JP4951394B2 - Optical element molding method - Google Patents

Description

  The present invention relates to an optical element molding method for molding a molding material using a pair of molding dies and a molding apparatus therefor.

  2. Description of the Related Art Conventionally, a method for forming an optical element used in an optical apparatus with high accuracy with a single shot using a mold is known. In such a molding method, for example, as shown in Patent Document 1, when a preform having a concave molding surface and a spherical shape (molding material) is used, the effect is that the center of gravity of the preform naturally moves toward the center of the molding surface. It was positioned using.

On the other hand, for the convex molding surface shape where the center of gravity of the preform does not naturally go to the center, after placing the preform on the molding surface of the lower mold, the molding surface of the lower mold is placed using a positioning jig The preform was moved to the center of the head and the position was kept by the weight of the preform.
Japanese Patent Publication No. 6-24992

  However, in the method using the positioning jig, the preform may be displaced from the center of the mold before molding due to vibration or the like accompanying the movement of the mold during molding. In this case, the softened preform flows non-uniformly in the cavity and the required lens outer shape cannot be obtained. For this reason, the preform is carefully positioned so as not to be misaligned, or a preform larger than the target is used, and the excess portion of the lens is shaved after molding.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a method of molding an optical element and a molding apparatus thereof that can mold a molding material at the center of a molding die.

In order to achieve the object, the invention according to claim 1
In the molding method of the optical element that molds the molding material using a pair of molding dies arranged opposite to each other with the molding material sandwiched therebetween,
Place the molding material on the molding surface of one mold,
Before the molding material is softened, the positioning member is brought into contact with the molding material,
The positioning material is positioned by moving the molding material to the center of the pair of molds by its own weight ,
After the positioning member positions the molding material, the other molding die facing the one molding die moves to mold the molding material that has been softened by heating, and the positioning member is restricted from moving in the middle. It leaves | separates from the said shaping | molding raw material, It is characterized by the above-mentioned .

The invention according to claim 2 is the optical element molding method according to claim 1,
The positioning member has a cylindrical shape, and a peripheral portion on an inner diameter side thereof abuts on the molding material.

The invention according to claim 3 is the method for molding an optical element according to claim 1,
The positioning member has a cylindrical shape, a peripheral portion on an inner diameter side thereof is formed as a tapered portion, and the tapered portion is in contact with the molding material.

  According to the present invention, since the molding material can be molded at the center of the molding die, it is possible to prevent the occurrence of molding defects due to misalignment. In addition, since the molding material can be molded at the center of the molding die, the molded optical element does not suffer from defects such as insufficient outer shape. For this reason, the volume of the molding material can be set to the minimum.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Throughout the drawings, in the cross section of the mold set 20, only the positioning member 32 and the stopper member 34 are hatched, and other members are not hatched.
(First embodiment)
FIGS. 1A and 1B are diagrams showing an overall configuration of an optical element molding apparatus according to the present embodiment.

  The molding apparatus 10 includes an upper plate 12 and a lower plate 14 that are arranged to face each other with a mold set 20 interposed therebetween, and a pressure device (not shown) that presses the upper plate 12 toward the lower plate 14. . An upper cartridge heater 16 is built in the upper plate 12. A lower cartridge heater 18 is built in the lower plate 14.

The mold set 20 is heated, molded, and cooled while being sandwiched between the upper plate 12 and the lower plate 14.
The mold set 20 includes an upper mold 22 and a lower mold 24 that are arranged to face each other, and a cylindrical sleeve 26 into which the upper mold 22 and the lower mold 24 are inserted. As materials for the upper mold 22, the lower mold 24, and the sleeve 26, for example, an alloy such as tungsten carbide is used.

  The upper mold 22 has a molding shaft 22b that protrudes to the surface facing the lower mold 24, and a molding surface 22a is formed at the tip of the molding shaft 22b. The molding surface 22a has a convex shape on the opposite side. The lower mold 24 has a molding surface 24a. The molding surface 24a has a concave shape on the opposite side. For this reason, the optical element to be molded is a meniscus lens. The molding surface 22a and the molding surface 24a are spaced apart from each other. A molding material (preform) 30 is disposed between the molding surface 22a and the molding surface 24a.

