A large-diameter thick-wall plastic pipe inner wall cooling device

Abstract

This invention discloses an inner wall cooling device for large-diameter, thick-walled plastic pipes, belonging to the field of plastic pipe forming technology. It includes: an extrusion die for extruding molten pipe blanks; and an internal cooling device located at the extrusion end of the extrusion die and connected to it. The internal cooling device is arranged circumferentially along the inner surface of the molten pipe blank and exchanges heat with the inner surface of the molten pipe blank through a cooling medium. Preferably, the internal cooling device employs a water-circulating internal cooling sizing sleeve and a spray-type internal cooling structure. After the molten pipe blank is extruded, the water-circulating internal cooling sizing sleeve performs primary cooling of the inner wall. The initially cooled inner wall undergoes secondary cooling through the spray-type internal cooling structure. Because the primary cooling pre-cools the originally high-temperature inner wall of the molten pipe blank, the secondary cooling prevents rapid shrinkage of the inner wall during secondary cooling, reducing pipe wall thickness deviation caused by sag and ensuring product quality.

Description

Technical Field

[0001] This invention belongs to the field of plastic pipe forming technology, specifically relating to a cooling device for the inner wall of large-diameter thick-walled plastic pipes. Background Technology

[0002] During the extrusion molding process of plastic pipes from the mold, the pipes are at a high temperature and are in a molten state. They need to be cooled to give them sufficient rigidity. However, the current cooling method only cools the outer wall of the molten pipe blank. This method is only suitable for cooling thin-walled plastic pipes. Once the pipe has a large wall thickness, the low temperature of the outer wall cannot be quickly transferred to the inner wall, causing the inner wall to sag due to the inability to cool in time. This results in uneven pipe wall thickness and easy deformation of the pipe. Summary of the Invention

[0003] This invention addresses the aforementioned problems in the existing technology by proposing a cooling device for the inner wall of large-diameter, thick-walled plastic pipes.

[0004] This invention can be achieved through the following technical solutions:

[0005] A cooling device for the inner wall of a large-diameter, thick-walled plastic pipe, comprising:

[0006] Extrusion die, used to extrude molten tubular material;

[0007] An internal cooling device is located at the extrusion end of the extrusion die and connected to the extrusion die. The internal cooling device is arranged circumferentially along the inner surface of the molten tubular billet and exchanges heat with the inner surface of the molten tubular billet through a cooling medium.

[0008] As a further improvement of the present invention, the internal cooling device can be configured as a water-circulating internal cooling sizing sleeve, which is connected to the extrusion end of the extrusion die, and the water-circulating internal cooling sizing sleeve is in contact with the inner surface of the molten pipe blank.

[0009] As a further improvement of the present invention, the internal cooling device may also be configured as a spray-type internal cooling structure, which is disposed at the extrusion end of the extrusion die and has multiple nozzles, the multiple nozzles being arranged circumferentially along the inner surface of the molten tubular material and close to the inner surface of the molten tubular material.

[0010] As a further improvement of the present invention, the internal cooling device may simultaneously include the water circulation internal cooling sizing sleeve and the spray-type internal cooling structure. In this case, the spray-type internal cooling structure is connected to the water circulation internal cooling sizing sleeve. Alternatively, the internal cooling device may be configured as either the water circulation internal cooling sizing sleeve or the spray-type internal cooling structure.

[0011] As a further improvement of the present invention, the water circulation internal cooling sizing sleeve includes:

[0012] An internal cooling sizing sleeve abuts against the inner surface of the molten pipe blank through a heat insulation plate, and the internal cooling sizing sleeve has a spiral water flow channel inside;

[0013] The first water inlet pipe has one end connected to an external water tank and the other end connected to the water inlet end of the spiral water flow channel;

[0014] The first water outlet pipe has one end connected to the water outlet end of the spiral water flow channel and the other end used for draining water outward.

[0015] As a further improvement of the present invention, the spray-type internal cooling structure includes:

[0016] A spray tube sleeve is connected to the inner cooling sizing sleeve or to the extrusion end of the extrusion die. There is a water-air mixing space between the inner wall and the outer wall of the spray tube sleeve, and the nozzle is disposed on the outer wall of the spray tube sleeve and communicates with the water-air mixing space.

[0017] A compressed air inlet pipe is disposed on the inner wall of the spray pipe sleeve and communicates with the water-air mixing space;

[0018] The second water inlet pipe is located on the inner wall of the spray pipe sleeve and communicates with the water-air mixing space.

