A PVC plate gradient cooling device based on multi-stage countercurrent and atomization assistance

Abstract

The utility model provides a kind of PVC board gradient cooling equipment based on multistage counterflow and atomization auxiliary, including fixed seat and the cooling roll group and cooling auxiliary unit being set on fixed seat;Cooling roll group includes the cooling roll of being set to several along fixed seat length direction, cooling roll is hollow structure and several cooling roll is sequentially communicated, cooling water is circulated in cooling roll group, the flow direction of cooling water is opposite with the movement direction of PVC board, by using the cooling mode of counterflow heat exchange, significantly improve heat exchange efficiency, the reverse temperature change process of cooling water and PVC board can better adapt to the cooling process of PVC board, so that PVC board can be cooled faster and more evenly;Cooling auxiliary unit is fixedly set above cooling roll group, for providing cooling for the side of PVC board away from cooling roll group;Effectively avoid the problems such as uneven shrinkage of board, large internal and external temperature difference, internal stress generation caused by the too large difference of cooling rate of upper and lower surfaces of PVC board.

Description

Technical Field

[0001] This utility model relates to the field of PVC sheet production and processing technology, and in particular to a gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance. Background Technology

[0002] Existing PVC sheet cooling lines mostly use simple roller water cooling. The bottom of the sheet is in contact with the water-cooled roller, resulting in fast cooling, while the top of the sheet relies on air cooling, which is slower. This difference in cooling rate between the upper and lower surfaces can lead to uneven shrinkage inside the sheet, large temperature differences between the inside and outside, and internal stress that can cause product warping and deformation. The produced sheets may appear flat after cooling, but during subsequent cutting or use, the release of internal stress can cause the product to warp (arch upwards or bend downwards), deform, and even affect the splicing accuracy of the locking mechanism.

[0003] Some cooling equipment used in PVC sheet production employs co-current cooling or simple zoned cooling methods. These methods exhibit low heat exchange efficiency in practical applications, leading to high energy consumption and increased energy costs. Furthermore, for thicker or harder sheets, such as SPC sheets, this cooling method is ineffective, failing to achieve the desired cooling effect and thus impacting sheet quality and production efficiency. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the defects of the existing technology. This utility model proposes a gradient cooling device for PVC sheets based on multi-stage counterflow and atomization assistance. It avoids problems such as uneven shrinkage, large internal and external temperature difference, and easy generation of internal stress leading to product warping and deformation caused by excessive difference in cooling rate between the upper and lower surfaces of PVC sheets during the cooling process. It improves the heat exchange efficiency between PVC sheets and cooling medium and reduces the operating energy consumption of cooling equipment.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance, comprising: Fixed base; A cooling roller assembly is disposed on the fixed base and includes a plurality of cooling rollers arranged along the length of the fixed base. The cooling rollers are hollow and the plurality of cooling rollers are connected in sequence. A cooling auxiliary unit is fixedly installed above the cooling roller assembly to provide cooling for the side of the PVC sheet facing away from the cooling roller assembly. Cooling water flows through the cooling roller assembly, and the flow direction of the cooling water is opposite to the movement direction of the PVC sheet.

[0006] In some embodiments, the cooling roller assembly sequentially includes a pre-cooling zone, a main cooling zone, and a fine cooling zone along the direction of movement. The pre-cooling zone is connected to a heat exchange unit, and the fine cooling zone is connected to a cooling water unit. The cooling auxiliary unit includes an atomizing cooling unit and an air-cooling cooling unit, either of which is fixedly disposed above any one of the pre-cooling zone, the main cooling zone, and the fine cooling zone. Therefore, a more precise and efficient cooling method can be provided according to the cooling needs of different areas.

[0007] In some embodiments, the atomizing cooling unit is disposed above the pre-cooling zone and the main cooling zone, and the air-cooling unit is disposed above the fine cooling zone. Therefore, differentiated cooling treatment can be performed to meet the needs of PVC sheets at different cooling stages. In the pre-cooling and main cooling stages, the atomizing cooling unit absorbs heat through the evaporation of tiny water droplets, rapidly reducing the surface temperature of the sheet while avoiding excessive moisture residue; while in the fine cooling stage, the air-cooling unit uses high-speed airflow to remove residual heat from the sheet surface, ensuring a uniform temperature drop across the entire sheet.

