Plastic pipe extrusion on-line ovality detection and correction method and device

Abstract

The invention discloses a plastic pipe extrusion on-line ovality detection and correction method and device, and belongs to the technical field of plastic pipe forming. Comprising the following steps: S1, pipe surface data measurement: driving a turntable to rotate around a pipe, and synchronously measuring distance and temperature through a displacement sensor and a temperature sensor on the turntable; s2, ellipticity calculation: calculating the real-time ellipticity and the distribution orientation of the pipe based on the distance data; s3, temperature partition calculation: calculating the average temperature and the temperature difference of each fan-shaped partition of the pipe based on the temperature data; and S4, ellipticity closed-loop regulation and control: associating the distribution orientation of the ellipticity with the temperature parameters of the corresponding subareas, and differentially adjusting the cooling parameters of the corresponding subareas on the setting machine so as to actively correct the ellipticity. According to the method, the ellipticity and the circumferential temperature are measured synchronously on line, and partition regulation and control are implemented based on'temperature-deformation 'association, so that closed-loop quality control from passive detection to active prevention is realized.

Description

Technical Field

[0001] This invention belongs to the field of plastic pipe forming technology, specifically relating to a method and device for online ellipticity detection and correction of extruded plastic pipes. Background Technology

[0002] During the extrusion production of plastic pipes, insufficient cooling rate or uneven circumferential cooling can easily lead to elliptic deformation of the pipe cross-section. This defect significantly reduces the dimensional accuracy and performance of the pipe.

[0003] Currently used ellipticity detection methods have the following main problems:

[0004] 1. Offline sampling inspection: Typically, after production is completed, a portion of the samples are inspected manually using calipers or offline measuring equipment. This method has a significant time lag, cannot achieve 100% inspection, and often results in a large number of defective products when quality problems are discovered, making it difficult to intervene in the production process in a timely manner.

[0005] 2. Contact measurement: This method uses mechanical probes or rollers to directly contact the surface of the pipe. This not only easily scratches the surface of soft pipes, but also causes the sensor to wear out easily, resulting in a decrease in measurement accuracy and making it difficult to adapt to high-speed continuous production conditions.

[0006] 3. Limited Functionality: Most existing detection methods only focus on ellipticity itself, failing to simultaneously detect the key process parameter that directly affects ellipticity formation—the circumferential temperature distribution of the pipe. Therefore, they cannot provide early warning or control from the perspective of the causes of pipe ellipticity and lack closed-loop feedback capability for the cooling process. Summary of the Invention

[0007] This invention addresses the aforementioned problems in the existing technology by proposing an online ellipticity detection and correction method and device for plastic pipe extrusion that can simultaneously detect the ellipticity and circumferential temperature of pipes in real time, non-contact, and from all directions, and has the capability of active ellipticity correction.

[0008] This invention can be achieved through the following technical solutions:

[0009] A method for online ellipticity detection and correction of extruded plastic pipes includes the following steps:

[0010] S1. Pipe Surface Data Measurement: A turntable is driven to rotate around the linearly conveyed pipe. Displacement sensors and temperature sensors mounted on the turntable measure the pipe surface data as the turntable rotates.

[0011] The displacement sensor measures the distance between itself and a specific point on the outer circumference of the pipe;

[0012] The temperature sensor measures the temperature of each zone on the outer circumference of the pipe.

[0013] S2. Ellipticity Calculation: Based on the distance data measured by the displacement sensor, calculate the real-time ellipticity of the pipe and its distribution orientation in the circumferential direction.

[0014] S3. Temperature Zone Calculation: Based on the temperature values ​​of each zone on the outer circumference of the pipe measured by the temperature sensor, calculate the average temperature and temperature difference of each zone.

[0015] S4. Ellipticity Closed-Loop Control: The control system correlates real-time ellipticity data and its distribution with the temperature parameters of each zone on the outer circumference of the pipe, and differentially adjusts the cooling parameters of the corresponding specific zones on the forming machine to actively correct the ellipticity of the pipe.

[0016] As a further improvement of the present invention, in step S1, as the turntable rotates, the displacement sensor continuously detects the distance between itself and the outer surface of the pipe.

