JPH01257143A - Press forming method for glass lens - Google Patents

Abstract

PURPOSE:To shorten the time for heating and to prevent the deterioration of a punch and a die by forming fitting hole of the loose fitting hole of a flask die to a stepped sectional shape, receiving the glass material charged into the die by the stepped part and heating the material without bringing the material into contact with the punch and the die, then pressing the material. CONSTITUTION:The loose fitting hole of the flask die 1 is formed to the stepped shape which is larger in the sectional shape of the part 1a to be loosely fitted with the punch 2 than the sectional shape of the part 1b to be loosely fitted with the die 3. Further, the loose fitting hole 1a is formed to the shape that the glass material 6 charged therein can be received by the stepped part 1c. The glass material 6 charged into the hole 1a is received by the stepped part 1c and while the contact of the punch 2 and the die 3 with the glass material 6 is prohibited, the glass material is heated to the temp. above the glass transition point. The heated glass material 6 is then press-formed by the punch 2 and the die 3, by which the glass lens 6' is produced.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method of press molding a glass lens, and in particular, the present invention relates to a press molding method for a glass lens, and in particular, a glass material is put into the play hole of a frame mold in which a lower mold is played, and the frame is The present invention relates to a method of molding a glass lens by fitting an upper mold into a fitting hole of a mold and pressing a glass material at a temperature above the glass transition point with the upper and lower molds in the fitting hole of a frame mold.

[Conventional technology]

The above-described conventional press molding method uses a frame mold and upper and lower molds in which the cross-sectional shape of the engagement hole in which the upper and lower molds fit is uniform. Therefore, the glass material introduced into the play hole of the frame mold is stopped by coming into contact with the upper surface of the lower mold, that is, the pressing surface that presses the glass material.

[Problem to be solved by the invention]

In the conventional press molding method described above, when heating the glass material to a molding temperature higher than the glass transition point after inputting it,
Because the glass material is in contact with the pressing surface of the lower mold, it takes time to uniformly heat the glass material, and the pressing surface of the lower mold is in contact with the high-temperature glass material for a long time. There are problems such as deterioration of the molded glass lens, causing devitrification in the molded glass lens, and the tendency for the glass lens to become fused to the lower mold. Even when glass material is put into the mold, the glass material comes into contact with the lower mold when it is put in, so the temperature of the glass material during pressing increases between the lower mold side, the upper mold side, and the lower mold side. There is a problem in that the internal distortion of the glass lens becomes large and it is easily deformed when heat-treated later.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to introduce the glass material into the play hole of the frame mold without contacting the lower mold, and to prevent the glass material from coming into contact with the upper and lower molds until pressing. The purpose of the present invention is to provide a press-molding method for a glass lens that can prevent the lenses from coming into contact with glass materials.

[Means to solve the problem]

In the present invention, a glass material is put into the play hole of the frame mold with which the lower mold is loosely engaged, and the upper mold is loosely engaged with the play hole of the frame shape, and the glass material is placed in the play hole of the frame die. In a method of forming a glass lens by pressing a glass material with a temperature above the glass transition point using a lower die, the engagement hole of the frame mold is set so that the cross-sectional shape of the engagement area of the upper die is larger than the cross-sectional shape of the engagement area of the lower die. The cross-sectional shape of the upper mold and the frame are shaped so that the stepped part of the upper mold and the frame mold are larger, and the glass material to be introduced into the joint hole can be stopped at the stepped part of the upper mold and the frame mold. The present invention provides a press-molding method for a glass lens, characterized in that the mold is not brought into contact with the glass material introduced until the glass material is pressed, and this structure achieves the above object.

[For production]

That is, in the method of the present invention, since the glass material introduced into the engagement hole of the frame mold with which the lower mold is loose is stopped at the stepped part of the engagement hole, the glass material is inserted into the upper die and the lower die. The glass material can be brought into contact with the glass material for the first time when it is pressed. Therefore, even if the glass material is heated after being charged, it can be heated relatively easily and uniformly, and the upper and lower molds can be heated to the high temperature glass material. The contact time is short (this makes it possible to press the glass material at a uniform temperature even when glass material that has been heated to the molding temperature in advance is used, making it possible to mold glass lenses with less internal distortion. .

〔Example〕

The present invention will be explained below using illustrated examples.

Figure 1.2 is a sectional view before pressing and at the end of pressing, showing an example of the forming method of the present invention, Figure 3.4 is a similar partial sectional view showing a different example, and Figure 5 is a press showing a different example. It is a partial sectional view at the end.

In the figure, 1 is a frame mold, 2 is an upper mold, 3 is a lower mold, 4 is a table of a press machine, 5 is a fixing means for fixing the frame mold 1 to the table 4, 6 is a glass material, and 6' is a press-molded material. Glass lens 7 is placed on the lower mold 3.

It is a plunger that moves downward.

The glass material 6 is dropped into the opening 1a of the opened frame 1 by raising the upper mold 2 above the upper end of the frame 1 by a lifting means (not shown) into the opening 1a where the upper mold 2 of the frame 1 is fitted. In rare cases, the cross-sectional shape of the lower engagement hole 1b where the lower die 3 engages is smaller than the cross-sectional shape of the engagement hole 1a. and does not come into contact with the lower mold 3.

If the glass material 6 charged in the above manner has been previously heated to a molding temperature higher than the glass transition point, the upper mold 2 is lowered into the play hole 1a of the frame mold 1 by the elevating means, and the lower mold 3 is lowered. The first one is raised by the plunger 7,
The state shown in FIG. 3 is brought to the state shown in FIG. 2.4.5, thereby forming a glass lens 6'. The molded glass lens 6' is produced by raising the upper mold 2 above the upper end of the frame mold 1, and using the plunger 7 to raise the lower mold 3 so that the glass lens 6' protrudes beyond the upper end of the frame mold 1. It can be easily removed from the mold by letting it slide.

If the temperature of the charged glass material 6 is lower than the molding temperature, the upper mold 2 is raised above the frame mold 1 when the glass material 6 is charged, or preferably, the upper mold 2 is raised above the frame mold 1. The first plate is lowered into the play hole 1a of the frame mold 1 without contacting the material 6. The glass material 6 is heated to the molding temperature in the state shown in FIG.

Heating is performed by placing the frame 1, upper and lower molds 2, 3, etc. in a heating furnace, or by having a heater embedded in the frame 1, upper and lower molds 2, 3, etc.

In addition, in the frame 1 shown in FIG. 1, the upper peripheral wall of the play hole 1a has a fir split groove 1d and is shaped like a windsock. It can be heated evenly. Once the glass material 6 reaches the molding temperature, the glass lens 6' is press-molded and removed from the mold in the same manner as described above.

In the method of the present invention, the lower mold 3 is particularly
As shown in the figure, the pressing surface on the upper end surface is the glass lens 6'.
The fact that it consists of a surface 3a forming an optical surface and a surrounding frame surface 3b prevents the rise of the glass lens 6' caused by the play gap between the frame mold 1 and the lower mold 3 from affecting the optical surface. It is preferable to remove it without any problems. FIG. 5 shows an example of molding a convex lens whose optical surface does not come into contact with the table surface even if the device is placed on a flat table.

〔Effect of the invention〕

According to the press forming method of the present invention, it is possible to prevent the upper and lower molds from coming into contact with the glass material charged into the frame mold until the time of pressing. Can be done uniformly in time,
This has the effect that the pressing surface of the lower mold does not deteriorate due to long contact with high-temperature glass material, and even when press-molding glass material that has been heated to the molding temperature in advance, glass lenses with less internal distortion can be obtained. The effect is that it can be molded.

[Brief explanation of the drawing]

Figure 1.2 is a sectional view before pressing and at the end of pressing, showing an example of the molding method of the present invention, Figures 3 and 4 are similar partial sectional views showing different examples, and Figure 5 is a press showing a different example. It is a partial sectional view at the end. 1... Frame shape, la, lb... play hole, 1c... step part, 1d... vertical groove,
2... Upper mold, 3... Lower mold, 3a...
- Optical surface forming surface, 3b... Surrounding frame surface, 4... Press machine table, 5... Fixing means, 6... Glass material, 6'... Glass lens, 7... Plunger .

Claims (1)

[Claims] The glass material is put into the play hole of the frame mold where the lower mold is loosely matched, and the upper mold is loosely matched with the play hole of the frame mold, and the glass material is poured into the play hole of the frame mold by the upper and lower molds in the play hole of the frame mold. In a method of molding glass lenses by pressing glass materials with a temperature above the transition point, the compatibility hole of the frame mold is made so that the cross-sectional shape of the mate- riable part of the upper mold is smaller than the cross-sectional shape of the mate- ble part of the lower mold. The upper mold and the lower mold mating with the mating hole of the frame mold are shaped so that the glass material introduced into the mating hole can be stopped at the stepped part of the mating hole. A method for press-molding a glass lens, characterized in that the glass lens is not brought into contact with the glass material until the material is pressed.