JP2002127200A - Molding method for optical disk, and die device for optical disk molding which is used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly cool a resin in a cold sprue bush while the resin is surely prevented from leaking, and the resin in a hot tip is kept under a molten state, when a plurality of optical disks are manufactured by a semi-hot runner method. SOLUTION: The hot tip 36 having a material passage 38 which is heated by a heater 39 is connected to the cold sprue bush 26 having a cold sprue 31 which communicates with a product cavity 3. For the connection, a cylindrical nozzle core 43 is slidably incorporated in the distal end section of the hot tip 36. The nozzle core 43 has a material passage 45 which communicates the material passage 38 in the hot tip 36 and the cold sprue 31. In the material passage 45, pressure-receiving surfaces 48 and 49 are provided, and by the pressure of the resin which is applied to the pressure-receiving surfaces 48 and 49, the nozzle core 43 hits the bearing surface 30 of the cold sprue bush 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a CD (compact disk) and a DVD (digital video disk).
The present invention relates to a method for molding an optical disk such as an optical disk and a mold apparatus for molding an optical disk used in the method.

[0002]

The substrate of an optical disk such as a DVD is generally injection-molded with a resin.
In this molding, the fixed mold and the movable mold attached to the fixed plate and the movable plate of the injection molding machine are closed, and a product cavity is formed between the fixed mold and the movable mold.
After filling the product cavity with the molten thermoplastic resin, which is the molding material injected from the nozzle of the injection molding machine, and solidifying the resin in the product cavity, that is, the optical disk, the fixed mold and the movable mold were opened and molded. I try to take out the optical disk.

Conventional dies for molding optical disks generally take one piece, that is, mold optical disks one by one in one molding operation. However, this method has poor productivity. As described in, for example, Japanese Patent Application No. 227883, a multi-cavity mold for molding a plurality of optical disks by one molding has been proposed. further,
The mold apparatus described in the above publication employs a hot runner method in which a thermoplastic resin in a material passage to a product cavity is always heated and kept in a molten state in order to further improve productivity. Further, a hot chip connected to a manifold having a branch of the material passage and a sprue bush having a material passage (cold sprue) facing the product cavity are connected to each other. The resin is heated by a heater and kept in a molten state at all times, while the resin in the material passage of the sprue bush is cooled and solidified together with the resin in the product cavity. This is a method called a so-called semi-hot runner. When the optical disk molded by opening the mold is taken out, the solidified resin in the sprue bush is separated from the molten resin in the hot chip. In the mold device described in the above publication, in order to absorb a dimensional change due to thermal expansion of a hot tip or the like and to prevent resin leakage, a hot tip nozzle is fitted to a hole-shaped cylindrical surface fitting portion formed in a sprue bush. Are fitted in the axial direction to connect the hot tip and the sprue bush.

However, in such a structure in which the hot tip nozzle is axially fitted into the hole-shaped cylindrical surface fitting portion of the sprue bush, the resin in the sprue bush to be cooled and solidified can be quickly cooled. There is no problem. This is because a part of the hot chip which has a heater and is heated enters the sprue bush to be cooled, and heat is easily transmitted from the hot chip to the sprue bush. If the cooling of the resin in the sprue bush is delayed, it may hinder the shortening of the molding cycle, and the resin in the sprue bush may not be reliably separated from the resin in the hot chip.

The present invention is intended to solve such a problem, and it is possible to rapidly cool and solidify the molding material in a sprue bush while keeping the molding material in a hot chip in a molten state. In addition, an object of the present invention is to provide a method of molding an optical disk capable of reliably preventing leakage of a molding material and a mold device for molding an optical disk used in the method.

[0006]

According to a first aspect of the present invention, a plurality of product cavities for closing a plurality of molds and forming an optical disc between the molds are formed. A manifold having a branch of the material passage, and a hot tip connected to the manifold when filling each of the product cavities with a thermoplastic molding material through a material passage having a branch formed inside one mold body. The molding material is filled in the product cavity by sequentially passing through the material passage in the sprue bush, and the molding material in the material passage of the manifold and the hot chip is heated to be always in a molten state, while the material of the sprue bush is kept. In the method for molding an optical disk, the molding material in the passage is cooled and solidified together with the molding material in the product cavity. A cylindrical nozzle insert provided slidably at the tip of the tip and slidably into and away from the sprue bush abuts against the sprue bush by the pressure of the molding material in the material passage of the nozzle insert. The molding material flows from the material passage of the hot tip to the material passage of the sprue bush via the material passage of the nozzle insert.

A dimensional change due to thermal expansion or the like is unavoidable in a hot tip or a sprue bush, and the hot tip is heated, while the sprue bush is cooled. The change is
The hot tip and the sprue bush are different. However, the nozzle insert slidably provided at the tip of the hot tip hits the sprue bush due to the pressure of the molding material, and the contact state between the nozzle insert and the sprue bush is always reliably maintained. Leakage of the molding material from between the hot tip and the sprue bush is prevented. In addition, the contact area between the nozzle insert on the hot tip side and the sprue bushing can be reduced by contacting the sprue bushing with the sprue bushing. The molding material inside cools quickly and solidifies.

According to a second aspect of the present invention, there is provided, in order to achieve the above-mentioned object, a plurality of molds which are mutually moved to open and close to form a plurality of product cavities for forming an optical disk when the mold is closed. An optical disc molding die apparatus, wherein a material passage branching from one inlet to the plurality of product cavities is formed inside one of the molds, wherein the mold having the material passage is provided in the product cavity. , A manifold forming a branch of the material passage and having heating means for heating the material passage, a material passage connected to the manifold and communicating with an outlet of the material passage, and the material passage A hot chip having heating means for heating the material, and a material passage and a product cavity of the hot chip provided on the base. A sprue bush having a material passage, and a tip end of the hot tip is provided with a cylindrical nozzle insert having therein a material passage communicating the material passage in the hot tip and the material passage in the sprue bush. It is provided slidably and freely to and away from the sprue bush, and the pressure of the molding material in the material passage in the material passage of the nozzle insert acts in the direction in which the nozzle insert moves toward the sprue bush. A pressure receiving surface is formed.

With this mold apparatus, the method of molding an optical disk according to the first aspect of the present invention can be performed.

According to a third aspect of the present invention, in the optical disk molding die apparatus according to the second aspect of the present invention, a minimum diameter portion is formed at an axially intermediate portion of the material passage in the nozzle insert. The part closer to the sprue bush than the minimum diameter part is a tapered part whose diameter increases toward the sprue bush, and the part opposite to the minimum diameter part has a taper whose diameter increases toward the opposite side to the sprue bush. A pressure receiving surface is formed.

When the pressure of the molding material is applied to this tapered pressure receiving surface, the nozzle insert strikes the sprue bush. Also, when releasing the molded optical disk and the molding material solidified in the sprue bush, the molding material on the hot tip side and the molding material on the sprue bushing at the minimum diameter portion of the material passage in the nozzle insert. And are separated. The minimum diameter portion is located at an axially intermediate portion in the cylindrical nozzle insert, and therefore, the molding material is separated inside the nozzle insert.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the optical disk molding method of the present invention and an optical disk molding die apparatus used in the method will be described below with reference to the drawings. First, the configuration of the optical disk molding die apparatus will be described. Reference numeral 1 denotes a fixed mold, and 2 denotes a movable mold. The fixed mold 1 and the movable mold 2, which are molds, move in the vertical direction (mold opening and closing direction) in the figure to open and close, and form a product cavity for forming an optical disc when the mold is closed. 3 are formed between each other.

The fixed mold 1 has a fixed mold plate 6 as a base and a fixed side support as a base fixed to a surface (upper surface in the drawing) of the fixed mold plate 6 opposite to the movable mold 2. A plate 7 and a fixed-side mounting plate 9 fixed via a spacer block 8 to a surface of the fixed-side receiving plate 7 opposite to the movable mold 2 are provided. This fixed side mounting plate 9
Is attached to a fixed platen of an injection molding machine (not shown). A manifold 11 is disposed in a space between the fixed-side receiving plate 7, the spacer block 8, and the fixed-side mounting plate 9. A support block 12 is interposed between the manifold 11 and the fixed-side receiving plate 7 and the fixed-side mounting plate 9.