In the present embodiment, a spherical glass preform is used as the molding material 30.
A cylindrical positioning member 32 with a flange is fitted to the molding shaft 22 b of the upper mold 22. As for this positioning member 32, the inner diameter part and the outer diameter part, and the collar part 32a are processed with high precision with respect to the shaft center. The outer diameter portion of the positioning member 32 is fitted with a stopper member 34 described later with high accuracy, and the flange portion 32a is fitted with the sleeve 26 with high accuracy. Furthermore, since the positioning member 32 has a cylindrical shape, the molding shaft 22b of the upper mold 22 can be easily fitted into the inner diameter portion thereof.

  Further, a cylindrical stopper member 34 is placed on the molding surface 24 a of the lower mold 24 inside the sleeve 26. The stopper member 34 has a lower end surface placed around the molding surface 24 a of the lower mold 24, and an upper end surface of the stopper member 34 abutted with the flange portion 32 a of the positioning member 32.

  In the present embodiment, the stopper member 34 has a cylindrical shape, but the shape is not limited thereto. Further, in this embodiment, the positioning member 32 and the stopper member 34 are formed separately, but they may be formed integrally.

  In order to assemble the mold set 20, as shown in FIG. 1A, the molding material 30 is placed on the molding surface 24 a of the lower mold 24, and then the sleeve 26 is fitted into the lower mold 24. Next, a cylindrical stopper member 34 is disposed around the molding surface 24 a of the lower mold 24 inside the sleeve 26. Further, the positioning member 32 is fitted inside the sleeve 26 and on the inner peripheral side of the stopper member 34.

  In this case, as for the positioning member 32, the peripheral edge part 32b of the inner diameter side is brought into contact with the upper part of the molding material 30 by its own weight. Further, the positioning member 32 does not move in the diameter direction of the stopper member 34. Thereby, the molding material 30 moves to the center side of the molding surface 24a of the lower mold 24 so that the contact pressure with the peripheral edge portion 32b on the inner diameter side of the positioning member 32 becomes equal. In this way, natural center positioning of the molding material 30 is performed.

  Next, with the center of the molding material 30 being positioned, the upper mold 22 is fitted into the sleeve 26, and the molding shaft 22 b of the upper mold 22 is fitted into the inner diameter side of the cylindrical positioning member 32. Thus, the assembly of the mold set 20 is completed. In addition, these procedures show an example and the order is not restricted to this.

Next, in order to mold using the mold set 20, the molding material 30 is heated to the softening temperature.
In this case, the upper cartridge heater 16 and the lower cartridge heater 18 are energized to heat and soften the molding material 30. During this time, the positioning member 32 presses the molding material 30 by its own weight. For this reason, as described above, the positioning member 32 is in a state in which the peripheral portion 32b on the inner diameter side abuts on the molding material 30 and the molding material 30 is positioned at the center. Next, as shown in FIG. 1B, the upper die 22 is moved so as to approach the lower die 24 by a pressurizing device (not shown). The positioning member 32 also moves in the direction approaching the lower mold 24 by its own weight in conjunction with the thickness reduction of the molding material 30 due to the movement of the upper mold 22. Eventually, the collar portion 32 a comes into contact with the upper end surface of the stopper member 34. Therefore, the positioning member 32 does not move downward any more. That is, the positioning member 32 abuts on the upper end surface of the stopper member 34 during the movement, and does not abut on the molding material 30 thereafter.

  Although not shown, a scale for measuring the amount of movement of the upper mold 22 is provided, and the movement of the upper mold 22 is controlled by the measured value. Thus, the molding surface 22 a of the upper mold 22 and the molding surface 24 a of the lower mold 24 are transferred to the molding material 30. Thereby, the optical element (meniscus lens) 31 as a product is obtained.

  In the present embodiment, a gap is generated between the upper mold 22 and the positioning member 32 at the end of molding. Therefore, the molding surface 22a of the upper mold 22 presses the molding material 30, and the optical element 31 is molded. Further, there is no member that presses the molding material 30 around the molding surface 22 a of the upper mold 22. For this reason, a part of the softened molding material 30 does not enter the gap between the mold members, and no burrs are generated in the molded optical element 31.

