Mpp pipe extrusion molding equipment based on temperature dynamic adjustment

Abstract

The present application relates to the field of plastic extrusion molding machinery, in particular to MPP pipe extrusion molding equipment based on temperature dynamic adjustment, which comprises a cylinder, a screw, a die head, a traction mechanism, a controller and a double thermal response ring assembly arranged in the core rod; the system obtains the displacement increment of the two thermal response rings with different thermal response time constants in the non-melt channel area of the core rod through a displacement transmitter; the core is that the controller generates a rapid heat index according to the displacement increment and the radial displacement response lag time of the two thermal response rings, and dynamically adjusts the screw speed in combination with the melt pressure, the traction speed and the pipe blank outer diameter; the present application converts heat change into mechanical deformation measurement, avoids the damage of melt flow line and the initiation of local carbon deposition caused by the direct insertion of the probe into the channel, and effectively decouples external heating and internal shear heating by using the double thermal response time constant structure, which significantly improves the timeliness of transient heat change perception.

Description

Technical Field

[0001] This invention relates to the field of plastic extrusion molding machinery and equipment, specifically to MPP pipe extrusion molding equipment based on dynamic temperature regulation. Background Technology

[0002] In the current field of polymer pipe extrusion molding, the temperature state of the polymer melt is affected by both external barrel heating and internal screw shear heating, directly determining the molding quality of extruded products such as MPP pipes. To monitor the melt temperature, existing solutions generally adopt traditional temperature measurement architectures, which involve indirectly obtaining temperature data by attaching a temperature probe to the outer wall of the barrel or directly inserting the probe into the melt flow channel for contact measurement. Although the wall-attached measurement scheme has the ability to sense the reference temperature under steady-state conditions, it cannot detect the transient shear heat accumulation inside the melt caused by sudden changes in screw speed in real time due to the heat transfer lag phenomenon, which can easily lead to adjustment overshoot and temperature oscillation. On the other hand, the method of inserting the probe directly into the flow channel will disrupt the continuity of melt flow and disturb the melt flow lines, causing local carbon buildup and thermal degradation of materials, making it difficult to support high-frequency extrusion process intervention and precise control of the outer diameter of the tube blank.

[0003] Therefore, how to improve the timeliness of sensing transient heat changes and the accuracy of dynamic adjustment in the extrusion process without disrupting the melt flow pattern has become an urgent technical problem to be solved. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides an MPP tube extrusion molding device based on dynamic temperature regulation. Specifically, the technical solution of the present invention is as follows: The MPP tube extrusion molding equipment based on dynamic temperature control includes: The machine includes a frame, a traction mechanism, and a controller. A screw, connected to the main drive motor, rotates within the barrel. The die head is fixed to the discharge end of the barrel. A mandrel is coaxially positioned within the die head, forming an annular melt channel. The non-melt flow channel region of the mandrel is a section offset axially from the annular melt channel, not participating in its formation and not directly contacting the melt flowing through it. This mandrel section is thermally connected to the annular melt channel via the mandrel body. Within this section, a first thermal response ring is thermally connected to the mandrel via a first thermally conductive shoulder, and the first thermal response ring is in direct contact with the first thermally conductive shoulder. A second thermal response ring is thermally connected to the mandrel via a second thermally conductive shoulder. A heat insulation element is sandwiched between the second thermally conductive shoulder and the second thermal response ring, and the thermal response time constant of the first thermal response ring is smaller than that of the second thermal response ring. The outer circles of the first thermal response ring and the second thermal response ring respectively abut against the first transmission rod and the second transmission rod that move radially along the mandrel. The first transmission rod and the second transmission rod respectively abut against the first displacement transmitter and the second displacement transmitter. The die head is equipped with a melt pressure transmitter, the traction mechanism is equipped with a traction speed encoder, and the feed side of the traction mechanism is equipped with a billet outer diameter detector. The feed side is the side of the traction mechanism facing the die head outlet. The controller is connected to the first displacement transmitter, the second displacement transmitter, the melt pressure transmitter, the traction speed encoder, the billet outer diameter detector, and the main drive motor. It generates a rapid thermal index based on the difference between the corrected displacement increment of the first thermal response loop in the same sampling window and the corrected displacement increment of the second thermal response loop after alignment according to the radial displacement response lag time in the same sampling window. The screw speed is adjusted in combination with the melt pressure, screw speed, traction speed, and billet outer diameter.

[0005] In a preferred embodiment, the mandrel is provided with a first annular step and a second annular step; wherein, the first thermal response ring is a thin-walled stainless steel ring sleeved on the outer periphery of the first annular step, and the first thermal response ring and the first annular step are in a transition fit; wherein, the second thermal response ring is a nickel-chromium alloy ring sleeved on the outer periphery of the second annular step, the wall thickness of the second thermal response ring is greater than the wall thickness of the first thermal response ring, and an annular thermal insulation gap is formed between the second thermal response ring and the second annular step.

[0006] In a preferred embodiment, the annular heat insulation gap is filled with alumina ceramic particles, which are confined within the annular heat insulation gap by a thin-walled stainless steel retaining ring; wherein, an alumina ceramic heat insulation element is disposed between the second thermally conductive shoulder and the second thermal response ring; wherein, the first thermally conductive shoulder is in direct contact with the first thermal response ring.

[0007] In a preferred embodiment, the outer wall of the die head is provided with two radial guide holes, and a linear guide sleeve is fixed in each radial guide hole; wherein, the first transmission rod and the second transmission rod are slidably inserted into the corresponding linear guide sleeves; the inner ends of the first transmission rod and the second transmission rod are threadedly connected to spherical heads, and the spherical heads abut against the outer circles of the first thermal response ring and the second thermal response ring respectively; wherein, the first transmission rod and the second transmission rod are each fitted with a preload spring, and the two ends of the preload spring abut against the corresponding linear guide sleeve and the spherical head respectively.

[0008] In a preferred embodiment, both the first displacement transmitter and the second displacement transmitter are differential inductive displacement transmitters and are fixed to the same support plate; wherein, the support plate is connected to the frame via a transverse slide and a vertical slide, the transverse slide being used to adjust the support plate radially along the barrel; the vertical slide being used to adjust the height of the first displacement transmitter and the second displacement transmitter; wherein, the support plate is provided with a limit screw, the limit screw being located on the movement path of the first transmission rod and the second transmission rod.

[0009] In a preferred embodiment, a heating coil and a cooling duct are fixed to the outer periphery of the barrel, and the cooling duct is connected to a cooling fan and a proportional air valve. The controller is connected to the power controller of the heating coil, the cooling fan, and the proportional air valve. When the rapid heat index increases and the displacement trend of the second thermal response ring does not continue to increase, the controller reduces the screw speed and limits the increase in cooling airflow. When the displacements of both thermal response rings continue to increase, the controller increases the speed of the cooling fan and the opening of the proportional air valve, and reduces the output power of the heating coil. When neither the rapid heat index nor the displacement trend of the second thermal response ring increases, the controller maintains the current screw speed and the current output power of the heating coil.

[0010] In a preferred embodiment, the controller records the first displacement zero point of the first displacement transmitter and the second displacement zero point of the second displacement transmitter at a cold reference temperature; and obtains the thermal response time difference between the first thermal response loop and the second thermal response loop; The controller is configured with a sampling window for acquiring signals; wherein the controller processes the displacement data of the first thermal response loop and the second thermal response loop within the sampling window to generate the rapid thermal index.

[0011] In a preferred embodiment, the controller determines the sampling window based on the screw speed, traction speed, and billet outer diameter; and filters the same-direction displacement signals of the first thermal response ring and the second thermal response ring according to the set sampling window.

[0012] In a preferred embodiment, the controller generates a calculated process temperature for the melt contact region based on the corrected displacement of the first thermal response loop, the hysteresis corrected displacement of the second thermal response loop, the barrel outer wall temperature, and pre-calibrated material expansion parameters including the thermal expansion coefficient of the components themselves, and determines the temperature rise trend based on the continuous change of the calculated process temperature; the controller generates a heat accumulation index based on the temperature rise trend and the rapid heat index.

[0013] In a preferred embodiment, when the heat accumulation index exceeds the heat intervention threshold, the controller reduces the screw speed in a segmented ramp manner; wherein, when the outer diameter of the tube blank decreases, the controller reduces the traction speed of the traction mechanism and limits the reduction range of the screw speed; wherein, when the melt pressure increases and the outer diameter of the tube blank increases, the controller increases the traction speed under the condition that the calculated process temperature is lower than the process warning value; the controller controls the recovery of the screw speed according to the falling rapid heat index.

