Multi-section collaborative dynamic adjustment temperature control system and method

Abstract

The invention provides a multi-section collaborative dynamic adjustment temperature control system and method, and relates to the technical field of multi-section temperature adjusting.According to the multi-section collaborative dynamic adjustment temperature control system and method, division and data acquisition of a screw rod section, a barrel section and a machine head section are achieved through the thermodynamic state of materials of all sections, and after thermodynamic state data of all the sections are obtained, the temperature of the materials of all the sections is obtained; based on shear heat modeling of a compression section, heat source distribution and axial temperature change of a screw area are obtained, a two-dimensional heat conduction model of a barrel section is established, heat flux density in an axial partition structure is continuously solved, flow coupling calculation is further introduced into a machine head area, outlet temperature fluctuation characteristics are extracted, and a heat flow distribution model is established. And finally, by uniformly fusing the output parameters of each section, a dynamic thermal potential energy function is constructed, and the system can realize overall quantification and uniform expression of the thermal state of each temperature control section. The real-time responsiveness and the global heat balance level of the multi-section temperature control system are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-segment temperature regulation, and in particular to a multi-segment coordinated dynamic temperature regulation control system and method. Background Art

[0002] In various continuous thermal processing systems, temperature control systems are a core component for ensuring process stability and product consistency. Traditional industrial equipment commonly employs an "axially segmented" temperature control architecture, dividing the entire thermal processing path into several temperature-controlled zones based on structural function or spatial location. Each zone is equipped with a heater, temperature sensor, and independent control circuit. While this zoned temperature control approach offers a clear structure and facilitates modular design, in actual operation, heat conduction, convection, and flow coupling between zones often cause local temperature changes to generate cross-segment thermal interference effects. Traditional systems lack a unified temperature coordination mechanism, making it difficult to achieve consistent control of the global thermal field. For example, in industrial production lines or energy systems, single temperature control devices often rely on static models, making them difficult to adapt to dynamic load changes and nonlinear thermodynamic coupling effects. This leads to large temperature fluctuations and high energy consumption, and there is a lack of coordinated optimization mechanisms for heat conduction and shear heat feedback across multiple zones. Furthermore, existing technologies are inefficient in the real-time recovery and reuse of heat sources. This is particularly true in scenarios where multiple energy forms are coupled, making it difficult to achieve dynamic distribution and coordinated storage of thermal energy, limiting the overall energy efficiency and stability of the system.

[0003] In the prior art, publication number CN214000522U discloses a twin-screw plastic extruder with multi-stage temperature control and good balance. The extruder's heating system is spatially divided and each heating section is given a relatively independent temperature control mechanism. However, the temperature control logic between different sections is independent of each other, and the adjustment mechanism is manually set in the form of gears or switches. There is a lack of coupling control between cross-segment physical variables such as heat transfer, shear heat accumulation, and flow rate disturbance. Although the system can achieve temperature difference settings in local regulation, it is difficult to capture the thermal dynamic relationship between different heating sections, and it is also impossible to automatically coordinate the real-time balance of cross-segment temperature, which can easily lead to problems such as local overheating, melt instability, increased screw energy consumption, or head pressure difference fluctuations.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0005] The object of the present invention is to provide a multi-segment coordinated dynamic temperature adjustment control system and method to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A multi-segment coordinated dynamic temperature adjustment control system, comprising:

[0008] A data acquisition module is used to divide different areas of the plastic extruder according to the thermodynamic state of the material in each section to obtain multiple sub-areas, wherein the different areas include the screw area, the barrel section and the head area. The screw area is divided into the feeding section, the compression section and the homogenization section. The barrel section is divided into zones 1-4. The head area is divided into zones H1-H3.

[0009] The screw thermal shear conduction modeling module is used to obtain the geometric parameters of the screw zone and the rheological properties of the material. The thermal shear-conduction model is constructed by calculating the shear heat in the compression section of the screw zone. The influence of shear heat power density and axial heat conduction is quantified through the three-dimensional unsteady-state control equation. The axial temperature distribution and shear heat source distribution are output through discrete calculation using the finite difference method.

[0010] The two-dimensional heat transfer module for the cylinder is used to calculate the heat flux density of the cylinder section and construct a two-dimensional heat conduction model of the cylinder section. The two-dimensional cylindrical coordinate heat conduction equation is used to consider the effects of the equidistant arrangement of heating zones and the axial segment coupling. The finite element method is used to solve the radial and axial temperature difference distribution and output a high-precision temperature field.

[0011] The die head fluid-thermal coupling module is used to build a thermal-fluid coupling model in the die head area. Based on the PTT viscoelastic constitutive model, it couples the Navier-Stokes and energy equations to establish a quantitative relationship between shear, dissipation, and heat transfer, and extracts the outlet temperature fluctuation characteristics.

[0012] The thermal potential energy control module is used to integrate the model output parameters of the screw zone, barrel section and head zone, construct a unified dynamic thermal potential energy function to characterize the overall thermal instability of each section, and realize cross-section temperature coordination regulation.

[0013] Furthermore, the screw zone is divided into a feeding section, a compression section and a homogenizing section according to the screw aspect ratio, the barrel section is divided into zones 1-4 according to the length-to-diameter ratio, and the head zone is divided into zones H1-H3 according to the ratio of die lip width to die lip gap. The aspect ratio range of the feeding section is 0-8, the aspect ratio range of the compression section is 8-20, and the aspect ratio range of the homogenizing section is 20-end. The barrel section is divided according to the length-to-diameter ratio, zone 1 is divided into a range of 0-5, zone 2 is divided into a range of 5-15, zone 3 is divided into a range of 15-25, and zone 4 is divided into a range of 25-end. The head zone is divided according to the ratio of die lip width to die lip gap, i.e., die lip ratio, zone H1 is divided into a range of 15-20, zone H2 is divided into a range of 20-30, and zone H3 is divided into a range of 30-50.

