Optical element molding method and optical element molding die

Abstract

A method for forming an optical element that comprises: an assembly step for inserting neck parts, which are provided in an upper mold and a lower mold respectively, into a hole provided in a side mold; a gas replacement step for replacing the atmosphere in the hole of the side mold with an inert gas through a groove connecting the upper or lower end surface of the side mold and the hole of the side mold; a heating step for heating a material to be formed which is placed in the hole of the side mold; and a press forming step for relatively approaching the upper mold and the side mold to the lower mold to thereby press form the material to be formed.

Description

[Technical field]

[0001] The present invention relates to a method for molding an optical element and a mold for molding an optical element. [Background technology]

[0002] As one of the molding methods for optical elements such as glass lenses, a molding method is known in which a glass material (molding material) is heated and press-molded using a mold to transfer the shape of the mold to the glass material, as shown in Patent Document 1. In such a molding method for optical elements, in addition to the optically functional surfaces provided on the top and bottom surfaces of the optical element, the side surfaces are also molded at the same time, making it possible to reduce costs including post-processing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-292327 A Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, when press molding a glass material, in order to prevent oxidation of the mold and the glass material, it is necessary to evacuate oxygen from the molding surface of the mold and near the glass material and replace the atmosphere inside the mold with an inert gas.

[0005] For example, in Patent Document 1, the entire apparatus is placed under a nitrogen atmosphere beforehand, and then molten glass material is dropped onto the lower molding surface, and the upper and side molds are lowered together relative to the lower mold, thereby press-molding the glass material inside the side mold. However, when the entire apparatus is placed under a nitrogen atmosphere beforehand, there is a problem in that the configuration of the molding apparatus becomes complicated.

[0006] Another common configuration different from that of Patent Document 1 is to insert the lower die into the side die in advance, and with the upper die removed from the side die, exhaust the oxygen inside the side die and replace it with inert gas. However, in this case, it is necessary to exhaust the oxygen while keeping the upper die floating above the side die, and it is necessary to provide a separate drive mechanism for the upper die in the molding device, or to provide separate mechanisms for driving the side die and the lower die relative to the upper die.

[0007] The present invention has been made in consideration of the above, and has an object to provide a method for molding optical elements and a mold for molding optical elements that is capable of molding the optical functional surface and side surfaces of an optical element together while preventing oxidation of the material and the mold with a simple configuration. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the molding method for optical elements of the present invention includes an assembly process of inserting neck portions provided on an upper mold and a lower mold, respectively, into holes provided in a side mold; a gas replacement process of replacing the atmosphere in the hole of the side mold with an inert gas through a groove portion that connects the upper or lower end surface of the side mold to the hole of the side mold; a heating process of heating a molding material placed in the hole of the side mold; and a press molding process of press-molding the molding material by bringing the upper mold, the side mold, and the lower mold relatively close to each other.

[0009] In addition, the method for molding an optical element according to the present invention, in the above invention, includes a removal step of removing the upper mold from the side mold and then raising the lower mold, thereby causing a part of the molded optical element to protrude from the upper end of the side mold, and removing the optical element.

[0010] In addition, in the molding method for an optical element according to the present invention, in the above invention, the opening of the groove portion on the inner surface of the hole portion is formed at a position different from a side molding surface provided on the inner surface of the hole portion for molding the side surface of the optical element.

[0011] In order to solve the above-mentioned problems and achieve the object, the optical element molding mold of the present invention comprises an upper mold and a lower mold each having a neck portion, and a side mold provided with a hole portion into which the neck portions of the upper mold and the lower mold are inserted, and a groove portion is formed between the upper end surface or the lower end surface of the side mold and the hole portion of the side mold for introducing an inert gas into the hole portion of the side mold.

[0012] In addition, in the optical element molding die of the present invention, in the above invention, the groove portion is provided in the hole portion of the side mold and is provided at a position that avoids the side molding surface for molding the side of the optical element.

