Pressure automatic compensation device and control method of medical packaging bag heat sealing mechanism

Abstract

The present application relates to medical packaging heat sealing equipment, and discloses a pressure automatic compensation device and a control method. A main driving cylinder pushes the main hinge pin shaft of two connecting rods to cross the center connecting line and abut against a limiting piece, so that the heat sealing main beam forms a load reference over the dead point. A servo bidirectional screw rod drives a mirror image inclined wedge slider between the heat sealing main beam and the floating heat sealing knife bearing seat, so that the vertical push block is independently micro-fed. After confirmation of locking, the controller implements hysteresis compensation according to the heat sealing effective temperature window and the normalized stress relaxation rate of sealing pressure, and resets before unlocking. The partition structure realizes common feeding and differential correction through the thinning groove and the thin-walled bridge part of the continuous heat sealing knife. The present application is used for compensating the sealing pressure attenuation caused by the softening of the packaging material under heat, and improving the consistency of the sealing pressure.

Description

Technical Field

[0001] This invention relates to the field of sealing equipment for medical packaging materials, and in particular to an automatic pressure compensation device and control method that performs a small closed-loop correction of the position of the heat-sealing knife based on the temperature state of the heat-sealing interface and the stress relaxation characteristics of the sealing pressure during the heat-sealing and pressure-holding process of medical packaging bags. Background Technology

[0002] Medical packaging bags are typically composed of thermoplastic films, coated dialysis paper, composite films, or combinations thereof. During heat sealing, a heat-sealing blade and a lower support clamp the area to be sealed, and under set temperature, pressure, and time conditions, the heat-sealing layer softens, melts, or undergoes viscoelastic deformation, thereby forming a continuous seal. The stability of the heat-sealing pressure and its uniformity along the length of the seal directly affect the seal strength, peel consistency, and seal integrity.

[0003] Existing heat-sealing equipment typically uses cylinders to directly drive the heat-sealing main beam and maintain the sealing pressure while the cylinders are under pressure. Due to the elasticity and hysteresis of compressed gas, seals, pipelines, and valves, the load-bearing boundary of the heat-sealing main beam changes with fluctuations in gas source pressure, friction conditions, and thermal deformation. Once the packaging material enters the effective heat-sealing temperature range, it also undergoes thermal softening, viscoelastic stress relaxation, and a reduction in effective thickness. When the heat-sealing blade position remains essentially unchanged, these changes manifest as a decrease in sealing pressure over time. If pressure adjustment or stroke compensation is directly achieved through the main drive cylinder, aeroelasticity, static friction, and the large inertia of moving parts limit the resolution and response speed of fine adjustments.

[0004] Other devices use lead screws, wedges, or servo actuators to adjust the position of the heat-sealing knife. However, if the fine-tuning actuator shares the load path with the main drive mechanism, the elasticity of the air chamber in the main drive cylinder will still enter the micro-compensation loop, and the correspondence between micro-displacement and actual pressure change is prone to drift. If only pressure below a threshold is used as the compensation condition, equipment vibration, mold closing impact, initial clamping fluctuations, or measurement noise may also cause false triggering.

[0005] For longer heat-sealing blades, variations in the number of layers in the packaging bag, as well as errors in the processing and thermal deformation of the heat-sealing blade and support components, can cause uneven distribution of sealing pressure along the length. While completely segmenting the heat-sealing blade facilitates independent adjustment, it can easily lead to discontinuities in the working surface, temperature field, or abrupt changes in sealing indentations between adjacent segments. Therefore, a technical solution is needed that can establish a stable macroscopic bearing reference, perform high-resolution micro-feeding under this reference, and simultaneously ensure continuous heat-sealing working surface and balanced pressure in different zones. Summary of the Invention

[0006] The present invention aims to solve at least the following technical problems: reducing the influence of the pneumatic elasticity of the main drive cylinder on the sealing pressure during the heat sealing and pressure holding stage; independently compensating for the effective thickness change caused by the heat softening and stress relaxation of the packaging material under a stable bearing reference; reducing miscompensation caused by vibration, noise and initial clamping fluctuations; and coordinating and compensating for local pressure differences in the length direction of the heat sealing knife when necessary, while maintaining the continuity of the heat sealing working surface and the heating path.

[0007] To address the aforementioned technical problems, this invention provides an automatic pressure compensation device for a heat-sealing mechanism of medical packaging bags. The device includes a frame, a lower support fixed to the frame, a heat-sealing main beam that moves vertically relative to the frame, a main drive cylinder, a floating heat-sealing knife support seat located below the heat-sealing main beam and having vertical freedom of movement, and a heat-sealing knife mounted on the floating heat-sealing knife support seat. The heat-sealing knife is equipped with a heating element and forms a heat-sealing gap with the lower support.

[0008] The device further includes a macroscopic drive mechanism. The macroscopic drive mechanism includes a first link, a second link, a main hinge pin connecting the lower end of the first link and the upper end of the second link, and a dead-point limiting component mounted on the frame. The upper end of the first link is hinged to the frame, and the lower end of the second link is hinged to the heat-sealing main beam. A main drive cylinder is connected to the main hinge pin. The main drive cylinder can drive the main hinge pin across the center line between the upper hinge point of the first link and the lower hinge point of the second link and abut against the dead-point limiting component, so that the heat-sealing reaction force is transmitted to the frame via the first link, the second link, and the dead-point limiting component.

[0009] The device also includes a micro-compensation mechanism disposed between the heat-sealing main beam and the floating heat-sealing knife support. The micro-compensation mechanism includes a micro-compensation frame fixed to the heat-sealing main beam, a servo motor, a bidirectional lead screw driven by the servo motor, two mirror-arranged wedge sliders, and a vertical push block constrained by linear guidance. The two wedge sliders act on the vertical push block through mutually cooperating inclined surfaces and are driven by the bidirectional lead screw to move synchronously in opposite directions or in opposite directions, thereby driving the vertical push block to perform a micro-feed relative to the heat-sealing main beam. The micro-compensation mechanism uses the heat-sealing main beam in a dead-point locked state as the displacement reference, and its micro-feed displacement is not generated by the extension and retraction of the main drive cylinder.

[0010] The device also includes a force sensor disposed between the vertical push block and the floating heat sealing knife support, a temperature sensor for detecting the temperature near the working surface of the heat sealing knife, a locking state detection element for detecting the dead-point locking state, a displacement detection element for detecting the micro-compensation position, and a controller. The controller is connected to the main drive cylinder, servo motor, force sensor, temperature sensor, locking state detection element, and displacement detection element, respectively.

