JP4932580B2 - Optical element manufacturing apparatus and optical element manufacturing method - Google Patents

Description

  The present invention relates to an apparatus for manufacturing an optical element from molten glass and a manufacturing method for manufacturing an optical element from molten glass.

  In recent years, in the field of optical devices such as digital cameras and projectors, miniaturization and weight reduction are required, and accordingly, miniaturization of optical elements and reduction of the number of lenses used have become issues.

  In general, the lenses constituting the optical system generally include a spherical lens and an aspheric lens. Many spherical lenses are manufactured by cold working (grinding / polishing, etc.) a glass material, or by cold working a glass molded product obtained by reheat press molding. On the other hand, an aspherical lens is formed by press-molding a heat-softened spherical, elliptical, or flat glass lump (for example, a preform) with a mold having a high-precision molding surface, and the shape of the high-precision molding surface of the mold. It is the mainstream that is obtained by transferring the material to a preform, that is, manufactured by precision press molding.

  Here, the preform can be produced by once forming molten glass into a sheet glass and performing cold working such as cutting, grinding, and polishing. However, this method has the disadvantages that the cost for cold working is high and the yield of the material is poor. Therefore, depending on the type of glass, there is a means for preparing a preform without cold working by melting the raw material with a melting apparatus and then dropping it onto a mold from a nozzle or the like to float the glass lump. It has been adopted.

In addition, research has also been conducted to continuously produce optical elements from glass raw materials by connecting a glass lump manufacturing apparatus and a precision press molding apparatus for cost reduction (see, for example, Patent Document 1).
JP-A-8-26739

  However, the time required to perform precision press molding of one preform is usually significantly longer (usually about 1 minute) than the time required to produce one preform (usually 5 seconds or less). It is. Therefore, there is a problem that even if the two are simply connected, the precision press molding process is not in time. However, precision press molding machines are very expensive, and simply increasing the number is not practical. Therefore, there is a need for a technique for improving the material yield and producing the optical element at a low cost by adjusting the cycle of preform production and precision press molding without increasing the number of precision press molding machines as much as possible. It was.

  The present invention has been made in view of the above problems, and an object thereof is to provide an optical element manufacturing apparatus and an optical element manufacturing method for manufacturing a preform in accordance with the time required for precision press molding. To do.

  The inventor of the present invention has completed the present invention by adjusting the time for producing a glass lump in relation to the precision press molding time and reducing the time required for precision press molding under a certain condition.

  (1) (i) a glass lump manufacturing apparatus that melts optical glass, divides the molten glass into a predetermined volume or mass, and forms a glass lump, (ii) a conveying apparatus that conveys the glass lump, and (iii) A precision press molding apparatus for precision press molding the conveyed glass lump, and the average time required for precision press molding in the precision press molding apparatus is a (seconds / piece), and the number of precision press molding apparatuses Is a time period (seconds / piece) required for forming a glass lump in the glass lump manufacturing apparatus, wherein a / b ≦ c.

  (2) In the glass lump production apparatus, the outflow amount of the molten glass is 0.5 g / second or less, and in the glass lump production apparatus, the time required for forming the glass lump is 2 seconds / piece or more. The apparatus for manufacturing an optical element according to (1), which is characterized in that

  (3) According to (1) or (2), the transport device receives the glass block in a tray heated from 100 ° C. to 400 ° C. and transports the glass block while maintaining the temperature. The manufacturing apparatus of the optical element of description.

  (4) The temperature according to any one of (1) to (3), wherein the temperature of the glass block supplied to the precision press-molding manufacturing apparatus through the transport apparatus is 50 ° C. or higher. Device manufacturing equipment.

  (5) By generating heat turbulence around the glass lump by heat radiation from the heated and maintained glass lump, and preventing adhesion of foreign matters such as dust and dust on the surface of the glass lump, The apparatus for manufacturing an optical element according to any one of (1) to (4), wherein a cleaning device is omitted.

  (6) The optical element according to any one of (1) to (5), wherein a ratio of a total weight of the optical element after precision press molding to a total outflow amount of the molten glass is 90% or more. Manufacturing equipment.

  (7) (i) melting the optical glass, dividing the molten glass into a predetermined volume or mass, forming a glass lump, (ii) conveying the glass lump, and (iii) being conveyed A precision press molding machine comprising: a step of precision press molding the glass lump, wherein a (second) is an average time required for precision press molding in the step of precision press molding the glass lump. When the number is b, the step of adjusting the time c so that the time c (second / piece) required for forming the glass block in the step of forming the glass block is performed within the range of a / b ≦ c. A manufacturing method of an optical element characterized by including.

