Air filter paper and folding forming process thereof

Abstract

The invention discloses air filter paper and a folding forming process thereof, and the folding forming process comprises the following steps: providing a sheet-shaped filter paper base material, dividing the filter paper base material into a middle folding region and edge constraint regions on two sides of the middle folding region, respectively forming a pre-folding guide structure in the middle folding region and a guide transfer structure in the edge constraint regions, and carrying out limiting introduction on the edge constraint regions, the initial folded body is formed by sequentially connecting a plurality of pleat sets, the initial folded body is conveyed to a shaping station to form a three-dimensional folded body, the three-dimensional folded body is locally fixed in a pleat set connecting area, then contour closing treatment is conducted, and the filter paper is obtained; the pre-folding guide structure enables folding operation to have direction guide, the guide transfer structure provides necessary positioning support for the filter paper during folding, tight combination of folding layers is ensured, the filter paper keeps accurate folding angles and relative positions in the folding process, and therefore the problems of folding direction deviation and interlayer looseness are effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of air filter material manufacturing, and more specifically, to an air filter paper and its folding process. Background Technology

[0002] With the continuous development of air purification technology, air filter paper plays a crucial role in various air purification equipment. The performance of air filter paper directly determines the filtration effect and service life of the equipment. Especially in high-efficiency air filters, the folding structure of the filter paper not only affects filtration accuracy but is also closely related to airflow, pressure loss, and maintenance cycle. Therefore, how to improve filter paper performance through reasonable folding processes has become an important research direction in filter paper production technology. In recent years, with the widespread expansion of filter paper applications, the industry's requirements for filter paper folding structures have become increasingly refined, especially in terms of folding accuracy, stability, and production efficiency.

[0003] Currently, air filter paper is mostly folded using mechanized methods, relying on fixed folding molds or mechanical folding techniques to form the filter paper. However, in practical applications, uneven folding and instability between layers are common problems. When processing multiple folded layers of filter paper, it is often difficult to effectively control the rotation during the folding process, which can easily lead to deviations in the folding direction and loose connections between folded layers, adversely affecting the stability and filtration efficiency of the filter paper.

[0004] Therefore, there is a need to provide an air filter paper and its folding process to solve the problems that existing air filter paper folding processes easily cause deviations in folding direction and looseness between folded layers. Summary of the Invention

[0005] The main objective of this invention is to provide an air filter paper and its folding process, which aims to solve the technical problems mentioned in the background section.

[0006] The present invention adopts the following technical solution: A folding and forming process for air filter paper includes: S1. Provide a sheet-like filter paper substrate, and divide the filter paper substrate into a central folding area and edge constraint areas on both sides, forming a pre-folding guide structure in the central folding area and a guide transmission structure in the edge constraint areas respectively; S2. Limit the edge constraint area and, based on the relative rotation relationship between the two edge constraint areas, continuously and alternately fold the middle fold area to form an initial fold body, wherein the initial fold body is composed of multiple fold groups connected in sequence. S3. The initial folded body is transported to the shaping station, the edge constraint area is fitted with end constraints, and the body is folded and shaped along the length under the end constraints to form a three-dimensional folded body. S4. The three-dimensional folded body is locally fixed in the fold connection area, and then the outline is closed to obtain filter paper.

[0007] Further, in step S1, the filter paper substrate is conveyed along the length direction, and the middle folded area of ​​the filter paper substrate is continuously or intermittently pressed along the width direction to form a pre-folded guide structure. Each pre-folded guide structure is arranged sequentially along the first preset interval. During the formation of the pre-folded guide structure, the edge constraint area remains continuously unfolded and is transported synchronously, so that a continuous transition is formed between the pre-folded guide structure and the guide transmission structure.

[0008] Furthermore, before implementing the limit import step for the edge constraint region, the following steps are included: The filter paper substrate that forms the pre-folding guide structure and the guide transmission structure is prepared to be introduced into the folding station. The folding station includes a first limiting channel and a second limiting channel. The relative rotation relationship includes at least one of the height difference, stroke difference or phase difference between the first limiting channel and the second limiting channel. Step S2 includes: The edge constraint area on one side of the filter paper substrate is introduced into the first limiting channel, while the edge constraint area on the other side is introduced into the second limiting channel. During the introduction process, the first limiting channel and the second limiting channel are controlled to form a relative rotation relationship. During the differential introduction process, the middle folding area is folded sequentially along each pre-folding guide structure to form the initial folded body.

