JPH0450124A - Molding device of fine glass lens - Google Patents

Abstract

PURPOSE:To uniformly heat the whole material and to eliminate occurrence of pressure contact mark and other distortions in press molding of optical glass, by making a specific floating means to maintain an optical glass material not in contact with an upper mold and a lower mold during heating of the material. CONSTITUTION:An upper mold 5 and a lower mold 3 are inserted into and arranged between an upper and a lower platens 1 and 2 and a device to press mold an optical glass material 8 to be molded placed on the lower mold 3 is equipped with the following means. Namely, at least just before a press process, a floating means (e.g. drum 4 and spring 6) to maintain the distance between the upper mold 5 and the lower mold 3 at a given interval and to hold both side surfaces of the optical glass material 8 to be molded apart from the upper mold 5 and the lower mold 3 is installed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a precision optical glass molding apparatus for molding precision optical glass such as an optical glass lens.

[Prior Art] In recent years, in addition to the conventional processing method of grinding and polishing, optical glass lenses have been manufactured using a method in which molten optical glass is directly press-molded using a mold, and a method in which an optical glass material is shaped in advance to approximate the final shape. A method of press-molding reformed optical glass materials using a mold has come into use.

Among the above-mentioned methods, the method of manufacturing by press molding is considered to be a promising method for producing optical lenses in the future from the viewpoint of cost-saving production and automation. In particular, the method of press-molding a preform optical glass material is the most promising since it is excellent in terms of temperature control, etc., and equipment for carrying out this method has been developed and put into practical use.

As mentioned above, the apparatus for press-molding optical glass lenses using preformed optical glass materials includes upper and lower platens, and a lower mold and an upper mold interposed between these platens. The optical glass material to be formed is placed on a lower mold, the optical glass material is heated to a predetermined temperature, and pressure is applied by the upper mold, whereby the optical glass material is press-molded. It is configured to do this.

[Problems to be Solved by the Invention] By the way, in the press processing apparatus according to the prior art described above, the optical glass material to be formed is placed on the lower mold, and the mold surface of the upper mold is brought into contact with this optical glass material. For example, if the mold surface of the upper mold is convex, the load of the upper mold may cause pressure apertures on the surface of the optical glass molded product, or heating of the optical glass material may occur. Since the mold is in contact with the optical glass material at times, it is not possible to bring the optical glass material into a uniform temperature state, resulting in problems such as distortion and deformation due to uneven distribution of heat during molding.

The present invention has been made in view of the above-mentioned points, and its purpose is to avoid pressure marks etc. during molding, and to uniformly heat the optical glass material to be molded during molding. The purpose of the present invention is to provide a precision optical glass molding device.

[Means for Solving the Problems 1] In order to achieve the above-mentioned object, the present invention provides a predetermined interval between an upper mold and a lower mold inserted between upper and lower platens, at least before the pressing process. The structure is characterized in that it is provided with floating means for holding both surfaces of the optical glass material to be molded in a state separated from the upper mold and the lower mold.

[Operation] By adopting such a configuration, the optical glass material to be formed is fed into the molding device with the upper mold and the lower mold separated by the floating means, and the optical glass material is held by the floating means. By this,
The optical glass material can be held apart from both the upper mold and the lower mold. Therefore, after heating the optical glass material floated in this way to a predetermined temperature, one or both of the upper mold and the lower mold are displaced to separate the floating means from the optical glass material and both The optical glass material is formed by pressurizing it between molds.

In this way, when heating the optical glass material, since the upper mold and the lower mold are kept in a state of not contacting each other, the entire optical glass material can be heated uniformly, and the optical glass material can be heated evenly. Since the material is held in a non-loaded state before pressing, pressure marks and other distortions may occur on the molded product.

Press molding can be performed without causing deformation or the like.

[Example j] Hereinafter, an example of the present invention will be described in detail based on the drawings.

First, FIG. 1 is a sectional view of a main part showing an embodiment of a precision optical glass forming apparatus. In the figure, l indicates an upper platen, 2 indicates a lower platen, and a lower mold 3 and a cylindrical body wall 4 that surrounds the lower mold 3 and extends upward from the mold surface 3a of the lower mold 3, and an upper mold 5 is disposed within the body wall 4. The upper mold 5 is arranged to be movable up and down, and is lowered by the pressing force of the upper platen 1, and such a construction is well known in this type of molding apparatus.

However, the feature of this embodiment is that in order to maintain the body wall 4 in a spaced state between the lower surface 4a of the body wall 4 and the flange portion 3b of the lower mold 3, a heat-resistant material such as ceramics is used. A spring 6 made of a good quality material is loaded, and a step 7 is formed below the body wall 4 to project inward, and the BRIFORM optical glass material 8 is made to float by the step 7. The point is that it is configured so that it can be supported in any state. Here, the outer dimensions of the lower mold 5 are smaller than the outer dimensions of the upper mold 3 by the amount by which the stepped portion 7 is formed.

In the stage before processing, the upper mold 5 is moved by the spring 6 acting on the adjusting mold 4 so that the mold surface 5a thereof is larger than the maximum thickness dimension of the preform optical glass material 8 from the mold surface 3a of the lower mold 3. It can be held in an isolated position for a long time. As a result, when the preform optical glass material 8 is installed so as to be supported by the stepped portion 7, both upper and lower surfaces 8a and 8b of the optical glass material 8 are formed on the mold surface 3a of the lower mold 3 and the mold surface 3a of the upper mold 5. It is arranged to be spaced apart from the surface 5a. Incidentally, since the upper die 5 moves up and down, it goes without saying that the spring 6 is formed so as not to become an obstacle when the upper die 5 moves to the stroke end of the downward movement. .

This embodiment is constructed as described above, and the upper mold 5 is pushed upward by the action of the spring 6 as shown in FIG. Insert the reformed optical glass material 8. As a result, the optical glass material 8 is locked to the stepped portion 7 formed in the mold 4 and held in that position. In this state, the preform optical glass material 8 has both upper and lower surfaces 8a and 8b.
is spaced apart from the mold surface 3a of the lower mold 3 and from the mold surface 5a of the upper mold 5.

With the optical glass material 8 floating in this way,
heating the optical glass material 8 to a predetermined temperature to soften it;
Next, the upper platen 1 is lowered. As a result, the mold 4 is lowered together with the upper mold 5 while bending the spring 6, and as shown in FIG. 8 will be placed on the lower mold 3. Then, when the upper mold 5 further descends, the optical glass material 8 is transferred to the mold surface 3a of the lower mold 3, as shown in FIG.
and the mold surface 5a of the upper mold 5, and the pressing is performed.

When the pressing operation is completed, the upper platen 2 is returned to its original position. At this time, the adjusting mold 4 is raised together with the upper mold 5 due to the action of the spring 6, and the upper mold 5 is used to mold the optical glass material 8. Move away from the product. Further, during the upward stroke of the mold 4, it comes into contact with a step 7 formed on its inner surface and separates from the lower mold 3, so that the molded product returns to its floating state.

In this way, until the optical glass material 8 is heated and pressing is actually started, the optical glass material 8 is heated against the mold surface 3a of the lower mold 3 and against the mold surface 5a of the upper mold 5. Since it is kept in a non-contact state, it is possible to heat the entire surface uniformly, and it is possible to prevent deformation and distortion caused by heat. Moreover, the load of the upper mold 5 acts on the optical glass material 8, and the optical glass material 8
There is no risk of press marks being generated by the optical glass material 8 being pressed against the lower mold 3 by its own weight. However, since the optical glass material 8 is supported by the stepped portion 7 of the mold 4, there are no press marks in this part. Although there is a possibility that this may occur, if the part that contacts the stepped portion 7 is set outside the effective photographing area of the lens,
There is no particular problem.

Furthermore, after the press molding is completed, the molded product is immediately separated from the upper mold 5 and lower mold 3, which improves mold releasability, so the mold can be protected and its life can be extended. Become.

In addition, in the above-mentioned embodiment, the upper mold was configured to be movable, but the lower mold may be raised or both molds may be configured to be movable. Although the floating means is shown as being composed of a spring and a step portion formed into a shape, it is also possible to use, for example, an arc-shaped clamp member that clamps the optical glass from both the left and right sides, and to connect this clamp member to a cylinder, The opening/closing operation may be performed using a cam mechanism or the like.

[Effect of the Invention 1] As explained above, according to the present invention, the floating means is configured to hold the optical glass material so as not to come into contact with either the upper mold or the lower mold, at least at a stage before the start of the pressing process. Therefore, when heating the optical glass material, it is now possible to uniformly heat the entire optical glass material, and there are no pressure marks on the optical glass during press molding, which improves molding accuracy. is significantly improved.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which FIG. 1 is an explanatory diagram of the main part configuration of a molding device, and FIGS. 2 and 3 are explanatory diagrams of its operation. upper platen, 2: lower platen, 3: lower mold, 4: tone mold,
5: upper mold, 6: spring, 7: step, 8 nib form optical glass material.

Claims (1)

[Claims] In an apparatus for press-molding an optical glass material to be formed, in which an upper mold and a lower mold are inserted between upper and lower platens and placed on the lower mold, at least before the pressing process, the upper mold and the lower mold are With a predetermined separation between
A precision optical glass molding apparatus, characterized in that it is configured to include floating means for holding both surfaces of the optical glass material to be molded in a state separated from the upper mold and the lower mold.