  (8) In the step of forming the glass lump, the outflow amount of the molten glass is 0.5 g / second or less, and in the step of forming the glass lump, the time required for forming the glass lump is 2 seconds / piece or more. (7) The method for manufacturing an optical element according to (7).

  (9) The step of transporting the glass block is characterized in that the glass block is received in a tray heated to 100 ° C. to 400 ° C., and the glass block is transported while maintaining the temperature (7) or The manufacturing method of the optical element as described in (8).

  (10) The temperature of the glass lump supplied to the step of precision press molding through the step of conveying the glass lump is set to 50 ° C. or higher, (7) to (9) Of manufacturing an optical element from molten glass.

  (11) By generating heat turbulence around the glass lump by heat radiation from the heated and maintained glass lump, and preventing adhesion of foreign matters such as dust and dirt on the surface of the glass lump, The method for manufacturing an optical element according to any one of (7) to (10), wherein the cleaning step is omitted.

  (12) The optical element according to any one of (7) to (11), wherein a ratio of a total weight of the optical element after precision press molding to a total outflow amount of the molten glass is 90% or more. Manufacturing method.

  According to the present invention, since the molding of the glass lump, the conveyance of the glass lump and the precision press molding are performed consistently, the optical element can be efficiently produced from the molten glass. In addition, steps such as cleaning can be omitted, and the productivity of optical elements can be improved.

  Hereinafter, embodiments of the optical element manufacturing apparatus and the manufacturing method of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be appropriately selected within the scope of the object of the present invention. Can be implemented with changes. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.

  As shown in FIGS. 1 and 2, a manufacturing apparatus 100 (hereinafter referred to as a manufacturing apparatus) for manufacturing an optical element from molten glass includes a glass lump manufacturing apparatus 400, a precision press molding apparatus 300, a transport apparatus 700, and a transfer apparatus. 500, 600.

  The glass lump manufacturing apparatus 400 forms the molten glass C flowing down from the flow path 200 into a glass lump E using a mold.

(Flow path)
The channel 200 is connected to a melting furnace (not shown), and drops the molten glass C melted in the melting furnace.

  The flow path 200 is provided with a sensor or the like (not shown) so that the molten glass C can be divided into a predetermined volume or a predetermined mass every predetermined time. You may control dripping so that it may have a predetermined mass.

(Glass lump manufacturing equipment)
1 and 2, the glass lump manufacturing apparatus 400 includes, for example, a rotary table 422 that is rotatably supported and a melt that flows out from the lower end of the flow path 200 and is disposed on the concentric position of the peripheral edge of the rotary table 422. And a plurality of molds 430 capable of receiving glass.

  Specifically, the glass lump manufacturing apparatus 400 includes a rotary shaft 425 rotatably supported by a rotary shaft 425 and a rotary shaft 425 connected to a rotation drive source (not shown). The glass lump manufacturing apparatus 400 may be provided with a cooling device (not shown) around the rotating shaft 425 depending on circumstances.

  The molding die 430 disposed on the rotary table 422 moves directly below the flow path 200 when the rotary table 422 rotates, and the molten glass C is dropped from the flow path 200 onto the molding die 430.

  It is preferable that the glass lump manufacturing apparatus 400 can float form the molten glass on a mold. As a mode of flotation molding, methods described in known documents such as JP-A-6-122526, JP-A-8-319124, JP-A-8-325021, and JP-A-2002-310439 can be used.

  Moreover, in order to float mold molten glass, it is preferable to use a porous material for the mold and to eject gas from the holes, but non-porous as described in JP-A-2003-40632 An inverted conical shape made of a quality material may be used. Further, in some cases, as described in JP-A-2004-300020, it may be once received by a support (receiving mold) before entering the forming mold.

  When the flow channel 200 drops molten glass on the mold 430, a sensor (not shown) detects the molten glass C or the rotary table 422 is rotated by a predetermined angle by control in accordance with a preset time. The mold 430 that has received C moves as the rotary table 422 rotates. As the turntable 422 rotates, the mold 430 moves from directly below the flow path 200 to directly below the first transfer device 500. During this time, the molten glass is formed into a curved body, cooled, and becomes a glass lump E.

  Moreover, when the temperature of the glass lump E falls rapidly, the glass lump may cause disadvantages such as cracks and chips. In such a case, it is preferable to arrange an arbitrary number of heating devices at arbitrary locations and to heat the molding die to a predetermined temperature. This prevents a rapid temperature drop of the mold and consequently makes it difficult to increase the defective rate of the glass molded product.

