JPH11255529A - Molding apparatus for optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out the heating and the cooling of an upper and a lower molds in a short time, by reducing the heat capacity of the circumference of the upper and the lower molds to extrusion mold an optical element material. SOLUTION: The circumference of an upper and a lower molds 1 and 2 for the extrusion molding of an optical element material 3 is equipped with one movable guide 6 and two stationary guides 5. The sides of the upper and the lower molds 1 and 2 are engaged with the three guides 5 and 6 to adjust the central axes of the upper and the lower molds each other. The guides 5 and 6 do not completely the circumference of the upper and the lower molds 1 and 2 and the heat capacity of the upper and the lower molds 1 and 2 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a molding apparatus for producing an optical element such as an optical glass element.

[0002]

2. Description of the Related Art The need for aspherical lenses has been increasing in order to satisfy the demands for higher performance of lenses themselves and reduction of the number of lenses in a lens system. Means for finishing a glass material by spherical polishing has been used for a long time to manufacture a glass lens. However, it is very difficult to manufacture an aspherical lens by polishing with current technology. For this reason, aspherical lenses are manufactured by press molding. In this molding, however, plastic materials that can be easily molded have limited optical performance. It has been done.

Many devices for molding optical glass elements have been devised, but in this molding device, when manufacturing an optical lens or the like, it is important to obtain the eccentricity of the upper and lower molding dies. For this reason, in the prior art, Japanese Patent Publication No. 3-5542
No. 0 and Japanese Utility Model Application Laid-Open No. Sho 62-194018 have been proposed.

The technique disclosed in Japanese Patent Publication No. 3-55420 is to increase the eccentricity by slidably fitting upper and lower molds into a cylindrical body mold. 62-194
In the technique disclosed in Japanese Patent Publication No. 018, the eccentricity is obtained by accommodating the mold in a square mold support member and pressing the mold support member against a guide plane formed with high precision.

[0005]

However, in the molding apparatus proposed in Japanese Patent Publication No. 3-55420,
The heat capacity of the body mold in which the upper and lower molds are inserted is large, and it takes a long time to heat and cool the entire mold, which increases the tact time of molding and cannot improve productivity. . This is the same problem in Japanese Utility Model Application Laid-Open No. Sho 62-194018, which has a mold supporting member for accommodating a mold.

The present invention has been made in consideration of the above-mentioned problems of the prior art, and it is possible to shorten the molding tact time and improve the productivity of the optical element. It is intended to provide a device.

[0007]

According to a first aspect of the present invention, there is provided an optical element molding apparatus for press-molding an optical element material with a pair of molding dies. It is characterized by having three guides that fit and align the axis of each mold.

In the present invention, the three guides are fitted to the side surfaces of a pair of molding dies, the axes of the respective molding dies are aligned, and in this state, the optical element material is pressed and molded by the pair of molding dies. In the present invention, since the heat capacity around the mold is small, heating and cooling of the mold can be performed in a short time, and the tact time of molding can be shortened.

According to a second aspect of the present invention, in the first aspect, one of the three guides is provided with a preload means for applying a desired preload toward the side surface of the molding die. It is characterized by.

In the present invention, a desired preload is applied to one of the three guides toward the side surface of the mold by the preload means. Therefore, the eccentricity of the mold can be improved.

A third aspect of the present invention is the invention according to the first or second aspect, wherein the guide has a round bar shape.

In the present invention, the side surfaces of the pair of molds are fitted to the three round bar-shaped guides so that the axes of the molds are aligned. Since the guide is a round bar, the molding die and the guide are in line contact, the contact area with the molding die is reduced, and the heat capacity around the molding die can be reduced.

A fourth aspect of the present invention is the invention according to the first or second aspect, wherein the guide has a shape in which two round bars are arranged.

According to the present invention, a three-bar-shaped 3
The side surfaces of the pair of molds are fitted to the book guide, and the axes of the molds are aligned. By arranging the two round bars in this manner, the strength of the guide is improved.

A fifth aspect of the present invention is the invention according to any one of the first to fourth aspects, further comprising a parallelism adjusting mechanism for adjusting the parallelism of two of the three guides. It is characterized by.

In the present invention, the parallelism adjusting mechanism is used to adjust
Adjust the parallelism of two of the book guides. By adjusting the parallelism of the two guides in this way, the mold can be guided stably.

[0017]

(Embodiment 1) FIG. 1 shows an entire optical element molding apparatus according to Embodiment 1 of the present invention, and FIG.
Indicates the relationship between the mold and the guide.

As shown in FIG. 1, in this optical element molding apparatus, a frame 16 is mounted on a base 15, and
The inside is a molding chamber 14. A pair of molding dies including an upper mold 1 and a lower mold 2 are provided in the molding chamber 14.

As shown in FIG. 2, two fixed guides 5 and one movable guide 6 extending in the driving direction (vertical direction) of the forming die are arranged around the upper die 1 and the lower die 2. ing. The fixed guide 5 and the movable guide 6 are arranged at equal positions obtained by dividing a circle into three equal parts, and respectively contact the side surfaces of the upper die 1 and the lower die 2. As a result, the upper mold 1 and the lower mold 2 are fitted to the fixed guide 5 and the movable guide 6 so as to be movable in the vertical direction. As described above, the fixed guide 5 and the movable guide 5 function so that the axes of the upper die 1 and the lower die 2 coincide with each other.

Guide cylinders 7 are attached to three positions of the frame 16 in the vertical direction, respectively.
Are connected to the pistons 7a of these guide cylinders 7. The guide cylinder 7 moves the movable guide 6 in the radial direction of the forming die by its driving. In addition to this, the guide cylinder 7 presses the movable guide 6 toward the side surfaces of the upper mold 1 and the lower mold 2, and by this pressing gives an equal preload to the movable guide 6 and the fixed guide 5, and Adjust the eccentricity of the mold 2. For this reason, the guide cylinder 7 also functions as a preload means for applying a preload toward the side surfaces of the upper die 1 and the lower die 2.

The upper and lower ends of the fixed guide 5 and the movable guide 6 are held by the stopper 11 by being inserted into the guide stopper 11. A parallelism adjusting mechanism (not shown) for adjusting the parallelism of the two fixed guides 5 is stored in the upper and lower guide stoppers 11, whereby the two fixed guides 5 have good parallelism. Can be kept.

The upper mold 1 and the lower mold 2 are molded in a cylindrical shape, and the optical axis of the molding surface of each mold 1 and 2 coincides with the axis of the outer peripheral side surface of the molding mold. In this embodiment, tungsten carbide is used as a material of the upper mold 1 and the lower mold 2, and the upper mold 1 and the lower mold 2 have the same size in the upper and lower directions, an outer diameter (φ) of 14 mm, and a height of 14 mm. 20 mm.

As the fixed guide 5 and the movable guide 6,
A round bar made of SiC having a diameter (φ) of 5 mm was used, and the preload from the guide cylinder 7 during the forming operation was set to about 0.3 kgf.

An optical element material 3 made of optical glass is placed on the lower mold 2. Further, a quartz tube 12 surrounding the upper and lower molds 1 and 2 and the optical element material 3 is disposed inside a frame 16 constituting the molding chamber 14. The inside of the quartz tube 12 can maintain a nitrogen atmosphere. Quartz tube 12
On the outside, a heater 4 is provided.

The upper die 1 can contact the lower end of the upper shaft 9,
A lower shaft 8 is connected to the lower mold 2. Lower shaft 8 is base 15
It is connected to the lower shaft cylinder 10 provided in the
When the lower cylinder 10 is driven, the upper and lower dies 1 and 2 are moved upward via the lower shaft 8, and the bottom of the upper die 1 is brought into contact with the lower end of the upper shaft 9 by the lower cylinder 10 during molding. The optical element material 3 is pressed and molded by this application. The part in which the upper and lower dies 1 and 2 move up and down by driving the lower cylinder 10 in this manner constitutes a mold supply unit 13.

Next, molding according to this embodiment will be described. Before molding, the lower shaft 8 is lowered, and the upper and lower dies 1 and 2 are on standby outside the molding chamber 14. First, the movable guide 6 is moved rightward in FIG. 1 by driving the guide cylinder 7. Thereby, a gap is formed in the fixed guide 5 and the movable guide 6 in which the upper and lower dies 1 and 2 can be inserted.

Thereafter, the lower mold 2, the upper mold 1, and the optical element material 3
Is supplied onto the lower shaft 8, and the guide cylinder 7 is driven to move the movable guide 6 to the left in FIG. 1, thereby abutting the outer peripheral portions of the side surfaces of the upper mold 1 and the lower mold 2. By this application, the upper and lower molds 1 and 2 can maintain a predetermined eccentricity accuracy.

Then, the lower shaft cylinder 10 is driven to push up the lower shaft 8, and the optical element material 3, the upper mold 1, and the lower mold 2 are transported to the heating position. At the heating position, the heater 4 heats the upper and lower dies 1 and 2 and the optical element material 3 to a predetermined temperature.

When the temperature reaches a predetermined temperature, the optical element blank 3 is pressed by applying pressure to the forming die by the lower shaft cylinder 10 to perform the forming. When the optical element material 3 reaches the desired medium thickness, the pressure is released, the heater 4 is turned off, and cooling is started. When the cooling is completed, the lower shaft 8 is lowered to the mold supply section 13, and the guide cylinder 7 is moved rightward in FIG. 1 to release the upper and lower molds 1 and 2 from the guides 5 and 6, and the upper mold 1 and the lower mold 2 Then, the molded optical element is taken out and the molding is completed.

In this embodiment, the diameter (φ) is 10 m.
m, a convex lens having a medium thickness of 4 mm was molded. For comparison, a mold of the same size and material was formed by an apparatus using a barrel mold described in JP-A-3-55420. Therefore, other elements (for example, specifications of a heater and the like) other than the use of the body mold are common. As the optical optical material 3 to be molded, a glass material SF6 (manufactured by OHARA CORPORATION) was used.

A molding experiment was carried out at a molding temperature of 495 ° C., and the time required to reach the mold temperature of 495 ° C. was 3 minutes and 40 seconds in a conventional apparatus using a barrel mold. On the other hand, the apparatus of the present embodiment was 2 minutes and 50 seconds. The time required for cooling was 5 minutes and 20 seconds in the conventional apparatus, whereas it was 4 minutes and 10 seconds in the apparatus of the present embodiment. In both cases, an optical element having surface accuracy and outer diameter of a non-defective product could be formed.

As described above, in the present embodiment, it has been found that the takt time can be reduced as compared with the conventional apparatus, and thereby the production efficiency can be improved.

As the material of the fixed guide 5 and the movable guide 6, any material other than SiC can be used as long as it is a heat-resistant material such as heat-resistant steel, stainless steel, tungsten carbide, or silicon nitride. A material that is high and resistant to bending stress is desirable. In this embodiment, the guides 5 and 6 are round bars. This is to reduce the contact points between the molds 1 and 2 and the guides 5 and 6 to make the heat distribution of the molds uniform and to reduce the heat capacity of the guides while maintaining the strength. The shape may be the same as the curvature of the outer periphery, and is not particularly limited to the cross-sectional shape.

(Second Embodiment) FIG. 3 shows a second embodiment. Also in this embodiment, the fixed guide 5 and the movable guide 6 are in contact with the side surfaces of the upper and lower dies 1 and 2 from three equal positions. The fixed guide 5 is formed by arranging guide rods 21 and 21 formed of two thin cylindrical bodies (round bar shapes), and the movable guide 6 is similarly formed of a guide rod 20 formed of two thin cylindrical bodies. 20 are formed.

In this embodiment, both the fixed guide 5 and the movable guide 6 have two guide rods 21, 21 and 2
It is possible to swing as shown by an arrow in FIG. 3 around the 0, 20 tangent line as a central axis. The guide rod 2
The material of 1, 21, and 20, 20 is SiC.

The molding method in this embodiment is the same as that in the first embodiment. The guides 5 and 6 having a shape in which two guide rods each formed of a columnar body are arranged, the contact points between the upper and lower dies 1 and 2 and the guides 5 and 6 are minimized, and the guides 5 and 6 heat the dies 1 and 2. The strength of the guides 5 and 6 can be improved while minimizing the influence of the
It is easy to reduce the eccentricity of No. 2. Also,
By swinging the guides 5 and 6 around a tangent connecting the guide rods 20, 20 and 21, 21, the guides 5,
6 and the upper and lower molds 1 and 2 can be brought into close contact with no gap. Therefore, the strength and axial accuracy of the guides 5 and 6 can be improved.

