Extruder cylinder and extruder

Abstract

The invention discloses an extruder barrel and an extruder, belongs to the technical field of high polymer material processing equipment, and aims to solve the problem that ultra-high molecular weight polyethylene is difficult to process and form in the prior art. The extruder barrel comprises a barrel body, and a plurality of grooves (13) are formed in the inner wall surface (4) of the barrel body; the section of the groove (13) comprises a first arc section (5) and a second arc section (6) which are connected in sequence, and the diameter of a circle where the first arc section (5) is located is smaller than that of a circle where the second arc section (6) is located. The extruder barrel can prevent UHMWPE from slipping in the transportation process, reduces mold back pressure caused by materials in the barrel, realizes continuous and stable forward conveying of the materials in a single-screw extruder, and is beneficial to rapid extrusion, processing and forming of the UHMWPE on the basis of keeping original excellent performance of the materials.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material processing equipment, in particular to an extruder barrel for ultra-high molecular weight polyethylene, and also to an extruder. Background Art

[0002] Ultra High Molecular Weight Polyethylene (UHMWPE) is a linear thermoplastic polymer with a number average molecular weight (Mn) greater than 1 million. Since it was successfully developed by United Chemical Company of the United States using ZN catalyst in 1957, UHMWPE has a variety of unique properties due to its ultra-long regular molecular chain structure. Compared with many polymer materials, UHMWPE has a small friction coefficient and low friction loss, so it has excellent wear resistance. Due to its excellent self-lubrication, anti-fouling and biocompatibility, it is often used in wear-resistant devices such as artificial joints. UHMWPE has good crystallization properties, and its crystallinity is generally 65%-85%, and its ultra-long molecular chains form a highly entangled state in the amorphous region. Therefore, UHMWPE has excellent mechanical strength, such as impact resistance, extrusion resistance, bending resistance, stress cracking resistance, etc., so it is often used in various force-bearing structural devices. UHMWPE also has unique cold resistance and frost resistance, and can show good mechanical properties under extremely cold conditions. At the same time, UHMWPE has poor thermal conductivity, so it can also be used in deep cold insulation materials, thermal insulation materials, etc. In addition, UHMWPE also has strong corrosion resistance to almost all chemicals and is specially used in special environments.

[0003] While UHMWPE has many excellent properties, it also has serious processing and molding problems. The ultra-long molecular chain structure of UHMWPE is simple, and it is easy to form a highly cross-entangled state within and between molecular chains. This state still exists in large quantities when heated above the melting point, resulting in the molecular chain segments being restricted to thermal motion only in local areas, and it is difficult for the molecular chain segments to have coordinated motion, resulting in the difficulty of moving the center of gravity of the molecular chain. The macroscopic manifestation is that the melt viscosity of UHMWPE is extremely high, and its melt viscosity is as high as 108Pa·s. The melt has almost no fluidity and presents a highly elastic state similar to hard rubber. This state brings great difficulties and challenges to the processing and application of UHMWPE. The conventional processing and molding method of UHMWPE is compression molding, but compression molding cannot manufacture continuous profiles such as pipes and bars, as well as large-area molded parts such as plates and sheets. Compression molding is highly dependent on manual operation, making it difficult to achieve automated continuous production and processing. Compression molding has a long production cycle, low output, and low production efficiency. The properties of UHMWPE itself determine that general extrusion molding is difficult to achieve fast and good molding processing. The decomposition temperature of UHMWPE is low. The method of increasing the temperature to increase fluidity has little effect. Instead, it causes the macromolecules to degrade, the molecular weight to decrease, and many of its excellent properties to be lost. UHMWPE materials expand during the extrusion process, the back pressure increases, and extrusion is difficult. The critical shear rate value of UHMWPE is very low. Increasing the shear rate to reduce viscosity is prone to melt fracture and molecular chain breakage. UHMWPE also has an ultra-low friction coefficient, and it slips on the barrel wall or screw, making material transportation difficult. These situations have greatly limited the mass molding and wide-range application of ultra-high molecular weight polyethylene.

