CN101875233A - Conical three-screw extruder arranged in line - Google Patents

Abstract

The invention discloses a straight conical three-screw extruder, which consists of a mouth die (1), a cylinder (2), three conical screws (3), a feeding hopper (4), a reduction box (5) and a motor (6). Through the reduction box, rotary motion is transmitted to the three screws through the motor. Three screws (7, 9 and 11) are all conical screws, and the center line is straight (figure 2). The three screws are all active and form two kneading areas (8, 10). The straight conical three-screw extruder integrates the advantages of a parallel three-screw extruder and a conical double-screw extruder, is used as a device for processing and mixing polymers such as plastic, rubber, propellant and the like and other materials, and improves the mixing, conveying and plasticating capabilities.

Description

Conical three-screw extruder arranged in line

technical field

The invention relates to an inline-arranged conical three-screw extruder, which can be used for mixing, extrusion, molding, reaction and other processes in the processing of plastics, rubber, synthetic fibers, coatings, pulp, pharmaceuticals, feed, food, explosives, etc. process. The machine can be used both in experiments and directly in production.

Background technique

The processing principle of the extruder is: feed the material into a screw device with heating, stirring and forward conveying. When the screw is screwed in, in addition to continuously screwing the material into the screw groove for continuous forward conveying , mainly because the material is on the inner side of the screw groove, gradually melted due to the temperature, and evenly turned and stirred in the screw groove. The shape is extruded into a long strip to form a product. And on the distinction of the main structural forms of existing extruders, there are three major categories: single-screw, twin-screw and multi-screw.

The internal mixing function of the single-screw extruder is very weak, mainly relying on the friction between the material and the screw and barrel, extrusion, high temperature heating and screw extrusion for plasticization. Generally, the speed and temperature are high, and the power consumption is high; it will generate quite high Back pressure, so the quality of the output is not easy to control, and the output is relatively reduced.

With the development of the polymer processing industry, higher and higher requirements are put forward for the molding and mixing process. Due to the inherent defects of its own structure (simple structure leads to simple flow field and insufficient mixing capacity), the single-screw extruder can no longer meet the requirements. These process requirements are mainly manifested in: (A) the filling amount is small during filling modification, and it is difficult to mix well; (B) in glass fiber reinforced modification, it is difficult to add glass fiber and the mixing effect is poor; (C) for rigid polyvinyl chloride Powder and other materials have poor processability. The twin-screw extruder can better meet the process requirements of the above aspects. In the twin-screw extruder, the convex rows of the two screws are staggered and opposed to each other, forming a "C-shaped" chamber. The material is sheared, rubbed, heated, and kneaded to enhance the mixing and plasticizing effect; Large conveying capacity, high output; generally do not need too high heating temperature, energy saving, high discharge speed; two screws mesh with each other, good self-cleaning effect, reducing the decomposition and carbonization of materials, so it is widely used.

Twin-screw extruders are divided into parallel twin-screw extruders and conical twin-screw extruders. Compared with the former, the outer taper angle of the outer diameter of the screw and the inner taper angle of the root diameter of the screw groove of the latter are different; the ratio of the diameter of the large and small end of the screw is greater than 1; the depth of the screw groove gradually changes along the entire length of the screw. Compared with the parallel meshing counter-rotating twin-screw extruder, the structural characteristics of the conical twin-screw determine that it not only has a closed screw groove cavity, forced conveying of materials, narrow distribution of material residence time, and good self-cleaning performance, but also has the following Unique advantages:

The diameter of the tail of the screw is increased, and the feeding amount is increased to increase the extrusion output of the extruder. The increase in the diameter of the tail of the screw also increases the load-bearing capacity of the screw. The service life of the gears and bearings is long, which is conducive to the arrangement of thrust bearings and gears; It is beneficial to heat conduction, and it is easier to heat or cool the material; the diameter of the screw in the discharge section is small, the peripheral speed is small, the shear generated is low, the frictional heat is small, and the risk of thermal damage is small; the volume of the screw groove is along the extrusion direction Gradual reduction, the material is gradually compressed, so that the screw groove is filled with the material faster, ensuring continuous and smooth plasticization of the material; under the same production capacity, the back pressure can be lower.

The traditional conical twin-screws are counter-rotating, and patent CN200510118915.3 invented a conical twin-screw extruder that rotates in the same direction. The material to be processed is extruded in a figure-eight shape around the double-conical screw in the barrel, which increases the plasticizing time and internal mixing performance, thus ensuring the plasticizing quality of the product. This machine has both good extrusion force and good plasticity, suitable for extrusion and granulation in plastic processing, which increases output and reduces energy consumption. It is a novel extruder suitable for processing various materials. . However, the two screws still can only form one kneading zone. With the rapid development of polymer blending and compound modification, the requirements for the refinement, dispersion and mixing effect of each component in processing are getting higher and higher, and correspondingly better plasticizing equipment is required to achieve high quality and high efficiency. , low energy consumption goals.

Patent 200620154843.8 develops a parallel three-screw extruder arranged in a line on the basis of a parallel twin-screw extruder. Three screws are arranged in parallel to form two kneading zones. Compared with the two-screw extruder, the three-screw extruder has the characteristics of friction shear and positive displacement conveying of two meshing zones, and the material has a larger contact area with the screw. Good mixing, good heat transfer, high melting capacity, excellent exhaust ability and better temperature control, and has lower energy consumption.

If the three screws are conical, it will develop into a conical three-screw extruder, and the rotation of the three screws can be combined in the same direction and in different directions. In this way, multiple advantages of parallel three-screw extruders and conical extruders can be combined, thereby further improving processing quality and efficiency, reducing energy consumption, and expanding the formation of new process applications. This is the idea of this patent.

Contents of the invention

The invention combines the advantages of the conical twin-screw extruder and the in-line arrangement of the parallel three-screw extruder.

In the present invention, the conical three-screw extruder arranged in line is composed of a die (1), a barrel (2), three conical screws (3), a hopper (4), a reduction box (5), a motor (6) Composition. Through the gearbox, the motor transmits the rotary motion to the three screws. The three screws are all conical screws, and the center distance gradually increases from the small end to the large end; the three screws (the three screws 7, 9, and 11 in Figure 1) are arranged in a straight line, that is, the centers of the three screws are located on the same cross section. On a straight line (Fig. 1); the shaded part of Fig. 1 represents the meshing area, and three screw rods mesh in pairs to form two meshing areas (8, 10 in Fig. 1), which is equivalent to the effect of two pairs of twin-screws. Driven by the output shaft of the reduction box, the three screws have four rotation direction combinations (Fig. 3, 4, 5, 6).

The doubling of the meshing area doubles the times of mastication, homogenization and shearing of the material in the screw, which effectively improves the mastication, melting and dispersion performance of the equipment, improves the quality of mastication, and shortens the processing time. Time, in line with the requirements of energy saving and emission reduction. The center distance of the three axes gradually increases from the small end to the large end, so that the three output shafts of the transmission gearbox have a larger center distance, which is the gears and gear shafts in the transmission system and the radial bearings and thrust supporting these gear shafts. There is a large installation space for the bearings, which is incomparable to parallel three-screw extruders arranged in a straight line. Moreover, the diameter of the feeding section is large, and the volume of the screw groove is large, so it is easy to add a large volume of bulk powder; the volume of the screw groove gradually decreases along the extrusion direction, and the material is gradually compressed, so that the screw groove is filled with the material faster and ensures the continuous flow of the material. Gently plasticized; the diameter of the screw in the discharge section is small, and under the same pressure and frictional resistance, the torque on the screw is small; under the same production capacity, the back pressure is low.

specific implementation plan

Driven by the motor 6, the three screw rods 7, 9, and 11 rotate and move independently through the deceleration and transmission distribution of the reduction box 5. The three screws (7, 9, 11) are all conical screws, and the center lines are arranged in a straight line (Fig. 1). The center distance of the three axes gradually increases from the small end to the large end, so that the three output shafts of the transmission gearbox There is a large center distance, which leaves a large installation space for the gears and gear shafts in the transmission system, as well as the radial bearings and thrust bearings that support these gear shafts. Three screws constitute two kneading zones (8, 10). The doubling of the meshing area doubles the times of mastication, homogenization and shearing of the material in the screw, which effectively improves the mastication, melting and dispersion performance of the equipment, improves the quality of mastication, and shortens the processing time. Time, in line with the requirements of energy saving and emission reduction. The material is fed from the feeding port 4, and extruded from the machine head under the shearing of the screw and the heating of the temperature control system on the barrel 2.

Description of drawings

Figure 1 is a schematic diagram of the kneading of the extruder screw

Figure 2 is a schematic diagram of the overall structure of the extruder

Figure 3-6 shows the combination of four rotation directions of the screw

Figure 7 is a three-dimensional schematic diagram of a screw combination of an extruder screw

Claims (4)

1. the conical three-screw rod extruder of yi word pattern arrangement comprises a mouthful mould, machine barrel, three conical screws, loading hopper, reduction box, motor.It is characterized in that: three screw rods are conical screw, and the center line yi word pattern is arranged, and the screw rod of three independent rotations has formed two and mediated the district.

2. require described three screw rods to be conical screw as right 1, the center line yi word pattern is arranged, and it is characterized in that: on same section, and being centered close on same the straight line of three screw rods.

3. requiring described three screw rods to form two as right 1 mediates the district, it is characterized in that: per two adjacent screw rods form one and mediate the district.

4. require described three screw rods all independently to rotatablely move as right 1, it is characterized in that: three screw rods independently rotatablely move respectively under the drive of reduction gearbox output shaft, can carry out in the same way and incorgruous combination direction of rotation, have direction of rotation direction combination in 4.

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