Method for manufacturing a paper disc case

Abstract

This invention provides a method for manufacturing a paper optical disc case, using thick paper as a substrate, which can form a cylindrical retaining protrusion that can be inserted into / removed from the circular hole of a disc-shaped optical disc. On the outer periphery of a narrow area in the center of the paper substrate (1) to be formed by deep drawing, a discontinuous first arc-shaped cut (3L) is formed that, when viewed from the center point (O) of the narrow area, does not intersect with the parallel and orthogonal directions of the paper grain of the paper substrate. On the outer periphery of the discontinuous first arc-shaped cut (3L), a discontinuous second arc-shaped cut (4L) is formed that, when viewed from the center point (O), intersects with the parallel and orthogonal directions of the paper grain of the paper substrate (1), and when viewed from the center point (O), does not intersect with the radial directions of the central parts of the discontinuous first arc-shaped cut (3L). Then, a deep drawing process is performed on the narrow area in the center of the paper substrate to form the cylindrical retaining protrusion (2).

Description

Technical Field

[0001] This invention relates to a method for manufacturing a paper optical disc case that can replace a plastic storage box for CDs or DVDs. Background Technology

[0002] Plastic and polystyrene containers have long been widely used as containers for daily necessities and food due to their good formability. However, with the mass production, consumption, and disposal of these containers, the resulting microplastics have led to increasingly prominent problems such as marine pollution. From an environmental perspective, paper containers, which are easy to dispose of after use, have received much attention.

[0003] Therefore, a method was proposed to press and shape flat paper materials, such as thick paper, which are more difficult to process than plastic, to produce tray-shaped or cup-shaped containers while ensuring their strength (Patent Document 1).

[0004] According to the invention described in Patent Document 1, when forming a large-capacity tray shape using ordinary paper, wrinkles appear on the edges or side walls of the tray-shaped container. These wrinkles detract from the appearance and make it impossible to properly mark these areas using printing or other methods. Furthermore, when attempting to seal the container, especially when wrinkles appear at the edges, a complete seal cannot be achieved. Therefore, a manufacturing method to solve these problems has been proposed (Patent Document 2).

[0005] As mentioned above, although many methods for manufacturing paper containers aimed at reducing plastic have been proposed, the main products manufactured are tray-shaped or cup-shaped containers for holding food, and these alternatives are gradually becoming more widespread. Furthermore, plastic products are also being mass-produced and used as cases for electronic devices such as CDs and DVDs, and with the increasing demand for reducing plastic, people are beginning to seek paper alternatives to these plastic products.

[0006] However, the structural feature of disc-shaped optical discs such as CDs or DVDs is that a circular hole is formed in the center. Typically, a plastic storage case with a locking mechanism is used. This locking mechanism has claw-shaped protrusions that fold up along the inner circumference of the hole and engage with its upper edge. Even if a paper-based alternative storage case were to be used, the complex shape of the locking mechanism with claw-shaped protrusions would make it impossible to manufacture this form through pressing. Therefore, a paper optical disc case has been proposed, which uses sheet paper to form a cylindrical retaining protrusion through pressing, allowing insertion / removal of the circular hole in the center of the disc, replacing the claw-shaped locking mechanism (Patent Document 3).

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2002-347736

[0010] Patent Document 2: Japanese Patent Application Publication No. 2023-121290

[0011] Patent Document 3: Japanese Patent Application Publication No. 2005-193923 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] However, even with the invention described in Patent Document 3 above, which uses a stamping machine to deep-draw a planar paper material of 10 cm square or more with a corresponding thickness that employs a laminated structure to maintain a certain level of strength, it is practically impossible to form a cylindrical retaining protrusion with a diameter of less than 15 mm and a height of about 3 to 4 mm corresponding to the diameter of the circular hole in the center of the optical disc. In other words, when attempting to form such a cylindrical retaining protrusion, if a sheet of paper material of a certain thickness for maintaining strength is deep-drawn in a narrow section with the aforementioned dimensions corresponding to the diameter of the circular hole, the concentrated processing pressure applied to this narrow section will cause breakage around the upright base of the cylindrical retaining protrusion, thus making it impossible to practically provide a paper optical disc case of this form.

[0014] Therefore, the objective of this invention is to provide a manufacturing method that uses sheet paper with a certain strength as a base material, and can form a cylindrical retaining protrusion that can be inserted / removed from the circular hole of a disc-shaped optical disc even when stamped using a conventional deep drawing machine. Furthermore, when inserting or removing the optical disc from the retaining protrusion, the method can ensure that the optical disc is easily inserted and difficult to detach, thus realizing a paper optical disc case that can replace traditional plastic storage boxes.

