Sheet winding device and sheet winding method

Abstract

To provide a sheet winding device and a sheet winding method capable of winding a belt-like sheet to a winding core without any wrinkle, and manufacturing a cylindrical laminate with a predetermined outer diameter.SOLUTION: A winder 1 winds a belt-like sheet 2 to a winding core 3 to manufacture a cylindrical laminate 4. The winder comprises a pressure part 11 which presses a both end part of the winding core 3, and a pressure adjustment part 12 which adjusts a load applied from the pressure part 11 to the winding core 3 so that pressure applied to one end part of the winding core 3 is made larger or smaller than the pressure applied to the other end part. The load applied to the winding core 3 is adjusted, based on a difference between a wound diameter in one end part side of the wound belt-like sheet 2 and the wound diameter in the other end part side, by the pressure adjustment part 12, while winding the belt-like sheet 2 to the winding core 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet winding device and a sheet winding method for winding a strip-shaped sheet around a core to produce a cylindrical laminate. [Background technology]

[0002] Cylindrical laminates such as cartridge filters are manufactured by winding a strip-shaped nonwoven fabric sheet around a core and heat-sealing each layer (see, for example, Patent Document 1). On the other hand, strip-shaped sheets made of materials with low rigidity and high stretchability, such as nonwoven fabric sheets and thin plastic films, tend to wrinkle when wound and are prone to variations in winding diameter.

[0003] Conventionally, methods proposed for preventing wrinkles from occurring when a strip-shaped sheet or film (hereinafter collectively referred to as "strip sheet") is wound onto a core include a winding device that automatically changes the speed difference in response to changes in tension within the tensioning section to keep the winding tension of the winding roller constant (see Patent Document 2), and a winding device that prevents the sheet from floating up by spraying compressed air from an air nozzle (see Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-056446 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-108075 [Patent Document 3] Japanese Patent Application Publication No. 2019-1611 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method of adjusting the speed difference so that the winding tension of the winding roller is constant, as in the device described in Patent Document 2, cannot be applied to cases where the material is wound around a long, thin core that cannot be fitted with a drive system, such as a cartridge filter.Furthermore, the method of spraying compressed air onto a strip-shaped sheet, as in the device described in Patent Document 3, is unsuitable for producing cylindrical laminates such as cartridge filters, because there is a risk that surrounding dust and dirt will fly and cause foreign matter to become mixed into the product.

[0006] Furthermore, the techniques described in Patent Documents 2 and 3 cannot suppress variations in winding diameter, so if, for example, the winding diameter at one end is larger than the winding diameter at the other end, it is necessary to perform a long diameter reduction process on the cylindrical laminate until the desired finished diameter is achieved, resulting in poor productivity.As such, with conventional winding devices, it is difficult to wind a strip-shaped sheet made of a material with low rigidity and easy stretch, such as a nonwoven fabric sheet or a thin plastic film, without wrinkles and evenly on both sides to produce a cylindrical laminate with the desired outer diameter.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a sheet winding device and a sheet winding method that are capable of winding a strip-shaped sheet around a core without wrinkles and producing a cylindrical laminate having a predetermined outer diameter. [Means for solving the problem]

[0008] The sheet winding device of the present invention is an apparatus for winding a strip sheet around a winding core to produce a cylindrical laminate, and has a pressure unit that applies pressure to both ends of the winding core, and a pressure adjustment unit that adjusts the load applied to the winding core from the pressure unit so that the pressure applied to one end of the winding core is greater or less than the pressure applied to the other end, and while the strip sheet is being wound around the winding core, the pressure adjustment unit adjusts the load applied to the winding core based on the difference between the winding diameter at one end of the strip sheet and the winding diameter at the other end. The sheet winding device of the present invention may have a diameter-reducing section that reduces the diameter of the strip-shaped sheet wound around the core by heating and pressurizing it, and a cylindrical laminate having the desired outer diameter may be obtained by reducing the diameter using the diameter-reducing section. The pressure adjusting unit can start adjusting the load based on the difference between the winding diameter at one end side and the winding diameter at the other end side of the strip sheet after a certain time has elapsed since the start of winding the strip sheet. The pressure applying unit may be positioned so that the pressure applying position is 0.07x to 0.14x mm from the edge of the winding core, relative to the length of the winding core (x mm), and the pressure adjusting unit may adjust the load applied to the winding core so that the ratio of the winding diameter at one end of the strip-shaped sheet to the winding diameter at the other end is 1.2 or less.

