JPH04122017U - injection mold - Google Patents

Abstract

(57) [Summary] [Purpose] Eliminate distortion of surface shape. [Configuration] The fixed insert 2 is fitted into the fixed plate 1, and the fixed mold 3
shall be. The movable insert 5 is slidably fitted into the movable plate 4,
It will be a movable type 6. A Teflon film 9 is formed on the outer peripheral surface of the tip of the movable insert 5. The inner diameter surface of the flange 8a of the plastic lens 8 is formed by a portion provided with a Teflon film 9. To take out the molded product, the mold is opened along the parting line 7. Next, only the movable insert 5 is moved in the direction of the fixed mold 3, and after the movable insert 5 is projected from the movable plate 4, it is released from the mold.
During demolding, the inner diameter surface of the flange 8a slides smoothly on the Teflon film 9. Low sliding resistance, easy release from mold, and no distortion.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is applicable to injection molds for plastic lenses that have flanges on the outer periphery. related.

0002

[Conventional technology]

In recent years, we have been making use of the fact that a free external shape can be obtained depending on the shape of the mold cavity. However, the flange formed on the outer periphery of a plastic lens has become complicated, and the lens Some have a flange that stands up in the direction of the optical axis.

0003 Conventionally, the mold for injection molding such plastic lenses was, for example, an actual mold. The one described in JP-A No. 2-15321 is known. This injection mold As shown in FIG. has been done. Further, a movable insert 5 is slidably fitted into the movable plate 4, and a movable mold 6 is configured. The movable mold 6 comes into contact with and separates from the fixed mold 3 at the parting line 7. It is currently set up. The space sealed by the fixed mold 3 and the movable mold 6 is a cavity. Molten resin is injected into this cavity, cooled and solidified to form a molded product. A plastic lens 8 is obtained. 8a is provided on the outer periphery of the plastic lens 8. This flange 8a is formed to stand up in the optical axis direction. It is.

0004 To take out the molded product, move the movable mold 6 in the opposite direction from the fixed mold 3 side (to the right in Fig. 5). direction) and open the mold with the parting line 7 as the border, then move the movable insert 5 The mold is moved in the direction of the fixed mold 3, and the movable insert 5 is projected from the movable plate 4 and released from the mold.

[0005] In general injection molding, it is important to have good protrusion when taking out the molded product. A draft angle is created on the product surface perpendicular to the parting line 7 in order to However In the case of plastic lens molding, the material itself has high elasticity, and a slight force is applied. It can be easily released from the mold by simply touching it. Therefore, the inner and outer diameter portions of the flange 8a When high precision is required, draft angles cannot be added, as shown in Figure 5. There are many things.

[0006]

[Problem that the idea aims to solve]

However, when molding is performed using the conventional injection mold mentioned above, plastic shrinkage occurs. As a result, the flange 8a of the plastic lens 8 bites into the movable plate 4, making it impossible to move. When the insert 5 protrudes, the flange 8a and the movable plate 4 slide, and the plastic is removed. A large stress is applied to the lock lens 8. Plastic obtained in this way When the optical surface of lens 8 is measured with a laser interferometer, interference fringes appear as shown in Figure 6. , a distortion of the surface shape called as-area occurred. This distortion of the surface shape is caused by The optical part that most degrades the performance of lenses, and which requires high precision. It could not be used for products.

[0007] The present invention was developed in view of the problems of the conventional methods, and is designed to prevent distortion in the surface shape. The purpose is to provide an injection mold that can obtain plastic lenses. do.

[0008]

[Means to solve the problem]

In order to achieve the above object, the present invention utilizes a plastic material having a flange on the outer periphery. In the KLENS injection mold, the surface of the part that forms the inner diameter surface of the flange. We decided to increase the sliding properties of the surface compared to other parts. In other words, the inner diameter surface of the flange The mold part that forms the mold is made of a material that has extremely good sliding properties compared to other parts. It is. Examples of materials with good sliding properties include Teflon, molybdenum sulfide, and fluoride. Molybdenum, boron nitride, etc. are suitable.

[0009]

[Effect]

According to the mold of the present invention having the above configuration, the inner diameter surface of the flange of the molded lens is spaced apart. The mold slides smoothly during molding. Therefore, lens deformation due to mold release resistance is minimized. The surface accuracy of the lens is high.