[0014] Furthermore, the calculation formula for the shear heat power density of the screw compression section in the screw thermal shear guide modeling module is:

[0015]

[0016] Where Q shear is the shear heat power density, η is the viscosity of the material, D is the screw diameter, N is the screw speed, and h is the fluid layer thickness;

[0017] The viscosity of a material generally decreases with increasing temperature and is characterized by the Arrhenius equation:

[0018]

[0019] Where η(T) is the viscosity of the material at different temperatures T, A and B are constants related to the material properties, and T is the absolute temperature;

[0020] The basic equation for heat conduction is:

[0021]

[0022] Where T is the absolute temperature, α is the thermal diffusivity, ρ is the material density, and c p is the specific heat capacity;

[0023] The calculation formula of thermal diffusivity α is:

[0024]

[0025] Where k is thermal conductivity, ρ is material density, c p is the specific heat capacity.

[0026] Furthermore, the calculation formula of the three-dimensional unsteady-state control equation in the screw thermal shear guide modeling module is:

[0027]

[0028] Where, v s is the axial speed, r is the radial coordinate variable, from the center of the screw outward, h is the thickness of the fluid layer, ρ is the material density, c p is the specific heat capacity;

[0029] The axial velocity v s The calculation formula is:

[0030] v s =πDN

[0031] Where D is the screw diameter and N is the screw speed;

[0032] Simplified to a one-dimensional axial model:

[0033]

[0034] The specific steps of the finite difference method discrete calculation are: divide the screw into M nodes along the axial direction, with a spacing of Δx, and the position of each node is xx i =iΔx(i=0,1,...,M-1), the temperature field is discretized as The time step is t m =mΔt;

[0035] The upwind format is used to discretize the convection term, and the specific formula is:

[0036]

[0037] The central difference method is used to discretize the diffusion term. The specific formula is:

[0038]

[0039] The explicit Euler method is used to discretize the time term. The specific formula is:

[0040]

[0041] Substituting the discrete terms into the original equation, we get the explicit iterative formula:

[0042]

[0043] The explicit discretization needs to satisfy the CFL stability condition and limit the time step Δt:

[0044]

[0045] Where α is the thermal diffusivity, Δx is the distance between screw nodes, and v is s is the axial speed.

[0046] Furthermore, the calculation formula for the heat flux density in the cylinder two-dimensional heat transfer module is:

[0047]

[0048] Where q is the heat flux density, k is the thermal conductivity of the material, is the temperature gradient;

[0049] Using a two-dimensional cylindrical coordinate system (r, z) for modeling, according to Fourier's law and the law of conservation of energy, the calculation formula for the two-dimensional unsteady-state heat conduction control equation in the cylindrical coordinate system (r, z) is:

[0050]

[0051] Where T(r,z,t) is the temperature of a point inside the cylinder that changes with radial position, axial position and time, ρ is the density of the cylinder material, c pis the material specific heat capacity, k is the thermal conductivity, Q(r,z,t) is the internal source term, and the heat source intensity varies with radial position, axial position, and time;

[0052] The calculation formula of the heat flux density at the outer wall boundary is:

[0053]

[0054] where q h (z, t) is the heat flux density function along the axial direction. Considering that the spacing between the heating zones is L and the heating power of each zone is P, then:

[0055]

[0056] Where Pi(t) is the heating power of the cylinder at the i-th section and time t;

[0057] Similarly, the calculation formula for the inner wall boundary heat flux density is:

[0058]

[0059] Where k is the thermal conductivity of the material, h m is the heat transfer coefficient between the material and the inner wall of the cylinder, R0 is the inner radius of the cylinder, which is also the radial position of the material-cylinder contact surface, T(R0,z,t) is the temperature at the corresponding axial position z and time t at the contact point between the inner wall of the cylinder with a radius of R0 and the material, T m (z,t) is the average temperature of the material at the corresponding axial position z and time t.

[0060] Furthermore, in the two-dimensional heat transfer module of the cylinder, the corresponding heat flux density formula is calculated based on the heating power Pi(t) of each heating zone in the i-th section and time t:

[0061]

[0062] Where q i (t) is the heat flux density in the i-th heating zone at time t;

[0063] The heat flux density of each segment is dynamically modified by the following coupling rules:

[0064]

[0065] Where q i (t) set is the heat flux density before correction in the i-th heating zone at time t, γ is the axial temperature difference response coefficient, is the average axial temperature of the i-th segment, T0 is the reference temperature;

[0066] The steps for solving the radial and axial temperature difference distribution using the finite element method are:

[0067] The cylinder is divided into a number of finite axial and radial grid units. The heat source sections are arranged equidistantly in the axial direction, and Nz sections are set. The radial direction is divided into Nr layers from the inner wall R0 to the outer wall R. The control equation is transformed into an integral form by the weighted residual method. The weak form calculation formula of heat conduction is:

[0068]

[0069] Where w is the test function, Ω is the analysis domain, is the temperature gradient, k is the thermal conductivity of the material, and Q is the internal heat source intensity;

[0070] The Crank-Nicolson format is used for time discretization, and the calculation formula is:

[0071]

[0072] Where G is the mass matrix, which is represented by ρc p Weight formation, K is the thermal stiffness matrix, F is the time-varying heat flux density excitation vector, T n 、T n+1 The temperature vectors at the nth and n+1th moments respectively;

[0073] Model output radial temperature difference distribution ΔT r (z, t) = T(R, z, t) - T(R0, z, t), axial temperature difference distribution ΔT z (r,t)=T(r,z i+1 ,t)-T(r,z i ,t).

[0074] Furthermore, the PTT viscoelastic constitutive model in the die head flow-thermal coupling module can accurately describe the shear thinning and elastic effects of polymer melts. The calculation formula is:

[0075]

[0076] Where θ is the deviatoric stress tensor, λ is the relaxation time, and ε is a nonlinear parameter that controls the degree of shear thinning. is the upper body derivative, η is the material viscosity, is the velocity gradient tensor;

[0077] The calculation formula of Navier-Stokes and energy equation is:

[0078]

[0079] Where ρ is the melt density, c p is the specific heat capacity, is the pressure gradient, g is the gravitational acceleration vector, ι is the viscous stress tensor, is the viscous dissipation rate;

[0080] The effect of temperature on viscosity is described by the Arrhenius equation, and the calculation formula is:

[0081]

[0082] Where η(T) is the viscosity of the material at temperature T, η0 is the zero shear viscosity, E is the activation energy, and A is the ideal gas constant.

