PVC pipe processing cooling forming device

Abstract

The application discloses a PVC pipe processing cooling forming device, which comprises a front sizing cooling unit, a multistage gradient spraying cooling unit and a terminal air cooling sizing unit, and the front sizing cooling unit, the multistage gradient spraying cooling unit and the terminal air cooling sizing unit are sequentially arranged along the pipe extrusion direction. The beneficial effect is that the sizing sleeve of the front sizing cooling unit is provided with a continuous spiral cooling flow channel, cooling water can uniformly and circularly flow along the spiral cooling flow channel, there is no problem of water flow short circuit and uneven distribution of straight-through flow channel, the circumferential temperature difference of the sizing sleeve can be controlled within 1 DEG C from the traditional 5-8 DEG C, the circumferential cooling rate of the pipe blank is completely consistent, which is helpful to eliminate the causes of uneven pipe diameter and ovality, meanwhile, the spiral cooling flow channel adopts a gradually changing pitch design with dense inlet and sparse outlet, which can match the thermodynamic characteristics of high inlet temperature and low outlet temperature of the pipe blank, and ensures the uniform axial temperature distribution of the sizing sleeve.

Description

Technical Field

[0001] This invention relates to the field of PVC pipe processing cooling equipment, and more specifically to a PVC pipe processing cooling and forming device. Background Technology

[0002] Polyvinyl chloride (PVC) plastic pipes, with their significant advantages such as corrosion resistance, light weight, low fluid resistance, low cost, and convenient installation, are widely used in many fields, including municipal water supply and drainage, building water supply and drainage, power and communication conduit, and agricultural irrigation. They represent the largest-volume and most widely used category of plastic pipes in my country. According to industry statistics, my country's annual total output of plastic pipes exceeds 18 million tons, with PVC pipes accounting for approximately 45%, playing an irreplaceable role in urban and rural infrastructure construction.

[0003] Extrusion molding is the core production process for PVC pipes. Molten PVC mixture is plasticized by an extruder and extruded from the die. At this point, the material temperature is approximately 180-190℃, in a highly elastic state. It must undergo a cooling and shaping process to gradually cool down to a glassy state in order to obtain stable geometric dimensions and meet the required mechanical properties. Because the thermal conductivity of PVC material is only 0.13-0.16 W / (m・K), much lower than that of metal materials, the heat conduction rate is slow. The uniformity, temperature control accuracy, and heat exchange efficiency of the cooling process directly determine the dimensional accuracy, internal stress level, and production line operating speed of the pipes, making it one of the core bottlenecks of the entire production line.

[0004] Currently, the mainstream PVC pipe cooling and forming equipment in the industry generally adopts the classic architecture of "vacuum sizing box + long cooling water tank": the molten pipe blank first enters the vacuum sizing box, where it is initially shaped by vacuum adsorption to adhere to the inner wall of the sizing sleeve. Then it enters a multi-stage cooling water tank, where the outer wall of the pipe is cooled by immersion or spraying until the pipe is completely solidified. This architecture has been used for decades and has a high degree of technological maturity; however, it still has certain shortcomings in actual production, specifically in the following aspects: First, the rapid cooling method results in high residual internal stress, leading to inherent defects in the mechanical properties of the pipe. Traditional cooling devices often use ambient temperature tap water or well water for direct cooling, typically at 15-25℃, creating a temperature difference exceeding 160℃ with the molten pipe blank at nearly 200℃. Related thermo-mechanical coupling simulation studies show that under conventional cooling conditions, the outer wall temperature of the pipe blank can drop abruptly from 175℃ to 65℃ within 300 milliseconds, instantly forming a hardened shell. Meanwhile, heat conduction within the pipe wall is slow, remaining in a molten or highly elastic state, resulting in a typical "hard outside, soft inside" temperature distribution. During subsequent internal cooling and contraction, the solidified surface layer constrains the pipe wall, generating significant residual internal stress. This residual internal stress drastically reduces the pipe's low-temperature impact performance and resistance to environmental stress cracking, making it prone to brittleness at low temperatures and stress cracking during long-term use. This is one of the core causes of failure in drop hammer impact tests within the industry. For large-diameter, thick-walled pipes, the greater the wall thickness, the more obvious the difference in cooling between the inside and outside, and the more prominent the internal stress problem becomes. Some companies have to add an extra annealing process to eliminate stress, which significantly lengthens the production cycle and increases production costs.

[0005] Secondly, the sizing structure suffers from poor cooling uniformity, making it difficult to meet high-standard requirements for pipe dimensional accuracy. Existing sizing sleeves often employ axially straight-through or simple annular water channels, resulting in uneven water flow distribution. This leads to a circumferential temperature difference of 5-8℃ in the sizing sleeve and inconsistent circumferential cooling rates in the pipe blank. This causes pipe diameter deviations and ellipticity defects from the shaping stage, defects that cannot be corrected in subsequent cooling processes. According to national standards such as GB / T10002.1-2023, the ellipticity of the pipe should not exceed 50% of the outer diameter tolerance, while the ellipticity of pipes produced by traditional processes is generally between 0.8% and 1%, failing to meet the high-precision requirements of high-end municipal engineering projects. Furthermore, the uneven axial temperature distribution of the sizing sleeve leads to insufficient cooling and pipe sticking to the mold in the inlet section where it contacts the high-temperature molten material, while over-cooling occurs in the outlet section due to the lower material temperature, further affecting shaping stability and surface quality.

[0006] Furthermore, the low efficiency of cooling the outer wall alone hinders production line capacity expansion. Due to the poor thermal conductivity of PVC material, traditional equipment relies solely on heat exchange in one direction along the outer wall of the pipe. The long path and high resistance of heat transfer from the inside of the pipe to the outside result in low cooling efficiency, becoming a core factor limiting production line speed increases. Industry test data shows that for conventional DN50-110mm PVC water supply pipes, the extrusion speed on traditional production lines is generally 4-8 m / min; for large-diameter pipes above DN160mm, the extrusion speed is only 1-3 m / min. To ensure complete pipe curing and shaping, the production line needs to be equipped with multiple cooling water tanks, with a total cooling length of 20-30 meters. This results in large equipment footprint, high infrastructure and equipment investment costs, and very limited capacity expansion potential, making it difficult to meet the efficiency requirements of large-scale production.

