A paper stack, a paper stack packaging apparatus, and a packaging method thereof

Abstract

This application discloses a paper stack, a paper stack packaging device, and a packaging method thereof, relating to the field of paper processing technology, aiming to solve the problems of high energy consumption, low efficiency, and easy condensation generation in existing heat shrink film packaging. The paper stack packaging device includes: a bag-making mechanism configured to prepare a thin film bag from a cold-stretched film; a stretching mechanism located below the bag-making mechanism, configured to stretch the open end of the thin film bag to a first dimension, the first dimension being larger than the horizontal cross-sectional dimension of the paper stack pallet; and a conveying mechanism located below the stretching mechanism, configured to convey the paper stack. This application also provides a paper stack packaging method and a paper stack. By using a cold-stretched film to complete the paper stack packaging at room temperature, no heating is required, resulting in low energy consumption, high efficiency, and prevention of condensation generation inside the film, thus ensuring paper quality.

Description

Technical Field

[0001] This application relates to the field of paper processing technology, and in particular to a paper stack, a paper stack packaging device, and a packaging method thereof. Background Technology

[0002] In the field of cultural paper processing, finished paper is usually stacked on pallets to form paper stacks for easy storage and transportation. To prevent paper stacks from scattering, getting damp, or being damaged during handling, the entire stack needs to be wrapped with film.

[0003] Currently, the most common packaging method is heat shrink film packaging. This process involves first covering the top and sides of the paper stack with film, then sending the paper stack into a heat shrink oven, where the film is heated and shrunk at a high temperature of 180-220℃. Finally, the film is cooled and shaped to achieve complete wrapping of the paper stack. Summary of the Invention

[0004] To achieve the above objectives, this application provides the following technical solution: A paper stacking packaging device, comprising: A bag-making mechanism, configured to prepare a cold-stretched film into a film bag; The stretching mechanism located below the bag-making mechanism is configured to stretch the open end of the film bag to a first dimension, which is larger than the dimension of the horizontal cross-section of the pallet of the paper stack. The conveying mechanism located below the stretching mechanism is configured to convey paper stacks.

[0005] Compared with existing technologies, the paper stack packaging apparatus provided in this application uses a bag-making mechanism to form bags from cold-stretched film, resulting in film bags made from the cold-stretched film. A stretching mechanism stretches the open end of the film bag to a size larger than the horizontal cross-sectional dimension of the paper stack. A conveying mechanism then transports the paper stack below the stretching mechanism, allowing the stretched film bag to be inserted into the paper stack from top to bottom. After the stretching force is removed, the film bag adheres tightly to the surface of the paper stack due to the elastic recoil force of the cold-stretched film itself. The entire packaging process is carried out at room temperature without heating, thus fundamentally avoiding the condensation problem inside the film caused by high-temperature heating and rapid cooling in heat shrink film packaging. This effectively prevents the paper from becoming damp and warping, improves product quality, and offers high packaging efficiency.

[0006] Furthermore, the bag-making mechanism, stretching mechanism, and conveying mechanism of the packaging device of this application adopt a vertical layout, which occupies a small area, and the various mechanisms work together to achieve continuous automated production.

[0007] This application also provides a paper stack packaging method, which uses the above-mentioned paper stack packaging device for packaging, and the method includes: A film bag of the target length is prepared using a bag-making mechanism; The film bag is stretched to a first size using a stretching mechanism, the first size being larger than the horizontal cross-sectional dimension of the pallet of the paper stack. The stretched film bag is placed on the paper stack using a stretching mechanism to obtain a pre-wrapped paper stack. The top and sides of the pre-wrapped paper stack are covered with film bags. Remove the stretching mechanism to allow the film bag to adhere to the surface of the paper stack, with the open end of the film bag tucked under the tray at the bottom of the paper stack.

[0008] Compared with the prior art, the beneficial effects of the paper stacking packaging method provided in this application are the same as those of the paper stacking packaging device described above, and will not be repeated here.

[0009] This application also provides a paper stack, comprising: a pallet, a paper stack stacked on the pallet, and a cold-stretch film, the cold-stretch film being wrapped around the top and sides of the paper stack, and also wrapping around the sides and part of the lower surface of the pallet.

[0010] Compared with the prior art, the beneficial effects of the paper stack provided in this application are the same as those of the paper stack packaging device described above, and will not be elaborated here. Attached Figure Description

[0011] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This paper stack packaging device according to an embodiment of the present application is shown in a structural schematic diagram. Figure 2 A schematic diagram of a dual-membrane frame provided in an embodiment of this application is shown; Figure 3 A schematic diagram of a four-membrane frame provided in an embodiment of this application is shown; Figure 4 A schematic flowchart of a paper stack packaging method provided in an embodiment of this application is shown.

[0012] Figure label: Bag making mechanism 100; stretching mechanism 200; stretching assembly 210; conveying mechanism 300; film frame 400; support shaft 410; film roll 420. Detailed Implementation

[0013] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0014] The accompanying drawings illustrate various structural schematics according to embodiments of this application. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0015] Furthermore, 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0016] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0017] In the field of cultural paper processing technology, finished paper stacks such as copy paper and offset paper are prone to problems such as product displacement, scattering, damage, dirt, and moisture during handling, thus requiring whole-stack lamination packaging. Currently, heat shrink film is used for lamination packaging of finished paper stacks. This method first involves top film covering. After the paper stack is conveyed to the position, the top film covering machine automatically descends and pulls the film to cover the top of the paper stack. Next, curtain packaging and folding film packaging are performed. The curtain device selects the appropriate film roll according to the paper stack specifications. The paper stack carries the film through the curtain door. After the curtain door closes, the two sides of the film are pressed, welded, and cut. Then, the paper stack enters the film heating stage. The temperature inside the furnace is controlled at 180-220℃, and the film shrinks due to heat through hot air circulation. Finally, pressure shrinking is performed. After the paper stack is output, it is cooled under pressure to set the film shape. However, this solution has significant shortcomings in practical applications. On the one hand, the heating equipment has a rated power of up to 350KW, with a power consumption of approximately 5.66KWH per ton, resulting in extremely high energy consumption. On the other hand, the lamination process involves multiple steps, including laying the top film, welding the outer film, and heat shrink molding, making the process complex. Actual measurements show that a single stack takes up to 120 seconds, leading to low packaging efficiency. Furthermore, the heat-packing process is prone to quality defects such as poor heat shrinkage and holes in the packaging film. Additionally, the rapid cooling of the packaged product from the high-temperature environment causes condensation within the film, trapping humid air and resulting in water droplets on the product surface, negatively impacting customer experience.

[0018] To overcome the aforementioned problems, exemplary embodiments of this application provide a paper stack, a paper stack packaging apparatus, and a packaging method thereof. This solution employs cold-stretch film for paper stack packaging. First, a bag-making mechanism prepares a thin film bag from the cold-stretch film. Then, a stretching mechanism stretches the open end of the thin film bag to a size larger than the horizontal cross-sectional dimension of the paper stack. Next, the thin film bag is inserted into the paper stack from top to bottom. Finally, the stretching force is released, allowing the thin film bag to tightly adhere to the surface of the paper stack due to its own elastic recoil force, and the open end is tightened and fixed to the bottom of the pallet. The entire packaging process is carried out at room temperature, requiring no heating, thus completely avoiding the condensation problem caused by high-temperature heating and rapid cooling, ensuring paper quality. Simultaneously, it improves the packaging efficiency of the paper stack.

[0019] Figure 1 A schematic diagram of a paper stacking packaging device according to an embodiment of this application is shown. Figure 1 As shown, the paper stacking packaging device provided in this application embodiment includes: a bag making mechanism 100, a stretching mechanism 200 disposed below the bag making mechanism 100, and a conveying mechanism 300 disposed below the stretching mechanism 200.

[0020] The bag-making mechanism 100 described above is configured to prepare a thin-film bag from a cold-stretched sleeve film. It is understood that the cold-stretched sleeve film involved in this embodiment is a multi-layer co-extruded polyethylene film with high elasticity and high retraction force, and the stretched cold-stretched sleeve film has an unclosed shape with openings at both ends when stretched. The bag-making mechanism 100 processes the flat film material into a bag-shaped structure with one end closed and the other open through actions such as film feeding, heat sealing, and film opening.

[0021] The stretching mechanism 200 is located below the bag-making mechanism 100 and is configured to stretch the open end of the film bag to a first dimension, which is larger than the horizontal cross-sectional dimension of the pallet of the paper stack. It can be understood that this first dimension can be the perimeter or diagonal length of the film bag after the opening is stretched open, as long as it ensures that the film bag can be smoothly fitted into the paper stack. The stretching mechanism 200 can employ various structures to achieve the stretching function, such as: robotic arm-type stretching, cylinder-driven stretching, or screw-guide rail-type stretching, etc.

[0022] The aforementioned conveying mechanism 300 is located below the stretching mechanism 200 and is configured to convey paper stacks. The conveying mechanism 300 can be any of the following: roller conveyor, chain conveyor, belt conveyor, or roller conveyor, as long as it can smoothly feed the paper stacks into and out of the wrapping station. Through the coordinated operation of the above three mechanisms, this device can complete the cold stretch wrapping of paper stacks at room temperature without heating, has a compact structure, and a high degree of automation.

[0023] As can be seen, in the paper stack packaging device provided in this application, a bag-making mechanism is used to make bags from cold-stretched film, resulting in film bags prepared from the cold-stretched film. A stretching mechanism stretches the open end of the film bag to a size larger than the horizontal cross-sectional dimension of the paper stack. Then, a conveying mechanism transports the paper stack below the stretching mechanism, allowing the stretched film bags to be inserted into the paper stack from top to bottom. After the stretching force is removed, the film bags adhere tightly to the surface of the paper stack due to the elastic recoil force of the cold-stretched film itself. The entire packaging process is carried out at room temperature without heating, thus fundamentally avoiding the problem of condensation inside the film caused by high-temperature heating and rapid cooling in heat-shrink film packaging. This effectively prevents the paper from becoming damp and warping, improves product quality, and results in high packaging efficiency.

[0024] Furthermore, the bag-making mechanism, stretching mechanism, and conveying mechanism of the packaging device of this application adopt a vertical layout, which occupies a small area, and the various mechanisms work together to achieve continuous automated production.

[0025] As one possible implementation, such as Figure 1 As shown, the bag making mechanism 100 may include a film feeding unit (not shown in the figure), a heat sealing unit (not shown in the figure), and a film opening unit (not shown in the figure).

[0026] The aforementioned film feeding unit is configured to select a target cold-stretched film from at least one cold-stretched film and deliver the target cold-stretched film of a target length. Specifically, the film feeding unit may include a traction roller group corresponding to the film frame. When multiple film rolls exist, the film feeding unit can pull the film material from one of the film rolls according to a preset program or manual instruction. The control of the film feeding length can be achieved by a servo motor in conjunction with an encoder, by detecting markings on the film material using a photoelectric sensor, or by manual control.

[0027] The aforementioned heat-sealing unit is configured to cut a target length of cold-stretched film and seal one end of the target cold-stretched film. The heat-sealing unit may include a fixed static heat-sealing block and a cylinder-driven dynamic heat-sealing block. When the two are pressed together, heating seals the film material, while a cutter on the static heat-sealing block cuts the film material, forming an independent, one-end-closed film bag. It is understood that the heat-sealing temperature, pressure, and time can be adjusted according to the actual conditions such as the film thickness and material.

[0028] The aforementioned film-opening unit is configured to open the opening end of the target cold-stretched film. The film-opening unit can use methods such as negative pressure adsorption, mechanical expansion, or electrostatic adsorption to open the opening end of the target cold-stretched film. By setting the film-opening unit, the opening end of the already sealed film bag is fully expanded, so that the robotic arm of the subsequent stretching mechanism 200 can smoothly extend in.

[0029] As one possible implementation, such as Figure 1 As shown, the aforementioned film-opening unit may include at least two sets of negative pressure components (not shown in the figure), which are arranged opposite to each other on both sides of the target cold-stretched film. It is understood that the number of negative pressure components can also be three, four, or more. For example, four sets of negative pressure components can be used to adsorb the four sides of the film bag respectively, which can more evenly expand the opening into a rectangle, facilitating the subsequent insertion of the robotic arm.

[0030] In practical applications, the aforementioned film-opening unit includes two sets of negative pressure components, located on the front and rear sides or left and right sides of the film bag, respectively. Each set of negative pressure components may include a negative pressure air box and a negative pressure fan. During operation, the negative pressure fan starts, creating negative pressure inside the negative pressure air box. The adsorption holes or adsorption grooves on the surface of the air box adsorb the sidewalls of the film bag. Subsequently, the two sets of negative pressure components move away from each other, pulling the opening end of the film bag open into a flat or rectangular shape.

[0031] The aforementioned negative pressure components can be arranged symmetrically or asymmetrically. They can move horizontally, vertically, or have both degrees of freedom simultaneously.

[0032] The aforementioned negative pressure air box is a flat, box-shaped structure with multiple small holes or elongated slots on the side facing the film bag to evenly distribute the negative pressure suction. The negative pressure fan can be a centrifugal fan or a vortex fan, connected to the negative pressure air box via a pipe. The negative pressure fan can be installed on the back of the negative pressure air box or installed remotely and connected via a flexible hose.

[0033] As one possible implementation, such as Figure 1 As shown, the stretching mechanism 200 may include at least four stretching components 210, with the positions of the at least four stretching components 210 opposite each corner of the paper stack. It is understood that the number of stretching components 210 can be set according to the shape and size of the paper stack, and six, eight, or more stretching components 210 may be used. For example, for extra-large paper stacks, auxiliary stretching components 210 may be added at the midpoint of each side to provide a more uniform stretching force.

[0034] In practical applications, the four stretching components 210 can be arranged on the outer sides of the four corners of the paper stack. When the opening of the film bag is opened, the robotic arms of the four stretching components 210 extend into the film bag from the four corners. By moving outward synchronously, the opening of the film bag is evenly stretched into a rectangular shape similar to the horizontal cross-section of the paper stack. This arrangement ensures that the film bag is subjected to uniform force during stretching, avoiding localized overstretching that could lead to film breakage or uneven shrinkage.

[0035] As one possible implementation, such as Figure 1 As shown, each of the at least four stretching assemblies 210 includes a rubber roller and a robotic arm. The rubber roller is configured to wind up the film bag, and the robotic arm is configured to open the film bag and move it along the height direction of the paper stack.

[0036] Specifically, the aforementioned robotic arm can move horizontally to reach inside the film bag and open its opening. A rubber roller is mounted at the end of the robotic arm. Once the robotic arm is in place, the rubber roller rotates to roll up the edge of the film bag, thus tensioning the film. During the film-wrapping stage, the robotic arm, along with the rubber roller, moves downwards. The rubber roller reverses to release the film, allowing the opened film bag to be wrapped around the paper stack from top to bottom. Once the film bag completely covers the paper stack, the robotic arm moves out from the bottom along both sides of the conveyor mechanism and resets. The film bag adheres to the surface of the paper stack and the tray at the bottom of the stack due to its own retraction force. It is understood that the rubber roller can be driven by a separate servo motor or by a cylinder in conjunction with a ratchet mechanism. The surface of the rubber roller can be covered with rubber or silicone material to increase friction. The robotic arm can be mounted on a linear guide rail and driven by a servo motor or cylinder. Its movement direction can be horizontal (X and Y directions) and vertical (Z direction). The end of the robotic arm can be equipped with grippers or suction cups to assist in fixing the film.

