JP2005004880A - Manufacturing method of reel for magnetic tape cartridge, metallic mold for manufacture the reel, reel for magnetic tape cartridge, and magnetic tape cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a decrease in fixing force of a metal plate while improving the work efficiency for positioning a metal plate with respect to a metallic mold and positioning accuracy of the metallic mold. <P>SOLUTION: The inner peripheral surface 61A of the ring-form metal plate 49 is formed in a tapered shape, and the circumferential surfaces of a positioning projections 74 for holding the inner peripheral surface 61A in the metallic mold are also formed in a tapered shape. A plurality of positioning projections 74 are prepared so as to be engaged with the inner peripheral surface 61A of the plate over a predetermined circumferential angular range. Thus, the work efficiency of engagement of the metal plate 49 with the positioning projections 74 is improved. Moreover, since a resin adheres closely to the inner peripheral surface 61A of the plate after molding and the tapered and undercut mode of the plate inner peripheral surface is obtained, separation of the metal plate 49 from a reel bottom part 62 can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a reel for a magnetic tape cartridge in which a metal plate for magnetic attraction is integrally formed on the bottom surface of the reel, a mold for manufacturing the same, a reel for a magnetic tape cartridge, and a magnetic tape cartridge.
[0002]
[Prior art]
Conventionally, a magnetic tape cartridge used as a recording medium used in an external storage device such as a computer is of a type in which a magnetic tape is wound around a single reel and the reel is rotatably accommodated in the cartridge body. Things are generally known. There are various types of such a single reel type magnetic tape cartridge.
[0003]
For example, in an LTO format magnetic tape cartridge, a reel gear that meshes with the drive gear is provided on the bottom surface of the reel in order to perform rotational drive by the drive gear of the drive side rotational drive means. A metal plate for magnetic attraction for maintaining the state is installed. In general, the metal plate has an annular shape having a central hole, and is integrally formed on the bottom surface of a synthetic resin reel by insert molding.
[0004]
7A and 7B show a method for manufacturing a reel for a magnetic tape cartridge described in Patent Document 1 below. Here, FIG. 7A is a bottom view of the metal plate portion at the center of the bottom surface of the reel of the conventional magnetic tape cartridge, and FIG. 7B is a cross-sectional view of a mold for explaining the forming process of the reel and the metal plate. The reel 103 is molded by injecting resin through a gate hole 113a of the gate bush 113 into a cavity formed by the fixed mold 111 and the movable mold 112.
[0005]
A tubular holding member 114 that holds the inner peripheral surface of the metal plate 101 is disposed on the outer periphery of the gate bush 113. A ring-shaped protrusion 115 is provided at the tip of the holding member 114, and the inner peripheral surface of the central hole 102 of the metal plate 101 is fitted into the outer peripheral surface of the ring-shaped protrusion 115 to fix the plate surface of the metal plate 101. The mold 111 is held in contact with a predetermined position on the inner surface, the movable mold 112 is closed, and the resin is injected.
[0006]
Further, in the formed reel 103, a holding trace 116 of the ring-shaped protrusion 115 of the holding member 114 is formed as a concave ring groove in a portion of the bottom wall 104 that closes the central hole 102 of the metal plate 101. Become. A gate mark 117 is formed at the center of the bottom wall 104.
[0007]
[Patent Document 1]
JP-A-11-353851 gazette
[Problems to be solved by the invention]
In the method of integrally forming the reel bottom wall and the metal plate by insert molding, the positioning accuracy of the metal plate with respect to a predetermined position in the mold is important.
In this regard, in the conventional reel forming method described above, a predetermined positioning accuracy is ensured by fitting the center hole 102 of the metal plate 101 into the ring-shaped protrusion 115 of the holding member 114 disposed at the center of the cavity.
[0009]
However, if the clearance between the inner periphery of the metal plate 101 and the outer periphery of the ring-shaped protrusion 115 is small, the fitting operation between the ring-shaped protrusion 115 and the metal plate 101 cannot be easily performed. It is a major cause of outages.
