JP2007091554A - Mold-press mold, manufacturing method of optical element, and recessed meniscus lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold-press mold capable of efficiently manufacturing an optical element with high shape precision in a high yield through restraining thickness unevenness or the like at the time of press molding by preventing positional deviation of a molding material fed on the molding face of the lower mold from occurring, and a method for manufacturing an optical element. <P>SOLUTION: In press-molding a molding material 50 softened by heating using a molding mold equipped with an upper mold 10 and a lower mold 20 having opposing molding faces 14 and 24, respectively, the molding material 50 is fed on the molding face 24 of the lower mold having a recessed face, the upper mold 10 is held above the molding material 50 by an upper mold holding means 40 so that the molding face 14 of the upper mold does not come into contact with the molding material 50, and the mold is transferred to a treatment chamber for carrying out a treatment necessary for the press molding in a state permitting the movement of the molding material 50 to the center position of the molding face 24 of the lower mold, and performing the press molding. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  When manufacturing an optical element such as a glass lens by a precision mold press, the present invention prevents an uneven thickness especially during press molding, and efficiently manufactures an optical element having a high shape accuracy with a high yield. The present invention relates to a mold press mold capable of forming an optical element, a method for manufacturing an optical element, and a concave meniscus lens.

  In manufacturing an optical element such as a glass lens by softening a molding material such as glass by heating and press-molding with a pair of upper and lower molds precisely processed into a predetermined shape, Patent Document 1 discloses the center of the lower mold. As a positioning device for positioning so that the center of the glass material matches, the positioning member having the glass material insertion hole and the glass material insertion hole in contact with the outer peripheral surface of the lower mold or the lower mold fixture There is described a glass material positioning device provided with a centering member for centering, and an attaching / detaching mechanism for attaching / detaching the centering member to / from the lower mold or the lower mold fixture.

  Further, in Patent Document 2, an optical glass material is set on the lower mold surface, and in order to align it, using a centering jig mounted with a barrel mold assembled to the lower mold as a guide, A method is described in which the glass material is aligned before the upper mold is installed.

JP 2002-308633 A JP 7-81953 A

In such a conventional technique, according to the positioning device as disclosed in Patent Document 1, it is possible to position the glass material so that the center of the glass material coincides with the center of the lower mold. It is said that a simple optical element can be obtained.
However, the positioning device of Patent Document 1 is based on the premise that press molding is performed at the same position after supplying and positioning the glass material. When press molding is performed after moving to the position, it cannot be applied as it is.

According to Patent Document 2, a glass material is set on a lower mold, and a cylinder mold and a centering jig are assembled into the lower mold, and then the upper mold assembling station is loaded. It is removed from the body mold and the upper mold is incorporated immediately after that. In this way, when the upper mold is assembled, the glass material will be held between the lower mold and the upper mold, and the glass material will be misaligned even if there is some vibration after that. It is said that there is no inconvenience.
Then, the molding die is transferred to the heating part, the glass material is softened or melted, and the lens is molded by pressing between the upper die and the lower die. Since it is set in an accurately aligned state with respect to this mold, the molding accuracy is remarkably improved, and high-precision press molding is possible.

However, in the method of Patent Document 2, even if the glass material is aligned before the upper mold is assembled, there is little possibility that the glass material will be displaced when the upper mold is assembled or thereafter. Absent.
For example, when the lower mold forming surface is a concave surface having a large radius of curvature, the glass material is likely to be displaced due to vibration during transportation, and this tendency is particularly noticeable when the glass material has a convex curved surface such as a sphere. It is.
In addition, when the upper mold surface has a convex surface due to the shape of the lens to be obtained, when the glass material is sandwiched between the upper mold and the lower mold, the glass material before heat softening is As shown in FIG. 5, the glass material may escape from the center of the lower mold and move as it comes into contact with the convex portion of the upper mold. And if such position shift arises, a glass material will not return to an original position.

  Furthermore, as in Patent Document 2, when the molding after the upper mold is assembled is transferred to another position and press molding is performed, it is virtually impossible to completely eliminate vibrations associated with the transfer. Therefore, there have been problems such as uneven thickness caused by the positional displacement of the glass material on the lower mold forming surface and shape defects.

By the way, in recent years, compact imaging devices for mobile terminals, optical pickups, and optical lenses used in optical communication and the like have been required to achieve both miniaturization and high optical performance. The accuracy is getting higher and higher.
For example, the lens required for these applications has a lens diameter of about 1 to 5 mm, and the thinnest part is about 0.1 to 1 mm. When these lenses are molded by precision mold press, the optical functional surface is formed by press molding on the premise that post-processing such as centering is not performed after press molding. The method of forming by the member and defining the outer diameter is advantageously applied.
For example, by this method, the outer diameter variation can be within 5 μm, and furthermore, a lens with high shape accuracy in which the coincidence between the optical axis and the outer diameter center is within several μm can be obtained.