[0008] In some embodiments, the air-cooling unit includes at least one air knife, and the atomizing cooling unit includes at least one atomizing air knife. The lengths of both the air knife and the atomizing air knife are not less than the length of the cooling roller. This ensures uniform cooling across the entire width of the PVC sheet, avoiding cooling dead zones or uneven cooling. The lengths of the air knife and the atomizing air knife are designed to fully consider the actual production width of the PVC sheet, allowing the cooling effect to comprehensively cover the sheet surface, improving the uniformity and consistency of cooling.

[0009] In some embodiments, the air knife and atomizing air knife are inclinedly disposed above the cooling roller assembly, with the inclination angle between 20° and 50°. This further optimizes the cooling effect, allowing the cooling medium (airflow or atomized water droplets) to make more thorough contact with the PVC sheet surface, thus enhancing heat exchange efficiency. The inclination angle range of 20° to 50° ensures effective coverage of the cooling medium while avoiding a decrease in cooling efficiency or waste of medium due to excessively large or small angles.

[0010] In some embodiments, a compression section and a conveying section are sequentially arranged at both ends of the cooling roller. The diameter of the conveying section is not greater than the diameter of the cooling roller, and the diameter of the compression section is smaller than the diameter of the conveying section. Therefore, the heat exchange efficiency between the cooling roller and the PVC sheet can be improved under the action of the Venturi effect, while achieving energy saving and noise reduction to a certain extent.

[0011] In some embodiments, a pressure roller is further included, which is disposed between the cooling roller assembly and the cooling auxiliary unit, and the distance between the pressure roller and the cooling roller assembly is not less than the thickness of the PVC sheet. This ensures that the PVC sheet remains stable during the cooling process, preventing the cooling effect from being affected by the sheet floating or shifting.

[0012] Compared with the prior art, the beneficial effects of this utility model include: In the technical solution of this application embodiment, the PVC sheet gradient cooling device includes a fixed base and a cooling roller group and a cooling auxiliary unit disposed on the fixed base. The cooling roller group includes a plurality of cooling rollers disposed along the length direction of the fixed base. The cooling rollers are hollow and the plurality of cooling rollers are connected in sequence. Cooling water flows through the cooling roller group. The flow direction of the cooling water is opposite to the movement direction of the PVC sheet. By adopting a countercurrent heat exchange cooling method, the heat exchange efficiency is significantly improved. The reverse temperature change process between the cooling water and the PVC sheet can better adapt to the cooling process of the PVC sheet, so that the PVC sheet can be cooled faster and more uniformly. The cooling auxiliary unit is fixedly disposed above the cooling roller group and is used to provide cooling for the side of the PVC sheet away from the cooling roller group. This effectively avoids problems such as uneven sheet shrinkage, large internal and external temperature difference, and internal stress caused by excessive difference in cooling rates between the upper and lower surfaces of the PVC sheet. Attached Figure Description

[0013] The disclosure of this utility model is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this utility model. In the drawings, the same reference numerals are used to refer to the same parts. Wherein: Figure 1 The schematic diagram illustrates the overall structure of a gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance; Figure 2 Schematic representation Figure 1 Top view structure; Figure 3 The schematic diagram shows the overall structure of the cooling roller; Figure 4 Schematic representation Figure 3 The magnified structure of region A in the middle.

[0014] The numbers in the diagram are: 1-fixed seat, 2-cooling roller group, 21-precooling zone, 22-main cooling zone, 23-fine cooling zone, 3-cooling auxiliary unit, 31-atomizing cooling unit, 32-air-cooling unit, 4-heat exchange unit, 5-cooling water unit, 6-cooling roller, 7-compression section, 8-conveying section, 9-pressure roller. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0017] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0018] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0019] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0020] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0021] In this application, "multiple" means two or more (including two).

[0022] The inventors of this application have noticed that existing PVC sheet cooling lines mostly use simple roller water cooling. The bottom of the sheet is in contact with the water-cooled roller, resulting in fast cooling, while the top of the sheet relies on air cooling, which is slower. This difference in cooling rate between the upper and lower surfaces can lead to uneven shrinkage inside the sheet, large temperature differences between the inside and outside, and internal stress that can cause product warping and deformation. The produced sheet may appear flat after cooling, but during subsequent cutting or use, the release of internal stress can cause the product to warp (arch upwards or bend downwards), deform, and even affect the splicing accuracy of the locking mechanism.

