Bending device for high-performance material films

Abstract

To provide a device capable of stably bending films or sheets made of various high-performance materials without leaving any internal stress.SOLUTION: Folding equipment for a high-performance material film that performs valley folding or mountain folding on a peripheral portion of a high-performance material film whose at least the surface is made of plastic, with a bend line set back by a predetermined distance from the leading edge of the peripheral portion, includes a first mold 5 and a second mold 6 that sandwich the peripheral portion in the thickness direction of the film and perform valley folding or mountain folding, and an impact force generator 11 is provided that applies an impact force to the peripheral portion sandwiched between the first mold 5 and the second mold 6 in at least one of the first mold 5 and the second mold 6.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an apparatus for bending a high-functional material film excellent in functions such as stretchability and light-shielding property, such as a polyethylene film, a polypropylene film, a polyolefin film, or a laminate film obtained by laminating these with a metal foil such as an aluminum foil. In particular, it relates to an apparatus for performing bending processing called hemming bending (hemming) or azafolding or crushing bending, which involves bending two sheets over each other.

Background Art

[0002] As an example of this type of high-functional material film, a laminate film obtained by laminating an aluminum foil and a plastic is known, and an example in which a container for housing a lithium-ion secondary battery is constituted by the laminate film is described in Patent Document 1. The laminate plate described in Patent Document 1 is obtained by laminating plastic layers on both sides of a thin aluminum plate, encloses the secondary battery in an airtight state, and at the joint portion around it, the upper and lower laminate plates are overlapped and adhered. In order to fold the joint portion in half, in the method described in Patent Document 1, first, a portion along the side surface of the workpiece is pushed down, and the tip side from the pushed-down portion is received by a lower die or the like, and thus the portion along the workpiece is bent in a V shape with the portion along the workpiece as a base point. Then, the portion extending obliquely upward in the joint portion is pushed from the lateral direction toward the workpiece side, and the portion of the base point is further bent at a sharper angle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The bending method described in Patent Document 1 above involves warm working to prevent damage at the bending point during the bending process. The temperature is set to 100°C to 110°C, and the processing time is approximately 5 seconds. Heating the laminate sheet softens the aluminum sheet and promotes intermolecular displacement in the plastic layer covering it, making it easier to bend. However, this process requires time for heating, as well as time for heat dissipation to return to room temperature, ultimately increasing the overall bending time and making it difficult to improve the efficiency or speed of the process. Furthermore, since thermal energy is consumed for heating, there is a factor that increases the environmental burden, such as greenhouse gas emissions, and improvements in this area are desirable.

[0005] Furthermore, if the workpiece (material) is not heated or warmed during the bending process, the residual stress (internal stress) associated with bending will increase, causing springback. Moreover, the amount of springback is not necessarily uniform, which can cause the ridges (edges) created by bending to become wavy, potentially resulting in defective products. In addition, if the plastic layer on the surface side, which is greatly stretched by bending, changes or deteriorates over time, the stress generated during the bending process may cause cracks or fractures. As described in Patent Document 1, if a secondary battery is housed within, leakage of electrolyte may occur from the cracks or fractures, potentially leading to the explosion or combustion of the secondary battery.

[0006] This invention was made in view of the above-mentioned technical problems, and aims to provide a device that can stably bend films or sheets made of various high-performance materials, including the aforementioned laminate films or laminate sheets, without leaving any internal stress. [Means for solving the problem]

[0007] To achieve the above objective, this invention provides a folding mechanism for a high-performance material film in which the peripheral portion of a high-performance material film, at least on its surface, is folded using a fold line set back a predetermined distance from the leading edge of the peripheral portion, either as a valley fold or a mountain fold. It is placed, The device has a first mold and a second mold that sandwich the peripheral portion in the thickness direction of the film to perform the valley fold or mountain fold, and at least one of the first mold and the second mold holds the peripheral portion sandwiched between the first mold and the second mold. In the clamping direction, impact An impact force generator is installed to apply impact force. The impact force generator is mainly composed of functional elements including a magnetostrictive element or piezoelectric element that electrically generates mechanical deformation, and is configured to repeat the application of impact force and the maintenance of the applied impact force for a predetermined pressurized period of time, with predetermined intervals between each application. It is characterized by the following:

[0008] In this invention, The aforementioned pressurization maintenance time is longer than the aforementioned interval. good.