[0007] Finally, uneven distribution of cooling field leads to insufficient product quality stability. Traditional cooling water tanks rely primarily on natural convection, resulting in low heat exchange efficiency and a tendency for water temperature stratification. Temperature differences between the upper and lower sections of the tank can reach 3-5℃, and significant temperature differences exist between the inlet and outlet ends. This causes uneven circumferential and axial cooling rates in the pipes, ultimately leading to quality problems such as large wall thickness deviations and pipe bending and deformation. Furthermore, traditional open cooling water systems are greatly affected by ambient temperature. High water temperatures in summer result in insufficient cooling and pipe deformation, while low water temperatures in winter exacerbate internal stress problems. The performance of pipes produced in different seasons and batches fluctuates greatly, leading to unstable product qualification rates. Summary of the Invention

[0008] The purpose of this invention is to provide a PVC pipe processing and cooling forming apparatus to solve the above-mentioned problems, as detailed below.

[0009] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a PVC pipe processing cooling and forming device, including a pre-sizing cooling unit, a multi-stage gradient spray cooling unit and a terminal air-cooling forming unit, wherein the pre-sizing cooling unit, the multi-stage gradient spray cooling unit and the terminal air-cooling forming unit are sequentially arranged along the pipe extrusion direction, and a closed-loop circulating temperature-controlled water system is also provided. The pre-sizing cooling unit includes a sizing box and a sizing sleeve. The sizing sleeve is inserted and fixed into the sizing box from the inlet end along the pipe extrusion direction, and the end of the sizing sleeve is sealed to the sizing box. A continuous spiral cooling channel is opened on the outside of the sizing sleeve. Sizing inlet and outlet water pipes are respectively provided on the outside of the sizing sleeve, and the sizing inlet and outlet water pipes are connected to the spiral cooling channel. At the same time, the sizing inlet and outlet water pipes are connected to the closed-loop circulating temperature-controlled water system. The sizing box is equipped with a circumferential atomizing spray assembly at the outlet position of the sizing sleeve, so as to quickly form a uniform solidified surface layer on the pipe after it exits the sizing sleeve. The multi-stage gradient spray cooling unit includes a spray cooling box and partitions. Two partitions are vertically spaced and fixed inside the spray cooling box to divide it into three independent spaces. These three spaces are respectively configured as a high-temperature spray cooling tank, a medium-temperature spray cooling tank, and a low-temperature spray cooling tank arranged sequentially along the pipe extrusion direction. Spray return water pipes are installed at the bottom of each of the three spray cooling tanks. Spray cooling components are assembled within each of the three tanks. The spray return water pipes and the spray cooling components are connected to a closed-loop temperature-controlled water system to provide three-stage gradient cooling of the PVC pipe in high-temperature, medium-temperature, and low-temperature ranges. The terminal air-cooled shaping unit includes an air-cooled box and a water collection tank. The water collection tank is fixedly configured at the bottom of the air-cooled box, and the bottom of the water collection tank is fixedly connected to an air-cooled return water pipe. At the same time, the air-cooled return water pipe is connected to the closed-loop temperature-controlled water system. A spiral air knife assembly is fixedly configured inside the air-cooled box. The spiral air knife assembly is connected to dry ambient temperature air and the air outlet direction is spirally inclined along the circumference of the pipe to blow and dry the surface of the pipe without dead angles. The closed-loop temperature-controlled water system includes a water collection module, a filtration module, a plate heat exchange module, and a segmented temperature control output module. It is used to filter and temperature-control the recovered cooling water and then supply cooling water at the corresponding temperatures to the pre-diameter cooling unit and the multi-stage gradient spray cooling unit, respectively.

[0010] Preferably, the spiral cooling channel is a continuous spiral channel with a rectangular cross-section, and the pitch of the spiral cooling channel gradually decreases along the pipe extrusion direction, so that the cooling intensity of the inlet section of the sizing sleeve is higher than that of the outlet section.

[0011] Preferably, the circumferential atomizing spray assembly includes a diversion ring pipe and atomizing nozzles. The diversion ring pipe is coaxially fixed to the outside of the sizing box. Multiple atomizing nozzles are fixedly connected to the inner circumference of the diversion ring pipe along the radial direction. The inner ends of the atomizing nozzles all extend into the interior of the sizing box and are located outside the outlet of the sizing sleeve. An atomizing water inlet pipe is fixedly connected to the outside of the diversion ring pipe and is connected to the closed-loop temperature-controlled water system.

[0012] Preferably, at least 6 sets of atomizing nozzles are evenly arranged around the circumference of the sizing sleeve, and the spraying direction is towards the outer wall of the pipe on the outlet side of the sizing sleeve. The spray atomization particle size range of the atomizing nozzles is 50-100μm.

[0013] Preferably, the water temperature of the high-temperature spray cooling tank is controlled at 40-50℃, the water temperature of the medium-temperature spray cooling tank is controlled at 25-35℃, and the water temperature of the low-temperature spray cooling tank is controlled at 15-20℃. The spraying pressure of the high-temperature spray cooling tank, the medium-temperature spray cooling tank, and the low-temperature spray cooling tank corresponding to the spray cooling component increases progressively along the extrusion direction, with a pressure range of 0.15-0.35MPa.

[0014] Preferably, each of the spray cooling components includes an annular distribution box and a spray inlet pipe. The annular distribution box is fixed to the inner front wall of the high-temperature section spray cooling tank, the medium-temperature section spray cooling tank, and the low-temperature section spray cooling tank along the pipe extrusion direction. The top of each annular distribution box is fixedly connected to the spray inlet pipe, and the spray inlet pipe is connected to the closed-loop temperature-controlled water system. Multiple spray pipes are arranged parallel to each other along the pipe extrusion direction on the outside of each annular distribution box. The multiple spray pipes are an upper spray pipe, a lower spray pipe, a left spray pipe, and a right spray pipe. The bottom of each of the upper spray pipe, the lower spray pipe, the left spray pipe, and the right spray pipe is fixedly connected to multiple distribution pipes radially. The end of each distribution pipe is connected to a fan-shaped spray head, and the spray surface of the fan-shaped spray head covers the corresponding area of ​​the outer wall of the pipe.

