JP2021066639A - Molding die, and method for manufacturing optical element - Google Patents

Abstract

To provide a technique capable of suppressing the inclination eccentricity of an optical element being a molding.SOLUTION: The molding die comprises: a cylindrical barrel die; an upper die for pressing the material of an optical element from above in the inside of the barrel die; a spacer arranged above the upper die; and a lower die for pressing the material from below in the inside of the barrel die. The barrel die includes a vertical sleeve for storing the material; the upper die includes an upper shaft inserted into the sleeve of the barrel die; and the lower die includes a lower shaft inserted into the sleeve of the barrel die. The upper surface of the spacer having a curved surface convex upward has the highest point in height on the vertical center line of the upper shaft, and the lower surface of the spacer having a curved surface convex downward has the lowest point in height on the vertical center line of the upper shaft.SELECTED DRAWING: Figure 3A

Description

The present disclosure relates to a molding die and a method for manufacturing an optical element.

The molding die described in Patent Document 1 press-molds an optical element such as a glass lens. The molding die has an upper die, a lower die, an inner body, an outer body, and a coil spring. The upper mold forms the upper surface of the optical element. The lower mold forms the lower surface of the optical element. The inner body is formed in a cylindrical shape. An upper mold and a lower mold are inserted into the inner body. The outer body is formed in a cylindrical shape and surrounds the inner body. The outer body regulates the distance between the upper and lower molds. The coil spring is arranged on the outside of the outer body and presses the flange of the inner body against the flange of the lower mold.

Japanese Unexamined Patent Publication No. 2011-184249

The molding die described in Patent Document 1 is arranged between the upper plate and the lower plate of the press molding machine. The mold contains the material of the optical element in advance. The mold is heated after accommodating the material M, pressed, and then cooled.

By the way, at the time of pressing, the upper plate is lowered and the upper mold is pushed down. At that time, the lower surface of the upper board sometimes warped due to heat or the like. When the lower surface of the upper plate is warped, unlike the case where the lower surface is not warped, the upper plate cannot make surface contact with the entire upper surface of the upper mold, and may make point contact with the edge of the upper surface of the upper mold. As a result, an eccentric load was applied to the upper mold, and the upper mold sometimes tilted. Therefore, the material cannot be compressed in a well-balanced manner, and the optical axis of the upper and lower surfaces of the optical element, which is a molded product, may be tilted to cause tilt eccentricity (tilt).

One aspect of the present disclosure provides a technique capable of suppressing the tilt eccentricity of an optical element which is a molded product.

The molding mold according to one aspect of the present disclosure includes a cylindrical body mold, an upper mold that presses the material of the optical element from above inside the body mold, a spacer arranged above the upper mold, and the above. It has a lower mold that presses the material from below inside the body mold. The barrel includes a vertical sleeve that houses the material. The upper die includes an upper shaft that is inserted into the sleeve of the body die. The lower mold includes a lower shaft that is inserted into the sleeve of the body mold. The upper surface of the spacer has an upwardly convex curved surface and has the highest point on the vertical center line of the upper shaft, or the lower surface of the spacer has a downwardly convex curved surface. , Has the lowest height point on the vertical centerline of the upper shaft.

According to one aspect of the present disclosure, it is possible to suppress the tilt eccentricity of the optical element which is a molded product.

FIG. 1 is a side view showing a press molding machine according to an embodiment. FIG. 2A is a cross-sectional view showing a molding die according to an embodiment, and is a cross-sectional view showing a state before the start of compression of the molding die. FIG. 2B is a cross-sectional view showing a state of the molding mold of FIG. 2A at the time of compression. FIG. 3A is an enlarged cross-sectional view showing a part of FIG. 2B. FIG. 3B is an enlarged cross-sectional view showing a part of the molding die according to the reference form. FIG. 4 is a top view showing a main part of the molding mold according to the embodiment. FIG. 5A is a cross-sectional view showing a molding die according to the first modification, and is a cross-sectional view showing a state before the start of compression of the molding die. FIG. 5B is a cross-sectional view showing a state of the molding mold of FIG. 5A at the time of compression. FIG. 6A is a cross-sectional view showing a molding die according to the second modification, and is a cross-sectional view showing a state before the start of compression of the molding die. FIG. 6B is a cross-sectional view showing a state of the molding mold of FIG. 6A at the time of compression.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding configurations may be designated by the same reference numerals and description thereof may be omitted. Further, in each drawing, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other, the X-axis direction and the Y-axis direction are the horizontal direction, and the Z-axis direction is the vertical direction.

