A screw extruder and a fiber spinning, drawing and winding combined machine for polylactic acid industry

Abstract

The present invention discloses a screw extruder, which relates to the technical field of spinning production, and solves the technical problem in the related technology that the bio-based polylactic acid raw material is unstable and hydrolysis has a serious impact on the subsequent spinning. It includes a screw sleeve and a screw inserted in the screw sleeve, the screw includes a feed section, a compression section and a metering section arranged in sequence, the screw sleeve includes a gas collection chamber and an exhaust hole, the gas collection chamber is on the inner wall at the junction of the compression section and the metering section, the exhaust hole is connected to the gas collection chamber, wherein the screw sleeve is equipped with an on-off valve for opening and closing the exhaust hole. The gas is collected by the gas collection chamber located at the end of the compression section, and the gas generated by the hydrolysis is discharged from the exhaust hole through the control of the on-off valve, and the gas is removed in time when the melt enters the metering section, thereby overcoming the serious adverse effects of the hydrolysis gas on the spinning, improving the adverse situation of the broken end, and ensuring the quality and efficiency of the subsequent spinning.

Description

Technical Field

[0001] The invention relates to the technical field of spinning production, in particular to a screw extruder and a fiber spinning, drawing and winding combined machine for polylactic acid industry. Background Art

[0002] Most of the existing polylactic acid industrial fiber filament spinning, drawing and winding equipment are modified from other types of equipment. The biggest disadvantage is that the product quality and performance are unstable. Due to the instability of bio-based polylactic acid raw materials, the slices will be hydrolyzed during the melting process, producing gas and weak acid corrosive substances. In particular, the generation of gas has a serious impact on the subsequent spinning, the most obvious being a large number of broken ends, which urgently needs to be improved. Summary of the invention

[0003] The present application provides a screw extruder and a fiber spinning, drawing and winding combined machine for the polylactic acid industry, which solves the technical problem in the related art that the bio-based polylactic acid raw materials are unstable and hydrolyzed, causing serious impact on subsequent spinning.

[0004] The present application provides a screw extruder, comprising a screw sleeve and a screw inserted into the screw sleeve, the screw comprising a feed section, a compression section and a metering section arranged in sequence, the screw sleeve comprising a gas collecting chamber and an exhaust hole, the gas collecting chamber is on the inner wall at the junction of the compression section and the metering section, the exhaust hole is connected to the gas collecting chamber, wherein the screw sleeve is equipped with an on-off valve for opening and closing the exhaust hole.

[0005] Optionally, the screw sleeve includes a first screw sleeve and a second screw sleeve that are connected to each other, the screw rod is inserted into the first screw sleeve and the second screw sleeve, the first screw sleeve is provided with an exhaust hole and an opening and closing valve, the inner wall of the first screw sleeve at one end close to the second screw sleeve is recessed, a sealing gasket is provided between the first screw sleeve and the second screw sleeve, and / or the inner wall of the second screw sleeve at one end close to the first screw sleeve is recessed, and the first screw sleeve, the sealing gasket, the second screw sleeve and the screw rod together enclose a gas collection chamber.

[0006] Optionally, the feed section is provided with a single-thread screw, and the compression section is provided with a double-thread screw.

[0007] Optionally, the compression section includes a first compression section and a second compression section, the first compression section and the second compression section are arranged in a double-thread screw, and the screw includes a feed section, a first compression section, a second compression section and a metering section arranged in sequence;

[0008] Along the material conveying direction in the screw extruder, the groove depths of the first compression section and the second compression section gradually decrease, and the groove depth variation degree of the second compression section is smaller than that of the first compression section.

[0009] Optionally, the screw sleeve includes an electric contact pressure gauge, and a measuring end of the electric contact pressure gauge is connected to the gas collection chamber.

[0010] Optionally, the screw sleeve includes a base arranged at the outer edge, the exhaust hole is L-shaped and arranged inside the base, the two ends of the exhaust hole are respectively connected to the gas collection chamber and the outside atmosphere, and the opening and closing valve is installed on the base;

[0011] The on-off valve includes:

[0012] A valve body, wherein the valve body portion is disposed inside the base;

[0013] The valve stem is movably arranged in the valve body, and the end of the valve stem is arranged in an arc surface to close or open the L-shaped bend of the exhaust hole;

[0014] A packing seal is arranged inside the base and between the base and the valve stem;

[0015] The bushing is arranged at the L-shaped bending part of the exhaust hole of the base, and the bushing is configured to abut against the arc surface of the end of the valve stem.