On the other hand, if the clearance is increased, the backlash of the ring-shaped protrusion 115 in the mold increases, so that the positioning accuracy inevitably decreases.
[0010]
As described above, in the conventional reel forming method, it is impossible to achieve both the workability of fitting the metal plate into the mold and the positioning accuracy of the metal plate. I can't plan.
[0011]
On the other hand, in the formed reel 103, a ring-shaped holding mark 116 is formed along the inner peripheral surface of the central hole 102 of the metal plate 101, so that the resin portion of the inner peripheral portion of the metal plate 101 and the reel bottom wall 104 is formed. The contact area cannot be increased, and the metal plate 101 is insufficiently fixed to the reel bottom wall 104.
[0012]
On the other hand, as shown in FIGS. 8A and 8B, in Patent Document 1, a plurality of holding pins 124 are arranged on the outer peripheral portion of the gate bush 113, and the plurality of holding pins 124 are used. A configuration is described in which the inner peripheral surface of the metal plate 101 is held so that the plate surface of the metal plate 101 is held in close contact with a predetermined position on the inner surface of the fixed mold 111.
[0013]
With this configuration, the adhesion between the inner peripheral surface of the metal plate 101 and the resin portion of the reel bottom wall 104 can be improved as compared with the example shown in FIG. With respect to the compatibility between the positioning accuracy and the positioning accuracy, there are problems similar to those of the configuration example shown in FIG. 9, and it is impossible to simultaneously improve workability and molding quality.
[0014]
The present invention has been made in view of the above-described problems, and a method for manufacturing a reel for a magnetic tape cartridge capable of preventing a decrease in the fixing force of the metal plate while improving the alignment workability of the metal plate relative to the mold and the positioning accuracy of the metal plate. An object of the present invention is to provide a molding die and a reel for a magnetic tape cartridge.
[0015]
[Means for Solving the Problems]
In solving the above problems, the method for manufacturing a reel for a magnetic tape cartridge according to the present invention is such that a metal plate is formed in an annular shape having a central hole whose inner peripheral surface is tapered, and the outer peripheral surface is tapered inside the cavity. Positioning protrusions that engage with each other over a predetermined angular range of the inner peripheral surface of the metal plate are provided at a plurality of locations, and the metal plate is moved by the engaging action between the central hole and the plurality of positioning protrusions during insert molding. The resin constituting the reel is injected and filled into the cavity while being positioned and held.
[0016]
In the present invention, the metal plate is positioned inside the cavity by the engaging action between the central hole of the metal plate and the plurality of positioning protrusions inside the cavity, and the inner peripheral surface of the metal plate and the outer peripheral surface of the positioning protrusion are mutually aligned. The taper surfaces are engaged with each other. As a result, the peripheral surface of the central hole of the metal plate has a divergent shape, and the mating positioning projection is tapered, so that the engaging action between them is very easy. Further, since the positioning operation can be performed with close contact with each other when the engagement is completed, the workability of fitting the metal plate into the positioning projection and the improvement of the molding quality can be achieved at the same time.
[0017]
In addition, since a plurality of positioning protrusions are provided so as to engage over a predetermined range in the circumferential direction of the inner peripheral surface of the metal plate, an appropriate positioning function of the positioning protrusion with respect to the central hole of the metal plate can be secured.
[0018]
Furthermore, since the constituent resin of the bottom surface of the reel is in close contact with the region of the inner peripheral surface of the metal plate that is not in intimate contact with the positioning protrusion, the taper portion of the inner peripheral surface region exhibits an undercut after the molding, A high fixing force of the metal plate can be obtained.
[0019]
On the other hand, in the mold for manufacturing a reel for a magnetic tape cartridge according to the present invention, a plurality of positioning projections engaged with each other over a predetermined range in the circumferential direction of the inner peripheral surface of the metal plate are tapered inside the cavity. The metal plate is positioned and held by an engaging action between the central hole and a plurality of positioning protrusions at the time of insert molding.
[0020]
With this configuration, the metal plate fitting workability and the positioning accuracy can be improved at the same time, and a high-quality magnetic tape cartridge reel can be manufactured.