0010

[Example 1] FIG. 1 shows the injection mold of this embodiment, in which the flanges of the plastic lens 8 are The inner diameter surface of the hinge 8a is formed by the outer peripheral surface of the tip of the movable insert 5. For this reason, Fig. As shown in the enlarged view in FIG. A ron film 9 is formed. A plastic lens 8 is molded using this mold, and its finished product is To take out the shaped part, the fixed mold 3 and the movable mold 6 are separated from each other by the parting line 7. After opening, only the movable insert 5 is moved toward the fixed mold 3, and the movable insert 5 is moved toward the movable plate 4. After that, the plastic lens 8 is directly released from the mold by hand by an operator, or Or it is released from the mold by a robot hand.

[0011] According to the mold of this embodiment, when releasing the plastic lens 8, the flange 8a is A Teflon film 9 is formed on the outer peripheral surface of the tip of the movable insert 5 that forms the inner diameter surface. Therefore, the sliding resistance is significantly reduced and the mold can be easily released. Figure 3 shows the actual implementation Results obtained by measuring the optical surface of the plastic lens 8 obtained using the example mold using a laser interferometer. The interference fringes appeared concentrically, and there was no distortion in the surface shape.

0012

[Example 2] In this example, instead of the Teflon film 9 of Example 1, Teflon particles with a diameter of 2 μm were used. The outer peripheral surface of the tip of the movable insert 5 is plated with nickel containing 30% by volume of Ta. The mold of this example also has the same effect as that of Example 1, especially the resistance of the above surface treatment. Improved durability. The optimal diameter of Teflon particles is 0.1 to 5 μm; The mixing amount of is preferably 25 to 40% by volume.

[0013]

[Example 3] FIG. 4 shows the injection mold of this embodiment, and the tip of the movable insert 5 has a stepped portion. 10 are formed. Then, on the outer circumferential surface of the small diameter portion of this stepped portion 10, the A Teflon film 9 is formed in the same manner. Flange 8 of plastic lens 8 The inner diameter surface of a is formed by the portion where this Teflon film 9 is provided. In addition, the movable insert 5 A stripper 12 is provided on the outer periphery of the stripper 12 and is biased toward the fixed mold 3 by a spring 11. ing. The stripper 12 abuts against the flange 8a of the plastic lens 8. The Teflon film 9 is formed in a portion having a smaller diameter than the inner diameter of the stripper 12. Therefore, the stripper 12 does not slide on the Teflon film 9.

[0014] In the mold of this embodiment, the molded product is released by separating the stationary mold 3 and the movable mold 6 into parts. This is done when the mold is opened at the cutting line 7. When opening the mold, the plastic The lens 8 is pressed against the fixed mold 3 by the stripper 12 and separated from the movable insert 5. be molded. In this example, as in the above-mentioned example, the mold release was carried out easily, and the The mold release takes place automatically.

[0015] Furthermore, this invention can also be applied to molds that employ methods such as pin protrusion and air protrusion. Of course you can.

[0016]

[Effect of the idea]

As described above, according to the injection mold of the present invention, the flanges of plastic lenses can be The inner diameter surface of the lens slides smoothly on the mold during mold release, so the lens will not be affected by mold release resistance. Deformation can be minimized to obtain a plastic lens with a good surface shape. be able to.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an injection mold according to Example 1 of the present invention.

FIG. 2 is an enlarged vertical cross-sectional view of the main part in FIG. 1;

FIG. 3 is a characteristic diagram showing the results of measurement by a laser interferometer of the optical surface of a plastic lens molded with the injection mold of Example 1 of the present invention.

FIG. 4 is a longitudinal sectional view showing an injection mold according to a third embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing a conventional injection mold.

FIG. 6 is a characteristic diagram showing the results of measurement by a laser interferometer of the optical surface of a plastic lens molded with a conventional injection mold.

[Explanation of symbols]

1 Fixed plate 2 Fixed nesting 3 Fixed type 4 Movable plate 5 Movable insert 6 Movable type 7 Parting line 8 Plastic lens 8a flange 9 Teflon membrane

Claims (1)

[Scope of utility model registration request] 1. An injection mold for a plastic lens having a flange on the outer periphery, characterized in that the surface of the portion forming the inner diameter surface of the flange has higher sliding properties than other portions. Mold for injection molding.