Method and apparatus for determining dimensions of mandrel, device, medium, and product

Abstract

The present application provides a method and apparatus for determining the dimensions of a mandrel, a device, a medium, and a product. The method comprises: establishing a cross-sectional model of a pipe on the basis of dimensions of an initial mold, performing mesh discretization of the cross-sectional model of the pipe, then assigning a shear relaxation modulus function to each mesh cell, and obtaining a viscoelastic model of the pipe; on the basis of an actual stress and an actual temperature field, performing deformation simulation on the viscoelastic model, and obtaining a deformation model of the pipe; and obtaining optimized mandrel dimensions on the basis of a comparison result of the cross-sectional model and the deformation model. In the solution of the present application, the cross-sectional model is established on the basis of dimension requirements of the pipe, the viscoelastic model can characterize the relaxation modulus of the pipe under shear stress, and the environmental conditions of the pipe during a cooling and solidification stage can be extracted using the actual stress and the actual temperature field, thereby improving the accuracy of deformation simulation and mandrel dimension adjustment and accordingly enhancing the anti-sag performance of the pipe.

Description

Methods, apparatus, equipment, media, and products for determining the dimensions of core molds

[0001] Cross-references to related applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411555669.7, filed on November 4, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of pipeline manufacturing technology, and in particular to a method, apparatus, equipment, medium, and product for determining the size of a mandrel. Background Technology

[0004] In the pipe extrusion molding process, the material is melted at high temperature and extruded through a die to form a pipe of the required size. During the cooling stage after the pipe is extruded from the die, gravity causes sag in the vertical direction, affecting the consistency and reliability of the pipe.

[0005] Currently, one approach to preventing pipe sagging is to modify the pipe material formula, such as by adding reinforcing materials like glass fiber, to improve the pipe's mechanical strength and rigidity, thereby reducing material deformation. However, reinforcing materials increase pipe production costs, processing difficulty, and equipment wear. Another approach is to adjust the position of the mandrel in the mold to reduce sagging, but this method has limited effectiveness. Therefore, the current challenge is to improve the anti-sagging performance of pipes. Summary of the Invention

[0006] This application provides a method, apparatus, equipment, medium, and product for determining the size of a mandrel, in order to improve the anti-sagging performance of pipelines.

[0007] On one hand, this application provides a method for determining the size of a mandrel, which is used as a mold for pipe fabrication. The method includes: determining the size of an initial mold according to the size requirements of the pipe; wherein the initial mold includes a mandrel and a die; establishing a cross-sectional model of the pipe according to the size of the initial mold, and meshing the cross-sectional model of the pipe to obtain multiple mesh elements; assigning a shear relaxation modulus function to each mesh element to obtain a viscoelastic model of the pipe; obtaining the actual stress and actual temperature field of the pipe fabricated by extrusion molding using the initial mold during the cooling and solidification stage; performing deformation simulation on the viscoelastic model based on the actual stress and actual temperature field to obtain a deformation model of the pipe; wherein the actual temperature field characterizes the temperature change in different regions of the pipe after extrusion molding; and adjusting the size of the mandrel in the initial mold according to the comparison results of the cross-sectional model and the deformation model to obtain an optimized mandrel size.

[0008] In one possible implementation, the method further includes: obtaining fixed shear relaxation moduli at different temperatures; and establishing a shear relaxation modulus function by summing the fixed shear relaxation moduli at different temperatures and at least one temperature-dependent dynamic shear relaxation modulus; the shear relaxation modulus function is:

[0009] Among them, G e To fix the shear relaxation modulus, G i (t) represents the i-th dynamic shear relaxation modulus, N is the number of dynamic shear relaxation moduli, and t is the cooling time of the pipe; the dynamic shear relaxation modulus is:

[0010] Among them, g i τ is a fixed component of the i-th dynamic shear relaxation modulus. i Let be the relaxation time under the i-th dynamic shear relaxation modulus.

[0011] In one possible implementation, a shear relaxation modulus function is established by summing a fixed shear relaxation modulus at different temperatures and at least one temperature-dependent dynamic shear relaxation modulus. This includes: obtaining the shear relaxation modulus values ​​of the material to which the pipe belongs at different temperatures; using an exponential function with temperature as the independent variable as the fixed component of the shear relaxation modulus, and a quadratic function with temperature as the independent variable as the relaxation time, and determining the initial values ​​of the fixed shear relaxation modulus and the number of dynamic shear relaxation moduli to establish an initial shear relaxation modulus function; establishing a loss based on the shear relaxation modulus values ​​and the output value of the initial shear relaxation modulus function; if the loss value is less than a threshold, determining the shear relaxation modulus function; if the loss value is not less than the threshold, adjusting the coefficients in the exponential and quadratic functions, and the number of fixed and dynamic shear relaxation moduli, until the loss value is less than the threshold.

[0012] In one possible implementation, the initial mold has a circular cross-section. Based on the comparison between the cross-sectional model and the deformation model, the dimensions of the core mold in the initial mold are adjusted, including: detecting the relationship between the pipe thickness corresponding to the cross-sectional model and the pipe thickness corresponding to the deformation model in a preset direction outward from the center of the cross-sectional model; if the pipe thickness corresponding to the cross-sectional model is less than the pipe thickness corresponding to the deformation model in this direction, the radius length of the core mold in this direction is increased; if the pipe thickness corresponding to the cross-sectional model is greater than the pipe thickness corresponding to the deformation model in this direction, the radius length of the core mold in this direction is decreased.

[0013] In one possible implementation, the preset directions include: a first direction and a second direction that are parallel to and opposite to the direction of gravity, and a third direction and a fourth direction that are perpendicular to and opposite to the direction of gravity.

[0014] In one possible implementation, after obtaining the optimized core mold dimensions, the process further includes: curve fitting the profile of the core mold's cross-section so that the profile consists of two semi-elliptical curves connected together.

[0015] In one possible implementation, after obtaining the optimized mandrel size, the process further includes: establishing a current cross-sectional model of the pipe based on the current mold size, meshing the current cross-sectional model, assigning a shear relaxation modulus function to each mesh element, and obtaining the current viscoelastic model; the current mold includes a mandrel with the optimized mandrel size and a die; obtaining the test shear stress and test temperature field of the pipe prepared by the extrusion molding process using the current mold during the cooling and solidification stage; performing deformation simulation on the current viscoelastic model based on the test shear stress and test temperature field to obtain the current deformation model; determining whether the comparison results of the cross-sectional model obtained based on the initial mold and the current deformation model are consistent; if they are consistent, determining the mandrel size; if they are inconsistent, continuing to adjust the mandrel size.

[0016] In one possible implementation, the method further includes: establishing a database, which includes the mandrel dimensions corresponding to different preparation information, including the pipe dimensions, the pipe material, and the pipe preparation temperature.

[0017] In one possible implementation, the method further includes: determining the mandrel size that matches the pipe fabrication requirements from a database based on the fabrication information of this pipe fabrication; and selecting a mandrel of the corresponding size as the mandrel used in this pipe fabrication based on the mandrel size that matches the pipe fabrication requirements.

[0018] On the other hand, this application provides a mandrel size determination device, comprising: an initial module for determining the size of an initial mold according to the size requirements of a pipe; wherein the initial mold includes a mandrel and a die; a processing module for establishing a cross-sectional model of the pipe according to the size of the initial mold, and meshing the cross-sectional model of the pipe to obtain multiple mesh elements; assigning a shear relaxation modulus function to each mesh element to obtain a viscoelastic model of the pipe; a simulation module for acquiring the actual stress and actual temperature field of the pipe prepared by extrusion molding using the initial mold during the cooling and solidification stage; performing deformation simulation on the viscoelastic model based on the actual stress and actual temperature field to obtain a deformation model of the pipe; wherein the actual temperature field characterizes the temperature change in different regions of the pipe after extrusion molding; and an optimization module for adjusting the size of the mandrel in the initial mold according to the comparison results of the cross-sectional model and the deformation model to obtain an optimized mandrel size.

