JPH0717723A - Method and apparatus for forming optical element - Google Patents

Abstract

PURPOSE:To press form optical elements which are free from sink marks. CONSTITUTION:A lower planar heating member 29 and upper planar heating member 30 which are previously heated by a lower plate material heating furnace 31 and upper plate material heating furnace 32 are respectively pressed to a forming surface 23 of a lower mold 22 and a forming surface 27 of an upper mold 26 just before press forming of a glass blank material 4 at the time of heating this blank material to soften in both upper and lower heating furnaces 17, 18 and press forming the blank material with the lower mold 22 and the upper mold 26. As a result, the forming surfaces 23, 27 of the parts for forming the thin parts of the optical elements are heated and the cooling rate of the thin parts during the press forming of the glass blank material 4 is lowered, by which the temp. difference from thick parts is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element molding method and molding apparatus in which an optical material such as glass is heated and softened and pressure-molded to obtain an optical element.

[0002]

2. Description of the Related Art In a molding method and a molding apparatus in which a glass material is heated and softened and then pressure-molded, a pair of molding dies having a molding surface corresponding to a desired optical element shape is used. There is. In order to prevent sink marks due to a temperature difference generated inside the glass during such pressure molding, conventionally, a molding die and a molding method have been proposed in the following publications.

Japanese Patent Publication No. 20855/1992 discloses a molding die in which one of the molding dies opposed to each other is divided into an annular shape and the temperature of the divided mold members can be set separately. Has been done. Further, Japanese Patent Laid-Open No. 2-133325 discloses a molding method for heating and softening a glass material such that the thin portion of the glass material is heated to a temperature higher than that of the thick portion.

[0004]

[Problems to be Solved by the Invention] However, Japanese Patent Publication No. 4-2
Since the molding die of the 0855 publication has a divided structure,
Since a dividing line is generated on the optical element surface, it is necessary to divide the dividing line so that the dividing line does not serve as an optical function surface. Therefore,
If the optical function surface is equal to or close to the outer diameter of the optical element, there is a problem that it cannot be used.

Further, in JP-A-2-133325, in order to provide a temperature difference in the glass material, the heating heater is brought close to the glass material to cause the temperature difference, but in reality, the diameter of the heater is There is a problem that it cannot be used for large and small aperture lenses. Further, even when the temperature difference is produced by spraying the gas, the gas flows, so that it is difficult to provide the spot-like temperature difference in the case of the small aperture lens.

The present invention has been made in view of the above-mentioned problems of the prior art. Even when the optical function surface is equal to or close to the outer diameter of the optical element, or when the lens has a small aperture, An object of the present invention is to provide an optical element molding method and a molding apparatus capable of obtaining a highly accurate optical element without sink marks.

[0007]

In order to achieve the above object, the present invention is to press a glass molding material by sandwiching the glass molding material between a pair of molding dies having a desired molding surface shape after heating and softening the glass molding material. In the optical element molding method of molding to obtain an optical element, a pre-heated plate-shaped heating member is brought into contact with the molding surface immediately before press molding a glass molding material that has actually been softened by heating.

Further, a glass molding material for molding a desired optical element is used for the plate-shaped heating member, and the glass molding material is heated and brought into contact with the molding surface of the molding die, and then the glass molding material is molded on the molding surface. It may be separated from the mold, heated and softened again, and press-molded by the above-mentioned mold.

Further, the present invention is an optical element molding apparatus for press-molding a glass molding material by heating and softening the glass molding material and sandwiching the glass molding material with a pair of molding dies having a desired molding surface shape. A plate-shaped heating member for heating,
A heating furnace for heating the plate-shaped heating member, and a conveying means for conveying the plate-shaped heating member between the heating furnace and the pair of molding dies were provided.

[0010]

According to the optical element molding method and molding apparatus having the above construction, when a pre-heated plate-shaped heating member is brought into contact with the molding surfaces of a pair of molding dies, the molding surface for convex lens molding has a concave molding surface shape. Therefore, it contacts the outer edge of the molding surface, and contacts the center of the molding surface because the molding surface for concave lens molding has a convex shape. Then, the portion in contact with the plate-shaped heating member is heated by the heating member, and a temperature distribution occurs in the molding die in which the portion forming the thin portion of the molded lens is in a high temperature state. In this state, when the heat-softened glass molding material is sandwiched between the molding surfaces of a pair of molding dies and press-molded, the temperature of the molding surface of the portion corresponding to the thin portion of the molded lens is high. Very fast cooling slows down the thin part of the glass molding material. Therefore, the temperature difference between the thin portion and the thick portion in the glass molding material disappears,
The heat-damaged part disappears and the sink mark does not occur on the lens that has been molded.

When the glass molding material is used for the plate-shaped heating member, when the glass molding material is brought into contact with the heating member for heating the molding surface, the glass molding material is slightly deformed along the shape of the molding surface. Thereby, when the glass molding material is heated again and press-molded, the deformation amount (flow amount) of the glass molding material is reduced.

[0012]

Embodiment 1 FIG. 1 is a sectional view showing Embodiment 1 of the optical element molding apparatus according to the present invention. Molding machine body 1 of molding machine
Is provided with a lower base 2 and an upper base 3 having a U-shaped cross section, and the lower base 2 and the upper base 3 supply the glass material 4 with a supply section 5, the glass material 4 with a heating and softening section 6 and the glass material 4 with pressing force. A space 9 in which the molding unit 7 and the molding die partial heating unit 8 are installed is formed.

Side direction of the upper base 3 (right side in the figure)
A guide rail 10 having one end inserted in the space 9 is installed on the lower base 2. A transport arm 11 is provided on the guide rail 10 via a movable pedestal 12 so as to be movable left and right in the space 9. A transport tray holding portion 13 is provided at the tip of the transport arm 11 so that the transport tray 14 holding the glass material 4 of the supply portion 5 can be placed.

The supply section 5 is provided with a carrier tray carrier 15, a cylinder 16 and a stocker (not shown), and the carrier tray carrier 15 installed on the lower base 2 moves up and down by the cylinder 16 to move the glass. The transport tray 14 holding the material 4 is lifted from the stocker so that the transport tray 14 can be placed on the transport tray holder 13.

A heating and softening section 6 is provided on the left side of the supply section 5. The heating and softening section 6 is configured such that the glass material 4 is arranged between the upper heating furnace 17 attached to the upper base 3 and the lower heating furnace 18 attached to the lower base 2 via the transfer arm 11. There is.

On the left side of the heating and softening section 6, a pressure molding section 7 is provided. A main shaft 20 is provided in the press-molding section 7 so as to be vertically movable via a main shaft lifting device 19 attached to the lower base 2. A lower die mounting seat 21 is fixed to the upper end of the main shaft 20, and a lower die 22 is mounted on the lower die mounting seat 21 with a lower die molding surface 23 facing upward. A lower die heater 24 that heats the lower die 22 to a predetermined temperature is provided around the lower die 22. On the other hand, an upper die 26 is attached to the upper base 3 via an upper die mounting seat 25. The upper die 26 is disposed coaxially with the lower die 22 so that the upper die molding surface 27 faces downward and faces the lower die molding surface 23, and the upper die heater 28 is provided around the upper die 26.
Is provided.

A molding die partial heating unit 8 is provided on the left side of the press molding portion 7. The molding die partial heating unit 8 includes a lower plate-shaped heating member 29 and an upper plate-shaped heating member 3 which partially heat the lower mold molding surface 23 and the upper mold molding surface 27, respectively.
0, a lower plate material heating furnace 31 that heats the lower plate heating member 29 and an upper plate material heating furnace 32 that heats the upper plate heating member 30, and the lower plate heating member 29 and the upper plate heating member 30 in the left and right directions, respectively. A moving means for moving up and down is provided.

The lower plate heating furnace 31 is installed on the lower base 2 and is provided on the left side of the lower mold 22, and the upper plate heating furnace 32 is installed on the upper base 3 above the lower plate heating furnace 31.

On the left side of the lower plate heating furnace 31, a moving means for the lower plate heating member 29 is provided. The moving means includes a lower guide rail 33, a lower moving pedestal 34, a cylinder 35, and an arm 36. Lower guide rail 33
Is installed on the lower base 2 on the left side of the lower plate heating furnace 31. The lower guide rail 33 has a lower moving base 34.
Is slidably provided in the left-right direction, and the cylinder 35 is mounted on the lower moving base 34. The cylinder 35 is
The piston shaft 37 is arranged so as to face upward. An arm 36 is attached to the piston shaft 37, and the lower plate heating member 29 is attached to the tip of the arm 36.

On the left side of the upper plate heating furnace 32, a moving means for the upper plate heating member 30 having the same structure as the above moving means is provided. That is, an upper guide rail 38 is attached to the upper base 3 on the left side of the upper plate heating furnace 32, and an upper moving pedestal 39 is attached to the upper guide rail 38.
Is slidable left and right. A cylinder 40 is attached to the lower surface of the upper moving pedestal 39 with its piston shaft 41 facing downward, and an arm 42 having the upper plate-shaped heating member 30 attached to its tip is attached to the piston shaft 41. There is.

Next, a method of molding an optical element using the molding apparatus having the above structure will be described with reference to FIGS.
First, the transport tray 14 holding the glass material 4 is placed from a stocker (not shown), and then placed on the transport tray holder 13 at the tip of the transport arm 11. And the guide rail 1
0 move the pedestal 12 to the left to move the transfer arm 1
The carrier plate 14 is inserted and arranged between the upper and lower heating furnaces 17 and 18 via the 1 to heat and soften the glass material 4 until it has a desired viscosity. On the other hand, the upper and lower plate material heating furnaces 32 and 31 are previously prepared.
Both upper and lower plate-shaped heating members 30, which are inserted and heated
29 is moved to the right by the upper and lower guide rails 38 and 33 and the upper and lower moving pedestals 39 and 34 to the right just before the heating and softening of the glass material 4 is completed, and the upper and lower mold forming surfaces 27 and 23 are formed.
Insert between and stop. Then, the piston shaft 37 is lowered by the cylinder 35 to bring the lower plate-shaped heating member 29 into contact with the central portion of the lower die molding surface 23, and the cylinder 40.
The piston shaft 41 is lifted by the upper plate-shaped heating member 30.
Is brought into contact with the central portion of the upper die molding surface 27. At this time, lower mold 2
As shown in FIG. 2, a high temperature portion H is formed around the portion where the plate-shaped heating members 29 and 30 are in contact with each other, and a temperature distribution is generated in the lower die 23 and the upper die 26. Note that FIG.
Shows a case where a concave mold 43 for molding a convex lens is used. In this case, the mold 44 is in contact with the outer periphery of the molding surface 44, and a high temperature portion H is formed around the portion, and the mold 44 is formed.
Temperature distribution occurs.

Next, the piston shaft 37 is raised and the piston shaft 41 is lowered by the cylinder 35 and the cylinder 40 to form the lower plate-shaped heating member 29 and the upper plate-shaped heating member 30 in the upper and lower mold molding surfaces 23 and upper mold, respectively. Away from surface 27,
The upper and lower moving seats 39, 34 can be moved leftward to return the upper and lower plate-shaped heating members 30, 29 between the upper and lower plate-shaped heating furnaces 32, 31.

Immediately thereafter, the glass material 4 softened by heating to a desired viscosity is inserted between the lower mold 22 and the upper mold 26 by the transfer arm 11. Then, the lower die 22 is raised by the spindle lifting device 19, and the glass material 4 is sandwiched between the lower die molding surface 23 and the upper die molding surface 27 to perform press molding. At this time, in the upper and lower molds 22 and 26, since the portion for molding the thin portion (center portion) of the molded lens is in a high temperature state due to the plate-shaped heating members 30 and 29, when the glass material 4 is press-molded, The thin portion and the thick portion of the glass material 4 are cooled substantially evenly. After the cooling is completed, the lower die 22 is moved to the main shaft lifting device 19
Then, the molded lens is lowered together with the transport tray 14 and placed again on the transport tray holder 13 of the transport arm 11. Then, the moving pedestal 17 is moved to the right, and the transport tray 14 is returned to the stocker transport tray 15 and collected by the stocker.

According to the present embodiment, before the glass material 4 is press-molded, the upper molds 26 and 22 for molding the thin portion of the molded lens can be heated to a high temperature. During the cooling process, there is no temperature difference between the thin portion and the thick portion of the glass material 4, and heat accumulation is not possible.
It is possible to obtain a highly accurate optical element without sink marks.

[0025]

[Embodiment 2] FIG. 4 is an explanatory view for explaining a main part of Embodiment 2 of the present invention. In the molding apparatus of the present embodiment, the lower plate-shaped heating member 45 (upper plate-shaped heating member 46) that partially heats the lower mold 22 (upper mold 26) has a soft or elastic member in a desired heating state. It is formed and provided. Other configurations are the same as those in the first embodiment.

In the present embodiment, since the heated upper and lower plate-shaped heating members 46, 45 are soft or elastic, the upper and lower molding surfaces are in contact with each other. Other molding methods and operations are the same as in Example 1.

According to this embodiment, the plate-shaped heating members 45, 4
Since the contact of 6 with the molding surface is surface contact, it is possible to more effectively form the high temperature portion H in the upper and lower molds 26 and 22, and it is possible to obtain a highly accurate optical element without sink marks. Other effects are the same as those of the first embodiment.

[0028]

[Embodiment 3] FIGS. 5 and 6 are a front view and a plan view showing an essential part of a molding apparatus according to the present invention. The molding apparatus of this embodiment is characterized in that the moving means and the plate-shaped heating member in the molding die partial heating unit 8 shown in FIG.
It is a point that is configured into individual pieces. In this embodiment, similarly to the first embodiment, the moving base 47 is mounted on the guide rail 33 installed on the lower base.
Is mounted so that it can move in the left-right direction,
The arm 52 is directly attached to the top of the 1. As shown in FIG. 6, the tip of the arm 48 is bifurcated, and long holes 53 are vertically formed in both side surfaces of the bifurcated front end. Pins 54 cut out along the long holes 53 are fitted in the long holes 53 so as to be slidable in the vertical direction, and a plate-shaped heating member 55 is fixed to the tip of the pins 54. . That is, the plate-shaped heating member 55 is freely movable in the up-and-down direction while maintaining the horizontal state by the pin 54 at the branched portion of the arm 48.
It is held at 8. Other configurations are the same as those in the first embodiment.

Next, the molding method of this embodiment will be described with reference to FIGS.
Only parts different from the first embodiment will be described using. The plate-shaped heating member 55 heated in the upper and lower plate material heating furnaces 32 and 31 (see FIG. 1) is moved to the right by the moving base 51 and inserted between the upper and lower molds 26 and 22. Then, the lower die 22 is raised by the spindle lifting device 19 (see FIG. 1), and the lower die molding surface 23 and the lower surface of the plate-shaped heating member 55 are brought into contact with each other as shown in FIG. 7. Further, the lower die 22 is raised to raise the plate-shaped heating member 55.
Is lifted to bring the upper die molding surface 27 into contact with the upper surface of the plate-shaped heating member 55, and the plate-shaped heating member 55 is sandwiched between the upper die molding surface 27 and the lower die molding surface 23 as shown in FIG. At this time, a temperature distribution is generated in the upper and lower molds 26, 22 such that the portion corresponding to the thin portion of the molded product is in a high temperature state. Then, the lower die 22 is lowered by the spindle lifting device 19, and the plate-shaped heating member 55 is moved by the moving base 51 to heat both upper and lower plate material heating furnaces 32, 3.
Return to within 1.

According to this embodiment, since the plate-shaped heating member 55 of the mold partial heating unit and its moving means can be constructed by one, the cost of the molding apparatus can be reduced.
Other effects are the same as those of the first embodiment.

[0031]

Fourth Embodiment FIG. 9 shows a fourth embodiment of the molding apparatus according to the present invention.
FIG. In the molding apparatus of this embodiment, the molding die partial heating unit 60 has the same structure as the glass material conveying device, the supply unit 5 and the heat softening unit 6 of FIG.
That is, the molding machine body 61 has a bilaterally symmetrical structure with the press molding portion 7 as the center.

A guide rail 62 is installed on the lower base 2 of the molding die partial heating unit 60.
A moving base 63 is attached to the unit 2. Moving base 6
A transfer arm 64 is attached to the upper part 3 and is movable in the left-right direction via a moving base 63 guided by a guide rail 62.

A transport tray holding portion 65 is formed at the tip of the transport arm 64, and the transport tray transport base 66 installed on the lower base 2 is moved up and down by the cylinder 67, so that the glass material 4 serving as a plate-shaped heating member. The transport tray 68 holding the above can be lifted from a stocker (not shown) and placed on the transport tray holder 65. On the right side of the cylinder 67,
An upper heating furnace 69 attached to the upper base 3 and a lower heating furnace 70 attached to the lower base 2 are vertically opposed to each other. Other configurations are the same as those in the first and third embodiments.

In the molding apparatus having the above structure, in the molding die partial unit 60, the transport tray 6 holding the glass material 4 used for the plate-shaped heating member from the stocker (not shown).
8 is placed on the transfer tray transfer table 66, and the transfer arm 64
The transport tray 68 is placed on the transport tray holder 65 at the tip of the. Next, the moving pedestal 63 on the guide rail 62 is moved, and the transfer dish 68 is inserted between the upper heating furnace 69 and the lower heating furnace 70 via the transfer arm 64 until the glass material 4 reaches a desired temperature. Heat and soften. Then, after the glass material 4 is heated and softened, the movable pedestal 63 is moved to insert the transport tray 68 between the lower die 22 and the upper die 26.

Next, the lower die 22 is lifted by the spindle lifting device 19 to lift the glass material 4 together with the carrying tray 68,
As shown in FIG. 10, since the glass material 4 is sandwiched between the lower mold molding surface 23 and the upper mold molding surface 27, and no pressure is applied, only the upper and lower molding surfaces 27, 23 for molding the thin portion of the molded product are in contact with each other. Let At this time, the temperature of the portion in contact with the glass material 4 becomes high, and a temperature distribution occurs in the upper and lower molds 26, 22.

Thereafter, the lower die 22 is moved by the spindle lifting device 19.
Is lowered and the transport tray 68 together with the glass material 4 is placed on the transport tray holding portion 65 of the transport arm 64 again. Then, the transfer tray 68 is placed on the transfer arm 64 and is returned to the transfer tray transfer table 66 by the reverse procedure, and is collected in the stocker.

The glass material 4 collected in the stocker is
After that, it is moved to the supply unit 5 side in FIG. 9 and placed on the transfer arm 11 according to the procedure shown in the first embodiment, and heated and press-molded in the same manner as in the first and third embodiments.

According to this embodiment, since the glass material 4 used for molding the optical element is used as the plate-shaped heating member, when the high temperature parts are partially formed in the upper and lower molds 26 and 22, the glass material 4 is vertically moved. Since the glass material 4 is slightly deformed along the shapes of the molding surfaces 27 and 23, the deformation amount of the glass material 4 is reduced in the main molding in the next step, and a more accurate optical element can be obtained. Other effects are the same as those of the first and third embodiments.

[0039]

As described above, according to the present invention, it is possible to heat a molding surface portion for pressing and molding a thin portion of a desired optical element by a plate-shaped heating member to provide a temperature difference on the molding surface. Therefore, a temperature difference does not occur between the thick portion and the thin portion of the glass molding material during press molding of the glass molding material, the heat damaging portion is eliminated, and a highly accurate optical element without sink marks can be obtained. Further, by using the glass molding material for the plate-shaped heating member, when the heating member is brought into contact with the molding surface, it is slightly deformed along the shape of the molding surface. Therefore, when the glass molding material is press-molded, the amount of deformation (fluidity) of the glass molding material is small, and a more accurate optical element can be molded.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of an optical element molding apparatus according to the present invention.

FIG. 2 is an explanatory diagram for explaining the operation of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram for explaining the operation of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating a main part of a second embodiment of the present invention.

FIG. 5 is a front view showing a main part of a third embodiment of the molding apparatus according to the present invention.

FIG. 6 is a plan view showing a main part of a third embodiment of the molding apparatus according to the present invention.

FIG. 7 is an explanatory diagram for explaining one step of Example 3 of the molding method according to the present invention.

FIG. 8 is an explanatory diagram for explaining one step of Example 3 of the molding method according to the present invention.

FIG. 9 is a cross-sectional view showing a fourth embodiment of the molding apparatus according to the present invention.

FIG. 10 is an explanatory diagram for explaining one step of Example 4 of the molding method according to the present invention.

[Explanation of symbols]

 4 glass material 22 lower mold 23 lower mold molding surface 26 upper mold 27 upper mold molding surface 29,45 lower plate heating member 30,46 upper plate heating member 31 lower plate heating furnace 32 upper plate heating furnace 55 plate heating member

Claims (3)

[Claims] 1. An optical element molding method for obtaining an optical element by sandwiching a glass molding material between a pair of molding dies having a desired molding surface shape and press-molding after softening the glass molding material by heating. An optical element molding method, characterized in that a plate-shaped heating member which has been heated in advance is brought into contact with the above-mentioned molding surface immediately before press-molding the heat-softened glass molding material. 2. A glass molding material for molding a desired optical element is used for the plate-shaped heating member, and the glass molding material is heated and brought into contact with the molding surface of the molding die, and then the glass molding material is molded on the molding surface. 2. The method for molding an optical element according to claim 1, wherein the optical element is separated from the mold, heated and softened again, and press-molded by the molding die. 3. An optical element molding apparatus for heating and softening a glass molding material and sandwiching it between a pair of molding dies having a desired molding surface shape for press molding, and a plate shape for partially heating the pair of molding dies. Of the heating element, a heating furnace that heats the plate-shaped heating member, and a conveying unit that conveys the plate-shaped heating member between the heating furnace and the pair of molding dies. .