JPS6032175A - Center core producing device of magnetic disk device - Google Patents

Abstract

PURPOSE:To obtain a center core having high accuracy by having a contact between the upper end face of a columnar part of a prescribed form of a metallic mold at the fixed side and the lower end surface of a columnar part of a movable metallic mold having a prescribed structure together with a contact between the upper end face of the fixed metallic mold and the lower end face of the movable metallic mold respectively and injecting synthetic resin into a circular space part. CONSTITUTION:The 2nd fixed metallic mold 24 containing circular recess parts 25 and 26 is provided around a columnar part 21 set on a conical trapezoidal pedestal part 20 of a fixed metallic mold. A U-shaped bent surface 34 and a projected part 35 are provided on the outer circumferential surface 21a of the part 21 together with two flat surfaces 36 formed at the side opposite to the part 35 to form a positioning surface. The surface 21a is flat. A bent bar 32 and two tongue piece 33 are protruded over a flat lower end face 28A of a columnar part of a movable metallic mold 27. Then a contact is secured between a lower end face 29A of the 2nd movable metallic mold 29 and the upper end face of a fixed metallic mold 24 as well as between the face 28A and an upper end face 21A of the part 21 respectively. Then synthetic resin is injected into a circular space part. In such a way, a center core having high accuracy is obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an apparatus for manufacturing a center core made of synthetic resin, which is attached to the rotation center of a sheet-shaped magnetic disk (hereinafter referred to as a rotating magnetic sheet), for example. Regarding.

[Background technology and its problems]

2. Description of the Related Art Recently, devices have been proposed that record still image information on a rotating magnetic sheet or reproduce the recorded image information.

A magnetic disk device as shown in FIG. 1 has been proposed as a magnetic disk device for use in the above device. That is, the rotating magnetic sheet S is rotatably housed in a thin housing J. A center core 100 molded from synthetic resin is attached to the center of rotation of the above-mentioned seat S. A shaft insertion hole 102 into which, for example, a disk drive shaft 101 of a magnetic recording/reproducing device is inserted and positioned is formed in the core 100 and extends vertically in the figure.

As shown in FIG. 2, positioning surfaces 103, 103 for aligning the rotation center of the magnetic sheet S with the axis of the drive shaft 101 are formed in the shaft insertion hole 102 in a substantially V-shape. There is. And these positioning surfaces 103, 10
3 as a reference to determine the center of rotation of the magnetic sheet S with respect to the drive shaft 101. Further, the drive shaft 101 is inserted into the shaft insertion hole 102 at a position facing the positioning surface 103.103.
U-shaped suppression piece 104 for elastically pressing against 103
are integrally formed. This suppressing piece 104 is formed by providing a long hole 105 on the side opposite to the suppressing surface 104A that contacts the outer peripheral surface of the drive shaft 101. The length of a straight line d connecting the central portion a of the suppression surface 104 and the rotation center X of the magnetic sheet S is set to be shorter than the length of the radius of the drive shaft 101. Therefore, when the drive shaft 101 is inserted into the shaft insertion hole 102, the pressing surface 104A of the pressing piece 104 pushes the outer peripheral surface of the driving shaft 101 into the positioning surface 10.
3,103 so that it can be elastically pressed.

In the center core 100, the shaft insertion portion 102 into which the drive shaft 101 is actually inserted is formed of Venus having a substantially cylindrical column body portion 106 as shown in FIG. A flat surface 107 for forming each of the positioning surfaces 103, 103 on the outer peripheral surface of the columnar portion 106.
, 107 are chamfered so as to be continuous in a straight line in the axial direction. Further, on the outer circumferential surface of the columnar portion 106, a U-shaped curved surface 108 for forming the pressing surface 104A of the pressing piece 104 is arranged in a straight line in the axial direction at a portion opposite to the flat surfaces 107, 107. They are formed in a series of shapes.

Incidentally, the margin of the shaft insertion portion 102' relative to the drive shaft 101 is set to about 50 microns.

Therefore, high precision is required for manufacturing the column body portion 106 in the mold.

By the way, in manufacturing the columnar portion 106, although the flat surfaces 107, 107 can be formed by cutting or the like with high precision without any problem, the curved surface 108
It is quite difficult to form with high precision. That is, this is because the curved surface 108 must be formed into a U-shape around the outer periphery of the material of the cylindrical body 106.

Therefore, it is quite difficult to finish the inner diameter of the shaft insertion portion 102 to a dimension that satisfies the above-mentioned tightening margin, and if the inner diameter of the shaft insertion portion 102 is outside the allowable range, the shaft insertion hole 102 The drive shaft 10 that is inserted into the
The receiving state of the magnetic sheet S also becomes unstable, and a stable rotating state of the magnetic sheet S cannot be obtained.