[0017] As a further improvement of the present invention, in step S2, the distance parameters measured by the displacement sensor are fitted into an elliptic curve by the ellipticity calculation module, and the elliptic value is provided.

[0018] As a further improvement of the present invention, in step S1, the turntable rotates 360° for one measurement cycle. Within one measurement cycle, the turntable stops sequentially at multiple equally spaced detection points, and the temperature sensor performs temperature detection during each stop at a detection point.

[0019] As a further improvement of the present invention, the multiple detection points of the turntable divide the outer circumference of the pipe into N corresponding temperature measurement areas, and a single temperature sensor is used to detect the temperature of one temperature measurement area.

[0020] As a further improvement of the present invention, in step S3, the temperature parameters measured by the temperature sensor are reconstructed into a real-time temperature distribution map of the outer circumference of the pipe by the temperature calculation module, so as to calculate the average temperature and temperature difference of each temperature measurement area.

[0021] As a further improvement of the present invention, the cooling system of the stenter is provided with cooling units arranged one-to-one with the N temperature measuring areas. In step S4, the control system determines the temperature measuring area to which the ellipticity deviation belongs based on the distribution orientation of the deviation, and adjusts the cooling parameters of the cooling unit corresponding to the temperature measuring area.

[0022] As a further improvement of the present invention, in steps S2 and S3, when the calculated ellipticity data or temperature data exceeds the threshold, an automatic alarm is triggered.

[0023] A device for online ellipticity detection and correction of plastic pipe extrusion is also provided, employing the above-mentioned method for online ellipticity detection and correction of plastic pipe extrusion, including:

[0024] A frame, which is located at a subsequent station of the shaping machine;

[0025] A turntable, which is rotatably mounted on the frame, through which the tubing passes;

[0026] A displacement sensor is mounted on the turntable and positioned toward the center of the pipe; the displacement sensor is used to measure the distance between itself and the outer surface of the pipe.

[0027] A temperature sensor is mounted on the turntable and positioned toward the center of the pipe; the temperature sensor is used to measure the temperature of the outer surface of the pipe.

[0028] The data processing unit is connected to the displacement sensor and the temperature sensor, and is used to receive measurement data and calculate the ellipticity data of the pipe and the temperature data of each temperature measurement area.

[0029] The control system is connected to the data processing unit and the cooling system of the setting machine by signal connection. It is used to generate control commands and adjust the cooling parameters of the corresponding cooling unit of the setting machine based on the ellipticity data calculated by the data processing unit and the temperature data of the corresponding temperature measurement area.

[0030] As a further improvement of the present invention, an alarm module connected to the control system is also included.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. A fundamental transformation in pipe ellipticity control: By integrating rotary scanning and synchronous measurement technologies, online, real-time, and comprehensive monitoring of pipe ellipticity and its cause—circumferential temperature distribution—is achieved. Based on the causal relationship model of "temperature-deformation," zoned closed-loop control of the cooling system is implemented. This completely changes the traditional quality control model that relies on offline and delayed sampling inspections, and promotes production management to shift from "passive handling" of post-discovery and scrapping to "proactive prevention" of real-time intervention and correction during the production process, significantly improving the timeliness of quality control and product consistency.

[0033] 2. Achieving "precise targeting" for efficient process control, optimizing energy efficiency and quality: By establishing a one-to-one spatial mapping relationship between "temperature measurement areas" and "cooling units," the location of ellipticity deviation can be precisely located to specific pipe sections, and the cooling intensity of the corresponding sections can be adjusted independently and differentiatedly. This targeted control of "where it is overheated, it strengthens cooling" only intervenes in abnormal areas, thereby quickly correcting ellipticity while avoiding energy waste and internal stress accumulation caused by overall overcooling, achieving a balance between quality improvement and energy efficiency optimization.

[0034] 3. Intelligent control logic based on "causal relationship": The deformation result (ellipticity) is analyzed and controlled online and synchronously with its physical cause (circumferential temperature unevenness). This intelligent decision-making based on causal relationship enables the system not only to "diagnose" defects, but also to "trace the cause" and "prescribe the right medicine", intervening from the physical root of the defect and truly solving the fundamental problem of "inability to prevent ellipticity from the source" that has long existed in the industry.