  Note that the lower end 200a of the flow path 200 is located immediately above one of the plurality of molds 430 when the rotary table 422 is stationary.

(First transfer device and second transfer device)
In the manufacturing apparatus of the present invention, a glass lump or an optical element can be transferred appropriately using a transfer device depending on the arrangement of each machine. In FIGS. 1 and 2, the glass lump manufacturing apparatus 400, the transport apparatus 700, An example in which a transfer device is used as appropriate between the transfer device 700 and the precision press molding device 300 is shown.

  Among these, when the rotary table 422 is in a stationary state, the first transfer device 500 is positioned directly above one of the plurality of molds 430 or the plurality of molds, and takes out the glass block from the mold 430, Transfer to the transfer device 700.

  The mode of the transfer device is not particularly limited, and may be a method of adsorbing a glass lump or a device that can be gripped by a mechanical arm.

(Transport device)
As shown in FIG. 3, the transport device 700 includes a tray 762 that houses the glass block E, a conveyor 760 that is a moving device that places and moves the tray 762, and a heating device (not shown) that heats the tray 762. ) And a heat retaining device 763 for maintaining the temperature of the tray 762.

  The saucer 762 has a concave surface 762a formed on the surface so that the glass lump E can be placed thereon. The number of concave forming surfaces may be any number.

  The conveyor 760 is an example of a unit that conveys the receiving tray 762 on which the glass lump E formed by the glass lump manufacturing apparatus 400 is placed to the precision press molding apparatus 300 that is the next step. Accordingly, the conveying method is not particularly limited, and for example, a belt method or a roller method may be used. Note that FIG. 3 illustrates the case of a belt system for convenience of explanation. In this case, the tray 762 is moved by a conveyor 760 driven by a motor (not shown). The conveyor 760 may have a structure that circulates by being inverted at the end, or may have a structure that circulates via the back side of the tray 762.

  The conveyor 760 is operated by a computer controlled motor based on an optical sensor (not shown) or the like. Along with the operation of the conveyor 760, the tray 762 on which the glass block E is placed moves at a predetermined timing or stops at a predetermined position.

  As described above, the transport device 700 is preferably provided with a heating device (not shown) for heating the tray 762. This heating device (not shown) is a device that warms in advance a tray 762 on which the glass block E transferred from the first transfer device 500 is placed. This is because when the tray 762 is cold, the glass lump E is rapidly deprived of heat and is likely to cause adverse effects such as distortion. Here, although the temperature which heats the receiving tray 762 can be suitably changed according to the property etc. of the glass lump E, it is preferable to heat in the range of 100 to 400 degreeC, and in the range of 110 to 380 degreeC. Heating is more preferable, and heating in the range of 120 ° C. to 350 ° C. is most preferable. In addition, it is preferable that the temperature of the saucer 762 is conveyed, maintaining the said temperature by using the heat retention apparatus 763 mentioned later.

  Note that the heating time and heating intensity of the above heating device change appropriately depending on the thermal characteristics of the glass, and in some cases, the heating device may not be installed.

  The heating method of the heating device (not shown) may be heating by fuel such as gas or heating by electricity. However, it is necessary that the material of the tray 762 does not suffer from disadvantages such as deformation even when heated by a heating device (not shown).

  It is preferable that the transport device 700 is provided with a heat retaining device 763 for retaining the glass lump E. In precision press molding, which is a subsequent process, it is necessary to heat the glass to a temperature above the transition point, but if the temperature falls too low in advance, the time required for heating before precision press molding will be longer than necessary. Needless to say, the precision press cycle is not only meaninglessly lengthened, but it is also easy to cause disadvantages such as distortion and deformation by applying unnecessary heat history to the glass, which tends to deteriorate the yield during press molding. Because. At that time, when the glass lump E that has passed through the heat retaining device 763 is supplied to the precision press molding device 300, the temperature is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, and most preferably 100 ° C. or higher. The temperature is adjusted.

  The heat retaining means of the heat retaining device 763 is not particularly limited, but may be heated by a fuel such as a gas or by electricity, as in the above-described heating means (not shown).

  As described above, the glass lump E to be precision press-molded is heated using the heating device and the heat retaining device 763, and the temperature of the glass lump E is raised as described above, so that the glass lump until the precision press-molding is performed. Heat dissipation occurs from the surface of E, and turbulence is generated around the glass lump E. Due to this turbulent air flow, it is possible to prevent foreign matters such as dust and dust from adhering to the surface of the glass lump E. As a result, the cleaning process of the glass lump E can be omitted, and the optical element can be manufactured efficiently.

