JP2008100775A - Winding core and manufacturing method for wound body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a wound body of a sheet-like material having no winding core and to provide the winding core used in this method. <P>SOLUTION: This core for winding the sheet-like material around it is provided with a pair of core half bodies 2, 2 and a plurality of connection members 3 for connecting a plurality of sections separated from each other in the longitudinal direction of the pair of core half bodies mutually. The core 1 is set to a chuck 21 of a winding shaft of a winding device while an interval between the pair of core half bodies 2 and 2 is made large to form the wound body 22 by winding the sheet-like material on the core. Then, the wound body 22 is removed from the winding device together with the core 1, the pair of core half bodies 2, 2 are shifted to each other in the longitudinal direction to reduce the interval between them, cause a clearance between them and an inner face of the wound body 22, and pull the core 1 out of the wound body 22 to manufacture the wound body having no core. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a winding core used for winding a sheet-like material such as a woven fabric, a knitted fabric, a nonwoven fabric, a continuous long-fiber nonwoven fabric, a sheet, and a film, and a method for producing a wound body using the winding core.

  In general, in order to produce a wound body of a sheet-like material, a winding core is mounted on a winding shaft of a winding device, and the sheet-like material is wound on the winding core to produce a wound body. Conventionally used winding cores are of a cylindrical integrated structure such as paper tubes, plastic tubes, aluminum tubes, etc., and after winding a sheet material on the winding core to produce a wound body, It is shipped to the user with the roll. On the user side, the sheet-like material is pulled out from the roll body and used, and after the use is finished, the core is often discarded as industrial waste. Therefore, there is a problem that it is expensive to dispose of the core. . In particular, recently, it has been demanded to reduce industrial waste as much as possible, and there was a problem in the disposal of the core from this point. The cores are also collected without being discarded, but this also has a problem that the cost is higher than the disposal.

  Therefore, after winding the sheet-like material on the core, it is conceivable to pull out the core from the roll and ship only the roll to the user. However, in the innermost layer of the roll, the sheet-like material is the core of the core. It is extremely difficult to pull out the winding core from the wound body because it is strongly wound around the surface. Moreover, even if it can be pulled out forcibly, in that case, the innermost layer part is pulled out from the roll, and the wound form of the roll collapses and does not become a product.

  On the other hand, as a core support device for mounting a core, one having a configuration in which the core is held by being inserted into the entire length of the core is described in Japanese Utility Model Publication No. 42-4633. In the core support device described in this publication, one end of a pair of core holding parts is pivotally connected to a disk-shaped pedestal, and one or a plurality of core supporting parts are provided in an intermediate region of the pair of core holding parts. The connecting plate is pivotally connected, and the receiving plate is attached to the other end of the pair of core holding parts. After the receiving plate is removed, the pair of core holding parts are attached to the cradle. By swinging to an inclined position, the interval between the pair of core holding parts is narrowed, and it is possible to easily attach and detach the core, and after attaching the core to the pair of core holding parts, By setting the core holding part at a position perpendicular to the cradle, the interval between the pair of core holding parts can be widened and fixed to the inner surface of the core. However, this core support device is for supporting the core, and is not used as a core for winding the sheet-like material directly on the core support device.

Japanese Utility Model Publication No.42-4633

  An object of the present invention is to provide a method for producing a winding body without a winding core in order to eliminate the need to dispose of the winding core on the user side who consumes the winding body. Further, the present invention provides a core that can be easily pulled out from the wound body after the sheet-like material is wound on the core to form the wound body in order to produce the wound body. This is also an issue.

  In the invention according to claim 1 of the present invention, after forming a winding body on a winding core used for winding a sheet-like material, the winding core can be easily pulled out from the winding body. A pair of core halves provided with a winding surface for winding the sheet-like material, and a plurality of connecting materials for mutually connecting a plurality of locations separated in the longitudinal direction of the pair of core halves The plurality of connecting members are pivotally connected to the pair of core halves so that the distance between the pair of core halves can be changed. In this configuration, a lever insertion hole is formed in the vicinity of at least one end of the core half.

  According to a second aspect of the present invention, in the core according to the first aspect, the connecting member can be swung with respect to the longitudinal direction of the core half on at least one of the pair of core halves. A stopper that restrains the angle within a range of 90 degrees to 100 degrees, and a spring is connected to the pair of core halves, and the connection member is connected to the pair of core halves by the spring. It is set as the structure which applies the spring force of the direction which strikes.