[0009] The sheet winding method of the present invention is a method for producing a cylindrical laminate by winding a strip-shaped sheet around a winding core, and includes a winding process in which the strip-shaped sheet is wound while applying pressure to both ends of the winding core.In the winding process, the load applied to the winding core is adjusted based on the difference between the winding diameter at one end of the strip-shaped sheet wound around the winding core and the winding diameter at the other end so that the pressure applied to one end of the winding core is greater or smaller than the pressure applied to the other end. The sheet winding method of the present invention may further include a cutting step in which winding of the strip sheet is stopped and the strip sheet is cut when a predetermined winding diameter is reached, and a diameter reduction step in which the strip sheet wound around the winding core is reduced in diameter by applying heat and pressure to the wound strip sheet to obtain a cylindrical laminate having the desired outer diameter. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress wrinkles and variations in winding diameter when winding a strip-shaped sheet around a winding core, and to manufacture a cylindrical laminate that is wrinkle-free and has a substantially uniform outer diameter. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating a configuration of a sheet winding device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing an example of the arrangement of the pressure unit 11. [Figure 3] 1A and 1B are side views showing examples of the arrangement of the pressure unit 11. [Figure 4]3 is a flowchart showing a sheet winding method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0013] (sheet winding device) Fig. 1 is a schematic diagram showing the configuration of a sheet winding device (hereinafter also simply referred to as "winding device") according to an embodiment of the present invention. As shown in Fig. 1, the winding device 1 of this embodiment is a device that winds a strip-shaped sheet 2 around a winding core 3 to produce a cylindrical laminate 4, and in addition to a normal winding mechanism, it is equipped with a pressure unit 11 that applies pressure to both ends of the winding core 3 and a pressure adjustment unit 12 that adjusts the load applied to the winding core 3.

[0014] Furthermore, for example, when a cartridge filter is manufactured as a cylindrical laminate 4 using a nonwoven fabric sheet as the strip sheet 2, the winding device 1 of this embodiment may have various rollers such as heating rollers 13a and 13b that heat the strip sheet 2 and a touch roller 14 that presses the strip sheet 2 against the heating roller 13a, as well as a diameter reducing section that reduces the diameter of the strip sheet 2 wound around the winding core 2 by applying pressure while heating it. Furthermore, the winding device 1 of this embodiment may also be provided with a guide plate 15 that guides the strip sheet 2 to the winding core 3 and a cutter 16 that cuts the strip sheet 2, as necessary.

[0015] [Pressure unit 11] Fig. 2 is a perspective view showing an example of the arrangement of the pressure unit 11, and Figs. 3A and 3B are side views. The pressure unit 11 applies pressure to both ends of the winding core 3 and can be configured, for example, by attaching a load cell 112 and a servo motor 113 to an arm 111. In this case, it is preferable that a pair of disk-shaped or cylindrical bearings 114 be rotatably provided on the load cell 112 at the portion that contacts the winding core 3. The reason for providing the bearings 114 is that, since the winding core 3 rotates when the strip-shaped sheet 2 is wound, the contact portions that are subject to contact pressure must also be rotated, otherwise the contact portions will rub against each other, generating metal powder that will adhere to the cylindrical laminate 4 and cause poor appearance.

[0016] However, if the load cell 112 has only one bearing 114, it will be in contact with the winding core 3 along a single line (line contact), and even a slight deviation in the contact position will make it impossible to apply stable contact pressure to the winding core 3. Therefore, as shown in Figure 2, it is preferable to arrange the bearing 114 so that it presses the winding core 3 from two diagonally upward directions. This reduces friction and allows stable application of contact pressure to the winding core 3.

[0017] 3A and 3B, when a winding core having a length of x mm is used, it is preferable to position the pressure applying unit 11 so that the midpoint of the length or thickness of each bearing 114 is located within a range of 0.07x to 0.14x mm from the edge of the winding core 3. If the distance d from the edge of the winding core 3 to the midpoint of the length or thickness of each bearing 114 is less than 0.07x mm, in other words, if the midpoint is located outside (towards the edge) the position 0.07x mm from the edge of the winding core 3, the effect of pressure on the band-shaped sheet 2 will be reduced and the winding core 3 may bend and deform.

[0018] On the other hand, if the distance d from the edge of the winding core 3 to the midpoint of the length or thickness of each bearing 114 is greater than 0.14x mm, that is, if the midpoint is located inside the position 0.14x mm from the edge of the winding core 3, the bearings 114 will approach the strip-shaped sheet 2 being wound, and even a slight shift in the winding position may cause the strip-shaped sheet 2 and bearings 114 to come into contact, making winding impossible.

[0019] [Pressure adjustment unit 12] The pressure adjustment unit 12 adjusts the load applied from the pressure unit 11 to the winding core 3 so that the pressure applied to one end of the winding core 3 is greater or smaller than the pressure applied to the other end. Here, the load applied from the pressure unit 11 to the winding core 3 can be adjusted by, for example, controlling the servo motor 113 of the pressure unit 11 with the pressure adjustment unit 12.

[0020] While the strip sheet 2 is being wound around the winding core 3, the pressure adjustment unit 12 adjusts the load applied to the winding core 3 based on the difference between the winding diameter at one end and the winding diameter at the other end of the strip sheet 2 wound around the winding core 3. Specifically, the winding diameter of the strip sheet 2 wound around the winding core 3 is monitored continuously or at regular intervals, and when the winding diameter exceeds a preset threshold value for the difference in winding diameter, the servo motor 113 is controlled to apply additional contact pressure in addition to the set contact pressure, and the position of the arm 111 is adjusted.

[0021] Furthermore, when the pressure applying position of pressure applying unit 11 is 0.07x to 0.14x mm from the edge of winding core 3, pressure adjusting unit 12 may adjust the load applied to winding core 3 so that the ratio of the winding diameter at one end of strip sheet 2 to the winding diameter at the other end (winding diameter ratio) is 1.2 or less, in addition to the control based on the winding diameter difference described above. This can further reduce the occurrence of wrinkles and variations in winding diameter. Note that when diameter reduction is performed after winding, the winding diameter ratio is preferably 1.1 or less from the viewpoint of shortening the processing time, and the winding diameter ratio is preferably 1.05 or less from the viewpoint of preventing wrinkles.

[0022] Here, the winding diameter of the strip sheet 2 wound around the winding core 3 can be monitored by the load cell 112 of the pressure unit 11, a sensor capable of measuring the winding diameter, image observation, or other methods. As described above, in the winding device 1 of this embodiment, during winding, the pressure adjustment unit 12 adjusts the contact pressure so that the difference in the winding diameter of the strip sheet 2 wound around the winding core 3 does not become too large (so that it does not exceed a threshold value).

[0023] Depending on the type, width, and thickness of the strip sheet 2, the tension of the strip sheet 2 may become unstable at the start of winding. In this case, the increase in winding diameter also becomes unstable, making automatic control difficult and potentially resulting in the application of more load than necessary. Therefore, at the start of winding, the load applied to the winding core 3 is not adjusted by the pressure adjustment unit 12 described above, and load adjustment can be started after a certain time has passed since the start of winding of the strip sheet 2, when the increase in winding diameter has stabilized. In this way, by providing an automatic adjustment control invalid time during which contact pressure control is not performed at the start of winding, the contact pressure can be adjusted efficiently, eliminating differences in winding diameter due to uneven thickness of the strip sheet.

[0024] Furthermore, it is preferable to control the load adjustment based on the difference in winding diameter every time at least one layer of the strip sheet is wound (at least once per layer). By controlling at this interval, the layers of the wound strip sheet are stacked concentrically, preventing the difference in winding diameter between both ends from becoming too large and making the winding diameter uniform.

[0025] [Reduced diameter part] The diameter-reducing section reduces the diameter of the strip-shaped sheet 2 wound around the core 3 by applying heat and pressure to the strip-shaped sheet 2, thereby obtaining a cylindrical laminate 4 with a desired outer diameter, and can be composed of, for example, the above-mentioned heating rollers 13a and 13b, the touch roller 14, and the pressure section 11. In this case, the contact pressure of the pressure section 11 may be controlled by the pressure adjustment section 12.

[0026] [Other configurations] The guide plate 15 guides the strip sheet 2 to the winding core 3 and is installed on the back side of the strip sheet 2. The guide plate 15 may be a plate-like member that is wider than the strip sheet 2 and has a smooth surface. The material of the guide plate 15 is preferably a heat-resistant material that is not easily deformed, such as stainless steel, but is not limited to such a material and can be appropriately selected depending on the specifications of the strip sheet 2, such as the material and thickness, and on manufacturing conditions, such as the heating temperature during winding.