[0035] 4. Comprehensive Improvement of System Measurement Accuracy, Operational Reliability, and Production Line Adaptability: The "rotation-stop" strategy optimizes sensor sampling conditions, improving data accuracy; an independent clamping mechanism provides a stable measurement benchmark, suppressing pipe vibration; non-contact measurement avoids product damage; and the transmission and adjustment mechanism design ensures high precision and high reliability. These design features work together to enable the entire system to operate stably, accurately, and without damage on high-speed, continuous production lines, and possesses excellent adaptability to different pipe diameters, ensuring the efficient implementation and long-term reliable application of the technical solution.

[0036] 5. Human-Machine Interaction and Feedback: The integrated touchscreen human-machine interface provides centralized visualization and recording of real-time ellipticity, temperature field distribution, historical trend curves, alarm information, etc. This not only provides intuitive monitoring and convenient interactive interface for on-site operations, lowering the threshold for use, but more importantly, it forms a complete process data flow and management closed loop. Through the accumulation and analysis of historical data, a solid data foundation can be provided for in-depth optimization of cooling process parameters, predictive maintenance, and improvement of the overall intelligent level of production, driving the production process to continuously move towards a data-driven, predictable, and optimizable advanced stage. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the online ellipticity detection and correction device for plastic pipe extrusion of the present invention;

[0038] Figure 2 This is the invention Figure 1 A structural diagram from another perspective;

[0039] Figure 3 This is the invention Figure 2 A magnified view of a portion of point A in the middle.

[0040] In the diagram, 100 is the frame; 110 is the turntable; 111 is the displacement sensor; 112 is the temperature sensor; 113 is the linear module; 120 is the drive motor; 121 is the transmission gear; 122 is the gear and bearing transmission pair; and 130 is the clamping wheel. Detailed Implementation

[0041] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical methods of the present invention. However, the present invention is not limited to these embodiments.

[0042] like Figures 1-3 As shown, the present invention provides a method for online ellipticity detection and correction of extruded plastic pipes, comprising the following steps:

[0043] S1. Pipe Surface Data Measurement: A drive turntable 110 rotates around the linearly conveyed pipe. Displacement sensor 111 and temperature sensor 112, mounted on the turntable 110, measure the pipe surface data as the turntable 110 rotates.

[0044] Displacement sensor 111 measures the distance between itself and a specific point on the outer circumference of the pipe;

[0045] Temperature sensor 112 measures the temperature of each zone on the outer circumference of the pipe;

[0046] S2. Ellipticity Calculation: Based on the distance data measured by displacement sensor 111, calculate the real-time ellipticity of the pipe and its distribution orientation in the circumferential direction.

[0047] S3. Temperature zone calculation: Based on the temperature values ​​of each zone on the outer circumference of the pipe measured by temperature sensor 112, calculate the average temperature and temperature difference of each zone.

[0048] S4. Ellipticity Closed-Loop Control: The control system correlates real-time ellipticity data and its distribution with the temperature parameters of each zone on the outer circumference of the pipe, and differentially adjusts the cooling parameters of the corresponding specific zones on the forming machine to actively correct the ellipticity of the pipe.

[0049] It should be noted that because plastic pipes are not completely cooled and shaped during the shaping stage, their shape is easily affected by thermal stress caused by uneven cooling, which can lead to deformation. High-temperature areas cool slowly and shrink later, while low-temperature areas cool quickly and shrink earlier. Under the influence of gravity, high-temperature areas will sink and collapse slightly, resulting in non-circular cross-sections. Therefore, the ellipticity is closely related to the circumferential temperature difference.

[0050] Existing technologies often focus only on ellipticity itself, without detecting the key process parameter that directly affects ellipticity formation—the circumferential temperature distribution of the pipe. Therefore, it is impossible to provide early warning or control from the perspective of the causes of pipe ellipticity, which is the core problem that this application aims to solve.