[0019] As a further improvement of the present invention, the compressed air input by the compressed air intake pipe and the cooling water input by the second water inlet pipe are mixed in the water-air mixing space to form a water-air mixture, and the water-air mixture is sprayed outward from the nozzle to cool the inner surface of the molten pipe blank.

[0020] As a further improvement of the present invention, an exhaust device is also included, comprising:

[0021] The exhaust pipe has its rear end located outside the extrusion mold and connected to an external exhaust fan, and its front end passes through the extrusion mold and enters the molten tubular material. The front end of the exhaust pipe has multiple exhaust holes.

[0022] A fog-blocking ring is located inside the molten tubing blank and installed at the front end of the exhaust pipe. The exhaust hole is close to the fog-blocking ring, and there is a distance between the fog-blocking ring and the spray-type internal cooling structure. The fog-blocking ring blocks the cooling water mist sprayed by the spray-type internal cooling structure, and allows the cooling water mist after heat exchange to be drawn out from the exhaust hole.

[0023] As a further improvement of the present invention, a water ring vacuum sizing sleeve is provided on the outer surface of the molten pipe blank, which is arranged vertically and vertically corresponding to the spray-type internal cooling structure.

[0024] As a further improvement of the present invention, the water ring vacuum sizing sleeve includes:

[0025] A cooling copper sleeve is fitted onto the molten tubular billet and the two abut against each other; the cooling copper sleeve has an annular flow channel.

[0026] A water ring chamber is disposed on the cooling copper sleeve, and the water ring chamber is connected to the annular flow channel;

[0027] A water tap that extends into the water ring chamber and is used to connect a water pipe.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The internal cooling device is arranged circumferentially along the inner surface of the molten pipe blank and exchanges heat with the inner surface of the molten pipe blank through the cooling medium. This can quickly cool the inner surface of the molten pipe blank, thereby ensuring the quality of the pipe after hardening and forming.

[0030] 2. The internal cooling device preferably employs a cooling method that combines a water-circulating internal cooling sizing sleeve with a spray-type internal cooling structure. After the high-temperature molten pipe blank is extruded, the water-circulating internal cooling sizing sleeve will cool the high-temperature inner wall once. Subsequently, the inner wall, which has completed the initial cooling, will undergo a secondary cooling through the spray-type internal cooling structure. The secondary cooling rapidly reduces the temperature of the inner wall of the molten pipe blank and allows the pipe to be formed. It is precisely because the primary cooling pre-cools the originally high-temperature inner wall of the molten pipe blank that the secondary cooling does not cause the inner wall of the molten pipe blank to shrink rapidly. Ultimately, this ensures that the formed pipe has a smooth inner wall, guaranteeing product quality.

[0031] 3. When the water vapor mixture comes into contact with the inner wall of the high-temperature molten pipe blank and undergoes heat exchange, water vapor will be generated. The fog ring blocks the water vapor to prevent it from spreading. At this time, the external exhaust fan can draw the water vapor out from the exhaust hole, taking away the heat and thus ensuring good cooling effect.

[0032] 4. A water ring vacuum sizing sleeve is set on the outer surface of the molten pipe blank, and is set up in a corresponding manner with the spray-type internal cooling structure to ensure the synchronicity of the outer diameter sizing and the inner diameter cooling and solidification of the molten pipe blank, thereby improving the pipe forming quality.

[0033] 5. The spray-type internal cooling structure has a water-air mixing space, which ensures that the cooling water and compressed air can be fully mixed in the water-air mixing space to obtain a water-air mixture. In addition, an atomizing head is installed at the end of the second water inlet pipe, so that the cooling water entering the water-air mixing space is atomized, which further improves the mixing effect of compressed air and cooling water. Attached Figure Description

[0034] Figure 1This is a schematic diagram of the structure of the large-diameter thick-walled plastic pipe inner wall cooling device of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure of the water circulation internal cooling sizing sleeve of the present invention;

[0036] Figure 3 This is a schematic diagram of the spray-type internal cooling structure of the present invention;

[0037] Figure 4 This is a schematic diagram of the structure of the water ring vacuum sizing sleeve of the present invention.