[0037] As one possible implementation method, Figure 2 A schematic diagram of a dual-membrane frame provided in an embodiment of this application is shown. Figure 1 and Figure 2 As shown in the embodiment of this application, the paper stacking packaging device also includes a film holder 400, which is configured to accommodate cold-stretched sleeve film. The film holder 400 can be disposed above, to the side, or behind the bag-making mechanism 100 for holding the cold-stretched sleeve film roll. The film holder 400 may include a support shaft 410, a tension adjusting device (not shown in the figure), and a film roll detection sensor (not shown in the figure). The support shaft 410 is used to mount the film roll 420, and the tension adjusting device is used to control the film tension during unwinding to prevent the film from becoming loose or too tight. The film roll detection sensor is used to monitor the remaining amount of film roll and issues an alarm signal when the film roll 420 is about to run out.

[0038] Figure 3 A schematic diagram of a four-membrane frame provided in an embodiment of this application is shown. Figure 3 As shown, the membrane frame 400 can be a single membrane frame or a double membrane frame (see reference). Figure 2 ) or four-membrane frame (reference) Figure 3 Dual or quad membrane racks allow for membrane changes without stopping the machine, or provide multiple alternative membrane rolls of different specifications to improve production efficiency.

[0039] The aforementioned tension adjustment device can be a mechanical device such as a spring swing arm or a magnetic powder brake, or an electrical device with constant tension control by a servo motor. High-precision tension control is crucial for ensuring the consistency of film bag dimensions.

[0040] This application also provides a method for packaging paper stacks. Figure 4 A schematic flowchart of a paper stack packaging method provided in an embodiment of this application is shown. Figure 4 As shown, this method uses the aforementioned paper stacking packaging device for packaging. The method may include the following steps: Step 410: Prepare film bags of the target length using the bag-making mechanism. It is understood that the target length of the film bag can be automatically calculated based on the stack height or manually entered by the operator. For example, the stack height can be measured using a photoelectric sensor.

[0041] Specifically, the film feeding unit of the bag-making mechanism can be used to pull the cold-stretched film from the film rack and deliver the film material to a preset length; the heat-sealing unit seals and cuts the bottom of the film material to form a film bag with a closed bottom and an open top; the film opening unit opens the open end of the film bag to prepare for subsequent stretching. The target length of the film bag should be determined based on the height of the paper stack, usually slightly greater than the sum of the height of the paper stack and the height of the pallet, to ensure that the film bag can completely cover the top and sides of the paper stack and fold into the bottom of the pallet.

[0042] Step 420: Use a stretching mechanism to stretch the film bag to a first dimension, which is larger than the horizontal cross-sectional dimension of the pallet of the paper stack. It can be understood that the film bag can be stretched to its position in one go using the stretching mechanism, or it can be stretched gradually in multiple stages to avoid the film tearing due to excessive instantaneous tension. This first dimension can be a fixed value or dynamically adjusted according to the dimensions of the paper stack.

[0043] Specifically, multiple stretching components of the stretching mechanism, such as four robotic arms, extend into the inside of the opened film bag and expand the opening by moving radially outward. The first dimension can be the diagonal length or circumference of the film bag opening after it has been expanded, as long as it ensures that the expanded opening can be inserted into the stack of paper without obstruction.

[0044] Step 430: Use a stretching mechanism to put the stretched film bag onto the paper stack to obtain a pre-wrapped paper stack, the top and sides of which are covered with film bags.

[0045] Specifically, after the film bag is inflated, the stretching mechanism moves the film bag downwards, fitting it from top to bottom into the paper stack that has been positioned at the target location. During the fitting process, the closed end of the film bag first covers the top surface of the paper stack, and then the sidewalls cover the four sides of the paper stack. At this point, the film bag has not yet released its tensile force and is still in an inflated state.