[0009] Furthermore, step S3, the step of performing end constraint mating on the edge constraint region, includes: The edge constraint area on one side of the initial folded body is positioned and engaged with the first end connector, while the edge constraint area on the other side is positioned and engaged with the second end connector. After the engagement is completed, the initial folded body is kept in a state of being restricted at both ends.

[0010] Further, step S3, the step of gathering and shaping along the length direction under end constraint, includes: With both ends restricted, a relative displacement along the length direction is applied to the initial fold body, causing each fold group to gradually close along the length direction; During the process of gathering each pleat group, the pleat cavities formed between adjacent pleat groups are sequentially inserted for correction. The insertion correction is carried out one by one according to the arrangement of the pleat groups. After all the pleat cavities are corrected, the three-dimensional folded body is output.

[0011] Furthermore, in step S4, the step of locally holding the three-dimensional folded body in the fold connection area includes: Pressing or hot pressing is applied sequentially to the fold root region of each fold group of the three-dimensional folded body, and a fixing action is applied simultaneously in the transition region between the fold root region and the edge constraint region. The local fixing is continuously advanced along the length direction of the three-dimensional folded body.

[0012] Further, step S4, the contour closure process, includes: After partially holding all the folds of the three-dimensional folded body in place, the outline is closed. When the contour closure process uses a rolling method, the starting end of one side of the three-dimensional folded body is rolled towards the ending end on the other side along its extension direction. During the rolling process, the edge constraint area of ​​the starting end is gradually inserted into the corresponding receiving area of ​​the ending end, and the closure connection is completed along the length direction. When the contour closure process adopts the merging method, multiple three-dimensional folded bodies are arranged side by side at a second preset interval and combined along the side direction of the three-dimensional folded bodies to form an overall structure.

[0013] Furthermore, after the contour closure process adopts a rolling method, a connection relationship is formed between the edge constraint area at the starting end of one side of the three-dimensional folded body and the corresponding receiving area at the ending end of the other side, which simultaneously exists in surface contact and edge embedding. The connection relationship extends continuously along the length direction of the three-dimensional folded body.

[0014] An air filter paper is made using the folding and forming process of filter paper as described in any of the preceding claims.

[0015] Beneficial effects: In this invention, by setting pre-folding guide structures and guide transfer structures on the central folding area and the edge constraint areas on both sides of the filter paper substrate, the directionality and precision of the filter paper during the folding process are effectively controlled. The pre-folding guide structure provides directional guidance for the folding operation, while the guide transfer structure formed in the edge constraint area provides necessary positioning support for the filter paper during folding, ensuring a tight bond between each folded layer. This allows the filter paper to maintain precise folding angles and relative positions during folding, thereby effectively reducing folding direction deviations and interlayer loosening. Furthermore, by implementing limit-introduction and relative rotation control, precise constraint of the edge constraint area and alternating folding of the central folding area are ensured, achieving uniform mechanical transfer between multiple folded layers. This ensures that the shape and size of each folded part are consistent, thus avoiding uneven folding or structural instability. After end constraint and length-direction shaping, the filter paper obtains a more stable and robust three-dimensional structure, further improving its filtration performance and service life. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of an air filter paper and its folding process according to the present invention; The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0017] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. 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 indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly 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, 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 invention according to the specific circumstances.

[0020] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0021] Reference Figure 1 This invention proposes an air filter paper and its folding process, comprising: S1. Provide a sheet-like filter paper substrate, and divide the filter paper substrate into a central folding area and edge constraint areas on both sides, forming a pre-folding guide structure in the central folding area and a guide transmission structure in the edge constraint areas respectively; In step S1, a sheet-like filter paper substrate suitable for air filtration is selected, and different functional areas are divided on the filter paper substrate according to certain standards. The filter paper substrate can be glass fiber filter paper, synthetic fiber filter paper, or composite material filter paper, with a thickness controlled at 0.1-0.5 mm and an air permeability of 50-300 L / m³. 2 *s, to ensure good filtration performance and folding adaptability. Specifically, the filter paper substrate is divided into a central folding area and two edge constraint areas on both sides. In this process, the central folding area is the core area for forming the main filter pleats during folding, while the edge constraint areas on both sides serve as connection areas for clamping, shaping, and end coupling. During the division, the longitudinal and transverse directions are determined according to filtration requirements and the physical properties of the filter paper, thereby ensuring precise positioning and stability during the folding process. To achieve precise folding of the filter paper, a low-stress introduction mechanism is used to perform tension equalization treatment on the filter paper substrate before it enters the folding station, which can prevent deformation or damage to the filter paper substrate caused by uneven tension during the folding process.