[0021]
Furthermore, in the reel for the magnetic tape cartridge of the present invention, the metal plate integrally formed on the bottom surface of the reel by insert molding is formed in an annular shape having an inner peripheral surface having a tapered center hole, and on the bottom surface of the reel. The remaining metal plate holding traces are formed at a plurality of locations over a predetermined angular range of the inner peripheral surface of the metal plate, and the reel bottom surface is connected to an area where the holding traces are not formed on the inner peripheral surface of the metal plate.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an entire magnetic tape cartridge 20 according to an embodiment of the present invention. First, the overall configuration of the magnetic tape cartridge 20 will be described.
[0023]
The cartridge main body 21 of the magnetic tape cartridge 20 is configured by connecting an upper half 21 a and a lower half 21 b with four screw members 43. A single reel 23 around which a magnetic tape 22 is wound is accommodated inside the cartridge body 21. The reel 23 is configured by integrating an upper reel flange 44 and a lower reel flange 45 integral with the hub 51 by ultrasonic bonding.
[0024]
On the bottom surface of the reel 23, a reel gear 25 that meshes with the drive gear of the rotation drive means of the tape drive device is formed in an annular shape and exposed to the outside through an opening 24 provided in the center of the lower half 21b. . On the inner side of the reel gear 25, a magnetic force attracting metal plate 49 for fixing the meshed state with the drive gear is fixed.
[0025]
The metal plate 49 is integrally formed with the bottom surface of the reel 23 by insert molding, and details thereof will be described later.
[0026]
A spider 46, a reel lock member 47, and a reel lock spring 48 are provided between the upper half 21 a and the reel 23.
[0027]
The spider 46 has a substantially triangular shape, and leg portions 46 a projecting downward at the respective vertex portions are respectively inserted into insertion holes 51 b formed in the hub 51. A cylindrical protrusion 46b is provided on the upper surface of the spider 46, and a reel lock member 47 is rotatably supported via a bearing 50 inserted therein.
[0028]
The reel lock member 47 receives an urging force of a reel lock spring 48 formed of a coil spring, and a gear portion 47a formed in an annular shape on the bottom surface thereof meshes with a plurality of arc-shaped gear portions 51a erected inside the hub 51. By doing so, the operation of restricting the rotation of the reel 23 when the magnetic tape cartridge 20 is not used is performed.
[0029]
When the magnetic tape cartridge is used, a drive release spindle of a tape drive device (not shown) presses the spider 46 from below, and moves the reel lock member 47 upward against the urging force of the reel lock spring 48. As a result, the meshing between the gear portion 47a of the reel lock member 47 and the gear portion 51a of the hub 51 is released, and the reel 23 is rotatable.
[0030]
On the other hand, an opening 27 for pulling out one end of the magnetic tape 22 to the outside is provided on one side wall 26 of the cartridge body 21. Inside the side wall 26, a wall portion 39 is formed at a predetermined distance from the side wall 26, and the side wall 26 and the wall portion 39 guide the movement of the openable slide door 29 of the opening 27. A guide groove 41 is formed. The guide groove 41 is configured not only in the lower half 21b side but also in the same form on the upper half 21a side, not shown.
[0031]
A metal leader pin 31 is fixed to one end of the magnetic tape 22 by a clamper 52. The leader pin 31 can be attached to and detached from the elastic holder 33 on the pin holding portion 30 provided on the inner side of the opening 27. The elastic holder 33 is formed by bending a leaf spring into a U-shape, and is formed on both the upper wall inner surface (the inner surface of the upper half 21a) and the bottom wall inner surface (the inner surface of the lower half 21b). It is configured vertically symmetrical.
[0032]
An engagement portion 29 a is provided at one side edge of the slide door 29 to allow the tape transport mechanism of the tape drive device to chuck and open the slide door 29. A torsion spring 57 that biases the slide door 29 to the closed position is accommodated in the guide groove 41.
[0033]
In addition, a safety tab 53 for preventing accidental erasure of information recorded on the magnetic tape 22 is slidably attached to the other side wall of the cartridge main body 21, and information recorded on the magnetic tape 22 can be stored. A non-contact readable / writable IC substrate 54 is inclined.