On the other hand, when the center core 100 is mass-produced by injection molding, it becomes unavoidable to use a large number of molds.

By the way, since it is quite difficult to manufacture the column body part 106 for forming the shaft insertion part 102' of the center core 100 with high precision as described above, the column body part 106 to be manufactured is There is almost always some variation in dimensions.

In order to correct the variation in the dimensions, the columnar portion 10
When the curved surface 108 of 6 is additionally machined, for example, by cutting, the wall thickness of the pressing piece 104 of the finally finished center core 100 becomes thinner than the normal thickness, and the pressing piece 10
The spring constant of 4 will change.

Therefore, it has been difficult to manufacture a large number of the pillar portions 106 according to the set dimensions.

L object of the invention] Therefore, the present invention was proposed in view of such conventional circumstances, and an object of the present invention is to provide a center core manufacturing device that is easy to manufacture and has high precision. .

Another object of the present invention is to provide a center core manufacturing device whose dimensions can be easily modified, thereby making it possible to easily manufacture a large number of highly accurate manufacturing devices.

[Summary of the Invention] In order to achieve the above object, the center core manufacturing apparatus of the present invention includes butting a stationary side Venus having a pillar section upright on a pedestal section and this stationary side mold. a movable side mold having a substantially circular recess formed in a surface thereof with an opening diameter larger than the diameter of the column body, and a protrusion hanging from the bottom of the concave portion; A flat surface extending linearly in the axial direction is chamfered on the outer peripheral surface of the part, and a convex strip extending linearly in the axial direction is formed on a portion of the outer peripheral surface opposite to the flat surface. , the movable mold is butted against the stationary mold so that the protruding piece faces the protruding strip with a predetermined gap and its tip abuts against the pedestal, and by this butting, the inside of the recess is The center core is formed by injecting synthetic resin into an annular space formed in the center core.

〔Example〕

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings.

First, before explaining the manufacturing apparatus according to the present invention.

Let me explain about the center core of a magnetic disk device that is molded using this device.

FIG. 4 is a sectional view of a main part of a rotating magnetic sheet device to which the center core is mounted. The rotating magnetic sheet S of this rotating magnetic sheet device is housed in a thin salmon throat J. At the center of rotation of the magnetic sheet S, the sheet 1-8 is
A center core 1 is attached to support the seat S so that the seat S can rotate horizontally without eccentricity. Both end faces IA and IB of the core 1 in the axial direction are exposed to the outside through openings Ja and Jb formed in the shaft J.

The core 1 is molded from synthetic resin, and has a square shaft insertion hole 3 formed through its center into which a disk drive shaft 2 (not shown) installed, for example, on a magnetic recording/reproducing device is inserted. There is.

The diameter of the shaft insertion hole 3 is approximately 7 mm.

Further, an annular positioning member 4 made of a magnetic member such as a metal plate is integrally fixed to the outer peripheral portion of the core 1 by outsert molding.

Then, on the magnetic recording surface Sa side of the above magnetic y-)S,
A portion closer to the inner circumference is attached to one end surface 4A of the positioning member 4.

The other end surface 4B of the positioning member 4 is formed parallel to the magnetic recording surface Sa of the magnetic sheet S.
B is a position reference surface that is received by an annular positioning rib 6 that protrudes from the rotary table 5 provided on the drive shaft 2 side. That is, the core 1 of the magnetic sheet S is received by the tip of the rib 6, so that the magnetic recording surface Sa can stably contact a magnetic head (not shown).

On the rotary table 5, an annular magnet 8 that protrudes into the inside of a skirt 7, which will be described later, is arranged and fixed at a portion on the inner peripheral side of the positioning rib 6.

An annular skirt 7 made of synthetic resin is fixed to the other end surface 4B of the positioning member 4, the tip of which protrudes into a position near the mouth wall of the opening Jb of the jacket l-J.

Due to the presence of the skirt 7, it is possible to prevent dust and the like from entering the jacket J through the opening Jb during storage of the magnetic sheet S, etc., and the magnetic recording surface S of the magnetic sheet S)
It is possible to prevent dust etc. from adhering to a. Therefore, excellent storage management of the magnetic sheet S can be obtained.

By the way, in the shaft insertion hole 3, as shown in FIG. 5, positioning surfaces 9, 9 are formed in a substantially V-shape for aligning the rotation center of the magnetic 7-toe S with the axis of the drive shaft 2. has been done. This positioning surface 9°9 serves as a reference to determine the center of rotation of the magnetic sheet S relative to the drive shaft 2. Further, the drive shaft 2 is placed in the shaft insertion hole 3 at a position opposite to the positioning surfaces 9, 9.
A U-shaped suppressing piece 10 for elastically pressing against 9 is integrally formed. This suppression piece 10 has a U-shaped elongated hole 11 on the opposite side to a suppression surface 10A that contacts the outer peripheral surface of the drive shaft 2.
It is formed by penetrating in the axial direction.