[0014] The present invention has the following beneficial effects: 1. This invention sets up a first thermal response ring and a second thermal response ring with different thermal response time constants in the non-melt flow channel region of the mandrel. The displacement increment is obtained by a displacement transmitter and a transmission rod, and the controller generates a rapid thermal index. This design converts the change in melt heat into a measurement of mechanical deformation, avoiding the problems of probes directly inserting into the flow channel, damaging the melt flow lines, and causing local carbon buildup. At the same time, the dual thermal response time constant structure effectively decouples external heating from internal shear heating, improving the timeliness of sensing transient heat changes.

[0015] 2. The controller of this invention adjusts the screw speed by combining rapid heat indicators with melt pressure, screw speed, traction speed, and billet outer diameter, and coordinates the heating coil power and cooling air volume under different heat accumulation states. This solution can accurately identify and distinguish between screw shear heating and overall heat storage states, and selectively call up speed, cooling, or heating adjustments, overcoming the over-adjustment and temperature oscillation problems caused by heat transfer lag in traditional wall-mounted temperature measurement, and effectively ensuring the molding quality and dimensional consistency of extruded products. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the overall external structure of the device; Figure 2 This is a schematic diagram of the barrel structure; Figure 3 This is a schematic diagram of the mold head structure; Figure 4 This is a schematic diagram of the thermal response loop; Figure 5 This is a schematic diagram of the mandrel structure; Figure 6 yes Figure 1 A magnified view of a portion of point A in the middle.

[0017] In the diagram: 1. Frame; 2. Barrel; 3. Screw; 4. Main drive motor; 5. Die head; 6. Mandrel; 7. Annular melt channel; 8. Traction mechanism; 9. First thermal response ring; 10. Second thermal response ring; 11. First annular step; 12. Second annular step; 13. First thermally conductive shoulder; 14. Second thermally conductive shoulder; 15. Thermal insulation component; 16. Annular thermal insulation gap; 17. Alumina ceramic particles; 18. Thin-walled stainless steel retaining ring; 19. Alumina ceramic thermal insulation pad; 20. First transfer rod; 21. Second transfer rod; 22. Linear guide sleeve; 23. Spherical mandrel; 24. Preload spring; 25. First displacement transmitter; 26. Second displacement transmitter; 27. Support plate; 28. Horizontal slide; 29. ​​Vertical slide; 30. Limit screw. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0019] Example 1: Please refer to Figures 1 to 6 An MPP tube extrusion molding device based on dynamic temperature control, comprising: The frame 1, traction mechanism 8 and controller, the screw 3 which is rotatably connected to the main drive motor 4 is installed inside the barrel 2, the die head 5 is fixed to the discharge end of the barrel 2, and the mandrel 6 is coaxially installed inside the die head 5 and the two form an annular melt channel 7. The non-melt flow channel region of the mandrel 6 is a section of the mandrel 6 that is offset from the annular melt channel 7 in the axial direction, does not participate in the formation of the annular melt channel 7, and does not directly contact the melt flowing through the annular melt channel 7. This section of the mandrel 6 is thermally connected to the annular melt channel 7 through the body of the mandrel 6. In this section of the mandrel 6, the first thermal response ring 9 is thermally connected to the mandrel 6 through the first thermally conductive shoulder 13, and the first thermal response ring 9 is in direct contact with the first thermally conductive shoulder 13. The second thermal response ring 10 is thermally connected to the mandrel 6 through the second thermally conductive shoulder 14. The heat insulation member 15 is sandwiched between the second thermally conductive shoulder 14 and the second thermal response ring 10, and the thermal response time constant of the first thermal response ring 9 is smaller than the thermal response time constant of the second thermal response ring 10. The outer circles of the first thermal response ring 9 and the second thermal response ring 10 respectively abut against the first transmission rod 20 and the second transmission rod 21 that move radially along the core rod 6, and the first transmission rod 20 and the second transmission rod 21 respectively abut against the first displacement transmitter 25 and the second displacement transmitter 26. The die head 5 is equipped with a melt pressure transmitter, the traction mechanism 8 is equipped with a traction speed encoder, and the feed side of the traction mechanism 8 is equipped with a billet outer diameter detector. The feed side is the side of the traction mechanism 8 facing the discharge port of the die head 5. The controller is connected to the first displacement transmitter 25, the second displacement transmitter 26, the melt pressure transmitter, the traction speed encoder, the billet outer diameter detector, and the main drive motor 4. It generates a rapid heat index based on the difference between the corrected displacement increment of the first thermal response loop 9 in the same sampling window and the corrected displacement increment of the second thermal response loop 10 after alignment with the radial displacement response lag time in the same sampling window. It combines the melt pressure, screw speed 3, traction speed, and billet outer diameter to adjust the screw speed 3.

[0020] In the existing technology, the melt temperature of the extruded pipe is affected by the combined heating of the external barrel 2 and the internal shear heating of the screw 3. The conventional measurement method of attaching the temperature probe to the outer wall of the barrel 2 has the phenomenon of heat transfer lag and cannot detect the accumulation of internal shear heat in the melt caused by the sudden change of the screw speed. On the other hand, the method of directly inserting the probe into the melt flow channel will disrupt the melt flow line and cause local carbon buildup. To address the aforementioned issues, this embodiment proposes an MPP tube extrusion molding device based on dynamic temperature control. The device includes a frame 1, a barrel 2, a screw 3, a main drive motor 4, a die 5, a mandrel 6, a traction mechanism 8, and a controller. The screw 3 is rotatably mounted inside the barrel 2, and the main drive motor 4 is connected to the screw 3 to output rotational power. The die 5 is fixed to the discharge end of the barrel 2, and the mandrel 6 is coaxially mounted inside the die 5. An annular melt channel 7 for polymer passage is formed between the outer circumferential surface of the mandrel 6 and the inner circumferential surface of the die 5. A first thermal response ring 9 and a second thermal response ring 10 are provided in the non-melting flow channel region of the mandrel 6. The first thermal response ring 9 is heat-transferringly connected to the mandrel 6 through a first thermally conductive shoulder 13, and the first thermal response ring 9 is in direct contact with the first thermally conductive shoulder 13. The second thermal response ring 10 is heat-transferringly connected to the mandrel 6 through a second thermally conductive shoulder 14, and a heat insulation element 15 is sandwiched between the second thermally conductive shoulder 14 and the second thermal response ring 10. Due to the difference in heat transfer path and medium, the thermal response time constant of the first thermal response ring 9 is smaller than that of the second thermal response ring 10, causing the two thermal response rings to undergo asynchronous radial expansion in response to temperature changes from the same heat source. The thermal response time constant is the thermal response time constant of the thermal response ring after being heated and causing radial thermal expansion displacement. The start time of the step temperature rise is denoted as... , No. The stable radial displacement of each thermal response ring is ,when At that time, the thermal response time constant is ;in, Corresponding to the first thermal response ring (9). Corresponding to the second thermal response ring (10), and ; The outer circles of the first thermal response ring 9 and the second thermal response ring 10 respectively abut against the first transmission rod 20 and the second transmission rod 21, which move radially along the mandrel 6; the first transmission rod 20 and the second transmission rod 21 respectively abut against the first displacement transmitter 25 and the second displacement transmitter 26, converting the thermal expansion deformation of the first thermal response ring 9 and the second thermal response ring 10 into continuous electrical signals; the die head 5 is equipped with a melt pressure transmitter, the traction mechanism 8 is equipped with a traction speed encoder, and the feed side of the traction mechanism 8 is equipped with a billet outer diameter detector; control The device is connected to each of the above-mentioned detection elements and the main drive motor 4 respectively; the melt pressure transmitter is installed in the radial mounting hole of the die head 5, and its pressure measuring end is connected to the annular melt channel 7, and the pressure measuring end face is flush with the inner wall of the annular melt channel 7 formed by the die head 5; the traction speed encoder is connected to the traction drive shaft of the traction mechanism 8 for outputting the traction speed signal; the tube blank outer diameter detector is fixed on the side of the traction mechanism 8 facing the discharge port of the die head 5, and its detection direction is perpendicular to the tube blank axis and towards the outer circle of the tube blank, for outputting the tube blank outer diameter signal.

[0021] The controller acquires the corrected displacement increment of the first thermal response loop 9 within the same sampling window and the corrected displacement increment of the second thermal response loop 10 within the same sampling window after alignment according to the radial displacement response lag time. The difference between the two is used as a rapid thermal index that can reflect transient thermal changes. Combined with the real-time status of melt pressure, screw speed 3, traction speed and billet outer diameter, the controller sends a speed adjustment command to the main drive motor 4. This scheme converts the melt heat change into the mechanical deformation of the internal components of the die head 5, avoiding direct contact between the temperature measuring element and the high-temperature melt. At the same time, the dual thermal response time constant structure effectively decouples external heating and internal shear heating.

