JPH0813687B2 - Glass lens forming apparatus and manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a glass lens molding device for forming a glass lens used in optical equipment by a precision glass molding method,
And a manufacturing method thereof.

Conventional technology In recent years, one-shot molding of optical lenses without a polishing process
Many attempts have been made to form it, and each company is currently in the mass production stage. The most efficient method is to cast a glass material from a molten state into a mold and perform pressure molding, but it is difficult to control the shrinkage of the glass during cooling, and it is not suitable for precise lens molding.

Therefore, it is a general method to pre-process a glass material into a certain shape, supply it between molds, and heat and press-mold it. (For example, Japanese Patent Laid-Open No. 58-8413, 60-2008
No. 33 public information). The conventional molding method described above will be described below with reference to the drawings.

FIG. 4 is a sectional view showing a state in which a lens is formed by molding a disk-shaped glass material by one of the conventional methods.
44 is a molded lens, 41 and 42 are a pair of molding dies, and 43 is a barrel mold. Reference numeral 45 is a heater, and 46 and 47 are parts of a molding apparatus having a pressure mechanism.

The glass material is supplied into the molding die, and the heater and the glass material are heated to a temperature near the softening point of the glass by the heater 45, and pressure-deformed by the die 41 and 42. After the deformation is completed, the molded lens is gradually cooled, and when the temperature reaches the temperature at which the lens can be taken out, the mold is opened and the lens is taken out.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the method as described above, the temperature at which the glass lens used for optics can be molded is 500 to 700 ° C., so that the mold and the glass material are heated, deformed under pressure, and cooled respectively. It takes a certain amount of time, and it takes a long time from the introduction of the glass material to the molding of the lens. As a result, there is a problem that the efficiency of the molding apparatus does not increase and the cost required for molding is high.

Further, in order to shorten the molding cycle, if the glass is deformed and the mold is opened before being cooled sufficiently, or if the mold is forcedly cooled, there is a problem that the accuracy required for the lens cannot be obtained.

Therefore, the inventors of the present invention have disclosed in Japanese Patent Laid-Open No. 62-2
It was disclosed in the No. 92629 public information. However, this molding apparatus is disadvantageous in that the number of mold surfaces can be reduced to only half of the number of stages arranged in the apparatus, and is not suitable for mass production. In addition, due to the improvement of the mold structure, the importance of pressurizing while cooling after deformation has been alleviated.

In view of the above problems, the present invention provides a glass lens molding apparatus that has high shape accuracy and surface accuracy, and can press-mold a low-cost lens in a short time, and a method for manufacturing a glass lens. To aim.

Means for Solving the Problems In order to solve the above problems, the glass lens molding apparatus of the present invention is a heating zone including a plurality of heating blocks for heating a molding block including a pair of molding dies and a barrel die. A pressure zone consisting of a pressure block for pressurizing the mold of the former molding block, a cooling zone consisting of a plurality of cooling blocks for cooling the entire molding block, a chamber containing each of the three zones, and Conveying means for sequentially conveying the molding block to each zone of heating, pressurization, and cooling, an inlet and an outlet having an opening / closing shutter for loading and unloading the molding block into the chamber, and a non-oxidizing agent. A gas supply port for feeding gas into the chamber.

Further, the method for producing a glass lens of the present invention comprises a plurality of heating steps of heating a molding block composed of a molding die having a pair of upper and lower molds and a barrel for sandwiching a glass material from the upper and lower surfaces thereof, and the above-mentioned molding. It comprises a deforming step of deforming the glass material through a mold, and a plurality of cooling steps of cooling the molding block from its upper and lower surfaces after the deformation is completed. Each of the heating, deforming and cooling steps is performed as described above. It is carried out in order.

Action The present invention has the effect that by arranging a plurality of temperature control means and pressure control means in the same chamber, a molding block having a predetermined heat capacity can be heated, deformed and cooled with the highest thermal efficiency.

Examples Hereinafter, one example of the glass lens molding apparatus of the present invention will be described in detail with reference to the drawings.

First, the configuration of FIG. 1 will be described. On the pedestal 2 provided in the chamber 1, the lower heating blocks 3, 4, 5, the lower pressurizing block 6, and the lower cooling blocks 7, 8, 9 are arranged laterally (in the drawing). They are arranged in a line (left-right direction).

And, above it, the upper heating blocks 10, 11, 12 and the pressure block 13, as opposed to the lower blocks.
Cooling blocks 14, 15, 16 are arranged.

The space between each block in the vertical direction is the upper die 17,
The height of the molding block A formed by the lower mold 18, the body mold 19, and the glass material 20 is set to be larger by a predetermined amount.

Heating, pressurizing, cooling upper and lower blocks 10, 11, 12, 1
3, 14, 15, and 16 are respectively mounted via a press cylinder 21 so as to be vertically movable (Z direction in the drawing) by a required stroke.

A heater 22 capable of raising a desired temperature is embedded in each of the lower heating blocks 3, 4, 5, the lower pressurizing block 6, the lower cooling blocks 7, 8 and each of the upper blocks opposed thereto.

The lower cooling block 9 and the upper cooling block 16 have cooling water intake ports 2 for efficiently cooling the entire molding block.
3 and outlet 24 are external temperature controllers (not shown)
Connected with.

A thermocouple (not shown) is embedded in each of the upper and lower blocks 10 to 16 and 3 to 9 to detect a predetermined temperature.

To control the atmosphere in the chamber 1, gas supply ports 25 such as an inert gas as a non-oxidizing gas are connected to the upper two places of the chamber.

Further, the respective lower blocks are installed on the same surface so that the forming blocks can be transferred, and the lower heating block 3 and the outside of the chamber are connected to the preparation table 27 via the forming block inlet 26. It is set up.

In the inlet 26 provided on the right side of the chamber 1,
A shutter 28 that can be freely opened and closed is provided, and an outlet 29 is provided on the other left side surface, and a shutter 30 and a mold cradle 31 are provided.
And are lined up.

Forming block A into lower heating block 3 in chamber 1
Cylinder 32 pushes push bar 33-
It can be done by pushing in a predetermined amount in the X direction.

Next, the transfer means for the molding block A will be described with reference to FIG. FIG. 2 is a plan view of FIG. The transfer of the molding block is performed by the transfer device 34. That is, the rods 37 are moved by the same pitch as the arrangement pitch between the blocks via the drive cylinders 35 and 36 arranged on the back surface of the chamber 1. The drive cylinders 35, 36 can be freely moved back and forth and left and right in an X direction with a predetermined pitch and a Y direction with a predetermined amount.

Next, a process of molding a lens using the above-described molding device will be described with reference to FIGS. 1 to 3. The glass material 20 is put into the upper mold 17, the lower mold 18, and the body mold 19 and placed on the preparation stand 27 as a molding block A. The molding equipment is
After the molding cylinder A is moved to the position of the molding block B in the forward direction by the ejection cylinder 38, the ejection cylinder returns to the original position.

Next, the shutter 30 of the outlet 29 is opened, and at the same time, the drive cylinder 35 is moved by a predetermined amount in the −Y direction by using the above-mentioned transfer means, so that the rod 37 is projected in the forward direction, and subsequently, the drive cylinder 36. In the -X direction.

By this operation, the molding block on each lower block is sequentially slid and transferred to the next block. For example, the molding block A on the lower cooling block 9 has a take-out port.
After passing through 29, it is transferred onto the die cradle 31. Then, the rod 37 is returned to its original position in the order of + Y direction and + X direction by the drive cylinders 35 and 36, and at the same time, the shutter 30 is closed.

Then, the shutter 28 of the charging port 26 is opened, and the molding block A on the preparation stand 27 is moved by the cylinder 32 and the push rod 33.
It is moved in the X direction and placed on the lower heating block 3. At the same time as the cylinder 32 returns, the shutter 28 closes.

This operation is sequentially repeated at regular intervals to continuously perform lens molding.

When the shutter 30 is opened, N2 gas having a constant pressure is supplied from the gas supply port 25 to increase the gas pressure in the chamber 1, and the gas flows out from the outlet 29 to the outside of the chamber. Has no adverse effect. That is, shutters provided on both sides of the chamber 1
One of the opening and closing of the shutter 28 and the shutter 30 is closed when the molding block is loaded and unloaded. The reason is that both shutters are opened at the same time and the molding block is put in at the same time during transfer. This is because the disturbance of the atmosphere in the chamber 1 due to the above is eliminated and the molding is performed in a stable atmosphere.

The molding block A put into the chamber 1 is placed on the lower heating block 3 and simultaneously descends from above until the upper heating block 10 contacts the upper die 17 of the molding block A. That is, efficient heat transfer heating is performed from the upper and lower surfaces of the forming block.

Here, in the heating zone, that is, in the zone where the upper heating block and the lower heating block are arranged, the first reason for making the upper and lower heating blocks a plurality of stages is that the upper and lower molds and the barrel mold having different thermal conductivities, and the glass material Is to efficiently perform uniform heating without a temperature difference until the temperature reaches a predetermined temperature (deformation temperature).

The second reason is to set the optimum heating temperature condition in order to minimize the scattered substances from the glass that determine the quality of the appearance of the molded lens.

Of course, the heat capacity and electric power of the upper heating block and the lower heating block, and the thermal conductivity and heat capacity of the molding block are calculated.

In the heated forming block A, the transfer rod 37 shown in FIG. 2 moves in the -Y direction (toward the front side), and the forming block moves along the guide rails 39 which enable linear transfer on the lower blocks. And moves a predetermined amount P in the -X direction (left side in the drawing), and is transferred and placed on the next lower heating block.
After that, the rod 37 moves in the + Y direction (rear side), separates from the forming block, and returns a predetermined amount P in the rear + X direction (right side) to complete the transfer.

The molding block A stands by on the lower heating blocks 3, 4 and 5 for a certain period of time respectively, and at the same time, the upper heating blocks 10 and 11,
The heating of the molding block A is completed by heating from the upper and lower surfaces within a waiting time by 12 and sequentially transferring at regular intervals.

In this embodiment, when the outer diameter of the molded lens is about 20 mm, the three-stage heating method is the most efficient and there is no scattered matter from the glass material at the time of heating, and the lens appearance is good.

Next, the molding block A is transferred onto the lower pressing block 6 by the means described above. The temperature settings of the lower pressure block 6 and the upper pressure block 13 are set so that the glass material 20 can be deformed, and immediately after transfer, via the pressure block 13, the press cylinder 21 moves in the -Z direction. The glass material 20 is deformed under pressure. After a certain time has passed after the deformation, the press cylinder 21 is lifted in the + Z direction to complete the deformation.

Next, the molding block A is transferred onto the lower cooling block 7 and brought into contact with the upper cooling block 14 to cool it. After that, the molding block A is transferred onto the lower cooling block 8,
Further, the lens is cooled.

In particular, the shape accuracy of the molded lens is determined by how well the glass transition point and its vicinity are cooled in the above two-stage cooling process. In this embodiment, the second cooling step,
That is, the temperature setting of the lower cooling block 8 and the upper cooling block 15 is set below the glass transition point, the cooling speed of the molding block is fast immediately after transfer, gradually decreases with the passage of time, and waits on the lower block. The glass transition point is passed within a certain time, and the temperature is further cooled to the same temperature as the set temperature of the cooling block. Further, the molding block is cooled to a temperature at which it can be taken out by the lower cooling block 9 and the upper cooling block 16, and after being subjected to a three-stage cooling process, it is transferred to the die receiving table 31.

After that, the molding block is completed by passing through a total of seven upper and lower blocks in each of the three zones of heating, deformation and cooling in this manner at regular intervals.

In this embodiment, the temperature setting of each of the upper and lower blocks is maintained at an optimum constant temperature (the set temperature is different, but the steady state), and the molding blocks sequentially transferred and having different temperatures and the upper and lower blocks are sequentially set. The time difference is set so that the temperature difference between them is eliminated within a predetermined time (machine tact).

The molding apparatus of the present embodiment, means for further shortening the molding tact by the molding method can be solved by increasing the number of steps of heating, pressurization, and cooling as much as possible, but on the other hand, there is a drawback that the number of mold surfaces increases. Have.

Therefore, the present apparatus and the present method avoid the above-mentioned inconvenience, and determine the optimum number of steps from the size of the objective molded lens, the required accuracy of the lens, the thermal characteristics of the glass material, and the like.

With the above-mentioned configuration, it was possible to reduce the molding time from about 90 seconds or more in the conventional example to 60 seconds or less.

FIG. 3 shows the structure of each of the upper blocks for heating, pressurizing and cooling in more detail. A water cooling pipe 55 is provided on the flange portion 54 of the press cylinder 21 which is movable up and down.

The inlet / outlet of the water cooling pipe 55 is connected to the outside of the chamber, and the cooling water flowing in the water cooling pipe is adjusted to a predetermined temperature.

Further, a mold release pin 51 is embedded in the center of each block on the upper side of heating, pressurizing and cooling. This release pin 51
The purpose of this is to prevent each block and the upper die 17 of the molding block from being lifted upward by adsorption or contact and hindering the molding operation. The release pin 51 is projected about 1 mm from the lower end surface of each block by the compression spring 52.

Adsorption or close contact between the upper mold and each block generated during molding is forcibly released by the spring pressure of the compression spring 52. The spring pressure is set to 200 grm-f, which does not affect the performance of the molded lens.

The flange portion 54 and each block 53 are fixed to each other by a fixing screw 58 using a mounting plate 57 via a heat insulating plate 56. Further, the mounting plate 57 and the flange portion 54 are fixed by mounting screws 59.

In this embodiment, the release means is constituted by spring pressure, but the upper die contact surface of each upper block is grooved to reduce the contact area to prevent adsorption and adhesion with the upper die. A method of doing it is also possible.

Further, in this embodiment, the constant temperature condition is set according to each upper block and each lower block. The reason for this is that, especially when the molding block is cooled at a uniform cooling rate from above and below in the cooling step, lens molding without warpage can usually be realized with a lens whose top and bottom surfaces are substantially uniform.

However, in a lens (for example, meniscus, plano-convex) or the like whose top and bottom surfaces are greatly different in shape, warpage is conspicuously conspicuous on the contrary at the above uniform cooling rate.

In such a case, the temperature can be controlled so that the warp can be controlled by increasing the temperature on the side opposite to the direction in which warpage occurs and providing a time difference when the upper and lower lens surfaces are solidified.

The method for providing the time difference is to directly change the temperature settings of the upper and lower blocks to provide a time difference for cooling both surfaces of the lens by a difference in heat conduction, and to provide the time difference by radiative cooling with the upper cooling block not in contact with the molding block. There is. In the former case, the contact surface of the mold or the cooling block causes a slight variation in heat conduction due to oxidation and gas adhesion.

In view of this, in the present embodiment, by forming the cooling block and the molding block out of contact with each other in the second cooling step of passing the glass transition point, lens molding with a shape accuracy of the molded lens within ± 1 μ could be realized.

The lens shape molded in this example has an outer diameter of 20 mm,
The lens had a biconvex shape with a thickness of 3 mm, the glass type was barium borosilicate, and the temperature was set at 570 ° C at the set temperature of the upper and lower pressure blocks. Further, in this embodiment, the heating, pressurizing, and cooling zones are composed of blocks arranged vertically, but other zones may be used as long as there is no hindrance to the performance of the molded lens and molding.

EFFECTS OF THE INVENTION According to the apparatus of the present invention, it is possible to heat, pressurize, and cool a glass material with good heat efficiency, and to perform lens molding in a short time. Moreover, a simple apparatus is mass-produced and economical. To provide a glass lens molding device with high utility value.

Further, according to the method of the present invention, it is possible to perform lens molding with stable shape accuracy, it is possible to supply the most desirable lens in terms of optical design, and it is possible to contribute to the stability of optical equipment.

Furthermore, the lens obtained by the present invention is excellent in appearance, shape accuracy, and optical characteristics, and further, the lens cost can be reduced, which is of great value.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of a glass lens molding apparatus of the present invention, FIG. 2 is a plan view of the apparatus of the same embodiment, FIG. 3 is a sectional view of a releasing means in the embodiment, and FIG. It is a principal part sectional drawing of a prior art example. 1 ... Chamber, 2 ... Stand, 3, 4, 5 ... Lower heating block, 6 ... Lower pressure block, 7, 8, 9 ... Lower cooling block, 10, 11, 12 ... Upper heating block , 13 …… Upper pressure block 14, 15, 16 …… Upper cooling block, 17 …… Upper mold, 18 …… Lower mold, 19 …… Body mold, 20 …… Glass material, 21…
… Press cylinder, 22 …… Heater, 28, 29 …… Shutter 35, 36 …… Drive cylinder, 37 …… Rod 32, 38 …… Cylinder, 39 …… Guide rail, 51 …… Release pin, 52…
… A compression spring.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadao Shioyama 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-63-139019 (JP, A)

Claims (10)

[Claims] 1. A heating zone composed of a plurality of heating blocks for heating the entire molding block in which a glass material is put inside a pair of molding dies and a body mold, and a molding die for the molding blocks. A pressure zone composed of a pressure block capable of deforming the glass material, a cooling zone composed of a plurality of cooling blocks for cooling the entire deformed molding block, and a chamber containing the three zones, Heating means, heating means for sequentially carrying the molding block to each zone of cooling, and for carrying the molding block into and out of the chamber,
A glass lens molding apparatus comprising: an inlet having an opening / closing shutter, an outlet, and a gas supply port for feeding a non-oxidizing gas into the chamber. 2. The heating, pressurizing, and cooling zones are composed of an upper block and a lower block so as to sandwich a pair of molding dies from above and below, and each has a temperature control means based on the thermal characteristics of the glass material and a pressure. The glass lens molding apparatus according to claim 1, further comprising a control unit. 3. The glass lens molding apparatus according to claim 1, wherein the upper block of each zone is provided with a mold releasing means for releasing the upper mold of the mold that contacts the upper block. 4. The mold releasing means comprises a mold releasing pin embedded in an upper block and a pressing means, and the pressing means presses the upper mold of the mold toward the lower block via the mold releasing pin. The glass lens molding device according to claim 3, further comprising: 5. A shutter according to claim 1, wherein one of the shutters at the inlet and the outlet is closed when the molding block is carried in and out from the inlet and the outlet. Glass lens molding equipment. 6. The temperature and pressure control means for each block constituting the heating, pressurizing and cooling zones comprises seven stages, as set forth in any one of claims (1), (2) and (3). The glass lens molding device described in 1. 7. A plurality of heating steps of heating a molding block composed of a molding die having a pair of upper and lower molds for sandwiching a glass material and a barrel die from above and below, and the glass through the molding die. It is equipped with a deforming step of deforming the material and a plurality of cooling steps of cooling the molding block from its upper and lower surfaces after the deformation is completed. The heating, deforming and cooling steps are sequentially carried out to mold the glass lens. A method of manufacturing a glass lens, comprising: 8. In the cooling step, based on the lens shape,
The method for producing a glass lens according to claim (7), wherein a temperature difference is set between the cooling temperatures of the upper mold and the lower mold of the molding die. 9. The manufacturing method of a glass lens according to claim 8, wherein the upper block is not in contact with the molding block in at least one of a plurality of cooling steps as means for providing a temperature difference. Method. 10. The method according to claim 7, wherein the temperature of the second cooling step among the plurality of cooling steps is set to a glass transition point or lower. Of manufacturing glass lens of.