[0027] Furthermore, the type of cutter 16 is not particularly limited as long as it is capable of cutting the strip-shaped sheet 2, and the cutting method may be either a contact type or a non-contact type. For example, in the case of a contact type, blade cutting such as a cutter blade, mechanical shearing, or press shearing can be used. In the case of a non-contact type, cutting by laser irradiation or laser heating can be used. Among these, blade cutting such as a cutter blade is particularly preferred for the winding device 1 of this embodiment from the standpoint of cost and ease of handling. When blade cutting is used, the material forming the blade and the thickness of the blade are not particularly limited, and conventionally known blades made of SK (carbon tool steel), stainless steel, titanium, ceramic, etc. can be used.

[0028] (Sheet winding method) Next, the operation of the winding device 1 of this embodiment, i.e., a method of using the winding device 1 to wind the strip sheet 2 around the winding core 3 and produce a cylindrical laminate 4, will be described. Fig. 4 is a flowchart showing the sheet winding method of this embodiment. As shown in Fig. 4, the sheet winding method of this embodiment performs a winding step S1 in which the strip sheet 2 is wound while applying pressure to both ends of the winding core 3, and further performs a cutting step S2 in which the strip sheet 2 is cut, and a diameter reduction step S3 in which the diameter of the strip sheet 2 wound around the winding core 3 is reduced by applying pressure while heating.

[0029] <Strip sheet 2> The strip-shaped sheet 2 wound by the sheet winding method of this embodiment is not particularly limited, and may be any material that can be easily folded and wound into a roll, such as a thin plastic film having a thickness of 0.2 to 3.0 mm, or a sheet having a tensile elongation of 100% or less and a tensile strength of 3 N / 50 mm or more. Specific examples of the strip-shaped sheet 2 include nonwoven fabric, paper, rubber-like sheet, film, and thin metal film.

[0030] <Core 3> The winding core 3 is not particularly limited either and can be appropriately selected depending on the purpose and application. For example, a core having an outer diameter of 4 to 45 mm, made of metal such as stainless steel or iron, or made of ceramics, that does not deform even when heated to a high temperature of about 150°C or when pressure is applied can be used.

[0031] [Winding process S1] In the winding step S1, the strip sheet 2 is wound onto the winding core 3 while the pressure unit 11 applies pressure to both ends of the winding core 3. At this time, the load applied to the winding core 3 by the pressure adjustment unit 12 is adjusted based on the difference between the winding diameter at one end of the strip sheet 2 wound onto the winding core 3 and the winding diameter at the other end, so that the pressure applied to one end of the winding core 3 is greater or smaller than the pressure applied to the other end.

[0032] Specifically, as the strip sheet 2 is wound around the reel core 3 and the reel diameter increases, the servo motor 113 is operated to move the arm 111 of the pressure unit 11 upward. At this time, the amount of movement of the arm is adjusted so that the difference in reel diameter between both ends, detected by a load cell 112 or the like, is equal to or less than a preset threshold. In addition to the control based on the reel diameter difference, the amount of movement of the arm may be adjusted so that the reel diameter ratio is 1.2 or less, preferably 1.1 or less, and more preferably 1.05 or less. This reduces variation in reel diameter in the winding process S1.

[0033] It is preferable to adjust the load applied to the core based on the difference in winding diameter after a certain time has elapsed since the start of winding. By providing a period during which the load is not adjusted (automatic adjustment control invalid time) at the start of winding the strip-shaped sheet 2, it is possible to improve the efficiency of contact pressure adjustment and manufacture a cylindrical laminate with uniform winding diameter.

[0034] [Cutting process S2] Next, when a predetermined winding diameter is reached, winding of the strip-shaped sheet 2 is stopped, and the strip-shaped sheet 2 is cut by a cutter 16 .

[0035] [Diameter reduction process S3] In the diameter reduction step S3, the strip-shaped sheet 2 wound around the winding core 3 is reduced in diameter by applying pressure while heating, to obtain a cylindrical laminate 4 with a desired outer diameter. Specifically, the wound strip-shaped sheet 2 (cylindrical laminate 4) is heated by heating rollers 13a and 13b, while the servo motor 113 is operated to move the arm 111 of the pressure unit 11 downward, and pressure is applied by the touch roller 14 and the winding core 3 to which a load is applied by the pressure unit 11.

[0036] At this time, it is preferable to control the load applied to the winding core 3 from the pressure adjusting unit 12 to the winding core 3 from the pressure unit 11 based on the difference between the winding diameter at one end and the winding diameter at the other end of the strip-shaped sheet 2 wound around the winding core 3 so that the pressure applied to one end is greater or smaller than the pressure applied to the other end. For example, if there is a difference in the winding diameter at both ends of the already wound strip-shaped sheet 2 (cylindrical laminate 4) at the time the diameter reduction step S3 is started, the load applied to the winding core 3 is adjusted at a predetermined cycle, such as at least once a revolution, until the difference in winding diameter detected by the load cell 112 or the like becomes equal to or less than a preset threshold value.

[0037] On the other hand, when the diameter reduction step S3 is started, if there is no difference in the winding diameters at both ends or the difference in winding diameters is equal to or less than a preset threshold value, a preset load is applied to the winding core 3 to reduce the diameter, and when the difference in winding diameters exceeds the threshold value, the load is adjusted based on the difference in winding diameter. In either case, when the difference in winding diameters of the wound strip-shaped sheet 2 (cylindrical laminate 4) becomes equal to or less than the threshold value, the load adjustment is stopped and a constant load is applied.

[0038] In the sheet winding device and sheet winding method of this embodiment, the strip sheet is wound while adjusting the load applied to the winding core based on the difference in winding diameter of the strip sheet wound around the winding core, thereby suppressing wrinkles and variations in winding diameter and producing a cylindrical laminate that is wrinkle-free and has a substantially uniform outer diameter. Furthermore, by adjusting the load applied to the winding core based on the difference in winding diameter even during diameter reduction, the target outer diameter can be efficiently achieved, making it possible to increase the production volume per hour by 1.05 to 1.15 times compared to conventional methods. As a result, the productivity of cylindrical laminates can be improved. [Example]

[0039] The effects of the present invention will be specifically described below with reference to Examples and Comparative Examples. In these Examples, a nonwoven fabric sheet having a thickness of 1.10 mm was wound using the winding device shown in Figure 1 under the conditions shown in Table 1 below, and a cylindrical laminate was produced with a target outer diameter of 20.00 mm. The resulting cylindrical laminates of the Examples and Comparative Examples (420 pieces each) were then evaluated for production time, outer diameter accuracy, and the presence or absence of wrinkles.

[0040] 〔evaluation〕 (1) Production time A product that took less than 230 seconds to produce one piece was deemed to have passed, and a product that took more than 230 seconds to produce one piece was deemed to have failed, and the failure rate (%) was calculated.

[0041] (2) Outer diameter accuracy The outer diameter of each cylindrical laminate was measured over its entire length using a Keyence LS-7070 digital dimension measuring instrument. Products with an outer diameter of 19.50 to 20.50 mm at all points (within 0.50 mm of the target outer diameter) were deemed to have passed, and products with an outer diameter of less than 19.50 mm or exceeding 20.50 mm at any point were deemed to have failed, and the failure rate (%) was calculated.

[0042] (3) Wrinkles Each cylindrical laminate of the Examples and Comparative Examples was visually inspected, and those that had no wrinkles (unevenness due to overlapping nonwoven fabrics) were deemed to have passed, and those that had wrinkles in even one place were deemed to have failed, and the failure rate (%) was calculated.

[0043] The evaluation results are summarized in Table 1. Table 1 also shows the percentage of samples that passed all evaluation items (pass rate).

[0044] [Table 1]

[0045] As shown in Table 1 above, the cylindrical laminates of Examples 1 to 3 produced within the scope of the present invention had higher outer diameter accuracy and a significantly reduced wrinkle occurrence rate, despite the shorter production time, compared to the cylindrical laminates of Comparative Examples 1 to 3 produced without load control.

[0046] From the above results, it was confirmed that according to the present invention, it is possible to wind a strip-shaped sheet around a core without wrinkles and to produce a cylindrical laminate having a predetermined outer diameter.