[0015] Preferably, the inner walls of the high-temperature spray cooling tank, the medium-temperature spray cooling tank, and the low-temperature spray cooling tank are all fixedly provided with multiple turbulence baffles. The turbulence baffles are arranged alternately on both sides to make the cooling water form lateral turbulence and avoid water temperature stratification.

[0016] Preferably, the spiral air knife assembly includes an annular air cavity and an air outlet slit. The annular air cavity is coaxially sleeved on the outside of the extruded pipe, and the annular air cavity is fixed inside the air-cooled box by an air cavity bracket. A plurality of air outlet slits are evenly distributed on the inner circumferential surface of the annular air cavity, and the axis of the air outlet slit is inclined at an angle of 30-45° with the axis of the pipe to make the air flow spirally along the surface of the pipe.

[0017] Preferably, the closed-loop temperature-controlled water system is also equipped with a graded return water pipeline and multiple independent temperature-controlled branches. The graded return water pipeline collects return water from each section respectively. After the return water is heat-exchanged and temperature-regulated by the plate heat exchange module, it is transported to the cooling section with the corresponding temperature requirement through the multiple independent temperature-controlled branches.

[0018] Preferably, a sealing transition sleeve is fixedly configured between the pre-sizing cooling unit, the multi-stage gradient spray cooling unit, and the terminal air-cooling shaping unit, and the inner diameter of the sealing transition sleeve is slightly larger than the outer diameter of the pipe to reduce cooling water leakage.

[0019] The beneficial effects are as follows: 1. The present invention has a continuous spiral cooling channel in the sizing sleeve of the pre-sizing cooling unit. The cooling water can flow around the spiral cooling channel at a uniform speed in the circumference. There is no problem of water flow short circuit and uneven distribution in the straight channel. The circumferential cooling rate of the tube blank is completely consistent, which helps to eliminate the causes of uneven tube diameter and ellipticity. At the same time, the spiral cooling channel adopts a gradually changing pitch design with dense inlet and sparse outlet. The cooling intensity of the inlet section is higher, which can match the thermodynamic characteristics of high inlet temperature and low outlet temperature of the tube blank. This ensures that the axial temperature distribution of the sizing sleeve is uniform. It avoids the tube sticking defect caused by excessively high inlet temperature and the overcooling problem caused by excessively low outlet temperature. This helps to improve the stability of the sizing process. In addition, the sizing box is equipped with a circumferential atomizing spray assembly in the part located at the outlet of the sizing sleeve. With the help of the atomizing nozzle of the circumferential atomizing spray assembly, the tube can quickly form a uniform solidified surface after exiting the sizing sleeve. This helps to stably control the ellipticity and wall thickness deviation of the finished tube. 2. A multi-stage gradient spray cooling unit is installed after the pre-sizing cooling unit. The multi-stage gradient spray cooling unit includes a high-temperature spray cooling tank, a medium-temperature spray cooling tank, and a low-temperature spray cooling tank. Spray cooling components are combined in the high-temperature, medium-temperature, and low-temperature spray cooling tanks. In this way, the PVC pipe is cooled in three stages of gradient cooling: high temperature, medium temperature, and low temperature. The PVC pipe is cooled step by step through the high-temperature section (40-50℃), the medium-temperature section (25-35℃), and the low-temperature section (15-20℃). The maximum temperature difference in a single stage is narrowed from the traditional 160℃ or more to the 40-50℃ range. This ensures that the temperature gradient of the pipe wall along the wall thickness is significantly gentler, and the difference in cooling rate between the inner and outer layers is greatly reduced. This avoids the stress generation mechanism of internal shrinkage constrained by the surface layer under the traditional "hard outside, soft inside" structure, and helps to reduce the residual internal stress inside the pipe. 3. The multi-stage gradient spray cooling unit can achieve circumferential forced spraying with the help of spray cooling components. At the same time, the baffles of the high-temperature section spray cooling tank, the medium-temperature section spray cooling tank and the low-temperature section spray cooling tank can achieve turbulence in the tank. In this way, the circumferential forced spraying and the turbulence in the tank can form a double enhancement of external heat exchange, which helps to increase the heat exchange per unit time and accelerate the cooling and solidification speed of the pipe. Moreover, the spray pressure of the high-temperature section spray cooling tank, the medium-temperature section spray cooling tank and the low-temperature section spray cooling tank increases segment by segment along the extrusion direction, which matches the state of the gradual increase of the surface hardness of the pipe and helps to further improve the extrusion speed of the production line. 4. The multi-stage gradient spray cooling unit ensures circumferential cooling of the pipe without dead angles. At the same time, the baffle plate eliminates water temperature stratification, so that the water temperature deviation at any position in the high-temperature, medium-temperature and low-temperature spray cooling tanks is ≤1℃. This ensures that the circumferential and axial cooling rates of the pipe are highly consistent, which helps to avoid defects such as uneven wall thickness and pipe bending deformation. In addition, the closed-loop circulating temperature-controlled water system supplies water to the pre-sizing cooling unit and the multi-stage gradient spray cooling unit respectively. The water temperature of each section is independently controlled in a closed loop, which is not affected by the fluctuation of ambient temperature. This ensures that the cooling process parameters are stable and controllable throughout the process, avoiding pipe deformation caused by insufficient cooling in summer and increased internal stress caused by excessive cooling in winter, which helps to improve quality consistency. 5. The terminal air-cooled shaping unit is equipped with a spirally inclined spiral air knife assembly, and the airflow blows forward spirally along the surface of the pipe. This allows for thorough air drying of the pipe surface without dead angles, eliminating the need for an additional hot air drying process. This helps reduce equipment investment and drying energy consumption. At the same time, the ambient temperature airflow can further remove residual heat from the surface of the pipe while blowing away moisture, further reducing the outlet temperature of the pipe. This facilitates direct cutting, printing, and other subsequent processes after the pipe is discharged, shortening the production process. Moreover, the uniform blowing of the spiral airflow around the circumference of the pipe can also homogenize the circumferential temperature of the pipe, helping to reduce the final temperature difference and residual deformation. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is an overall schematic diagram of the present invention. Figure 1 ; Figure 2 This is an overall schematic diagram of the present invention. Figure 2 ; Figure 3 This is the present invention. Figure 1 External schematic diagram of the pre-diameter cooling unit; Figure 4 This is the present invention. Figure 1 Schematic diagram of the cross-section of the pre-sizing cooling unit; Figure 5 This is the present invention. Figure 1 External schematic diagram of the multi-stage gradient spray cooling unit; Figure 6 This is the present invention. Figure 1 Schematic diagram of the cross-section of a multi-stage gradient spray cooling unit; Figure 7 This is the present invention. Figure 1 External schematic diagram of the terminal air-cooled shaping unit; Figure 8 This is the present invention. Figure 1 Schematic diagram of the cross-section of the terminal air-cooled shaping unit; Figure 9 This is a structural block diagram of the closed-loop temperature-controlled water system of the present invention; Figure 10 This is the present invention. Figure 1 Front view diagram; Figure 11 This is the present invention. Figure 1 A top-down view.