As shown in FIG. 1, the press molding machine 100 has a plurality of processing units 110 and a transfer device 120 that conveys the molding die 1 to the plurality of processing units 110. The plurality of processing units 110 are arranged in the X-axis direction, and the transfer device 120 slides the molding die 1 in the X-axis direction. As shown in FIG. 2A and the like, the molding die 1 houses the material M for forming the optical element in advance. The optical element is, for example, a lens. The material M is, for example, glass.

After accommodating the material M, the molding die 1 is heated stepwise in the heating zone X1. After that, the molding die 1 is pressed in the press zone X2. The temperature of the material M at the time of pressing is, for example, equal to or higher than the yield point and lower than or lower than the softening point. The material M is plastically deformed into the shape of the optical element. After that, the mold 1 is cooled stepwise in the cooling zone X3. The material M is taken out from the molding die 1 after being cooled to a temperature equal to or lower than the strain point. As a result, an optical element can be obtained. Since the molding die 1 is heated, the periphery of the molding die 1 may be filled with an inert gas such as nitrogen gas so that the molding die 1 is not oxidized.

Each of the plurality of processing units 110 has an upper plate 111, a lower plate 112, and an elevating mechanism 113, respectively. The upper plate 111 can be raised and lowered above the lower plate 112. The lower board 112 is fixed. The molding die 1 is placed on the upper surface of the lower plate 112. The elevating mechanism 113 elevates and elevates the upper plate 111, and pushes the molding die 1 on the lower surface of the upper plate 111. The lower surface of the upper plate 111 and the upper surface of the lower plate 112 are horizontal.

The upper plate 111 has, for example, a temperature controller 114 and a heat soaking plate 115. The temperature controller 114 is arranged above the heat equalizing plate 115, and adjusts the temperature of the molding die 1 via the heat equalizing plate 115. The temperature of the molding die 1 gradually increases in the negative direction of the X-axis in the heating zone X1, becomes highest in the press zone X2, and gradually decreases in the negative direction of the X-axis in the cooling zone X3. Become. The temperature controller 114 is a heater or a cooler.

The lower plate 112 is configured in the same manner as the upper plate 111, and has, for example, a temperature controller 116 and a heat soaking plate 117. The temperature controller 116 is arranged below the heat equalizing plate 117, and adjusts the temperature of the molding die 1 via the heat equalizing plate 117. The temperature controller 116 is a heater or a cooler.

The elevating mechanism 113 is, for example, a pneumatic cylinder, a hydraulic cylinder, or an electric cylinder. The elevating mechanism 113 elevates and elevates the upper plate 111, and pushes the molding die 1 on the lower surface of the upper plate 111. The upper plate 111 and the molding die 1 are in contact with each other to efficiently transfer heat. In the heating zone X1, the upper plate 111 and the molding die 1 may come into contact with each other to transfer heat, and the molding die 1 may be hardly compressed. In the press zone X2, the molding die 1 is compressed so that the material M is plastically deformed into the shape of the optical element. In the cooling zone X3, the molding die is compressed so that the upper die follows the cooling shrinkage of the material M.

The press molding machine 100 shown in FIG. 1 is an example and is not particularly limited. For example, the arrangement position and number of X1, X2, and X3 can be appropriately changed depending on the molding conditions.

As shown in FIGS. 2A and 2B, the molding die 1 has a body die 2, an upper die 3, and a lower die 5. The body type 2 accommodates the material M. The upper mold 3 presses the material M from above inside the body mold 2. The lower mold 5 presses the material M from below inside the body mold 2. Since the body mold 2, the upper mold 3, and the lower mold 5 transfer their respective surface shapes to the material M, they are formed of a material having high hardness, for example, cemented carbide or silicon carbide.