However, if press molding is performed at a position where the glass material deviates from the center position of the mold, the molded body will be unevenly thickened, resulting in defects in the outer periphery due to partial underfilling, or protrusions due to partial overfilling. , Burr formation may occur.
For example, when placing the glass material on the lower mold forming surface, even if it is arranged at the center position of the lower mold forming surface having a concave surface with sufficient positional accuracy, as described above, the shape of the upper and lower molds, and the upper and lower molds and the glass Misalignment is likely to occur due to the mutual relationship between the shapes of the materials.

In addition, when many of the lenses for the above applications are mounted on an optical device, positioning with other components is performed by a flat portion formed on the outer side of the optical effective diameter or an outer peripheral surface.
Therefore, poor shape due to press molding and non-uniform shape, even if it is a region outside the effective optical diameter, impairs the lens mounting accuracy and adversely affects the optical performance of the device. . For this reason, the outer periphery of the lens is required to be formed as a transfer surface of a mold member such as a barrel mold over 360 degrees. Even if it is misalignment, the outer peripheral surface is easily lost and the mounting accuracy is likely to deteriorate, and the influence is serious.

  The present invention has been made in view of the above circumstances, and prevents misalignment during press molding so as not to cause misalignment of the molding material supplied onto the lower mold molding surface. An object of the present invention is to provide a mold press mold, a method for manufacturing an optical element, and a concave meniscus lens capable of efficiently manufacturing a high optical element with a high yield.

  In order to achieve the above object, a mold press mold of the present invention comprises an upper mold and a lower mold having molding surfaces facing each other, transferred to a processing chamber where processing necessary for press molding is performed, and heated. A mold press mold for press-molding a softened molding material, wherein the molding surface of the lower mold has a concave surface at least in the center position, and the molding material supplied onto the molding surface of the lower mold In addition, the upper mold holding means for holding the upper mold so that the molding surface of the upper mold does not come into contact and allowing the molding surface of the upper mold to contact the molding material when a press load is applied. It is set as the structure provided with.

  By adopting such a configuration, when press-molding the molding material, the molding material is not in contact with the molding surface of the upper mold until a press load is applied to the molding die, and the lower mold It can move freely on the molding surface. For this reason, the molding material can move to the center position of the concave molding surface by rolling or sliding with its own weight, thereby effectively avoiding misalignment of the molding material. Thus, it is possible to efficiently manufacture an optical element with high yield accuracy by preventing uneven thickness during press molding.

Moreover, the mold press mold of this invention can be set as the structure by which the said upper mold holding means is formed using the elastic member.
With such a configuration, the molding surface of the upper mold can be prevented from contacting the molding material by simple means that balances the weight of the upper mold and the biasing force of the elastic member.

In addition, the mold press mold of the present invention includes a barrel mold that regulates the mutual position in the direction perpendicular to the central axis of the upper mold and the lower mold, and resists the elastic force of the upper mold holding means, The upper mold may be configured to be slidable with respect to the trunk mold.
With such a configuration, it is possible to ensure the coaxiality of the upper and lower molds and effectively avoid eccentricity during press molding.

  Further, the mold press mold of the present invention can be configured such that the upper mold molding surface has a convex surface, and even in such a configuration, the upper mold molding surface is not in contact with the molding material. Therefore, the convex surface of the upper mold molding surface does not push the molding material and cause the positional deviation.

  The optical element manufacturing method of the present invention is a method for manufacturing an optical element in which a molding material softened by heating is press-molded using a molding die having an upper die and a lower die having molding surfaces facing each other. The molding material is supplied onto the molding surface of the lower mold having a concave surface, and the upper mold is held on the molding material so that the molding surface of the upper mold does not come into contact with the molding material. In a state where the movement of the molding material to the center position of the molding surface of the lower mold is allowed, the molding die is transferred to a processing chamber for performing processing necessary for press molding, and the molding material is softened by heating. By applying a press load in a state, the upper mold and the lower mold are brought close to each other to perform press molding.

  By adopting such a method, it is possible to effectively avoid misalignment of the molding material, prevent uneven thickness at the time of press molding, and efficiently produce an optical element with high shape accuracy with high yield. Can do.

Further, in the method of manufacturing an optical element of the present invention, the molding material is used together with the molding die in a state where the upper mold is held on the molding material so that the molding surface of the upper mold is not in contact with the molding material. It can be set as the method of heating.
With such a method, it is possible to apply a press load in a state where the viscosity of the molding material at the center position of the molding surface of the lower mold is reduced and the movement thereof is suppressed. Therefore, there is no displacement of the molding material due to the contact with the molding surface of the upper mold during press molding, and the molding material is more reliably press-molded with the molding material positioned at the center of the molding surface of the lower mold. be able to.

Moreover, the manufacturing method of the optical element of this invention can be set as the method of hold | maintaining the said upper mold | type on the said molding raw material by the upper mold | type holding means currently formed using the elastic member.
With such a method, the molding surface of the upper mold can be prevented from coming into contact with the molding material by simple means that balances the weight of the upper mold and the biasing force of the elastic member.