[0022] To further ensure the folding accuracy of the filter paper, pre-folding guide lines are formed in the central folding zone using shallow indentation prefabricated components, spaced laterally. These guide lines provide a folding direction, guiding the folding operation and ensuring the filter paper deforms along a predetermined direction during folding. Furthermore, continuous guide strips are formed near the edge constraint areas on both sides. These strips, working closely with the edge constraint areas during folding, provide positioning and control, ensuring the filter paper does not shift during folding. After this step, the filter paper substrate possesses a folding direction, a clearly defined stress structure, and pre-formed filter paper blanks with edge functional areas, effectively guiding subsequent multi-segment folding operations and providing a stable foundation for the following folding processes.

[0023] S2. Limit the edge constraint area and, based on the relative rotation relationship between the two edge constraint areas, continuously and alternately fold the middle fold area to form an initial fold body, wherein the initial fold body is composed of multiple fold groups connected in sequence. In step S2, the folding and forming of the filter paper substrate is achieved through the limiting and relative rotation relationship of the edge constraint areas. The pre-formed filter paper blank is fed into the folding and forming mechanism, and the first edge constraint area of ​​the filter paper enters the limiting channel, while the second edge constraint area enters another limiting channel. Between these two channels, by setting a height difference and a phase difference, the central folding area of ​​the filter paper is forced to alternately fold around a preset guide line. This folding pattern, through different displacements between adjacent fold lines, causes the filter paper to produce a wavy shape with mountain-shaped and valley-shaped folds.

[0024] In this step, folding is achieved through controlled displacement of the edge constraint zones on both sides. The movement of the edge constraint zones causes the central folding zone to fold. Therefore, the entire folding process does not rely solely on the general compression of the filter paper, but rather on the differential transmission between the edge constraint zones. Through this differential action, the central folding zone of the filter paper can naturally flip, thereby forming multiple connected initial fold groups. Each fold group consists of interconnected fold walls and turning line segments, and the spacing between adjacent fold groups is determined by the stepping amount of the edge strip, ensuring the consistency of the fold spacing.

[0025] Through this alternating folding method, the filter paper substrate transforms from a planar state into an initial folded body with a corrugated shape. This preserves the controllable connection between the two side strips, facilitating simultaneous constraint of the fold apex and fold trough, as well as three-dimensional height control. This ensures that each fold group is precisely formed, and the spacing between each fold group remains consistent. By precisely controlling the force transmission during the folding process, the folded shape is stably formed, guaranteeing the function and structure of the filter paper.

[0026] S3. The initial folded body is transported to the shaping station, the edge constraint area is fitted with end constraints, and the body is folded and shaped along the length under the end constraints to form a three-dimensional folded body. In step S3, after the initial folded body enters the shaping station, the filter paper is further shaped by the end constraints of the edge constraint area. The key to this process is to use end connectors to constrain both ends of the filter paper, ensuring that the shape and size of the folded body remain consistent. Specifically, the two edge constraint areas of the filter paper are respectively attached to the end connectors, and an axial constraint force is applied between these two end connectors. Through this axial constraint, each fold group of the filter paper gradually converges in the length direction, thus unifying the fold structure formed solely by folding. During the folding process, the top of each mountain-shaped fold is connected to the adjacent valley-shaped fold through its oblique fold wall. The constraint effect of the end constraint area allows these folds to automatically align under the overall constraint, thereby calibrating the height of the fold top and the depth of the fold valley. In addition, the shaping tongue in the shaping station can be inserted into the fold cavity between adjacent folds and fine-tune the opening width of the fold cavity.

