JP2011105562A - Forming method and forming apparatus of optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forming method and forming apparatus suppressing occurrence of faults in the surface shape of an optical element. <P>SOLUTION: The forming apparatus 1 of an optical element comprises: a forming die having an upper die 2, a lower die 3, an inner cylinder 4 and an outer cylinder 5 capable of accommodating a glass material to press form; heating means (6a and 6b) to heat the forming die to soften the glass material 80; pressing means 6a and 6b to pressurize the softened glass material by the forming die to impart an optical element shape; and cooling means (6a and 6b) to solidify the glass material imparted with the optical element shape, wherein the forming apparatus 1 has an outer cylinder cooling means 7 to cool the outer cylinder during the press formation by the pressing means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a molding method and a molding apparatus for an optical element, and in particular, when a glass material is press-molded, pressure on the glass material can be applied during cooling, thereby suppressing the occurrence of a defective surface shape of the optical element. The present invention relates to a molding method and a molding apparatus for an optical element.

  At present, as a method for producing an optical element such as a glass lens, a press molding method in which a glass material as an optical element molding material is press-molded and can be used as it is without polishing the molding surface is often used.

  In this press molding method, an optical element having a predetermined shape is obtained by heating and softening a glass material, press-pressing with a molding die, and then cooling to form an optical element having a predetermined shape. Accuracy is required. In particular, the apparatus is strictly configured so that the distance between the upper die and the lower die is a predetermined distance during pressing so that the thickness dimension becomes the target thickness.

  For example, FIG. 4 shows the operation of a conventional press molding method. The optical element molding apparatus 101 used here includes an upper mold 102, a lower mold 103, and a hollow cylindrical shape capable of press molding a glass material 80. A mold having a body 104 and an outer body 105, heating plates 106a and 106b for heating the mold to soften the glass material 80, and a press for pressing the softened glass material with the mold to give an optical element shape. It has plates 107a and 107b, and cooling plates 108a and 108b for cooling the glass material provided with the mold and the optical element shape.

  The inner cylinder 104 has a function of restricting the optical axes of the upper mold 102 and the lower mold 103 coaxially, and the outer cylinder 105 has a function of regulating the distance between the upper mold 102 and the lower mold 103 during pressing. It is what has.

  As shown in FIG. 4, first, the mold and the glass material 80 are heated by the heating plates 106 a and 106 b (FIG. 4 -heating stage), and then the glass material 80 that is softened by heating is pressed into the press plate 107 a and the glass material 80. The distance between the upper die 102 and the lower die 103 is reduced by narrowing the distance 107b, and pressing is performed. At this time, the minimum distance between the upper mold 102 and the lower mold 103 is restricted to a constant distance by the outer body 105, and the optical element to be molded has a constant thickness under a predetermined pressure (FIG. 4—press stage). (A)).

  By the way, at the time of this press molding, the temperature of the press plates 107a and 107b is heated to a high temperature of, for example, 500 ° C. or higher. In some cases, the temperature increases and the distance between the press plates 107a and 107b increases. As a result, a space is generated between the press plate 107a and the upper mold 102, and the necessary pressure may not be applied to the glass material (FIG. 4—press stage (b)). If the glass material is cooled and solidified without applying pressure in this manner, the surface shape of the obtained optical element may become defective, and the product yield may be reduced.

  In order to solve such a problem, for example, a target position that is a press position is calculated in advance, and when pressing, the detected position becomes the target position while detecting the press position of the mold. A molding method (see Patent Document 1) in which a press load is applied until the position where the upper die and the glass material are in contact is detected, and the press is performed based on the amount of movement of the upper die or the lower die from this contact position. A molding method (see Patent Document 2) that performs molding, and a body mold that regulates the interval between molding surfaces are selected so that the amount of heat shrinkage in the vertical direction is equal to or greater than the amount of heat shrinkage of the thickness of the glass molded body. There is known a method for manufacturing a glass optical element made of a different material (see Patent Document 3).