[0009] In this invention, the high-performance material film includes a film formed by laminating a metal film and a plastic film, and the valley fold or mountain fold may be a bend in which the plastic film is on the outside.

[0010] In this invention, the first mold is provided with a recess for pressing the portion of the peripheral area that has a bend, and the second mold is provided with a projection for pressing the portion of the peripheral area that has a bend towards the inside of the recess, and the impact force may be applied to at least the portion of the bend that is sandwiched between the recess and the projection.

[0011] In this invention, the first mold and the second mold include a first mold and a second mold for the first process that bend the peripheral portion to an angle greater than 90°, and a first mold and a second mold for the second process that bend the portion bent to an angle greater than 90° until the peripheral portion is folded in half and overlaps with each other, and the impact force generator may be provided in at least one of the first mold and the second mold for the first process. [Effects of the Invention]

[0012] In this invention, the peripheral portion of a high-performance material film is sandwiched between a first mold and a second mold, thereby bending the peripheral portion of the film according to the shape of the molds. While the molds are sandwiching and pressing the peripheral portion, an impact force generated by an impact force generator is applied to at least the fold line of the peripheral portion. and maintain for a predetermined period of time. As a result, residual stress (internal stress) at the bending line, i.e., the point where bending occurs, is reduced, and the amount of springback after bending is reduced. In addition, since the residual stress is made uniform in each part along the bending line, the ridge line or the edge of the bent part becomes a straight line parallel to the bending line, making it possible to bend as intended. Furthermore, since the residual stress associated with bending is reduced, defects such as cracks and fractures due to aging can be prevented, even if, for example, the surface layer is a plastic layer. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic perspective view showing an example of a packaging film to be processed in this invention. [Figure 2] This is a cross-sectional view of the peripheral portion of the packaging film, illustrating the procedure for folding the peripheral portion. [Figure 3] This diagram schematically shows an example of the apparatus according to this invention, and is a schematic diagram showing the configuration for performing the first step. [Figure 4] This diagram schematically shows an example of the apparatus according to this invention, and is a schematic diagram showing a mold for performing the second step. [Figure 5] This diagram schematically shows an example of the apparatus according to this invention, and is a schematic diagram showing a mold for performing the third step. [Modes for carrying out the invention]

[0014] This invention will be described with reference to the embodiments shown in the figures. The embodiments listed below are merely examples of how this invention can be implemented and do not limit the invention.

[0015] The apparatus according to this invention is a device for so-called double-folding the peripheral portion of a high-performance material film. The high-performance material film to be processed is a film made of polyethylene, polypropylene, polyolefin, etc., a film made by compounding at least two types of plastics, and a laminated film made by laminating a metal film and a plastic film to provide gas barrier properties. The peripheral portion of the high-performance material film is, for example, the portion that is joined to close the opening when the high-performance material film is configured in a bag shape, and therefore it may be the peripheral portion that extends around the entire circumference of the high-performance material film, or it may be only the closing portion on one side that forms the opening. Furthermore, the folding in this invention is a valley fold or mountain fold of a flat high-performance material film along a predetermined folding line, and in particular, in the case of the laminated film mentioned above, the plastic film is on the outside when folded. The folding angle is not particularly limited, but the load on the folding point is most severe when performing a so-called double fold (a fold with a bending angle of 180°), so the apparatus according to this invention is particularly effective when performing such a double fold. In the field of metalworking, a bi-fold is a type of bending known as hemming bend, kerf bend, or crush bend, in which the two sides of a fold line are overlapped and brought into close contact with each other.

[0016] FIG. 1 is a partial view schematically showing a high-functional material film (hereinafter referred to as a packaging film) 1 as an example of an object to be bent in this invention. The packaging film 1 shown here is a laminate film with a thickness of 0.32 m as an example, which is formed by sandwiching an aluminum foil (aluminum film) from both the front and back sides with a plastic film such as polyethylene and integrating them. It is formed in a bag shape and houses a secondary battery 2 such as a lithium-ion battery inside. At the opening of the packaging film 1, the laminate films are joined and welded to seal the secondary battery 2. The portion where they are welded and closed to each other is the closing margin portion 3 which is the bending target portion in this invention. This closing margin portion 3 corresponds to the peripheral portion in this invention. Since this closing margin portion 3 is plate-shaped and protrudes sideways, it is bent in order not to get in the way during handling or lamination, etc., and also in order not to take up space. Also, in order to ensure an airtight state, the bending is a double-fold such as a hemi-fold as described above.