[0022] The mandrel 6 is provided with a first annular step 11 and a second annular step 12; wherein, the first thermal response ring 9 is a thin-walled stainless steel ring sleeved on the outer periphery of the first annular step 11, and the first thermal response ring 9 and the first annular step 11 are in transition fit; wherein, the second thermal response ring 10 is a nickel-chromium alloy ring sleeved on the outer periphery of the second annular step 12, the wall thickness of the second thermal response ring 10 is greater than the wall thickness of the first thermal response ring 9, and an annular thermal insulation gap 16 is formed between the second thermal response ring 10 and the second annular step 12.

[0023] The first thermal expansion coefficient of the first thermal response ring 9 is greater than the second thermal expansion coefficient of the second thermal response ring 10. The wall thickness of the first thermal response ring 9 makes its heat capacity less than that of the second thermal response ring 10. The transition fit ensures that the heat on the surface of the mandrel 6 is conducted to the first thermal response ring 9, so that it follows the temperature fluctuation of the melt contact area. The second thermal response ring 10 is a nickel-chromium alloy ring sleeved on the outer periphery of the second annular step 12. The wall thickness of the second thermal response ring 10 is greater than the wall thickness of the first thermal response ring 9. An annular heat insulation gap 16 is formed between the second thermal response ring 10 and the second annular step 12. The nickel-chromium alloy has thermal stability that meets the preset standard, and the set wall thickness increases its own heat capacity. By comprehensively configuring material properties, structural dimensions, and assembly gaps, the response speed of the second thermal response ring 10 to temperature changes is lower than that of the first thermal response ring 9. Its radial expansion displacement reflects the overall steady-state heat storage level of the mold head 5. This structural differentiation design lays the necessary physical foundation for the subsequent controller to distinguish heat sources of different properties.

[0024] The annular heat insulation gap 16 is filled with alumina ceramic particles 17, which are confined within the annular heat insulation gap 16 by a thin-walled stainless steel retaining ring 18; an alumina ceramic heat insulation element 15 is provided between the second thermally conductive shoulder 14 and the second thermal response ring 10; and the first thermally conductive shoulder 13 is in direct contact with the first thermal response ring 9.

[0025] The annular thermal insulation gap 16 is filled with alumina ceramic particles 17. Alumina ceramic material has intrinsic thermal conductivity, but in this embodiment, it is filled in the annular thermal insulation gap 16 in the form of a loose particle layer. Discontinuous contact interfaces and non-contact air gaps are formed between the particles and between the particles and the adjacent wall surfaces, so that the equivalent thermal conductivity of the particle layer is lower than that of a continuous dense ceramic structure. The filling density and particle size of the particles are selected according to the required thermal response time constant, and their axial and circumferential movement is restricted by a thin-walled stainless steel retaining ring 18; an alumina ceramic insulation element 15 is provided between the second thermally conductive shoulder 14 and the second thermal response ring 10. The insulation element and the particle layer together constitute a controlled thermal resistance, rather than using the alumina ceramic particles 17 themselves as a low thermal conductivity bulk. The first thermally conductive shoulder 13 is in direct contact with the first thermally responsive ring 9; the above connection structure makes the first thermally responsive ring 9 and the second thermally responsive ring 10 form different heat transfer paths; the heat transfer path of the first thermally responsive ring 9 is all-metal direct conduction, exhibiting low thermal resistance and low delay characteristics; the heat transfer path of the second thermally responsive ring 10 connects the particle layer, the annular air gap and the thermal insulation pad in series, exhibiting thermal resistance and thermal delay characteristics within a set range. The controller obtains the response time difference between the two paths through temperature calibration, and uses the calibration result as the basis for subsequent displacement signal time correction. The unique consideration of this technique is that by constructing a controlled physical thermal resistance, the complex temperature field change inside the mold head 5 is transformed into two displacement signals with a clear phase difference, thereby filtering out high-frequency thermal disturbances and making the second thermal response loop 10 a stable thermal state reference.

[0026] The outer wall of the die head 5 is provided with two radial guide holes, and a linear guide sleeve 22 is fixed in each radial guide hole; wherein, the first transmission rod 20 and the second transmission rod 21 are slidably inserted into the corresponding linear guide sleeve 22; the inner ends of the first transmission rod 20 and the second transmission rod 21 are threadedly connected to a spherical top 23, and the spherical top 23 abuts against the outer circle of the first thermal response ring 9 and the second thermal response ring 10 respectively; wherein, the first transmission rod 20 and the second transmission rod 21 are both fitted with a preload spring 24, and the two ends of the preload spring 24 abut against the corresponding linear guide sleeve and the spherical top 23 respectively.

[0027] The outer wall of the mold head 5 is provided with two radial guide holes, and a linear guide sleeve 22 is fixed in each radial guide hole; the first transmission rod 20 and the second transmission rod 21 are respectively slidably inserted into the corresponding linear guide sleeve 22; the linear guide sleeve 22 restricts the motion freedom of the transmission rod, ensuring that it can only undergo linear displacement along the radial direction of the mandrel 6, avoiding torsion or lateral displacement caused by mechanical vibration; the inner end of each transmission rod is threaded with a spherical dome 23, and the spherical dome 23 abuts against the outer circle of the corresponding thermal response ring; The spherical contact method can accommodate axial deformation or assembly form and position errors within the tolerance range generated by the thermal response ring during expansion, preventing the transmission rod from getting stuck. Each transmission rod is equipped with a preload spring 24, and the elastic force of the preload spring 24 is directed towards the center of the mandrel 6, so that the spherical top 23 always maintains close contact with the thermal response ring. This structure eliminates transmission gaps and ensures that the contraction displacement of the thermal response ring can also be accurately transmitted to the outside.

[0028] The first displacement transmitter 25 and the second displacement transmitter 26 are both differential inductive displacement transmitters and are fixed to the same support plate 27. The support plate 27 is connected to the frame 1 through a horizontal slide 28 and a vertical slide 29. The horizontal slide 28 is used to adjust the support plate 27 radially along the barrel 2. The vertical slide 29 is used to adjust the height of the first displacement transmitter 25 and the second displacement transmitter 26. The support plate 27 is provided with a limit screw 30, which is located on the movement path of the first transmission rod 20 and the second transmission rod 21.

[0029] The first displacement transmitter 25 and the second displacement transmitter 26 are both differential inductive displacement transmitters and are fixed to the same support plate 27. The support plate 27 is connected to the frame 1 through a transverse slide 28 and a vertical slide 29. The transverse slide 28 is used to adjust the reference position of the support plate 27 radially along the barrel 2, and the vertical slide 29 is used to adjust the height of the two displacement transmitters to ensure that their measuring axes coincide with the axis of the transmission rod. The support plate 27 is provided with a limit screw 30, which is located on the movement path of the corresponding transmission rod and is used to limit the maximum radial displacement of the transmission rod. By integrating two displacement transmitters on the same support plate 27, the mechanical vibration generated by the operation of the frame 1 or the thermal deformation caused by the change of ambient temperature will be superimposed on the output signals of the two transmitters in the form of common mode interference. In subsequent data processing, the controller can effectively identify and eliminate the common-mode mechanical noise by comparing the synchronous changes of the two channels, thereby improving the signal-to-noise ratio of the measurement of minute thermal deformation. The limit screw 30 forms a physical boundary protection to prevent the thermal response loop from over-expanding and damaging the precision displacement transmitter under extreme conditions.

[0030] Example 2: A heating coil and a cooling air duct are fixed to the outer periphery of the barrel 2. The cooling air duct is connected to a cooling fan and a proportional air valve. The controller is connected to the power controller of the heating coil, the cooling fan, and the proportional air valve. When the rapid heat index increases and the displacement trend of the second thermal response ring 10 does not continue to increase, the controller reduces the speed of the screw 3 and limits the increase in cooling air volume. When the displacement of both thermal response rings continues to increase, the controller increases the speed of the cooling fan and the opening of the proportional air valve, and reduces the output power of the heating coil. When neither the rapid heat index nor the displacement trend of the second thermal response ring 10 increases, the controller maintains the current speed of the screw 3 and the current output power of the heating coil.