Further, the optical element manufacturing method of the present invention is a method of bringing the upper mold and the lower mold close to each other against the elastic force of the upper mold holding means when a press load is applied to the mold. be able to.
According to such a method, when a press load is applied, the upper and lower mold surfaces can be transferred to the molding material while allowing the upper mold surface to contact the molding material.

Further, the optical element manufacturing method of the present invention is configured such that the molding die supplied with the molding material is sequentially transferred to a plurality of processing chambers including a heating chamber, a press chamber, and a cooling chamber, and is pressed in each processing chamber. It can be set as the method of performing the process required for shaping | molding.
With such a method, heating of the mold to a temperature suitable for press molding, application of a press load, and subsequent cooling treatment can be performed without molding each processing chamber without raising or lowering the temperature of the entire apparatus. This reduces the real time (molding cycle time) required for individual molding, and makes the thermal environment given to each molding material constant, improving the stability in mass production. Can do.

Moreover, the manufacturing method of the optical element of this invention can be made into the method whose surface of the said shaping | molding raw material is a convex curve.
With such a method, it is possible to facilitate the sliding movement and rolling movement of the molding material on the molding surface of the lower mold.

  Moreover, the manufacturing method of the optical element of the present invention can be a method in which the molding surface of the upper mold has a convex surface, and even in such a method, the upper mold molding surface is not in contact with the molding material. Therefore, the convex surface of the upper mold molding surface does not push the molding material and cause the positional deviation.

  In addition, the concave meniscus lens of the present invention can be suitably manufactured by the optical element manufacturing method as described above, and the concave meniscus lens press-molded by the manufacturing method as described above can only have high optical performance. In other words, it can be provided with a high accuracy of attachment to an optical device.

  As described above, according to the present invention, when press-molding a molding material, it effectively avoids misalignment of the molding material, prevents uneven thickness at the time of press molding, and an optical element with high shape accuracy. High yield and efficient production

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Mold press mold]
First, an embodiment of a mold press mold (hereinafter simply referred to as “mold”) according to the present invention will be described.
Here, FIG. 1 is a schematic cross-sectional view of the mold, and shows a state in which the molding material 50 is arranged in the mold.

  In the example shown in the figure, the molding die includes an upper die 10, a lower die 20, and a body die 30. In a press molding apparatus as will be described later, the molding material 50 is placed inside, and the molding die is transferred to a processing chamber in which processing necessary for press molding is performed. The molding material 50 softened by heating is press-molded between the upper mold 10 that is slidably guided by the body mold 30 so as to be relatively close to and away from each other.

Forming surfaces 14 and 24 facing each other are formed on the upper mold 10 and the lower mold 20 constituting the mold by performing precise shape processing based on the shape of an optical element such as a glass lens to be molded. Has been.
In the present embodiment, the molding surface 24 of the lower mold 20 is a combination of a concave surface and a convex surface, even if it has a concave surface and a flat surface as a whole, as long as it has a concave surface at least in the center position. The concave shape may be spherical or aspherical.
On the other hand, the specific shape of the molding surface 14 of the upper mold 10 is not particularly limited, and may be a convex surface, a concave surface, a flat surface, or a combination thereof. The effect of this embodiment becomes remarkable when it has a convex surface, such as an aspheric surface with a portion.

The body mold 30 accommodates the upper and lower molds 10 and 20 and restricts the mutual position in the direction orthogonal to the central axis C of the upper and lower molds 10 and 20. Is ensured, and eccentricity during press molding can be effectively avoided.
For this reason, the clearance between the upper and lower molds 10 and 20 and the body mold 30 is preferably 10 μm or less, particularly 5 μm or less in consideration of the required eccentric accuracy of the optical element, and is required for the optical element to be molded. It can be further reduced depending on the optical performance.

  In the present embodiment, such a body mold 30 is omitted. For example, in the illustrated example, the lower mold 20 and the body mold 30 are integrated, so that the above function of the body mold 30 is achieved. You may make it equip the lower mold | type 20 with the part to bear.

Above such upper die 10 is not limited to such materials used for the lower mold 20 and the body mold 30, for example, ceramics such as known Si 3 _{N 4, SiC,} or cemented carbide and the like as a base material Can be used.
Further, in order to ensure the slipperiness and rolling property of the molding surfaces 14 and 24 with respect to the molding material 50, the molding surfaces 14 and 24 are preferably processed into a smooth flat surface, a spherical surface, or an aspherical surface, Furthermore, on the surfaces of the molding surfaces 14 and 24, for example, a film containing carbon or hydrocarbon as a main component is used by using a known means such as a vapor deposition method, a sputtering method, an ion plating method, plasma CVD, It is preferable to form a film with a predetermined film thickness.