[0022] The annotations in the attached figures are explained as follows: 1. Terminal air-cooled shaping unit; 101. Spiral air knife assembly; 1011. Air cavity support; 1012. Annular air cavity; 1013. Air cavity inlet pipe; 1014. Air outlet gap; 102. Air-cooled housing; 103. Water collection tank; 104. Air-cooled return water pipe; 2. Multi-stage gradient spray cooling unit; 201. Baffle; 202. Low-temperature section spray cooling tank; 203. Baffle; 204. Medium-temperature section spray cooling tank; 205. Spray cooling housing; 206. High-temperature section spray cooling tank; 207. Spray cooling assembly; 2071. Spray water inlet pipe; 2072. Upper spray pipe; 2073. Diverter pipe; 2074. Fan-shaped spray head; 2075. Annular diverter box 2076. Left spray pipe; 2077. Lower spray pipe; 2078. Right spray pipe; 208. Spray return water pipe; 3. Pre-sizing cooling unit; 301. Circumferential atomizing spray assembly; 3011. Atomizing water inlet pipe; 3012. Diverting ring pipe; 3013. Atomizing nozzle; 302. Sizing box; 303. Sizing inlet and outlet water pipes; 304. Sizing sleeve; 305. Sizing section return water pipe; 306. Spiral cooling channel; 4. Sealed transition sleeve; 5. Closed-loop circulating temperature-controlled water system; 501. Staged return water pipeline; 502. Water collection module; 503. Filter module; 504. Plate heat exchange module; 505. Segmented temperature control output module; 506. Multiple independent temperature control branches. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0024] See Figures 1-11As shown, the present invention provides a PVC pipe processing cooling and forming device, which is horizontally and coaxially arranged along the pipe extrusion direction. It includes a pre-sizing cooling unit 3, a multi-stage gradient spray cooling unit 2, and a terminal air-cooling shaping unit 1, which are connected end to end. In addition, a closed-loop circulating temperature-controlled water system 5 is also provided. After the molten PVC pipe blank is extruded from the extrusion die, it passes through the three units in sequence to complete precise sizing, gradient cooling and air drying shaping, and is finally output to subsequent processing steps such as printing and cutting.

[0025] 1. Pre-sizing cooling unit 3, for details please refer to Figures 1-4 As shown: The pre-sizing and cooling unit 3 includes a sizing box 302 and a sizing sleeve 304. The sizing sleeve 304 is inserted and fixed inside the sizing box 302 from the inlet end in the tube extrusion direction. The inlet end of the sizing sleeve 304 is sealed to the end face of the sizing box 302, so that the sizing sleeve 304 is coaxially suspended in the inner cavity of the sizing box 302.

[0026] The outer wall of the sizing sleeve 304 is provided with a continuous spiral cooling channel 306. The spiral cooling channel 306 is a continuous spiral channel with a rectangular cross-section, and the pitch of the spiral cooling channel 306 gradually decreases along the tube extrusion direction, making the channel distribution in the inlet section of the sizing sleeve 304 denser and the cooling intensity higher. This matches the thermodynamic characteristics of the tube blank having a high inlet temperature and a low outlet temperature, ensuring the axial temperature uniformity of the sizing sleeve 304. The sizing sleeve 304 is provided with sizing inlet and outlet water pipes 303 on its exterior. Both sets of pipes are connected to the beginning and end of the spiral cooling channel 306, and the sizing inlet and outlet water pipes 303 are connected to a closed-loop circulating temperature-controlled water system 5. The circulating system supplies constant-temperature cooling water, and the uniform heat exchange and cooling of the sizing sleeve 304 is achieved through the circulating water flow in the spiral cooling channel 306.

[0027] A circumferential atomizing spray assembly 301 is assembled at the outlet of the sizing sleeve 304 in the sizing box 302 to rapidly form a uniformly cured surface layer on the pipe after it exits the sizing sleeve 304. Specifically, the circumferential atomizing spray assembly 301 includes a diversion ring pipe 3012 and atomizing nozzles 3013. The diversion ring pipe 3012 is coaxially fixed to the outside of the sizing box 302. At least six sets of atomizing nozzles 3013 are uniformly fixed and connected radially around the inner circumference of the diversion ring pipe 3012. The inner ends of the atomizing nozzles 3013 all extend into the interior of the sizing box 302 and are arranged around the outside of the outlet of the sizing sleeve 304. The spray direction of the atomizing nozzles 3013 is all towards the outer wall of the pipe on the outlet side of the sizing sleeve 304. The spray atomization particle size is controlled at 50-100μm, which can form a soft and uniform water mist pre-cooling on the surface layer of the pipe that has just exited the sizing sleeve 304. The external connection of the diversion ring pipe 3012 is fixedly connected to the atomizing water inlet pipe 3011, which is connected to the closed-loop temperature-controlled water system 5 to provide a stable water source for atomizing spraying. The bottom of the sizing box 302 is provided with a sizing section return water pipe 305, through which the cooling water falling back from the spraying flows back to the closed-loop temperature-controlled water system 5.