[0016] Optionally, the on-off valve includes a manual setting or an automatic setting;

[0017] One end of the exhaust hole is directly connected to the outside atmosphere or is connected to the outside atmosphere through a vacuum pump.

[0018] Optionally, along the material conveying direction in the screw extruder, the metering section includes a first double-thread structure, a diamond-shaped separation structure, and a second double-thread structure in sequence, and the diamond-shaped separation structure is an integrally milled diamond or diamond-shaped pin processing setting.

[0019] Optionally, along the material conveying direction in the screw extruder, the diameter of the diamond-shaped separation structure gradually decreases and the diamond arrangement density gradually decreases;

[0020] The screw of the first double-thread structure part is provided with a plurality of V-shaped grooves distributed along the spiral ring.

[0021] A fiber spinning, stretching and winding combined machine for polylactic acid industry comprises the above-mentioned screw extruder, and the extruder head arranged on the head of the screw extruder is equipped with a melt pressure sensor.

[0022] The beneficial effects of the present application are as follows: The present application provides a screw extruder, comprising a screw sleeve and a screw inserted into the screw sleeve, an external heater is arranged outside the screw sleeve to provide heat, the screw comprises a feed section, a compression section and a metering section arranged in sequence, when the polylactic acid raw material enters the feed section, it gradually changes from a solid state as the temperature rises step by step, and at the same time, it changes into a molten melt under the shear heat between the raw materials, in the compression section, the solid material is compressed and sheared to be fully melted to a liquid phase, hydrolysis will occur during the melting process, and the generated gas will have a serious impact on subsequent spinning, the gas is collected by a gas collection chamber located at the end of the compression section, and is controlled by an opening and closing valve to discharge the gas generated by the hydrolysis from the exhaust hole, and the gas is removed in time when the melt enters the metering section, thereby overcoming the serious adverse effects of the hydrolysis gas on spinning, improving the adverse situation of breakage, and ensuring the subsequent spinning quality and spinning efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0024] Figure 1 A schematic diagram of the overall structure of a screw extruder provided in this application;

[0025] Figure 2 for Figure 1 Schematic diagram of the local structure at A in the middle;

[0026] Figure 3 for Figure 2 Schematic diagram of cross-section comparison of G1-G1, G2-G2, and G3-G3;

[0027] Figure 4 for Figure 1 A partial enlarged view of point B in the middle;

[0028] Figure 5 for Figure 4 A schematic diagram of another possible implementation method;

[0029] Figure 6 for Figure 4 A schematic diagram of another possible implementation method;

[0030] Figure 7 for Figure 1 A partial enlarged view of point C in the middle;

[0031] Figure 8 for Figure 1 A partial enlarged view of point D in the middle;

[0032] Fig. 9 for Figure 1 A partial enlarged view of EE in the middle.

[0033] Figure markings: 1-a-screw sleeve, 1-b-screw, 1-c-base, 1-1-first screw sleeve, 1-2-electric contact pressure gauge, 1-3-on-off valve, 1-3a-valve stem, 1-3b-valve body, 1-3c-packing seal, 1-3d-exhaust hole, 1-3e-bushing, 1-3f-sealing pad, 1-3g-gas collection chamber, 1-3h-electric vacuum pump, 1-3i-manual needle valve, 1-3j-electric needle valve, 1-4-second screw sleeve, 1-5a-metering section, 1-5a1-second double thread structure, 1-5a2-diamond separate structure, 1-5a3-first double thread structure, 1-5a3-1~4-grooved V-groove, 1-5b-second compression section, 1-5c-first compression section, 1-5d-feeding section. DETAILED DESCRIPTION

[0034] The embodiments of the present application provide a screw extruder and a fiber spinning, stretching and winding combined machine for the polylactic acid industry, thereby solving the technical problem in the related art that the bio-based polylactic acid raw materials are unstable and hydrolyzed, causing serious impact on subsequent spinning.