As shown in FIG. 3A, the body type 2 has a vertical sleeve 21 for accommodating the material M. The body type 2 is cylindrical and has a through hole 22 that penetrates the sleeve 21 in the vertical direction. The sleeve 21 accommodates the material M inside the through hole 22, and transfers the shape of the inner peripheral surface thereof to the material M.

Further, the body type 2 has a flange 23 formed on the outer peripheral surface of the sleeve 21. The flange 23 is formed, for example, at the lower end of the sleeve 21. Although the flange 23 is formed at the lower end of the sleeve 21 in this embodiment, it may be formed in the middle of the sleeve 21. When the flange 23 is formed in the middle of the sleeve 21, a ring protruding upward from the peripheral edge of the flange 53 is formed, and the ring supports the flange 23. However, the flange 23 is preferably formed at the lower end of the sleeve 21 in order to increase the contact area between the horizontal planes with the flange 53. The wider the contact area between the horizontal planes of the flange 23 and the flange 53, the more the inclination of the lower mold 5 can be suppressed.

The upper die 3 has an upper shaft 31 that is inserted into the sleeve 21 of the body die 2. The upper shaft 31 presses the material M on its lower surface and transfers the shape of the lower surface to the material M. The outer peripheral surface of the upper shaft 31 slidably contacts the inner peripheral surface of the sleeve 21, and the center line Z1 of the upper shaft 31 and the center line Z0 of the sleeve 21 coincide with each other.

Further, the upper mold 3 has a flange 33 formed on the outer peripheral surface of the upper shaft 31. The flange 33 is formed at the upper end of the upper shaft 31 and is arranged horizontally. A spacer 4, which will be described later, is placed on the flange 33. The upper plate 111 of the press molding machine 100 pushes the upper mold 3 via the spacer 4.

The spacer 4 is arranged above the upper mold 3. Since the spacer 4 transmits the load of the press molding machine 100 to the upper mold 3, it is formed of a material having high hardness, for example, cemented carbide or silicon carbide. The spacer 4 may be formed integrally with the upper mold 3, but in the present embodiment, the spacer 4 is formed separately from the upper mold 3 and is separably placed on the upper mold 3.

The thickness of the optical element, which is a molded product, can be adjusted by adjusting the thickness of the spacer 4. For example, the thickness of the optical element can be adjusted by grinding the lower surface of the spacer 4 and adjusting the thickness of the spacer 4. Alternatively, spacers 4 having different thicknesses may be prepared and the spacers 4 may be replaced so that the thickness of the optical element becomes a desired thickness.

According to the present embodiment, the upper surface 41 of the spacer 4 has an upwardly convex curved surface, and has a point 42 having the highest height on the vertical center line Z1 of the upper shaft 31. Therefore, even if the lower surface of the upper plate 111 of the press forming machine 100 is warped, the upper plate 111 makes point contact with the center point 42 of the upper surface of the spacer 4 as in the case where the lower surface is not warped. Therefore, the upper shaft 31 of the upper mold 3 can be pushed straight down, the inclination of the upper shaft 31 can be suppressed, and the inclination eccentricity of the optical element which is a molded product can be suppressed. It should be noted that not only tilt eccentricity but also interplane eccentricity can be suppressed. The inter-plane eccentricity is an eccentricity in which the optical axes of the upper and lower surfaces of the optical element are displaced in the horizontal direction.

As shown in FIG. 3B, the upper surface 41 of the spacer 4 according to the reference embodiment is a flat horizontal plane. In this case, when the lower surface of the upper plate 111 of the press forming machine 100 is warped, unlike the case where the upper plate 111 is not warped, the upper plate 111 cannot make surface contact with the entire upper surface of the spacer 4, and the edge of the upper surface of the spacer 4 cannot be contacted. May make point contact with. As a result, an eccentric load is applied to the upper die 3, and the upper shaft 31 of the upper die 3 may be tilted. Therefore, tilt eccentricity can occur.