A cylindrical hot sprue bush 13 is fixed to a surface of the manifold 11 on the fixed side mounting plate 9 side. This hot sprue bush 13
, Which penetrates the fixed side mounting plate 9 and is connected to a nozzle of an injection molding machine. The inside of the hot sprue bush 13 forms a hot sprue 14 which is an inlet of a material passage. On the outer periphery of the hot sprue bush 13, a heater 15 as a heating means is provided, and a cylindrical heater cover 16 for covering the heater 15 is provided. Further, a locate ring 17 is fixed to the outer surface of the fixed-side mounting plate 9 so as to surround the hot sprue bush 13.

The manifold 11 has a runner 21 which is a branch of a material passage formed therein. That is, the runner 21 branches off from one inlet 21a communicating with the hot sprue 14, and has two outlets 21b respectively corresponding to the two product cavities 3 on the surface on the fixed mold receiving plate 7 side. are doing. Further, the manifold 11 is provided with a heater 22 as heating means for heating the runner 21.

Further, two cold sprue bushes 26, which are sprue bushes, are fixed to the fixed receiving plate 7 so as to correspond to the two product cavities 3, respectively. The cold sprue bush 26 has a recess 27 formed on the surface of the fixed side receiving plate 7 on the side of the manifold 11.
, But the cylindrical protrusion 28
The projecting portion 28 further penetrates the fixed-side mold plate 6 from the fixed-side receiving plate 7. An assembly recess 29 is formed on the cold sprue bush 26 on the manifold 11 side. The bottom surface of the mounting recess 29 on the side of the fixed mold plate 6 is a seat surface 30 formed of a plane orthogonal to the mold opening and closing direction. Further, a cold sprue 31 is formed in the cold sprue bush 26 as a material passage extending from the seat surface 30 to the tip end surface of the projection 28. The cold sprue 31 communicates with the product cavity 3 and has a tapered shape whose diameter increases toward the product cavity 3. Further, the cold sprue 31 is formed with a temperature control passage 32 for passing a temperature control fluid such as cooling water.

A hot chip 36 is connected to the vicinity of the two outlets 21b of the runner 21 in the manifold 11. More specifically, a flange portion 37 formed at one end of the hot tip 36 is sandwiched and fixed between the manifold 11 and the cold sprue bush 26, and the hot tip 36 is located inside the mounting recess 29 of the cold sprue bush 26. Has been inserted. In the hot tip 36, a material passage 38 communicating with the outlet 21b of the runner 21 is formed. A heater 39 as a heating means for heating the material passage 38 is provided on the outer periphery of the hot chip 36, and a cylindrical heater cover 40 for covering the heater 39 is provided.

At the cold sprue bush 26 side, that is, on the downstream end of the material passage 38 of the hot tip 36, a nested fitting portion 41 is formed. The nested incorporation portion 41 has a cylindrical shape whose axial direction is the mold opening and closing direction, but is slightly larger in diameter than other portions of the material passage 38, and A step surface 42 is formed at the end of the. Then, a cylindrical nozzle insert 43 is slidably fitted in the mold opening and closing direction and incorporated into the insert inserting portion 41. The tip end face of the nozzle insert 43 abuts on the seat surface 30 of the cold sprue bush 26 so as to be able to freely contact and separate from the seat surface 30, and the movement in the direction opposite to the seat surface 30 is regulated by the step surface 42. Although the outer peripheral surface of the nozzle insert 43 is a cylindrical surface, the distal end side that contacts the seat surface 30 is a tapered portion 44. The inside of the nozzle insert 43 is a material passage 45 for communicating the material passage 38 in the hot tip 36 with the cold sprue 31 in the cold sprue bush 26. A pinpoint portion 46 is formed by the minimum diameter portion located in the middle of the direction and near the seating surface 30, and a portion closer to the seating surface 30 than the pinpoint portion 46 becomes larger in diameter toward the seating surface 30 side. It has a tapered portion 47. Also, the pinpoint part 46
The part on the opposite side is also a tapered part whose diameter increases in the direction opposite to the tapered part 47, and this tapered part forms one pressure receiving surface 48. Further, a tapered pressure receiving surface 49 whose diameter increases toward the step surface 42 is also formed at the end of the material passage 45 on the step surface 42 side. The projected area on a plane orthogonal to the mold opening / closing direction is substantially larger in the pressure receiving surfaces 48 and 49 than in the tapered portion 47. Therefore, the pressure of the molding material applied to the nozzle insert 43 acts in the direction in which the nozzle insert 43 moves toward the seat surface 30 due to the pressure applied to the pressure receiving surfaces 48 and 49. The maximum diameter of the tapered portion 47 is slightly smaller than the minimum diameter of the cold sprue 31.

