Active feed system for a bag making machine

Abstract

This specification discloses an active feeding system for a bag-making machine. The bag-making machine includes a feeding motor that provides periodic feeding force. The system includes an active feeding unit, a temporary storage unit, and a tension monitoring unit. The active feeding unit pulls material from outside the system at a preset feeding speed. The temporary storage unit includes a movable roller around which the material enters the system, a drive component that drives the movable roller to move along a defined trajectory to change the material path length, and a control module. The tension monitoring unit monitors the tension of the material inside the system in real time and outputs monitoring information. The control module outputs control signals to the drive component based on the rotational speed of the feeding motor, the preset feeding speed, and the monitoring information, so as to keep the tension of the material inside the system stable. Through the feedforward and feedback control of the control module, high-precision active control of material tension is achieved, thereby adapting to easily stretchable environmentally friendly materials and increasing production speed while ensuring product quality.

Description

Technical Field

[0001] Several embodiments of this specification relate to the field of bag making machine technology, specifically to the optimization of feeding control in an active feeding system for a bag making machine. Background Technology

[0002] In bag manufacturing, maintaining stable and controllable tension in roll materials such as plastic film is crucial for ensuring accurate bag dimensions, secure sealing, and a smooth appearance. Excessive tension can lead to material stretching, deformation, or even breakage, while insufficient tension can cause the material to loosen and wrinkle, affecting subsequent processes.

[0003] To reduce tension at the source, most mainstream bag-making machines currently employ a motor-driven active feeding system. However, because the subsequent heat-sealing and pressing process is a rhythmic cyclical action of "pulling material, stopping, and pressing," a swing arm structure with resistance provided by a cylinder is often incorporated into the system to achieve continuous and even feeding. (See attached reference.) Figure 1 Its working principle is as follows: When pulling the material, the material pulls the swing roller at the end of the swing arm, and the cylinder is stretched to release the stored material; when the pressing stops, the continuous feeding loosens the material, the cylinder contracts and drives the swing arm to return to its original position, temporarily storing the material. This method essentially uses the passive swing of the swing arm and the passive response of the air damper to buffer and adapt to the rhythm changes of the traction mechanism.

[0004] However, with the increasing prevalence of environmentally friendly materials (such as thinner and more stretchable PE films), their stretchability places higher demands on the tension control precision and response speed of the feeding device. On the one hand, the passive adjustment mechanism exhibits a lag in response, making it difficult to keep up with the drastic "start-stop" rhythm changes of the traction mechanism during high-speed production, easily causing instantaneous tension fluctuations. On the other hand, the tension generation depends on the opposing relationship between the "pull" of the traction mechanism and the "resistance" of the swing arm damping; the material must withstand a certain tensile force to maintain flatness, which contradicts the "near-zero tension" process requirement of environmentally friendly materials. In practice, to improve the response speed under high-speed production, it is often necessary to increase the cylinder rebound force, which in turn leads to a higher average tension on the material during the next pull. Ultimately, to protect the material, the production speed must be reduced, thus limiting production efficiency. Summary of the Invention

[0005] This specification provides an active feeding system for a bag-making machine, which aims to solve the problem of sudden changes and instability in material tension caused by passive feeding in high-speed, rhythmic production of bag-making machines. Through an active feeding, temporary storage, and tension monitoring unit coordinated by a control module, high-precision active control of the material tension inside the system is achieved, thereby adapting to easily stretchable environmentally friendly materials and improving production speed and product quality.

[0006] The technical solution is as follows:

[0007] An active feeding system for a bag making machine, the bag making machine including a pulling motor that provides periodic pulling driving force, the system including an active feeding unit, a temporary storage unit and a tension monitoring unit;

[0008] The active feeding unit pulls the material from outside the system at a preset feeding speed;

[0009] The temporary storage unit includes a movable roller that surrounds the material entering the system, a drive component that drives the movable roller to move along a defined trajectory to change the length of the material path, and a control module.

[0010] The tension monitoring unit monitors the tension of the materials inside the system in real time and outputs monitoring information.

[0011] The control module outputs control signals to the drive component based on the rotational speed of the feeding motor, the preset feeding speed, and monitoring information, so as to keep the tension of the material inside the system stable.

[0012] As a preferred embodiment, the tension monitoring unit includes two fixed rollers around which the material entering the system is surrounded, a floating roller disposed between the two fixed rollers and capable of floating up and down relative to the fixed rollers, and a sensor for monitoring the position change of the floating roller. The material entering the system surrounds the same side of the two fixed rollers and surrounds the other side of the floating roller.

[0013] As a preferred embodiment, the core of the floating roller is provided with a connecting rod that is rotatably connected to any of the cores of the fixed roller, and the sensor is an encoder located at the rotatable connection point of the connecting rod.

[0014] As a preferred embodiment, the tension monitoring unit is located on the side of the temporary storage unit away from the active discharge unit.

