JP2778651B2 - Injection mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold for injection molding of an optical element.

[Conventional technology]

Conventionally, an optical surface 31b (parallel to the mold release direction A) of 90 ° with a reference surface 31a (eg, a first optical surface in a right-angle prism) having a structure as shown in FIG. In the case of the molded article 31 having the above optical surface, the important optical surface 31b is scratched due to rubbing or stress generated at the time of mold release. To eliminate this drawback, the fifth
A method of releasing the optical surface 31b and the slide insert 34 by a slide mechanism including a slide insert 34, an angular pin 35, a backup 36, a slide presser 37, and the like before the protrusion is generally used as shown in the drawing. Have been.
In FIG. 4, on both sides of the molded product 31, the molded product
In some cases, an overhang portion 22 used when attaching the molded product 31 and a boss protruding from the overhang portion 22 are formed integrally with the molded product 31 so as to be used for positioning when the molded product 31 is attached.

In addition, the following inventions are disclosed in the case where an angle crossing of an optical surface is allowed in the function of a molded product. For example, the invention described in Japanese Utility Model Laid-Open No. 1-67627 proposes a method for preventing a trouble during mold release by providing a draft in a mold.

[Problems to be solved by the invention]

However, the above-described conventional technology that solves the problem of mold release by using a slide mechanism not only complicates the structure of the mold and increases the production cost of the mold, but also has a high precision especially in the case of an optical molded body. In the case of molded products that require a high degree of angular accuracy, the clearance B and C (see Fig. 5b) required for sliding of the movable part itself of the slide mechanism may cause play and positioning reproducibility.
There was a disadvantage that the accuracy was reduced by one rank as compared with the case without the slide mechanism.

Further, in the invention described in Japanese Utility Model Laid-Open No. 1-67627, the optical molded body requires the angular accuracy itself, and the surface accuracy of the optical surface is not considered.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks in the prior art and to provide an inexpensive and simple mold.

[Means and actions for solving the problem]

The present invention provides an injection molding die for an optical surface molded body in which an angle formed between an optical molding surface and a structural reference surface is a right angle, wherein the optical molding surface and the structural reference surface are inclined in a die removing direction. , The cavity having an inclination angle. In addition, in the injection mold having the cavity having an inclination angle, an uneven portion is formed in the mold, and a side surface of the uneven portion is provided with a gradient of the inclination angle or more. Further, in the injection mold having the cavity having an inclination angle, the side surface of the uneven portion formed in a direction orthogonal to the structural reference surface is configured to have a taper of twice or more the inclination angle.

According to the present invention, by inclining the entire cavity of the injection mold, the mold can be easily released without damaging the optical surface of the molded product.

〔Example〕

Hereinafter, embodiments of the injection mold according to the present invention will be described in detail with reference to the drawings.

First Embodiment FIG. 1 is a partially omitted cross-sectional view showing a first embodiment according to the present invention.

Reference numeral 1 denotes an injection mold. The injection mold 1 includes a fixed mold plate 2 and a movable mold plate 3. An insert 4 is fitted and fixed to the recess 2 a of the fixed mold plate 2 by a pin 5. An insert 6 is fitted and fixed to the concave portion 3a of the movable mold plate 3 by a pin 5, and an insert 7 is slidably fitted. The molding surface 6a of the insert 6 is normally parallel to the mold release direction A, but is formed to be inclined by an angle θ of 4 °. A protruding rod 8 is connected to the insert 7 so as to be movable up and down, and its molding surface 7a is inclined by an angle θ of 4 ° in accordance with the inclination of the insert 6 to secure a right angle portion of the cavity. It is formed.

When injection molding was performed using the injection molding die having the above-described configuration, a molded product having no scratch on the optical surface was easily obtained.

In the present embodiment, the inclination angle θ of the cavity was set to 4 °, but the present invention is not limited to this, and the inclination angle may be in the range of 1 ° to 10 °, without any stress. An angle of 3 ° to 5 ° is suitable for releasing the mold.

