CN102189664A - Differential extruder with three straightly-arranged screws - Google Patents

Abstract

The invention relates to a differential extruder with three straightly-arranged screws. The differential extruder mainly comprises a feeding device, a machine barrel, the screws, a machine head, a heating/cooling device, an exhaust port, a motor and a transmission device, wherein the three screws are straightly arranged; if a middle screw is a male rotor, screws on the two sides are female rotors, and if the middle screw is a female rotor, the screws on the two sides are male rotors; at least one thread engagement area is provided when the three screws are combined; and the screw flight quantity of the female rotors in the area is integral multiples of that of the male rotors, and the rotating speeds of the female and male rotors are inversely proportional to the screw flight quantity, so that differential rotation can be realized, and the female and male rotors do not interfere with each other during movement. According to the machining requirements of materials, threaded sections or other forms with different leads and cross section molded lines can be arranged in different sections of charging sections, melting sections, exhaust sections and metering sections of the screws; and the at least one thread engagement area in a differential rotation mode can be provided when the three screws are arranged, and the screws can be engaged with one another or can be separated from one another in the different sections, so that mixing and exhaust effects or other functions can be enhanced. The extruder has high mixing, plasticization and delivery capabilities, and is suitable for machine-shaping of various materials such as plastic, rubber, foods, explosives and the like.

Description

Differential speed three-screw extruder with in-line arrangement of screws

technical field

The differential speed three-screw extruder with the screws arranged in a straight line of the present invention is suitable for conveying, plasticizing, mixing, granulating, extrusion molding and reactive extrusion processing of materials, and can be used in petroleum, chemical industry, rubber, plastic, food, Industries such as pharmaceuticals, explosives and propellants.

Background technique

In industries such as petroleum, chemical, rubber, plastic, pharmaceutical, food, explosives and propellants, it is often involved in the mixing, shearing and plasticizing of high-viscosity fluids. Extruders and kneaders are used to achieve these functions. important equipment. The three-screw extruder is significantly better than the single-screw extruder and twin-screw extruder in terms of mixing effect and output, and it solves the defects of large space occupation, low efficiency and non-continuous operation of the traditional kneader. development prospects.

Patent CN201079735Y provides a differential twin-screw kneader, which not only has the mixing, shearing and plasticizing and kneading effects of traditional kneading equipment on high-viscosity fluids, but also has the characteristics of continuous extrusion of counter-rotating twin-screw extruders. During the working process of the differential twin-screw kneader, the two screws mesh with each other. There is an intermeshing zone between the two screws, where there is a speed difference between the flight and the groove, which significantly enhances the mixing effect. However, the axial thread structure of the screw in this patent is exactly the same, which cannot adapt to the different thread structures required by different processing stages of materials; the patent stipulates that the number of thread heads of the male rotor is 1, and the form is too single; and the patent is only a continuous The kneader is not very suitable for extrusion molding, granulation, mixing, etc. of materials.

Patent 200620154843.8 develops a three-screw extruder arranged in a line on the basis of a twin-screw extruder. Three screws are arranged in parallel to form two kneading zones. Compared with the twin-screw extruder, the three-screw extruder has the positive displacement conveying characteristics of two meshing zones, and the material and the screw have a larger contact area, which is equivalent to two pairs of twin-screws. The three-screw extruder has full mixing, good heat transfer, large melting capacity, excellent venting capacity and better temperature control, and has lower energy consumption.

If the structure of the differential twin-screw kneader is improved, and a screw is added to form two meshing zones, then both energy saving and product quality will have better results.

Contents of the invention

The differential-speed three-screw extruder with the screws arranged in a straight line of the present invention is mainly composed of a feeding device, a machine barrel, a screw, a machine head, a heating device, an exhaust device, a motor, and a transmission device. Three screw rods are arranged in a straight line. During the working process, the three screws mesh with each other to form two meshing areas.

