JPH0481532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure molding method for an optical element, and in particular, an upper mold for molding one functional surface of an optical element and a mold for molding another functional surface of the optical element. The present invention relates to a method of pressure-molding an optical element using a molding die that includes a lower die for forming a functional surface, and a body die for movably holding the upper die and the lower die.

[Prior art] Conventionally, the pressure molding method for such optical elements has been
A pressure molding device as shown in FIG. 6 is used, and the material pressure molded by this device is used as it is as an optical element.

In FIG. 6, 1 is an upper mold for molding one functional surface of the optical element, 2 is a lower mold for molding another functional surface of the optical element, and 3 is a barrel mold for accommodating the upper mold and the lower mold. It is. The upper die 1 is movably held within a body die 3, and the body die 3 and the lower die 2 are held on a holding table 4. Above upper mold 1, lower mold 2 and body mold 3
The mold constructed by is housed in the center of the furnace 5, and this furnace wall forms the inner circumferential wall of the pressurizing device.

A pressure molding chamber 6 surrounded by an upper mold 1, a lower mold 2, and a body mold 3 is formed in the mold,
In order to heat the molding material supplied therein, a thermal radiation heating device including a heating light source 7 such as a halogen lamp and a reflection plate 8 is provided on the inner wall of the furnace 5 . Reference numeral 9 indicates a pressure rod that presses the upper mold 1 during pressure molding.

When pressure molding an optical element using the above-mentioned apparatus, the molding material 10 is inserted into the pressure molding chamber 6, the upper mold 1 is placed on top of the molding material 10, and the molding material 10 into which the molding material 10 is inserted is molded. The entire mold was heated, or the portion 3a of the body mold 3 into which the molding material 10 was inserted was heated by the radiant heating devices 7 and 8, whereby the molding material 10 was heated and softened. Afterwards, the pressure rod 9 is driven by a pressure rod drive means (not shown), the upper mold 1 is pushed down, and the molding material 10 in the pressure molding chamber 6 is compression molded. Molding the desired optical element.

[Problem that the invention seeks to solve]

The pressure molding method for the above optical element is conventional grinding,
Compared to polishing methods, this method has the advantage of shortening the manufacturing time of optical elements, and is now becoming widely used.

However, according to this method, the molding material 10 is
During the long heating time until the temperature at which pressure deformation is possible is reached, the molding material and the mold come into contact at high temperatures. Therefore, as shown in FIG. 7, a problem arises in that bubbles 11 are generated at the contact surface between the molding material and the molding die.

On the other hand, since the molding material and the molding die are in contact with each other before pressure molding reaches a temperature that can change the pressure, the weight of the upper die 1 of the molding die and the molding material 1
Due to the self-deformation caused by the softening of the mold, a part of the molding surface of the upper mold 1 and/or lower mold 2 is transferred to the molding material 10 before pressure molding, and a step 12 etc. is formed on the surface of the molding material. Generates boundaries of form. This step 12 and the like remain on the functional surface of the optical element after molding, resulting in a problem that accurate transfer of the molding surface of the mold is prevented.

Therefore, conventional methods have been adopted to reduce the contact area with the mold by changing the shape of the molding material, but this method requires a large amount of money and advanced technology to produce the molding material, making it economically uneconomical. There are many problems that need to be solved on both a physical and technical level.

Also, a molding material 10 is placed between the upper mold 1 and the lower mold 2.
A method has been proposed in which the upper mold and the lower mold are heated to the same high temperature as the molding material, and the molding material 10, upper mold 1, and lower mold 2 are heated during pressure molding. Defects such as bubbles occur on the contact surface.

[Means to solve problems]

The present invention aims to solve the above-mentioned problems in the conventional pressure molding method for optical elements. When press-molding an optical element using a mold consisting of a lower mold for molding a surface and a trunk mold that holds the upper mold and the lower mold relatively movably, The part where the material is inserted and the part where heat escapes by thermal conduction,
That is, a heat insulating means is provided between the upper mold and/or the lower mold, and the material inside the mold is held at a position apart from the upper mold and the lower mold, and While creating a temperature difference between the molding material and the molding material, the molding material is heated and softened and then pressure molded between the upper mold and the lower mold, thereby molding an optical element with no defects on the surface. To provide a pressure molding method for an optical element that can heat a molding material in a shorter time than conventional methods.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pressure molding method for an optical element according to the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 shows a pressure molding apparatus used in the pressure molding method for optical elements according to the present invention, and in the figure, 1, 2, and 3 respectively indicate an upper die similar to that shown in FIG. The lower mold and torso mold are shown. however,
In the apparatus shown in FIG. 1, an upper die 1 and a lower die 2 are both held in a body die 3 so as to be movable up and down, and both are respectively driven by pressure rod driving means (not shown). Pressure rods 9a and 9 driven by the
attached to b. In Figure 1, 5,
Reference numerals 6, 7, and 8 respectively indicate a furnace, a pressure molding chamber, a heating light source, and a reflecting plate similar to those shown in FIG.

The body mold 3 is a portion 3 into which the molding material 10 is inserted.
a, a portion 3b that holds the upper mold, and a portion 3c that holds the lower mold, and these portions are insulated by a heat insulating material 13. The molding material 10 is held at a position apart from the upper mold 1 and the lower mold 2. In the embodiment shown in FIG. 1, as shown enlarged in FIG. 2, a shoulder 14 is formed on the inner surface of the body mold 3.
The molding material 10 is supported on this shoulder 14 and held at an intermediate position between the upper mold 1 and the lower mold 2.

