JPS6054826A - Precision injection molding die - Google Patents

Abstract

PURPOSE:To enable to mold with high accuracy a molded part, which is thin at its center and has no draft provided at its outer peripheral part, without generating any weld-marks and developing any flexural deformation at mold release by a structure wherein a sliding core block and a sliding sleeve, both of which can move severally each other, are installed in a die. CONSTITUTION:Firstly, injection is performed under the conditions that a sliding core block 5 is retreated while a sliding sleeve 12 is advanced or, in other words, the inflowing of resin into the flange part of a molded part is prohibited. Secondly, the sliding sleeve 12 is retreated and at the same time the sliding core block 5 is advanced. Thirdly, both the sliding core block 5 and the sliding sleeve 12 are advanced in order to process injected resin and then solidify by cooling. After that, ejector bars 4 are advanced so as to advance a push plate 9 pushed by the ejector bars 4. As a result, both the sliding core block 5 and the sliding sleeve 12 are advanced simultaneously. Accordingly, a concave plastic lens part is released from a die.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a precision injection mold, and particularly to a mold for precision injection molding.

A mold for precision injection molding that is capable of molding a molded product with a thin central part and no taper on the surrounding brim part, such as a concave plastic lens, with high precision and releasing the mold without bending deformation. Regarding.

[Background of the invention]

Below, a conventional injection mold for molding a molded product that requires shape accuracy and surface precision, such as a plastic lens, will be explained using drawings. Figure 1 shows a conventional injection mold for molding a concave glass lens. 6 is a partial cross-sectional view for explaining an example of an injection mold. 6 In the same figure, 1 is a cavity, 2 is an injection molding machine, and 3 is a sliding plate, which will be described later, in response to a signal from the injection molding machine 2. A hydraulic control device for driving and controlling a hydraulic cylinder for moving pieces; 4 is an ejector rod integrally constructed with the injection molding machine 2; 5;
and 6 are sliding pieces and sleeves provided in the movable mold 20, 7 and 8 are fixed pieces and sleeves provided in the fixed mold 30, 9 is an extrusion plate, and 10 is the sliding piece. A sliding piece hydraulic cylinder 13 for advancing or retracting the piece 5 is a Z-bin provided in the movable mold 20 with its rear portion fixed to the extrusion plate 9.

Note that this figure shows a state in which the inside of the cavity 1 and the space 1α are filled with resin.

In Figure 1, the molding of the concave glass lens is 1.
It is done as follows.

First, the cavity 1 is formed so that the fixed insert piece 7 in the identification mold 30 and the sliding insert piece 5 in the movable alloy 20 can obtain a product (molded product) with a desired wall thickness. Then, the cavity 1 is filled with resin injected from the injection molding machine 2.

Furthermore, at this time.

A gap 1 extending from the injection port of the injection molding machine 2 to the cavity 1
A is also filled with the resin.

Next, taking into consideration the amount of resin contraction, etc., the resin in the cavity 1 is moved forward by a hydraulic cylinder 10, which is a sliding piece 5, and the resin in the cavity 1 is processed and shaped.

That is, the concave glass lens portion is shaped like ff.

Then, after waiting for the resin in the cavity 1 to cool and solidify, the movable mold 20 is moved in the direction of arrow A using the method described above. That is, the mold is separated from the dotted chain line 1-1 into the movable mold 20Σ and the solid foot metal #150. At this time, the resin that has been filled and solidified in the cavity 1 and the gap 1CL is particularly thick at the tip and becomes thinner as it goes deeper. Type 2
It is semi-fixed on the 0 side and taken out together with the Z pin.

Thereafter, the removed resin, inter alia.

The concave plastic lens part molded within the cavity 1 is released from the mold by advancing the ejector rod 4.

Specifically, when the ejector rod 4 moves forward and the extrusion plate 9 inside the movable mold 20 pushed by the ejector rod 4 moves forward, the Z bin 15
Then, the hydraulic cylinder 10 and the sliding piece 5 are moved forward, and as a result, the resin that was attached to the movable mold 20 in the manual state is released from the mold. In other words, the concave glass lens part is #! ! be molded.

As described above, concave plastic lenses are molded and released, but in these cases, the thickness of the center part is extremely thin compared to the thickness of the outer peripheral part, and the outer peripheral part, that is, It is like a concave glass lens that does not have a cutout on the rim.There are two drawbacks as described below.The first is that it is difficult to fill the cavity 1 with resin. , Because the center part is thin, the flow of resin at the front edge is slower than in the thick outer peripheral part, and this results.

As shown in FIG. 21, a unique mark 15 is generated on the surface of a molded product, that is, a concave glass lens.

Second, since no extraction taper is provided on the outer periphery of the molded product, that is, on the flange, as is clear from Figure A1, when releasing the mold by advancing the sliding piece 5, the front edge Second, friction occurs between the collar of the molded product and the second league 6, which causes bending and deformation due to FLK.

That is, as shown in FIG. 3, as the sliding entry piece 5 moves forward, it receives a force in the direction of the arrow 14.

The molded concave glass lens was deformed as shown by the broken line.

In addition, FIG. 2 is a front view of a concave plastic lens.
FIG. 3 is a cross-sectional view of the surface.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art described above, to prevent the occurrence of weld marks even in a molded product that is thin in the center and has no punched taper on the outer periphery, and to prevent bending during mold release. It is an object of the present invention to provide a precision injection mold that can also prevent deformation and, therefore, can mold highly accurate molded products.

[Summary of the invention]

The feature of the present invention is that the sliding piece is in contact with the outer peripheral part of the sliding piece.

and a sliding sleeve capable of sliding separately from the sliding insert piece, and a sliding sleeve 1 capable of moving the sliding sleeve in the front-rear direction in a system different from the sliding operation of the sliding insert piece. The point is that a hydraulic cylinder is required.

[Embodiments of the invention]

The present invention will be explained below with reference to the drawings.

FIG. 4 is a partial cross-sectional view for explaining an embodiment of a precision injection mold of the present invention for molding a concave plastic lens as in the conventional example.

In this figure, the same reference numerals as in FIG. 1 indicate the same or equivalent parts. 11 is a sliding sleeve hydraulic cylinder for advancing or retracting the sliding sleeve described later; 12 is provided in the movable mold 20 according to the present invention;
This is the sliding sleeve that slides at a distance of m.

The hydraulic cylinder 11, like the hydraulic cylinder 10, is driven and controlled by the hydraulic control device 6, and as will be clear from the description below, the hydraulic pressure is controlled by a signal from the injection molding machine 2. The drive is controlled by a separate system from the cylinder 10.

The operation of molding a concave plastic lens according to this embodiment will now be described using enlarged views of main parts in FIGS. 5 to 7, in which the vicinity of the cavity 1 is enlarged.

First, in this embodiment, when the injection molding machine 2 injects the resin, the sliding entry piece 5 is moved to the width of the cavity 1 (as shown in the fifth factor).
Set aside to increase thickness (thickness). That is, the flow rate of the resin in the cavity 1 becomes almost uniform in the central and peripheral parts of the molded product, and as a result, the weld mark 15 is prevented from occurring in the molded product. place i
The sliding entry piece 5 is set back from the position where the wall thickness of .

Further, at the time of resin injection, the sliding sleeve 12 is advanced as far as possible by the hydraulic cylinder 11 to prevent the resin from flowing into the portion corresponding to the flange of the molded product.

In such a state, immediately after resin is actually injected from the injection molding machine 2 and the cavity 1 and the gap 1α are filled with the resin.

As is clear from FIG. 6, in this embodiment, the sliding sleeve 12 is retracted, and at the same time, the sliding piece 5 is advanced. As a result, the resin whose fluidity has not been reduced flows into the portion corresponding to the brim of the molded product, and therefore the shape of the resin filled in the cavity 1 becomes the same as the shape of the molded product.

In this way, after the resin is approximately arranged in the shape of the molded product, the sliding entry piece 5 and the sliding sleeve 12 are moved forward again.
The resin is processed and in this state is cooled and solidified.

By the way, the amount of advance of the sliding insert piece 5 is calculated by calculating the volume of the molded product's collar, that is, the sum of the volume created by the retreat of the sliding sleeve 12 and the amount of resin contraction, and the projected area of the sliding insert piece 50. It is the value divided by .

Therefore, in order to obtain the desired wall thickness of the molded product, either the position of the sliding entry piece 5 during resin injection or the amount of retraction of the sliding sleeve 12 corresponding to the thickness of the collar of the molded product must be selected. All you have to do is adjust at least one of them.