[0046] Step 440: Remove the stretching mechanism to allow the film bag to adhere to the surface of the paper stack, with the open end of the film bag tucked under the tray at the bottom of the paper stack.

[0047] Specifically, the robotic arm of the stretching assembly can be released and reset, releasing the stretching force. The film bag, relying on its own high elasticity and retraction force, quickly shrinks and fits tightly against the top and sides of the paper stack. The open end of the film bag naturally closes at the bottom of the pallet, completing the packaging of the paper stack.

[0048] As can be seen, the method provided in this application embodiment allows the entire packaging process to be completed at room temperature without heating, thus avoiding the generation of condensate, while improving packaging efficiency and reducing packaging costs.

[0049] As one possible implementation, the above-mentioned preparation of film bags of the target length using a bag-making mechanism can further include: firstly, selecting a target cold-stretch sleeve film based on the dimensions of the paper stack, the target cold-stretch sleeve film having dimensions matching those of the paper stack; then, using the bag-making mechanism to fabricate a film bag of the target length from the target cold-stretch sleeve film, the film bag having an open end. It is understood that the selection of the target cold-stretch sleeve film can be achieved by automatically matching the film roll by reading the specification barcode or RFID tag of the paper stack; alternatively, the operator can select the paper stack model on a touchscreen, and the system will automatically call up the corresponding film roll; or the corresponding film roll can be manually pushed to the working position, or the film holder can be manually switched.

[0050] In one example, the film feeding unit of the bag-making mechanism described above can be connected to multiple film racks, each holding cold-stretched film rolls of different specifications. The system can automatically determine and select the most suitable film roll based on pre-inputted paper stack length, width, and height, or by online measurement of the paper stack dimensions. For example, when the paper stack is long, a film roll with a larger width is selected; when the paper stack is wide, a film roll with a larger insert edge is selected. It should be noted that the matching principle here is that the selected film bag can completely cover the paper stack after stretching, with minimal material waste.

[0051] Then, the selected target cold-stretch film is pulled to the target length by the film feeding unit. This target length can be understood as the height of the paper stack plus the pallet height, plus a certain margin. One end of this film section is sealed and cut by the heat-sealing unit, forming a film bag with one closed end and one open end. The opening end of the film bag is then opened using the film opening unit, preparing it for subsequent stretching.

[0052] As one possible implementation, the aforementioned first dimension can be achieved by stretching the film bag to 1.05 to 1.1 times its original size using a stretching mechanism. It should be noted that the original size here refers to the opening circumference or diagonal length of the film bag in its unstretched state. This stretching ratio is an optimized value determined based on the material properties of the cold-stretch film. When the stretching ratio is less than 1.05 times, the opening size may be insufficient for the paper stack to be smoothly fitted; when the stretching ratio is greater than 1.1 times, the film may be overstretched, leading to thinning, reduced strength, or even breakage. Simultaneously, excessive retraction force may cause indentations on the edges of the paper stack. Therefore, a stretching ratio of 1.05-1.1 times achieves the best balance between ensuring smooth film fitting and tight wrapping. This stretching ratio can be 1.05 times, 1.07 times, or 1.1 times the original size, etc. The specific stretching ratio can be determined based on the brand or batch of the cold-stretch film and the size of the paper stack, and is not limited here.

[0053] As one possible implementation, the thickness of the aforementioned cold-stretched sleeve is 100µm-120µm. For example, the thickness of the cold-stretched sleeve can be 100µm, 110µm, or 120µm, and is not limited to these. This thickness range is determined after comprehensively considering the mechanical strength, shrinkage force, puncture resistance, and cost of the film. When the thickness is less than 100µm, the film is prone to breakage during stretching, and the shrinkage force is insufficient to firmly fix the paper stack. When the thickness is greater than 120µm, the elasticity of the film decreases, stretching requires greater force, and material costs increase significantly.