(Precision press molding equipment)
As shown in FIG. 4, the precision press molding apparatus 300 accommodates the glass lump E transferred from the second transfer apparatus 600, and a lower mold 301 that becomes a part of a mold when pressed, and a lower mold An upper mold 302 that is a part of a mold for pressing the glass lump E accommodated on the 301; a press machine 303 that presses the glass lump E supplied between the lower mold 301 and the upper mold 302; And a conveyor 304 on which the mold 301 is placed and moved. In FIG. 4, for convenience of explanation, only one precision press molding apparatus 300 is shown. However, as shown in FIG. 5, a glass lump E created by one glass lump manufacturing apparatus 400 is pressed by a plurality of machines. May be.

  The lower mold 301 has a molding surface for accommodating and molding the glass block E, and an optical element can be manufactured by pressing the upper mold 302 directly. On the molding surfaces of the lower mold 301 and the upper mold 302, a release film (not shown) that suppresses damage to the molding surfaces of the lower mold 301 and the upper mold 302 is provided. Here, the material used for the lower die 301 and the upper die 302 may be a cemented carbide such as tungsten carbide, or any material such as silicon carbide, crystallized glass, or stainless steel. As the release film, platinum group films such as platinum, iridium and palladium, carbon-based films such as diamond-like carbon (DLC), nitride films such as TiN and CrN, and known films such as Ni-P are used. it can.

  The lower mold 301 and / or the upper mold 302 are heated by a heating device (not shown) as necessary, and the glass lump E can be pressed while being heated. In addition, before putting the glass lump E on the lower mold | type 301, you may heat a type | mold beforehand.

  The press machine 303 presses the lower mold 301 and / or the upper mold 302 and presses the glass block E between the lower mold 301 and the upper mold 302. The pressing method is not particularly limited, and the pressing can be performed by a known pressing method. The time, pressure, and thermal history during pressing can be appropriately changed according to the shape of the optical element to be obtained, the material of the glass lump E, and the like.

  In FIG. 4, the lower mold 301 is moved by a conveyor 304 driven by a motor (not shown). The conveyor 304 may have a structure that circulates by being inverted at the end, or may have a structure that circulates via the back side of the lower mold 301.

  The conveyor 304 is moved and stopped by the computer being controlled by a motor based on an optical sensor (not shown) or the like, or based on a preset time. With the operation of the conveyor 304, the lower mold 301 on which the glass block E is placed is transferred at a predetermined timing and stopped at a predetermined position. In addition, the conveyor 304 should just be able to move a shaping | molding die suitably according to precision press molding, and the means should just use a well-known means, and is not limited at all.

  When the upper mold 302 is supplied onto the glass lump E, the lower mold 301 and the upper mold 302 are heated to a temperature higher than the transition point of the glass lump E and pressed by the press machine 303.

  After pressing for a certain time, the lower mold 301 and the upper mold 302 are cooled, the upper mold 302 is discharged, and the optical element obtained by pressing the glass block E is taken out.

  When the average time required for precision press molding in the precision press molding apparatus 300 is a (seconds / piece) and the number of machines of the precision press molding apparatus 300 is b, the time c required for molding the glass lump E in the glass lump manufacturing apparatus 400 It is preferable to adjust the production time of the glass lump E so that (second / piece) is performed within the range of a / b ≦ c. Here, if c is smaller than a / b, a glass lump that exceeds the processing capacity of the precision press molding machine is likely to be produced, which tends to cause a reduction in material yield. In this specification, “the average time required for precision press molding is a (second / piece)” means that when there is one precision press molding apparatus connected to the glass lump manufacturing apparatus, the precision press molding is performed. It means the time required to mold one optical element of the apparatus. When a plurality of precision press molding apparatuses are connected, it means the average molding time of each molding machine. The time c (second / piece) required for forming the glass lump E is c = t / n (seconds / second) when the glass lump manufacturing apparatus produces n pieces of glass lump E at a predetermined time t (second). Means).

  For this reason, the one where the molten glass outflow amount at the time of manufacturing the glass lump E is small is preferable, and the one where the time required for precision press molding is short is preferable. Specifically, in the glass lump production apparatus 400, the outflow amount of the molten glass C is preferably 0.5 g / second or less, more preferably 0.4 g / second or less, and most preferably 0.3 g / second or less. The time required for forming the glass mass E is preferably 2 seconds / piece or more, more preferably 3 seconds / piece or more, and most preferably 4 seconds / piece or more. However, if the outflow amount is too low, detrimental effects such as devitrification are likely to occur at the outflow, so careful attention to temperature and atmosphere management is required. Further, in the glass lump manufacturing apparatus 400, in order to reduce the time required for precision press molding of the glass lump E, it is beneficial to maintain the glass lump E in a predetermined temperature range during transportation as described above.

  In the manufacturing apparatus 100 of the present invention, the glass lump E is manufactured by the glass lump manufacturing apparatus 400, and after the precision press-molding with respect to the total outflow amount of the molten glass, is performed consistently from the conveying apparatus 700 to the precision press-forming apparatus 300. The ratio of the total weight of the optical elements is preferably 90% or more. Thereby, the loss of the molten glass C can be suppressed to the minimum, and the material yield can be improved.

  The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

It is a figure which shows an example of the outline of a structure of the manufacturing apparatus of this invention. It is a figure which shows an example of the outline of a structure of the manufacturing apparatus of this invention. It is an example of the outline of a structure of a conveying apparatus. It is an example of the outline of a structure of a precision press molding apparatus. It is the figure which showed the outline of the structure of the manufacturing apparatus at the time of using a several precision press molding apparatus.

Explanation of symbols

100 Optical element manufacturing equipment (manufacturing equipment)
200 Flow path 300 Precision press molding apparatus 400 Glass lump manufacturing apparatus 500 First transfer apparatus 600 Second transfer apparatus 700 Conveyance apparatus

Claims (8)

(I) a glass lump manufacturing apparatus that divides molten glass into a predetermined volume or mass and molds the glass lump on a mold;
(Ii) a transport device for transporting the glass block;
(Iii) a precision press molding apparatus for precision press molding the conveyed glass lump,
When the average time required for precision press molding in the precision press molding apparatus is a (seconds / piece) and the number of machines in the precision press molding apparatus is b (b is 2 or more) , The time required for molding c (second / piece) is performed within the range of a / b ≦ c,
The outflow amount of the molten glass is 0.5 g / second or less, and in the glass lump production apparatus, the time required for forming the glass lump is 2 seconds / piece or more,
The transport device receives the glass block from a receiving tray heated from 100 ° C. to 400 ° C. and different from the mold, and transports the glass block while maintaining the temperature. apparatus.   2. The optical element manufacturing apparatus according to claim 1, wherein the temperature of the glass block supplied to the precision press-molding manufacturing apparatus through the transport device is 50 ° C. or more.   A turbulent airflow is generated around the glass lump by heat radiation from the heated glass lump and the temperature of the glass lump is maintained, thereby preventing adhesion of foreign matters such as dust and dust on the surface of the glass lump. The optical element manufacturing apparatus according to claim 1, wherein the optical element manufacturing apparatus is omitted.   4. The optical element manufacturing apparatus according to claim 1, wherein a ratio of a total weight of the optical element after precision press molding to a total outflow amount of the molten glass is 90% or more. 5. (I) dividing the molten glass into a predetermined volume or mass and molding a glass lump on a mold;
(Ii) conveying the glass block;
(Iii) a step of precision press-molding the conveyed glass lump,
When the average time required for precision press molding in the precision press molding step of the glass lump is a (second), and the number of precision press molding machines in the precision press molding step is b (b is 2 or more) , A step of adjusting the time c so that the time c (seconds / piece) required for forming the glass block in the step of forming the glass block is performed within the range of a / b ≦ c,
In the step of forming the glass lump, the outflow amount of the molten glass is 0.5 g / second or less, and in the step of forming the glass lump, the time required for forming the glass lump is 2 seconds / piece,
The step of conveying the glass lump is an optical device characterized in that the glass lump is heated from 100 ° C. to 400 ° C. and received in a tray different from the mold, and the glass lump is conveyed while maintaining the temperature. Device manufacturing method.   6. The method of manufacturing an optical element according to claim 5, wherein the temperature of the glass block supplied to the step of precision press molding is set to 50 ° C. or higher through the step of conveying the glass block.   The process of cleaning the glass lump by generating turbulent airflow around the glass lump by radiating heat from the glass lump that has been heated and maintained at temperature, and preventing the adhesion of foreign matter such as dust and dust to the surface of the glass lump. The method for manufacturing an optical element according to claim 5, wherein the method is omitted.   The method of manufacturing an optical element according to any one of claims 5 to 7, wherein a ratio of a total weight of the optical element after precision press molding to a total outflow amount of the molten glass is 90% or more.

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