[0035] The technical solution in the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows:

[0036] A screw extruder comprises a screw sleeve and a screw inserted into the screw sleeve, wherein the screw comprises a feed section, a compression section and a metering section which are arranged in sequence, the screw sleeve comprises a gas collecting chamber and an exhaust hole, the gas collecting chamber is on the inner wall at the junction of the compression section and the metering section, the exhaust hole is connected to the gas collecting chamber, and the screw sleeve is provided with an on-off valve for opening and closing the exhaust hole.

[0037] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0038] Please refer to Figure 1 and Figure 4 This embodiment discloses a screw extruder, including a screw sleeve 1-a and a screw 1-b inserted into the screw sleeve 1-a, wherein the screw 1-b includes a feed section 1-5d, a compression section (such as Figure 1 The middle compression section is presented as a first compression section 1-5c and a second compression section 1-5b, and may also be presented in other forms) and a metering section 1-5a. The screw sleeve 1-a includes a gas collection chamber 1-3g and an exhaust hole 1-3d. The gas collection chamber 1-3g is on the inner wall at the junction of the compression section and the metering section 1-5a. The exhaust hole 1-3d is connected to the gas collection chamber 1-3g, wherein the screw sleeve 1-a is equipped with an on-off valve 1-3 for opening and closing the exhaust hole 1-3d.

[0039] The outer sleeve 1-a is provided with an external heater to provide heat. The screw 1-b includes a feed section 1-5d, a compression section and a metering section 1-5a arranged in sequence. When the polylactic acid raw material enters the feed section 1-5d, it gradually changes from a solid to a molten melt as the temperature rises step by step. At the same time, it changes into a molten melt under the shear heat between the raw materials. In the compression section, the solid material is fully melted to a liquid phase by compression and shear. When the bio-based polylactic acid raw material is heated, a small part of the raw material structure is unstable and chemical changes occur, and hydrolysis occurs. The generated gas has a serious impact on the subsequent spinning. The gas is collected by the gas collection chamber 1-3g located at the end of the compression section, and the gas generated by the hydrolysis is concentrated and discharged from the exhaust hole 1-3d through the control of the opening and closing valve 1-3. When the melt enters the metering section 1-5a, the gas is removed in time, thereby overcoming the serious adverse effects of the hydrolysis gas on spinning, improving the adverse situation of broken ends, and ensuring the subsequent spinning quality and spinning efficiency.

[0040] Alternatively, if Figure 1 and Figure 4 As shown, the screw sleeve 1-a includes a first screw sleeve 1-1 and a second screw sleeve 1-4 connected to each other, a screw rod 1-b is inserted into the first screw sleeve 1-1 and the second screw sleeve 1-4, the first screw sleeve 1-1 is provided with an exhaust hole 1-3d and is installed with an opening and closing valve 1-3, the inner wall of one end of the first screw sleeve 1-1 close to the second screw sleeve 1-4 is recessed, a sealing gasket 1-3f is provided between the first screw sleeve 1-1 and the second screw sleeve 1-4, and / or the inner wall of one end of the second screw sleeve 1-4 close to the first screw sleeve 1-1 is recessed, the first screw sleeve 1-1, the sealing gasket 1-3f, the second screw sleeve 1-4 and the screw rod 1-b together enclose a gas collection chamber 1-3g.

[0041] The screw sleeve 1-a is arranged in the form of a combination of a first screw sleeve 1-1 and a second screw sleeve 1-4 so as to assemble and form a gas collection chamber 1-3g. A sealing gasket 1-3f is arranged between the first screw sleeve 1-1 and the second screw sleeve 1-4, which means that the sealing gasket 1-3f is arranged at the butt joint surface of the first screw sleeve 1-1 and the second screw sleeve 1-4, and the first screw sleeve 1-1 and the second screw sleeve 1-4 can be connected by bolts, and the sealing gasket 1-3f is used to ensure the sealing of the gas collection chamber 1-3g.