[0083] Furthermore, the outlet temperature fluctuation characteristic steps in the head flow-heat coupling module are as follows:

[0084] Data sampling: 9 temperature measurement points are arranged at the outlet cross section for sampling; statistical characteristic quantities are counted, and the characteristic quantities include standard deviation, peak value and autocorrelation time. The standard deviation calculation formula is:

[0085]

[0086] The peak-to-peak value calculation formula is:

[0087] ΔT pp =max(T)-min(T)

[0088] The formula for calculating the autocorrelation time is:

[0089]

[0090] Where R(τ) is the autocorrelation function, τ is the time delay, which represents the time difference between two time points;

[0091] The calculation formula of the autocorrelation function R(τ) is:

[0092] R(τ)=E[T(t)·T(t+τ)]

[0093] Where E[·] is the expected value operator;

[0094] Extract the dominant spatial mode of the temperature field and its time coefficient, reconstruct the low-order model, and the calculation formula is:

[0095]

[0096] Where a i (t) is the time coefficient of the intensity of the ith mode changing with time, φ i (r,z) is the basis function at the spatial position (r,z).

[0097] Furthermore, the calculation formula of the dynamic thermal potential energy function in the thermal potential energy control module is:

[0098] U=w1·TSI+w2·TH+w3·FDI

[0099] Where TSI is the heat source intensity, TH is the heat distribution heterogeneity, FDI is the flow disturbance index, w1, w2, and w3 are the weight indices of heat source intensity, heat distribution heterogeneity, and flow disturbance index, respectively;

[0100] The heat source intensity is used to reflect the overall rate at which mechanical energy in the system is converted into thermal energy. The calculation formula is:

[0101]

[0102] Where Q shear is the screw shear heat, Q nominal is the nominal shear heat of the screw, φ is the viscous dissipation of the die head, φ nominal is the nominal dissipation rate of the nose;

[0103] The thermal distribution non-uniformity is used to quantify the spatial non-uniformity of the temperature field in the system. The calculation formula is:

[0104]

[0105] Where, is the axial gradient, is the maximum axial gradient allowed, ΔT r is the radial temperature difference, ΔT crit is the maximum allowable radial temperature difference;

[0106] The flow disturbance index is used to characterize the feedback effect of flow instability on thermal state, and the calculation formula is:

[0107]

[0108] Where σ T is the temperature fluctuation, σ crit is the maximum allowable temperature fluctuation, q x is the axial heat flow, q crit is the critical axial heat flux.

[0109] The present invention also provides a multi-segment coordinated dynamic temperature control method, which is executed by the multi-segment coordinated dynamic temperature control system described above, and specifically comprises the following steps:

[0110] Step 1: Divide different areas of the plastic extruder according to the thermodynamic state of the material in each section to obtain multiple sub-areas, wherein the different areas include the screw area, the barrel section and the head area. The screw area is divided into the feeding section, the compression section and the homogenization section. The barrel section is divided into zones 1-4, and the head area is divided into zones H1-H3.

[0111] Step 2: Obtain the geometric parameters of the screw zone and the material rheological properties data, construct a heat shear-conduction model by calculating the shear heat in the compression section of the screw zone, quantify the effects of shear heat power density and axial heat conduction using a three-dimensional unsteady-state control equation, and output the axial temperature distribution and shear heat source distribution through discrete calculation using the finite difference method;

[0112] Step 3: Calculate the heat flux density of the barrel section and construct a two-dimensional heat conduction model of the barrel section. Use the two-dimensional cylindrical coordinate heat conduction equation to consider the effects of the equidistant arrangement of the heating zones and the axial segment coupling. Use the finite element method to solve the radial and axial temperature difference distributions and output a high-precision temperature field.

[0113] Step 4: Construct a thermal-fluid coupling model for the nose area. Based on the PTT viscoelastic constitutive model, couple the Navier-Stokes and energy equations to establish a quantitative relationship between shear, dissipation, and heat transfer, and extract the outlet temperature fluctuation characteristics.

[0114] Step 5: Integrate the model output parameters of the screw zone, barrel section, and head section to construct a unified dynamic thermal potential energy function to characterize the overall thermal instability of each section and achieve coordinated temperature regulation across sections.

[0115] Compared with the prior art, the present invention has the following beneficial effects:

[0116] The present invention uses the thermodynamic state of the materials in each section to achieve the division and data collection of the screw zone, barrel section, and die section. After obtaining the thermodynamic state data of each section, relying on shear heat modeling of the compression section, the heat source distribution and axial temperature change in the screw zone are obtained. A two-dimensional heat conduction model of the barrel section is established, and the heat flux density within the axial partition structure is continuously solved. Flow coupling calculations are further introduced in the die section to extract the outlet temperature fluctuation characteristics. Finally, by unifying and integrating the output parameters of each section, a dynamic thermal potential energy function is constructed. The system can achieve the overall quantification and unified expression of the thermal state of each temperature-controlled section. This invention effectively improves the real-time responsiveness and global thermal balance level of the multi-segment temperature control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0117] Figure 1 This is a schematic diagram of the system modules of an embodiment of the present invention;

[0118] Figure 2 Schematic diagram of the method flow of an embodiment of the present invention. DETAILED DESCRIPTION

[0119] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0120] It should be noted that, unless otherwise defined, the technical or scientific terms used in the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0121] Example:

[0122] See also Figure 1 , the present invention provides a technical solution:

[0123] A multi-segment coordinated dynamic temperature adjustment control system, comprising:

[0124] The data acquisition module is used to divide the different areas of the plastic extruder according to the thermodynamic state of the material in each section to obtain multiple sub-areas. The different areas include the screw area, the barrel section and the head area. The screw area is divided into the feeding section, the compression section and the homogenization section. The barrel section is divided into zones 1-4, and the head area is divided into zones H1-H3.