According to the present embodiment, as described above, the upper surface 41 of the spacer 4 has an upwardly convex curved surface, and has a point 42 having the highest height on the vertical center line Z1 of the upper shaft 31. Therefore, even if the lower surface of the upper plate 111 of the press forming machine 100 is warped, the upper shaft 31 can be pushed straight down as in the case where the upper shaft 111 is not warped, and the inclination of the upper shaft 31 can be suppressed. The radius of curvature of the upper surface 41 of the spacer 4 is, for example, 300 mm to 2600 mm, preferably 800 mm to 1600 mm. The lower surface 45 of the spacer 4 may be a flat horizontal surface. The spacer 4 can be stably placed on the upper mold 3.

As shown in FIGS. 5A and 5B, the upper surface 41 of the spacer 4 may be a flat horizontal surface, and the lower surface 45 of the spacer 4 may be a downwardly convex curved surface. The lower surface 45 of the spacer 4 has the lowest height point 46 on the vertical center line Z1 of the upper shaft 31. Therefore, even if the lower surface of the upper plate 111 of the press forming machine 100 is warped, the upper mold 3 makes point contact with the center point 46 of the lower surface 45 of the spacer 4 as in the case where the lower surface is not warped. Therefore, the upper shaft 31 of the upper mold 3 can be pushed straight down, and the inclination of the upper shaft 31 can be suppressed. The radius of curvature of the lower surface 45 of the spacer 4 is, for example, 300 mm to 2600 mm, preferably 800 mm to 1600 mm.

Further, although not shown, the upper surface 41 of the spacer 4 may be a curved surface that is convex upward, and the lower surface 45 of the spacer 4 may be a curved surface that is convex downward. However, if one of the upper surface 41 and the lower surface 45 of the spacer 4 is a horizontal flat surface, it is easy to scrape the flat surface, so that the thickness of the spacer 4 can be easily adjusted.

Further, although not shown, even if both the upper surface 41 and the lower surface 45 of the spacer 4 are flat horizontal surfaces, the upper surface of the upper die 3 may be a curved surface that is convex upward. The upper surface of the upper mold 3 has the highest point on the vertical center line Z1 of the upper shaft 31. Therefore, even if the lower surface of the upper plate 111 of the press forming machine 100 is warped, the spacer 4 makes point contact with the center point of the upper surface of the upper mold 3 as in the case where the lower surface is not warped. Therefore, the upper shaft 31 of the upper mold 3 can be pushed straight down, and the inclination of the upper shaft 31 can be suppressed. The radius of curvature of the upper surface of the upper mold 3 is, for example, 300 mm to 2600 mm, preferably 450 mm to 900 mm.

As shown in FIG. 3A, the lower die 5 has a lower shaft 51 that is inserted into the sleeve 21 of the body die 2. The lower shaft 51 presses the material M on its upper surface and transfers the shape of the upper surface to the material M. The outer peripheral surface of the lower shaft 51 slidably contacts the inner peripheral surface of the sleeve 21, and the center line Z2 of the lower shaft 51 and the center line Z0 of the sleeve 21 coincide with each other.

Further, the lower mold 5 has a flange 53 formed on the outer peripheral surface of the lower shaft 51. The flange 53 is formed at the lower end of the lower shaft 51 and is arranged horizontally. The flange 53 contacts the lower plate 112 of the press forming machine 100 and is held horizontally.

The mold 1 further has a spring 6. The material of the spring 6 is not particularly limited, but from the viewpoint of heat resistance, for example, a nickel-based superalloy or silicon nitride is used. Silicon nitride is superior in heat resistance.

The spring 6 is elastically deformed by the proximity of the upper plate 111 and the lower plate 112 of the press molding machine 100, and the restoring force of the spring 6 presses the flange 23 of the body mold 2 against the flange 53 of the lower mold 5. As a result, the two flanges 23 and 53 pressed against each other become horizontal, so that the center line Z0 of the sleeve 21 and the center line Z2 of the lower shaft 51 become vertical, and the inclinations of these center lines Z0 and Z2 are increased. Can be suppressed. That is, the inclination of the lower mold 5 can be suppressed, and the inclination eccentricity of the optical element which is a molded product can be suppressed.

The spring 6 is, for example, a coil spring, and surrounds the sleeve 21 of the body mold 2, the upper shaft 31 of the upper mold 3, and the lower shaft 51 of the lower mold 5. The center line Z3 of the spring 6 coincides with the center line Z0 of the sleeve 21, the center line Z1 of the upper shaft 31, and the center line Z2 of the lower shaft 51. The restoring force of the spring 6 can evenly push the flange 23 of the body mold 2 over the entire circumferential direction.

After the spring 6 is compressed, the length of the spring 6 is determined so that the material M is compressed. Before the material M is compressed, the spring 6 is compressed, and the restoring force of the spring 6 presses the flange 23 of the body mold 2 against the flange 53 of the lower mold 5. Therefore, the center line Z0 of the sleeve 21 and the center line Z2 of the lower shaft 51 can be matched with each other before the material M is compressed.

The mold 1 further has a spring holder 7. The spring holder 7 holds the spring 6 and holds the spacer 4. Further, the spring holder 7 regulates the deformation of the spring 6 in the horizontal direction. The spring 6 elastically deforms straight in the vertical direction during press molding. As a result, the restoring force of the spring 6 can push the flange 23 of the body mold 2 straight down, and the horizontality of the contact surface between the flange 23 and the flange 53 can be ensured. Further, the verticality (right angle) between the contact surfaces of the flanges 23 and 53 and the center line of the lower mold 5 can be ensured. As a result, the inclination of the lower mold 5 can be suppressed, and the occurrence of inclination eccentricity of the optical element which is a molded product can be suppressed.

The spring holder 7 includes, for example, a cylindrical inner cylinder 71 surrounding the sleeve 21 and a cylindrical outer cylinder 72 surrounding the inner cylinder 71. The inner cylinder 71 and the outer cylinder 72 are arranged outside the sleeve 21 of the body type 2 and inside the spring 6. The outer cylinder 72 moves in the vertical direction relative to the inner cylinder 71, and allows the spring 6 to expand and contract in the vertical direction.

The inner peripheral surface of the outer cylinder 72 slidably contacts the outer peripheral surface of the inner cylinder 71. Since the outer cylinder 72 and the inner cylinder 71 do not move relatively in the horizontal direction, the deformation of the spring 6 in the horizontal direction can be regulated. Further, it is possible to allow the spring 6 to expand and contract in the vertical direction.

The inner peripheral surface of the outer cylinder 72 contacts the outer peripheral surface of the inner cylinder 71 in the present embodiment, but it does not have to be in contact with the outer peripheral surface. In the latter case, if the outer peripheral surface of the outer cylinder 72 slidably contacts the inner peripheral surface of the stopper 10 described later, the horizontal deformation of the spring 6 can be regulated.

The spacer 4 is inserted inside the inner cylinder 71. The inner cylinder 71 determines the horizontal position of the spacer 4 and the upper mold 3. By providing the inner cylinder 71, the inclination of the spacer 4 can be suppressed and the inclination of the upper mold 3 can be suppressed.

The spacer 4 is detachably placed on the upper mold 3. By adjusting the thickness of the spacer 4, the thickness of the optical element can be adjusted.

The outer peripheral surface of the spacer 4 slidably contacts the inner peripheral surface of the inner cylinder 71. The spacer 4 can be moved in the vertical direction along the inner peripheral surface of the inner cylinder 71, and the inclination of the center line of the spacer 4 can be prevented. Therefore, the highest point 42 of the height of the upper surface 41 of the spacer 4 can always coincide with the center line Z1 of the upper shaft 31.

Further, the spring holder 7 further includes a protrusion 73 on the inner peripheral surface of the inner cylinder 71 to lift the spacer 4 from the upper mold 3. The protrusion 73 is formed in a ring shape, for example. The inner diameter of the protrusion 73 is larger than the outer diameter of the flange 33 of the upper mold 3, and the protrusion 73 does not lift the upper mold 3. By grasping and lifting the inner cylinder 71 when the molding mold 1 is disassembled, the spacer 4 can be separated from the upper mold 3 together with the inner cylinder 71.