  When molding is completed, the mold set 20 is cooled, the assembled mold set 20 is removed, and the optical element 31 is taken out. In addition, the removal order of the mold set 20 is performed, for example, by a procedure reverse to the order of assembly described above.

According to the present embodiment, since the molding material 30 can be positioned at the center of the molding die and molded in that state, the molded optical element 31 is not displaced. For this reason, the molded optical element 31 does not have a defect of insufficient outer diameter due to positional deviation. Further, since the molding material 30 can be molded at the center of the molding die, the volume of the molding material 30 can be minimized. Therefore, it is economical.
(Modification)
2A and 2B show a modification of the first embodiment. Note that the upper plate 12 and the lower plate 14 shown in the first embodiment are not shown. Further, the same or corresponding members as those in the first embodiment will be described with the same reference numerals.

  In the first embodiment, the flange portion 32 a of the positioning member 32 is in contact with the upper end surface of the stopper member 34 during the molding. However, in this modification, the lower surface 32c of the positioning member 32 is in contact with the upper end surface of the stopper member 34 during the molding.

  That is, as shown in FIG. 2A, when the mold set 20 is assembled, after the molding material 30 is placed on the molding surface 24a of the lower mold 24, the sleeve 26 is fitted and the stopper member is placed inside the sleeve 26. 34 is arranged. Further, the positioning member 32 is fitted on the inner peripheral side of the sleeve 26 above the stopper member 34.

  In this case, as for the positioning member 32, the peripheral edge part 32b of the inner diameter side is brought into contact with the upper part of the molding material 30 by its own weight. As a result, the molding material 30 moves to the center of the molding surface 24a of the lower mold 24 so as to evenly contact the peripheral portion 32b on the inner diameter side of the positioning member 32 in the same manner as described above. Thus, the centering of the molding material 30 is performed.

  In this state, the lower surface 32 c of the positioning member 32 is not in contact with the stopper member 34. Next, the molding shaft 22 b of the upper mold 22 is fitted inside the sleeve 26 and on the inner diameter side of the cylindrical positioning member 32. Thus, the assembly of the mold set 20 is completed.

  Next, as shown in FIG. 2B, when the molding material 30 is heated and softened, the upper die 22 is moved closer to the lower die 24 by a pressurizing device (not shown). In conjunction with the thickness reduction of the molding material 30 due to the movement of the upper mold 22, the positioning member 32 also moves in a direction approaching the lower mold 24 by its own weight. Eventually, the lower surface 32c of the positioning member 32 comes into contact with the stopper member 34 and stops. Further, by moving the upper mold 22 so as to approach the lower mold 24, the molding surface 22 a of the upper mold 22 and the molding surface 24 a of the lower mold 24 are transferred to the molding material 30.

  At this time, the outer peripheral portion of the softened molding material 30 is in contact with the inner peripheral surface of the stopper member 34. For this reason, the outer peripheral portion of the molding material 30 is molded by the stopper member 34. There is no member in contact with the upper surface of the molding material 30.

According to this modification, the portion excluding the upper surface of the molding material 30 is molded by the mold member. For this reason, since the molding material 30 does not have a regulating member at the upper side, it is possible to obtain an optical element 31 close to the final shape without generation of burrs. For this reason, it is possible to reduce the work of scraping off the surplus portion in the optical element 31, and further, the work of removing the burrs after molding becomes unnecessary.
(Second Embodiment)
3A and 3B show the overall configuration of the molding apparatus according to the second embodiment. Note that the upper plate 12 and the lower plate 14 shown in the first embodiment are not shown. Further, the same or corresponding members as those in the first embodiment will be described with the same reference numerals.

  In the present embodiment, the length of the stopper member 34 is shortened as compared with the first embodiment. For this reason, the movement restriction | limiting of the positioning member 32 is lose | eliminated. Further, the lower surface of the positioning member 32 forms a molding surface for molding the molding material 30 together with the molding surface 22 a of the upper mold 22.

  As shown in FIG. 3A, when the mold set 20 is assembled, after the molding material 30 is placed on the molding surface 24a of the lower mold 24 in the same manner as described above, the sleeve 26 is inserted and the sleeve 26 is inserted. A stopper member 34 is disposed inside. Further, the positioning member 32 is fitted on the inner peripheral side of the stopper member 34. In this case, as for the positioning member 32, the peripheral edge part 32b of the inner diameter side is brought into contact with the upper part of the molding material 30 by its own weight.