[0017] Figs. 2(a) to (d) show the bending procedure in schematic cross-sectional views. First, as shown in Fig. 2(a), a portion from the base end portion to the tip end side in the width direction (the left-right direction in Figs. 1 and 2) of the closing margin portion 3 is bent obliquely downward, and at the same time, a portion retreated by a predetermined dimension from the tip edge portion of the closing margin portion 3, that is, a substantially central portion in the width direction, is valley-folded as a bending line 4. In that case, it is bent so that the portion on the tip end side of the bending line 4 faces in the vertical direction, that is, is substantially perpendicular to the closing margin portion 3 (that is, the horizontal plane) before bending. This is to make the angle formed by the portions on both sides sandwiching the bending line 4, that is, the tip end side portion 3A and the base end side portion 3B, an acute angle less than 90°. In other words, the bending angle is 90° or more.

[0018] Next, as shown in (b) of FIG. 2, the portion including the proximal-side portion 3B from the proximal end portion of the closing margin portion 3 to the folding line 4 is bent to a horizontal or slightly obliquely upward direction. In this state, since the distal-side portion 3A forms an acute angle with respect to the proximal-side portion 3B, the distal-side portion 3A is in a direction falling toward the horizontal plane side. Therefore, by simply crushing the distal-side portion 3A from above toward the proximal-side portion 3B, as shown in (c) of FIG. 2, the distal-side portion 3A is overlapped with the proximal-side portion 3B and folded in half. That is, it is so-called half-folded.

[0019] The half-folded portion is pushed up from below and bent upward as shown in (d) of FIG. 2. This is to make the shape of the secondary battery 2 as a whole packaged with the packaging film 1 conform to the shape along the contour of the secondary battery 2.

[0020] Next, the apparatus according to the present invention for performing the bending process shown in FIG. 2 described above will be explained. FIG. 3 schematically shows an apparatus used in a so-called first step of processing the flat closing margin portion 3 into the shape shown in (a) of FIG. 2. As shown in FIG. 3, a lower punch 5 and an upper punch 6 are provided for making the closing margin portion 3 into the shape shown in (a) of FIG. 2. The upper surface (processing surface) of the lower punch 5 has a width for placing the portion from the proximal end portion to the vicinity of the folding line 4 in the closing margin portion 3. The portion corresponding to the folding line 4 has a concave portion (depressed portion) 5A whose cross-sectional shape is an arc shape with a central angle θo of about 120°. Also, in the processing surface, the end portion on the opposite side of the concave portion 5A in the width direction of the lower punch 5, that is, the portion corresponding to a part of the proximal end portion side in the closing margin portion 3, is a narrow flat surface, and this portion serves as a receiving surface 5B for placing and fixing the closing margin portion 3. And the portion between the concave portion 5A and the receiving surface 5B is an inclined surface 5C that smoothly descends from the receiving surface 5B toward the concave portion 5A. This inclined surface 5C is the surface for processing the proximal-side portion 3B shown in (a) of FIG. 2 above.

[0021] An upper bending punch 7 is provided on the side of the lower punch 5 that contacts its side and moves up and down. This upper bending punch 7 is a punch that performs a bending process by pushing up the closing allowance portion 3 (the tip portion 3A shown in Figure 2(a)) that protrudes from the lower punch 5 at the upper corner portion, and the upper surface that forms the almost right-angle upper corner portion is an almost flat surface.

[0022] The upper punch 6 is configured to sandwich the closing portion 3, which is the workpiece, between the inclined surface 5C and the recess 5A of the lower punch 5, and bend it into the shape shown in Figure 2(a). That is, the working surface, which is the lower surface of the upper punch 6, is composed of an inclined surface 6A that is symmetrical to the inclined surface 5C of the lower punch 5, and a projection 6B that is symmetrical to the recess 5A and protrudes toward the recess 5A. In addition, a material holder 8 that moves up and down toward the receiving surface 5B of the lower punch 5 is positioned adjacent to the upper punch 6 and moves up and down together with the upper punch 6.