[0011] The controller calculates the sealing pressure based on the sealing force measured by the force sensor and the preset effective sealing area; after confirming the dead point lock, it allows the micro-compensation mechanism to start, and controls the micro-compensation mechanism to return to the preset yield position before releasing the dead point lock; during the pressure holding stage, it controls the micro-compensation mechanism to perform micro-feeding based on whether the detected temperature is within the effective heat sealing temperature window and the stress relaxation characteristics of the sealing pressure, and stops micro-feeding when the sealing pressure reaches the exit condition.

[0012] In a preferred configuration, the center of the main hinge pin is located on the over-point side of the center line and has a preset vertical offset distance from the center line. In the heat-sealed state, the micro-compensation mechanism forms a micro-compensation force transmission path that does not pass through the main drive cylinder's air chamber. This micro-compensation force transmission path sequentially passes through the micro-compensation frame, the wedge slider, the vertical push block, the force sensor, the floating heat-sealing knife support, the heat-sealing knife, the medical packaging bag to be sealed within the heat-sealing gap, the lower support, the frame, the first link, the second link, the over-dead-point limiter, the heat-sealing main beam, and returns to the micro-compensation frame.

[0013] In a preferred configuration, each of the two wedge sliders has a driving inclined surface, and the two sides of the vertical push block each have a mating inclined surface that slides with the driving inclined surface. The two driving inclined surfaces are symmetrically arranged with respect to the center plane of the heat sealing knife width, and the two mating inclined surfaces are also symmetrically arranged with respect to the center plane of the heat sealing knife width. The two driving inclined surfaces have equal inclination angles and opposite inclination directions. The two sections of the bidirectional lead screw have opposite thread directions, allowing the two wedge sliders to move synchronously towards or away from each other.

[0014] In a preferred configuration, each wedge slider is equipped with a main nut and a preload nut that mate with the corresponding helical thread section of the bidirectional lead screw. The servo motor is equipped with a servo brake to maintain the current micro-feed position of the vertical push block during micro-compensation reset or pause. A locking state detection element is provided corresponding to the main hinge pin or the over-dead-point limit element; a displacement detection element is provided corresponding to the wedge slider or the vertical push block, and can be a stroke sensor, a zero-position switch, or a linear displacement sensor.

[0015] In a preferred configuration, the force sensor is either a strain gauge force sensor or a piezoresistive force sensor. Along the path that transmits force to the heat-sealing knife, from top to bottom, a vertical push block, a pre-tightened force sensor, a ceramic heat-insulating pressure plate, and a floating heat-sealing knife support are arranged sequentially. The force sensor is held under pressure by a pre-tightening bolt or a disc spring to measure static and quasi-static sealing forces and to reduce the possibility of the sensor disengaging from pressure contact when the load is released or during minor vibrations.

[0016] In a preferred configuration, the device employs a partitioned compensation structure. Multiple floating heat-sealing knife supports are arranged along the length of the heat-sealing knife. Each floating heat-sealing knife support is driven by an independent micro-compensation mechanism and has only a vertical micro-displacement degree of freedom. Each partition is respectively equipped with a force sensor and a displacement detection element. A continuous heat-sealing knife is supported below all the floating heat-sealing knife supports. The continuous heat-sealing knife has a thinning groove with an opening facing away from the heat-sealing working surface between adjacent floating heat-sealing knife supports, and a continuous thin-walled bridging portion is maintained between the thinning groove and the heat-sealing working surface. The heating element extends along the length of the continuous heat-sealing knife and is located between the heat-sealing working surface and the bottom of the thinning groove. The thinning groove avoids and does not cut off the heating element in the length direction.

[0017] The present invention also provides a control method for the above-mentioned automatic pressure compensation device, comprising: rapid mold closing; confirmation of over-dead point locking; initial pressure establishment; temperature window identification; dual-condition judgment of pressure error and stress relaxation rate; micro-feed compensation; pressure recovery stop; micro-compensation reset after pressure holding ends; and releasing over-dead point locking and opening the mold.

[0018] Among them, a lower limit for sealing pressure is set. Pressure recovery limit Stress relaxation rate initiation threshold and stress relaxation rate exit threshold ,and , When the detected temperature is within the effective heat-sealing temperature window, the controller adjusts the pressure based on the real-time sealing pressure. and the sealing pressure after filtering The calculated normalized stress relaxation rate is used to trigger, hold, or exit the microfeed control. When the detected temperature is below the lower limit of the effective heat-sealing temperature window, the controller stops further microfeeding and maintains the current position of the micro-compensation mechanism. When the detected temperature is above the upper limit of the effective heat-sealing temperature window, the controller stops microfeeding and heating of the heating element, and outputs a temperature anomaly signal.

[0019] In the partitioned compensation structure, the controller calculates the sealing pressure and area-weighted average pressure of each partition. Based on the error of the area-weighted average pressure, it outputs a common feed amount, and based on the deviation of the sealing pressure of each partition from the area-weighted average pressure, it outputs a differential correction amount. The differential correction amount of each partition satisfies the requirement of zeroing the area weighting and limits the vertical displacement difference of the micro-feed of adjacent partitions to no more than the maximum elastic deflection displacement difference allowed by the continuous thin-walled bridging section.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: Compared with the structure where the main drive cylinder directly maintains pressure, after the main hinge pin crosses the center line and abuts against the dead point limiter, the heat sealing reaction force is mainly borne by the bearing path formed by the connecting rod and the frame. The air chamber elasticity of the main drive cylinder no longer constitutes a micro-compensation force transmission path, thus establishing a relatively stable displacement and bearing benchmark for micro-feeding.

[0021] The mirrored wedge slider is synchronously driven by a bidirectional lead screw, which can convert a large horizontal stroke into a vertical micro stroke. The horizontal component forces generated by the two inclined plane pairs are in opposite directions. The micro-compensation frame and the linear guide only bear the unbalanced parts on both sides, which helps to reduce the lateral disturbances on the floating heat sealing knife support and improve the repeatability of micro-feed.

[0022] The controller combines the effective heat-sealing temperature window with the normalized stress relaxation rate of the sealing pressure and sets the hysteresis relationship between the pressure threshold and the rate threshold. This allows it to distinguish between the continuous pressure decay after the material enters the thermal softening stage and the initial fluctuations of mold closing, equipment vibration, and measurement noise, thereby reducing the frequent start-stop and erroneous feeding of the micro-compensation mechanism.