[0019] On the other hand, this application provides an electronic device, including: a processor, and a memory communicatively connected to the processor; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory to implement the above method.

[0020] On the other hand, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the above-described method.

[0021] On the other hand, this application provides a computer program product, including a computer program that, when executed by a processor, implements the method described above.

[0022] The method, apparatus, equipment, medium, and product for determining the size of the mandrel provided in this application include: establishing a cross-sectional model of the pipeline based on the initial mold size; meshing the cross-sectional model and assigning a shear relaxation modulus function to each mesh element to obtain a viscoelastic model of the pipeline; performing deformation simulation on the viscoelastic model based on actual stress and actual temperature field to obtain a deformation model of the pipeline; and obtaining the optimized mandrel size based on the comparison results between the cross-sectional model and the deformation model. The scheme of this application establishes a cross-sectional model based on the pipeline size requirements, and the viscoelastic model can characterize the relaxation modulus of the pipeline under shear stress. The environmental conditions of the pipeline during the cooling and solidification stage can be extracted through actual stress and actual temperature field, improving the accuracy of deformation simulation and mandrel size adjustment, thereby improving the pipeline's anti-sagging performance. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0024] Figure 1 illustrates an exemplary flowchart of a method for determining the dimensions of a core mold;

[0025] Figure 2 shows an exemplary schematic diagram of the cross-sectional structure of the initial mold.

[0026] Figure 3 illustrates an exemplary flowchart of a method for determining the dimensions of a core mold;

[0027] Figure 4 illustrates an exemplary flowchart of the method for determining the size of the core mold;

[0028] Figure 5 illustrates an exemplary flowchart of the method for determining the size of the core mold;

[0029] Figure 6 illustrates an exemplary flowchart of the method for determining the size of the core mold;

[0030] Figure 7 shows an exemplary schematic diagram of the deformation model after deformation simulation;

[0031] Figure 8 illustrates an exemplary flowchart of a method for determining the dimensions of a core mold;

[0032] Figure 9 shows an exemplary structural schematic diagram of the core mold size determination device;

[0033] Figure 10 shows an exemplary structural diagram of an electronic device.

[0034] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0035] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0036] It should be noted that the brief descriptions of terminology in this application are merely for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning. The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to be omnipresent but not exclusive. For example, a product or device that comprises a series of components is not necessarily limited to those components explicitly listed, but may include other components not explicitly listed or inherent to such product or device. The term "module" as used in this application refers to any known or subsequently developed hardware, software, firmware, artificial intelligence, fuzzy logic, or combination of hardware and / or software code capable of performing the functions associated with that element.

[0037] Pipes made from polymers such as polyethylene, polypropylene, and polyvinyl chloride are widely used for material transport in construction and municipal engineering, agriculture, and industry due to their excellent chemical resistance, flexibility, and insulation properties. Extrusion molding has become the mainstream process for pipe production due to its advantages of high production speed and high material utilization. The mold used in extrusion molding typically consists of a solid cylindrical mandrel with a regular circular cross-section, a hollow cylindrical die, and an extrusion device. The mandrel is fitted inside the die, and the extrusion device squeezes the polymer into the annular cavity between the mandrel and the die to achieve pipe extrusion molding. However, after the polymer is extruded through the mold at high temperature, there is a period of time before it cools and solidifies. During this time, gravity causes sag in the vertical direction of the pipe, meaning the upper part of the pipe is narrower than the lower part. This sag phenomenon is more pronounced in the manufacturing of large-diameter pipes. Sag causes the deformed pipe to exceed quality standards, further reducing the pipe's performance and safety.

[0038] One approach to preventing pipe sagging is to modify the pipe material formulation, such as by adding reinforcing materials like glass fiber, to improve the pipe's mechanical strength and rigidity, thereby reducing material deformation. However, adding extra materials increases production costs, reduces the controllability of the pipe processing technology, and increases wear on extrusion molding equipment. Another approach involves improving die design, using adjustable dies such as eccentric mandrels with a regular circular cross-section, tilted towards the direction of gravity, to reduce sagging. However, this approach has limited effectiveness in preventing sagging, and is particularly unsuitable for producing large-diameter, thick-walled pipes.

[0039] The technical content provided in this application aims to solve the aforementioned technical problems in related technologies. The method, apparatus, equipment, medium, and product for determining the size of the mandrel in this application include: establishing a cross-sectional model of the pipe based on the initial mold size; meshing the cross-sectional model of the pipe and assigning a shear relaxation modulus function to each mesh element to obtain a viscoelastic model of the pipe; performing deformation simulation on the viscoelastic model based on actual stress and actual temperature field to obtain a deformation model of the pipe; and obtaining the optimized mandrel size based on the comparison results between the cross-sectional model and the deformation model. The solution in this application establishes a cross-sectional model based on the pipe's size requirements. The viscoelastic model can characterize the relaxation modulus of the pipe under shear stress. The environmental conditions of the pipe during the cooling and solidification stage can be extracted through actual stress and actual temperature field, improving the accuracy of deformation simulation and mandrel size adjustment, thereby improving the pipe's anti-sagging performance.

[0040] The technical solutions of this application will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. In the description of this application, unless otherwise expressly specified and limited, the terms should be broadly understood within the art. The embodiments of this application will now be described with reference to the accompanying drawings.

[0041] Example 1

[0042] Figure 1 illustrates a flowchart of a method for determining the size of a mandrel, where the execution entity can be a mandrel size determination device. The mandrel is used as a mold for pipe fabrication. As shown in Figure 1, the method includes:

[0043] Step 101: Determine the dimensions of the initial mold according to the pipe size requirements; the initial mold includes a core mold and a die.

[0044] Step 102: Based on the dimensions of the initial mold, establish the cross-sectional model of the pipe, and mesh the cross-sectional model of the pipe to obtain multiple mesh elements; assign a shear relaxation modulus function to each mesh element to obtain the viscoelastic model of the pipe.

[0045] Step 103: Obtain the actual stress and actual temperature field of the pipe prepared by extrusion molding using the initial mold during the cooling and solidification stage; based on the actual stress and actual temperature field, perform deformation simulation on the viscoelastic model to obtain the deformation model of the pipe; wherein, the actual temperature field characterizes the temperature change in different regions of the pipe after extrusion molding.

[0046] Step 104: The cross-section of the initial mold is circular. Based on the comparison results of the cross-section model and the deformation model, the size of the core mold in the initial mold is adjusted to obtain the optimized core mold size.

[0047] In practical applications, the execution subject of this method can be a core mold size determination device, which can be implemented in various ways. For example, it can be implemented through a computer program, such as application software; or it can be implemented as a medium storing relevant computer programs, such as a USB flash drive or cloud drive; or it can be implemented through a physical device that integrates or installs relevant computer programs, such as a chip.

