JP2002104833A - Mold for forming optical element and method of forming optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for forming an optical element not generating a scratch on sliding, making smooth inserting and not necessitating frequent adjustment for enhancing precision of eccentricity and fitting. SOLUTION: This method of forming an optical element comprises the steps of blowing a gas through an introducing hole 5 provided at the side wall of a barrel 1 to float a lower mold 3 and an upper mold 2, setting the lower mold 3 and the upper mold 2 slowly to a determined position in the barrel by a plug-in cylinder 7 while floating in the barrel, stopping the introduction of the gas and opening a vent gas hole 6 to vent the pressurized gas in the barrel, blowing the gas again through the introducing hole 5 (at a lower pressure than insertion of the molds) to stand a gas membrane between the mold and the barrel, and forming a glass perform 9 by the plug-in cylinder 7 keeping the mold and the barrel not to contact to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved mold for molding an optical element and a method for molding an optical element using the mold.

[0002]

2. Description of the Related Art In order to produce a fine and precise molded product such as an optical element, a molding die composed of an upper and lower die and a body die for guiding and accurately fitting them has been used. Japanese Patent Publication No. 63-46010 discloses an upper mold, a lower mold and a ring-shaped body mold between them as a molding mold for molding a glass lens with little eccentricity without requiring cold grinding and polishing. A mold that is slidably housed in a sleeve is described. In this method, since the clearance between the upper and lower dies is very small, there is a problem that the upper and lower dies are easily damaged when the upper and lower dies are inserted into the torso.
Japanese Patent Publication No. 08822 discloses an apparatus for manufacturing an optical element having means for fitting a mold in a body mold while applying ultrasonic vibration. Japanese Patent Application Laid-Open No. 9-20525 discloses that in molding an optical element by press molding, an eccentric angle between a center axis of curvature of a molding surface formed on each of the upper and lower mold members and a press axis is measured. A method is disclosed in which both mold members are set by rotating and adjusting relative to the press axis so as to cancel out each eccentric angle.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a mold which does not require any frequent adjustments to prevent damage during sliding, smooth insertion, and increase eccentricity and fitting accuracy. Is to provide.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a molding die comprising a body die and an upper and lower die which can be slidably moved therein and which are fitted to each other. A means for introducing a gas into the sliding portion of the optical element. In one aspect, the present invention provides
The above-mentioned optical element molding die, wherein the trunk die is divided into an upper trunk die combined with the upper die and a lower trunk die combined with the lower die, and the upper trunk die and the lower trunk die are fitted by fitting positioning means. . In addition, the present invention is to slide and insert at least one of the lower mold and the upper mold into the body mold while introducing gas into the body mold, after incorporating the upper mold and the lower mold in the body mold, The present invention relates to a method for forming an optical element, wherein gas in a body mold is exhausted before a molded object is taken out.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the molding die of the present invention, the upper and lower dies inserted with a small clearance into the trunk die are smoothly inserted without damaging the trunk die, and are fitted with excellent precision. It is a molding die for an optical element improved as described above. The molding die of the present invention is characterized in that a gas introducing means is provided for blowing gas into the body die when the upper and lower dies are inserted so that the upper and lower dies can be smoothly inserted into the body die. The clearance between the body mold and the upper and lower molds is generally about 3 to 6 μm, which is almost the same as that of the conventional mold of this type. However, in the method of the present invention in which gas is interposed, a gas film is formed in the clearance between the body mold and the mold. As a result, the sliding resistance becomes extremely small because of the non-contact state, so that the upper and lower dies can be smoothly inserted.

In the present invention, forcibly interposing gas when inserting the upper and lower molds into the body mold means that the metal is pressed to prevent the lower mold or the upper mold from being eccentrically pressed into the body mold. This means that a gas film is interposed in the clearance between the mold and the body mold. In this state, if the lower mold or the upper mold to be inserted is slowly pushed in by the pushing cylinder, the lower mold and the upper mold can be assembled at predetermined positions in the body mold without eccentricity. The strength of the gas sent into the barrel mold is
There is no particular limitation as long as a gas film is formed in the clearance between the lower mold or the upper mold and the body mold, and the pressure is higher than the wind force or pressure that does not contact the inside of the body mold.

Various means can be used for introducing gas for this purpose. For example, it can be easily realized by providing a gas introduction pipe on the side surface of the trunk as shown in FIG. The gas introduction pipe may be only an introduction pipe or a separate exhaust pipe. Further, the gas introduction pipe (and the exhaust pipe) may be provided at one place, or a plurality of gas introduction pipes may be provided symmetrically around the body. Further, the gas inlet pipe (and the exhaust pipe) may be provided for the lower mold provided at the lower part of the body mold and for the upper mold provided at the upper part.

