A built-in synchronous hot air cold insulation PET foam heat sealing device and anti-cracking heat sealing method

Abstract

The application relates to the field of foamed material processing technology, and discloses a PET foam heat sealing device with built-in synchronous hot air cold insulation and a crack prevention heat sealing method. The device comprises a heat sealing heating plate with an internal air duct and air outlet holes, a constant temperature and pressure air supply device, an electrical proportional flow valve, a detection assembly and a programmable logic controller. When the controller performs the separation action on the heating plate, the controller dynamically outputs a feedforward control voltage based on the instantaneous retreat speed and the gas temperature, and synchronously supplies high-temperature hot air to the heat sealing gap to block the infiltration of cold air; when the two side plates are folded towards each other and the spacing is lower than a threshold value, the controller controls the airflow to be exponentially attenuated in a nonlinear manner with the decrease of the spacing, so that the flow field pressure does not damage the surface melt; and a small amount of air is continuously supplied after the compression to reduce the cooling rate. The application effectively avoids the hardening or micro-cracks of PET melt caused by sudden cooling shrinkage, reduces the accumulation of internal thermal stress of the joint, and improves the mechanical strength of the heat sealing part.

Description

Technical Field

[0001] This invention relates to the field of foam material processing technology, specifically to a PET foam heat sealing device with built-in synchronous hot air insulation and a crack-resistant heat sealing method. Background Technology

[0002] PET foam boards are widely used in the manufacture of composite core materials for wind turbine blades, transportation equipment, and other applications due to their excellent specific strength and temperature resistance. When processing large-sized components, a hot plate welding process is typically used to join multiple boards together. This involves melting the mating surfaces of the boards with a heat-sealing plate, then removing the heat-sealing plate and applying pressure to join the two sides of the boards together.

[0003] In actual processing, due to the low thermal conductivity and temperature-sensitive physical properties of PET material, the heat-sealing quality is easily affected by ambient temperature. When the heating plate is quickly removed from between the two sheets, a local negative pressure inevitably forms in the heat-sealing gap, causing surrounding cold air to be rapidly drawn in. The direct infiltration of cold air causes the PET melt on the sheet end face to cool rapidly, leading to local surface hardening or internal micro-shrinkage cracks. This hinders the mutual diffusion and entanglement of macromolecular chains in the subsequent pressing stage, thereby reducing the overall mechanical strength of the joint.

[0004] To mitigate the cooling problem caused by cold air intrusion, some existing processes attempt to introduce auxiliary hot airflow into the heat-sealing area for insulation. However, during the pressing of the two plates together, as the relative distance between the plates decreases, the internal space is drastically compressed, and the flow pressure increases accordingly. If the air supply system fails to coordinate with the mechanical action and only maintains a fixed displacement, the compressed high-speed airflow can easily cause lateral shear damage to the molten PET that has not yet solidified on the surface, or even blow away local melt, resulting in defects at the joint surface. At the same time, if the auxiliary heat source is directly cut off after the plates are pressed together and allowed to cool naturally, the temperature gradient between the joint center and the external environment will cause localized excessively rapid cooling. This rapid phase change will cause residual thermal stress concentration inside the weld, increasing the risk of cracking during the joint's service under load. Currently, conventional heat-sealing equipment struggles to achieve dynamic and coordinated control of the gap thermal environment and fluid dynamic pressure throughout the entire process cycle of heating plate removal, plate closing, and pressure holding and cooling.

[0005] Therefore, this invention proposes a PET foam heat sealing device with built-in synchronous hot air insulation and a crack-resistant heat sealing method to overcome the shortcomings of the prior art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a PET foam heat sealing device with built-in synchronous hot air insulation and a crack-preventing heat sealing method. This solves the problems in existing PET foam heat sealing processes, such as the sudden cooling and shrinkage of the molten layer caused by cold air entrapment when the heating plate is removed, the damage to the surface melt by uncontrollable airflow during plate pressing, and the concentration of internal thermal stress in the joint due to excessively rapid cooling after pressing.

[0007] The first aspect of the present invention provides a PET foam heat sealing device with built-in synchronous hot air insulation, comprising: A heat-sealing heating plate, which has a through main air duct inside, and the heat-sealing heating plate is provided with a group of partitioned air outlets that are connected to the through main air duct. The constant temperature and pressure stabilizing air supply device is connected to the through main air duct through a sealed air inlet connector; The flow regulating component is equipped with an electric proportional flow valve, which is connected in series between the constant temperature and pressure stabilizing gas supply device and the sealed air inlet connector. The detection components include a position detection component and a temperature sensor; The controller is a programmable logic controller (PLC). The PLC establishes a data connection with the position detection component, the temperature sensor, and the electro-proportional flow valve. The PLC is used to dynamically adjust the control voltage signal output to the electro-proportional flow valve during the process of the heat-sealing heating plate being removed and the foam boards on both sides closing towards each other. The programmable logic controller specifically includes: The zero-opening maintenance module is used to continuously output zero-opening commands to seal the gas pipeline during the pretreatment and static hot-melting stages of the sheet material. The pre-charge control module is used to output a pre-charge control voltage to fill the gas delivery channel volume to be filled within a preset advance time before the heat-sealing heating plate performs the mechanical removal action. The extraction speed feedforward gas supply module is used to output a multivariable coupled feedforward control voltage based on the instantaneous backward speed and the measured absolute gas temperature when the heat-sealing heating plate generates backward displacement, and to latch the transition maintenance voltage. The spacing attenuation control module is used to output the transition maintenance voltage after the heat-sealing heating plate is completely removed, and to maintain the output of the transition maintenance voltage when the foam boards on both sides start to close towards each other and the relative spatial distance is not lower than the preset attenuation trigger distance threshold; when the relative spatial distance is lower than the attenuation trigger distance threshold, the transition maintenance voltage is used as the attenuation reference, and a nonlinear exponential attenuation voltage is output according to the spatial distance reduction ratio. The slow cooling air supply and shutdown module is used to output a small amount of slow cooling air supply voltage command within a set cooling time window after the foam boards on both sides are connected and pressed together, and to reset the electro-proportional flow valve after the delay condition is met.

[0008] Preferably, the heat-sealing heating plate has a first heat-sealing working surface and a second heat-sealing working surface that are arranged opposite to each other and face the foam boards on both sides respectively. The partitioned air outlet group is respectively arranged on the first heat-sealing working surface and the second heat-sealing working surface, and is arranged in the air supply area outside the core heat-melting butt joint area. The partitioned air outlet group includes multiple air outlets, the diameter of which is 5mm to 15mm, and the spacing between adjacent air outlets is 50mm to 100mm, for partitioned diffusion of input hot air.

[0009] Preferably, the constant temperature and pressure stabilizing gas supply device includes a multi-stage air purification component, a pressure reducing and regulating valve, a low-pressure stabilizing gas storage tank, and a constant temperature heating component connected in sequence along the gas flow direction; The multi-stage air purification component includes a pre-oil-water separator and a precision dust filter; The constant temperature heating component is installed in the low-pressure stabilizing gas storage tank and is equipped with an independent temperature control module and an over-temperature power-off protection module. It is used to heat and maintain the temperature of the gas inside the low-pressure stabilizing gas storage tank or at the outlet of the low-pressure stabilizing gas storage tank.

[0010] Preferably, the position detection component includes position detection units corresponding to the mechanical servo axis of the left foam board, the mechanical servo axis of the right foam board, and the mechanical servo axis of the heat sealing heating plate, respectively. Each position detection unit adopts an independent position sensor or an absolute encoder corresponding to the mechanical servo axis. The programmable logic controller is used to obtain the extraction displacement and instantaneous backward speed of the heat-sealing heating plate according to the absolute position coordinates output by the position detection unit of the mechanical servo axis of the heat-sealing heating plate, and to calculate the relative spatial distance between the two foam boards according to the absolute position coordinates output by the position detection units of the mechanical servo axes of the left foam board and the right foam board. The temperature sensor is installed inside the through-flow main air duct and is used to collect the absolute temperature of the gas blown into the heat sealing gap in real time.

[0011] Preferably, the preset advance time determined by the pre-inflation control module is based on the aerodynamic pure time lag constant and the redundancy compensation time of system communication and program scanning; The pneumatic pure time delay constant is determined based on the electromagnetic switching response time of the electro-proportional flow valve and the pipeline propagation time of the gas between the outlet of the electro-proportional flow valve and the through main air duct, and is corrected based on the measured time difference between the time when the pre-charge control command is issued and the time when the downstream pressure or flow reaches the preset response threshold. The pre-charge control voltage is determined based on the volume to be charged in the gas delivery channel, the gas supply pressure, the gas temperature, and the pre-charge duration, through a pre-calibrated mapping relationship between the working pressure, gas temperature, control voltage, action time, and cumulative output gas volume. The pre-charge control module switches the control voltage output to the electro-proportional flow valve from zero voltage to the pre-charge control voltage at the trigger time corresponding to the preset advance time, and continues to output the voltage until the pre-charge is completed, so that the target cumulative output gas volume matches the volume to be filled in the gas delivery channel. The gas transmission channel to be filled is the fixed space volume between the outlet of the electric proportional flow valve and the through main air duct and the zoned air outlet group.

[0012] Preferably, the logic for the multivariable coupled feedforward control voltage output by the extraction velocity feedforward gas supply module is as follows: The reference value of the feedforward control voltage is positively correlated with the instantaneous backward speed of the heat-sealing heating plate. At the same time, dynamic gain compensation is performed using the measured absolute temperature of the gas. The higher the absolute temperature of the gas, the lower the control voltage required for compensation. When the heat-sealing heating plate reaches the preset safe exit position and the mechanical servo axis corresponding to the heat-sealing heating plate reaches the state, the transition sustaining voltage is switched to maintain the airflow barrier.

[0013] Preferably, the logic for the nonlinear exponential decay voltage output by the spacing attenuation control module is as follows: As the relative spatial distance between the foam boards on both sides gradually decreases, the control voltage output to the electro-proportional flow valve is reduced exponentially, using the transition sustaining voltage latched when the decay control is triggered as the reference voltage. When the relative spatial distance is less than the mechanical closure threshold set according to the surface roughness of the foam boards on both sides, the control voltage output to the electro-proportional flow valve is set to zero.

[0014] Preferably, the control logic of the slow cooling air supply and shutdown module is as follows: During the pressure holding and cooling stage after the plates are pressed together, the set slow cooling air supply voltage is maintained so that the hot air flow rate output by the partitioned air outlet group is maintained at 5L / min to 15L / min, and hot air is continuously supplied to the periphery of the heat-sealed joint to build a temperature gradient buffer zone. After the cooling time window ends, the slow cooling air supply voltage is reduced to zero.

[0015] Preferably, the constant temperature and pressure stabilizing gas supply device includes a low-pressure stabilizing gas storage tank with a working gauge pressure of 0.03MPa to 0.06MPa and a constant temperature heating component. The low-pressure stabilizing gas storage tank or its outlet pipeline is equipped with a safety pressure relief component, a pressure detection element and an outlet temperature detection element. The constant temperature heating component is equipped with an independent temperature control module and an over-temperature power-off protection module. When the outlet temperature detection element detects that the gas temperature exceeds the set upper limit, or the pressure detection element detects that the gas supply pressure exceeds the set upper limit or falls below the set lower limit, the constant temperature and pressure stabilizing gas supply device outputs an abnormal status signal to the programmable logic controller. The programmable logic controller then forces the control voltage output to the electro-proportional flow valve to zero and prohibits the removal of the heat-sealing heating plate and the closing action of the foam boards on both sides from starting or continuing.