  As a result, the molding material 30 moves to the center side of the molding surface 24a of the lower mold 24 so as to evenly contact the peripheral edge portion 32b on the inner diameter side of the positioning member 32. Thus, the centering of the molding material 30 is performed.

  Next, with the center positioning of the molding material 30 performed, the upper mold 22 is fitted into the sleeve 26, and the molding shaft 22 b of the upper mold 22 is fitted into the inner diameter side of the cylindrical positioning member 32. Thus, the assembly of the mold set 20 is completed.

Next, in order to mold using the mold set 20, the molding material 30 is heated to the softening temperature.
That is, the upper cartridge heater 16 and the lower cartridge heater 18 are energized to heat and soften the molding material 30. Next, as shown in FIG. 3 (B), the upper die 22 moves so as to approach the lower die 24 by a pressurizing device (not shown). In conjunction with the decrease in the thickness of the molding material 30 due to the movement of the upper mold 22, the positioning member 32 moves in a state where the peripheral edge portion 32 b is uniformly in contact with the molding material 30 by its own weight.

  When the upper mold 22 is further moved, the collar portion 32a comes into contact with the upper mold 22 during the movement, and thereafter, the upper mold 22 and the positioning member 32 are integrally lowered. The upper mold 22 is provided with a scale (not shown) for measuring the amount of movement, and the movement of the upper mold 22 is controlled by the measured value so that the molding material 30 is pressed to a desired thickness. Stop. At the same time, the lower surface 32 c of the positioning member 32 is brought into contact with the upper surface around the molding material 30 to mold the molding material 30.

  Thus, the molding surface 24 a of the lower mold 24, the molding surface 22 a of the upper mold 22, the lower surface 32 c of the positioning member 32, and the inner peripheral surface of the stopper member 34 press the entire surface of the molding material 30. Then, these molding surfaces are transferred to the molding material 30. Thereby, the optical element (meniscus lens) 31 as a product is obtained.

  In a state where the molding is completed, the upper surface of the positioning member 32 is in contact with the upper mold 22, and a predetermined gap is formed between the flange portion 32 a of the positioning member 32 and the stopper member 34.

According to this embodiment, all surfaces including the outer peripheral portion and the upper surface of the optical element 31 can be molded. Thereby, the optical element 31 close to the final shape of interest can be obtained. Therefore, the shaving amount of the molded optical element 31 can be small.
(Third embodiment)
4 (A) and 4 (B) show the overall configuration of the molding apparatus according to the third embodiment. Note that the upper plate 12 and the lower plate 14 shown in the first embodiment are not shown. Further, the same or corresponding members as those in the first embodiment will be described with the same reference numerals.

  In the present embodiment, the shape of the positioning member 32 is different from that in the first embodiment. That is, the inner diameter side of the positioning member 32 is formed in the tapered portion 32d. Further, the shape of the molding material 30 is different from the shape of the molding surface 24 a of the lower mold 24.

  That is, the molding surface 22a of the upper mold 22 has a convex shape on the opposite side, and the molding surface 24a of the lower mold 24 has a convex shape on the opposite side. For this reason, the optical element to be molded is a biconcave lens. The molding surface 22a and the molding surface 24a are spaced apart from each other. And the molding raw material 30 is arrange | positioned between the molding surface 22a and the molding surface 24a.

The molding material 30 is a columnar glass preform. Cylindrical glass preforms are frequently used mainly because of their low cost.
In order to assemble the mold set 20, as shown in FIG. 4A, after the molding material 30 is placed on the molding surface 24 a of the lower mold 24, the sleeve 26 is fitted and the stopper member 34 is inserted inside the sleeve 26. Place. Further, the positioning member 32 is inserted into the inner peripheral side of the stopper member 34.

  In this case, the positioning member 32 has a taper portion 32 d on its inner diameter side abutted on the upper portion of the molding material 30 by its own weight. For this reason, the molding material 30 moves to the center side of the molding surface 24a of the lower mold 24 so that the edge portion thereof is evenly in contact with the inclined surface of the tapered portion 32d on the inner diameter side of the positioning member 32.

  Next, with the center of the molding material 30 being positioned, the upper mold 22 is inserted into the sleeve 26, and the molding shaft 22 b of the upper mold 22 is inserted into the inner diameter side of the cylindrical positioning member 32. Thus, the positioning of the molding material 30 is performed, and the assembly is completed.

Next, in order to mold using the mold set 20, the molding material 30 is heated to the softening temperature.
That is, the upper cartridge heater 16 and the lower cartridge heater 18 are energized to heat and soften the molding material 30. Next, as shown in FIG. 4B, the upper die 22 is moved so as to approach the lower die 24 by a pressurizing device (not shown). At this time, the positioning member 32 moves in a state in which the inclined surface of the tapered portion 32 d is in contact with the molding material 30 by its own weight in conjunction with the thickness reduction of the molding material 30 due to the movement of the upper mold 22.

When the upper die 22 further moves, the positioning member 32 has the flange portion 32 a abutting against the upper end surface of the stopper member 34. Therefore, the positioning member 32 does not move downward any more.
That is, the positioning member 32 is lowered for a while from the start of molding, but abuts against the stopper member 34 while moving, and does not contact the molding material 30 thereafter.

The upper mold 22 is provided with a scale (not shown) for measuring the movement amount, and the movement of the upper mold 22 is controlled by the measured value.
Due to the movement of the upper mold 22, the molding surface 22 a of the upper mold 22 presses the molding material 30 to the center thickness thereof and stops. Thus, the molding material 30 is molded by the molding surface 22a of the upper mold 22 and the molding surface 24a of the lower mold 24. The tapered portion 32 d of the positioning member 32 is not in contact with the molding material 30.

  Thus, the molding surface 24a of the lower mold 24 and the molding surface 22a of the upper mold 22 are transferred to the molding material 30, and an optical element (concave lens) 31 as a product is obtained. Note that a gap is formed between the upper mold 22 and the positioning member 32 in a state where the molding is completed.

  According to the present embodiment, since the molding material 30 can be molded at the center of the molding die, no positional deviation occurs in the molded optical element 31. For this reason, the optical element 31 does not have a defect of insufficient outer diameter due to the positional deviation. Moreover, since the upper and lower molding surfaces 22a and 24a are transferred to the molding material 30, no burr is generated in the obtained optical element 31. Furthermore, since the inner diameter side of the positioning member 32 is formed in the tapered portion 32d, it is effective for centering when the molding material 30 is cylindrical.

It is a figure which shows the whole structure of the shaping | molding apparatus in 1st Embodiment. It is a figure which shows the modification of 1st Embodiment. It is a figure which shows the whole structure of the shaping | molding apparatus in 2nd Embodiment. It is a figure which shows the whole structure of the shaping | molding apparatus in 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Molding apparatus 12 Upper plate 14 Lower plate 16 Upper cartridge heater 18 Lower cartridge heater 20 Mold set 22 Upper mold 22a Molding surface 22b Molding shaft 24 Lower mold 24a Molding surface 26 Sleeve 30 Molding material 31 Optical element 32 Positioning member 32a Part 32b peripheral edge part 32c lower surface 32d taper part 34 stopper member

Claims (3)

In the molding method of the optical element that molds the molding material using a pair of molding dies arranged opposite to each other with the molding material sandwiched therebetween,
Place the molding material on the molding surface of one mold,
Before the molding material is softened, the positioning member is brought into contact with the molding material,
The positioning material is positioned by moving the molding material to the center of the pair of molds by its own weight ,
After the positioning member positions the molding material, the other molding die facing the one molding die moves to mold the molding material that has been softened by heating, and the positioning member is restricted from moving in the middle. A method for molding an optical element, which is separated from the molding material . The method for molding an optical element according to claim 1, wherein the positioning member has a cylindrical shape, and a peripheral portion on an inner diameter side thereof abuts on the molding material. The optical element molding method according to claim 1, wherein the positioning member has a cylindrical shape, a peripheral edge portion on an inner diameter side thereof is formed as a tapered portion, and the tapered portion abuts on the molding material.

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