[0023] The mechanism for raising and lowering the lower punch 5 is described below the lower punch 5, where a lifter 9 is positioned. The lifter 9 is a mechanism that raises and lowers the lower punch 5 and also receives the load of the bending process, and is mainly composed of appropriate actuators. For example, the lifter 9 can be composed of an appropriate mechanism such as a cam mechanism that rotates around a horizontal rotational axis and a cam follower that is pushed up and pulled down by a guide groove or cam surface which is the outer surface of the cam, or a toggle jack mainly composed of a toggle mechanism, or a hydraulic cylinder.

[0024] A holder 10 is provided above the lifter 9, which is moved vertically by the lifter 9. An impact force generator 11 is mounted on top of the holder 10, and the lower punch 5 is attached to the movable part of the impact force generator 11. Therefore, the lower punch 5 is configured to be raised and lowered together with the holder 10 and the impact force generator 11 by the lifter 9.

[0025] The impact force generator 11 is used to apply an impact force to the closing portion 3, which is clamped between the lower punch 5 and the upper punch 6, in the clamping direction. It is mainly composed of magnetostrictive elements and piezoelectric elements (PZT piezoelectric elements), and is configured to generate a pressing force by electrically causing deformation. Essentially, the impact force generator 11 just needs to be configured to repeatedly apply a pressing force to the workpiece in a short period of time. In the bending process described above, the pressing force (impact force) is mainly applied along or near the bending line 4, and the magnitude of the pressing force can be experimentally determined according to the rigidity and material of the workpiece. For example, if a magnetostrictive element is used, the pressing force (impact force) can be adjusted by voltage. The impact force may be simply applied repeatedly, or it may be applied in a cycle of maintaining the pressing force for a predetermined time, leaving a predetermined interval, and then applying it again. In that case, the pressing maintenance time can be, for example, about 20 ms (milliseconds), and the interval can be, for example, about 10 ms. Furthermore, the time for repeatedly applying the impact force can be as short as approximately 3 seconds.

[0026] On the other hand, the upper bending punch 7, which is positioned adjacent to the lower punch 5, is attached to a holder 13 that is raised and lowered by a lifter 12. Since the timing of the raising and lowering of the upper bending punch 7 is different from that of the lower punch 5, the lifter 12 may be provided separately from the lifter 9 for the lower punch 5. Alternatively, if the lifter 9 for the lower punch 5 is configured as a cam mechanism, for example, the lifter 9 for the lower punch 5 can be used as a lifter for the upper bending punch 7 if it is configured to have a cam profile for the upper bending punch 7 that is different from the cam profile for the lower punch 5.

[0027] The upper punch 6 is attached to the lower surface of a holder 15 suspended by a pusher 14. This pusher 14 is a mechanism for pushing the upper punch 6 downward toward the lower punch 5, and is mainly composed of actuators such as a servo motor or hydraulic cylinder. The material holder 8 is attached to the holder 15 in the same way as the upper punch 6. The material holder 8 may be configured to move up and down independently of the upper punch 6, in which case the material holder 8 can be attached to the lower surface of a holder suspended by a suitable pusher (not shown). Alternatively, the material holder 8 may be attached to the holder 15 for the upper punch 6 via an elastic member such as a spring (not shown). In other words, the material holder 8 is for pressing and fixing the closing allowance 3 against the receiving surface 5B of the lower punch 5 before and after the bending process. Therefore, by descending ahead of the upper punch 6 to press down on the closing allowance 3, and compressing the elastic member while further descending the upper punch 6, the closing allowance 3 can be fixed. Furthermore, when raising the upper punch 6, the material holder 8 is pushed toward the lower punch 5 by the elastic member until the elastic member stretches to the specified length, thus maintaining the closing allowance portion 3 in a fixed state.

