JP3585260B2 - Apparatus and method for manufacturing optical element - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a manufacturing apparatus and a manufacturing method for obtaining an optical element by pressing an optical element material.
[0002]
[Prior art]
Conventionally, in glass press lens molding, when a heat-softened material lens (hereinafter, referred to as a preform) is blown with a molding die, the purpose is to prevent the preform that is at a high temperature from being fused to the molding die, or As a method for shortening the time from the heat softening state of the molded lens to the cooling and solidification, a method of blowing air (or nitrogen gas) toward the outer periphery of the lens so as to forcibly perform cooling is known.
[0003]
However, the above method has a drawback that when the edge is forcibly cooled from the outer periphery, the outer peripheral portion is solidified first, and the deformation flow is stopped before the molding is completed, particularly in the case of a biconvex lens having a thin edge. there were.
Further, when the outer peripheral portion is first solidified and the inside is softened, there is a disadvantage that distortion due to shrinkage at the time of cooling and solidification occurs and a ring-shaped crack occurs.
[0004]
Therefore, in order to solve the above-mentioned drawbacks, for example, Japanese Patent Laid-Open No. 5-193962 proposes the following invention.
In the above invention, a cavity is provided in the lower part of the mold, and a cooling fluid discharge nozzle is provided there.
In the manufacturing method using these devices, a cooling fluid is discharged from the nozzle in the forming step to cool the forming die from the inside.
[0005]
[Problems to be solved by the invention]
However, in the invention described in Japanese Patent Application Laid-Open No. 5-193962, since the cooling is performed uniformly by the cooling fluid, it is not possible to further make a difference between the inside and outside of the cooling within the cooling range due to the gap, and the cooling capacity is reduced. There was a problem that fine adjustment was not possible.
[0006]
An object of the present invention according to claim 1 is to provide an optical element manufacturing apparatus capable of delicate cooling distribution control and capable of coping with uneven thickness molding of a convex or concave lens.
An object of the present invention according to claim 2 is to provide a method of manufacturing an optical element which performs delicate cooling distribution control and copes with uneven thickness molding of a convex or concave lens.
[0007]
Means and action for solving the problem
The present invention is directed to an optical element manufacturing apparatus for press-molding heat-softened glass on each of the molding surfaces of a pair of upper and lower molding dies, wherein a molding die having a void formed toward the molding surface inside at least one of the molding dies, A plurality of contact members that contact the ceiling of the gap and the plurality of contact members, wherein the center portion movably disposed in the gap is formed of a column and the outside is formed of one or more hollow cylinders. A temperature adjusting unit for adjusting the temperature, a driving unit for vertically moving the plurality of contact members independently, and controlling the temperature adjusting unit; and the plurality of contact members are independently controlled by the driving unit. An apparatus for manufacturing an optical element, comprising: a control device for controlling timing and time of contact with a ceiling portion of an air gap.
Further, in the present invention, when the heat-softened glass is pressed and formed on each of the forming surfaces of the pair of upper and lower forming dies, the glass forming step may be performed on at least one of the forming dies inside a ceiling formed toward the forming surface. A method of manufacturing an optical element, wherein a plurality of temperature-adjusted contact members each having a columnar shape at the center and one or more hollow cylindrical shapes at the outside are brought into contact with a time difference therebetween.
[0008]
In the molding of the optical element by the glass press, when the optical element is cooled while being pressed and held by the mold, the contact time of the contact member is lengthened as the thickness increases, and the cooling capacity is increased. It is possible to arbitrarily set the optical element to be strong, and to uniformly cool an optical element having a large uneven thickness.
[0009]
Embodiment 1
1 to 12 show an apparatus used in this embodiment, FIG. 1 is a schematic configuration diagram of the entire apparatus, FIG. 2 is a detailed sectional view of a portion A in FIG. 1, FIG. 3 to FIG. FIG. 10 is a side view of the lens, and FIGS. 11 and 12 are cross-sectional views of the molded lens.
[0010]
An outline of the entire apparatus will be described with reference to FIG.
An upper mold unit base 91 having an upper mold 1 at the tip and a lower mold unit base 10 (hereinafter, referred to as a unit base) having a lower mold 11 at the tip are provided in the molding chamber 93. Have been. The unit base 10 is vertically movably supported by a unit base lifting device 41 fixed on a molding machine chassis 94.
The molding chamber 93 is provided with a heating furnace 96 having a heating furnace heater 97 therein. Reference numeral 95 denotes a holder transfer arm which holds and transfers the lens holder 5 on which the material glass 6 is placed.
[0011]
Next, the lower mold 11 and its surroundings will be described with reference to FIG.
Inside the lower molding die 11, a columnar gap 11h is formed with its lower end as an opening toward the molding surface.
The unit base 10 has a cylindrical shape with a bottom, and a lid-shaped mold mounting table 10p is mounted on an upper portion thereof. A lower molding die 11 is fixed to the upper surface of the mold mounting table 10p. A hole 10h having substantially the same diameter as the gap 11h of the lower molding die 11 is provided in the mold mounting table 10p.
[0012]
On the upper surface of the bottom of the unit base 10, three lifting devices 32, 33, and 34 for independently supporting the three contact members 12, 13, and 14 to be vertically movable are fixed as driving means.
The contact member 12 is formed in a cylindrical shape at the center, and a thermocouple 12T for temperature measurement is inserted in the axial direction from the lower end surface.
The contact member 13 is formed in a cylindrical shape, and is loosely fitted on the outer periphery (outside) of the contact member 12.
The contact member 14 is also formed in a cylindrical shape, and is loosely fitted on the outer periphery (outside) of the contact member 13.
Thermocouples 13T and 14T for temperature measurement are also inserted into the contact members 13 and 14 in the axial direction from the lower end surfaces, respectively.
When each of the contact members 12 to 14 is at the lower end, a step is held so that the contact member 12 is at the highest position, the contact member 13 is at the intermediate position, and the contact member 14 is at the lowest position. Have been.
[0013]
As a material of each of the contact members 12 to 14, a material having a high heat resistance and a high thermal conductivity is preferable, and a heat-resistant iron-based alloy or a tungsten-based sintered material whose surface is subjected to a heat-resistant surface treatment is used. Is given as an example.
In this embodiment, SUS420J2 is used as a material, and the surface thereof is coated with chromium nitride. It should be noted that ceramics may be applied with an emphasis on heat resistance.
[0014]
On the inner peripheral surface of the unit base 10, three nozzles 22 to 24 for blow discharge for cooling the contact members 12 to 14 are arranged, and electromagnetic valves 22V for controlling discharge and stop of blow are provided near the tips thereof. -24V is provided as temperature control means.
The arrangement positions of the nozzles 22 to 24 are arranged with steps up and down so that the cooling blow directly hits the respective contact members 12 to 14 when the respective contact members 12 to 14 are in the lower end state. .
[0015]
In the vicinity of the unit base 10, a cooling blow supply source 60 (for example, a nitrogen gas producing device or a nitrogen gas cylinder or an inert gas cylinder) is installed, and a gas for cooling blow is supplied to each of the nozzles 22 to 24 by the air hoses 22H to 24H. Supply.
In this embodiment, one set of the nozzles 22 to 24 is arranged on the inner peripheral surface of the unit base 10. However, if a plurality of sets of the nozzles 22 to 24 are provided at equal intervals on the inner peripheral surface of the unit base 10, each contact 22 The cooling temperatures of the members 12 to 14 can be equalized and the cooling rate can be improved.
[0016]
Further, a CPU 50 (central processing unit; a personal computer or the like is used as an example of equipment to be used) is installed near the unit base 10 as a control device. The thermocouples 12T to 14T, valves 22V to 24V, lifting devices 32 to 34 and 41 are electrically connected to the CPU 50 by cables 12C to 14C, 22C to 24C, 32C to 34C and 41C, respectively. It controls the temperature of the members 12 to 14 and controls the elevating operation. Incidentally, the cables 12C to 14C, 22C to 24C, 32C to 34C, 41C and the air hoses 22H to 24H are manufactured and mounted in a layout and length that do not interfere with the operation of each element by the operation of the lifting devices 41 and 32 to 34. ing.
[0017]
As described above, the periphery of the lower molding die 11 has been described. However, regarding the peripheral device of the upper molding die 1, the lifting device 41 and the cable 41C in FIG. 2 are omitted (the upper molding die 1 does not perform the lifting / lowering operation for pressing). Others may be considered to be upside down (the cooling blow supply source and the CPU are shared with those for the lower mold 11), and description and illustration are omitted.
[0018]
Hereinafter, the operation of the present embodiment will be described. Note that 2, 3 and 4 shown in FIGS. 3 to 9 are contact members having the same configuration as the contact members 12 to 14.
In FIG. 3, reference numeral 5 denotes a lens holder, 6 denotes a raw glass, and shows a state in which the heating and softening of the raw glass 6 has been completed and the raw glass 6 has been conveyed between the upper and lower molding dies 1, 11.
In the state of FIG. 3, the cooling of the contact members 2 to 4 and 12 to 14 is completed, and the heated and softened material glass 6 is stored in the lens holder 5 and conveyed between the upper and lower molds 1 and 11. Then, the lower molding die 11 is raised, and the material glass 6 is pressed with the upper molding die 1. FIG. 4 shows the state, and 6a shows the lens after molding.
[0019]
At the same time as the raising of the lower mold 11 is completed, or with a slight time lag, cooling with air is started from the outside of the lens (the outside blow device is not shown).
Similarly, the cooling from the inside of the mold by the contact members 2 to 4 and 12 to 14 starts. In the present embodiment, the case of a convex lens is used, and the degree of heating at the center of the lens is large, and it is necessary to perform cooling from the center to the outer periphery. First, the contact member 2 located at the most central portion is lowered and the contact member 12 is raised, and contacts the upper and lower molds 1 and 11 to cool the central portion. This state is shown in FIG.
[0020]
Next, the contact member 3 immediately below is lowered and the contact member 13 is raised, and contacts the upper and lower molds 1 and 11, respectively, to expand the cooling range slightly to the outside. This state is shown in FIG.
Finally, the outermost contact member 4 is lowered and the contact member 14 is raised, and comes into contact with the upper and lower molds 1 and 11 to apply cooling to the entire lens. Cooling is continued in this state (shown in FIG. 7).
[0021]
When the cooling of the lens is completed, the upper mold 1 rises, the lower mold 11 descends, and the molded lens 6a and the upper and lower molds 1, 11 are separated. FIG. 8 shows this state. In FIG. 8, the contact members 2 to 4 and 12 to 14 are kept in contact with the upper mold 1 and the lower mold 11, respectively. However, this is not always the case depending on the elevating mechanism of the contact member.
[0022]
When the upper mold 1 reaches the upper end and the lower mold 11 reaches the lower end and stops, the contact members 2 to 4 and 12 to 14 return to the initial positions similar to FIG. This state is shown in FIG. 9, but the timing of moving the contact member to the initial position is not limited to this as described above, and may be performed while the lower molding die 11 is descending.
[0023]
As described above, assuming that the contact members 2 to 4 and 12 to 14 are in contact with the upper and lower molds 1 and 11 at times t ₂ to t ₄ and t ₁₂ to t ₁₄ , respectively, t ₂ > t ₃ > t _4. And t ₁₂ > t ₁₃ > t ₁₄ , so that the cooling time in the central part is longer, that in the outer peripheral part is shorter, and a difference in cooling capacity between the inside and outside can be provided. However, t ₂ = t ₁₂ , t ₃ = t ₁₃ , or t ₄ = t ₁₄ , in other words, the upper and lower opposing contact members 2 to 4 and 12 to 14 simultaneously contact the upper and lower molds 1, 11. You don't have to. For example, when molding the lens 6b having an extremely different R on the upper and lower surfaces as shown in FIG. 10, it is necessary to make a large difference between the inside and outside of the cooling capacity of the upper surface where the uneven thickness due to R is large. _is a _{t 2 / t 4> t 12} / t 14. That is, the start of contact _{t 2} is faster than _{t 12,} it is not a _{t 2} ≠ _{t 12.}
[0024]
FIGS. 11 and 12 are cross-sections of the molded lens 6a immediately after the cooling is completed during the molding process and immediately before the mold release, and show a high-temperature portion 6d, a medium-temperature portion 6e, and a low-temperature portion 6f, respectively.
