JPH09164560A - Mold for injection molding and mold for injection molding of shutter for recording-reproduction medium cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mold a shutter for a recording-reproduction medium cartridge without defective molding such as a weld mark at low cost by forming openings simultaneously in a connection plate which constitutes the shutter in a process of molding the shutter. SOLUTION: A gate 30 is formed in the cavity insertion 11 of a mold for injection molding, a needle 23 for forming openings in a connection plate through the gate 30 is installed in a resin passage, and a gate bank 24 which receives the tip of the needle 23 is installed in a core 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention integrally molds an injection molding die for integrally molding a molded product having an opening, and a shutter for a cartridge of a recording / reproducing medium such as a magnetic disk, an optical disk or a magneto-optical disk. For injection molding molds for

[0002]

2. Description of the Related Art FIG. 7 shows an example of a rewritable optical disk cartridge and is an explanatory view seen from the front side.
FIG. 8 shows an example of a rewritable optical disk cartridge, and is an explanatory view seen from the back side. Generally, a rewritable optical disc cartridge has a resin upper half 1 and a lower half 2 for accommodating a recording / reproducing disc body 5 and outer peripheral portions of these halves 1 and 2 as shown in FIGS. 7 and 8. The shutter 3 is slidably mounted and has a U-shaped cross section. The shutter 3 closes the optical head openings 4 of the halves 1 and 2 when not in use.

FIG. 9 is a perspective view of the shutter. FIG.
0 is a development view of the shutter. FIG. 11 is a cross-sectional view of essential parts showing a state in which the hole of the shutter is locked to the cylindrical convex portion of the slider portion. Shutter 3 in FIGS. 9 and 10
Is a U-shaped cross section in which the side edges of two opposing upper surface plates 3d and lower surface plates 3f are connected by side surface plates 3e,
The cylindrical convex portion 6a of the slider portion 6 is provided in the approximate center of the side plate 3e.
A hole 3a for engaging with is formed (see FIG. 11).

Further, thin-walled portions 3b and 3b are formed at the respective tip portions of the upper surface plate 3d and the lower surface plate 3f. These thin portions 3b and 3b are guided by shutter guide / holding portions 1b and 2b provided on the halves 1 and 2 (FIGS. 7 and 8).
reference). Reference numerals 3c and 3c denote both ends of the side plate 3e. As described above, the shutter 3 is held by the slider portion 6 through the hole 3a and can be smoothly operated by the guides of the lower guide / holding portions 1b and 2b.

[0005]

Conventionally, there are roughly two methods for manufacturing the shutter. One is FIG. 12, FIG.
This is the case as shown in FIG. FIG. 12 is a front view for explaining a conventional example of a shutter molding method, and FIG. 13 is a cross-sectional view of a shutter molded by the molding method of FIG. In FIG. 12, reference numeral 101 denotes a fixed die, and a movable die 102 is provided so as to face the fixed die 101 so as to be able to come into contact with and separate from the movable die 102. Then, the hole 3 of the shutter 3 is provided at the center of the movable mold 102.
A core pin 103 for forming a is installed so as to project toward the fixed mold 101 side. Then, the fixed mold 101
A cavity 104 for molding the shutter 3 shown in FIG. 9 is formed between and the movable mold 102 as shown by a dotted line in the figure.

Further, to the cavity 104, runners 107a, 107b and gates 105a, 105 on the left and right of the drawing are provided.
Resin is injected via b. Note that the symbol PL is an abbreviation for parting line, and in FIG. 12, the seam of the fixed die 101 and the movable die 102 is shown. In the injection-molding die configured as described above, in the mold closed state shown in FIG.
5b and two runners 107a and 107b to supply into the cavity 104. And the cavity 104
After the resin inside has cooled and solidified, the mold is opened and the cavity 10 is opened.
The shutter 3 which is a molded product in 4 is taken out.

