JP4841668B2 - Tape reel flange and its mold for tape cartridges - Google Patents

Description

  The present invention relates to a flange for a tape cartridge having a tape reel in which a tape-shaped medium is wound in a case body and a molding die thereof.

  2. Description of the Related Art Conventionally, a tape reel of a type comprising a hub for winding a tape and upper and lower flanges, one flange formed integrally with the hub and the other flange fixed to the hub has been widely known. Since the tape cartridge having such a tape reel is used for recording of a digital signal or the like of a computer or the like, the tape reel must have a high dimensional accuracy in order for the magnetic tape to show stable running.

  This type of tape reel is generally manufactured by injection molding of synthetic resin. Injection molding is performed by introducing a molten thermoplastic resin as a raw material into a molding cavity via a runner through a plurality of gates facing a cavity (molding space) of a molding die, and solidifying by cooling. Therefore, a gate mark is formed on the reel flange.

  In Patent Document 1 (Japanese Patent Laid-Open No. 11-53862) and Patent Document 2 (Japanese Patent Laid-Open No. 11-203825), in order to increase molding accuracy, the gate position of the flange and the flange are welded to the central hub. The positional relationship of the welding ribs has been studied.

  In Patent Document 1, in a reel including an upper flange integrally having a central hub for winding a tape and a lower flange having a low cylindrical portion fitted to a peripheral surface of a lower end portion of the hub, Gate traces are formed at equal intervals along the circumferential direction, and several fusion ribs fused by ultrasonic waves are formed on the upper surface of the lower flange contacting the lower end surface of the hub, and these gate traces and fusion ribs are formed. By arranging them symmetrically, the molding accuracy of the lower flange is improved.

  On the other hand, in Patent Document 2, in a reel comprising an upper flange integrally having a central hub for winding a tape and a lower flange having a low cylindrical portion that fits on the peripheral side surface of the lower end portion of the hub, Gate traces are formed at several locations on the inner circumferential side of the inner surface, and several fusion ribs are formed at equal intervals in the circumferential direction at the upper end of the lower flange that is in contact with the lower end surface of the hub. By arranging the gaps formed between the ribs so that they do not align with each other across the diameter, the molding accuracy of the lower flange is improved.

  As can be seen from the set position of the gate mark, these lower flanges are formed by injecting resin from a plurality of gates provided on the inner peripheral side surface. A highly accurate flange can be obtained by setting the arrangement relationship between the gate trace and the fusion rib as described above.

JP 11-53862 A JP-A-11-203825

However, even if it is possible to mold with high accuracy in this way, the molded product (flange) may be warped if the position and number of protruding pins are not set correctly when taking out the molded product (flange) from the mold. The problem of breakage occurs, leading to a decrease in productivity and a decrease in tape reel accuracy.

  Accordingly, it is an object of the present invention to solve such problems, avoid problems of warping and cracking of the flange, improve productivity, and improve accuracy.

  The present invention is a flange for constituting a tape reel in combination with another flange formed integrally with a hub for winding a tape, and has an opening in the center and the peripheral surface of the opening is the hub. In the flange configured to be fixed to the hub in a state of being covered with one end of the plurality of gates, a plurality of gate traces are formed at substantially equal intervals on the peripheral surface of the opening, and further on the flange surface near the opening. The tape reel flange is characterized in that protruding pin marks are formed only at positions corresponding to the gate marks. In particular, the gate marks are preferably 6 to 8 places.

  The present invention is also a flange for constituting a tape reel in combination with another flange formed integrally with a hub for winding a tape, and has an opening in the center and the peripheral surface of the opening In a mold for molding a flange configured to be fixed to the hub in a state of being covered with one end of the hub, the mold has a molding surface forming a molding space (cavity) for forming the flange. The first mold has a plurality of gates opened on the peripheral surface of the flange at substantially equal intervals, and the second mold projects the flange. There is provided a molding die for a tape reel, characterized in that a projecting pin for the purpose is provided only in the vicinity of each of the plurality of gates.

  According to the present invention, the flange can be molded with high accuracy, and the removal of the flange from the mold is also stabilized, so that productivity and product reliability are improved.

  As described above, according to the present invention, not only the trace of the gate is distributed almost uniformly on the peripheral surface of the opening, but also the protruding pin trace is provided close to the trace of the gate. We were able to provide a flange without any problems.

It is a disassembled perspective view of the tape cartridge which shows the Example of this invention. It is an expansion perspective view from the upper side of the tape reel of this invention, a bearing, and a plug. It is a perspective view from the back side of FIG. (A) is a top view of a flange, (b) is sectional drawing. It is sectional drawing of the metal mold | die for shape | molding a flange.

  FIG. 1 is an exploded perspective view showing a tape cartridge incorporating a tape reel according to an embodiment of the present invention.

One tape reel 3 is accommodated in the upper and lower cases 1 and 2. The tape reel 3 includes a hub 32 integrally formed with an upper flange 31 and a lower flange 33.
The lower surface side of the inside of the tape winding portion of the hub 32 is closed, and an engagement tooth 37 (FIG. 3) that engages with the drive portion of the apparatus through the opening 22 in the center of the lower case 2 is provided on the lower surface. The upper surface side is a concave portion 34 (FIGS. 1 and 2) that opens, and a cylindrical convex portion 35 into which the bearing 4 is fitted is formed inside.

  The plug 5 has a flange 54 (FIGS. 2 to 3), a first convex portion 51 (FIG. 3) fitted to the bear link 4 thereunder, and a second convex portion 55 (FIG. 2) into which the reel spring 6 is fitted. ).

  The reel spring 6 is a coil spring, one of which is fitted into the second convex portion 55 of the plug 5 and the other is fitted into a projection 12 provided at the center of the inner surface of the upper case 1 to constantly urge the tape reel 3 toward the lower case 2 side. Concavities and convexities 36 are formed on the outer periphery of the upper flange 31, and are engaged with reel brakes 8a and 8b provided at a pair of diagonal portions in the case and urged by spring members 8c to rotate the tape reel 3 when not in use. To prevent. The upper and lower cases 1 and 2 are formed with openings 11 and 21 for drawing the tape out of the case, and provided with a hook portion 9 for hooking the leading end of the tape in the vicinity of the opening. There is a door member 7a for opening and closing the openings 11 and 21. The door member 7a is biased in the closing direction by the spring member 7c, and is kept closed by the lid lock member 7b.

  2 and 3 are perspective views of the tape reel 3. 2 is a perspective view from an oblique upper side, and FIG. 3 is a perspective view from an oblique lower side. As can be seen from FIG. 2, welding ribs 33 b for welding and fixing the lower flange 33 to the hub 32 are formed at substantially equal intervals around the central opening 33 a of the lower flange 33. The opening 33 a is welded on a step 32 a around the engaging tooth 37 on the lower surface of the hub 32.

  4A and 4B show the lower flange 33, where FIG. 4A is a plan view and FIG. 4B is a cross-sectional view. Six gate traces 33c are provided at substantially equal intervals on the peripheral surface of the opening 33a. Here, “substantially equidistant” means that the angle viewed from the center of the flange is within plus or minus 5 degrees from the equiangular position, and within this range, there is no substantial difference in the effect intended by the present invention. . A protruding pin trace 33d for taking out the flange 33 from the mold 100 is formed on a radius passing through the gate trace 33c or close to the gate trace 33c. In any case, if the distance from the gate trace to the center of the protruding pin trace is within 10 mm, preferably within 5 mm, there is no difference in effect.

  In order to improve the moldability of the flange, it is a good means to increase the number of gates. However, as disclosed in Japanese Patent Application Laid-Open No. 11-203825, the resin injected from each gate hits between the gates to generate a weld line. However, the strength tends to decrease along the weld line.

  However, in the present invention, since the lower flange 33 protrudes only in the vicinity of the gate mark 33 c, the weld line is not protruded, and cracks and deformation do not occur when the lower flange 33 is removed from the mold 100. Four gate traces 33c are sufficient, but four protruding pins are insufficient. In order to take out this product, it is necessary to stick out at 6 or more places. However, it is not preferable to have four gates and six protrusions because the protrusions may coincide with the weld lines. Therefore, the positions of the gates and the protrusion pins are the same, and the protrusion pins are provided close to each gate position (preferably close to the radial direction). The number of gates (and protruding pins) is preferably 6 to 8 or more. Further, it is difficult to provide gates at nine or more positions because the gate space is eliminated and the mold structure is difficult.

