JPH07165431A - Forming of gob and forming apparatus therefor - Google Patents

Abstract

PURPOSE:To provide a gob forming method capable of forming a gob having not only a desired-shape under surface but a desired-shape upper surface from a softened raw material glass and a forming apparatus therefor. CONSTITUTION:A raw material glass 40 softened by heating is supplied onto a bottom tool 10 for forming the shape of the under surface 50a of a gob 50 and held on the bottom tool 10. After the under surface of the raw material glass bulk 41 held on the bottom tool 10 is cooled to <= the softening temperature of the raw material glass 40 and before the upper surface of the raw material glass bulk 41 is cooled to <= the softening temperature, a top force 20 for forming the shape of the upper surface 50b of the gob 50 is pressed onto the upper surface of the raw material glass bulk 41. Since both the upper and under surfaces of the raw material glass bulk can be formed into desired shapes, a gob having a shape similar to that of the final product such as lens can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a gob used for mold optics (MO) optical parts and the like and a molding apparatus used for the method.

[0002]

2. Description of the Related Art Generally, a MO optical component uses a mirror-like gob (glass lump) having a shape similar to a desired shape. Conventionally, such a gob is, for example, Japanese Patent Publication No.
As described in Japanese Patent Laid-Open No. 4-39846, the molten raw material glass is put into a molding die, and the raw material glass is held in the molding die until it becomes a softening temperature or lower.

The molding die used at that time is opened so as to face the upper side, and the raw material glass melt can be dropped from above the molding die and supplied into the molding die. . Therefore, the lower surface shape of the obtained gob is similar to the molding surface of the molding die, but the upper surface shape of the gob is the surface tension and the diameter of the gob when the raw material melt is cooled and solidified in the molding die. It tends to have a convex shape based on various factors. Therefore, when a general molding die having a concave molding surface is used, a gob having a biconvex shape can be obtained. Therefore, the conventional molding method is suitable for direct molding of a biconvex lens.

[0004]

However, in the above-mentioned molding method, when the melt of the raw material glass is solidified in the molding die, the upper surface shape of the raw material glass cannot be regulated. It is necessary to apply molding means such as press molding to the taken out gob. Above Japanese Patent Publication No. 54-
No. 39846 gazette also describes that fact, and after the step of solidifying the glass in the molding die, the pressing step of molding the solidified glass is continuously performed.

In particular, when manufacturing a biconcave lens or a plano-concave lens, it is possible to mold the lower surface of the gob into a concave shape by using a mold having a convex molding surface.
The shape of the top surface of the obtained gob is significantly different from the shape of the biconcave lens or the plano-concave lens, that is, the concave shape or the flat shape, so that the upper surface side of the gob had to be reshaped into a desired shape. Therefore, there are problems that the molding accuracy of the lens is low, and that a long molding time is required.

The present invention has been made to solve the above problems, and an object thereof is to form a gob having a desired shape not only on the lower surface but also on the upper surface from a softened raw material glass. It is to provide a molding method of a gob that can be performed. Another object of the present invention is to provide a molding apparatus used in the above molding method.

[0007]

In order to achieve the above object, the forming method of the present invention is such that when a gob is formed from a raw material glass softened by heating, the softened raw material glass is used as a lower surface of the gob. The temperature of the lower surface of the raw glass gob held on the lower molding die supplied to the lower molding die for shaping the shape and held on the lower molding die is equal to or lower than the softening temperature of the raw material glass. After that, before the temperature of the upper surface of the raw material glass gob becomes equal to or lower than the softening temperature, an upper molding die for shaping the upper surface shape of the gob is pressed against the upper surface of the raw glass gob.

The molding apparatus used in the above-mentioned molding method is a molding apparatus used when forming a gob from a raw material glass softened by heating, and holds a raw material glass block made of the softened raw material glass. And a lower molding die that molds the lower surface of the raw glass gob into the lower surface shape of the gob, and an upper molding die that is pressed against the upper surface of the raw glass mass to shape the upper surface into the upper surface shape of the gob. , The upper mold has a lower surface temperature of the raw material glass gob held on the lower molding die below a softening temperature of the raw material glass, and then an upper surface temperature of the raw material glass gob is the softening temperature. It is characterized in that it is adapted to be pressed against the upper surface of the raw glass body before it becomes the following.

[0009]

[Function] When the raw material glass softened by heating is supplied and held on the lower mold, the portion of the held raw material glass lump near the lower mold reaches the softening temperature or lower within an extremely short time. Cools and solidifies. As a result, the shape of the lower surface of the manufactured gob becomes extremely close to the shape of the molding surface of the lower molding die.

On the other hand, the upper portion of the raw glass gob is in contact with the atmosphere, and the heat dissipation (cooling ability) of the atmosphere is generally smaller than that of the lower mold. Does not fall below the softening temperature. That is, the raw material glass gob is solidified on the lower side and softened on the upper side on the lower mold.

In this state, when the upper mold is pressed against the upper surface of the raw material glass gob, the upper part of the raw material glass gob is cooled to the softening temperature or lower and solidified, and the top shape of the gob to be produced has the upper shape. The shape is extremely close to the shape of the molding surface. Then, when the upper mold is pressed against the raw material glass gob, the lower part of the raw material glass gob has already been solidified, so that the shape of the lower surface formed earlier does not change.

Therefore, both the lower surface and the upper surface of the raw material glass gob are molded into a desired shape, and a gob having a shape similar to the final shape of a lens or the like is obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a gob molding method and a molding apparatus used therefor according to the present invention will be described with reference to FIG. FIG. 1 shows a schematic configuration of a molding apparatus used in a gob molding method according to the present invention and an example of a molding procedure using the molding apparatus.

First, a gob molding apparatus according to the present invention will be described. As shown in FIG. 1, the molding apparatus 1 includes a lower molding die 10, an upper molding die 20 and a raw glass supply means 30. From the supply means 30, a raw glass 40 is placed on the lower molding die 10. Then, the lower surface shape and the upper surface shape of the supplied raw material glass gob 41 are molded by the lower molding die 10 and the upper molding die 20, respectively, to manufacture the gob 50 having a desired shape.

In the molding apparatus 1 of this example, a plurality of lower molding dies 10 are provided, and are arranged side by side along the periphery of the rotary table, for example. Then, the supply means 30 and the upper molding die 20 are respectively arranged on appropriate places of the passage paths of the plurality of lower molding dies 10.

That is, the empty lower mold 10 starting from the initial position (position (A) in FIG. 1) passes through the position (B) in FIG. 1 and directly below the supply means 30 (position (C) in FIG. 1). When it moves to, the appropriate amount of the raw material glass 40 is dropped from the supply means 30. When the lower molding die 10 on which the dropped raw material glass 40 (raw material glass gob 41) is moved to just below the upper molding die 20 (position (E) in FIG. 1), the upper molding die 2 is moved.
0 descends and is pressed against the raw glass gob 41. The upper molding die 20 is designed to move up when a sufficient time for molding has passed.

From the position of FIG. 1 (C) to the position of FIG. 1 (E) is the cooling process of the raw glass gob 41 on the lower molding die 10 (position (D) of FIG. 1). In this process,
A portion of the raw glass gob 41 near the lower molding die 10 is cooled, and the shape of the lower surface 50a of the gob 50 is molded.

At the position (E) in FIG. 1, the upper part of the raw glass gob 41 is cooled by the upper mold 20, and the shape of the upper surface 50b of the gob 50 is molded. The gob 50 having the upper and lower surfaces 50b and 50a formed into a desired shape is further cooled to room temperature through a cooling process (position (F) in FIG. 1). Then, the gob 50 is taken out by a known means such as a vacuum suction means and a tilting means of the lower molding die 10 at the take-out position (position (G) in FIG. 1).

The empty lower molding die 10 moves to the initial position again and is used for the next gob molding.