[0048] For example, pipe size requirements typically include the outer diameter and wall thickness specifications. For instance, when producing 36-inch DR9 pipe (i.e., an outer diameter to wall thickness ratio of 9:1), the pipe size requirements are: outer diameter 914.4 ± 4.11 mm and wall thickness 101.6 ± 12.2 mm. Based on the pipe size requirements, the dimensions of the initial mold, including the mandrel and die, are determined. For example, the mandrel is typically a solid cylinder while the die is a hollow cylinder; the mandrel and die are concentrically nested, and the annular cavity between them is filled with pipe material. The cross-section of the initial mold can be seen in the schematic diagram of the initial mold cross-section structure shown in Figure 2. In practical applications, taking the size requirements of 36-inch DR9 pipe as an example, the corresponding mandrel specification is Φ987 mm, and the die specification is Φ768 mm. Optionally, the specifications of the mandrel and die in the initial mold can be adjusted according to requirements. Furthermore, a cross-sectional model is established based on the dimensions of the initial mold; this cross-section is a two-dimensional cross-section of the annular cavity between the core mold and the die. It should be noted that in the extrusion molding process, each cross-section of the pipe can be considered to have undergone the same extrusion process and formed the same cross-sectional dimensions. Therefore, a two-dimensional cross-sectional model can be established for subsequent deformation simulation. Correspondingly, the two-dimensional cross-sectional model can reduce the required computational resources. Optionally, multiple cross-sectional models can be established to simulate the deformation of different locations of the pipe under different cooling environments. After obtaining the cross-sectional model, the model is meshed to obtain multiple mesh elements. For example, the model can be divided into quadrilateral or triangular meshes, and the number of mesh elements can be selected according to requirements. A shear relaxation modulus function is assigned to each obtained mesh element to obtain the viscoelastic model of the pipe. The shear relaxation modulus function characterizes the pipe material's ability to resist deformation under shear force; the shear relaxation modulus varies at different temperatures. In practical applications, the shear relaxation modulus function can be fitted using the Maxwell model or the Kelvin-Voigt model. In this example, by assigning a shear relaxation modulus function to each mesh element, it is beneficial to calculate the degree of deformation of each mesh element under the influence of temperature and actual stress in subsequent deformation simulations.

[0049] After obtaining the viscoelastic model, the actual stress and temperature field of the pipe fabricated using the initial die during the cooling and solidification stage are acquired. For example, the actual stress and temperature field characterize the environmental factors affecting pipe deformation during the cooling and solidification stage after fabrication. In practical applications, a real pipe section can be fabricated based on the initial die, and the actual stress and temperature field of this real pipe section can be measured using relevant instruments and sensors. Optionally, shear stress and the actual temperature field can also be obtained through numerical simulation. For example, the actual stress can be shear stress, tensile stress, or compressive stress that causes sag. For example, the actual temperature field characterizes the temperature change of the pipe's inner and outer sides on the cross-section after extrusion, which gradually decreases with heat diffusion, leading to pipe cooling and solidification. For example, to improve the representativeness of the temperature field, the temperature field corresponding to the cross-section of the middle section of the pipe can be selected. Optionally, the average of multiple temperature fields at different pipe locations can be calculated. Further, based on the actual stress and temperature field, deformation simulation is performed on the viscoelastic model to obtain the pipe's deformation model. For example, finite element analysis tools or physics simulation tools can be selected to perform deformation simulation on the viscoelastic model to obtain a deformation model.

[0050] After obtaining the deformation model, the dimensions of the mandrel in the initial mold are adjusted based on the comparison results between the cross-sectional model and the deformation model to obtain optimized mandrel dimensions. The comparison between the cross-sectional model and the deformation model can be approximated by comparing the standard cross-sectional dimensions of the pipe with the cross-sectional dimensions of the pipe after deformation simulation. For example, using the pipe thickness corresponding to the cross-sectional model as a standard, the mandrel dimensions are adjusted based on the comparison results between the cross-sectional model and the deformation model. For instance, if the pipe thickness corresponding to the deformation model in a certain direction is greater than the pipe thickness corresponding to the cross-sectional model in that direction, it indicates that the pipe thickness has increased in that direction due to the sag effect. Accordingly, increasing the radius of the mandrel in that direction, i.e., reducing the volume of the cavity between the mandrel and the die in that direction, can reduce the thickness of the fabricated pipe. Alternatively, relevant machine learning methods can also be used to adjust the mandrel dimensions based on the comparison results between the cross-sectional model and the deformation model. In the above-mentioned core mold size adjustment process, only the size of one cross-section of the core mold is adjusted. After extending this cross-section longitudinally, a columnar core mold can be obtained, and this columnar core mold is used as the optimized core mold size.

[0051] The method for determining the size of the mandrel in this example includes: establishing a cross-sectional model of the pipe based on the initial mold size; meshing the cross-sectional model and assigning a shear relaxation modulus function to each mesh element to obtain the viscoelastic model of the pipe; performing deformation simulation on the viscoelastic model based on actual stress and temperature field to obtain the deformation model of the pipe; and obtaining the optimized mandrel size based on the comparison between the cross-sectional model and the deformation model. The scheme in this application establishes a cross-sectional model according to the pipe's size requirements, and the viscoelastic model can characterize the relaxation modulus of the pipe under shear stress. The environmental conditions of the pipe during the cooling and solidification stage can be extracted through actual stress and temperature field, improving the accuracy of deformation simulation and mandrel size adjustment, thereby improving the pipe's anti-sagging performance.

[0052] As another example, Figure 3 illustrates a flowchart of a method for determining the dimensions of a core mold. As shown in Figure 3, the method for determining the dimensions of a core mold further includes:

[0053] Step 201: Obtain the fixed shear relaxation modulus at different temperatures;

[0054] Step 202: Establish a shear relaxation modulus function by summing the fixed shear relaxation modulus at different temperatures and at least one dynamic shear relaxation modulus related to temperature.

[0055] This example considers the pipe material as a viscoelastic material, whose relaxation modulus under shear force has a complex composition. Decomposing the relaxation modulus allows for a better understanding and description of the pipe material's mechanical behavior at different time scales. Specifically, the shear relaxation modulus is decomposed into a fixed shear relaxation modulus and a dynamic relaxation modulus. The fixed shear relaxation modulus is typically related to the material's instantaneous elastic response, i.e., the elastic properties exhibited by the material at the moment of loading. This portion of the relaxation modulus remains constant throughout the relaxation process but changes with temperature; for example, at higher temperatures, the fixed relaxation modulus decreases due to molecular thermal motion. On the other hand, the dynamic shear relaxation modulus is related to the material's viscoelastic behavior; the stress on the material gradually relaxes over time. This portion of the relaxation modulus is time-dependent and typically decreases with increasing time. For example, the number of dynamic shear relaxation moduli in the mathematical expression of the shear relaxation modulus is related to the material properties, and the number needs to be determined through fitting. Correspondingly, for the same material property, increasing the number of dynamic shear relaxation moduli can improve the mathematical expression of the shear relaxation modulus function for that material. For example, the shear relaxation modulus function is:

[0056] Among them, G e To fix the shear relaxation modulus, G i(t) represents the i-th dynamic shear relaxation modulus, N is the number of dynamic shear relaxation moduli, and t is the cooling time of the pipe. For example, the cooling time of the pipe refers to the time from extrusion through the die to solidification. For instance, for high-density polyethylene, the cooling time refers to the period from approximately 140°C at the extrusion temperature to approximately 110°C at the solidification temperature. In practical applications, the cooling time may vary depending on the processing temperature and extrusion speed. As mentioned above, the fixed shear relaxation modulus corresponds to a constant value at different temperatures, while the dynamic shear relaxation modulus is time-dependent. The dynamic shear relaxation modulus is:

[0057] Among them, g i τ is a fixed component of the i-th dynamic shear relaxation modulus. i Let be the relaxation time at the i-th dynamic shear relaxation modulus. Here, the fixed components of the dynamic shear relaxation modulus and their corresponding pipe relaxation times are temperature-dependent physical quantities. The scheme in this example, by decomposing the shear relaxation modulus of the pipe material and quantitatively representing it using a shear relaxation modulus function, can improve the realism of the viscoelastic model and the accuracy of subsequent deformation simulations.

[0058] As another example, Figure 4 illustrates a flowchart of a method for determining the dimensions of a mandrel. As shown in Figure 4, step 202 includes:

[0059] Step 301: Obtain the shear relaxation modulus values ​​of the material to which the pipe is made at different temperatures;

[0060] Step 302: Take the exponential function with temperature as the independent variable as the fixed component of the shear relaxation modulus, take the quadratic function with temperature as the independent variable as the relaxation time, and determine the initial value of the fixed shear relaxation modulus and the initial value of the number of dynamic shear relaxation moduli to establish the initial shear relaxation modulus function.

