Mixing extrusion screw

Abstract

A mixing extrusion screw comprises a rod body and a screw flight arranged on the rod body, the screw flight comprises a feeding section, a compression section, a secondary compression section, a material blocking section and a mixing section, and transverse strips are arranged on the rod body corresponding to the material blocking section at intervals. The transverse strips are connected with the screw flights of the adjacent material blocking sections so that the screw flights of the material blocking sections and the surfaces of the corresponding rod bodies can form closed spiral grooves with the two ends closed and the middle communicated and open spiral grooves with the middle closed and the two ends open respectively, and the closed spiral grooves and the open spiral grooves are sequentially arranged at intervals. Compared with the prior art, the structure has the advantages that in the material pushing process, material pressure can be quickly relieved through the opening spiral groove, blocking pressure is set through flowing of materials from the opening spiral groove to the closed spiral groove and flowing of the closed spiral groove to the opening spiral groove, the blocking effect of blocking materials is achieved, material backflow is reduced, and the service life of the materials is prolonged. Meanwhile, through material pressure relief and pressurization operation, the material pressure change is increased, and the material mixing effect is improved.

Description

Technical Field

[0001] This utility model relates to the field of extrusion screw technology, and more particularly to a compounding extrusion screw. Background Technology

[0002] A Chinese utility model patent with patent number CN202120678516.7, entitled "An Extrusion Screw for High-Efficiency Granulation of Flat-Double Polyvinyl Chloride Powder," discloses an extrusion screw for high-efficiency granulation of flat-double polyvinyl chloride powder. It includes two parallel screws running in opposite directions. The screws are divided into a feeding section, a compression section, a secondary compression section, a baffle section, a venting section, a plasticizing section, and a mixing section along their length from feed to discharge. In the feeding section, the screw threads have the same pitch and screw groove depth. The meshing gap between the two screws in the compression and secondary compression sections decreases, resulting in a smaller cavity. The meshing gap between the two screws in the baffle section is further reduced. The cavity volume in the venting section increases, while the cavity volume in the plasticizing section is smaller than that in the venting section. The length-to-diameter ratio of the screws is 23:1 to 25:1. This invention features a reasonable structural design, sufficient shear melting, and good product quality, resulting in stable extrusion of PVC strips with high strength, ideal filtration effect, high working efficiency, and low energy consumption. However, the mixing effect of this extrusion screw still has room for improvement; therefore, the structure of the extrusion screw needs further refinement. Summary of the Invention

[0003] The technical problem to be solved by this utility model is to provide a compounding extrusion screw with high compounding efficiency and good compounding effect by providing a compounding structure near the tail of the rod, which is in response to the above-mentioned existing technology.

[0004] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: This compounding extrusion screw includes a rod body and a screw rib disposed on the rod body. The screw rib includes a feeding section, a compression section, a secondary compression section, a baffle section, and a compounding section. The feature is that: horizontal bars are spaced apart on the rod body corresponding to the baffle section. The horizontal bars connect the screw ribs of adjacent baffle sections so that the screw ribs of the baffle section and the corresponding rod body surface respectively form a closed spiral groove with closed ends and a connected middle section, and an open spiral groove with closed middle section and open ends. The closed spiral groove and the open spiral groove are arranged alternately.

[0005] As an improvement, the baffle section can preferably be four spiral ridges. In the four spiral ridges, the first and second spiral ridges are closed at their ends by crossbars to form a closed first spiral melt channel. The second and third spiral ridges are closed at their ends by crossbars to form a second spiral melt channel and a third spiral melt channel with open ends. The third and fourth spiral ridges are closed at their ends by crossbars to form a closed fourth spiral melt channel. The fourth spiral ridge and the first spiral ridge are closed at their ends by crossbars to form a fifth spiral melt channel and a sixth spiral melt channel with open ends.

[0006] Further improvements include, in the four spiral ridges, the height of the latter half of the first and third spiral ridges is preferably greater than the height of the first half of the corresponding first and third spiral ridges, and the height of the latter half of the second and fourth spiral ridges is preferably less than the height of the first half of the corresponding second and fourth spiral ridges. This enhances the material-blocking effect, making it easier for the material to flow in the sequence of open spiral groove, closed spiral groove, and open spiral groove, further improving the barrier effect against backflow and the mixing effect.

[0007] As an improvement, the mixing section can preferably be a disc-shaped structure spaced apart on the rod, with connecting grooves of raised protrusions distributed on the circumferential surface of the disc-shaped structure, dividing the circumferential surface into spaced protrusions.

[0008] In a further improvement, the connecting grooves can preferably all be spiral grooves, and the spiral direction of the spiral grooves is the same as the spiral direction of the open spiral grooves.

[0009] In a further improvement, the helical pitch of the spiral through groove can preferably be the same as the helical pitch of the open spiral groove.

[0010] Further improvements can be made by gradually increasing the spacing between adjacent disc structures along the screw discharge direction.

[0011] As an improvement, the feeding section can preferably be a single-threaded section, the compression section can preferably be a single-threaded section, and the compression section and the feeding section can preferably be smoothly connected end to end.

[0012] Further improvements could be made by including, preferably, a transition cone with a gradually decreasing diameter and a cylindrical body with a constant diameter, in the compression section.

[0013] In a further improvement, the secondary compression section can preferably be a single-ribbed screw, with the screw width of the secondary compression section being greater than that of the compression section. An auxiliary screw is provided on the rod corresponding to the secondary compression section, with the width of the auxiliary screw being less than that of the compression section, and the distance between the auxiliary screw and the screw of the secondary compression section gradually increasing. This structure helps to further improve the mixing effect.

[0014] Compared with the prior art, the advantages of this utility model are as follows: Horizontal bars are spaced apart on the rods corresponding to the material-blocking sections. These horizontal bars connect the helical edges of adjacent material-blocking sections, forming closed spiral grooves (with closed ends and open middle) and open spiral grooves (with closed middle and open ends), respectively, with the helical edges of the material-blocking sections and the corresponding rod surfaces. The closed and open spiral grooves are arranged alternately. This structure allows for rapid material pressure relief through the open spiral grooves during material pushing, and also sets up pressure barriers through the flow of material from the open spiral grooves to the closed spiral grooves and vice versa. This serves as a barrier to block material flow, reducing backflow. Simultaneously, the material pressure variation is increased through the pressure relief and pressurization operation, improving the mixing effect. Attached Figure Description

[0015] Figure 1 This is a front projection view of an embodiment of the present utility model;

[0016] Figure 2 for Figure 1 A three-dimensional image;

[0017] Figure 3 yes Figure 2 A 3D view after rotating at one angle;

[0018] Figure 4 yes Figure 2 Enlarged view of section I;

[0019] Figure 5 yes Figure 3 Enlarged view of Part II. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0021] like Figures 1 to 5 As shown, the compounding extrusion screw of this embodiment includes a rod body 1 and screw ribs disposed on the rod body 1. The screw ribs include a feeding section A, a compression section B, a secondary compression section C, a baffle section D, and a compounding section E. Horizontal bars 15 are spaced apart on the rod body 1 corresponding to the baffle section D. The horizontal bars 15 connect the screw ribs of adjacent baffle sections D, so that the screw ribs of the baffle section D and the corresponding rod body surface respectively form a closed spiral groove 101 with closed ends and open middle and an open spiral groove 102 with closed middle and open ends. The closed spiral groove 101 and the open spiral groove 102 are arranged sequentially at intervals.

[0022] The baffle section is a four-spiral rib. In the four-spiral rib, the first spiral rib 11 and the second spiral rib 12 are closed at their ends by the crossbar 15 to form a closed first spiral melt channel. The second spiral rib 12 and the third spiral rib 13 are closed at their ends by the crossbar 15 to form a second spiral melt channel and a third spiral melt channel with open ends. The third spiral rib 13 and the fourth spiral rib 14 are closed at their ends by the crossbar 15 to form a closed fourth spiral melt channel. The fourth spiral rib 14 and the first spiral rib 11 are closed at their ends by the crossbar 15 to form a fifth spiral melt channel and a sixth spiral melt channel with open ends.

[0023] In the four-screw edge, the height of the latter half of the first screw edge 11 and the third screw edge 13 is greater than the height of the first half of the corresponding first screw edge 1 and the third screw edge 13, and the height of the latter half of the second screw edge 12 and the fourth screw edge 14 is less than the height of the first half of the corresponding second screw edge 12 and the fourth screw edge 14.

[0024] The mixing section E consists of disc-shaped structures spaced apart on the rod body 1. The circumference of each disc-shaped structure is divided into spaced, protruding connecting grooves 16. All connecting grooves 16 are spiral grooves, with the spiral direction matching that of the open spiral grooves 102. The spiral spacing of the spiral grooves is the same as that of the open spiral grooves 102. The spacing between adjacent disc-shaped structures gradually increases along the screw discharge direction.

[0025] The feeding section A and the compression section B are both single-threaded, and the compression section B is smoothly connected to the feeding section A end-to-end. The rod 1 corresponding to the compression section B includes a transition cone with a gradually decreasing diameter and a cylindrical body with a constant diameter. The secondary compression section C is a single-threaded section, and the width of the thread in the secondary compression section C is greater than that in the compression section B. An auxiliary thread 17 is provided on the rod 1 corresponding to the secondary compression section C. The width of the auxiliary thread 17 is smaller than that in the compression section B, and the distance between the auxiliary thread 17 and the thread in the secondary compression section C gradually increases.

Claims

1. A compounding extrusion screw, comprising a rod body (1) and screw ribs disposed on the rod body (1), the screw ribs comprising a feeding section (A), a compression section (B), a secondary compression section (C), a baffle section (D), and a compounding section (E), characterized in that: A horizontal bar (15) is provided at intervals on the rod (1) corresponding to the retaining section (D). The horizontal bar (15) connects the screw edges of the adjacent retaining section (D) so that the screw edges of the retaining section (D) and the surface of the corresponding rod form a closed spiral groove (101) with closed ends and open middle and an open spiral groove (102) with closed middle and open ends. The closed spiral groove (101) and the open spiral groove (102) are arranged at intervals in sequence.

2. The compounding extrusion screw according to claim 1, characterized in that: The baffle section is a four-spiral rib. In the four-spiral rib, the first spiral rib (11) and the second spiral rib (12) are closed at their ends by crossbars (15) to form a closed first spiral melt channel. The second spiral rib (12) and the third spiral rib (13) are closed at their middle by crossbars (15) to form a second spiral melt channel and a third spiral melt channel with open ends. The third spiral rib (13) and the fourth spiral rib (14) are closed at their ends by crossbars (15) to form a closed fourth spiral melt channel. The fourth spiral rib (14) and the first spiral rib (11) are closed at their middle by crossbars (15) to form a fifth spiral melt channel and a sixth spiral melt channel with open ends.

3. The compounding extrusion screw according to claim 2, characterized in that: In the four spiral edges, the spiral height of the latter half of the first spiral edge (11) and the third spiral edge (13) is greater than the spiral height of the first half of the corresponding first spiral edge (11) and the third spiral edge (13), and the spiral height of the latter half of the second spiral edge (12) and the fourth spiral edge (14) is less than the spiral height of the first half of the corresponding second spiral edge (12) and the fourth spiral edge (14).

4. The compounding extrusion screw according to any one of claims 1 to 3, characterized in that: The mixing section (E) is a disc-shaped structure spaced apart on the rod (1), and the circumferential surface of the disc-shaped structure is provided with intermittently distributed protruding connecting grooves (16) that divide the circumferential surface into spaced protrusions.

5. The compounding extrusion screw according to claim 4, characterized in that: All the connecting grooves (16) are spiral grooves, and the spiral direction of the spiral grooves is the same as the spiral direction of the open spiral grooves (102).

6. The compounding extrusion screw according to claim 5, characterized in that: The helical pitch of the spiral through groove is the same as that of the open spiral groove (102).

7. The compounding extrusion screw according to claim 4, characterized in that: The spacing between adjacent disc-shaped structures gradually increases along the screw discharge direction.

8. The compounding extrusion screw according to any one of claims 1 to 3, characterized in that: The feeding section (A) has a single helical edge, the compression section (B) has a single helical edge, and the compression section (B) and the feeding section (A) are smoothly connected end to end.

9. The compounding extrusion screw according to claim 8, characterized in that: The rod (1) corresponding to the compression section (B) includes a transition cone with a gradually decreasing diameter and a cylindrical body with a constant diameter.

10. The compounding extrusion screw according to claim 8, characterized in that: The secondary compression section (C) is a single screw thread. The screw thread width of the secondary compression section (C) is greater than that of the compression section (B). An auxiliary screw thread (17) is provided on the rod (1) corresponding to the secondary compression section (C). The screw thread width of the auxiliary screw thread (17) is less than that of the compression section (B). The distance between the auxiliary screw thread (17) and the screw thread of the secondary compression section (C) gradually increases.

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