  The invention according to claim 3 provides a method for producing a winding body without a winding core so as to eliminate the need to dispose of the winding core on the user side. A pair of core halves each having a winding surface, and a plurality of connecting members for mutually connecting a plurality of locations separated in the longitudinal direction of the pair of core halves, the pair of core halves A winding core provided with a connecting member pivotably connected to the pair of winding core halves so that the distance between the winding cores can be changed is set on the winding shaft of the winding device, and the winding core A winding step of winding the sheet-like material, a step of winding the sheet material on the winding core to form a winding body, and then removing the winding body from the winding device together with the winding core; and a pair of the winding cores The core half is shifted in the longitudinal direction to reduce the distance between the pair of core halves, and the core is Is obtained by a configuration that a step of pulling out.

  According to a fourth aspect of the present invention, in the method of manufacturing a wound body according to the third aspect, a hole for inserting a lever is formed in the vicinity of at least one end of the pair of core halves of the core. When the pair of core halves of the core is displaced in the longitudinal direction, a lever is inserted from the hole, and the tip of the lever is hooked to the end of the other core half, and the lever is used. Thus, the pair of core halves are displaced from each other in the longitudinal direction.

  The invention according to claim 5 is configured such that in the winding step in the method for manufacturing a wound body according to claim 3 or 4 described above, the sheet material is wound with a tension of 3% or less. is there.

  The invention according to claim 6 is the above-described method for manufacturing a wound body according to claim 3, 4 or 5, wherein the sheet-like material to be rolled up has an elongation of 3% or less at a load of 5 kgf / 25 mm. Is.

  Since the core of the present invention has a configuration in which a pair of core halves are connected by a plurality of connecting members that are pivotably connected, the interval between the pair of core halves is increased. In the state, set on the take-up shaft of the take-up device, wind up the sheet-like material thereon to form a roll, and then remove the roll from the take-up device together with the core, and remove the pair of core halves By shifting each other in the longitudinal direction, the distance between the two can be reduced, and a gap can be formed between the inner surface of the wound body and the winding core can be removed from the wound body, so that a wound body without a winding core can be produced. Here, when the pair of core halves are displaced from each other in the longitudinal direction, the lever is inserted into a hole for inserting a lever formed in one of the pair of core halves, and the other core with the lever By pressing the ends of the half halves, it is possible to apply a large force in opposite directions to the pair of core halves, even when the outer surfaces of the pair of core halves are tightened by the rolls and are difficult to move. The pair of core halves can be easily displaced in the longitudinal direction.

  Here, if a spring for energizing the winding core so as to press the stopper against the stopper and the stopper for limiting the swing angle of the coupling material is provided, the pair of core halves and the coupling material do not move. The core can be easily handled during handling such as when the core is mounted on the winding shaft of the winding device.

  In the method for producing a wound body of the present invention, a winding core having a pair of winding core halves is set on a winding shaft of a winding device, and a sheet is wound thereon to form a wound body. The winding body is removed from the winding device together with the winding core, and the pair of core halves are displaced from each other in the longitudinal direction to narrow the distance between the two, so that the winding core is pulled out from the winding body. A wound body can be produced. The produced roll is supplied to the user for use, but since the roll does not have a core, the user does not get the core as waste after the end of use of the roll on the user side. It is possible to reduce the cost of core collection and disposal.

  Here, a lever insertion hole is formed in the vicinity of at least one end of the pair of core halves, the lever is inserted through the hole, and the tip of the lever is the end of the other core half. If it is set as the structure which hooks and pushes on a part, a pair of core half bodies can be easily shifted in the longitudinal direction mutually.

  Further, when the sheet-like material is wound around the core, if the sheet-like material is wound up with a tension of 3% or less, a pair of cores are pulled out to pull out the core from the wound body. When the interval between the winding core halves is narrowed, the inner surface of the winding body is less likely to be reduced, so that the winding core can be easily pulled out.

