Molds, tape reels, and tape cartridges

Abstract

To provide a metal mold which can form a cylindrical part of a tape reel into a shape close to a perfect circle, a tape reel whose cylindrical part is formed into a shape close to a perfect circle, and a tape cartridge including a tape reel whose cylindrical part is formed into a shape close to a perfect circle.SOLUTION: A metal mold for forming a tape reel of a resin including: a cylindrical part; a bottom part formed at a base end side of the cylindrical part; and a plurality of through holes penetrating through the bottom part and arrayed in a circumferential direction of the cylindrical part has: a bottom surface which forms the bottom part; a cylindrical surface which forms the cylindrical part; and a plurality of convex parts which respectively form a plurality of through holes projected from the bottom surface, in which the cylindrical surface has a first portion corresponding to a gap between the convex parts of the plurality of convex parts adjacent in the circumferential direction has a shape bulging more outward in the radius direction of the bottom surface than a second portion corresponding to the convex part.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The technology of the present disclosure relates to a mold, a tape reel, and a tape cartridge. [Background technology]

[0002] Patent Document 1 discloses a reel having a cylindrical hub molded from a resin material and having a bottom with an open upper end, a lower flange integrally molded with the hub on the lower end side of the hub, an annular upper flange facing the lower flange, and a welded portion joining the lower surface of the upper flange to the upper end surface of the hub.

[0003] Patent Document 2 discloses a manufacturing method for manufacturing a reel of a recording tape cartridge using a mold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-15191 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-64480 Summary of the Invention

[0005] One embodiment of the technology disclosed herein provides a mold capable of forming the cylindrical portion of a tape reel into a shape that is close to a perfect circle, a tape reel whose cylindrical portion is shaped like a perfect circle, and a tape cartridge equipped with a tape reel whose cylindrical portion is shaped like a perfect circle. [Means for solving the problem]

[0006] A first aspect of the technology disclosed herein is a mold for molding a resin tape reel having a cylindrical portion, a bottom portion formed on the base end side of the cylindrical portion, and a plurality of through holes that penetrate the bottom portion and are arranged circumferentially of the cylindrical portion, the mold having a bottom surface that forms the bottom portion, a cylindrical surface that forms the cylindrical portion, and a plurality of protrusions that protrude from the bottom surface and each form a plurality of through holes, and the cylindrical surface has a shape in which a first portion corresponding to a space between circumferentially adjacent protrusions among the plurality of protrusions is bulged radially outward from the bottom surface more than a second portion corresponding to the protrusions.

[0007] A second aspect of the technique of the present disclosure is the mold according to the first aspect, in which the first portion is a portion corresponding to a central portion between adjacent protrusions.

[0008] A third aspect according to the technique of the present disclosure is the mold according to the first or second aspect, in which the cylindrical surface has a shape that widens radially outward as it moves away from the bottom surface.

[0009] A fourth aspect of the technique of the present disclosure is the mold according to any one of the first to third aspects, in which the plurality of protrusions are arranged at equal intervals in the circumferential direction.

[0010] A fifth aspect of the technique of the present disclosure is the mold according to any one of the first to fourth aspects, in which the number of the plurality of protrusions is three.

[0011] A sixth aspect of the technology of the present disclosure is a resin tape reel molded using a mold of any one of the first to fifth aspects, the tape reel comprising a cylindrical portion, a bottom portion at one axial end of the cylindrical portion, and a plurality of through holes formed around the circumference of the cylindrical portion, the tape reel having a roundness of 20 μm or less at the base end of the cylindrical portion.

[0012] A seventh aspect of the technique of the present disclosure is a tape cartridge having the tape reel of the sixth aspect and a case that rotatably supports the tape reel and houses the tape reel and the tape wound around the tape reel. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view showing a tape cartridge equipped with a tape reel according to a first embodiment. FIG. [Figure 2] 1 is an exploded perspective view showing a tape cartridge including a tape reel according to a first embodiment, as viewed from above. [Figure 3] 1 is an exploded perspective view showing a tape cartridge including a tape reel according to a first embodiment, as viewed from below. FIG. [Figure 4] 1 is a perspective view showing a tape reel according to a first embodiment, with a partially enlarged cross section; [Figure 5] FIG. 2 is a partially enlarged plan view of the tape reel according to the first embodiment. [Figure 6] FIG. 2 is a vertical cross-sectional view showing a mold used in manufacturing the tape reel according to the first embodiment. [Figure 7] 7 is a cross-sectional view taken along line 7-7 of FIG. 6, showing a mold used in manufacturing the tape reel according to the first embodiment. [Figure 8] 8 is a cross-sectional view taken along line 8-8 of FIG. 6, showing a mold used in manufacturing the tape reel according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] An example of an embodiment of the technology of the present disclosure will be described with reference to the accompanying drawings.

[0015] As shown in FIG. 1, the tape cartridge 10 has a case 12. One tape reel 20 is housed in the case 12. A recording tape T is wound around the tape reel 20. Details of the case 12 and the tape reel 20 will be described later. The case 12 is an example of a "case" according to the technology of the present disclosure. The tape reel 20 is an example of a "tape reel" according to the technology of the present disclosure. The tape cartridge 10 is an example of a "tape cartridge" according to the technology of the present disclosure.

[0016] The tape cartridge 10 is inserted into a drive device (not shown). In the drive device, the recording tape T is unwound from the tape cartridge 10, and information is written to and read from the recording tape T.

[0017] In the drawings, the loading direction of the tape cartridge 10 into the drive device is indicated by arrow A. The direction indicated by arrow A is the forward direction of the tape cartridge 10. The direction indicated by arrow B, which is perpendicular to arrow A, is the rightward direction of the tape cartridge 10, and the direction indicated by arrow C, which is perpendicular to arrows A and B, is the upward direction of the tape cartridge 10 and the tape reel 20. In the following, the radial and circumferential directions of the tape reel 20 may be simply referred to as the "radial direction" and the "circumferential direction." The above-mentioned forward, rightward, and upward directions are defined for convenience and do not limit the orientation of the tape cartridge according to the technology of the present disclosure.

[0018] As shown in Figures 1 to 3, the case 12 is formed in the shape of a flat rectangular box. The case 12 has an upper case 14 and a lower case 16. A peripheral wall 14B is provided on the periphery of a top plate 14A of the upper case 14, and a peripheral wall 16B is provided on the periphery of a bottom plate 16A of the lower case 16. With the lower end of the peripheral wall 14B and the upper end of the peripheral wall 16B in contact with each other, the upper case 14 and the lower case 16 are joined by ultrasonic welding and / or screw fastening, for example. The upper case 14 and the lower case 16 are made of resin, such as polycarbonate (PC), for example.

[0019] 2 and 3, screw bosses 15 are formed near the corners of the upper case 14 and the lower case 16. Screws (not shown) are threaded into the screw bosses 15 from the underside of the lower case 16, joining the upper case 14 and the lower case 16 to assemble the case 12. A resin tape reel 20 is rotatably housed inside the case 12.

[0020] The tape reel 20 has a hub 22, an upper flange 24, and a lower flange 26. The hub 22 is an example of a "cylindrical portion" according to the technology of the present disclosure. The hub 22 is formed into a cylindrical shape with an open upper end and a closed bottom. The upper flange 24 is formed into an annular shape, and the lower flange 26 is also formed into an annular shape. The upper flange 24 and the lower flange 26 face each other.

[0021] In this embodiment, the upper flange 24 is ultrasonically welded to the upper end of the hub 22. In contrast, the lower flange 26 is molded integrally with the hub 22 at the lower end of the hub 22. In other words, the hub 22 and the lower flange 26 constitute a hub member 100 with a lower flange.

[0022] Recording tape T is wound around the outer peripheral surface of hub 22. Recording tape T is an example of a magnetic tape or the like as an information recording and reproducing medium. The positions of both widthwise ends of the wound recording tape T are regulated by an upper flange 24 and a lower flange 26 that face each other in parallel.

[0023] The hub 22 has a bottom wall 28 formed on one axial end side of the hub 22, specifically the base end side. The bottom wall 28 is an example of a "bottom" according to the technology of the present disclosure. The bottom wall 28 is perpendicular to the hub 22. A reel gear 44 is formed in an annular shape on the lower surface (outer surface) of the bottom wall 28.

[0024] A gear opening 40 is formed in the center of the lower case 16 to expose the reel gear 44 to the outside of the case 12. The reel gear 44 exposed from the gear opening 40 is meshed with a drive gear (not shown) formed on a rotating shaft (not shown) of the drive device. The reel gear 44 is then driven to rotate by the drive gear, causing the tape reel 20 to rotate relative to the case 12 within the case 12.

[0025] A reel plate 46 is fixed to the underside of the bottom wall 28, radially inward of the reel gear 44. The reel plate 46 is a disk-shaped metal plate made of a magnetic material. The reel plate 46 is fixed coaxially and integrally with the hub 22, for example, by insert molding. The reel plate 46 is attracted and held by the magnetic force of an annular magnet (not shown) provided on the rotating shaft of the drive device.

[0026] A plurality of play restriction walls 42 are provided partially on the inner surfaces of the upper case 14 and the lower case 16. Each play restriction wall 42 is formed in an arc shape that is concentric with the gear opening 40. By being surrounded by the plurality of play restriction walls 42, the tape reel 20 is held in place so as not to rattle in the radial direction.

[0027] An opening 18 is formed in the right wall of the case 12. The recording tape T wound around the tape reel 20 can be pulled out through the opening 18.

[0028] A leader pin 30 is fixed to the free end of the recording tape T that is pulled out from the opening 18. The leader pin 30 is engaged with a pull-out member (not shown) of the drive device and is operated to pull out the tape. Both ends of the leader pin 30 protrude beyond the width direction ends of the recording tape T. An annular groove 32 is formed at each end of the leader pin 30. The annular groove 32 is engaged with a hook or the like of the pull-out member of the drive device.

[0029] A pair of pin holding portions 36 are provided inside the opening 18 of the case 12. In the example shown in Fig. 2, each pin holding portion 36 is provided facing the inner surface of the top plate 14A of the upper case 14 and the inner surface of the bottom plate 16A of the lower case 16. The pin holding portions 36 position and hold the leader pin 30 inside the case 12. The pin holding portion 36 has a generally semicircular shape that is open on the side from which the recording tape T is pulled out. Both ends 34 of the leader pin 30 can enter and exit the pin holding portion 36 from the open side of the pin holding portion 36.

[0030] A leaf spring 38 is fixed inside the case 12. The leaf spring 38 is disposed inside the case 12 relative to the pin holding portion 36. The leaf spring 38 has a bifurcated tip. Each tip of the leaf spring 38 engages with both upper and lower ends 34 of the leader pin 30, thereby holding the leader pin 30 in the pin holding portion 36. When the leader pin 30 moves in and out of the pin holding portion 36, each tip of the leaf spring 38 elastically deforms appropriately, allowing the leader pin 30 to move.

[0031] The case 12 is provided with a door 50. The door 50 is formed in the shape of a rectangular plate large enough to close the opening 18. Grooves 64 are formed in the top plate 14A and bottom plate 16A inside the opening 18. The upper and lower ends of the door 50 are slidably fitted into the grooves 64, respectively. This allows the door 50 to move along the right wall of the case 12 to open and close the opening 18.

[0032] A shaft 52 protrudes from the rear end of the door 50. A coil spring 58 is inserted into the shaft 52. An expanded portion 54 is formed at the rear end of the shaft 52. The expanded portion 54 prevents the coil spring 58 from falling off the shaft 52. A support base 60 having a locking portion 62 protrudes from the lower case 16. The rear end of the coil spring 58 inserted into the shaft 52 is locked to the locking portion 62.

[0033] The shaft 52 is slidably supported on a support base 60, and the rear end of the coil spring 58 is engaged with an engaging portion 62. As a result, the door 50 is constantly urged in the direction of closing the opening 18 by the urging force of the coil spring 58.

[0034] A protrusion 56 protrudes outward from the front end of the door 50. When the tape cartridge 10 is inserted into the drive device, the protrusion 56 engages with an opening / closing member (not shown) on the drive device side. The opening / closing member on the drive device applies a force to the protrusion 56 toward the opening side of the door 50, causing the door 50 to open against the biasing force of the coil spring 58.

[0035] A write protector 70 is provided on the left rear portion of the case 12. The write protector 70 is slidable in the left and right directions.

[0036] The write protector 70 is a member that sets whether recording is "allowed" or "not allowed" on the recording tape T. The write protector 70 is formed with an operating protrusion 72 for manually sliding the write protector 70 left and right.

[0037] An opening 68 is formed in the rear wall of the case 12. The operating protrusion 72 protrudes from the opening 68 to the outside of the case 12. In the example shown in Figures 2 and 3, a notch 68A is formed in the peripheral wall 14B of the upper case 14, and a notch 68B is formed in the peripheral wall 16B of the lower case 16. When the upper case 14 and the lower case 16 are joined together, the opening 68 is formed by the notch 68A and the notch 68B.

[0038] A protrusion 74 is formed on the write protect 70. A long hole 69 is formed in the lower case 16. The longitudinal direction of the long hole 69 coincides with the left-right direction of the case 12. The protrusion 74 is exposed to the outside of the case 12 from the long hole 69. When the tape cartridge 10 is loaded in the drive device, the position of the protrusion 74 is detected on the drive device side to determine whether recording onto the recording tape T is "possible" or "not possible."

[0039] A plurality of engagement gears 48 are provided on the periphery of the upper surface of the bottom wall 28 of the hub 22. The plurality of engagement gears 48 are provided at intervals (for example, at equal intervals) in the circumferential direction of the hub 22. A plurality of through holes 29 are formed between the plurality of engagement gears 48 and at positions above the reel gear 44. In the example shown in FIGS. 2 and 5, the number of the plurality of engagement gears 48 is three. The three engagement gears 48 are arranged at intervals of 120 degrees in the circumferential direction of the hub 22. The number of the plurality of through holes 29 is also three. The three through holes 29 are also arranged at intervals of 120 degrees in the circumferential direction of the hub 22. The through holes 29 are an example of a "through hole" according to the technology of the present disclosure.

[0040] A braking member 80 is disposed inside the hub 22. The braking member 80 is, for example, a disk-shaped member molded from a resin material. The cylindrical cavity of the hub 22 is a space capable of accommodating a braking mechanism including the braking member 80. Furthermore, the hole 25A of the upper flange 24 is a hole through which the braking mechanism can pass and operate.

[0041] An annular brake gear 84 is formed on the periphery of the lower surface 80A of the brake member 80. The brake gear 84 is capable of meshing with the engagement gear 48.

[0042] A rotation-restricting rib 76 protrudes downward from the inner surface of the top plate 14A of the upper case 14. The rotation-restricting rib 76 has a cross shape in a plan view. An engagement protrusion 86, which also has a cross shape in a plan view, protrudes from the upper surface of the braking member 80. The height of the engagement protrusion 86 is greater than the height of the rotation-restricting rib 76. When the rotation-restricting rib 76 is inserted inside the engagement protrusion 86, the braking member 80 becomes unable to rotate relative to the case 12 (specifically, the upper case 14), and becomes movable up and down within the hub 22.

[0043] A compression coil spring 98 is disposed between the upper case 14 and the braking member 80. The braking member 80 is urged downward by the urging force of the compression coil spring 98. As shown in FIG. 3, an annular protrusion 78 protrudes from the outer side of the rotation-restricting rib 76 of the upper case 14. One end of the compression coil spring 98 is located inside the annular protrusion 78 (specifically, between the rotation-restricting rib 76 and the annular protrusion 78). In addition, as shown in FIG. 2, an annular groove 88 is formed in the upper surface of the braking member 80. The other end of the compression coil spring 98 is located within the annular groove 88.

[0044] When the tape cartridge 10 is not in use (i.e., not loaded in a drive device), the brake gear 84 meshes with the engagement gear 48. Because the brake gear 84 meshes with the engagement gear 48, the tape reel 20 is prevented from rotating relative to the case 12. The tape reel 20 is then pushed toward the lower case 16 by the biasing force of the compression coil spring 98, exposing the reel gear 44 from the gear opening 40.

[0045] A release member 90 is disposed inside the hub 22. The release member 90 is located below the braking member 80 (specifically, between the bottom wall 28 and the braking member 80). The release member 90 is a member molded from a resin material and shaped like an equilateral triangle in a plan view. A plurality of through holes 92 are formed in the release member 90, which contributes to reducing the weight of the release member 90.

[0046] A plurality of legs 94 protrude from the underside of the release member 90. In the example shown in Figures 2 and 3, the legs 94 are provided at each vertex of the release member 90. The legs 94 are inserted into the through holes 29 and protrude above the reel gear 44 from the underside of the bottom wall 28.

[0047] As shown in Figure 2, a support protrusion 96 is formed in the center of the upper surface of the release member 90. As shown in Figure 3, a hemispherical release projection 82 is provided in the center of the lower surface 80A of the brake member 80. The release projection 82 is in contact with the support protrusion 96. This reduces the contact area between the brake member 80 and the release member 90, thereby reducing sliding resistance when in use (i.e., when the tape reel 20 is rotating). The brake member 80 can be made of, for example, polyacetal (POM). The release member 90 can be made of, for example, polybutylene terephthalate (PBT).

[0048] 4, a short cylindrical portion 25 is provided on the inner peripheral side (specifically, the inner peripheral edge) of the upper flange 24. The short cylindrical portion 25 is inserted into the inside of the hub 22 so as to fit along the inner peripheral surface of the hub 22.

[0049] As also shown in FIG. 5, a plurality of restriction ribs 22C extending in the vertical direction are formed on the inner peripheral surface of the hub 22. The plurality of restriction ribs 22C are formed at equal intervals in the circumferential direction. When the braking member 80 moves up and down inside the hub 22, the radial position of the braking member 80 is restricted from the outside. In addition, a plurality of protrusions 22D are formed on the inner peripheral surface of the hub 22. Each protrusion 22D extends in the vertical direction separately from each restriction rib 22C. The number of protrusions 22D is, for example, six. The plurality of protrusions 22D are formed at equal intervals in the circumferential direction.

[0050] Next, a method for molding the lower flanged hub member 100 will be described.

[0051] The lower flanged hub member 100 is formed by injection molding using a mold 200 shown in Figures 6 to 8. The mold 200 is an example of the "mold" according to the technology of the present disclosure.

[0052] 6, the mold 200 has a fixed-side mold plate 202 and a movable-side mold plate 204. A cavity 206 is formed between the fixed-side mold plate 202 and the movable-side mold plate 204. The cavity 206 is filled with a resin material to form the hub member 100 with a lower flange.

[0053] The mold 200 is made of steel or the like, and has a hub forming portion 222 for forming the hub 22, a flange forming portion 224 for forming the lower flange 26, and a bottom wall forming portion 226 for forming the bottom wall 28. The mold 200 is made of steel, for example.

[0054] One or more gates 210 are formed in the fixed side mold plate 202. The gates 210 are the entrances for the resin into the cavity 206.

[0055] A reel plate 46 is set in the cavity 206. Resin material injected from a molding machine (not shown) passes through a flow path 208 formed in the fixed side mold plate 202 and is poured into the cavity 206 through a gate 210. The resin is then cooled and solidified in the cavity 206. After the resin material has solidified, the mold 200 is opened and the hub member 100 with a lower flange is released from the mold 200. This completes the formation of the hub member 100 with a lower flange.

[0056] The mold 200 has a bottom surface 212 and a cylindrical surface 214. The bottom surface 212 forms part of the bottom wall forming portion 226, and is the surface that forms the bottom wall 28 of the hub member 100 with a lower flange. The bottom surface 212 is an example of a "bottom surface" according to the technology of the present disclosure. The cylindrical surface 214 is the surface that forms the hub 22 of the hub member 100 with a lower flange. The cylindrical surface 214 is an example of a "cylindrical surface" according to the technology of the present disclosure.

[0057] Furthermore, the mold 200 has a plurality of protrusions 216 that form the plurality of through holes 29, respectively. The number of the protrusions 216 is the same as the number of through holes 29. In this embodiment, the plurality of through holes 29 are provided in three, spaced equally apart in the circumferential direction of the hub 22 (specifically, at intervals of 120 degrees), and therefore the plurality of protrusions 216 are also arranged in three, spaced equally apart in the circumferential direction (specifically, at intervals of 120 degrees). The protrusions 216 are an example of a "protrusion" according to the technology of the present disclosure.

[0058] 6, a corrosion-resistant coating CT is applied to the cylindrical surface 214. Even if corrosive gas is generated from the molten resin material during molding in the mold 60, corrosion of the cylindrical surface 214 over time is suppressed compared to when the corrosion-resistant coating CT is not applied. The mold of the technology disclosed in the present application may have a structure in which the corrosion-resistant coating CT is not applied to the cylindrical surface 214.