[0125] In the data acquisition module, the screw area is divided into a feeding section, a compression section and a homogenizing section according to the screw aspect ratio, the barrel section is divided into zones 1-4 according to the length-to-diameter ratio, and the head area is divided into zones H1-H3 according to the ratio of die lip width to die lip gap. The aspect ratio range of the feeding section is 0-8, the aspect ratio range of the compression section is 8-20, and the aspect ratio range of the homogenizing section is 20-end. The barrel section is divided according to the length-to-diameter ratio, zone 1 is divided into a range of 0-5, zone 2 is divided into a range of 5-15, zone 3 is divided into a range of 15-25, and zone 4 is divided into a range of 25-end. The head area is divided according to the ratio of die lip width to die lip gap, that is, die lip ratio, zone H1 is divided into a range of 15-20, zone H2 is divided into a range of 20-30, and zone H3 is divided into a range of 30-50.

[0126] The German Coperion ZSK 70Mc18 co-rotating twin-screw extruder has a screw diameter of 70 mm, an aspect ratio of 40:1, and a designed capacity of 350 kg per hour. The processed material is a blend of polyvinylidene fluoride and titanium dioxide masterbatch. According to the thermodynamic state evolution law of the material during the extrusion process, the equipment is divided into three functional areas: in the screw area, according to the aspect ratio, it is divided into a feeding section (0-8 times the diameter section, axial length 560 mm), a compression section (8-20 times the diameter section, length 840 mm) and a homogenizing section (20-40 times the diameter section, length 1400 mm) based on the phase change characteristics of the material; in the barrel area, the axial length is equidistant. It is divided into four temperature control zones, corresponding to 0-5 times the diameter (350 mm), 5-15 times the diameter (1050 mm), 15-25 times the diameter (1750 mm) and 25-40 times the diameter (2800 mm); in the die head area, it is divided into H1 boost zone (ratio of 18), H2 steady flow zone (ratio of 25) and H3 diffusion zone (ratio of 40) according to the flow channel expansion characteristics and the ratio of die lip width to gap. The feeding section maintains 160°C to prevent premature melting, the compression section temperature gradually increases from 170°C to 210°C to trigger phase change, and the homogenization section is strictly controlled at 200°C to ensure melt uniformity.

[0127] The screw thermal shear conduction modeling module is used to obtain the geometric parameters and material rheological properties of the screw zone, construct a thermal shear-conduction model by calculating the shear heat of the compression section of the screw zone, quantify the effects of shear heat power density and axial heat conduction through three-dimensional unsteady-state control equations, and output the axial temperature distribution and shear heat source distribution through discrete calculation using the finite difference method.

[0128] The calculation formula for the shear heat power density of the screw compression section in the screw thermal shear guide modeling module is:

[0129]

[0130] Where Q shear is the shear heat power density, η is the viscosity of the material, D is the screw diameter, N is the screw speed, and h is the fluid layer thickness;

[0131] The viscosity of a material generally decreases with increasing temperature and is characterized by the Arrhenius equation:

[0132]

[0133] Where η(T) is the viscosity of the material at different temperatures T, A and B are constants related to the material properties, and T is the absolute temperature;

[0134] The basic equation for heat conduction is:

[0135]

[0136] Where T is the absolute temperature, α is the thermal diffusivity, ρ is the material density, and c p is the specific heat capacity;

[0137] The calculation formula of thermal diffusivity α is:

[0138]

[0139] Where k is thermal conductivity, ρ is material density, c p is the specific heat capacity.

[0140] The calculation formula of the three-dimensional unsteady-state control equation in the screw thermal shear guide modeling module is:

[0141]

[0142] Where, v s is the axial speed, r is the radial coordinate variable, from the center of the screw outward, h is the thickness of the fluid layer, ρ is the material density, c p is the specific heat capacity;

[0143] The axial velocity v s The calculation formula is:

[0144] v s =πDN

[0145] Where D is the screw diameter and N is the screw speed;

[0146] Simplified to a one-dimensional axial model:

[0147]

[0148] The specific steps of the finite difference method discrete calculation are: divide the screw into M nodes along the axial direction, with a spacing of Δx, and the position of each node is xx i =iΔx(i=0,1,...,M-1), the temperature field is discretized as The time step is t m =mΔt;

[0149] The upwind format is used to discretize the convection term, and the specific formula is:

[0150]

[0151] The central difference method is used to discretize the diffusion term. The specific formula is:

[0152]

[0153] The explicit Euler method is used to discretize the time term. The specific formula is:

[0154]

[0155] Substituting the discrete terms into the original equation, we get the explicit iterative formula:

[0156]

[0157] The explicit discretization needs to satisfy the CFL stability condition and limit the time step Δt:

[0158]

[0159] Where α is the thermal diffusivity, Δx is the distance between screw nodes, and v is s is the axial speed.

[0160] When the system starts, the preset partition parameters are first loaded. When the screw runs at 250 rpm, the compression section generates significant shear heat at 10 times the diameter. This heat is calculated using a viscosity model: at a screw groove depth of 8.4 mm, a melt with a viscosity of 850 Pascals per second generates a heat power density of 2.3 million watts per cubic meter. The heat source data is input into a three-dimensional unsteady-state temperature field model, and the explicit finite difference method is used to solve the spatial discretization with an axial step size of 5 mm, a radial step size of 0.7 mm, and a time step size of 0.1 second. The calculation shows that the temperature at the end of the compression section is as high as 208°C, and the axial temperature gradient reaches 15°C per 100 mm. This non-uniform temperature field is then transferred to the barrel heat transfer module.

[0161] The two-dimensional heat transfer module for the cylinder is used to calculate the heat flux density of the cylinder section and construct a two-dimensional heat conduction model of the cylinder section. The two-dimensional cylindrical coordinate heat conduction equation is used to consider the effects of the equidistant arrangement of heating zones and the axial segment coupling. The finite element method is used to solve the radial and axial temperature difference distribution and output a high-precision temperature field.

[0162] The calculation formula for the heat flux density in the two-dimensional heat transfer module of the cylinder is:

[0163]

[0164] Where q is the heat flux density, k is the thermal conductivity of the material, is the temperature gradient;

[0165] Using a two-dimensional cylindrical coordinate system (r, z) for modeling, according to Fourier's law and the law of conservation of energy, the calculation formula for the two-dimensional unsteady-state heat conduction control equation in the cylindrical coordinate system (r, z) is:

[0166]

[0167] Where T(r,z,t) is the temperature of a point inside the cylinder that changes with radial position, axial position and time, ρ is the density of the cylinder material, c pis the material specific heat capacity, k is the thermal conductivity, Q(r,z,t) is the internal source term, and the heat source intensity varies with radial position, axial position, and time;

[0168] The calculation formula of the heat flux density at the outer wall boundary is:

[0169]

[0170] where q h (z, t) is the heat flux density function along the axial direction. Considering that the spacing between the heating zones is L and the heating power of each zone is P, then:

[0171]

[0172] Where Pi(t) is the heating power of the cylinder at the i-th section and time t;

[0173] Similarly, the calculation formula for the inner wall boundary heat flux density is:

[0174]

[0175] Where k is the thermal conductivity of the material, h m is the heat transfer coefficient between the material and the inner wall of the cylinder, R0 is the inner radius of the cylinder, which is also the radial position of the material-cylinder contact surface, T(R0,z,t) is the temperature at the corresponding axial position z and time t at the contact point between the inner wall of the cylinder with a radius of R0 and the material, T m (z,t) is the average temperature of the material at the corresponding axial position z and time t.

[0176] In the two-dimensional heat transfer module of the cylinder, the corresponding heat flux density formula is calculated based on the heating power Pi(t) of each heating zone in the i-th section and time t:

[0177]

[0178] Where q i (t) is the heat flux density in the i-th heating zone at time t;

[0179] The heat flux density of each segment is dynamically modified by the following coupling rules:

[0180]

[0181] Where q i (t) set is the heat flux density before correction in the i-th heating zone at time t, γ is the axial temperature difference response coefficient, is the average axial temperature of the i-th segment, T0 is the reference temperature;

[0182] The steps for solving the radial and axial temperature difference distribution using the finite element method are:

[0183] The cylinder is divided into a number of finite axial and radial grid units. The heat source sections are arranged equidistantly in the axial direction, and Nz sections are set. The radial direction is divided into Nr layers from the inner wall R0 to the outer wall R. The control equation is transformed into an integral form by the weighted residual method. The weak form calculation formula of heat conduction is:

[0184]

[0185] Where w is the test function, Ω is the analysis domain, is the temperature gradient, k is the thermal conductivity of the material, and Q is the internal heat source intensity;

[0186] The Crank-Nicolson format is used for time discretization, and the calculation formula is:

[0187]

[0188] Where G is the mass matrix, which is represented by ρc p Weight formation, K is the thermal stiffness matrix, F is the time-varying heat flux density excitation vector, T n 、T n+1 The temperature vectors at the nth and n+1th moments respectively;

[0189] Model output radial temperature difference distribution ΔT r (z, t) = T(R, z, t) - T(R0, z, t), axial temperature difference distribution ΔT z (r,t)=T(r,z i+1 ,t)-T(r,z i ,t).

[0190] The barrel module uses the screw heat source as the boundary condition and establishes the heat conduction equation in a two-dimensional cylindrical coordinate system. Considering the four-layer composite structure of the barrel (silicon carbide bushing, alloy steel matrix, ceramic heating belt, rock wool insulation layer from the inside to the outside), the finite element method is used for discrete solution, and PID precise control is implemented in the constant temperature homogenization zone of the third zone of the barrel: the proportional gain is set to 8.0, the integral coefficient is 0.2, and the differential coefficient is 1.5. By adjusting the duty cycle of the ceramic heating belt in real time, the axial temperature difference is compressed from the initial ±6°C to ±1.2°C. The optimized temperature field data is then input into the head module.

[0191] The head fluid-thermal coupling module is used to build a thermal-fluid coupling model in the head area. Based on the PTT viscoelastic constitutive model, it couples the Navier-Stokes and energy equations to establish a quantitative relationship between shear, dissipation, and heat transfer, and extracts the outlet temperature fluctuation characteristics.

[0192] The PTT viscoelastic constitutive model in the die head flow-thermal coupling module can accurately describe the shear thinning and elastic effects of polymer melts. The calculation formula is:

[0193]

[0194] Where θ is the deviatoric stress tensor, λ is the relaxation time, and ε is a nonlinear parameter that controls the degree of shear thinning. is the upper body derivative, η is the material viscosity, is the velocity gradient tensor;

[0195] The calculation formula of Navier-Stokes and energy equation is:

[0196]

[0197] Where ρ is the melt density, c p is the specific heat capacity, is the pressure gradient, g is the gravitational acceleration vector, ι is the viscous stress tensor, is the viscous dissipation rate;

[0198] The effect of temperature on viscosity is described by the Arrhenius equation, and the calculation formula is:

[0199]

[0200] Where η(T) is the viscosity of the material at temperature T, η0 is the zero shear viscosity, E is the activation energy, and A is the ideal gas constant.

[0201] The steps for characterizing outlet temperature fluctuation in the head flow-thermal coupling module are as follows:

[0202] Data sampling: 9 temperature measurement points are arranged at the outlet cross section for sampling; statistical characteristic quantities are counted, and the characteristic quantities include standard deviation, peak value and autocorrelation time. The standard deviation calculation formula is:

[0203]

[0204] The peak-to-peak value calculation formula is:

[0205] ΔT pp =max(T)-min(T)

[0206] The formula for calculating the autocorrelation time is:

[0207]

[0208] Where R(τ) is the autocorrelation function, τ is the time delay, which represents the time difference between two time points;

[0209] The calculation formula of the autocorrelation function R(τ) is:

[0210] R(τ)=E[T(t)·T(t+τ)]

[0211] Where E[·] is the expected value operator;

[0212] Extract the dominant spatial mode of the temperature field and its time coefficient, reconstruct the low-order model, and the calculation formula is:

[0213]

[0214] Where a i (t) is the time coefficient of the intensity of the ith mode changing with time, φ i (r,z) is the basis function at the spatial position (r,z).

[0215] The PTT viscoelastic constitutive model for the die head describes the melt behavior. This model introduces a relaxation time parameter λ = 0.35 seconds and an elongation coefficient ε = 0.12. When the melt flows through the H2 steady flow zone at a flow rate of 1.2 meters per minute, calculations show that the viscoelastic dissipation power reaches 180,000 watts per cubic meter, with a theoretical outlet temperature of 205.3°C. However, the infrared thermometer actually detected a fluctuation of ±0.7°C, exceeding the allowable threshold of ±0.5°C. This abnormal signal triggered the thermal potential energy control module.

[0216] The thermal potential energy control module is used to integrate the model output parameters of the screw zone, barrel section and head zone, construct a unified dynamic thermal potential energy function to characterize the overall thermal instability of each section, and realize cross-section temperature coordination regulation.

[0217] The calculation formula of the dynamic thermal potential energy function in the thermal potential energy control module is:

[0218] U=w1·TSI+w2·TH+w3·FDI

[0219] Where TSI is the heat source intensity, TH is the heat distribution heterogeneity, FDI is the flow disturbance index, w1, w2, and w3 are the weight indices of heat source intensity, heat distribution heterogeneity, and flow disturbance index, respectively;

[0220] The heat source intensity is used to reflect the overall rate at which mechanical energy in the system is converted into thermal energy. The calculation formula is:

[0221]

[0222] Where Q shear is the screw shear heat, Q nominal is the nominal shear heat of the screw, Φ is the viscous dissipation of the die head, Φ nominal is the nominal dissipation rate of the nose;

[0223] The thermal distribution non-uniformity is used to quantify the spatial non-uniformity of the temperature field in the system. The calculation formula is:

[0224]

[0225] Where, is the axial gradient, is the maximum axial gradient allowed, ΔT r is the radial temperature difference, ΔT crit is the maximum allowable radial temperature difference;

[0226] The flow disturbance index is used to characterize the feedback effect of flow instability on thermal state, and the calculation formula is:

[0227]

[0228] Where σ T is the temperature fluctuation, σ crit is the maximum allowable temperature fluctuation, q x is the axial heat flow, q crit is the critical axial heat flux.

[0229] The thermal potential energy function incorporates three key parameters: the integrated intensity of shear heat in the screw zone, the maximum temperature gradient in the barrel, and the variance of die head temperature fluctuations. The real-time calculated value was 185.6, exceeding the preset threshold of 180. The system immediately initiated a coordinated adjustment strategy: the screw speed was reduced from 250 rpm to 230 rpm, reducing shear heat by 8%. The set temperature in the third barrel zone was simultaneously increased by 2°C to 202°C to compensate for the increase in melt viscosity caused by the speed reduction. The heating power in the die head H2 zone was also increased by 5%. This coordinated operation stabilized the outlet temperature fluctuation to ±0.3°C within 30 minutes, narrowed the melt pressure fluctuation from ±8% to ±2.5%, and brought the thermal potential energy function value back to the ideal range of 172.3.

[0230] See also Figure 2 The present invention also provides a multi-segment coordinated dynamic temperature control method, which is executed by the multi-segment coordinated dynamic temperature control system described above, and specifically comprises the following steps:

[0231] Step 1: Divide different areas of the plastic extruder according to the thermodynamic state of the material in each section to obtain multiple sub-areas, wherein the different areas include the screw area, the barrel section and the head area. The screw area is divided into the feeding section, the compression section and the homogenization section. The barrel section is divided into zones 1-4, and the head area is divided into zones H1-H3.

[0232] Step 2: Obtain the geometric parameters of the screw zone and the material rheological properties data, construct a heat shear-conduction model by calculating the shear heat in the compression section of the screw zone, quantify the effects of shear heat power density and axial heat conduction using a three-dimensional unsteady-state control equation, and output the axial temperature distribution and shear heat source distribution through discrete calculation using the finite difference method;

[0233] Step 3: Calculate the heat flux density of the barrel section and construct a two-dimensional heat conduction model of the barrel section. Use the two-dimensional cylindrical coordinate heat conduction equation to consider the effects of the equidistant arrangement of the heating zones and the axial segment coupling. Use the finite element method to solve the radial and axial temperature difference distributions and output a high-precision temperature field.

[0234] Step 4: Construct a thermal-fluid coupling model for the nose area. Based on the PTT viscoelastic constitutive model, couple the Navier-Stokes and energy equations to establish a quantitative relationship between shear, dissipation, and heat transfer, and extract the outlet temperature fluctuation characteristics.

[0235] Step 5: Integrate the model output parameters of the screw zone, barrel section, and head section to construct a unified dynamic thermal potential energy function to characterize the overall thermal instability of each section and achieve coordinated temperature regulation across sections.

[0236] The above formulas are all dimensionless and numerical calculations. The formulas are obtained by collecting a large amount of data and performing software simulation to obtain the most recent real situation. The preset parameters in the formulas are set by technicians in this field according to actual conditions.

[0237] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software depends on the specific application and design constraints of the technical solution.

[0238] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment as needed.

[0239] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

Claims

1. A multi-segment coordinated dynamic temperature adjustment control system, characterized in that: include: A data acquisition module is used to divide different areas of the plastic extruder according to the thermodynamic state of the material in each section to obtain multiple sub-areas, wherein the different areas include the screw area, the barrel section and the head area. The screw area is divided into the feeding section, the compression section and the homogenization section. The barrel section is divided into zones 1-4. The head area is divided into zones H1-H3. The screw thermal shear conduction modeling module is used to obtain the geometric parameters of the screw zone and the rheological properties of the material. The thermal shear-conduction model is constructed by calculating the shear heat in the compression section of the screw zone. The influence of shear heat power density and axial heat conduction is quantified through the three-dimensional unsteady-state control equation. The axial temperature distribution and shear heat source distribution are output through discrete calculation using the finite difference method. The two-dimensional heat transfer module for the cylinder is used to calculate the heat flux density of the cylinder section and construct a two-dimensional heat conduction model of the cylinder section. The two-dimensional cylindrical coordinate heat conduction equation is used to consider the effects of the equidistant arrangement of heating zones and the axial segment coupling. The finite element method is used to solve the radial and axial temperature difference distribution and output a high-precision temperature field. The die head fluid-thermal coupling module is used to build a thermal-fluid coupling model in the die head area. Based on the PTT viscoelastic constitutive model, it couples the Navier-Stokes and energy equations to establish a quantitative relationship between shear, dissipation, and heat transfer, and extracts the outlet temperature fluctuation characteristics. The thermal potential energy control module is used to integrate the model output parameters of the screw zone, barrel section and head zone, construct a unified dynamic thermal potential energy function to characterize the overall thermal instability of each section, and realize cross-section temperature coordination regulation.

2. The multi-segment coordinated dynamic temperature control system according to claim 1, characterized in that: In the data acquisition module, the screw area is divided into a feeding section, a compression section and a homogenizing section according to the screw aspect ratio, the barrel section is divided into zones 1-4 according to the length-to-diameter ratio, and the head area is divided into zones H1-H3 according to the ratio of die lip width to die lip gap. The aspect ratio range of the feeding section is 0-8, the aspect ratio range of the compression section is 8-20, and the aspect ratio range of the homogenizing section is 20-end. The barrel section is divided according to the length-to-diameter ratio, zone 1 is divided into a range of 0-5, zone 2 is divided into a range of 5-15, zone 3 is divided into a range of 15-25, and zone 4 is divided into a range of 25-end. The head area is divided according to the ratio of die lip width to die lip gap, i.e., die lip ratio, zone H1 is divided into a range of 15-20, zone H2 is divided into a range of 20-30, and zone H3 is divided into a range of 30-50.

3. The multi-segment coordinated dynamic temperature adjustment control system according to claim 1, characterized in that: The calculation formula for the shear heat power density of the screw compression section in the screw thermal shear guide modeling module is: Where Q shear is the shear heat power density, η is the viscosity of the material, D is the screw diameter, N is the screw speed, and h is the fluid layer thickness; The viscosity of a material generally decreases with increasing temperature and is characterized by the Arrhenius equation: Where η(T) is the viscosity of the material at different temperatures T, A and B are constants related to the material properties, and T is the absolute temperature; The basic equation for heat conduction is: Where T is the absolute temperature, α is the thermal diffusivity, ρ is the material density, and c p is the specific heat capacity; The calculation formula of thermal diffusivity α is: Where k is thermal conductivity, ρ is material density, c p is the specific heat capacity.

4. The multi-segment coordinated dynamic temperature adjustment control system according to claim 3, characterized in that: The calculation formula of the three-dimensional unsteady-state control equation in the screw thermal shear guide modeling module is: Where, v s is the axial speed, r is the radial coordinate variable, from the center of the screw outward, h is the thickness of the fluid layer, ρ is the material density, c p is the specific heat capacity; The axial velocity v s The calculation formula is: v s =πDN Where D is the screw diameter and N is the screw speed; Simplified to a one-dimensional axial model: The specific steps of the finite difference method discrete calculation are: divide the screw into M nodes along the axial direction, with a spacing of Δx, and the position of each node is xx i =iΔx(i=0,1,...,M-1), the temperature field is discretized as The time step is t m =mΔt; The upwind format is used to discretize the convection term, and the specific formula is: The central difference method is used to discretize the diffusion term. The specific formula is: The explicit Euler method is used to discretize the time term. The specific formula is: Substituting the discrete terms into the original equation, we get the explicit iterative formula: The explicit discretization needs to satisfy the CFL stability condition and limit the time step Δt: Where α is the thermal diffusivity, Δx is the distance between screw nodes, and v is s is the axial speed.

5. The multi-segment coordinated dynamic temperature adjustment control system according to claim 1, characterized in that: The calculation formula for the heat flux density in the cylindrical two-dimensional heat transfer module is: Where q is the heat flux density, k is the thermal conductivity of the material, is the temperature gradient; Using a two-dimensional cylindrical coordinate system (r, z) for modeling, according to Fourier's law and the law of conservation of energy, the calculation formula for the two-dimensional unsteady-state heat conduction control equation in the cylindrical coordinate system (r, z) is: Where T(r,z,t) is the temperature of a point inside the cylinder that changes with radial position, axial position and time, ρ is the density of the cylinder material, c p is the material specific heat capacity, k is the thermal conductivity, Q(r,z,t) is the internal source term, and the heat source intensity varies with radial position, axial position, and time; The calculation formula of the heat flux density at the outer wall boundary is: where q h (z, t) is the heat flux density function along the axial direction. Considering that the spacing between the heating zones is L and the heating power of each zone is P, then: Where Pi(t) is the heating power of the cylinder at the i-th section and time t; Similarly, the calculation formula for the inner wall boundary heat flux density is: Where k is the thermal conductivity of the material, h m is the heat transfer coefficient between the material and the inner wall of the cylinder, R0 is the inner radius of the cylinder, which is also the radial position of the material-cylinder contact surface, T(R0,z,t) is the temperature at the corresponding axial position z and time t at the contact point between the inner wall of the cylinder with a radius of R0 and the material, T m (z,t) is the average temperature of the material at the corresponding axial position z and time t.