Further, the spring holder 7 includes a lower ring 74 that holds the lower end of the spring 6 and an upper ring 75 that holds the upper end of the spring 6. The lower ring 74 is formed on the outer peripheral surface of the inner cylinder 71, and the upper ring 75 is formed on the outer peripheral surface of the outer cylinder 72. When the upper ring 75 is pushed down, the spring 6 is compressed.

The lower ring 74 is formed at the lower end of the inner cylinder 71, and is pressed against the flange 23 of the body mold 2 by the restoring force of the spring 6. As a result, the center line Z3 of the spring 6 and the center line Z0 of the sleeve 21 become vertical, and the inclination of these center lines Z0 and Z3 can be suppressed. Further, since the lower ring 74 is pushed straight down in the vertical direction by the restoring force of the spring 6, the horizontality of the contact surface between the lower ring 74 and the flange 23 of the body mold 2 can be ensured. Further, the verticality (right angle) between the contact surface between the lower ring 74 and the flange 23 and the center line of the lower mold can be ensured. As a result, the inclination of the lower mold 5 can be further suppressed, and the occurrence of inclination eccentricity of the optical element which is a molded product can be suppressed.

On the other hand, the upper ring 75 is formed at the upper end of the outer cylinder 72 and receives the upper plate 111 of the press molding machine 100. As described above, the upper ring 75 is formed on the outer peripheral surface of the outer cylinder 72, but when the outer peripheral surface of the outer cylinder 72 slidably contacts the inner peripheral surface of the stopper 10 described later, the upper ring 75 is formed. It may be formed on the inner peripheral surface of the outer cylinder 72. In this case, the spring 6 is arranged inside the outer cylinder 72 and outside the inner cylinder 71.

The spring holder 7 includes a lower ring 74 and an upper ring 75 and has a complicated shape. Therefore, the spring holder 7 is formed of a material having excellent machinability, such as stainless steel, a nickel-based superalloy, or a tungsten alloy, in order to reduce the manufacturing cost. From the viewpoint of heat resistance and dimensional change due to temperature change, a tungsten alloy, which is a material having a low coefficient of linear expansion, is preferable.

Note that FIG. 4 is a top view showing a main part of the molding mold according to the embodiment of the present invention. As shown in FIG. 4, the main part constituting the molding die 1 is preferably a coaxial concentric circle when viewed from the upper surface. As a result, the inclination of the upper mold 3 and the lower mold 5 can be suppressed, and the inclination eccentricity of the optical element which is a molded product can be suppressed.

As shown in FIGS. 2A and 2B, the molding die 1 may have a plurality of assemblies 8. The assembly 8 includes at least a body mold 2, an upper mold 3, a spacer 4, and a lower mold 5. The assembly 8 may further include a spring 6. Further, the assembly 8 may further include both the spring 6 and the spring holder 7. If the molding die 1 has a plurality of assemblies 8, the plurality of materials M can be press-molded at the same time, and optical elements can be mass-produced.

Further, when the molding die 1 has a plurality of assemblies 8, it is of great technical significance to make the upper surface 41 of the spacer 4 an upwardly convex curved surface or the lower surface 45 of the spacer 4 to be a downwardly convex curved surface. This is because when the lower surface of the upper plate 111 is warped, the magnitude or direction of the inclination of the lower surface of the upper plate 111 changes at the position of the assembly 8. However, the molding die 1 may have only one assembly 8.

When the molding die 1 has a plurality of assemblies 8, the molding die 1 may further have a transport holder 9. The transport holder 9 holds a plurality of assemblies 8 at predetermined intervals and transports them together. The transport holder 9 includes a plurality of holes 91 into which the assembly 8 is inserted at intervals in the horizontal direction. When the transport holder 9 slides in the X-axis direction, the plurality of assemblies 8 slide in the X-axis direction at the same time, and move from one processing unit 110 to another processing unit 110. The transport holder 9 may further have a plate (not shown) that closes the lower end of the hole 91.