The screw is divided into a female rotor and a male rotor. The one with more screw heads is called the female rotor, and the one with the few screw heads is called the male rotor. The three screws in the barrel form two groups of meshes, and there are two combinations, one is two male rotors and one female rotor, and the female rotor is in the middle, and the other is two female rotors and one male rotor, and the male rotor is in the middle. When the three screws are combined, there is at least one thread meshing area. The number of screw heads of the female rotor in this area is an integer multiple of the number of male rotors. The rotation speed of the male and female rotors is inversely proportional to the number of screw heads, which can realize differential rotation. In the thread meshing area of differential rotation, the section profile of the rotor is formed by connecting several sections of curves sequentially, and the profile lines of the male and female rotors correspond to each other, conjugate meshing, and form a good meshing state during differential motion to ensure non-interference.

During the working process of the differential three-screw extruder, the three screws mesh with each other to form two meshing zones. In the thread meshing area of differential rotation, the adjacent male and female rotor screw pairs can be conjugated in theory, and the positive displacement transmission capacity and pressure capacity are very strong. In the meshing area, a large speed difference is formed between the flight and flight of the female rotor and the flight and flight of the corresponding male rotor due to the difference in screw speed, which has multiple functions such as shearing and stretching, so Significantly enhanced mixing and plasticizing effects. Moreover, during the intermeshing process of the male and female rotors, the materials adhered to the screw are peeled off from each other, which has self-cleaning ability.

In order to better adapt to the processing requirements of the material, different sections of the feeding section, melting section, exhaust section and metering section of the screw can be set to different lead and end surface profiles, and even change the thread section of the number of screw heads. or other forms. When the three screws are installed, it is guaranteed to have at least one thread meshing area of differential rotation, which can be meshed or not meshed in different sections, so as to achieve enhanced mixing, exhaust effect or other functions. For example, in order to further enhance the mixing ability of the equipment and achieve stable extrusion, pin screw segments or toothed discs can be added in a certain section, but it must be ensured that the male and female rotors do not interfere when they move; Set the exhaust port, and the exhaust port is connected to the exhaust device to realize the devolatilization of moisture and other gases and improve the quality of the product.

Description of drawings

Figure 1 is a structural schematic diagram of a differential three-screw extruder with screws arranged in a straight line

1-head, 2-barrel, 3-heating and cooling device, 4-exhaust port, 5-screw, 6-feeding device, 7-mounting seat, 8-coupling, 9-reduction box, 10-motor , 11-rack.

Figure 2 is a schematic diagram of meshing of two male rotors and one female rotor

Figure 3 is a schematic diagram of meshing of two female rotors and one male rotor

Figure 4 is a schematic cross-sectional view of the meshing screw section in Figure 2, the number of male rotor heads is 1, and the number of female rotor heads is 4

Figure 5 is a schematic cross-sectional view of the meshing screw section in Figure 3, the number of male rotor heads is 1, and the number of female rotor heads is 4

Figure 6 is a schematic cross-sectional view of the meshing screw section, the number of male rotor heads is 2, and the number of female rotor heads is 3

Figure 7 is a schematic cross-sectional view of the meshing screw section, the number of female rotor heads is 3, and the number of male rotor heads is 2

Figure 8 is a cross-sectional view of the screw section with pin mounting holes when the screw mixing section uses a pin screw

Figure 9 is a side view of the screw mixing section using meshing disc elements

Figure 10 is a front view of the screw mixing section using meshing disc elements

specific implementation plan

Implementation Case 1

According to Figure 1, design the differential speed three-screw extruder with the screws arranged in a straight line. Fig. 2 is a schematic diagram of screw engagement when two male rotors and one female rotor are used for the three screws in Fig. 1, the middle screw is a female rotor, and the screws at both ends are male rotors. Fig. 3 is a schematic diagram of screw meshing when two female rotors and one male rotor are used for the three screws in Fig. 1, the middle screw is a male rotor, and the screws at both ends are female rotors. Three screw rods 5 in the extruder adopt the arrangement form shown in Fig. 2 or Fig. 3 . Among them, in the thread meshing area, the number of screw heads of the male rotor is 1, and the number of screw heads of the female rotor is 4. The high-speed motor distributes the torque to the male and female rotors through the reduction box 9 and the coupling 8, and the speed ratio is 1/4. The screw 5 is assembled and placed in the barrel 2 fixed on the mounting base 7. The barrel 2 has an exhaust port 4, and the temperature is adjusted through the external heating and cooling device 3. The barrel 2, the reduction box 9 and the motor are directly installed on the frame. 11 on.