  Further, in this embodiment, the mold holds the upper mold 10 so that the molding surface 14 of the upper mold 10 does not contact the molding material 50 supplied on the molding surface 24 of the lower mold 20, and press When a load is applied, an upper mold holding means 40 that allows the molding surface 14 of the upper mold 10 to contact the molding material 50 is provided.

  The upper mold holding means 40 can be formed using an elastic member. In the illustrated example, a spring made of a heat-resistant material such as metal or ceramic is used as the elastic member that forms the upper mold holding means 40, and the lower end side of the spring 40 is connected to the inside of the body mold 30. While supporting to the step part 31 provided in the surrounding surface, and supporting the step part 11 provided in the side surface of the upper mold | type 10 with the upper end side of the spring 40, it is given so that the upward biasing force may be given with respect to the upper mold | type 10. It is.

  Thereby, the weight of the upper mold 10 incorporated in the body mold 30 and the urging force of the spring 40 are balanced, and the upper mold 10 is held at a predetermined position. The molding surface 14 of the upper mold 10 is The molding material 50 arranged on the molding surface 24 of the lower mold 20 is not brought into contact with the molding die 50. When a press load is applied, the upper die 10 slides on the inner periphery of the barrel die 30 against the elastic force while pushing and shrinking the spring 40, so that the upper die 10 is applied to the molding material 50. The molding surface 14 is allowed to come into contact.

  Therefore, according to the molding die of this embodiment, when the molding material 50 is press-molded, the molding material 50 is not in contact with the molding surface 14 of the upper mold 10 until a press load is applied to the molding die. It is in a state and can move freely on the molding surface 24 of the lower mold 20. For this reason, the molding material 50 is displaced from the center position and is supplied onto the molding surface 24 of the lower mold 20, or after the molding material 50 is supplied, the molding material 50 is subjected to vibration due to the conveyance of the molding die and the like. When the molding material 50 is displaced from the center position of 24, the molding material 50 moves to the center position of the concave molding surface 24 by rolling or sliding with its own weight. can do.

  In particular, when the molding surface 14 of the upper mold 10 has a convex surface, if the molding surface 14 is in contact with the molding material 50 before being softened by heating, the molding material 50 is formed by the molding surface 14. Although it may be pushed away, it may move from the center position of the molding surface 24 of the lower mold 20 and may not return to the original position as it is (see FIG. 5). According to this embodiment, such a molding material 50 is used. It is possible to effectively avoid the misalignment.

  And when the viscosity of the molding material 50 is reduced by the subsequent heating, the movement of the molding material 50 is suppressed. If a press load is applied in this state, even if it contacts the molding surface 14 of the upper mold 10 during press molding, Since the molding material 50 is surely press-molded at the center position of the molding surface 24 without causing a positional shift, uneven thickness at the time of press molding can be prevented.

  Here, when the upper mold 10 is held at a predetermined position so that the molding surface 14 of the upper mold 10 does not contact the molding material 50, the distance between the molding surface 14 of the upper mold 10 and the molding material 50 is the barrel mold 30. In view of the stability of the upper mold 10 with respect to the upper mold 10, it is preferable that the upper mold 10 is not too large. For example, the upper mold 10 can be about 0.2 to 2 mm. There is no particular limitation as long as there is enough clearance to move to the center position, and the non-contact state between the molding surface 14 of the upper mold 10 and the molding material 50 can be maintained.

  Further, the specific configuration of the upper mold holding member 40 is not particularly limited. For example, as shown in the illustrated example, the upper mold 10 can be avoided by avoiding the arrangement of the springs 40 around the molding surfaces 14 and 24. If the spring 40 is disposed between the body mold 30 and the body mold 30, the function of the body mold 30 slidingly guiding the vicinity of the molding surfaces 14, 24 of the upper and lower molds 10, 20 is not impaired. Although the outer peripheral shape of the optical element obtained by press-molding the molding material 50 by the inner peripheral surface of the body mold 30 is defined and does not hinder the omission of the centering process, the upper mold holding member 40 is preferable. Alternatively, it may be arranged between the upper mold 10 and the lower mold 20.

[Mold press molding equipment]
Next, a mold press molding apparatus (hereinafter simply referred to as “molding apparatus”) suitable for carrying out the method of manufacturing an optical element according to the present invention will be described.
Here, FIG. 2 is a schematic plan view of a rotary transfer molding apparatus shown as an example of such a molding apparatus.

The molding apparatus shown in FIG. 2 includes an extraction / insertion chamber P1 and a large number of processing chambers P2 to P8 in which processing necessary for press molding is performed.
In the take-out / insertion chamber P1, an operation of taking out the molding die that has been molded and an operation of inserting a molding die that contains a molding material to be newly used for molding are performed. The molding die inserted from the take-out / insertion chamber P1 is supported by a support base attached to a rotary table that rotates in the direction of the arrow in the drawing, and accommodates the molding material 50 (or molding 51). These are sequentially passed through the processing chambers P2 to P8 that are arranged side by side in the circumferential direction and are always in a non-oxidizing gas atmosphere (inert gas atmosphere). The rotary table rotates intermittently at regular intervals, and the mold moves between adjacent processing chambers by this intermittent rotation. And this fixed time becomes a molding cycle time.

  Here, P2 is a first heating chamber, P3 is a second heating chamber, and P4 is a third heating chamber (or soaking chamber), which are also collectively referred to as a heating unit. P5 is a press chamber, and a press load is applied to a mold set at a temperature suitable for press molding in the heating section. P6 is a first slow cooling chamber, P7 is a second slow cooling chamber, and P8 is a rapid cooling chamber. These are also collectively referred to as a cooling section, and the mold is cooled after a press load is applied. These processing chambers P2 to P8 are arranged at substantially equal intervals, and are controlled to a temperature suitable for each processing, and in order to keep the temperature in each processing chamber at a predetermined temperature, shutters S1 to S6 are used. It is partitioned.

If a molding apparatus as shown in FIG. 2 is used, a desired optical element can be obtained by subjecting a mold containing the molding material 50 (or molded body 51) to appropriate processing while sequentially transporting each processing chamber. It can be manufactured efficiently.
In other words, heating of the mold to a temperature suitable for press molding, application of a press load, and subsequent cooling processing forms each processing chamber arranged two-dimensionally without raising or lowering the temperature of the entire apparatus. Since the process is performed by passing the mold, the actual time (molding cycle time) required for each molding is shortened.
In addition, since the thermal environment applied to each molding material 50 can always be made constant, the mass production stability is high.

  In the method for manufacturing an optical element according to the present invention, a molding die containing a molding material 50 (or a molded body 51) is transferred to each processing chamber such as a heating chamber, a press chamber, and a cooling chamber, and heating, pressing, Although it is suitably implemented in a molding apparatus that sequentially performs appropriate processing including cooling, the specific configuration of such a molding apparatus is not limited to the above-described example. For example, in the above-described example, the mold is transferred by the rotary table, but it is configured so that it can pass through each processing chamber arranged two-dimensionally (in some cases three-dimensionally) at a predetermined time interval. If it is what is carried out, the means in particular to transfer a shaping | molding die will not be restrict | limited.

  Further, the arrangement configuration of each processing chamber can be changed as appropriate in order to optimize the heating process and the cooling process in accordance with the composition of the molding material and the shape of the optical element to be obtained. For example, changes such as four heating chambers or three annealing chambers can be performed. In order to further improve production efficiency, the same number of heating chambers, press chambers, cooling chambers, etc. are provided in series, and multiple types of press molding that require different temperature conditions and different pressurization conditions are performed simultaneously. It may be.

  Further, in order to improve production efficiency, in each processing chamber, when processing such as heating, application of a press load, and cooling processing is performed, so that two or more molds are arranged in one processing chamber, Corresponding to this, a plurality of support bases may be provided so as to move together in each processing chamber, and the same processing may be simultaneously performed on a plurality of molding dies. In this case, the press chamber is preferably provided with two or more pressing means corresponding to the number of molds.

[Method for Manufacturing Optical Element]
Next, an embodiment of the optical element manufacturing method according to the present invention is based on an example in which the molding die shown in FIG. 1 is applied to the molding apparatus shown in FIG. explain.
Here, FIG. 3 is explanatory drawing which shows process (1)-(3) in the manufacturing method of the optical element which concerns on this embodiment, FIG. 4 is explanatory drawing which shows the process (4), (5). .

Step (1): Supply of molding material The position of the body mold 30 in which the upper mold 10 is incorporated is fixed by the support means 80 and the atmosphere gas is sucked from the opening 71 of the mounting table 70, thereby placing the mounting table 70. The lower mold 20 is in close contact with and fixed on the upper mold 10, and the lower mold 20 and the upper mold 10 are waiting in a separated state. Then, a molding material 50 molded into a spherical shape is supplied. When the suction pad of the transfer arm reaches the molding surface 21 of the lower mold 20 with an accuracy within a predetermined range, the suction is released and the transfer arm is immediately retracted.
Thereby, the molding material 50 is placed on the molding surface 24 of the lower mold 20 (see FIG. 3A).

As the molding material 50 used in the present embodiment, a glass material such as a glass preform having desired optical and physical properties and preformed in a predetermined volume and shape in advance can be used.
Specifically, the block-shaped optical glass is cut into a predetermined size, and is cold-worked into a spherical shape by polishing, or the molten glass is dropped or dropped into the receiving mold and separated by an appropriate means. It can be produced by solidifying and preliminarily forming (hot forming), and subjecting the surface to processing such as polishing as necessary. In the latter case, even if processing is involved, the amount of removal by processing is small, so that the amount of glass to be removed is reduced, and a desired spherical shape can be obtained by processing in a short time.

In addition, the shape of the molding material 50 is preferably a convex curved surface, particularly preferably spherical, so that the lower mold 20 can easily slide and roll on the molding surface 24. . The molding material 50 preferably has a smooth surface, and particularly preferably has a spherical shape with a smooth surface by polishing or the like. For example, the difference between the major axis and the minor axis is 10 μm or less, The effect of the present invention can be remarkably obtained by setting the shape to a substantially spherical shape of 5 μm or less.
In the present embodiment, it is particularly preferable to polish the surface of the glass sphere formed by the hot forming to obtain the above sphericity.

Step (2): Mold assembly Assembling table 70 is raised and lower mold 20 is assembled into body mold 30 (see FIG. 3 (2)). At this time, the clearance between the trunk mold 30 and the lower mold 20 is preferably 5 μm or less, and the upper mold 10 and the trunk mold 30 assembled in advance are preferably set to the same clearance.
The upper mold 10 is held on the molding material 50 by the upper mold holding means 40 so that the molding surface 14 does not come into contact with the molding material 50, and the upper mold 10 is molded to the center position of the molding surface 24 of the lower mold 20. While the movement of the material 50 is allowed, the lower surface of the body mold 30 comes into contact with the lower mold 20 to complete the assembly of the mold.

  When assembling the molding die, the upper die 10 and the barrel die 30 may be lowered by the holding means 80 instead of raising the mounting table 70. In the molding apparatus shown in FIG. 2, the steps (1) to (2) may be performed in the vicinity of the extraction / insertion chamber P1 in part or all of the steps (1) to (2). You may make it carry out within P1.

Step (3): Heating Step A molding die containing the molding material 50 is placed on the molding die support 75 on the rotary table by a gripping tool (not shown) and heated while being sequentially transferred to the heating chambers P2 to P4. (See FIG. 3 (3)).
Thus, the molding material 50 is press-molded together with the molding die in a state where the upper mold 10 is held on the molding material 50 at a position where the molding surface 15 of the upper mold 10 and the molding material 50 are kept in non-contact. The temperature is raised to a suitable temperature.

At this time, for example, the first heating chamber P2 maintains a high temperature equal to or higher than the pressing temperature of the molding material 50, and rapidly heats the contained molding material 50 together with the molding die. And the shaping | molding die in which the shaping | molding raw material 50 was accommodated is stopped for a predetermined time in the 1st heating chamber P2, and is transferred to the 2nd heating chamber P3 according to rotation of a turntable. Due to the heating in the second heating chamber P3, the mold and the molding material 50 are further heated and soaked to approach the press temperature. Next, the molding die and the molding material 50 are soaked in the third heating chamber P4 so that the viscosity of the molding material 50 is 10 ⁶ to 10 ⁹ dPa · s suitable for press molding. The temperature is set so that the viscosity is 10 ⁶ to 10 ⁸ dPa · s.
In addition, there is no restriction | limiting in particular in the heating means with which the heating chambers P2-P4 are equipped. For example, a heater by resistance heating, a high frequency induction coil, or the like can be used.

  During the heating process, the molding die is kept stationary in the first heating chamber P2, and the molding material 50 is molded even when the molding material 50 is shifted from the center position of the molding surface 24 of the lower mold 20. It moves to the center position of the surface 24 by its own weight. Then, the surface of the molding material 50 is gradually heated in that state, and the molding material 50 whose surface is softened is prevented from rolling and sliding on the molding surface 24 of the lower mold 20, While being placed at the center position of the molding surface 24, it is transferred to the next processing chamber.

  As described above, in the present embodiment, when the molding material 50 is supplied onto the molding surface 24 of the lower mold 20 or when the molding material 50 is moved thereafter, the molding material 50 is positioned at the center position of the molding surface 24. It is preferable that the movement of the molding material 50 is suppressed by heating the molding die and the molding material 50 in this state and softening the surface of the molding material 50. However, when the molding material 50 settles at the center position of the molding surface 24, the holding of the upper mold 10 may be released and heating may be started.

Steps (4) to (5): Pressing Step The mold that has reached an appropriate temperature is transferred to the press chamber P5 (see FIG. 4 (4)).
In the press chamber P5, a press load is applied to the mold by a press head 90 from above the mold at a predetermined pressure (for example, 30 to 200 kgf) and a predetermined time (for example, several tens of seconds) (FIG. 4 (5)). reference).

At this time, the upper mold 10 slides with respect to the trunk mold 30 against the elastic force of the spring 40, and the molding surface 14 of the upper mold 10 and the molding surface 24 of the lower mold 20 come close to each other. The material 50 is press-molded, and the shapes of the molding surfaces 14 and 24 of the upper and lower molds 10 and 20 are transferred.
Then, when the lower surface of the press head 90 comes into contact with the upper surface of the body mold 30 and the upper surface of the body mold 30 and the upper surface of the upper mold 10 are flush with each other, the thickness of the molded body 51 is defined. Then, the press head 90 is raised to release the press load, thereby completing the press process.

