Tensioning mechanism for hot sealing processing of stringing bag

Abstract

The utility model provides a kind of tensioning mechanism for rope-penetrating bag heat-sealing processing, including rack, tensioning assembly, heat-sealing cutting assembly and driving assembly;The tensioning assembly includes first tensioning wheel and second tensioning wheel that are arranged side by side and can rotate intermittently, and tensioning sleeve is arranged on the first tensioning wheel and second tensioning wheel, bag body passes between the first tensioning wheel and the second tensioning wheel and between the second tensioning wheel and tensioning sleeve, to form wavy wrinkle;The heat-sealing cutting assembly is used to heat seal and slitting after the bag body is tensioned;The driving assembly is used to drive the first tensioning wheel and the second tensioning wheel intermittent rotation and drive the heat-sealing cutting assembly action.The utility model realizes the high-quality processing of firm and flat edge sealing, smooth and neat edge cutting, solves the sealing and cutting quality defects caused by bag body relaxation in traditional process.

Description

Technical Field

[0001] This utility model relates to a tensioning mechanism for heat sealing of drawstring bags. Background Technology

[0002] Heat sealing and slitting are the final quality control steps in the production process of drawstring bags. Existing equipment commonly suffers from a technical challenge at this stage: during heat sealing and slitting, the bag body is in a naturally relaxed or only slightly tensioned state. In this state, when the heat-sealing blade presses down to cut, the soft bag material is easily buckled and deformed due to stress, leading to skewed sealing lines, uneven cuts, and even poor sealing and fraying at the cut, severely affecting the product's sealing performance and appearance. Furthermore, traditional heat-sealing and slitting mechanisms generate significant impact force during mold closing, not only producing loud noise and vibration, affecting equipment lifespan, but also crushing the bag material due to instantaneous impact pressure, or causing premature wear of the heat-cutting blade. Although some equipment attempts to increase tension, the tensioning method is mostly simple constant-speed traction, which cannot create an ideal structure to enhance the local rigidity of the bag body. Therefore, there is an urgent need for a high-quality end-processing mechanism that can effectively tension and shape the bag body before heat sealing and slitting, and can buffer the cutting impact. Utility Model Content

[0003] This invention provides a tensioning mechanism for heat-sealing drawstring bags, which can effectively solve the above-mentioned problems.

[0004] This utility model is implemented as follows: A tensioning mechanism for heat-sealing drawstring bags includes a frame, a tensioning assembly, a heat-sealing cutting assembly, and a drive assembly; The tensioning assembly includes a first tensioning wheel and a second tensioning wheel arranged side by side and capable of intermittent rotation, and a tensioning sleeve disposed on the first tensioning wheel and the second tensioning wheel. The bag body passes through the space between the first tensioning wheel and the second tensioning wheel and between the second tensioning wheel and the tensioning sleeve to form a wavy pleat. The heat-sealing and cutting assembly is used to heat-seal and cut the stretched bag. The drive assembly is used to drive the first tensioning wheel and the second tensioning wheel to rotate intermittently and to drive the heat sealing and cutting assembly to operate.

[0005] The beneficial effects of this utility model are: (1) This utility model uses the intermittent tensioning action of the tensioning component to force the bag body to form regular wavy folds before heat sealing and cutting. This structure greatly enhances the local rigidity of the bag body sealing and cutting area, thereby effectively resisting the pressure deformation during the heat sealing and cutting process. At the same time, the S-shaped path formed by the tensioning sleeve and the double tensioning wheel ensures zero slippage and high precision in the tensioning process, and finally achieves high-quality processing with firm and flat sealing and smooth and neat cutting, solving the sealing and cutting quality defects caused by bag body looseness in traditional processes. Attached Figure Description

[0006] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0007] Figure 1 This is the complete production line of this utility model.

[0008] Figure 2 This is a schematic diagram of the structure of the rope-threading mechanism of this utility model.