[0054] As one possible implementation, the width of the film bag is positively correlated with the length of the paper stack; that is, the longer the paper stack, the wider the selected film bag. Similarly, the insert size of the film bag is positively correlated with the width of the paper stack; that is, the wider the paper stack, the larger the insert size. It should be noted that this positive correlation can be linear, piecewise linear, or nonlinear. This application does not limit the specific mathematical relationship, as long as the general trend is that the larger the paper stack, the larger the film bag.

[0055] As shown above, the width of the film bag determines its ability to wrap the paper stack along its length. The folded edges, i.e., the inward folds on both sides of the film, determine the film bag's ability to wrap the paper stack along its width and form a bottom three-dimensional space. By establishing a positive correlation between the paper stack size and the film specifications, it is possible to quickly and accurately package paper stacks of various sizes, avoiding waste or incomplete wrapping caused by using films that are too large or too small.

[0056] In one example, the specific correspondence between the dimensions of the paper stacks and film bags can be determined based on a pre-stored correspondence table, as detailed in Table 1.

[0057] Table 1. Correspondence between film specifications and pallet dimensions of paper stacks

[0058] As shown in the table above, the width and edge dimensions of the film are positively correlated with the length (x) and width (y) of the pallet of the paper stack: when the length and width of the pallet of the paper stack are large, a film with a larger width and a larger edge is selected; when the size of the pallet of the paper stack is small, a film with a smaller width and a smaller edge is selected. Through this matching relationship, precise packaging of paper stacks of different specifications can be achieved.

[0059] In practical applications, based on the dimensions of the paper stack and the type of film used, this application provides corresponding formulation designs to ensure that the packaged finished product meets quality requirements. Specific system settings are shown in Tables 2-5 below: Table 2 System settings for sizes 1070×825mm, 1140×870mm, and 1150×940mm

[0060] Table 3 System settings for sizes 960×760mm, 1180×960mm, and 1105×800mm

[0061] Table 4 System settings for sizes 1210×905mm, 1210×865mm, and 910×650mm

[0062] Table 5 System settings for 1245×895mm specification

[0063] Through the above parameter formulation design, the embodiments of this application can accurately control each step of cold stretch film packaging for cultural paper stacks of different specifications, ensuring that the packaged finished product meets quality requirements.

[0064] As one possible implementation, the stretching mechanism may also include a robot and a rubber roller. The method provided in this application embodiment may also include: determining the stretching distance of the robot in a first direction and the stretching distance of the robot in a second direction based on the size of the paper stack.

[0065] Specifically, the stretching mechanism in this application may include four robotic arms, each corresponding to one of the four corners of the paper stack. Each robotic arm can move independently along a first direction, i.e., the length direction of the paper stack, and a second direction, i.e., the width direction of the paper stack. The stretching distance between the robotic arms may refer to the distance between two opposing robotic arms.

[0066] The stretching distance between the two robotic arms in the X direction can be determined based on the length of the paper stack; the stretching distance in the Y direction can be determined based on the width of the paper stack. The stretching distance is typically set slightly larger than the corresponding dimension of the paper stack to ensure a uniform fit after the film bag is inserted. For example, the stretching distance in the X direction can be set to the length of the paper stack plus a 10-20mm allowance, and the same applies to the Y direction.

[0067] As can be seen, through the above method, the embodiments of this application can precisely control the stretching distance of the robot for paper stacks of different sizes, so that the stretching shape of the film bag matches the horizontal cross-sectional shape of the paper stack, ensuring both smooth film application and tight adhesion.

[0068] This application also provides a paper stack, including: a pallet, a paper stack stacked on the pallet, and a cold-stretch film, the cold-stretch film wrapping the top and sides of the paper stack, and wrapping the sides and part of the lower surface of the pallet.