[0038] In the diagram, 100 is the extrusion die; 110 is the water-circulating internal cooling sizing sleeve; 111 is the internal cooling sizing sleeve; 1111 is the spiral water flow channel; 112 is the heat insulation plate; 113 is the first water inlet pipe; 114 is the first water outlet pipe; 120 is the spray-type internal cooling structure; 121 is the nozzle; 122 is the spray pipe sleeve; 123 is the water-air mixing space; 124 is the compressed air inlet pipe; 125 is the second water inlet pipe; 1251 is the atomizing head; 130 is the exhaust device; 131 is the exhaust pipe; 1311 is the exhaust hole; 132 is the fog baffle; 140 is the water ring vacuum sizing sleeve; 141 is the cooling copper sleeve; 1411 is the annular flow channel; 142 is the water ring chamber; 143 is the water nozzle; and 200 is the molten pipe blank. Detailed Implementation

[0039] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical methods of the present invention. However, the present invention is not limited to these embodiments.

[0040] like Figure 1-4 As shown, the present invention provides a cooling device for the inner wall of a large-diameter, thick-walled plastic pipe, comprising:

[0041] An extrusion die 100 is used to extrude a molten pipe blank 200. The pipe extruded by the extrusion die 100 is a thick-walled plastic pipe. Due to its large wall thickness, if only the outer wall is cooled, the low temperature of the outer wall cannot be quickly transferred to the inner wall. This will cause the inner wall to sag due to the inability to cool in time, resulting in uneven pipe wall thickness. To solve this problem, an internal cooling device is added in this embodiment to cool the inner surface of the molten pipe blank 200.

[0042] An internal cooling device is located at the extrusion end of the extrusion die 100 and connected to the extrusion die 100. The internal cooling device is arranged circumferentially along the inner surface of the pipe molten blank 200 and exchanges heat with the inner surface of the pipe molten blank 200 through a cooling medium. This can quickly cool the inner surface of the pipe molten blank 200, thereby ensuring the quality of the pipe after hardening and molding.

[0043] It is worth mentioning that the internal cooling device in this embodiment can select various cooling methods, including water cooling, oil cooling, air cooling, and water-air mixing. Among them, water cooling and oil cooling, which use liquid media, need to exchange heat with the molten pipe blank 200 through the sizing sleeve, and their cooling speed is relatively slow. In contrast, air cooling and water-air mixing can directly contact the inner surface of the molten pipe blank 200, and their cooling speed is relatively fast. Therefore, how to better improve the cooling effect on the basis of cooling the inner wall of the molten pipe blank 200 is also a problem worth exploring in this embodiment.

[0044] Preferably, the internal cooling device can be configured as a water-circulating internal cooling sizing sleeve 110, which is connected to the extrusion end of the extrusion die 100, and the water-circulating internal cooling sizing sleeve 110 is in contact with the inner surface of the molten pipe blank 200. In this case, the internal cooling device adopts a water-cooling / oil-cooling cooling method.

[0045] Preferably, the internal cooling device can also be configured as a spray-type internal cooling structure 120, which is set at the extrusion end of the extrusion die 100 and has multiple nozzles 121. The multiple nozzles 121 are arranged circumferentially along the inner surface of the molten tubular material 200 and close to the inner surface of the molten tubular material 200. In this case, the internal cooling device adopts a water-air mixing cooling method.

[0046] Furthermore, the internal cooling device can simultaneously include a water-circulating internal cooling sizing sleeve 110 and a spray-type internal cooling structure 120. In this case, the spray-type internal cooling structure 120 is connected to the water-circulating internal cooling sizing sleeve 110. The internal cooling device can also be configured as either a water-circulating internal cooling sizing sleeve 110 or a spray-type internal cooling structure 120. Therefore, all three cooling methods should be included within the scope of protection of this application. In this embodiment, in order to improve the cooling effect on the inner wall of the molten pipe blank 200, it is preferable to adopt a cooling method that simultaneously includes a water-circulating internal cooling sizing sleeve 110 and a spray-type internal cooling structure 120. The specific reasons are explained as follows:

[0047] First, the cooling method of using water-circulating internal cooling sizing sleeve 110 alone can use cooling water or cooling oil as the cooling medium. However, since it needs to exchange heat with the molten pipe blank 200 through the sizing sleeve, its cooling speed is slow and it cannot make the inner wall of the molten pipe blank 200 form quickly, which has certain defects.

[0048] Secondly, when using a spray-type internal cooling structure 120 alone, the cooling medium can be a water-air mixture or compressed air. However, whether it is a water-air mixture or compressed air, it is sprayed onto the inner wall of the molten pipe blank 200 for cooling. This cooling method will result in a cooling rate that is too fast. At this time, the high temperature inner wall of the molten pipe blank 200 will shrink rapidly and produce wrinkles, resulting in a problem of poor inner surface quality of the final formed pipe.