[0023] The inventors discovered through research that some cooling equipment used in PVC sheet production employs co-current cooling or a relatively simple zoned cooling method. This method exhibits low heat exchange efficiency in practical applications, leading to high energy consumption and increased energy costs. Furthermore, for thicker or harder sheets, such as SPC sheets, this cooling method is ineffective, failing to achieve the desired cooling effect and thus impacting sheet quality and production efficiency.

[0024] Based on the aforementioned problems discovered by the inventors, the inventors designed a gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance, including a fixed base 1 and a cooling roller group 2 and a cooling auxiliary unit 3 disposed on the fixed base 1; the cooling roller group 2 includes several cooling rollers 6 arranged along the length direction of the fixed base 1, the cooling rollers 6 are hollow structures and several cooling rollers 6 are connected in sequence, and cooling water flows through the cooling roller group 2, the flow direction of the cooling water is opposite to the movement direction of the PVC sheet, by adopting a countercurrent heat exchange cooling method, the heat exchange efficiency is significantly improved, and the reverse temperature change process between the cooling water and the PVC sheet can better adapt to the cooling process of the PVC sheet, so that the PVC sheet can be cooled faster and more uniformly; the cooling auxiliary unit 3 is fixedly disposed above the cooling roller group 2, and is used to provide cooling for the side of the PVC sheet away from the cooling roller group 2; effectively avoiding problems such as uneven sheet shrinkage, large internal and external temperature difference, and internal stress caused by excessive difference in cooling rate between the upper and lower surfaces of the PVC sheet.

[0025] Please see Figure 1 and Figure 2 , Figure 1 The overall structure of the gradient cooling equipment for PVC sheets based on multi-stage countercurrent and atomization assistance is as follows: Figure 2 for Figure 1 The top-down view of the structure.

[0026] A gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance includes a fixed base 1 and a cooling roller assembly 2 and a cooling auxiliary unit 3 disposed on the fixed base 1. The cooling roller assembly 2 includes several cooling rollers 6 arranged along the length of the fixed base 1, and the cooling rollers 6 are all hollow structures. The several cooling rollers 6 are connected in sequence to facilitate the introduction of a cooling medium, such as cooling water, into the cooling rollers 6 and to allow the cooling water to flow in a certain manner within the cooling rollers 6, thereby completing the heat exchange between the cooling rollers 6 and the PVC sheet moving above the cooling rollers 6. The cooling auxiliary unit 3 is fixedly disposed above the cooling roller assembly 2 and is used to provide cooling for the side of the PVC sheet facing away from the cooling roller assembly 2, thereby ensuring that the temperature on the upper and lower sides of the PVC sheet is relatively balanced and reducing the generation of internal stress in the PVC sheet. It is worth noting that the cooling water flowing in the cooling roller group 2 flows in the opposite direction to the movement of the PVC sheet. This multi-stage counter-current cooling method can significantly improve heat exchange efficiency, so that the temperature difference between the upper and lower surfaces of the PVC sheet can be effectively controlled during the cooling process, thereby reducing the internal stress caused by uneven temperature, effectively avoiding problems such as board warping and deformation, and improving product quality.