The transport holder 9 is made of a material having a low coefficient of linear expansion in order to reduce the change in the positional relationship of the plurality of assemblies 8 due to a change in temperature, for example, cemented carbide, tungsten alloy, silicon carbide, or silicon nitride. It is formed by.

In addition to holding the plurality of assemblies 8 at predetermined intervals, the transport holder 9 may hold the stopper 10 described later. The transport holder 9 is inserted into, for example, the inside of the ring-shaped stopper 10, holds the inner peripheral surface of the stopper 10, and maintains the positional relationship between the stopper 10 and the plurality of assemblies 8.

The molding die 1 may further have a stopper 10. The stopper 10 stops the upper mold 3 and the lower mold 5 from approaching each other when the thickness of the material M reaches the set thickness during press molding of the material M. The elevating mechanism 113 lowers the upper plate 111 until the stopper 10 stops the upper mold 3 and the lower mold 5 from approaching each other, so that optical elements having the same dimensions and the same shape can be mass-produced.

The stopper 10 is, for example, a vertical ring that surrounds the plurality of assemblies 8 and stops the approach of the plurality of sets of the upper mold 3 and the lower mold 5 to each other. As a result, optical elements having the same dimensions and the same shape can be mass-produced. As described above, the number of assemblies 8 may be one.

The stopper 10 stops the lowering of the upper plate 111 by contacting both the lower plate 112 and the upper plate 111, for example, as shown in FIGS. 2B and 5B. The vertical dimension of the stopper 10 is determined so that an optical element having a desired thickness can be obtained. The lower end of the stopper 10 contacts the lower plate 112 as shown in FIGS. 2B and 5B, but it does not have to contact the lower plate 112.

Specifically, as shown in FIG. 6B, the stopper 10 may stop the lowering of the upper plate 111 by contacting both the lower ring 74 and the upper plate 111 of the spring holder 7. Although not shown, the stopper 10 may stop the lowering of the upper plate 111 by contacting both the flange 23 of the body mold 2 and the upper plate 111. Further, although not shown, the stopper 10 may stop the lowering of the upper plate 111 by contacting both the flange 53 of the lower mold 5 and the upper plate 111.

If the stopper 10 does not come into contact with the lower plate 112, the lower plate 112 will not be damaged when sliding in the X-axis direction.

The stopper 10 may be made of a material having a coefficient of linear expansion larger than that of the upper mold 3, the spacer 4 and the lower mold 5, for example, stainless steel. In the cooling zone X3, the stopper 10 shrinks relative to the upper mold 3 and the like. Therefore, the upper mold 3 descends so as to follow the cooling shrinkage of the material M, and can continue to hold the material M.

Next, a method of manufacturing an optical element using the molding die 1 will be briefly described with reference to FIGS. 1, 2A, 2B, and 3A again.

First, the lower mold 5 and the body mold 2 are assembled, the material M is put into the body mold 2, and the upper mold 3 is further inserted into the body mold 2 to assemble the assembly 8. After that, the transport holder 9 holds the plurality of assemblies 8 at predetermined intervals and holds the tubular stopper 10. The molding die 1 is composed of a plurality of assemblies 8, a transport holder 9, and a stopper 10. The molding die 1 houses the material M inside.

Next, the transfer device 120 arranges the molding die 1 between the upper plate 111 and the lower plate 112 of the press molding machine 100, and slides the molding die 1 in the X-axis direction. The mold 1 is heated stepwise in the heating zone X1. After that, the molding die 1 is pressed in the press zone X2. As a result, the material M is plastically deformed into the shape of the optical element. After that, the mold 1 is cooled stepwise in the cooling zone X3. The material M is taken out from the molding die 1 after being cooled to a temperature equal to or lower than the strain point. As a result, an optical element can be obtained. By using the molding die 1 according to one aspect of the present invention, the tilt eccentricity of the obtained optical element can be suppressed.