[0027] Through this series of constraints and adjustments, the pleats of the filter paper are further solidified, and the pleat height and pleat cavity shape are precisely controlled, transforming the initial folded body into a three-dimensional folded body with good geometric shape and structural strength. By utilizing end constraints and local shaping, not only is the stability of the folded body improved, but the consistency and efficiency of the filter paper in subsequent processing are also ensured. Through the above shaping and adjustment, the filter paper can maintain good filtration effect and stability in actual use.

[0028] S4. The three-dimensional folded body is locally fixed in the fold connection area, and then the outline is closed to obtain filter paper.

[0029] In step S4, the initially folded and shaped filter paper undergoes further stabilization to ensure its pleated structure remains stable over a long period. The three-dimensional folded body formed in step S3 possesses a basic geometric shape and a certain degree of stability. To further prevent the pleated structure from springing back or deforming during use, precise local fixation is required. This process targets the transition areas between the fold roots and edge constraint zones. In these areas, the filter paper's pleated structure may become unstable or spring back due to stress accumulated during folding. Therefore, by implementing localized pressing and curing treatment in these areas, changes in the filter paper's shape during subsequent operations can be effectively prevented.

[0030] Local fixation relies on selecting appropriate locking bands. These bands extend continuously along the length of the folded body and form a close mechanical connection with the edge constraint areas on both sides. The formation of the locking bands not only prevents wrinkle springback but also ensures the stability of the filter paper structure. When the folded body detaches from the mold, the springback force is interrupted by the locking bands, thus preventing the springback force from spreading throughout the entire fold group. Even under external forces, the filter paper maintains its original stability, preventing wrinkle collapse and unevenness.

[0031] Furthermore, to prevent the filter paper pores from being excessively compressed, the locking and holding area is limited to outside the main filtration channels of the filter paper. This ensures that the filtration effect of the filter paper is not affected, effectively enhancing its mechanical strength while maintaining its porosity and flowability, and preventing loss of filtration efficiency due to excessive compression. After this stage of treatment, the filter paper folds form a structure with stable pleat memory, maintaining its shape throughout use and enhancing its stability during transportation, assembly, and use. After localized holding and stabilization treatment, the pleated structure of the filter paper is not only more stable, but its overall shape is also further optimized, improving its overall filtration performance and service life.

[0032] In one embodiment, in step S1, the filter paper substrate is conveyed along the length direction, and the middle folded area of ​​the filter paper substrate is continuously or intermittently pressed along the width direction to form a pre-folded guide structure, and each pre-folded guide structure is arranged sequentially along a first preset interval. During the formation of the pre-folded guide structure, the edge constraint area remains continuously unfolded and is transported synchronously, so that a continuous transition is formed between the pre-folded guide structure and the guide transmission structure.

[0033] In the above embodiments, the conveying of the filter paper substrate along its length plays a crucial role in forming the pre-folding guide structure. During this process, the filter paper substrate is fed into the workstation, where the central folding area undergoes continuous or intermittent pressing operations to form the pre-folding guide structure. The arrangement of the pre-folding guide structure follows a clear rule, sequentially arranged along the width of the filter paper at a first preset interval, ensuring a consistent distance between each guide structure. This guarantees the accuracy and consistency of the folding, ensuring that each folding area folds along a predetermined trajectory. Simultaneously, the formation of the pre-folding guide structure is achieved through the continuous unfolding and synchronous conveying of the edge constraint area. That is, the edge constraint area remains stable during this process, preventing excessive deformation. During folding, a smooth transition is formed between the pre-folding guide structure and the guide transmission structure. This continuous transition ensures smoother subsequent folding operations, avoiding folding errors and unevenness.

[0034] In one example, before the step of implementing limit import for the edge constraint region, the following steps are included: The filter paper substrate that forms the pre-folding guide structure and the guide transmission structure is prepared to be introduced into the folding station. The folding station includes a first limiting channel and a second limiting channel. The relative rotation relationship includes at least one of the height difference, stroke difference or phase difference between the first limiting channel and the second limiting channel. Step S2 includes: The edge constraint area on one side of the filter paper substrate is introduced into the first limiting channel, while the edge constraint area on the other side is introduced into the second limiting channel. During the introduction process, the first limiting channel and the second limiting channel are controlled to form a relative rotation relationship. During the differential introduction process, the middle folding area is folded sequentially along each pre-folding guide structure to form the initial folded body.