[0047] The present invention can also take the following forms. [1] An apparatus for winding a strip-shaped sheet around a winding core to produce a cylindrical laminate, a pressure applying unit that applies pressure to both ends of the core; a pressure adjusting unit that adjusts the load applied to the winding core from the pressure unit so that the pressure applied to one end of the winding core is greater or smaller than the pressure applied to the other end; and The pressure adjustment unit is a sheet winding device that adjusts the load applied to the winding core based on the difference between the winding diameter at one end of the strip sheet and the winding diameter at the other end while the strip sheet is being wound onto the winding core. [2] a diameter-reducing section that reduces the diameter of the strip-shaped sheet wound around the core by applying pressure while heating the strip-shaped sheet; The sheet winding device according to [1], wherein the cylindrical laminate having the desired outer diameter is obtained by reducing the diameter by the diameter reducing section. [3] The pressure adjustment unit starts adjusting the load based on the difference between the winding diameter at one end of the strip sheet and the winding diameter at the other end after a certain time has elapsed since the start of winding the strip sheet. [4] the pressure applying unit is disposed so that the pressure applying position is 0.07x to 0.14x mm from the edge of the winding core with respect to the length x mm of the winding core, The pressure adjustment unit adjusts the load applied to the core so that the ratio of the winding diameter at one end of the strip sheet to the winding diameter at the other end is 1.2 or less. [5] A method for producing a cylindrical laminate by winding a strip-shaped sheet around a core, comprising: a winding step of winding the strip-shaped sheet while applying pressure to both end portions of the core, In the winding process, the load applied to the core is adjusted based on the difference between the winding diameter at one end of the strip sheet wound around the core and the winding diameter at the other end, so that the pressure applied to one end of the core is greater or smaller than the pressure applied to the other end. [6] a cutting step of ending winding of the strip-shaped sheet and cutting the strip-shaped sheet when a predetermined winding diameter is reached; a diameter reduction step of reducing the diameter of the strip-shaped sheet wound around the core by applying pressure while heating to obtain a cylindrical laminate having a desired outer diameter; The sheet winding method according to [5], comprising: [Explanation of symbols]

[0048] 1 Winding device 2 Strip sheets 3 Core 4 Cylindrical laminate 11 Pressure unit 12 Pressure adjustment section 13a, 13b Heating roller 14 Touch Roller 15 Guide plate 16 cutting machine 111 Arm 112 load cells 113 Servo motor 114 Bearing

Claims

1. An apparatus for winding a strip-shaped sheet around a winding core to produce a cylindrical laminate, a pressure applying unit that applies pressure to both ends of the core; a pressure adjusting unit that adjusts the load applied to the winding core from the pressure unit so that the pressure applied to one end of the winding core is greater or smaller than the pressure applied to the other end; and The pressure adjustment unit is a sheet winding device that adjusts the load applied to the winding core based on the difference between the winding diameter at one end of the strip sheet and the winding diameter at the other end while the strip sheet is being wound onto the winding core.

2. a diameter-reducing section that reduces the diameter of the strip-shaped sheet wound around the core by applying pressure while heating the strip-shaped sheet; 2. The sheet winding device according to claim 1, wherein the cylindrical laminate having a desired outer diameter is obtained by reducing the diameter of the laminate by the reduced diameter portion.

3. The sheet winding device according to claim 1, wherein the pressure adjustment unit starts adjusting the load based on the difference between the winding diameter at one end of the strip sheet and the winding diameter at the other end after a certain time has elapsed since the start of winding the strip sheet.

4. the pressure applying unit is arranged such that the pressure applying position is 0.07x to 0.14x mm from the edge of the winding core with respect to the length of the winding core (x mm); The sheet winding device according to claim 1, wherein the pressure adjusting unit adjusts the load applied to the winding core so that the ratio of the winding diameter at one end of the strip sheet to the winding diameter at the other end is 1.2 or less.

5. A method for producing a cylindrical laminate by winding a strip-shaped sheet around a core, comprising: a winding step of winding the strip-shaped sheet while applying pressure to both end portions of the core, In the winding process, the load applied to the core is adjusted based on the difference between the winding diameter at one end of the strip sheet wound around the core and the winding diameter at the other end, so that the pressure applied to one end of the core is greater or smaller than the pressure applied to the other end.

6. a cutting step of ending winding of the strip-shaped sheet and cutting the strip-shaped sheet when a predetermined winding diameter is reached; a diameter reduction step of reducing the diameter of the strip-shaped sheet wound around the core by applying pressure while heating to obtain a cylindrical laminate having a desired outer diameter; The sheet winding method according to claim 5, further comprising the steps of:

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