[0028] Figure 4 schematically shows a forming die for performing the bending process shown in Figures 2(b) and 2(c) above. This forming die performs the so-called second process, in contrast to the so-called first process performed by each punch shown in Figure 3, and comprises a lower punch 21, an upper punch 22, and a material holder 23. The lower punch 21 has an inclined surface 21A that pushes the base end portion 3B shown in Figure 2(b) diagonally upward relative to the horizontal plane, and a receiving surface 21B on which the base end of the closing allowance portion 3 rests. The upper punch 22 presses and bends the so-called open tip portion 3A shown in Figure 2(b) so that it becomes a so-called bifold, and therefore its lower processing surface has an inclined surface 22A parallel to the inclined surface 21A of the lower punch 21. The inclined surface 22A is a surface of a length (width) that presses the portion of the tip portion 3A described above that is a predetermined distance from the bending line 4 towards the tip. Furthermore, the portion of the inclined surface 22A facing the vicinity of the bending line 4 is recessed on the upper side, and its cross-sectional shape is a curved surface with an arc shape. That is, the so-called bending portion, which is the boundary between the base end portion 3B and the tip end portion 3A, is a curved portion with a predetermined radius (for example, an outer diameter (radius) of 400 μm and an inner diameter (radius) of 100 μm) corresponding to the thickness of the closing allowance portion 3, and if this portion is crushed to flatten it, cracks will occur or it will break. Therefore, a recessed portion 22B is formed on the upper side in an arc shape to maintain the curved shape with a predetermined radius. The outer radius of the recessed portion 22B is 600 μm or more. The crack This prevents defects such as cracks and fractures from occurring.

[0029] The material holder 23 is positioned above the receiving surface 21B of the lower punch 21 so as to be able to move up and down. The lower end surface (tip surface) of the material holder 23 is the holding surface, and it is substantially the same shape as the receiving surface 21B of the lower punch 21 and faces each other. Therefore, when the lower punch 21 rises to the lower surface of the closing allowance portion 3 and the material holder 23 descends toward the lower punch 21, the base end of the closing allowance portion 3 is clamped between the receiving surface 21B of the lower punch 21 and the material holder 23, thereby fixing the closing allowance portion 3.

[0030] Furthermore, the mechanism for raising and lowering each punch 21, 22 and the material holder 23 shown in Figure 4 may be the same as the mechanism shown in Figure 3, or it may be configured in the same way as various mechanisms used in conventional press machines. Also, in the molding die that performs bending as the so-called second step shown in Figure 4, since pressure is applied near the bending line 4, the aforementioned impact force generator may be provided on the lower punch 21 or the upper punch 22.

[0031] Figure 5 schematically shows a mold for bending the already folded portion into the shape shown in Figure 2(d). This mold is a mold for performing the so-called third step and comprises a material receiver 31, a material holder 32, and an upper bending punch 33. The material receiver 31 is a mold for supporting the base end of the closing allowance portion 3 from below, and its receiving surface (upper end surface) is inclined so that the right side of Figure 5 is the upper side in order to facilitate upward bending. In contrast, the lower end (tip) of the material holder 32 is pointed so as to press the base end of the closing allowance portion 3 against the upper end surface of the material receiver 31, approximately in the width direction.

[0032] The upper bending punch 33 is positioned to move up and down along the side surface of the material receiver 31, and its upper surface (working surface) is inclined to face the lower surface of the base end portion 3B, which is inclined with respect to the horizontal plane. In other words, the initial step of bending the so-called folded portion upward is to push up the lower surface of the aforementioned base end portion 3B with a surface that contacts almost its entire surface.

[0033] Furthermore, the mechanism for raising and lowering each of the molds shown in Figure 5 may be the mechanism with the configuration shown in Figure 3 or a conventionally known mechanism.

[0034] Furthermore, each punch and material holder shown in Figures 3 to 5 has a length equal to or greater than the length measured in the direction of the bending line 4 in the closing portion 3, in order to make surface contact with the closing portion 3 that is subjected to bending.

[0035] The bending process in the first to third steps described above will now be explained. First, the workpiece, the closing allowance portion 3, is set almost horizontally between the lower punch 5 and the upper punch 6 shown in Figure 3, and in this state, the lower punch 5 is raised to the closing allowance portion 3 by the lifter 9. In this state, the receiving surface 5B of the lower punch 5 is in contact with the lower surface of the base end of the closing allowance portion 3. Next, when the upper punch 6 is lowered by the pusher 14, the projection 6B first contacts the upper surface of the closing allowance portion 3 and pushes it down, while simultaneously pushing the portion of the fold line 4 into the recess 5A of the lower punch 5. At the same time, the base end portion 3B is bent diagonally downward with respect to the horizontal plane. As a result, a valley fold is made at the portion of the fold line 4, and the tip portion 3A is bent so that it is horizontal or slightly upward.