Figure 3 shows a modification of the above mold.
In this modification, the upper die 1 has a pin 15 slidably disposed in the radial direction of the body die 3 and a spring 16 for pushing the pin inward. The upper mold 1 is
is held so that it does not fall downwards before the forming operation. Further, a support pin 17 is provided protruding from the inner surface of the body mold 3, and the molding material 10 is placed on this pin 17 and held at a position apart from the upper mold 1 and the lower mold 2.

In the pressure molding method of an optical element according to the present invention, as described above, the portion 3a of the body mold 3 into which the molding material 10 is inserted, and the portion 3b that holds the upper mold 1.
By disposing a heat insulating material 13 between the upper mold 2 and the lower mold 2 holding portion 3c, heat of the portion 3a is prevented from being conducted to the portions 3b and 3c, and a heating light source 7 such as a halogen lamp A body-shaped molding material insertion portion 3 is heated by a radiation heating device including a reflection plate 8.
a, and reduce the amount of heat conducted to the upper mold and lower mold holding parts 3b and 3c,
While creating a temperature difference between the molding material 10 and the upper mold 1 and lower mold 2, the molding material 10 is heated and softened,
The upper mold 1 and the lower mold 2 are pressure-molded via pressure rods 9a and 9b, and as shown in FIG. 4, an optical element 1 is formed.
Mold 8.

In the above embodiment, as a means for insulating the portion 3a and the portions 3b, 3c of the body mold 3, a heat insulating material 13 is disposed between these parts, but it is possible to obtain such a heat insulating effect. Possible methods include circulating a cooling liquid (water, oil, etc.) through the heat insulating material 13, or inserting heat-resistant ceramics or the like.

In addition, as a method for efficiently heating the molding material insertion part 3a, the shapes of the heating light source 7 such as a halogen lamp and the reflection plate 8 shown in FIG. 1 are changed to concentrate the heat rays on the molding material insertion part 3a. Further efficiency can be achieved by configuring this and applying a heat ray absorbing paint or the like around the molding material insertion portion 3a.

As described above, in the pressure molding method for optical elements according to the present invention, since the temperature of the upper mold 1 and the lower mold 2 is lower than the temperature of the molding material 10 during pressure molding, the molding material and the upper mold, Defects such as bubbles do not occur on the contact surface 19 with the lower mold. On the other hand, the molding material insertion part 3
Since the heat concentrated in a is efficiently transmitted to the molding material 10, pressure molding can be performed in a shorter time and with less thermal energy than conventional methods.

The pressure molding method according to the present invention can be applied not only to pressure molding of a circular optical element as described above but also to pressure molding of a prism or rectangular optical element.
This method is particularly effective for pressure molding a rectangular optical element with a large lateral area as shown in FIG.

In addition, in the above explanation, an example was explained in which an insulating material was provided between the part of the body mold into which the molding material is inserted and the part that holds the upper mold and the lower mold. In a configuration in which the heat escapes to either the part where the heat escapes or the part which holds the upper mold, a heat insulating material may be provided between the part where the heat escapes and the part into which the molding material is inserted.

〔Effect of the invention〕

As explained above, the method for pressure molding an optical element according to the present invention includes holding a molding material in a molding material insertion part of a body type provided with a heat insulating part, and
By intensively heating this area, the upper and lower molds are at a lower temperature than the molding material during pressure molding, so air bubbles etc. are formed on the optical surface of the molded product that comes into contact with the upper and lower molds. No defects occur, and the optical surfaces of the upper mold and molding can be accurately transferred. In addition, by applying heat ray-absorbing paint to the part where the molding material is inserted, heat is efficiently conducted to the molding material, and even when press molding large-sized optical elements, a large amount of heat energy is not required and the time is efficient and short. It can be pressure molded.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a pressure molding apparatus used in the pressure molding method for optical elements according to the present invention, FIG. 2 is an enlarged sectional view of the mold, and FIG. 3 is a modified example of the mold. 4 is a sectional view showing the state of the molding material during pressure molding, FIG. 5 is a perspective view of a rectangular optical element molded by the method of the present invention, and FIG. 6 is a conventional press FIG. 7 is a cross-sectional view of the molding apparatus showing an optical element molded by the apparatus shown in FIG. DESCRIPTION OF SYMBOLS 1...Upper mold, 2...Lower mold, 3...Body mold, 3a...Molding material insertion part of the barrel mold, 4...Holding stand, 5...Furnace, 6...Pressure molding chamber, 7...Heating light source, 8...Reflection Plate, 9... Pressure rod, 10... Molding material, 11... Air bubble, 12... Step, 13... Insulating material, 14... Shoulder, 15... Pin, 16
... Spring, 17... Support pin, 18... Optical element.

Claims (1)

[Claims] 1. An upper mold for molding one functional surface of an optical element;
A method for pressure molding an optical element using a mold comprising a lower mold for molding other functional surfaces of the optical element, and a body mold for holding the upper mold and the lower mold in a relatively movable manner, A heat insulating means is provided between the part of the body mold into which the molding material is inserted and the part from which heat escapes by heat conduction, and the molding material is held between the upper mold and the lower mold, Pressing of an optical element, characterized in that the molding material is heated and softened while creating a temperature difference between the upper mold and the lower mold and the molding material, and then pressure molded between the upper mold and the lower mold. Molding method. 2. Apply heat ray absorbing paint to the part of the body mold into which the molding material is inserted, and apply heat rays to the above part to make this part hotter than the parts in contact with the upper and lower molds, while keeping the molding material and upper mold together. 2. The method of pressure molding an optical element according to claim 1, wherein the pressure molding is performed between a lower mold and a lower mold.