[0049] The preferred cooling method incorporates both a water-circulating internal cooling sizing sleeve 110 and a spray-type internal cooling structure 120. In this case, after the high-temperature molten pipe blank 200 is extruded from the extrusion die 100, the water-circulating internal cooling sizing sleeve 110 will cool the high-temperature inner wall once. Subsequently, the inner wall, which has completed the initial cooling, will undergo secondary cooling through the spray-type internal cooling structure 120. The secondary cooling rapidly reduces the inner wall temperature of the molten pipe blank 200 and allows the pipe to be formed. Because the primary cooling pre-cools the originally high-temperature inner wall of the molten pipe blank 200, the secondary cooling will not cause the inner wall of the molten pipe blank 200 to shrink, ultimately ensuring that the formed pipe has a smooth inner wall and guaranteeing product quality.

[0050] Preferably, the water-circulating internal cooling sizing sleeve 110 includes:

[0051] The internal cooling sizing sleeve 111 abuts against the inner surface of the molten pipe blank 200 through the heat insulation plate 112, and the internal cooling sizing sleeve 111 has a spiral water flow channel 1111 inside;

[0052] The first water inlet pipe 113 has one end connected to an external water tank and the other end connected to the water inlet end of the spiral water flow channel 1111.

[0053] The first water outlet pipe 114 has one end connected to the water outlet end of the spiral water flow channel 1111 and the other end used for draining water outward.

[0054] The internal cooling sizing sleeve 111 supports and sizing the inner wall of the extruded pipe molten blank 200, and cools the inner wall of the pipe molten blank 200 once through circulating water cooling to ensure that it has initial hardness.

[0055] Preferably, the spray-type internal cooling structure 120 includes:

[0056] The spray pipe sleeve 122 is connected to the inner cooling sizing sleeve 111. There is a water-air mixing space 123 between the inner wall and the outer wall of the spray pipe sleeve 122, and the nozzle 121 is disposed on the outer wall of the spray pipe sleeve 122 and communicates with the water-air mixing space 123.

[0057] The compressed air inlet pipe 124 is installed on the inner wall of the spray pipe sleeve 122 and communicates with the water-air mixing space 123, so that compressed air can enter the water-air mixing space 123.

[0058] The second water inlet pipe 125 is installed on the inner wall of the spray pipe sleeve 122 and communicates with the water-air mixing space 123. Thus, cooling water can enter the water-air mixing space 123 and mix with compressed air to obtain a water-air mixture, which is then sprayed out from the nozzle 121 onto the inner wall of the molten pipe blank 200. At this time, the water-air mixture exchanges heat with the high temperature molten pipe blank 200, absorbs heat and forms a large amount of water vapor, which plays a role in rapid cooling.

[0059] In order to improve the mixing effect of compressed air and cooling water, an atomizing head 1251 is installed at the end of the second water inlet pipe 125, so that the cooling water entering the water-air mixing space 123 is atomized.

[0060] Preferably, it also includes an exhaust device 130, which comprises:

[0061] The exhaust pipe 131 has its rear end located outside the extrusion die 100 and connected to an external exhaust fan, and its front end passes through the extrusion die 100 and enters the molten tubular material 200. The exhaust pipe 131 has multiple exhaust holes 1311 at its front end.

[0062] The defogging ring 132 is located inside the molten tubing blank 200 and installed at the front end of the exhaust pipe 131. At the same time, the exhaust port 1311 is close to the defogging ring 132, and there is a distance between the defogging ring 132 and the spray-type internal cooling structure 120. Specifically, when the water vapor mixture comes into contact with the high-temperature molten tubing blank 200 and undergoes heat exchange, water vapor will be generated. In order to ensure a good cooling effect, this part of the water vapor needs to be discharged to the outside. At this time, the defogging ring 132 can block the water vapor and prevent the water vapor from spreading. At this time, the external exhaust fan can draw the water vapor out from the exhaust port 1311, thereby ensuring a good cooling effect.

[0063] Preferably, the outer surface of the molten pipe blank 200 is also provided with a water ring vacuum sizing sleeve 140, which is arranged vertically and vertically corresponding to the spray-type internal cooling structure 120. It should be noted that the water ring chamber 142 vacuum sizing sleeve is used to cool and sizing the outer wall of the molten pipe blank 200. The reason why it is arranged vertically and vertically corresponding to the spray-type internal cooling structure 120 is to ensure the synchronicity of the outer diameter sizing and the inner diameter cooling and solidification of the molten pipe blank 200, thereby improving the pipe forming quality.