[0061] Step 303: Establish a loss based on the shear relaxation modulus value and the output value of the initial shear relaxation modulus function. If the loss value is less than the threshold, determine the shear relaxation modulus function; if the loss value is not less than the threshold, adjust the coefficients in the exponential and quadratic functions, and the number of fixed and dynamic shear relaxation moduli, until the loss value is less than the threshold.

[0062] For example, the shear relaxation modulus value of the pipe material can be obtained through stress relaxation tests on the material. A set of data pairs is formed by pairing temperature with the corresponding shear relaxation modulus value, which can be pre-stored on a server or storage medium. Optionally, an interpolation method can be used to supplement the existing data pairs to increase the data volume. An exponential function with temperature as the independent variable is used as the fixed component of the shear relaxation modulus, and a quadratic function with temperature as the independent variable is used as the relaxation time.

[0063] The formula for the fixed component g of the shear relaxation modulus is as follows: g = a * e (b*T)

[0064] The formula for relaxation time τ is as follows: τ=c*T 2 +d*T+e

[0065] Where T is the temperature, a and b are the coefficients of the exponential function, and c, d, and e are the coefficients of the quadratic function. In practical applications, the coefficients of the exponential and quadratic functions are predetermined, and these coefficients can be a set of random numbers. On the other hand, the fixed shear relaxation modulus G also needs to be determined. e The initial value can be randomly assigned to G based on each obtained temperature. e Alternatively, a fixed value such as 100 MPa can be assigned based on experience; and an initial value, N, can be determined for the number of dynamic shear relaxation moduli. For example, N can be any integer from 2 to 6, or its value can be increased based on the complexity of the pipe material. After establishing the initial shear relaxation modulus function, a loss is established based on the shear relaxation modulus value and the output value of the initial shear relaxation modulus function. For example, if the shear relaxation modulus value is 255 MPa at 100°C, and the initial shear relaxation modulus function output value is 200 MPa at T=100°C, the corresponding loss value is calculated. For example, algorithms such as nonlinear least squares or gradient descent can be used to establish the loss and obtain the loss value. If the loss value is less than a threshold, the shear relaxation modulus function is determined; if the loss value is not less than the threshold, the coefficients in the exponential and quadratic functions, the number of fixed and dynamic shear relaxation moduli, are adjusted until the loss value is less than the threshold. The proposed solution acquires observed data, i.e., shear relaxation modulus values, at different temperatures. By establishing an initial shear relaxation modulus function and obtaining the predicted value of the function output at the same temperature, the error between the two is used to determine the relevant parameters in the shear relaxation modulus function, thereby improving the fitting ability of the shear relaxation modulus function and the accuracy of the output value.

[0066] As another example, Figure 5 illustrates a flowchart of a method for determining the size of a core mold. As shown in Figure 5, the cross-section of the initial mold in step 104 is circular. Based on the comparison results of the cross-section model and the deformation model, the size of the core mold in the initial mold is adjusted, including:

[0067] Step 401: Detect the relationship between the pipe thickness corresponding to the cross-section model and the pipe thickness corresponding to the deformation model in a preset direction outward from the center of the cross-section model.

[0068] Step 402: If the pipe thickness corresponding to the cross-sectional model in this direction is less than the pipe thickness corresponding to the deformation model, then increase the radius length of the mandrel in this direction.

[0069] Step 403: If the pipe thickness corresponding to the cross-sectional model in this direction is greater than the pipe thickness corresponding to the deformation model, then reduce the radius length of the mandrel in this direction.

[0070] In this example, preset directions can be set to dozens to hundreds of directions radiating outward from the origin, so that the cross-sectional profile of the adjusted mandrel is a high-precision irregular curve, thereby improving the accuracy of mandrel size adjustment. Optionally, the preset directions can be four or eight directions distributed at equal angles to reduce the processing difficulty of the mandrel size. If the pipe thickness corresponding to the cross-sectional model in a preset direction is less than the pipe thickness corresponding to the deformation model, the radius of the mandrel in that direction is increased. For example, when the pipe thickness corresponding to the cross-sectional model in a certain preset direction is 100mm, and the pipe thickness corresponding to the deformation model is 120mm, the radius of the mandrel in that direction is increased by 20mm. Optionally, for a pipe thickness specification of 100±10mm, the radius of the mandrel in that direction can be increased by 10mm simply by adjusting it to within the specification range. On the other hand, if the pipe thickness corresponding to the cross-sectional model in a preset direction is greater than the pipe thickness corresponding to the deformation model, the radius of the mandrel in that direction is decreased. Similarly, the radius of the mandrel in that direction can be decreased according to the adjustment logic described above. In this example, the solution adjusts the radius length of the mandrel in a preset direction based on the relationship between the pipe thickness corresponding to the cross-sectional model and the pipe thickness corresponding to the deformation model, thereby improving the accuracy of mandrel size adjustment.

[0071] As another example, the preset directions include: a first and a second direction that are parallel to and opposite to the direction of gravity, and a third and a fourth direction that are perpendicular to and opposite to the direction of gravity.

[0072] In this example, considering that the sag effect is mainly caused by gravity, by setting a first and second direction that are parallel to the direction of gravity and opposite to each other, and a third and fourth direction that are perpendicular to the direction of gravity and opposite to each other, the number of times the core mold size can be adjusted can be reduced while compensating for the sag effect.

[0073] As yet another example, after the optimized core mold dimensions in step 104, the following steps are also included:

[0074] The profile of the cross-section of the core mold is curve-fitted so that the profile is composed of two semi-elliptical curves connected together.

[0075] For example, a straight line perpendicular to the direction of gravity and passing through the center of the mandrel's cross-section can be used as a dividing line. The cross-sectional profile of the mandrel above the dividing line can be fitted into a semi-ellipse, and the cross-sectional profile of the mandrel below the dividing line can be fitted into another semi-ellipse. For example, the dividing line can also be any straight line passing through the cross-section of the mandrel, where the geometric dimensions of the ellipses on both sides of the dividing line can be the same or different. In practical applications, the above fitting process can be implemented using computer programming tools or image processing tools. The scheme in this example further optimizes the shape of the profile of the optimized mandrel, improving the smoothness of the mandrel profile, resulting in consistent pipes, and improving the ease of mandrel manufacturing.

[0076] As another example, Figure 6 illustrates a flowchart of a method for determining the size of a mandrel. As shown in Figure 6, after obtaining the optimized mandrel size in step 104, the method further includes:

[0077] Step 501: Based on the current mold size, establish the current cross-sectional model of the pipe, and mesh the current cross-sectional model. Assign a shear relaxation modulus function to each mesh element to obtain the current viscoelastic model. The current mold includes a core mold with optimized core mold size and a die.

[0078] Step 502: Obtain the test stress and test temperature field of the pipe prepared by the extrusion molding process using the current mold during the cooling and solidification stage; Based on the test stress and test temperature field, perform deformation simulation on the current viscoelastic model to obtain the current deformation model;

[0079] Step 503: Determine whether the comparison results of the cross-sectional model obtained based on the initial mold and the current deformation model are consistent. If they are consistent, determine the core mold size; if they are inconsistent, continue to adjust the core mold size.

[0080] In this example, a viscoelastic model is established based on the dimensions of the current mold, which includes a mandrel with optimized core dimensions and a die. Specifically, the optimized core dimensions in the current mold can be the core dimensions optimized once or optimized multiple times. After obtaining the current viscoelastic model, the test stress and test temperature field of the pipe prepared by the extrusion molding process using the current mold are obtained during the cooling and solidification stage. In practical applications, a real pipe section can be prepared using the current mold, and the test stress and test temperature field of this real pipe section during the cooling and solidification stage can be obtained using testing instruments or sensors. Optionally, considering that the adjustment between the unoptimized and optimized core dimensions will not be significant, the unoptimized actual stress and actual temperature field can be used as the test stress and test temperature field for further deformation simulation.