[0015] Technical solutions for solving the problem

[0016] To solve the above-mentioned problems, the present invention has the following structure. Specifically, the manufacturing method of the paper optical disc case of the first invention is characterized in that a cylindrical retaining protrusion for inserting / removing a circular hole for storing an optical disc is formed in the central portion of a square planar paper substrate through a deep drawing process. In this method, a discontinuous first arc-shaped cut is formed on the outer periphery of the narrow area where the cylindrical retaining protrusion is formed by deep drawing in the central portion of the paper substrate. Viewed from the center point of this narrow area, the discontinuous first arc-shaped cut does not intersect with the parallel or orthogonal directions of the paper grain of the paper substrate. Furthermore, a discontinuous second arc-shaped cut is formed on the outer periphery of the discontinuous first arc-shaped cut. Viewed from the center point, the discontinuous second arc-shaped cuts are staggered with the parallel and orthogonal directions of the paper grain of the paper substrate, and the radial directions of the discontinuous second arc-shaped cuts through the center portions of the discontinuous first arc-shaped cuts are not staggered (i.e., the cut portions of the discontinuous second arc-shaped cuts are formed to avoid the radial directions through the center portions of the first arc-shaped cuts). After forming these discontinuous first arc-shaped cuts and discontinuous second arc-shaped cuts, a deep drawing process is performed on the narrow area in the center of the paper substrate to form a cylindrical retaining protrusion that can be inserted / pulled out of the circular hole of the optical disc.

[0017] Furthermore, the manufacturing method of the paper optical disc case of the second invention is characterized in that, similarly to the first invention, a deep drawing process is performed on the outer periphery of a narrow area of ​​a cylindrical retaining protrusion formed in the center of the paper substrate, forming discontinuous first arc-shaped cuts and discontinuous second arc-shaped cuts. Starting from the circumference of the narrow circular area of ​​the cylindrical retaining protrusion, which becomes the base of the cylinder after forming, and ending at the circumference of the upper surface of the cylinder after forming, a plurality of teardrop-shaped notches are formed at equal intervals along the circumference. The teardrop-shaped notches are thinner at the front end and slightly larger at the rear end in the direction toward the center point of the narrow area. After forming these discontinuous first arc-shaped cuts, discontinuous second arc-shaped cuts, and teardrop-shaped notches, a deep drawing process is performed on the narrow area of ​​the center of the paper substrate to form a cylindrical retaining protrusion that can be inserted / removed from the circular hole of the optical disc.

[0018] Furthermore, in the first invention, the paper substrate is 5 cm square or larger and 0.4 to 1.0 mm thick. When the cylindrical retaining protrusion in the narrow area of ​​the central part of the paper substrate where the deep drawing process is performed is set to have a diameter of 15 mm or less and a height of 3 to 4 mm, the first arc-shaped cut is formed at a distance of 6 mm from the outer periphery of the cylindrical retaining protrusion, and the second arc-shaped cut is formed at a distance of 8 mm from the outer periphery of the cylindrical retaining protrusion. In the second invention, the length of the teardrop-shaped notch is 6.2 mm.

[0019] Invention Effects

[0020] According to the manufacturing method of the paper CD case of the first invention, a discontinuous first arc-shaped cut is formed around a narrow area of ​​a cylindrical retaining protrusion formed by deep drawing in the central part of a paper substrate. Viewed from the center point of this narrow area, the first arc-shaped cut does not intersect with the parallel or orthogonal directions of the paper grain. A discontinuous second arc-shaped cut is formed around the outer periphery of the discontinuous first arc-shaped cut. The second arc-shaped cut intersects with the parallel and orthogonal directions of the paper grain. Furthermore, viewed from the center point, the radial directions passing through the center points of the discontinuous first arc-shaped cut do not intersect. After forming these first and second discontinuous arc-shaped cuts, a deep drawing process is performed on the narrow area of ​​the central part of the paper substrate using a stamping press. Therefore, when deep drawing pressure is applied to this narrow area, the deep drawing pressure is also applied to the discontinuous first and second arc-shaped cuts, causing cracks to form in these cuts and dispersing the deep drawing force.