Step (9): Cooling Step The forming die that has finished the pressing step is subjected to cooling treatment. First, the forming die is sequentially transferred to the first annealing chamber P6 and the second annealing chamber P7, and at least the molding material 50 is transferred. Cool to a temperature lower than the glass transition point of the (molded body 51).
Next, the mold is transferred to the quenching chamber P8 and the cooling process is continued. In the quenching chamber P8, quenching can be performed with a cooling gas until the molded body 51 reaches a temperature that does not hinder the opening to the atmosphere. Cooling.

Steps (7) to (8): Mold Decomposition Step / Mold Body Removal Step When the cooling step is completed and the molding die returns to the take-out / insertion chamber P1, the molding die is removed from the support portion 75. And transferred to the mounting table 70. Then, the position of the trunk mold 30 is fixed by the holding means 80, the mounting table 70 is vertically lowered, and the lower mold 20 is extracted from the trunk mold 30. Next, the molded body 51 is taken out from the molding surface 24 of the lower mold 20.
In this way, the molded body 51 taken out from the mold is subjected to centering as necessary, in order to make the outer diameter center of the optical element coincide with the optical center, and the desired optical It can be set as an element.

  After these steps (1) to (8) are completed, the process can be continuously performed by returning to the step (1) and repeating the above cycle.

According to the present embodiment as described above, an optical element with high shape accuracy can be stably formed by press molding using a mold that can be transferred to a processing chamber that performs processing necessary for press molding such as heating, pressing, and cooling. And can be molded.
In particular, when press molding is performed while the molding die is transferred to each processing chamber such as a heating chamber, a press chamber, and a cooling chamber, the heat history applied to the molding material 50 is extremely stable and excellent in terms of energy efficiency. However, in such a case, conventionally, the molding material 50 is supplied into the molding die before being softened, and is transferred after the molding die is assembled. Therefore, the position of the molding material 50 in the assembled molding die. The possibility of a shift could not be excluded.

  In the present embodiment, when the molding material 50 has a high viscosity, that is, when the rolling movement and the sliding movement can be easily performed, the molding material 50 is allowed to move to the center position of the molding surface 24 of the lower mold 20 by its own weight. And if a viscosity falls by heating after that, the movement of the shaping | molding raw material 50 will be suppressed. Therefore, when press molding is performed, the molding material 50 is disposed at the center position of the molding surface 24 of the lower mold 20, so that uneven thickness during press molding can be prevented.

  As described above, in the present embodiment, even if the molding material 50 is deviated from the center position of the molding surface 24 of the lower mold 20 due to vibration due to conveyance of the molding die, the molding material 50 is Since it can move to the center position of the molding surface 24 of the lower mold 20 by its own weight, it can be particularly preferably carried out in the above-mentioned molding die transfer type molding apparatus.

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

[Example]
A molding material made of borate optical glass is placed inside the molding die shown in FIG. 1, and the press temperature is set to 620 ° C. by the molding device of FIG. 2 while the upper molding surface and the molding material are kept in non-contact. 100 lenses were molded for each of the following preform A and preform B with a press load of 80 kgf. The obtained lens is a biconvex lens (with a recess at the center of the first surface) having an outer diameter of 8 mm and a flat thickness of the outer edge of 1 mm, and the upper mold forming surface forms the lens first surface. The molding surface and the lower mold molding surface were surfaces forming the second lens surface.

  Preform A: Dropped from a molten state onto a receiving mold and preformed into a spherical shape in a substantially floating state (difference in major and minor diameters is 20 μm or less).

  Preform B: A glass lump that has been dripped from a molten state onto a receiving mold and preformed in a substantially floating state and polished into a spherical shape by a polishing machine to increase the sphericity (long and short diameter difference is 5 μm or less) .

  Yield Evaluation Criteria: Yield rate was determined with the outer circumference having a predetermined outer diameter of 360 degrees as a non-defective product and the other as a defective product. Table 1 shows the results.

[Comparative example]
From the mold shown in FIG. 1, 100 lenses for Preform A were obtained in the same manner as in Example except that the spring was removed. About the obtained lens, the yield rate was calculated | required similarly to the Example, and the result was combined with Table 1 and shown.

  As described above, this example was advantageous in the accuracy of the outer peripheral yield. Furthermore, when a molding material subjected to polishing to increase the sphericity was used, a significant improvement in the yield rate was recognized.

  While the present invention has been described with reference to the preferred embodiment, it is needless to say that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. .

  For example, in the above-described embodiment, the molding die is not a molding die that is integrally fixed to the molding apparatus, but a molding die that can be disposed in a processing chamber that performs necessary processing by transfer. Even if the mold is transported alone, it may be transported in a state where it is connected to a transport arm of the mold, or the like as long as it can move other than the press operation.

  In addition, the “transfer” in the present invention is not limited to the case where the mold is sequentially transferred to a plurality of processing chambers as in the above-described embodiment. For example, the molding apparatus performs heating, pressing, and cooling at the same position. On the other hand, the case where the shaping | molding die which accommodated the shaping | molding raw material 50 is carried in or arrange | positioned shall be included. In these cases, it goes without saying that the effects of the present invention can be obtained.

  Moreover, there is no restriction | limiting in particular in the optical element shape | molded by this invention. However, as the shape, for example, when one of the two surfaces is a concave surface, or a convex surface having a concave portion, or a flat surface (upper mold side), the other is a convex surface with a loose curvature (large curvature radius). At certain (lower mold side), it has a remarkable effect. In particular, it is advantageous for forming a concave meniscus lens. In addition, the present invention has a remarkable effect in that the centering process is not performed after molding, and the shape of the molded body is substantially the final shape of the optical element as it is.

  Moreover, there is no restriction | limiting in particular also in the use of the optical element of this invention. However, it is useful for small imaging devices, objective lenses for optical pickups, collimator lenses, communication lenses, and the like. Many of these lenses achieve mounting accuracy using a flat transfer surface formed by press molding on the outer peripheral surface of the lens or the optical functional surface of the lens as a reference surface. Furthermore, it is particularly advantageous because it can prevent the occurrence of shape defects. If positioning with the lens barrel etc. can be performed accurately by the outer peripheral surface, the optical axis shift (shift) of the lens with other parts can be suppressed, and if a flat surface outside the optical function surface can be secured sufficiently, The optical axis tilt (tilt) can be suppressed.

  The present invention is applied to a mold press mold for molding an optical element such as a glass lens and a method for manufacturing the optical element.

1 is a schematic cross-sectional view showing an embodiment of a mold press mold according to the present invention. It is a schematic plan view which shows an example of the mold press molding apparatus suitable for enforcing the manufacturing method of the optical element which concerns on this invention. It is explanatory drawing which shows process (1)-(3) in embodiment of the manufacturing method of the optical element which concerns on this invention. It is explanatory drawing which shows process (4), (5) in one Embodiment of the manufacturing method of the optical element which concerns on this invention. It is explanatory drawing which shows a prior art example.

Explanation of symbols

10 upper mold 14 molding surface 20 lower mold 24 molding surface 30 barrel mold 40 upper mold holding means 50 molding material 51 molded body

Claims (12)

A mold press mold comprising an upper mold and a lower mold having molding surfaces facing each other, which is transferred to a processing chamber where processing necessary for press molding is performed and press-molds a molding material softened by heating. ,
The molding surface of the lower mold has a concave surface at least in the center position,
When the upper mold is held so that the molding surface of the upper mold does not come into contact with the molding material supplied on the molding surface of the lower mold and a press load is applied, the molding surface of the upper mold A mold press mold comprising an upper mold holding means for allowing contact with the molding material.   2. The mold press mold according to claim 1, wherein the upper mold holding means is formed using an elastic member. While comprising a barrel mold that regulates the mutual position in the direction perpendicular to the central axis of the upper mold and the lower mold,
The mold press mold according to claim 2, wherein the upper mold is slidable with respect to the barrel mold against the elastic force of the upper mold holding means.   The mold press mold according to claim 1, wherein the upper mold surface has a convex surface. A method of manufacturing an optical element that press-molds a molding material softened by heating using a molding die having an upper die and a lower die having molding surfaces facing each other,
Supplying the molding material onto the molding surface of the lower mold having a concave surface;
The upper mold is held on the molding material so that the molding surface of the upper mold does not come into contact with the molding material, and the molding material is allowed to move to the center position of the molding surface of the lower mold. The mold is transferred to a processing chamber for performing processing necessary for press molding,
A method for manufacturing an optical element, wherein press molding is performed by applying a press load in a state where the molding material is softened by heating to bring the upper mold and the lower mold close to each other.   6. The molding material is heated together with the molding die in a state where the upper die is held on the molding material so that the molding surface of the upper die does not come into contact with the molding material. Of manufacturing the optical element.   The method for manufacturing an optical element according to claim 5, wherein the upper mold is held on the molding material by upper mold holding means formed using an elastic member.   The optical element manufacturing method according to claim 7, wherein when the press load is applied to the mold, the upper mold and the lower mold are brought close to each other against an elastic force of the upper mold holding means. Method.   The molding die supplied with the molding material is sequentially transferred to a plurality of processing chambers including a heating chamber, a press chamber, and a cooling chamber, and the processing necessary for press molding is performed in each processing chamber. The manufacturing method of the optical element of any one of Claims 5-8.   The method for manufacturing an optical element according to claim 5, wherein the surface of the molding material is a convex curved surface.   The method of manufacturing an optical element according to claim 5, wherein the molding surface of the upper mold has a convex surface.   The concave meniscus lens manufactured by the manufacturing method of the optical element of any one of Claims 5-11.

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