JPH01215731A - Forming of optical element - Google Patents

Abstract

PURPOSE:To surely deliver a formed material held with a cutting member after press-forming and to easily take out a molded article of an optical element, by using a mold member moving in a cutting member and transferring only the above mold member in the pressing direction. CONSTITUTION:A pair of forming mold members 5, 6 are oppositely disposed interposing a glass fluid 2 therebetween and the glass fluid 2 is pressed with said members 5, 6 to form a formed part. A cutting member 7 attached to said members 5, 6 is operated to cut and separate the formed part from the other parts. In the separation of the formed part held with the cutting member 7 after cutting the outer circumference of the formed part, only the mold member 5 or 6 attached with said cutting member 7 is shifted in the pressing direction to release the holding of the formed part with the cutting member 7. The press-formed article can be easily taken out of the mold members 5, 6 by this process.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a mold for molding an optical element f- by press molding, and more specifically, to a mold for molding an optical element f- without undergoing processes such as grinding and polishing after press molding. The present invention relates to a method for molding a preform suitable for reheat pressing of an optical element having good surface precision and weight precision.

(Prior Art) In recent years, a glass material is housed in a mold having a predetermined surface accuracy and then press-molded.

Methods have been developed for molding high-precision optical elements that do not require post-processing such as grinding and polishing.

This press molding method generally includes a reheat press method and a direct press method.

In the reheat press method, the necessary amount of glass material that has been melted and solidified in advance is cut, the weight is reduced by a method such as sanding, and the glass pellets are then placed in a mold. This is a method of heating the molds simultaneously or separately to a pressing temperature, and then pressing and transferring the optical functional surface formed on the mold by press molding to mold an optical element.

On the other hand, in the direct press method, the required amount of the molten glass flowing out or extruded from the molten glass outflow orifice is cut by a cutting blade, and the cut is directly dropped into a mold or thrown into a chute, and then molded. This is a method of molding an optical element by pressing a mold.

In addition, in the above reheat press method, molten glass is put into a mold and press-formed into a final product, as in the above direct press method, without going through low productivity steps such as cutting and sanding. Preformed products with similar shapes (
There is a method of press-molding a preform obtained by placing the preform into a mold having an optical functional surface with a precision equal to or higher than that of the final product in shape and area.

(Problems to be Solved by the Invention) Optical elements obtained by these molding methods are required to have a certain area density and one-method accuracy in order to obtain good image forming quality, and for this reason, none of the above methods is required. Even in the h method, the amount of glass material supplied to press molding to obtain the final product must be sufficiently adjusted.

However, in the above-mentioned method of press-molding using small glass lumps, since the breakage of the glass lumps is adjusted by cutting and sanding, grains may remain on the surface of the molded product.
When heating a small glass lump before press forming, the mold release agent applied to prevent the glass and the heating tray from fusing together bites into the surface of the molded product during pressing, resulting in poor surface precision of the molded product. The problem is that it gets significantly worse.

In addition, in the method of press forming directly using molten glass,
When cutting with a cutting blade, there is a problem in that cutting marks called shear marks are generated on the molded product, and the area density of the molded product is deteriorated. In addition, in this press molding method, the weight of the molded product is adjusted by cutting the molten glass flow, so weight fluctuations occur in the molded product due to temperature changes in the molten glass flow, cutting timing, pulsation of the glass flow, etc. There is also the problem that dimensional accuracy cannot be obtained.

In addition, as a press molding method that particularly prevents the occurrence of shear marks, Japanese Patent Publication No. 41-9190 or Japanese Patent Application Laid-Open No. 6
There is one described in Publication No. 1-132523.

In the molding method described in Japanese Patent Publication No. 41-9190, press molding is performed by pressing a mold in a direction perpendicular to the direction of flow of molten glass to fill the mold cavity with molten glass. When the mold is pressed, a phenomenon occurs in which excess glass in the mold cavity flows out from between the mold and the anvil facing the mold. As the pressing operation of the mold progresses, this excess glass increases its outflow resistance and is cooled by the mold, increasing its viscosity, until it is completely cut off between the mold and the opposing anvil. The molded product is cooled without being completely wet, and a protruding portion is formed on the outer periphery of the molded product. Therefore, after press forming, it is necessary to break the protruding portion and finish the broken surface. Furthermore, due to variations in the size of the molten glass flow, the glass thickness between the above-mentioned molded product and the protruding portion changes, causing variations in the thickness of the molded product, making it difficult to adjust the weight with high precision. There is also the problem of not having one.