[0004] Improvements in the molding and processing of UHMWPE have always been a hot topic of exploration in the materials industry. One improvement scheme based on the structure of UHMWPE is to use special catalysts and special synthesis methods to prepare UHMWPE in a low entanglement state. The disadvantage is that this scheme requires the development of new methods and processes, which is costly, complex conditions, low yield, and difficult to achieve industrial production. Another scheme is to add flow aids during the processing process, by adding polymers such as low molecular weight polyethylene, polypropylene, paraffin, or inorganic fillers such as talcum powder and silica to reduce the melt viscosity and fluidity of UHMWPE during the processing. Although this scheme can significantly improve the processing efficiency of UHMWPE extrusion molding, its disadvantages are also very obvious. The modified additives will affect the performance of the UHMWPE material itself, greatly reducing its excellent and unique properties and affecting the performance of the product. Another scheme is to process UHMWPE using a solution method such as gel spinning. Summary of the invention

[0005] In order to solve the problem of difficulty in processing and molding ultra-high molecular weight polyethylene in the prior art, the present invention provides an extruder barrel and an extruder, wherein the extruder barrel can prevent UHMWPE from slipping during transportation, reduce the mold back pressure caused by the material in the barrel, ensure that the material is gradually compacted during the forward movement, and realize continuous and stable forward transportation of the material in the single-screw extruder, which is conducive to the rapid extrusion processing and molding of UHMWPE while maintaining the original excellent properties of the material.

[0006] The technical solution adopted by the embodiment of the present invention to solve the technical problem is:

[0007] An extruder barrel comprises a barrel, wherein the inner wall surface of the barrel comprises a plurality of grooves, the plurality of grooves are arranged at intervals along the circumference of the barrel, the grooves extend along the axial direction of the barrel, the cross section of the grooves comprises a first circular arc segment and a second circular arc segment connected in sequence, and the diameter of the circle where the first circular arc segment is located is smaller than the diameter of the circle where the second circular arc segment is located.

[0008] An extruder comprises the above-mentioned extruder barrel, wherein a screw is arranged in the extruder barrel.

[0009] The beneficial effects of the embodiments of the present invention are as follows: UHMWPE adheres to each other and forms blocks in the grooves of the extruder barrel to prevent the material from slipping, the material is quickly depressurized at the grooves in the barrel, the material is gradually compacted during forward transportation, and the molecular weight reduction caused by shear chain breaking during transportation is prevented, thereby achieving continuous and stable transportation of UHMWPE in a single-screw extruder, improving the processing efficiency of UHMWPE extrusion molding, and ensuring the quality of UHMWPE extrusion molded products. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0011] Figure 1 It is a left side schematic diagram of the extruder barrel of the present invention in Example 1.

[0012] Figure 2 It is a schematic diagram of the right side view of the extruder barrel of the present invention in Example 1.

[0013] Figure 3 Schematic diagram of a top view of the extruder barrel of the present invention in Example 1.

[0014] Figure 4 Schematic cross-sectional view of the extruder barrel of the present invention in Example 1.

[0015] Figure 53D is a schematic three-dimensional diagram of the extruder barrel of the present invention in Example 1.

[0016] Figure 6 Schematic diagram of the relationship between the groove and the inner wall surface in the cross section of the extruder barrel of the present invention in Example 1.

[0017] Figure 7 yes Figure 6 Schematic diagram of a groove section and an inner wall section connected in the figure.

[0018] Figure 8 It is a left side schematic diagram of the extruder barrel of the present invention in Example 2.

[0019] Fig. 9 It is a schematic diagram of the right side view of the extruder barrel of the present invention in Example 2.

[0020] Fig.10 Schematic top view of the extruder barrel of the present invention in Example 2.

[0021] Fig.11 Schematic cross-sectional view of the extruder barrel of the present invention in Example 2.

[0022] Fig.12 It is a three-dimensional schematic diagram of the extruder barrel of the present invention in Example 2.