  Furthermore, when the sheet-like material to be wound is set to have an elongation of 3% or less at a load of 5 kgf / 25 mm, even when the winding tension is set to be large when winding the sheet-like material on the winding core, The elongation of the sheet-like material can be kept small, and the sheet-like material can be tightly wound so that it does not collapse during winding or transportation, and the core can be easily pulled out. It becomes.

  Preferred embodiments of the present invention will be described below with reference to the drawings. 1A is a partial sectional schematic side view of a winding core according to a preferred embodiment of the present invention, FIG. 1B is a schematic sectional view taken along line AA in FIG. 1A, and FIG. FIG. 3B is a schematic cross-sectional view showing the end region of the core shown in FIG. 2 in an enlarged manner, FIG. 3B is a schematic cross-sectional view taken along the line BB, and FIG. 3 shows the region shown in FIG. It is a schematic sectional drawing shown in the state which mutually shifted in the longitudinal direction. The core indicated by reference numeral 1 as a whole is a longitudinal direction of a pair of core halves 2 and 2 provided with a winding surface 2a for winding a sheet-like material, and the pair of core halves 2 and 2 And a plurality of connecting members 3 for mutually connecting a plurality of locations separated from each other, and a pivot attachment 4 for pivotally connecting both ends of each connecting member 3 to the pair of core halves 2 and 2 respectively. The pair of core halves 2 and 2 are partially cylindrical in shape slightly smaller than the semi-cylindrical shape, and are arranged facing each other as shown in FIG. Can be formed. In addition, the shape of the core formed by the pair of core halves 2 and 2 is not limited to the cylindrical shape as illustrated, and may be an elliptical cylindrical shape, a polygonal cylindrical shape, or the like. However, when using a polygonal cylindrical shape, it is preferable to round the corners. For the core half 2, a metal material such as steel or aluminum, plastic, fiber reinforced resin, or the like is used.

The pivot attachment 4 includes a pair of support plates 5a and 5a arranged at intervals so that the connecting member 3 can be inserted, and the support fixture 5 fixed to the core half 2 by welding, adhesion or the like. , A bolt 6 and a nut 7 for connecting the pair of support plates 5a and 5a and the connecting member 3 so as to be pivotable. Here, the pivot attachment 4 is fixed to the center region in the width direction of each core half body 2, and the pivot axis OO (the central axis of the bolt 6) by the pivot attachment 4 at both ends of the connecting member 3. Are defined in parallel to each other and at right angles to the longitudinal direction of the pair of core halves 2 and 2, and also at right angles to the longitudinal direction of the connecting member 3 (the direction connecting the pivot axes OO at both ends). With this configuration, the pair of core halves 2 and 2 can be shifted in the longitudinal direction by pivoting the connecting member 3, and the distance between the pair of core halves 2 and 2 can be changed. As shown in FIG. 2, the length of the connecting member 3 and the circumferential size of the pair of core halves 2 and 2 are such that the angle θ of the connecting member 3 with respect to the longitudinal direction of the core halves 2 is 90 degrees. The maximum dimension D between the winding surfaces 2a, 2a of the pair of core halves 2, 2 is substantially equal to the diameter of the winding surfaces 2a, 2a, and the pair of core halves 2, 2 It is determined that a gap 9 having an appropriate dimension G is formed between the end portions. In addition, the dimension G of the gap 9 is within the range of the gap 9 after the sheet-like material is wound around the pair of core halves 2 and 2 in the state shown in FIG. As shown in FIG. 2, the distance between the pair of core halves 2 and 2 is narrowed, and the maximum dimension D ₁ between the winding surfaces 2a and 2a is decreased, so A gap is created so that the core 1 can be pulled out of the wound body. In addition, it is preferable to set the dimension G of the gap 9 as small as possible within the range that fulfills this function, because the rolled shape of the sheet-like material can be improved. A metal material, plastic, fiber reinforced resin, or the like is also used for the connecting member 3 and the pivot attachment 4.

  In FIG. 2 (b), when the bolt 6 and the nut 7 are attached to the pair of core halves 2, 2 on the extension of the pivot axis OO (the center axis of the bolt 6) by the pivot attachment 4. The hole 10 used for is formed. In addition, after attaching the bolt 6 and the nut 7, an appropriate sheet is preferably pasted and closed in the hole 10.

  The core 1 is further provided in each of the pair of core halves 2 and 2 in the vicinity of the pivot position of each connecting member 3, and the connecting member 3 can swing with respect to the longitudinal direction of the core half. Is connected to a pair of core halves 2 and 2, and the connecting member 3 abuts against the stopper 11. A spring 12 is provided for applying a spring force in the direction. With this configuration, in a state where the pair of core halves 2 and 2 are not constrained, as shown in FIGS. 2A and 2B, the connecting material 3 is constrained at a position where it abuts against the stopper 11, and the pair of cores The halves 2 and 2 are also constrained at a predetermined interval, and the pair of core halves 2 and 2 and the connecting member 3 are constrained so as not to move. For this reason, handling of the core 1 is facilitated when the core 1 is mounted on the winding shaft of the winding device. It should be noted that the constraining position of the connecting member 3 by the stopper 11 is not limited to the position where the angle θ of the connecting member 3 with respect to the longitudinal direction of the core half is constrained to 90 degrees, as in the illustrated embodiment, You may change so that it may restrain within the range which slightly exceeded 90 degree | times (for example, within +10 degree | times, therefore within the range of 90 degree | times to 100 degree | times). Further, the stopper 11 is not limited to being provided on both of the pair of core halves 2 and 2, but may be provided on at least one, but the binding force of the connecting member 3 is greater if the stopper 11 is provided on both. Since it becomes large, it is preferable.

  A lever insertion hole 15 is formed in the vicinity of at least one end of the pair of core halves 2 and 2. As shown in FIG. 2 (a), the hole 15 is inserted with a lever 16, such as a metal rod, and its tip is pressed against the end surface of the core half 2 on the other side, and as shown in FIG. The lever 16 is used to apply a force in the direction of arrow D to the lower end of the lever 16 to apply a large force in the direction of arrow C to the core half 2 on the other side.

  Next, a method for producing a wound body using the core 1 having the above configuration will be described. First, as shown in FIG. 4A, the winding core 1 is mounted on the chuck 21 provided at the tip of the winding shaft 20 of the winding device. The chuck 21 used here fixes and holds both ends of the core 1 in a state in which the pair of core halves 2 and 2 are most open (the connecting member 3 is perpendicular to the longitudinal direction of the core). However, in this embodiment, the structure is inserted into both ends of the core 1, expanded in diameter, and fixed and held by the pair of core halves 2, 2. Things are used.

  Next, a sheet-like material is wound on the core 1 to form a wound body 22 as shown in FIG. At the time of winding, the connecting member 3 becomes a support rod in response to the pressure applied to the pair of core halves 2 and 2 by the winding pressure of the sheet-shaped material wound around the core 1, and the pair of core halves 2 and 2 can be prevented. This prevents winding wrinkles and enables good winding. Moreover, it is possible to increase the winding tension and perform the tight winding, thereby forming the wound body 22 that is unlikely to collapse. Here, the mounting position and the number of the connecting members 3 used are required for the strength of the pair of core halves 2 and 2 depending on the winding conditions such as the material of the sheet material, the winding tension, and the winding amount. It should be determined so that it can be reinforced, but at least one is preferably provided in the winding region of the sheet-like material. When one is provided in the winding region, it is provided in the central portion. It is preferable.

  After winding the sheet material onto the core 1 to form the wound body 22, the chuck 21 is pulled out from the core 1, and the wound body 22 is removed together with the core 1. At this time, since the connecting member 3 becomes a support rod against the pressure caused by the winding pressure of the winding body 22 acting on the pair of core halves 2, 2, the distance between the pair of core halves 2, 2 is narrowed. The chuck 21 can be easily pulled out. Here, in order to prevent the portion of the pair of core halves 2 and 2 into which the chuck 21 is inserted from being narrowed by the winding pressure of the winding body 22, the connecting member 3 is connected to the pair of core halves 2 and 2. It is preferable to arrange in the vicinity of the end of the. As described above, it is preferable to provide one connecting member 3 in the central portion of the winding region of the sheet-like material from the viewpoint of preventing deflection due to winding of the pair of core halves 2 and 2. After all, it is preferable to provide the connecting material 3 at least at three locations near both ends and the center of the pair of core halves 2 and 2.