The fixed mold plate 6 is fixed to the fixed receiving plate 7.
And a cavity block 52 as two cavity forming members fitted inside the positioning frame 51. These cavity blocks 52 form the product cavities 3 respectively. An annular outer stamper retainer 53 is detachably attached to the outer peripheral portion of the cavity block 52, and a cylindrical inner peripheral stamper retainer 54 is detachably attached to the inner peripheral portion. These stamper holders 53 and 54 are used to form a cavity block and a lander on the optical disk.
It is for holding detachably to 52. Further, an intermediate cylinder 55 is fitted in a cylindrical inner peripheral stamper retainer 54 penetrating the cavity block 52, and the projecting portion 28 of the cold sprue bush 26 is fitted in the intermediate cylinder 55. The inner stamper retainer 54 and the intermediate cylinder 55 form a part of the product cavity 3. Further, a temperature control passage 56 for passing a temperature control fluid such as cooling water is formed in the cavity block 52.

The movable die 2 includes a movable mounting plate 61 mounted on a fixed platen of an injection molding machine, a movable receiving plate 62 fixed to a surface of the movable mounting plate 61 on the fixed die 1 side. Fixed type 1 of this movable side receiving plate 62
And a movable mold plate 63 fixed to the side surface. The movable mold plate 63 includes a positioning frame 64 fixed to a surface of the movable mold plate 72 on the fixed mold 12 side, and a core block 65 as two cavity forming members fitted inside the positioning frame 64. Consists of These core blocks 65
Each of the product cavities 3 is formed.
The positioning frame 64 is taperedly fitted to the positioning frame 51 of the fixed die 1. The core block 65 has a temperature control passage 66 for passing a temperature control fluid such as cooling water.
Are formed.

Further, on the outer peripheral portion of the core block 65,
The butting ring 67 is fitted. The abutment ring 67 is used to hold the outer peripheral stamper presser on the fixed mold 1 side when the mold is closed.
53 to form an outer peripheral surface of the product cavity 3.

Further, a cylindrical air outlet / inlet 71 is fixed to the inner peripheral portion of the core block 65 in a penetrating state, and a cylindrical protrusion sleeve 72 is provided on the inner peripheral side of the air outlet / inlet 71. Is fitted slidably in the mold opening and closing direction for a predetermined range, and a cylindrical gate cut sleeve 73 is fitted on the inner peripheral side of the protruding sleeve 72 so as to be slidable in the mold opening and closing direction for a predetermined range. A protruding pin 74 is slidably fitted in the gate cut sleeve 73 in a predetermined range in the mold opening and closing direction. The protruding sleeve 72 and the gate cut sleeve 73 are
It is urged to the side opposite to the fixed mold 1 by 5,76. The gate cut sleeve 73 has a receiving portion 77 projecting through the movable-side mounting plate 61. This receiving part
The gate cut sleeve 73 is moved to the fixed mold 1 side when the 77 is pressed by a pressing rod (not shown) provided in the injection molding machine. Also,
The protruding pins 74 are fixed to a protruding plate 78 provided in the movable-side mounting plate 61. When this protruding plate 78 is pressed by another pressing rod (not shown) provided in the injection molding machine, the protruding pin
74 moves to the fixed mold 1 side. further,
Interlocking pin fixed to the protruding plate 78 (not shown)
By pressing the protruding sleeve 72, the protruding sleeve 72 moves to the fixed mold 1 side.