However, in this molding method, the core pin 10
The resin P branches at location 3 to generate a weld mark 108, which is a type of molding failure (see FIG. 13). Since the product thickness of this shutter is as thin as about 0.6 mm, the weld mark 108 causes the product to crack, which is not preferable in terms of quality.

Another method will be described with reference to FIGS. FIG. 14 is a front view for explaining another conventional example of the shutter molding method. FIG. 15 is a cross-sectional view showing a step of forming a hole in the shutter molded by the molding method of FIG. Here, the same reference numerals as those in FIGS. 12 and 13 denote the same members (the same applies hereinafter). As shown in FIGS. 14 and 9, the gate 105 for injecting the resin into the cavity 104 corresponds to the hole 3a of the side plate 3e.
It is formed on the fixed die 101 at the center of 4.

In the injection molding die having the above-mentioned structure, the molten resin P in the mold closed state shown in FIG.
Is supplied into the cavity 104 through the gate 105. Then, after the resin in the cavity 104 is cooled and solidified, the mold is opened and the shutter 3 as a molded product in the cavity 104 is taken out. At this stage, the side plate 3e of the shutter 3 does not have the hole 3a.
A hole 3a is made in the side plate 3e with 9 or the like (see FIG. 15). In this molding method, the weld mark 108 does not occur. However, in the process of opening the hole 3a, it is troublesome that the center of the hole 3a needs to be accurately aligned. Further, since the step of forming the hole 3a is performed in a different step from the molding, the cost is increased.

An object of the present invention is to mold a shutter for a recording / reproducing medium cartridge at the same time as forming an opening in a connecting plate constituting the shutter, thereby molding a shutter having no molding defects such as weld marks at low cost. An object of the present invention is to provide a mold for injection molding capable of performing the above.

[0011]

In order to achieve the above object, the injection molding die according to claim 1 is an article to be molded in a space between one die and the other die provided so as to face the die. A mold structure for injection molding in which a predetermined space is provided to form a hot runner, and a valve gate of a hot runner is provided in the one mold and a flat plate shape is formed by penetrating the valve gate inside the hot runner. A needle for forming an opening is provided in a predetermined portion of the article to be molded, and a recess for accommodating the tip of the needle is provided in the other mold.

In the above injection molding die, the needle provided inside the hot runner of one mold is retracted from the valve gate closed position to open the valve gate, and the molten resin is transferred from the hot runner to the one mold. After filling the space provided between this mold and the other mold provided so as to face it, the needle is advanced to close the valve gate after completion of the filling, and further advanced to open an opening in a predetermined portion of the molded product. Form and house the tip of the needle in the recess of the other mold. Therefore,
In a molding process with a molded product having an opening, the opening is opened at the same time, and molding defects such as weld marks do not occur.

An injection molding die of a recording / reproducing medium cartridge shutter according to a second aspect of the present invention comprises a pair of side plates facing each other.
A pair of molds for a recording / reproducing medium cartridge for manufacturing a shutter for a recording / reproducing medium cartridge, which is composed of a connecting plate for connecting these side plates and has a U shape as a whole, and which has an opening in the connecting plate. In a mold for injection molding of a shutter, a valve gate of a hot runner is provided in one of the molds forming the connecting plate, and a needle for penetrating the valve gate and forming an opening in the connecting plate is provided inside the hot runner. And a recess for accommodating the tip of the needle is provided in the other mold.

In the mold for injection molding of the shutter for the recording / reproducing medium cartridge, the needle provided inside the hot runner of one mold is retracted from the valve gate closed position to open the valve gate, and the molten resin is hot. After filling the cavity formed between the runner and the pair of molds, after the filling is completed, the needle is advanced to close the valve gate, and further advanced to form an opening in the resin to be the connecting plate, and to fix the tip of the needle. Store in the recess of the other mold. Therefore, in the step of molding the shutter, an opening is simultaneously opened in the connecting plate forming the shutter, and molding defects such as weld marks do not occur.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, an embodiment of the injection molding die of the present invention will be described. FIG. 1 is a cross-sectional view showing an embodiment of an injection molding die of the present invention, showing a state before filling a cavity with resin. In this figure, reference numeral 10
Is a fixed type in which the cavity insert 11 is incorporated,
A movable die 12 is provided so as to be opposed to the fixed die 10 so as to be able to come into contact with and separate from the fixed die 10. A rectangular plate-shaped core 13 is formed on the movable mold 12 so as to project toward the cavity insert 11 side. A pair of slide cores 14 and 14 are disposed on both sides of the core 13 so as to be slidable along the movable die 12. The slide cores 14 and 14 are formed by a means (not shown) when the die is opened. It is separated from the core 13 and approaches the core 13 when the mold is closed. Reference numeral 15 is a locking block that contacts the inclined surfaces of the slide cores 14 to regulate the sliding of the slide cores 14.

Then, the cavity insert 11 and the core 1
3, a cavity 16 for molding the shutter 3 as shown in FIG. 9 is formed between the slide cores 14, 14. The outer surface of the side plate 3e of the shutter 3 is formed by the cavity insert 11, and the top plate 3d,
The inner surfaces of the lower surface plate 3f and the side surface plate 3e are formed by the core 13, and the outer surfaces of the upper surface plate 3d and the lower surface plate 3f are formed by the slide cores 14.

Further, the fixed die 10 and the cavity insert 1
A resin passage 22 that penetrates 1 and opens at a position corresponding to the central portion of the outer surface of the side surface plate 3e of the cavity 16 is provided. Then, the molten resin is supplied into the cavity 16 through the resin passage 22.

That is, an insertion hole 20 is formed in the fixed mold 10 and the cavity insert 11, and the insertion hole 20 is formed.
The tip of the gate is formed to have a reduced diameter to form a gate 30. A cylindrical body 21 is inserted inside the insertion hole 20, and a needle 23 is provided inside the body 21 so as to be movable along the axis thereof. A part is configured to open and close the gate 30. As shown in FIG. 10, the shape of the gate 30 and the tip of the needle 23 is substantially the same as that of the hole 3a so as to correspond to the hole 3a formed in the substantially central portion of the side plate 3e. It is formed in a circular shape.

The operation of the injection molding die having the above structure will be described below. FIG. 2 is a cross-sectional view showing a state in which the needle is lifted up in FIG. 1, the gate is opened, and the resin is completely filled in the cavity. In the injection molding die configured as described above, when the needle 23 is moved upward in the mold closed state shown in FIG. 1 and the gate 30 is opened as shown in FIG. Molten resin P being supplied to the resin passage 22 in the body 21 through the manifold
Are filled in the cavity 16 through the gate 30.

FIG. 3 is a sectional view showing a state in which the needle is lowered from the state of FIG. 2, the gate is closed, and a hole is opened in the resin. After the filling of the molten resin P into the cavity 16 is completed, as shown in FIG. 3, the needle 23 is moved downward to close the gate 30, and the gate 30 is closed, and at the same time, the molten resin corresponding to the side surface plate 3e is further closed. Of the side plate 3 when it penetrates beyond the thickness part of the core 13 and is inserted into the gate pool 24, which is a recess provided in the upper end of the core 13, in a cut state.
A hole 3a is formed in e.

The inner diameter of the gate reservoir 24, which is a recess, is slightly larger than the outer diameter of the needle 23. After the needle 23 closes the gate 30 and forms the hole 3a in the side surface plate 3e, the remaining resin 25 having substantially the same thickness as the side surface plate 3e and the outer diameter substantially the same as that of the gate 30 is formed as a recess in the gate pool 24. Remain in. The remaining resin 25 is discharged by projecting a projecting pin (not shown) from the core 13 when the mold is opened, or is removed by blowing it away with air. It should be noted that the recess may have a space for accommodating the tip of the needle 23 penetrating beyond the thickness portion of the resin.
It is not limited to the form of FIG.