[0023] The following are the descriptions of the reference numerals:

[0024] 1. Flange; 2. Bolts; 3. Feeding section; 4. Inner wall surface; 5. First arc section; 6. Second arc section; 7. Rotation direction of the screw; 8. Screw hole of homogenizing section; 9. Screw hole of die head; 10. Die head; 11. Compression section; 12. Homogenizing section; 13. Groove;

[0025] 41, first tangent point; 51, second tangent point; 61, third tangent point. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] Example 1

[0028] like Figures 1 to 7As shown, an extruder barrel described in an embodiment of the present invention includes a barrel, an inner wall surface 4 of the barrel contains a plurality of grooves 13, the plurality of grooves 13 are evenly spaced along the circumference of the barrel, the grooves 13 extend along the axial direction of the barrel, the cross-section of the grooves 13 contains a first circular arc segment 5 and a second circular arc segment 6 connected in sequence along the circumference of the barrel, and the diameter of the circle where the first circular arc segment 5 is located is smaller than the diameter of the circle where the second circular arc segment 6 is located.

[0029] The cross-sections of the inner wall and the outer wall of the extruder barrel are both roughly circular. The extruder barrel can prevent UHMWPE from slipping during transportation, reduce the mold back pressure caused by the material in the barrel, ensure that the material is gradually compacted during the forward movement, and realize continuous and stable forward transportation of the material in the single-screw extruder, which is conducive to the rapid extrusion processing and molding of UHMWPE while maintaining the original excellent properties of the material.

[0030] like Figure 6 and Figure 7 As shown, in the cross-sectional structure of the extruder barrel, the cross section of the inner wall surface 4 is circular, the radius of the circle where the first arc segment 5 is located and the circle where the inner wall surface 4 is located are tangent at the first tangent point 41, the circle where the first arc segment 5 is located and the circle where the second arc segment 6 is located are inscribed at the second tangent point 51, the circle where the second arc segment 6 is located and the circle where the inner wall surface 4 is located are inscribed at the third tangent point 61, the first tangent point 41 is located on the circle where the inner wall surface 4 is located, and along the circumference of the barrel, the first tangent point 41, the second tangent point 51 and the third tangent point 61 are arranged in sequence. The cross section of the extruder barrel is perpendicular to the axis of the extruder barrel.

[0031] like Figure 6 and Figure 7 As shown, in the cross section of a groove 13, one end of the first arc segment 5 is located at the first tangent point 41, the other end of the first arc segment 5 is located at the second tangent point 51, one end of the second arc segment 6 is located at the second tangent point 51, and the other end of the second arc segment 6 is located at the third tangent point 61. The two ends of the inner wall surface 4 are respectively located at the first tangent point 41 and the third tangent point 61 of two adjacent grooves 13.

[0032] The axis of the extruder barrel coincides with the axis of the inner wall surface 4, the diameter of the circle where the second arc segment 6 is located is 1.5 to 3 times the diameter of the circle where the inner wall surface 4 is located, and the center angle corresponding to the groove 13 is equal to the center angle corresponding to the inner wall surface 4 between two adjacent grooves 13. The number of grooves 13 can be 2 to 9, preferably 3, 4, 6 or 8, and the center angle corresponding to the groove 13 can be 20° to 90°. For example, when the number of grooves 13 is 4, the center angle corresponding to the groove 13 is 45°, and the center angle corresponding to the inner wall surface 4 between two adjacent grooves 13 is also 45°.

[0033] like Figures 1 to 5 As shown, the ratio of the diameter of the outer wall surface of the cylinder to the diameter of the inner wall surface 4 of the cylinder is 1.5-3, the ratio of the axial length of the cylinder to the diameter of the inner wall surface 4 of the cylinder is 20-30, and the axial length of the cylinder can be 600mm-6000mm.

[0034] Along the direction from the inlet end of the cylinder to the outlet end of the cylinder, the cylinder comprises a feed section 3, a compression section 11 and a homogenization section 12 connected in sequence. The length of the feed section 3 is 50%-60% of the total length of the cylinder, the length of the compression section 11 is 10%-30% of the total length of the cylinder, and the length of the homogenization section 12 is 20%-30% of the total length of the cylinder.