6. The multi-segment coordinated dynamic temperature control system according to claim 5, characterized in that: In the two-dimensional heat transfer module of the cylinder, the corresponding heat flux density is calculated based on the heating power Pi(t) of each heating zone at the i-th section and time t: Where q i (t) is the heat flux density in the i-th heating zone at time t; The heat flux density of each segment is dynamically modified by the following coupling rules: Where q i (t) set is the heat flux density before correction in the i-th heating zone at time t, γ is the axial temperature difference response coefficient, is the average axial temperature of the i-th segment, T0 is the reference temperature; The steps for solving the radial and axial temperature difference distribution using the finite element method are: The cylinder is divided into a number of finite axial and radial grid units. The heat source sections are arranged equidistantly in the axial direction, and Nz sections are set. The radial direction is divided into Nr layers from the inner wall R0 to the outer wall R. The control equation is transformed into an integral form by the weighted residual method. The weak form calculation formula of heat conduction is: Where w is the test function, Ω is the analysis domain, is the temperature gradient, k is the thermal conductivity of the material, and Q is the internal heat source intensity; The Crank-Nicolson format is used for time discretization, and the calculation formula is: In the formula, G is the mass matrix, which is represented by ρc p Weight formation, K is the thermal stiffness matrix, F is the time-varying heat flux density excitation vector, T n 、T n+1 The temperature vectors at the nth and n+1th moments respectively; Model output radial temperature difference distribution ΔT r (z, t) = T(R, z, t) - T(R0, z, t), axial temperature difference distribution ΔT z (r,t)=T(r,z i+1 ,t)-T(r,z i ,t).

7. The multi-segment coordinated dynamic temperature adjustment control system according to claim 1, characterized in that: The PTT viscoelastic constitutive model in the die head flow-thermal coupling module can accurately describe the shear thinning and elastic effects of polymer melts. The calculation formula is: Where θ is the deviatoric stress tensor, λ is the relaxation time, and ε is a nonlinear parameter that controls the degree of shear thinning. is the upper body derivative, η is the material viscosity, is the velocity gradient tensor; The calculation formula of Navier-Stokes and energy equation is: Where ρ is the melt density, c p is the specific heat capacity, is the pressure gradient, g is the gravitational acceleration vector, ι is the viscous stress tensor, is the viscous dissipation rate; The effect of temperature on viscosity is described by the Arrhenius equation, and the calculation formula is: Where η(T) is the viscosity of the material at temperature T, η0 is the zero shear viscosity, E is the activation energy, and A is the ideal gas constant.

8. The multi-segment coordinated dynamic temperature control system according to claim 7, characterized in that: The steps for characterizing the outlet temperature fluctuation in the head flow-thermal coupling module are as follows: Data sampling: 9 temperature measurement points are arranged on the outlet section for sampling; Statistical features include standard deviation, peak value and autocorrelation time. The standard deviation is calculated as follows: The peak-to-peak value calculation formula is: ΔT pp =max(T)-min(T) The formula for calculating the autocorrelation time is: Where R(τ) is the autocorrelation function, τ is the time delay, which represents the time difference between two time points; The calculation formula of the autocorrelation function R(τ) is: R(τ)=E[T(t)·T(t+τ)] Where E[·] is the expected value operator; Extract the dominant spatial mode of the temperature field and its time coefficient, reconstruct the low-order model, and the calculation formula is: Where a i (t) is the time coefficient of the intensity of the ith mode changing with time, φ i (r,z) is the basis function at the spatial position (r,z).

9. The multi-segment coordinated dynamic temperature adjustment control system according to claim 1, characterized in that: The calculation formula of the dynamic thermal potential energy function in the thermal potential energy regulation module is: U=w1·TSI+w2·TH+w3·FDI Where TSI is the heat source intensity, TH is the heat distribution heterogeneity, FDI is the flow disturbance index, w1, w2, and w3 are the weight indices of heat source intensity, heat distribution heterogeneity, and flow disturbance index, respectively; The heat source intensity is used to reflect the overall rate at which mechanical energy in the system is converted into thermal energy. The calculation formula is: Where Q shear is the screw shear heat, Q nominal is the nominal shear heat of the screw, Φ is the viscous dissipation of the die head, Φ nominal is the nominal dissipation rate of the nose; The thermal distribution non-uniformity is used to quantify the spatial non-uniformity of the temperature field in the system. The calculation formula is: Where, is the axial gradient, is the maximum axial gradient allowed, ΔT r is the radial temperature difference, ΔT crit is the maximum allowable radial temperature difference; The flow disturbance index is used to characterize the feedback effect of flow instability on thermal state, and the calculation formula is: Where σ T is the temperature fluctuation, σ crit is the maximum allowable temperature fluctuation, q x is the axial heat flow, q crit is the critical axial heat flux.

10. A multi-segment coordinated dynamic temperature control method, characterized by: The method is performed by the multi-segment coordinated dynamic temperature adjustment control system according to any one of claims 1 to 9, and the specific steps include: Step 1: Divide different areas of the plastic extruder according to the thermodynamic state of the material in each section to obtain multiple sub-areas, wherein the different areas include the screw area, the barrel section and the head area. The screw area is divided into the feeding section, the compression section and the homogenization section. The barrel section is divided into zones 1-4, and the head area is divided into zones H1-H3. Step 2: Obtain the geometric parameters of the screw zone and the material rheological properties data, construct a heat shear-conduction model by calculating the shear heat in the compression section of the screw zone, quantify the effects of shear heat power density and axial heat conduction using a three-dimensional unsteady-state control equation, and output the axial temperature distribution and shear heat source distribution through discrete calculation using the finite difference method; Step 3: Calculate the heat flux density of the barrel section and construct a two-dimensional heat conduction model of the barrel section. Use the two-dimensional cylindrical coordinate heat conduction equation to consider the effects of the equidistant arrangement of the heating zones and the axial segment coupling. Use the finite element method to solve the radial and axial temperature difference distributions and output a high-precision temperature field. Step 4: Construct a thermal-fluid coupling model for the nose area. Based on the PTT viscoelastic constitutive model, couple the Navier-Stokes and energy equations to establish a quantitative relationship between shear, dissipation, and heat transfer, and extract the outlet temperature fluctuation characteristics. Step 5: Integrate the model output parameters of the screw zone, barrel section, and head section to construct a unified dynamic thermal potential energy function to characterize the overall thermal instability of each section and achieve coordinated temperature regulation across sections.

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