[0021] Therefore, the drawing pressure is not concentrated at the base of the drawn cylindrical retaining protrusion, and unlike existing technologies, it does not break around the upright base of the cylindrical retaining protrusion. Taking the paper grain of the paper substrate into account when forming these arc-shaped cuts, the cut portions of the first and second discontinuous arc-shaped cuts do not coincide with each other. Therefore, the concentration and dispersion of the drawing pressure can function in a balanced manner, preventing breakage at the base of the cylindrical retaining protrusion and enabling the cylindrical retaining protrusion to be formed while maintaining a certain strength.

[0022] Furthermore, the paper substrate is 5cm square or larger and 0.4-1.0mm thick. When deep drawing is performed on the central portion of this paper substrate, and the forming conditions for the cylindrical retaining protrusion in the narrow area are set to a diameter of 15mm or less and a height of 3-4mm, a discontinuous first arc-shaped cut is formed at a distance of 6mm from the deep drawing position at the outer periphery of the base of the cylindrical retaining protrusion, and a discontinuous second arc-shaped cut is formed at a distance of 8mm from the deep drawing position at the outer periphery of the base of the cylindrical retaining protrusion. In this way, the concentration and dispersion of the deep drawing force can be balanced, and the cylindrical retaining protrusion meeting the set conditions can be reliably formed while maintaining practical strength. The position setting of this cut is based on experimental data obtained by the applicant through repeated experiments.

[0023] According to the manufacturing method of the paper CD case of the second invention, similar to the first invention, when the drawing pressure is applied to the narrow area, the drawing pressure is applied to the discontinuous first and second arc-shaped cuts. These cuts will produce cracks, which will disperse the drawing force. The drawing pressure will not be concentrated at the base of the drawn cylindrical retaining protrusion, and unlike the prior art, it will not break around the upright base of the cylindrical retaining protrusion. Furthermore, starting from the circumference of the cylindrical base after forming the narrow circular area of ​​the cylindrical retaining protrusion and ending at the circumference of the upper surface of the cylinder after forming, multiple teardrop-shaped notches are formed at equal intervals. The teardrop-shaped notches are thinner at the front end and slightly larger at the rear end in the direction towards the center of the narrow area. Therefore, during deep drawing, these teardrop-shaped notches formed on the cylindrical sidewall of the cylindrical retaining protrusion will also produce tiny cracks. As described above, the deep drawing pressure will act in a dispersed manner when the cylindrical retaining protrusion is erected, and the sidewall of the cylindrical retaining protrusion will not break, so the cylindrical retaining protrusion can be formed in a more stable state.

[0024] Furthermore, when inserting / removing a disc using the cylindrical retaining protrusion, the tiny crack closes during insertion, making it easier to insert. After insertion, the tiny crack widens, making the disc difficult to remove. When removing the disc, simply press down on the upper surface of the cylindrical retaining protrusion while lifting the disc, and the tiny crack will close, allowing for easy removal.

[0025] Furthermore, similar to the first invention, when the size of the paper substrate and other forming conditions are set to be the same, by forming the teardrop-shaped notch to a length of 6.2 mm, as described above, the concentration and dispersion of the drawing force can be balanced, enabling the reliable forming of a cylindrical retaining protrusion that meets the set conditions while maintaining practical strength. The position, number, and length of this notch are also based on experimental data obtained by the applicant through repeated experiments. Attached Figure Description

[0026] Figure 1 It is a three-dimensional view showing the external shape of a paper CD case for manufacturing purposes.

[0027] Figure 2 This is an explanatory diagram illustrating the cutting process in the pre-drawing stage of an embodiment of the first invention.

[0028] Figure 3 This is a perspective view showing the appearance of a cylindrical retaining protrusion formed according to the manufacturing method of the first embodiment, which can be inserted into / removed from the circular hole in the center of the optical disc.

[0029] Figure 4This is a perspective view showing the appearance of a storage box shaped into the size of a standard optical disc according to the manufacturing method of the first invention.

[0030] Figure 5 This is a perspective view showing the state in which the disc-shaped optical disc is stored in the paper optical disc case of the first embodiment.

[0031] Figure 6 This is an explanatory diagram illustrating the cutting and notching process in the pre-drawing stage of an embodiment of the second invention.

[0032] Figure 7 This is a perspective view showing the appearance of a cylindrical retaining protrusion formed according to the manufacturing method of the second embodiment, which can be inserted into / removed from the circular hole in the center of the optical disc.

[0033] Figure 8 This is a perspective view showing the appearance of a storage box shaped into the size of a standard optical disc according to the manufacturing method of the second invention.

[0034] Figure 9 This is a perspective view showing the state in which the disc-shaped optical disc is stored in the paper optical disc case of the second embodiment. Detailed Implementation

[0035] The following description relates to embodiments of the present invention, with reference to the accompanying drawings.

[0036] Example 1

[0037] Figure 1 This is a perspective view showing the basic form of a paper CD case for manufacturing purposes. For example, the sheet-like paper substrate 1 is 5cm square or larger and 0.4 to 1.0mm thick (in this embodiment, a 5cm square and 1.0mm thick paper substrate is used as the object, assuming that a CD with a diameter of 5cm is to be stored). A stamping forming machine is used to perform a deep drawing process on a small area in the center of the paper substrate 1 to form a cylindrical retaining protrusion 2 with a diameter of 15mm or less and a height of 3 to 4mm. In this way, the cylindrical retaining protrusion 2 with a diameter of 15mm or less and a height of 3 to 4mm can be inserted into the hole of the CD (usually with a diameter of 15mm) and engaged with it, thereby storing the CD. However, when using a traditional stamping machine to perform this type of deep drawing, the paper substrate 1 has strong molecular bonding and lacks the external force ductility of metal. Therefore, when a strong external force is applied, the base 2B of the cylindrical retaining protrusion 2 to be formed will break, and it is actually impossible to form this shape.

[0038] In the manufacturing method of the embodiment of the first invention, as follows: Figure 2As shown, as a preliminary step for forming a cylindrical retaining protrusion 2 in a narrow area in the center of the paper substrate 1, a discontinuous first arc-shaped cut 3L is formed on the outer periphery of the area to be formed as the base 2B of the cylindrical retaining protrusion 2. From the center point O of the narrow area, the discontinuous first arc-shaped cut 3L does not intersect with the parallel direction or orthogonal direction of the paper grain of the paper substrate 1.

[0039] Furthermore, a discontinuous second arc-shaped cut 4L is formed on the outer periphery of the discontinuous first arc-shaped cut 3L. This discontinuous second arc-shaped cut 4L intersects with the parallel and orthogonal directions of the paper grain of the paper substrate 1, and from the center point O, the radial directions passing through the central portions of the discontinuous first arc-shaped cut 3L do not intersect. As shown in the figure, the discontinuous first arc-shaped cut 3L is formed at a position 6 mm away from the drawn position of the base 2B of the cylindrical retaining protrusion 2, and the discontinuous second arc-shaped cut 4L is formed at a position 8 mm away from the drawn position of the base 2B of the cylindrical retaining protrusion 2.

[0040] In the manufacturing method of this embodiment, as a preliminary step, after forming the first arc-shaped cuts 3L and the second arc-shaped cuts 4L, a deep drawing process is performed on a narrow area in the center of the paper substrate 1 using a stamping machine. When performing the deep drawing process using a stamping machine, conventional equipment is used, and no special equipment is used for implementing this invention; therefore, the description of the deep drawing process itself is omitted.

[0041] Figure 3 This is a perspective view showing the appearance of a cylindrical retaining protrusion 2 formed in the center of a paper substrate 1 by the manufacturing method described in the above embodiment. As shown in the figure, crescent-shaped cracks 3LH and 4LH are generated around the base 2B of the formed cylindrical retaining protrusion 2 at the discontinuous first arc-shaped cut 3L and second arc-shaped cut 4L.

[0042] The reason why these crescent-shaped cracks 3LH and 4LH are generated is that when the paper substrate 1 is deep-drawn in a narrow area in the center using a stamping forming machine, the deep-drawing pressure also acts on the discontinuous first arc-shaped cut 3L and second arc-shaped cut 4L, thereby generating cracks 3LH and 4LH in these cuts 3L and 4L. This indicates that the deep-drawing force is not concentrated on the base 2B, but is dispersed around it.

[0043] In this way, the drawing pressure will not be concentrated on the base 2B of the drawn cylindrical retaining protrusion 2, and therefore breakage will not occur around the upright base 2B of the cylindrical retaining protrusion 2. However, when forming these arc-shaped cuts, the paper texture of the paper substrate is taken into account. The cut portions in the discontinuous first and second arc-shaped cuts do not coincide with the discontinuous portions. Therefore, the concentration and dispersion of the drawing pressure can play a more balanced role, preventing the base 2B of the cylindrical retaining protrusion 2 from breaking, and the cylindrical retaining protrusion 2 can be formed while maintaining a certain strength. By inserting the formed cylindrical retaining protrusion 2 into the hole of the optical disc and engaging it, the optical disc can be stored on the paper substrate 1.