The lower mold 10 and the upper mold 2
In No. 0, each of the molding surfaces 11 and 21 is molded into a desired shape and further mirror-finished, so that the gob 50 having a mirror-finished surface can be obtained. As necessary, the lower mold 10 and the upper mold 20 are respectively
In each cooling process of the position (D) and the position (F) in FIG.
In order to cool the lower surface and the upper surface of the raw material glass gob 41 at appropriate cooling rates, they are cooled with cooling water or the like (not shown), or several hundreds of degrees Celsius by a heater or the like (not shown).
It is heated to some extent.

Further, the lower molding die 10 and the upper molding die 20.
The gas may be ejected from each of the molding surfaces 11 and 21 so that the raw glass body 41 can be supported by a known gas cushion.

The upper molding die 20 is attached to a well-known vertical drive means 25 provided in the molding apparatus 1, and is vertically moved at a predetermined timing.

The supply means 30 includes a flow control pipe 31 for dropping the raw material glass 40 and a pipe heating heater 32.
And a cutting means 33. In the flow control pipe 31,
A raw material glass 40 melted in the melting furnace is supplied from a glass melting furnace (not shown). Then, the pipe heating heater 32 optimizes the viscosity of the raw material glass 40 (viscosity l
ogη is about 0.5 to 1.5 poise. ), The temperature of the flow control pipe 31 is adjusted to a temperature of about 500 to 1500 ° C. according to the type of glass.

In the supply means 30 of this example, the cutting means 33 is composed of cutting blades 34 and 35. That is, by opening and closing the cutting blades 34 and 35 at a predetermined timing, the drop portion 40a of the raw material glass 40 flowing out from the flow rate control pipe 31 is separated by an appropriate amount and dropped.

Alternatively, in the present molding apparatus 1, as the cutting means 33, there are known well-known cutting means such as rapid heating cutting by laser, infrared radiation, high frequency heating, oxyhydrogen flame, cutting by rapid lowering of the molding die, cutting by natural dropping and the like. A cutting method can be applied.

The timing of the cutting by the cutting means 33, the timing of the vertical movement of the upper molding die 20 described above, etc. are the rotation cycle of the lower molding die 10 and the position (D) and (F) in FIG.
It is determined in consideration of the time required for each cooling process of the position. The cooling time at the position of FIG. 1D, that is, the time required from the dropping of the raw material glass 40 to the pressing of the upper molding die 20 is usually about 1 to 20 seconds.

Next, an example of molding the gob 50 using the molding apparatus 1 having the above-mentioned structure will be described. First, a switch (not shown) of the molding apparatus 1 is turned on to move the lower molding die 10 in a predetermined rotation cycle, and the pipe heating heater 32 heats the flow control pipe 31. Further, a glass melting furnace (not shown) is operated to supply the raw material glass 40 melted in the melting furnace into the flow control pipe 31.

When the raw material glass 40 is sufficiently supplied into the flow rate control pipe 31 and the operation of the molding apparatus 1 is in a steady state, the initial position of FIG. 1 (A) passes through the standby position of FIG. 1 (B). The drop portion 40a of the raw material glass 40 cut by the cutting means 33 is dropped onto the empty lower molding die 10 that has moved to the raw material dropping position in FIG. 1 (C).

The raw glass gob 41 (drop portion 40a) dropped and held on the lower molding die 10 is cooled to the softening temperature or lower in the cooling process of FIG. Become. As a result, the lower part of the raw glass gob 41 is solidified in conformity with the shape of the molding surface 11 of the lower molding die 10, and the lower surface 50a of the gob 50 is molded.

Thereafter, in FIG. 1 (E), the upper molding die 20 is pressed against the raw glass ingot 41. Up to this point, the upper portion of the raw material glass gob 41 has not yet been cooled to the softening temperature or lower and remains in the softened state.

The raw glass gob 41 is cooled by the pressed upper molding die 20 and solidifies in accordance with the shape of the molding surface 21 of the upper molding die 20. As a result, the shape of the upper surface 50b of the gob 50 is formed on the upper surface of the raw material glass gob 41. When the upper molding die 20 is pressed, the raw material glass gob 41 is pressed against the lower molding die 10 by the pressing force, but the raw material glass gob 4 has already been pressed.
Since the lower surface of 1 is solidified, there is no possibility that the lower surface will be deformed or scratched.