[0013] In addition, in the optical element molding die of the present invention, in the above invention, the opening of the groove portion on the inner surface of the hole portion is formed at a position different from a side molding surface provided on the inner surface of the hole portion for molding the side surface of the optical element. Effect of the Invention

[0014] According to the optical element molding method and optical element molding die of the present invention, even when the neck of the upper die is inserted in advance into the hole of the side die, the atmosphere inside the die can be replaced with an inert gas through the groove provided in the side die. This makes it possible to mold the optical functional surface and the side of the optical element at the same time, with a simple configuration of only providing a groove in the side die, while exhausting oxygen from inside the die and replacing it with an inert gas. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of a main part of a molding apparatus equipped with an optical element molding die according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a configuration of an optical element molding die according to the embodiment of the present invention. [Diagram 3] FIG. 3 is a diagram showing a state of an optical element molding die during a press molding step in the optical element molding method according to the embodiment of the present invention. [Figure 4]FIG. 4 is a diagram showing a state of an optical element molding die during a press molding step in the optical element molding method according to the embodiment of the present invention. [Diagram 5] FIG. 5 is a diagram showing a state of the optical element molding die during the removal step in the optical element molding method according to the embodiment of the present invention. [Figure 6] FIG. 6 is a flow chart showing a method for molding an optical element using the optical element molding die according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the embodiments of the molding method for optical elements and the mold for molding optical elements according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments, and the components in the following embodiments include those that are replaceable and easy for a person skilled in the art, or those that are substantially the same.

[0017] [Molding equipment configuration] The molding device 1 molds an optical element (e.g., a glass lens) by press-molding a heat-softened molding material (e.g., a glass material) M. As shown in FIG. 1, the molding device 1 mainly includes a mold supply section 11, a gas replacement section 12, and a molding section 13.

[0018] In the mold supplying section 11, a mold supplying process is performed in which the mold 20 before molding is supplied to the molding apparatus 1, and a mold discharging process is performed in which the mold 20 after molding is discharged from the molding apparatus 1. The mold supplying section 11 is provided with a placement section 111 for placing the mold 20 transported by a transport mechanism (not shown).

[0019] In the gas replacement section 12, a gas replacement process is carried out in which oxygen inside the mold 20 is discharged and the atmosphere inside the mold 20 is replaced with an inert gas such as nitrogen. The gas replacement section 12 is provided with a placement section 121 for placing the mold 20 transported by a transport mechanism (not shown). Note that the "inside of the mold 20" specifically refers to the inside of the hole 231 of the side mold 23, and more specifically refers to the molding space consisting of the side molding surface formed by a part of the inner surface of the hole 231 of the side mold 23, the upper molding surface 212 of the upper mold 21, and the lower molding surface 222 of the lower mold 22 (see FIG. 2).

[0020] In the molding section 13, a heating process, a press molding process, and a cooling process are performed. In the molding section 13, an upper plate 131 and a lower plate 132 are provided for sandwiching and heating and pressing the die 20 transported by a transport mechanism (not shown). The upper plate 131 and the lower plate 132 are provided with a heating mechanism and a cooling mechanism (not shown), respectively. In addition, the lower plate 132 is provided with a pressing mechanism (pressing pin) 133 for pressing the lower die 22 in the press molding process.

[0021] [Mold configuration] The configuration of a mold (optical element molding mold) 20 according to an embodiment of the present invention will be described with reference to Figures 2 and 3. The mold 20 includes an upper mold 21, a lower mold 22, a side mold 23, a sleeve 24, and a spacer 25.

[0022] The upper die 21 has a cylindrical neck 211 extending toward the lower die 22. This neck 211 is the part of the upper die 21 that is inserted into the hole 231 of the side die 23. An upper molding surface 212 for molding the upper optically functional surface of the optical element is provided at the end of the neck 211.

[0023] The lower die 22 has a cylindrical neck portion 221 extending toward the upper die 21. This neck portion 221 is a portion of the lower die 22 that is inserted into a hole portion 231 of the side die 23. An end portion of the neck portion 221 is provided with a lower surface molding surface 222 for molding the lower optically functional surface of the optical element.

[0024] The side mold 23 is provided with a hole 231 that penetrates the side mold 23 from top to bottom. A part of the inner surface of this hole 231 constitutes a side molding surface for molding the side of the optical element. The upper mold 21 and the lower mold 22 are arranged at positions where their molding surfaces face each other with the side mold 23 in between. The upper mold 21, the lower mold 22 and the side mold 23 are also arranged inside the sleeve 24.

[0025] A tapered portion 232 is formed on the upper end surface of the side mold 23. This tapered portion 232 functions as a guide portion for facilitating insertion of the neck portion 211 of the upper mold 21 into the hole portion 231 of the side mold 23. In addition, a tapered portion 233 is formed on the lower end surface of the side mold 23. This tapered portion 233 functions as a guide portion for facilitating insertion of the neck portion 221 of the lower mold 22 into the hole portion 231 of the side mold 23.

[0026] A groove 234 is formed in the side mold 23. This groove 234 is for introducing an inert gas into the hole 231 of the side mold 23 in a gas replacement step in the molding method of an optical element, and is formed by, for example, electric discharge machining.

[0027] The groove 234 is provided between the lower end surface of the side mold 23 and the hole 231. That is, the groove 234 communicates with the lower end surface of the side mold 23 and the hole 231. One side of the groove 234 communicates with the tapered portion 233 on the lower side of the side mold 23. The other side of the groove 234 communicates with the hole 231 of the side mold 23. As a result, as shown by the dashed arrow A in FIG. 2, in the gas replacement step, the inert gas taken in from the vent hole 242 on the lower side of the sleeve 24 is introduced into the hole 231 of the side mold 23 through the groove 234, and the atmosphere in the hole 231 is replaced with the inert gas.

[0028] Moreover, groove 234 is provided at a position that avoids a side molding surface for molding the side surface of the optical element. That is, the opening (end) of groove 234 on the inner peripheral surface of hole 231 is formed at a position different from the side molding surface provided on the inner peripheral surface of hole 231.

[0029] Here, the side molding surface refers to a part of the inner surface of the hole 231 of the side mold 23. In the press molding process of the molding method of the optical element, as shown in Fig. 3, the lower mold 22 is brought close to the upper mold 21 and the side mold 23 to press mold the molding material M. The groove 234 is provided at a position on the inner surface of the hole 231 of the side mold 23 that does not come into contact with the molding material M during press molding. In this way, by providing the groove 234 at a position that does not come into contact with the molding material M during press molding, gas replacement can be performed without adversely affecting the subsequent press molding process.

[0030] The position of the groove 234 may be changed depending on the path for introducing the inert gas. For example, in FIG. 2, the groove 234 is provided between the lower end surface of the side mold 23 and the hole 231 in order to introduce the inert gas from the vent hole 242 on the lower side of the sleeve 24. On the other hand, when the inert gas is introduced from the vent hole 241 on the upper side of the sleeve 24, for example, it is desirable to provide the groove 234 between the upper end surface of the side mold 23 and the hole 231. In this way, by providing the groove 234 at a position according to the path for introducing the inert gas, gas replacement can be performed smoothly, for example, in the gas replacement step.

[0031] Further, the groove 234 may be provided at a plurality of positions in the side mold 23. For example, in Fig. 2, one groove 234 is provided on the left side of the hole 231 in the cross-sectional view, but a plurality of grooves 234 may be provided on the left side of the hole 231, or one or a plurality of grooves 234 may be provided on the right side of the hole 231. By providing a plurality of grooves 234 in the side mold 23, for example, the time required for gas replacement in the gas replacement step can be shortened.

[0032] The sleeve 24 is for accommodating the upper die 21, the lower die 22, and the side die 23 therein. The sleeve 24 is formed in a cylindrical shape. The sleeve 24 also has vent holes 241 and 242 that communicate between the inside and outside of the sleeve 24 and are used to introduce an inert gas into the die 20 in a gas replacement step of a molding method for optical elements, which will be described later.

[0033] The spacer 25 is for supporting the upper die 21 so that it does not fall when the die 20 is assembled before molding. In the die supplying step, the gas replacement step, and the heating step, each process is performed with the spacer 25 attached to the die 20, and in the steps after the heating step, each process is performed with the spacer 25 removed from the die 20.

[0034] [Mold assembly process] The assembly process of the mold 20 before molding will be described below. First, the lower die 22 and the side die 23 are assembled into the sleeve 24. Specifically, the side die 23 is placed on a step provided inside the sleeve 24, and the lower die 22 is placed so that the lower end surface of the lower die 22 is flush with the lower end surface of the sleeve 24. In addition, the neck portion 221 of the lower die 22 is inserted into the hole portion 231 of the side die 23.

[0035] Next, the molding material M is placed on the lower molding surface 222 of the lower mold 22. Although a spherical molding material M is illustrated in Fig. 2, the molding material M is not limited to a spherical shape, and may be, for example, a roughly spherical pellet shape, a lens shape that has been machined into an approximately spherical shape in advance, or the like.

[0036] Furthermore, the molding material M is processed to have a diameter smaller than the inner diameter of the hole 231 in order to enable press molding by the upper die 21 and the lower die 22 inside the hole 231 of the side die 23. As a result, when the molding material M is inserted into the hole 231, a predetermined gap is formed between the molding material M and a part of the inner surface of the hole 231 (side molding surface).

[0037] Next, the upper die 21 is fitted into the sleeve 24. Specifically, the upper die 21 is placed on the upper end surface of the sleeve 24, and the neck portion 211 of the upper die 21 is inserted into the hole portion 231 of the side die 23.

[0038] The length of the neck 221 of the lower die 22 is formed to be, for example, equal to or longer than the length of the hole 231 of the side die 23. Note that the above-mentioned "equal to" includes a state in which the length of the neck 221 of the lower die 22 is the same as the length of the hole 231 of the side die 23, a state in which the length of the neck 221 of the lower die 22 is slightly shorter than the length of the hole 231 of the side die 23, and a state in which the length of the neck 221 of the lower die 22 is slightly longer than the length of the hole 231 of the side die 23.

[0039] As a result, in a removal step of a molding method for optical elements, which will be described later, by raising the lower die 22 relative to the side die 23 with the upper die 21 removed (see FIG. 5), the position of the lower molding surface 222 rises to a position higher than the position of the lower molding surface 222 during press molding (see FIG. 4). Then, the end of the neck portion 221 of the lower die 22 rises to approximately the same height as the opening of the hole portion 231 in the side die 23, or to a position higher than the opening of the hole portion 231 in the side die 23.

[0040] [Optical element molding method] A method for molding an optical element using the mold 20 will be described below with reference to Fig. 1 to Fig. 6. In the method for molding an optical element according to this embodiment, necks 211, 221 provided on upper mold 21 and lower mold 22, respectively, are inserted into hole 231 provided in side mold 23, and then an optical element is molded from molding material M by upper molding surface 212 provided on upper mold 21, lower molding surface 222 provided on lower mold 22, and a side molding surface consisting of a part of the inner surface of hole 231 in side mold 23.

[0041] In the molding method for optical elements, a pre-molding die 20 (see FIG. 2) that has been assembled outside the molding apparatus 1 is supplied to the die supply section 11 of the molding apparatus 1, and then a gas replacement step is performed in the gas replacement section 12. Then, after a heating step, a press molding step, and a cooling step are performed in the molding section 13, the molded die 20 is discharged from the die supply section 11, and a removal step is performed outside the molding apparatus 1. Note that transportation between the die supply section 11, the gas replacement section 12, and the molding section 13 is performed by a transport mechanism (e.g., an arm) not shown. Specific contents of each step will be described below with reference to FIGS. 2 to 6.

[0042] (Gas replacement process) In the gas replacement process, the inside of the mold 20 transported to the gas replacement section 12 is filled with an inert gas such as nitrogen, and oxygen in the mold is discharged (see step S1 in FIG. 6). Specifically, in the gas replacement process, the atmosphere in the hole 231 of the side mold 23 is replaced with an inert gas through a groove 234 (groove 234 connecting the lower end surface of the side mold 23 and the hole 231) provided in the side mold 23. Note that in the gas replacement process, in order to ensure replacement with an inert gas, the atmosphere in the gas replacement section 12 may be depressurized by a vacuum pump (not shown) before replacement with an inert gas, and then the inert gas may be filled.

[0043] (Heating process) In the heating process, the mold 20 transported to the molding section 13 is sandwiched between an upper plate 131 and a lower plate 132, and the molding material M placed in the hole 231 of the side mold 23 is heated to a temperature above the yield point of the molding material M (see step S2 in Figure 6).

[0044] (Press molding process) In the press molding process, the upper die 21 and the side die 23 are brought relatively close to the lower die 22, thereby press-molding the molding material M (see step S3 in FIG. 6). Specifically, in the press molding process, as shown in FIGS. 3 and 4, the pressing mechanism 133 (see FIG. 1) of the molding device 1 is raised to raise the lower die 22 and the molding material M. As a result, inside the hole 231 of the side die 23, the upper and lower optical functional surfaces of the optical element O are transferred by the upper molding surface 212 and the lower molding surface 222, and the side surface of the optical element O is transferred by a part of the inner surface of the hole 231 (side molding surface).