JP 2006-176356 A JP 2008-179488 A Japanese Patent No. 4094210

  However, since the methods of Patent Documents 1 and 2 are performed using a sensor or the like so that the press position and movement amount of the mold are set to predetermined values, not the distance restriction by the body mold, the apparatus configuration is complicated, and the position There was a problem that adjustment was difficult. Further, the method of Patent Document 3 is a method in which the distance is regulated by a body mold, and the material is selected so that the amount of thermal shrinkage is larger than that for the glass molded body. This was performed by changing the ambient temperature of the. By the way, even if this technique is diverted when the temperature is adjusted by bringing the heating means and the cooling means into direct contact with the mold, the temperature adjustment by the contact is also a temperature difference depending on the distance from the contact position of the mold member. It becomes large and cannot be applied as it is.

  Therefore, in order to solve the above problems, the present invention provides an optical element molding method and molding apparatus for adjusting the temperature of a molding die by bringing heating means and cooling means into contact with each other. It is an object of the present invention to provide an optical element molding method and a molding apparatus which can be easily regulated and can apply pressure to the glass material with a simple structure even after the glass material is press-molded.

  The optical element molding apparatus of the present invention includes a molding die having an upper die, a lower die, an inner cylinder and an outer cylinder capable of accommodating a glass material and press-molding, and a glass material in the molding die by heating the molding die. A heating means for softening, a pressing means for pressurizing the softened glass material with a molding die to impart an optical element shape, a cooling means for cooling the molding die and solidifying the glass material imparted with the optical element shape, An optical element molding apparatus having an outer cylinder cooling means for cooling the outer cylinder during press molding by a press means.

  The optical element molding method of the present invention includes a glass material contained in a molding die having an upper die, a lower die, an inner cylinder and an outer cylinder, and the glass die in the molding die is softened by heating the molding die. A heating process, a pressing process in which a softened glass material is pressed with a molding die using a pressing means to give an optical element shape, and after the pressing process, the molding die is cooled to give an optical element shape to the glass material. And a cooling step for solidifying, characterized in that after the press cutting of the glass material is completed in the pressing step, the outer body is cooled while continuing to pressurize the glass material. It is.

  According to the molding method and molding apparatus of the optical element of the present invention, the upper and lower positions of the molding die can be easily regulated by the outer cylinder, and the outer cylinder is cooled after the pressing when the glass material is press-molded. By doing so, the pressurization state to a glass raw material can be continued and it can suppress that the malfunction of the surface shape of an optical element arises.

It is a schematic block diagram of the shaping | molding apparatus of the optical element which is one Embodiment of this invention. FIG. 2 is a plan view of the outer body cooling means shown in FIG. 1 and a side sectional view in the AA ′ direction. It is the figure which showed the molding conditions of the molding method of the optical element which is one Embodiment of this invention. It is sectional drawing at the time of the optical element press in the shaping | molding apparatus of the conventional optical element.

  The present invention will be described below with reference to the drawings. Here, FIG. 1 is a schematic configuration diagram of an optical element molding apparatus according to an embodiment of the present invention, and FIG. 2 is a plan view and a side view of an outer shell cooling means used in the optical element molding apparatus of FIG. FIG.

  First, the optical element molding apparatus 1 shown in FIG. 1 heats a molding die having an upper mold 2, a lower mold 3, an inner cylinder 4 and an outer cylinder 5 capable of press-molding a glass material 80, and a molding mold. An optical element molding apparatus comprising press plates 6a and 6b, which are press means for applying a shape of an optical element by softening a glass material 80 and then pressing the softened glass material with a molding die. Outer cylinder cooling means 7 is provided between 6a and 6b for cooling the outer cylinder 5 when a glass material is pressed by the press plate. Here, the press plates 6a and 6b have a temperature control function so that the mold can be heated and cooled, and also serve as heating means, pressing means, and cooling means.

  In the present embodiment, the mold is composed of an upper mold 2, a lower mold 3, an inner cylinder 4 and an outer cylinder 5. The upper mold 2 and the lower mold 3 are columnar members and are formed in a hollow cylindrical shape. It can be inserted into the hollow portion of the inner cylinder 4. The inner cylinder 4 is configured to insert the upper mold 2 and the lower mold 3 and restrict the optical axes of the upper mold 2 and the lower mold 3 coaxially during pressing. The outer cylinder 5 has a hollow cylindrical shape like the inner cylinder 4, but the inner cylinder 4 can be inserted and the distance between the press plates 6a and 6b is restricted, whereby the upper mold 2 and the lower mold 3 are arranged. It regulates the distance between them. Here, it is preferable that the inner cylinder 4 and the outer cylinder 5 have the same central axis and are provided in a non-contact state.

  This molding die is made of a material such as cemented carbide or ceramics, and the upper die 2 and the lower die 3 have molding surfaces for transferring the surface shape of the optical element to be molded on opposite surfaces. . In FIG. 1, an optical element for manufacturing a concave meniscus-shaped optical element is illustrated as a mold, but the optical element shape is not limited to this, and is biconvex, biconcave, plano-convex, plano-concave, convex meniscus. Any mold that molds any shape can be used. For the outer cylinder, stainless steel (SUS) is used instead of the ceramics. Stainless steel is preferable because it is easy to process, has a larger thermal expansion coefficient than ceramics, and is cheaper.

  The press plates 6a and 6b of the present embodiment can reduce the distance between the upper mold 2 and the lower mold 3 by reducing the distance between the plates, and the glass material 80 accommodated in the mold can be reduced. The optical element is molded by pressing and deforming in the softened state and applying the optical forming surface shapes of the upper mold 2 and the lower mold 3 to the glass material 80.

  The press plate 6a, which is the pressing means, has a temperature control function for heating and cooling the mold, and a heater is embedded in the press plate 6a. Therefore, by bringing this pressing means into contact with the mold, the glass material 80 is melted and softened through the mold, press-molded with the mold, and then a series of operations for cooling and solidifying the molded glass material is performed 1 It can be done on one plate.

  When pressing the glass material, the press plates 6a and 6b regulate the distance between the press plates 6a and 6b according to the height of the outer shell 5 of the mold, so that the distance between the upper mold 2 and the lower mold 3 is reduced. To be adjusted. Thereby, the thickness of the optical element to be molded is adjusted.

  In addition, when the glass material provided with the optical element shape is cooled and solidified by cooling the mold, it is cooled below the glass transition point of the glass material, more preferably below the strain point. When cooled, the shape of the optical element of the glass material is stabilized and deformation is suppressed.

  Furthermore, the press plate 6a can be pressurized to the glass material by gradually increasing the pressure when cooling and solidifying the glass material to which the optical element shape has been applied, if necessary. You may provide the pressure control means which controls a pressure.

  And the outer cylinder cooling means 7 of this invention cools the outer cylinder 5 of a shaping | molding die, and cools an outer cylinder in the case of press molding of the glass raw material by a shaping | molding die. The outer cylinder cooling means 7 is not particularly limited as long as it can cool the outer cylinder 5, but from the viewpoint of efficiency, the outer cylinder 5 is brought into contact with the refrigerant from the outer periphery. It is preferable that the contact can be performed uniformly.

  Examples of the outer cylinder cooling means 7 include those that cool by jetting a cooling gas to the outer cylinder, and those that cool the outer cylinder by directly contacting the cooling means cooled by the refrigerant. Since it is simple and can be cooled without contact with the outer cylinder 5, the apparatus configuration is simple, the efficiency is high, and problems such as contamination are unlikely to occur, so that the outer cylinder 5 is cooled by jetting cooling gas. Is preferred.

  As shown in FIG. 2, for example, as shown in FIG. 2, the outer body cooling means 7 is a cooling gas jetting portion 7a in which a pipe is formed in an annular shape, and the cooling gas is sent to the cooling gas jetting portion 7a. The cooling gas delivery part 7b is connected to a cooling gas cylinder or the like, and the cooling gas is supplied to the end part of the cooling gas delivery part 7b. The reason why the cooling gas ejection portion 7a is annular is that cooling is performed by placing a molding die inside the ring.

  The cooling gas jetting portion 7a is provided with a plurality of cooling gas jetting ports 7c for jetting the cooling gas toward the center of the ring on the side surface on the center side of the ring of the pipe. By ejecting the cooling gas from 7c, the cooling gas comes into contact with the outer cylinder 5 to cool the outer cylinder 5. At this time, a plurality of cooling gas jets 7c are provided. The cooling gas jets 7c and the outer body 5 are equal to each other, and adjacent cooling gas jets 7c are connected to each other. It is preferable to equidistantly cool the outer cylinder 5 so as to be uniformly performed on a certain horizontal plane. For this uniform cooling, for example, it is preferable to provide the outer body cooling means 7 in an overlapping manner so that the cooling can be performed uniformly in the vertical direction.

  In general, a preheating plate for preheating the glass material 80 is provided before the press plate 6a, and a glass material that is cooled below the glass transition point or below the strain point after the press plate 6b. On the other hand, cooling is further continued, and a cooling plate is provided which is cooled to 200 ° C. or lower to be an optical element. An example of the cooling plate is a water-cooled plate that is cooled by circulating cooling water inside the plate. Furthermore, the optical element obtained by cooling is subjected to an annealing process or the like to perform post-processing such as removal of distortion or the like to obtain a final product.

  In addition, the above-described press plates 6a and 6b have been described as performing heating, press molding, and cooling operations. However, as shown in the conventional example of FIG. As described above, the heating plate and the cooling plate may be provided separately from the press plate. At this time, the press plate should just be able to perform the press molding operation by a shaping | molding die, maintaining the temperature of a glass raw material. At this time, the processing is performed while sequentially moving the molding die to each plate, and moving means for moving the molding die from this plate to the plate is provided. This moving means is moved from the heating plate to the press plate and from the press plate to the cooling plate, for example, by a robot arm or the like.

Next, an optical element molding method using the optical element molding apparatus 1 will be described.
First, the glass material 80 is accommodated in the mold, the mold is heated, and the glass material is preheated to a predetermined temperature in advance. Next, after the mold is moved onto the press plate 6, when the press plates 6a and 6b are brought into contact with the upper mold 2 and the lower mold 3 and further heated, the glass material 80 accommodated therein is also heated. This softens the glass material.

  The glass material is heated to a temperature higher than the deformation point where deformation is easy, but generally, the lens surface becomes clouded when the temperature is raised to the softening point, so the temperature is set between the yield point (At) and the softening point.

  The heating temperature may be a temperature at which the glass material to be used can be deformed under pressure, and is preferably a temperature in the middle between the yield point and the softening point. When the press plates 6a and 6b are set to a predetermined temperature and this heating step is performed, the upper mold 2 and the lower mold 3 are heated to the same temperature as the set temperature of the press plate as the temperature rises. .

  When the upper mold 2 and the lower mold 3 are heated and the glass material reaches a temperature sufficient for press molding, the press plate 6a is lowered to reduce the distance between the press plates 6a and 6b. The distance between the mold 2 and the lower mold 3 is reduced, and the glass material 80 accommodated in the mold is deformed by applying pressure to perform press molding. At this time, the distance between the upper mold 2 and the lower mold 3 is regulated to a predetermined distance by the height of the outer cylinder 5.

  In this pressing step, as described above, the glass material 80 is press-molded by applying pressure from above and below the molding die, whereby the optical forming surfaces of the upper mold 2 and the lower mold 3 are transferred to the glass material, and the optical material An element shape is given.

The pressure during pressing in the pressing step is preferably set to 0.1~30N / mm ^2, for example, and particularly preferably 0.5~10N / mm ^2.

  However, in the present invention, when performing press molding, the outer cylinder cooling means 9 is disposed around the outer cylinder 5, and the outer cylinder cooling means is immediately after the glass material 80 is pressed by the press plates 6a and 6b. The outer cylinder 5 is cooled by 9.

  Here, the outer cylinder cooling means 7 is provided, as mentioned in the conventional problem, is heated by the outer cylinder 5 coming into contact with the press plate and expands, and is higher than the initially pressed position by expansion. This is to prevent the occurrence of a defect in the surface shape of the optical element by avoiding the occurrence of a space between the upper die 2 and the press plate 6a that is pushed up and the pressure being not applied to the glass material.

  In the pressing process as in the present invention, the outer body 5 is cooled immediately after the pressing, so that the glass material can be pressed by the upper mold 2 in the subsequent pressing process and cooling process. That is, since pressure is always applied to the glass material from the upper mold 2, it is effective in suppressing defects in the surface shape of the optical element.

  At this time, the cooling of the outer body 5 is preferably started as soon as possible after completion of the pressing in the pressing step, and more preferably started within one second, for example. The cooling rate may be such that the amount of change due to the shrinkage in the height direction of the outer body 5 is greater than the amount of change due to the shrinkage in the height direction of the glass material 80, the upper die 2 and the lower die 3. The cooling rate is preferably equal to or higher than the cooling rate of (6a, 6b). If it is slower than the plate cooling rate, surface cracking may occur.

  In this outer cylinder cooling, the outer cylinder is cooled to a temperature that sufficiently suppresses the vertical expansion of the outer cylinder. For example, the stainless steel outer cylinder is cooled so as to be lower by 5 to 200 ° C., preferably 10 to 100 ° C. lower than the upper die and lower die temperatures, so that the expansion is sufficiently suppressed, and the subsequent pressing step and cooling step In this case, pressure can be applied to the glass material.

  At this time, when cooling with nitrogen gas, industrial nitrogen gas is used as the nitrogen gas, and the temperature of the outer cylinder can be lowered by blowing this nitrogen gas onto the outer cylinder. In the case of cooling using this nitrogen gas, for example, when the outer circumference of the cylindrical outer cylinder 5 is about φ30 mm, the nitrogen flow rate is preferably 2 to 30 L / min, and 5 to 20 L / min. More preferably.

  In this outer cylinder cooling, the temperature of the press plates 6a and 6b is lowered at the same time, and the temperature of the molding die including the outer cylinder 5 is also lowered. In this outer shell cooling, it is preferable to cool until the strain point or lower.

  The outer cylinder cooling is performed immediately after the pressing of the mold in the pressing process, but the pressurization to the glass material is continuously performed as it is, and the pressurization is continued until the temperature becomes equal to or lower than the strain point. It is preferable. Furthermore, it is preferable to change the pressure applied to the glass material when the temperature of the glass material becomes equal to or lower than the glass transition point during the cooling. For example, when the temperature of the glass material 80 is equal to or higher than the glass transition point, it is preferable to apply the pressure at the time of pressing as it is, and to increase the pressure after the temperature becomes lower than the glass transition point, and pressurize in steps.

  The reason why the pressure at the temperature above the glass transition point is set to a low pressure is to suppress the thickness variation (reduce the indentation amount), and in the temperature range below that, there is almost no indentation amount, so the pressure is increased. That is, the pressure is maintained at a low pressure until the glass material is close to the cured state (Tg), and a higher pressure is applied until the glass material is solidified from near the glass transition point (Tg). It is.

Here, the low pressure is 5 N / mm ² or less, and the high pressure is more than 5 N / mm ² . When a high pressure is applied, any pressure may be used as long as there is no problem such as cracking of the glass material. Usually, the upper limit is about 30 N / mm ² . At this time, although the example in which the pressure is increased in two stages has been described above, the pressure may be increased or decreased as more stages.

  Thus, by heating, press molding and cooling on one plate, an optical element can be manufactured with a small number of plates, and the apparatus configuration can be simplified. In addition, by performing the cooling and solidification with a single plate in this way, it is possible to avoid a state in which no pressure is applied during movement between the plates after pressing, and the problem that the surface shape of the molded optical element is not stable is solved. it can.

  And the shaping | molding die which completed the press process in this way is moved, for example on a water cooling plate, in order to make it cool further. The cooling by the water-cooled plate further cools the glass material cooled in the pressing process, and cools the glass material from a temperature in the vicinity of the strain point to 200 ° C. or less at which the mold does not oxidize.

  According to the present invention, by cooling the outer cylinder in the pressing process, the expansion of the outer cylinder in the vertical direction can be suppressed, the thickness of the optical element can be brought close to the original shape of the mold, and the optical shape is high. An element can be obtained.

  In addition, by suppressing the vertical expansion of the outer shell, it is possible to maintain the pressurized state of the glass material immediately after the press-off and through the cooling process, and continue to apply pressure to the glass material during the cooling process. Thus, the occurrence of defects in the surface shape of the optical element can be suppressed.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
The optical element was molded as follows using the optical element molding apparatus of FIG. As a molding condition in this press molding, the relationship between the upper mold and lower mold temperatures and time is shown in FIG. 3A, and the relationship between the pressure applied to the glass material and time is shown in FIG. 3B. The pressure in FIG. 3B refers to the pressure of the air sent to the press air cylinder of the press device. When a lens element having a diameter of 16 mm is molded by this press apparatus, the pressure applied to the element at an air pressure of 0.1 MPa is 5 N / mm ² .

  The molding die used here is made of a cemented carbide made of tungsten carbide, and a concave meniscus optical element having a diameter of 16 mm, a center thickness of 1 mm, and a peripheral thickness of 5 mm can be obtained by press molding. . The outer cylinder made of SUS316L was used with a cylindrical inner diameter of φ24.6 mm, an outer diameter of φ30 mm, and a height of 29.8 mm.

  Further, as shown in FIG. 2, the outer body cooling means has a pipe with an inner diameter of 4 mm and an outer diameter of 6 mm in an annular shape to form a cooling gas jetting portion, and a cooling gas is delivered to a part of the cooling gas jetting portion. A cooling gas delivery unit capable of being connected is connected. Further, the cooling gas jetting portion is provided with eight cooling gas jetting ports having a diameter of φ1 mm at equal intervals on the side surface on the center side of the ring to jet the cooling gas toward the center of the ring.

  A lanthanum glass material having an elliptical cross section with a diameter of 14 mm and a center thickness of 5.4 mm is accommodated in the mold, and the mold is heated to around 700 ° C. This glass material has a strain point of 580 ° C., a glass transition point (Tg) of 616 ° C., and a yield point (At) of 662 ° C.

  First, the mold containing the glass material is preheated to about 500 ° C., and then conveyed and placed on the press plate 6b by the conveying means, and at the same time, the press plate 6a is lowered and brought into contact with the upper mold, The upper mold, the lower mold, and the glass material were sufficiently heated for 150 seconds, and the glass material was softened by raising the temperature.

Next, when the molding die and the glass material are sufficiently heated to reach the same temperature as the press plates 6a and 6b (about 700 ° C.), the press plate 6a is further lowered and pressed to form the upper die 2 and the lower die. The glass material was press-molded according to 3. The pressure at the time of molding was set to 0.1 MPa (5 N / mm ² ) and pressed for about 160 seconds to cut off.

  In this press molding, cooling by the outer cylinder cooling means was started 1 second after completion of the press-off, and the outer cylinder was cooled by supplying nitrogen gas at 10 L / min. Even during the outer shell cooling, the same pressure as that during pressing was continuously applied to the glass material. At the same time as the outer cylinder cooling was started, the temperature of the press plates 6a and 6b was lowered at a rate of 2/5 (° C./second) to cool the entire mold. At this time, as shown in FIG. 3, the temperature of the upper mold and the lower mold is also lowered so as to follow the temperature of the press plates 6a and 6b.

When the temperature of the upper plate 6a becomes 640 ° C. or lower, the pressure on the glass material is increased to 0.15 MPa (7.5 N / mm ² ), and cooling is continued as it is, so that the strain point of the glass material is increased. Cooled to below.

When the glass material became a temperature below the strain point, the press plate 6a was raised, the mold was transferred onto the water-cooled plate and placed, and the glass material was cooled to room temperature. When the glass material was sufficiently cooled, it was taken out of the mold and an optical element was obtained.
When the optical element obtained by molding this optical element was randomly taken out from different molds, sequentially distinguished from the molds A to D, and the wall thickness was measured, the results shown in Table 1 were obtained.

(Example 2)
An optical element was obtained in the same manner as in Example 1 except that the cooling by the outer cylinder cooling means was performed by supplying nitrogen gas at 6 L / min. When the thickness of the optical element obtained from the same mold as that measured in Example 1 was measured, the results shown in Table 1 were obtained.

(Comparative Example 1)
In the pressing step, the optical element was molded by the same operation as in Example 1 except that nitrogen gas was not ejected from the outer cylinder cooling means and the outer cylinder was not cooled. When the thickness of the optical element obtained from the same mold as that measured in Example 1 was measured, the results shown in Table 1 were obtained.

(Test example)
When the optical elements obtained in Example 1 and Comparative Example 1 were examined for the presence of cracks, the results shown in Table 2 were obtained. Those with no cracks were set as OK, and those with some cracks were set as NG. There are two methods for inspection of surface cracks: a method of visually confirming a shadow projected on a light source such as a mercury lamp and a method of confirming with a microscope. This time, it was visually confirmed by projecting with a mercury lamp. In this specification, surface cracking refers to an optical element having a discontinuous curvature when only part of the optical element is released first and then the rest is released after the optical element is released from the mold. This refers to a mold release abnormality in which a surface is formed and a defect in which the accuracy of the aspheric shape deteriorates occurs.

  As shown above, by the method of molding an optical element of the present invention, by performing outer cylinder cooling immediately after the pressing of the press molding operation, it is possible to accurately transfer the originally planned shape of the mold, It was found that an optical element with high shape accuracy can be obtained. In addition, since this molding method can perform a cooling operation while applying pressure to the optical element by forced cooling of the outer body, it is possible to effectively suppress the occurrence of surface shape defects such as cracks in the optical element. .

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

DESCRIPTION OF SYMBOLS 1 ... Optical element molding apparatus, 2 ... Upper mold, 3 ... Lower mold, 4 ... Inner cylinder, 5 ... Outer cylinder, 6a, 6b ... Press plate, 7 ... Outer cylinder cooling means, 80 ... Glass material

Claims (7)

A mold having an upper mold, a lower mold, an inner cylinder and an outer cylinder capable of containing a glass material and capable of being press-molded, heating means for heating the mold and softening the glass material in the mold, and softened An apparatus for molding an optical element, comprising: a pressing unit that pressurizes a glass material with the mold and imparts an optical element shape; and a cooling unit that cools the mold and solidifies the glass material imparted with the optical element shape. And
An apparatus for molding an optical element, comprising outer cylinder cooling means for cooling the outer cylinder during press molding by the pressing means.   2. The optical element molding apparatus according to claim 1, wherein the outer cylinder cooling means cools the outer cylinder by injecting a cooling gas.   The outer body cooling means is a pipe formed in an annular shape, and a cooling gas ejection part having a cooling gas ejection port for ejecting a cooling gas toward the center of the ring on the center side surface of the ring, The apparatus for molding an optical element according to claim 2, further comprising: a cooling gas delivery unit that delivers a cooling gas to the cooling gas ejection unit. A glass material is housed in a mold having an upper mold, a lower mold, an inner cylinder, and an outer cylinder, and a heating process for heating the mold to soften the glass material in the mold, and pressing the softened glass material, An optical process comprising: a pressing step for applying an optical element shape by pressurizing with the molding die using means; and a cooling step for cooling the molding die and solidifying the glass material provided with the optical element shape after the pressing step. A method of forming an element,
An optical element molding method comprising performing an outer cylinder cooling step of cooling the outer cylinder after the pressing of the glass material is completed in the pressing step.   5. The method for molding an optical element according to claim 4, wherein the outer cylinder cooling step is performed by injecting a cooling gas into the outer cylinder.   6. The method of molding an optical element according to claim 5, wherein the cooling gas is nitrogen gas.   The method for molding an optical element according to claim 6, wherein a supply amount of the nitrogen gas is 2 to 30 L / min.

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