[0016] A second aspect of the present invention provides a method for heat-sealing PET foam with built-in synchronous hot air insulation to prevent cracking, comprising the following steps: S1. Heat the heat-sealing heating plate and keep it at a constant temperature of 260℃~400℃. Press the PET foam boards on both sides of the heat-sealing heating plate for static heat melting. Set the heat melting time to 3s~20s. During this stage, the programmable logic controller continuously outputs zero opening instructions. S2. Within a preset lead time of 0.1s to 0.3s before the heat-sealing heating plate performs the extraction action, the constant temperature and pressure stabilizing gas supply device provides hot gas with constant pressure and a temperature of 80℃ to 220℃, and the programmable logic controller outputs a pre-charge control voltage. S3. The heat-sealing heating plate is withdrawn at a speed of 200mm / s to 400mm / s. The programmable logic controller outputs a feedforward control voltage to the electric proportional flow valve based on the instantaneous retreat speed and temperature, controlling the gas to be discharged from the heat-sealing heating plate to between the two plates. S4. After the heat-sealing heating plate is removed, the PET foam boards on both sides close towards each other at a speed of 100mm / s to 200mm / s. When the relative spatial distance between the two boards is lower than the preset attenuation trigger distance threshold, the programmable logic controller outputs a non-linear exponential decay voltage. The attenuation trigger distance threshold is 15mm to 50mm. S5. The PET foam sheets on both sides are pressed together under an upsetting pressure of 0.2MPa to 0.5MPa. The programmable logic controller outputs a slow cooling air supply voltage command during a slow cooling air supply duration of 1s to 5s to control the partitioned air outlet group to output a small amount of hot air to the periphery of the closed joint of the PET foam sheets on both sides. After the slow cooling air supply duration ends, the control voltage output to the electro-proportional flow valve is set to zero to reset the electro-proportional flow valve. After the electro-proportional flow valve is reset, the upsetting pressure is maintained until the closed joint is cooled and formed and the part is discharged.

[0017] This invention provides a PET foam heat-sealing device with built-in synchronous hot gas insulation and a crack-resistant heat-sealing method. It has the following beneficial effects: 1. This invention, by setting up a feedforward air supply module for the extraction speed and a group of zoned air outlets, dynamically controls the opening of the electro-proportional flow valve based on the instantaneous retraction speed of the heating plate and the absolute temperature of the gas during the extraction of the heat-sealing heating plate. This control method can replenish the heat-sealing gap with a matching volume of high-temperature hot air while the heating plate is being removed, establishing a positive pressure environment to prevent the infiltration of external cold air. This avoids surface hardening or internal micro-cracks in the molten layer on the PET sheet surface due to sudden cooling and contraction, thereby improving the mechanical strength of the heat-sealed joint.

[0018] 2. This invention utilizes a gap attenuation control module to control the gas supply voltage to decay non-linearly and exponentially when the PET foam sheets on both sides are brought together and the gap is below the trigger threshold. This control strategy causes the gas discharge rate to decrease rapidly at first and then slowly as the gap between the sheets decreases, adapting to the non-linear changes in the internal flow field pressure during the sheet closing stage. This prevents excessive airflow from causing lateral shear damage to the molten PET material on the surface, ensuring the structural integrity of the heat-sealed joint surface.

[0019] 3. After the plates are butt-fitted and pressed together and enter the pressure-holding and cooling stage, this invention maintains a small control voltage to continuously output hot air to the periphery of the heat-sealed joint. This design creates a temperature gradient transition zone outside the joint area, reducing the cooling rate during the transition from the molten state to the solid state of the joint, reducing the accumulation of thermal stress inside the joint due to excessively rapid cooling, and further improving the connection quality of the heat-sealed part. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the system framework of the present invention; Figure 2 This is a schematic diagram of the method flow of the present invention; Figure 3 This is a timing diagram of the zero-position maintenance control logic of the present invention; Figure 4 This is a schematic diagram of the pneumatic pure time delay pre-charge control principle of the present invention; Figure 5 This is a schematic diagram of the mechanical-thermal coupling feedforward control principle of the present invention; Figure 6 This is a schematic diagram illustrating the principle of spatial exponential decay control during the close-range docking phase of the present invention. Figure 7 This is a schematic diagram of the principle of external heat barrier maintenance and delayed shutdown control of the present invention; Figure 8 This is a schematic diagram of the device structure of the present invention; Figure 9 This is a comparison diagram of the stress-strain curves of various groups of samples in this invention; Figure 10 This is a full-temperature DSC spectrum of the heat-sealed region and the parent material of the present invention.

[0021] The components include: 10. Position detection component; 20. Temperature sensor; 30. Electro-proportional flow valve; 40. Programmable logic controller; 50. Heat-sealing heating plate; 51. Through-type main air duct; 52. Zoned air outlet group; 53. Sealed air inlet connector; 60. Constant temperature and pressure stabilizing air supply device; 61. Low-pressure stabilizing air storage tank; 62. Multi-stage air purification component; 63. Pressure reducing and regulating valve; 64. Constant temperature heating component; 100. Zero opening maintenance module; 200. Pre-charge control module; 300. Extraction speed feedforward air supply module; 400. Spacing attenuation control module; 500. Slow cooling air supply and shutdown module. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0023] Please see the appendix Figure 1 and attached Figure 8 This invention provides a PET foam heat sealing device with built-in synchronous hot air insulation, comprising: Heat sealing heating plate 50, constant temperature and pressure stabilizing gas supply device 60, detection component, flow regulation component and controller; The heat-sealing heating plate 50 has a through-flow main air duct 51 machined along its length. The through-flow main air duct 51 is spatially positioned to avoid the electric heating element inside the heat-sealing heating plate 50, thus preventing structural intersection or direct contact between the through-flow main air duct 51 and the electric heating element. The duct wall of the through-flow main air duct 51 forms a thermally conductive connection with the electric heating element through the heat-conducting substrate of the heat-sealing heating plate 50. The heat-sealing heating plate 50 has a first heat-sealing working surface and a second heat-sealing working surface that are oppositely arranged and facing the foam boards on both sides. Both the first and second heat-sealing working surfaces are provided with partitioned air outlet groups 52. A sealed air inlet connector 53 is provided at the tail of the heat-sealing heating plate 50, and the sealed air inlet connector 53 is connected to a constant temperature and pressure stabilizing air supply device 60 through a flexible pipeline. The constant-temperature and pressure-stabilized gas supply device 60 includes a low-pressure stabilized gas storage tank 61, a multi-stage air purification component 62, a pressure reducing and regulating valve 63, and a constant-temperature heating component 64. The multi-stage air purification component 62 includes a pre-oil-water separator and a precision dust filter. Gas flows sequentially through the pre-oil-water separator, the precision dust filter, the pressure reducing and regulating valve 63, the low-pressure stabilized gas storage tank 61, and the tank area heated by the constant-temperature heating component 64, and then through the electro-proportional flow valve 30 and a flexible, heat-resistant pipeline into the sealed inlet connector 53. The low-pressure stabilized gas storage tank 61 or its outlet is equipped with a safety pressure relief component, a pressure detection element, and an outlet temperature detection element.

[0024] The constant temperature heating component 64 is wrapped around the outside of the low-pressure stabilizing gas storage tank 61 and is equipped with an independent temperature control module and an over-temperature power-off protection module. The low-pressure stabilizing gas storage tank 61 or its outlet pipeline is also equipped with a safety pressure relief component and a pressure detection element. When over-temperature, over-pressure or pressure is below the set gas supply lower limit occurs, the constant temperature stabilizing gas supply device 60 outputs an abnormal status signal to the programmable logic controller 40. The programmable logic controller 40 forces the control voltage of the electro-proportional flow valve 30 to zero and prohibits the current mechanical action from continuing. The detection assembly includes a position detection component 10 and a temperature sensor 20. The position detection component 10 includes position detection units corresponding to the servo axes of the left and right foam boards and the heating plate, respectively. Each position detection unit uses an independent position sensor or an absolute encoder corresponding to the mechanical servo axis, and is used to collect the absolute position coordinates of the left foam board, the right foam board and the heat sealing heating plate 50 in real time. The programmable logic controller 40 calculates the relative spatial distance between the working surfaces of the two foam boards based on the absolute position coordinates, the pre-stored mechanical zero-point offset and the structural dimensions of the corresponding working surfaces. The flow regulation component is equipped with an electric proportional flow valve 30, which is installed in series between the constant temperature and pressure gas supply device 60 and the sealed gas inlet connector 53, and is used to adjust the output flow of gas according to the received analog voltage signal. The controller adopts a programmable logic controller 40. The programmable logic controller 40 establishes data connections with the position detection component 10, the temperature sensor 20 and the electric proportional flow valve 30 through the communication bus. The programmable logic controller 40 is internally configured with a zero opening degree holding module 100, a pre-charge control module 200, a withdrawal speed feedforward air supply module 300, a gap attenuation control module 400 and a slow cooling air supply and shutdown module 500. The zero-opening holding module 100 is used to continuously output zero-opening commands to the electro-proportional flow valve 30 to close the gas pipeline during the pretreatment and hot-melting stages of the sheet material. The pre-charge control module 200 is used to output a pre-charge control voltage to the electric proportional flow valve 30 before the heat-sealing heating plate 50 performs the mechanical extraction action and before the servo axis starts, so as to cause gas output and fill the gas transmission channel between the constant temperature and pressure stabilizing gas supply device 60 and the through main air duct 51 to the volume to be filled. The extraction speed feedforward gas supply module 300 is used to extract the instantaneous backward speed of the heat-sealing heating plate 50 based on the data from the position detection component 10 when the heat-sealing heating plate 50 actually generates backward displacement. It calculates the gas density temperature correction value by combining the measured absolute gas temperature fed back by the temperature sensor 20, and outputs a multivariable coupled feedforward control voltage to the electric proportional flow valve 30 so that the target gas output is adjusted according to the working gap between the plates generated by mechanical extraction. When the heat-sealing heating plate 50 reaches the preset safe withdrawal position, the extraction speed feedforward gas supply module 300 stops calculating the feedforward control voltage based on the instantaneous backward speed, and latches the effective control voltage within the preset time window at the end of the extraction stage as a transition maintenance voltage for use after the foam plates on both sides begin to close towards each other. The spacing attenuation control module 400 is used to output a transition maintenance voltage to the electro-proportional flow valve 30 after the heat-sealing heating plate 50 reaches the preset safe exit position and the servo controller feeds back the heating plate shaft position signal, and monitors the relative spatial distance calculated by the position detection component 10 in real time; when the relative spatial distance is lower than the set trigger threshold, it calculates the nonlinear exponential attenuation parameter according to the reduction ratio of the spatial distance, uses the transition maintenance voltage as the attenuation reference voltage, and gradually reduces the control opening of the electro-proportional flow valve 30 to reduce the amount of gas added during the plate closing process and reduce the risk of excessive pressure increase caused by volume compression; The slow cooling air supply and shutdown module 500 is used to maintain a set micro slow cooling air supply voltage command to the electro-proportional flow valve 30 within a set cooling time window after the foam boards on both sides are connected and pressed together. This allows the heat-sealing heating plate 50, which has been withdrawn to the standby position, to provide a micro amount of hot air to the external area of ​​the closed joint through the partitioned air outlet group 52 to form an external slow cooling hot air barrier. After the delay condition is met, the module cuts off the analog output and resets the electro-proportional flow valve 30.

[0025] See attached document Figure 2 This invention provides a method for heat-sealing PET foam with built-in synchronous hot air insulation, comprising the following steps: S10, during the pretreatment and hot-melting stage of the sheet material, the zero-opening holding module 100 continuously outputs a zero-opening command to the electro-proportional flow valve 30 to close the gas pipeline. S20, before the heat-sealing heating plate 50 performs the mechanical removal action, the pre-charging control module 200 outputs a pre-charging control voltage to the electric proportional flow valve 30 within a preset advance time before the servo axis starts, so as to cause gas output and fill the gas delivery channel to be charged volume. S30, when the heat-sealing heating plate 50 actually retracts, the extraction speed feedforward gas supply module 300 extracts the instantaneous retraction speed of the heat-sealing heating plate 50 based on the data from the position detection component 10, calculates the gas density temperature correction value by combining the measured absolute gas temperature fed back by the temperature sensor 20, and outputs a multivariable coupled feedforward control voltage to the electric proportional flow valve 30, so that the target gas output is adjusted according to the working gap between the plates generated by mechanical extraction; when the heat-sealing heating plate 50 reaches the preset safe withdrawal position, the effective control voltage at the end of the extraction stage is latched as a transition maintenance voltage. S40, after the heat-sealing heating plate 50 reaches the preset safe exit position and the heating plate mechanical servo axis feedback signal is received, the servo controller releases the action prohibition state of the mechanical servo axis of the foam boards on both sides, and the foam boards on both sides start the opposite closing action; when the relative spatial distance has not yet reached the attenuation trigger distance threshold, the gap attenuation control module 400 maintains the output transition maintenance voltage; when the relative spatial distance is lower than the set trigger threshold, the nonlinear exponential attenuation parameter is calculated according to the reduction ratio of the spatial distance, and the control opening of the electric proportional flow valve 30 is reduced with the transition maintenance voltage as a reference, so as to reduce the amount of gas added in the working gap between the boards and reduce the risk of excessive pressure increase caused by volume compression; S50, when the foam boards on both sides are connected and pressed together, the slow cooling air supply and shut-off module 500 maintains a set micro slow cooling air supply voltage command to the electro-proportional flow valve 30 within the set cooling time window, so that the partitioned air outlet group 52 outputs a micro amount of hot air to the external area of ​​the board joint and forms a slow cooling hot air barrier; after the delay condition is met, the analog output is cut off and the electro-proportional flow valve 30 is reset, completing the hot air insulation and external slow cooling process in the current working cycle.

[0026] To further clarify the implementation of each technical aspect of the present invention, the following will provide a detailed description of the implementation of each functional module involved above and its internal processing flow.

[0027] See attached document Figure 3The specific execution process of step S10 is divided into multiple control sub-steps, which are completed by the zero opening degree holding module 100 configured inside the programmable logic controller 40 in conjunction with the sensor data and system hardware features.

[0028] Step S101, as can be understood, determines that the prerequisite for the system to enter the hot-melt process is to confirm that the two side panels and the heating plate have achieved a tight fit. The zero-opening maintenance module 100 determines whether the current system is in the static hot-melt stage of pressing the two side foam panels against the heating plate 50 based on the mechanical servo axis coordinate data and the system's electrical operating status. At the beginning of the work cycle, each position detection unit of the position detection component 10 collects the real-time position information of the mechanical servo axis and feeds back the absolute position coordinates of the left foam panel to the programmable logic controller 40. The absolute position coordinates of the foam board on the right. and the absolute position coordinates of the heat sealing heating plate 50 The programmable logic controller 40 converts each absolute position coordinate to a unified mechanical coordinate system and performs distance calculations by combining the pre-calibrated zero-point offset of the working surface, the tooling thickness, and the structural dimensions of the heat-sealing heating plate 50. This represents the current system running time. The zero-opening holding module 100 calculates the instantaneous contact gap distance between the working surface of the plate and the working surface of the heating plate using absolute position coordinates. The distance calculation formula is as follows: ; In the formula, This indicates the instantaneous contact gap distance between the working surface of the plate and the working surface of the heating plate; Indicates the absolute position coordinates of the foam board on the left; Indicates the absolute position coordinates of the foam board on the right; Indicates the absolute position coordinates of the heat sealing heating plate 50; This indicates the current running time of the system.

[0029] When the calculated instantaneous contact gap distance Within the preset filtering time window The internal gap remains below the contact gap threshold. Furthermore, when the system's main control program sends a heating hold status signal, the zero-opening hold module 100 determines that the system has entered the static hot-melt process stage. Among these, the contact gap threshold... Based on the surface roughness of the PET foam board and the assembly tolerances of the mechanical structure, the effective bonding state of the working surface is characterized, and its value range is typically configured from 0.1mm to 0.5mm. Preset filtering time window. This is used to filter out sensor data jitter during the moment of mechanical clamping. If the above conditions are not met, the system maintains the current monitoring state and waits for the servo mechanical axis to complete its movement to ensure the integrity of the control logic.

[0030] In step S102, after confirming the entry into the static heat-melting stage, the zero-opening holding module 100 continuously sends zero-opening control commands to the electro-proportional flow valve 30 to close the gas path. Specifically, the zero-opening holding module 100, through the digital-to-analog conversion channel of the programmable logic controller 40, outputs the instantaneous analog control voltage signal to the electro-proportional flow valve 30. Set and lock to zero potential, that is, expressed by a function expression as follows: Upon receiving a zero-volt control voltage command, the internal valve core of the electro-proportional flow valve 30 returns to its mechanical zero point under the mechanical force of a spring. This action blocks the gas flow loop from the external air supply source to the internal ventilation duct of the heat-sealing heating plate 50, thus physically closing the transmission pipeline. For the specific electrical drive circuit design of the proportional servo valve's internal electromagnetic coil and valve core displacement driven by the analog voltage signal output by the programmable logic controller, those skilled in the art can refer to the corresponding servo valve specification manual for conventional configuration. The underlying drive circuit principle is well-known in the field and will not be elaborated upon here.

[0031] In step S103, in practical engineering applications, residual static pressure still exists inside the pipeline after the air supply circuit is cut off. Therefore, the zero-opening module 100, while performing zero-opening control, works in conjunction with the surface physical structure characteristics of the heat-sealing heating plate 50 to achieve anti-gas leakage protection in the heat-melting area. The central area of ​​the working surface of the heat-sealing heating plate 50 facing the foam board is defined as the core heat-melting butt joint area, which is sealed and without pores. The partitioned air outlet group 52 is arranged in the air supply area outside the welding area on both sides of the working surface of the heat-sealing heating plate 50. During the static heat-melting stage, residual gas pressure exists inside the pipeline. If there is a valve leak, the airflow will seep out to the pores with the least resistance. The zero-volt forced shutdown control of the zero-opening module 100 cuts off the active pressure supply from the front-end air source. The closed state of the air path, combined with the poreless central area of ​​the working surface, significantly reduces the risk of residual gas overflowing through the partitioned air outlet group 52 and spreading to the core heat-melting butt joint area. This hardware and software co-control mechanism aims to suppress the disturbance of the temperature field of the core hot-melt end face by the external airflow, so as to maintain the uniformity of the temperature distribution at the thermal interface.

[0032] See attached document Figure 4 The specific execution process of step S20 is divided into multiple control sub-steps, which are executed by the pre-inflation control module 200 configured inside the programmable logic controller 40 to overcome the inherent physical time delay of fluid transmission in the flexible pipeline.

[0033] In step S201, it is understood that gas, as a compressible fluid, inevitably experiences physical hysteresis during transmission through a flexible pipeline with resistance. If a gas command is issued simultaneously with the removal of the heat-sealing heating plate 50, the response delay at the pipeline's front end will cause a brief negative pressure at the air outlet, leading to the intrusion of external cold air. Therefore, this hysteresis parameter needs to be pre-extracted for feedforward compensation. The pre-charge control module 200 obtains the pneumatic pure hysteresis time constant by integrating the valve's electrical response parameters and the fluid dynamics transmission parameters.

[0034] Specifically, the pre-charge control module 200 retrieves the electromagnetic reversing response time of the electro-proportional flow valve 30, and, in conjunction with the pipeline length between the constant temperature and pressure stabilizing gas supply device 60 and the sealed air inlet connector 53, and the airflow sound velocity at the current operating temperature, calculates the aerodynamic pure time lag constant. The theoretical initial value is obtained by applying a preset step voltage to the electro-proportional flow valve 30 during the equipment commissioning and calibration phase. Using pressure or flow detection elements temporarily installed downstream of the main air duct 51 or near the partitioned air outlet group 52, the time difference between the moment the valve control command is issued and the moment when the downstream pressure or flow first reaches the preset response threshold is recorded. This measured time difference is used to correct the theoretical initial value, and the corrected time constant is used as the actual pneumatic pure time delay time constant. Aerodynamic pure time delay constant The calculation formula is as follows: ; In the formula, This represents the aerodynamic pure time delay constant; Indicates the electromagnetic switching response time of the electro-proportional flow valve 30; This indicates the total length of the pipeline from the outlet of the electro-proportional flow valve 30 to the main air duct 51. This indicates the speed of sound during airflow transmission under the current operating temperature environment.

[0035] Of the parameters mentioned above, Determined based on the factory calibration parameters of the electro-proportional flow valve 30. The velocity of sound is calculated based on the absolute temperature of the gas output from the constant temperature and pressure gas supply device 60, combined with the ideal gas law. For specific calculation models of the ideal gas sound velocity under different temperature and pressure conditions, those skilled in the art can refer to standard fluid mechanics handbooks for conventional calculations. The sound velocity calculation method is a well-known technique in this field and will not be elaborated here.

[0036] Step S202, obtaining the aerodynamic pure time delay constant Subsequently, the pre-inflation control module 200 implements advance triggering of control logic based on the servo motion planning instructions within the programmable logic controller 40. Before the heat-sealing heating plate 50 performs the mechanical withdrawal action, the underlying controller driving the servo axis generates trajectory planning data containing the start time of the motion in advance. The pre-inflation control module 200 reads the expected start time of the planned retraction and withdrawal of the heat-sealing heating plate 50 in the servo motion planning instructions in real time through bidirectional communication between the programmable logic controller 40 and the servo controller. The pneumatic control command issuance time is advanced; the servo controller only initiates the actual removal action of the heat-sealing heating plate 50 after receiving the pre-charge completion signal and shaft movement permission signal output by the programmable logic controller 40; when the pre-charge control module 200 continuously outputs the pre-charge control voltage... When the pre-charge duration is reached and the data from the air supply pressure and temperature detection elements are both within the preset allowable range, the pre-charge control module 200 sets the pre-charge completion flag and the programmable logic controller 40 sends a pre-charge completion signal and an axis movement permission signal to the servo controller. The actual execution time when the pre-charge control module 200 triggers the pre-charge action is... The calculation formula is as follows: ; In the formula, This indicates the actual execution time when the pre-inflation control module 200 triggers the pre-inflation control action; This indicates the expected start time for the retraction and withdrawal of the heat-sealing heating plate 50 in the servo motion planning command; This represents the aerodynamic pure time delay constant; This indicates the redundancy compensation time for system communication and program scanning.

[0037] Redundancy compensation time To compensate for time fluctuations in industrial communication bus data transmission, its value is typically set within the range of one to three programmable logic controller (PLC) scan cycles. Furthermore, when the trajectory planning lead time provided by the system's underlying servo controller is less than... When, that is, calculated Earlier than the current system time, the pre-inflation control module 200 immediately triggers the pre-inflation control action and sends an axis start prohibition signal to the servo controller. The servo controller keeps the mechanical servo axis of the heat sealing heating plate 50 in a stopped state until the pre-inflation control module 200 completes at least [time missing]. After the pre-charge time is set and a pre-charge completion signal is output, the shaft start prohibition signal is released to ensure the integrity of the pre-charge airflow establishment in the physical space. Through the above-mentioned advance scheduling in the time dimension, the control system can ensure that the gas basically reaches the internal cavity of the main air duct 51 at the moment when the heat-sealing heating plate 50 undergoes actual extraction displacement.

[0038] Step S203, the actual execution time is reached. At this time, the pre-charge control module 200 outputs a pre-charge control voltage to the electro-proportional flow valve 30, causing a trace amount of gas to fill the unfilled volume of the gas delivery channel. The unfilled volume of the gas delivery channel refers to the fixed physical space volume between the outlet of the electro-proportional flow valve 30 and the main air duct 51 and the zoned air outlet group 52. The volume of the internal air duct can be obtained by calculating the inner diameter and length of the pipe and then summing it up using 3D modeling software for the heat-sealing heating plate 50, or by calibrating it through conventional drainage methods.

[0039] Considering the compressibility of gas transmission and the fact that the actual output flow of the electro-proportional flow valve 30 is affected by the supply pressure, gas temperature, and control voltage, it is not advisable to directly calculate the pre-charge control voltage based solely on a single linear voltage-flow relationship. The pre-charge control module 200 determines the required pre-charge control voltage by looking up tables and interpolation, based on a pre-calibrated and stored multi-parameter mapping relationship between the operating pressure, gas temperature, control voltage, action time, and cumulative output gas volume, combined with the volume to be charged in the gas delivery channel and the pre-charge duration.

[0040] Specifically, the pre-inflation control module 200 extracts the volume to be inflated from the gas delivery channel. Based on the currently set working gas pressure and pre-charge duration of the constant temperature and pressure stabilizing gas supply device 60, the corresponding pre-charge control voltage is calculated by looking up a table. The precharge duration is and The time difference between them. The lookup data is pre-calibrated using the following method: Under different upstream gauge pressures, gas temperatures, and control voltages, the cumulative output gas volume of the electro-proportional flow valve 30 is measured within a set time to establish a mapping relationship between working pressure, gas temperature, control voltage, operating time, and cumulative output gas volume; for control parameters between adjacent calibration points, the pre-charge control voltage is determined using interpolation. .

[0041] Pre-inflation control module 200 Time to During the specified time interval, a pre-charge control voltage is continuously output to the electro-proportional flow valve 30. This ensures that the target cumulative output gas volume within this time interval is equal to the gas delivery channel's unfilled volume. The system matches and limits the excessive gas overflow from the partitioned air outlet group 52 before the actual removal of the heat-sealing heating plate 50, by setting a preset pre-charge volume limit. This control action drives the electro-proportional flow valve 30 to establish an initial airflow with a small valve core opening, and the output airflow volume is expected to fill the uncharged volume of the aforementioned gas delivery channel. Pre-charge control voltage The value limits the total amount of output gas, which helps to establish a basic static pressure when the gas reaches the edge of the zoned air outlet group 52 without significantly overflowing the holes. This control mechanism avoids the problem of airflow scouring the molten end face of the PET foam board due to premature injection of a large amount of gas, and establishes a steady-state physical basis for the dynamic tracking of microenvironmental air pressure in the subsequent extraction stage.

[0042] See attached document Figure 5 The specific execution process of step S30 is divided into multiple control sub-steps, which are executed by the extraction speed feedforward gas supply module 300 configured inside the programmable logic controller 40, so as to realize the follow-up matching between the gas output volume and the working gap between the plates generated by mechanical extraction.

[0043] In step S301, during the cavity expansion stage, the extraction speed feedforward air supply module 300 extracts the instantaneous retraction speed of the heat-sealing heating plate 50 based on the data from the position detection component 10. Specifically, the position detection component 10 feeds back the absolute position coordinates of the heat-sealing heating plate 50 to the programmable logic controller 40 at a fixed communication scan cycle. Within one communication scan cycle, the extraction speed feedforward air supply module 300 performs first-order discrete difference calculations on the absolute position coordinate data of two adjacent sampling cycles, and defines the extraction direction of the heat-sealing heating plate 50 away from the working area between the two foam boards in a unified mechanical coordinate system as the positive speed direction; the extraction trajectory of the heat-sealing heating plate 50 avoids the opposing closing trajectory of the two foam boards to prevent mechanical interference. Instantaneous retraction speed The calculation formula is as follows: ; In the formula, Indicates the first The instantaneous retraction speed of the heat-sealing heating plate 50 within each scanning cycle; Indicates the first The absolute position coordinates sampled in each scan cycle; Indicates the first The absolute position coordinates sampled in each scan cycle; This indicates the system communication scan cycle.

[0044] To prevent minute speed fluctuations caused by mechanical system vibration or high-frequency sampling noise from sensors from being amplified by the differential algorithm, the underlying logic of the extraction speed feedforward air supply module 300 is configured with a speed dead zone threshold. When the calculated absolute value of the instantaneous backward speed is less than... At that time, the system forced order The absolute position coordinates of the heat sealing heating plate 50. Reaching the pre-defined safe exit position threshold When the feedback position of the mechanical servo axis of the heating plate reaches the state, it is determined that the heat-sealing heating plate 50 has exited the mechanical closing interference zone of the foam boards on both sides.

[0045] For the specific underlying electrical configuration of the high-frequency discrete sampling and first-order differential filtering algorithm for displacement signals, those skilled in the art can refer to the standard servo control system for conventional implementation. The signal preprocessing method is a well-known technology in this field and will not be elaborated here.

[0046] In step S302, before performing the feedforward calculation, the extraction velocity feedforward gas supply module 300, in conjunction with the physical properties of the constant temperature and pressure stabilizing gas supply device 60, defines the basic input environment constraints for the feedforward algorithm. The constant temperature and pressure stabilizing gas supply device 60 continuously outputs a low-pressure gas flow with a gauge pressure set to 0.03MPa to 0.06MPa to the front-end pipeline. The gauge pressure is the pressure value relative to the atmospheric pressure of the environment where the equipment is located. When calculating the gas state parameters, the gauge pressure is added to the current ambient atmospheric pressure and converted into an absolute working pressure. This pressure range can form a soft, static thermal barrier within the working gap between the plates and help reduce impact turbulence. Simultaneously, the output airflow temperature range of the constant temperature and pressure stabilizing gas supply device 60 is set to 80℃ to 200℃. The extraction speed feedforward gas supply module 300 reads the aforementioned set nominal working gauge pressure and nominal working temperature values, and converts the working gauge pressure into absolute working air pressure. Subsequently, it is input to the underlying algorithm as a reference variable, and the upper limit of the control gain of the electric proportional flow valve 30 is limited in the subsequent control to avoid aerodynamic shock caused by exceeding the basic environmental constraints.

[0047] In step S303, the extraction speed feedforward gas supply module 300 calculates the dynamic gas density based on the actual gas temperature fed back by the temperature sensor 20. The temperature sensor 20 is located downstream of the main air duct 51 near the partitioned air outlet group 52, and its detection result can reflect the actual gas temperature entering the heat-sealing gap under the current gas flow and heat exchange conditions.

[0048] The extraction speed feedforward gas supply module 300 directly uses the measured absolute gas temperature collected in real time by the temperature sensor 20 in the kth scan cycle to calculate the dynamic gas density, without performing secondary attenuation correction on the measured absolute gas temperature based on the instantaneous retreat speed of the heat sealing heating plate 50.

[0049] Extraction speed feedforward gas supply module 300 calculates dynamic gas density The formula is as follows: ; In the formula, Indicates the first Dynamic gas density within each scan cycle, in kg / m³ 3 ; The absolute working pressure is the sum of the working gauge pressure of the output gas of the constant temperature and pressure stabilizing gas supply device 60 and the current ambient atmospheric pressure, expressed in Pa. The specific gas constant of the working gas is expressed in J / (kg·K). Indicates that temperature sensor 20 is at the The measured absolute temperature of the gas collected in real time within each scanning cycle, in K.

[0050] When the temperature sensor 20 outputs a Celsius temperature, the programmable logic controller 40 first converts the Celsius temperature into an absolute temperature, and then substitutes it into the dynamic gas density formula.

[0051] In step S304, the extraction speed feedforward air supply module 300 establishes a multivariable coupled feedforward control voltage formula based on the physical cavity expansion rate generated by the extraction of the heat-sealing heating plate 50 and continuously outputs it to the flow regulation component. The rate of change of the cavity volume left by the backward retraction of the heat-sealing heating plate 50 is usually positively correlated with its instantaneous backward retraction speed and the effective cross-sectional area of ​​the working surface. In order to achieve dynamic matching of the spatial volume of airflow filling and cavity expansion, the extraction speed feedforward air supply module 300 calculates the multivariable coupled feedforward control voltage output to the electro-proportional flow valve 30 by comprehensively considering the instantaneous velocity, internal pressure, universal gas constant, and thermal expansion density. Multivariable Coupled Feedforward Control Voltage The formula is as follows: ; In the formula, Indicates the first The multivariable coupled feedforward control voltage output within each scan cycle; This represents the flow-to-voltage conversion factor of the electro-proportional flow valve 30. Indicates the instantaneous backward speed; This represents the equivalent cross-sectional area of ​​the working gap between the plates when the heat sealing heating plate 50 is removed; This indicates the dynamic gas density.

[0052] The target volume filling flow rate generated by the removal of the heat-sealing heating plate 50 is determined according to the following formula: ; The target mass flow rate is determined by the following formula: ; The multivariable coupled feedforward control voltage is determined according to the following formula: ; After merging the above relationships, we get: ; In the formula: Indicates the first The multivariable coupled feedforward control voltage output to the electro-proportional flow valve 30 within each scan cycle is in V; Indicates the first The target actual volumetric flow rate, in m³, matches the expansion rate of the working gap between the plates within each scanning cycle. 3 / s; Indicates the first The target mass flow rate within each scan cycle is expressed in kg / s. This indicates the instantaneous retraction speed of the heat-sealing heating plate 50, in m / s; This represents the equivalent cross-sectional area of ​​the working gap between the panels caused by the removal of the heat sealing heating plate 50, in meters. 2 ; Indicates the first Dynamic gas density within each scan cycle, in kg / m³ 3 ; This indicates the conversion factor from mass flow rate to control voltage for the electro-proportional flow valve 30, expressed in Vs / kg.