[0028] II. Multi-stage gradient spray cooling unit 2, for details please refer to Figures 1-6 As shown: The multi-stage gradient spray cooling unit 2 includes a spray cooling box 205 and partitions 203. Two partitions 203 are vertically fixed inside the spray cooling box 205, dividing the inner cavity of the spray cooling box 205 into three independent sealed spaces, which are sequentially configured as a high-temperature spray cooling tank 206, a medium-temperature spray cooling tank 204, and a low-temperature spray cooling tank 202 along the pipe extrusion direction. It should be noted that the center of each partition 203 should have a pipe hole and be fitted with a wear-resistant bushing to allow the pipe to pass through smoothly while reducing water flow between sections.

[0029] The bottoms of the high-temperature spray cooling tank 206, the medium-temperature spray cooling tank 204, and the low-temperature spray cooling tank 202 are all equipped with spray return water pipes 208. Each tank contains a spray cooling assembly 207. The spray return water pipes 208 and the spray cooling assemblies 207 are connected to a closed-loop temperature-controlled water system 5. Through independent temperature-controlled water supply and graded return water, a three-stage gradient cooling system for the PVC pipes (high-temperature, medium-temperature, and low-temperature) is achieved. In this embodiment, the water temperature of the high-temperature spray cooling tank 206 is controlled at 40-50℃, the water temperature of the medium-temperature spray cooling tank 204 is controlled at 25-35℃, and the water temperature of the low-temperature spray cooling tank 202 is controlled at 15-20℃. The spray pressure of the spray cooling assemblies 207 corresponding to the three tank sections increases progressively along the extrusion direction, with a pressure range of 0.15-0.35 MPa, matching the gradually increasing surface hardness of the pipe.

[0030] Specifically, each spray cooling assembly 207 includes an annular distribution box 2075 and a spray water inlet pipe 2071. The high-temperature section spray cooling tank 206, the medium-temperature section spray cooling tank 204 and the low-temperature section spray cooling tank 202 are all fixed with an annular distribution box 2075 along the inner front wall of the pipe extrusion direction. The top of the annular distribution box 2075 is fixedly connected to the spray water inlet pipe 2071. The spray water inlet pipe 2071 extends upward through the spray cooling box body 205 and is connected to the closed-loop circulating temperature-controlled water system 5. On the side of the annular distribution box 2075 facing the pipe outlet, four spray pipes are arranged parallel to the pipe extrusion direction: upper spray pipe 2072, lower spray pipe 2077, left spray pipe 2076, and right spray pipe 2078. The four spray pipes are evenly distributed around the circumference of the pipe. Multiple distribution pipes 2073 are evenly fixed and connected to the pipe wall along the axial direction. The ends of the distribution pipes 2073 are all equipped with fan-shaped spray heads 2074, and the spray surfaces of the fan-shaped spray heads 2074 cover the corresponding area of ​​the outer wall of the pipe, so as to achieve full circumference spraying of the pipe without dead angles.

[0031] In addition, multiple baffles 201 are fixedly installed on the inner walls of the high-temperature spray cooling tank 206, the medium-temperature spray cooling tank 204, and the low-temperature spray cooling tank 202. The baffles 201 are arranged alternately on the inner walls of both sides of the tank. When the water in the tank flows through the alternate baffles, it is forced to form a transverse turbulence, which can effectively prevent the water temperature in the tank from stratifying and ensure that the water temperature in the tank is uniform.

[0032] III. Terminal air-cooled shaping unit 1, for details please refer to Figures 1-8 As shown: The terminal air-cooled shaping unit 1 includes an air-cooled housing 102 and a water collection tank 103. The bottom of the air-cooled housing 102 is fixedly equipped with the water collection tank 103. Preferably, the bottom of the water collection tank 103 has a conical opening structure. The bottom is fixedly connected to an air-cooled return water pipe 104. The air-cooled return water pipe 104 is connected to a closed-loop circulating temperature-controlled water system 5 for recycling the cooling water that has been blown off.

[0033] A spiral air knife assembly 101 is fixedly installed inside the air-cooled housing 102. The spiral air knife assembly 101 is connected to dry ambient temperature air, and the air outlet direction is spirally inclined along the circumference of the pipe, which is used to blow and dry the surface of the pipe without dead angles. Specifically, the spiral air knife assembly 101 includes an annular air cavity 1012 and air outlet slits 1014. The annular air cavity 1012 is coaxially sleeved on the outside of the extruded pipe, and the annular air cavity 1012 is fixedly installed inside the air-cooled housing 102 by an air cavity bracket 1011. Multiple air outlet slits 1014 are evenly opened on the inner circumference of the annular air cavity 1012, and the axis of the air outlet slits 1014 is inclined at an angle of 30-45° with the axis of the pipe. The spiral direction of all air outlet slits 1014 is consistent. After compressed air is introduced, a spiral forward airflow along the pipe surface can be formed, achieving full circumference cleaning without dead angles.

[0034] IV. Closed-loop circulating temperature-controlled water system 5, for details please refer to Figure 9 As shown: The closed-loop temperature-controlled water system 5 includes a water collection module 502, a filter module 503, a plate heat exchange module 504, and a segmented temperature control output module 505. The cooling water recovered from each unit flows into the water collection module 502 through pipelines. It first passes through the filter module 503 to remove impurities and suspended solids in the water, and then enters the plate heat exchange module 504 for cooling capacity distribution and temperature regulation. Finally, it supplies cooling water of the corresponding temperature to the front fixed-diameter cooling unit 3 and the multi-stage gradient spray cooling unit 2 through the segmented temperature control output module 505.

[0035] Furthermore, the closed-loop circulating temperature-controlled water system 5 is also equipped with a graded return water pipeline 501 and multiple independent temperature-controlled branches 506. The graded return water pipeline 501 collects return water from the high-temperature section, medium-temperature section, low-temperature section and the sizing unit respectively. After the return water of different temperatures is graded heat exchanged and temperature-regulated by the plate heat exchange module 504, it is accurately delivered to the cooling section with the corresponding temperature requirement through the multiple independent temperature-controlled branches 506, realizing the cascade utilization of cooling capacity and reducing cooling energy consumption.

[0036] V. For details on joint sealing, please refer to [link / reference]. Figures 1-11 As shown: The connection end faces between the pre-sizing cooling unit 3 and the multi-stage gradient spray cooling unit 2, and between the multi-stage gradient spray cooling unit 2 and the terminal air-cooled shaping unit 1, are all fixedly equipped with sealing transition sleeves 4. The sealing transition sleeves 4 are made of nitrile rubber, and their inner diameter is slightly larger than the outer diameter of the pipe. This not only does not hinder the smooth passage of the pipe, but also effectively reduces the leakage of cooling water and airflow, ensuring a clean production environment.

