JPS609722A - Injection molding die for plastic optical parts - Google Patents

Abstract

PURPOSE:To make cutting off of an unnecessary part after molding unnecessary and to prevent a bend of optical parts through contraction of resin at the time of molding, by cutting a cavity part apart from a molten resin leading part and a molten resin sump part. CONSTITUTION:When pressure of resin 10 in a cavity part 1 injected from an injection opening 7 becomes high, an inner force 17 of a stationary molding die A is pushed up, and when predetermined resin pressure is detected by a pressure detector 21 an inner force 12 is pushed up by operating an inner force moving mechanism 14 of a movable molding die B. Then the inner force 12 is lifted up while it is pushing up the resin 10 in the cavity part 1 and the inner force 17 of the stationary molding die A and during the process the resin 10 in the cavity part 1 is cut apart from the resin 10 in a molten resin leading part and a molten resin sump part 8 by an injected resin cutting-apart part 15. When the inner force 17 of the stationary molding die is abutted against a stopper 20, only the inner force 12 of the movable molding die B is ascended after that, which pushes out resin between the injected resin cutting-apart part 15 of both the inner forces 12, 17 and its catching part 23 into the cavity part 1, compresses the resin 10 in the cavity part 1 and abuts against the catching part 23.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an injection mold for plastic optical components.

[Technical background of the invention]

In recent years, optical components such as lenses and ZOLISM are being made of plastic for the purpose of reducing weight and cost.

Figure 1 shows a conventional mold used for injection molding of plastic optical parts. This mold consists of a fixed mold (upper mold) A and a movable mold (lower mold) B. The mating surfaces of this pair of molds A and B are equipped with optical components (
A cavity portion 1 for molding a lens (in the figure) is formed. Still, in FIG. 1, 2 represents the pair of molds A.
, H is a sprue formed vertically, 3 is a sprue closing pin that closes this sprue 2 in the movable mold B, 4 is a locate ring attached to the upper part of the fixed mold A,
The sprue 2 is communicated with the cavity portion 1 via a molten metal guide portion consisting of a runner 5, a gate 6, and an injection lower formed on the mating surfaces of the pair of molds A and B. Further, on the mating surfaces of the molds A and H, a molten metal sump 8 is formed which communicates with the cavity 1 on the opposite side from the molten metal guide portion. In addition, 9 in the figure is a molded product extrusion bottle.

Therefore, the molding of the optical component is performed using the pair of molds A and B.
Inject the resin 1θ from the locate ring 4 into the cavity 1 via the sprue 2 and the runner 5, the r-toro, and the injection lower until the resin 1o also flows into the pool 8. This is carried out by curing the resin 10 in a state in which the resin 1o fills the cavity portion 1.

[Problems with background technology]

However, molded products molded using the above conventional molds,
Unfortunately, the optical component molded in the cavity part 1 is connected to the resin cured in the melt guide part and the molten pool part 8. (resin hardened in the parts and molten pools) must be cut off, which not only requires a lot of effort and time to cut off the unnecessary parts, but also creates processing distortion on the optical parts when cutting the unnecessary parts. However, there is a problem in that the optical components may be accidentally scratched and scratched during cutting. Moreover, in the conventional mold described above, the molded optical component may be warped due to contraction of the resin IO injected into the cavity 1 during curing, and this warpage is a fatal defect for optical components. In order to become
Since warped parts cannot be used, there is also the problem that the yield of molded optical parts is poor.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to mold an optical component that is molded in a cavity section separately from the resin in the molten metal guide section and the molten pool section. Plastic optics that eliminates the need to cut unnecessary parts after molding, and also prevents warping of optical parts due to resin contraction during molding, making it possible to produce high-quality optical parts with high yield. Our objective is to provide injection molds for parts.

[Summary of the invention]

That is, in the present invention, at least one of a pair of molds is made up of an outer mold in which a molten metal guide part and a tundish part are formed, and an inner mold in which a cavity part is formed, and the inner mold is slidable on the outer mold. An inner mold moving mechanism is provided on the back side of the inner mold to move the inner mold toward and away from the surface of the other mold, and an inner mold moving mechanism is provided on the outer periphery of the cavity of the inner mold. When resin is injected into the mold, the molten metal lead part and the molten duct part of the outer mold are communicated with the capity part while facing away from the other mold surface during resin injection into the mold, and the other mold is moved by the inner mold moving mechanism. The injection resin separation part is formed by moving the inner mold toward the mold side to separate the resin in the cavity part from the resin in the molten metal leading part and the tundish part. Inject the resin into the mold while keeping it away from the mold surface, and then move the inner mold to the other mold side to compress the resin injected into the cavity into the shape of the optical component to be molded. By curing the resin in this state, the occurrence of warping due to resin contraction is prevented, and the injection resin dividing part of the inner mold separates the resin in the cavity part from the resin in the molten metal guide part and the tundish part. By curing the resin in this state, the optical component can be molded separately from the resin in the molten metal guide part and the tundish part.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 2 and 3. Components in the figure that correspond to those shown in FIG. 1 are given the same reference numerals, and descriptions of those that do not require particular explanation will be omitted.

First, the movable mold B, which is the lower mold, will be explained. This movable mold B consists of an outer mold 11 in which a molten metal guiding part (runner 5, dart 6, and injection lower) and a molten mold part 8 are formed, and a cavity part. 1, and an inner mold 12 which formed the inner mold 1.
2 is fitted into an inner mold fitting hole 13 provided in the outer mold 11 so as to be vertically slidable without any gap. And this inner mold 1
2 is supported at the bottom of the inner mold fitting hole 13 of the outer mold 11 via an inner mold moving mechanism (for example, a hydraulic cylinder) 14 provided on the back side thereof, and this inner mold 12 is a fixed mold. When mold A and movable mold B are aligned and when the molds are opened, it moves up and down together with the outer mold 11, and is independently moved toward and away from the surface of the fixed mold A by the operation of the inner mold moving mechanism 14. It has become so. Further, on the outer periphery of the cavity portion of the inner mold 12, an injection lower of the molten metal guide portion of the outer mold 11 and a molten metal pool are provided over the entire periphery, facing away from the fixed molding mold surface A when resin is injected into the mold. 8 and the cavity part 1, and when the inner mold 12 is moved toward the fixed mold A side by the inner mold moving mechanism 14, it is pressed against the A side of the fixed mold, and the resin 10 in the cavity part 1 and the resin 10 in the cavity part 1 are moved. An injection resin dividing section 15 is formed that separates the resin 10 in the molten metal guide section and the tundish pool section 8 .

Next, the fixed mold A, which is the upper mold, will be explained. Similar to the movable mold B, this fixed mold A has an outer mold 16 in which a molten metal leading part and a tundish part 8 are formed, and a cavity part 1.
It consists of an inner shape 17 formed with. The inner mold 17 is slidably fitted into the outer mold 16 so as to be pushed in and out of the upper mold by the pressure of the resin 10 injected into the cavity part 1. When no resin pressure is applied to the inner mold 17, the inner mold holder formed on the outer mold 16 is pressed against the portion 19 by a spring 18 provided on the back side of the inner mold 17. Further, on the back side of the inner mold 17, a stopper 20 for regulating the amount of movement of the inner mold 17 in and out, and a pressure detector 21 for detecting the resin pressure applied to the inner mold 17 are provided. The pressure detector 21 is connected to a controller 22 that controls the inner mold moving mechanism 14 of the movable mold B. Furthermore, the inner mold 1
The injection resin dividing portion 1 formed in the inner mold 12 of the movable mold B is disposed on the outer periphery of the cavity portion of No. 7 over its entire circumference.
5 receiving portions 23 are formed.

Molding of a plastic optical component using the mold having the above configuration is carried out as follows. First, as shown in Fig. 2, a pair of molds A and B are matched, and the inner mold 1 of movable mold B is
Resin is injected into the mold with the mold 2 spaced apart from the A side of the fixed mold. The resin 10 injected into this mold is injected into the cavity part 1 from the metal introduction part through between the injection resin dividing part 15 of the inner mold 12.17 and its receiving part 23,
The cavity part 1 is filled with the resin, and the space between the injection resin dividing parts 23 and 15 and the pool part 8 are also filled with the resin, and as the resin is injected into the mold, the resin pressure in the mold increases. going up. Then, the resin 10 inside the cavity part 1
When the pressure increases, this resin pressure causes the fixed mold A to
The inner mold 17 is pushed up against the pushing force of the spring 18, and the pressure detector 21 detects the resin pressure inside the cavity 1. This pressure detector 21 detects a predetermined resin pressure (this varies depending on the type of resin 10 and the shape of the cavity 1, but for example, if the resin is acrylic resin and the shape of the cavity 1 is as shown in the figure, 1200 K).
It is assumed that a signal is output when a signal is detected (approximately mi). On the other hand, the injection of resin into the mold is automatically stopped by a signal from the pressure detector 21, so that a fixed amount of resin is injected into the mold. When a signal is output from the pressure detector 21, the inner mold moving mechanism 14 of the movable mold B is actuated in response to a command from the controller 22, and the inner mold 12 is pushed up. At the same time, the resin 10 inside is pushed up, and the inner shape 17 of the fixed mold is pressed down by the resin pressure inside the cavity 1 and moves upwardly into and out of the outer mold 16. Then, when the inner mold of the movable mold B is pushed up, this inner mold enters the outer mold 16 of the fixed mold A while pushing up the resin 10 in the cavity part 1 and the inner mold 17 of the fixed mold A. In this process, the injection resin dividing section 15 separates the resin 10 in the capitivity section 1 from the resin 10 in the molten metal guide section and the tundish pool section 8. In addition, the inner mold 17 of the fixed mold A
hits the stopper 20, from then on, only the inner mold 12 of the movable mold B rises, and the resin between the injection resin dividing portion 15 of the side inner mold 12.17 and its receiving portion 23 is transferred to the cavity. At the same time, the gap between the inner molds 12 and 17 is compressed to compress the resin 1o inside the cavity part 1. This resin 10 is compressed by the inner mold 12. The process continues until the injection resin dividing section 15 of I'i and its receiving section 23 come into contact with each other as shown in FIG. 3, and the resin between them is completely extruded. It is compressed into the shape of the optical component to be molded. After this, after curing the resin 10 in the mold, open the molds A and B, and take out the molded optical component by vacuum suction, and remove the hardened resin in the molten metal lead part and the tundish part 8. Bye.

The optical component molded in this manner does not suffer from any warping due to shrinkage of the resin during curing, and the optical component is separated from the resin in the molten metal guide portion and the tundish portion 8 before the resin hardens. Since the optical parts are molded in the same shape, there is no need to cut off unnecessary parts after molding, unlike optical parts molded using conventional molds.

In addition, in the above embodiment, the fixed mold A also has an outer mold 16 and an inner mold 1.
7, but this fixed mold insert may be an integral piece similar to a conventional mold, and in that case, the inner mold 12 of the movable mold B must be pressed against the fixed mold A surface. At the same time, the resin 10 can be divided by the injection resin dividing section 15 and the resin 10 inside the cavity section 1 can be compressed. In this case, as the resin pressure in the cavity 1 increases, a part of the resin in the cavity 1 is pushed out to the molten metal leading part and the tundish pool 8, but the volumes of the molten metal leading part and the tundish pool 8 are Since it is very small compared to the volume of cavity part 1,
If the amount of resin that escapes into the lead-in part and the molten pool part 8 is taken into account and the position of the inner mold 12 is lowered by that amount during resin injection, an optical part that is no different from the optical part molded with the mold of the above embodiment can be obtained. When molded, it is possible to form. In this case, the inner mold moving mechanism 14 may be operated by detecting the injection resin pressure at the injection lower of the molten metal pool 8 or the molten metal guide section. In addition, in the above embodiment, the resin is divided and compressed by the inner mold 12 of the movable mold B, but on the contrary, an inner mold moving mechanism is provided on the back side of the inner mold 17 of the fixed mold A. Then, the resin may be divided (in this case, the receiving part 23 in the above embodiment becomes the injection resin dividing part) and compressed by the inner mold 17 of the fixed mold A. The inner mold 12 of the movable mold B may be operated in the same manner as the inner mold 17 of the fixed mold A in the above embodiment, or the movable mold B may be made integral.

〔Effect of the invention〕

According to the present invention, the optical component molded in the cavity part can be molded in a form separated from the resin in the molten metal guide part and the molten mold part, so that unnecessary parts, ie, the molten metal guide part, can be separated from the optical component after molding. There is no need to cut the resin that has hardened in the hot water pool, and it is also possible to prevent optical parts from warping due to shrinkage of the resin during compact molding, making it possible to produce high-quality optical parts at a high yield.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a conventional mold, and FIGS. 2 and 3 are vertical cross-sectional views of the mold showing an embodiment of the present invention during resin injection and compression. A... Fixed mold, B... Movable mold, 1... Cavity part, 2... Sprue, 5... Runner, 6...
・y-t, 7... Injection port, 8... Hot water pool part, 1
0...Resin, 1...Outer mold, 12...Inner mold, 14
... Inner mold movement mechanism, 15 ... Injection resin dividing section, 16
...Outer mold, 17...Inner #1B...Spring, 2
0... Stop valve, 21... Pressure detector, 23...
Receiving part.

Claims (2)

[Claims] (1) In an injection mold for plastic optical components, which consists of a pair of molds each having a cavity portion on which the optical component is molded on mating surfaces, and a molten metal lead portion and a molten metal reservoir portion that communicate with the cavity portion, at least one of the molds is molded. The mold is made up of an external mold in which the molten metal guide part and the tundish pool are formed, and an inner mold in which the cavity part is formed, and the inner mold is slidably fitted into the outer mold, and the inner mold is slidably fitted into the outer mold. An inner mold moving mechanism is provided on the back side of the mold to move the inner mold toward and away from the surface of the other mold, and furthermore, an inner mold moving mechanism is provided on the outer periphery of the cavity portion of the inner mold, and the resin injection mechanism into the mold is provided on the outer periphery of the cavity portion of the inner mold. Sometimes, the mold surface is spaced apart from the surface of the other mold, and the molten metal guide part and the tundish part of the outer mold are communicated with the cavity part, and the cavity is moved by the movement of the inner mold toward the other mold side by the inner mold moving mechanism. An injection mold for a plastic optical component, characterized in that an injection resin separation part is formed to separate the resin inside the part from the resin in the molten metal guide part and the tundish part. (2) The other mold consists of an outer mold in which a molten metal leading part and a molten metal pool are formed, and an inner mold in which a cavity part is formed, and the inner mold is caused by resin pressure in the cavity part with respect to the outer mold. The inner mold is slidably fitted so as to move in and out, and a stone is provided on the back side of the inner mold to restrict the amount of retraction movement of the inner mold. An injection mold for a plastic optical component according to claim (1), characterized in that a receiving part for an injection resin dividing part formed in the inner mold of one mold is formed over the entire circumference. .