[0044] In this embodiment, when the cylindrical retaining protrusion 2 is inserted into and engaged with the hole of the optical disc, a step portion 5 is further formed on the outer periphery of the discontinuous first arc-shaped cut 3L and second arc-shaped cut 4L to facilitate easier insertion and removal of the optical disc. The cylindrical retaining protrusion 2 and the step portion 5 are formed simultaneously. Due to the formation of the step portion 5, the optical disc engaged with the cylindrical retaining protrusion 2 becomes slightly raised, making it easier to remove. Furthermore, since crescent-shaped cracks 3LH and 4LH are generated on the outer periphery of the cylindrical retaining protrusion 2, considering the potential decrease in peripheral strength of the base 2B when the cylindrical retaining protrusion 2 is inserted into and engaged with the hole of the optical disc, a small recess 6 is formed around the base 2B to maintain strength.

[0045] As described above, a discontinuous first arc-shaped cut 3L is formed at a depth position 6 mm from the outer periphery of the base 2B of the cylindrical retaining protrusion 2, and a discontinuous second arc-shaped cut 4L is formed at a depth position 8 mm from the outer periphery of the base 2B of the cylindrical retaining protrusion 2. Therefore, the concentration and dispersion of the drawing force can be balanced, and the cylindrical retaining protrusion 2 that meets the set conditions of the paper substrate 1 can be reliably formed while maintaining practical strength. The position setting of this cut is based on experimental data obtained by the applicant through repeated experiments.

[0046] Figure 4This is a perspective view showing the appearance of a cardboard box for storing an optical disc with a diameter of 12 cm, manufactured using a paper substrate 10 according to the manufacturing method of the present invention. The portion surrounding the cylindrical retaining protrusion 2 formed as described above is shown as a solid line, while other portions are shown as dashed lines as an example of the shape, allowing for various storage configurations provided in the prior art based on the size of the optical disc. As shown in this figure, for a 15 cm square paper substrate 10, a storage recess 11 is formed, which serves as the storage portion for the entire optical disc when the cylindrical retaining protrusion 2 is inserted into and engaged with the hole in the optical disc; an optical disc removal recess 12 communicates with the cylindrical retaining protrusion 2; and a peripheral wall portion 13 formed along the outer shape of the optical disc, forming these storage recesses 11 and removal recesses 12. These portions are formed on a single template using a stamping machine to achieve this shape.

[0047] Figure 5 This is a perspective view showing the state in which the disc-shaped optical disc 20 is stored in a paper storage box manufactured by applying the manufacturing method of the present invention to the paper substrate 10 as described above. The cylindrical retaining protrusion 2 can be inserted into the hole 21 of the disc-shaped optical disc 20 and engaged, storing the entire optical disc in the storage recess 11. The stored disc-shaped optical disc 20 can be easily removed by inserting a fingertip into the removal recess 12 to release the engagement.

[0048] As described above, according to the manufacturing method of the first invention, using sheet paper with a certain strength as the base material, even when stamped using a commonly used deep drawing machine, a cylindrical retaining protrusion that can be inserted into / pulled out of the circular hole of the disc-shaped optical disc can be formed. Therefore, it is possible to practically provide a paper optical disc case that can replace plastic storage boxes, which has not been possible until now.

[0049] Example 2

[0050] Next, embodiments of the second invention will be described. The paper optical disc case, for manufacturing purposes, is similar to the one described above. Figure 1 The basic shape shown in the 3D view is the same, so the description is omitted.

[0051] In the manufacturing method of the second embodiment of the invention, similar to the first embodiment, firstly as follows: Figure 6 As shown, as a preliminary step for forming a cylindrical retaining protrusion 2 in a narrow area in the center of the paper substrate 1, a discontinuous first arc-shaped cut 3L is formed on the outer periphery of the area to be formed as the base 2B of the cylindrical retaining protrusion 2. From the center point O of the narrow area, the discontinuous first arc-shaped cut 3L does not intersect with the parallel direction or orthogonal direction of the paper grain of the paper substrate 1.