[0035] In the above embodiment, the preparatory work before step S2 involves the introduction of the filter paper substrate and the setting of the folding station to ensure that the filter paper substrate can enter the folding station in a predetermined manner, and that the edge constraint area can enter the first limiting channel and the second limiting channel.

[0036] Before entering the folding station, the filter paper substrate is introduced through the folding station. During this process, the first and second limiting channels in the folding station position the edges of the filter paper. These channels provide constraint on the filter paper substrate, ensuring its positioning as it enters the next folding step. Furthermore, the relative rotational relationship between the first and second limiting channels—at least one of height difference, stroke difference, or phase difference—provides necessary differential guidance for the folding process, allowing the filter paper substrate to fold synchronously under the control of the two edge constraint areas. Specifically, the aforementioned differential force transmission enables the central folding area of ​​the filter paper to fold sequentially, forming the initial fold. Unlike traditional platen pressing methods, this method of driving folding through relative rotational relationships is not only more precise but also avoids unnecessary indentations and deformation, ensuring the accurate shape of the folded area and effectively improving the folding quality and stability of the filter paper.

[0037] In one example, step S3, the step of performing end constraint mating on the edge constraint region, includes: The edge constraint area on one side of the initial folded body is positioned and engaged with the first end connector, while the edge constraint area on the other side is positioned and engaged with the second end connector. After the engagement is completed, the initial folded body is kept in a state of being restricted at both ends.

[0038] In the above embodiments, the end-constraint mechanism ensures that both ends of the filter paper fold remain fixed during subsequent shaping, preventing any loosening or misalignment. Each edge constraint area of ​​the initial fold is positioned and engaged with the first and second end connectors, respectively. This ensures the fixed position of both ends of the filter paper, thus guaranteeing the stability of the filter paper fold. The end-constraint positioning prevents the filter paper from becoming distorted or uneven in shape due to loosening at the ends during subsequent shaping. Furthermore, the end constraints not only improve the geometric stability of the fold but also provide necessary rigid support for the gathering and shaping process, ensuring that the overall fold structure of the filter paper does not deform or loosen during subsequent processing.

[0039] In one example, step S3, the step of gathering and shaping along the length direction under end constraint, includes: With both ends restricted, a relative displacement along the length direction is applied to the initial fold body, causing each fold group to gradually close along the length direction; During the process of gathering each pleat group, the pleat cavities formed between adjacent pleat groups are sequentially inserted for correction. The insertion correction is carried out one by one according to the arrangement of the pleat groups. After all the pleat cavities are corrected, the three-dimensional folded body is output.

[0040] In the above embodiments, the process of gathering and shaping the initial folded body under end constraint is further described. With both ends constrained, by applying relative displacement along the length direction, each fold of the filter paper begins to gradually gather, ensuring that the shape of each fold remains consistent during the folding process, preventing loosening or imbalance of the folds due to uneven force or positioning deviations. Specifically, during the gathering of the folds, the cavities formed between adjacent folds undergo insertion-type correction to ensure the uniformity of the opening width and shape of the cavities. The key to insertion-type correction is to perform it sequentially according to the fold arrangement, ensuring that each cavity is precisely adjusted to avoid problems such as narrow or inconsistent cavities. After this series of correction operations, the final three-dimensional folded body has a uniform fold height and regular cavities, ensuring the stability and filtration efficiency of the filter paper in use. This not only improves the quality of the filter paper but also lays the foundation for local fixation and contour closure processing, ensuring the final forming quality and stability of the filter paper.

[0041] In one example, step S4, which involves locally holding the three-dimensional folded body in the fold connection area, includes: Pressing or hot pressing is applied sequentially to the fold root region of each fold group of the three-dimensional folded body, and a fixing action is applied simultaneously in the transition region between the fold root region and the edge constraint region. The local fixing is continuously advanced along the length direction of the three-dimensional folded body.