The gate cut sleeve 73 is
It is fitted into the intermediate cylinder 55 of the fixed mold 1 so as to be able to be inserted and removed so as to form an opening at the center of the optical disk. Therefore, the protruding sleeve 72 and the air blowing insert 71 located on the outer peripheral side of the gate cut sleeve 73 form a part of the product cavity 3. Further, the outer peripheral portion of the distal end surface of the protruding portion 28 of the cold sprue bush 26 on the fixed die 1 side and the movable die 2
Between the outer peripheral portion of the end face of the gate cut sleeve 73 on the side
A gate 81 for connecting the cold sprue 31 of the fixed mold 1 to the product cavity 3 is formed.

Next, a method of molding an optical disk using the above-described mold apparatus will be described. During molding, first, the fixed mold 1 and the movable mold 2 are closed, and two product cavities 3 are formed between the fixed mold 1 and the movable mold 2. In this state, the butting ring 67 of the movable mold 2 is closed.
Abuts against the outer peripheral stamper retainer 53 of the fixed die 1, and the positioning frames 51 and 64 of the fixed die 1 and the movable die 2 are taperedly fitted to each other. Then, a molten thermoplastic resin as a thermoplastic molding material is injected into the hot sprue 14 from a nozzle of the injection molding machine. This resin is hot sprue
From 14 flows into the runner 21 of the manifold 11, where the runner 21 branches off. Further, the resin passes from the runner 21 through the material passage 38 in the hot tip 36, the material passage 45 in the nozzle insert 43, and the cold sprue 31 in order to form a gate 81.
Flow into the two product cavities 3 respectively. Initially, the clamping force of the fixed mold 1 and the movable mold 2 is relatively weak, and the pressure of the resin in the product cavity 3 causes the fixed mold 1 and the movable mold 2 to slightly open.

In the state where the resin is filled in the nozzle insert 43 as described above, the pressure receiving surface in the nozzle insert 43 is set.
Due to the pressure of the resin applied to the nozzles 48 and 49, a force is applied to the nozzle insert 43 toward the seating surface 30 of the cold sprue bush 26, and the nozzle insert 43 moves toward the seating surface 30 and strikes the seating surface 30. State. This state is maintained not only when the resin is injected from the nozzle of the injection molding machine but also as long as the resin is filled in the nozzle insert 43 with a predetermined pressure or more. Even if the nozzle insert 43 is once separated from the seating surface 30 after the molding is completed, the nozzle insert
43 will strike the seating surface 30.

After the resin is filled into the product cavity 3, the receiving portion 77 of the gate cut sleeve 73 is pushed toward the fixed mold 1 by a pressing rod (not shown) provided on the injection molding machine side. As a result, the gate cut sleeve 73 moves to the fixed mold 1 side, and the intermediate cylinder 55 of the fixed mold 1 is moved.
Fit inside. As a result, the resin in the cold sprue 31 and the resin in the product cavity 3, that is, the optical disk, are cut at the gate 81. Also, by increasing the clamping force of the fixed mold 1 and the movable mold 2, the core block
Almost the entire movable mold 2 including 65 moves toward the fixed mold 1. Thereby, the resin in the product cavity 3 is compressed.

The resin in the product cavity 3 is actively cooled by the cooling water as a temperature control fluid flowing through the temperature control passages 56 and 66, and the resin in the cold sprue 31 is
Cooling water, which is a temperature control fluid, passes through the temperature control passage 32 to be actively cooled. Then, after the resin in the product cavity 3 is cooled and solidified, the fixed mold 1 and the movable mold 2 are opened. With the opening of the mold, the molded optical disk and the resin solidified in the cold sprue 31 are first removed from the fixed mold 1.
Move away from At this time, the cold sprue 31 is formed at the pinpoint portion 46 narrowed by the material passage 45 in the nozzle insert 42.
And the resin on the material path 38 side of the hot chip 36 is separated. Then, when the ejection plate 78 is pushed toward the fixed mold 1 by a pressing rod (not shown) provided on the injection molding machine side, the ejection pin 74 moves together with the ejection plate 78 to the fixed mold 1 side, and the cold sprue is moved. The resin solidified in 31 is protruded and released from the movable mold 2. Further, the protrusion sleeve 72 moves toward the fixed die 1 in conjunction with the protrusion plate 78, and protrudes the inner peripheral portion of the optical disk to be released from the movable die 2. And the released optical disk is
It is taken out by a take-out robot (not shown).

Thereafter, the mold is closed again and the above molding cycle is repeated. The resin in the hot sprue 14, the runner 21 of the manifold 11, and the material passage 38 of the hot chip 36 is supplied to the heater 15, throughout the molding cycle. twenty two,
The molten state is always maintained by the heating of 39.

According to the configuration of the above embodiment, the hot chip
A nozzle insert 43 having a material passage 45 for communicating the material passage 38 in the hot tip 36 with the cold sprue 31 in the cold sprue bush 26 is slidably assembled at the tip of the nozzle 36. Is pressed against the seating surface 30 of the cold sprue bush 26 by the pressure of the resin, so that leakage of the resin from between the hot tip 36 and the cold sprue bush 26 can be prevented. That is, hot tip 36
Is heated, whereas the cold sprue bushing 26 is cooled.
And the temperature of the hot tip 36 varies, for example, from 20 ° C. to 400 ° C.
The contact between the nozzle insert 43 and the cold sprue bush 26 is always reliably maintained by absorbing the dimensional change due to the sliding of, and the resin leakage is reliably prevented.

Also, the nozzle insert 43 on the hot chip 36 side
Inserts the nozzle into the cold sprue bush 26
Since it comes into contact with and comes into contact with the flat bearing surface 30 orthogonal to the sliding direction of 43, the contact area can be reduced. Therefore, heat conduction from the hot tip 36 side heated by the heater 39 to the cold sprue bush 26 side can be suppressed,
The resin in the cold sprue 31 can be quickly cooled and solidified.

Further, when the resin solidified in the cold sprue 31 is released from the mold, a pinpoint portion 46 for separating the resin from the resin on the hot chip 36 side is provided at an axially intermediate portion in the nozzle insert 43. Since the resin is separated inside the nozzle insert 43 by being positioned, it is possible to prevent the resin on the trace of separation on the hot chip 36 side from adversely affecting the subsequent molding. That is, the resin at the separation mark on the hot tip 36 side may be stretched toward the cold sprue bush 26 side. Even in such a case, it is possible to prevent adverse effects on the subsequent molding.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made. For example,
Although the mold apparatus of the above embodiment is two-cavity, the present invention can of course be applied to a case where the number of molds is three or more.

[0033]

According to the first aspect of the present invention, the molding material is filled into the product cavity by sequentially passing through the material passage in the hot tip and the sprue bush connected to the manifold, and the material passage in the manifold and the hot tip is formed. The molding material in the material passage of the sprue bush is heated and kept constantly molten while the molding material in the material passage of the sprue bush is cooled and solidified together with the molding material in the product cavity. A cylindrical nozzle insert provided freely and freely to and away from the sprue bush is abutted against the sprue bush by the pressure of the molding material in the material passage of the nozzle insert, and the nozzle enters through the hot chip material passage. The molding material flows through the material passage of the sprue bush to the material passage of the sprue bush. While preventing leakage of molding material from between the Interview surely, by suppressing heat conduction to the sprue bushing from the hot tip, the molding material in the sprue bush can be solidified by rapidly cooling.

According to the optical disk molding die apparatus of the second aspect of the present invention, the mold having the material passage includes the base for forming the product cavity, the manifold having the heating means,
A hot chip connected to the manifold and having a heating means; and a sprue bush provided on the base, and a material passage in the hot chip and a material passage in the sprue bush are communicated with the tip of the hot chip. A cylindrical nozzle insert having a material passage inside is provided slidably and slidably with respect to the sprue bush,
A pressure receiving surface is formed in the material passage of the nozzle insert to apply the pressure of the molding material in the material passage in a direction in which the nozzle insert moves toward the sprue bush.
The optical disk molding method of the invention can be carried out.