FIG. 11 shows a case where the present invention is not applied, and FIG. 12 shows a case where the present invention is applied. In the case of FIG. 11, a lump of the high-temperature portion 6d remains inside the thick central portion, which causes distortion of the temperature difference and causes cracks and the like. However, in the case of FIG. 12, it can be seen that the thermal state of the lens is uniform from the center to the outer periphery, so that distortion due to a temperature difference is hardly generated.
[0025]
In the conventional molding using only a cooling means from the outside, in the case of a convex lens having a large uneven thickness, a large temperature difference occurs between an outer peripheral portion where cooling proceeds strongly and a center where cooling is difficult at high temperature.
According to the present embodiment, by sequentially cooling the contact members from inside the upper and lower molds, it is possible to uniformly cool the lens from the center to the outer periphery.
[0026]
Embodiment 2
FIGS. 13 to 15 are cross-sectional views showing the molding process of this embodiment.
This embodiment, the upper and lower side instead of the mold 1 and 11, the upper and lower side mold 1b, except using 11b, other configurations are the same constituent parts of the concave lens molding convex lens molding in Example 1 The same components are denoted by the same reference numerals, and description of the configuration is omitted.
[0027]
Hereinafter, the operation of the present embodiment will be described.
First, the contact members 2 to 4 and 12 to 14 are cooled by cooling blow. This state is the same as FIG. 3 in the first embodiment (however, the upper and lower side mold, 1b of concave lens molding are replaced with 11b). When the cooling is completed and the pressure enters the holding pressure cooling state from the molding pressing, the contact members 4 and 14 on the outermost periphery first contact the upper and lower molding dies 1b and 11b, respectively. Next, the contact members 3 and 13 and finally the contact members 2 and 12 at the center contact the upper and lower molds 1b and 11b.
[0028]
As described above, when each of the contact members 2～4,12,14 to upper and lower mold 1b, and the time in contact with 11b and _{t 2 ~t 4, t 12 ~t} 14, t 2 <t 3 <t 4 And t ₁₂ <t ₁₃ <t ₁₄ , and the difference between the inside and outside of the cooling capacity is strong at the outer periphery and weaker at the center, which is opposite to that of the first embodiment. However, for the same reason as in the first embodiment, it is not necessary that t ₂ = t ₁₂ , t ₃ = t ₁₃ , or t ₄ = t ₁₄ .
[0029]
According to the present embodiment, it is possible to correct uneven cooling after molding due to the thick wall of the outer peripheral portion of the concave lens, and the control accuracy is remarkably improved as compared with normal blow cooling. Furthermore, in the case of a concave lens, it is required to realize an extremely thin molding at the center portion. However, since the entire lens is uniformly cooled, the heating and softening at the center portion is maintained until the molding is completed, and the center thin portion is formed. Can greatly increase the molding limit.
[0030]
Embodiment 3
FIG. 16 is a sectional view of the device used in this embodiment.
This embodiment is different from the first embodiment in that the lower mold 11 in the first embodiment is abolished, and the lower mold 11 is replaced with a lower flat mold 11f in which no void is formed. The same components are denoted by the same reference numerals and the description thereof is omitted.
It is not necessary to provide a contact member, a contact member elevating means, a contact member elevating / lowering operation control means, and a contact member cooling means on a unit base (not shown) of the upper flat mold 11f.
[0031]
Hereinafter, the operation of the present embodiment will be described.
Since the timing of the cooling members 2 to 4 of the upper mold 1 is a convex surface, it is set such that t ₂ > t ₃ > t ₄ as in the first embodiment. In the case of a concave surface, t ₂ <t ₃ <t ₄ as in the second embodiment. That is, when applied to a convex lens, it is the same as in the first embodiment, and when applied to a concave lens, the same as in the second embodiment.
[0032]
According to the present embodiment, it is possible to reduce equipment costs by applying the present invention when the thickness of the lens to be molded is relatively small.
[0033]
In this embodiment, the lower mold 11f is used. However, the present invention is not limited to this. The lower mold 11 in the first embodiment is used, and the upper mold 1 is used instead. It is good also as an upper side flat mold where a void part is not formed and abolished. In addition, although a one-sided plane is shown as an example, the present invention is also effectively applied to a biconvex lens, a biconcave lens, a convex meniscus lens, or a concave meniscus lens having a relatively shallow R on one side.
[0034]
【The invention's effect】
The effect of the invention according to claim 1 is that even when molding a convex or concave optical element having uneven thickness, the inside of the optical element during molding can be cooled to an even temperature, and cracks caused by a temperature difference are prevented. There is no sink mark or the like, and molding with high yield can be performed.
The effect of the invention according to claim 2 is that even when molding a convex or concave optical element having uneven thickness, the cooling distribution of the internal temperature of the optical element can be finely adjusted during the molding process, and the occurrence of defects is suppressed to the limit. Thus, it is possible to set molding conditions with a high yield.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a first embodiment.
FIG. 2 is a detailed sectional view of a portion A in FIG.
FIG. 3 is a cross-sectional view showing a forming step of Example 1.
FIG. 4 is a cross-sectional view showing a molding step of Example 1.
FIG. 5 is a cross-sectional view showing a molding step of Example 1.
FIG. 6 is a cross-sectional view showing a molding step according to the first embodiment.
FIG. 7 is a cross-sectional view showing a molding step of Example 1.
FIG. 8 is a cross-sectional view showing a molding step according to the first embodiment.
FIG. 9 is a cross-sectional view showing a molding step of Example 1.
FIG. 10 is a side view showing the first embodiment.
FIG. 11 is a sectional view showing Example 1.
FIG. 12 is a sectional view showing the first embodiment.
FIG. 13 is a cross-sectional view showing a molding step of Example 2.
FIG. 14 is a cross-sectional view showing a molding step of Example 2.
FIG. 15 is a cross-sectional view showing a molding step of Example 2.
FIG. 16 is a sectional view showing a third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Upper molding die 2,3,4,12,13,14 Contact member 5 Lens holder 6 Material glass 10 Lower molding die unit base 11 Lower molding die 22,23,24 Nozzle 32,33,34,41 Lifting device 50 CPU
60 Cooling blow supply source 91 Upper mold unit base

Claims (2)

In an optical element manufacturing apparatus that press-molds the heat-softened glass on each molding surface of a pair of upper and lower molds,
At least one of the molds having a cavity formed therein toward the molding surface, and a central portion movably disposed in the cavity has a columnar shape and an outer portion formed of one or more hollow cylindrical shapes. A plurality of contact members that contact the ceiling of the gap,
Temperature adjusting means for adjusting the temperature of the plurality of contact members,
Driving means for vertically moving the plurality of contact members independently,
A control device that controls the temperature adjusting unit and controls the timing and time for bringing the plurality of contact members into contact with the ceiling of the gap independently by the driving unit,
An apparatus for producing an optical element, comprising: In press-molding the heat-softened glass on each molding surface of a pair of upper and lower molding dies, at least one of the molding dies inside the glass molding step to the ceiling portion of the void formed toward the molding surface during the glass molding step. A method for producing an optical element, comprising: contacting a plurality of temperature-controlled contact members each having a columnar shape and one or more hollow cylindrical shapes with a time difference.

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