[0052] Next, a discontinuous second arc-shaped cut 4L is formed on the outer periphery of the discontinuous first arc-shaped cut 3L. This discontinuous second arc-shaped cut 4L intersects with the parallel and orthogonal directions of the paper grain of the paper substrate 1, and from the center point O, the radial directions passing through the center portions of the discontinuous first arc-shaped cut 3L do not intersect. As shown in the figure, the discontinuous first arc-shaped cut 3L is formed at a position 6 mm away from the drawn position of the base 2B of the cylindrical retaining protrusion 2, and the discontinuous second arc-shaped cut 4L is formed at a position 8 mm away from the drawn position of the base 2B of the cylindrical retaining protrusion 2.

[0053] Next, starting from the circumference of the cylindrical base 2B formed after the narrow circular area of ​​the cylindrical retaining protrusion 2 is formed, and ending at the circumference 2C formed after the upper plane edge of the cylinder, eight teardrop-shaped notches 2L are formed at equal intervals along the circumference. The teardrop-shaped notches 2L are thinner at the front end and slightly wider at the rear end in the direction towards the center point O of the narrow area. The length of the teardrop-shaped notch 2L is 6.2 mm.

[0054] In the second embodiment, as a preliminary step, after forming the first arc-shaped cuts 3L, the second arc-shaped cuts 4L, and the teardrop-shaped cuts 2L, a deep drawing process is performed on a narrow area in the center of the paper substrate 1 using a stamping machine. When performing this deep drawing process using a stamping machine, conventional equipment is used, as in the first embodiment; therefore, the description of the deep drawing process itself is omitted.

[0055] Figure 7 This is a perspective view showing the appearance of a cylindrical retaining protrusion 2 formed in the center of a paper substrate 1 by implementing the manufacturing method of the second embodiment as described above. As shown in the figure, crescent-shaped cracks 3LH and 4LH are generated around the base 2B of the formed cylindrical retaining protrusion 2 at the locations of the discontinuous first arc-shaped cut 3L and second arc-shaped cut 4L. Ultra-thin convex lens-shaped cracks 2LH are generated at the locations of eight teardrop-shaped notches 2L formed from the base 2B of the cylindrical retaining protrusion 2 to the circumferential edge 2C that becomes the upper surface edge of the cylinder and then becomes the side wall surface of the cylinder.

[0056] The reason why these crescent-shaped cracks 3LH, 4LH and ultra-thin convex lens-shaped cracks 2LH are generated is that when the paper substrate 1 is deep-drawn in a narrow area in the center using a stamping forming machine, the deep-drawing pressure also acts on the discontinuous first arc-shaped cut 3L, second arc-shaped cut 4L, and teardrop-shaped notch 2L, thereby generating cracks 2LH, 3LH, and 4L in these notches 2L, cuts 3L, and 4L. This indicates that the deep-drawing force is not concentrated at the base 2B, nor is it concentrated from the base 2B to the circumference 2C, but rather the processing pressure is dispersed around it.

[0057] In this way, the concentration and dispersion of the deep drawing pressure can more evenly affect the first arc-shaped cut 3L, the second arc-shaped cut 4L, and the teardrop-shaped notch 2L, preventing the base 2B of the cylindrical retaining protrusion 2 from breaking around and on the sidewalls, and enabling the cylindrical retaining protrusion 2 to be formed while maintaining a certain strength.

[0058] In the second embodiment, the cylindrical retaining protrusion 2 is shaped as described above. Therefore, when inserting / removing the optical disc using the cylindrical retaining protrusion 2, the micro-crack 2LH closes during insertion, making insertion easier. After insertion, the micro-crack 2LH expands, making the optical disc difficult to remove. When removing the optical disc, simply holding the upper surface of the cylindrical retaining protrusion 2 while lifting the optical disc closes the micro-crack 2LH, allowing for easy removal. Thus, by inserting and engaging the formed cylindrical retaining protrusion 2 into the hole of the optical disc, the optical disc can be stably stored in the paper substrate 1 in a state where it is difficult to remove, and removal operations can be performed easily and reliably.

[0059] In the second embodiment, when the cylindrical retaining protrusion 2 is inserted into and engaged with the hole of the optical disc, a stepped portion 5 is further formed on the outer periphery of the discontinuous first arc-shaped cut 3L and second arc-shaped cut 4L to facilitate easier and more reliable insertion / removal of the optical disc. Simultaneously, a recessed surface 2D is formed on the upper plane of the cylindrical retaining protrusion. By forming the stepped portion 5, the optical disc engaged with the cylindrical retaining protrusion 2 becomes slightly raised. By pressing down the recessed surface 2D of the cylindrical retaining protrusion, the crack 2LH quickly closes, thus making the removal of the optical disc easier. Furthermore, similar to the first embodiment, since crescent-shaped cracks 3LH and 4LH are generated on the outer periphery of the cylindrical retaining protrusion 2, considering the potential decrease in peripheral strength of the base 2B when the cylindrical retaining protrusion 2 is inserted into and engaged with the hole of the optical disc, a small recess 6 is formed around the base 2B to maintain strength.

[0060] Similar to the first embodiment, a discontinuous first arc-shaped cut 3L is formed at a drawing position 6 mm from the outer periphery of the base 2B, which becomes the cylindrical retaining protrusion 2, and a discontinuous second arc-shaped cut 4L is formed at a drawing position 8 mm from the outer periphery of the base 2B, which becomes the cylindrical retaining protrusion 2. When eight teardrop-shaped notches 2L are formed at equal intervals from the circumferential edge of the base 2B to the circumferential edge 2C, which becomes the upper plane edge of the cylinder, and pointing towards the center point O, the length of each teardrop-shaped notch 2L is 6.2 mm. According to this setting, the concentration and dispersion of the drawing force can function in a balanced manner, enabling the reliable forming of the cylindrical retaining protrusion 2, which adapts to the set conditions of the paper substrate 1, while maintaining practical strength. The position settings of each cut, as well as the number and position settings of the notches, are based on experimental data obtained by the applicant through repeated experiments.

[0061] Figure 8 This is a perspective view showing the appearance of a cardboard box for storing a 12cm diameter optical disc using a paper substrate 10 manufactured according to the manufacturing method of the second invention. Similar to the first embodiment, the portion surrounding the formed cylindrical retaining protrusion 2 is shown as solid lines, while other portions are shown as dashed lines as an example of the shape, allowing for various storage configurations available in the prior art for different optical disc sizes. As shown in the figure, for a 15cm square paper substrate 10, a storage recess 11 is formed that serves as the storage portion for the entire optical disc when the cylindrical retaining protrusion 2 is inserted into and engaged with the hole in the disc; an optical disc removal recess 12 communicates with the cylindrical retaining protrusion 2; and a peripheral wall portion 13 formed along the outer shape of the optical disc, forming these storage recesses 11 and removal recesses 12. These portions are formed on a single template using a stamping machine to achieve this shape.

[0062] Figure 9 This is a perspective view showing the state in which the disc-shaped optical disc 20 is housed in a paper storage box manufactured by the manufacturing method of the second invention on the paper substrate 10 as described above. When the cylindrical retaining protrusion 2 is inserted into the hole 21 of the disc-shaped optical disc 20 and engaged therewith, thereby housing the entire optical disc in the storage recess 11, the optical disc will not easily fall out in the engaged state and can be stably stored. By simply inserting a fingertip into the removal recess 12 to release the engagement and pressing the recessed surface 2D of the cylindrical retaining protrusion as described above, the stored disc-shaped optical disc 20 can be removed more easily and smoothly.

[0063] As described above, according to the manufacturing methods of the first and second inventions, using sheet paper with a certain strength as the base material, even when stamped using a commonly used deep drawing machine, a cylindrical retaining protrusion that can be inserted into / pulled out of the circular hole of the disc-shaped optical disc can be formed. Therefore, it is possible to practically provide a paper optical disc case that can replace plastic storage boxes, which has not been possible until now.

[0064] Industrial availability

[0065] According to the above embodiments, when a small area in the center of a paper substrate is drawn using a stamping machine to form a cylindrical retaining protrusion with a small diameter, multiple cuts and notches are formed around this small area to avoid concentrating the drawing pressure on it. This allows the drawing pressure to also be applied to these cuts and notches, and by creating cracks in these cuts and notches, the drawing force is dispersed. While this manufacturing method provides paper boxes for disc-shaped optical discs such as CDs and DVDs, various patterns can be used when forming the cuts and notches, which are key points. In plastic containers used as storage boxes for other electronic devices, the range of paper box alternatives is further expanded when the same protrusion can be formed to create the storage portion. Furthermore, if a plastic box has a portion that functions as a retaining part in the same shape, such as a cosmetic box or a grocery box, the manufacturing method of this invention can also provide a paper storage box as an alternative.

[0066] Explanation of reference numerals in the attached figures

[0067] 1. Paper substrate

[0068] 2. Cylindrical retaining protrusion

[0069] 2B base

[0070] 2C Circumference

[0071] 2L teardrop-shaped notch

[0072] 2LH Crack

[0073] 3L Discontinuous first arc-shaped incision

[0074] 3LH Crack

[0075] 4L Discontinuous second arc-shaped incision

[0076] 4LH Crack

[0077] 5. Step section

[0078] 6. Recessed area

[0079] O is the center point.

Claims

1. A method for manufacturing a paper CD case, wherein a cylindrical retaining protrusion for inserting / removing a CD disc into a circular hole is formed in the center of a square planar paper substrate by deep drawing, the method being characterized in that: On the outer periphery of a narrow area in the center of the paper substrate where a deep drawing process is performed to form a cylindrical retaining protrusion, a discontinuous first arc-shaped cut is formed. Viewed from the center point of this narrow area, this discontinuous first arc-shaped cut does not intersect with either the parallel or orthogonal directions of the paper grain. A discontinuous second arc-shaped cut is formed around the outer periphery of the discontinuous first arc-shaped cut. Viewed from the center point, this discontinuous second arc-shaped cut intersects with both the parallel and orthogonal directions of the paper grain of the paper substrate. Furthermore, viewed from the center point, the radial directions of this discontinuous second arc-shaped cut do not intersect at the central portions of the discontinuous first arc-shaped cut. After forming these discontinuous first arc-shaped cuts and discontinuous second arc-shaped cuts, a deep drawing process is performed on a narrow area in the center of the paper substrate to form a cylindrical retaining protrusion that can be inserted / pulled out of the circular hole of the optical disc.

2. A method for manufacturing a paper CD case, wherein a cylindrical retaining protrusion for inserting / removing a CD disc into a circular hole is formed in the center of a square planar paper substrate by deep drawing, the method being characterized in that: On the outer periphery of the narrow circular area in the center of the paper substrate where a deep drawing process is performed to form a cylindrical retaining protrusion, a discontinuous first arc-shaped cut is formed. Viewed from the center point of this narrow area, this discontinuous first arc-shaped cut does not intersect with the parallel or orthogonal directions of the paper grain. A discontinuous second arc-shaped cut is formed around the outer periphery of the discontinuous first arc-shaped cut. Viewed from the center point, this discontinuous second arc-shaped cut intersects with both the parallel and orthogonal directions of the paper grain of the paper substrate. Furthermore, viewed from the center point, the radial directions of this discontinuous second arc-shaped cut do not intersect at the central portions of the discontinuous first arc-shaped cut. Starting from the circumference of the narrow circular area where the cylindrical retaining protrusion is formed, which becomes the base of the cylinder after forming, and ending at the circumference of the upper plane of the cylinder after forming, multiple teardrop-shaped notches are formed at equal intervals along the circumference. These teardrop-shaped notches are thinner at the front end and slightly wider at the rear end in the direction towards the center of the narrow area. After forming the discontinuous first arc-shaped cut, the discontinuous second arc-shaped cut, and the teardrop-shaped notch, a deep drawing process is performed on a narrow area in the center of the paper substrate to form a cylindrical retaining protrusion that can be inserted into / pulled out of the circular hole of the optical disc.

3. The method for manufacturing a paper optical disc case according to claim 1, characterized in that: The paper substrate is 5cm square or larger and 0.4 to 1.0mm thick. When the cylindrical holding protrusion in the narrow area of ​​the central part of the paper substrate where the deep drawing process is performed is set to have a diameter of 15mm or less and a height of 3 to 4mm, the discontinuous first arc-shaped cut is formed at a position 6mm away from the deep drawing position of the base of the cylindrical holding protrusion, and the discontinuous second arc-shaped cut is formed at a position 8mm away from the deep drawing position of the base of the cylindrical holding protrusion.

4. The method for manufacturing a paper optical disc case according to claim 2, characterized in that: The paper substrate is 5cm square or larger and 0.4 to 1.0mm thick. When the cylindrical holding protrusion in the narrow area of ​​the central part of the paper substrate where the deep drawing process is performed is set to have a diameter of 15mm or less and a height of 3 to 4mm, the discontinuous first arc-shaped cut is formed at a position 6mm away from the deep drawing position of the base of the cylindrical holding protrusion, and the discontinuous second arc-shaped cut is formed at a position 8mm away from the deep drawing position of the base of the cylindrical holding protrusion. The length of the teardrop-shaped notch is 6.2mm.

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