[0034]
Further, a display 60 indicating the insertion direction of the cartridge with respect to the tape drive device is recessed in the upper front side of the upper half 21a.
[0035]
Next, the configuration of the bottom surface of the reel 23 to which the metal plate 49 is fixed will be described with reference to FIGS.
2 is a bottom view of the reel 23, FIG. 3 is an enlarged view of a mounting portion of the metal plate 49 on the bottom surface of the reel 23, and FIG. 4A is an enlarged view of a reel bottom portion 62 that closes the central hole 61 of the metal plate 49. 4B is a cross-sectional view in the direction [X]-[X] in FIG. 4A, and FIG. 5 is a cross-sectional side view of a main part of a lower reel flange 45 constituting the reel 23.
[0036]
As shown in FIG. 2, the metal plate 49 is fixed to the bottom surface of the reel 23. The metal plate 49 is integrally formed on the bottom surface of the reel 23 by insert molding. The metal plate 49 is made of a magnetic material and has an annular shape having a central hole 61. A reel gear 25 is formed in an annular shape on the outer periphery of the metal plate 49. The reel gear 25 is formed to protrude outward from the plate surface of the metal plate 49 (FIG. 5).
[0037]
On the plate surface of the metal plate 49, three through holes 63 are formed at equal angular intervals on the circumference of the same radius. The inner peripheral surfaces of these through-holes 63 are tapered in order to maintain the adhering force, and are filled with the constituent resin of the reel 23 (FIG. 5). The constituent resin of the reel 23 closes the central hole 61 of the metal plate 49 and constitutes the reel bottom surface portion 62. In this embodiment, a polycarbonate resin is used as the constituent resin of the reel 23. Of course, other synthetic resin materials can also be used.
[0038]
A plate inner peripheral surface 61A constituting the central hole 61 of the metal plate 49 is formed of a tapered surface whose diameter increases toward the outer side of the bottom of the reel 23 (FIGS. 4A and 4B). The taper angle of the inner peripheral surface 61A of the plate is not particularly limited, and is determined corresponding to the taper angle of the outer peripheral surface of a positioning projection (described later) that positions and holds the metal plate 49 during insert molding.
[0039]
At a plurality of positions on the peripheral edge of the reel bottom surface portion 62 that closes the central hole 61, substantially fan-shaped holding traces 64 are formed over a predetermined circumferential angular range of the plate inner peripheral surface 61A. These holding marks 64 are portions into which positioning protrusions for positioning and holding the metal plate 49 enter during insert molding. In addition, a recess 65 and a gate mark 66 are formed in the center of the reel bottom surface portion 62 to drop the gate.
[0040]
6A and 6B are mold configuration diagrams for explaining the forming process of the reel 23, A is an enlarged view of a main part of the fixed side mold, and B is a cross-sectional view in the [Y]-[Y] line direction in A. FIG.
[0041]
In a cavity 73 formed between the fixed side mold 70 and the movable side mold 71, a plurality of positioning projections 74 that are engaged over a predetermined angular range of the plate inner peripheral surface 61A of the metal plate 49 are provided. Is provided. The outer peripheral surface 74A of the positioning protrusion 74 has a taper shape with an angle corresponding to the inner peripheral surface 61A of the plate. During insert molding, as shown in FIG. 6B, the entire outer peripheral surface 74A of the positioning protrusion 74 is the inner peripheral surface of the plate. It comes in close contact with the surface 61A.
[0042]
The number of the positioning protrusions 74 formed is not particularly limited, but in this embodiment, it is necessary to hold a plurality of locations on the inner surface 61A of the plate in order to ensure the positioning function of the metal plate 49 with respect to the inside of the cavity 73. Three places are provided at equal angular intervals. However, the present invention is not limited to this, and it is only necessary that the positioning projections 74 be provided at least at two or more positions at equal or unequal angular intervals.
[0043]
The taper angle θ (see FIG. 6B) of the outer peripheral surface 74A of the positioning protrusion 74 is set according to the taper angle of the plate inner peripheral surface 61A. The taper angle θ can be set arbitrarily. However, if it is too small, it becomes difficult to engage the center hole 61 of the metal plate 49 and the positioning projection 74, and if it is too large, the engagement workability is improved. The positioning function of the object is reduced.
In the present embodiment, the taper angle θ is set to 7 °, for example. Thereby, positioning accuracy of about 0.12 mm can be obtained.
[0044]
The engagement angle range between the outer peripheral surface 74A of the positioning protrusion 74 and the plate inner peripheral surface 61A can also be set as appropriate. However, if this engagement angle range is too narrow, wear due to sliding with the inner peripheral surface 61A of the plate tends to occur, durability is lowered, and the positioning function of the metal plate 49 is lowered. If the engagement angle range is too wide, the interval between the adjacent positioning projections 74 is narrowed, and the contact area between the reel constituent resin filling the gap and the plate inner peripheral surface 61A is reduced, so that the bottom surface of the reel 23 is reduced. A large fixing force of the metal plate 49 cannot be obtained.
In the present embodiment, the engagement angle range between the outer peripheral surface 74A of the positioning protrusion 74 and the plate inner peripheral surface 61A is set to 60 ° per location, for example.
[0045]
The protrusion amount (engagement height) of the positioning protrusion 74 with respect to the center hole 61 of the metal plate 49 is set to be smaller than the thickness dimension of the metal plate 49, whereby the positioning protrusion 74 moves from the metal plate 49 to the movable side. It does not protrude toward the mold 71 so that the flow of resin in the flange direction is not hindered.
[0046]
Each positioning projection 74 is formed to protrude on a common base 77. The pedestal 77 is circular, and its diameter is equivalent to the maximum hole diameter of the central hole 61 of the metal plate 49. The outer peripheral surface of the pedestal 77 has a taper shape with the same angle as the outer peripheral surface 74A of the positioning projection 74 over the entire periphery. Thus, the base 77 can be fitted into the center hole 61 by a predetermined amount.
In the present embodiment, the fitting amount D is about 0.2 mm.
[0047]
A circular convex surface portion 75 protruding in a convex shape is formed at the center of the pedestal 77, and a gate hole 76 for injecting the constituent resin of the reel 23 is provided at the central portion of the convex surface portion 75. This pedestal 77 is integrally formed on the inner surface of the fixed mold 70.
[0048]
Now, in the mold for manufacturing the reel 23 of the present embodiment configured as described above, the positioning projection 74 and the pedestal 77 formed on the inner surface of the fixed side mold 70 are connected to the central hole 61 of the metal plate 49. The metal plate 49 is positioned inside the cavity 73 in a state where the plate surface of the metal plate 49 is in close contact with the inner surface of the fixed mold 70. At this time, the outer peripheral surface of the pedestal 77 is fitted over the entire periphery of the plate inner peripheral surface 61A.
[0049]
According to the present embodiment, both the inner peripheral surface 61A of the metal plate 49 and the outer peripheral surface 74A of the positioning projection 74 are formed with a tapered surface having substantially the same angle θ. While facilitating the fitting operation, the metal plate 49 can be positioned with high accuracy without any rattling after fitting. Further, since the positioning protrusion 74 is integrally formed on the inner surface of the fixed mold 70, it is possible to ensure a high positioning accuracy of the metal plate 49 with respect to the mold surface.
[0050]
After positioning the metal plate 49, the movable mold 71 is closed, and molten resin is injected from the gate hole 76 into the cavity 73 and filled. Thereby, the lower reel flange 45 is formed. A metal plate 49 is fixed to the bottom surface of the reel 23 after molding in the form as shown in FIGS.
In addition, when the molten resin is injected and filled, the metal plate 49 may be pressed and held toward the fixed mold 70 using a plurality of pins as necessary.
[0051]
Here, the inside of the central hole 61 of the metal plate 49 is blocked by a reel bottom surface portion 62 made of a filling resin, and the inner peripheral surface of the metal plate 49 is provided at a plurality of locations over a predetermined angular range at the periphery of the reel bottom surface portion 23. (In this example, three locations) The substantially fan-shaped holding marks 64 remain at equiangular intervals. The reel bottom surface portion 62 is connected to the plate peripheral surface portion 61A where the holding trace 64 is not formed.
[0052]
In the present embodiment, since the inner peripheral surface 61A of the plate is formed in a tapered shape, the reel bottom surface portion 62 that is in close contact with the inner peripheral surface 61A of the plate exhibits an undercut mode, whereby the reel bottom surface portion The separation of the metal plate 49 with respect to 62 is prevented, and the fixing force between the reel 23 and the metal plate 49 can be improved.
[0053]
Further, according to the present embodiment, the height of the reel bottom surface portion 62 is formed by the upper surface portion 72 of the pedestal 77 to be lower than the plate surface of the metal plate 49 by a distance D. Thereby, it becomes possible to absorb the burrs formed by the resin leaked between the inner peripheral surface 61A of the plate and the fixed mold 70 (the outer peripheral surface of the pedestal 77) by the step having the depth D, It is possible to suppress the protrusion of burrs to the outer surface side of the metal plate 49. It should be noted that the size of the step D can be adjusted according to the nature of the generated burr.
[0054]
Furthermore, according to the present embodiment, since the convex surface portion 75 is formed around the gate hole 76, the protrusion of the gate mark 66 on the reel bottom surface portion 62 formed corresponding to the gate hole 76 is It can absorb by the recess 65 formed corresponding to the said convex surface part 75, and the management burden reduction of molding quality can be aimed at.
[0055]
As described above, according to the present embodiment, it is possible to achieve both the workability of fitting the metal plate 49 into the positioning projection 74 and the positioning accuracy, and the reel 23 with excellent workability and high quality is provided. A magnetic tape cartridge 20 can be obtained. In addition, the magnetic tape cartridge 20 with high reliability can be configured by firmly holding the metal plate 49 firmly attached to the bottom surface of the reel 23.
[0056]
The embodiment of the present invention has been described above. Of course, the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.
[0057]
For example, in the above embodiment, the positioning protrusions 74 for positioning and holding the metal plate 49 are formed at three locations, but the number is not limited to this. In accordance with the engagement angle range with the plate inner peripheral surface 61A, for example, a predetermined positioning function can be obtained only by providing it at two locations.
[0058]
【The invention's effect】
As described above, according to the present invention, it is possible to achieve both the alignment workability of the metal plate with respect to the inside of the mold and the positioning accuracy, the workability is excellent, and the reel for a magnetic tape cartridge with high quality is provided. Can be manufactured.
[0059]
In addition, it is possible to form a highly reliable magnetic tape cartridge reel and a magnetic tape cartridge including the same by firmly holding the metal plate firmly attached to the bottom surface of the reel.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a configuration of a magnetic tape cartridge according to an embodiment of the present invention.
FIG. 2 is a bottom view of the reel 23. FIG.
FIG. 3 is an enlarged view showing a fixing portion of the metal plate 49 on the bottom surface of the reel 23;
4A is a diagram showing a configuration inside the central hole 61 of the metal plate 49, and B is a cross-sectional view in the [X]-[X] line direction in A. FIG.
5 is a sectional side view of a main part of a lower reel flange constituting the reel 23. FIG.
6A and 6B are configuration diagrams of a mold for molding the lower reel flange 45 of the reel 23, in which A is an enlarged view of a main part of the fixed-side mold, and B is a cross-sectional view in the [Y]-[Y] line direction in A; .
7 is an enlarged view of a central portion of a reel bottom surface of a conventional reel for a magnetic tape cartridge and a sectional view thereof. FIG.
FIG. 8 is an enlarged view and a cross-sectional view of the reel bottom center portion of another conventional magnetic tape cartridge reel.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20 ... Magnetic tape cartridge, 21 ... Cartridge main body, 21a ... Upper half, 21b ... Lower half, 22 ... Magnetic tape, 23 ... Reel, 25 ... Reel gear, 45 ... Lower reel flange, 49 ... Metal plate, 61 ... Center hole, 61A ... Plate inner peripheral surface, 62 ... Reel bottom surface, 64 ... Holding trace, 65 ... Recess, 66 ... Gate trace, 70 ... Fixed side mold, 71 ... Movable side mold, 73 ... Cavity, 74 ... Positioning protrusion 74A, outer peripheral surfaces of the positioning protrusions, 75, convex portions, 76, gate holes, 77, pedestal.