Next, when the resin in the cavity 1 is sufficiently cooled and solidified, in this embodiment, the pressure applied to the resin by the sliding piece 5 and the sliding sleeve 12 is removed. After that, as in the conventional example, the fourth
The 5'fWJJ mold 20 and the fixed mold 30 are separated along the dashed line VI-Vl in the figure.

That is, the movable mold 20 has a cavity 1 and a cavity 1.
The solidified resin filled in a is moved in the direction of arrow A in a semi-fixed state.

After that, in this embodiment, the ejector rod 4 is advanced, and the extrusion plate 9 in the movable mold 20 pushed by the ejector rod 4 is advanced. As a result, the Z-bin 13 and the hydraulic cylinder 10
, 11. The human piece 5 and the sliding sleeve 12 move forward at the same time.

Therefore, the resin that was semi-fixed to the movable mold 20,
In particular, the concave plastic lens portion is released from the mold as shown in FIG.

By the way, at this time, the inner surface of the flange of the molded product is pressed by the sliding sleeve 12 provided according to the present invention, so in this embodiment, the entire surface of one side of the molded product is pressed against the sliding entry piece. 5 and the sliding sleeve 12,
As a result, it is clear that bending deformation as shown by the broken line in FIG. 3 does not occur.

In addition, in the above explanation, the movable mold 20 side, the sliding insert piece 5
However, in the present invention, this sliding sleeve 12i is not added.

That is, as is clear from FIG. 8 showing another embodiment of the present invention, even if the sliding insert piece 5 and the sliding sleeve 12 are provided on the fixed mold 30 side, the above-mentioned problem will not occur. Of course, similar results can be obtained.

In FIG. 8, the same reference numerals as in FIG. 4 indicate the same or equivalent components.

〔Effect of the invention〕

As is clear from the above description, according to one aspect of the present invention, a sliding piece and a sliding sleeve that can be operated separately are installed in at least one of the identified mold or the movable mold, and This is because it is designed to slide by the desired amount in a predetermined order.

This has the effect that a molded product with a thin center portion and no punching taper on the outer periphery can be molded with high precision without producing weld marks or bending deformation during mold release.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view for explaining an example of a conventional injection mold, Fig. 2 is a front view of a concave glass lens, and Fig. 6 is a side sectional view thereof. Figure 4 is a partial sectional view for explaining one embodiment of the present invention, and Figures 5 to 7 are enlarged views of the vicinity of the cavity in Figure 4 for each case in which a concave plastic lens is molded. FIG. 8 is a partially sectional view for explaining another embodiment of the present invention. 1... Cavity 2... Injection molding machine 3... Hydraulic control device 4... Ejector rod 5... Sliding entry piece 6
．． B... Sleeve 7... Fixed insert piece 9... Push-out plate 10... Hydraulic cylinder for sliding insert piece 11... Hydraulic cylinder for sliding sleeve 12... Sliding sleeve piece 1 (i21 3 Figure 3 Rabbit 2 Figure 4 Old

Claims (2)

[Claims] (1) A sliding insert placed on either one of the fixed mold or a movable mold, a fixed insert placed on the other, and the front surface of both the sliding insert and the fixed insert. In an injection mold having a butt K, H, and a cavity for shaping the molding resin, it is in contact with the outer periphery of the sliding insert piece, and is independent of the sliding insert piece. A slidable sliding three 1, a hydraulic cylinder for a sliding entry piece that moves the sliding entry piece in the front and back direction by hydraulic control device pressure controlled in accordance with a signal from the outside, and the hydraulic control device. Accordingly, a sliding sleeve hydraulic cylinder i for moving the sliding sleeve in the front-rear direction is provided in a separate system from the sliding inserting hydraulic cylinder, at least the sliding sleeve hydraulic cylinder and the sliding sleeve hydraulic cylinder. and an extrusion plate that is firmly supported, and the entire surface of one side of the shaped molding resin is pressed by the front surface of the sliding entry piece and the tip of the sliding sleeve when the mold is released. That's it! Mold for dense injection molding. (2) A patent characterized in that the front surfaces of both the sliding insert piece and the fixed insert piece are spherical or aspherical, and the tip shape of the sliding direction cross section of the sliding sleeve is a right-angled etch. A precision injection mold according to claim 1.