  For example, when the flange material is polycarbonate, the flange diameter is 95 mm, and the opening diameter is 40 mm, the position of the protruding pin is set within 10 mm, preferably within 5 mm from the gate position. Other flange materials include acrylic resin, styrene acrylonitrile copolymer, polystyrene, and the like, and effects can be expected for these.

  FIG. 5 is a cross-sectional view of a mold 100 for forming the lower flange 33. The mold 100 includes a fixed-side mold 101 and a movable-side mold 102, and when both 101 and 102 are combined, a molding space 106 having a cross-sectional shape corresponding to the cross-section of the flange shown in FIG. 4 is formed. Inside the space, the flange opening 33 a of the movable mold 102 is formed by the insert piece 105. A runner 107 and a gate 33c 'are formed therein.

  After the resin is injected into the mold, the product (flange 33) and the runner 107 move together with the movable mold 102 when the movable mold moves downward in the drawing. Then, the protruding pins 103 and 104 move upward in the drawing, whereby the product (lower flange 33) and the runner 107 are taken out from the movable mold 102.

1 Upper case, 11, 21 Opening, 2 Lower case, 12 Protrusion, 22 Opening, 3 Tape reel, 31 Upper flange, 32 Hub, 32a Step, 33 Lower flange, 33a
Opening, 33b welding rib, 33c gate mark, 33c 'gate, 33d protruding pin mark, 34 recess, 35 cylindrical protrusion, 36 unevenness (tooth part), 37 engagement tooth, 4 bearing, 5 plug, 51 first protrusion Part, 52 rib, 53 guide projection, 54 flange, 55 second convex part, 55a vertical part, 6 reel spring, 7 door member, 8a, 8b reel brake, 9 hook, 100 mold, 101 fixed side mold, 102 Movable mold, 103 extruding pin, 104 extruding pin, 105 insert piece, 106 space, 107 runner.

Claims (12)

A flange for a tape reel, wherein the flange has an opening in the center of the flange,
A plurality of gate marks formed at substantially equal intervals in the vicinity of the opening on the flange;
A plurality of weld lines in the vicinity of the opening on the flange, each weld line being at an intermediate position between two corresponding gate traces of the plurality of gate traces;
A plurality of protruding pin marks formed on the flange, each protruding pin mark being formed on a radius in the vicinity of each corresponding gate mark and extending from the opening through the corresponding gate mark; There is a flange.   The flange according to claim 1, wherein none of the plurality of protruding pin marks is on a radius extending through the weld line.   The plurality of gate traces is a first number of gate traces, the plurality of protruding pin traces is a second number of protruding pin traces, and the first number is equal to the second number. The flange according to 1.   The flange according to claim 3, wherein the first number and the second number are each 6 or 8.   2. The flange according to claim 1, wherein the plurality of gate marks formed at substantially equal intervals are formed at an angle of plus or minus 5 degrees or less from an equal angular position when viewed from the center of the flange.   The flange according to claim 1, wherein each protruding pin mark is located at a distance of 10 mm or less from each corresponding gate mark. A mold for forming a flange for a tape reel, wherein the flange has an opening at the center of the flange, and the mold includes:
Including a first mold half and a second mold half, each of the first and second mold halves having a molding surface forming a molding space for molding the flange;
The first mold half has a plurality of gates formed at substantially equal intervals in the vicinity of the opening of the flange;
The second mold half has a plurality of weld lines, each weld line being in an intermediate position between two corresponding gates of the plurality of gates;
The second mold half has a plurality of ejector pins for projecting the flanges, each ejector pin being in the vicinity of a corresponding gate on the first mold half and each corresponding one A mold in the same radial direction from the gate and the opening of the flange.   The mold according to claim 7, wherein none of the plurality of protruding pins is on a radius extending through the weld line.   8. The plurality of gates is a first number of gates, the plurality of ejector pins are a second number of ejector pins, and the first number is equal to the second number. Mold.   The mold according to claim 9, wherein the first number and the second number are 6 or 8, respectively. The plurality of gates formed at substantially equal intervals are formed at an angle of plus or minus 5 degrees or less from an equal angular position when viewed from the center of the first mold half. Mold.   The mold according to claim 7, wherein each protruding pin is located at a distance of 10 mm or less from each corresponding gate.

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