[0037] In practical applications, the above structure, with its continuous spiral cooling channel 306 in the sizing sleeve 304 of the pre-sizing cooling unit 3, allows cooling water to flow uniformly around the spiral cooling channel 306. This eliminates the problems of short-circuiting and uneven distribution of water flow in straight channels, ensuring a completely consistent circumferential cooling rate for the tube blank. This helps eliminate pipe diameter inconsistencies and ellipticity. Furthermore, the spiral cooling channel 306 employs a gradually changing pitch design with a denser inlet and a sparser outlet, resulting in higher cooling intensity at the inlet. This matches the thermodynamic characteristics of the high inlet temperature and low outlet temperature of the tube blank, ensuring uniform axial temperature distribution in the sizing sleeve 304. This avoids both the tube sticking defect caused by excessively high inlet temperature and overcooling caused by excessively low outlet temperature, thus contributing to... To improve the stability of the sizing process, the sizing box 302 is equipped with a circumferential atomizing spray assembly 301 located at the outlet of the sizing sleeve 304. The atomizing nozzles 3013 of the circumferential atomizing spray assembly 301 enable the pipe to quickly form a uniformly cured surface layer after exiting the sizing sleeve 304, which helps to stably control the ovality and wall thickness deviation of the finished pipe. Furthermore, a multi-stage gradient spray cooling unit 2 is subsequently installed after the pre-sizing cooling unit 3. This multi-stage gradient spray cooling unit 2 includes a high-temperature spray cooling tank 206, a medium-temperature spray cooling tank 204, and a low-temperature spray cooling tank 202. Each of these three sections is equipped with... The spray cooling assembly 207 uses a three-stage gradient cooling method—high-temperature, medium-temperature, and low-temperature—to cool the PVC pipe through a high-temperature spray cooling tank 206, a medium-temperature spray cooling tank 204, and a low-temperature spray cooling tank 202. This allows the PVC pipe to be gradually cooled through a 40-50℃ high-temperature section, a 25-35℃ medium-temperature section, and a 15-20℃ low-temperature section. The maximum temperature difference in a single section is narrowed from the traditional 160℃ or more to the 40-50℃ range. This ensures a significantly gentler gradient in the pipe wall temperature along the wall thickness direction and a substantial reduction in the cooling rate difference between the inner and outer layers. This avoids the stress generation mechanism caused by the surface constraint on internal shrinkage under the traditional "hard outside, soft inside" structure, which helps reduce residual internal stress in the pipe. Furthermore, the multi-stage gradient spray cooling unit 2, with the help of the spray cooling assembly... Component 207 enables circumferential forced spraying. Simultaneously, the baffles 201 in the high-temperature spray cooling tank 206, medium-temperature spray cooling tank 204, and low-temperature spray cooling tank 202 create turbulence within the tanks. This combination of circumferential forced spraying and turbulence within the tanks creates a dual-enhanced external heat exchange, increasing the heat exchange per unit time and accelerating the cooling and solidification speed of the pipe. Furthermore, the spray pressure corresponding to the high-temperature spray cooling tank 206, medium-temperature spray cooling tank 204, and low-temperature spray cooling tank 202 gradually increases along the extrusion direction, matching the gradually increasing surface hardness of the pipe. This further helps to increase the extrusion speed of the production line. Moreover, the circumferential full-circumferential spraying by the multi-stage gradient spray cooling unit 2 ensures that there are no dead angles in the circumferential cooling of the pipe.Simultaneously, the baffle 201 eliminates water temperature stratification, ensuring that the water temperature deviation at any point within the high-temperature spray cooling tank 206, the medium-temperature spray cooling tank 204, and the low-temperature spray cooling tank 202 is ≤1℃. This guarantees a high degree of consistency in the circumferential and axial cooling rates of the pipe, helping to avoid defects such as uneven wall thickness and pipe bending deformation. Furthermore, the closed-loop circulating temperature-controlled water system 5 supplies water to the pre-sizing cooling unit 3 and the multi-stage gradient spray cooling unit 2, with independent closed-loop temperature control for each section, unaffected by ambient temperature fluctuations. This ensures stable and controllable cooling process parameters throughout the process, preventing pipe deformation due to insufficient cooling in summer and excessive cooling in winter. The increased internal stress helps improve quality consistency. Furthermore, the terminal air-cooled shaping unit 1 is equipped with a spirally inclined spiral air knife assembly 101, and the airflow spirally sweeps forward along the pipe surface, enabling thorough cleaning and drying of the pipe surface without dead angles. This eliminates the need for an additional hot air drying process, reducing equipment investment and drying energy consumption. Simultaneously, the ambient temperature airflow further removes residual heat from the pipe surface while sweeping away moisture, further lowering the pipe's outlet temperature. This facilitates direct cutting, printing, and other subsequent processes after discharge, shortening the production process. Moreover, the uniform circumferential sweeping of the spiral airflow also homogenizes the circumferential temperature of the pipe, helping to reduce the final temperature difference and residual deformation.

[0038] See Figures 1-11 As shown, the working process of this solution is as follows: After the molten PVC pipe blank is extruded from the extrusion die, it first enters the sizing sleeve 304 of the pre-sizing cooling unit 3. The sizing sleeve 304 exchanges heat evenly with circulating water in the spiral cooling channel 306, so that the surface of the pipe blank is initially solidified and a precise outer diameter is obtained. After the pipe blank exits the sizing sleeve 304, the circumferentially arranged atomizing nozzles 3013 spray fine water mist for gentle pre-cooling, quickly forming a uniform solidified surface layer, providing strength support for subsequent high-pressure spraying.

[0039] Subsequently, the pipes sequentially enter the high-temperature section, medium-temperature section, and low-temperature section spray cooling tank 202 of the multi-stage gradient spray cooling unit 2. Under the action of gradually decreasing water temperature and gradually increasing spray pressure, the temperature drops smoothly, resulting in a small temperature difference between the inside and outside of the pipe wall, uniform cooling, and low residual internal stress. The turbulence baffle 201 in the tank forces water turbulence, eliminates water temperature stratification, and ensures circumferential cooling consistency.