[0031] A heating coil and a cooling air duct are fixed on the outer periphery of the barrel 2. The cooling air duct is connected to a cooling fan and a proportional air valve. The controller is connected to the power controller of the heating coil, the cooling fan and the proportional air valve respectively. When the heat index rises rapidly and the displacement trend of the second thermal response ring 10 does not continue to increase, the controller determines that the current heat increase is mainly due to local shear heating caused by the sudden change in the speed of the screw 3. At this time, the controller outputs a command to reduce the speed of the screw 3 and limit the increase in cooling air volume to avoid excessive external cooling causing a sudden drop in the surface temperature of the die head 5 and triggering melt rupture. When the displacement of both thermal response loops continues to increase, the controller determines that the current mold head 5 is in a state of heat storage caused by excessive external heating. At this time, the controller outputs a command to increase the speed of the cooling fan and the opening of the proportional air valve to accelerate the heat dissipation on the surface of the mold head 5 and simultaneously reduce the output power of the heating coil. Through the above control logic, the equipment can selectively call speed adjustment, cooling adjustment or heating adjustment according to the physical properties of the heat source, avoiding the over-adjustment and temperature oscillation common in traditional single temperature feedback control.

[0032] The controller records the first displacement zero point of the first displacement transmitter and the second displacement zero point of the second displacement transmitter at a cold reference temperature; and acquires the thermal response time difference between the first thermal response loop 9 and the second thermal response loop 10; the controller is configured with a sampling window for acquiring signals; wherein, the controller processes the displacement data of the first thermal response loop 9 and the second thermal response loop 10 within the sampling window to generate a rapid thermal index.

[0033] The controller records the first displacement zero point of the first displacement transmitter and the second displacement zero point of the second displacement transmitter when the equipment is at a set cold reference temperature, eliminating static deviations caused by mechanical assembly tolerances. At the same time, the controller converts the outputs of the two channels into the same displacement dimension based on the sensitivity calibration results of the two displacement transmitters, so as to avoid fixed deviations in rapid thermal indicators caused by differences in transmitter gain. During the phased heating process of the equipment, the controller continuously collects signals from the two displacement transmitters and simultaneously records the outer wall temperature of the barrel 2, the melt pressure, the screw speed 3, the traction speed, the outer diameter of the billet, and the load of the main drive motor 4. All data are written into the controller's cyclic data cache according to a unified sampling clock. When calibrating the time difference, screw 3 is kept at a stop or a preset low constant speed state, the traction speed remains unchanged, the cooling fan and proportional air valve maintain a fixed output, and the melt pressure is kept within a preset stable range; the same heating power change method and holding time are used in each heating stage to avoid the periodic pressure pulsation, drive vibration and cooling air volume change of screw 3 being mistaken for heat transfer lag. At least 300 sampling points should be continuously collected for each heating stage, and the calibration should be repeated for no less than 5 heating stages; each heating stage should be repeated at least 3 times, and the data of the same stage should only be used as valid calibration data if the time difference of the same stage does not exceed 10% of the average value of the stage. The stable deformation state refers to the state in which the displacement change of the thermal response rings is within the allowable fluctuation range within a consecutive preset number of sampling periods. The controller records the moment when the two thermal response rings first reach this state, and repeatedly acquires the corresponding time difference in multiple heating stages. When the time difference in each stage is within the preset allowable deviation range, the controller uses the median of multiple effective time differences as the hysteresis correction parameter and stores it. Let the moments when the first thermal response ring 9 and the second thermal response ring 10 first reach the stable deformation state in the same heating stage be respectively... and The radial displacement response hysteresis time is The hysteresis correction parameter has multiple effective parameters. the median; If the time difference of a certain stage exceeds the allowable deviation range, or if there are sudden changes in the melt pressure, screw speed of screw 3 and outer wall temperature of barrel 2 that are not caused by the heating setting, the data of that stage will not be used to update the hysteresis correction parameters, thereby avoiding time correction distortion caused by heating disturbance or measurement abnormality; the time difference characterizes the equivalent dynamic hysteresis characteristics of the specific structure of die head 5 and the second heat transfer path relative to the first heat transfer path within the calibrated operating range, and is not used as a material constant that remains unchanged after leaving the operating range; During the initial calibration phase, the controller uses a metrologically calibrated temperature reference device to compare the temperature of the outer wall of the barrel 2 in stages, and records the stable output of the two displacement channels at at least three temperature calibration points; the zero displacement point, displacement sensitivity, and time difference parameters are determined through the calibration data. During the on-site calibration phase, a verification is performed under three conditions: no-load cold state, low-speed heating, and stable production. If the deviation between the verification result and the factory calibration value exceeds the preset allowable range, the controller will prohibit updating the rapid thermal index and prompt for readjustment of the contact preload of the displacement transmitter and the transmission rod or the position of the support plate 27. This calibration process does not rely on neural network training or manual sample annotation. The rapid thermal index is directly generated from the collected displacement data according to the predetermined time alignment rules and incremental calculation rules. The controller receives the continuous displacement signals output by the first displacement transmitter 25 and the second displacement transmitter 26, and first subtracts the corresponding cold displacement zero point to obtain the corrected displacement sequence of the first thermal response loop 9 and the original corrected displacement sequence of the second thermal response loop 10. The controller aligns the second displacement sequence forward along the time axis according to the hysteresis correction parameter, so that the response time of the second thermal response loop 10 under the same thermal change corresponds to that of the first thermal response loop 9; when the correction parameter falls between two sampling times, time interpolation is performed based on the displacement values ​​of adjacent sampling points to obtain a hysteresis correction displacement sequence with the same time base as the first displacement signal. Forward alignment is performed causally through a circular data cache, without calling data that has not been collected since the current moment: when the hysteresis correction parameter is a preset time length, after the controller obtains the subsequent response of the second displacement channel, it generates a rapid heat index corresponding to the moment before the preset time length. Therefore, this index has a known and fixed calculation delay. For windows that lack complete data after time alignment, the controller does not generate a rapid heat index temporarily, but calculates it after a complete sampling window is formed, without using extrapolated values ​​to supplement future data. The controller then calculates the displacement increments of the two aligned displacement sequences between the start and end points of the same sampling window, and subtracts the second displacement increment from the first displacement increment to obtain the rapid thermal index. Taking a sampling period of 100ms and a hysteresis correction parameter of 250ms as an example, after obtaining the second displacement data for the subsequent 250ms, the controller aligns the second displacement channel forward by two complete sampling periods and interpolates adjacent sampling points for the remaining 50ms to generate an index belonging to the corresponding time before 250ms. When the displacement increment of the first thermal response loop 9 within a sampling window is 18μm and the corrected displacement increment of the second thermal response loop 10 is 11μm, the rapid thermal index is 7μm. Let the first displacement after zero-point correction be... According to the lag correction parameter The second displacement after time alignment is ,but , The rapid calorie index is ; Since the heat transfer path of the first thermal response ring 9 is relatively short, the rapid heat input is reflected as the increase of the first displacement increment relative to the second displacement increment; while the continuous heat storage caused by external heating will be reflected in both displacement increments after hysteresis correction; therefore, the positive increase of this index indicates that the deformation growth of the rapid thermal response ring is faster than that of the second thermal response ring 10, which represents the overall heat storage state, and can be used as a judgment quantity for the enhancement of transient heat input. Through the above processing, zero-point calibration solves static assembly deviations, sensitivity unification solves channel gain differences, time alignment solves the main phase difference between the two heat transfer paths within the calibration dynamic range, and window increment calculation filters out slow changes in absolute displacement. Considering that the two heat transfer paths are not ideal pure time delay elements, the controller also saves the applicable heating rate, screw speed, melt pressure and sampling window range for the time difference parameter; if the rate of heat change or pressure pulsation frequency in production exceeds the calibration range, or if the steady-state deviation of the two channels after time alignment continuously exceeds the allowable value, the controller does not recognize that the fixed time difference can complete the effective correction, suspends the automatic speed reduction based on the rapid heat index, and switches to a conservative control state constrained by the melt pressure, billet outer diameter and process temperature limits, until the operating state returns to the calibration range or the time difference calibration is completed again; To verify the effectiveness of time difference correction and rapid heat index, external heating test, screw speed step test and repeated heating test were carried out during the equipment calibration and factory inspection stages. In the external heating test, the screw speed, melt pressure and traction speed were kept stable, and the deviation of the stable state of the two displacement channels before and after time alignment for the same heating process was checked. In the screw speed step test, the output of the heating coil is kept constant, and the sequential response of the first displacement channel relative to the second displacement channel and the direction of change of the rapid heat index are recorded when the speed changes. In the repeated heating test, the same heating power change method is repeated at least 3 times, and the repeatability of time difference, displacement increment difference and steady-state deviation is compared. The controller only enables the rapid thermal index when the time difference repeatability, steady-state deviation, and response direction all meet the preset verification range. If the index generated by the external heating test continues to deviate from zero, or if the speed step test does not show the first displacement channel priority response, the calibration or transmission mechanism is judged to be abnormal and automatic adjustment is prohibited. The above tests establish repeatable verification standards for time correction, heat source differentiation, and index stability, and do not directly use unverified fixed time differences as general parameters under all operating conditions.

[0034] The controller determines the sampling window based on the screw speed, traction speed and outer diameter of the tube blank; and filters the same-direction displacement signals of the first thermal response ring 9 and the second thermal response ring 10 according to the set sampling window.

[0035] The controller dynamically determines the sampling window for calculating the displacement increment based on the screw speed, traction speed and outer diameter of the tube blank; the sampling period is determined by the controller's unified clock, preferably 50ms to 200ms; the initial value of the sampling window is called from the calibration table corresponding to the current tube specification, and the calibration table records at least the screw speed range, traction speed range, tube blank outer diameter range, tube wall thickness range and the corresponding window length; The controller uses linear interpolation between adjacent calibration points to obtain the current window length, and limits the calculation result to between the preset shortest and longest windows to avoid sudden changes in window length due to instantaneous sensor anomalies; the current sampling window length is denoted as... The controller uses the current screw speed traction speed and the outer diameter of the tube blank As an index, linear interpolation is used to obtain the values ​​between adjacent calibration points. and make it satisfy When the screw speed increases, the melt shear rate increases and heat accumulation accelerates. The controller then shortens the sampling window to improve the sensitivity of capturing transient heat. When the screw speed decreases or the melt pressure stabilizes, the system dynamic characteristics become slower, and the controller extends the sampling window to smooth out high-frequency noise. For thin-walled pipes, due to their small heat capacity and sensitivity to temperature fluctuations, the sampling window used by the controller is shorter than that used for thick-walled pipes. The sampling window calibration data comes from the continuous operation data of the equipment during the MPP pipe extrusion production process, including the first displacement transmitter 25, the second displacement transmitter 26, the melt pressure transmitter, the traction speed encoder, the billet outer diameter detector, the screw speed feedback signal, and the main drive motor 4 load signal. For each pipe specification, data from at least three stable production batches should be collected, with each batch continuously collected for no less than 30 minutes. During the calibration process, the preset operating ranges of low speed, rated speed, and above rated speed should be covered respectively, and the signal changes under stable outer diameter and temperature disturbance conditions should be recorded. The determination of this sampling window is a deterministic process based on rules and calibration parameters, and it does not require the establishment of a neural network or the training of a model with manually labeled samples. The abnormal records used to verify the mechanical vibration recognition effect must meet the following preset conditions: the two displacement channels change synchronously in the same direction, the duration is less than the current sampling window, and there are no corresponding changes in melt pressure and barrel 2 outer wall temperature; these records are only used to confirm the threshold and window parameters and are not used as input for uninterpretable classification models. The rotation of screw 3, the output torque fluctuation of main drive motor 4, the eccentricity of screw 3, and the pulsation of melt pressure will generate periodic mechanical excitation near the rotational frequency and its multiples of screw 3. There may also be relative displacement between frame 1 and die head 5. In order to make the same-direction changes in the two displacement channels represent common mechanical disturbances, after the axis adjustment is completed, the transverse slide 28 and the vertical slide 29 are locked, and the measuring axes of the two displacement transmitters are made to coincide with the axes of the corresponding transmission rods. The two displacement transmitters, support plate 27 and their connecting parts adopt the same installation stiffness. The first natural frequency of support plate 27 avoids the normal rotational frequency of screw 3 and its main harmonics. The vibration amplitude, phase difference and duration of the two channels are recorded in three states: cold no-load, screw 3 at graded constant speed and constant heating power. Based on this, the synchronization time tolerance, the range of the same direction change amplitude ratio and the minimum effective vibration amplitude are determined. The parameters enable mechanical vibration identification to be based on the rotation boundary conditions of the equipment, rather than the absolute stillness of the mold head 5 and the frame 1. During the displacement signal preprocessing stage, the controller compares the real-time data sequences of the first displacement channel and the second displacement channel. When the controller detects a synchronous displacement change in the two displacement channels with a duration less than the sampling window, it first checks whether the change is accompanied by changes in melt pressure, barrel 2 outer wall temperature, or screw 3 load. Only when the start time of the change in both channels is within the calibrated synchronization time tolerance, the amplitude ratio is within the calibrated range, the duration is less than the current sampling window, and no corresponding thermal or load state change occurs, is it determined that the change originates from the mechanical vibration interference of the support plate 27, the mold head 5, or the frame 1. If two channels change in the same direction, but the phase difference, amplitude ratio, or duration does not meet the above conditions, or if any of the signals of melt pressure, barrel 2 outer wall temperature, and screw 3 load shows a time-related change, then the data segment is retained as a possible real process response and is not rejected based solely on the single condition of changing in the same direction. The controller marks the confirmed mechanical vibration data segments as invalid data and skips the corresponding sampling points when calculating the rapid thermal index; the skipped data is not filled by long-distance interpolation across the vibration segment to avoid converting periodic jumps into false slow displacement trends. When invalid data continuously exceeds the preset ratio, the controller pauses the output of rapid thermal indicators and generates sensor or mechanical vibration check signals instead of continuing to use incomplete data for speed regulation; the above short-time common mode identification rules do not apply to low-frequency rack 1 oscillations that last for a duration equal to or exceeding the sampling window, or high-frequency vibrations that exceed the effective bandwidth of the sampling system. In this state, the controller pauses automatic adjustment based on rapid thermal indicators and prompts for checking the fastening status of support plate 27, the eccentricity of screw 3, the connection of mold head 5, and the sampling filter settings. The configuration of the dynamic sampling window, combined with the common-mode interference identification calibrated by the rotational operating condition, takes into account both the real-time response and anti-interference robustness of the control algorithm.

[0036] The controller generates the estimated process temperature of the melt contact area based on the corrected displacement of the first thermal response ring 9, the hysteresis corrected displacement of the second thermal response ring 10, the outer wall temperature of the barrel 2, and the pre-calibrated material expansion parameters including the thermal expansion coefficient of the components themselves. The controller also determines the temperature rise trend based on the continuous change of the estimated process temperature. The controller generates a heat accumulation index based on the temperature rise trend and the rapid heat index.

[0037] The controller receives the corrected displacement of the first thermal response loop 9, the hysteresis corrected displacement of the second thermal response loop 10, and the outer wall temperature of the barrel 2. The outer wall temperature of the barrel 2 is collected by a temperature sensor fixed to the non-melting contact area on the outer periphery of the barrel 2. The temperature sensor is attached to the outer wall of the barrel 2 through a thermally conductive mounting base and connected to the controller. A heat insulation structure is set between the temperature sensor and the heating coil to reduce the direct influence of the heating coil radiation on the measurement results. The controller acquires the temperature signal at the same sampling clock as the displacement signal and converts it into the reference temperature of the outer wall of the barrel 2 according to the calibration compensation value corresponding to the sensor installation position; the corrected displacement is obtained by subtracting the cold displacement zero point from the real-time output of the corresponding displacement transmitter and calibrating the channel sensitivity; the hysteresis corrected displacement is obtained by time alignment of the corrected displacement of the second thermal response loop 10 according to the pre-recorded time difference. The pre-calibrated material expansion parameters, including the component's own thermal expansion coefficient, include at least the thermal expansion coefficients, effective size parameters, and corresponding initial temperature references of the first thermal response ring 9, the second thermal response ring 10, the thermally conductive shoulder, and the core rod 6; these parameters are obtained by calibrating each component under known temperature conditions and stored in the controller. The outer wall temperature of barrel 2, the two displacement channels and the melt pressure signal are all marked with the sampling time. The controller only performs temperature conversion on the data that are in the same valid sampling window and are not marked by mechanical vibration interference. If any input signal is missing, out of bounds or does not meet the continuity requirements, the calculated process temperature will not be updated temporarily. The measured position of the thermal response ring, in addition to the thermal expansion of the ring itself, may also include the thermal deformation of the mandrel 6, the die head 5, the transmission rod and the support structure, as well as the elastic deformation caused by the melt pressure acting on the mandrel 6. In order to avoid directly interpreting the above mechanical deformation as temperature change, the effective dimensional parameters adopt the equivalent parameters of the whole machine after assembly, rather than just the free expansion dimensions of the thermal response ring material. The entire machine is calibrated in at least three stable melt pressure ranges, and the changes in the two displacement channels corresponding to the pressure changes under the same temperature conditions are recorded to form the elastic deformation compensation value for each pressure range. During production, the controller calls the compensation value of the corresponding pressure range according to the current signal of the melt pressure transmitter, and deducts the quasi-static elastic deformation confirmed by calibration before displacement conversion. When the pressure change rate or pressure pulsation amplitude exceeds the calibration range, the temperature conversion of that displacement segment is not performed, and the estimated process temperature is marked as temporarily invalid. The processing logic used to generate the estimated process temperature includes a global temperature branch and a local heat input branch that work together. The global temperature branch receives the hysteresis correction displacement of the second thermal response loop 10 and the outer wall temperature of the barrel 2, which is used to characterize the temperature change caused by external heating and overall heat storage of the die head 5. The local heat input branch receives the displacement difference between the first thermal response loop 9 and the second thermal response loop 10 at the same time reference, which is used to characterize the rapid temperature rise of the melt contact area relative to the overall temperature state. The controller first uses the temperature of the outer wall of the barrel 2 and the displacement of the second thermal response ring 10 to make a baseline correction for the common temperature change caused by external heating. Then, it uses the difference between the first thermal response ring 9 and the second thermal response ring 10 to compensate for local rapid heat input. Combined with the calibrated material expansion parameters and effective size parameters, the displacement change is converted into the temperature change of the melt contact area relative to the baseline state, and added to the baseline temperature to form the estimated process temperature. The above processing logic does not directly use the uncalibrated displacement value as temperature, but completes the conversion from displacement to temperature through a correspondence established by known temperature calibration data; the correspondence includes at least the following processing steps: zero-point correction, material expansion response, effective structural dimensions, pressure elastic deformation compensation, and temperature compensation of the outer wall of barrel 2. The controller calls the corresponding calibration parameters according to the current pipe specifications and melt pressure range, and performs segmented table lookup or interpolation between adjacent calibration points for inputs within the calibration range; when the input exceeds the calibration range of temperature, pressure or operating speed, the controller marks the calculation result as out of bounds and uses the upper limit of temperature or conservative boundary to participate in the subsequent heat intervention judgment, so as to avoid using the extrapolated result of the out-of-range as the basis for normal temperature. Before the equipment leaves the factory, a contact or non-contact temperature reference device that has been calibrated by metrology is used to compare and calibrate the non-melt flow channel area of ​​the mandrel 6 and the outer wall of the barrel 2 at at least three representative temperature points; each temperature point is maintained until the first thermal response ring 9 and the second thermal response ring 10 reach a stable state, and no less than 300 sets of synchronous data are continuously collected; for each MPP pipe specification, at least 3 sets of repeated calibration data are saved, and the corresponding pipe wall thickness, screw speed 3, traction speed and melt pressure range are recorded; Since the temperature in the non-melt flow channel area cannot be directly equivalent to the temperature of the melt contact area under all operating conditions, a detachable flush-type temperature reference probe is installed at a position that does not change the effective contour of the annular melt channel 7 during equipment finalization or initial field calibration. The reference temperature of the melt contact area is obtained under low speed, rated speed and preset high load conditions. After calibration, the reference probe is removed and the flow channel surface is restored with a flush-type sealing component. The controller uses the data of the reference temperature, two displacement channels, outer wall temperature of barrel 2 and corresponding pressure range to establish a segmented calibration relationship, so that the calculated process temperature corresponds to the extrusion thermal boundary conditions, rather than just the static uniform heating conditions. During on-site deployment, the calibration parameters are checked under three states: no-load cold state, low-speed stable extrusion, and target specification stable extrusion. If the deviation between the displacement-converted temperature and the temperature reference device exceeds the preset calibration tolerance, the time difference repeatability of the two thermal response loops does not meet the requirements, or the repeated displacement deviation under the same temperature and pressure conditions exceeds the allowable range, the controller will determine the calibration state as invalid, stop the automatic thermal intervention based on the calculated process temperature, and prompt for recalibration. The estimated process temperature is a process state estimate limited to the calibrated temperature, pressure, screw speed, and cooling conditions, and is not used as the absolute melt temperature measurement value after deviating from the boundary conditions; the heat accumulation index is generated using deterministic hierarchical weighting rules and is not obtained through neural networks or data-driven models whose internal computational logic is not visible. The controller first divides the degree of deviation of the rapid heat index from the production baseline, the continuous increase in the estimated process temperature, the change in melt pressure, and the change in the load of the main drive motor 4 by the corresponding baseline fluctuation range to obtain four dimensionless deviations. Then, initial weights are set to 0.40, 0.25, 0.20, and 0.15 in the order of rapid heat index, temperature change, melt pressure, and motor load, and only positive deviations exceeding the corresponding allowable fluctuation range are accumulated to form a heat accumulation index. The dimensionless positive deviations of the rapid heat index, estimated process temperature, melt pressure, and main drive motor 4 load are denoted as follows: and The heat accumulation index is then... ; When using this system, the weights and thresholds are determined by continuous data from the stable production phase and thermal anomaly records verified on-site. Stable production data must cover at least three production batches, with each batch lasting no less than 30 minutes. Thermal anomaly records are confirmed by the following criteria: rapid heat index increases continuously over multiple sampling windows, and at least one of the following increases simultaneously: screw speed, main drive motor load, or melt pressure. Manual verification is only used to confirm production baselines, thresholds, and anomaly records and is not used for model training. Taking the current specification's rapid heat index benchmark fluctuation range as 5μm, the estimated process temperature allowable rise range as 2℃, the melt pressure allowable fluctuation range as 0.5MPa, and the main drive motor 4 load allowable fluctuation range as 5% as an example, when the four positive deviations are 10μm, 1℃, 0.25MPa, and 2.5%, respectively, the four normalized deviations are 2, 0.5, 0.5, and 0.5, respectively. According to the above weights, the heat accumulation index is calculated to be 1.1. The controller compares this index with the heat intervention threshold corresponding to the current pipe specification and enters the normal state, warning state, or heat intervention state based on the comparison result. The controller calculates the direction and degree of temperature change based on the estimated process temperature over multiple consecutive control cycles. When subsequent values ​​are continuously higher than the value of the previous control cycle and exceed the allowable fluctuation range, an upward temperature trend is determined. When the temperature change is within the allowable fluctuation range, the original trend is maintained. When the temperature is lower than the previous cycle for multiple consecutive cycles and exceeds the fallback judgment limit, the upward temperature trend is canceled. This avoids the measurement noise of a single sampling point triggering the heat accumulation judgment. When generating the heat accumulation index, the controller first reads the rapid heat index, calculates the continuous change in process temperature, the melt pressure transmitter signal, and the load signal of the main drive motor 4, and compares them with the production baseline corresponding to the current specification to obtain the deviation direction and degree of each signal. The controller performs dimensionless processing according to the reference fluctuation range corresponding to each signal to avoid the dimensional differences of displacement, temperature, pressure and motor load affecting the judgment result; then, it sets weights according to the indicative role of rapid heat index, temperature rise trend, melt pressure change and motor load change on heat accumulation, and classifies and merges them according to the deviation direction to form a heat accumulation index. The production baseline is determined by the rapid heat index, estimated process temperature, melt pressure and motor load data continuously collected by the equipment under stable molding conditions, and is saved separately according to the pipe specifications and normal production conditions; the heat accumulation index is used to compare with the heat intervention threshold and as the input for subsequent screw 3 speed reduction and molding state constraints. When the rapid heat index continuously increases within multiple consecutive sampling windows, and at least one of the screw speed, main drive motor load, or melt pressure increases synchronously, the controller will identify the rapid heat input as shear heating; when the rapid heat index does not increase but only the outer wall temperature of the barrel 2 changes, it will not be judged as shear heating based solely on this change. If the displacement change is synchronous with the melt pressure pulsation and no longer shows a continuous increase after pressure elastic deformation compensation, it is identified as a mechanical load response and not used as a basis for shear heating. Therefore, the controller uses the priority response of the first thermal response loop 9 to the rapid heat input, the hysteretic response of the second thermal response loop 10 to the overall heat storage, and the causal relationship between pressure and drive load and shear input of screw 3 to distinguish the source of rapid heat input and transmit the identification result to the heat intervention control module. The controller executes data acquisition, validity judgment, temperature conversion, trend judgment, index generation, and status output in the following order: The data acquisition module forms a data group with timestamps using a unified sampling clock. The data group includes at least two displacement channels, melt pressure, barrel 2 outer wall temperature, screw 3 speed, traction speed, billet outer diameter, and main drive motor 4 load; The validity judgment module generates valid data flags based on missing flags, out-of-bounds flags, mechanical vibration flags, and calibration range flags. The temperature conversion module only processes valid data and outputs the estimated process temperature with a valid temperature flag; the trend judgment module counts the data of continuous control cycles and only changes the temperature upward trend state when the preset number of continuous cycles is reached; the index generation module outputs the heat accumulation index and its state level according to the baseline, fluctuation range, weight and deviation direction of each input. The status level and valid data flag are written to the cyclic data buffer along with the exponent and transmitted to the subsequent speed control module, so that invalid data will not be mistakenly used as zero value in the accumulation, and each control command can be traced back to the corresponding input data group. To verify the reliability of the calculated process temperature and heat accumulation index, stable temperature rise, screw speed step, melt pressure step, and cooling air volume change tests were set up during the factory calibration and on-site verification stages. The stable temperature rise test was used to check the correspondence between the calculated process temperature and the temperature reference device. The screw speed step test is used to check the shear heating identification results when the rapid heat index changes synchronously with the motor load or melt pressure; the melt pressure step test is used to verify that the pressure elastic deformation compensation will not continuously generate a temperature rise trend; the cooling air volume change test is used to check that changes in external thermal state will not be identified as shear heating on its own. Each test is repeated at least 3 times, and the temperature conversion deviation, index direction consistency, anomaly identification repeatability, and steady-state deviation are used as verification items. If any item exceeds the preset allowable range, the controller will set the corresponding calibration status to invalid and stop the automatic heat intervention with that parameter. Thus, the calculation of process temperature and heat accumulation index have clear input, processing sequence, output flags, and repeatable verification conditions.