[0064] Preferably, the water ring vacuum sizing sleeve 140 includes:

[0065] Cooling copper sleeve 141 is sleeved on the molten tubular billet 200 and the two abut against each other. Cooling copper sleeve 141 has an annular flow channel 1411.

[0066] A water ring chamber 142 is disposed on a cooling copper sleeve 141, and the water ring chamber 142 is connected to an annular flow channel 1411;

[0067] Water nozzle 143 extends into water ring chamber 142 and is used to connect water pipe. Similarly, it circulates repeatedly in annular flow channel 1411 through cooling water or cooling oil, constantly exchanging heat with the outer wall of molten pipe blank 200, and ultimately cooling the outer wall.

[0068] In addition to the water ring chamber 142 vacuum sizing sleeve, a spray-type cooling device is also provided for cooling the outer wall of the molten pipe blank 200. This spray-type cooling device is located at the front end of the water ring chamber 142 vacuum sizing sleeve (it is existing technology and therefore not shown in the figure).

[0069] The technical means disclosed in this invention are not limited to the single technical features mentioned above, but also include technical solutions composed of any combination of the above technical features. The above are specific embodiments of this invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of this invention, and these improvements and modifications are also considered to be within the scope of protection of this invention.

[0070] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0071] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0072] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0073] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A cooling device for the inner wall of a large-diameter, thick-walled plastic pipe, characterized in that, include: Extrusion die, used to extrude molten tubular material; An internal cooling device is located at the extrusion end of the extrusion die and connected to the extrusion die. The internal cooling device is arranged circumferentially along the inner surface of the molten tubular material and exchanges heat with the inner surface of the molten tubular material through a cooling medium. The internal cooling device includes a water-circulating internal cooling sizing sleeve and a spray-type internal cooling structure. The water-circulating internal cooling sizing sleeve includes: An internal cooling sizing sleeve abuts against the inner surface of the molten pipe blank through a heat insulation plate, and the internal cooling sizing sleeve has a spiral water flow channel inside; The first water inlet pipe has one end connected to an external water tank and the other end connected to the water inlet end of the spiral water flow channel; The first water outlet pipe has one end connected to the water outlet end of the spiral water flow channel and the other end used for draining water outwards. The spray-type internal cooling structure includes: A spray pipe sleeve is connected to the inner cooling sizing sleeve, and there is a water-air mixing space between the inner wall and the outer wall of the spray pipe sleeve; A nozzle is disposed on the outer wall of the spray tube sleeve and communicates with the water-air mixing space; A compressed air inlet pipe is disposed on the inner wall of the spray pipe sleeve and communicates with the water-air mixing space; The second water inlet pipe is disposed on the inner wall of the spray pipe sleeve and communicates with the water-air mixing space; The exhaust system includes: The exhaust pipe has its rear end located outside the extrusion mold and connected to an external exhaust fan, and its front end passes through the extrusion mold and enters the molten tubular material. The front end of the exhaust pipe has multiple exhaust holes. A fog-blocking ring is located inside the molten tubing blank and installed at the front end of the exhaust pipe. The exhaust hole is close to the fog-blocking ring, and there is a distance between the fog-blocking ring and the spray-type internal cooling structure. The fog-blocking ring blocks the cooling water mist sprayed by the spray-type internal cooling structure, and allows the cooling water mist after heat exchange to be drawn out from the exhaust hole. The outer surface of the molten pipe blank is also provided with a water ring vacuum sizing sleeve, which is arranged vertically and vertically corresponding to the spray-type internal cooling structure.

2. The cooling device for the inner wall of a large-diameter thick-walled plastic pipe according to claim 1, characterized in that, The compressed air input through the compressed air intake pipe and the cooling water input through the second water intake pipe are mixed in the water-air mixing space to form a water-air mixture. The water-air mixture is sprayed outward from the nozzle to cool the inner surface of the molten tubular material.

3. The cooling device for the inner wall of a large-diameter thick-walled plastic pipe according to claim 1, characterized in that, The water ring vacuum sizing sleeve includes: A cooling copper sleeve is fitted onto the molten tubular billet and the two abut against each other; the cooling copper sleeve has an annular flow channel. A water ring chamber is disposed on the cooling copper sleeve, and the water ring chamber is connected to the annular flow channel; A water tap that extends into the water ring chamber and is used to connect a water pipe.

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