[0009] Figure 3 This is a utility model Figure 2 A schematic diagram of the structure of the middle limit guide.

[0010] Figure 4 This is a rear view of the winding and conveying mechanism of this utility model.

[0011] Figure 5 This is a front view of the winding and conveying mechanism of this utility model.

[0012] Figure 6 This is a schematic diagram of the hot-pressing, cutting, and tightening mechanism of this utility model.

[0013] Figure 7 This is a schematic diagram showing the connection of the first tensioning wheel, the second tensioning wheel, and the tensioning sleeve of this utility model.

[0014] Figure 8 This is a system flowchart of this utility model. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Therefore, the following detailed description of the embodiments of this utility model provided in the accompanying drawings is not intended to limit the scope of the claimed utility model, but merely to represent selected embodiments of this utility model.

[0016] In the description of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0017] Reference Figure 1-8 As shown, a tensioning mechanism for heat-sealing drawstring bags includes a frame, a plurality of guide rollers on the bag conveying path mounted on the frame, a folding assembly, and a tension adjusting assembly; the folding assembly is used to fold the two sides of the bag during conveying; the tension adjusting assembly includes a mounting frame movably mounted on the frame, at least one ninth roller mounted on the mounting frame, and a push-pull device for driving the mounting frame to reciprocate; the push-pull device is a cylinder, a hydraulic cylinder, or an electric push rod.

[0018] The folding assembly includes a folding plate with a guide slope at its inlet end and an outlet end extending to the bag sealing station. A perforated groove is formed on the folding plate. A folding wheel is also located near the outlet end of the folding plate, with its rim contacting the folded edge of the bag. One side of the folding plate is connected to a connecting rod. The folding wheel is mounted on the frame via an adjusting component. The bag conveying path includes an S-shaped path formed by a first roller, a second roller, a third roller, a fourth roller, a fifth roller, a sixth roller, a top roller, a seventh roller, and an eighth roller. This path is a multi-segment, large-angle curved surface path composed of the first to eighth rollers. According to the Euler-Eitelwin formula, the friction between the conveyor belt (in this case, the bag) and the rollers increases exponentially with the increase of the wrap angle. The S-shaped path creates a huge total wrap angle, thus providing a "static friction driving force" far exceeding that of conventional paths, ensuring strong tensile output and preventing slippage. At the same time, the bag is forced to adhere to the rollers in different directions during repeated travel. This process is like "roller pressing and leveling," which can effectively eliminate uneven stress and initial wrinkles inside the bag material, allowing it to reach the optimal flatness before entering the critical work station.

[0019] Furthermore, the folding plate is a gradually curved surface rather than a single plane, ensuring that the edge of the bag can be smoothly and gradually guided from a horizontal state to the target folding angle (usually 180°), avoiding stress concentration and wrinkles caused by abrupt bending. The hollowed-out grooves on it serve two purposes: reducing weight and facilitating real-time monitoring of the folding status. They also prevent material deformation or adhesion caused by long-term friction and heat between the bag and the steel plate.

[0020] A separating rod is installed at the entrance area of ​​the bag conveying path to separate stacked bags. This utilizes the static friction difference between the stacked materials. When the bottom bag is pulled out, the separating rod provides downward resistance to the bags above, successfully achieving single-sheet separation. The frame also has several first and second mounting rods, and first and second connecting pieces are detachably mounted on these rods. These connecting pieces connect to the ends of a third and fourth roller, respectively, allowing for adjustment and fixation of the third and fourth rollers. The frame includes opposing side plates, a limiting rod positioned between the side plates, and a side plate positioned on the limiting rod. The side plates are inclined inwards and contact the end face of the bag, thereby tightening the bag. Furthermore, the inclined plane of the side plate generates a normal force, which can be decomposed into a vertical supporting force and a horizontal clamping force. This horizontal component continuously "squeezes" the two sides of the bag inward, thereby generating a uniform lateral friction force, effectively eliminating the "deviation" or "snake-like" phenomenon of the bag during transportation, and ensuring the centering of the bag.

[0021] Specifically, the hot-press slitting and tensioning mechanism 120 includes a frame, a tensioning assembly, a heat-sealing and cutting assembly, and a drive assembly. The tensioning assembly includes a first tensioning wheel and a second tensioning wheel arranged side-by-side and capable of intermittent rotation, and a tensioning sleeve disposed on the first and second tensioning wheels. The bag body passes between the first and second tensioning wheels and between the second tensioning wheel and the tensioning sleeve to form a wavy pleat. A buffer mechanism is also included to cushion the impact when the heat-sealing and cutting assembly closes the mold. The other end of the tensioning sleeve is connected to a pull rod, thereby fixing the tensioning sleeve between the first and second tensioning wheels and the pull rod. The heat-sealing and cutting assembly is used to heat-seal and cut the stretched bag. The assembly includes a long connecting rod, an upper plate, a lower plate, a hot-cutting blade, a buffer rod, and a limiting cutting plate. The hot-cutting blade is mounted on the long connecting rod, which passes through a connecting block between the upper and lower plates and connects to the base. The limiting cutting plate has a cutting groove corresponding to the hot-cutting blade. When the hot-cutting blade moves up and down, the upper plate buffers the downward cutting force of the blade through the buffer rod, allowing the upper and lower plates to close relative to each other for heat sealing and cutting. The hot-cutting blade is connected to a power source that drives its movement via the long connecting rod. The drive assembly drives the first and second tensioning wheels to rotate intermittently and drives the heat-sealing and cutting assembly. The surfaces of the first and second tensioning wheels are textured or coated to increase friction. A limiting cylinder and a movable rod connected to the limiting cylinder are provided on the frame. The movable rod passes through the base and connects to the upper support, and a buffer spring is sleeved on the movable rod, so that the force is absorbed and buffered when the base moves up and down.

[0022] Furthermore, the bag body sequentially wraps around the first tensioning wheel and the second tensioning wheel, and then wraps around the tensioning sleeve in the opposite direction, forming a double "C" shaped S-path. This design significantly increases the wrap angle between the bag body and the tensioning component. According to Euler's formula for friction of flexible bodies, this multiplies the maximum static friction force, ensuring absolutely zero slippage during the tensioning process. Each tensioning action can be precisely converted into the deformation of the bag body. The movement of the tensioning wheel is not uniform, but an intermittent cycle of "stationary → acceleration → high speed (instantaneous) → deceleration → stationary". In the "high speed" stage, the linear velocity (V_pull) of the tensioning wheel is set to be much higher than the main conveying speed (V_feed) of the bag body. This positive velocity difference (ΔV = V_pull - V_feed>0) causes the tensioning wheel to "take away" a fixed length of bag from upstream in a very short time. Since the bag is clamped from both ends, this "taken away" bag has nowhere to go and can only buckle and become unstable due to longitudinal compression between the two tensioning wheels, thus forming regular, wavy folds (corrugated) perpendicular to the conveying direction.

[0023] The tensioning sleeve is typically made of a high-friction, high-elasticity material such as polyurethane. It is not a completely rigid support but rather a flexible anvil. The pull rod is a precision tension adjuster; by rotating the nut on the pull rod, the bending tension of the tensioning sleeve can be precisely controlled. Tightening: A taut tensioning sleeve increases the gripping force on the bag, resulting in a more secure hold, higher tensioning efficiency, and deeper corrugations. Loosening: A relaxed tensioning sleeve provides better adaptability to thick or hard materials, preventing excessive compression and damage to the bag.

[0024] It's important to note that the hot-cutting blade is not simply a cutting edge, but a heated blade with an integrated heating unit. Its working process is as follows: first, it melts, then it cuts. As the hot-cutting blade descends, the high-temperature blade contacts the bag, instantly melting the contact surface of the upper and lower layers of fabric (usually PP / PE). The blade continues downward, and the pressure cuts through the molten area. Simultaneously, the molten plastic is squeezed to both sides of the cut, where it re-fused under pressure, forming a fused seal. This means that sealing and cutting are completed simultaneously in one action, and the cut edge is automatically sealed, completely eliminating burrs and frayed edges. The long connecting rod connected to the hot-cutting blade provides a long stroke, ensuring sufficient space for acceleration and stability. Its cooperation with the linear bearing ensures absolute verticality of the downward movement, preventing oblique cuts. The cutting grooves on the limiting cutting plate are not only for avoiding the blade. Too small a gap will cause the blade to clamp, while too large a gap will cause the material to stretch and deform during cutting. The appropriate gap allows the blade to cleanly and neatly cut the molten material while providing adequate compression space for sealing.

[0025] Furthermore, a buffer rod (usually with a built-in compression spring or a polyurethane buffer pad) is located between the upper plate and the hot cutting blade. When the hot cutting blade contacts the bag and begins to encounter resistance, the drive source (such as a hydraulic cylinder) continues to descend. At this time, the buffer rod is compressed, absorbing this excess stroke and energy, thereby transforming the impactful instantaneous cutting force into a continuous and stable holding pressure. This holding pressure is maintained for a moment after cutting through the bag, ensuring that the molten sealing edge has enough time to cool and solidify under pressure, forming a strong seal. When the entire heat-sealing and cutting assembly (base, upper plate, hot cutting blade, etc.) is driven downward to close the mold, the huge kinetic energy is absorbed by the secondary buffer consisting of the moving rod, the limiting cylinder, and the buffer spring.

[0026] Also includes Central processing unit; The central processing unit controls the tensioning frequency and amplitude of the tensioning components, so that the surface of the bag forms a corrugated structure.

[0027] The central processing unit can be an industrial computer (IPC) or a programmable logic controller (PLC), and the central processing unit, motion control module, servo driver and sensing module are connected through an industrial Ethernet bus to form a distributed real-time control system.

[0028] Furthermore, the central processing unit is also connected to a data logging unit for continuously recording key data during the production process, such as actual production quantity, operating time of each mechanism, fault alarm history, and bag tension fluctuation curves. Based on this historical data, the system can generate production efficiency reports and quality trend analyses, providing decision support for process optimization and equipment maintenance.

[0029] The storage unit stores preset production programs. It supports saving and one-click recall of multiple production recipes. Each recipe includes not only process parameters but also a specific product batch number. At the start of production, the batch number is entered via the human-machine interface, and the system automatically records the start and end times and key data for that batch, enabling product information traceability.

[0030] The motion control module, communicating with the central processing unit, sends control commands to the bag winding mechanism 10, winding conveyor mechanism 20, punching mechanism 40, coding mechanism 50, guide rope threading mechanism 60, sealing mechanism 80, rope cutting mechanism 90, and hot-press slitting and tensioning mechanism 120 according to the production program, to coordinate the start / stop, speed, and phase of each mechanism. The motion control module also controls the first intermittent pressing mechanism 30 and the second intermittent pressing mechanism 70, synchronizing their pressing actions with the intermittent conveying rhythm of the bag. The motion control module controls the tensioning components in the hot-press slitting and tensioning mechanism 120 to perform intermittent tensioning actions, and triggers the heat sealing and slitting components in the mechanism after the tensioning action is completed. The motion control module can be a high-speed positioning unit integrated into the PLC or a separate motion controller.