[0038] When the heat accumulation index exceeds the heat intervention threshold, the controller reduces the speed of screw 3 in a segmented ramp manner. Specifically, when the outer diameter of the tube blank decreases, the controller reduces the traction speed of the traction mechanism 8 and limits the speed reduction of screw 3. When the melt pressure increases and the outer diameter of the tube blank increases, the controller increases the traction speed under the condition that the calculated process temperature is lower than the process warning value. The controller controls the recovery of the screw 3 speed based on the rapid heat index.

[0039] The controller monitors the heat accumulation index in real time; when the heat accumulation index exceeds the set heat intervention threshold, the controller initiates the intervention program; when... At that time, the controller enters the first deceleration phase, in which The threshold for heat intervention; the first The screw speed at the beginning of the deceleration stage is: The pre-calibrated slope rate is The duration is The given rotational speed of screw 3 is... ,in The speed reduction in this section is: ,and , The values ​​are determined based on the pre-calibrated limits corresponding to the current screw speed, melt pressure stability, and billet outer diameter deviation; after each speed reduction stage, if and If it continues to rise, it will enter the next deceleration phase; if If the ascent stops and the outer diameter of the tube blank needs adjustment, then the traction speed should be adjusted; if If the temperature drops back to the production baseline range, the system will enter a recovery observation state. The heat intervention threshold is determined based on the stable production data of the equipment under the target pipe specification, the allowable process temperature range of the material, and the heat accumulation index before the outer diameter fluctuation, and is set to a value higher than the upper limit of the normal production baseline fluctuation. At the same time, a release threshold lower than the heat intervention threshold is set so that the intervention start and release have a hysteresis range, avoiding repeated switching of control state when the heat accumulation index fluctuates near the critical value. The controller gradually reduces the speed of screw 3 according to the predetermined segmented ramp. After each segment of speed reduction is completed, a state evaluation time of more than one control cycle is reserved, and the controller decides whether to enter the next speed reduction segment based on the changes in rapid heat index, melt pressure and billet outer diameter. The execution of the speed reduction phase has priority: when the rapid heat index and heat accumulation index are still rising, the shear input of screw 3 is restricted first; only when the heat index stops rising and the billet size needs to be corrected, the traction speed adjustment is performed; thus avoiding the simultaneous screw 3 speed reduction and traction speed change exceeding the set speed reduction threshold in the same control cycle, reducing the shear mechanical energy applied to the melt and avoiding sudden changes in flow rate caused by a one-time speed reduction. During the deceleration process, the controller synchronously reads the continuous measurement value of the tube blank outer diameter detector and compares it with the allowable outer diameter range corresponding to the current tube specification. The reduction in the outer diameter of the tube blank indicates a change in the forming flow rate or the mold filling state. At this time, the controller reduces the traction speed of the traction mechanism 8 and limits the deceleration range of the screw 3 within the current control cycle to within the preset maximum change. The maximum change is determined based on the current screw speed (3), melt pressure stability, and billet outer diameter deviation. This is to prevent excessive screw speed reduction from causing insufficient billet supply and further size reduction. After the traction speed adjustment is completed, the controller retains a size observation window, waiting for the billet outer diameter change to stabilize before deciding whether to continue adjusting. At that time, the traction speed setpoint is taken as When the melt pressure continuously increases, Furthermore, when the calculated process temperature is lower than the process warning value, the traction speed setpoint is taken as follows: ;in, and These are the lower and upper limits of the permissible outer diameter, respectively. The preset single traction speed change, and meets the following requirements. ; When the melt pressure increases for several consecutive control cycles and the outer diameter of the tube blank increases synchronously, the controller determines that the melt output is blocked or the forming material accumulation is increasing. At this time, the controller first compares the estimated process temperature with the process warning value. The process warning value is determined based on the allowable processing temperature of MPP material, equipment calibration error and process window of target product, and is used to limit the operation of continuing to increase the traction speed under high temperature conditions. The controller increases the traction speed only when the estimated process temperature is below the process warning value, the rapid heat index does not continue to rise, and the upward trend of the melt pressure does not reach the pressure protection limit. After the increase, the changes in melt pressure and tube blank outer diameter are re-observed. If the estimated process temperature reaches or exceeds the process warning value, or the rapid heat index continues to rise, the relevant drive amount is maintained or reduced to avoid further heat accumulation caused by size adjustment. When the rapid heat index falls back to the production baseline range, the displacement trend of the second thermal response loop 10 stops increasing, the melt pressure remains stable, and the outer diameter of the billet returns to the allowable range, the controller determines that the risk of thermal runaway is eliminated. The production baseline range is determined by the average value of the rapid heat index and its allowable fluctuation range during the stable production phase. The displacement trend of the second thermal response loop 10 stops increasing when its displacement increment within a consecutive preset number of sampling windows does not exceed the trend judgment limit. Stable melt pressure means that the pressure change is within the allowable fluctuation range for multiple consecutive control cycles. After the above conditions are met, the controller gradually increases the speed of screw 3 according to the predetermined recovery slope. After each increase in speed, the thermal response observation window is retained. When the rapid heat index, the displacement trend of the second thermal response ring 10, the melt pressure and the outer diameter of the billet do not exceed the limit, the next speed increase is executed. If any heat or size status in the observation window exceeds the corresponding limit again, the controller immediately stops the speed increase and returns to the intervention state. The execution logic of this multivariate constraint ensures that the heat suppression action, traction speed adjustment and screw speed recovery are coordinated and executed in the order of thermal state priority and dimensional state follow, so as to suppress thermal degradation and ensure dimensional consistency in continuous extrusion production. The controller stores the normal production state, early warning state, heat intervention state, recovery observation state and fault conservative state as control status flags, and calls the corresponding speed change limit, traction speed change limit and observation window length according to the status flags. Under normal production conditions, the system enters an early warning state only when the heat accumulation index continuously exceeds the warning threshold. In the early warning state, the controller reduces the allowable screw speed variation and continues to collect data. In the heat intervention state, segmented speed reduction is implemented. In the recovery observation state, continuous cross-segment speed increase is prohibited. In the fault conservative state, the use of invalid rapid heat indicators is stopped, and the actuator output is constrained only by the protection limits of melt pressure, billet outer diameter and process temperature; the state transition adopts hysteresis judgment with separate entry threshold and release threshold, and the transition is only performed after the corresponding conditions are continuously satisfied for a preset number of control cycles. Each screw speed or traction speed command is calculated by the controller based on the current feedback value, target change, maximum change in a single cycle, and the actuator's allowable upper and lower limits. The calculation result is then limited and transmitted to the speed setting interface of the main drive motor 4 or the speed setting interface of the traction mechanism 8. When the feedback signal is missing, exceeds the range, communication times out, or the actuator fails to reach the command range within the preset time, the controller cancels the automatic speed increase command, maintains the current safe speed, or executes the preset limited speed decrease, and writes the fault status into the cyclic data cache. The adjustment commands for heating coil power, cooling fan speed and proportional air valve opening are also set with upper and lower limits and change rate limits to avoid secondary fluctuations in melt pressure and billet outer diameter caused by simultaneous sudden changes in multiple actuators during heat intervention. To verify the effectiveness of the above control logic in suppressing heat accumulation and dimensional fluctuations, normal temperature rise test, screw speed increase test, external heating power increase test, cooling air volume change test, and recovery speed rise test were conducted under the target MPP pipe specifications. Each experiment recorded rapid heat indicators, displacement trend of the second thermal response ring 10, estimated process temperature, melt pressure, screw speed 3, traction speed, billet outer diameter and main drive motor 4 load, and compared them with stable production data of the same specification when the heat intervention logic was not enabled. The evaluation items include the response time after the heat accumulation index reaches the intervention threshold, the peak melt pressure, the maximum deviation of the billet outer diameter, the time required to recover to the allowable range, and the number of times the intervention is triggered again during the recovery process; each data item must be repeated at least 3 times under the same process conditions; the control logic is only considered valid if the controller can complete the deceleration, size correction, thermal state observation and segmented recovery in the preset sequence, and does not output an unrestricted automatic speed-up command when there is a fault or invalid signal.

[0040] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An MPP tube extrusion molding equipment based on dynamic temperature control, comprising: The machine includes a frame (1), a traction mechanism (8), and a controller. A screw (3) connected to the main drive motor (4) is rotatably mounted inside the barrel (2). The die head (5) is fixed to the discharge end of the barrel (2). A mandrel (6) is coaxially mounted inside the die head (5), and the two form an annular melt channel (7). The non-melt flow channel area of ​​the mandrel (6) is a section of the mandrel that is axially offset from the annular melt channel (7), does not participate in forming the annular melt channel (7), and does not directly contact the melt flowing through the annular melt channel (7). This mandrel section is connected by a core... The rod (6) body is thermally connected to the annular melt channel (7); in this mandrel section, the first thermal response ring (9) is thermally connected to the mandrel (6) via the first thermally conductive shoulder (13), and the first thermal response ring (9) is in direct contact with the first thermally conductive shoulder (13); the second thermal response ring (10) is thermally connected to the mandrel (6) via the second thermally conductive shoulder (14), and the heat insulation element (15) is sandwiched between the second thermally conductive shoulder (14) and the second thermal response ring (10), and the thermal response time constant of the first thermal response ring (9) is smaller than the thermal response time constant of the second thermal response ring (10); The outer circles of the first thermal response ring (9) and the second thermal response ring (10) respectively abut against the first transmission rod (20) and the second transmission rod (21) that move radially along the core rod (6), and the first transmission rod (20) and the second transmission rod (21) respectively abut against the first displacement transmitter (25) and the second displacement transmitter (26). The die head (5) is equipped with a melt pressure transmitter, the traction mechanism (8) is equipped with a traction speed encoder, and the feed side of the traction mechanism (8) is equipped with a tube blank outer diameter detector. The feed side is the side of the traction mechanism (8) facing the discharge port of the die head (5). The controller is connected to the first displacement transmitter (25), the second displacement transmitter (26), the melt pressure transmitter, the traction speed encoder, the tube blank outer diameter detector and the main drive motor (4). The controller generates a rapid heat index based on the difference between the corrected displacement increment of the first thermal response loop (9) in the same sampling window and the corrected displacement increment of the second thermal response loop (10) after being aligned according to the radial displacement response lag time in the same sampling window. The controller is combined with the melt pressure, screw (3) speed, traction speed and tube blank outer diameter adjustment screw (3) speed.

2. The MPP tube extrusion molding equipment based on dynamic temperature control according to claim 1, characterized in that: The core rod (6) is provided with a first annular step (11) and a second annular step (12); wherein, the first thermal response ring (9) is a thin-walled stainless steel ring sleeved on the outer periphery of the first annular step (11), and the first thermal response ring (9) and the first annular step (11) are in transition fit; wherein, the second thermal response ring (10) is a nickel-chromium alloy ring sleeved on the outer periphery of the second annular step (12), the wall thickness of the second thermal response ring (10) is greater than the wall thickness of the first thermal response ring (9), and an annular heat insulation gap (16) is formed between the second thermal response ring (10) and the second annular step (12).

3. The MPP tube extrusion molding equipment based on dynamic temperature regulation according to claim 2, characterized in that: The annular heat insulation gap (16) is filled with alumina ceramic particles (17), and the alumina ceramic particles (17) are confined within the annular heat insulation gap (16) by a thin-walled stainless steel retaining ring (18); wherein, an alumina ceramic heat insulation component (15) is provided between the second thermally conductive shoulder (14) and the second thermal response ring (10); wherein, the first thermally conductive shoulder (13) is in direct contact with the first thermal response ring (9).

4. The MPP tube extrusion molding equipment based on dynamic temperature control according to claim 3, characterized in that: The outer wall of the mold head (5) is provided with two radial guide holes, and a linear guide sleeve (22) is fixed in each radial guide hole; wherein, the first transmission rod (20) and the second transmission rod (21) are respectively slidably inserted into the corresponding linear guide sleeve (22); the inner ends of the first transmission rod (20) and the second transmission rod (21) are threadedly connected to a spherical top (23), and the spherical top (23) abuts against the outer circle of the first thermal response ring (9) and the second thermal response ring (10) respectively; wherein, the first transmission rod (20) and the second transmission rod (21) are each sleeved with a preload spring (24), and the two ends of the preload spring (24) abut against the corresponding linear guide sleeve and the spherical top (23) respectively.

5. The MPP tube extrusion molding equipment based on dynamic temperature control according to claim 4, characterized in that: The first displacement transmitter (25) and the second displacement transmitter (26) are both differential inductive displacement transmitters and are fixed to the same support plate (27); wherein, the support plate (27) is connected to the frame (1) through a transverse slide (28) and a vertical slide (29), the transverse slide (28) is used to adjust the support plate (27) radially along the barrel (2); the vertical slide (29) is used to adjust the height of the first displacement transmitter (25) and the second displacement transmitter (26); wherein, the support plate (27) is provided with a limit screw (30), the limit screw (30) is located on the moving path of the first transmission rod (20) and the second transmission rod (21).

6. The MPP tube extrusion molding equipment based on dynamic temperature control according to claim 5, characterized in that: A heating coil and a cooling air duct are fixed on the outer periphery of the barrel (2), and the cooling air duct is connected to a cooling fan and a proportional air valve; wherein, the controller is connected to the power controller of the heating coil, the cooling fan and the proportional air valve respectively; When the rapid heat index increases and the displacement trend of the second thermal response ring (10) does not continue to increase, the controller reduces the rotational speed of the screw (3) and limits the increase in cooling air volume; when the displacements of both thermal response rings continue to increase, the controller increases the rotational speed of the cooling fan and the opening of the proportional air valve, and reduces the output power of the heating coil; when neither the rapid heat index nor the displacement trend of the second thermal response ring (10) increases, the controller maintains the current rotational speed of the screw (3) and the current output power of the heating coil.

7. The MPP tube extrusion molding equipment based on dynamic temperature control according to claim 6, characterized in that: The controller records the first displacement zero point of the first displacement transmitter and the second displacement zero point of the second displacement transmitter at a cold reference temperature; and obtains the thermal response time difference between the first thermal response loop (9) and the second thermal response loop (10); The controller is configured with a sampling window for acquiring signals; wherein the controller processes the displacement data of the first thermal response loop (9) and the second thermal response loop (10) within the sampling window to generate the rapid thermal index.

8. The MPP tube extrusion molding equipment based on dynamic temperature control according to claim 7, characterized in that: The controller determines the sampling window based on the screw (3) rotation speed, traction speed and tube blank outer diameter; and filters the same displacement signals of the first thermal response ring (9) and the second thermal response ring (10) according to the set sampling window.

9. The MPP tube extrusion molding equipment based on dynamic temperature control according to claim 8, characterized in that: The controller generates the estimated process temperature of the melt contact area based on the corrected displacement of the first thermal response ring (9), the hysteresis corrected displacement of the second thermal response ring (10), the outer wall temperature of the barrel (2), and the pre-calibrated material expansion parameters including the thermal expansion coefficient of the component itself, and determines the temperature rise trend based on the continuous change of the estimated process temperature; the controller generates a heat accumulation index based on the temperature rise trend and the rapid heat index.

10. The MPP tube extrusion molding equipment based on dynamic temperature control according to claim 9, characterized in that: When the heat accumulation index exceeds the heat intervention threshold, the controller reduces the rotational speed of the screw (3) in a segmented ramp manner; wherein, when the outer diameter of the tube blank decreases, the controller reduces the traction speed of the traction mechanism (8) and limits the reduction range of the screw (3); wherein, when the melt pressure increases and the outer diameter of the tube blank increases, the controller increases the traction speed under the condition that the calculated process temperature is lower than the process warning value; the controller controls the recovery of the rotational speed of the screw (3) according to the falling rapid heat index.

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