[0040] After the main cooling is completed, the pipe enters the terminal air-cooled shaping unit 1. The ambient temperature airflow sprayed by the spiral air knife assembly 101 blows along the surface of the pipe in a spiral motion, completely removing the water droplets attached to the surface and taking away the residual heat on the surface, thus achieving final cooling. The cooling water blown down flows into the water collection tank 103 at the bottom and flows back to the closed-loop temperature-controlled water system 5.

[0041] Throughout the cooling process, the closed-loop temperature-controlled water system collects, filters, and adjusts the temperature of the return water in each section before circulating it back to the system, realizing the tiered utilization of cooling capacity and the closed-loop reuse of water resources, thus significantly reducing operating energy consumption.

[0042] It should also be noted that in this invention, the above-mentioned effects are not a simple summation of the effects of individual unit technical features, but rather a significant synergistic effect of 1+1+1>3 generated through systematic process reconstruction. This fundamentally solves the inherent industry contradiction in the background technology that "single-point optimization cannot simultaneously take into account efficiency and internal stress," and its core is reflected in three dimensions: First, it resolves the inherent contradiction and enhances efficiency: In traditional processes, cooling rate and internal stress control are inherently contradictory – increasing the cooling rate inevitably exacerbates the quenching effect and increases internal stress; reducing internal stress requires slowing down the cooling rate and sacrificing production capacity. This invention combines the gradient temperature control of the multi-stage gradient spray cooling unit 2 to smooth the temperature difference with the enhanced heat exchange of the pre-sizing cooling unit 3 to improve efficiency. Gradient temperature control manages internal stress generation, while forced turbulent heat exchange compensates for the efficiency loss caused by gradient cooling. These two elements support each other: gradient cooling ensures that even with increased heat exchange intensity, the temperature difference between the inside and outside of the pipe wall does not become uncontrollable; uniform spraying and turbulence ensure uniform application of gradient temperature control, preventing localized quenching. Ultimately, it simultaneously improves cooling efficiency and reduces residual internal stress, breaking the performance seesaw of traditional processes.

[0043] Secondly, the process connection is improved: the pre-sizing and cooling unit 3 completes the precise shaping and pre-cooling of the surface layer, providing sufficient surface strength support for the subsequent high-pressure spraying and avoiding damage to the softened tube blank by high-pressure water; after the multi-stage gradient spray cooling unit 2 completes the main cooling, the tube temperature drops to near room temperature, and the terminal air-cooled shaping unit 1 undertakes the final cooling and dewatering functions. The parameters of the three processes are matched and seamlessly connected to form a complete continuous process of "shaping-main cooling-final cooling and dewatering". Compared with the traditional decentralized independent arrangement of sizing boxes, cooling water tanks and drying boxes, this device has a higher degree of integration, stronger production continuity, and the overall operating efficiency of the production line can be further improved.

[0044] Thirdly, energy reuse enhances efficiency: The closed-loop temperature-controlled water system 5 simultaneously supplies water to both the pre-sizing cooling unit 3 and the multi-stage gradient spray cooling unit 2. The condensate recovered from the terminal air-cooled shaping unit 1 is also incorporated into the closed-loop temperature-controlled water system 5, achieving closed-loop reuse of water resources throughout the system. Simultaneously, cooling capacity is allocated in stages according to water temperature levels, avoiding energy waste. Furthermore, by utilizing the terminal air-cooling function of the terminal air-cooled shaping unit 1 to replace hot air drying, the energy consumption of the dehydration process is transformed from "heating energy consumption" to "air supply energy consumption," resulting in a significant reduction in energy consumption. The synergistic effect of these multi-dimensional energy-saving measures reduces overall operating energy consumption by more than 30% compared to traditional solutions, achieving a win-win situation of increased production capacity and reduced energy consumption.

[0045] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A PVC pipe processing cooling and forming device, characterized in that: It includes a pre-sizing cooling unit (3), a multi-stage gradient spray cooling unit (2) and a terminal air-cooling shaping unit (1), and the pre-sizing cooling unit (3), the multi-stage gradient spray cooling unit (2) and the terminal air-cooling shaping unit (1) are sequentially arranged along the pipe extrusion direction, and a closed-loop circulating temperature-controlled water system (5) is also provided. The pre-sizing cooling unit (3) includes a sizing box (302) and a sizing sleeve (304). The sizing sleeve (304) is inserted and fixed into the sizing box (302) from the inlet end along the pipe extrusion direction, and the end of the sizing sleeve (304) is sealed to the sizing box (302). A continuous spiral cooling channel (306) is provided on the outside of the sizing sleeve (304), and sizing inlet and outlet water pipes (306) are respectively provided on the outside of the sizing sleeve (304). 3), and the sizing inlet and outlet water pipe (303) is connected to the spiral cooling channel (306), and the sizing inlet and outlet water pipe (303) is connected to the closed-loop circulating temperature control water system (5). The sizing box (302) is equipped with a circumferential atomizing spray assembly (301) at the outlet position of the sizing sleeve (304) so ​​that the pipe can quickly form a uniform solidified surface after exiting the sizing sleeve (304) by means of the circumferential atomizing spray assembly (301). The multi-stage gradient spray cooling unit (2) includes a spray cooling box (205) and partitions (203). Two partitions (203) are vertically spaced inside the spray cooling box (205) to divide the spray cooling box (205) into three independent spaces. The three independent spaces are respectively configured as a high-temperature spray cooling tank (206), a medium-temperature spray cooling tank (204), and a low-temperature spray cooling tank (202) arranged sequentially along the pipe extrusion direction. At the same time, the high-temperature spray cooling tank (206), the medium-temperature spray cooling tank (204), and the low-temperature spray cooling tank (202) are all connected in sequence. The bottom of the high-temperature spray cooling tank (204) and the low-temperature spray cooling tank (202) are both provided with spray return water pipes (208). The high-temperature spray cooling tank (206), the medium-temperature spray cooling tank (204) and the low-temperature spray cooling tank (202) are all equipped with spray cooling components (207). The spray return water pipes (208) and the spray cooling components (207) are respectively connected to the closed-loop temperature control water system (5) to perform three-stage gradient cooling of the PVC pipe in the high-temperature-medium-low-temperature range. The terminal air-cooled shaping unit (1) includes an air-cooled box (102) and a water collection tank (103). The water collection tank (103) is fixedly arranged at the bottom of the air-cooled box (102), and the bottom of the water collection tank (103) is fixedly connected to an air-cooled return water pipe (104). At the same time, the air-cooled return water pipe (104) is connected to the closed-loop temperature-controlled water system (5). A spiral air knife assembly (101) is fixedly arranged inside the air-cooled box (102). The spiral air knife assembly (101) is connected to dry ambient temperature air and the air outlet direction is spirally inclined along the circumference of the pipe to blow and dry the surface of the pipe without dead angles. The closed-loop temperature-controlled water system (5) includes a water collection module (502), a filtration module (503), a plate heat exchange module (504), and a segmented temperature control output module (505), which are used to filter and temperature control the recovered cooling water and supply cooling water of corresponding temperatures to the pre-dip sizing cooling unit (3) and the multi-stage gradient spray cooling unit (2).

2. The PVC pipe processing cooling and forming device according to claim 1, characterized in that: The spiral cooling channel (306) is a continuous spiral channel with a rectangular cross section, and the pitch of the spiral cooling channel (306) gradually decreases along the pipe extrusion direction, so that the cooling intensity of the inlet section of the sizing sleeve (304) is higher than that of the outlet section.

3. The PVC pipe processing cooling and forming device according to claim 1, characterized in that: The circumferential atomizing spray assembly (301) includes a diversion ring pipe (3012) and an atomizing nozzle (3013). The diversion ring pipe (3012) is coaxially fixed on the outside of the sizing box (302). Multiple atomizing nozzles (3013) are fixedly connected to the inner circumference of the diversion ring pipe (3012) radially. The inner ends of the atomizing nozzles (3013) all extend into the inside of the sizing box (302) and are located outside the outlet of the sizing sleeve (304). An atomizing water inlet pipe (3011) is fixedly connected to the outside of the diversion ring pipe (3012), and the atomizing water inlet pipe (3011) is connected to the closed-loop temperature-controlled water system (5).

4. The PVC pipe processing cooling and forming device according to claim 3, characterized in that: At least 6 sets of atomizing nozzles (3013) are evenly arranged around the circumference of the sizing sleeve (304) and the spraying direction is towards the outer wall of the pipe on the outlet side of the sizing sleeve (304). The spray atomization particle size range of the atomizing nozzles (3013) is 50-100μm.

5. The PVC pipe processing cooling and forming device according to claim 1, characterized in that: The water temperature of the high-temperature spray cooling tank (206) is controlled at 40-50℃, the water temperature of the medium-temperature spray cooling tank (204) is controlled at 25-35℃, and the water temperature of the low-temperature spray cooling tank (202) is controlled at 15-20℃. The spray pressure of the high-temperature spray cooling tank (206), the medium-temperature spray cooling tank (204), and the low-temperature spray cooling tank (202) corresponding to the spray cooling component (207) increases gradually along the extrusion direction, with a pressure range of 0.15-0.35MPa.

6. The PVC pipe processing cooling and forming device according to claim 1, characterized in that: Each of the spray cooling components (207) includes an annular distribution box (2075) and a spray inlet pipe (2071). The annular distribution box (2075) is fixed to the inner front wall of the high-temperature section spray cooling tank (206), the medium-temperature section spray cooling tank (204), and the low-temperature section spray cooling tank (202) along the pipe extrusion direction. The top of the annular distribution box (2075) is fixedly connected to the spray inlet pipe (2071), and the spray inlet pipe (2071) is connected to the closed-loop circulating temperature-controlled water system (5). The outer side of the annular distribution box (2075) is fixed along the pipe extrusion direction. Multiple spray pipes are arranged in parallel in the outward direction, and the multiple spray pipes are an upper spray pipe (2072), a lower spray pipe (2077), a left spray pipe (2076), and a right spray pipe (2078). The bottom of the upper spray pipe (2072), the lower spray pipe (2077), the left spray pipe (2076), and the right spray pipe (2078) are all fixedly connected to multiple diversion pipes (2073) in the radial direction, and the ends of the diversion pipes (2073) are all connected to fan-shaped spray heads (2074). At the same time, the spray surface of the fan-shaped spray heads (2074) covers the corresponding area of ​​the outer wall of the pipe.

7. The PVC pipe processing cooling and forming device according to claim 1, characterized in that: The inner walls of the high-temperature spray cooling tank (206), the medium-temperature spray cooling tank (204), and the low-temperature spray cooling tank (202) are all fixedly provided with multiple turbulence baffles (201). The turbulence baffles (201) are arranged alternately on both sides to make the cooling water form lateral turbulence and avoid water temperature stratification.

8. The PVC pipe processing cooling and forming device according to claim 1, characterized in that: The spiral air knife assembly (101) includes an annular air cavity (1012) and an air outlet slit (1014). The annular air cavity (1012) is coaxially sleeved on the outside of the extruded pipe, and the annular air cavity (1012) is fixed inside the air-cooled box (102) by an air cavity bracket (1011). A plurality of air outlet slits (1014) are evenly distributed on the inner circumferential surface of the annular air cavity (1012), and the axis of the air outlet slit (1014) is inclined at an angle of 30-45° with the axis of the pipe, so that the air flows spirally along the surface of the pipe.

9. The PVC pipe processing cooling and forming device according to claim 1, characterized in that: The closed-loop temperature-controlled water system (5) is also equipped with a graded return water pipeline (501) and multiple independent temperature control branches (506). The graded return water pipeline (501) collects the return water of each section respectively. After the return water is heated and regulated by the plate heat exchange module (504), it is transported to the cooling section with the corresponding temperature requirement through the multiple independent temperature control branches (506).

10. The PVC pipe processing cooling and forming device according to claim 1, characterized in that: A sealing transition sleeve (4) is fixedly configured between the pre-sizing cooling unit (3), the multi-stage gradient spray cooling unit (2), and the terminal air-cooled shaping unit (1), and the inner diameter of the sealing transition sleeve (4) is slightly larger than the outer diameter of the pipe to reduce the leakage of cooling water.

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