[0031] Specifically, the motion control module constructs a virtual spindle system as a unified time reference for the entire production line. The rotational speed of this virtual spindle corresponds to the production cycle. For mechanisms requiring continuous or periodic motion, such as the bag winding mechanism 10 and the winding conveyor mechanism 20, the module sets their drive servo motors as "electronic gear driven shafts," maintaining a strict speed ratio with the virtual spindle. This ensures that the linear speed of material conveying is constant and synchronized, fundamentally preventing bag stretching, stacking, or tearing caused by speed mismatch. For the punching mechanism 40, coding mechanism 50, guide rope threading mechanism 60, sealing mechanism 80, and rope cutting mechanism 90, the module allocates a fixed action phase window for each mechanism within one cycle of the virtual spindle. For example, the module controls the punching mechanism 40 to perform a downward pressing action at a specific angle on the spindle, and ensures that the coding mechanism 50 moves to the inkjet printing position only after the punching head is fully raised. This phase management based on a unified time reference ensures that each process is executed precisely according to a preset, irreversible time sequence.

[0032] Furthermore, for the first intermittent pressing mechanism 30 and the second intermittent pressing mechanism 70, the module defines an electronic cam curve for each pressing mechanism. This curve maps the rotation angle of the virtual spindle to the target position of the pressing cylinder or servo motor. When the virtual spindle rotates to a preset angle (for example, the angle corresponding to the first intermittent pressing mechanism 30), the module outputs a smooth position command to drive the mechanism to perform the complete action of "pressing down-holding-lifting up". In other words, regardless of whether the production line is accelerating, decelerating or running at a constant speed, the first intermittent pressing mechanism 30 always presses down precisely at the moment before the bag is conveyed to the punching station for positioning; while the second intermittent pressing mechanism 70 always presses down precisely at the moment after the bag is threaded and before it enters the sealing station to arrange the bag and rope. Their action moments are firmly locked with the intermittent conveying rhythm of the bag in the angle of the virtual spindle, achieving precise timing coordination.

[0033] Furthermore, when controlling the hot-pressing slitting and tensioning mechanism 120, the motion control module sends instructions to the tensioning components (such as a pair of servo-driven tensioning wheels) of the mechanism based on the virtual spindle phase or the completion signal of the previous process, causing them to execute a preset "intermittent tensioning action". This action typically includes a cycle of "quickly clamping the bag body → maintaining tension and forming a corrugated structure → releasing". At the end of the "holding" phase of the tensioning action, the tensioning component or its associated sensor will feed back a high-level "tensioning action completed" signal to the motion control module. This signal is the enabling condition for all subsequent actions. Only after confirming the "tensioning action completed" signal will the motion control module send a start command to the heat-sealing and slitting components (such as heat-sealing blades and cutters) in the mechanism. This ensures that every heat sealing and cutting operation is performed at the moment when the bag is fully tightened and has formed an ideal corrugated structure, thus solving the quality defects of weak sealing and wrinkled cuts caused by loose bag body, while avoiding mechanical damage that may be caused by the equipment performing heat cutting at the wrong time.

[0034] It should be noted that, under the command of the motion control module, the tensioning component (such as the tensioning wheel) travels a very short stroke at a linear speed higher than the bag conveying speed, actively "seizing" a section of the bag. This causes the bag to buckle and become unstable due to compression in the clamped local area, forming continuous wavy pleats perpendicular to the conveying direction, i.e., a corrugated structure. This corrugated structure increases the local rigidity of the bag, making it less prone to buckling deformation during heat sealing and cutting, thus obtaining a smooth cut edge. On the other hand, the gaps between the pleats prevent excessive contact between the heat sealing blade and the bag, preventing thermal adhesion and charring.

[0035] Specifically, the guiding rope threading mechanism 60 also includes a support plate; at least one set of guide rail assemblies and multiple limiting guides disposed on the support plate; the limiting guides are mounted on the support plate via a first connecting rod, and a guiding gap is formed between the limiting arc plate and the first connecting rod; the limiting guides include a collar for the rope to pass through and a limiting arc plate connected to the collar, and a guiding gap for the rope to pass through is formed below the limiting arc plate; the collar is provided with a movable groove, and the limiting arc plate is rotatably mounted on the movable groove; the guide rail assembly includes a first guide rail and a second guide rail arranged in parallel, the first guide rail and the second guide rail can extend into the folded edge of the side of the rope threading bag, and the middle of the first guide rail and the second guide rail are both provided with a groove, so as to facilitate the rope to be embedded in the groove and avoid the rope from getting tangled; the axial direction of the collar is perpendicular to the bag conveying direction, and the arc concave surface of the limiting arc plate faces the rope's exit direction. The limiting guides are made of low-friction engineering plastics or metals with a wear-resistant coating; multiple limiting guides are arranged in a straight line or curve along a preset rope threading path. It also includes a pre-separation plate, the end of which extends into the folded edge of the rope threading bag side to guide the introduction of the guide rail assembly; the pre-separation plate is mounted on the support plate via a second connecting rod.

[0036] The groove formed by machining or installing the middle working section of the parallel first and second guide rails is a continuous groove with a "U" or "V" shaped cross-section. Its dimensions are precisely designed to match the diameter of the rope. It extends along the entire effective working length of the guide rails to ensure that the rope remains under control throughout the entire guiding process.

[0037] Furthermore, the sidewalls of the groove form a physical boundary, confining the rope within the groove. Regardless of equipment vibration, the rope is "held" within the groove, eliminating the possibility of the rope slipping off the guide rail. Simultaneously, for double-rope bags, the two ropes are each confined within their respective grooves on the two guide rails. The grooves physically isolate the two ropes, preventing any opportunity for them to contact or entangle during transport. Moreover, the grooves force the rope to always move along a fixed path, ensuring that the rope's spatial position and angle are highly consistent and predictable when it leaves the guide rail and prepares to enter the bag hole, greatly improving the repeatability and success rate of the rope-threading action.

[0038] Furthermore, the inlet and outlet ends of the groove are each machined with a flared, trumpet-shaped opening. The function of the inlet flared opening is to guide the rope end to "slide in" rather than "collide" with the groove during the initial stage of rope threading or when the rope deviates slightly, ensuring smooth introduction. The function of the outlet flared opening is to ensure that the rope leaves the guide rail smoothly and without impact, entering the next limiting guide component, avoiding jamming caused by sudden geometric changes. After the rope exits from the outlet end of the guide rail, it immediately enters the guide gap formed by the limiting arc plate. This gap is responsible for the "precise positioning and rope exit angle control" of the end, and also ensures that while the guide rail completes its guiding function, its own structure can precisely accommodate and avoid the folded bag material, preventing interference or wear between the guide rail and the bag, reflecting the synergy of the overall design.

[0039] Specifically, the winding and conveying mechanism 20 also includes a frame, and further includes multiple guide rollers on the bag conveying path disposed on the frame, a folding assembly, and a tension adjusting assembly; the folding assembly is used to fold the two sides of the bag during conveying; the tension adjusting assembly includes a mounting frame movably disposed on the frame, at least one ninth roller disposed on the mounting frame, and a push-pull device for driving the mounting frame to reciprocate; the push-pull device is a cylinder, a hydraulic cylinder, or an electric push rod.

[0040] The folding assembly includes a folding plate with a guide slope at its inlet end and an outlet end extending to the bag sealing station. A perforated groove is formed on the folding plate. A folding wheel is also located near the outlet end of the folding plate, with its rim contacting the folded edge of the bag. One side of the folding plate is connected to a connecting rod. The folding wheel is mounted on the frame via an adjusting component. The bag conveying path includes an S-shaped path formed by a first roller, a second roller, a third roller, a fourth roller, a fifth roller, a sixth roller, a top roller, a seventh roller, and an eighth roller. This path is a multi-segment, large-angle curved surface path composed of the first to eighth rollers. According to the Euler-Eitelwin formula, the friction between the conveyor belt (in this case, the bag) and the rollers increases exponentially with the increase of the wrap angle. The S-shaped path creates a huge total wrap angle, thus providing a "static friction driving force" far exceeding that of conventional paths, ensuring strong tensile output and preventing slippage. At the same time, the bag is forced to adhere to the rollers in different directions during repeated travel. This process is like "roller pressing and leveling," which can effectively eliminate uneven stress and initial wrinkles inside the bag material, allowing it to reach the optimal flatness before entering the critical work station.