In this embodiment, when the same optical element shown in the first embodiment was molded, an optical element of a nondefective level could be molded in the same manner as in the first embodiment. The time required for the mold temperature to reach 495 ° C. is 3 minutes and 50 minutes.
Seconds. The advantage of this embodiment over the first embodiment is that the variation in eccentricity when molding continuously for 100 shots can be suppressed to 0.2 minutes including shift and tilt.

From the above description, the present invention includes the following inventions. (1) Pressing and molding optical glass material 1
In an optical glass forming apparatus having a pair of forming dies, 1
An apparatus for molding an optical glass element, wherein three guides are used as means for vertically guiding a pair of molds.

In this molding apparatus, the three guides guide the molding die in the vertical direction in the same manner as the body die, but since the guides do not cover the entire molding die, the heat capacity around the molding die is reduced, and The heating time and cooling time of the mold can be reduced.

(2) The optical glass element molding apparatus according to the above (1), wherein the molding is performed while applying an appropriate amount of preload to the molding die to one of the three guides.

In this molding apparatus, the accuracy of the eccentricity of the molding die can be improved.

(3) The apparatus for molding an optical glass element according to the above (1), wherein the three guides have a round bar shape.

By making the guide into a round bar shape, the guide and the mold are in linear contact, and the contact area between them can be reduced.

(4) The shape of the guide should be two round bars.
The apparatus for forming an optical glass element according to the above (1), wherein the optical glass element is formed in the form of a series.

Since the guide is composed of two round bars, the strength of the guide is improved.

(5) The apparatus for molding an optical glass element according to the above (1), further comprising a mechanism for adjusting the parallelism of two of the three guides.

Since the parallelism of the guide can be adjusted, the molding die can be guided well.

(6) In an optical element molding apparatus for press-molding an optical element material with a pair of molding dies, at least three of the pair of molding dies are fitted to each other so that the axes of the molding dies are aligned. An optical element molding apparatus comprising a guide.

In this molding apparatus, at least three guides guide up and down. However, since the guides do not cover the entire mold, the heat capacity around the mold is small, and the heating time and cooling time of the mold are reduced. Can be shortened. Here, if the number of guides is more than three and is, for example, four or five, the heat capacity around the forming die is slightly increased, but the upper and lower dies can be guided more stably.

[0050]

As described above, according to the first aspect of the present invention, since the heat capacity around the mold is reduced,
Heating and cooling of the mold can be performed in a short time, and the tact time of molding can be shortened.

According to the second aspect of the present invention, since the preload means applies a desired preload to the side surface of the molding die with one guide, the eccentricity of the molding die can be improved.

According to the third aspect of the present invention, since the guide is a round bar, the contact area between the mold and the guide is reduced, and the heat capacity around the mold can be reduced.

According to the fourth aspect of the invention, the strength of the guide is improved by arranging two round bars.

According to the fifth aspect of the present invention, by adjusting the parallelism of the two guides, the mold can be guided stably.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of Embodiment 1 of the present invention.

FIG. 2 is a perspective view around a molding die and a guide according to the first embodiment.

FIG. 3 is a perspective view around a molding die and a guide according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper die 2 Lower die 3 Optical element material 4 Heater 5 Fixed guide 6 Movable guide 7 Guide cylinder 8 Lower shaft 9 Upper shaft 10 Lower shaft cylinder 11 Guide stopper 12 Quartz tube 13 Mold supply part 14 Molding chamber

Claims (5)

[Claims] 1. An optical element molding apparatus for press-molding an optical element material with a pair of molding dies, comprising: three guides that fit the side surfaces of the pair of molding dies and align the axes of the respective molding dies. A molding device for an optical element, comprising: 2. An optical element molding apparatus according to claim 1, wherein one of said three guides has a preload means for applying a desired preload toward a side surface of said molding die. . 3. The molding device according to claim 1, wherein the guide has a round bar shape. 4. The apparatus according to claim 1, wherein the guide has a shape in which two round bars are arranged. 5. The optical element molding apparatus according to claim 1, further comprising a parallelism adjusting mechanism for adjusting two of the three guides.