[0023] The timing interlock, which allows micro-compensation only after lock confirmation and returns to the preset yield position before unlocking, avoids conflicting actions before the macroscopic load-bearing benchmark is established or micro-compensation reset is completed. Abnormal handling for temperature exceeding limits, stroke exceeding limits, or the inability to recover target pressure reduces the risk of overpressure or overheating of the heat-sealing knife.

[0024] The partitioned structure uses multiple floating heat-sealing knife supports to differentially correct local pressure, while a continuous heat-sealing knife with thinning grooves and continuous thin-walled bridging sections maintains the continuity of the heat-sealing working surface. The common feed rate is separated from the differential correction rate with area weighting set to zero, and the displacement difference between adjacent partitions is limited, which helps to reduce local pressure deviation while maintaining the overall sealing pressure. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the overall structure of the automatic pressure compensation device of the present invention.

[0027] Figure 2 This is a schematic diagram of the state of the macroscopic drive mechanism of the present invention, wherein... Figure 2 (a) shows the state where the main hinge pin has not yet crossed the center line. Figure 2(b) shows the locked state where the main hinge pin crosses the center line and abuts against the dead point limiter.

[0028] Figure 3 This is a cross-sectional schematic diagram of a single micro-compensation mechanism and its pressure-bearing component according to the present invention.

[0029] Figure 4 This is a partial cross-sectional schematic diagram of the present invention through the thinning groove and heating element.

[0030] Figure 5 This is the overall flowchart of the control method of the present invention.

[0031] Figure 6 This is a schematic diagram of the closed-loop control logic of the present invention, wherein... Figure 6 (a) is the hysteresis control process for temperature window and pressure-stress relaxation rate. Figure 6 (b) is the process for zoned common feed, differential correction and abnormal handling.

[0032] In the diagram: 1. Frame; 2. Lower support; 3. Heat-sealing main beam; 4. Main drive cylinder; 5. Floating heat-sealing knife support; 6. Heat-sealing knife; 7. First connecting rod; 8. Second connecting rod; 9. Main hinge pin; 10. Over-dead-point limit component; 11. Micro-compensation frame; 12. Servo motor; 13. Bidirectional lead screw; 14. Wedge slider; 15. Vertical push block; 16. Force sensor; 17. Temperature sensor; 18. Locking status detection component; 19. Displacement detection component; 20. Controller; 21. Linear guide component; 22. Main nut; 23. Preload nut; 24. Ceramic heat-insulating pressure plate; 25. Continuous heat-sealing knife; 26. Thinning groove; 27. Continuous thin-walled bridging part; 28. Heating element. Detailed Implementation

[0033] The embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be understood that the embodiments described are for illustrating the technical concept of the present invention and are not intended to limit the present invention to the specific dimensions, materials, control cycles, or component models described below. Where there is no contradiction, the technical features of the various embodiments can be combined with each other.

[0034] The term "vertical" as used in this manual refers to the direction of movement of the heat-sealing blade 6 toward or away from the lower support 2, and is not limited to the direction of absolute gravity of the equipment in the actual installation location; "micro-feeding toward the heat-sealing blade" means that the vertical push block 15 pushes the floating heat-sealing blade carrier 5 to reduce the heat-sealing gap or increase the tightness of the medical packaging bag to be sealed; "preset retraction position" refers to the safe position that the micro-compensation mechanism should return to before releasing the over-dead point lock, which can be the mechanical zero position or a position with a preset offset relative to the mechanical zero position.

[0035] The effective sealing area referred to in this specification refers to the effective heat-sealing contact area actually distributed to the sealing force measured by the force sensor 16. The effective sealing area of ​​a single-zone structure can be determined based on the effective working length and effective working width of the heat-sealing knife 6, and corrected through standard sample indentation, pressure distribution detection, or equipment calibration; the effective sealing area of ​​a zoned structure... The effective enclosed area of ​​each zone is denoted as . The effective sealing area is stored in the controller 20 as a process parameter corresponding to the packaging specifications and heat sealing knife specifications.

[0036] Example 1: Single-zone pressure automatic compensation device.

[0037] like Figure 1 As shown, the frame 1 forms the fixed bearing base of the device. The lower support 2 is fixed to the lower part of the frame 1, and the heat-sealing main beam 3 moves up and down relative to the frame 1 via vertical guide rails set at both ends or the back side. The cylinder body of the main drive cylinder 4 is mounted on the frame 1, and the output end of the main drive cylinder 4 is connected to the main hinge pin 9. The lower support 2 may have a flat pressure-bearing surface and may be equipped with a heat-resistant elastic pad or a replaceable pressure strip depending on the packaging material and heat-sealing process.

[0038] A floating heat-sealing knife support 5 is positioned below the heat-sealing main beam 3 and has limited vertical micro-displacement freedom relative to the heat-sealing main beam 3 via guide posts, linear slide rails, or equivalent vertical guiding structures. A heat-sealing knife 6 is mounted on the floating heat-sealing knife support 5, and a heating element 28 is installed within the heat-sealing knife 6. A temperature sensor 17 is embedded inside the heat-sealing knife 6 and adjacent to the heat-sealing working surface, or installed in a position capable of stably characterizing the temperature of the heat-sealing working surface. The heat-sealing knife 6 and the lower support 2 are positioned opposite each other, forming a heat-sealing gap that clamps the medical packaging bag to be sealed during the heat-sealing process.

[0039] like Figure 2 As shown, the upper end of the first connecting rod 7 is hinged to the frame 1 via a fixed hinge point, and the lower end of the second connecting rod 8 is hinged to the heat-sealing main beam 3. The lower end of the first connecting rod 7 and the upper end of the second connecting rod 8 are connected by the main hinge pin 9. The first connecting rod 7 and the second connecting rod 8 can each be a pair of plate-type connecting rods arranged on both sides of the heat-sealing mechanism, and share the main hinge pin 9 to improve the symmetry of the force on the heat-sealing main beam 3; if the movement and load-bearing capacity are not affected, a single-sided connecting rod or a fork-shaped connecting rod can also be used.

[0040] When the main drive cylinder 4 extends, it pushes the main hinge pin 9 to move along a combined lateral and vertical trajectory, causing the first link 7 and the second link 8 to gradually unfold. Figure 2 In the state shown in (a), the main hinge pin 9 has not yet crossed the center line connecting the upper hinge point of the first link 7 and the lower hinge point of the second link 8. After continued driving, the main hinge pin 9 crosses this center line and enters the crossing point side, forming a directional vertical offset distance between its center and the center line. Then, it abuts against the dead-point limiting member 10 fixed to the frame 1, forming Figure 2 (b) shows the locked state.

[0041] Vertical offset distance The determination is based on the lengths of the first link 7 and the second link 8, the expected heat-sealing reaction force, the hinge clearance, the stroke of the main drive cylinder 4, and the driving force required for unlocking. The over-dead-point limiter 10 can be a limit block with a high-rigidity contact surface, and can be equipped with adjusting threads, shims, or replaceable wear-resistant contact blocks to calibrate the over-point position during assembly and maintenance. The locking state detection element 18 is provided corresponding to the main hinge pin 9 or the over-dead-point limiter 10, and can be a proximity switch, limit switch, photoelectric switch, or a detection element that can confirm that the main hinge pin 9 has reached the limit position.

[0042] exist Figure 2 In the state shown in (b), the reaction force from the heat-sealing blade 6 is transmitted to the frame 1 via the second link 8, the first link 7, and the over-dead-point limiter 10. The over-dead-point limiter 10 prevents the main hinge pin 9 from returning to the unlocked side of the center line under the action of the heat-sealing reaction force. The main drive cylinder 4 is used to complete the rapid mold closing, over-point locking, and unlocking mold opening. Its air cavity is not used as the source of micro-feed displacement for the micro-compensation mechanism described later.

[0043] like Figure 3 As shown, the micro-compensation frame 11 is fixed to the heat-sealed main beam 3. A bidirectional lead screw 13 is rotatably mounted on the micro-compensation frame 11 via bearings. The servo motor 12 is directly connected to the bidirectional lead screw 13, or connected via a reducer, coupling, or synchronous transmission assembly. The bidirectional lead screw 13 includes two threaded sections with opposite directions of rotation. Two wedge sliders 14 respectively engage with the corresponding threaded sections and are restricted to axial movement along the bidirectional lead screw 13 by horizontal guide components on the micro-compensation frame 11.

[0044] Two wedge sliders 14 are mirror images of the width center plane of the heat sealing knife 6. Each wedge slider 14 has a driving ramp, and the vertical push block 15 has mating ramps on both sides that slide in conjunction with the corresponding driving ramp. The two driving ramps have equal inclination angles and opposite inclination directions, and the two mating ramps are mirror images of each other. When the bidirectional lead screw 13 rotates in the first direction, the two wedge sliders 14 move synchronously towards each other and push the vertical push block 15 toward the heat sealing knife 6; when the bidirectional lead screw 13 rotates in the opposite direction, the two wedge sliders 14 move synchronously away from each other, allowing the vertical push block 15 to move away from the heat sealing knife 6.

[0045] The vertical push block 15 is constrained by the linear guide 21 disposed within the micro-compensation frame 11, retaining only the vertical degree of freedom of movement. The linear guide 21 can be a linear sliding guide, a rolling linear guide, a crossed roller guide, or a guide pair formed by guide posts and guide sleeves. The horizontal component of the force generated by the mirrored inclined plane pair is in the opposite direction; the remaining horizontal component caused by the manufacturing and friction differences on both sides is borne by the linear guide 21 and the micro-compensation frame 11, so the resultant force transmitted to the floating heat-sealing knife support 5 is mainly vertical.

[0046] To ensure reliable return of the vertical push block 15 and the floating heat-sealing knife support 5 when the wedge slider 14 moves backward, a reset assembly can be installed between the vertical push block 15 and the micro-compensation frame 11, or between the floating heat-sealing knife support 5 and the heat-sealing main beam 3. The reset assembly can be a tension spring, compression spring, disc spring assembly, or controlled pull-back component, ensuring that the mating inclined surface of the vertical push block 15 remains in contact with the driving inclined surface of the wedge slider 14 within permissible limits. Alternatively, a sloped groove with retaining edges or a roller driven structure can be used to achieve bidirectional geometric constraint. The reset assembly only provides the return action required to overcome the weight, friction, and preload of the moving parts, without altering the primary pressure path established by the mirrored wedge structure during micro-feeding.

[0047] Each wedge slider 14 can be equipped with a main nut 22 and a preload nut 23. The main nut 22 and the preload nut 23 engage with the threaded sections of the bidirectional lead screw 13 in the corresponding direction of rotation, and form a double-nut backlash-free structure through elastic preload or axial adjustment to reduce the axial backlash of the bidirectional lead screw 13 during reversal. The servo motor 12 is equipped with a servo brake; when the controller 20 issues a pause command, the equipment disconnects from the drive, or the micro-compensation mechanism completes its reset, the servo brake maintains the angular position of the bidirectional lead screw 13, thereby maintaining the position of the vertical push block 15.

[0048] Force sensor 16 is disposed between vertical push block 15 and floating heat sealing knife support 5. In one embodiment, vertical push block 15, force sensor 16, ceramic heat-insulating pressure plate 24 and floating heat sealing knife support 5 are arranged sequentially from top to bottom. Ceramic heat-insulating pressure plate 24 may be made of alumina, silicon nitride or other ceramic materials that have both compressive strength and heat insulation properties to reduce the transfer of heat from heat sealing knife 6 to force sensor 16.

[0049] Force sensor 16 is a strain gauge force sensor or a piezoresistive force sensor capable of measuring static or quasi-static forces. The preload can be a preload bolt, a disc spring, or a combination of both, ensuring that force sensor 16 remains under pressure within the measurement range of the heat-sealing cycle. The preload force is greater than the tendency to disengage due to the resetting of the moving part and the allowable vibration of the equipment, but less than the allowable preload of force sensor 16. Controller 20 records the zero point or preload reference in the mold-open, unsealed state, and subtracts the reference from the sensor output in the pressure-holding state to obtain the sealing force acting on the medical packaging bag to be sealed. .

[0050] Displacement detection element 19 is set for any wedge slider 14 or vertical push block 15. When a zero-position switch is used, the controller 20 calculates the micro-compensation displacement in conjunction with the encoder pulses of the servo motor 12, and the cumulative position is periodically calibrated by the zero-position switch; when a stroke sensor or linear displacement sensor is used, the controller 20 can directly obtain the position of the wedge slider 14 or vertical push block 15. The horizontal displacement of the wedge slider 14... Theoretical vertical displacement of vertical push block 15 Calculations are made based on the geometric relationships of the inclined plane. When the angle between the driving inclined plane and the horizontal plane is... When elastic deformation is neglected, the theoretical vertical displacement is... Represented as:

[0051] in, This is the horizontal displacement of either of the two wedge sliders 14 relative to its initial position; This represents the theoretical vertical displacement of the vertical pusher 15 relative to its initial position. The angle between the driving inclined plane and the horizontal plane. For a structure in which two wedge sliders 14 move synchronously towards each other, the two wedge sliders 14 jointly constrain the direction of motion of the vertical push block 15, but do not multiply the theoretical vertical displacement obtained by converting the horizontal displacement of a single wedge slider 14.