[0059] Figure 7 shows the mold 200 in a cross section taken along line 7-7 in Figure 6. Figure 8 shows the mold 200 in a cross section taken along line 8-8 in Figure 6. The position of the cross section taken along line 8-8 is farther from the bottom surface 212 than the position of the cross section taken along line 7-7.

[0060] As shown in Fig. 7, the portion of the cylindrical surface 214 located between the circumferentially adjacent protrusions 216 is the first portion 218. In this embodiment, in particular, the portion corresponding to the center between the circumferentially adjacent protrusions 216 (i.e., the portion located in the center) is the first portion 218. The first portion 218 is an example of the "first portion" according to the technology of the present disclosure. In contrast, the portion corresponding to the protrusion 216 is the second portion 220. The second portion 220 is an example of the "second portion" according to the technology of the present disclosure.

[0061] The first portion 218 has a shape that bulges outward in the radial direction of the bottom surface 212 more than the second portion 220. Specifically, as shown in FIG. 7 , a circle CL is assumed whose radius is the distance from the center CC of the bottom surface 212 to the second portion 220. In the second portion 220, the cylindrical surface 214 is on the circle CL. The distance from the center CC of the cylindrical surface 214 increases from the second portion 220 to the first portion 218. In the first portion 218, the distance from the center CC to the second portion 220 is the longest.

[0062] 6 and 8, the cylindrical surface 214 has a shape that widens radially outward as it moves away from the bottom surface 212. Here, in FIG. 6, the two-dot chain line indicates a case in which the cylindrical surface 214 does not widen radially outward but extends in a direction away from the bottom surface 212 at a constant radius. Compared to the shape indicated by the two-dot chain line, it can be seen that the cylindrical surface 214 widens radially outward as it moves away from the bottom surface 212. In other words, the cylindrical surface 214 has a shape that widens radially outward around the entire circumference as it moves upward in FIG. 6. The circumferential length of the cylindrical surface 214 shown in FIG. 8 is longer than the circumferential length of the cylindrical surface 214 shown in FIG. 7. In Figures 6 to 8, in order to clarify the above-mentioned shape of the mold 200, the fact that the first portion 218 bulges radially outward more than the second portion 220 and that the cylindrical surface 214 widens radially outward as it moves away from the bottom surface 212 are emphasized, compared to the actual shape of the mold.

[0063] By performing resin injection molding using the above-described mold 200, the hub member 100 with a lower flange having a lower flange 26 is formed (that is, manufactured).

[0064] Next, the operation of this embodiment will be described.

[0065] The hub member 100 with a lower flange of this embodiment is formed by injection molding using a mold 200. In injection molding, resin is injected into a cavity 206 of the mold 200, and the injected resin shrinks as it cools and solidifies.

[0066] The mold 200 has a cylindrical surface 214 that forms the hub 22. A first portion 218 of the cylindrical surface 214 has a shape that bulges outward in the radial direction from the bottom surface 212 more than the second portion 220. Therefore, the shape of the hub 22 before contraction in the cavity 206 is such that the portion in contact with the first portion 218 bulges outward in the radial direction more than the portion in contact with the second portion 220.

[0067] When the resin in cavity 206 contracts as it cools and solidifies, the convex portions 216 suppress the contraction of the resin around second portion 220. In contrast, the convex portions 216 are not present around first portion 218, and therefore the force of convex portions 216 in suppressing the contraction of the resin is weaker than around second portion 220. In other words, the shape of the molded hub 22, i.e., the shape of hub 22 after contraction, causes the degree of contraction of the resin to be greater around first portion 218 than around second portion 220.

[0068] As described above, the first portion 218 of the cylindrical surface 214 has a shape that bulges outward in the radial direction of the bottom surface 212 more than the second portion 220. Therefore, in the molded hub 22, the portion corresponding to the first portion 218 shrinks more than the portion corresponding to the second portion 220. As a result, the cross-sectional shape of the hub 22 after shrinkage becomes closer to a perfect circle compared to when a mold is used in which the first portion 218 does not bulge outward relative to the second portion 220.

[0069] In particular, the first portion 218 of the cylindrical surface 214 is located in the center between adjacent protrusions 216. Even if the first portion 218 of the cylindrical surface 214 is located circumferentially away from the center between adjacent protrusions 216, it is possible to form a hub 22 that is nearly perfectly circular, compared to a mold that has a cylindrical surface that does not have the first portion 218, i.e., a portion that bulges outward in the radial direction.

[0070] In contrast, in this embodiment, the first portion 218 is located in the center between adjacent protrusions 216. Therefore, the hub 22 can be formed into a shape that is closer to a perfect circle than when using a mold with a cylindrical surface that does not have a portion that bulges outward in the radial direction at the center between adjacent protrusions 216.

[0071] Moreover, cylindrical surface 214 has a shape that widens radially outward as it moves away from bottom surface 212. The circumferential length of cylindrical surface 214 at the position of the cross section shown in Figure 8 is longer than the circumferential length of cylindrical surface 214 at the position shown in Figure 7.

[0072] When the resin injected into the cavity 206 of the mold 200 shrinks, the resin is less likely to shrink on the bottom surface 212 side because of the presence of the convex portion 216 of the mold 200 compared to when a mold without the convex portion 216 is used. However, the degree of shrinkage increases with increasing distance from the bottom surface 212 compared to the bottom surface 212 side. In this embodiment, the cylindrical surface 214 has a shape that widens radially outward with increasing distance from the bottom surface 212. Therefore, by shrinking the side of the hub 22 away from the bottom surface 212, deviation from a perfect circle can be suppressed even on the side away from the bottom surface 212 compared to the bottom surface 212 side, and a hub 22 with a shape that is close to a perfect circle can be obtained.

[0073] In this embodiment, the multiple protrusions 216 are arranged at equal intervals in the circumferential direction of the cylindrical surface 214. The multiple first portions 218 on the cylindrical surface 214 of the mold 200 are also arranged at equal intervals in the circumferential direction. Therefore, it is possible to equalize shrinkage in the circumferential direction when molding the hub 22. Furthermore, the multiple second portions 220 on the cylindrical surface of the mold 200 are also arranged at equal intervals in the circumferential direction. Therefore, it is possible to equalize shrinkage in the circumferential direction when molding the hub 22, compared to when using a mold configured so that the multiple second portions 220 are not formed at equal intervals in the circumferential direction.

[0074] In this embodiment, three through holes 29 are formed in the bottom wall 28 of the hub 22. The mold 200 has three protrusions 216 formed therein corresponding to the through holes 29, and is therefore suitable for forming a hub 22 having three through holes 29 in the bottom wall 28.

[0075] In this embodiment, a tape reel 20 is obtained in which the roundness of the hub 22 is 20 μm or less. This roundness is defined as (Dmax-Dmin) / 2, where Dmax is the maximum diameter of the hub 22 and Dmin is the minimum diameter. The roundness of the hub 22 according to this embodiment satisfies the above-mentioned roundness conditions at both the base end and the tip end.

[0076] In the tape reel 20 according to this embodiment, the tape T is wound around the hub 22. Then, in the drive device, the recording tape T is unwound from the tape cartridge 10. In this case, by having the roundness of the hub 22 be 20 μm or less, fluctuations in the feed speed of the recording tape T are suppressed compared to a configuration in which the roundness exceeds 20 μm, and it is possible to make the feed speed closer to a constant speed. Furthermore, by having the roundness of the hub 22 be 20 μm or less, fluctuations in the feed speed of the recording tape T are suppressed compared to a configuration in which the roundness exceeds 20 μm, and errors in reading and writing information from and to the recording tape T can also be suppressed. Note that, when the base end of the hub 22 satisfies the above-mentioned roundness conditions, the effect of suppressing the feed speed of the recording tape T and the effect of suppressing errors in reading and writing information from and to the recording tape T can be obtained compared to a configuration in which the roundness of the base end exceeds 20 μm. Similarly, even when the above-mentioned circularity conditions are met at the tip of the hub 22, the effect of suppressing the conveying speed of the recording tape T and the effect of suppressing errors in reading and writing information to the recording tape T can be achieved compared to a configuration in which the circularity of the tip exceeds 20 μm.

[0077] To actually determine the shape of the mold 200, the following method can be used as an example.

[0078] That is, first, a hub member with a lower flange is formed using a mold in which the second portion 220 does not bulge outward in the radial direction.

[0079] The shape of the formed hub member with a lower flange is then measured, and the mold shape is modified based on the measurement results. The modified mold is then used to form the hub member with a lower flange again. By performing this process multiple times to modify the mold shape, it is possible to make the hub shape of the formed hub member with a lower flange closer to a perfect circle compared to when the mold shape is not modified. Therefore, no lower limit for circularity is specified for the hub 22 according to the technology disclosed herein.

[0080] The material of the lower flange-equipped hub member 100 according to the technology of the present disclosure is not particularly limited as long as it is resin. From the viewpoint of satisfying the strength and durability required of the tape reel 20, for example, glass fiber reinforced polycarbonate is preferable. The glass fiber content in the glass fiber reinforced polycarbonate is, for example, 10% or more and 30% or less.

[0081] In the description of this specification, "parallel" refers to parallelism in the sense of including a tolerance that is generally accepted in the technical field to which the technology of the present disclosure belongs, in addition to completely parallelism. In the description of this specification, "perpendicular" refers to perpendicularity in the sense of including a tolerance that is generally accepted in the technical field to which the technology of the present disclosure belongs, in addition to completely perpendicularity. In the description of this specification, "equally spaced" refers to equidistant spacing in the sense of including a tolerance that is generally accepted in the technical field to which the technology of the present disclosure belongs, in addition to completely equal spacing. In the description of this specification, "matched" refers to matching in the sense of including a tolerance that is generally accepted in the technical field to which the technology of the present disclosure belongs, in addition to completely equal spacing.

[0082] The above-described description and illustrations are a detailed explanation of the parts related to the technology of the present disclosure and are merely an example of the technology of the present disclosure. For example, the above description of the configuration, functions, actions, and effects is an explanation of an example of the configuration, functions, actions, and effects of the parts related to the technology of the present disclosure. Therefore, it goes without saying that unnecessary parts may be deleted, new elements may be added, or replacements may be made to the above-described description and illustrations within the scope of the gist of the technology of the present disclosure. Furthermore, to avoid confusion and facilitate understanding of the parts related to the technology of the present disclosure, the above-described description and illustrations omit explanations of common technical knowledge that do not require particular explanation to enable the implementation of the technology of the present disclosure.

[0083] In this specification, "A and / or B" is synonymous with "at least one of A and B." In other words, "A and / or B" means that it may be only A, only B, or a combination of A and B. Furthermore, in this specification, the same concept as "A and / or B" is also applied when three or more things are expressed connected by "and / or."

[0084] All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference. [Explanation of symbols]

[0085] 10 Tape Cartridge 12 cases 14 Upper case 16 Lower case 20 tape reels 22 Hub (an example of a cylindrical part) 28 Bottom wall (example of bottom) 100 Lower flanged hub member 200 molds 212 bottom 214 Cylindrical surface 216 Convex 218 Part 1 220 Part 2

Claims

1. A mold for molding a resin tape reel, the mold comprising: a cylindrical portion; a bottom portion formed on a base end side of the cylindrical portion; and a plurality of through holes that pass through the bottom portion and are arranged in a circumferential direction of the cylindrical portion, a bottom surface forming the bottom; a cylindrical surface forming the cylindrical portion; a plurality of protrusions protruding from the bottom surface and forming the plurality of through holes, respectively; and The cylindrical surface has a shape in which a first portion corresponding to a space between adjacent ones of the plurality of protrusions in the circumferential direction bulges outward in the radial direction of the bottom surface more than a second portion corresponding to the protrusion. Mold.

2. The first portion corresponds to a central portion between adjacent protrusions. The mold according to claim 1 .

3. The cylindrical surface has a shape that widens outward in the radial direction as it moves away from the bottom surface. The mold according to claim 1 or claim 2.

4. The plurality of protrusions are arranged at equal intervals in the circumferential direction. The mold according to any one of claims 1 to 3.

5. The number of the plurality of protrusions is three. The mold according to any one of claims 1 to 4.

6. A resin tape reel comprising a cylindrical portion, a bottom portion at one axial end of the cylindrical portion, and a plurality of through holes penetrating the bottom portion and formed in a circumferential direction of the cylindrical portion, the tape reel being molded using the mold according to any one of claims 1 to 5, The circularity of the base end of the cylindrical portion is 20 μm or less. Tape reel.

7. The tape reel according to claim 6; a case that rotatably supports the tape reel and houses the tape reel and a tape wound around the tape reel; A tape cartridge having:

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