[0041] Furthermore, the folding plate is a gradually curved surface rather than a single plane, ensuring that the edge of the bag can be smoothly and gradually guided from a horizontal state to the target folding angle (usually 180°), avoiding stress concentration and wrinkles caused by abrupt bending. The hollowed-out grooves on it serve two purposes: reducing weight and facilitating real-time monitoring of the folding status. They also prevent material deformation or adhesion caused by long-term friction and heat between the bag and the steel plate.

[0042] A separating rod is installed at the entrance area of ​​the bag conveying path to separate stacked bags. This utilizes the static friction difference between the stacked materials. When the bottom bag is pulled out, the separating rod provides downward resistance to the bags above, successfully achieving single-sheet separation. The frame also has several first and second mounting rods, and first and second connecting pieces are detachably mounted on these rods. These connecting pieces connect to the ends of a third and fourth roller, respectively, allowing for adjustment and fixation of the third and fourth rollers. The frame includes opposing side plates, a limiting rod positioned between the side plates, and a side plate positioned on the limiting rod. The side plates are inclined inwards and contact the end face of the bag, thereby tightening the bag. Furthermore, the inclined plane of the side plate generates a normal force, which can be decomposed into a vertical supporting force and a horizontal clamping force. This horizontal component continuously "squeezes" the two sides of the bag inward, thereby generating a uniform lateral friction force, effectively eliminating the "deviation" or "snake-like" phenomenon of the bag during transportation, and ensuring the centering of the bag.

[0043] The first sensing module is used to detect the position and / or tension of the bag and generate a first feedback signal to the central processing unit. The central processing unit dynamically adjusts the operating parameters of the winding conveying mechanism 20 and the hot pressing slitting and tensioning mechanism 120 through the motion control module according to the first feedback signal to maintain the stability of the bag tension.

[0044] It also includes a second sensing module that is connected to the central processing unit for detecting the status of the rope; when the second sensing module does not detect the rope, the central processing unit controls the guide rope threading mechanism 60 to pause or issue an alarm.

[0045] Furthermore, a third sensing module is included to monitor whether the punch of the punching mechanism is stuck, whether the temperature of the edge sealing mechanism is abnormal, or whether the current of the drive motor is overloaded. When the central processing unit receives any abnormal signal, it executes a tiered alarm or emergency shutdown.

[0046] A method for producing drawstring bags includes the following steps: S1. Start the production process via the central processing unit; S2. The bag body is continuously or intermittently conveyed by the bag body winding and winding conveying mechanism controlled by the motion control module; S3. During the bag conveying process, control the punching, coding, guiding rope threading, sealing and rope cutting mechanisms to perform corresponding operations according to the preset time sequence; S4. Based on the feedback from the first sensing module, adjust the operating parameters of the conveying and tensioning mechanism in real time to stabilize the bag tension. S5. Control the hot-pressing, cutting, and tightening mechanism to tighten, heat-seal, and cut the finished bags.

[0047] In step S3, the rope threading is completed by controlling the guide component in the guide rope threading mechanism 60 to move synchronously with the bag conveying speed.

[0048] In step S3, the synchronous motion is specifically as follows: the motion control module sets the drive device of the guide component (such as the guide rail or the guide mouth) in the guide rope threading mechanism 60 as an electronic gear driven shaft, so that during the rope threading action execution period, it maintains a 1:1 speed ratio relationship with the virtual main shaft or the winding conveyor driven shaft representing the bag conveying speed, thereby achieving absolute synchronization between the guide component and the bag conveying, and ensuring that the rope is accurately guided into the bag hole during the dynamic process.

[0049] The first intermittent pressing mechanism 30 is controlled to press and position the bag body before the punching station, and the second intermittent pressing mechanism 70 is controlled to press and arrange the bag body after the rope threading station.

[0050] In step S5, the tensioning components are controlled to intermittently tighten the bag body, so that the bag body forms a corrugated shape, and then it is heat-sealed and cut.

[0051] The method also includes: receiving production parameter input through a human-machine interface, and having the central processing unit adjust the control instructions in the production program according to the production parameters. The production parameters include at least: "bag length, production speed, punching position, coding content, rope length, target tension value, tension amplitude and frequency, and heat sealing temperature and time."

[0052] Furthermore, the human-machine interface offers multiple operating modes, including but not limited to: fully automatic mode, semi-automatic mode (for single-step debugging and equipment maintenance), and manual mode (for independent jog control of individual mechanisms). The interface displays the production line's operating status in real-time with animations, including bag position, the phase of each mechanism's action, real-time tension value, and equipment status (running, stopped, alarm). When an alarm occurs, the interface automatically displays an alarm screen, indicating possible causes of the fault and troubleshooting suggestions.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A tensioning mechanism for heat-sealing drawstring bags, characterized in that, Includes frame, tensioning assembly, heat sealing and cutting assembly, and drive assembly; The tensioning assembly includes a first tensioning wheel (20) and a second tensioning wheel (30) arranged side by side and capable of intermittent rotation, and a tensioning sleeve (40) disposed on the first tensioning wheel (20) and the second tensioning wheel (30). The bag body passes through the space between the first tensioning wheel (20) and the second tensioning wheel (30) and between the second tensioning wheel (30) and the tensioning sleeve (40) to form a wavy pleat. The heat-sealing and cutting assembly is used to heat-seal and cut the stretched bag. The drive assembly is used to drive the first tension wheel (20) and the second tension wheel (30) to rotate intermittently and to drive the heat sealing and cutting assembly to operate.

2. The tensioning mechanism for heat-sealing a drawstring bag according to claim 1, characterized in that, The heat-sealing and cutting assembly includes a long connecting rod (160), an upper plate (220), a lower plate (240), a heat-cutting blade (180), a buffer rod (200), and a limiting cutting plate (120). The hot cutting blade (180) is mounted on the long connecting rod (160). The long connecting rod (160) passes through the connecting block between the upper plate (220) and the lower plate (240) and is connected to the base (50). The limiting cutting plate (120) has a cutting groove (140) corresponding to the hot cutting blade (180). When the hot cutting blade (180) moves up and down, the upper plate (220) buffers the downward cutting force of the hot cutting blade (180) through the buffer rod (200), so that the upper plate (220) and the lower plate (240) can close relative to each other to complete the heat sealing and cutting.

3. The tensioning mechanism for heat-sealing a drawstring bag according to claim 2, characterized in that, The frame is provided with a limiting cylinder (60) and a movable rod (70) connected to the limiting cylinder (60). The movable rod (70) passes through the base (50) and is connected to the upper bracket (100). A buffer spring (90) is sleeved on the movable rod (70), so that when the base (50) moves up and down, the buffer spring (90) can absorb the force and buffer the movement.

4. The tensioning mechanism for heat-sealing a drawstring bag according to claim 1, characterized in that, It also includes a buffer mechanism (80) for buffering the impact when the heat-sealing cutter assembly is molded.

5. The tensioning mechanism for heat-sealing a drawstring bag according to claim 2, characterized in that, The hot cutting blade (180) is connected to the power source that drives its movement via a long connecting rod (160).

6. The tensioning mechanism for heat-sealing a drawstring bag according to claim 1, characterized in that, The surfaces of the first tensioning wheel (20) and the second tensioning wheel (30) are provided with textures or coatings to increase friction.

7. The tensioning mechanism for heat-sealing a drawstring bag according to claim 1, characterized in that, The other end of the tension sleeve (40) is connected to the pull rod (260), thereby fixing the tension sleeve (40) between the first tension wheel (20) and the second tension wheel (30) and the pull rod (260).

Images