[0042] Among them, the above-mentioned and / or the inner wall of one end of the second screw sleeve 1-4 close to the first screw sleeve 1-1 is recessed, which means that, on the basis of the inner wall of one end of the first screw sleeve 1-1 close to the second screw sleeve 1-4 being recessed, the inner wall of one end of the second screw sleeve 1-4 close to the first screw sleeve 1-1 can be recessed to cooperate to form a part of the gas collection chamber 1-3g; it can also be recessed separately from the inner wall of one end of the first screw sleeve 1-1 close to the second screw sleeve 1-4, or other possible implementation methods in which it is recessed separately from the inner wall of one end of the second screw sleeve 1-4 close to the first screw sleeve 1-1.

[0043] Optionally, the feeding section 1-5d is configured as a single-thread screw 1-b to complete the feeding; the compression section is configured as a double-thread screw 1-b to reduce the shear heat of the compression section, thereby reducing the overheating phenomenon of the compression section.

[0044] Optionally, see Figure 1 , Figure 7 and Figure 8 The compression section includes a first compression section 1-5c and a second compression section 1-5b, and the first compression section 1-5c and the second compression section 1-5b are arranged in a double-thread screw 1-b. The screw 1-b includes a feed section 1-5d, a first compression section 1-5c, a second compression section 1-5b and a metering section 1-5a arranged in sequence; along the material conveying direction in the screw extruder, the groove depths of the first compression section 1-5c and the second compression section 1-5b gradually decrease, and the degree of change of the groove depth of the second compression section 1-5b is less than that of the first compression section 1-5c.

[0045] The groove depth of the first compression section 1-5c gradually decreases, and the degree of change in the groove depth is relatively large, so that the solid phase material is fully melted into the liquid phase under compression and shearing; and then after the second compression section 1-5b, the groove depth of the second compression section 1-5b gradually decreases, and the degree of change in the groove depth is relatively small. On the one hand, the solid phase material is further fully melted into liquid, and on the other hand, a relative space is provided for the gas generated after hydrolysis to be stored.

[0046] The above groove depth variation refers to the groove depth variation corresponding to a unit length in the material conveying direction in the screw extruder. The above groove depth variation is relatively large or small.

[0047] Alternatively, if Figure 1 As shown, the screw sleeve 1-a includes an electric contact pressure gauge 1-2, and the measuring end of the electric contact pressure gauge 1-2 is connected to the gas collection chamber 1-3g. The gas collection chamber 1-3g collects the gas generated by the hydrolysis of the material. When the gas reaches a certain volume, the gas pressure generated is reflected in the electric contact pressure gauge 1-2, and the action of the opening and closing valve 1-3 is assisted by the electric contact pressure gauge 1-2.

[0048] Alternatively, if Figure 1 and Figure 4 As shown, the screw sleeve 1-a includes a base 1-c arranged at the outer edge, and the exhaust hole 1-3d is L-shaped and arranged inside the base 1-c. The two ends of the exhaust hole 1-3d are respectively connected to the gas collection chamber 1-3g and the outside atmosphere, and the opening and closing valve 1-3 is installed on the base 1-c. The opening and closing valve 1-3 includes a valve body 1-3b, a packing seal 1-3c, a valve stem 1-3a and a bushing 1-3e. The valve body 1-3b is partially arranged inside the base 1-c, and the other part protrudes from the base 1-c (such as Figure 4As shown, part of the valve body 1-3b is arranged inside the base 1-c, and the other part is exposed from the base 1-c), the valve stem 1-3a is movably arranged in the valve body 1-3b, and is arranged in the base 1-c in the valve body 1-3b part, so that the valve stem 1-3a is also movably arranged in the base 1-c. The packing seal 1-3c is arranged inside the base 1-c and between the base 1-c and the valve stem 1-3a to seal the gap area between the base 1-c and the valve stem 1-3a, so that the gas is discharged from the exhaust hole 1-3d. The end of the valve stem 1-3a is arranged in an arc surface to close or conduct the L-shaped bend of the exhaust hole 1-3d. The bushing 1-3e is arranged at the L-shaped bend of the exhaust hole 1-3d of the base 1-c, and the bushing 1-3e is configured to abut against the end arc surface of the valve stem 1-3a to ensure good sealing when the valve stem 1-3a closes the exhaust hole 1-3d.

