A high efficiency plasticizing screw for polyolefin pipe

Abstract

This utility model discloses a high-efficiency plasticizing screw for polyolefin pipes, comprising a mixing section and a screw body. The screw body has multiple equally spaced barrier rings. Each barrier ring has a first channel and a second channel distributed radially. On the same barrier ring, a first channel is located inside a second channel, and the first and second channels are staggered. The axis of the first channel forms a first angle with the axis of the screw body, and the axis of the second channel forms a second angle with the axis of the screw body. Both the first and second angles are acute angles, and their openings are opposite. This screw has a simple structure and ingenious design, allowing for more complete plasticization of the polyolefin raw material inside the screw barrel, thus avoiding problems such as insufficient plasticization during polyolefin pipe extrusion and eliminating quality hazards such as crystal point bulging on the inner wall of the pipe.

Description

Technical Field

[0001] This utility model relates to the field of polyolefin pipe production and processing technology, specifically to a high-efficiency plasticizing screw for polyolefin pipes. Background Technology

[0002] In the production of polyolefin pipes, adequate plasticization of raw materials is a crucial step in ensuring product quality. However, in current polyolefin pipe production, some raw materials suffer from insufficient plasticization. The specific reasons are as follows:

[0003] 1. Differences in raw material characteristics: Polyolefin raw materials are diverse, including virgin resins, recycled materials, fillers, and blends (such as polyethylene / polypropylene alloys). These raw materials have different melting points, resulting in poor compatibility between components during blending. For example, recycled materials have unstable properties, fillers are prone to agglomeration, and the compatibility of different polymers in blends is difficult to guarantee.

[0004] 2. Limitations of existing screw design: During shearing and mixing in a traditional screw press barrel, the shearing and plasticizing time and force are insufficient due to the limitations of the screw structure (ordinary pin screw). This results in some raw materials failing to melt completely, forming unplasticized crystal points and bulges on the inner wall of the pipe, severely affecting the appearance quality and mechanical properties of the pipe.

[0005] For the reasons mentioned above, unplasticized crystal points and bulges appear on the inner wall of the pipe, which not only affects the appearance quality of the pipe but may also lead to internal defects such as unmelted grains and bubbles, reducing the pipe's pressure resistance and strength. These problems not only increase production costs but may also cause safety issues during subsequent use. Summary of the Invention

[0006] To address the problems existing in the prior art, this utility model provides a high-efficiency plasticizing screw for polyolefin pipes. The screw has a simple structure and ingenious design, which allows the polyolefin raw material to be more fully plasticized inside the screw barrel. It increases the shearing and plasticizing time and force of the screw on the polyolefin raw material, thereby avoiding problems such as insufficient plasticization of polyolefin pipes during extrusion and eliminating quality hazards such as crystal point bulging on the inner wall of the pipe.

[0007] The technical solution adopted to achieve the above-mentioned objectives of this utility model is as follows:

[0008] A high-efficiency plasticizing screw for polyolefin pipes includes a mixing section, which includes a screw body. The screw body has multiple equally spaced barrier rings. Each barrier ring has a first channel and a second channel distributed radially. On the same barrier ring, multiple first channels in the first channel are evenly distributed circumferentially along the barrier ring, and multiple second channels in the second channel are evenly distributed circumferentially along the barrier ring. The first channel is located inside the second channel, and the first and second channels are staggered. The axis of the first channel forms a first angle with the axis of the screw body, and both the first and second angles are acute. The axis of the second channel forms a second angle with the axis of the screw body, and the openings of the first and second angles are opposite.

[0009] The first included angle is between 20° and 30° (inclusive), and the second included angle is between 20° and 30° (inclusive).

[0010] The first included angle and the second included angle are the same.

[0011] On the two adjacent blocking rings, the angle formed by the axis of the first channel of one blocking ring and the axis of the screw body is equal to the angle formed by the axis of the first channel of the other blocking ring and the axis of the screw body, and the openings are opposite.

[0012] The blocking ring is thicker in the middle and thinner at both ends, and the two sides of the blocking ring are truncated cone-shaped.

[0013] The diameters of the first and second channels are both 9-12% of the diameter of the first screw body.

[0014] The width of the barrier ring is 25-30% of the diameter of the first screw body.

[0015] The first and second channels have the same diameter.

[0016] Compared with the prior art, the beneficial effects and advantages of this utility model are as follows:

[0017] 1. The mixing section of the screw is equipped with multiple perforated disc structures of barrier discs. The barrier discs block the molten polyolefin raw material. The polyolefin raw material can only flow into the next stage from the first and second channels. In the next stage, it will still be blocked by the barrier discs. This repeated blocking can effectively block the polyolefin raw material that is not fully plasticized, and can also increase the shear plasticization time of the polyolefin raw material.

[0018] 2. The mixing section of the screw is provided with first and second channels facing opposite directions on each barrier disk, which makes the path of polyolefin raw material inside the screw longer and further increases the plasticizing time. At the same time, since the polyolefin raw material can only be extruded and sheared through the first and second channels, the shearing plasticizing force is greatly increased.

[0019] 3. The mixing section of the screw, through the barrier disk with a special structure, greatly increases the shearing and plasticizing force and time of the polyolefin raw material, so that the polyolefin raw material is more fully plasticized inside the screw barrel, thereby avoiding problems such as insufficient plasticization of polyolefin pipe extrusion and eliminating quality hazards such as crystal point bulging on the inner wall of the pipe. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a high-efficiency plasticizing screw used for polyolefin pipes.

[0021] Figure 2 for Figure 1 The main view and partial sectional view.

[0022] Figure 3 for Figure 2 A cross-sectional view along the CC direction.

[0023] Among them, 1-screw body, 2-barrier ring, 3-first channel, 4-second channel. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings.

[0025] The high-efficiency plasticizing screw for polyolefin pipes provided in this embodiment has the following structure: Figure 1-2 As shown, the system includes a mixing section, which includes a screw body 1. In this embodiment, the screw body 1 has a diameter of 45 mm. The screw body 1 is provided with multiple equally spaced barrier rings 2. In this embodiment, there are six barrier rings 2.

[0026] like Figure 2 and Figure 3 As shown, the blocking ring 2 is thicker in the middle and thinner at both ends. The two sides of the blocking ring 2 are frustum-shaped. The height of the middle part of the blocking ring 2 is 3-4 times the height of the frustum-shaped structure on the sides. The minimum inner diameter of the two sides of the blocking ring 2 is the same as the diameter of the screw body 1. In this embodiment, the ring width of the middle part of the blocking ring 2 is 20mm.

[0027] For the same barrier ring 2, a first channel 3 and a second channel 4 are respectively provided on the barrier ring 2 along its radial direction. Multiple first channels 3 in the first channel 3 are evenly distributed around the circumference of the barrier ring 1, and multiple second channels 4 in the second channel 4 are evenly distributed around the circumference of the barrier ring 1. The first channel 3 is located inside the second channel 4, and the first channels 3 and second channels 4 are staggered. The diameters of the first channels 3 and second channels 4 are the same. In this embodiment, the diameters of both the first channel 3 and the second channel 4 are 8 mm.

[0028] For the same blocking ring 2, the axis of the first channel 3 forms a first angle with the axis of the screw body 1, and the axis of the second channel 4 forms a second angle with the axis of the screw body 1. The openings of the first and second angles are opposite. Both the first and second angles are acute angles, and the angles of the first and second angles are the same, with both angles between 20-30°. In this embodiment, both the first and second angles are 25°.

[0029] For two adjacent barrier rings 2, the angle formed by the axis of the first channel 3 of one barrier ring 2 and the axis of the screw body 1 is equal to the angle formed by the axis of the first channel 3 of the other barrier ring 2 and the axis of the screw body 1, and their openings are opposite. The two adjacent barrier rings 2 use channels facing opposite directions, which makes the path of the polyolefin raw material inside the screw longer and the shear plasticizing time longer.

[0030] Polyolefin raw materials enter the barrel from the feeding section. After being sheared and plasticized by the screw plasticizing section, they become molten and then flow into the mixing section. In this stage, the molten polyolefin raw material is blocked by the first blocking disc 2 and enters the next space from the first blocking disc 2 through the opposite first channel 3 and second channel 4. It is then blocked by the next blocking disc 2. After being plasticized through the blocking channels 6 times, it is extruded through the die head.

[0031] This technology has a wide range of applications, including pressure-resistant pipes (such as gas pipes and water supply pipes), high-plasticity screws to avoid fusion lines caused by insufficient melting, and filled / modified polyolefins, such as calcium carbonate-filled PE. The mixing section design prevents filler agglomeration. It can also be used in large-diameter thick-walled pipes, multi-layer composite pipes, and recycled material processing. For PE pipes containing 30% to 50% recycled material, the design of the reinforced mixing section can improve compatibility.

[0032] First, this screw can improve plasticizing efficiency and production capacity, increase extrusion output, and reduce production energy consumption and costs. Second, this screw can also improve melt quality and pipe performance, homogenize melt temperature, reduce internal stress in the pipe, and prevent stress cracking during subsequent use. Third, this screw can reduce defects, eliminate unmelted grains and bubbles, and increase the burst pressure of the pipe by 10% to 15% (e.g., from 4.5 MPa to 5.2 MPa for PE100 gas pipes).

Claims

1. A high efficiency plasticizing screw for polyolefin pipestock, characterized by: The system includes a mixing section, which comprises a screw body. The screw body has multiple equally spaced barrier rings. Each barrier ring has a first channel and a second channel arranged radially. On the same barrier ring, multiple first channels in the first channel are evenly distributed circumferentially along the barrier ring, and multiple second channels in the second channel are evenly distributed circumferentially along the barrier ring. The first channel is located inside the second channel. The first and second channels are staggered. The axis of the first channel forms a first angle with the axis of the screw body, and the axis of the second channel forms a second angle with the axis of the screw body. Both the first and second angles are acute angles, and their openings are opposite.

2. The high efficiency plasticizing screw for polyolefin pipe materials according to claim 1, characterized by: The first included angle is between 20-30°, and the second included angle is between 20-30°.

3. The high efficiency plasticizing screw for polyolefin pipe materials according to claim 2, characterized in that: The first included angle and the second included angle are the same.

4. The high efficiency plasticizing screw for polyolefin pipe materials according to claim 1, characterized by: On two adjacent blocking rings, the angle formed by the first channel axis of one blocking ring and the axis of the screw body is equal to the angle formed by the first channel axis of the other blocking ring and the axis of the screw body, and their openings are opposite.

5. The high efficiency plasticizing screw for polyolefin pipe materials according to claim 1, characterized in that: The blocking ring is thicker in the middle and thinner at both ends, and the two sides of the blocking ring are truncated cone-shaped.

6. The high efficiency plasticizing screw for polyolefin pipe materials according to claim 1, characterized in that: The diameters of the first and second channels are both 9-12% of the diameter of the first screw body.

7. The high efficiency plasticizing screw for polyolefin pipe materials according to claim 1, characterized in that: The width of the barrier ring is 25-30% of the diameter of the first screw body.

8. The high efficiency plasticizing screw for polyolefin pipe materials according to claim 1, characterized in that: The first and second channels have the same diameter.

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