[0052] In actual control, errors caused by lead screw pitch, inclined plane angle, guide clearance, and structural elasticity can be corrected using a displacement calibration table. The inclined plane angle, the pitch of the bidirectional lead screw (13), and the encoder resolution of the servo motor (12) jointly determine the micro-feed resolution; the total micro-compensation stroke is determined based on the allowable compression of the packaging material, the assembly tolerance of the heat sealing knife, and the safety margin.

[0053] In the over-dead-point locked state, the micro-compensation mechanism uses the heat-sealing main beam 3 as the displacement reference. Observing the closed bearing circuit starting from the micro-compensation frame 11, the micro-compensation action passes through the wedge slider 14, vertical push block 15, force sensor 16, floating heat-sealing knife support 5, heat-sealing knife 6, medical packaging bag to be sealed, lower support 2, frame 1, first connecting rod 7, second connecting rod 8, over-dead-point limiting component 10, and heat-sealing main beam 3 before returning to the micro-compensation frame 11. This circuit does not pass through the air chamber of the main drive cylinder 4, therefore the correspondence between servo micro-feed and sealing pressure changes is less affected by gas compressibility.

[0054] The controller 20 can be an industrial controller, a programmable logic controller, a motion controller, or an embedded controller with real-time data acquisition and servo control capabilities. The controller 20 includes a force signal acquisition channel, a temperature signal acquisition channel, a digital input channel, a servo drive interface, and a valve control interface for the main drive cylinder 4. The heating element 28 is driven by a temperature control module, which can be integrated into the controller 20 or communicate with it.

[0055] Example 2: Single-zone control method.

[0056] like Figure 5 and Figure 6 As shown in (a), a heat sealing cycle can be performed according to the following steps.

[0057] Step S100: System preparation and zero-point check. Controller 20 confirms that the heat-sealing main beam 3 is in the mold-opening position, the micro-compensation mechanism is in the preset retraction position, and that the force sensor 16 and temperature sensor 17 have no open wires or over-range faults. It also reads the effective sealing area corresponding to the packaging specifications. The target pressure range, effective temperature window, and stress relaxation rate threshold are defined. When necessary, the zero point or preload reference of force sensor 16 is updated under unsealed load conditions.

[0058] Step S200, rapid mold closing. Controller 20 controls the main drive cylinder 4 to extend, pushing the main hinge pin 9 to unfold the first connecting rod 7 and the second connecting rod 8. The heat sealing knife 6 approaches the lower support 2 and clamps the medical packaging bag to be sealed. After the main hinge pin 9 crosses the center line, it abuts against the dead-point limit member 10.

[0059] Step S0, Over-dead-point locking confirmation. Controller 20 receives the signal from locking status detector 18. When locking status is detected within a preset time, it confirms that the heat-sealed main beam 3 has established a reference load-bearing state and enables servo micro-compensation; when locking status is not detected within the preset time, the micro-compensation mechanism is prohibited from continuing to feed, the cycle is stopped, and a locking abnormality signal is output.

[0060] Step S400: Initial pressure is established. Controller 20 reads the output from force sensor 16, and obtains the sealing force after zero-point and preload compensation. and in accordance with

[0061] Calculate real-time sealing pressure The controller 20 drives the servo motor 12 at an initial adjustment speed lower than the maximum permissible feed speed during the pressure holding phase, so that the sealing pressure enters the initial target range. During the initial adjustment process, the displacement detection element 19 is monitored simultaneously to prevent the vertical push block 15 from exceeding the permissible stroke.

[0062] Step S500, temperature window identification. Controller 20 reads the detected temperature from temperature sensor 17. Temperature detection It can be directly used as the temperature near the heat-sealing working surface, or it can be converted into an estimated value characterizing the heat-sealing interface temperature through a pre-calibrated temperature difference correction model. Effective heat-sealing temperature window. Set and store parameters based on packaging materials, heat sealing knife structure, sealing time, and verification results.

[0063] Step S600: Pressure signal processing and normalized stress relaxation rate calculation. Controller 20 performs low-pass filtering, moving average filtering, median filtering, or a combination thereof on the real-time sealing pressure to obtain the filtered sealing pressure. In length of Within the calculation window, the normalized stress relaxation rate Represented as:

[0064] In discrete implementation, the normalized stress relaxation rate It can be represented as:

[0065] in, This is the sequence number of the current sampling time; This represents the filtered sealing pressure corresponding to the current sampling moment; The number of times before the current sampling time The filtered sealing pressure corresponding to each sampling interval; The sampling period; To calculate the number of sampling intervals contained in the window, and It is a positive integer. As the sealing pressure decreases with time, The result of this calculation It is a positive value. Using a normalized form can reduce the impact of different packaging specifications and target sealing pressures on the relaxation rate threshold scale.

[0066] Step S700: Perform dual-condition judgment of pressure error and stress relaxation rate, and micro-feed compensation. Controller 20 sets the lower limit of sealing pressure. Pressure recovery limit Stress relaxation rate initiation threshold and stress relaxation rate exit threshold ,in , .

[0067] when If the conditions are met or satisfy and The controller 20 sets the micro-compensation state to feed, driving the two inclined wedge sliders 14 to move synchronously towards each other, so that the vertical push block 15 is micro-feeded towards the heat sealing knife 6.

[0068] when If the conditions are met or satisfy and The controller 20 sets the micro-compensation state to stop, stops the micro-feeding, and maintains the current position by the position closed loop of the servo motor 12 and / or the servo brake.

[0069] when And satisfy as well as At this time, controller 20 maintains the previous control state. Pressure threshold. With rate threshold These constitute hysteresis zones, which can reduce frequent start-stop cycles caused by pressure or rate fluctuations around a single threshold.

[0070] when At that time, before the packaging material has entered the set effective heat-sealing temperature window, the controller 20 stops further micro-feeding and maintains the current position of the vertical pusher 15 to avoid misinterpreting the initial mechanical positioning process of mold closing as material stress relaxation. When the temperature is abnormal, the controller 20 stops the micro-feed and the heating element 28, outputs a temperature abnormality signal, and switches to the abnormal handling or safe mold opening process.

[0071] In one specific control method, after the controller 20 enters the feed state, it determines the single micro-feed command quantity based on the pressure error between the current sealing pressure and the target sealing pressure, and the excess amount of the normalized stress relaxation rate relative to the start-up threshold.

[0072] in, This refers to the amount of a single micro-feed command. To achieve the target sealing pressure; This refers to the sealing pressure after filtering. This represents the normalized stress relaxation rate. This is the threshold for initiating the stress relaxation rate. This is the pressure error coefficient; The relaxation rate coefficient; This represents the maximum micro-feed amount per cycle. This indicates that the calculation result will be restricted to zero. The limiting function between. The result of the above formula can also be converted into the micro-feed rate within a limited duration. This control formula is only one implementation method. The controller 20 can also use table lookup, piecewise linear or model prediction methods to determine the single micro-feed amount or micro-feed rate, but all are subject to the constraints of the total stroke of the micro-compensation mechanism, the maximum single micro-feed amount and the upper limit of the sealing pressure.

[0073] Step S800: Pressure holding ends and micro-compensation reset. When the set pressure holding time is reached, or the verified heat sealing end condition is met, the controller 20 stops the closed-loop micro-feed and controls the servo motor 12 to move the two wedge sliders 14 in opposite directions. The displacement detector 19 confirms that the vertical push block 15 has returned to the preset retraction position; the reset assembly causes the vertical push block 15 and the floating heat sealing knife support 5 to return along with the retraction of the wedge sliders 14. If the preset retraction position is not confirmed within the preset time, the over-dead-point lock is maintained, a reset abnormal signal is output, and the main drive cylinder 4 is prohibited from performing the unlocking action.

[0074] Step S900: Release the dead-point lock and open the mold. After confirming that the micro-compensation mechanism has been reset, the controller 20 controls the main drive cylinder 4 to retract, causing the main hinge pin 9 to disengage from the dead-point limit member 10 and cross the center line back to the unlocked side, thereby driving the heat-sealed main beam 3 to rise and complete the mold opening.

[0075] During the pressure holding phase, if the locking signal of the locking state detection element 18 is lost, the controller 20 stops further micro-feeding, maintains or brakes the current position of the micro-compensation, and outputs a locking abnormality signal; subsequently, unloading or controlled mold opening is performed according to the equipment safety strategy. If the displacement detection element 19 detects that the micro-compensation mechanism has reached its limit stroke, but the sealing pressure has not yet entered the qualified range, or if the force sensor 16 is overloaded, disconnected, or significantly drifts, the controller 20 stops the compensation for that cycle and outputs the corresponding abnormal signal.

[0076] Each control parameter can be determined through material and process verification. Preferably, temperature-pressure curves of multiple qualified heat-sealing cycles are first collected under conditions without micro-compensation to determine the temperature range and pressure relaxation rate distribution when the material enters the softening stage; then, qualified sealing strength, peel consistency, and seal integrity are used as constraints to determine... .in, The normalized rate is higher than the upper limit of normal measurement rate caused by noise and mechanical vibration. Below This is to create a stable exit hysteresis.

[0077] Example 3: Zone compensation device and its control.

[0078] like Figure 4 As shown, for a long heat-sealing area, it is set along the length of the heat-sealing blade. 5 floating heat sealing knife support seats Each floating heat-sealing knife support 5 corresponds to an independent micro-compensation mechanism, a force sensor 16, and a displacement detection element 19, and retains only vertical micro-displacement freedom through its own vertical guide structure. Multiple floating heat-sealing knife supports 5 together support a continuous heat-sealing knife 25, so that each zone acts on the same continuous heat-sealing working surface.

[0079] The continuous heat-sealing knife 25 has a thinning groove 26 between adjacent floating heat-sealing knife supports 5. The thinning groove 26 opens from the side opposite to the heat-sealing working surface and retains a continuous thin-walled bridging portion 27 between itself and the heat-sealing working surface. The continuous thin-walled bridging portion 27 maintains material continuity on the working surface side and can elastically flex when there is a small displacement difference between adjacent sections, avoiding the formation of rigid steps or discontinuous seams on the heat-sealing working surface.

[0080] The heating element 28 extends along the length of the continuous heat-sealing knife 25 and is arranged between the heat-sealing working surface and the bottom of the thinning groove 26. The thinning groove 26 avoids the heating element 28 in both the length and depth directions, without cutting off the heating element 28 and its continuous conductive or thermal path. The heating element 28 may be an electric heating tube, a resistance heating strip, or other continuous heating element formed in the knife body and embedded in the continuous heat-sealing knife 25.

[0081] The width, depth, and bottom fillet radius of the thinning groove 26, as well as the thickness of the continuous thin-walled bridging portion 27, are determined based on the material's elastic modulus, yield strength, thermal expansion characteristics, adjacent section spacing, allowable displacement difference, and the position of the heating element 28 of the continuous heat-sealing blade 25. During the design process, the displacement difference between adjacent sections is ensured to reach... At this time, the continuous thin-walled bridging portion 27 remains within the allowable elastic deformation range, and the temperature difference of the heat-sealing working surface is within the allowable range verified by the process. The end of the thinning groove 26 preferably adopts a rounded transition to reduce stress concentration during cyclic deflection.

[0082] like Figure 6 As shown in (b), controller 20 according to the... The sealing force measured by the 16 zone force sensors and the effective sealed area of ​​the zone Calculate the sealing pressure of the partition:

[0083] And calculate the area-weighted average pressure:

[0084] Controller 20 handles overall pressure regulation and zone-based equalization regulation separately. It calculates the pressure based on area-weighted average. With target pressure The error is used to generate a common feed rate that applies to all partitions. According to the pressure of each zone Area-weighted average pressure The deviation is used to generate the original differential correction amount for each partition. One implementation method is as follows:

[0085] in, For common feed coefficient, This is the differential correction factor.

[0086] To ensure that the differential correction does not change the overall feed rate in the area-weighted sense, the original differential correction is normalized as follows:

[0087] Therefore, the following is satisfied:

[0088] No. The candidate feed instructions for each partition are:

[0089] The controller 20 performs single-zone stroke limiting, single-feed limiting, and adjacent zone displacement difference constraints on candidate feed commands. Let the... The cumulative vertical position after each partition is executed is Then it should satisfy:

[0090] The controller 20 can use a successive pair limiting, constraint projection, or secondary optimization method to project candidate feed commands into the feasible region that satisfies the above constraints. If the limiting changes the differential correction amount, the controller 20 can perform area-weighted zeroing again among the remaining partitions that have not reached the travel boundary, in order to maintain the decoupling relationship between common feed and differential correction as much as possible.

[0091] Each zone still determines whether micro-feeding is allowed according to the temperature window and pressure-stress relaxation rate hysteresis logic of Example 2. The common feed rate is used to maintain the area-weighted average pressure, and the differential correction rate is used to reduce the deviation of local pressure from the average pressure. The controller 20 can set the same pressure target for each zone, or it can set different local acceptable ranges according to the packaging bag fold, the number of material layers, or verified process requirements.

[0092] If the displacement detector 19 of any zone detects that the zone has reached its limit stroke, but the corresponding zone sealing pressure has not yet reached the qualified range, the controller 20 determines that there is a clamping abnormality, abnormal number of material layers, abnormal state of the heat sealing knife, or other deviations that cannot be eliminated by the allowable micro-compensation stroke in this cycle, stops the compensation operation for this cycle, and outputs a zone abnormality signal. To avoid excessive deflection of the continuous heat sealing knife 25 under abnormal conditions, the displacement difference constraint between adjacent zones is maintained when compensation is stopped, and then the micro-compensation mechanism is reset in a safe sequence and the over-dead point lock is released.

[0093] When calibrating the partitioned structure, known loads can be applied to calibrate each force sensor 16 and measure the effective sealing area of ​​each partition. A calibration table for the motor position and vertical displacement of each micro-compensation mechanism is established. Temporary calibration temperature sensors can also be arranged along the length of the working surface of the continuous heat-sealing knife 25 to verify the temperature uniformity near the thinning groove 26 and the continuous thin-walled bridging section 27. These temporary calibration sensors can be removed after equipment delivery and are not essential components for the operation of the device.

[0094] In other embodiments, the main drive cylinder 4 can be a single-acting or double-acting cylinder; the servo motor 12 can directly drive the bidirectional lead screw 13, or it can be driven via a reduction mechanism; the temperature sensor 17 can be a thermocouple, a resistance temperature detector (RTD), or other sensors suitable for heat-sealing temperature measurement; the displacement detection element 19 can independently detect the wedge slider 14 or the vertical push block 15, or it can combine a servo encoder with a zero-position switch for position estimation and period calibration. The above substitutions do not change the basic coordination relationship of the macroscopic over-dead-point bearing reference, the independent mirror wedge micro-compensation, and the control based on temperature windows and pressure stress relaxation characteristics.

[0095] This invention applies to medical paper-plastic bags, plastic-plastic bags, composite film bags, and other medical packaging bags with sealed edges formed by thermoplastic sealing layers. For different packaging materials, the effective heat-sealing temperature window, target pressure, stress relaxation rate threshold, holding time, and maximum permissible micro-feed amount are determined through process validation and stored as formulation parameters. The equipment can record the temperature, sealing pressure, micro-feed displacement, locking status, and abnormal status for each heat-sealing cycle for process verification; whether to save data, the saving format, and the traceability method can be configured according to the equipment application requirements.

[0096] The above embodiments illustrate the structure and control logic of the present invention. Those skilled in the art can make equivalent adjustments to the specific installation method, guidance method, sensor type, and control parameters without departing from the concept of the present invention; all such adjustments should be protected within the scope defined by the technical solution of the claims.

Claims

1. A pressure automatic compensation device of a medical packaging bag heat sealing mechanism, comprising a frame, a lower supporting member fixed to the frame, a heat sealing main beam vertically moving relative to the frame, a main driving cylinder, a floating type heat sealing cutter bearing seat provided below the heat sealing main beam and having a vertical moving degree of freedom, and a heat sealing cutter installed on the floating type heat sealing cutter bearing seat, the heat sealing cutter being provided with a heating element and forming a heat sealing gap with the lower supporting member, characterized in that, Also include: Macro drive mechanism, including a first connecting rod, a second connecting rod, a main hinge pin shaft connecting the lower end of the first connecting rod and the upper end of the second connecting rod, and an over dead point limiting piece arranged on the rack; the upper end of the first connecting rod is hinged to the rack, the lower end of the second connecting rod is hinged to the heat sealing main beam, and the main drive cylinder is connected to the main hinge pin shaft; the main drive cylinder can drive the main hinge pin shaft to pass through the center connecting line between the upper hinge point of the first connecting rod and the lower hinge point of the second connecting rod and abut against the over dead point limiting piece, so that the heat sealing reaction force is transmitted to the rack through the first connecting rod, the second connecting rod and the over dead point limiting piece; Micro compensation mechanism, arranged between the heat sealing main beam and the floating heat sealing knife bearing seat, including a micro compensation frame fixed to the heat sealing main beam, a servo motor, a bidirectional screw driven by the servo motor, two inclined wedge blocks arranged in mirror image, and a vertical push block constrained by a straight line guide; two inclined wedge blocks act on the vertical push block through mutually cooperating inclined surfaces, and are driven by the bidirectional screw to move synchronously towards or away from each other, so as to drive the vertical push block to vertically micro feed relative to the heat sealing main beam; the micro compensation mechanism takes the heat sealing main beam in the over dead point locking state as the displacement reference, and the micro feed displacement thereof is not generated by the extension and retraction action of the main drive cylinder; A force sensor arranged between the vertical push block and the floating heat sealing knife bearing seat, a temperature sensor for detecting the temperature adjacent to the working surface of the heat sealing knife, a locking state detection piece for detecting the over dead point locking state, and a displacement detection piece for detecting the micro compensation position; A controller connected with the main drive cylinder, the servo motor, the force sensor, the temperature sensor, the locking state detection piece and the displacement detection piece, and configured to: calculate the sealing pressure according to the sealing force measured by the force sensor and the preset effective sealing area; allow the micro compensation mechanism to start after confirming the over dead point locking, and control the micro compensation mechanism to return to the preset retreat position before releasing the over dead point locking; In the pressure maintaining stage, the micro compensation mechanism is controlled to micro feed according to whether the detected temperature is in the heat sealing effective temperature window and the stress relaxation characteristics of the sealing pressure, and the micro feed is stopped when the sealing pressure reaches the exit condition.