In the suppression surface 10A, a grooved portion 12 is formed so as to extend linearly in the axial direction at a portion symmetrically facing each of the positioning surfaces 9.9 (the central portion in the longitudinal direction of the suppression piece 10). . Then, as shown in FIG. 6, the drive shaft 2
The outer circumferential surface of the groove 12 is received by the central portion a of the bottom surface 12A of the grooved portion 12. Above suppression surface 10
The length of the straight line -R1 connecting the center part a of the bottom surface 12A of the grooved portion 12 and the rotation center X of the magnetic sheet S at A is as follows:
The radius of the drive shaft 2 is set to be shorter than the length of the radius l. Therefore, when the drive shaft 2 is inserted into the shaft insertion hole 3,
The bottom surface 12A of the concave portion 12 of the pressing piece 10 can elastically press the outer circumferential surface of the drive shaft 2 against the positioning surface 9°9. Note that the depth D of the grooved portion 12 is several tens of microns.

Further, in the one axial end surface 1A of the core 1, in the portion where the respective positioning surfaces 9, 9 are present, each of these surfaces 9, 9 is
Concave portions 13, 13 are formed substantially parallel to this. These recesses 13, 13 are for removing the thickness of the center core 1.

Next, a manufacturing apparatus for the center core 1 having the above configuration will be explained.

FIG. 7 is an exploded cross-sectional view of the main parts of this manufacturing apparatus. This manufacturing apparatus has a pedestal part 20 having a substantially truncated conical shape, a first stationary mold 23 having a columnar part 21 erected at the center of the pedestal part 20, and the pedestal part 20.
It has an annular second stationary side mold 24 that is fitted and positioned on the outer periphery of 0. In addition, around the columnar part 21,
As expected, an annular recess 25 surrounded by the second stationary mold 24 is formed.

Note that the upper end surface of the second stationary mold 24 (abutting surface with a lower end surface 29A of the second movable mold 29 described later) 2
At 48, a narrow annular recess 26 is formed to surround the recess 25, increasing the number +7.

On the other hand, the upper end surface 21A of the columnar body part 21 is formed as a flat surface, and the upper end surface 2i1 is a columnar body constituting the first movable mold 27 having a diameter larger than the diameter of the columnar part 21. The lower end surfaces 28A of the portions 28 are butted against each other. The columnar portion 28 is fitted into an annular second movable mold 29 and has an annular inward flange 31 formed near the lower end of the inner circumferential surface 30 of the mold 29. Therefore, the position is maintained. The inner diameter of the flange β1 is larger than the diameter of the columnar body portion 21 of the first fixed side metal 23.

Therefore, the lower end surface of the second movable mold 29 (the abutting surface with the upper end surface 24A of the second fixed mold 24)
29A is formed with a substantially circular recess 31 having an opening diameter larger than the diameter of the column body 21 of the first stationary mold 23.

Further, a lower end surface 28A of the columnar portion 2B of the first movable mold 27 is provided with a portion of the outer peripheral surface of the columnar portion 21 of the first fixed mold 23 (the pressing surface of the pressing piece 10). 10A is formed) 21a and the distal end surface 32 with a predetermined gap between them.
A U-shaped curved protrusion 32 whose portion a abuts against the pedestal 20 is formed to hang down. The thickness of the curved protrusion 32 is the same as the width of the elongated hole 11.

Furthermore, on the lower end surface 28A of the columnar portion 28 of the first movable mold 27, two tongue pieces 33° 33 are provided on the opposite side of the portion where the curved protrusion 32 is formed. The movable mold 29 is formed to hang down so as not to protrude from the lower end surface 29A of the movable mold 29. The thickness of each of the tongue pieces 33, 33 is formed to be the same as the width of each of the recesses 13, 13.

By the way, the columnar part 21 of the first stationary mold 23 mentioned above
As shown in FIG. 8, a U-shaped curved surface 34 for forming the pressing surface 10A of the pressing piece 10 is formed on a portion 21a of the outer peripheral surface of the curved surface 34. At the center of the groove, the height H is the same as the depth D of the groove 12 of the pressing piece 10, and the width Wl is the same as the groove 12 of the pressing piece 10.
The protruding stripes 35 having the same size as the width W2 are formed so as to be continuous in a straight line in the axial direction. Furthermore, flat surfaces 36 and 36 for forming the respective positioning surfaces 9, 9 are formed in a row in the axial direction on the other part of the outer circumferential surface of the columnar part 21 on the opposite side to the protruding strip part 35. has been done.

