JPH1055608A - Resin turntable and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the producing method of a resin turntable which is capable of working a holding pin holding a center yoke and a pin inserting hole with high accuracy and with which burrs are hardly produced at the periphery of the stamping trance of the holding pin. SOLUTION: A first mold 23 in which a plurality of holding pins 21 which are inserted into pin inserting holes 22 formed on the mold surface and are protruded to a molding space 30 to hold the outer periphery of a center yoke 42 are provided and a second mold 24 to be fitted to the first mold 23 are prepared. Next, after the center yoke 42 is made to be held by the holding pins 21 to be protruded from the mold surface of the first mold 23, both molds 23, 24 are fitted and the center yoke 42 being in a state in which it is held by the holding pins 21 and resin are integrally molded by injecting resin into the molding space 30 and by making them to be fixed. Next, a molded part is released from the molds by removing the both molds 23, 24 and sectional shapes of the holding pins 21 are formed to be circular shapes and also shapes of pin inserting holes 22 into which the holding pins 21 are to be inserted are formed to be circular shapes corresponding to the sectional shapes of the holding pins 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a center yoke insert type resin turntable used for a spindle of a CD-ROM drive, a DVD drive or the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, as a turntable used for a spindle of a CD-ROM drive, a DVD drive or the like, a resin turntable which is inexpensive and easy to mold as compared with a metal turntable has been increasingly required. Among such resin turntables, a center yoke insert type resin turntable in which a donut-shaped center metal fitting (hereinafter, referred to as a “center yoke”) is insert-molded at the center of the upper surface has been widely used. I have.

In the center yoke insert type resin turntable, as shown in FIG. 5, a turntable body 41 is formed in a disk shape, and a truncated conical disk centering portion for centering a compact disk or the like is provided at the center of the upper surface thereof. 40 are formed. At the center of the disc centering portion 40, a cylindrical shaft insertion hole 43 having a shaft insertion hole 43 penetrating vertically is formed.
a is formed. Then, the slope portion 44 of the disc centering portion 40 and the shaft insertion hole portion 43a
A donut disk-shaped center yoke 42 is insert-molded concentrically with the shaft insertion hole 43a, and as shown in FIG. Is formed. Then, the disk centering unit 40
A plurality of cutouts 47 are formed in the inclined surface portion 44 (four in FIG. 5), and the outer peripheral wall of the center yoke 42 is partially exposed from the cutouts 47.

In the resin turntable, a motor shaft (not shown) is press-fitted into a shaft insertion hole 43, and a compact disk 45 is mounted on the upper surface thereof, and the resin turntable rotates.
The compact disk 45 is rotated. When the compact disc 45 is mounted on the resin turntable, the compact disc 45 is mounted on the resin turntable such that the compact disc 45 is dropped from a slightly higher position. At this time, the inner diameter hole 46 of the compact disc 45 slides on the inclined surface 44 of the disc centering portion 40 having a truncated cone shape as a guide, and the inner diameter hole 46 is fitted with the disc centering portion 40, and the compact disc 45 is inserted into the resin turntable. Is positioned and mounted at the center of the

[0005] The resin turntable is manufactured as follows. That is, as shown in FIG. 7, a first mold 32 provided with a holding pin 31 for holding a center yoke 42 in a molding space 30, and a second mold 33 mating with the first mold 32. Prepare The holding pin 3
As shown in FIG. 8, a plurality of reference numerals 1 are arranged at equal intervals at positions on a circumference surrounding the center yoke 42. Further, the cross section of the holding pin 31 is formed in a quadrangular shape (substantially fan-shaped) in which the inner side and the outer side each form an arc. Then, the holding pin 31 is inserted into a pin insertion hole 34 formed in the mold surface of the first mold 32 in a substantially fan shape corresponding to the cross-sectional shape of the holding pin 31, and the molding space 30 is formed.
It protrudes into. The concavely curved inner surface of the holding pin 31 contacts the outer peripheral wall of the center yoke 42 to hold the center yoke 42.
7 and 8, reference numeral 48 denotes an ejector pin which protrudes into the molding space 30 so as to advance and retreat, and pushes out a molded product from the molding space 30. Next, after holding the center yoke 42 on the holding pin 31 of the first mold 32, the two dies 32 and 33 are combined, and a resin is injected into the molding space 30 to be solidified. The yoke 42 and the resin are integrally formed. After that, the first mold 32 and the second mold 3
3 and the ejector pins 48 are protruded to the left side as shown in FIG. 7 and removed from the mold, whereby the center yoke insert type resin turntable shown in FIGS. 5 and 6 is formed. In the resin turntable thus formed, traces of the plurality of holding pins 31 holding the center yoke 42 are formed as the plurality of cutouts 47 on the slope 44 of the disk centering portion 40. is there. In FIG. 7, reference numeral 35 denotes a gate for resin injection.