[0015] As a preferred embodiment, the drive assembly includes two wheel sets located at both ends of the movable roller, a belt surrounding the wheel sets, and a drive motor for rotating the wheel sets;

[0016] The roller core of the movable roller is fixedly connected to the belts on both wheel sets;

[0017] The control module outputs control signals to the drive motor based on the rotational speed of the feeding motor, the preset feeding speed, and monitoring information, so as to drive the movable roller to move with the belt;

[0018] The control module outputs control signals to the drive motor based on the rotational speed of the feeding motor, the preset feeding speed, and monitoring information, so that the movable roller moves with the belt to maintain stable material tension inside the system.

[0019] As a preferred embodiment, the belts of both wheel sets are vertically arranged.

[0020] As a preferred embodiment, the active feeding unit includes a feeding roller group that clamps the material and a feeding motor that drives the feeding roller group; the fixed roller near the temporary storage unit is a fixed roller group that includes two sub-fixed rollers with gaps and located on the upper and lower sides of the material entering the system; the movable roller is a movable roller group that includes two sub-movable rollers with gaps and located on the upper and lower sides of the material entering the system.

[0021] The fixed roller group and the feeding roller group are symmetrically arranged on both sides of the belt of the two wheel groups and at the same height as the midpoint of the belt length.

[0022] As a preferred embodiment, the control module takes the midpoint of the belt length as the default position of the movable roller group, obtains the highest and lowest positions of the movable roller group on the belt based on the horizontal distance between the movable roller group and the feeding roller group and the single feeding length, obtains the storage speed curve from the default position to the highest and lowest positions based on the preset feeding speed, obtains the feeding speed curve from the highest and lowest positions to the default position based on the preset feeding speed and the rotation speed of the feeding motor, obtains the feeding speed curve from the highest and lowest positions to the default position, and obtains a compensation signal based on monitoring information. The storage speed curve, feeding speed curve and compensation signal are used as control signals and output to the drive motor.

[0023] As a preferred embodiment, the control module is connected to the feeding motor;

[0024] The control module also adjusts the rotation speed of the feeding motor based on the monitoring information corresponding to the active roller group at the default position, so as to match the preset feeding speed.

[0025] As a preferred embodiment, the control module obtains a correction signal based on the monitoring information corresponding to the default position of two adjacent active roller groups and outputs it to the feeding motor.

[0026] The beneficial effects of the technical solutions provided in some embodiments of this specification include at least the following:

[0027] This invention innovatively combines the known motion law of the material pulling motor with the real-time state of material tension through a control module, dynamically and precisely controlling the movement trajectory of the movable roller. This allows the system to not only actively adapt to the periodic material pulling cycle but also resist random disturbances in real time, ultimately ensuring that the material tension inside the system remains highly stable under high-speed production conditions. This technical solution is particularly suitable for bag making of thin, easily stretchable environmentally friendly materials (such as PE film) that are extremely sensitive to tension, effectively avoiding material stretching deformation or wrinkling, and significantly improving production speed and efficiency while ensuring product quality. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the existing active feeding system described in the background section of this specification, showing the swing arm structure.

[0030] Figure 2 This is a schematic diagram of the overall structure of the active feeding system of a bag making machine provided in Embodiment 1 of this specification.

[0031] Figure 3 This is a schematic diagram of the active feeding system of a bag making machine provided in Embodiment 1 of this specification, showing the material transfer path into the system.

[0032] Figure 4 This is a schematic diagram of the active feeding system of a bag making machine provided in Embodiment 2 of this specification, showing the transmission path of the material entering the system in the upper half of the belt at the midpoint.

[0033] Figure 5 This is a schematic diagram of the active feeding system of a bag making machine provided in Embodiment 2 of this specification, showing the transmission path of the material entering the system in the lower half of the belt.

[0034] In the diagram: 1. Active feeding unit; 11. Feeding roller group; 2. Temporary storage unit; 21. Movable roller; 211. Sub-movable roller; 22. Drive assembly; 221. Wheel group; 222. Belt; 3. Tension monitoring unit; 31. Fixed roller; 311. Sub-fixed roller; 32. Floating roller; 321. Connecting rod. Detailed Implementation

[0035] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings.

[0036] The terms "first," "second," "third," etc., in the description, claims, and accompanying drawings are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus.

[0037] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this specification. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0038] Example 1

[0039] An active feeding system for a bag making machine

[0040] Reference Figure 2 , Figure 3 As shown, an active feeding system for a bag making machine includes a feeding motor that provides periodic feeding driving force, and the system includes an active feeding unit 1, a temporary storage unit 2, and a tension monitoring unit 3.

[0041] The active feeding unit 1 pulls the material from outside the system at a preset feeding speed;

[0042] The temporary storage unit 2 includes a movable roller 21 around which the material enters the system, a drive assembly 22 that drives the movable roller 21 to move along a defined trajectory to change the length of the material path, and a control module.

