Plastic extruding machine adopting carbon dioxide for foaming

Abstract

The utility model provides a plastic extruding machine adopting carbon dioxide for foaming, which belongs to the technical field of plastic extruding machines and comprises a plurality of supporting seats and a machine barrel arranged on the supporting seats, and the supporting seats are mounted on the outer wall of the machine barrel. The spiral blade is arranged on the outer side of the cooling cylinder, the contact area of cooling water and the outer wall of the cooling cylinder is increased, the flowing direction of the cooling water is optimized, more efficient heat exchange is promoted, the actual cooling area of the blade is increased due to the arrangement of the cooling holes and the cooling cavity, and the retention time of the cooling water is prolonged due to the large cooling cavity. The heat in the blades can be absorbed more sufficiently, the number and the thickness of the screw flights on the extrusion screw are controlled, so that the friction area during material mixing is reduced, heat generation is reduced, and paste caused by materials is avoided, the gradually deepened material returning groove is formed, and the heat in the blades can be absorbed more sufficiently by controlling the depth of the material returning groove. Therefore, the reflux time can be effectively controlled, and the technical problem of paste caused by overlong reflux time of materials is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of extruders, in particular to an extruder using carbon dioxide foaming. Background Art

[0002] Existing extruders use fluorine-series foaming agents and chain hydrocarbons. As we all know, Freon is the main cause of the ozone hole. The use of Freon is not conducive to environmental protection, and chain hydrocarbons are flammable, affecting production safety. For this reason, the existing technology uses carbon dioxide to replace Freon as a foaming agent for extruded board production, that is, a mixture of carbon dioxide and alcohols or alkanes is used as a foaming agent.

[0003] To improve the mixing effect of extruders, conventional technologies often incorporate return chutes on the screw fins to allow some material to flow back, thereby increasing mixing time and improving mixing efficiency. However, this often results in excessive backflow and mixing time on the outside of the screw, and excessive friction between the material and the screw, which can easily lead to a paste. Inventing an extruder using carbon dioxide foaming to address these issues has become a pressing issue for those skilled in the art. Utility Model Content

[0004] In order to make up for the above shortcomings, the utility model provides an extruder using carbon dioxide foaming, which aims to solve the common problem that the backflow mixing time of the material outside the extrusion screw is too long, which easily leads to the occurrence of paste.

[0005] The utility model is achieved in this way:

[0006] The utility model provides an extruder using carbon dioxide foaming, comprising a support base and a barrel arranged on the support base, a motor being installed at one end of the support base, the barrel being fixedly connected by a plurality of barrel units through bolts, the barrel at the head end being installed on an outer wall of one side of the support base, an extrusion head being installed on one side of the barrel at the tail end, a water inlet pipe and a water outlet pipe being installed on the side walls of both ends of the barrel respectively, a cooling barrel being installed inside the barrel, and a feeding port being installed on the inner walls of the barrel and the cooling barrel;

[0007] An extrusion screw is installed inside the cooling cylinder, one end of the extrusion screw is rotatably connected to the inner wall of the support seat, and the extrusion screw is composed of a feed end, a melting end and a discharge end in sequence along the material conveying direction. The feed end, the melting end and the discharge end are respectively equipped with a plurality of first screw ribs, second screw ribs and third screw ribs that are rotationally symmetrically distributed along the axis of the extrusion screw. A return groove is provided on the first screw rib, and the depth of the return groove gradually deepens toward the conveying direction. The return groove is opened on multiple screw ribs in a spirally rotating manner, and the spiral direction is opposite to the thread direction of the first screw rib.

[0008] Preferably, both ends of the barrel and both ends of the cooling barrel are sealed and fixed by welding, and the extrusion head is fixed to one end of the barrel by bolts.

[0009] Preferably, a spiral blade is installed on the outer wall of the cooling cylinder, a plurality of cooling holes are opened on the spiral blade, and a cooling cavity is opened on the inner wall of the cooling hole.

[0010] By adopting the above technical solution, during the extrusion process, one end of the water inlet pipe is connected to the cooling water, and the cooled water is discharged and collected at one end of the water outlet pipe. During the cooling process, the spiral blades arranged on the outside of the cooling barrel are used to increase the flow distance of the cooling water inside the barrel. At the same time, the cooling holes increase the contact area between the cooling water and the spiral blades, thereby promoting more efficient heat exchange, improving the cooling effect of the internal extrusion screw, and avoiding the occurrence of paste.

[0011] Preferably, one end of the extrusion screw is fixedly connected to the output end of the motor, the number of first screw ribs on the feed end is six, the number of second screw ribs on the melting end is three, and the number of third screw ribs on the discharge end is six.

[0012] Preferably, the thickness of the first screw flight and the third screw flight is reduced to half of the original thickness, that is, 20 to 30 mm.

[0013] Preferably, the thickness of the second screw fin gradually decreases from close to the extrusion screw end to away from the extrusion screw end, and the end away from the extrusion screw end is sharp.

[0014] By adopting the above technical solution, the number of spiral fins at the feed end and the discharge end is greater than that at the melting end, thereby increasing the loading and unloading speeds at both ends of the extrusion screw. At the same time, the mixing end with fewer spiral fins reduces the conveying rate of the material at this position and increases the mixing time. The return trough set up transports part of the material backward, further increasing the mixing time of the material, thereby improving the mixing effect of the material.

[0015] The beneficial effects of the utility model are:

[0016] The spiral blades arranged on the outside of the cooling cylinder increase the contact area between the cooling water and the outer wall of the cooling cylinder. At the same time, the flow direction of the cooling water is optimized, which increases the contact time between the cooling water and the sleeve and promotes more efficient heat exchange.

[0017] The cooling holes and cooling cavities set on the blades increase the actual cooling area of the blades, providing more area for heat exchange, and the larger cooling cavity provides more space for cooling water, which increases the residence time of cooling water, is conducive to more fully absorbing the heat in the blades and improving the cooling effect;

[0018] The conventional number of first and third screw fins on the extrusion screw is eight, and the conventional number of second screw fins is four. However, the number of first and third screw fins in the present invention is six, and the number of second screw fins is three. Moreover, the thickness of the first and third screw fins is reduced to half of the conventional ones. Under the premise of ensuring the driving force of the extrusion screw, by reducing the number of screw fins and thinning the screw fins, the friction area during material mixing is reduced, thereby reducing heat generation and avoiding technical problems of paste.

[0019] The second fin of the extrusion screw gradually becomes thinner from the bottom to the outside and is sharp on the outside, that is, the cross section of the second fin is inverted V-shaped, which not only reduces the friction area with the material, reduces heat generation, and avoids sticking, but also its outermost sharp shape can quickly and effectively cut and separate the clumped material, making the material mixing more uniform and improving the melting effect;

[0020] The return trough set on the extrusion screw, which gradually deepens in the conveying direction, is deeper than the conventional return trough of the same depth. On the basis of realizing the backflow of materials for re-mixing, it reduces the backflow time. By controlling the depth of the backflow trough, the backflow time can be effectively controlled, solving the technical problem of paste caused by long backflow time of materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 This is a schematic structural diagram of an extruder using carbon dioxide foaming provided by an embodiment of the present utility model;

[0023] Figure 2 This is a cross-sectional view of the local structure of an extruder using carbon dioxide foaming provided by an embodiment of the present utility model;

[0024] Figure 3 This is an extruder using carbon dioxide foaming provided by the embodiment of the utility model. Figure 3 A magnified view of the structure of the middle A area;

[0025] Figure 4 This is a schematic diagram of the structure of an extrusion screw in an extruder using carbon dioxide foaming provided by an embodiment of the present utility model;

[0026] Figure 5This is a schematic diagram of the cooling hole structure on a spiral blade in an extruder using carbon dioxide foaming provided by an embodiment of the present utility model;

[0027] Figure 6 This is a schematic structural diagram of the feed end of an extruder using carbon dioxide foaming provided by an embodiment of the present utility model;

[0028] Figure 7 This is a schematic diagram of the structure of the melting end of an extruder using carbon dioxide foaming provided by an embodiment of the present utility model;

[0029] Figure 8 It is a schematic structural diagram of a discharge end of an extruder using carbon dioxide foaming provided by an embodiment of the present utility model.