[0006]

However, in the above conventional example, the holding pin 3 for holding the center yoke 42 is not used.
1 is formed in a substantially fan-shaped cross section.
The pin insertion hole 34 through which is inserted is also formed in a substantially sector shape corresponding thereto. In this case, if the holding pin 31 having a substantially sectorial cross section and the pin insertion hole 34 having a substantially sector shape are not properly aligned, a minute gap is formed between the holding pin 31 and the pin insertion hole 34, and the inside of the molding space 30 is formed. When the resin is injected into the small gap, the resin enters the minute gap and solidifies. Then, burrs are formed just around the notch portion 47 (the trace of the holding pin 31) formed in the slope portion 44 of the disk centering portion 40. With such burrs, when the compact disc 45 is mounted on the resin turntable, the inner diameter hole 46 of the compact disc 45 is caught by the burrs and does not slide smoothly on the slope portion 44 of the disc centering portion 40. Therefore, there is a problem that the positioning of the compact disk 45 is hindered. However, as described above, it is extremely difficult to machine the holding pin 31 into a substantially sectoral cross-sectional shape with high precision, and also to machine the pin insertion hole 34 with high precision into a substantially sectorial shape in accordance with the above. Therefore, it was difficult to form the disk centering portion 40 so that no burr was formed on the slope portion 44. Further, in the above-mentioned conventional example, since the outer periphery of the center yoke 42 is held and held by the holding pin 31 having a substantially fan-shaped cross section (large cross section), the center yoke 42 is formed integrally with the resin. The contact area between the outer peripheral wall and the resin is reduced, and the center yoke 42 is easily detached from the disc centering portion 40. In addition, each of the cutouts 47 has a square shape and is easily cracked at the corners, and the cutout 47 having a large cross-sectional shape is formed so that the area of the slope 44 is small. When the inner diameter hole 46 of the compact disk 45 slides on the slope 44 of the portion 40, the surface pressure of the pressing force acting on the slope 44 increases, so that a crack or the like occurs at the corner of each notch 47. Cheap. For this reason, in the conventional resin turntable, the slope portion 44 becomes rough due to the cracks and the like, and the compact disc 45
Is difficult to slide smoothly.

The present invention has been made in view of such circumstances, and the center yoke is hardly disengaged, and the holding pin for holding the center yoke and the pin insertion hole can be machined with high precision, so that the holding pin comes off. It is an object of the present invention to provide a resin turntable in which burrs are hardly generated around a trace and a method of manufacturing the same.

[0008]

In order to achieve the above object, according to the present invention, a disc centering portion having a truncated cone shape is protruded at the center of the upper surface, and a shaft insertion hole is formed in the center of the disc centering portion in the axial direction. A resin-made turntable main body, and a donut-shaped center metal fitting embedded in the disk centering part in a state of being arranged concentrically with the shaft insertion hole, wherein the disk centering part has a truncated cone. A first gist is a resin turntable in which a plurality of circular recesses having a circular cross section extending downwardly from the inclined surface along the outer peripheral surface of the center fitting are formed at predetermined intervals, A frustoconical disk centering portion is formed in the shaft, and a donut-shaped disk centering portion is formed between the disk centering portion and the outer diameter portion of the shaft insertion hole. Centers bracket A method of manufacturing a resin turntable which is insert-molded, projecting into the molding space is inserted into the pin insertion hole formed in the mold surface,
A step of preparing a first mold provided with a plurality of holding pins for holding the outer periphery of the center metal fitting, and a second mold matching the first mold; After the center metal is held by the protruding holding pins, a step of combining the first mold and the second mold is performed, and a resin is injected into the molding space to be solidified and held by the holding pins. And a step of separating the first die and the second die to release the molded product, and forming the holding pin into a circular cross-sectional shape. A second gist of the present invention is a method of manufacturing a resin turntable in which a pin insertion hole into which the holding pin is inserted is formed in a circular shape corresponding to the cross-sectional shape of the holding pin.

That is, according to the method of manufacturing a resin turntable of the present invention, a holding pin is formed in a circular shape in cross section, and a pin insertion hole of a first type through which the holding pin is inserted is formed in a cross section of the holding pin. It is formed in a circular shape corresponding to the shape. For this reason, compared to the conventional manufacturing method in which the holding pin is formed in a substantially sector shape in cross section and the pin insertion hole is formed in a substantially sector shape corresponding to the substantially sector shape in cross section of the holding pin.
The dimensions of the holding pin and the pin insertion hole can be easily adjusted with high precision. Therefore, it is difficult to form a gap between the holding pin and the pin insertion hole, and it is difficult for the resin to flow into the gap when the resin is injected into the molding space. For this reason, the generation of burrs around the trace of the retaining pin formed on the slope of the disk centering portion is prevented. Further, according to the manufacturing method of the present invention, since the shape of the holding pin and the pin insertion hole are both simple and easy to work, the manufacturing cost of the mold is reduced in this manufacturing.
Moreover, since the center pin is held integrally with the resin while the outer periphery of the center metal is held by the holding pin having a circular cross section, the contact area between the holding pin and the center metal is reduced, and the contact area between the resin and the center metal is reduced accordingly. And the center metal is less likely to come off the molded product.
Moreover, the trace of the retaining pin is circular in cross section,
The shape of the hole is such that there is no sharp corner and the crack is hardly formed around the hole, and the area of the hole of the retaining pin is smaller toward the lower end of the slope portion of the disk centering portion (the hole has a cross-sectional shape). The resin turntable obtained can be used for a long period of time since the surface pressure of the pressing force received by the slope portion when the inner diameter hole of the compact disk slides on the lower end side of the slope portion is small. There is also an advantage that cracks and the like are hardly generated around the void. Further, in the resin turntable of the present invention, a circular recess having a circular cross section that is less likely to generate burrs is formed on the periphery of the disk centering portion, and since the periphery of the disk centering portion is smooth, a compact disk or the like is mounted on the resin turntable. In doing so, there is no problem that the inner diameter hole of the compact disk or the like is caught on the inclined surface of the disk centering portion and the positioning of the compact disk or the like is hindered.

[0010]

Next, embodiments of the present invention will be described in detail.

FIGS. 1 and 2 show a center yoke insert type resin turntable formed by the method of manufacturing a resin turntable of the present invention. This is basically the same as that shown in FIGS. 5 and 6, and the same parts are denoted by the same reference numerals. This resin turntable has no notch 47 in the slope portion 44 of the disc centering portion 40, and instead has four circular holes (recesses) 2
Zeros are formed at regular intervals along the outer peripheral wall of the center yoke 42.

In the present invention, the resin turntable is manufactured as follows.

That is, as shown in FIG.
Mold 23 and a second mold 24 that fits the first mold 23
And prepare. The first die 23 is provided with four holding pins 21 that are inserted into pin insertion holes 22 formed in the die surface, protrude into the molding space 30, and hold the outer periphery of the center yoke 42. I have. In the present invention, as shown in FIG. 4, the holding pin 21 is formed in a circular cross section, and a pin insertion hole 22 through which the holding pin 21 is inserted.
Are also formed in a circular shape corresponding to the cross-sectional shape of the holding pin 21. The holding pins 21 are provided at four locations at equal intervals so as to surround the center yoke 42, and the four holding pins 21 radially hold the outer peripheral wall of the center yoke 42. ing.
3 and 4, reference numeral 48 denotes an ejector pin that projects into the molding space 30 so as to be able to advance and retreat, and pushes out a molded product from the molding space 30.

After the center yoke 42 is held by the four holding pins 21 protruding from the mold surface of the first mold 23, the first mold 23 and the second mold 24 are joined. The resin is injected into the molding space 30 and solidified, and the center yoke 42 held by the holding pins 21 and the resin are integrated. After that, the first mold 23 and the second mold 2
4 and the ejector pin 48 is projected leftward as shown in FIG. 3 to release the molded product.

As described above, the center yoke insert type resin turntable shown in FIGS. 1 and 2 is manufactured. The resin turntable manufactured in this manner is attached to the slope 44 of the disc centering section 40 by 4
Circular holes 20 (traces of the holding pins 21) are formed along the outer peripheral wall of the center yoke 42.

According to the above-described manufacturing method, both the holding pin 21 and the pin insertion hole 22 can be easily processed with high precision and aligned. Therefore, it is difficult to form a gap between the holding pin 21 and the pin insertion hole 22, and it is difficult for the resin to flow into the gap when the resin is injected. Is prevented. For this reason, in the resin turntable molded by the above-described method, when the compact disc or the like is mounted on the resin turntable, the inner diameter hole of the compact disc or the like is caught on the slope portion 44 of the disc centering portion 40, and the compact disc is compacted. Does not occur. In addition, the contact area between the center yoke 42 and the resin is large, so that the center yoke 42 is unlikely to come off the disk centering portion 40. Further, since the trace of the holding pin 21 has a circular cross-sectional shape and does not have a sharp corner, cracks and the like hardly occur around the trace even when used for a long time.

In the above embodiment, the center yoke 42 is held by the four holding pins 21. However, the present invention is not limited to this, and the center yoke 42 is held by the three holding pins 21. You can do it. When the center yoke 42 is held by the three or four holding pins 21 as described above, the number of the holding pins 21 is reduced, and the processing of the mold is further reduced. In addition, there is an advantage that the contact area between the resin and the center yoke 42 is increased, and the center yoke 42 is harder to come off from the molded product. Of course, the holding pin 21
May be 5 or more.

[0018]

As described above, according to the method of manufacturing the resin turntable of the present invention, the holding pin is formed to have a substantially fan-shaped cross-section and the pin insertion hole is formed to have a substantially cross-sectional shape of the holding pin. Compared with a manufacturing method of forming a substantially sector shape corresponding to a sector shape, the holding pin and the pin insertion hole can be easily processed with high precision to match the dimensions of both. Therefore,
It is difficult to form a gap between the holding pin and the pin insertion hole, and it is difficult for the resin to flow into the gap when the resin is injected into the molding space. For this reason, the generation of burrs around the trace of the retaining pin formed on the slope of the disk centering portion is prevented. Further, according to the manufacturing method of the present invention, since the shape of the holding pin and the pin insertion hole are both simple and easy to work, the manufacturing cost of the mold is reduced in this manufacturing. Moreover, since the center pin is held integrally with the resin while the outer periphery of the center metal is held by the holding pin having a circular cross section, the contact area between the holding pin and the center metal is reduced, and the contact area between the resin and the center metal is reduced accordingly. Becomes larger,
There is also an advantage that the center fitting is not easily detached from the molded product. In addition, the retaining pin has a circular cross-section with a circular cross-section, and there is no squared portion in the depressed area, and it is difficult to generate cracks or the like around the depressed area. When the inner diameter hole of the compact disc slides on the lower end side of the slope, the surface pressure of the slope is smaller at the lower end side of the slope part (because the trace is circular in cross section). Therefore, the obtained resin turntable also has an advantage that cracks and the like are hardly generated around the void even when used for a long time. Also, in the resin turntable of the present invention, a circular recess having a circular cross section that is less likely to generate burrs is formed on the periphery of the disk centering portion, and since the periphery of the disk centering portion is smooth, a compact disk or the like is mounted on the resin turntable. In doing so, the problem that the inner diameter hole of the compact disk or the like is caught on the slope of the disk centering portion and the positioning of the compact disk or the like is hindered does not occur.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a resin turntable manufactured by the manufacturing method of the present invention.

FIG. 2 is an AA sectional view showing the resin turntable.

FIG. 3 is an explanatory view showing the steps of the production method of the present invention.

FIG. 4 is a view as seen from the direction of arrows BB, showing the above steps.

FIG. 5 is a perspective view showing a conventional resin turntable.

FIG. 6 is a sectional view taken along the line A′-A ′ showing the resin turntable.

FIG. 7 is an explanatory view showing a manufacturing process of the conventional resin turntable.

FIG. 8 is a view on arrow B'-B 'showing the above process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Holding pin 22 Pin insertion hole 23 1st type 24 2nd type 30 Molding space 42 Center yoke

Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location // B29K 101: 12 705: 00 B29L 31:34 (72) Inventor Yuichi Yamamoto Komaki City, Aichi Prefecture Kita Toyama 3600, Gezu Tokai Rubber Industries Co., Ltd. No. 6-2 in Mitsubishi Electric Engineering Co., Ltd.

Claims (3)

[Claims] 1. A resin turntable body having a truncated conical disk centering portion projecting at the center of the upper surface and a shaft insertion hole formed in the center of the disk centering portion in the axial direction, and concentric with the shaft insertion hole. A donut disk-shaped center metal fitting embedded in the disk centering part in a state of being arranged in a shape, and having the disk centering part downward from the truncated cone-shaped inclined surface along the outer peripheral surface of the center metal fitting. A resin turntable, wherein a plurality of recesses having a circular cross section and extending are formed at predetermined intervals. 2. A frustum-shaped disk centering portion is formed at the center of the upper surface of the turntable body, and a donut-shaped center metal is insert-molded between the disk centering portion and the outer diameter portion of the shaft insertion hole. A method for manufacturing a resin turntable, comprising a first pin provided with a plurality of holding pins that are inserted into pin insertion holes formed in a mold surface, protrude into a molding space, and hold an outer periphery of the center fitting. A step of preparing a mold and a second mold to be fitted with the first mold; holding a center metal on a holding pin projecting from a mold surface of the first mold; A step of combining the second mold with the second mold, a step of injecting and solidifying the resin into the molding space, and a step of integrally molding the resin with the center metal held by the holding pins;
The mold is separated from the mold, and the molded product is released from the mold.
A method for manufacturing a resin turntable, wherein the holding pin is formed in a circular cross section and the pin insertion hole through which the holding pin is inserted is formed in a circle corresponding to the cross section of the holding pin. 3. The method for manufacturing a resin turntable according to claim 2, wherein the center fitting is held by three or four holding pins.