On the other hand, in the molding method described in JP-A No. 61-132523, the accuracy of the molded product depends on the size of the flowing glass body before punching it, and highly accurate dimensions and shapes can be produced. A rod or glass sheet is required.

In order to solve the above-mentioned problems, the present inventors have already proposed a method for manufacturing an optical element in which the molded product is free from surface defects such as shear marks and has excellent dimensional accuracy.

The present invention relates to a method for manufacturing the above-mentioned optical element, and an object of the present invention is to provide a method that allows easy removal of the molded product after press molding by discharging the molded product from the mold member.

(Means for Solving the Problems) In order to solve the above-mentioned conventional problems, the method for molding an optical element of the present invention includes arranging a pair of mold members facing each other so as to narrow the glass fluid. A method for molding an optical element, in which the glass fluid is pressed by the mold member to form a molded part, and then a cutting member provided on the mold member is operated to cut and separate the molded part and other parts. When separating the molded part held by the MLL cutting member after cutting the outer periphery of the molded part, the cutting member is removed by moving only the face-cutting member provided with the cutting member in the pressing direction. It is characterized by releasing from holding.

(Function) In the present invention, after forming a molded part by pressing a glass fluid with a pair of molding mold members having opposing stiffness so as to narrow the glass fluid, a cutting member provided on the mold member is actuated to form a molded part. The molded part and other parts are cut and separated. At this time, the surface and outer periphery of the molded part are held in contact with the mold member and the cutting member, and both the outer shape and the surface of the molded part shrink due to the temperature difference between the mold member and the cutting member. However,
Since the outer periphery of this molded part is held by the cutting member, it is prevented from falling due to shrinkage as described above. Then, in order to separate the molded part from the mold member, only the mold member provided with the cutting member is moved in the pressing direction, so that the molded part is released from the cutting member and detached from the mold member. This allows the part to be molded to be ejected from the mold member.

(Example) An example of the present invention will be described with reference to the drawings.

Figure 1 shows a press forming apparatus (
It is a schematic sectional view of No. 1 press molding m). In this embodiment, two sets of press forming apparatuses shown in FIG. 1 are connected and placed on the same rail! It's a set configuration. FIGS. 2 to 6 are schematic cross-sectional views of the two sets of press molding machines, and show the operating states of the machines in sequence.

In the following description, of the two sets of press molding apparatuses, the one on the left in FIG. 2 will be referred to as the No. 1 press molding machine, and the one on the right will be referred to as the No. 2 press molding machine.

Since both press molding machines have the same configuration,
First, the No. 1 press molding machine will be explained, and later the connection structure of each press molding machine and the means for moving the press molding machines to the rails will be explained. In addition, in the following, the part to be molded refers to the glass between the mold members that is pressed by the mold member, and the molded product refers to the glass whose surface is formed by the mold member and whose outer periphery is cut by a cutting member (ring cutter). ) refers to glass that has been cut to form an outer peripheral shape.

In FIG. 1, 1 is a nozzle through which molten glass flows out from a melting furnace (not shown), 2 is a glass fluid flowing out from this nozzle, and 3 is a cut mark produced at the tip of the glass fluid 2. 4 is provided below the nozzle l, and the glass fluid 2 is opened and closed by a drive device (not shown).
This is a shear for cutting.

The press molding apparatus shown in this embodiment is configured to allow the glass fluid 2 to flow from the nozzle 1.
The first mold member 5 and the second mold member 6 constituting a pair of molding molds are rearranged so as to face each other so as to narrow the glass fluid 2 from a substantially right angle direction.

The mold member 5.6 has molding surfaces 5a, 6a which are mirror-finished on opposing surfaces. When the mold member 5.6 operates to press the glass fluid 2, the molding surfaces 5a, 6a are transferred to the pressed surface of the molded part. Furthermore, by maintaining this pressed state for a certain period of time, the part to be molded is cooled by the mold member 5.6, and the surface shape of the part to be molded is formed. One part of the molded product is formed on each molding surface 5a, 6a.
This capacity can be set by the respective strokes of the cylinders 13, 16 shown below.