[0081] After obtaining the current deformation model, it is determined whether the comparison result between the cross-sectional model obtained based on the initial mold and the current deformation model is consistent. If they are consistent, the mandrel size is determined; otherwise, the mandrel size is adjusted further. The consistency determination refers to whether the pipe thickness corresponding to the current deformation model is within the specification range of the pipe thickness corresponding to the cross-sectional model obtained from the initial mold. For example, further adjusting the mandrel size involves adjusting it according to the adjustment direction based on the mandrel adjustment corresponding to the previous deformation fitting. This example scheme, considering that the mandrel size optimized in a single operation may have limitations in practical applications, improves the error tolerance and applicability of the optimized mandrel size by adjusting it after multiple deformation simulations.

[0082] Figure 7 illustrates an exemplary deformation model after deformation simulation. As shown in Figure 7, the left figure is a deformation diagram of the deformation model without optimized mandrel dimensions, and the right figure is a deformation diagram of the deformation model after one optimization of the mandrel dimensions. Different colors represent different degrees of deformation; the closer the color is to blue (the inner edges of the top and bottom of the ring are blue), the smaller the deformation degree; the closer the color is to red (the outer edges of the left and right of the ring are red), the larger the deformation degree. The black ring in the figure represents the initial cross-sectional model. Figure 7 shows that the deformation degree caused by the sag effect after one optimization of the mandrel dimensions is less than the deformation degree caused by the sag effect without optimized mandrel dimensions.

[0083] As yet another example, methods for determining the dimensions of the core mold also include:

[0084] A database is established, which includes the core mold dimensions corresponding to different preparation information. The preparation information includes the pipe dimensions, pipe material, and pipe preparation temperature.

[0085] This example demonstrates a scheme that establishes a correspondence between fabrication information and mandrel dimensions and stores this information in a database. This improves the automation level of the pipe production process and enables customized production. Optionally, the fabrication information may also include extrusion molding speed, etc. In practical applications, mandrels of different sizes can also be pre-manufactured to improve the production efficiency of pipe manufacturing.

[0086] As another example, Figure 8 illustrates a flowchart of a method for determining the dimensions of a core mold. As shown in Figure 8, the determination of the core mold dimensions further includes:

[0087] Step 601: Based on the preparation information of this pipeline preparation, determine the core mold size that matches the pipeline preparation requirements from the database;

[0088] Step 602: Select a mandrel of the corresponding size as the mandrel used in this pipeline fabrication based on the mandrel size that matches the pipeline fabrication requirements.

[0089] The solution in this example matches the mandrel size from the database based on the preparation information of this pipe fabrication, and selects the mandrel of the corresponding size as the mandrel used in this pipe fabrication. This can improve production accuracy, optimize mandrel inventory management, and increase the utilization rate of existing mandrel resources.

[0090] The method for determining the size of the mandrel in this embodiment includes: establishing a cross-sectional model of the pipe based on the initial mold size; meshing the cross-sectional model and assigning a shear relaxation modulus function to each mesh element to obtain a viscoelastic model of the pipe; performing deformation simulation on the viscoelastic model based on actual stress and actual temperature field to obtain a deformation model of the pipe; and obtaining the optimized mandrel size based on the comparison results between the cross-sectional model and the deformation model. The solution in this application establishes a cross-sectional model based on the pipe's size requirements. The viscoelastic model can characterize the relaxation modulus of the pipe under shear stress. The environmental conditions of the pipe during the cooling and solidification stage can be extracted through actual stress and actual temperature field, improving the accuracy of deformation simulation and mandrel size adjustment, thereby improving the pipe's anti-sagging performance.

[0091] Example 2

[0092] Figure 9 illustrates a schematic diagram of a mandrel size determination device. As shown in Figure 9, the device includes:

[0093] The initial module 91 is used to determine the size of the initial mold according to the size requirements of the pipeline; wherein the initial mold includes a core mold and a die.

[0094] Processing module 92 is used to establish a cross-sectional model of the pipe based on the size of the initial mold, and to mesh the cross-sectional model of the pipe to obtain multiple mesh elements; a shear relaxation modulus function is assigned to each mesh element to obtain the viscoelastic model of the pipe.

[0095] Simulation module 93 is used to obtain the actual stress and actual temperature field of the pipe prepared by extrusion molding using an initial mold during the cooling and solidification stage; based on the actual stress and actual temperature field, the viscoelastic model is used to perform deformation simulation to obtain the deformation model of the pipe; wherein, the actual temperature field characterizes the temperature change in different regions of the pipe after extrusion molding.

[0096] The optimization module 94 is used to adjust the size of the core mold in the initial mold based on the comparison results of the cross-sectional model and the deformation model, so as to obtain the optimized core mold size.

[0097] In practical applications, there are various ways to implement the core mold size determination device. For example, it can be implemented through a computer program, such as application software; or it can be implemented as a medium storing the relevant computer program, such as a USB flash drive or cloud drive; or it can be implemented through a physical device that integrates or installs the relevant computer program, such as a chip.

[0098] For example, the cross-section of the initial mold is circular. Pipe size requirements typically include the outer diameter and wall thickness specifications. For instance, when producing 36-inch DR9 pipe (i.e., an outer diameter to wall thickness ratio of 9:1), the pipe size requirements are an outer diameter of 914.4 ± 4.11 mm and a wall thickness of 101.6 ± 12.2 mm. Based on the pipe size requirements, the dimensions of the initial mold, including the mandrel and die, are determined. For example, the mandrel is typically a solid cylinder while the die is a hollow cylinder; the mandrel and die are concentrically nested, and the annular cavity between them is filled with pipe material. The cross-section of the initial mold can be seen in the schematic diagram of the initial mold cross-section structure shown in Figure 2. In practical applications, taking the size requirements of 36-inch DR9 pipe as an example, the corresponding mandrel specification is Φ987 mm, and the die specification is Φ768 mm. Optionally, the specifications of the mandrel and die in the initial mold can be adjusted according to requirements. Furthermore, a cross-sectional model is established based on the dimensions of the initial mold; this cross-section is a two-dimensional cross-section of the annular cavity between the core mold and the die. It should be noted that in the extrusion molding process, each cross-section of the pipe can be considered to have undergone the same extrusion process and formed the same cross-sectional dimensions. Therefore, a two-dimensional cross-sectional model can be established for subsequent deformation simulation. Correspondingly, the two-dimensional cross-sectional model can reduce the required computational resources. Optionally, multiple cross-sectional models can be established to simulate the deformation of different locations of the pipe under different cooling environments. After obtaining the cross-sectional model, the model is meshed to obtain multiple mesh elements. For example, the model can be divided into quadrilateral or triangular meshes, and the number of mesh elements can be selected according to requirements. A shear relaxation modulus function is assigned to each obtained mesh element to obtain the viscoelastic model of the pipe. The shear relaxation modulus function characterizes the pipe material's ability to resist deformation under shear force; the shear relaxation modulus varies at different temperatures. In practical applications, the shear relaxation modulus function can be fitted using the Maxwell model or the Kelvin-Voigt model. In this example, by assigning a shear relaxation modulus function to each mesh element, it is beneficial to calculate the degree of deformation of each mesh element under the influence of temperature and actual stress in subsequent deformation simulations.

[0099] After obtaining the viscoelastic model, the actual stress and temperature field of the pipe fabricated using the initial die during the cooling and solidification stage are acquired. For example, the actual stress and temperature field characterize the environmental factors affecting pipe deformation during the cooling and solidification stage after fabrication. In practical applications, a real pipe section can be fabricated based on the initial die, and the actual stress and temperature field of this real pipe section can be measured using relevant instruments and sensors. Optionally, the actual stress and temperature field can also be obtained through numerical simulation. For example, the actual stress can be shear stress, tensile stress, or compressive stress that causes sag. For example, the actual temperature field characterizes the temperature change of the pipe's inner and outer sides on the cross-section after extrusion, which gradually decreases with heat diffusion, leading to pipe cooling and solidification. For example, to improve the representativeness of the temperature field, the temperature field corresponding to the cross-section of the middle section of the pipe can be selected. Optionally, the average of multiple temperature fields at different pipe locations can be calculated. Further, based on the actual stress and temperature field, deformation simulation is performed on the viscoelastic model to obtain the pipe deformation model. For example, finite element analysis tools or physics simulation tools can be selected to perform deformation simulation on the viscoelastic model to obtain a deformation model.

[0100] After obtaining the deformation model, the dimensions of the mandrel in the initial mold are adjusted based on the comparison results between the cross-sectional model and the deformation model to obtain optimized mandrel dimensions. The comparison between the cross-sectional model and the deformation model can be approximated by comparing the standard cross-sectional dimensions of the pipe with the cross-sectional dimensions of the pipe after deformation simulation. For example, using the pipe thickness corresponding to the cross-sectional model as a standard, the mandrel dimensions are adjusted based on the comparison results between the cross-sectional model and the deformation model. For instance, if the pipe thickness corresponding to the deformation model in a certain direction is greater than the pipe thickness corresponding to the cross-sectional model in that direction, it indicates that the pipe thickness has increased in that direction due to the sag effect. Accordingly, increasing the radius of the mandrel in that direction, i.e., reducing the volume of the cavity between the mandrel and the die in that direction, can reduce the thickness of the fabricated pipe. Alternatively, relevant machine learning methods can also be used to adjust the mandrel dimensions based on the comparison results between the cross-sectional model and the deformation model. In the above-mentioned core mold size adjustment process, only the size of one cross-section of the core mold is adjusted. After extending this cross-section longitudinally, a columnar core mold can be obtained, and this columnar core mold is used as the optimized core mold size.

[0101] The mandrel size determination device in this example includes: establishing a cross-sectional model of the pipe based on the initial mold size; meshing the cross-sectional model and assigning a shear relaxation modulus function to each mesh element to obtain a viscoelastic model of the pipe; performing deformation simulation on the viscoelastic model based on actual stress and temperature field to obtain a deformation model of the pipe; and obtaining the optimized mandrel size based on the comparison results between the cross-sectional model and the deformation model. The scheme in this application establishes a cross-sectional model according to the pipe's size requirements, and the viscoelastic model can characterize the relaxation modulus of the pipe under shear stress. The environmental conditions of the pipe during the cooling and solidification stage can be extracted through actual stress and temperature field, improving the accuracy of deformation simulation and mandrel size adjustment, thereby improving the pipe's anti-sagging performance.

[0102] In one example, processing module 92 is also used for:

[0103] Obtain the fixed shear relaxation modulus at different temperatures;

[0104] A shear relaxation modulus function is established by summing the fixed shear relaxation modulus at different temperatures and at least one temperature-dependent dynamic shear relaxation modulus.

[0105] This example considers the pipe material as a viscoelastic material, whose relaxation modulus under shear force has a complex composition. Decomposing the relaxation modulus allows for a better understanding and description of the pipe material's mechanical behavior at different time scales. Specifically, the shear relaxation modulus is decomposed into a fixed shear relaxation modulus and a dynamic relaxation modulus. The fixed shear relaxation modulus is typically related to the material's instantaneous elastic response, i.e., the elastic properties exhibited by the material at the moment of loading. This portion of the relaxation modulus remains constant throughout the relaxation process but changes with temperature; for example, at higher temperatures, the fixed relaxation modulus decreases due to molecular thermal motion. On the other hand, the dynamic shear relaxation modulus is related to the material's viscoelastic behavior; the stress on the material gradually relaxes over time. This portion of the relaxation modulus is time-dependent and typically decreases with increasing time. For example, the number of dynamic shear relaxation moduli in the mathematical expression of the shear relaxation modulus is related to the material properties, and the number needs to be determined through fitting. Correspondingly, for the same material property, increasing the number of dynamic shear relaxation moduli can improve the mathematical expression of the shear relaxation modulus function for that material. For example, the shear relaxation modulus function is:

[0106] Among them, G e To fix the shear relaxation modulus, G i(t) represents the i-th dynamic shear relaxation modulus, N is the number of dynamic shear relaxation moduli, and t is the cooling time of the pipe. For example, the cooling time of the pipe refers to the time from extrusion through the die to solidification. For instance, for high-density polyethylene, the cooling time refers to the period from approximately 140°C at the extrusion temperature to approximately 110°C at the solidification temperature. In practical applications, the cooling time may vary depending on the processing temperature and extrusion speed. As mentioned above, the fixed shear relaxation modulus corresponds to a constant value at different temperatures, while the dynamic shear relaxation modulus is time-dependent. The dynamic shear relaxation modulus is:

[0107] Among them, g i τ is a fixed component of the i-th dynamic shear relaxation modulus. i Let be the relaxation time at the i-th dynamic shear relaxation modulus. Here, the fixed components of the dynamic shear relaxation modulus and their corresponding pipe relaxation times are temperature-dependent physical quantities. The scheme in this example, by decomposing the shear relaxation modulus of the pipe material and quantitatively representing it using a shear relaxation modulus function, can improve the realism of the viscoelastic model and the accuracy of subsequent deformation simulations.

[0108] In one example, processing module 92 is specifically used for:

[0109] Obtain the shear relaxation modulus values ​​of the material to which the pipe is made at different temperatures;

[0110] An exponential function with temperature as the independent variable is used as the fixed component of the shear relaxation modulus, and a quadratic function with temperature as the independent variable is used as the relaxation time. The initial values ​​of the fixed shear relaxation modulus and the number of dynamic shear relaxation moduli are determined to establish the initial shear relaxation modulus function.

[0111] The loss is established based on the shear relaxation modulus value and the output value of the initial shear relaxation modulus function. If the loss value is less than the threshold, the shear relaxation modulus function is determined; if the loss value is not less than the threshold, the coefficients in the exponential and quadratic functions, the number of fixed and dynamic shear relaxation moduli are adjusted until the loss value is less than the threshold.

[0112] For example, the shear relaxation modulus value of the pipe material can be obtained through stress relaxation tests on the material. A set of data pairs is formed by pairing temperature with the corresponding shear relaxation modulus value, which can be pre-stored on a server or storage medium. Optionally, an interpolation method can be used to supplement the existing data pairs to increase the data volume. An exponential function with temperature as the independent variable is used as the fixed component of the shear relaxation modulus, and a quadratic function with temperature as the independent variable is used as the relaxation time.

[0113] The formula for the fixed component g of the shear relaxation modulus is as follows: g = a * e (b*T)

[0114] The formula for relaxation time τ is as follows: τ=c*T 2 +d*T+e

[0115] Where T is the temperature, a and b are the coefficients of the exponential function, and c, d, and e are the coefficients of the quadratic function. In practical applications, the coefficients of the exponential and quadratic functions are predetermined, and these coefficients can be a set of random numbers. On the other hand, the fixed shear relaxation modulus G also needs to be determined. e The initial value can be randomly assigned to G based on each obtained temperature. e Alternatively, a fixed value such as 100 MPa can be assigned based on experience; and an initial value, N, can be determined for the number of dynamic shear relaxation moduli. For example, N can be any integer from 2 to 6, or its value can be increased based on the complexity of the pipe material. After establishing the initial shear relaxation modulus function, a loss is established based on the shear relaxation modulus value and the output value of the initial shear relaxation modulus function. For example, if the shear relaxation modulus value is 255 MPa at 100°C, and the initial shear relaxation modulus function output value is 200 MPa at T=100°C, the corresponding loss value is calculated. For example, algorithms such as nonlinear least squares or gradient descent can be used to establish the loss and obtain the loss value. If the loss value is less than a threshold, the shear relaxation modulus function is determined; if the loss value is not less than the threshold, the coefficients in the exponential and quadratic functions, the number of fixed and dynamic shear relaxation moduli, are adjusted until the loss value is less than the threshold. The proposed solution acquires observed data, i.e., shear relaxation modulus values, at different temperatures. By establishing an initial shear relaxation modulus function and obtaining the predicted value of the function output at the same temperature, the error between the two is used to determine the relevant parameters in the shear relaxation modulus function, thereby improving the fitting ability of the shear relaxation modulus function and the accuracy of the output value.

[0116] In one example, optimization module 94 is specifically used for:

[0117] The relationship between the pipe thickness corresponding to the cross-sectional model and the pipe thickness corresponding to the deformation model is detected in a preset direction outward from the center of the cross-sectional model.

[0118] If the pipe thickness corresponding to the cross-sectional model in this direction is less than the pipe thickness corresponding to the deformation model, then increase the radius length of the mandrel in this direction.

[0119] If the pipe thickness corresponding to the cross-sectional model in this direction is greater than the pipe thickness corresponding to the deformation model, then the radius length of the mandrel in this direction should be reduced.

[0120] In this example, preset directions can be set to dozens to hundreds of directions radiating outward from the origin, so that the cross-sectional profile of the adjusted mandrel is a high-precision irregular curve, thereby improving the accuracy of mandrel size adjustment. Optionally, the preset directions can be four or eight directions distributed at equal angles to reduce the processing difficulty of the mandrel size. If the pipe thickness corresponding to the cross-sectional model in a preset direction is less than the pipe thickness corresponding to the deformation model, the radius of the mandrel in that direction is increased. For example, when the pipe thickness corresponding to the cross-sectional model in a certain preset direction is 100mm, and the pipe thickness corresponding to the deformation model is 120mm, the radius of the mandrel in that direction is increased by 20mm. Optionally, for a pipe thickness specification of 100±10mm, the radius of the mandrel in that direction can be increased by 10mm simply by adjusting it to within the specification range. On the other hand, if the pipe thickness corresponding to the cross-sectional model in a preset direction is greater than the pipe thickness corresponding to the deformation model, the radius of the mandrel in that direction is decreased. Similarly, the radius of the mandrel in that direction can be decreased according to the adjustment logic described above. In this example, the solution adjusts the radius length of the mandrel in a preset direction based on the relationship between the pipe thickness corresponding to the cross-sectional model and the pipe thickness corresponding to the deformation model, thereby improving the accuracy of mandrel size adjustment.

[0121] In one example, the preset directions include: a first and a second direction that are parallel to and opposite to the direction of gravity, and a third and a fourth direction that are perpendicular to and opposite to the direction of gravity.

[0122] In this example, considering that the sag effect is mainly caused by gravity, by setting a first and second direction that are parallel to the direction of gravity and opposite to each other, and a third and fourth direction that are perpendicular to the direction of gravity and opposite to each other, the number of times the core mold size can be adjusted can be reduced while compensating for the sag effect.

[0123] In one example, optimization module 94 is also used for:

[0124] The profile of the cross-section of the core mold is curve-fitted so that the profile is composed of two semi-elliptical curves connected together.

[0125] For example, a straight line perpendicular to the direction of gravity and passing through the center of the mandrel's cross-section can be used as a dividing line. The cross-sectional profile of the mandrel above the dividing line can be fitted into a semi-ellipse, and the cross-sectional profile of the mandrel below the dividing line can be fitted into another semi-ellipse. For example, the dividing line can also be any straight line passing through the cross-section of the mandrel, where the geometric dimensions of the ellipses on both sides of the dividing line can be the same or different. In practical applications, the above fitting process can be implemented using computer programming tools or image processing tools. The scheme in this example further optimizes the shape of the profile of the optimized mandrel, improving the smoothness of the mandrel profile, resulting in consistent pipes, and improving the ease of mandrel manufacturing.

[0126] In one example, optimization module 94 is also used for:

[0127] Based on the current mold size, a current cross-sectional model of the pipe is established, and the current cross-sectional model is meshed. A shear relaxation modulus function is assigned to each mesh element to obtain the current viscoelastic model. The current mold includes a core mold with optimized core mold size and a die.

[0128] The test stress and test temperature field of the pipe prepared by the extrusion molding process using the current mold are obtained during the cooling and solidification stage; based on the test stress and test temperature field, the deformation simulation of the current viscoelastic model is performed to obtain the current deformation model.

[0129] Determine whether the cross-sectional model obtained based on the initial mold and the current deformation model are consistent. If they are consistent, determine the core mold size; if they are inconsistent, continue to adjust the core mold size.

[0130] In this example, a viscoelastic model is established based on the dimensions of the current mold, which includes a mandrel with optimized core dimensions and a die. Specifically, the optimized core dimensions in the current mold can be the core dimensions optimized once or optimized multiple times. After obtaining the current viscoelastic model, the test stress and test temperature field of the pipe prepared by the extrusion molding process using the current mold are obtained during the cooling and solidification stage. In practical applications, a real pipe section can be prepared using the current mold, and the test stress and test temperature field of this real pipe section during the cooling and solidification stage can be obtained using testing instruments or sensors. Optionally, considering that the adjustment between the unoptimized and optimized core dimensions will not be significant, the unoptimized actual stress and actual temperature field can be used as the test stress and test temperature field for further deformation simulation.

[0131] After obtaining the current deformation model, it is determined whether the comparison result between the cross-sectional model obtained based on the initial mold and the current deformation model is consistent. If they are consistent, the mandrel size is determined; otherwise, the mandrel size is adjusted further. The consistency determination refers to whether the pipe thickness corresponding to the current deformation model is within the specification range of the pipe thickness corresponding to the cross-sectional model obtained from the initial mold. For example, further adjusting the mandrel size involves adjusting it according to the adjustment direction based on the mandrel adjustment corresponding to the previous deformation fitting. This example scheme, considering that the mandrel size optimized in a single operation may have limitations in practical applications, improves the error tolerance and applicability of the optimized mandrel size by adjusting it after multiple deformation simulations.

[0132] In one example, the core mold sizing device further includes: an application module 95; the application module 95 is specifically used for:

[0133] A database is established, which includes the core mold dimensions corresponding to different preparation information. The preparation information includes the pipe dimensions, pipe material, and pipe preparation temperature.

[0134] This example demonstrates a scheme that establishes a correspondence between fabrication information and mandrel dimensions and stores this information in a database. This improves the automation level of the pipe production process and enables customized production. Optionally, the fabrication information may also include extrusion molding speed, etc. In practical applications, mandrels of different sizes can also be pre-manufactured to improve the production efficiency of pipe manufacturing.

[0135] In one example, module 95 is also used for:

[0136] Based on the preparation information of this pipeline, the core mold size that matches the pipeline preparation requirements is determined from the database;

[0137] Based on the mandrel size that matches the pipeline fabrication requirements, a mandrel of the corresponding size is selected as the mandrel used in this pipeline fabrication.

[0138] The solution in this example matches the mandrel size from the database based on the preparation information of this pipe fabrication, and selects the mandrel of the corresponding size as the mandrel used in this pipe fabrication. This can improve production accuracy, optimize mandrel inventory management, and increase the utilization rate of existing mandrel resources.

