CN100443285C - A compound co-extrusion screw extruder - Google Patents

Abstract

The invention relates to a compound co-extrusion screw extruder, which is mainly composed of a feeding device, a machine barrel, a screw, an extruder head, a motor and a transmission device. The machine barrel is equipped with nested inner and outer screws, and the inner and outer screws The screw direction is opposite, and the inner and outer screws rotate relative to each other in the opposite direction. There are first feeding port and second feeding port on the barrel. The first feeding port corresponds to the feeding section of the outer screw, and the feeding section of the outer screw is opened before There is an annular groove, which corresponds to the second feeding port of the machine barrel. The outer ring surface of the annular groove and the inner surface of the machine barrel form a closed annular storage room. The bottom of the annular storage room is opened to allow the second material to enter the inner screw. Feed holes, nested screws are connected to the same extruder head. The invention realizes single-machine double-layer co-extrusion, can cooperate with single-layer or multi-layer extrusion, reduces the number of co-extrusion machines, saves investment and equipment occupation area, and has high extrusion efficiency and improves product processing quality.

Description

A compound co-extrusion screw extruder

technical field

The invention relates to a composite co-extrusion screw extruder, which can be used for composite co-extrusion of plastic products such as composite plates, films, pipes, sheets, optical fiber cables and the like.

Background technique

Composite co-extrusion is a processing method in which two or more polymers with different properties are co-extruded to form a multi-layer single product. Such as multi-layer sheets, films, plates, pipes, cables and multi-layer hollow containers. At present, the equipment used for compound co-extrusion is a combination of two or more screw extruders, which extrude different materials into the co-extrusion die for compounding. The equipment investment is large, complex, and the equipment occupies a large area. , especially the more layers of composite products, the more prominent this problem is. In addition, the molten materials from different extruder barrels must be redistributed to meet the requirements of the designed product shape. The molten polymer is distributed during the distribution process. In the process, the different flow areas caused by different melting temperature and residence time distribution, not only low efficiency, thus affecting the appearance and quality of the product, for example, due to the use of separators, traces of "welding lines" will be formed on the melt, etc. question.

Contents of the invention

The technical problem to be solved by the present invention is to realize single-machine double-layer co-extrusion, that is, to use one device to extrude two kinds of materials at the same time, to avoid or reduce the redistribution of molten materials, thereby improving the composite extrusion efficiency and improving the quality of composite products .

The present invention is mainly composed of a feeding device, a machine barrel, an inner screw and an outer screw nested in the barrel, an extruder head, a motor and a transmission device, wherein: the inner screw is directly nested in the outer screw, and the helix of the inner and outer screws The directions are opposite, and the inner and outer screws rotate relative to each other in the opposite direction. There are a first feeding port and a second feeding port on the barrel. The first feeding port corresponds to the feeding section of the outer screw. The annular groove corresponds to the second feeding port of the machine barrel. The outer ring surface of the annular groove and the inner surface of the barrel form a closed annular storage room. The bottom of the annular storage room is opened to allow the second material to enter the inner screw. Holes, the nested screw is connected to the same extruder head.

The above-mentioned outer screw rod is driven by a motor to rotate, and the inner screw rod is fixed on the stator, so that the inner and outer screw rods perform opposite relative rotation movements.

The above-mentioned internal and external screw rods are respectively driven by motors for counter-rotational motion.

A heating ring is installed on the outer circumference of the above-mentioned machine barrel to heat the screw and the machine barrel.

The above-mentioned inner screw core is equipped with a heating rod to heat the inner screw.

The core of the above-mentioned inner screw can also be passed with heat conduction oil to heat the inner screw.

The effect of the present invention: due to the inner screw with reverse rotation and helical direction nested in the outer screw, the inner and outer screws can extrude the same or different materials at the same time, the relative speed of the inner screw is the sum of the actual speed of the inner and outer screws, and the inner screw The relative speed is greatly increased, and the conveying capacity and output of the internal screw are also increased accordingly; when extruding the same material, one extruder can be equivalent to the effect of two single-screw extruders, which improves the output and extrusion efficiency; When extruding different materials, it can realize single-machine double-layer co-extrusion, and can also reduce the number of hosts of multi-layer co-extrusion units, saving investment and equipment footprint, and has high extrusion efficiency, simple operation and simple maintenance. In addition, the single-machine double-layer co-extrusion compound head is used, and the material will not enter from the side, which can make up for the shortcomings of the traditional co-extrusion technology, avoid the traces of "welding lines", and improve the quality of product processing.