[0027] Optionally, the aforementioned cooling roller assembly 2 is divided along the direction of movement into a pre-cooling zone 21, a main cooling zone 22, and a fine cooling zone 23. The pre-cooling zone 21 is connected to the heat exchange unit 4, and the fine cooling zone 23 is connected to the cooling water unit 5. In the pre-cooling zone 21, the PVC sheet has just exited the press, and its temperature is 150-180℃. The cooling water used for heat exchange with the sheet in this zone, after passing through the fine cooling zone 23 and the main cooling zone 22, experiences a significant temperature rise, reaching a temperature of 30-35℃. At this point, an effective and gentle temperature difference exists between the sheet and the cooling water, allowing the cooling process to begin. This design avoids surface hardening, increased internal stress, and surface defects caused by rapid cooling. In the main cooling zone 22, after the PVC sheet undergoes cooling in the pre-cooling zone 21, it exchanges heat with the cooling water flowing through the fine cooling zone 23, reducing the PVC sheet temperature from 150℃ to approximately 60℃. The cooling water temperature flowing through the main cooling zone 22 is 20-25℃. In the fine cooling zone 23, the PVC sheet temperature has dropped to approximately 60℃. It then exchanges heat with the coolest cooling water (e.g., 15℃) in this zone, ensuring dimensional stability and stress-free operation when the sheet exits the cooling line. As the cooling water flows sequentially through the fine cooling zone 23, main cooling zone 22, and pre-cooling zone 21, its temperature continuously rises, while the sheet temperature continuously decreases under the influence of the cooling water. This multi-stage counter-flow design makes the heat exchange between the cooling water and the sheet more thorough and efficient. In the pre-cooling zone 21, the cooling water absorbs heat from the sheet material, causing its temperature to rise. By the time it enters the main cooling zone 22, its temperature is significantly higher than when it first entered the pre-cooling zone 21, but still lower than the sheet material's temperature in the main cooling zone 22, allowing it to continue absorbing heat from the sheet material. Similarly, the cooling water that has absorbed heat in the main cooling zone 22, before entering the pre-cooling zone 21, although its temperature rises again, still maintains an effective temperature difference compared to the high-temperature sheet material just transferred from the press, allowing it to continue cooling the sheet material. The fine cooling zone 23 uses the lowest temperature cooling water to provide final cooling to the sheet material that has undergone pre-cooling and main cooling treatments, ensuring that the sheet material reaches the ideal temperature when it exits the cooling line.

[0028] It should be further explained that heat exchange unit 4 can specifically be a plate heat exchanger. The cooling water flowing out of the precooling zone 21 has a temperature of approximately 50-60℃. This cooling water exchanges heat with the PVC resin and / or filler that is about to enter the mixer in heat exchange unit 4, thereby completing the preheating process of the PVC resin and / or filler. This can effectively reduce the energy consumption of heating the raw materials for PVC sheets and significantly reduce production costs. At the same time, preheating the raw materials can also make the mixing of raw materials more uniform and sometimes even improve the product performance of PVC sheets.

[0029] In addition, the cooling auxiliary unit 3 includes an atomizing cooling unit 31 and an air-cooling cooling unit 32, and either the atomizing cooling unit 31 or the air-cooling cooling unit 32 is fixedly disposed above any one of the pre-cooling zone 21, the main cooling zone 22, and the fine cooling zone 23. By providing the atomizing cooling unit 31 or the air-cooling cooling unit 32 above the pre-cooling zone 21, the main cooling zone 22, and the fine cooling zone 23, cooling treatment can be completed on the other side of the PVC sheet, forming a synergistic cooling effect with the cooling roller group 2.

[0030] Preferably, an atomizing cooling unit 31 is provided above the pre-cooling zone 21 and the main cooling zone 22, and an air-cooling cooling unit 32 is provided above the fine cooling zone 23. In the pre-cooling zone 21, the atomizing cooling unit 31 can perform preliminary cooling of the PVC sheet, causing the surface temperature of the sheet to drop rapidly, preparing it for subsequent cooling in the main cooling zone 22. After entering the main cooling zone 22, another atomizing cooling unit 31 can further enhance the cooling effect according to the specific conditions of the sheet, ensuring that the heat inside the sheet can be dissipated in time. That is, in the pre-cooling and main cooling stages, the atomizing cooling unit 31 absorbs heat through the evaporation of tiny water droplets, quickly reducing the surface temperature of the sheet while avoiding excessive moisture residue. In the fine cooling zone 23, the air-cooling unit 32 can perform final fine cooling of the sheet, that is, using high-speed airflow to remove residual heat from the surface of the sheet, ensuring that the overall temperature of the sheet drops evenly, so that the sheet reaches the required temperature, and ensuring that the cooling rate of the upper and lower surfaces of the sheet is more balanced. This effectively avoids problems such as uneven sheet shrinkage, large internal and external temperature differences, and internal stress caused by excessive differences in the cooling rates of the upper and lower surfaces, greatly improving the quality of the produced PVC sheet, reducing the occurrence of product warping and deformation, and ensuring the splicing accuracy of the locking mechanism. Meanwhile, the multi-stage counter-current cooling method and the cooperation of cooling auxiliary unit 3 also improve heat exchange efficiency, reduce energy consumption during equipment operation, and save energy consumption costs. For thicker or harder boards, such as SPC boards, it can also achieve ideal cooling effect and improve the production efficiency of the boards.