As shown in FIG. 9, the center core 1 is connected to the first
28A of the lower end surfaces of the columnar parts 28 constituting the movable mold 27 of
The upper end surface 21 of the columnar part 21 of the first stationary mold 23
At the same time, the lower end surface 29A of the second movable mold 29 is brought into contact with the upper end surface 29A of the second fixed mold 24.
A, the synthetic resin is applied from the first resin injection passage 37 formed in the first fixed mold 23 to each fixed mold 23.24 of each movable mold 28.29. It is formed by injecting into the annular space 50 formed by the combination. That is, - the shaft insertion hole 3 is formed by the columnar part 21 of the first stationary mold 23; A suppressing piece 10 is formed between the columnar part 21 and the curved protruding piece 32. Note that a positioning member 4 that is subjected to Awatosato molding is interposed between the second fixed side mold 24 and the second movable side mold 29.

Note that the second mold formed in the second stationary mold 24
By injecting synthetic resin into the recess 26 from the resin injection passage 3B, the annular skirt 7 is formed into the core 1.
It is designed to be formed separately.

It is easy to form the convex strips 35 on the columnar part 21 of the first stationary mold 23 with high accuracy by cutting or the like using common processing techniques. Therefore, the shaft insertion hole 3 including the concave portion 12 of the pressing surface 10A of the pressing piece 10 can be easily formed with high precision.

As a result, the center core 1 can be manufactured easily and with high precision.

Further, in the case where a large number of the first stationary side molds 23 are manufactured in order to mass-produce the core 1, the protruding portion 35
Even if the height H of the protrusion 35 is larger than the set dimension, the height H of the protrusion 35 can be easily adjusted to the set dimension by cutting or polishing the upper end surface 35A of the protrusion 35 using a milling machine or the like. It can be easily modified and a large number of highly accurate molds can be manufactured.

Note that in the manufacturing apparatus of the present invention, the drive shaft 2 is connected to each positioning surface 9,
The present invention is also applied to a center core in which the pressing piece for pressing against 9 is linear.

〔Effect of the invention〕

In this way, the present invention forms a shaft insertion hole into which a disk drive shaft is inserted into the center of the center core by the column part of the stationary mold, and at the same time forms a shaft insertion hole into which the disk drive shaft is inserted into the center of the center core, and also allows the shaft part to be inserted into the shaft by the column part and the protrusion of the movable mold. A suppressing piece is formed to align the center of the insertion hole with the center of the disk drive shaft, and a concave strip is formed on the outer circumferential surface of the columnar part to allow the suppressing piece to receive the outer circumferential surface of the disk drive shaft. was formed. The protruding stripes can be formed on the outer circumferential surface of the columnar body by simple processing such as cutting, and the device can be easily manufactured with higher precision than conventional devices. Furthermore, in the case where a large number of units of this manufacturing device are manufactured in order to mass-produce the above-mentioned cores, even if the height of the above-mentioned protruding stripes is larger than the setting method, the upper end surface of the protruding stripes may be The height of the protruding strip can be easily adjusted to a set dimension by cutting or polishing using a milling machine or the like, and a large number of highly accurate manufacturing devices can be easily manufactured.

[Brief Description of the Drawings] Fig. 1 is a sectional view of the main parts of a conventional magnetic sheet device, Fig. 2 is a plan view of the center core, and Fig. 3 is an external perspective view showing a part of the manufacturing mold for the core. , FIG. 4 is a cross-sectional view of a main part of a magnetic disk device equipped with a center core formed by the manufacturing apparatus of the present invention, FIG. 5 is a plan view of the center core, and FIG. FIG. 7 is an exploded sectional view showing an embodiment of the present invention; FIG. 8 is an external perspective view showing a part of a manufacturing mold; FIG. 9 is a sectional view showing the assembled state of the manufacturing molds. 20... Pedestal, 21... Column body portion, 23... First fixed side mold, 24... Second fixed side mold, 27...
First movable mold, 29...Second movable mold, 32
...Curved protruding piece, 35... Convex strip, 36.36...
・Flat surface, 50...Annular space Patent applicant: Sony Corporation Representative Patent attorney: Kodo Koike 1) Sakae Mura -

Claims (1)

[Claims] A fixed side mold with a pillar part erected on a pedestal part, and a substantially circular recess formed in the abutting surface of the fixed mold part with an opening diameter larger than the diameter of the pillar part. and a movable side mold having a projecting piece hanging down from the bottom surface of the recess, and a flat surface extending in a straight line in the axial direction is chamfered on the outer peripheral surface of the columnar part, and the outer periphery is chamfered. A protruding strip extending linearly in the axial direction is formed on the opposite side of the flat surface, and the protruding piece faces the movable mold with a predetermined gap between the protruding strip and the protruding strip. At the same time, the center core is formed by abutting against the stationary mold so that its tip abuts against the pedestal, and injecting synthetic resin into the annular space formed in the recess by this abutment. A manufacturing device for a center core of a magnetic disk device, characterized in that: