JP2011136883A - Apparatus and method for molding optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for molding an optical element that can control the temperature to heat a molding material and a molding die and perform efficient press molding. <P>SOLUTION: The apparatus 1 for molding an optical element includes a molding die composed of an upper die 11, a lower die 12 and a body die 13, and a driving means 20 to move at least one of the upper die 11 and the lower die 12 up and down, wherein a molding material 2 of the optical element contained in the molding die is heated up to its softening temperature or higher and then subjected to press molding using the upper die 11 and lower die 12 to obtain the optical element of a predetermined shape. The apparatus 1 is further equipped with a upper heater 20 to directly heat the upper die 11, a lower heater 21 to directly heat the lower die 12, an infrared lamp heater 22 to heat the body die 13, a heater 15 to heat the molding material 2 installed attachably-detachably in the molding die, and a temperature controller to control each of the upper heater 20, lower heater 21, infrared lamp heater 22 and heater 15 to heat the molding material independently. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical element molding apparatus and molding method, and more particularly, to an optical element molding apparatus and molding method capable of individually managing and controlling the temperature of a molding die and a molding material.

  Currently, optical elements used in small imaging equipment and optical pickups are heat-softened optical element molding materials, and press molding is performed to transfer the molding surface shape of the mold while pressing the softened molding materials. It is manufactured by cooling and solidifying the molded material.

  For example, this press molding includes a pair of molds, and is performed by a mold-fixed type apparatus that relatively moves one of the pair of molds. Heating is performed by an infrared lamp disposed around the mold or the body mold, a heater embedded in the press shaft holding the mold, or the like (see, for example, Patent Document 1).

  In this method of heating the mold and the optical element molding material integrally, the entire mold is surrounded by an infrared lamp, the temperature of the optical element molding material can be easily adjusted by the temperature of the mold, and management is simple. In addition, heating by an infrared lamp has been widely performed because of relatively excellent temperature uniformity.

  By the way, in this press molding, it is advantageous to efficiently heat the optical element molding material that is the object to be softened by heating, so that the heating efficiency of the optical element molding material has been improved. In addition to the infrared lamp, a molding apparatus provided with a heating lamp dedicated to the molding material is known (see Patent Document 2).

  Also, by embedding a heater inside the upper mold, which is a molding die, and heating the molding surface of this upper mold, only the surface of the molding material that will be the molded part will be softer than the other parts. There is known a molding apparatus that suppresses thermal softening of the entire molding material and prevents flow during pressing (see Patent Document 3). The present invention further intends to transfer the shape accurately and surely even for a fine pattern by concentrating and softening only the surface of the molding material.

JP 2003-26432 A JP 2004-115280 A JP 2008-137835 A

  However, the molding apparatus as disclosed in Patent Document 1 is for press molding by heating an optical element molding material integrally with a molding die, so that the molding material cannot be individually heated and is efficiently press-molded. Can not do. In addition, this molding device manages the temperature of the molding die with a thermocouple and can control the temperature. However, since the heater exists on the press shaft holding the molding die, the temperature of the molding material or the molding material to be actually controlled is controlled. The mold temperature could not be controlled directly, and a concept such as temperature correction had to be introduced.

  Furthermore, since the member where the thermocouple is installed and the member that feeds back the information detected by the thermocouple are different members, the temperature of the heater immediately increases when the temperature of the molding material or mold changes. Even if it is controlled, there is a problem that a time lag occurs until it is reflected in the temperature of the molding material and the mold.

  And although the shaping | molding apparatus like patent document 2 is going to heat the shaping | molding material efficiently, since it is based on the heating means provided in the outer periphery of the shaping | molding die by an infrared lamp, a shaping | molding material is rapidly used. However, it was not sufficient in terms of improving the molding efficiency.

  In addition, since a molding apparatus such as Patent Document 3 has a heater embedded in the upper mold and is heated to a temperature at which the molding material is softened by this heating, the heating temperature is highest in the mold. turn into. However, although the molding die is press-molded by setting the surroundings to an inert gas atmosphere, there is a concern that the higher the temperature, the faster the deterioration.

  The present invention has been made to solve the above-described problems, and can control the temperature of the molding material and the mold individually, and provides a temperature sufficient to make the temperature of the molding material soft. However, an object of the present invention is to provide an optical element molding apparatus in which the temperature of the molding die is not unnecessarily heated so that deterioration can be suppressed, and an optical element molding method using the molding apparatus.

  The optical element molding apparatus of the present invention includes a molding die composed of an upper die, a lower die and a barrel die, an upper die holding member for holding the upper die and the upper end of the barrel die, and a lower die for holding the lower end of the lower die. Provided with a mold holding member and a driving means for moving up and down at least one of the upper mold holding member and the lower mold holding member, the optical element molding material is accommodated in the molding die, and the optical element molding material is heated to a softening temperature or higher. Then, in an optical element molding apparatus that press-molds an optical element molding material into an optical element having a predetermined shape by moving at least one of the upper mold holding member and the lower mold holding member toward each other, the optical element molding material is accommodated inside the lower mold. A lower heater that directly heats the lower mold, an upper heater that is housed in the upper mold and directly heats the upper mold, an infrared lamp heater that is provided around the body mold and heats the molding mold, and a molding mold Heat the optical element molding material housed in Therefore, a heater for molding material provided in the mold so as to be detachable, temperature detecting means respectively disposed in the upper die, the lower die, the barrel die and the heater for molding material, and detection of the temperature detecting means And a temperature control means for individually controlling the temperature of the upper heater, the lower heater, the infrared lamp heater, and the molding material heater based on the results.

  Further, the optical element manufacturing method of the present invention uses the optical element molding apparatus of the present invention to heat and soften the optical element molding material on the mold, and press the softened optical element molding material with the molding die. An optical element manufacturing method for providing an optical element shape and cooling and solidifying the optical element molding material provided with the optical element shape, wherein the temperature detecting means are disposed in the upper mold, the lower mold, and the body mold, respectively. The temperature of the upper heater, the lower heater, the infrared lamp heater, and the molding material heater is individually controlled based on the detection result.

  According to the molding apparatus and molding method of an optical element of the present invention, the upper die, the lower die, and the optical element molding material are provided with dedicated heaters, respectively, and the heating temperature is individually controlled to control the temperature of each element. Can be performed stably, and the optical element can be molded efficiently.

  Furthermore, by making the temperature of the optical element molding material higher than the temperature of the mold, the press molding operation can be performed efficiently, and the mold is prevented from being unnecessarily heated. Deterioration of the mold can also be suppressed. Therefore, it is possible to extend the life of the mold and thereby reduce the manufacturing cost.

1 is a side sectional view showing a schematic configuration of an optical element molding apparatus according to an embodiment of the present invention. It is the figure which showed the operation | movement at the time of press molding of the shaping | molding die of FIG. 1, and the heater for shaping | molding materials.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a side sectional view showing a schematic configuration of an optical element molding apparatus according to an embodiment of the present invention, and FIG. 2 shows an operation during press molding of the molding die and molding material heater shown in FIG. FIG.

  First, the optical element molding apparatus of the present invention is an apparatus for press-molding an optical element molding material 2, and this optical element molding apparatus 1 includes an upper mold 11, a lower mold 12, a body mold 13, a stopper 14, a molding. Material heater 15, upper heat insulating member 16, lower heat insulating member 17, upper shaft 18, lower shaft 19, upper heater 20, lower heater 21, lamp heater 22, alignment mechanism 23, upper frame 24, lower frame 25, lamp heater A support member 26, a support column 27, a base frame 28, a drive mechanism 29, and the like are provided.

  The upper mold 11 molds the upper surface of the optical element by press molding. The lower mold 12 molds the lower surface of the optical element by press molding. Each of the upper mold 11 and the lower mold 12 is a member having a cylindrical body as a basic shape, and the upper heater 20 and the lower heater 21 are inserted into the center of the surface opposite to the molding surface of the optical element. Have holes for.

  The lower mold 12 has a flange 12b at the lower end of the lower mold 12 in order to improve stability during use. The upper mold 11 has an upper molding surface 11a for molding the upper surface of the optical element, and the lower mold 12 has a lower molding surface 12a for molding the lower surface of the optical element. The upper mold 11 and the lower mold 12 are used as a set of molds with the upper molding surface 11a and the lower molding surface 12a facing each other.

  The upper mold 11 is attached to and held by the upper shaft 18 via the upper heat insulating member 16. The upper shaft 18 is a fixed shaft attached to the upper frame 24. The upper heat insulating member 16 and the upper shaft 18 each have a hole through which the upper heater 20 passes in the center. Although not shown in FIG. 1, the upper heat insulating member 16 and the upper shaft 18 each have an introduction path for introducing a cooling medium into the upper mold 11. The upper heater 20 passes through the upper heat insulating member and the upper shaft and is inserted into the upper mold 11 to directly heat the upper mold 11.

  The lower mold 12 is attached and held to the lower shaft 19 via the lower heat insulating member 17. The lower heat insulating member 17 and the lower shaft 19 each have a hole through which the lower heater 21 passes in the center. Although not shown in FIG. 1, the lower heat insulating member 17 and the lower shaft 19 each have an introduction path for introducing a cooling medium into the lower mold 12. Since the lower shaft 19 is disposed on the alignment mechanism 23, the lower shaft 19 is automatically aligned when the upper mold 11 and the lower mold 12 are slid. The lower heater 21 is housed in 17 and 19 and directly heats the lower mold 12.

  The body mold 13 is a cylindrical member attached to the upper heat insulating member 16, and the upper mold 11 and the lower mold 12 are slid to align the central axes of the upper mold 11 and the lower mold 12. The stopper 14 is disposed on the flange 12 b of the lower mold 12 and regulates the distance in the vertical direction between the upper mold 11 and the lower mold 12. The molding material heater 15 is a flat heater, and heats the optical element molding material 2 by the radiant heat of the plate-like body heated to a high temperature.

  The lamp heater 22 includes an infrared lamp 22a, a reflection mirror 22b disposed behind the lamp heater 22, a support member 22c for supporting the infrared lamp 22a and the reflection mirror 22b, and is attached to the lamp heater support member 26. Each of the infrared lamp 22a and the reflecting mirror 22b is configured by stacking two or more semicircular arc-shaped parts in a ring shape, and has a cylindrical shape as a whole. It is attached so as to surround it. The body mold 13 is heated by infrared rays emitted from the lamp 22a.

  The upper mold 11, the lower mold 12, and the body mold 13 are each provided with a temperature detecting means such as a thermocouple for detecting the temperature of each member, and is connected to a temperature control means (not shown). A temperature control program is input to the temperature control means, and the outputs of the upper heater 20, the lower heater 21 and the lamp heater 22 are individually controlled according to the temperature detected by the temperature detection means. The molding material heater 15 is provided with a thermocouple attached to the heater, and the temperature of the heater itself is controlled by temperature control means.

  The alignment mechanism 23 is attached on the lower frame 25. The alignment mechanism 23 includes a rolling element type load receiver 23a and a base 23b that holds the rolling element type load receiver 23a. The rolling element type load receiver 23a includes an annular race plate, a rolling element, and a cage, and can move the lower shaft 19 horizontally. This horizontal movement of the lower shaft 19 also moves the lower heat insulating member 17 and the lower mold 12 formed integrally with the lower shaft 19 at the same time, and when the lower mold 12 is inserted and fitted into the body mold 13, Fine positioning can be easily performed. The rolling element may be a steel ball used in a bearing or the like.

  The drive mechanism 29 has an elevating mechanism such as a servo motor or an air cylinder. For example, the servo motor is used as a drive source to convert the rotational motion of the servo motor into a linear motion thrust, thereby moving the moving shaft 29a up and down. The drive mechanism 29 is attached to the base frame 28 with the upper end of the moving shaft 29 a in contact with the lower surface of the lower frame 25. The moving shaft 29a is driven in the vertical direction with the speed, position and axial load controlled by a program input to a control device (not shown). For this reason, the lower frame 25 also moves up and down as the moving shaft 29a moves up and down, and the lower mold 12 that is indirectly fixed to the lower frame 25 also moves up and down.

  The optical element molding apparatus 1 has a chamber 30 that accommodates the components of the apparatus described above except for the drive mechanism 29. The chamber 30 can be maintained in an inert gas atmosphere with an inert gas such as nitrogen, so that the members constituting the apparatus are not oxidized during press molding. It is easy to maintain the environment.

  Hereinafter, the molding material heater 15, the upper heater 20, the lower heater 21, and the lamp heater 22, which are characteristic portions of the present invention, will be described.

  In the present invention, the molding material heater 15 is a dedicated heater for heating the optical element molding material 2 and can heat the molding material placed on the lower mold 12 in a non-contact state from above. For example, the type, shape, etc. are not particularly limited. By the way, the optical element molding material 2 is generally formed in a spherical shape or a flat spherical shape, and the molding material heater 15 is formed in a flat plate shape so that the entire molding material can be uniformly heated. It is preferable that the molding material 2 can be disposed so as to cover the planar shape. For example, a heating element such as a cartridge heater, a ceramic heater, or a SiC heater is inserted into a metal plate such as stainless steel or ambiloy. What is comprised can be mentioned.

  Here, the planar shape of the molding material heater 15 needs to be larger than the planar shape of the optical element molding material 2, and in order to heat the molding material uniformly more efficiently, the molding material is required. The area of the planar shape of the heater 15 is preferably at least three times the area of the planar shape of the optical element molding material 2. The molding material heater 15 is provided with a thermocouple 31 therein, and the temperature of the heater is directly detected, and the output is adjusted by the temperature control means according to this temperature, so that the molding material heater 15 is desired. The temperature can be maintained. The molding material heater 15 includes a rectangular parallelepiped shape, a heater provided therein, and a thermocouple 31. The thermocouple 31 is 1 to 5 mm above the heater provided inside in the vertical direction and the molding material heater 15 in the horizontal direction so that the temperature of the molding material heater 15 can be reflected immediately. It is preferable to provide it within a circle having a radius of 10 mm from the center.

  The molding material heater 15 can be removably moved into the molding die through an opening formed on the side surface of the barrel die 13 and inserted into the molding die. Thus, the molding material heater 15 is disposed between the upper mold 11 and the lower mold 12. Here, a groove for guiding the molding material heater 15 is formed on the inner side surface of the body mold 13, and a guide pin projects from the side surface of the molding material heater 15 so as to correspond to the groove. When the molding material heater 15 is inserted into the molding die, the guide pin moves along the groove so that the molding material heater 15 is disposed at a predetermined position.

  In the present invention, the upper heater 20 is a cartridge heater in which a terminal portion or a terminal lead wire is formed at one end of a metal pipe. The cartridge heater is inserted into a hole formed on the surface of the upper mold 11 opposite to the molding surface 11a of the optical element, and the upper mold 11 is directly heated by raising the temperature of the cartridge heater. Can be done.

  The upper heater 20 detects the temperature of the upper die 11 by a thermocouple 32 similarly provided in the upper die 11, and maintains a predetermined temperature by the temperature control means in accordance with the detected temperature. The output of the upper heater 20 is adjusted. The thermocouple 32 is preferably provided at a position of 5 to 10 mm from the upper molding surface 11a so that the temperature of the molding material can be immediately reflected.

  In the present invention, the lower heater 21 is a cartridge heater in which a terminal portion or a terminal lead wire is formed at one end of a metal pipe. The cartridge heater is inserted into a hole formed on the surface opposite to the molding surface 12a of the optical element of the lower mold 12, and the lower mold 12 is directly heated by increasing the temperature of the cartridge heater. Can be done.

  The lower heater 21 detects the temperature of the lower die 12 by a thermocouple 33 provided in the lower die 12 and maintains a predetermined temperature by the temperature control means according to the detected temperature. The output of the lower heater 21 is adjusted. The thermocouple 33 is preferably provided at a position of 5 to 10 mm from the lower molding surface 12a so that the temperature of the molding material can be reflected immediately.

  Since the upper heater 20 and the lower heater 21 are embedded in the same members as the thermocouples 32 and 33 that perform temperature management, respectively, even when feedback control is performed, the time lag is small, and the temperature is stricter than before. It can be managed.

  Further, the upper heater 20 and the lower heater 21 are configured to be inserted into the respective molds through holes formed in the upper mold and the lower mold, respectively, but expansion of the heater and the mold during heating is performed. Due to the difference in rate, the heater may be damaged inside the mold and may not function. Therefore, when inserting the heater into the mold, it is preferable to provide a buffer member on the surface of the heater and insert this into the mold.

At this time, the buffer member may be any member having a thermal expansion coefficient in the range of 3 to 20 × 10 ⁻⁶ and heat resistance to the heating temperature. For example, the thermal expansion coefficient is about 3 to 8 × 10 ^−6. It is desirable to use a heat-resistant steel (for example, nickel, hastelloy, or carbide) having a small thermal expansion, and the shape may be any shape that prevents the heater from being damaged by thermal expansion. Shape, collet chuck shape).

  In the present invention, as described above, the lamp heater 22 includes the infrared lamp 22a, the reflection mirror 22b disposed behind the infrared lamp 22a, the infrared lamp 22a, and the support member 22c for supporting the reflection mirror 22b.

  Here, the infrared lamp 22a is for heating the entire mold by irradiation with infrared rays, and in order to efficiently perform this infrared irradiation, a reflection mirror 22b is provided behind the mold, and the reflection mirror 22b The reflected infrared light also contributes to the heating of the mold. The infrared lamp 22a and the reflection mirror 22b are fixed to the support member 22c, and further fixed to the lamp heater support member 26, so that the mold 13 can be sufficiently heated. It is arranged around.

  The infrared lamp 22a detects the temperature of the body mold 13 by a thermocouple 34 provided on the body mold 13, and in accordance with the detected temperature, the infrared lamp 22a maintains a predetermined temperature by the temperature control means. The output of 22a is adjusted. The thermocouple 34 is preferably inserted into the body of the body mold 13 and disposed in a height range of about 10 mm above and below the center of the body mold 13 in the height direction.

  The molding material heater 15, the upper heater 20, the lower heater 21, and the lamp heater 22 have their heating timing and temperature controlled by the temperature control means. In particular, the upper heater 20, The temperature of the lower heater 21 and the lamp heater 22 is individually controlled based on the result detected by the temperature detection unit as described above.

  Next, the optical element molding method of the present invention will be described in the case of using the optical element molding apparatus 1 of FIG.

  The optical element molding apparatus 1 is disposed in a chamber 30, and the inside of the chamber 30 is replaced with an inert gas such as nitrogen. When the replacement is completed and the inside of the chamber 30 becomes an inert gas atmosphere, the preheated optical element molding material 2 is placed on the molding surface 12a of the lower mold 12, and the upper heater 20, the lower heater 21, and the lamp heater are placed. The entire mold is heated by 22 and at the same time, the optical element molding material 2 is also heated.

  While performing this heating, the lower die 12 is moved upward by the driving means 29 to fit the lower die 12 to the barrel die 13. The fitted lower mold 12 is further moved upward, and once the molding material heater 15 and the optical element molding material 2 reach a predetermined distance, the upward movement is once stopped. Here, for the molding material The heater 15 is heated to a temperature at which the optical element molding material 2 is softened (FIG. 2A). The upper mold 11 and the lower mold 12 are aligned with each other so that the optical axes of the optical elements coincide with each other by the fitting to the body mold 13, thereby ensuring coaxiality.

  At this time, the distance between the molding material heater 15 and the optical element molding material 2 is appropriately determined depending on the shape and performance of the heater, the size of the optical element molding material, and the like so that the molding material can be heated uniformly. That's fine. In general, for example, it may be adjusted within a range of 3 to 10 mm. At this time, if the distance is too close, the temperature distribution is generated on the surface of the molding material and the temperature varies depending on the location. The surface of the molding material cannot be heated to a desired molding viscosity.

  At the same time, the upper die 11 and the lower die 12 are heated by the upper heater 20 and the lower heater 21, respectively. These heaters 20 and 21 individually control the temperature of the die. The mold temperature can be detected by thermocouples provided on the upper mold 11 and the lower mold 12, and the positions where these thermocouples 32 and 33 are attached reflect the temperature of the optical element molding material 2 as accurately as possible. The mold surfaces 11a and 12a are preferably provided inside the mold, and for example, the distance between the mold surfaces 11a and 12a and the thermocouple is preferably 5 to 10 mm.

  FIG. 2 shows an example in which the upper die 11 is provided with a thermocouple 32 at the tip of the upper heater 20, and the lower die 12 is provided with a thermocouple 33 at the tip of the lower heater 21. Thus, by installing a heater and a thermocouple in the mold, the time lag in temperature control can be reduced, and the temperature management of the upper mold 11 and the lower mold 12 can be performed more strictly.

  At this time, the temperature of the upper mold | type 11 and the lower mold | type 12 may be the same temperature, and may provide a temperature difference. When providing a temperature difference, it is preferable that the temperature difference between the upper mold 11 and the lower mold 12 is in the range of about 2 to 15 ° C.

  At the same time, the lamp heater 22 can also heat the entire mold and maintain the heated state during press molding. At this time, each heater is individually adjusted and maintained by the temperature control means so as to have a predetermined temperature.

  The molding material heater 15 is heated to a temperature at which the molding material is softened. When the material is heated to a temperature above the yield point (At) of the material, deformation is facilitated, but generally the temperature is raised to the softening point. Since the lens surface becomes cloudy, the temperature is set between the yield point and the softening point. The heating temperature here may be a temperature at which the glass material to be used can be pressurized and deformed, and is preferably a temperature in the vicinity of the middle between the yield point and the softening point. Although the heating temperature of this heater varies depending on the type of optical element molding material used, the heating temperature and the heating timing are controlled by temperature control means so that the optical element can be heated to a predetermined temperature range without performing feedback control. Can be controlled. The molding material heater 15 may stop heating when performing press molding because the object to be heated disappears due to the movement of the molding die to the outside.

  Further, the upper heater 20 and the lower heater 21 individually manage the temperatures of the upper mold 11 and the lower mold 12, respectively, and the temperatures are controlled by thermocouples 32 and 33 embedded in the respective molds. By feeding back the detected temperature, the temperature is controlled within a predetermined temperature range. At this time, the temperature of the upper mold 11 and the lower mold 12 is preferably 5 to 50 ° C. higher than the yield point (At) of the molding material.

  Further, the lamp heater 22 heats the entire mold and can rapidly heat the mold. The lamp heater 22 is suitable for heating the entire mold, and is particularly useful in the initial stage of heating. The lamp heater 22 is controlled to a predetermined temperature range by temperature control means by detecting the temperature of the body mold 13 by a thermocouple 34 provided in the body mold and feeding back the detected temperature. The temperature of the body mold 13 at this time is preferably set to a temperature that is 5 to 50 ° C. higher than the yield point (At) of the molding material.

  When the optical element molding material 2 and the molding die are sufficiently heated by the molding material heater 15, the upper heater 20, the lower heater 21, and the lamp heater 22, the molding material heater 15 is inserted into the molding die from the opening of the barrel die 13. (Fig. 2 (b)).

  Simultaneously with the movement of the molding material heater 15, the lower mold 12 is moved upward again, and the optical element molding material 2 is pressed with the upper mold 11 to give a desired optical element shape (FIG. 2 ( c)). The stroke of the lower mold 12 for pressing is a preset value based on the thickness of the optical element to be molded, and is determined in consideration of the thermal contraction of the optical element after molding in the cooling process of the next process. Amount. In the present embodiment, a stopper 14 is provided so as to stop the upward movement of the lower mold 12 at a predetermined position.

In general, the speed of press molding is desirably 3 to 600 mm / min. In the case of molding a glass lens having a diameter of 15 mm or more, it is preferably 3 to 80 mm / min. The pressing procedure can be arbitrarily set according to the shape and size of the optical glass to be molded. In this case, it is preferable that the pressure during pressing is to 2.5~37.5N / mm ^2, particularly preferably 10~20N / mm ²

  Immediately after pressing the molding material by press molding, heating by the upper heater 20, the lower heater 21 and the lamp heater 22 is stopped, and the molding die is cooled. When the temperature of the molding die becomes equal to or lower than the glass transition point (Tg) of the molding material, the lower die 12 is lowered by the driving means 29 to release the press-molded optical element, and the optical element can be taken out. To do.

  The mold is cooled by circulating a cooling medium inside the upper heat insulating member 16 and the upper shaft 18 that hold the upper die 11, and the lower heat insulating member 17 and the lower shaft 19 that hold the lower die 12. The lower mold 12 may be cooled by circulating a cooling medium in the interior of the chamber, and at this time, any of a gas such as nitrogen and a liquid such as cooling water may be used as the cooling medium. However, in consideration of deterioration due to oxidation of the mold, an inert gas such as nitrogen is preferable.

  At this time, in order to prevent the occurrence of cracks and radiation flaws in the optical element, the cooling rate can be set to 50 to 200 ° C./min as an average value from the start of cooling to mold release. The cooling rate at the start of cooling may be larger than the average cooling rate, and it is preferable to reduce the cooling rate as the mold release temperature is approached and to cool slowly so as not to cause distortion in the molding material. The mold release temperature can be in the vicinity of the glass transition point Tg or lower, but in general, it is preferably a value in the range from (Tg-50 ° C.) to Tg.

  Further, the optical element is cooled to a temperature equal to or lower than the strain point of the material, and when it is preferably 200 ° C. or lower, the optical element on the lower mold 12 is carried out of the chamber 30 by the carrying-out means. When the optical element is carried out of the chamber 30, the upper heater 20, the lower heater 21 and the lamp heater 22 heat the mold again to prepare for the next press molding.

  By repeatedly performing the above operation, an optical element can be efficiently manufactured.

  In addition, there is no restriction | limiting in particular about the shape of the optical glass to manufacture, Molding of a biconvex lens, a biconcave lens, a plano-convex lens, a plano-concave lens, a convex meniscus lens, a concave meniscus lens, etc. can be performed. There is no particular limitation on the size of the optical element, and generally, an optical element having a diameter of about 2 mm to about 50 mm can be molded. This is because if the thickness is 2 mm or less, the glass material is likely to be cooled, so that the glass material is easily broken. If the thickness is 50 mm or more, it takes time for molding and it is extremely difficult to obtain a good surface. Furthermore, the shape of the optical glass can be spherical, aspherical, or a combination thereof.

  Incidentally, the mold used at this time is preferably formed of a cemented carbide such as tungsten carbide.

Next, the present invention will be described in more detail with reference to specific examples.
(Example 1)
Using the optical element molding apparatus shown in FIGS. 1 and 2, the optical element was molded as follows.

  The mold used here is made of cemented carbide made of tungsten carbide, and has a diameter φ of 40 mm, a center thickness of 7.5 mm, a peripheral thickness of 3 mm, and an approximate aspheric radius of curvature by press molding. A 100 mm and 85 mm biconvex molded product is obtained, and an optical element having a diameter of 35 mm is obtained by post-processing a centering process.

  Further, the molding material heater 15 is formed by inserting three cartridge heaters with a diameter of 6 mm into a 60 × 80 × 20 mm stainless steel plate, and the upper heater 20 and the lower heater 21 have a diameter of 8 mm. The outer periphery of the cartridge heater is covered with a 3 mm thick stainless steel plate, and the lamp heater 22 has a configuration of 2 kW × 3.

  Here, an opening having a size of 30 × 70 mm is provided on the side surface of the body mold 13, and the molding material heater 15 can be inserted into and removed from the molding mold through the opening. The upper heater 20 and the lower heater 21 are inserted such that the tips of the heaters are at a distance of 5 mm from the molding surfaces 11a and 12a of the upper mold 11 and the lower mold 12, respectively. , 33 are provided. Further, the lamp heater 22 is installed on the outer periphery of the body mold 13 with a spacing of 40 mm, and a control thermocouple 34 is provided inside the body mold 13.

  This mold was preheated to 550 ° C., and the diameter φ36 mm, center thickness 8.83 mm, and peripheral thickness 4.3 mm produced by grinding and polishing made of lanthanum glass preheated to 200 ° C. on the molding surface 12 a of the lower mold 12. An optical element molding material of a biconvex spherical lens having a curvature radius of 90 mm and 60 mm, respectively, was placed. Next, the output of the upper heater 20, the lower heater 21 and the lamp heater 22 was increased and the mold was heated to 680 ° C. This optical element molding material has a strain point of 580 ° C., a glass transition point (Tg) of 616 ° C., and a yield point (At) of 662 ° C.

  Simultaneously with the heating, the lower mold 12 on which the glass material is placed is moved upward by the driving means 29, the lower mold 12 is fitted into the body mold 13, and the molding material heater 15 and the optical element molding are further performed. After moving the lower mold | type 12 upward until the distance with the raw material 2 was set to 10 mm, the upward movement was once stopped.

Here, by setting the temperature of the molding material heater to 920 ° C., the optical element molding material was heated to about 690 ° C. When the heating was sufficiently performed, the molding material heater was moved to the outside of the molding die. Thereafter, the lower mold 12 was again moved upward, and the optical element molding material was pressed by the upper mold 11 and the lower mold 12 to perform press molding. The pressing pressure at the time of molding was 20 N / mm ² , and the pressing time was 45 seconds. At this time, the position of the lower mold 12 is controlled so as to be a position where the desired lens thickness is 7.5 mm, and the press pressure is set to zero when the desired position is reached.

After pressing, the outputs of the upper heater 20, the lower heater 21, and the lamp heater 22 are lowered, and further, N ₂ gas is circulated through the flow paths provided in the upper shaft 18 and the upper heat insulating member 16 so that the upper die 11 is moved to the lower shaft. 19 and the lower heat insulation member 17 are made to flow N ₂ gas through a flow path, and the lower mold 12 is cooled at a constant cooling rate of 30 ° C./min. At a desired temperature between the yield point (At) and the glass transition point (Tg), the press pressure is increased to 20 N / mm ² again, and when it reaches 580 ° C., the press pressure is reduced to zero to give the optical element shape. The formed molding material was cooled to 580 ° C. and solidified.

  Next, the upper heater 20, the lower heater 21, and the lamp heater 22 are stopped, and the cooling rate of the upper mold 11 and the lower mold 12 is set to 60 ° C./min. When cooled to about 550 ° C., it was removed from the mold and an optical element was obtained.

  As described above, according to the molding apparatus and molding method of the optical element of the present invention, dedicated heaters are provided for the upper mold, the lower mold, and the optical element molding material, respectively, and the heating temperature is individually controlled so that each element is controlled. Thus, the temperature control of the optical element can be performed stably, and the optical element can be molded efficiently.

  In addition, the temperature control of the optical element molding material by the upper mold and the lower mold is such that when the heater and the thermocouple are present in the same member, and the mold temperature is fed back by arranging them near the molding surface, Since the time until heating with the heater is shortened and the time lag is less likely to occur, temperature management can be performed more accurately.

  The method and apparatus for molding an optical element of the present invention can be used for manufacturing an optical element by press molding.

DESCRIPTION OF SYMBOLS 1 ... Optical element molding apparatus, 11 ... Upper mold, 12 ... Lower mold, 13 ... Body mold, 14 ... Stopper, 15 ... Molding material heater, 16 ... Upper heat insulation member, 17 ... Lower heat insulation member, 18 ... Upper shaft , 19 ... Lower shaft, 20 ... Upper heater, 21 ... Lower heater, 22 ... Lamp heater, 23 ... Centering mechanism, 24 ... Upper frame, 25 ... Lower frame, 26 ... Support member, 27 ... Column, 28 ... Base frame , 29 ... Drive mechanism, 30 ... Chamber, 31, 32, 33, 34 ... Thermocouple

Claims (5)

A mold composed of an upper mold, a lower mold, and a body mold, an upper mold holding member that holds upper ends of the upper mold and the barrel mold, a lower mold holding member that holds a lower end of the lower mold, and the upper mold A driving means for moving up and down at least one of the holding member and the lower mold holding member is provided, the optical element molding material is accommodated in the mold, the optical element molding material is heated to a softening temperature or higher, and then the upper mold is held. In an optical element molding apparatus that moves at least one of a member and a lower mold holding member toward each other and press-molds an optical element molding material into an optical element of a predetermined shape,
An upper heater housed in the upper mold and directly heating the upper mold;
A lower heater housed in the lower mold and directly heating the lower mold;
An infrared lamp heater provided around the body mold for heating the mold;
A heater for a molding material provided to be removably inserted into the molding die in order to heat the optical element molding material accommodated in the molding die;
Temperature detecting means respectively disposed in the upper die, the lower die, the barrel die and the molding material heater;
Temperature control means for individually controlling the temperature of the upper heater, the lower heater, the infrared lamp heater, and the molding material heater based on the detection result of the temperature detection means;
An optical element molding apparatus comprising:   2. The optical element molding apparatus according to claim 1, wherein each of the upper heater and the lower heater has a buffer member on a surface thereof and is accommodated in the upper mold and the lower mold.   The optical element molding apparatus according to claim 1, wherein the body mold has an opening for inserting and removing the heater for molding material into and from the mold. The optical element molding material is heated and softened on a molding die using the optical element molding apparatus according to any one of claims 1 to 3, and the softened optical element molding material is press-molded by the molding die to be optical. An optical element molding method for providing an element shape and cooling and solidifying an optical element molding material provided with an optical element shape,
The temperature of the upper heater, the lower heater, the infrared lamp heater, and the molding material heater is individually controlled based on the detection results of the temperature detecting means disposed in the upper mold, the lower mold, and the body mold, respectively. Optical element molding method.   When heating and softening the optical element molding material, the upper heater, the lower heater, the infrared lamp heater, and the molding material heater are arranged so that the temperature of the optical element molding material is higher than the temperature of the mold. The method for molding an optical element according to claim 4, wherein the temperature is controlled.

Images