Heaters 8, 9 are provided inside each mold member 5.6. IO, +1 are conductive wires connected to each heater.

A ring cutter 7 is attached to the outer periphery of the second mold member 6.
A sliding member I'I is provided along the outer periphery of the second mold member 6. This ring cutter 7 is provided with a heater (not shown), and the temperature can be controlled. Such a ring cutter 7 operates after the mold member 5.6 presses and holds the glass fluid 2 to cut the outer periphery of the part to be formed, and also holds the outer periphery of the part to be formed by the ring cutter 7 for a certain period of time. As a result, the outer periphery of the part to be molded is cooled and hardened to fix its outer periphery shape.

The first mold member 5 is the first slider! 4, this first slider 14 is fixed to a base 19 that supports the device.
sliding on the first slide shaft 18 fixed to iiJ
is maintained effectively. Further, the first slider 14 is connected to a first cylinder 16 via a cylinder rod 16a, and the first slider 14 is moved in the sliding direction of the first slide shaft 18 by driving the first cylinder 16. Then, the first mold member 5 is pressed (in the direction of the second mold member 6) or the return operation is performed.

- On the other hand, the second mold member 6 is connected to the third cylinder 31 via the adapter 12 and the cylinder rod 31a connected thereto. Furthermore, this third cylinder 31 is connected to the second cylinder 13 by being connected to the cylinder rod 13a via the second slider 27. Furthermore, the second slider 27
sliding i1 on the second slide shaft 28 fixed to the
(The second cylinder 13
The second slider 27 moves in the sliding direction of the second slide shaft 28 and presses the second mold member 6 (in the direction of the first mold member 5) or performs a return operation. .

Further, the second slider 27 is slidably held by the second slide shaft 28 as described above, and also slidably holds the sleeve 26, and furthermore, the bushing rod 24 is held in the sleeve 26. The second slider 27, the sleeve 26, and the bushing rod 24 are configured to move in the same direction as the sliding direction of the second slide shaft 28. Sleeve flanges 26 are provided at both ends.
a and 26b are provided. Among these sleeve flanges, the sleeve flange 26b provided on the ring cutter 7 side is connected to the third slider 15 via the rod 25, and the third slider +5 is slidably connected to the first slide shaft 18. At the same time, a ring cutter 7 provided on the outer periphery of the second mold member 6 is firmly held.

Further, a return spring 30 is interposed between the sleeve flange 26a provided on the fourth cylinder 17 side among the sleeve flanges and the second slider 27.

A bushing rod flange 24a that can come into contact with the sleeve flange 26a is provided on the opposite side of the bushing rod 24 from the ring cutter 7, and this side is connected to the fourth cylinder 17 via a cylinder rod 17a. As the fourth cylinder 17 is driven, the bushing rod 24 slides within the sleeve 26 and moves.

With this configuration, when the second cylinder 13 is driven and operates the cylinder rod 13a in the pressing direction (in the direction of the first mold member 5), the second slider 27 moves the third cylinder 31. Possibly adapter 1
2 in the pressing direction, and the second slider 27 also operates the rod 25 via the flange 26b of the sleeve 26 to move the ring cutter 7 about the second mold member 6. Slide it in the direction of the first mold member 5. With this operation, the second mold member 6 and the ring cutter 7 move together, but the second and fourth cylinders 13, 17 are not actuated and the third cylinder 3 is moved.
If only 1 is activated.

The second mold part 6 moves in the direction of the first mold part 5 within the ring cutter 7 which is in a fixed state. As will be described later, this operation is useful as an operation for discharging the molded product 23 that has come into contact with the second mold member 6 and whose outer periphery is held by the ring cutter 7 after press molding.

Further, when the fourth cylinder 17 is driven and the cylinder rod 17a is moved in the direction of the first mold member 5, the bushing rod 24 is also driven, and at this time, the flange 24a of the bushing rod 24 comes into contact with the flange 26a of the sleeve 26. The third slider 15 is actuated via the sleeve 26 and the rod 25 connected thereto, and the ring cutter 7 is slid around the outer circumference of the second mold member 6 in the direction of the first mold member 5. It will be done. Further, when the fourth cylinder 17 is driven in the opposite direction to the second mold member 5, the restoring force of the return spring 30 between the flange 26a of the sleeve 26 and the second slider 27 causes the sleeve 2 to move in the opposite direction.
6 moves in the opposite direction to the first mold member 5, and along with this, the ring cutter 7 also moves back in the same direction.

Furthermore, the press molding apparatus configured as described above has an upper part provided below a base 19 that holds the entire apparatus.
It is supported by a moving cylinder 32 and can be moved vertically by driving the cylinder. However, the shear 4 shown in {circle around (2)} is attached to the apparatus, and moves upward along the E axis along with the upward F movement of the apparatus.

Further, the nozzle 1 is provided at a location different from the present device.

Therefore, when the device is moved up and down by driving the cylinder 32, the distance between the shear 4 and the nozzle l is relatively changed.

33 is a t on which the entire press molding apparatus as mentioned above is placed.
The mounting table is movable on rails 36 in the same direction as the mold member 5.6 by means of rollers 35 provided below.

Furthermore, a No. 2 press molding machine configured similarly to the No. 1 press molding machine is mounted on the same rail 36''. The No. 1 press molding machine and the No. 2 press molding machine are connected by a connecting member 34 as shown in FIG. A horizontally moving cylinder 37 is provided which is configured to move at a distance of 36". By adjusting the stroke of the cylinder 37, the No. 1 press molding machine and the No. 2 press molding machine
It can reciprocate on the rail 36 so that the gap is located below the nozzle 1. With such a configuration,
Not only can different types of molded products be manufactured using two sets of press molding devices 8 for the same nozzle 1, but also cooling or discharging after press molding can be performed using one press molding device as shown below. At this time, the mold member 5.6 is the nozzle 1
Since there is no need to position the die below the nozzle 1, the mold member of the other press molding device can be moved below the nozzle 1 and press forming can be performed using this mold member, allowing continuous molding of molded products. Become.

Note that each cylinder is connected to a pipe for supplying air or oil as a driving source for these cylinders. These correspond to the numbers with a suffix or c attached to each cylinder in Figure 1. These cylinders are connected to a controller (not shown), and can be operated according to the operation timing of each cylinder, which will be described later.

Next, the operation of the apparatus configured as described above will be explained based on FIGS. 2 to 6 and FIG. 7.

2 to 6 are sectional views of main parts showing the operating state of one apparatus in each process order. FIG. 7 is a timing chart showing the actuation timing of the actuating parts in one device, and the horizontal axis shows time T. These actuation timings can be controlled by a controller (not shown) connected to each actuating part.

In Fig. 7, "horizontal movement" indicates the movement of No. 1 and No. 2 machines on the rails (6) by the horizontal movement cylinder 37, and "in" means No. 1 or No. 2 press forming. One of the press molding machines moves below the nozzle 1 and is ready for press forming, and "retreat" means that one of the press forming machines in a position where press forming i=I is possible retreats from the side of the nozzle 1. This indicates a state in which press forming can be performed by the other press forming machine. Mold member 5. The "exit" or "pull" in the second mold member 6 indicates the pressing motion of each member and the return motion.The "exit" or "pull" in the ring cutter 7
indicates the cutting motion and return motion of the member. "Ejecting operation" indicates the ejecting operation of the molded product 23 due to the operation of the mold member 5, "ejection" indicates the action of the mold member 5 moving in the direction of the mold member 6 and ejecting the molded product 23, and "pull ” indicates the return movement of the mold member in the opposite direction. "Closed" in the cutting member 4 indicates the operation of the member to cut the glass fluid 2, and "open" indicates the return operation after cutting.

First, the operation of the No. 1 press molding machine will be explained.

Fig. 2 shows the state immediately before press forming by the No. 1 press forming machine.At aT+, the horizontal movement cylinder 37 provided in the No. 2 press forming machine operates, and at 1゛2, the press forming machine moves the nozzle. is moved below l. Also, at this point, the vertical cylinder 32 of the No. 1 press molding machine operates, and the entire press molding machine is raised at this point. At this time, the mold member 5.6, ring cutter 7, and shear 4 is in the open state and glass fluid 2
can flow down from the nozzle l between the mold members 5 and 6. Also, the tip of the ring cutter 7 is connected to the molding surface 6 of the mold member 6.
The ring cutter 7 is set so as to protrude slightly from the position a to prevent the molded product 23 from falling even after the ring cutter 7 returns to its original position.

FIG. 3 is a diagram showing the state during press molding by the No. 1 press molding machine. 6 The tip of the glass fluid 2.

That is, the pressing operation of the first mold member 5 and the second mold member 6 is started at T4, when the cut marks 3 have flowed downward from the opposing molding surfaces 5a and 6a, and this pressing Ff operation is finished at T. do. Thereafter, the mold member 5.6 keeps pressing the molded portion 21 of the glass fluid 2 for a predetermined period of time (1.6~
During this time, pressure transfer is performed on both surfaces of the molded portion 21 by the respective molding surfaces 5a and 6a.

The surface of the molded part 21 is gradually cooled and hardened.

In addition, the operation start timing of these mold members 5.6 may be the same for both, or the end time T of the pressing operation of the mold members 5.6 against the glass fluid 2 may be the same for both, or the aa+M of ±0.05 s at most. It is preferable to keep it within. If this error is large, only one side of the mold member 5.6 collides with the glass fluid 2, causing lateral wobbling of the glass fluid 2, which is not preferable.

Further, the operation start time of the shear 4 may be the same as the operation start time Ta of the mold member 5.6, but the end time Ts5 of cutting the glass fluid 2 by the shear 4 means that the mold member 5.6 is not in contact with the glass fluid. It must be at the same time as or at least after holding 2.

The shear 4 starts its return operation at the same time as it cuts off the glass fluid 2 at 1', and is returned to its original state at T.

The 1-'F operating cylinder 32 is driven at the same time as or slightly after the return operation completion time T6 of the shear 4.

At T, move the entire device downward.

FIG. 4 shows that the ring cutter 7 is operated to form the part to be formed 21.
It is a figure which shows the state where the outer periphery was cut.

The operation of the ring cutter 7 is desirably started at the same time or after the mold member 5.6 holds the glass fluid 2, and at least when the shear 4 finishes cutting the glass fluid 2. . By doing so, when the cutting operation of the ring cutter 7 is completed, the glass fluid 2 is already separated by the shear 4, and the cut piece 22 cut by the ring cutter 7 is easily attached to the first mold member. Move outside of 5.

After the cutting path r (T6) of this ring cutter 7,
The ring cutter 7 cools the molded part 21 from the outer periphery while holding the outer periphery of the molded part 21 for a certain period of time, and the molded part 21 gradually increases in viscosity and hardens from the vicinity of the outer periphery.

FIG. 5 is a diagram showing a state in which the No. 2 press molding machine has been moved below the nozzle 1. As described above, at the end of the cutting operation of the ring cutter 7 at T6, the lowering operation of the entire No. i press molding machine is started. Then, T? has finished this descending motion? At T8, the water motion of the No. 1 press molding machine is started, and at T8, the movement of the No. 1 press molding machine is finished.

By moving the No. 1 press molding machine between T and T1, the No. 2 press molding machine is moved below the nozzle seal.

-, in the No. 1 press molding machine, the No. 22 press molding machine moves below the nozzle l,
Mold member 5. The retracting operation of the second mold member 6 and ring cutter 7 is started. At T when this operation is completed, the discharge of the molded product is started. This ejecting operation is performed by pushing out the second mold member 6 in a direction opposite to the direction in which the ring cutter 7 is drawn in, as shown in FIG. As mentioned above, the tip of the ring cutter 7 slightly protrudes from the molding surface 6a of the mold member 6, and the molded product 23
Since the outer periphery is held by the ring cutter 7, the molded product 23 does not fall even after the ring cutter 7 returns, but the molded product 23 is pushed out by the ring cutter 7 due to the extrusion operation of the mold member 6 shown in L. is released from the holding state and detached from the mold member 6.

FIG. 6 is a diagram showing the state immediately before press molding by the No. 2 press molding machine. When the No. 2 press molding machine is moved to the corner of the nozzle 1, the mold members 5, 6, ring force/tutter 7, and shear 4 of the No. 2 press molding machine are moved below the nozzle l. It is in the same open state as when it was moved.

Regarding the subsequent operation of the No. 2 press molding machine, while the operation of the No. 1 press molding machine mentioned in 1 continues, the horizontal operation of the No. 2 press molding machine starts at T7] and ends at T8, and the press When the molding machine is moved below the nozzle L, the press molding machine starts to move upward, so that the No. 2 press molding machine has a deviation of It operates in the same way as the No. 1 press molding machine.Hereinafter,
The No. 1 and No. 2 press molding machines can perform press molding on the glass fluid 2 supplied from the nozzle l to the intersection U with a deviation of TI to T7.

As explained hereafter, in this embodiment, 1 nozzle 1 is used with 1 press molding machine, for example, 2 glass fluids.
When the press molding for the molded part 21 is completed, the No. 1 press molding machine 5 is lowered from the nozzle 1 and then retracted, during which time the outer periphery of the molded part 21 is cut by the cutter ring 7 and the molded product 23 is discharged. On the other hand, the No. 2 press molding machine performs press molding on the glass fluid 2 flowing down from the nozzle 1.
Two molding machines can be used alternately. However,
When press molding is performed using one press molding machine for one nozzle as in the past, after press molding, the next press molding should be performed until the molded product that has been press molded is discharged from the mold member. However, according to the present embodiment described above, such wasted time can be eliminated and molded products can be manufactured at high speed.

In addition, according to such a press molding method, the mold members 5,
Since the press molding in step 6 is performed on the tip of the glass fluid 2, that is, the portion excluding the cutting trace 3, surface defects such as shear marks do not occur in the obtained molded product 23.

Further, the entire device is moved downward at the same time as the glass fluid 2 is cut by the shear 4, and a gap is created between the nozzle l and the shear 4, so that the flowing glass fluid 2 does not come into contact with the shear 4. Therefore, the glass fluid 2 with a good thickness is supplied for the next press molding. Therefore, sufficient glass capacity is ensured for the next press molding, and non-uniformity in the shrinkage layer due to cooling, which occurs with tapered glass fluids, is less likely to occur. Further, if the glass fluid 2 flowing down comes into contact with the shear 4 and is cooled unevenly and partially solidifies, it becomes impossible to mold the glass fluid 2, but in this embodiment, such a problem does not occur.

Alternatively, the cavity formed by the mold 5.6 can be set by the stroke of each cylinder 13.16. That is, the distance between the molding surfaces of the molding die 5.6 at the pressing end time 5 is determined by the set stroke of the cylinder 13.16. Since the wall thickness of the molded product 23 is determined by this molding surface spacing, the stroke of the cylinder 13.16 is determined by the molded product 23 to be manufactured.
By setting the thickness according to the wall thickness, a molded product having a predetermined wall thickness can always be obtained. Further, the surface shape and properties of the molded article 23 are determined by the respective molding surfaces 5a, 6a of each molded member 5.6. Furthermore, the outer circumferential shape of the molded article 23 is determined by the inner circumferential shape of the ring cutter 7, and the outer circumference of the molded article is formed simultaneously with the cutting operation of the ring cutter 7.

Next, a specific example using the press molding method as described above will be described with reference to FIGS. 1 to 8.

Optical glass SF8 (usually used for camera lenses, etc.)
Using Tg = 443°C, specific gravity 4.22), the No. 1 press molding machine had 20 outer diameters, 2.7 mm center wall thickness, 1.29 mm edge thickness, curvature R+ = 20 mm, and R* = 40 m.
m, glass capacity 0.636 cc% weight Q 2.611 g convex meniscus shaped preform for reheat press, No. 2 press molding machine, outer diameter 191, center wall thickness 3.
$++ue, edge thickness -, 79++u11. Curvature R1=R
-=60mm, glass 8 heat 0.723 cc, weight 3.
A preform for reheat press weighing 0.5 g and having convex shapes on both sides was molded. Since both glass molded products to be manufactured require approximately the same glass capacity, even a molding method in which two sets of press molding machines are used alternately for one nozzle as in this example is suitable. Well applied.

In both the No. 1 and No. 2 press molding machines, the mold member 5
．． 6 is a molded part 5a made of 5US420J,
6a is polished to an optical mirror surface.

Further, these mold members 5 and 6 are heated with a heater 8.9 so that the mold temperature becomes 400°C (43°C lower than Tg of Sr8=443°C). Furthermore, in the one-press molding machine □, the first cylinder 16. In the first press molding machine, the maximum approach width of the stroke of the second cylinder 13 during the pressing operation of each mold member 5.6 is 2.7 mm,
In the second press molding machine, the thickness was adjusted to 3.3 to obtain the desired wall thickness. Operation of cylinder 13.16 [1-
The forces were 150 kg and 300 kg, respectively, and the operating speeds were 200 mm/s for both. Similarly, in both press molding machines, the ring cutter 7 is made of SK3, the operating pressure of the fourth cylinder 17 that moves the ring cutter 7 is look kg, and the operating speed is 200 mm/
It is s.

The No. 1 and No. 2 press molding devices configured in this way adjust the viscosity of the molten glass fluid 2 flowing out from the nozzle 1 to approximately In" poise (815°±5°C), and perform the above-mentioned operation. Press molding was performed using mold member 5.6.

Then, the ring cutter 7 is operated to form the outer peripheral shape of the part to be formed 21, and the first and second cylinders 16.1
While applying pressure to mold member 5.
After holding the state shown in FIG. 5 for about 10 seconds until the temperature becomes approximately equal to the temperature of No. 6 (400° C.), the first mold member 5 is molded into the molded product 23.
When the molded product 23 is separated from the ring cutter 7, the molded product 23 contracts as the temperature decreases, but it remains held by the ring cutter 7 and does not fall off by itself. Next, the third cylinder 31 was operated to extrude the second mold member 6 in the direction of the N-th mold member 5, and the molded product 23 was discharged. Molded article 2 thus obtained
3 has an outer diameter accuracy of ±0.0 for the desired molded product.
05 mm, center thickness ±0, OImm, weight 0.0
Variations within 2g (±0.7%), no shear marks or other harmful surface defects, and sink marks within a maximum of 10gm for the shape of each mold member 5.6 Therefore, it could be used not only as a preform for reheat press, but also as an optical lens that does not require much precision.

FIG. 8 is a graph showing temporal changes in the temperatures of the first mold member 5, the second mold member 6, and the glass material to be molded in this example. Incidentally, in this explanation, time 1' in FIG. 7 is used.

Initially, the first and second mold members 5.6 are formed at the glass transition point Tg of the glass material ("T' g of Sr.°s" = 443
The temperature was adjusted to 400°C, which is 43°C lower than the average temperature. or.

The viscosity of the glass fluid 2 flowing from the nozzle 1 is approximately 104.
The temperature was adjusted to 6 poise (815°±5°C).

During the molding period (approximately 10 seconds) from the end time 1' of the pressing operation of the mold member 5.6 to the start time r8 of the return operation, the glass of the molded part 2I suddenly changes due to the temperature difference of the mold member 5.6. When cooled, the viscosity ranges from 104.6 Boaz to lO''
・It will be 1 Boaz or more. In this embodiment, the mold member 5
．． 6 is heated by a heater 8.9 so as to be maintained at 400 DEG C. until the end of pressing, and at this time the glass temperature of the molded product 23 becomes approximately the same temperature as this mold member 5.6.

(Effects of the Invention) As explained below, according to the method for molding an optical element of the present invention, only the mold member that moves within the cutting member is actuated in the pressing direction, thereby reducing the The molded part held by the cutting member can be accurately discharged, and the molded product can be easily taken out.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a press molding apparatus showing an embodiment of the present invention. 2 to 6 are sectional views of essential parts of the apparatus shown in FIG. 1, and show the operating state of the apparatus in the order of steps. FIG. 7 is a small diagram showing a timing chart of each operating section of the press molding apparatus shown in FIG. 1. FIG. 8 is a graph showing temporal changes in temperature of the mold member and the glass which is the material to be molded in the I-body embodiment of the present invention. 1... Nozzle 2... Glass fluid 3... Cutting mark 4... Shear 5... First mold member 6... Second mold member 7... Cutting member 7 a =- Tip portion 21 of cutting member... Molded portion 22... Cut piece 23... Molded product + 3... Second cylinder + 6... First cylinder + 7... Fourth cylinder Cylinder 3 +-...Third cylinder agent Patent attorney Jo Yamashita i). Figure 2 Figure 3-Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] A pair of molding mold members are arranged opposite each other so as to narrow the glass fluid, and after pressing the glass fluid with the mold members to form a molded part, a cutting member provided on the mold member is operated to remove the molded part. In the method for molding an optical element in which a molded part and other parts are separated by cutting, the mold provided with the cutting member is used when separating the molded part held by the cutting member after cutting the outer periphery of the molded part. A method for molding an optical element, characterized in that the holding of the cutting member is released by moving only the member in the pressing direction.