[0042] In the above embodiments, the local fixation treatment is provided to ensure the stability of the three-dimensional folded body in the fold connection area. Local fixation further enhances the morphological stability of the filter paper after folding by applying pressure or heat to the fold root area. The fold root area is the part of the filter paper subjected to greater stress during folding, therefore, local fixation is necessary to ensure that it will not loosen or unravel during subsequent use. In this process, not only is the fold root area subjected to pressure or heat, but the transition area between the fold root and the edge constraint area is also simultaneously fixed, which can effectively prevent morphological changes or fold rebound due to excessive stress in subsequent operations. Local fixation is continuously applied along the length of the three-dimensional folded body to ensure the stability of the entire folded body.

[0043] In one embodiment, step S4, the step of performing contour closure processing, includes: After partially holding all the folds of the three-dimensional folded body in place, the outline is closed. When the contour closure process uses a rolling method, the starting end of one side of the three-dimensional folded body is rolled towards the ending end on the other side along its extension direction. During the rolling process, the edge constraint area of ​​the starting end is gradually inserted into the corresponding receiving area of ​​the ending end, and the closure connection is completed along the length direction. When the contour closure process adopts the merging method, multiple three-dimensional folded bodies are arranged side by side at a second preset interval and combined along the side direction of the three-dimensional folded bodies to form an overall structure.

[0044] In the above embodiments, contour closure processing is the final shape adjustment of the three-dimensional folded body. Specifically, contour closure processing is performed after the partial fixation of all folds of the three-dimensional folded body is completed. Its purpose is to further process the three-dimensional folded body, which has been gathered, shaped, and partially fixed, into a final product with a specific overall shape and structural integrity. Contour closure processing employs two methods: rolling and merging. When using the rolling method, the starting end of one side of the three-dimensional folded body is rolled towards the ending end along its extension direction, and gradually inserted into the corresponding receiving area of ​​the ending end during the rolling process to complete the closure connection. During this rolling process, the edge constraint area of ​​the starting end needs to be gradually inserted into the pre-designed corresponding receiving area of ​​the ending end, such as a slot or an overlapping structure. In this way, the closure connection of the entire structure is completed along the length direction of the three-dimensional folded body, forming a cylindrical or columnar whole. The filter paper not only completes the contour closure but also forms a reliable connection at the closure point, ensuring the sealing and stability of the filter paper during subsequent use.

[0045] When using the combined method, multiple three-dimensional folded components are arranged side-by-side at a second preset spacing. The spacing is determined based on the final product size, filtration area requirements, or specific installation standards. After arrangement, these three-dimensional folded components are joined together along their sides using methods such as adhesive bonding, heat sealing, ultrasonic welding, or mechanical connection to form a unified structure with a larger filtration area or a specific geometry. Multiple filter paper assemblies can be effectively combined into larger filter elements, resulting in higher production efficiency and stability. Both methods ensure the stability of the filter paper during subsequent processing and allow for flexible adjustments based on different product requirements.

[0046] In one embodiment, after the contour closure process employs a rolling method, a connection relationship is formed between the edge constraint area at one starting end of the three-dimensional folded body and the corresponding receiving area at the other ending end, where surface contact and edge embedding coexist simultaneously. This connection relationship extends continuously along the length direction of the three-dimensional folded body.

[0047] In the above embodiments, during the contour closure process using a rolling method, the two ends of the filter paper are connected through a surface contact and edge interlocking connection. Specifically, a composite connection is formed between the edge constraint areas of the starting and ending ends, which both transmits tension and avoids step phenomena. This connection method ensures the overall structural stability of the filter paper after closure and effectively prevents structural deformation caused by uneven stress. The surface contact and edge interlocking method ensures uniform tension transmission at the connection point in the circumferential direction, guaranteeing not only the strength of the connection but also avoiding unevenness at the joint, thus ensuring the filtration effect and stability of the filter paper in actual use, while also improving the operability of the filter paper during production and transportation.

[0048] The present invention also provides an air filter paper, which is manufactured using the folding and forming process of filter paper as described in any of the preceding claims.