[0043] Tension monitoring unit 3 monitors the tension of the materials inside the system in real time and outputs monitoring information;

[0044] The control module outputs control signals to the drive component 22 based on the rotational speed of the feeding motor, the preset feeding speed, and monitoring information, so as to keep the tension of the material inside the system stable.

[0045] Explanatoryly, this embodiment relates to an active feeding system for a bag-making machine, designed to solve the problem of material (especially easily stretchable environmentally friendly films) deformation caused by inaccurate tension control in traditional passive feeding modes, and the resulting suppression of production efficiency. This system works in conjunction with a feeding motor on the bag-making machine that provides periodic feeding drive force, together forming a material conveying system.

[0046] To illustrate, this system mainly consists of three functional units: active feeding unit 1, temporary storage unit 2, and tension monitoring unit 3, all coordinated by a core control module.

[0047] The active feeding unit 1 is responsible for actively drawing material from outside the system at a preset feeding speed, rather than passively pulling it from subsequent processes. This preset feeding speed is an average linear velocity calculated based on bag-making process parameters (such as single feeding length and feeding interval), and is achieved by controlling the speed of the feeding motor (e.g., using linear velocity control mode) to achieve uniform feeding. This ensures that the total feeding volume and total feeding consumption of the system remain balanced within the macro-cycle, laying the foundation for the stable operation of the entire system.

[0048] The temporary storage unit 2 is the core actuator for the system to achieve dynamic tension adjustment. This unit includes a movable roller 21 around which material entering the system is wrapped and adhered; a drive assembly 22 (typically composed of a servo motor, transmission structure, etc.) that drives the movable roller 21 along a defined trajectory (e.g., a guide rail); and a control module. By controlling the movement of the movable roller 21 through the drive assembly 22, the total length of the material's path within the system is dynamically changed. Specifically, during the pressing stage of the bag-making machine (when material feeding stops), although the material feeding motor pauses, the active feeding unit 1 continues to feed material at a constant speed. At this time, the control module instructs the drive assembly 22 to move the movable roller 21 towards the "storage" direction (e.g.,...). Figure 3 The roller 21 moves downwards to temporarily store excess material that is continuously being fed in; in the subsequent feeding phase, the control module instructs the active roller 21 to move in the "feeding" direction (e.g., downwards). Figure 3 The rising motion of the roller 21 actively and synchronously releases the previously stored material to meet the material pulling requirements. Through this periodic reciprocating motion of the roller 21, dynamic storage and release of material are achieved, buffering the intermittent impact of the material pulling action.

[0049] The tension monitoring unit 3 is used to sense the actual tension state of the material inside the system in real time and convert it into processable monitoring information, such as electrical signals. Implementation methods include directly installing tension sensors in the material path, but this is costly; or using non-contact distance sensors (such as ultrasonic sensors or laser rangefinders) aligned with the free segment of the material, measuring the sag or position of a point on the material at high frequency, and indirectly calculating the tension based on the physical relationship between the material sag and tension. However, the reliability of this monitoring method is relatively insufficient.

[0050] The control module is responsible for making decisions and outputting control signals to the drive component 22 of the temporary storage unit 2. Its control strategy combines feedforward and feedback control. First, feedforward control is based on the known, periodic rotational speed (motion curve) of the pulling motor and the preset feeding speed. The control module obtains the complete motion program of the pulling motor in advance, treating the pulling motor as the master axis and the servo motor driving the movable roller 21 as the slave axis. Through mathematical calculations and kinematic transformations, a motion curve is pre-generated that matches the linear velocity of the movable roller 21 at the material contact point with the speed curve of the pulling motor. This achieves predictive active feeding, offsetting most of the tension fluctuations caused by the start and stop of the pulling process. Second, feedback control is based on the real-time monitoring information output by the tension monitoring unit 3. Due to the existence of unknown interferences such as mechanical transmission errors and material slippage, simple feedforward control cannot guarantee absolute tension stability. The control module continuously compares the deviation between the monitored actual tension and the ideal tension and immediately calculates this deviation (e.g., using a PID algorithm) to generate a real-time correction. This correction amount is dynamically superimposed on the ideal motion curve generated by the feedforward, thereby fine-tuning and compensating for the instructions of the drive component 22 to eliminate minor deviations.

[0051] In summary, this invention innovatively combines the known motion law of the material pulling motor with the real-time state of material tension through a control module, dynamically and precisely controlling the motion trajectory of the movable roller 21. This allows the system to not only actively adapt to the periodic material pulling rhythm but also resist random interference in real time, ultimately ensuring that the material tension inside the system remains highly stable under high-speed production conditions. This technical solution is particularly suitable for bag making of thin, easily stretchable environmentally friendly materials (such as PE film) that are extremely sensitive to tension, effectively avoiding material stretching deformation or wrinkling, and significantly improving production speed and efficiency while ensuring product quality.