2. The pressure auto-compensator of claim 1, wherein: The center of the main hinge pin shaft is located on the overpass side of the center connecting line, and has a preset vertical offset distance from the center connecting line; in the heat sealing state, the micro compensation mechanism forms a micro compensation force transmission path which does not pass through the gas cavity of the main drive cylinder, and the micro compensation force transmission path sequentially passes through: the micro compensation frame, the inclined wedge block, the vertical push block, the force sensor, the floating heat sealing knife bearing seat, the heat sealing knife, the medical packaging bag to be sealed located in the heat sealing gap, the lower supporting piece, the rack, the first connecting rod, the second connecting rod, the over dead point limiting piece, the heat sealing main beam and returns to the micro compensation frame.

3. The pressure auto-compensator of claim 1, wherein: Two inclined wedge blocks are respectively provided with driving inclined surfaces, and the two sides of the vertical push block are respectively provided with matching inclined surfaces which are slidingly matched with the driving inclined surfaces; two driving inclined surfaces are symmetrically arranged relative to the center plane of the heat sealing knife width, two matching inclined surfaces are symmetrically arranged relative to the center plane of the heat sealing knife width, and the inclination angles of the two driving inclined surfaces are equal and the inclination directions are opposite; the rotation directions of the two threads of the bidirectional screw are opposite.

4. The pressure auto-compensator of claim 1, wherein: The locking state detection member corresponds to the main hinge pin or the over dead point limiting member; the displacement detection member corresponds to the inclined wedge slider or the vertical push block; the displacement detection member is a stroke sensor, a zero position switch or a linear displacement sensor; each inclined wedge slider is respectively provided with a main nut and a pre-tightening nut matched with a corresponding rotation thread segment of the bidirectional screw rod; the servo motor is provided with a servo brake for micro compensation reset or maintaining the current micro feed position of the vertical push block during pause.

5. The pressure auto-compensator of claim 1, wherein: The force sensor is a strain force sensor or a piezoresistive force sensor; in the path of transmitting force to the heat sealing knife, the vertical push block, the force sensor in the pre-tightening state, a ceramic heat insulation pressure bearing plate and the floating heat sealing knife bearing seat are sequentially arranged from top to bottom; the force sensor is kept in the pressure state by a pre-tightening bolt or a disc spring.

6. The pressure auto-compensator of claim 1, wherein, A partition compensation structure is adopted: a plurality of floating heat sealing knife bearing seats are arranged along the length direction of the heat sealing knife, each floating heat sealing knife bearing seat is driven by an independent micro compensation mechanism, and each floating heat sealing knife bearing seat only has a vertical micro displacement degree of freedom; each partition is respectively provided with one force sensor and one displacement detection member; the lower parts of the floating heat sealing knife bearing seats jointly support a continuous heat sealing knife, the continuous heat sealing knife is provided with a thinning groove opening away from the heat sealing working surface between adjacent floating heat sealing knife bearing seats, and a continuous thin wall bridge is reserved between the thinning groove and the heat sealing working surface; the heating element extends along the length direction of the continuous heat sealing knife and is located between the heat sealing working surface and the bottom of the thinning groove, and the thinning groove avoids and does not cut off the heating element in the length direction.

7. A control method for a pressure automatic compensation device applied to a heat sealing mechanism for a medical packaging bag according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: Fast clamping: control the main drive cylinder to act, drive the main hinge pin to cross the center connecting line and abut against the over dead point limiting member; Over dead point locking confirmation: receive the signal of the locking state detection member, and confirm that the macroscopic drive mechanism establishes the reference bearing state; Initial pressure establishment: the micro compensation mechanism performs displacement initial adjustment, the controller calculates the initial sealing pressure according to the sealing force measured by the force sensor and makes it establish to the target interval; Temperature window identification: judge whether the detection temperature representing the temperature of the heat sealing interface is in the heat sealing effective temperature window; Pressure error-stress relaxation rate double condition judgment: extract the filtered sealing pressure signal and the normalized pressure relaxation rate, and perform double condition triggering, hysteresis retention and exit judgment; Micro feed compensation: when the triggering condition is met, the micro compensation mechanism is controlled to perform micro feed to compensate the effective thickness change caused by material softening and stress relaxation under heating; Pressure recovery stop: when the sealing pressure reaches the exit condition, the micro feed is stopped; Micro compensation reset after pressure maintaining: after the heat sealing cycle is completed, the micro compensation mechanism is controlled to retreat to the preset retreat position; Release the over dead point locking and open the mold: after confirmation, the main drive cylinder is controlled to retract to release the over dead point locking and open the mold.

8. The control method according to claim 7, characterized by Setting a lower limit for the sealing pressure Setting an upper limit for the pressure recovery Setting a stress relaxation rate start threshold Setting a stress relaxation rate exit threshold wherein and The specific hysteresis control logic for the double condition judgment and micro-feeding is: When the detected temperature is in the heat-seal effective temperature window, i.e. , the condition for triggering micro-feeding is that any one of the following conditions is met: ; or, and ; the condition for stopping micro-feeding is that any one of the following conditions is met: ; or, and ; the hysteresis retention condition is that when , and the normalized stress relaxation rate satisfies , the previous control state is maintained; when detecting temperature Leaving the heat-seal effective temperature window: if , stop further micro-feeding and maintain the current micro-feeding position of the vertical push block until entering the micro-compensation reset step after the pressure-holding end or the abnormality handling step; if , stop micro-feeding and heating of the heating element, and output a temperature abnormality signal; wherein, , are the lower and upper limits of the heat seal effective temperature window, respectively; is the real-time calculated sealing pressure; is the filtered sealing pressure signal.

9. The control method according to claim 7, characterized by, The pressure automatic compensation device is the pressure automatic compensation device in claim 6, and the following partition coordination and abnormal processing are performed during the heat sealing pressure maintaining stage: calculating the sealing pressure for each zone wherein is the sealing force for the zone, is the effective sealing area for the zone; Computing an area-weighted average pressure ; According to the area-weighted average pressure The error compensation mechanism outputs a common feed amount to all partitions, and outputs a differential correction amount to the corresponding partition according to the deviation of the sealing pressure of each partition from the area-weighted average pressure of each partition from the area-weighted average pressure The differential correction amounts of all the partitions satisfy area-weighted zeroing, that is, wherein is the differential correction amount of the i-th partition; and is the area of the i-th partition. the vertical displacement difference of the adjacent sub-zones micro-feeding is limited to satisfy wherein is the displacement of the first sub-zone, is the displacement of its adjacent sub-zone, is the maximum allowable elastic deflection displacement difference; If the displacement detection member of a certain partition detects that the limit stroke is reached and the corresponding sealing pressure has not reached the qualified range, it is determined that the sealing process is abnormal and the compensation operation of this cycle is stopped.

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