According to the third aspect of the present invention, in addition to the effect of the second aspect, in addition to the effect of the second aspect, the material passage in the nozzle insert is provided at an intermediate portion in the axial direction of the material passage. A minimum diameter portion is formed, and a portion closer to the sprue bush than the minimum diameter portion is a tapered portion whose diameter increases toward the sprue bush, and a portion opposite the minimum diameter portion toward the sprue bush. Since the tapered pressure receiving surface with a large diameter is formed, the molding material on the hot tip side and the molding material on the sprue bush side are separated inside the nozzle insert when releasing the molding material in the sprue bush. Thereby, it is possible to prevent the molding material having the separation trace on the hot tip side from adversely affecting the subsequent molding.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a mold apparatus for molding an optical disk according to the present invention.

FIG. 2 is an enlarged sectional view of the vicinity of the hot tip and the cold sprue bush;

FIG. 3 is a further enlarged cross-sectional view of the vicinity of the nozzle insert according to the first embodiment.

[Description of Signs] 1 Fixed mold (mold) 2 Movable mold (mold) 3 Product cavity 6 Fixed mold plate (base) 7 Fixed receiving plate (base) 11 Manifold 14 Hot sprue (entrance of material passage) 21 Runner (branch of material passage) 21b Outlet 22 Heater (heating means) 26 Cold sprue bush (sprue bush) 31 Cold sprue (material passage) 36 Hot tip 38 Material passage (heating means) 39 Heater 43 Nozzle insert 45 Material passage 46 Pin point part (minimum diameter part) 47 Taper part 48 Pressure receiving surface 49 Pressure receiving surface

Claims (3)

[Claims] A plurality of product cavities for forming an optical disk between the plurality of molds by closing a plurality of molds, and the respective products are passed through a material passage having a branch path formed inside one mold. When filling the cavity with the thermoplastic molding material, the molding material is introduced into the product cavity by sequentially passing through a manifold having a branch of the material passage, a hot chip connected to the manifold and a material passage in a sprue bush. An optical disk that fills and heats the molding material in the material passage of the manifold and the hot tip to keep it constantly in a molten state, while cooling the molding material in the material passage of the sprue bush and the molding material in the product cavity to solidify. In the molding method of
A cylindrical nozzle insert slidably provided at the tip end of the hot tip and slidably attached to and detached from the sprue bush is pushed into the sprue bush by the pressure of a molding material in a material passage of the nozzle insert. And applying a molding material from the material passage of the hot tip to the material passage of the sprue bush via the material passage of the nozzle insert. 2. A method according to claim 1, further comprising the step of: forming a plurality of product cavities which are mutually moved to open and close to form an optical disk when the mold is closed; and forming a plurality of product cavities therebetween. In a mold apparatus for molding an optical disk, wherein a material passage branching from one inlet to the plurality of product cavities is formed, a mold having the material passage forms a base forming the product cavity and a branch passage of the material passage. A manifold having a heating means for heating the material passage, a hot chip connected to the manifold and having a material passage communicating with an outlet of the material passage, and a heating means for heating the material passage; and A sprue bush having a material passage communicating with the material passage of the hot tip and the product cavity provided in the hot tip, At the tip of the hot tip, a cylindrical nozzle insert having a material passage therein for communicating the material passage in the hot tip and the material passage in the sprue bush is slidably movable relative to the sprue bush. A pressure receiving surface which is provided so as to be able to freely contact and separate, and in which a pressure of the molding material in the material passage acts in a direction in which the nozzle nest moves toward the sprue bush, in a material passage of the nozzle insert. For molding optical discs. 3. In the material passage in the nozzle insert,
A minimum diameter portion is formed at an intermediate portion in the axial direction of the material passage, and a portion closer to the sprue bush than the minimum diameter portion is a tapered portion whose diameter increases toward the sprue bush,
3. The optical disk molding die apparatus according to claim 2, wherein a tapered pressure receiving surface whose diameter increases toward the side opposite to the sprue bush is formed at a portion opposite to the minimum diameter portion.