[0069] As can be seen, the paper stacks provided in this embodiment are packaged at room temperature using cold-stretch film. Therefore, no condensation occurs between the cold-stretch film and the surface of the paper stack, and the paper remains dry and flat. This avoids problems such as paper warping and mold caused by condensation due to heating and cooling in traditional heat-shrink film packaging. At the same time, the cold-stretch film has a uniform thickness, without defects such as poor heat shrinkage or holes, and has a flat and beautiful appearance.

[0070] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0071] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. The scope of this application is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this application, and all such substitutions and modifications should fall within the scope of this application.

Claims

1. A paper stack packaging apparatus characterized by comprising: include: A bag-making mechanism configured to prepare a cold-stretched film into a film bag; A stretching mechanism located below the bag-making mechanism is configured to stretch the open end of the film bag to a first dimension, the first dimension being larger than the dimension of the horizontal cross-section of the pallet of the paper stack; A conveying mechanism located below the stretching mechanism is configured to convey the paper stack.

2. The apparatus of claim 1, wherein, The bag-making mechanism includes a film feeding unit, a heat sealing unit, and a film opening unit. The film feeding unit is configured to select a target cold stretch film from at least one cold stretch film and deliver a target cold stretch film of a target length. The heat sealing unit is configured to cut the target cold stretch film of the target length and seal one end of the target cold stretch film. The film opening unit is configured to open the open end of the target cold stretch film.

3. The apparatus of claim 2, wherein, The film-opening unit includes at least two sets of negative pressure components, which are arranged opposite to each other on both sides of the target cold-stretched film.

4. The apparatus of claim 3, wherein, Each of the at least two sets of negative pressure components includes a negative pressure box and a negative pressure fan.

5. The apparatus of claim 1, wherein, The stretching mechanism includes at least four stretching components, the positions of which are opposite each corner of the paper stack.

6. The apparatus of claim 5, wherein, Each of the at least four stretching components includes a rubber roller and a robotic arm, the rubber roller being configured to wind up the film bag and the robotic arm being configured to open the film bag and move the film bag along the height direction of the stack.

7. The apparatus of claim 1, wherein, The device also includes a membrane frame configured to accommodate the cold-stretched membrane.

8. A method of packaging a paper stack, characterized by Packaging is performed using the paper stacking packaging apparatus according to any one of claims 1-7, the method comprising: A film bag of the target length is prepared using a bag-making mechanism; The film bag is stretched to a first size using a stretching mechanism, the first size being larger than the horizontal cross-sectional dimension of the pallet of the paper stack. The stretched film bag is placed over the paper stack using a stretching mechanism to obtain a pre-wrapped paper stack, the top and sides of which are covered with the film bag. Remove the stretching mechanism to allow the film bag to adhere to the surface of the paper stack, with the open end of the film bag retracted below the tray at the bottom of the paper stack.

9. The paper stack wrapping method according to claim 8, characterized in that, The process of preparing a film bag of a target length using a bag-making mechanism includes: Based on the dimensions of the paper stack, a target cold-stretch sleeve is selected using a bag-making mechanism, wherein the dimensions of the target cold-stretch sleeve match the dimensions of the paper stack. The target cold-stretched film is made into a film bag of a target length using a bag-making mechanism, the film bag having an open end.

10. The paper stack wrapping method according to claim 8, characterized in that, The first size is 1.05 to 1.1 times the original size of the film bag; and / or, The film bag includes a cold-stretched sleeve with a thickness of 100µm-120µm; and / or, The width of the film bag is positively correlated with the length of the paper stack, and the insert size of the film bag is positively correlated with the width of the paper stack.

11. The paper stack wrapping method according to claim 8, characterized in that, The stretching mechanism includes a robotic arm and a rubber roller, and the method further includes: Based on the dimensions of the paper stack, the stretching distance of the robot in the first direction and the stretching distance of the robot in the second direction are determined.

12. A paper stack, characterized in that include: A tray, a stack of paper stacked on the tray, and a cold-stretch shrink film wrapped around a top surface and side surfaces of the stack of paper and wrapped around side surfaces and a part of a lower surface of the tray.

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