[0031] It is worth noting that the aforementioned air-cooling unit 32 includes at least one air knife, and the atomizing cooling unit 31 includes at least one atomizing air knife, with the length of both the air knife and the atomizing air knife being no less than the length of the cooling roller 6. This arrangement ensures uniform and comprehensive cooling of the PVC sheet across its entire width, preventing any uncooled areas or inconsistent cooling levels. In actual production, the width of PVC sheets has specific dimensions. The lengths of the air knife and the atomizing air knife are no less than the length of the cooling roller 6, which is positioned along the length of the fixed base 1 and adapted to the width direction of the sheet. This ensures that the air knife and the atomizing air knife can cover every part of the sheet's width, allowing each part to receive effective cooling. This improves the uniformity and consistency of cooling across the entire sheet, contributing to improved overall sheet quality.

[0032] In a preferred embodiment, the air knife and atomizing air knife are inclined above the cooling roller assembly 2, with an inclination angle between 20° and 50°. This inclined arrangement has several advantages, further optimizing the cooling effect. When the air knife and atomizing air knife are inclined, the cooling medium (airflow or atomized water droplets) can be sprayed onto the PVC sheet surface at a more suitable angle, making more thorough contact with the sheet surface and thus enhancing heat exchange efficiency. Within this angle range, it ensures that the cooling medium effectively covers the sheet surface, achieving a good cooling effect, while avoiding uneven cooling and media waste caused by either an excessively large angle (which would result in insufficient contact with the sheet) or an excessively small angle (which would cause the cooling medium to be sprayed too concentratedly onto a small area of ​​the sheet), thereby ensuring the high efficiency and economy of the cooling process.

[0033] Please see Figure 3 and Figure 4 , Figure 3 The overall structure of the cooling roller Figure 4 for Figure 3 The magnified structure of region A in the middle.

[0034] To improve the cooling effect of the cooling roller 6, a compression section 7 and a conveying section 8 are sequentially arranged at both ends of the cooling roller 6. The diameter of the conveying section 8 is no larger than the diameter of the cooling roller 6, while the diameter of the compression section 7 is smaller than the diameter of the conveying section 8. The conveying section 8 and the compression section 7 are connected by a rotary joint, forming a Venturi-like structure. When the cooling water flows from the conveying section 8 to the compression section 7, the flow rate naturally increases. On the one hand, this promotes the high-speed flow of cooling water in the cooling roller 6, thereby violently scouring the inner wall of the roller and effectively breaking down the stagnant heat edge formed on the wall surface due to the increase in water temperature. The venturi effect enhances the heat exchange efficiency of the cooling roller 6 and the PVC board. On the other hand, the venturi effect can increase the flow rate and volume of cooling water in the cooling roller 6. To achieve the same cooling effect, the power of the water pump used to draw cooling water from the self-cooling water unit 5 can be appropriately reduced, or a better cooling effect can be obtained without increasing the pump load, thereby achieving energy saving. At the same time, compared with increasing the flow rate by using a throttle valve or increasing the pump speed, the venturi structure guides the water flow through its physical shape, resulting in a smoother flow field, reducing vibration and noise caused by turbulence and cavitation, and making the equipment operate more smoothly.

[0035] In a preferred embodiment, a pressure roller 9 is also provided, positioned between the cooling roller group 2 and the cooling auxiliary unit 3. The distance between the pressure roller 9 and the cooling roller group 2 is not less than the thickness of the PVC sheet. This arrangement ensures that during the cooling process, the PVC sheet is stably pressed onto the cooling roller group 2, preventing it from floating or shifting due to airflow or water mist generated by the cooling auxiliary unit 3 (such as the atomizing cooling unit 31 or the air-cooling cooling unit 32). Floating or shifting of the sheet not only leads to loose contact between the sheet and the cooling roller group 2, affecting heat exchange efficiency, but may also cause uneven cooling, resulting in internal stress and affecting the final quality of the sheet. The presence of the pressure roller 9 acts like a stable "clamp," ensuring the positional stability of the sheet during the cooling process, thereby guaranteeing the uniformity and consistency of the cooling effect. Furthermore, the pressure roller 9 can be adjusted appropriately according to the thickness of the sheet to adapt to the production needs of PVC sheets of different specifications, improving the versatility and flexibility of the equipment.