[0139] The mandrel size determination device of this embodiment includes: establishing a cross-sectional model of the pipe based on the initial mold size, and after meshing the cross-sectional model of the pipe, assigning a shear relaxation modulus function to each mesh element to obtain a viscoelastic model of the pipe; performing deformation simulation on the viscoelastic model based on actual stress and actual temperature field to obtain a deformation model of the pipe; and obtaining the optimized mandrel size based on the comparison results of the cross-sectional model and the deformation model. The solution of this application establishes a cross-sectional model according to the pipe size requirements, and the viscoelastic model can characterize the relaxation modulus of the pipe under shear stress. The environmental conditions of the pipe during the cooling and solidification stage can be extracted through actual stress and actual temperature field, improving the accuracy of deformation simulation and mandrel size adjustment, thereby improving the anti-sagging performance of the pipe.

[0140] Example 3

[0141] Figure 10 is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device includes:

[0142] The electronic device includes a processor 291 and a memory 292; it may also include a communication interface 293 and a bus 294. The processor 291, memory 292, and communication interface 293 can communicate with each other via the bus 294. The communication interface 293 can be used for information transmission. The processor 291 can invoke logical instructions stored in the memory 292 to execute the methods described in the example above.

[0143] Furthermore, the logic instructions in the aforementioned memory 292 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium.

[0144] The memory 292, as a computer-readable storage medium, can be used to store software programs and computer-executable programs, such as program instructions / modules corresponding to the methods in the embodiments of this application. The processor 291 executes functional applications and data processing by running the software programs, instructions, and modules stored in the memory 292, that is, it implements the methods in the above method examples.

[0145] The memory 292 may include a program storage area and a data storage area. The program storage area may store the operating system and application programs required for at least one function; the data storage area may store data created based on the use of the terminal device. Furthermore, the memory 292 may include high-speed random access memory and may also include non-volatile memory.

[0146] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the method in any of the embodiments.

[0147] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the method in any of the embodiments.

[0148] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0149] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for determining the dimensions of a core mold, characterized in that, The mandrel is used as a mold for pipe fabrication, and the method includes: The dimensions of the initial mold are determined according to the pipe size requirements; wherein, the initial mold includes a core mold and a die. Based on the dimensions of the initial mold, a cross-sectional model of the pipe is established, and the cross-sectional model of the pipe is meshed to obtain multiple mesh elements; a shear relaxation modulus function is assigned to each mesh element to obtain the viscoelastic model of the pipe. The actual stress and actual temperature field of the pipe prepared by the extrusion molding process using the initial mold are obtained during the cooling and solidification stage; based on the actual stress and the actual temperature field, the viscoelastic model is subjected to deformation simulation to obtain the deformation model of the pipe; wherein, the actual temperature field characterizes the temperature change of the pipe in different regions after preparation by the extrusion molding process. Based on the comparison results between the cross-sectional model and the deformation model, the dimensions of the core mold in the initial mold are adjusted to obtain the optimized core mold dimensions.

2. The method according to claim 1, characterized in that, The method further includes: Obtain the fixed shear relaxation modulus at different temperatures; The shear relaxation modulus function is established by summing the fixed shear relaxation modulus at different temperatures and at least one temperature-dependent dynamic shear relaxation modulus; the shear relaxation modulus function is: Among them, G e To fix the shear relaxation modulus, G i (t) represents the i-th dynamic shear relaxation modulus, N is the number of dynamic shear relaxation moduli, and t is the cooling time of the pipe; the dynamic shear relaxation modulus is: Among them, g i τ is a fixed component of the i-th dynamic shear relaxation modulus. i Let be the relaxation time under the i-th dynamic shear relaxation modulus.

3. The method according to claim 2, characterized in that, The step of establishing the shear relaxation modulus function by summing the fixed shear relaxation modulus at different temperatures and at least one temperature-dependent dynamic shear relaxation modulus includes: Obtain the shear relaxation modulus values ​​of the material to which the pipe belongs at different temperatures; An exponential function with temperature as the independent variable is used as the fixed component of the shear relaxation modulus, and a quadratic function with temperature as the independent variable is used as the relaxation time. The initial values ​​of the fixed shear relaxation modulus and the number of dynamic shear relaxation moduli are determined to establish an initial shear relaxation modulus function. A loss is established based on the shear relaxation modulus value and the output value of the initial shear relaxation modulus function. If the loss value is less than a threshold, the shear relaxation modulus function is determined. If the loss value is not less than the threshold, the coefficients in the exponential function and the quadratic function, as well as the number of fixed shear relaxation moduli and dynamic shear relaxation moduli, are adjusted until the loss value is less than the threshold.

4. The method according to claim 1, characterized in that, The initial mold has a circular cross-section. The adjustment of the core mold dimensions in the initial mold based on the comparison between the cross-sectional model and the deformation model includes: The relationship between the pipe thickness corresponding to the cross-sectional model and the pipe thickness corresponding to the deformation model is detected in a predetermined direction outward from the center of the circle in the cross-sectional model. If the pipe thickness corresponding to the cross-sectional model in this direction is less than the pipe thickness corresponding to the deformation model, then the radius length of the mandrel in this direction is increased. If the pipe thickness corresponding to the cross-sectional model in that direction is greater than the pipe thickness corresponding to the deformation model, then the radius length of the mandrel in that direction is reduced.

5. The method according to claim 4, characterized in that, The preset directions include: a first direction and a second direction that are parallel to and opposite to the direction of gravity, and a third direction and a fourth direction that are perpendicular to and opposite to the direction of gravity.

6. The method according to claim 1, characterized in that, After obtaining the optimized core mold dimensions, the process further includes: The profile of the cross-section of the core mold is curve-fitted so that the profile is composed of two semi-elliptical curves connected together.

7. The method according to claim 1, characterized in that, After obtaining the optimized core mold dimensions, the process further includes: Based on the current mold size, a current cross-sectional model of the pipe is established, and the current cross-sectional model is meshed. The shear relaxation modulus function is assigned to each mesh cell to obtain the current viscoelastic model. The current mold includes a core mold with optimized core mold size and a die. The test stress and test temperature field of the pipe prepared by the extrusion molding process using the current mold are obtained during the cooling and solidification stage; based on the test stress and the test temperature field, the current viscoelastic model is subjected to deformation simulation to obtain the current deformation model; Determine whether the comparison results between the cross-sectional model obtained based on the initial mold and the current deformation model are consistent. If they are consistent, determine the core mold size; if they are inconsistent, continue to adjust the core mold size.

8. The method according to any one of claims 1 to 7, characterized in that, The method further includes: A database is established, which includes the core mold dimensions corresponding to different preparation information, including the pipe dimensions, pipe material, and pipe preparation temperature.

9. The method according to claim 8, characterized in that, The method further includes: Based on the preparation information of this pipeline, the core mold size that matches the pipeline preparation requirements is determined from the database; Based on the mandrel size that matches the pipeline fabrication requirements, a mandrel of the corresponding size is selected as the mandrel used in this pipeline fabrication.

10. A device for determining the size of a core mold, characterized in that, include: An initial module is used to determine the size of the initial mold according to the size requirements of the pipeline; wherein, the initial mold includes a core mold and a die; The processing module is used to establish a cross-sectional model of the pipe based on the dimensions of the initial mold, and to mesh the cross-sectional model of the pipe to obtain multiple mesh elements; and to assign a shear relaxation modulus function to each mesh element to obtain the viscoelastic model of the pipe. The simulation module is used to acquire the actual stress and actual temperature field of the pipe prepared by the extrusion molding process using the initial mold during the cooling and solidification stage; based on the actual stress and the actual temperature field, the viscoelastic model is used to perform deformation simulation to obtain the deformation model of the pipe; wherein, the actual temperature field characterizes the temperature change of the pipe in different regions after the extrusion molding process. The optimization module is used to adjust the size of the core mold in the initial mold based on the comparison results of the cross-sectional model and the deformation model, so as to obtain the optimized core mold size.

11. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory to implement the method as described in any one of claims 1 to 9.

12. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1 to 9.

13. A computer program product, characterized in that, It includes a computer program that, when executed by a processor, implements the method as described in any one of claims 1 to 9.

Images