[0035] The feed section 3 and the compression section 11 are connected and fixed by flange 1 and bolts 2, and the compression section 11 and the homogenization section 12 are also connected and fixed by flange 1 and bolts 2. The ratio of the outer diameter of flange 1 to the diameter of the outer wall of the cylinder is 1.2-1.5. The ratio of the width of flange 1 to the length of the cylinder is 0.01-0.02. 8 screw holes are evenly distributed on flange 1, and the ratio of the screw hole diameter to the diameter of the outer wall of the cylinder is 0.1-0.3.

[0036] like Figures 1 to 5 As shown, the extruder barrel also includes a die head 10, which is located outside the outlet end of the barrel. The die head 10 is also connected and fixed to the homogenizing section 12 by a flange 1 and a bolt 2. The inner wall surface 4 of the die head 10 also contains a plurality of grooves 13. That is, the groove 13 runs through the entire extruder barrel in the axial direction. Along the axial direction of the barrel, the groove 13 runs through the entire inner wall surface 4 of the barrel and the inner wall surface 4 of the die head 10. The depth of the groove 13 gradually decreases from the inlet end of the barrel to the outlet end of the barrel. The depth of the groove 13 at the outlet end of the die head 10 is 25%-50% of the depth of the groove 13 at the inlet end of the barrel (i.e., the inlet end of the feed section 3).

[0037] The diameter of the inner wall surface 4 of the cylinder is the same as the diameter of the inner wall surface 4 of the die 10, and the ratio of the length of the die 10 to the length of the cylinder is 0.1-0.2. The outlet end of the homogenizing section 12 is provided with 8 homogenizing section screw holes 8, and the outlet end of the die 10 is provided with 8 die screw holes 9, and the homogenizing section screw holes 8 and the die screw holes 9 are both used to fix the die. The ratio of the depth of the homogenizing section screw hole 8 to the length of the die 10 is 0.2-0.5, and the ratio of the depth of the die screw hole 9 to the length of the die 10 is 0.2-0.5.

[0038] An extruder is introduced below, which includes the extruder barrel mentioned above, and a screw is arranged in the extruder barrel.

[0039] The extruder is a single screw extruder, that is, only one screw is arranged in the barrel of the extruder. According to the standards of my country's extruders, the diameter of the screw is generally 30 mm, 45 mm, 65 mm, 90 mm, 120 mm, 150 mm or 200 mm. The diameter of the inner wall surface 4 of the barrel is 2 mm-20 mm larger than the diameter of the screw.

[0040] The axis of the extruder barrel, the axis of the inner wall 4 of the barrel, the axis of the outer wall of the barrel and the axis of the inner wall of the head 10 all coincide. Figure 1 As shown, during operation, the rotation direction 7 of the screw is from the first circular arc segment 5 to the second circular arc segment 6 along the circumference of the barrel.

[0041] The working process of the extruder barrel is introduced below.

[0042] 1. A die is installed outside the outlet end of the die head 10. The die can be a die for processing pipes, bars or plates.

[0043] 2. UHMWPE is heated, melted and plasticized in the extruder barrel. UHMWPE passes through the feeding section 3, the compression section 11, the homogenization section 12 and the die head 10 in sequence and is extruded from the die to produce corresponding pipes, rods or plates.

[0044] Through experimental testing, it was found that the UHMWPE was continuously and stably conveyed in the extruder barrel and the extruder, the processing efficiency of UHMWPE extrusion molding was improved, the extruded products had no obvious defects and the quality met expectations.

[0045] Example 2

[0046] This embodiment is a variation of the embodiment 1. The main difference between this embodiment and the embodiment 1 is that the cross section of the outer wall of the extruder barrel is rectangular, especially square. Figures 8 to 12 The remaining technical features of this embodiment are the same as those in Embodiment 1. The specific parameters can be obtained by technicians in this field according to actual needs or limited experiments. In order to save space, this embodiment will not be described in detail.