Description of drawings

Figure 1: Schematic diagram of the structure of the present invention.

Figure 2: A-A sectional view of Figure 1.

Figure 3: B-B sectional view in Figure 2

Detailed ways:

As shown in Fig. 1, Fig. 2 and Fig. 3, the composite co-extrusion screw extruder of the present invention mainly includes: a motor 13, which is decelerated by a reduction box 2, a drive wheel 3, a machine barrel 10, and an inner screw embedded in an outer screw 11 12. The helical directions of the inner and outer screws are opposite, and the inner and outer screws make opposite relative rotation movements. There are first feeding port 8 and second feeding port 5 on the barrel, and the first feeding port 8 and the outer screw 11 Corresponding to the feeding section, there is an annular groove 14 in front of the outer screw feeding section, the annular groove corresponds to the second feeding port 5 of the machine barrel, and the closed annular storage chamber formed by the outer ring surface of the annular groove and the inner surface of the machine barrel, the annular storage There are evenly distributed feed holes 15 at the bottom of the material chamber, so that the second material enters the inner screw for melt extrusion, and the nested screw is connected to the compound extruder head.

The inner and outer screws adopt the commonly used screw heating method, and the preferred method is: a wrapping heating ring 9 is installed on the outer circumference of the machine barrel 10 to heat the outer screw. The core of the inner screw is equipped with a heating rod 16 for heating the inner screw. The core of the inner screw can also be fed with heat transfer oil to heat the inner screw.

The inner and outer screws perform reverse relative rotation, and different connection methods can be adopted. The better way is that the outer screw is driven by a motor to rotate, and the inner screw is fixed on the stator 1 (see Figure 1). The advantage is that it saves power and is easy to control; in another way, the inner and outer screws are respectively driven by the motor to rotate in the opposite direction. From the relative motion analysis, it can be known that the relative speed of the inner screw is n, and the absolute speed of the outer screw is n ₁ . The absolute rotational speed of the internal screw is n ₂ , n=n ₁ +n ₂ , the material flow direction of the internal screw is the same as that of the external screw, the relative rotational speed of the internal screw is greatly increased, and the conveying capacity and output are correspondingly increased. In order to facilitate processing, the barrel adopts segmented barrel.

The working principle of this extruder (see Figure 1): When the motor drives the outer screw to rotate, it produces an opposite rotational movement with the inner screw (fixed or driven by the motor alone), and the metering feeder 7 controls a material from the first One feeding port 8 is added, and enters the external screw for extrusion, conveying, plasticizing, and melting. The metering feeder 4 controls another material to enter from the second feeding port 5 into the circular groove at the front end of the external screw and the inner surface of the barrel. Close the material storage room, distribute circumferentially along the annular groove of the outer screw, and enter the inner screw from the feeding hole 15 at the bottom of the annular storage room, and the material entering the inner screw is driven by the rotation of the outer screw and the heating rod of the core. Extrusion, conveying, plasticizing and melting, because the rotation direction of the inner screw is opposite to that of the outer screw, and the screw helix direction of the inner and outer screws is also opposite, so that the two materials are conveyed in the same direction of the screw and merged into the same extruder head for compounding Extrusion molding, from the analysis of relative motion, it can be known that the relative speed of the inner screw is the sum of the speed of the inner and outer screws, and the relative speed increases, and the conveying capacity and output are also greatly improved. The closed chamber formed by the circular groove of the outer screw and the inner surface of the barrel is cooled by the inner liner 6 of the barrel to ensure that the material added from the second feeding port 5 enters the inner screw 12 smoothly. In the practical application of this extruder, two different materials can be extruded to realize single-machine double-layer co-extrusion, and it can also be used in multi-layer co-extrusion units to reduce the number of unit units to achieve multi-layer co-extrusion, reduce equipment costs, and improve product quality. quality. The application effect of the present invention is illustrated below through the application examples of the extruder.

Embodiment 1: Extrude the composite sheet with the compound co-extrusion screw extruder of the present invention, the first layer is polypropylene PP, the second layer is polyethylene PE, adopts compound co-extrusion sheet head, outer screw diameter D ₁ = 120mm, aspect ratio ${\left(\frac{L}{\mathrm{D.}}\right)}_1=25:1,$ Internal screw D ₂ = 65mm, aspect ratio ${\left(\frac{L}{\mathrm{D.}}\right)}_2=28:1$ The outer screw extrudes polypropylene (PP) and the inner screw extrudes polyethylene (PE). The outer screw rotates under the drive of the motor, the outer screw speed n ₁ =20-40r/min, and the inner screw is fixed on the stator. The barrel is a segmented barrel, and the temperature of each section of the outer edge heating ring is: the first section is 160°C to 165°C, the second section is 170°C to 180°C, the third section is 190°C to 200°C, and the fourth section is 210°C. ℃～220℃, the oil temperature of the inner screw core is 160℃. The layer thickness of the layered sheet can be adjusted by the rotation speed of the inner and outer screws, extruding a double-layer composite sheet structure, wherein δ ₁ =5mm, δ ₂ =3mm.

Embodiment 2: Extrude the composite pipe with the composite co-extrusion screw extruder of the present invention, the first layer A is polypropylene (PP), the second layer B is polyethylene (PE), and the composite co-extrusion pipe head is adopted, External screw diameter D ₁ =90mm, aspect ratio ${\left(\frac{L}{\mathrm{D.}}\right)}_1=25;$ Internal screw D ₂ ＝45mm, aspect ratio ${\left(\frac{L}{\mathrm{D.}}\right)}_2=28,$ The material PP is extruded by the external screw, and the material PE is extruded by the internal screw. The internal screw and the external screw are driven by their respective motors to perform reverse rotation. The external screw speed n ₁ =20~40r/min, the internal screw speed is n ₂ ＝0～30r/min, in order to meet the needs of adjusting the thickness of the inner and outer layers of the composite pipe, the internal screw speed can be zero. The temperature of each section of the heating ring on the outer edge of the barrel is 160°C to 165°C in the first section, 170°C to 180°C in the second section, 190°C to 200°C in the third section, and 210°C to 220°C in the fourth section. The part is heated with a heating rod at a temperature of 160°C. The thickness of the inner and outer layers of the composite pipe can be adjusted by the speed of the inner and outer screws. Extrude a double-layer composite pipe with an outer diameter of D=75mm, where the thickness of layer A is δ ₁ =5mm, and the thickness of layer B is δ ₂ =3mm.

Claims (6)

1. A composite co-extrusion screw extruder, mainly composed of a feeding device, a machine barrel, an inner screw and an outer screw nested in the barrel, an extruder head, a motor and a transmission device, characterized in that the inner screw directly Nested in the outer screw, the helical directions of the inner and outer screws are opposite, and the inner and outer screws perform opposite relative rotation movements. There are first feeding port and second feeding port on the barrel, and the first feeding port and the outer screw Corresponding to the feeding section, there is an annular groove in front of the feeding section of the outer screw, which corresponds to the second feeding port of the barrel, the outer ring surface of the annular groove and the inner surface of the barrel form a closed annular storage room, and the bottom of the annular storage room is opened There is a feeding hole for the second material to enter the inner screw, and the nested screw is connected to the same extruder head. 2. The screw extruder according to claim 1, characterized in that: the outer screw is driven to rotate by a motor, and the inner screw is fixed on the stator, so that the inner and outer screws rotate relative to each other in opposite directions. 3. The screw extruder according to claim 1, characterized in that: the inner and outer screws are respectively driven by motors for counter-rotation. 4. The screw extruder according to claim 1, characterized in that: a heating ring is installed and wrapped on the outer circumference of the barrel to heat the screw and the barrel. 5. The screw extruder according to claim 1, characterized in that: a heating rod is installed at the core of the inner screw to heat the inner screw. 6. The screw extruder according to claim 1, characterized in that: the core of the inner screw is connected with heat conduction oil to heat the inner screw.

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