designed according to the characteristics of rubber and the requirements of extrusion process.
- **Pin device**:
- Pins are usually made of metal, such as alloy steel, and their shapes are cylindrical, conical and other forms. The pins are installed on the inner wall of the barrel and arranged according to a certain pattern, generally in a circular distribution or matrix distribution. The size (length, diameter) and number of pins will be determined according to the size of the barrel and the amount of rubber processed. For example, a larger barrel may require more and longer pins to ensure sufficient mixing and plasticization of the rubber.
- **Heating and cooling system**:
- The heating system can be electrically heated or oil heated. The electrical heating method is achieved by a heating ring installed on the outside of the barrel. Its advantages are precise temperature control and fast heating speed. Oil heating transfers heat by circulating hot oil in the barrel interlayer, which is a more uniform heating method.
- The cooling system is mainly used to prevent the rubber from overheating in the barrel. Water cooling can be used to remove heat by setting a cooling water pipe outside the barrel. The cooling system and the heating system work together to control the temperature of the rubber in the barrel within a suitable range, generally between 60-100℃, and the specific temperature depends on the rubber formula and extrusion process.
- **Die head mold**:
- The die head is located at the front end of the extruder and is the key part that determines the shape and size of the tread of the retreaded tire. The internal channel shape of the die head mold is consistent with the final shape of the tire tread. For example, for a patterned tread, there is a corresponding pattern cavity inside the die head mold. The material of the mold is generally high-quality alloy steel with good wear resistance and thermal stability to ensure that the shape accuracy can be maintained during the long-term extrusion process.
 

3. Performance advantages
High product quality:
- Due to the action of the pins, the mixing and plasticization of the rubber is more uniform, and the extruded retread tire tread is more stable in physical properties. For example, indicators such as the hardness, tensile strength and wear resistance of the tread are more uniform over the entire length and cross-section, which helps to improve the overall quality and service life of the retreaded tire.
- It can better handle rubber formulas containing multiple ingredients, ensure that the ingredients are evenly dispersed in the rubber, and reduce tread quality problems caused by agglomeration of ingredients, such as abnormal local hardness or uneven vulcanization.
   Improved production efficiency:
- The cold feed method reduces the rubber preheating link, simplifies the production process, and improves production efficiency. Moreover, the pin's efficient mixing and plasticizing effect on the rubber allows the rubber to reach the extrusion state faster, and the screw speed can be increased accordingly, thereby increasing the extrusion speed of the tread. Generally speaking, compared with traditional extruders, the production efficiency of the pin cold feed extruder can be increased by about 30% - 50%.
    Reduced energy consumption:
- Although the cold feed extruder requires a certain amount of power to drive the screw to plasticize the cold rubber, due to its efficient working method, the energy consumption is relatively low throughout the production cycle. For example, at the same output, its power consumption may be reduced by 20% - 30% compared with the hot feed extruder. This is because the cold feed extruder does not need to preheat the rubber for a long time, and the optimized design of its screw and pins makes the plasticization process of rubber more energy-efficient.
    Wide range of application:
- It can handle many different types of rubber materials, including natural rubber, synthetic rubber and their mixed rubbers. For rubbers of different hardness, viscosity and elasticity, good extrusion effect can be achieved by adjusting parameters such as screw speed, pin arrangement (within a certain range) and temperature. At the same time, it can also be used to extrude retreaded tire treads with different shapes and pattern requirements, just need to replace the corresponding die mold.
4. Application scenarios
  Mainstream application in tire retreading industry: In the retreading process of various tires such as passenger car tires and truck tires, it is used to extrude the retreaded tire tread. Whether it is a patterned tread or a smooth tread, it can be extruded by adjusting the die mold.
   Special tire retreading field: It is also used in the retreading of some special purpose tires, such as engineering tires, aviation tires (partial retreading process), etc. However, in these special areas, the extruder parameters need to be more finely adjusted and controlled according to specific tire performance requirements and safety standards.