[0049] The above-mentioned operation of the position of the valve stem 1-3a can achieve the blocking or conduction of the exhaust hole 1-3d. Further, in combination with the indication of the electric contact pressure gauge 1-2, the gas in the gas collection chamber 1-3g is discharged by opening the exhaust hole 1-3d.

[0050] In one possible implementation, Figure 5 As shown, the on-off valve 1-3 can be set using a manual needle valve 1-3i.

[0051] In one possible implementation, Figure 6 As shown, the on-off valve 1-3 can be set with an electric needle valve 1-3j. At this time, the electric contact pressure gauge 1-2 can be combined to control the electric needle valve 1-3j to open at a fixed value.

[0052] In one possible implementation, Figure 4 As shown, one end of the exhaust hole 1-3d is directly connected to the outside atmosphere.

[0053] In one possible implementation, Figure 5 and Figure 6 As shown, an electric vacuum pump 1-3h can be added to the end of the exhaust hole 1-3d to quickly exhaust the gas by pumping. The electric vacuum pump 1-3h can also be combined with the electric contact pressure gauge 1-2 to control the electric vacuum pump 1-3h to automatically start exhausting at a preset gas pressure.

[0054] Alternatively, if Figure 2 and Figure 3 As shown, along the material conveying direction in the screw extruder, the metering section 1-5a includes a first double-thread structure 1-5a3, a rhombus-shaped separation structure 1-5a2, and a second double-thread structure 1-5a1 in sequence, and the rhombus-shaped separation structure 1-5a2 is an integrally milled rhombus or rhombus-shaped pin processing setting. Figure 3 The upper row of figures in the figure shows the structure of the integrated milled diamond. Figure 3The lower row of figures in the figure shows a diamond-shaped separation structure 1-5a2 processed by diamond-shaped pins. The diamond-shaped separation structure 1-5a2 is set to further promote the mixing and homogenization of the melt.

[0055] Alternatively, if Fig. 9 As shown, the screw 1-b of the first double thread structure 1-5a3 is provided with a plurality of V-shaped grooves 1-5a3-1 to 4 distributed along a spiral ring, and the groove length is set to the entire first double thread structure 1-5a3 to achieve the beneficial effect of reducing the unevenness of the temperature and characteristic viscosity of the melt.

[0056] Alternatively, if Figure 2 and Figure 3 As shown, along the material conveying direction in the screw extruder, the diameter of the diamond-shaped separation structure 1-5a2 gradually decreases, and the diamond arrangement density gradually decreases. Figure 3 The horizontal dotted line in the figure shows that the diameter of the diamond-shaped separation structure 1-5a2 gradually decreases, which ensures that the material does not flow back and gradually reduces the shear heat; Figure 3 The G3-G3, G2-G2, and G1-G1 screenshots in the figure compare the number of diamonds in a circle, showing that the density of the diamond arrangement gradually decreases. The initial large density is conducive to stirring, and the subsequent density reduction is conducive to reducing shear heat. This design has no dead corners, no raw material retention, and no material carbonization, which is conducive to the continuous operation of the spinning process.

[0057] In one embodiment, the length of the feeding section 1-5d of the single thread is set to 9D to 11D, the length of the compression section of the double thread is controlled to 10D to 11D, and the length of the metering section 1-5a is set to 9D to 15D.

[0058] In one embodiment, the length of the first double thread structure 1-5a3 is set to 4D to 10D, the length of the diamond-shaped separated structure 1-5a2 is 3D, and the length of the second double thread structure 1-5a1 is 2D.

[0059] In one embodiment, the aspect ratio of screw 1-b is controlled to be (28-34):1.

[0060] In one embodiment, the temperature of the screw extruder is controlled in a zone of 160° C. to 240° C., and the pressure of the screw extruder after filtration is controlled to be 80-120 kg / cm 2 .

[0061] In one embodiment, the screw edges of the feed section 1-5d are of equal diameter and single pitch, and the screw edges of the second double thread structure 1-5a1 are of equal distance and height, and are fully melted to make the output melt uniform and stabilize the pressure of the melt extrusion outlet, so as to facilitate the subsequent spinning in the mixing and extrusion section to achieve quantitative, constant pressure and constant temperature extrusion from the die head.

[0062] This embodiment also discloses a fiber spinning, stretching and winding machine for polylactic acid industry, including the above-mentioned screw extruder, wherein the extruder head arranged at the head of the screw extruder is equipped with a melt pressure sensor, so that the melt pressure value can be detected to ensure constant pressure of the extruder head.

[0063] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0064] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A screw extruder, characterized in that: The screw extruder comprises a screw sleeve and a screw rod passing through the screw sleeve, wherein the screw rod comprises a feeding section, a compression section and a metering section arranged in sequence, and the screw sleeve comprises: A gas collection chamber is provided on the inner wall at the junction of the compression section and the metering section, the screw sleeve comprises a first screw sleeve and a second screw sleeve which are butted against each other, a sealing gasket is provided between the first screw sleeve and the second screw sleeve, and the first screw sleeve, the sealing gasket and the second screw sleeve are used to enclose the gas collection chamber together with the screw rod; and an exhaust hole in communication with the gas collection chamber; Wherein, the screw sleeve is equipped with an on-off valve for opening and closing the exhaust hole; Along the material conveying direction in the screw extruder, the metering section includes a first double-thread structure, a rhombus-shaped separation structure, and a second double-thread structure in sequence, and the rhombus-shaped separation structure is an integrated milled rhombus or rhombus-shaped pin processing setting; Along the material conveying direction in the screw extruder, the diameter of the diamond-shaped separation structure gradually decreases, and the diamond arrangement density gradually decreases; The screw of the first double-thread structure part is provided with a plurality of V-shaped grooves distributed along the spiral ring; The screw edges of the second double-thread structure are equidistant and equal in height.

2. The screw extruder according to claim 1, characterized in that The screw rod is inserted into the first screw sleeve and the second screw sleeve, the first screw sleeve is provided with the exhaust hole and the opening and closing valve is installed, the inner wall of one end of the first screw sleeve close to the second screw sleeve is recessed, and / or the inner wall of one end of the second screw sleeve close to the first screw sleeve is recessed.

3. The screw extruder according to claim 1, characterized in that The feeding section is arranged in the form of a single-thread screw, and the compression section is arranged in the form of a double-thread screw.

4. The screw extruder according to claim 3, characterized in that The compression section includes a first compression section and a second compression section, the first compression section and the second compression section are arranged in a double-thread screw, and the screw includes the feed section, the first compression section, the second compression section and the metering section arranged in sequence; Along the material conveying direction in the screw extruder, the groove depths of the first compression section and the second compression section gradually decrease, and the groove depth variation degree of the second compression section is smaller than the groove depth variation degree of the first compression section.

5. The screw extruder according to claim 1, characterized in that The screw sleeve comprises an electric contact pressure gauge, and a measuring end of the electric contact pressure gauge is in conduction with the gas collecting chamber.

6. The screw extruder according to any one of claims 1 to 5, characterized in that The screw sleeve includes a base arranged at the outer edge, the exhaust hole is L-shaped and arranged inside the base, the two ends of the exhaust hole are respectively connected to the gas collection chamber and the outside atmosphere, and the on-off valve is installed on the base; The on-off valve comprises: A valve body, wherein the valve body portion is disposed inside the base; A valve stem, the valve stem is movably arranged in the valve body, and the end of the valve stem is arranged in an arc surface to close or open the L-shaped bend of the exhaust hole; A packing seal, wherein the packing seal is disposed inside the base and between the base and the valve stem; A bushing is arranged at the L-shaped bend of the exhaust hole of the base, and the bushing is configured to abut against the end arc surface of the valve stem.

7. The screw extruder according to claim 6, characterized in that The on-off valve includes manual setting or automatic setting; One end of the exhaust hole is directly connected to the outside atmosphere or is connected to the outside atmosphere through a vacuum pump.

8. A polylactic acid industrial fiber spinning, drawing and winding combined machine, characterized in that: A screw extruder according to any one of claims 1 to 7, wherein an extrusion head arranged at the head of the screw extruder is equipped with a melt pressure sensor.

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