Although the molding mold and the method for manufacturing the optical element according to the present disclosure have been described above, the present disclosure is not limited to the above-described embodiment and the like. Within the scope of the claims, various changes, modifications, replacements, additions, deletions, and combinations are possible. Of course, they also belong to the technical scope of the present disclosure.

For example, in the above embodiment, the flat surface of the spacer 4 is scraped in order to adjust the thickness of the optical element, but a flat shim may be attached to the flat surface of the spacer 4. In the former case, the thickness of the optical element can be increased, and in the latter case, the thickness of the optical element can be reduced.

Further, in the press molding machine 100 of the above embodiment, the upper plate 111 is a movable plate and the lower plate 112 is a fixed plate, but the upper plate 111 may be a fixed plate and the lower plate 112 may be a movable plate. However, if the lower plate 112 is a fixed plate, it is easier to slide the molding die 1 sideways.

Further, in the above embodiment, the sleeve 21 and the flange 23 are preferably integrated from the viewpoint of the optical element which is a molded product, but may be separate. The same applies to the upper shaft 31 and the flange 33. The same applies to the lower shaft 51 and the flange 53.

1 Molding mold 2 Body type 21 Sleeve 23 Flange 3 Upper mold 31 Upper shaft 4 Spacer 41 Upper surface 42 Highest point 45 Lower surface 46 Lowest height point 5 Lower mold 51 Lower shaft 53 Flange 6 Spring 7 Spring holder 71 Inner cylinder 72 Outer cylinder 73 Protrusion 8 Assembly 9 Transport holder 10 Stopper

Claims (12)

Cylindrical body type and
An upper mold that presses the material of the optical element from above inside the body mold,
The spacer placed above the upper mold and
A lower mold that presses the material from below inside the body mold,
Have,
The barrel includes a vertical sleeve that houses the material.
The upper die includes an upper shaft that is inserted into the sleeve of the body die.
The lower mold includes a lower shaft that is inserted into the sleeve of the body mold.
The upper surface of the spacer has an upwardly convex curved surface and has the highest point on the vertical center line of the upper shaft.
Alternatively, a molding die in which the lower surface of the spacer is a curved surface that is convex downward and has the lowest point on the vertical center line of the upper shaft. A spring is further provided on the outside of the sleeve of the body shape so as to surround the sleeve.
The body shape further includes a flange formed on the outer peripheral surface of the sleeve.
The lower mold further includes a flange formed on the outer peripheral surface of the lower shaft.
The molding die according to claim 1, wherein the flange of the body die is pressed against the flange of the lower die by the restoring force of the spring during press molding. The molding die according to claim 2, further comprising a spring holder that holds the spring and holds the spacer. The spring holder includes an inner cylinder that surrounds the sleeve and an outer cylinder that surrounds the inner cylinder.
The molding die according to claim 3, wherein the outer cylinder can move in the vertical direction relative to the inner cylinder. The molding die according to claim 4, wherein the spacer is inserted into the inner cylinder and is separably placed on the upper die. The molding die according to claim 5, wherein the outer peripheral surface of the spacer slidably contacts the inner peripheral surface of the inner cylinder. The molding die according to claim 5 or 6, wherein the spring holder further includes a protrusion capable of lifting the spacer from the upper die on the inner peripheral surface of the inner cylinder. The spring holder has a flange formed at the lower end of the outer peripheral surface of the inner cylinder.
The molding die according to any one of claims 4 to 7, wherein the flange of the inner cylinder is pressed against the flange of the body die by the restoring force of the spring during press molding. The molding die according to any one of claims 1 to 8, further comprising a plurality of assemblies including the body die, the upper die, the spacer, and the lower die. The molding die according to claim 9, further comprising a transport holder for holding and transporting the plurality of the assemblies at predetermined intervals. The molding die according to any one of claims 1 to 10, further comprising a stopper for stopping the approach of the upper die and the lower die. The molding die according to any one of claims 1 to 11 is arranged between the upper plate and the lower plate.
A method for manufacturing an optical element, wherein the upper plate and the lower plate are brought close to each other, and the material is pushed by the upper shaft and the lower shaft to obtain the optical element.

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