After the resin in the cavity 16 is cooled and solidified, the mold is opened and the molded product in the cavity 16 is taken out.
This mold opening operation is performed by first fixing the mold 10 and the cavity insert 1.
The movable mold 12 is opened with respect to 1. As a result, the locking block 15 is separated from the inclined surface of each slide core 14, so that the slide core 14 is separated in the left-right direction in FIG. 3 along the movable die 12 by means not shown. Next, the molded product attached to the core 13 is attached to the core 1
By projecting a projecting pin (not shown) from 3, the mold is projected and released.

In the molded product (shutter) 3 thus obtained, the gate can be provided at a position substantially in the center of the developed view of the shutter 3. Therefore, it is possible to fill the resin in the cavity while maintaining good fluidity.

After the resin is completely filled in the cavity, the gate is closed with the needle, and at the same time, the needle penetrates the thick portion of the side plate 3e, so that the hole 3a exists at a predetermined position. A high-quality molded product (shutter) 3 having no weld mark on the side plates (upper surface plate 3d, lower surface plate 3f) can be molded. That is, a separate process for drilling is not required, and a significant cost reduction is possible. Further, since no trace of the gate remains, the appearance is greatly improved and the degree of freedom in design can be improved.

INDUSTRIAL APPLICABILITY The present invention can be applied to general molded products in which a hole is not formed by post-processing and it is desirable that no weld mark is formed. FIGS. 4A to 4D are diagrams showing examples of needle tip shapes. However, since the tip of the needle penetrates the resin wall thickness of the gate part, in addition to the flat shape as in (a), it is rounded into a spherical shape as in (b) and the conical shape as in (c). In some cases, a shape having a low resistance, such as a concave shape with an edge left as in (d), is desirable.

Next, application examples of the present invention will be described.
The present invention can also be applied to the case where a ruler having holes is molded by using a compression molding technique. FIG. 5 is a diagram showing a ruler. The ruler 40 is made of resin, and a plan view is shown in FIG. 5A and a sectional view is shown in FIG. The ruler 40 has a hole 40a near the left short side and a difference scale 40b on the lower long side.

FIG. 6 is a sectional view showing a step of forming the ruler of FIG. When the ruler 40 of FIG. 5 is made of a molded product with less molding strain, a mechanical hot runner is provided above the left side of the cavity 16 for forming the ruler 40 and the needle 23 is moved upward as shown in FIG. When retracted, the gate 30 opens, and the molten resin P is filled from the resin passage 22 into the cavity 16 in a predetermined amount thicker than the final thickness of the ruler 40. As shown in FIG. 6B, when the molten resin P is completely filled in the cavity 16, the movable mold 12 is moved upward with respect to the fixed mold 10 to enter the compression process, and at the same time, the needle 23 is moved downward. The cavity 30 is advanced to the cavity end face 16a, the gate 30 is closed, and the filling of the molten resin P on the hot runner side into the cavity 16 is stopped.

Then, as shown in FIG. 6C, the cavity 16 is further compressed, and at the same time, the needle 23 is moved to the ruler 40.
Until it penetrates the thickness of the
A hole corresponding to the hole 40a of 0 is made. Next, after the resin is cooled and solidified, the molded product (ruler) 40 is released from the hot runner, and the molded product (ruler) 40 is taken out as shown in FIG.

[0029]

The present invention has the following effects due to the above configuration. In the injection molding die according to claim 1, a valve gate of a hot runner is provided in one mold, and the valve gate is penetrated into the hot runner to form an opening in a predetermined portion of a flat plate-shaped molded product. Since a needle is provided for this purpose, and a recess for accommodating the tip of the needle is provided in the other mold, the opening will be opened at the same time in the molding process in a molded product having an opening. It is possible to mold a molded product having no molding defects such as weld marks at a low cost by eliminating the need for separate steps such as. Furthermore, since no trace of the gate remains, the appearance and the degree of freedom in design are improved.

In the injection molding die of the shutter for the recording / reproducing medium cartridge of the second aspect, one of the molds forming the connecting plate is provided with a valve gate of the hot runner, and an opening is formed in the connecting plate through the valve gate. A needle for forming is provided inside the hot runner, and a recess for accommodating the tip of the needle is provided in the other mold, so that in the step of molding the shutter, an opening is simultaneously opened in the connecting plate that constitutes the shutter. Therefore, it is possible to efficiently manufacture shutters by eliminating the need for a separate process such as a hole-punching process outside the molding process, and the product shutters are of high quality and strength without weld marks or other molding defects. Is also high. Further, since no gate marks are left, the appearance is improved and the degree of freedom in design can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an injection molding die of the present invention, showing a state before filling a cavity with a resin.

FIG. 2 is a cross-sectional view showing a state in which the needle is lifted up, the gate is opened, and the resin is completely filled in the cavity in FIG.

FIG. 3 is a cross-sectional view showing a state in which the needle is lowered from the state of FIG. 2, the gate is closed, and a hole is opened in the resin.

FIG. 4 is a diagram showing an example of a needle tip shape.

FIG. 5 is a diagram showing a ruler.

6 is a cross-sectional view showing a step of forming the ruler of FIG.

FIG. 7 is an explanatory view showing an example of a rewritable optical disc cartridge as viewed from the front side.

FIG. 8 is an explanatory view showing an example of a rewritable optical disc cartridge as viewed from the back side.

FIG. 9 is a perspective view of a shutter.

FIG. 10 is a development view of a shutter

FIG. 11 is a cross-sectional view of essential parts showing a state in which the hole of the shutter is engaged with the cylindrical protrusion of the slider portion.

FIG. 12 is a front view for explaining a conventional example of a shutter molding method.

13 is a cross-sectional view of a shutter molded by the molding method of FIG.

FIG. 14 is a front view for explaining another conventional example of the shutter molding method.

FIG. 15 is a cross-sectional view showing a step of forming a hole in a shutter molded by the molding method of FIG.

[Explanation of symbols]

3 ... Shutter, 3a ... Hole (opening), 3d ... Top plate (side plate), 3e ... Side plate (connecting plate), 3f ... Bottom plate (side plate), 10 ... Fixed mold (one mold), 11 ... Cavity included Child, 12 ... Movable mold (other mold), 13 ... Core, 14 ... Slide core, 16 ... Cavity (space part), 20 ... Insertion hole, 21 ... Body, 22 ... Resin passage (hot runner),
23 ... Needle, 24 ... Gate Reservoir (Concave), 30 ...
Gate (valve gate), 40 ... Ruler (molded product), 4
0a ... hole (opening).

Claims (2)

[Claims] 1. A mold structure for injection molding, comprising a predetermined space for forming a molded product in a space between one mold and the other mold provided so as to face the mold. A valve gate for the hot runner is provided in one mold, and a needle is provided inside the hot runner for penetrating the valve gate to form an opening in a predetermined portion of a flat plate-shaped molded product, and A mold for injection molding, characterized in that the mold is provided with a recess for accommodating the tip of the needle. 2. A pair of side plates facing each other and a connecting plate connecting these side plates, and having a U shape as a whole,
In a mold for injection molding of a shutter for a recording / reproducing medium cartridge, which comprises a pair of molds, for manufacturing a shutter for a recording / reproducing medium cartridge having an opening in the connecting plate, one mold for forming the connecting plate is used. A valve gate for the hot runner is provided, a needle for penetrating the valve gate to form an opening in the connecting plate is provided inside the hot runner, and a recess for accommodating the tip of the needle is provided in the other mold. A mold for injection molding of a shutter for a recording / reproducing medium cartridge, which is characterized in that: