JP2012046370A - Method of forming optical lens - Google Patents

Abstract

The present invention relates to a method for molding an optical lens in which an optical material is heated and pressure-molded, and an object thereof is to improve the productivity of the optical lens.
In order to achieve this object, a molding method for forming an optical lens by heating and pressing an optical material 1, a heating step 7 for heating the optical material 1, and the optical material 1 with a molding die. A pressure process 8 for pressure deformation and a cooling process 9 for cooling the pressure-deformed optical material are included, and the temperature of the inner part of the optical material 1 is lower than the temperature of the outer part at the start of pressurization in the pressure process 8 In addition to having a temperature distribution, at least as a pressurizing method at the start of pressurization, the pressurizing speed of the molding die 4 is controlled to cause the pressurizing deformation.
[Selection] Figure 2

Description

  The present invention relates to an optical lens molding method for molding an optical lens by heating and pressing an optical material.

  As a molding method of this type of optical lens, an optical material corresponding to a desired volume of the optical lens is arranged between a pair of molding dies, and the temperature of the heater block attached to the molding dies is controlled to control the optical material. It is known to heat up to a moldable temperature above the glass transition temperature, sufficiently heat the entire optical material to a moldable temperature, perform pressure molding at a predetermined molding pressure, and then cool and take it out. Yes.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

JP 2008-50184 A

  However, in such heat and pressure molding, since the optical material is heated from the outer part through the molding die, it is necessary to increase the temperature sufficiently so that the temperature can be molded up to the inner part of the optical material. Even if the time is increased and the temperature rise rate is increased by increasing the set temperature of the heater block, the temperature distribution occurs between the inner part and the outer part of the optical material due to the thermal conductivity of the optical material. There was a problem that it took a lot of time to wait for it to become smaller.

  Therefore, the present invention aims to solve such problems and to shorten the temperature raising time of the optical material and increase the productivity of the optical lens.

  In order to achieve this object, the present invention provides a molding method for molding an optical lens by heating and pressurizing an optical material, a heating process in which the optical material is placed between a pair of molding dies and heated, A pressure process for pressurizing and deforming the optical material with a molding die, and a cooling process for cooling the pressure-deformed optical material. In addition to having a lower temperature distribution, as a pressurization method at least at the start of pressurization, the pressurization speed of the molding die is controlled to cause pressurization and deformation.

  Thus, the present invention can increase the productivity of the optical lens.

Sectional drawing which shows the shaping | molding apparatus of the optical lens which concerns on this invention Schematic diagram showing a method of molding an optical lens using the molding apparatus The figure which shows the relationship between the mold temperature and the distance between molds in the molding method

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a molding apparatus 2 for molding an optical lens by heating and pressing an optical material 1 such as optical glass or optical resin. The basic structure of the molding apparatus 2 is a cylindrical body having a through hole. The molding die 4a is fixed to one end of the die 3, and the molding die 4b is slidably inserted along the inner peripheral surface of the through hole from the other end side of the barrel die 3. The optical material 1 is heated and pressed in a molding space surrounded by the molding dies 4a and 4b and the body die 3. In addition, the heater block 5 which controls heating / cooling temperature is each attached to the edge part of each molding die 4a, 4b.

  Next, a method for molding an optical lens using the molding apparatus 2 will be described. As shown in FIG. 2, in this molding method, first, an injection process 6 in which the optical material 1 is arranged on the molding surface of the molding die 4b, and a heating process 7 in which the temperature is controlled by the heater block 5 to raise the temperature of the optical material 1. A pressurizing step 8 for raising and lowering the lower molding die 4b with respect to the heated optical material 1, a cooling step 9 for cooling the optically deformed optical material 1, and a lower side The molding step 4b is lowered, and an extraction step 10 for taking out the optical material 1 (optical lens) from the molding apparatus 2 is sequentially performed.

  FIG. 3 shows the relationship between the temperature of the molding dies 4a and 4b and the distance between the dies in each process. In the heat and pressure molding using this molding apparatus 2, first, the optical material 1 is placed on the molding surface of the molding die 4b when the molding dies 4a and 4b are at a low temperature, and the molding surface of the molding die 4a is optical. A heating step 7 is performed in which the temperature of the heater block 5 is raised while the molding die 4b is raised to a position close to the surface of the material 1 to heat the molding dies 4a and 4b, the body die 3 and the optical material 1. . Subsequently, the temperature of the heater block 5 is raised so that the temperature of the optical material 1 becomes equal to or higher than the glass transition temperature, and then the pressing die 8 is further raised to pressurize and deform the optical material 1. I do. Next, a cooling step 9 is performed in which the optical material 1 is cooled to a temperature at which the optical material 1 can be taken out, and a molding die 4b is lowered to take out an optical lens that is the optical material 1 after molding. Note that the pressurization step 8 starts the cooling of the molding die 4 and completes the pressurization when the temperature becomes close to the glass transition temperature, and suppresses shrinkage deformation of the optical material 1 in the cooling step 9.

  In this embodiment, the waiting time 11 from when the temperature of the molding dies 4a and 4b shown in FIG. 3 reaches a predetermined molding temperature until the start of pressurization is shortened. That is, the waiting time 11 is a time for soaking so that the temperature distribution from the outer part of the optical material 1 through the molding die 4 to the inner part to be heated is reduced. However, when the standby time 11 for soaking is shortened as described above, the inner side of the optical material 1 at the start of pressurization in the pressurization step 8 can be shortened. Since the temperature of the portion is lower than that of the outer portion and the viscosity increases accordingly, if a predetermined molding pressure required for pressure molding is applied to the optical material 1 at the start of pressurization, the high viscosity region of the inner portion A large pressing force is applied to the optical lens to cause cracking of the optical lens after molding.

  Therefore, when pressurizing the optical material 1 having a temperature distribution by shortening the waiting time 11, the pressurizing method by the molding die 4 is not a pressurizing method by pressure control such as an air cylinder or an oil cylinder. A pressurizing method is used in which the pressurizing speed of the molding die 4b, that is, the moving speed of the molding die 4b is controlled by a servo motor or a cam mechanism.

  That is, since the pressure applied to the molding die 4b is controlled by the moving speed, the pressure applied to the optical material 1 changes depending on the viscosity and the deformation amount, so that a large molding pressure is applied to the optical material 1 at a time when pressing is started. Instead, since pressure corresponding to the deformation speed is applied, the pressure at the start of pressurization is small, and deformation starts from the contact portion of the optical material 1 or the vicinity thereof, and the optical material 1 and the molding die 4 are accompanied by this deformation. As a result, the heat transfer from the molding die 4 is increased, thereby increasing the temperature of the inner portion of the optical material 1 and enabling further deformation.

  That is, even if the optical material 1 has a temperature distribution at the start of molding, the temperature distribution becomes smaller according to the progress of pressure molding, so that the optical material 1 is soaked before the pressurization starts. The waiting time 11 can be shortened and the productivity of the optical lens can be improved.

Further, in order to shorten the waiting time 11 in this way, the composition of the low dispersion glass having a large Abbe number belongs to phosphate glass, fluorinated glass, and fluorophosphate glass, and the glass composition has many alkaline modified oxidations. In particular, it has a low thermal conductivity of 0.80 W · m ^-1 · k ^-1 or less because the original network structure including glass is weak, and it is particularly effective for such an optical material 1 having a low thermal conductivity. It becomes.

  The pressurization speed control in the pressurizing step is a pressurizing means useful when the outer portion and the inner portion of the optical material 1 have a temperature distribution, and after this temperature distribution becomes small and there is substantially no difference. May be switched to pressure control.

  The present invention has an effect of shortening the molding time of an optical lens, and is particularly useful for heat-pressure molding of low dispersion glass having low thermal conductivity.

DESCRIPTION OF SYMBOLS 1 Optical material 4a, 4b Molding die 7 Heating process 8 Pressurizing process 9 Cooling process

Claims (2)

A molding method for forming an optical lens by heating and pressurizing an optical material, the heating step of placing the optical material between a pair of molding dies and heating, and adding the heated optical material with the molding dies. A pressure step for pressure deformation, and a cooling step for cooling the pressure-deformed optical material, and the optical material has a temperature distribution in which the temperature of the inner portion is lower than the temperature of the outer portion at the start of pressurization in the pressure step. And a method of molding an optical lens, wherein at least the pressurization method at the start of pressurization is controlled by pressurizing and deforming by controlling the pressurization speed of the mold. The method of molding an optical lens according to claim 1, wherein the thermal conductivity of the optical material is 0.80 W · m ⁻¹ · k ⁻¹ or less.

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