[0053] The flow rate is obtained by pre-calibrating the electro-proportional flow valve 30. During calibration, within the preset working pressure and temperature range of the constant temperature and pressure stabilizing gas supply device 60, the actual mass flow rate corresponding to multiple control voltages is recorded, and the relationship between mass flow rate and control voltage is determined. .

[0054] When the electro-proportional flow valve 30 exhibits non-linear flow characteristics within its operating range, the calibration relationship between mass flow rate and control voltage is stored in the programmable logic controller 40 in the form of piecewise coefficients or a lookup table, and determined by interpolation. .

[0055] The programmable logic controller 40 will calculate the The output is limited to the rated control voltage range of the electro-proportional flow valve 30; when the calculated value is lower than the lower limit of the rated control voltage, the lower limit value is output, and when the calculated value is higher than the upper limit of the rated control voltage, the upper limit value is output.

[0056] Among them, the equivalent cross-sectional area of ​​the working gap between the plates The volume of the cavity vacated is determined based on the actual extraction direction of the heat-sealing heating plate 50, the overlap size between the heat-sealing heating plate 50 and the foam boards on both sides, and the vacated volume corresponding to the extraction displacement. Specifically, the correspondence between the extraction displacement of the heat-sealing heating plate 50 and the vacated cavity volume is established in advance based on the three-dimensional structural model of the equipment, and the rate of change of the cavity volume relative to the extraction displacement is used as the equivalent cross-sectional area of ​​the working gap between the boards. .

[0057] The extraction speed feedforward air supply module 300 converts the calculated feedforward control voltage through the digital-to-analog converter interface of the programmable logic controller 40. The output is sent to the electric proportional flow valve 30 in real time. Through the above-mentioned feedforward mechanism, the system can synchronously adjust the opening of the proportional servo valve at the moment of cavity expansion, thereby realizing the feedforward air volume of the built-in hot air during the dynamic extraction process. This reduces the possibility of short-term negative pressure in the cavity and external cold air intruding into the core welding area. At least to a certain extent, this compensates for the response lag defect caused by conventional closed-loop PID control that only compensates after detecting a pressure drop. Thus, the feedforward air volume of the built-in hot air during the dynamic extraction process helps to reduce the possibility of external cold air entering the core welding area of ​​PET foam during the dynamic extraction process.

[0058] See attached document Figure 6 The specific execution process of step S40 is divided into multiple control sub-steps, which are executed by the spacing attenuation control module 400 configured inside the programmable logic controller 40, so as to suppress the overshoot of the internal microenvironment air pressure at the moment when the foam boards on both sides close, and reduce the risk of airflow impacting the molten end face.

[0059] Step S401, when the heat-sealing heating plate 50 reaches the safe withdrawal position threshold. Once the mechanical servo axis of the heating plate reaches the feedback position and the programmable logic controller 40 confirms that the main structure of the heat-sealing heating plate 50 has exited the closing interference zone of the foam boards on both sides, the programmable logic controller 40 outputs a closing action permission signal to the mechanical servo axis of the foam boards on both sides, and the foam boards on both sides enter the mechanical docking and closing stage; at this time, at least part of the air outlet group 52 of the heat-sealing heating plate 50 near the open side edge of the board is still facing the space between the foam boards on both sides, and maintains airflow communication with the space through the open side edge of the board.

[0060] The spacing attenuation control module 400 calculates the relative spatial gap distance between the working surfaces of the board in real time based on the data fed back by the position detection component 10, and determines whether the relative spatial distance is lower than the preset attenuation trigger distance threshold. Specifically, the spacing attenuation control module 400 acquires the absolute position coordinates of the left foam board within a fixed communication scanning cycle. absolute position coordinates of the foam board on the right Calculate relative spatial distance The distance calculation formula is as follows: ; In the formula, Indicates the relative spatial distance between the working surfaces of the sheet metal; Indicates the absolute position coordinates of the foam board on the left; This indicates the absolute position coordinates of the foam board on the right.

[0061] The spacing attenuation control module 400 will calculate the relative spatial distance. Distance threshold for decay trigger Perform a comparison. When Less than or equal to the decay trigger distance threshold At this time, the system triggers the spatial exponential decay control logic and synchronously controls the internal registers to read the transition sustaining voltage determined by the extraction speed feedforward air supply module 300 at the end of extraction as the reference value for the subsequent decay stage. This avoids mistakenly locking zero voltage as the decay reference due to the instantaneous drop in retreat speed to zero after the heat-sealing heating plate 50 stops moving. The decay trigger distance threshold is specified in the original text. Based on the mechanical closing speed of the heat sealing equipment and the setting of the gas compressibility time constant, its conventional value range is configured to be 20mm to 50mm to ensure sufficient air pressure adjustment space before the working surface is completely closed. If this condition is not met, the gap attenuation control module 400 maintains the output transition maintenance voltage and continuously monitors the distance.

[0062] In step S402, it is understood that during the process of the plates closing at a uniform speed, the internal confined volume decreases linearly. However, according to the ideal gas law, the internal pressure is inversely proportional to the volume, which will cause the gas pressure to increase non-linearly as the gap distance decreases. If conventional linear proportional pressure reduction control is used, it is often difficult to effectively suppress the pressure rise in the final stage. Therefore, after triggering the spatial exponential decay control, the gap decay control module 400 constructs an exponential decay calculation model that decreases non-linearly as the spatial distance decreases, in order to calculate the dynamic pressure reduction opening of the electro-proportional flow valve 30 during the docking process. The dynamic decay control voltage output by the gap decay control module 400 is... The calculation formula is as follows: ; In the formula, This indicates the dynamic attenuation control voltage output by the spacing attenuation control module 400 to the electro-proportional flow valve 30; This represents the reference sustaining voltage latched by the system at the moment the decay control is triggered; It is a natural constant; Indicates the spacing attenuation coefficient; Indicates the attenuation trigger distance threshold; It represents the instantaneous relative spatial distance.

[0063] Among them, the spacing attenuation coefficient The attenuation curvature used to adjust the control voltage as distance decreases is calibrated based on the inherent resistance characteristics of the inflation pipeline, and is typically configured to be 0.05 mm. -1 up to 0.2mm -1 Through this nonlinear spatial exponential decay function, the spacing decay control module 400 significantly reduces the control voltage at the end stage when the foam board is close to the edge, driving the electro-proportional flow valve 30 to quickly reduce the valve core opening to limit the airflow supply and reduce the possibility of high-pressure airflow impact in the tiny gap that is about to close. Furthermore, to prevent the decay algorithm from continuously outputting a weak bias voltage after the boards are fully bonded, causing a dead zone in the airflow path, the spacing decay control module 400's underlying program is configured with lower boundary cutoff protection logic. When the instantaneous relative spatial distance... When the surface roughness approaches the equivalent of the board surface roughness (e.g., less than 0.5 mm), the program will forcefully intervene. Stop supplying gas to the working gap between the foam boards on both sides that is about to close; after confirming that the foam boards on both sides have been connected and pressed tightly, the slow cooling air supply and shutdown module 500 outputs a small amount of slow cooling air supply voltage to the electro-proportional flow valve 30 according to the external slow cooling state.

[0064] For the compilation of the underlying exponential function code and the configuration of floating-point operations, those skilled in the art can perform conventional implementation based on the standard programmable controller instruction set. Its basic operation logic is a well-known technology in this field and will not be elaborated here.

[0065] In step S403, the nonlinear flow attenuation algorithm of the spacing attenuation control module 400, combined with the specific physical size parameters of the partitioned air outlet group 52, jointly achieves lateral diffusion airflow and counteracts the volume compression effect. When the foam boards are closely joined, the residual gas inside is physically compressed, which usually needs to be relieved through a reasonable exhaust channel. The partitioned air outlet group 52 set on the heat sealing heating plate 50 has a hole diameter limited to 5mm to 15mm and an adjacent hole spacing limited to 50mm to 100mm. The aforementioned combination of hardware parameters for aperture and aperture spacing, in conjunction with the spacing attenuation control module 400 actively reducing the intake airflow, is used to uniformly diffuse the input hot air in zones during the removal of the heat-sealing heating plate 50 and the initial stage when the plates begin to close. After the heat-sealing heating plate 50 reaches the safe withdrawal position, at least a portion of the zoned air outlet groups 52 near the open side edge of the plate still maintain airflow communication through the space between the open side edge and the working surfaces of the foam boards on both sides, thereby continuing to input attenuated hot air between the working surfaces of the plates. The zoned air outlet groups 52 do not serve as discharge channels for compressed gas in the working gap between the plates.

[0066] Specifically, the exponentially decaying intake volume limits the increase in total gas volume at the source. During the closing process of the foam boards on both sides, the peripheral gap between the working surfaces of the boards, which is not yet closed, forms a gas venting path. The board clamping fixture retains unobstructed lateral venting areas at at least one or both ends along the weld length, allowing the compressed gas in the working gap between the boards to be discharged outward through the peripheral gap and the lateral venting areas. The zoned air outlet group 52 is only used to limit and evenly distribute the newly added hot gas. The spacing decay control module 400 gradually reduces the flow rate of the newly added gas through exponential decay, preventing the intake volume from exceeding the exhaust capacity of the peripheral gap and the lateral venting areas from the source. This collaborative mechanism of software algorithm control, zoned air supply structure, and peripheral venting path of the boards helps to reduce the risk of local high pressure in the butt joint due to insufficient exhaust, and to a certain extent suppresses the pressure overshoot in the core welding area at the moment of closure. It aims to reduce the phenomenon that high-pressure turbulence blows away the molten PET foam material or causes porosity defects inside the weld.

[0067] See attached document Figure 7 The specific execution process of step S50 is divided into multiple control sub-steps, which are executed by the slow cooling air supply and shutdown module 500 configured inside the programmable logic controller 40, so as to maintain the stability of the thermodynamic environment at the external joint during the cooling and forming stage after the plate is joined, and reduce the risk of thermal stress concentration.

[0068] In step S501, the slow cooling air supply and shutdown module 500 determines that the relative spatial distance between the two foam boards is close to zero and starts a preset cooling time window timer. It is understandable that after the two foam boards are mechanically joined, the working gap between the boards is completely compressed and sealed, but the outer side of the joint is still exposed to ambient temperature. To prevent micro-cracks from forming on the weld surface due to rapid cooling by external cold air, the system needs to determine the mold closing state and trigger subsequent insulation logic.

[0069] Specifically, the slow cooling air supply and shutdown module 500 continuously monitors the relative spatial distance. .when Less than or equal to the preset mechanical closure threshold Both the left and right foam board mechanical servo axes report that they have reached their positions, and the driving torque of at least one foam board mechanical servo axis reaches a preset clamping torque threshold, or the clamping force reported by the clamping force detection element reaches a preset clamping force threshold, and the duration of the above state exceeds the confirmation time window. At that time, the slow cooling air supply and shutdown module 500 determine that the mechanical docking and clamping action has been completed.