In this way, the lower surface 50a and the upper surface 50b
The gob 50 which has completed the molding of (1) is held on the lower molding die 10 and cooled to room temperature during the cooling process of FIG. 1 (F). Then, at the take-out position in FIG.
0 is taken out from the lower molding die 10 to obtain the gob 50 in a mirror state in which both the upper surface 50b and the lower surface 50a have a desired shape.

According to the above-described embodiment, the raw glass gob 41 is held and cooled on the lower mold 10 to solidify only the lower part thereof, and then the upper mold 20 is applied to the upper part in the softened state. In order to press and cool and solidify, the shape of the lower surface 50a of the gob 50 is first molded by the lower mold 10.
Subsequently, the upper molding die 20 molds the shape of the upper surface 50b of the gob 50.

Therefore, both the lower surface and the upper surface of the raw glass body 41 can be molded into a desired shape, so that the gob 50 having a shape similar to the final shape of the lens or the like can be obtained.

The gob molding apparatus 1 is not limited to the one in the above-mentioned embodiment, and the raw glass gob 41 is made by the lower molding die 10.
Only the lower part of the gob is cooled to a softening temperature or lower to be solidified, the lower surface 50a of the gob 50 is molded, and thereafter the upper part of the raw material glass gob 41 is cooled to a softening temperature or lower to be solidified. If the upper surface 50b of the gob 50 is molded, the number of lower molds 10 and its moving mechanism, cutting means 33, vertical drive means 25, gob 5
There is no limitation on the configuration such as the take-out means of 0.

[0036]

According to the method for molding a gob and the molding apparatus used for the same according to the present invention, after the raw material glass lump is held on the lower molding die and the lower part of the raw material lump is solidified,
Since the gob is formed by pressing the upper molding die against the upper portion in the softened state and solidifying the upper portion, the lower molding die first determines the lower surface shape of the gob. Next, the upper mold determines the top shape of the gob.At that time, the bottom part of the raw glass gob has already solidified, so the bottom shape of the gob is deformed or the bottom surface of the gob is scratched. There is no inconvenience such as sticking.

Therefore, both the lower surface and the upper surface of the raw glass body can be formed into a desired shape, so that a gob having a shape similar to the final shape of a lens or the like can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a schematic configuration of a molding apparatus used in a gob molding method according to the present invention and an example of a molding procedure thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molding apparatus 10 Lower mold 20 Upper mold 40 Raw material glass 41 Raw material glass gob 50 Gob 50a Lower surface 50b Upper surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Moriji Nozaki 1-15-30 Oyama, Sagamihara-shi, Kanagawa Incorporated company Ohara (72) Inventor Wataru Gen Sato 1-15-30, Oyama, Sagamihara-shi, Kanagawa Within the stock company OHARA

Claims (2)

[Claims] 1. When forming a gob from a raw material glass softened by heating, the softened raw material glass is supplied onto a lower molding die for molding the lower surface shape of the gob, and the lower molding die is formed. After the temperature of the lower surface of the raw material glass gob held on the lower molding die has become equal to or lower than the softening temperature of the raw material glass, before the temperature of the upper surface of the raw material glass gob is equal to or lower than the softening temperature. Then, the upper molding die for molding the upper surface shape of the gob is pressed against the upper surface of the raw material glass gob, to form the gob. 2. A molding apparatus used when forming a gob from a raw material glass softened by heating, wherein a raw material glass lump made of the softened raw material glass is held and the lower surface of the raw material glass lump is said. A lower mold for molding the lower surface of the gob, and an upper mold for pressing the upper surface of the raw glass mass to mold the upper surface into the upper shape of the gob, wherein the upper mold is the lower mold. After the temperature of the lower surface of the raw material glass gob held on the molding die is equal to or lower than the softening temperature of the raw material glass, before the temperature of the upper surface of the raw material glass gob is equal to or lower than the softening temperature, of the raw material glass gob A molding apparatus used in a method of molding a gob, which is adapted to be pressed against an upper surface.