  As shown in FIG. 4 (c), after the winding body 22 is removed together with the core 21, the forces in opposite directions are applied to the pair of core halves 2, 2 as indicated by arrows C and E. The pair of core halves 2 and 2 are shifted in the longitudinal direction. At this time, when the winding body 22 fastens the pair of core halves 2 and 2 and the core half 2 is difficult to move, it is formed on the lower core half 2 as shown in FIG. A pair of a pair of levers 16 is inserted by inserting a lever 16 into the lever hole 15 and pressing the tip of the lever 16 against the end surface of the core half 2 on the other side. A large force in the C direction and E direction is applied to the core halves 2 and 2. Thereby, a pair of core half bodies 2 and 2 can be easily shifted to a longitudinal direction. When the pair of core halves 2 and 2 are displaced in the longitudinal direction, the connecting member 3 swings, and thereby the pair of core halves 2 and 2 move in a direction approaching each other, as shown in FIG. As shown, a gap 23 is formed between the inner surface of the wound body 22 and the outer surface of the core 1. Thereafter, the core 1 is pulled out from the wound body 22. Thereby, as shown in FIG.5 (b), the winding body 22 without a core is produced.

  The wound body 22 produced as described above is then packaged and supplied to the user. On the user side, the sheet-like material of the wound body 22 is used. However, since the core does not remain even after use, there is no need to treat the core as waste or return it to the manufacturer. Thus, the waste on the user side can be reduced and the cost required for the core processing can be reduced.

  As described above, in the present invention, the sheet-like material is wound on the pair of core halves 2 and 2 while the pair of core halves 2 and 2 are opened. A step of extracting the core 1 from the body 22 is performed. In this step, in order to be able to satisfactorily pull out the core 1 from the wound body 22, it is necessary to wind up the sheet-like material in a state where it is not stretched so much. If the roll 22 is formed by winding the sheet-like material in a large stretch state, the outer diameter of the pair of core halves 2 and 2 is reduced when the core 1 is pulled out from the roll 22. When the diameter is reduced, the inner surface of the wound body 22 is also contracted to leave a portion that is in close contact with the outer surface of the core, so that even if it becomes difficult to remove the core or can be removed, the innermost layer of the wound body 22 These parts are pulled out together, causing collapse, and cannot be pulled out well. In order to avoid this phenomenon, when the sheet-like material is wound around the core 1, the tension is such that the sheet-like material does not stretch so much. Specifically, the elongation of the sheet-like material is 3% or less. It is preferable to wind with such tension.

  As described above, as the sheet-like material to be wound around the core 1 having the above-described configuration, the sheet-like material is wound on the pair of core halves 2 and 2 with the pair of core halves 2 and 2 being opened. As long as the core 1 can be removed from the winding body 22 by narrowing the interval between the winding core halves 2 and 2, the core half is arbitrary. When winding the sheet-like material, it is necessary to apply a certain amount of tension and tightly wind it up so that it will not collapse during winding or during transportation. For easy pulling out of the core, it is preferable to wind up with a tension such that the elongation of the sheet-like material is 3% or less. Therefore, in order to satisfy these conditions, it is preferable to use a sheet-like material having low stretchability. Specifically, the elongation in the winding direction of the sheet-like material is 3% at a load of 5 kgf / 25 mm. Or less, more preferably 3% or less at a load of 10 kgf / 25 mm. By using a sheet-like material having a small elongation rate as described above, even if the sheet-like material is tightly wound, the core can be easily pulled out from the wound body 22, and at that time, the wound body is not collapsed. For this reason, it is possible to produce a wound body that is solidly wound, hardly collapses, and has a core removed. Specific examples of sheet materials with low stretchability include woven fabrics, non-woven fabrics, and continuous fibers using non-stretchable fibers such as resin fibers coated with organic fibers such as glass fibers, carbon fibers, and vinylon. Long fiber non-woven fabrics can be mentioned, and in particular, woven fabrics and continuous long-fiber non-woven fabrics in which non-stretchable fibers are arranged in the longitudinal direction (winding direction) of the sheet material are preferable.

  In addition, the measuring method of the elongation rate of a sheet-like material cuts out the test piece about 25 mm in width and about 250 mm in length so that the winding direction may become a longitudinal direction from a sheet-like material, and the test piece is constant-speed load. A method is used in which a tensile tester is used to pull at a speed of 200 m / min, and the load and elongation are measured to obtain the elongation, and the elongation is 5 kgf / 25 mm and 10 kgf / 25 mm. % Is a value obtained from a chart. When the test piece is cut out, if the sheet-like material is a cloth such as a woven fabric or a continuous long-fiber non-woven fabric, the width of the test piece is selected so that the number of threads is an integer.

  The method for producing a wound body of the present invention can be used for producing a sheet-like material wound body for an arbitrary use. In particular, a wound body used in a civil engineering construction site, for example, a glass fiber woven fabric, a glass fiber nonwoven fabric (continuous) It is preferable for production of a wound body such as a long fiber nonwoven fabric. Although it is desired to reduce waste as much as possible at the civil engineering construction site, since the winding body of the present invention does not use a core, no waste is generated even after the use of the sheet material, and civil engineering construction It is extremely effective for reducing waste on site.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this embodiment, and it is needless to say that the present invention can be appropriately changed within the scope of the claims.

(A) is a partial cross-sectional schematic side view of a core according to a preferred embodiment of the present invention, and (b) is a schematic cross-sectional view taken along line AA in (a). (A) is schematic sectional drawing which expands and shows the edge part area | region of the core shown in FIG. 1, (b) is the schematic sectional drawing seen from the BB arrow. FIG. 2A is a schematic cross-sectional view showing the region shown in FIG. (A) is a schematic cross-sectional view showing a state in which the winding core is mounted on the chuck of the winding shaft, (b) is a schematic cross-sectional view showing a state in which a sheet is formed on the winding core to form a wound body, (C) is schematic sectional drawing which shows the state which removed the winding core from the winding shaft with the winding body (A) is a schematic sectional view showing a state in which a pair of core halves supporting the wound body are displaced from each other in the longitudinal direction, and (b) is a schematic sectional view showing the wound body after the winding core is removed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Winding core 2 Winding core half 2a Winding surface 3 Connecting material 4 Pivoting tool 5 Supporting tool 5a Supporting plate 6 Bolt 7 Nut 9 Crevice 10 Hole 11 Stopper 12 Spring 15 Hole for lever insertion 16 Lever 20 Winding shaft 21 Chuck 22 Winding body 23 Clearance

Claims (6)

  A core used for winding a sheet-shaped material, the pair of core halves having a winding surface for winding the sheet-shaped material, and the pair of core halves separated in the longitudinal direction A plurality of connecting members for mutually connecting the plurality of locations, and the plurality of connecting members pivot with respect to the pair of core halves so that the distance between the pair of core halves can be changed. A core that is freely connected and further has a hole for inserting a lever in the vicinity of at least one end of the pair of core halves.   A stopper provided on at least one of the pair of core halves and restraining the swingable angle of the connecting member with respect to the longitudinal direction of the core halves within a range of 90 degrees to 100 degrees; The core according to claim 1, further comprising: a spring that is connected to the pair of core halves, and a spring force acting on the pair of core halves in a direction in which the connecting member abuts against the stopper. .   A pair of winding core halves provided with a winding surface for winding the sheet-shaped material, and a plurality of connecting materials for connecting a plurality of locations separated in the longitudinal direction of the pair of winding core halves, A winding core provided with a connecting member pivotally connected to the pair of core halves so that the interval between the pair of core halves can be changed is used as a winding shaft of the winding device. A winding step of winding a sheet-like material around the winding core, forming a winding body by winding the sheet material on the winding core, and then removing the winding body from the winding device together with the winding core And a method for producing a wound body, comprising: a step of shifting the pair of core halves of the core in the longitudinal direction to reduce a distance between the pair of core halves and pulling the core from the roll.   A lever insertion hole is formed in the vicinity of at least one end of the pair of core halves of the core, and when the pair of core halves of the core is displaced in the longitudinal direction, 4. A lever is inserted from the hole, the tip of the lever is hooked on the end of the other half of the core, and the pair of core halves are displaced in the longitudinal direction using the lever. A method for producing the described wound body.   The method for producing a wound body according to claim 3 or 4, wherein in the winding step, the sheet-like material is wound with a tension of 3% or less.   The method for producing a wound body according to claim 3, 4 or 5, wherein the sheet material to be wound is made to have an elongation of 3% or less at a load of 5 kgf / 25 mm.

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