[0070] Among them, mechanical closure threshold Taking into account both the micro-roughness of the sheet metal surface and the overpressure of the servo mechanical axis, its value is typically configured to range from 0mm to 0.2mm; confirmation time window. Used to filter out mechanical rebound vibrations during the closing moment, the typical value is 50ms to 100ms. If the mechanical mold closing cycle issued by the underlying system times out... If the mechanical closure threshold is not reached, or if the mechanical servo axis does not report the position reached, or the drive torque does not reach the preset clamping torque threshold, the system will trigger an abnormal alarm and forcibly set the control voltage of the electrical proportional flow valve 30 to zero. Simultaneously, it will stop the subsequent slow cooling timing program to prevent the algorithm logic from getting stuck in a dead zone. At the instant the closure condition is determined to be met, the slow cooling air supply and shutdown module 500 simultaneously starts its internal cooling time window timer.

[0071] In step S502, during the cooling time window timer operation, the slow cooling air supply and shutdown module 500 outputs a set micro slow cooling air supply voltage to the electro-proportional flow valve 30 to form a soft static heat barrier outside the joint. Since the heat-sealing heating plate 50 has retreated to the standby position, which is pre-set to a position that does not interfere with the mating movement of the foam boards on both sides, and the air outlet direction of the partitioned air outlet group 52 is directed towards the external area of ​​the closed board joint; a preset non-contact air supply distance is maintained between the partitioned air outlet group 52 and the board joint, so that the output hot air covers the outer surface of the joint without applying mechanical force to the joint. The slow cooling air supply and shutdown module 500 maintains the airflow by calculating the required barrier and outputs a micro slow cooling air supply voltage to the electro-proportional flow valve 30. The calculation formula is as follows: ; In the formula, This indicates the minute slow cooling air supply voltage output by the slow cooling air supply and shutdown module 500; This indicates the full-scale control voltage of the electro-proportional flow valve 30; This indicates the target microflow rate required to maintain the external thermal barrier; This indicates the nominal maximum output flow rate of the electro-proportional flow valve 30 at full-scale control voltage.

[0072] Among the parameters mentioned above, the target is a small flow rate. The distance between the standby position of the heat-sealing heating plate 50 and the joint of the boards is pre-calibrated, and its actual value range is usually configured from 5L / min to 15L / min. This control action causes the electro-proportional flow valve 30 to maintain a very small throttling opening, and the output micro-volume of hot air overflows onto the outer surface of the joint, forming a localized slow cooling temperature zone. At this stage, the gas is no longer used to maintain the pressure of the working gap between the foam boards on both sides, but is used to mitigate the temperature abrupt change between the outer surface of the joint and the surrounding environment. This non-contact static heat gas barrier can provide a certain temperature gradient buffer during the cooling and solidification stage of the welded area, which helps to reduce the risk of thermal stress concentration on the outer surface of the joint due to rapid temperature drop.

[0073] In step S503, the slow cooling air supply and shutdown module 500 cuts off the analog output voltage after the cooling time window ends, thereby resetting the electro-proportional flow valve 30 and ending the current hot air insulation and external slow cooling working cycle. As the running value of the cooling time window timer reaches the preset cooling and molding time, it indicates that the welded parts of the PET foam board have basically completed curing. The cooling and molding time is set according to the board thickness and ambient temperature, and its actual engineering value is usually between 2 and 10 seconds.

[0074] Upon reaching this time point, the slow cooling air supply and shutdown module 500 outputs a zero-volt voltage control command to the electro-proportional flow valve 30, completely shutting off the active air supply to the front-end constant temperature and pressure stabilizing air supply device 60. Furthermore, to prevent timer deadlock caused by external abnormal intervention during the cooling period, the slow cooling air supply and shutdown module 500 is configured with hardware interrupt response logic at its underlying level. If in If an emergency stop, system reset, over-temperature, over-pressure, abnormal air supply pressure, abnormal sensor communication, or mechanical servo axis fault signal is detected during the process, the system will skip the timing judgment and immediately force the analog control voltage of the electrical proportional flow valve 30 to zero by the highest priority safety shutdown state. It will also prevent the zero opening holding module 100, pre-charging control module 200, extraction speed feedforward air supply module 300, spacing attenuation control module 400, and slow cooling air supply and shutdown module 500 from continuing to write to the analog output register. Then, it will execute the initialization actions of the internal status flag bits, temporary variables, and timers.

[0075] After the normal cycle ends or an interruption is triggered, the slow cooling air supply and shutdown module 500 clears and initializes the temporary variables, status flags, and timer data in its internal registers, restoring the underlying program logic to its initial waiting state, ready to receive the trigger of the next machining cycle. For the specific programming of the programmable logic controller's internal timer instruction calls and underlying register clearing and reset, those skilled in the art can perform conventional configurations based on the controller programming manual. Its software control logic and execution mechanism are well-known technologies in the field and will not be elaborated upon here.

[0076] Furthermore, a heat-sealing method for preventing cracking of PET foam with built-in synchronous hot air insulation is provided. This heat-sealing process relies on the fluid dynamic adjustment mechanism of the aforementioned control system during the dynamic mold closing process.

[0077] Example 1: This embodiment provides a method for heat-sealing PET foam with built-in synchronous hot air insulation to prevent cracking, including the following steps: S1. Pre-treatment of the board: Place the wind power grade PET structural foam board to be processed in a constant temperature room to warm up to above 18°C. Use precision milling equipment to cut and process the mating end face of the board, clean the dust and oil stains attached to the end face, and ensure that the end face is flat.

[0078] S2, Normal Hot Melting Stage: The heating plate of the heat sealing equipment is moved forward and brought into contact with the mating ends of the two PET foam pieces. The working temperature of the heating plate is kept constant at 290℃, and the hot melting operation is carried out continuously for 15 seconds to form a uniform molten layer on the end face material. Before the hot melting timer ends, the system's underlying program forces the air circuit to be completely shut off, with no airflow output.

[0079] S3. Synchronous Hot Gas Insulation Stage: After the hot-melt process is completed, the system releases the gas path lock, and the heating plate enters the retraction preparation state. Before the heating plate actually moves, the pre-charge module inside the system triggers the valve in advance based on the pre-identified pure gas path lag time and first-order inertial time constant, outputting a bias voltage to pre-fill the dead zone of the pipeline with a trace amount of gas. As the heating plate actually retracts, the extraction speed feedforward gas supply module extracts the mechanical retraction speed in real time and performs mechanical-thermal coupling feedforward calculations based on the set gas temperature of 180℃ and the set gas pressure of 0.04MPa. The system synchronously drives the electric proportional flow valve to spray hot gas through the air outlet with a hole diameter of 8mm and a hole spacing of 50mm. Utilizing the feedforward output to accurately match the cavity expansion rate, it quickly fills the working gap between the plates and prevents external cold air from intruding into the welding area.

[0080] S4. Rapid docking and pressure holding stage: Under the coverage of the heat barrier, once the self-heating plate completely exits the welding area and sends a mold closing start signal, the servo mechanical mechanism drives the two sides of the plates to close and dock within 1 second. During this period, the spacing decay control module monitors the relative distance between the plates in real time. When the distance shrinks to the preset 30mm threshold, the system triggers spatial exponential decay control, driving the valve opening to decrease non-linearly. This, combined with the air outlet network on the plate surface, achieves smooth lateral discharge of compressed gas, suppressing internal air pressure overshoot at the moment of closure.

[0081] S5. Delayed Air-Holding Cooling Stage: After the plates are firmly pressed together (distance approaches zero), the slow cooling air supply and shutdown module is controlled to output a small amount of pressure-holding voltage to the valve, forming a soft static thermal barrier outside the joint. After a 1.5s delay, the analog output voltage is completely cut off to shut off the jet, allowing the joint to be removed from the external air-cooling environment to complete the initial crystallization. Mechanical pressure is then maintained until it cools to room temperature.

[0082] Example 2: This embodiment provides a method for heat-sealing PET foam with built-in synchronous hot air insulation to prevent cracking, including the following steps: S1. Pre-treatment of the board: The wind power grade PET structural foam board is left to warm up in a normal temperature workshop in summer, and the butt joint end face is precisely cut and the surface impurities are removed.

[0083] S2, Normal hot melt stage: The heating plate is moved forward to fit the mating end face, the heating plate temperature is set to the lower limit of 260℃, and hot melt heating is performed for 10 seconds. A uniform molten layer is formed on the end face, and the gas path is kept closed.

[0084] S3. Synchronous Hot Gas Insulation Stage: After the hot melting is completed, the pre-charging control module performs advanced pre-charging based on the pipeline physical parameters. When the heating plate is removed, the extraction speed feedforward air supply module sets the output temperature to 100℃ and the working air pressure to 0.03MPa based on the summer environment. The feedforward algorithm, combined with the instantaneous extraction speed, dynamically adjusts the gas density compensation amount. The airflow is smoothly ejected through the partitioned air outlets with a diameter of 5mm and a spacing of 80mm, dynamically occupying low-pressure hot air to isolate the internal draft of the workshop and the local airflow disturbance caused by pneumatic equipment.

[0085] S4. Rapid docking and pressure holding stage: From the moment the self-heating plate completely exits the welding area and sends a mold closing start signal, the mechanical mechanism completes the bonding and docking within 1 second. When the plate material approaches the 20mm threshold, the gap attenuation control module intervenes, limiting the air intake through an exponential pressure reduction algorithm to prevent aerodynamic impact at the end of the gap.

[0086] S5, Delayed Air Closure Cooling Stage: After the plates are pressed and stabilized, the slow cooling air supply and the shut-off module maintain a very small throttling opening. After a delay of 1 second, the front-end air supply is shut off, and then the heat sealing is completed under pressure holding and cooling in a normal environment.

[0087] Example 3: This embodiment provides a method for heat-sealing PET foam with built-in synchronous hot air insulation to prevent cracking, including the following steps: S1. Pre-treatment of the board: The wind power grade PET structural foam board is heated to a constant temperature and the end face is precisely cut to ensure flatness.

[0088] S2, Normal Hot Melting Stage: To increase the heat input in extremely cold environments, the heating plate temperature is set to the upper limit of 400℃ and hot melting is performed for 20 seconds to form a molten layer with sufficient enthalpy on the end face. During this stage, the gas path is kept in a forced closed state and there is no airflow output.

[0089] S3, Synchronous Hot Gas Insulation Stage: Before the heating plate is rapidly extracted, the system executes gas path dead zone compensation, pure lag compensation, and pre-charge logic. During extraction, to counteract the temperature difference impact of the extremely cold environment, the extraction speed feedforward gas supply module reads the upper limit parameter and controls the constant temperature equipment to output constant temperature low-pressure hot gas at 200℃ and 0.06MPa. The system calculates the computer-coupled feedforward voltage in real time, driving the airflow to be ejected through the air outlet with a diameter of 15mm and a spacing of 100mm, rapidly establishing a high-strength hot gas barrier around the molten surface.