[0052] In one embodiment of this specification, the tension monitoring unit 3 includes two fixed rollers 31 around which material enters the system and a floating roller 32 disposed between the two fixed rollers 31 and capable of floating up and down relative to the fixed rollers 31, as well as a sensor for monitoring the position change of the floating roller 32. The material entering the system surrounds the same side of the two fixed rollers 31 and surrounds the other side of the floating roller 32.

[0053] Explained, the tension monitoring unit 3 includes two fixed rollers 31, a floating roller 32, and a sensor. The two fixed rollers 31 are arranged parallel and spaced apart, their ends reliably mounted on the system frame, maintaining a fixed position during monitoring to provide a defined path reference for the material. The floating roller 32 is arranged parallel between the two fixed rollers 31, but its mounting allows it to float freely up and down relative to the fixed rollers 31 within a certain range. The sensor (such as a linear displacement sensor, encoder, or potentiometer) is configured to monitor the positional changes of the floating roller 32 in real time and accurately, converting them into an electrical signal output.

[0054] Illustratively, the monitoring of this unit is based on a material flow path design, where the material entering the system circles both fixed rollers 31 on the same side and simultaneously circles the floating roller 32 on the other side. (Refer to...) Figure 3 The material first passes over the top of a fixed roller 31, then over the bottom of a floating roller 32, and finally over the top of another fixed roller 31. In this arrangement, the material tension acts directly on the floating roller 32. When the material tension increases, it exerts an upward pull on the floating roller 32, causing it to float; when the material tension decreases, the floating roller 32 sinks under its own gravity. Through this mechanical structure, the change in material tension is linearly converted into a change in the vertical displacement of the floating roller 32. The sensor continuously detects this displacement, thereby indirectly, in real time, and with high resolution reflecting the actual tension value of the material inside the system, providing feedback signals to the control module.

[0055] It should be noted that the aforementioned winding direction is not unique; the material can also be designed to wrap around the lower sides of the two fixed rollers 31 and the upper side of the floating roller 32. In this configuration, the weight of the floating roller 32 will cause it to tend to move downwards. In this case, its weight can be balanced and an adjustable initial tension reference for the system can be provided by setting an elastic structure (such as a tension spring) on ​​the support structure such as the roller core of the floating roller 32 to provide a force in the opposite direction. Regardless of the specific winding direction and counterweight method used, the core monitoring mechanism remains the same.

[0056] The mechanical tension monitoring unit 3 has a simple and reliable structure, and achieves stable and accurate closed-loop control.

[0057] In one embodiment of this specification, the core of the floating roller 32 is provided with a connecting rod 321 that is rotatably connected to the core of any fixed roller 31, and the sensor is an encoder disposed at the rotatable connection of the connecting rod 321.

[0058] Explained in this embodiment, a specific mechanical and sensing structure is provided for the tension monitoring unit 3. The floating roller 32 is mechanically linked to a designated fixed roller 31 via a rigid connecting rod 321. One end of the connecting rod 321 is rotatably connected to the core of the fixed roller 31 (e.g., via a bearing or hinge), thus forming a crank-connecting rod structure with the core of the fixed roller 31 as the rotation fulcrum, the connecting rod 321 as the connecting rod, and the core of the floating roller 32 as the actuating point. Simultaneously, the sensor employs an encoder (such as a high-precision rotary encoder). The encoder's rotation axis is coaxially arranged with the rotation axis of the connecting rod 321, which swings around the core of the fixed roller 31, or directly coupled via a coupling. When the material tension within the system changes, the floating roller 32 is pulled by the material, resulting in vertical displacement. Because the floating roller 32 is mechanically coupled to the fixed roller 31 via the connecting rod 321, the vertical linear motion of the floating roller 32 is immediately converted into the rotational oscillation of the connecting rod 321 around the core of the fixed roller 31. A definite geometric proportional relationship exists between the displacement of the floating roller 32 and the oscillation angle of the connecting rod 321. The encoder indirectly but linearly measures the displacement of the float roller 32 by measuring this rotational swing angle in real time, and then converts this angle signal into a high-resolution digital or pulse signal, which is output to the control module as monitoring information.

[0059] The measurement reference is transferred from the floating roller 32 itself to the fixed roller 31 core, which is in an absolutely fixed position. The entire sensing mechanism is compact, easy to seal and protect, and the encoder and its mounting base can be firmly fixed to the frame, improving the reliability of long-term operation. Furthermore, the rigid linkage drive also offers high measurement accuracy.

[0060] In one embodiment of this specification, the tension monitoring unit 3 is disposed on the side of the temporary storage unit 2 away from the active discharge unit 1.

[0061] Explaining the material flow, from the perspective of material flow direction, the active feeding unit 1 is located at the upstream end, responsible for introducing material; the temporary storage unit 2 is located in the middle, responsible for dynamically adjusting the path length to buffer flow differences; and the bag-making machine's pulling mechanism is located at the downstream end, which is the source of periodic, large-amplitude tension disturbances. Placing the tension monitoring unit 3 after the temporary storage unit 2, adjacent to the downstream side of the pulling mechanism, allows for the fastest and most direct capture of tension mutations caused by the "start-stop" action of the pulling mechanism. Because the material path between the disturbance source and the monitoring point is the shortest, any change in tension can be transmitted to the monitoring unit with almost no delay, giving its feedback signal extremely high real-time performance, thus achieving rapid response.

[0062] Furthermore, since the temporary storage unit 2 already provides some buffering and isolation for certain slow or minor fluctuations from the upstream feeding unit, the tension signal detected by the downstream monitoring unit can more purely reflect the real-time dynamic balance between the downstream feeding process demand and the upstream supply, filtering out some secondary interferences. This allows the control module to output more precise control commands to drive the movable roller 21, achieving efficient and precise suppression of major tension disturbances.

[0063] Overall, it improves the response speed and control accuracy of the entire closed-loop control system.

[0064] In one embodiment of this specification, the drive assembly 22 includes two wheel sets 221 located at both ends of the movable roller 21, a belt 222 surrounding the wheel sets 221, and a drive motor for rotating the wheel sets 221.

[0065] The roller core of the movable roller 21 is fixedly connected to the belts 222 on both wheel sets 221;

[0066] The control module outputs control signals to the drive motor based on the rotational speed of the feeding motor, the preset feeding speed, and monitoring information, so as to drive the movable roller 21 to move with the belt 222.

[0067] The control module outputs control signals to the drive motor based on the rotational speed of the feeding motor, the preset feeding speed, and monitoring information, so that the movable roller 21 moves with the belt 222 to maintain the stability of the material tension inside the system.

[0068] Explanatoryly, this embodiment proposes a specific structure for the drive assembly 22 of the temporary storage unit 2, employing a synchronous belt 222 transmission mechanism to achieve rapid, precise, and stable linear control of the position of the movable roller 21. Two pulley sets 221 (typically synchronous pulleys) are precisely located at both ends of the movable roller 21. Each pulley set 221 includes two synchronous pulleys located directly above and below, respectively, and the axes of the pairs of synchronous pulleys in the two pulley sets 221 remain parallel. A closed-loop belt 222 (such as a synchronous toothed belt) tightly surrounds the two pulley sets 221, forming a transmission circuit. The output shaft of a drive motor (typically a servo motor) is driven and connected to one of the pulley sets 221, providing it with rotational power. The two ends of the roller core of the movable roller 21 are fixedly connected to the belts 222 on both sides by rigid connecting members (such as clamps or brackets). This makes the movable roller 21 an integrated part of the belt 222, moving synchronously with the belt 222.

[0069] Explanatoryly, when the control module calculates the required speed and direction of motion of the movable roller 21, it outputs corresponding control signals (forward / reverse rotation and speed) to the drive motor. The drive motor then drives the wheel set 221 to rotate, causing the movable roller 21 on the belt 222 to move along the length of the belt 222, thus precisely controlling the rising (discharging) and falling (storing) actions of the movable roller 21.

[0070] The belt drive 222 achieves efficient and direct conversion from rotary motion to linear motion, with a compact structure and fast response speed. Secondly, the combination of the servo motor and the closed-loop belt 222 provides extremely high speed control performance, enabling the movable roller 21 to strictly follow the high-speed, complex motion curve generated by the feedforward and feedback composite algorithm, thereby achieving high synchronization with the material pulling mechanism. This eliminates the additional tension on the material caused by the swing arm damping in traditional swing arm mechanisms, significantly increasing the upper limit of production speed.

[0071] In one embodiment of this specification, the belts 222 of both wheel sets 221 are vertically arranged.

[0072] Explained in this embodiment, the transmission plane formed by the two synchronous pulley sets 221 driving the movable roller 21 and the surrounding belt 222 is positioned perpendicular to the horizontal plane. The movable roller 21, fixedly connected to the belt 222, is also constrained to move vertically in a straight line. For maximum space utilization and motion efficiency, the conversion efficiency between the vertical displacement of the movable roller 21 and the change in material path length is highest when the belt 222 is vertically positioned. Geometrically, under the same material wrap angle conditions, vertical movement is the most direct and effective direction for changing the length of the catenary segment between two fixed points. This means that a shorter vertical stroke of the movable roller 21 is sufficient to achieve the storage or release of a larger material length.

[0073] Illustratively, the use of a vertically positioned belt drive 222 enables the required storage capacity to be achieved within a limited mechanical space with minimal displacement of the movable roller 21. This not only reduces the overall size of the equipment, making the structure more compact, but more importantly, it allows the movable roller 21 to complete the storage and discharging cycle at a faster speed, thereby improving the system's responsiveness and synchronization accuracy to high-speed material pulling cycles.

[0074] Example 2

[0075] An active feeding system for a bag making machine

[0076] The difference between this embodiment and Embodiment 1 is that: the active feeding unit 1 includes a feeding roller group 11 for holding materials and a feeding motor for driving the feeding roller group 11; the fixed roller 31 on the side closer to the temporary storage unit 2 is a fixed roller group including two sub-fixed rollers 311 with gaps and located on the upper and lower sides of the material entering the system; the movable roller 21 is a movable roller group including two sub-movable rollers 211 with gaps and located on the upper and lower sides of the material entering the system.

[0077] The fixed roller group and the feeding roller group 11 are symmetrically arranged on both sides of the belt 222 of the two wheel groups 221 and at the same height as the midpoint of the belt 222.

[0078] Explanatory, reference Figure 4 , Figure 5 As shown, this embodiment proposes a symmetrical double-stroke high-efficiency structure, aiming to reduce the reversing frequency, improve motion smoothness, and extend equipment lifespan. The active feeding unit 1 specifically includes a feeding roller group 11 for clamping and pulling the material, and a feeding motor to drive the roller group, achieving active and uniform material introduction. In the tension monitoring unit 3, the fixed roller 31 near the temporary storage unit 2 is designed as a fixed roller group, consisting of two interlocking sub-fixed rollers 311 located on the upper and lower sides of the material, respectively. Correspondingly, the movable roller 21 is also specifically designed as a movable roller group, similarly consisting of two interlocking sub-movable rollers 211 located on the upper and lower sides of the material, respectively. This roller group design provides stable and symmetrical support and a winding path for the material. More importantly, the fixed roller group and the feeding roller group 11 are symmetrically arranged on both sides of the belt 222 of the two wheel groups 221 driving the movable roller group, and the center height of these two roller groups is consistent with the midpoint of the belt 222's transmission length. This layout constitutes a mirror structure symmetrical about the midpoint of the belt 222's movement.

[0079] Illustratively, because the feeding roller group 11 and the fixed roller group are symmetrically distributed at the midpoints on both sides of the belt 222, the moving roller group can perform a complete "storage-discharge" work cycle without reversing its stroke. For example, it can descend from the upper half to the midpoint of the belt 222 to discharge material, then descend from the midpoint of the belt 222 to the lower half to store material, and then ascend from the lower half in the next cycle. Therefore, the drive motor only needs to change its rotation direction once to complete one process cycle, which reduces the motor's commutation frequency by 50% compared to the traditional layout where it must commutate twice per cycle. Frequent start-stop and reversal of the motor and transmission system are among the main causes of electrical stress, mechanical shock, and thermal fatigue. Significantly reducing the commutation frequency can effectively reduce these losses, thereby significantly extending the service life of core moving components such as the drive motor, belt 222, and pulley group 221, and improving the long-term reliability of the system.

[0080] Through mechanical layout design, the motion mode of the movable roller 21 was optimized without excessively increasing the system complexity. This not only ensured the accuracy of tension control, but also achieved outstanding results in improving the smoothness and durability of the system's motion.

[0081] In one embodiment of this specification, the control module takes the midpoint of the belt 222 as the default position of the movable roller group, obtains the highest and lowest positions of the movable roller group on the belt 222 based on the horizontal distance between the movable roller group and the feeding roller group 11 and the single feeding length, and obtains the storage speed curve from the default position to the highest and lowest positions based on the preset feeding speed, and obtains the feeding speed curve from the highest and lowest positions to the default position based on the preset feeding speed and the rotation speed of the feeding motor, and then obtains the compensation signal based on the monitoring information, and outputs the storage speed curve, feeding speed curve and compensation signal as control signals to the drive motor.

[0082] For illustrative purposes, this embodiment breaks down the complex dynamic control problem into multiple steps.

[0083] The control process begins with system initialization and parameter setting. Different initial positions of the movable roller assembly result in different actual stroke lengths required to release the same amount of material, inevitably leading to different motor speed curves. Through the mechanically symmetrical layout design in Embodiment 2, the control module uses the midpoint of the belt 222 transmission length as the default position of the movable roller assembly; this position is a preset initialization position. Based on two key parameters: the system's fixed mechanical parameters—the horizontal distance between the movable roller assembly and the feeding roller assembly 11; and the product process parameters—the single feeding length—the control module calculates the highest and lowest points on the belt 222 where the movable roller assembly achieves material storage through geometric model calculations. This determines the stroke of the movable roller assembly and avoids significant changes in the speed curve. Simultaneously, the calculation of these two extreme points also defines clear and safe stroke boundaries for the reciprocating motion of the movable roller 21, fundamentally preventing the movable roller 21 from impacting the mechanical hard limit during operation, thus achieving system protection.

[0084] After determining the motion boundaries, the control module plans the speed curves corresponding to each step. Based on the preset feeding speed, the control module calculates the material storage speed curve of the movable roller group moving from the default position to the highest or lowest position, ensuring that the material storage speed of the movable roller 21 precisely matches the continuous feeding speed of the feeding motor. Then, by combining the preset feeding speed with the real-time speed curve of the pulling motor, the control module calculates the feeding speed curve of the movable roller group returning from the highest or lowest position to the default position, ensuring that the linear velocity of the movable roller 21 releasing the material actively and synchronously matches the rhythmic movement of the pulling motor. This simplifies the complex, position-varying control problem into a problem of tracking and optimizing the preset speed curve within a fixed stroke, offering significant engineering advantages. Furthermore, by pre-planning and fixing the stroke of the movable roller 21 with the material storage and feeding speed curves, the system does not need to recalculate the stroke and matching curves in each cycle, greatly simplifying the real-time calculation burden of the controller and improving the determinism and reliability of the system.

[0085] The control module directly controls the drive motor to run according to the pre-planned travel of the movable roller 21 and the material storage speed curve and the material discharge speed curve, and receives the monitoring information from the tension monitoring unit 3 in real time. Based on this, it calculates a compensation signal that reflects the slight deviation between the actual tension and the target value, and superimposes it onto the material storage speed curve or the material discharge speed curve.

[0086] Illustratively, a progressive logic of fixed-point positioning, curve drawing, and compensation is used to deeply integrate model prediction with real-time sensing. Fixed stroke and preset curves simplify control matching calculations, improve system stability and predictability, and ultimately ensure the ultimate stability of material tension under high-speed production, thereby guaranteeing high-quality output of bag products with accurate dimensions and smooth seals.

[0087] In one embodiment of this specification, the control module is connected to the feeding motor;

[0088] The control module also adjusts the speed of the feeding motor based on the monitoring information corresponding to the active roller group at the default position, so as to match the preset feeding speed.

[0089] Explanatoryly, this embodiment further optimizes the integrity and accuracy of the control system, extending the scope of closed-loop control from simply adjusting the moving roller 21 to dynamically fine-tuning the source speed of the active feeding unit 1, thereby eliminating interference errors that may occur during system operation.

[0090] Explanatoryly, the control module, based on its original functions, directly connects to and controls the feeding motor. When the moving rollers reach their initial position in each work cycle, the control module synchronously reads the monitoring information corresponding to the tension monitoring unit 3. The ideal state of the material remaining flat and tension-free at the initial position corresponds to an ideal tension value in the tension monitoring unit 3. Therefore, based on the monitoring information corresponding to the default position and the ideal tension value, it can be verified whether the feeding motor's speed matches the preset feeding speed. If there is a deviation between the monitoring information and the ideal tension value, it indicates a slight difference between the actual total length of material fed by the feeding motor and the theoretical requirement (i.e., the length of material pulled in a single pass). This difference is usually caused by unavoidable factors such as a slight drift between the actual speed of the feeding motor and the preset value, or slight slippage of the material on the roller system, and is a type of steady-state error that accumulates gradually.

[0091] To this end, the control module dynamically adjusts the feed motor speed setting based on monitoring information from the active roller assembly at the default position. The control algorithm (e.g., inputting the deviation value into a dedicated integral controller) calculates the required speed compensation and fine-tunes the feed motor speed command. If the detected tension is too high, the feed motor speed is increased appropriately; if the tension is too low, it is decreased appropriately, until the tension deviation at the default position is reduced to zero.

[0092] By fine-tuning the speed at the material discharge source in a closed loop, a strict macroscopic match between supply and consumption is ensured during long-term operation, thereby eliminating the problem of slow tension baseline drift that may be caused by the accumulation of small speed errors. This allows the reciprocating motion of the movable roller 21 to always operate on a stable tension reference, further guaranteeing the long-term and absolute stability of the material tension within the system and improving the equipment's adaptability to different batches of materials and long-term continuous operation. Furthermore, it avoids the need to adjust the pre-planned stroke of the movable roller 21 with the material storage and discharge speed curves, greatly simplifying the matching calculations of the control module.

[0093] In one embodiment of this specification, the control module obtains a correction signal based on the monitoring information corresponding to the default position of two adjacent active roller groups and outputs it to the feeding motor.

[0094] Explained, this embodiment introduces a smoother and smarter correction algorithm based on historical state comparisons. This approach aims to improve the stability of the correction process and avoid system oscillations caused by single data fluctuations or overly aggressive adjustments.

[0095] Illustratively, if corrections are made based solely on a single deviation, the system may overreact to brief, atypical disturbances (such as a single accidental slippage), causing the feed motor speed to be adjusted frequently and drastically, which in turn undermines system stability.

[0096] When the control module corrects the speed of the feeding motor, it comprehensively considers the monitoring information obtained from the tension monitoring unit 3 at the time the moving roller returns to the default position in two adjacent work cycles (i.e., the current cycle and the previous cycle). The control module compares the deviation of the tension state corresponding to these two consecutive time points from the rational tension, and obtains the correction signal through a specific algorithm (e.g., calculating the rate of change of the deviation or applying a control algorithm with filtering function). Based on the comparison of two adjacent pieces of information, the true and continuous deviation trend can be identified more reliably, and the correction signal more accurately reflects the true trend and accumulation rate of the system deviation, rather than an instantaneous value that may contain random noise.

[0097] For example, if tension is detected twice consecutively at the default point, deviating from the set value in the same direction from the rational tension, it strongly indicates that there is indeed a systematic deviation in the average speed of the feeding motor that needs calibration. In this case, the correction signal output by the control module will be more definitive, but the correction amount can be applied slowly and incrementally. Conversely, if the two signals differ significantly or are in opposite directions, it may indicate that the interference is random, and the correction algorithm will tend to be conservative. Overall, this ensures that the correction of the feeding motor speed setting benchmark is smoothly and gradually integrated into the system operation, effectively avoiding the risk of overshoot or oscillation caused by the correction action itself. This keeps the material tension locked at the preset ideal level for a long period, further improving the consistency of product quality and the reliability of equipment operation.

[0098] The embodiments described above are merely preferred embodiments of this specification and are not intended to limit the scope of this specification. Any modifications and improvements made by those skilled in the art to the technical solutions of this specification without departing from the spirit of this specification should fall within the protection scope defined by the claims of this specification.

Claims

1. A positive feed system for a bag making machine, the bag making machine including a draw motor providing a periodic draw drive force, characterized by: The system includes an active feeding unit, a temporary storage unit, and a tension monitoring unit; The active feeding unit pulls the material from outside the system at a preset feeding speed; The temporary storage unit includes a movable roller that surrounds the material entering the system, a drive component that drives the movable roller to move along a defined trajectory to change the length of the material path, and a control module. The tension monitoring unit monitors the tension of the materials inside the system in real time and outputs monitoring information. The control module outputs control signals to the drive component based on the rotational speed of the feeding motor, the preset feeding speed, and monitoring information, so as to keep the tension of the material inside the system stable.

2. The active feeding system for a bag-making machine according to claim 1, characterized in that: The tension monitoring unit includes two fixed rollers around which the material entering the system is surrounded, a floating roller disposed between the two fixed rollers and capable of floating up and down relative to the fixed rollers, and a sensor for monitoring the position change of the floating roller. The material entering the system surrounds the same side of the two fixed rollers and surrounds the other side of the floating roller.

3. The active feeding system for a bag-making machine according to claim 2, characterized in that: The core of the floating roller is provided with a connecting rod that is rotatably connected to any of the cores of the fixed roller, and the sensor is an encoder located at the rotatable connection point of the connecting rod.

4. The active feeding system for a bag-making machine according to claim 3, characterized in that: The tension monitoring unit is located on the side of the temporary storage unit away from the active discharge unit.

5. The active feeding system for a bag-making machine according to claim 2, characterized in that: The drive assembly includes two wheel sets located at both ends of the movable roller, a belt surrounding the wheel sets, and a drive motor that drives the wheel sets to rotate. The roller core of the movable roller is fixedly connected to the belts on both wheel sets; The control module outputs control signals to the drive motor based on the rotational speed of the feeding motor, the preset feeding speed, and monitoring information, so as to drive the movable roller to move with the belt; The control module outputs control signals to the drive motor based on the rotational speed of the feeding motor, the preset feeding speed, and monitoring information, so that the movable roller moves with the belt to maintain stable material tension inside the system.

6. The active feeding system for a bag-making machine according to claim 5, characterized in that: Both of the belts in the wheel sets are vertically arranged.

7. The active feeding system for a bag-making machine according to claim 6, characterized in that: The active feeding unit includes a feeding roller group that clamps the material and a feeding motor that drives the feeding roller group; the fixed roller near the temporary storage unit is a fixed roller group that includes two sub-fixed rollers with gaps and located on the upper and lower sides of the material entering the system; the movable roller is a movable roller group that includes two sub-movable rollers with gaps and located on the upper and lower sides of the material entering the system. The fixed roller group and the feeding roller group are symmetrically arranged on both sides of the belt of the two wheel groups and at the same height as the midpoint of the belt length.

8. The active feeding system for a bag-making machine according to claim 7, characterized in that: The control module uses the midpoint of the belt length as the default position of the movable roller group. Based on the horizontal distance between the movable roller group and the feeding roller group and the single feeding length, it obtains the highest and lowest positions of the movable roller group on the belt. Based on the preset feeding speed, it obtains the material storage speed curve from the default position to the highest and lowest positions. Based on the preset feeding speed and the rotation speed of the feeding motor, it obtains the feeding speed curve from the highest and lowest positions to the default position. Then, it obtains a compensation signal based on the monitoring information. The material storage speed curve, feeding speed curve and compensation signal are used as control signals and output to the drive motor.

9. The active feeding system for a bag-making machine according to claim 8, characterized in that: The control module is connected to the feeding motor; The control module also adjusts the rotation speed of the feeding motor based on the monitoring information corresponding to the active roller group at the default position, so as to match the preset feeding speed.

10. The active feeding system for a bag-making machine according to claim 9, characterized in that: The control module obtains correction signals based on the monitoring information corresponding to the default positions of two adjacent active roller groups and outputs them to the feeding motor.

Images