[0045] Further, the groove 234 of the side die 23 is provided at a position that avoids the side molding surface, i.e., a part of the inner surface of the hole 231. Therefore, in the press molding process, the press molding is performed at a position above the groove 234 of the side die 23, as shown in Figs. 3 and 4.

[0046] (cooling process) In the cooling step, the mold 20 is gradually cooled to a temperature equal to or lower than the transition temperature of the molding material M, and then further cooled to room temperature (see step S4 in FIG. 6).

[0047] (Removal process) In the removal step, as shown in Fig. 5, after removing the upper die 21 from the side die 23, the lower die 22 is raised by the pressing mechanism 133 (see Fig. 1) to cause a part of the molded optical element O to protrude from the upper end of the side die 23, and the optical element O is removed (see step S5 in Fig. 6). In the removal step, as shown in the figure, the optical element O protruding from the upper end of the side die 23 is sucked by a suction tool or the like and removed.

[0048] According to the above-described optical element molding method and optical element molding die, even when the neck 211 of the upper die 21 and the neck 221 of the lower die 22 are inserted in advance into the hole 231 of the side die 23, the atmosphere inside the die 20 can be replaced with an inert gas through the groove 234 provided in the side die 23 as shown in Fig. 2. Moreover, according to the optical element molding method and optical element molding die, with a simple configuration in which the upper die 21 and the side die 23 are placed and fixed on the sleeve 24 and the lower die 22 is simply driven, the optical functional surface and the side of the optical element O can be molded collectively while discharging oxygen inside the die 20 and replacing it with an inert gas.

[0049] 4 and 5, in the optical element molding method and optical element molding die, even after press molding is completed, the lower molding surface 222 of the lower die 22 remains within the hole 231 of the side die 23, so the molded optical element O does not protrude or fall off from the lower molding surface 222. This effect can be obtained regardless of the thickness of the molded optical element O (even if the optical element O is thin).

[0050] Although the method for molding an optical element and the mold for molding an optical element according to the present invention have been specifically described above using the embodiments for carrying out the invention, the gist of the present invention is not limited to these descriptions and should be broadly interpreted based on the claims. Furthermore, it goes without saying that various changes and modifications based on these descriptions are also included in the gist of the present invention. [Explanation of symbols]

[0051] 1 Molding equipment 11 Mold Supply Department 12 Gas replacement section 13 Molding section 131 Upper Plate 132 Lower Plate 133 Pressing mechanism 20 Molds (molds for molding optical elements) 21 Upper mold 211 Neck 212 Top molding surface 22 Lower mold 221 Neck 222 Bottom molding surface 23 Side type 231 Hole 232,233 Tapered section 234 Groove 24 Sleeve 241,242 Ventilation holes 25 Spacer M Molding Material O Optical element

Claims

1. an assembly process in which neck portions provided on the upper and lower dies are inserted into holes provided on the side dies; a gas replacement step of replacing the atmosphere in the hole of the side mold with an inert gas through a groove portion that communicates with the upper end surface or the lower end surface of the side mold and the hole of the side mold; a heating step of heating the molding material placed in the hole of the side mold; a press molding process in which the upper mold and the side mold are brought relatively close to the lower mold, thereby press-molding the molding material; A method for molding an optical element comprising the steps of:

2. and a removal step of removing the optical element by lifting the lower die after removing the upper die from the side die, thereby causing a part of the molded optical element to protrude from an upper end of the side die. The method for molding an optical element according to claim 1 .

3. an opening of the groove in the inner circumferential surface of the hole is formed at a position different from a side molding surface that is provided in the inner circumferential surface of the hole and that is used to mold a side surface of the optical element; The method for molding an optical element according to claim 1 .

4. an upper mold and a lower mold each having a neck portion; a side mold having holes into which the neck portions of the upper mold and the lower mold are inserted; Equipped with A groove for introducing an inert gas into the hole of the side mold is formed between an upper end surface or a lower end surface of the side mold and the hole of the side mold. Mold for molding optical elements.

5. an opening of the groove in the inner circumferential surface of the hole is formed at a position different from a side molding surface that is provided in the inner circumferential surface of the hole and that is used to mold a side surface of the optical element; The optical element molding die according to claim 4 .

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