[0090] S4. Rapid docking and pressure holding stage: Under the protection of the thermal barrier, the equipment starts high-speed mold closing as soon as the self-heating plate completely exits the welding area and sends a mold closing start signal, completing the bonding and pressing of the plates within 1 second. To avoid the air hammer effect caused by high-temperature and high-pressure gas, the distance attenuation control module relaxes the distance trigger threshold to 50mm, intervenes in the spatial exponential attenuation control in advance, and relies on the larger aperture network to quickly release pressure.

[0091] S5. Delayed Air-Closing Cooling Stage: After the panels are pressed and stabilized, in order to further reduce the thermal stress concentration caused by the extremely cold environment, the slow cooling air supply and the shutdown module maintain a high proportion of external heat barrier and extend the cooling time window. After a delay of 2 seconds, the jet is completely shut off. The joint completes the initial curing in the controlled microenvironment and then holds the pressure to cool to room temperature.

[0092] Comparative Example 1: Compared with Example 1, the difference is that the synchronous hot air insulation and delayed air-sealing cooling processes in steps S3 and S5 are omitted. After the hot melt is completed, the conventional heating plate is directly removed and the mold is mechanically closed. There is no hot air output for space occupation throughout the process, and everything else is the same.

[0093] Comparative Example 2: Compared with Example 1, the difference is that in step S3, the pre-charge and mechanical-thermal coupling feedforward control is not used, but the conventional hysteresis closed-loop control logic is used (that is, after the heating plate is removed, the sensor detects the cavity and then triggers the gas valve to open), and the rest are the same.

[0094] Comparative Example 3: Compared with Example 1, the difference is that in step S3, the gas pressure process parameters are changed, the working gas pressure of the gas supply system is increased to 0.15MPa (conventional high-pressure purging pressure), and the space exponential decay pressure reduction control in step S4 is not performed, while the rest are the same.

[0095] Comparative Example 4: Compared with Example 2, the difference is that in the delayed air-sealing cooling stage of step S5, the hot airflow is immediately and completely cut off at the moment the plates are pressed together (delay 0s), and the hot air barrier outside the joint is not maintained. All other aspects are the same.

[0096] Test Example 1: The heat-sealing production equipment and PET foam boards corresponding to Example 1, Comparative Example 2 and Comparative Example 3 were selected as experimental subjects.

[0097] A test blind hole is pre-drilled along the thickness direction of the PET foam board on one side to be mated, at the geometric center point. A high-frequency miniature air pressure sensor with a range of -0.1MPa to 0.3MPa is implanted in the hole. The sensor's allowable operating temperature, frequency response, and temperature drift performance all meet the test conditions, and zero-point and range calibrations are completed before testing. The sensor is fixed by a heat-insulating, sealing, and mechanical isolation structure to ensure that the sensor probe end face is flush with the mating working surface of the board and does not directly bear the mechanical contact load applied by the board after the board is closed and pressed, so as to directly collect the air pressure changes in the gap.

[0098] Connect the data output terminal of the high-frequency miniature barometric pressure sensor to the high-frequency data acquisition card and then connect it to the host computer testing software. Set the sampling frequency of the data acquisition card to 1000Hz.

[0099] Start the heat sealing process program for each test object. Use the electrical control signal corresponding to the heating plate removal action as the hard trigger condition for data acquisition. When the system issues the removal signal, the host computer simultaneously starts recording, with the recording duration set to 1.5 seconds, and the recording range covering the entire process from the formation of the removal cavity to the completion of mold closing and clamping.

[0100] After the test, the air pressure time series data of each test object on the time axis from 0 to 1500ms were exported, and the data at key time nodes were extracted for comparative analysis.

[0101] The experimental data are shown in Table 1: Table 1: Microenvironment air pressure test data during dynamic mold closing process

[0102] in conclusion: According to the data characteristics in Table 1, in Example 1, during the initial stage of heating plate removal (0-150ms), the gas pressure gradually increased from 0.001MPa to 0.038MPa, and remained relatively stable within a range of 0.039MPa to 0.042MPa within 300-900ms, approaching the target pressure of 0.04MPa. This pressure response is consistent with the expected control effect of the pre-charge module and the mechanical-thermal coupling feedforward control module, which reduces the transient impact of rapid cavity expansion on gap pressure by pre-filling the dead zone of the pipeline and outputting the feedforward opening according to the instantaneous speed of plate removal. In the final stage of mold closing (1100-1500ms), the gas pressure reading in Example 1 shows a gradual downward trend, indicating that the space exponential decay control effectively reduces the gas flow input adaptively according to the shrinkage of the plate gap, suppressing the pressure rise caused by volume contraction.

[0103] In contrast, Comparative Example 2, due to its reliance on conventional feedback control and inherent lag, exhibited a negative pressure trough of -0.019 MPa in the initial stage of plate removal (50-150 ms). This negative pressure phenomenon increases the likelihood of external cold air entering the joint microenvironment. Comparative Example 3, with a base high pressure of 0.15 MPa and no spatial attenuation control, measured a transient pressure peak of 0.247 MPa at the end of mold closing (1300-1400 ms). Excluding the influence of mechanical contact load on the sensor, this pressure peak indicates that the high-pressure air supply and the rapid contraction of the cavity volume are superimposed, which may cause airflow scouring and shearing effects on the molten material, increasing the risk of cell destruction or local melt migration. The test results show that the coupled feedforward and spatial attenuation algorithm of this application has substantial technical improvements in maintaining the thermodynamic state of the microenvironment and suppressing pressure overshoot.

[0104] Test Example 2: PET foam boards that have undergone the heat sealing process in Examples 1, 2, 1, and 4 were used as experimental subjects.

[0105] According to the ISO 1926 standard for testing the tensile properties of rigid foamed plastics, each group of heat-sealed sheets was mechanically cut along a direction perpendicular to the joint plane to prepare tensile specimens that meet the shape and size requirements specified in the standard. The cutting accuracy was controlled so that the weld interface was located at the geometric center of each specimen, and three specimens were randomly selected from each group for parallel testing.

[0106] The prepared standard specimens are sequentially clamped in the upper and lower fixtures of the microcomputer-controlled universal testing machine. The fixtures are adjusted to ensure that the force axis of the specimen is collinear with the load axis of the testing machine. The system load and displacement sensors are then zeroed.

[0107] The crosshead loading rate of the universal testing machine was set to 2.0 mm / min. The tensile failure test was started at a standard ambient temperature of 23°C, and the load was continuously applied to the specimen until the specimen completely fractured.

[0108] The system uses the control software of the testing machine to record the instantaneous load and displacement deformation of each specimen during the stress process. The system calculates the stress based on the initial effective cross-sectional area of ​​the specimen and exports the tensile strength and fracture strain data of the specimen, while outputting a continuous stress-strain curve.

[0109] The experimental data are shown in Table 2: Table 2: Test Data of Mechanical Properties of Welds

[0110] in conclusion: According to Table 2 and Figure 9The mechanical test results show that the tensile strength of Examples 1 (winter conditions) and 2 (summer conditions) ranges from 1.81 MPa to 1.89 MPa, with fracture strains exceeding 8.0% in both cases. The stress-strain curves of the two sets show a high degree of overlap, and a clear plastic deformation range exists before fracture. This phenomenon preliminarily indicates that the synchronous hot gas occupancy method of this application, by adjusting the gas supply temperature, helps to reduce the influence of different ambient temperatures on the heat-sealing process, enabling the two sets of samples to exhibit similar tensile properties in this small-sample test.

[0111] In contrast, the tensile strength and fracture strain of the specimen in Comparative Example 1 showed a significant decrease, with the curve exhibiting abrupt fracture at a low strain state of approximately 2%. This result is consistent with the accelerated cooling rate of the molten end face and the decrease in weld toughness after the absence of the hot gas barrier, and shows a more pronounced tendency for low-strain fracture. However, the tensile data alone are insufficient to prove the formation of a micro-hardened layer at the joint or to determine its internal stress distribution. The three specimens in Comparative Example 4 showed significant dispersion in their mechanical parameters, with fracture strain fluctuating between 3.21% and 7.18%. Their average yield stress was 1.417 MPa with a sample standard deviation of 0.312 MPa, and their average fracture strain was 4.970% with a sample standard deviation of 2.023%. The significant dispersion shown in these three specimens suggests that immediately shutting off the hot gas after butt welding may increase the instability of weld formation performance. However, due to the small sample size, further verification is needed by increasing the number of parallel specimens and conducting repeated batch tests. The temperature compensation and delayed gas-tightening control strategy of this scheme provides corresponding experimental support for improving the mechanical properties of welds and reducing the performance dispersion between samples.

[0112] Test Example 3: Approximately 5.2 mg of core material was scraped from the center of the joint of the sample prepared in Example 1 as a test sample of the weld center layer of Example 1; approximately 5.1 mg of material was scraped from an area more than 150 mm away from the edge of the joint of the same sample that was not affected by heat as a test sample of the non-heated base material area; approximately 5.3 mg of core material was scraped from the center of the joint of the sample prepared in Comparative Example 1 as a test sample of the weld center layer of Comparative Example 1.

[0113] The three groups of powder samples were placed in standard aluminum crucibles, and the crucibles were pressurized and cold-sealed using a tablet press. The prepared sample crucibles, together with the empty reference crucibles, were placed in the heating chamber of the differential scanning calorimeter.

[0114] Dry nitrogen gas with a purity of 99.99% is introduced into the heating furnace cavity as a protective gas, and the purge gas flow rate is set to 50 mL / min to prevent the polymer from undergoing oxidative cross-linking at high temperature.

[0115] The thermal analysis program was set in the control software: the initial temperature was set to 30℃, and after maintaining isothermal temperature for 3 minutes, the temperature was linearly heated to 290℃ at a constant heating rate of 10℃ / min. This test directly collects the heat-sealing process history characteristics of the sample, without performing a pre-melting operation to eliminate the thermal history.

[0116] After the heating process is completed, the temperature and transient heat flow rate data of each sample are exported using thermal analysis software, and the temperature and integral enthalpy values ​​of the locations of the glass transition step, cold crystallization exothermic peak, and melting endothermic peak are extracted.

[0117] The experimental data are shown in Table 3: Table 3: Characteristic Parameters of Crystallization Kinetics DSC Thermal Analysis

[0118] in conclusion: According to Table 3 and Figure 10 The differential scanning calorimetry (DSC) results show that the DSC curve characteristics of the weld center layer in Example 1 are basically consistent with those of the unheated base material region in Example 1. The deviations of its cold crystallization peak temperature (141.6℃) and main melting peak temperature (253.9℃) from the base material are within a reasonable testing error range, and the enthalpy of fusion remains similar (30.82 J / g vs. 31.25 J / g). The data indicate that the constant temperature, low pressure airflow set up in this application did not cause any obvious glass transition, cold crystallization, or abnormal main melting characteristics that could be identified by this DSC test during the formation of the isolation barrier. Since DSC cannot directly characterize the polymer molecular weight and molecular chain breakage, the test results cannot rule out the possibility of slight thermal degradation or hydrolysis. In comparison, the test data for the weld center layer in Comparative Example 1 showed a deviation in physical characteristics. The cold crystallization peak temperature shifted significantly forward to 133.5℃, and the exothermic peak broadened. This phenomenon is consistent with the rapid cooling and high proportion of non-equilibrium amorphous structures formed in this region after melting. However, the position of the cold crystallization peak may also be affected by factors such as molecular weight, nucleation state, physical aging, and sampling differences. Simultaneously, a double melting peak phenomenon of 246.1℃ and 252.8℃ appeared during the melting stage. This double-peak structure indicates that the material exhibits multiple melting behaviors, which may be related to differences in crystal perfection or lamellar thickness distribution, or to melting, reorganization, and remelting processes occurring during DSC heating. The microcrystalline type cannot be uniquely determined based solely on the results of this single heating DSC. The above data verifies from a crystallization kinetics perspective that when the weld end face directly contacts cold air, it triggers rapid cooling, leading to abnormal phase transformation of the material. The simultaneous hot gas insulation and delayed slow cooling control applied in the embodiment provide corresponding improvement support for maintaining the integrity of the weld zone's crystal structure.

[0119] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A PET foam heat sealing device with built-in synchronous hot air insulation, characterized in that, include: A heat-sealing heating plate, which has a through main air duct inside, and the heat-sealing heating plate is provided with a group of partitioned air outlets that are connected to the through main air duct. The constant temperature and pressure stabilizing air supply device is connected to the through main air duct through a sealed air inlet connector; The flow regulating component is equipped with an electric proportional flow valve, which is connected in series between the constant temperature and pressure stabilizing gas supply device and the sealed air inlet connector. The detection components include a position detection component and a temperature sensor; The controller is a programmable logic controller (PLC). The PLC establishes a data connection with the position detection component, the temperature sensor, and the electro-proportional flow valve. The PLC is used to dynamically adjust the control voltage signal output to the electro-proportional flow valve during the process of the heat-sealing heating plate being removed and the foam boards on both sides closing towards each other. The programmable logic controller specifically includes: The zero-opening maintenance module is used to continuously output zero-opening commands to seal the gas pipeline during the pretreatment and static hot-melting stages of the sheet material. The pre-charge control module is used to output a pre-charge control voltage to fill the gas delivery channel volume to be filled within a preset advance time before the heat-sealing heating plate performs the mechanical removal action. The extraction speed feedforward gas supply module is used to output a multivariable coupled feedforward control voltage based on the instantaneous backward speed and the measured absolute gas temperature when the heat-sealing heating plate generates backward displacement, and to latch the transition maintenance voltage. The spacing attenuation control module is used to output the transition maintenance voltage after the heat-sealing heating plate is completely removed, and to maintain the output of the transition maintenance voltage when the foam boards on both sides start to close towards each other and the relative spatial distance is not lower than the preset attenuation trigger distance threshold; when the relative spatial distance is lower than the attenuation trigger distance threshold, the transition maintenance voltage is used as the attenuation reference, and a nonlinear exponential attenuation voltage is output according to the spatial distance reduction ratio. The slow cooling air supply and shutdown module is used to output a small amount of slow cooling air supply voltage command within a set cooling time window after the foam boards on both sides are connected and pressed together, and to reset the electro-proportional flow valve after the delay condition is met.

2. The PET foam heat sealing device with built-in synchronous hot air insulation according to claim 1, characterized in that, The heat-sealing heating plate has a first heat-sealing working surface and a second heat-sealing working surface that are arranged opposite to each other and face the foam boards on both sides respectively. The partitioned air outlet group is respectively arranged on the first heat-sealing working surface and the second heat-sealing working surface, and is arranged in the air supply area outside the core heat-melting butt joint area. The partitioned air outlet group includes multiple air outlets, the diameter of which is 5mm to 15mm, and the spacing between adjacent air outlets is 50mm to 100mm, for partitioned diffusion of input hot air.

3. The PET foam heat sealing device with built-in synchronous hot air insulation according to claim 1, characterized in that, The constant temperature and pressure stabilizing gas supply device includes a multi-stage air purification component, a pressure reducing and regulating valve, a low-pressure stabilizing gas storage tank, and a constant temperature heating component connected sequentially along the gas flow direction. The multi-stage air purification component includes a pre-oil-water separator and a precision dust filter; The constant temperature heating component is installed in the low-pressure stabilizing gas storage tank and is equipped with an independent temperature control module and an over-temperature power-off protection module. It is used to heat and maintain the temperature of the gas inside the low-pressure stabilizing gas storage tank or at the outlet of the low-pressure stabilizing gas storage tank.

4. The PET foam heat sealing device with built-in synchronous hot air insulation according to claim 1, characterized in that, The position detection component includes position detection units corresponding to the mechanical servo axis of the left foam board, the mechanical servo axis of the right foam board, and the mechanical servo axis of the heat sealing heating plate, respectively. Each position detection unit adopts an independent position sensor or an absolute encoder corresponding to the mechanical servo axis. The programmable logic controller is used to obtain the extraction displacement and instantaneous backward speed of the heat-sealing heating plate according to the absolute position coordinates output by the position detection unit of the mechanical servo axis of the heat-sealing heating plate, and to calculate the relative spatial distance between the two foam boards according to the absolute position coordinates output by the position detection units of the mechanical servo axes of the left foam board and the right foam board. The temperature sensor is installed inside the through-flow main air duct and is used to collect the absolute temperature of the gas blown into the heat sealing gap in real time.

5. A PET foam heat sealing device with built-in synchronous hot air insulation according to claim 1, characterized in that, The preset advance time determined by the pre-inflation control module is based on the aerodynamic pure time lag constant and the redundancy compensation time of system communication and program scanning. The pneumatic pure time delay constant is determined based on the electromagnetic switching response time of the electro-proportional flow valve and the pipeline propagation time of the gas between the outlet of the electro-proportional flow valve and the through main air duct, and is corrected based on the measured time difference between the time when the pre-charge control command is issued and the time when the downstream pressure or flow reaches the preset response threshold. The pre-charge control voltage is determined based on the volume to be charged in the gas delivery channel, the gas supply pressure, the gas temperature, and the pre-charge duration, through a pre-calibrated mapping relationship between the working pressure, gas temperature, control voltage, action time, and cumulative output gas volume. The pre-charge control module switches the control voltage output to the electro-proportional flow valve from zero voltage to the pre-charge control voltage at the trigger time corresponding to the preset advance time, and continues to output the voltage until the pre-charge is completed, so that the target cumulative output gas volume matches the volume to be filled in the gas delivery channel. The gas transmission channel to be filled is the fixed space volume between the outlet of the electric proportional flow valve and the through main air duct and the zoned air outlet group.

6. A PET foam heat sealing device with built-in synchronous hot air insulation according to claim 1, characterized in that, The logic for the multivariable coupled feedforward control voltage output by the extraction speed feedforward gas supply module is as follows: The reference value of the feedforward control voltage is positively correlated with the instantaneous backward speed of the heat-sealing heating plate. At the same time, dynamic gain compensation is performed using the measured absolute temperature of the gas. The higher the absolute temperature of the gas, the lower the control voltage required for compensation. When the heat-sealing heating plate reaches the preset safe exit position and the mechanical servo axis corresponding to the heat-sealing heating plate reaches the state, the transition sustaining voltage is switched to maintain the airflow barrier.

7. A PET foam heat sealing device with built-in synchronous hot air insulation according to claim 1, characterized in that, The logic for the nonlinear exponential decay voltage output by the spacing attenuation control module is as follows: As the relative spatial distance between the foam boards on both sides gradually decreases, the control voltage output to the electro-proportional flow valve is reduced exponentially, using the transition sustaining voltage latched when the decay control is triggered as the reference voltage. When the relative spatial distance is less than the mechanical closure threshold set according to the surface roughness of the foam boards on both sides, the control voltage output to the electro-proportional flow valve is set to zero.

8. A PET foam heat sealing device with built-in synchronous hot air insulation according to claim 1, characterized in that, The control logic for the slow cooling air supply and shutdown module is as follows: During the pressure holding and cooling stage after the plates are pressed together, the set slow cooling air supply voltage is maintained so that the hot air flow rate output by the partitioned air outlet group is maintained at 5L / min to 15L / min, and hot air is continuously supplied to the periphery of the heat-sealed joint to build a temperature gradient buffer zone. After the cooling time window ends, the slow cooling air supply voltage is reduced to zero.

9. A PET foam heat sealing device with built-in synchronous hot air insulation according to claim 1, characterized in that, The constant temperature and pressure stabilizing gas supply device includes a low-pressure stabilizing gas storage tank with a working gauge pressure of 0.03MPa to 0.06MPa and a constant temperature heating component. The low-pressure stabilizing gas storage tank or its outlet pipeline is equipped with a safety pressure relief component, a pressure detection element and an outlet temperature detection element. The constant temperature heating component is equipped with an independent temperature control module and an over-temperature power-off protection module. When the outlet temperature detection element detects that the gas temperature exceeds the set upper limit, or the pressure detection element detects that the gas supply pressure exceeds the set upper limit or falls below the set lower limit, the constant temperature and pressure stabilizing gas supply device outputs an abnormal status signal to the programmable logic controller. The programmable logic controller then forces the control voltage output to the electro-proportional flow valve to zero and prohibits the removal of the heat-sealing heating plate and the closing action of the foam boards on both sides from starting or continuing.

10. A method for preventing cracking of PET foam with built-in synchronous hot air insulation, applied to the PET foam heat sealing device with built-in synchronous hot air insulation as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Heat the heat-sealing heating plate and keep it at a constant temperature of 260℃~400℃. Press the PET foam boards on both sides of the heat-sealing heating plate for static heat melting. Set the heat melting time to 3s~20s. During this stage, the programmable logic controller continuously outputs zero opening instructions. S2. Within a preset lead time of 0.1s to 0.3s before the heat-sealing heating plate performs the extraction action, the constant temperature and pressure stabilizing gas supply device provides hot gas with constant pressure and a temperature of 80℃ to 220℃, and the programmable logic controller outputs a pre-charge control voltage. S3. The heat-sealing heating plate is withdrawn at a speed of 200mm / s to 400mm / s. The programmable logic controller outputs a feedforward control voltage to the electric proportional flow valve based on the instantaneous retreat speed and temperature, controlling the gas to be discharged from the heat-sealing heating plate to between the two plates. S4. After the heat-sealing heating plate is removed, the PET foam boards on both sides close towards each other at a speed of 100mm / s to 200mm / s. When the relative spatial distance between the two boards is lower than the preset attenuation trigger distance threshold, the programmable logic controller outputs a non-linear exponential decay voltage. The attenuation trigger distance threshold is 15mm to 50mm. S5. The PET foam sheets on both sides are pressed together under an upsetting pressure of 0.2MPa to 0.5MPa. The programmable logic controller outputs a slow cooling air supply voltage command during a slow cooling air supply duration of 1s to 5s to control the partitioned air outlet group to output a small amount of hot air to the periphery of the closed joint of the PET foam sheets on both sides. After the slow cooling air supply duration ends, the control voltage output to the electro-proportional flow valve is set to zero to reset the electro-proportional flow valve. After the electro-proportional flow valve is reset, the upsetting pressure is maintained until the closed joint is cooled and formed and the part is discharged.

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