(Second Embodiment) FIGS. 2a and 2b are partially enlarged cross-sectional views showing fixed-side inserts of a second embodiment according to the present invention.

FIG. 2A shows a molding in which a recess is provided in the lower end surface 4a of the fixed side insert 4 in the first embodiment and an overhang portion 22 protrudes from the side surface of the right-angle prism-shaped molded product 31 in FIG. An example of a product 21 is shown. Each surface of the molded product 21 indicated by a dotted line is formed by the nest 4 and the nest 6 in the first embodiment. If injection molding is performed with the molded product 21 having additional functional parts such as concave parts and convex parts simply inclined, the second
As shown in FIG. A, the side surface 22a of the overhang portion 22 interferes with the mold release direction A, so that an obstruction (undercut) occurs in mold release (at an angle). In order to eliminate this obstacle, as shown in FIG. 2B, the side surface 22a of the overhang portion 22, which is an undercut, is provided with a gradient (angle) of .theta. It is formed on the side 22b.

According to this embodiment, it is possible to eliminate an undercut portion which is an obstacle in releasing, and it is possible to add structural functions such as ribs, bosses and holes very easily.

Third Embodiment FIGS. 3A and 3B are side views showing a molded product of a third embodiment according to the present invention.

FIG. 3a shows a molded product in which a projecting boss 24 having the same diameter as a column and used for positioning when the molded product is mounted is integrally formed on the overhang portion 22 of the molded product 21 in the second embodiment. 23. If injection molding is performed in a state where the cavity of the molding die is simply inclined to form the boss 24 of the molded product 23, an obstacle (undercut) on mold release occurs at an angle portion. In order to remove this obstacle, as shown in FIG.
Ii) It is formed by providing the above taper.

Hereinafter, the operation and effect are the same as those of the second embodiment, and the description of the operation and effect will be omitted.

〔The invention's effect〕

As described above, according to the injection molding die of the present invention, it is possible to prevent a scratch and a stress caused by rubbing at the time of releasing, and to release the molded optical plane without distorting. Also, since a sliding portion such as a slide is not required, the mold has a simple structure and is inexpensive.

Furthermore, since there is no fitting play, the most important angle precision for the optical molded body is not impaired.

[Brief description of the drawings]

FIG. 1 is a partially omitted sectional view showing a first embodiment of an injection mold according to the present invention, FIGS. 2a and 2b are partially enlarged sectional views showing the second embodiment, and FIG. a and b are the third
FIGS. 4 and 5a and b show a conventional example, FIG. 4 is a perspective view, FIG. 5a is a front sectional view, and FIG.
FIG. B is a side sectional view. DESCRIPTION OF SYMBOLS 1 ... Injection mold 2 ... Fixed side mold plate 3 ... Movable side mold plate 4, 6, 7, 21 ... Nesting 5 ... Pin 8 ... Protruding rod 22 ... Overhang part 23 ... … Molded product 24 …… boss

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-12726 (JP, A) JP-A-59-87112 (JP, A) JP-A-62-85918 (JP, A) JP-A 62-85918 23721 (JP, A) JP-A-58-78716 (JP, A) JP-A-57-16321 (JP, U) JP-A-57-200362 (JP, U) JP-A-62-157221 (JP, U) Actual Opening Sho 64-57025 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45/26-45/38 B29L 11:00

Claims (3)

(57) [Claims] In an injection molding die for an optical molded body in which an angle formed between an optical molding surface and a structural reference surface is perpendicular, the optical molding surface and the structural reference surface are inclined in a die removing direction. ,
A mold for injection molding, characterized in that the cavity has an inclined angle. 2. An injection molding die in which the cavity has an inclined angle, wherein the concave and convex portions are formed in the mold, and the side surfaces of the concave and convex portions are provided with a gradient larger than the inclination angle. The injection mold according to claim 1. 3. An injection mold having a cavity having an inclination angle, wherein a side surface of an uneven portion formed in a direction orthogonal to a structural reference surface is configured to have a taper of at least twice the inclination angle. The injection mold according to claim 1 or 2, wherein: