JP2000143255A - Press forming device for optical lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly heat the upper and lower molds for pressing a forming blank and to reduce the consumption of the inert gas to be supplied at the time of forming. SOLUTION: This device has a pair of the molds 11 and 12 for press forming the forming blank 10, a sleeve 24 for enclosing the outer side of a pair of the molds 11 and 12 and a heater 25 for heating a pair of the molds. The device is provided with a hermetic closing means for maintaining a hermetic state in the sleeve 24, by which the consumption of the inert gas from the gas supplying means 21 is reduced. The sleeve 24 is formed of transparent quartz glass to allow the transmission of the radiation heat generated from the heater 25 through the sleeve, by which the upper and lower molds 11 and 12 are rapidly heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a press forming apparatus for press forming an optical lens.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional press molding apparatus for an optical lens, and FIG. 5 shows a press molding apparatus disclosed in Japanese Patent Publication No. 8-22757.

In the press molding apparatus shown in FIG. 4, a molding die member 5 is placed in a chamber (not shown) filled with an inert gas.
7 are arranged. The molding member 57 includes a pair of molding dies including an upper mold 53 and a lower mold 54 for molding the molding material 56, and a sleeve 55 for guiding the upper and lower dies 53 and 54. The heater 52 is in contact with the outer surface of the sleeve 55, and the upper and lower dies 53 and 54 are located at the center inside the heater 52.

In this press forming apparatus, a heater 52 as a heat source gives heat to the outer surface of a sleeve 55 to heat the sleeve 55. The upper and lower dies 53 and 54 are fitted inside the sleeve 55 and are indirectly heated by the sleeve 55, and then the molding material 56 located between these dies 53 and 54 is indirectly heated. And press molded.

[0005] In the press forming apparatus shown in FIG.
0 is provided with a heat-resistant glass tube 41 filled with an inert gas.
5 and an upper die 42 and a lower die 43 for pressing
There is provided a mold member comprising a positioning member 44 for positioning the components 2 and 43. A gas inlet 47 is formed in the upper fixed plate 46 so as to communicate with the inside of the glass tube 41. The gas inlet 47 is adapted to perform a cooling action by supplying an inert gas into the glass tube 41 during the molding cycle of the optical lens, and the gas thus introduced is supplied to the lower fixed plate 48. The air is exhausted from an exhaust port 49 opened to the outside.

Further, the upper mold 42 and the lower mold 43 are attached to the mold attaching members 61 and 62, respectively. Gas inlets 50 and 51 for supplying an active gas to cool the upper mold 42 and the lower mold 43 are provided. The inert gas introduced from the gas inlets 47, 50, 51 passes through the glass tube 41 and is exhausted from the exhaust hole 49 opened in the lower die fixing plate 48.

[0007]

However, in the conventional press forming apparatus shown in FIG. 4, the heat generated from the heater 52 is applied only to the outer peripheral surface of the sleeve 55, and is fitted inside the sleeve 55. The molding material 56 between the upper mold 53, the lower mold 54, and the upper and lower molds 53, 54 cannot be directly heated. As described above, indirect heating using only heat conduction from the sleeve 55 has a problem that the heating time is long.

On the other hand, in the press forming apparatus shown in FIG. 5, in order to cool the upper and lower dies 42 and 43 and to cool the positioning member 44, an inert gas is provided in the upper and lower mold mounting members 61 and 62 and the glass tube 41. And therefore, there is a problem that a large amount of inert gas is required.

The present invention has been made in consideration of such conventional problems, and can reduce the time required for raising the temperature of upper and lower molds and molding materials, and reduce the amount of inert gas to reduce energy consumption. It is an object of the present invention to provide an optical lens press molding device capable of reducing the number of optical lenses.

[0010]

Means for Solving the Problems To achieve the above object, the invention of claim 1 comprises a pair of dies for press-molding a molding material, a sleeve surrounding the outside of the pair of dies, and a pair of dies via the sleeve. A press forming apparatus having a heater for heating the mold, a gas supply unit for supplying an inert gas into the sleeve, and a sealing unit for sealing the inside of the sleeve in an airtight state, and the sleeve is generated from the heater. It is formed of transparent quartz glass that transmits radiant heat.

In the present invention, since the sealing means makes the inside of the sleeve airtight, the amount of inert gas supplied into the sleeve by the gas supply means can be reduced, and the amount of inert gas can be reduced. Further, since the sleeve transmits the radiant heat from the heater, the upper and lower molds and the molding material can be directly heated. For this reason, the heating time can be shortened. Also in this case, since the inside of the sleeve is airtight, efficient heating can be performed.

According to a second aspect of the present invention, there is provided the first aspect of the present invention, wherein a guide made of a heat insulating material for slidably supporting the upper and lower molds is provided inside the sleeve. I do.

In the present invention, since the guide for slidably supporting the upper and lower molds is made of a heat insulating material, the heat taken by the guide is reduced. Therefore, the temperature of the upper and lower molds and the molding material can be raised in a short time.

A third aspect of the present invention is the invention according to the second aspect, wherein the sleeve and the guide are fitted via a tapered surface that absorbs a difference in thermal expansion coefficient. I do.

In the present invention, since the sleeve is fitted to the guide via the tapered surface, the guide moves in the vertical direction by the difference of the linear expansion coefficient between the sleeve and the guide / taper angle as the temperature rises. shift. By this shift, the positional accuracy of the upper and lower dies to be pressed can be secured, and high-precision pressing can be performed.

[0016]

FIG. 1 is a sectional view of an embodiment of a press forming apparatus according to the present invention, FIG. 2 is a partial sectional view thereof, and FIG. 3 is a sectional view of a molding die member.

As shown in FIG.
Four columns 3 are erected from above the lower base plate 1, and the upper base plate 2 is supported by the columns 3. On the upper base plate 2, a press mechanism 13 composed of a cylinder or the like whose torque pressure can be controlled is mounted. Also, on the upper surface of the lower base plate 1,
The base 17 is fixed by bolts and the base 1
A molding die member 31 and a heating furnace 26 are supported on 7.

The molding die member 31 comprises a pair of upper and lower dies 11 and 12 for pressing and molding the molding material 10 from above and below, and a sleeve 24 surrounding these outside the upper and lower dies 11 and 12.
And

The upper die 11 is fitted on the lower surface of an upper die mounting member 16 mounted on the upper shaft 15. The rod 13a of the press mechanism 13 faces coaxially above the upper shaft 15, and is connected to the rod 13a so as to be able to move up and down via a pressure detection mechanism including a load cell 14 attached to the lower end of the rod 13a. I have.

FIG. 2 shows the connecting mechanism 8 of the upper shaft 15,
A pair of left and right horizontal connection plates 32 and an upper connection plate 33 that connects upper end portions of the pair of horizontal connection plates 32 are assembled with bolts. Upper connecting plate 3
Reference numeral 3 is located between the rod 13a and the load cell 14, and is connected to these by screws 34.
The pair of horizontal connecting plates 32 have vertically elongated guide grooves 32a.
The guide pin 35 of the upper shaft 15 is slidably inserted into the guide groove 32a.

In such a structure, when the rod 13a of the press mechanism 13 is extended, the connecting mechanism 8 is pushed down. Therefore, while the upper shaft 15 moves downward through the guide pin 35, when the rod 13a is shortened, Since the connecting mechanism 8 is pulled up, the upper shaft 15 can move upward through the guide pins 35. And this upper shaft 15
The upper die 11 moves up and down by the up and down movement of.

The lower die 12 faces the upper die 11 by fitting the lower part to the upper surface of the lower die mounting member 19 and mounting the lower die mounting member 19 on the lower die mounting member 19. Fixed by bolts. The lower die 12 and the upper die 11 supply a cooling medium to the cooling pipe 30 inside the lower die mounting member 19 and the upper die mounting member 16, so that the lower die 12 and the upper die 11 pass through the lower die mounting member 19 and the upper die mounting member 16. It is designed to be cooled.

The sleeve 24 has a tubular shape whose upper and lower ends are open, and extends around the upper mold 11 and the lower mold 12 and the upper and lower ends extend to the upper mold attaching member 16 and the lower mold attaching member 19. , The upper mold 11 and the lower mold 12. A ring-shaped seal ring 22 made of silicon or the like is provided between the upper die mounting member 16 and the sleeve 24 and between the lower die mounting member 19 and the sleeve 24.
The upper and lower seal rings 22 function as a sealing means for sealing the inside of the sleeve 24.

The sleeve 24 is made of transparent quartz glass, and transmits radiant heat from a heater lamp 25 described later. For this reason, the upper mold 11 and the lower mold 12 provided in the sleeve 24 and the molding material 10 set between these molds 11 and 12
Heating is performed by direct heating of the heater lamp 25 via the sleeve 24, and efficient heating can be performed.

The upper and lower guides 2 are provided inside the sleeve 24.
3, 29 and a spring 28 are provided. The upper guide 23 is fitted to the upper mold 11 from outside, and the lower guide 29 is fitted to the lower mold 12 from outside. These upper and lower guides 23 and 29 are made of a heat insulating material such as ceramics, and are formed in a ring shape in which the corresponding molds 11 and 12 are fitted.
A gas supply hole 27 for flowing an inert gas is vertically penetrated through each of the guides 23 and 29.