[0030] In the figure: 1. Support base; 2. Motor; 3. Cylinder; 4. Water inlet pipe; 5. Water outlet pipe; 6. Cooling cylinder; 7. Spiral blade; 8. Feed port; 9. Extrusion head; 10. Extrusion screw; 11. Feed end; 12. Melting end; 13. First screw wing; 14. Second screw wing; 15. Return trough; 16. Cooling hole; 17. Cooling cavity; 18. Discharge end; 19. Third screw wing. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Example, refer to Figures 1-8 , an extruder using carbon dioxide foaming, comprising a support base 1 and a barrel 3 arranged on the support base 1, a motor 2 is installed at one end of the support base 1, the barrel 3 is fixedly connected by multiple barrel units through bolts, the head barrel 3 is installed on one side outer wall of the support base 1, and an extrusion head 9 is installed on one side of the end barrel 3. The side walls of both ends of the barrel 3 are respectively installed with a water inlet pipe 4 and a water outlet pipe 5, a cooling barrel 6 is installed inside the barrel 3, and a feeding port 8 is installed on the inner walls of the barrel 3 and the cooling barrel 6;

[0033] The extrusion screw 10 is installed inside the cooling cylinder 6. One end of the extrusion screw 10 is rotatably connected to the inner wall of the support seat 1. The extrusion screw 10 is composed of a feed end 11, a melting end 12 and a discharge end 18 in sequence along the material conveying direction. The feed end 11, the melting end 12 and the discharge end 18 are respectively equipped with a plurality of first screw ribs 13, a second screw rib 14 and a third screw rib 19 that are rotationally symmetrically distributed along the axis of the extrusion screw 10. A return groove 15 is provided on the first screw rib 13, and the depth of the return groove 15 gradually deepens toward the conveying direction. The return groove 15 is opened on multiple screw ribs in a spiral rotating manner, and the spiral direction is opposite to the thread direction of the first screw rib 13.

[0034] Furthermore, both ends of the barrel 3 and the cooling barrel 6 are fixed by welding and sealing, the extrusion head 9 is fixed to one end of the barrel 3 by bolts, the outer wall of the cooling barrel 6 is installed with a spiral blade 7, and a plurality of cooling holes 16 are opened on the spiral blade 7, and a cooling cavity 17 is opened on the inner wall of the cooling hole 16.

[0035] It should be noted that: during the extrusion process, one end of the water inlet pipe 4 is connected to cooling water, and the cooling water is filled between the barrel 3 and the cooling barrel 6 to cool the extrusion screw 10 arranged inside the cooling barrel 6. At the same time, one end of the water outlet pipe 5 discharges and collects the cooled water, and during the cooling process, the spiral blades 7 arranged on the outside of the cooling barrel 6 increase the contact area between the cooling water and the outer wall of the cooling barrel 6, allowing the cooling water to flow through more surface area in the same time. At the same time, the cooling water flow rate is reduced through the narrower cooling hole 16, thereby increasing the contact time with the spiral blade 7, and the larger cooling cavity 17 provides more space for the cooling water, increasing the residence time of the cooling water, which is conducive to more sufficient absorption of heat in the spiral blade 7, promoting more efficient heat exchange, improving the cooling effect of the internal extrusion screw 10, and avoiding the occurrence of paste.

[0036] Furthermore; one end of the extrusion screw 10 is fixedly connected to the output end of the motor 2, the number of first screw ribs 13 on the feed end 11 is six, the number of second screw ribs 14 on the melting end 12 is three, and the number of third screw ribs 19 at the discharge end 18 is six. The thickness of the first screw ribs 13 and the third screw ribs 19 is reduced to half of the original thickness, which is 20 to 30 mm. The thickness of the second screw rib 14 gradually decreases from the end close to the extrusion screw 10 to the end away from the extrusion screw 10, and the end away from the extrusion screw 10 is sharp.

[0037] It should be noted that the six first spiral fins 13 provided at the feed end 11 and the six third spiral fins 19 provided at the discharge end 18 are reduced in number compared with the previous eight spiral fins, and the multiple first spiral fins 13 are evenly spaced and have the same spiral direction. The three second spiral fins 14 provided at the melting end 12 are reduced in number compared with the previous four second spiral fins 14, and the multiple second spiral fins 14 are evenly spaced and have the same spiral direction, which has a diversion effect on the mixing, improves the space utilization rate within the spiral fins, and reduces the accumulation and retention of materials between the spiral fins. At the same time, the thickness of the first spiral fins 13 and the third spiral fins 19 are reduced to half of the original thickness, which can reduce the contact surface between the material and the extrusion screw 10, reduce the area of material mixing friction, and reduce the generation of heat, thereby avoiding the material and the extruder. The excessive contact area of the screw 10 causes a paste, and the second screw ridge 14 with a sharp end whose thickness gradually decreases from the end close to the extrusion screw 10 to the end away from the extrusion screw 10 can increase the cutting force on the material and reduce the particle size of the material, so that the material can be fully mixed and evenly mixed, thereby improving the melting effect. The multiple return grooves 15 provided on the screw ridge are arranged in a spiral shape along the screw ridge, and the direction of the spiral is opposite to the spiral direction of the screw ridge, so as to realize the backflow of the material during the conveying process and increase the mixing time of the material. At the same time, the opening depth of the return groove 15 on each screw ridge is different, and its depth gradually deepens along the direction of material conveying. In the process of increasing the mixing time, the amount of backflow material is gradually reduced, thereby avoiding repeated backflow and mixing of the material to cause a paste.

[0038] The working principle of this extruder using carbon dioxide foaming:

[0039] When the material is extruded, the motor 2 is started to drive the extrusion screw 10 to rotate. The material is put into the interior of the cooling cylinder 6 through the feeding port 8 and transported through the extrusion screw 10. During the transportation process, the temperature of the extrusion screw 10 is lowered by cooling water, and part of the material is continuously refluxed through the multiple return troughs 15 set on the screw to increase the mixing time, thereby improving the mixing effect. At the same time, the return troughs 15 set in depth steps gradually reduce the amount of material reflux, thereby avoiding repeated reflux mixing of the material to form a paste, and the material is finally extruded through the extrusion head 9.

[0040] It should be noted that the specific model and specifications of the motor need to be selected and determined based on the actual specifications of the device, and the specific selection calculation method adopts the existing technology in this field, so it will not be described in detail.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An extruder using carbon dioxide foaming, comprising a support base (1) and a barrel (3) arranged on the support base (1), characterized in that: A motor (2) is installed at one end of the support base (1), and the barrel (3) is fixedly connected by a plurality of barrel units through bolts. The barrel (3) at the front end is installed on the outer wall of one side of the support base (1), and an extrusion head (9) is installed on one side of the barrel (3) at the rear end. The side walls at both ends of the barrel (3) are respectively installed with a water inlet pipe (4) and a water outlet pipe (5). A cooling barrel (6) is installed inside the barrel (3), and a feeding port (8) is installed on the inner walls of the barrel (3) and the cooling barrel (6); An extrusion screw (10) is installed inside a cooling cylinder (6), one end of the extrusion screw (10) is rotatably connected to the inner wall of a support seat (1), and the extrusion screw (10) is composed of a feed end (11), a melting end (12) and a discharge end (18) in sequence along the material conveying direction. The feed end (11), the melting end (12) and the discharge end (18) are respectively provided with a plurality of first screw ribs (13), a second screw rib (14) and a third screw rib (19) which are rotationally symmetrically distributed along the axis of the extrusion screw (10), a return trough (15) is provided on the first screw rib (13), the depth of the return trough (15) gradually deepens toward the conveying direction, and the return trough (15) is provided on the plurality of screw ribs in a spirally rotating manner, and the spiral direction is opposite to the thread direction of the first screw rib (13).

2. The extruder using carbon dioxide foaming according to claim 1, characterized in that: The two ends of the barrel (3) and the two ends of the cooling barrel (6) are sealed and fixed by welding, and the extrusion head (9) is fixed to one end of the barrel (3) by bolts.

3. The extruder using carbon dioxide foaming according to claim 2, characterized in that: The outer wall of the cooling cylinder (6) is provided with a spiral blade (7), a plurality of cooling holes (16) are provided on the spiral blade (7), and a cooling cavity (17) is provided on the inner wall of the cooling hole (16).

4. The extruder using carbon dioxide foaming according to claim 1, characterized in that: One end of the extrusion screw (10) is fixedly connected to the output end of the motor (2), the number of first screw fins (13) on the feed end (11) is six, the number of second screw fins (14) on the melting end (12) is three, and the number of third screw fins (19) on the discharge end (18) is six.

5. The extruder using carbon dioxide foaming according to claim 4, characterized in that: The thickness of the first screw flight (13) and the third screw flight (19) is reduced to half of the original thickness, that is, 20 to 30 mm.

6. The extruder using carbon dioxide foaming according to claim 5, characterized in that: The thickness of the second screw fin (14) gradually decreases from the end close to the extrusion screw (10) to the end away from the extrusion screw (10), and the end away from the extrusion screw (10) is in an inverted V-shaped sharp shape.

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