JPS63114614A - Injection mold - Google Patents

Abstract

PURPOSE:To make it possible to highly accurately mold the surface accuracy of a molded item by a constitution wherein a lens nest is restoringly shifted through the restoring force of an elastic member in response to the shrinkage due to the cooling of a molded body in a cavity. CONSTITUTION:An elastic member 31, which consists of a Belleville spring, is interiorly arranged in a recess 33, which is shaped in an ejector plate 20 located at the under surface part of an ejector rod 17. The elastic member 31 is constituted so as to set to the preloaded to about 250kgf by fixing ejector plates 19 and 20 to each other through fixing bolts. Accordingly, when the pressure of molten resin filled in a cavity 13 exceeds 250kgf, the elastic member 31 is set to start elastic deformation through a movable side lens bush 12 and the ejector rod 17. At this time, in order for the movable side lens bush 12 to be allowed to move, a proper gap 34 is provided between the movable side lens nest 12 and a movable retainer plate 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an injection mold for injection molding plastic lenses and the like.

[Conventional Technique IFj] Generally, an injection mold is constructed as shown in FIG. 1!11 As shown in the figure, the injection mold (the figure shows a mold for plastic lenses) consists of a fixed mold part 2 and a movable mold part 3, both of which Mold part 2.・3 is fixed joint 2 at mutual joint surface (mold matching surface) 4
It is structured so that it can be separated at will.

The fixed mold part 2 includes a fixed side mold plate 5. The fixed side mold plate 5 is equipped with a fixed lens insert 7 having a lens molding surface that is an inversion of the lens surface shape of a desired plastic lens. The fixed side lens insert 7 is fixed to the fixed side mold plate 5 via a fixing screw 8.

The movable mold part 3 includes a movable mold plate 9 and a spacer block 1.
0. It is composed of a movable side mounting plate 11, etc., and the movable side mold plate 9 has a plate facing the lens molding surface of the fixed side lens insert 7,
A movable lens insert 12 having a lens molding surface formed into a desired lens surface shape is provided inside. A cavity 13 is formed by each lens molding surface of the fixed lens insert 7 and the movable lens insert 12, and the cavity 13 is formed by a gate 14. 15 runners, 1 sprue
It is configured to communicate with the 6th class runner.

The movable lens insert 12 is fixed to one end of a protruding rod 17 that is slidably inserted into the movable mold plate 9, and the other end of the protruding rod 17 is attached to the spacer block 10. A protruding plate 19 disposed within the formed space 18.
It is fixed at 20. The projecting plate 19.20 is set and arranged so that it can move upward by a predetermined amount H within the space 18, and the projecting rod 17. That is, the movable insert 12 is configured to be able to protrude from the joint surface 4 in both directions. 21.22 shows the protrusion view for protruding the game 1-14 and runner 15, and the protrusion plate 19.2
It is fixed at 0. 23 is a warm JJ tube.

According to the above configuration, the molten resin injected and injected from the molding machine is transferred to the sprue 16. Runner 15. By filling the cavity 13 through the gate 14 and applying a predetermined pressure until the gate 14 is solidified, a plastic lens having a desired lens shape can be injection molded.

When the resin in the cavity 13 solidifies, the injection-molded plastic lens (molded product) opens the molding surface 4 and moves the protruding plates 19, 20 . Projection rod 17. It is taken out by protruding upward from the upper surface of the movable mold plate 9 via the protruding pins 21 and 22.

However, in the above-described molding method using the injection mold 1, even after the small-diameter gate 14 is solidified, the resin in the large-volume cavity 13 is further cooled and contracts, so that the molded product does not fit into the mold. There was a drawback that the molded surface could not be accurately transferred, and as a result, the surface accuracy of the molded product (for example, flatness 9 dimensional accuracy in the case of a general thick-walled molded product) was significantly reduced. This tendency becomes more pronounced when the molded product is thick.

Therefore, an injection compression molding apparatus has been devised to eliminate the above-mentioned drawbacks. Such an injection compression molding apparatus is disclosed, for example, in Utility Model Publication Committee No. 1863, 1983. The outline of this device is to forcibly seal the flow path without waiting for the gate to solidify naturally, and then slide the movable side insert with a hydraulic cylinder etc. via the protruding rod to compress the cavity. It is.

According to the above means, it is possible to compensate for the shrinkage of the molded product during cooling, and the shape of the molding surface of the mold can be reversed to the molded product with high precision.

[Problems to be Solved by the Invention] The injection compression molding apparatus described above has the advantage of improving the surface accuracy of the molded product, but it not only makes the mold structure complicated and expensive, but also makes it extremely expensive. It requires an injection compression molding machine and has the drawback of being extremely expensive.

Suekan IJI was developed in view of the above-mentioned problems in the conventional technology, and is an injection molding method that allows molded products with the same level of surface precision as injection compression molding equipment to be molded using only an injection mold. The aim is to provide molds for

[Means and effects for solving the problems] The present invention provides a method of solving the problem by inserting a lens insert having a lens molding surface into each of the movable side template and the fixed side template, and when the respective templates are bonded and fixed. In the injection mold, the mold is configured to mold a molded product of a desired shape by filling a cavity formed between the molding surfaces of each lens insert with a molten resin at a predetermined molding pressure. The fixed side insert and/or the movable side insert are pressed in the direction of the opposing lens insert with an elastic member interposed therebetween, and the lens insert is pressed in response to the pressure of the molten resin filled into the cavity. The molded body in the cavity is configured to be moved in a direction away from the opposing lens insert, and configured to store elastic force in the elastic member through the movement of the lens insert. The lens insert is configured to be moved back to its original position by the restoring force of the elastic member in response to contraction due to cooling, thereby making it possible to form a molded product with high surface accuracy.

[Example] Hereinafter, an example of the present invention will be described in detail using one drawing. In the following description, members that are the same as those shown in FIG. 3 are designated by the symbol ``-'' and the description thereof will be omitted.

(First Embodiment) FIG. 1a is a front view showing a first embodiment of an injection mold 30 according to the present invention, with a portion cut away for the sake of theory 11.

As shown in the figure, the protruding plate 20 located on the lower surface of the protruding rod 17 has four parts 33 formed therein, and a member 31 made of a disc spring is disposed inside the four parts 33. be.

The elastic modulus of the elastic member 31 made of a disc spring is 1030 k
gf/am, and the bending member 31 is set so as to flex by about 0.25 mm in the attached state. That is, by fixing the protruding plates 19 and 20 via fixing ports (not shown), the elastic member 3
The configuration is such that a preload of approximately 250 kgf is added to the engine.

Therefore, when the resin pressure of the molten resin filled into the cavity 13 exceeds 250 kgf, the movable lens insert 12. The elastic member 31 is connected to the
It is set so that one-dimensional deformation occurs, and there is a suitable material between the movable lens insert 12 and the movable mold plate 9 so that the movable lens insert 12 can move at this time. A void 34 is provided. It should be noted that the elastic member 31 is not limited to a disc spring, and may of course be an elastic body such as silicone rubber. Furthermore, the protruding plates 19 and 20 are thicker and more rigid than the conventional configuration so as to maintain the elastic force of the elastic member 31. Further, the projected area of the plastic lens in the cavity 13 is set to 1.6 cm2.

Next, the operation based on the above configuration will be explained.

Molten resin sprues 16. Runner 15. When the cavity 13 is filled through the gate 14, the movable insert 12
．． A load (compressive load) proportional to the projected area of the insert 2 acts on the elastic member 31 via the protruding rod 17 . However, since the elastic member 31 is bent in advance with a force of about 250 kgf, it does not displace until the load due to the resin pressure reaches about 250 kgf, and starts displacing when the load reaches about 250 kgf or more. .

Since the resin pressure of the molten resin is around 400 kgf/cm2, in the case of this example in which the projected area of the insert 12 is 1.6 cm2, a load of about 600 kgf acts on the elastic member 31 as the maximum load. I will do it.

Therefore, the elastic member 31 has a load of 250 mm due to the resin pressure.
When it exceeds kgf, it starts to displace, and from 250 kgf to 60 kgf.
A displacement (deflection) of approximately 0.15 mm occurs during the application of a load of 0 kgf. During this displacement, the flexural member 31
Restoring force is stored in , the resin pressure decreases, and cavity 1
It restores itself as the resin inside 3 contracts and returns to its equipped state. When the elastic member 31 is restored, the large diameter portion 17b at the bottom of the protruding rod 17 comes into contact with the abutting surface 19a of the protruding plate 19, thereby ensuring that the wall thickness of the molded product is a predetermined thickness. . Therefore, according to this embodiment, the injection mold 30
However, it is possible to obtain a molded product with high surface accuracy through the same operation as the injection pressure WJ molding device, and a significant cost reduction can be achieved.

In the above embodiment, the elastic member 31 is arranged on the movable mold 3 side, but as shown in FIG. , the structure may be such that the resistant member 31 is mounted in the four parts 33, and the fixed mold part 2. It may be provided in both of the movable mold parts 3.

(Second Embodiment) FIG. 2a is a partially cutaway front view showing a second embodiment of an injection mold 30 according to the present invention. In this embodiment, an elastic member 31 is provided between the movable insert 12 and the movable mold plate 9.
The movable insert 12 is fixed to the movable mold plate 9 via a fixing port 32 passing through the elastic member 31. Then, the movable side insert 12
It is equipped internally with the material 31 compressed by a predetermined amount,
The settings are made so that the same functions and effects as in the first embodiment can be achieved. Reference numeral 36 indicates a molded product ejection bin.