The outer surfaces of the upper and lower guides 23 and 29 are shown in FIG.
As shown in FIG. 7, tapered surfaces 23a and 29a are formed, and upper and lower guides 23 and
29, the respective tapered surfaces 23a, 2a
Tapered surfaces 24a and 24b facing 9a are formed.
That is, the tapered surface 24 a of the sleeve 24 faces the tapered surface 23 a of the upper guide 23, and the tapered surface 24 b of the sleeve 24 faces the tapered surface 29 a of the lower guide 29. In such a facing state, the upper and lower guides 23, 2
The upper and lower guides 23 and 29 can slide in the moving direction of the upper and lower dies 11 and 12 by fitting the 9 and the sleeve 24 together.

These opposed tapered surfaces are formed by upper and lower molds 1.
The sleeves 1 and 12 are inclined along the direction in which they move, so that the difference in the coefficient of thermal expansion between the sleeve 24 made of quartz glass and the guides 23 and 29 made of a heat insulating material is absorbed. That is, even if the sleeve 24 and the guides 23 and 29 expand due to a temperature change, the difference between the linear expansion coefficients of the sleeve 24 and the guides 23 and 29 is divided by the angle of the tapered surface.
3, 29 are shifted in the direction of movement of the dies 11, 12. For this reason, the positional accuracy of the dies 11 and 12 can be ensured.

A ring-shaped spring 28 is provided between the lower guide 29 and the lower mold mounting member 19. The spring 28 pushes the lower guide 29 upward.

Further, the gas supply pipe 21 is
Is inserted. The gas supply pipe 21 is connected to the upper mold mounting member 16.
Through the sleeve 24 and the upper and lower dies 11, 12
And a base end thereof is connected to an inert gas cylinder (not shown) via an opening / closing mechanism 20 such as a valve. The gas supply pipe 21 serves as a gas supply means for supplying an inert gas into the sleeve 24.
The space between the sleeve 24 and the upper and lower dies 11 and 12 is filled through the gas supply holes 27 of the third and the 29th. Although not shown, the lower die attachment member 19 is provided with a gas discharge pipe having the same configuration as the gas supply pipe 21 to discharge the inert gas supplied into the sleeve 24. Is possible.

A heating furnace 26 is arranged around the above-mentioned molding die member 31. The heating furnace 26 has a bottom plate 5 and an upper plate 6.
It has a tubular frame wall 4 sandwiched between them, and a reflection mirror member 7 provided on the inner surface of the frame wall 4, and a heater lamp 25 is provided inside the reflection mirror member 7.
A plurality of heater lamps 25 are arranged along the length direction of the upper and lower molds 11 and 12, and are lit to heat the upper and lower molds 11 and 12 uniformly.

Next, the operation of the lens forming apparatus of this embodiment will be described. Placing the molding material 10 on the lower mold 12,
The press mechanism 13 is operated to move the upper mold 11 toward the lower mold 12 via the upper shaft 15. Initially, the upper die 11 is moved to a position where a load is not applied to the molding material 10 by controlling the torque by the load cell 14.

At this time, by opening the opening / closing mechanism 20, an inert gas such as nitrogen having a temperature equal to or higher than room temperature is introduced from the gas supply pipe 21 into the molding die member 31. The introduced inert gas is supplied to the gas supply holes 27 of the upper die attaching member 16.
From the inside of the sleeve 24. When the inert gas reaches a predetermined purge concentration inside the sleeve 24, the opening / closing mechanism 20 is closed.

In this embodiment, since the seal ring 22 is provided between the sleeve 24 and the upper and lower mold mounting members 16 and 19, the inside of the sleeve 24 is airtight and the introduced inert gas is Does not leak outside. Therefore, the amount of the inert gas to be supplied can be reduced, and the consumption of the inert gas can be reduced.

At the same time as supplying the inert gas, the power of the heater lamp 25 is turned on to turn on the heater lamp 25. The radiant heat generated from the heater lamp 25 passes through the sleeve 24 made of transparent quartz glass, and rapidly heats the upper mold 11 and the lower mold 12. At this time, since the sleeve 24 is formed of transparent quartz glass, radiant heat from the heater lamp 25 is transmitted well and the upper and lower molds 11 and
Heat 12 For this reason, the upper and lower dies 11 and 12 and the molding material 10 can be efficiently heated, and the temperature raising time can be shortened. During this heating, the upper mold mounting member 16
A coolant such as water is supplied to a cooling pipe 30 formed inside the lower mold mounting member 19 to cool the seal ring 22 provided on the outer periphery of these members 16 and 19.

By being heated by the heater lamp 25, the molding material 10 is heated and softened. The heat-softened forming material 10 is press-formed under desired forming conditions by a press mechanism 13 controlled in torque by a load cell 14. During this molding, the upper mold 11 and the lower mold 12 are connected to the upper guide 23 provided inside the sleeve 24.
In addition, since the positioning is performed by fitting with the lower guide 29, the accuracy in the shift and tilt directions is guaranteed, whereby the shape of the molding material 10 by pressing can be ensured.

The sleeve 24 made of quartz glass has a different linear expansion coefficient from the guides 23 and 29 made of a heat insulating material.
29 presses the sleeve 24. However, since the sleeve 24 and the guides 23 and 29 are fitted in a tapered shape, the stress applied to the sleeve 24 in the horizontal direction due to heating is dispersed in the vertical direction. Therefore, the upper guide 23 in contact with the upper die 11 moves upward, and the lower guide 29 moves downward while pressing down the spring 28. In this movement, the positional accuracy of the upper die 11 and the upper guide 23 and the positional accuracy of the lower die 12 and the lower guide 27 can be ensured.

During press molding, there is no gas supply into the sleeve 24, and after the desired press molding by the press mechanism 13, cooling of the molded material 10 with an inert gas is started. At this time, the opening / closing mechanism 20 is opened and an inert gas such as nitrogen is supplied from the gas supply pipe 21 into the sleeve 24. This inert gas fills the inside of the sleeve 24 from the gas supply hole 27 of the upper guide 23, and the upper and lower dies 11, 1
2 and the formed molding material 10 are cooled. Even during this cooling, the inert gas does not leak from the inside of the sleeve 24, so that the consumption of the inert gas can be reduced.

When cooling after pressing, a valve (discharge mechanism) for discharging an inert gas is provided to the upper die mounting member 16 or the lower die mounting member 19, and this valve is used to cool the molding material 10. It may be used only when. By doing so, the exhaust efficiency, that is, the cooling efficiency of the molding die member 31 can be improved. When the temperatures of the upper mold 11 and the lower mold 12 reach about 400 ° C., the same cooling effect can be obtained even if the inert gas is switched to normal air. Even during such cooling, the upper and lower dies 11 and 1 are controlled by the upper and lower guides 23 and 29 as in the case of heating.
2 position accuracy can be guaranteed.

According to the above embodiment, the sleeve 24 surrounding the upper mold 11 and the lower mold 12 is formed of transparent quartz glass, and the sleeve 24 and the upper and lower molds 11 and 12 are formed.
Are provided between the upper die 11 and the lower die 12.
The amounts of radiant heat applied to the respective surfaces of the upper and lower dies 11 and 12 can be equalized, and the temperature distribution of the upper and lower dies 11 and 12 can be equalized in a short time. Further, the amount of inert gas used for purging and cooling can be reduced.

[0040]

As described above, according to the first aspect of the present invention, the amount of inert gas supplied into the sleeve can be reduced, and the amount of inert gas can be reduced.
Since the upper and lower molds and the molding material can be directly heated, the time required for heating can be shortened.

According to the second aspect of the present invention, since the heat taken by the guides that slidably support the upper and lower dies is reduced, the temperature of the upper and lower dies and the molding material can be raised in a short time.

According to the third aspect of the present invention, since the sleeve is fitted to the guide via the tapered surface, the positional accuracy of the upper and lower dies can be secured, and a high-precision press can be performed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

FIG. 2 is a partially broken front view illustrating a coupling mechanism.

FIG. 3 is a partially broken front view of a molding die member.

FIG. 4 is a sectional view of a conventional press forming apparatus.

FIG. 5 is a cross-sectional view of another conventional press forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Molding material 11 Upper die 12 Lower die 21 Gas supply pipe 22 Seal ring 23 Upper guide 24 Sleeve 25 Heater lamp 29 Lower guide

Claims (3)

[Claims] 1. A pair of molds for press-forming a molding material,
In a press forming apparatus including a sleeve surrounding the outside of a pair of molds, and a heater for heating the pair of molds via the sleeve, gas supply means for supplying an inert gas into the sleeve; An optical lens press-molding apparatus, comprising: a sealing means for airtightness; and wherein the sleeve is formed of transparent quartz glass that transmits radiant heat generated from a heater. 2. The optical lens press-molding apparatus according to claim 1, wherein a guide made of a heat insulating material for slidably supporting the upper and lower molds is provided inside the sleeve. 3. The press molding apparatus for an optical lens according to claim 2, wherein the sleeve and the guide are fitted via a tapered surface that absorbs a difference in coefficient of thermal expansion.