[0036] The lower punch 5 and the upper punch 6 clamp the closing portion 3, and the impact force generator 11 generates an impact force while the projection 6B of the upper punch 6 is pressing the portion of the closing portion 3 along the bending line 4 into the recess 5A of the lower punch 5. As a result, a condition similar to repeated bending load is created along the bending line 4, and the entire portion along the bending line 4 conforms to the processed surface of the lower punch 5 and the upper punch 6 and is bent into a shape similar to that of the processed surface. The impact force is applied as described above, and the state is maintained for a predetermined time (e.g., 20 ms), and then the impact force is applied and maintained again after a predetermined interval (e.g., 10 ms), and this maintenance and interval is repeated multiple times or for a predetermined time (e.g., 3 seconds).

[0037] Subsequently, after stopping the application of impact force, the upper bending punch 7 is raised, causing the tip portion 3A protruding from between the lower punch 5 and the upper punch 6 to bend upward by the upper bending punch 7. This bending is essentially a bending process performed by the upper punch 6 and the upper bending punch 7, and the tip portion 3A is bent upward so as to follow the side of the upper punch 6.

[0038] After performing the so-called first bending process, the upper punch 6 and material holder 8 are raised, and the upper bending punch 7 and lower punch 5 are lowered to release the closing portion 3, and then set into the so-called second forming die shown in Figure 4. In this forming die, the material holder 23 is lowered and its tip defines the vertical position of the base end of the closing portion 3, and in this state, the lower punch 21 is raised, pushing up the tip portion 3A of the closing portion 3 and bending it diagonally upward. At the same time, the receiving surface 21B of the lower punch 21 comes into contact with the lower surface of the closing portion 3, and its base end is sandwiched and fixed between the material holder 23 and the receiving surface 21B of the lower punch 21. In this state, the tip portion 3A is partially overlapping the base portion 3B. Therefore, in this state, the upper punch 22 is lowered, and its inclined surface 22A further bends the tip portion 3A so that it aligns with the base portion 3B. In other words, it is hemi-folded. In this case, the portion along the fold line 4 is located inside the arc-shaped recess 22B formed in the upper punch 22, and thus maintains a curved state with a predetermined radius of curvature. The resulting bent shape is as shown in Figure 2(c) above.

[0039] Then, the closed portion 3, which has been hemi-folded, is set into the molding die of the so-called third step shown in Figure 5. In this third step, the base end of the closed portion 3 is clamped and fixed from above and below by the material receiver 31 and the material holder 32. In this state, the hemi-folded portion protrudes above the upper bending punch 33, and therefore, as the upper bending punch 33 rises, the hemi-folded portion is bent upward. The shape after bending is shown in Figure 2(d).

[0040] As described above, in the bending device according to this invention, when the closing portion 3 of the packaging film 1 is sandwiched between the lower punch 5 and the upper punch 6 and folded in a valley fold, the aforementioned impact force is applied while the closing portion 3 is still sandwiched between the lower punch 5 and the upper punch 6. As a result, the entire portion along the fold line 4 is bent into a shape that accurately or closely follows the processed surfaces of the lower punch 5 and the upper punch 6. Consequently, the portion that becomes the so-called edge along the fold line 4 after bending, and the entire tip portion 3A can be formed into a straight or flat shape.

[0041] When the inventors of this invention conducted experiments, they found that when bending was performed without applying impact force, multiple instances occurred where the so-called edge portion along the bending line 4 was bent in a wavy manner. Furthermore, the angle between the tip portion 3A and the base portion 3B differed at multiple points along the bending line 4, resulting in multiple instances where the tip portion 3A was wavy in the direction along the bending line 4, or where the edge of the tip portion 3A was wavy. This is thought to be due to variations in the degree of bending from part to part, resulting in variations in springback. In contrast, when bending was performed with the aforementioned impact force, the so-called edge portion along the bending line 4 remained straight as intended, and the tip portion 3A remained flat, with its edge also remaining straight. Moreover, the angle between the tip portion 3A and the base portion 3B was smaller when bending was performed with impact force compared to when no impact force was applied, indicating that applying impact force resulted in less springback. Overall, it was confirmed that defect-free bending can be performed by applying impact force.

[0042] The reason why applying the aforementioned impact force produces the above-mentioned effects is not entirely clear, but it is thought that the application of impact force causes material flow, changes in molecular orientation, and displacement at crystal interfaces, which in turn eliminates or reduces residual stress caused by bending. Because residual stress at the bending line 4 can be reduced or eliminated due to these factors, in the case of packaging film 1 with a plastic outer layer, even if the plastic layer changes or deteriorates over time, it is possible to avoid or suppress the occurrence of cracks or fractures at the bending point. In particular, when packaging lithium-ion secondary batteries, it becomes possible to avoid or suppress accidents such as electrolyte leakage due to changes over time.