Claims (9)

In a method for manufacturing a reel for a magnetic tape cartridge in which a metal plate for magnetic attraction is integrally formed on the bottom surface of the reel,
The metal plate is formed in an annular shape having an inner peripheral surface having a tapered central hole,
Inside the cavity, the outer peripheral surface is tapered, and a plurality of positioning projections that engage over a predetermined angular range in the circumferential direction of the inner peripheral surface of the metal plate are provided,
A magnetic tape in which a reel component resin is injected and filled into the cavity in a state in which the metal plate is positioned and held by an engaging action between the center hole and the plurality of positioning protrusions during insert molding. Manufacturing method of cartridge reel. 2. The method for manufacturing a reel for a magnetic tape cartridge according to claim 1, wherein an engagement height of the positioning protrusion with respect to the central hole is made smaller than a thickness dimension of the metal plate. The pedestal on which the plurality of positioning projections are formed to protrude is provided inside the cavity, and the outer peripheral surface of the pedestal is fitted to the entire circumference of the central hole during insert molding. A method of manufacturing a reel for a magnetic tape cartridge. A magnetic tape cartridge reel in which a metal plate for magnetic force attraction is integrally formed on the bottom surface of the reel, wherein the metal plate is formed in an annular shape with an inner peripheral surface having a tapered central hole. In the mold for manufacturing cartridge reels,
In the cavity, the outer peripheral surface is tapered, and positioning protrusions that are engaged over a predetermined range in the circumferential direction of the inner peripheral surface of the metal plate are provided at a plurality of locations.
A mold for manufacturing a reel for a magnetic tape cartridge, wherein the metal plate is positioned and held by an engaging action between the central hole and the plurality of positioning protrusions during insert molding. 5. The mold for manufacturing a reel for a magnetic tape cartridge according to claim 4, wherein a protruding amount of the positioning protrusion is smaller than a thickness dimension of the metal plate. A pedestal on which the plurality of positioning protrusions are formed to protrude is provided inside the cavity, and an outer peripheral surface of the pedestal is fitted to the entire circumference of the central hole during insert molding. Item 5. A mold for manufacturing a reel for a magnetic tape cartridge according to Item 4. 5. The mold for manufacturing a reel for a magnetic tape cartridge according to claim 4, wherein the plurality of positioning protrusions are integrally formed on an inner surface of the fixed mold. An annular metal plate for attracting magnetic force is fixed to the bottom surface of the reel made of synthetic resin by insert molding, and a retaining mark of the metal plate is formed at the time of the insert molding on the bottom surface of the reel that closes the central hole of the metal plate. In a magnetic tape cartridge reel,
The metal plate is formed in an annular shape having an inner peripheral surface having a tapered center hole,
The holding marks are formed at a plurality of locations over a predetermined angular range in the circumferential direction of the inner peripheral surface of the metal plate,
A reel for a magnetic tape cartridge, wherein the bottom surface of the reel is connected to a region where the holding trace is not formed on the inner peripheral surface of the metal plate. A magnetic tape cartridge in which a single reel wound with a magnetic tape is rotatably accommodated inside the cartridge body, and an annular metal plate for magnetic attraction is fixed to the bottom surface of the synthetic resin by insert molding. In the magnetic tape cartridge, on the bottom surface of the reel that closes the central hole of the metal plate, a holding mark of the metal plate at the time of the insert molding is formed.
The metal plate is formed in an annular shape having an inner peripheral surface having a tapered center hole,
The holding marks are formed at a plurality of locations over a predetermined angular range in the circumferential direction of the inner peripheral surface of the metal plate,
The magnetic tape cartridge according to claim 1, wherein the bottom surface of the reel is connected to a region where the holding trace is not formed on the inner peripheral surface of the metal plate.

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