[0008] In the molding die of the present invention, the body mold part may be divided into an upper body mold corresponding to an upper mold part and a lower body mold corresponding to a lower mold part. In the case of such a split type mold, it is easy to take out the molded body after molding. In the case of split type, for positioning of upper body type and lower body type,
Preferably, a pin or some other positioning means is provided. The bottom of the torso (the bottom of the lower torso in the case of split type) may have a bottom integrated with the torso, or may be detachable to fit the bottom of the torso separately from the torso The bottom of the fitting type may be combined. From the viewpoint of ease of production, easy removal of the upper and lower dies, and easy cleaning of the inside of the body mold, it is preferable to use the latter as the removable bottom.

The gas to be introduced into the body mold is not limited as long as it has no danger or toxicity, such as air. However, in order to prevent oxidation of the mold and fusion of the mold and glass, nitrogen or nitrogen is used. Inert gases are preferred. The gas to be introduced may be mixed with fine particles having lubricity such as MoS ₂ or C (pulverized coal) of 0.5 μm or less.

[0010]

EXAMPLES The present invention will be described in more detail and specifically with reference to the following examples. Embodiment 1 FIG. 1 is a schematic view showing an example of a molding die according to the present invention, and shows a state where an upper die is being inserted after a lower die has already been inserted. The lower mold 3 and then the upper mold 2 are being inserted into the body mold 1 in which the bottom plate 8 is fitted. Gas is blown from the introduction pipe 5 provided on the side wall of the barrel die, whereby the lower die and the upper die can be slowly incorporated into the bottom of the die by the pushing cylinder 7 while floating the lower die and the upper die in the die. After the lower mold and the upper mold are assembled at the predetermined positions, the gas introduction is stopped and the gas exhaust pipe is opened to exhaust the gas existing in the body mold in a pressurized state. Subsequently, in the molding step, a gas is blown again from the introduction pipe 5 (at a lower pressure than when the mold is inserted), and a gas film is interposed between the mold and the mold so that the mold and the mold do not contact each other. In this state, the glass preform 9 can be formed by the pushing cylinder 7.

Embodiment 2 FIG. 2 is a schematic view of a molding die in which a body die is divided into a lower die and an upper die. Lower mold 3 in body mold 1 "fitted with bottom plate 8
When inserting the lower mold, gas is blown from the introduction pipe 5 ″, whereby the lower mold is fitted in the non-contact state with the body mold. Also, when inserting the upper mold 2 into the body mold 1 ′,
A gas is blown from the introduction pipe 5 'and fitted. In the present embodiment, in the forming step, the upper mold 2 and the upper barrel mold 1 'are integrally pressed by a pressing device (not shown) without blowing gas from the introduction pipes 5' and 5 '' again. At this time, the positioning of the upper body mold 1 'and the lower body mold 1''is performed by fitting the positioning pins 10. By doing so, since the sliding of the mold does not occur between the mold and the body, it is possible to suppress the occurrence of scratches due to the sliding. In this embodiment, the lower mold is fixed and the upper mold is pushed in.However, the upper mold is fixed and the lower mold is pushed in.In this case, the optical element can be easily pulled out of the barrel mold by pulling out the lower mold. Can be taken out. It is also conceivable to simultaneously push the upper mold and the lower mold into the body mold. Preferably, a plurality of positioning pins are provided.

[0012]

According to the present invention, if the molding is performed by using the mold of the present invention, the upper and lower molds can be inserted into the body mold with high accuracy, and can be slid with high accuracy. Or the risk of producing a defective molded product can be extremely reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a state in which an upper mold is being inserted after a lower mold has already been inserted in a molding die of the present invention.

FIG. 2 is a schematic diagram of a molding die in which a trunk die is divided into an upper die and a lower die.

[Explanation of symbols]

 1: trunk type, 1 ': upper trunk type, 1' ': lower trunk type, 2: upper die, 3: lower die, 4: clearance between upper and lower die and trunk type, 5: gas inlet pipe, 5': 5 ″: gas inlet pipe of lower body section, 6: gas exhaust pipe, 6 ′: gas exhaust pipe of upper body section, 6 ″: gas of lower body section Exhaust pipe, 7: Push cylinder, 8: Bottom plate, 9: Glass preform, 10: Positioning pin, 11: Positioning pin fitting hole.

Claims (5)

[Claims] 1. A mold comprising a body mold and an upper and lower mold which can slide and move in the body mold.
An optical element molding die, characterized in that a means for introducing gas is provided in a sliding portion between an upper die and a lower die of a trunk die. 2. The body mold is divided into an upper body mold combined with an upper mold and a lower body mold combined with a lower mold, and the upper body mold and the lower body mold are fitted by fitting positioning means. 2. The optical element molding die according to 1. 3. The optical element molding die according to claim 1, wherein the means for introducing gas into the sliding portion includes a gas introduction and exhaust pipe formed on a side surface of the body mold. 4. While at least one of the lower mold and the upper mold is slid and inserted into the body while the gas is being introduced into the body,
A method for forming an optical element, comprising: exhausting a gas in a body mold after assembling an upper mold and a lower mold in a body mold and before taking out an object to be molded. 5. A method of molding an optical element using a body mold and an upper and lower mold that can slide and move therein, wherein at least one of the upper and lower molds is in a non-contact state with the body mold during pressure molding. A method for molding an optical element.