[0051] Based on this, the core principle of the correction method provided in this application lies in performing real-time correlation analysis between the geometric deformation (ellipticity) of the pipe and the thermal field distribution (circumferential temperature), and implementing precise zoned cooling control based on this correlation. Specifically:

[0052] In step S1, the rotating turntable 110 drives the displacement sensor 111 and the temperature sensor 112 to scan around the moving pipe in sync, realizing non-contact, full-circumference, and synchronous measurement of the outer circumference of the pipe, while avoiding damage to the pipe surface caused by traditional contact measurement.

[0053] In steps S2 and S3, the system extracts the ellipticity and orientation information of the pipe cross-section from the displacement data, and reconstructs the circumferential temperature distribution of the pipe from the temperature data.

[0054] In step S4, the control system dynamically adjusts the cooling intensity (such as cooling water flow, air volume, or spraying time) of the corresponding area on the shaping machine based on the orientation of the ellipticity deviation of the pipe and the temperature characteristics of the temperature measurement area. This strengthens the cooling on the high-temperature side and moderately weakens it on the low-temperature side, thereby balancing the circumferential shrinkage rate and ultimately achieving the ellipticity correction of the pipe.

[0055] This correction method has at least the following advantages compared to existing technologies:

[0056] 1. Real-time online detection and active correction of ellipticity: By synchronously acquiring the circumferential geometric deformation and temperature distribution data of the pipe, a "temperature-deformation" correlation model is established, realizing the transformation from "passive sampling inspection" to "active closed-loop control", which significantly improves the roundness of the pipe and the consistency of the product.

[0057] 2. Improve the precision and energy efficiency of the cooling process: Based on the ellipticity orientation and the temperature difference of the corresponding zones, the cooling parameters are adjusted in a differentiated manner, which can effectively suppress ellipticity defects and avoid energy waste and internal stress accumulation caused by over-cooling, thereby improving production quality and resource utilization.

[0058] Preferably, in step S1, as the turntable 110 rotates, the displacement sensor 111 continuously detects the distance between itself and the outer surface of the pipe, thereby acquiring continuous, high-density profile data of the pipe cross-section in a single rotation cycle, rather than being limited to discrete point measurements. This method significantly improves the resolution and accuracy of ellipticity calculation, providing a reliable basis for subsequent ellipticity calculation.

[0059] Preferably, in step S2, the ellipticity calculation module reconstructs the real-time cross-sectional shape of the pipe based on the distance parameters measured by the displacement sensor 111 using a geometric algorithm. According to the fitted elliptic curve, the values ​​of the major axis (Dmax) and minor axis (Dmin) of the pipe are calculated. Based on the formula ellipticity = (Dmax - Dmin) / nominal outer diameter x 100%, the real-time elliptic value is calculated, providing a high-precision data foundation for subsequent accurate judgment of the degree of deformation and implementation of closed-loop correction.

[0060] Preferably, in step S1, the turntable 110 rotates 360° for one measurement cycle. Within one measurement cycle, the turntable 110 stops sequentially at multiple equally spaced detection points, and the temperature sensor 112 performs temperature detection during each stop at a detection point.

[0061] This design employs an intermittent motion mode of "rotation-pause-sampling". At each preset equal-angle detection point (e.g., every 60°), a stable measurement window is provided for the temperature sensor 112. The pause eliminates the dynamic error that may be introduced by the relative movement between the sensor and the pipe, ensuring that the temperature reading is obtained under static conditions, which greatly improves the stability and reliability of single-point measurement data.

[0062] In addition, setting detection points at equal intervals means that the outer circumference of the pipe is uniformly sampled in space, avoiding uneven data density, providing a uniform and reliable data foundation for the subsequent reconstruction of the complete temperature field distribution, and ensuring no detection blind spots.

[0063] It should be noted that during the pause of the turntable 110, the pipe is always in a continuous and uniform linear motion. This makes the target of the displacement sensor 111 to measure a point at a fixed angle on the same cross-section of the pipe, avoiding the tangential relative motion caused by the rotation of the turntable 110. Therefore, it will not affect the continuous use of the displacement sensor 111. On the contrary, by using the pause window to perform multiple average samplings, the repeatability accuracy of the distance data at each detection point can be improved, making the basic data for ellipticity calculation more reliable.

[0064] The "point pause" of this turntable 110 is an actively designed measurement strategy. By sacrificing extremely short cycle time, it creates optimal sampling conditions for each of the two types of sensors (temperature sensor 112 requires stable thermal radiation, while displacement sensor 111 can perform high-precision static measurement). This achieves an overall measurement effect of 1+1>2 at the system level and is an ingenious design that ensures the detection accuracy and calibration effectiveness of the entire device.

[0065] Preferably, the multiple detection points of the turntable 110 divide the outer circumference of the pipe into N corresponding temperature measurement areas, and a single temperature sensor 112 is used to detect the temperature of one temperature measurement area.

[0066] In step S3, the temperature calculation module reconstructs the real-time temperature distribution map of the outer circumference of the pipe by using the temperature parameters measured by the temperature sensor 112 through a geometric algorithm, so as to calculate the average temperature and temperature difference of each temperature measurement area.

[0067] This design forms the physical basis for subsequent corresponding closed-loop control of the temperature measurement area on the pipe surface. It enables the discretization, digitization, and precise positioning monitoring of the circumferential temperature field of the pipe. It can not only obtain the overall temperature, but also pinpoint which specific temperature measurement area has an abnormal temperature. This transforms the vague problem of "uneven cooling" into a clear executable instruction of "the temperature of zone X is too high / too low".

[0068] This provides a foundation for subsequent direct correlation analysis between "temperature of a specific zone" and "ellipticity deviation in the same orientation," and is a key structural guarantee for ultimately achieving the core invention objective of "causal regulation, zone compensation, and proactive prevention of ellipticity from the source," effectively solving the fundamental defect of "inability to prevent from the source" pointed out in the background technology.

[0069] Furthermore, the cooling system of the stenter is equipped with cooling units arranged one-to-one with the N temperature measurement areas. In step S4, the control system determines the temperature measurement area to which the ellipticity deviation belongs based on the distribution orientation of the deviation, and adjusts the cooling parameters of the cooling unit corresponding to the temperature measurement area.

[0070] This design achieves a closed-loop execution of "proactive prevention" and "source control" of pipe ellipticity. The physical boundaries of each cooling unit of the shaping machine are strictly aligned with the N temperature measurement areas divided by the turntable 110, forming a rigid correspondence between "one temperature measurement area and one cooling unit". The control system has this mapping logic embedded in it. When it receives "ellipticity deviation orientation" data, it can immediately convert it into a specific temperature measurement area and adjust the cooling unit parameters (such as cooling water flow rate and wind speed) serving that area in a directional manner.

[0071] Overall, through the closed-loop architecture of "zonal detection-zonal control", "single detection" (measuring only ellipticity) is upgraded to "causal control" (simultaneously measuring ellipticity and temperature, and adjusting the causes accordingly), thus achieving a fundamental leap from "offline sampling and post-event detection" to "online full inspection and real-time prevention".

[0072] Meanwhile, its non-contact measurement and precise control characteristics completely avoid the damage caused by contact measurement. By providing local and timely compensation for the root cause of "uneven circumferential cooling of the pipe," it proactively stabilizes the molding process from the source, significantly improving the consistency of product quality and production efficiency, and solving the ultimate problem in the background technology of "the inability to prevent ellipticity from the source."

[0073] In addition, to improve the cooling effect of the stenter on the pipe and the cooling uniformity of the inner and outer walls, the cooling system of the stenter consists of a water cooling system and an air cooling system. The water cooling system is used to cool the outer wall of the pipe, and the cooling units of the water cooling system are arranged one-to-one with the temperature measurement area during temperature detection. The air cooling system is the central exhaust system for the inner wall of the pipe, ensuring the cooling uniformity of the inner and outer walls of the pipe.

[0074] Preferably, in steps S2 and S3, when the calculated ellipticity data or temperature data exceeds the threshold, an automatic alarm is triggered to provide operators with immediate and clear intervention instructions and to provide necessary production safety assurance.

[0075] In summary, the correction method provided by this invention, through innovative integration of rotational scanning, simultaneous shape and temperature measurement, causal correlation analysis, and precise zonal control, achieves online diagnosis and real-time compensation for the causes of ellipticity in plastic pipes (circumferential temperature unevenness). This transforms quality control from an offline, result-based, sampling-based "post-event discovery" mode to an online, causal-linked "in-process prevention and correction" mode. It not only significantly improves the roundness, dimensional consistency, and product qualification rate of the pipes but also achieves precise cooling processes and energy-efficient utilization by avoiding "one-size-fits-all" overcooling. Simultaneously, it completely eliminates surface damage caused by contact measurement, providing key technical support for the efficient, stable, and intelligent production of high-quality plastic pipes.

[0076] This invention also provides an online ellipticity detection and correction device for plastic pipe extrusion, employing the above-mentioned online ellipticity detection and correction method for plastic pipe extrusion, comprising:

[0077] The frame 100 is located at the post-forming station of the stenter (since the stenter is a standard feature on plastic pipe extrusion molding production lines, it is not shown in the figure).

[0078] Turntable 110 is rotatably mounted on frame 100, and tubing passes through the central through hole of turntable 110;

[0079] Displacement sensor 111 is mounted on turntable 110 and positioned toward the center of the pipe. Displacement sensor 111 is used to measure the distance between itself and the outer surface of the pipe.

[0080] Temperature sensor 112 is mounted on turntable 110 and positioned toward the center of the pipe. Temperature sensor 112 is used to measure the temperature of the outer surface of the pipe.

[0081] The data processing unit is connected to the displacement sensor 111 and the temperature sensor 112 to receive measurement data and calculate the ellipticity data of the pipe and the temperature data of each temperature measurement area.

[0082] The control system is connected to the data processing unit and the cooling system of the stenter. It is used to generate control commands and adjust the cooling parameters of the corresponding cooling unit of the stenter based on the ellipticity data calculated by the data processing unit and the temperature data of the corresponding temperature measurement area.

[0083] The alarm module is connected to the control system signals.

[0084] Preferably, a drive motor 120 is provided on the frame 100, and the drive motor 120 is connected to the turntable 110 through a transmission assembly, which includes:

[0085] The transmission gear 121 is mounted on the output shaft of the drive motor 120;

[0086] The gear bearing transmission pair 122 is connected to the transmission gear 121, and the turntable 110 is connected to the gear bearing transmission pair 122.

[0087] This transmission structure achieves smooth power transmission and precise speed ratio control through gear meshing, providing a stable rotational speed for the turntable 110. Its core gear bearing transmission pair 122 highly integrates power transmission and rotational support functions, which not only greatly simplifies the machine head structure and reduces cumulative assembly errors, but more importantly, provides the turntable 110 with a rotational reference that is highly rigid, has low resistance, and extremely high rotational accuracy. This ensures that the displacement and temperature sensors 112 mounted on the turntable 110 have stable motion trajectories and precise spatial positions during the scanning process.

[0088] This fundamentally lays a solid mechanical foundation for subsequent high-precision ellipticity calculations, temperature field reconstruction, and reliable orientation-temperature correlation analysis, and is the basic guarantee for the entire detection and calibration device to achieve reliable and accurate measurements.

[0089] Preferably, the displacement sensor 111 and the temperature sensor 112 are respectively mounted on the turntable 110 via the linear module 113, thereby adjusting the distance between the displacement sensor 111, the temperature sensor 112 and the outer surface of the pipe, which is suitable for measuring pipes of different diameters.

[0090] Preferably, at least one set of displacement sensors 111 is symmetrically arranged on the turntable 110. When the turntable 110 rotates, a set of displacement sensors 111 works synchronously, which can simultaneously measure the distance between two symmetrical points on the circumference of the pipe. Its core principle is to use spatial symmetry to improve the spatiotemporal efficiency of data acquisition and the inherent verification capability.

[0091] This design doubles (or multiplies) the number of data sampling points per rotation, greatly improving the density of contour data and the response speed of the detection system without increasing the rotation speed. This provides a richer and more timely data foundation for ellipticity calculation. Through hardware-level spatial optimization, this layout ensures high-frequency and high-reliability online ellipticity monitoring, enabling subsequent closed-loop control to make decisions based on more timely and reliable deformation information, thereby improving the overall performance and stability of the entire correction system.

[0092] Preferably, at least one temperature sensor 112 is provided on the turntable 110. When multiple temperature sensors 112 are provided, they are evenly distributed on the turntable 110 and staggered with the displacement sensor 111. This layout strategy achieves efficient, reliable and interference-free synchronous measurement through spatial optimization.

[0093] Furthermore, the uniform distribution of multiple temperature sensors 112 ensures that when the turntable 110 rotates, the temperature sensors 112 can perform balanced and blind-zone-free sampling of the circumference of the pipe, eliminating measurement blind zones and providing a basis for quickly reconstructing a uniform temperature field.

[0094] The number of temperature sensors 112 is equal to the number of cooling units in the cooling system of the stenter, and their positions are set one-to-one. This ensures that the temperature measurement area on the surface of the pipe detected by the temperature sensor 112 corresponds one-to-one with the cooling zone of the cooling system of the stenter. The two form a spatial correspondence, avoiding the problem of control lag or misalignment caused by the mismatch between the detection point and the cooling area.

[0095] It is precisely because the temperature measurement area detected by temperature sensor 112 corresponds one-to-one with the cooling zone of the stenter cooling system that real-time, in-situ, point-to-point compensation of "where it is overheated, cooling is strengthened" can be finally achieved. This solves the core process problem of "uneven circumferential cooling of the pipe" with the highest efficiency and reliability, and truly achieves real-time intervention and proactive prevention from the physical root cause of ellipticity formation.

[0096] Preferably, the side of the frame 100 is also provided with a clamping mechanism, which is located on the front and rear sides of the frame 100, respectively, along with the turntable 110. The clamping mechanism includes:

[0097] At least one pair of clamping wheels 130, the surface of which has an arc structure that matches the pipe, clamps the pipe by clamping it, and guides the straight conveying of the pipe. At the same time, since the contact surface shapes of the two match and rolling friction is formed between the clamping wheel 130 and the pipe, the straight conveying of the pipe is not affected.

[0098] The servo drive system receives signals from the control system and drives the clamping wheel 130 to move closer to or further away from the center of the pipe.

[0099] This design provides a stable radial reference for the traveling pipe through the active clamping of the clamping wheel 130, effectively suppressing vibration and drift. This is a prerequisite for obtaining high-precision deformation and temperature data. Furthermore, the servo drive system enables automatic, precise, and repeatable adjustment of the clamping distance, allowing a single mechanism to quickly adapt to pipes of different diameters, greatly improving the equipment's versatility and production changeover efficiency.

[0100] Most importantly, the design of the arc surface fit and rolling friction makes the clamping action play a guiding and stabilizing role while providing minimal resistance to the straight-line transport of the pipe and almost no additional traction load, perfectly balancing the dual needs of "stable measurement" and "continuous production".

[0101] In addition, the calibration device is equipped with a touch screen (not shown in the figure), which adds an integrated human-machine interface to the entire closed-loop calibration system. It is used to display real-time ellipticity, temperature values, historical trend graphs, and out-of-tolerance alarm information.

[0102] Equipped with a touchscreen, the calibration device's intelligence, ease of operation, and production process traceability are significantly enhanced. Its core benefits are:

[0103] First, it provides users with a centralized and visual monitoring window for the entire system status. Operators can easily grasp the real-time ellipticity of the pipe, circumferential temperature distribution, cooling system working status and alarm information without the need for other equipment, thus achieving intuitive and immediate perception of production quality.

[0104] Secondly, by displaying historical trend charts, it provides strong data support for process optimization and problem diagnosis. Engineers can review and analyze the occurrence and development of ellipticity or temperature anomalies, thereby accurately locating process defects.

[0105] Furthermore, it integrates multiple functions such as parameter setting, manual control, alarm confirmation, and report generation, concentrating scattered operations on one screen, greatly simplifying operation and reducing reliance on professional personnel;

[0106] Ultimately, this highly integrated and user-friendly interactive design enables advanced closed-loop calibration technology to be more efficiently and reliably accepted and applied on the production floor, thereby effectively transforming technological advantages into improvements in production quality and efficiency.

[0107] The technical means disclosed in this invention are not limited to those described above, but also include technical solutions composed of any combination of the above technical features. The above are specific embodiments of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

[0108] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0109] Furthermore, in this invention, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. The terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly specified. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0110] The technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0111] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A plastic pipe extrusion on-line ovality detection correction method, characterized by, The method comprises the following steps: S1, pipe surface data measurement: driving a rotating disc to rotate around the linearly conveyed pipe, and a displacement sensor and a temperature sensor arranged on the rotating disc measure pipe surface data during rotation of the rotating disc, wherein, the displacement sensor measures the distance between the displacement sensor and a specific point on the outer circumference of the pipe; the temperature sensor measures the temperature of each sub-zone of the outer circumference of the pipe; S2, ellipticity calculation: based on the distance data measured by the displacement sensor, the real-time ellipticity of the pipe and the distribution direction of the real-time ellipticity in the circumferential direction are calculated; S3, temperature sub-zone calculation: based on the temperature values of each sub-zone of the outer circumference of the pipe measured by the temperature sensor, the average temperature and the temperature difference of each sub-zone are calculated; S4, ellipticity closed-loop regulation: the control system associates the real-time ellipticity data and the distribution direction of the real-time ellipticity with the temperature parameters of each sub-zone of the outer circumference of the pipe, and differentially adjusts the cooling parameters of the corresponding specific sub-zone of the pipe on the sizing machine to actively correct the ellipticity of the pipe.

2. The method of claim 1, wherein the method further comprises: In step S1, the displacement sensor continuously detects the distance between the displacement sensor and the outer surface of the pipe as the rotating disc rotates.

3. The method of claim 1, wherein the method further comprises: In step S2, the distance parameters measured by the displacement sensor are fitted into an elliptical curve by an ellipticity calculation module, and an ellipticity value is provided.

4. The method of claim 1, wherein the method further comprises: In step S1, the rotating disc rotates 360° for one measurement period, and the rotating disc stops at multiple equidistant detection points in one measurement period, and the temperature sensor performs temperature detection during the stop at each detection point.

5. The method of claim 4, wherein the method further comprises: The multiple detection points of the rotating disc divide the outer circumference of the pipe into N corresponding temperature measurement sub-zones, and a single temperature sensor is used to detect the temperature of one temperature measurement sub-zone.

6. The method of claim 1, wherein the method further comprises: In step S3, the temperature parameters measured by the temperature sensor are reconstructed into a real-time temperature distribution map of the outer circumference of the pipe by a temperature calculation module to calculate the average temperature and the temperature difference of each temperature measurement sub-zone.

7. The method of claim 5, wherein the method further comprises: The cooling system of the sizing machine is provided with cooling units corresponding to the N temperature measurement sub-zones, and in step S4, the control system determines the temperature measurement sub-zone to which the ellipticity deviation belongs according to the distribution direction of the ellipticity deviation, and adjusts the cooling parameters of the cooling unit corresponding to the temperature measurement sub-zone.

8. The method of claim 1, wherein the method further comprises: In steps S2 and S3, when the calculated ellipticity data or temperature data exceeds a threshold value, an automatic alarm is triggered.

9. A plastic pipe extrusion on-line ovality detection and correction apparatus employing the plastic pipe extrusion on-line ovality detection and correction method as claimed in any one of claims 1 to 8, characterized by, The method comprises the following steps: a rack arranged at a subsequent station of the sizing machine; a rotating disc rotatably mounted on the rack, and a pipe passing through a central through hole of the rotating disc; a displacement sensor mounted on the rotating disc and arranged towards the center of the pipe, the displacement sensor being used to measure the distance between the displacement sensor and the outer surface of the pipe; a temperature sensor mounted on the rotating disc and arranged towards the center of the pipe, the temperature sensor being used to measure the temperature of the outer surface of the pipe; a data processing unit connected to the displacement sensor and the temperature sensor, the data processing unit being used to receive measurement data and calculate ellipticity data of the pipe and temperature data of each temperature measurement sub-zone. A control system is connected with the data processing unit and the cooling system of the setting machine, for generating control instructions and adjusting the cooling parameters of the corresponding cooling unit of the setting machine according to the ovality data calculated by the data processing unit and the temperature data of the corresponding temperature measuring partition.

10. The plastic pipe extrusion on-line ovality detection and correction device of claim 9, wherein, An alarm module connected with the control system is further included.

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