[0047] The above is only a specific embodiment of the present invention, and cannot be used to limit the scope of the invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the scope of protection of the patent of the present invention, should still fall within the scope of this patent. In addition, the technical features of the present invention can be freely combined with each other, with technical features and technical solutions, with technical solutions and embodiments.

Claims

1. An extruder barrel, characterized in that, The extruder barrel comprises a barrel, wherein the inner wall surface (4) of the barrel comprises a plurality of grooves (13), wherein the plurality of grooves (13) are arranged at intervals along the circumference of the barrel, wherein the grooves (13) extend along the axial direction of the barrel, wherein the cross section of the grooves (13) comprises a first circular arc segment (5) and a second circular arc segment (6) connected in sequence, wherein the diameter of the circle where the first circular arc segment (5) is located is smaller than the diameter of the circle where the second circular arc segment (6) is located.

2. The extruder barrel according to claim 1, characterized in that The cross section of the inner wall surface (4) is circular, the radius of the circle where the first arc segment (5) is located and the radius of the circle where the inner wall surface (4) is located are tangent at a first tangent point (41), the circle where the first arc segment (5) is located and the circle where the second arc segment (6) is located are inscribed at a second tangent point (51), the circle where the second arc segment (6) is located and the circle where the inner wall surface (4) is located are inscribed at a third tangent point (61), the first tangent point (41) is located on the circle where the inner wall surface (4) is located, and along the circumference of the cylinder, the first tangent point (41), the second tangent point (51) and the third tangent point (61) are arranged in sequence.

3. The extruder barrel according to claim 2, characterized in that One end of the first arc segment (5) is located at the first tangent point (41), the other end of the first arc segment (5) is located at the second tangent point (51), one end of the second arc segment (6) is located at the second tangent point (51), and the other end of the second arc segment (6) is located at the third tangent point (61).

4. The extruder barrel according to claim 2, characterized in that The diameter of the circle where the second arc segment (6) is located is 1.5 to 3 times the diameter of the circle where the inner wall surface (4) is located, and the central angle corresponding to the groove (13) is 20° to 90°.

5. The extruder barrel according to claim 2, characterized in that The center angle corresponding to the groove (13) is equal to the center angle corresponding to the inner wall surface (4) between two adjacent grooves (13).

6. The extruder barrel according to claim 1, characterized in that The number of the grooves (13) is 2 to 9, and the depth of the grooves (13) gradually decreases from the inlet end of the cylinder to the outlet end of the cylinder.

7. The extruder barrel according to claim 1, characterized in that The ratio of the length of the cylinder to the diameter of the inner wall surface (4) of the cylinder is 20-30, and the length of the cylinder is 600mm-6000mm.

8. The extruder barrel according to claim 1, characterized in that The cross-section of the outer wall of the cylinder is circular or rectangular. Along the direction from the inlet end of the cylinder to the outlet end of the cylinder, the cylinder contains a feeding section (3), a compression section (11) and a homogenizing section (12) connected in sequence.

9. The extruder barrel according to claim 8, characterized in that The length of the feeding section (3) is 50%-60% of the length of the cylinder, the length of the compression section (11) is 10%-30% of the length of the cylinder, and the length of the homogenization section (12) is 20%-30% of the length of the cylinder.

10. The extruder barrel according to claim 1, characterized in that The extruder barrel further comprises a die head (10), which is located outside the outlet end of the barrel, and the inner wall surface (4) of the die head (10) also comprises a plurality of grooves (13).

11. An extruder, characterized in that: The extruder comprises the extruder barrel according to claim 1, wherein a screw is arranged in the extruder barrel.

12. The extruder according to claim 11, characterized in that The diameter of the inner wall surface (4) is 2 mm to 20 mm larger than the diameter of the screw.

13. The extruder according to claim 11, characterized in that The rotation direction (7) of the screw is from the first circular arc segment (5) to the second circular arc segment (6) along the circumference of the barrel.

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