[0036] After entering the cooling equipment, the PVC sheets undergo two distinct cooling methods: counter-current gradient cooling at the bottom and efficient atomization cooling at the top. These two methods work synergistically to address the root cause of uneven heat dissipation between the upper and lower surfaces, achieving uniform heat dissipation in three dimensions. This minimizes internal stress and warping deformation in the PVC sheets, making it particularly suitable for rigid, thick sheets such as SPC. Furthermore, the waste heat generated by the cooling system can be used to preheat raw materials in the production line, achieving closed-loop energy utilization and reducing overall energy consumption by more than 20% compared to traditional systems.

[0037] Those skilled in the art will understand that the above embodiments are exemplary and not restrictive. Different technical features appearing in different embodiments can be combined to achieve beneficial effects. Based on a study of the drawings, specification, and claims, those skilled in the art should be able to understand and implement other variations of the disclosed embodiments. In the claims, the term "comprising" does not exclude other means or steps; the indefinite article "a" does not exclude a plurality; the terms "first" and "second" are used to identify names and not to indicate any particular order. No reference numerals in the claims should be construed as limiting the scope of protection. The functionality of multiple parts appearing in the claims can be implemented by a single hardware or software module. The appearance of certain technical features in different dependent claims does not mean that these technical features cannot be combined to achieve beneficial effects.

Claims

1. A gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance, characterized in that, include: Fixed base (1); A cooling roller assembly (2) is disposed on the fixed base (1) and includes a plurality of cooling rollers (6) disposed along the length direction of the fixed base (1). The cooling rollers (6) are hollow structures and the plurality of cooling rollers (6) are connected in sequence. A cooling auxiliary unit (3) is fixedly installed above the cooling roller group (2) to provide cooling for the side of the PVC sheet away from the cooling roller group (2); Cooling water flows through the cooling roller group (2), and the flow direction of the cooling water is opposite to the movement direction of the PVC sheet.

2. The gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance as described in claim 1, characterized in that, The cooling roller assembly (2) includes a precooling zone (21), a main cooling zone (22) and a fine cooling zone (23) in sequence along the direction of movement. The precooling zone (21) is connected to the heat exchange unit (4), and the fine cooling zone (23) is connected to the cooling water unit (5). The cooling auxiliary unit (3) includes an atomizing cooling unit (31) and an air-cooling cooling unit (32). Either the atomizing cooling unit (31) or the air-cooling cooling unit (32) is fixedly disposed above any one of the precooling zone (21), the main cooling zone (22) and the fine cooling zone (23).

3. The gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance as described in claim 2, characterized in that, The atomizing cooling unit (31) is provided above the precooling zone (21) and the main cooling zone (22), and the air-cooling unit (32) is provided above the fine cooling zone (23).

4. The gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance as described in claim 3, characterized in that, The air-cooled unit (32) includes at least one air knife, and the atomizing cooling unit (31) includes at least one atomizing air knife. The lengths of the air knife and the atomizing air knife are not less than the length of the cooling roller (6).

5. The gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance as described in claim 4, characterized in that, The air knife and the atomizing air knife are inclinedly arranged above the cooling roller group (2), and the inclination angle of the air knife and the atomizing air knife is between 20° and 50°.

6. The gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance as described in claim 1, characterized in that, The cooling roller (6) has a compression section (7) and a conveying section (8) arranged sequentially at both ends. The diameter of the conveying section (8) is not greater than the diameter of the cooling roller (6), and the diameter of the compression section (7) is smaller than the diameter of the conveying section (8).

7. The gradient cooling device for PVC sheets based on multi-stage countercurrent and atomization assistance as described in claim 1, characterized in that, It also includes a pressure roller (9), which is disposed between the cooling roller group (2) and the cooling auxiliary unit (3), and the distance between the pressure roller (9) and the cooling roller group (2) is not less than the thickness of the PVC sheet.

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