[0043] Furthermore, this invention is not limited to the embodiments described above, and the impact force generator only needs to be provided in at least one of the upper punch and the lower punch. Also, the mold on which the impact force generator is provided is not limited to the mold used in the so-called first step described above, but may also be provided in the mold used in the so-called second step. Therefore, one of the lower punch 5 and upper punch 6 shown in Figure 3, or the lower punch 21 and upper punch 22 shown in Figure 4, corresponds to the first mold in this invention, and the other corresponds to the second mold. Also, one of the lower punch 5 and upper punch 6 shown in Figure 3 corresponds to the first mold for the first step in this invention, and the other corresponds to the second mold for the first step. One of the lower punch 21 and upper punch 22 shown in Figure 4 corresponds to the first mold for the second step in this invention, and the other corresponds to the second mold for the second step. Furthermore, although the embodiments described above show an example of valley folding in the so-called first step, in this invention, mountain folding may be performed instead of valley folding. Furthermore, the bending in this invention can be any type of bending, such as a hemi fold, and the bending procedure is not limited to the procedure shown in Figure 2 above. The high-performance material film that is the object of bending in this invention may be a film other than a packaging film for housing a secondary battery, and may be a film that forms part of or the surface of some structural material. [Explanation of Symbols]

[0044] 1. Packaging film 2 Secondary battery 3. Closing margin (peripheral part) 3A Tip side part 3B Proximal part 4. Folding line 5. Lower punch 5A Recess 5B receiving surface 5C Slope 6. Upper punch 6A Slope 6B Protrusion 7 punches 8. Material holder 9 Lifter 10 holders 11. Impact force generator 12 Lifters 13 holder 14 Pusher 15 holder 21. Lower punch 21A Slope 21B Receiving surface 22 Upper punch 22A Slope 22B Recess 23 Material Holder 31 Material receiver 32 Material holder 33 punches

Claims

1. A folding device for a high-performance material film, wherein the peripheral portion of the high-performance material film, whose surface is at least made of plastic, is folded in a valley fold or mountain fold along a fold line set at a predetermined distance back from the leading edge of the peripheral portion, The device comprises a first mold and a second mold for sandwiching the peripheral portion in the thickness direction of the film and performing the valley fold or mountain fold, An impact force generator is provided in at least one of the first mold and the second mold, which applies an impact force in the clamping direction to the peripheral portion clamped between the first mold and the second mold. The aforementioned impact force generator is It is mainly composed of functional elements including magnetostrictive elements or piezoelectric elements that electrically generate mechanical deformation, The system is configured to repeat the process of applying the impact force and maintaining that impact force for a predetermined duration, with predetermined intervals between these steps. A bending device for high-performance material films, characterized by the following features.

2. A bending apparatus for a high-performance material film according to claim 1, The pressurization duration is longer than the interval. A bending device for high-performance material films, characterized by the following features.

3. A bending apparatus for a high-performance material film according to claim 1 or 2, The aforementioned high-performance material film includes a film formed by laminating a metal film and a plastic film, and the valley fold or mountain fold is a bend in which the plastic film is on the outside. A bending device for high-performance material films, characterized by the following features.

4. A bending apparatus for a high-performance material film according to any one of claims 1 to 3, The first mold is provided with a recess for pressing the portion of the periphery that corresponds to the bending line, The second mold is provided with a projection that presses the portion of the peripheral area corresponding to the bend line toward the interior of the recessed portion. At a minimum, the impact force is applied to the portion of the bent line that is sandwiched between the recess and the projection. A bending device for high-performance material films, characterized by the following features.

5. A bending apparatus for a high-performance material film according to any one of claims 1 to 3, The first mold and the second mold include a first mold and a second mold for the first process that bend the peripheral portion to an angle greater than 90°, and a first mold and a second mold for the second process that bend the portion bent to an angle greater than 90° until the peripheral portion is folded in half and overlaps with each other. The impact force generator is provided in at least one of the first molding die for the first process, the second molding die for the first process, the first molding die for the second process, and the second molding die for the second process. A bending device for high-performance material films, characterized by the following features.

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