Add the material to be processed from the feeding port 6, and the material changes from pellets or powder to molten state after being transported by solid, compressed and melted. When passing through the exhaust port 4, the moisture and volatile gas in the material are discharged out of the barrel through the exhaust device. A mixing section is set on the screw close to the machine head 1, in the form of a holed screw with pins as shown in Figure 8. The pins on the screw have the functions of dividing the material flow, increasing the interface, changing the direction of the material flow, reorienting the interface, and rearranging the material flow. Distributive mixing is achieved through multiple diversions, merging, and reorientation, which makes up for the shortcomings of the rotor's poor ability to distribute and mix in counter-rotating directions. After the material passes through the mixing section, it is extruded through the machine head 1.

As shown in Figure 4 and Figure 5, the three screws form two meshing zones, which is equivalent to two pairs of twin-screws in parallel, which can improve the mixing quality and extrusion output. Wherein, FIG. 4 is a schematic cross-sectional diagram of the intermeshing screw section in FIG. 2 ; FIG. 5 is a schematic cross-sectional diagram of the intermeshing screw section in FIG. 3 . In comparison, the manufacture and maintenance of two male rotors and one female rotor shown in Figure 4 are more convenient.

Implementation Case 2

A differential three-screw extruder is formed similarly to Example 1. The difference is that the number of screw heads is different, and the meshing differential ratio formed is different. Among them, Figure 6 shows that the number of male rotor heads in the meshing screw section is 2, and the number of female rotor heads is 3. The speed ratio is 2/3, and two male rotors are distributed on both sides of a female rotor; Figure 7 shows the female rotor heads Each number is 3, the number of heads of the male rotor is 2, the speed ratio is 3/2, and two female rotors are distributed on both sides of a male rotor.

Implementation Case Three

A differential three-screw extruder is formed similarly to Example 1. The difference is that the screw is in the mixing section close to the machine head 1, which adopts the form of meshing discs shown in Fig. 9 and Fig. 10 . The non-staggered area of the screw toothed disc can divide the material, increase the interface, provide the minimum energy input, facilitate the distribution and mixing, and generate a lower temperature; the shearing of the material perpendicular to the flow direction in the interlaced area is also beneficial Distribution mixing makes up for the shortcoming of insufficient distribution mixing ability.

Claims (3)

1. The differential speed three-screw extruder with the screws arranged in a straight line is mainly composed of a feeding device, a barrel, a screw, a machine head, a heating and cooling device, an exhaust port, a motor, and a transmission device. It is characterized in that: the combination of three screws There is at least one thread meshing area, the number of screw heads of the female rotor in this area is an integral multiple of the number of male rotors, and the rotation speed of the male and female rotors is inversely proportional to the number of screw heads, which can realize differential rotation without interference during movement. 2. The differential speed three-screw extruder according to claim 1, characterized in that: the three screws are arranged in a straight line, the middle screw is a male rotor, and both sides are female rotors; the middle screw is a female rotor, and both sides are For the male rotor. 3. The differential speed three-screw extruder according to claim 1, characterized in that: according to material processing requirements, different sections of the feeding section, melting section, exhaust section and metering section of the screw can be set as For thread sections or other forms with different leads and cross-section lines, the three screws are installed to ensure that there is at least one thread engagement area of differential rotation, and they can be engaged or not engaged in different sections to achieve enhanced mixing. refining, exhaust effects or other functions.

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