[0049] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A folding and forming process for air filter paper, characterized in that, include: S1. Provide a sheet-like filter paper substrate, and divide the filter paper substrate into a central folding area and edge constraint areas on both sides, forming a pre-folding guide structure in the central folding area and a guide transmission structure in the edge constraint areas respectively; S2. Limit the edge constraint area and, based on the relative rotation relationship between the two edge constraint areas, continuously and alternately fold the middle fold area to form an initial fold body, wherein the initial fold body is composed of multiple fold groups connected in sequence. S3. The initial folded body is transported to the shaping station, the edge constraint area is fitted with end constraints, and the body is folded and shaped along the length under the end constraints to form a three-dimensional folded body. S4. The three-dimensional folded body is locally fixed in the fold connection area, and then the outline is closed to obtain filter paper.

2. The folding and forming process for air filter paper according to claim 1, characterized in that, In step S1, the filter paper substrate is conveyed along the length direction, and the middle folded area of ​​the filter paper substrate is continuously or intermittently pressed along the width direction to form a pre-folded guide structure. Each pre-folded guide structure is arranged sequentially along the first preset interval. During the formation of the pre-folded guide structure, the edge constraint area remains continuously unfolded and is transported synchronously, so that a continuous transition is formed between the pre-folded guide structure and the guide transmission structure.

3. The folding and forming process for air filter paper according to claim 1, characterized in that, Before implementing the limit import step for the edge constraint region, the following steps are included: The filter paper substrate that forms the pre-folding guide structure and the guide transmission structure is prepared to be introduced into the folding station. The folding station includes a first limiting channel and a second limiting channel. The relative rotation relationship includes at least one of the height difference, stroke difference or phase difference between the first limiting channel and the second limiting channel. Step S2 includes: The edge constraint area on one side of the filter paper substrate is introduced into the first limiting channel, while the edge constraint area on the other side is introduced into the second limiting channel. During the introduction process, the first limiting channel and the second limiting channel are controlled to form a relative rotation relationship. During the differential introduction process, the middle folding area is folded sequentially along each pre-folding guide structure to form the initial folded body.

4. The folding and forming process for air filter paper according to claim 1, characterized in that, Step S3, the step of performing end constraint mating on the edge constraint region, includes: The edge constraint area on one side of the initial folded body is positioned and engaged with the first end connector, while the edge constraint area on the other side is positioned and engaged with the second end connector. After the engagement is completed, the initial folded body is kept in a state of being restricted at both ends.

5. The folding and forming process for air filter paper according to claim 4, characterized in that, Step S3, the step of gathering and shaping along the length direction under end constraint, includes: With both ends restricted, a relative displacement along the length direction is applied to the initial fold body, causing each fold group to gradually close along the length direction; During the process of gathering each pleat group, the pleat cavities formed between adjacent pleat groups are sequentially inserted for correction. The insertion correction is carried out one by one according to the arrangement of the pleat groups. After all the pleat cavities are corrected, the three-dimensional folded body is output.

6. The folding and forming process for air filter paper according to claim 1, characterized in that, Step S4, the step of locally holding the three-dimensional folded body in the fold connection area, includes: Pressing or hot pressing is applied sequentially to the fold root region of each fold group of the three-dimensional folded body, and a fixing action is applied simultaneously in the transition region between the fold root region and the edge constraint region. The local fixing is continuously advanced along the length direction of the three-dimensional folded body.

7. The folding and forming process for air filter paper according to claim 6, characterized in that, Step S4, the contour closure process, includes: After partially holding all the folds of the three-dimensional folded body in place, the outline is closed. When the contour closure process uses a rolling method, the starting end of one side of the three-dimensional folded body is rolled towards the ending end on the other side along its extension direction. During the rolling process, the edge constraint area of ​​the starting end is gradually inserted into the corresponding receiving area of ​​the ending end, and the closure connection is completed along the length direction. When the contour closure process adopts the merging method, multiple three-dimensional folded bodies are arranged side by side at a second preset interval and combined along the side direction of the three-dimensional folded bodies to form an overall structure.

8. The folding and forming process for air filter paper according to claim 7, characterized in that, After the contour closure process is performed by rolling, a connection relationship is formed between the edge constraint area at the starting end of one side of the three-dimensional folded body and the corresponding receiving area at the ending end of the other side, which is both surface contact and edge embedding. This connection relationship extends continuously along the length direction of the three-dimensional folded body.

9. An air filter paper, characterized in that, The filter paper is prepared using the folding and forming process described in any one of claims 1 to 8.

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