The protrusion bottle 36 is set so that it can be operated by protruding the outer peripheral edge 37 of the molded product in the cavity 13. Therefore, this embodiment is suitable for molding when the outer peripheral part of the lens has a brim-like edge 37. Suitable.

According to the above embodiment, one elastic member 31 can be installed inside the movable template 9, which has the advantage of making it more compact. Other functions and effects are the same as in the first embodiment, so
The explanation will be omitted.

In the above embodiment, the elastic member 31 is installed in the movable mold plate 9, but the structure is not limited to this, and as shown in FIG.
It may be constructed by disposing the ammunition in the recess 33 formed in the
Further, it may be provided in both the fixed mold part 2 and the movable mold part 3.

[Effects of the Invention] As described above, according to the present invention, although it is an injection mold, it is possible to mold a molded product having high surface accuracy equivalent to that of a mold for injection pressure m, Significant cost reduction and configuration simplification

[Brief explanation of the drawing]

Figures 1a, b, and c are explanatory diagrams showing a first embodiment of a mold according to the present invention, and Figures 2a and b are explanatory diagrams showing a second embodiment of a mold according to the present invention. , FIG. 3 is an explanatory diagram of the prior art. 5...Fixed side template 7...Fixed side insert 9...Movable side template 12...Movable side insert 13...Cavity 17...Protrusion rod 31...Elastic member O patent applicant Olympus Optical Industry Co., Ltd. 1゜2nd
Diagram (a)? O 3' Figure 2 (b)? Figure 8 - December 8, 1988 Mr. Kunio Ogawa, Commissioner of the Patent Office. 1. Display of incident 5
゛2 1985 Patent Application No. 854832, Name of the invention Injection mold 3, Relationship to the case of the person making the amendment Patent applicant address 2-43-2 Hatagaya, Shibuya-ku, Tokyo Name Name
(037) Representative of Olympus Optical Industry Co., Ltd.
Satoshi Yama Department 4, Agent 105 Address 6, 2-2-15 Hamamatsucho, Minato-ku, Tokyo Subject of amendment 7 Contents of amendment ``Contents of amendment'' in the procedural amendment submitted on June 25, 1985 (5)" is corrected to "Beam 1 a in the drawing is corrected as shown in the attached sheet." Procedural amendment (voluntary) June 25, 1985 1. Display of 119 items 1985 Patent Application No. 85483 2 Name of invention Injection mold 3 Relationship to the Nagisa case to be amended Patent applicant Address: 2-43-2-4 Hatagaya, Shibuya-ku, Tokyo
7. Contents of the amendment (1) "Resin pressure" written on page 9, line 5 of the specification is amended to read "load due to resin pressure." (2) “Set to” written in page 9, line 17 of the specification is amended to “is”. (3) In page 40 of the specification, line 11 and line 15 of the same page. Correct the written r600kgfJ to r640kgfJ. (4) ro, 15 written on page 10, line 15 of the specification.
Correct mmJ to ro, 38mmJ. (5) Correct beam 1 in the drawing as shown in the attached sheet. 8. List of attached documents

Claims (4)

[Claims] (1) A cavity formed between the molding surfaces of each lens insert when a lens insert having a lens molding surface is inserted into each of the movable side template and the fixed side template and the respective templates are bonded and fixed. In an injection mold configured to mold a molded product of a desired shape by filling a tee with molten resin at a predetermined molding pressure, the fixed side insert and/or the movable side insert are A pressing structure is formed by interposing an elastic member in the direction of the opposing lens inserts, and the lens inserts are moved in a direction away from the opposing lens inserts in response to the pressure of the molten resin filled in the cavity. The lens insert is configured such that an elastic force is stored in the elastic member through the movement of the lens insert, and the lens insert is caused to move in response to contraction due to cooling of the molded body in the cavity. 1. An injection mold, characterized in that the mold is configured to return to its original position via the restoring force of an elastic member. (2) A patent claim characterized in that the elastic member is a disc spring, and is elastically provided between an ejecting rod that protrudes and operates the movable side insert and an ejecting plate that protrudes and operates the ejecting rod. The injection mold according to item 1. (3) The elastic member is interposed between the movable insert 12 and the movable template, and is capable of a predetermined initial displacement via a member screwed onto the movable insert 12. Claim 1 characterized in that it is set to be granted.
Injection mold as described in section. (4) The elastic member is elastically disposed in a recess formed in the fixed mold part, and is configured to be freely displaceable via the fixed side insert. The injection mold according to scope 1.