JP6081630B2 - Mold press molding apparatus and optical element manufacturing method - Google Patents

Description

  The present invention relates to a mold press molding apparatus for manufacturing an optical element such as a glass lens by press-molding a molding material such as glass with a precision-processed mold, and an optical element manufacturing method.

  In recent years, an optical glass material is accommodated in a mold that has been precisely machined to a predetermined surface accuracy, and the molded surface is ground by pressing it under heat and transferring the molded surface. There is known a method of manufacturing an optical element such as a glass lens having a high-precision optical functional surface that does not require post-processing such as polishing.

  For example, Patent Document 1 discloses glass in which processing chambers such as a heating chamber, a press chamber, and a cooling chamber are arranged side by side in a circumferential direction, and molding molds containing molding materials are sequentially transferred in these processing chambers. An apparatus for manufacturing a molded body is disclosed. In this manufacturing apparatus, each processing chamber is formed by being surrounded by a case in a furnace body, and a sample table is installed on a rotary table provided so as to be intermittently rotatable around a central rotary shaft. In addition, the glass mold is continuously formed by moving the processing molds placed on the sample stage to the processing chambers as the rotary table rotates.

  Further, Patent Document 2 discloses a die moving type press molding machine that sequentially transfers molding dies to a press machine in which a heating stage, a pressure stage, and a cooling stage are arranged to perform a predetermined operation in each stage. It is disclosed. In this molding machine, as in Patent Document 1, the molding die is transferred to the subsequent stage by the die feeding arm without being transferred or variously processed in a state where the molding die is placed on the support base, and is provided on the heater block. Various types of processing are executed by directly placing the mold on the soaking plate.

  Patent Document 3 discloses a glass lens molding apparatus that does not transfer a molding die in a molding machine, and supports the molding die with three protrusions provided on a fixed portion of the molding machine, and is close to the molding die. An apparatus is disclosed in which a glass lens having a predetermined shape is formed by performing various treatments using a pressurizing unit, a heating unit, and a cooling unit.

  In Patent Document 4, a plurality of rolling members are disposed between the lower mold and the lower mold holding member, so that when the lower mold is inserted into the body mold prepared on the fixed shaft side, There has been disclosed a mold press mold that facilitates smooth movement of the mold in the horizontal direction and can smoothly insert the lower mold into the body mold to enhance the coaxiality of the upper mold and the lower mold.

Japanese Patent Publication No.7-29779 JP 2003-25100 A JP 2004-149410 A Republished 2008-053860

  By the way, the apparatus of Patent Document 1 can independently and precisely control the temperature management of each processing chamber, and can prevent temperature fluctuations associated with the transfer of the mold. In addition to this, if the molding material is displaced in the molding die due to vibration during transfer, the optical element to be molded becomes uneven, resulting in a defective shape as well as due to uneven thickness. Although the surface accuracy of the optical functional surface is deteriorated due to nonuniformity of the press load application, according to the apparatus of Patent Document 1, the mold can be smoothly transferred by the rotary table without causing vibration to the mold. it can. As described above, the apparatus of Patent Document 1 has a very excellent function in manufacturing an optical element having a high-precision optical function surface.

  However, as a result of extensive studies by the present inventors, in the apparatus of Patent Document 1, the sample stage is heated together with the mold by the heater in the processing chamber. At this time, the thermal characteristics of the mold and the sample stage are also measured. It has been found that the difference between the two causes heat exchange between the two and may disturb the temperature control of the mold. And in the recent situation that the precision required for optical elements has become increasingly severe, the knowledge that the thermal effect of the sample stage supporting the mold will adversely affect high-precision molding is obtained. It came to.

  For example, an optical element used for an imaging device such as a digital camera or an interchangeable lens has extremely high optical performance requirements. In particular, in order to mold a glass lens having a relatively large diameter (for example, φ20 mm or more) with a precision mold press, the temperature control in each processing step of the molding process, particularly the temperature management of the mold that accommodates the molding material is elaborated. However, if the apparatus of Patent Document 1 is applied as it is, there has been a concern that when more precise temperature control of the mold is required, this cannot be met.

  In addition, since the molding machine of patent document 2 is not divided for every stage, the thermal influence from an adjacent stage cannot be avoided, and precise temperature control of each shaping | molding die cannot be performed. In addition, since heat is directly transmitted from the soaking plate sandwiched from above and below, if the contact area between the molding die and the soaking plate changes due to the presence of foreign matter, the forming die However, the temperature may fluctuate, and it may become impossible to mold a molded article having a desired quality.

  Further, in the apparatus of Patent Document 3, the posture of the molding die can be uniquely determined by supporting the molding die with three projections provided on the fixing portion of the molding machine, and at the time of heating and cooling of the molding die. However, it is not easy to form the three protrusions evenly on the fixed portion. In addition, since the press load of several tens to several hundred kgf is always received at three points, the protrusion may be deformed when the number of presses is increased, and the mold may be tilted at the beginning of press, for example, the mold may be tilted. There is.

  In the press molding apparatus of Patent Document 4, the lower mold is heated by receiving heat from the lower mold holding member that is induction-heated by the mold heating apparatus. For this reason, by disposing a plurality of rolling members between the lower mold and the lower mold holding member, the horizontal mold can move smoothly in the horizontal direction, but the heating efficiency of the lower mold is deteriorated. End up.

  The present invention has been made in view of the above points. By heating the molding material accommodated in the molding die together with the molding die supported by the support base and controlling the temperature, press molding is performed. In manufacturing an optical element molded in a desired shape, the thermal influence of the support that supports the mold is prevented from reaching the mold, and the temperature of the mold is controlled more precisely to achieve high accuracy. An object of the present invention is to provide a mold press molding apparatus capable of stably mass-producing an optical element and a method for manufacturing the optical element.

  The mold press molding apparatus of the present invention is a mold press molding apparatus that heats a molding material accommodated in a molding die together with the molding die supported by a support base and performs temperature molding while controlling the temperature. A holding plate having a holding hole formed therein and a rolling element that is held so as to be able to roll in the holding hole, and the inside of the holding hole so that a part of the rolling body protrudes from the surface of the holding plate. The lower surface of the mold is supported by point contact with the lower surface of the mold by supporting the molding die on the support base via a pedestal unit in which the rolling element is accommodated.

  The optical element manufacturing method of the present invention manufactures an optical element by press-molding a molding material accommodated in a molding die together with the molding die supported by a support base and controlling the temperature. In this case, at least a holding plate in which a plurality of holding holes are formed and a rolling element that is held so as to be able to roll in the holding hole are provided, and a part of the rolling element protrudes from the surface of the holding plate. The rolling element supports the lower surface of the molding die by point contact by supporting the molding die on the support base via a pedestal unit in which the rolling element is accommodated in the holding hole. .

  According to the present invention, it is possible to suppress the thermal influence of the support base that supports the molding die on the molding die, and more precisely control the temperature of the molding die. It can be mass-produced stably.

It is a schematic plan view which shows embodiment of the mold press molding apparatus which concerns on this invention. It is explanatory drawing inside the apparatus equivalent to the AA cross section of FIG. It is explanatory drawing which shows the outline of a base unit. It is a principal part expanded sectional view which expands and shows a part of FIG. It is explanatory drawing which shows the other example of a base unit. It is a distribution map which shows the result of having measured the shape error of the surrounding area with respect to the reference | standard shape for every five support bases about the Example. FIG. 6 is a histogram of the embodiment, in which the shape error of the peripheral region with respect to the reference shape is plotted on the horizontal axis and the frequency is plotted on the vertical axis. It is a distribution map which shows the result of having measured the shape error of the peripheral area with respect to the reference | standard shape for every five support bases about the comparative example. In the comparative example, the horizontal axis represents the shape error of the peripheral region with respect to the reference shape, and the vertical axis represents the frequency.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic plan view showing an embodiment of a mold press molding apparatus (hereinafter simply referred to as “molding apparatus”) according to the present invention, and FIG. 2 is an internal view of the apparatus corresponding to the AA cross section of FIG. It is explanatory drawing.

  The molding apparatus according to this embodiment is configured by press-molding a molding material P such as a glass preform housed in the molding die M while heating the molding die M supported by the support base 3 and controlling the temperature. In order to obtain a molded body such as an optical element molded into a desired shape.

  If the shaping | molding die M used by this embodiment can press-mold the shaping | molding raw material P in a desired shape, the specific structure will not be specifically limited. For example, it includes a pair of upper mold 10 and lower mold 20 on which molding surfaces facing each other are formed, and a barrel mold 30 that regulates the mutual position of the upper mold 10 and the lower mold 20 in the horizontal direction. A material in which the molding material P is press-molded between the upper die 10 slidably guided by the barrel die 30 so as to be relatively close to and away from the lower die 20 can be used.

  In addition, the molding apparatus of the present embodiment transfers a plurality of processing chambers for performing processing including heating, pressing, and cooling to the mold M, and a support base 3 that supports the mold M to each processing chamber. The press molding is performed by sequentially performing each process such as a heating process, a pressing process, and a cooling process while transporting the molding die M in which the molding material P is accommodated. Can be.

  Here, the molding apparatus shown in FIG. 1 is formed using stainless steel or other heat-resistant metal. For example, the cylindrical upper and lower openings are sealed to form a non-oxidizing gas inside. A chamber 1 having an airtight structure that can be maintained in an atmosphere (inert gas atmosphere) is provided. In the chamber 1, there are provided an extraction / insertion chamber P1 and processing chambers P2 to P8 that are arranged at almost equal intervals along the circumferential direction.

  In the illustrated example, P1 is an extraction / insertion chamber. In this take-out / insertion chamber P1, the setting environment of the processing chambers P2 to P8 is not impaired, and the mold M that has been molded is taken out, and the mold that contains the molding material P that is newly used for molding. M is inserted.

  P2 is a first heating chamber, P3 is a second heating chamber, and P4 is a third heating chamber (or a soaking chamber). These are also collectively referred to as a heating unit, and the mold M is subjected to heat treatment. The heat treatment here is performed such that the mold M and the molding material P reach a temperature suitable for press molding, for example, a temperature corresponding to a glass viscosity of 106 to 1011 dPa · s. P5 is a press room. In the press chamber P5, a press process for applying a press load by a press mechanism is performed on the mold M that has a temperature suitable for press molding by the heat treatment in the heating unit.

  P6 is a first annealing chamber, P7 is a second annealing chamber, and P8 is a quenching chamber. These are also collectively referred to as a cooling unit, and a cooling process is performed on the mold M after the press load is applied. The quenching chamber P8 is preferably provided with a quenching mechanism using a cooling gas, and the molded body formed into a desired shape by press-molding the molding material P has a temperature that does not hinder the opening to the atmosphere, for example, glass viscosity. The mold M is cooled until the temperature becomes equal to or lower than the temperature corresponding to 1012 dPa · s.

  These processing chambers P2 to P8 are independently controlled to a temperature suitable for each processing, and are partitioned by shutters S1 to S6 in order to keep the temperature in each processing chamber at a predetermined temperature.

  Further, in the illustrated example, a support base 3 that supports and transfers the mold M is attached to a turntable 2 as a transfer mechanism that is connected to a rotation drive mechanism that rotates in the direction of the arrow in FIG. Accordingly, the molding die M inserted into the apparatus from the take-out / insertion chamber P1 and supported by the support base 3 is always in a non-oxidizing gas atmosphere (nitrogen) in a state in which the molding material (or molded body) P is accommodated. Etc.) are sequentially transferred to the processing chambers P2 to P8 which are set under an inert gas atmosphere).

  The turntable 2 has a disk shape with a diameter smaller than the inner diameter of the chamber 1 and is rotatably attached to the chamber 1 so that the center of rotation coincides with the center of the chamber 1.

  Although not specifically shown, the rotary table 2 includes a control mechanism including an index machine in the center, and the rotary table 2 repeats rotation and stop at regular intervals to rotate intermittently by a predetermined rotation angle. As a result, the support base 3 that supports the mold M moves between adjacent processing chambers. The fixed time at this time, that is, the time from when the support base 3 starts to move due to intermittent rotation of the turntable 2 until the next movement is started is the molding cycle time. It becomes.

  In the present embodiment, an example of a rotary transfer type molding apparatus is illustrated and described. However, the transfer mechanism for transferring the support base 3 is configured to be connected to a known drive mechanism mainly for linear operation. The specific configuration is not particularly limited. Further, the arrangement of the extraction / insertion chamber P1 and the processing chambers P2 to P8 is not limited to the illustrated example, and can be variously changed according to the configuration of the transfer mechanism for transferring the support base 3. Furthermore, in order to optimize each treatment of heating, pressing, and cooling according to the composition of the molding material P and the shape of the molded body such as the optical element to be obtained, for example, four heating chambers, There may be two press chambers or three slow cooling chambers. In order to improve production efficiency, the same number of heating chambers, press chambers, and slow cooling chambers may be provided side by side, and multiple types of press molding requiring different temperature conditions and different pressurization conditions may be performed simultaneously. it can.

  In the illustrated example, the first heating chamber P2, the second heating chamber P3, the third heating chamber P4, the press chamber P5, the first annealing chamber P6, and the second annealing chamber P7 are treated by a case 7, respectively. The case 7 is fixed to the chamber 1 by an appropriate means (not shown). As shown in FIG. 2, the bottom wall 7a of the case 7 is formed with a slit 7b extending in the circumferential direction that serves as a movement path of the support base 3 when the mold M is transferred, and passes through the slit 7b. The support table 3 enters each processing chamber.

  Here, FIG. 2 shows the inside of the first heating chamber P2 as a representative, but the second heating chamber P3, the third heating chamber P4, the first annealing chamber P6, and the second annealing chamber P7 are: Only the set temperature is different and the first heating chamber P2 can have a common structure. The press chamber P5 can also have a common structure with other processing chambers except that it includes a press mechanism.

  As shown in FIG. 2, a heating unit 8 is installed on the inner side surface of the case 7 surrounding the processing chambers P <b> 2 to P <b> 7 so as to face the transfer path of the mold M and to face each other.

  The processing chambers P <b> 2 to P <b> 7 are maintained at their respective set temperatures by adjusting the output of the heating unit 8. For example, a thermocouple is disposed at the tip of the support base 3, and the lead wire is rotated by the turntable 2. The temperature of the tip of the support base 3, that is, the bottom of the mold M, is measured by guiding to the shaft, and the output of the heating unit 8 installed in each processing chamber can be controlled based on the measurement result. .

  Moreover, the specific structure of the heating part 8 is not specifically limited, For example, the resistance heater etc. which generate | occur | produce a radiant heat can be used. When a resistance heater is used as the heating unit 8, the strip-like resistance heating heating element is attached almost symmetrically to the opposite side surfaces while meandering several times in the vertical direction along the inner side surface of the case 7. Is preferred. At this time, a reflector 9 that covers the inner surface of the case 7 is disposed in the case 7 so as to reflect the radiant heat emitted from the heating unit 8 and efficiently apply the radiant heat to the mold M. It is preferable to keep it.

  Further, in the illustrated example, the support 3 for supporting the forming mold M and transferring the forming mold M to each processing chamber where heat treatment, press processing, and cooling processing are performed is a hollow cylindrical shape that stands vertically. The upright part 3b is provided. The support 3 is attached to the turntable 2 by fitting a base 3 c provided on the lower end side of the upright portion 3 b into a hole 2 a formed on the outer peripheral side of the turntable 2. Further, a mold support portion 3a for supporting the molding die M is provided on the upper end side of the upright portion 3b, and the mold support portion 3a includes a plurality of pins for preventing the molding die M from falling over as shown in the figure. 6 is preferably provided.

  The support base 3 is provided with a plurality of upright portions 3b with respect to one base portion 3c, and the mold support portion 3a provided on the upper end side of each upright portion 3b supports the molding die M to perform heat treatment. The plurality of molding dies M can be moved together in each processing chamber where the pressing process and the cooling process are performed. By doing so, it is possible to transfer a plurality of molds M to each processing chamber at the same time, arrange a plurality of molds M in one processing chamber, and perform the same process at the same time. Can be improved.

  By the way, such a support base 3 moves through each processing chamber where heat treatment, press treatment, and cooling treatment are performed in a state where the mold M is supported, is heated together with the mold M, and is pressed to the mold M. When a load is applied, the mold M is supported against the press load. For this reason, the support base 3 is normally formed using metal materials, such as stainless steel which has the intensity | strength which can be equal to a press load, heat resistance, toughness, and workability.

  On the other hand, the mold M is typically represented by ceramics such as silicon carbide and silicon nitride, cemented carbide such as tungsten carbide, etc., because it is necessary to have characteristics such as predetermined hardness, low thermal expansion, and denseness. In general, ceramic materials have higher thermal conductivity than metal materials such as stainless steel.

  For this reason, the mold M has a relatively higher thermal conductivity than the support 3, and as it moves through the processing chambers where heat treatment, press treatment, and cooling treatment are performed, its thermal environment Due to the change, heat exchange occurs between the mold M and the support 3.

  For example, when the heat treatment is performed, the temperature of the mold M is higher than that of the support base 3, but the temperature of the mold M increases as the temperature of the mold M becomes higher than the temperature of the support base 3. Heat transfer from M to the support base 3 having a low temperature occurs. In addition, when the cooling process is performed, the mold M is easier to cool than the support table 3, but as the temperature of the mold M becomes lower than the temperature of the support table 3, Heat transfer to the mold M having a low temperature occurs.

  When such heat exchange is performed between the mold M and the support base 3, a temperature difference occurs between the lower mold 20 side contacting the support base 3 and the upper mold 10 side, and the temperature of the entire mold M is reduced. It becomes difficult to heat and cool so as to change uniformly. In particular, when a large-diameter glass lens is molded, the mold M and the mold support portion 3a of the support base 3 also have a large diameter, the contact area between them increases, and a partial temperature distribution on the surface where both come into contact easily occurs. Therefore, it becomes more difficult to heat and cool the molding die M so that the temperature of the entire mold M changes uniformly.

  And when such a temperature difference arises in the shaping | molding die M, we are anxious about the surface precision (asp, habit) of the glass lens by which press molding is carried out.

  In addition, the plurality of support tables 3 that support the mold M and transfer it to the processing chambers have their thermal characteristics due to slight differences in thickness and shape, partial thermal deterioration that occurs over time, and the like. It must also be taken into account that there are variations. If the support mold 3 has such a variation in thermal characteristics, heat exchange with the mold M is not constant, and an optical element such as a glass lens can be formed with high shape reproducibility. There is also a concern that this may hinder accurate mass production.

  Further, when the support table 3 and the mold M are in contact with each other on a smooth surface, the mold M is adhered to the support table 3 after being subjected to press molding by applying a predetermined press load to the mold M, and the mold There is also a concern that it may be difficult to remove M from the support 3.

  For this reason, in the present embodiment, when the mold M is supported by the mold support portion 12 of the support base 10, the pedestal unit 5 is disposed on the mold support portion 3a as shown in FIG. The mold M is supported via the pedestal unit 5. As a result, when the mold M is heated and cooled, the heat exchange between the mold M and the support table 3 is suppressed so that the thermal influence of the support table does not reach the mold, and the support is supported. The sticking between the base 3 and the mold M is prevented from occurring.

  Here, FIG. 3 is an explanatory view showing an example of the pedestal unit, FIG. 3 (a) is a plan view of the pedestal unit, and FIG. 3 (b) is a cross-sectional view along BB in FIG. 3 (a). is there. 4 is an enlarged cross-sectional view of a main part showing a part surrounded by a one-dot chain line in FIG.

  As shown in these drawings, the pedestal unit 5 includes a disk-shaped receiving plate 51, a holding plate 52 in which a plurality of holding holes 52a are formed, and rolling in each holding hole 52a formed in the holding plate 52. And a rolling element 53 that can be held. The receiving plate 51 and the holding plate 52 are coupled by, for example, press-fitting, welding, screwing, or the like in a state where the rolling elements 53 are accommodated in the holding holes 52a formed in the holding plate 52. Further, as the rolling element 53, it is preferable to use a true spherical member having a diameter of 0.5 to 10 mm.

  The holding hole 52a formed in the holding plate 52 is formed so as to penetrate in the thickness direction of the holding plate 52, but is slightly larger than the diameter of the rolling element 53 so that the rolling element 53 can be held in a rollable manner. The inner diameter is set. And the part opened to the surface side of the holding plate 52 is larger than the diameter of the rolling element 53 so that a part of the accommodated rolling element 53 protrudes on the surface of the holding plate 52 and does not leave the holding hole 52a. The diameter is reduced to be smaller (see FIG. 3B).

  At this time, the thickness of the holding plate 52 is slightly smaller than the diameter of the rolling element 53, and is less than the radius of the rolling element 53, preferably 0.1 to 2 mm from the surface of the holding plate 52. The shape and dimensions of each part are appropriately set so that a part of the rolling element 53 protrudes.

  By supporting the mold M via the pedestal unit 5, the rolling elements 53 protruding from the surface of the holding plate 52 directly support the lower surface of the mold M substantially in point contact. Therefore, the contact area is supported in a point-contact manner, and the contact area can be reduced. This suppresses heat exchange between the mold M and the support table 3 so that the thermal influence of the support table does not reach the mold, and the support table 3 and the mold M stick to each other. It can be prevented from occurring.

  As described above, it is preferable to use a spherical member having a diameter of 0.5 to 10 mm as the rolling element 53. However, if the diameter of the rolling element 53 is too small, a part of the rolling element 53 is used. There is a possibility that the height protruding from the surface of the holding plate 52 cannot be sufficiently secured, and heat exchange between the mold M and the support base 3 cannot be effectively suppressed. On the other hand, if the diameter of the rolling elements 53 is too large, the number of the rolling elements 53 included in the pedestal unit 5 cannot be made sufficient, and when a press load is applied, the load on the individual rolling elements 53 is increased. There is a possibility that the rolling element 53 may be damaged due to being too large.

  Further, by holding the rolling element 53 so as to be able to roll, uneven wear of the rolling element 53 can be suppressed, the service life of the rolling element 53 can be extended, and the pedestal unit 5 can be used over a long period of time. Moreover, the rolling element 53 held by the holding plate 52 is only allowed to roll in the holding hole 52a and cannot move freely. Even if the support surface is inclined with respect to the horizontal plane, the rolling elements 53 do not roll and are unevenly distributed at a certain place. Thereby, the formed body M can be always supported uniformly without the posture of the mold M supported on the support base 3 being inclined.

  As shown in FIG. 3A, the holding holes 52a for holding the rolling elements 53 so as to be able to roll are formed in the holding plate 52 in a substantially equal pitch arrangement without being partially unevenly distributed. Is preferred. The arrangement of the holding holes 52a is not limited to the staggered arrangement shown in the figure, and may be, for example, a lattice, concentric, or radial arrangement.

  The number of holding holes 52a, that is, the number of rolling elements 53 is appropriately set from the viewpoint of suppressing heat exchange between the mold M and the support third, and temporarily increases the number of holding holes 52a. Thus, when the rolling elements 53 are held in the holding holes 52a, the number of the rolling elements 53 in contact with the mold M increases, and heat exchange between the mold M and the support base 3 is likely to occur. There is concern. For this reason, it is preferable to keep the number of holding holes 52a, that is, the number of rolling elements 53 at a predetermined number in consideration of the press load applied during the pressing process.

  For example, the following relational expression (1) is satisfied, where Pmax is the maximum load applied to the mold M during the pressing process, N is the number of rolling elements 53 to be used, and Pn is the average load applied to each rolling element 53. Thus, it is preferable to set the number N of rolling elements 53.

      Pn = Pmax / N ≧ 5 [kgf] (1)

  Taking the case where the maximum load Pmax is 300 kgf as an example, in this case, the number N of rolling elements 53 is preferably 60 or less from the above equation (1).

  If the number N of rolling elements 53 is increased so that the value of Pmax / N is less than 5 kgf, heat exchange between the mold 9 and the support base 10 is likely to occur, and precise temperature management of the mold 9 becomes difficult. On the other hand, when the value of Pmax / N exceeds 20 kgf, the load on each rolling element 53 becomes too large, and the rolling element 53 or the receiving plate 51 may be damaged or deformed, and a desired effect may not be obtained. is there. For this reason, it is desirable that the number N of rolling elements 53 is set so that the value of Pmax / N is 20 kgf or less so that the following relational expression (2) is satisfied together with the relational expression (1). .

      Pn = Pmax / N ≦ 2 [kgf] (2)

  Further, as described above, it is preferable to use a spherical member having a diameter of 0.5 to 5 mm as the rolling element 53. However, the holding hole 52a for holding the rolling element 53 so as to roll is provided on the holding plate. 52, when the total area of the holding holes 52a (the area of the portion excluding the reduced diameter opening portion) is Sa and the surface area of the holding plate 52 is S, the following relational expression It is preferable to satisfy (3).

        S ≧ Sa × 2 (3)

  As an example, a case where the radius of the holding plate 52 is 20 mm and the surface area S of the surface is 400πmm 2, in this case, the total area Sa of the holding holes 52a is 200πmm 2 or less from the above equation (3). Thus, it is preferable to set the number of holding holes 52 a formed in the holding plate 52.

  When the holding holes 52a are formed in such a number that the total area Sa of the holding holes 52a exceeds half of the area S of the surface of the holding plate 52, the number of rolling elements 53 accommodated in the holding holes 52a and in contact with the mold M is large. As a result, heat exchange between the mold M and the support 3 is likely to occur, and precise temperature management of the mold M becomes difficult.

  Further, the rolling elements 53 can be arbitrarily thinned out as necessary without being accommodated in all of the holding holes 52 a formed in the holding plate 52. For example, in consideration of variations in the thermal characteristics of each support base 3, in the pedestal unit 5 disposed on the support base 3 having a relatively large thermal influence, the number of rolling elements 53 may be thinned to reduce the number thereof. it can. In particular, when a large-diameter lens (for example, a lens having a diameter of 30 mm or more) is press-molded, the mold M is also large, so that a temperature distribution in one mold M is likely to occur. By thinning out, the temperature distribution of the mold M can be adjusted and reduced.

  It should be noted that the number of rolling elements 53 provided in the pedestal unit 5 takes into consideration the fact that heat exchange between the mold M and the support base 3 can be effectively suppressed and the press load applied during the pressing process. More specifically, the number of rolling elements 53 having a diameter of 0.5 mm to 5 mm is preferably 30 to 80.

  The receiving plate 51 and the holding plate 52 that form the pedestal unit 5 can be formed using an alloy having high hardness and high heat resistance such as tungsten alloy, tungsten carbide, titanium carbide, cermet, and the like. In particular, the receiving plate 51 is preferably made of a material having high hardness so as not to be deformed or broken even when a press load of several tens to several hundreds kgf is applied via the rolling elements 53.

  Further, like the receiving plate 51, the rolling element 53 is made of a material having a high hardness such as silicon nitride, silicon carbide, zirconia, alumina so as not to be deformed or damaged even when a press load of several tens to several hundred kgf is applied. It can be formed using a material having high hardness and high heat resistance such as ceramics such as tungsten alloy, tungsten carbide, titanium carbide, and cermet.

  Next, the present invention will be described in more detail with reference to specific examples.

  [Example]

  In an existing mold press molding apparatus similar to the example shown in FIG. 1, a pedestal unit 5 as shown in FIG. 3 is arranged on the mold support portion 3a of the support base 3, and molding is performed in the take-out / insertion chamber P1. An operation for taking out the finished mold M and an insertion operation for carrying the mold M containing the molding material P newly used for molding into the molding apparatus were performed. The mold M was supported by the mold support portion 3 a of the support base 3 via the pedestal unit 5. Then, press molding was repeatedly performed through various processes of heating, pressing, and cooling while sequentially transferring the molding die M to each of the processing chambers P2 to P8 with the rotation of the turntable 2. By such press molding, a concave meniscus lens having a press diameter of 33 mm, a center thickness of 1.3 mm, and a peripheral thickness of 8 mm was continuously molded.

  In addition, as the forming material P, lanthanum borate optical glass M-TAF101 (manufactured by HOYA Corporation) was used.

  The pedestal unit 5 has an outer diameter of 50 mm, a combined thickness of the receiving plate 51 and the holding plate 52 of 4 mm, the number of holding holes 52a, 40 carbide rolling elements 53 accommodated in the holding holes 52a. Having a diameter of 2 mm was used.

  FIG. 6 shows the result of measuring the shape error of the peripheral region with respect to the reference shape (hereinafter referred to as “periphery F ′”) for each of the five support stands for the molded glass lens. FIG. 7 shows a histogram in which the peripheral F ′ is on the horizontal axis and the frequency is on the vertical axis.

  [Comparative example]

  A similar glass lens was continuously molded in the same manner as in Example except that the mold was directly supported by the mold support portion of the support base without using the pedestal unit.

  FIG. 8 shows the result of measuring the periphery F ′ for each of the five support bases for the molded glass lens. FIG. 9 shows a histogram in which the peripheral F ′ is on the horizontal axis and the frequency is on the vertical axis.

  As can be seen from the comparison between the embodiment and the comparative example, by supporting the molding die to the mold support portion of the support table via the pedestal unit, the shape error that has occurred between the plurality of support tables is improved, The variation could also be reduced. Further, in the comparative example, there were some that did not fall within the standard range, but in the example, all the molded glass lenses were within the standard range.

  Although the present invention has been described with reference to the preferred embodiment, it is needless to say that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. .

  For example, in the above-described embodiment, the base unit 5 includes the receiving plate 51, the holding plate 52 having the plurality of holding holes 52a, and the rolling elements 53 that are held so as to roll within the holding holes 52a. Although shown, the receiving plate 51 may be omitted as shown in FIG. In this case, the mold support portion 3 b provided on the support base 3 can have the function of the receiving plate 51.

  5 is an explanatory view showing another example of the pedestal unit 5, and is an enlarged cross-sectional view of a main part corresponding to FIG. The same components as those in the example shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof is omitted.

  Further, in the above-described embodiment, a mold press provided with a plurality of processing chambers for performing each process including heating, pressing, and cooling, and a transfer mechanism for sequentially transferring the support base 3 supporting the mold M to these processing chambers. Although the example of the shaping | molding apparatus was shown, it is not limited to this. INDUSTRIAL APPLICABILITY The present invention is applicable to a mold press molding apparatus that press-molds a molding material accommodated in a molding die together with the molding die supported by a support base and performs temperature control, and an optical element manufacturing method. .

  In the above-described embodiment, an example in which a concave meniscus lens is continuously formed has been described. Applicable when molding. In particular, when manufacturing an optical element having a lens diameter (press diameter) of 30 mm or more, the present invention can be applied to suppress the temperature distribution in the molding surface and to control the temperature of the mold more precisely. Therefore, high-precision optical elements can be stably mass-produced.

  The present invention can be widely used as a technique for press-molding an optical element such as a glass lens.

3 support base 5 base unit 51 receiving plate 52 holding plate 52a holding hole 53 rolling element M mold P molding material P1 take-out / insertion chamber P2 first heating chamber P3 second heating chamber P4 third heating chamber P5 press chamber P6 first Slow cooling room P7 Second slow cooling room P8 Rapid cooling room

Claims (9)

A mold press molding apparatus for press-molding a molding material accommodated in a molding die together with the molding die supported by a support base while controlling the temperature, and a holding plate having a plurality of holding holes; And a pedestal in which the rolling element is accommodated in the holding hole so that a part of the rolling element protrudes from the surface of the holding plate. By supporting the molding die on the support base via a unit, the rolling element is supported in a point contact manner on the lower surface of the molding die,
The holding plate is reduced in diameter so that the opening of the holding hole is smaller than the diameter of the rolling element so that the rolling element is not detached from the holding hole, and the rolling element is placed in the holding hole. Rolling is permitted ,
A mold press molding apparatus, wherein the rolling elements housed in the pedestal unit are thinned out in order to adjust and reduce the temperature distribution of the mold. The said pedestal unit is provided with the receiving plate couple | bonded with the said holding plate, The said holding plate and the said receiving plate are couple | bonded in the state which accommodated the said rolling element in the said holding hole. Mold press molding equipment. A plurality of processing chambers for performing each processing including heating, pressing, and cooling on the molding die, and a transfer mechanism for sequentially transferring the support table supporting the molding die to the processing chambers. The mold press molding apparatus according to 1 or 2. The mold press molding apparatus according to claim 1, wherein the holding plate is fixed to the support base. The mold press molding apparatus according to any one of claims 1 to 3, wherein the number of the holding holes is a number in which a total area of the plurality of holding holes satisfies a half or less of a surface area of the holding plate. A holding plate in which a plurality of holding holes are formed when an optical element is manufactured by press-molding a molding material accommodated in a molding die together with the molding die supported by a support base while controlling the temperature. And a rolling element that is rotatably held in the holding hole, and the rolling element is accommodated in the holding hole so that a part of the rolling element protrudes from the surface of the holding plate. By supporting the molding die on the support base via a pedestal unit, the rolling element supports the lower surface of the molding die in a point contact manner,
The holding plate is reduced in diameter so that the opening of the holding hole is smaller than the diameter of the rolling element so that the rolling element is not detached from the holding hole, and the rolling element is placed in the holding hole. Rolling is permitted ,
A method of manufacturing an optical element , wherein the temperature distribution of the mold is adjusted and reduced by thinning out the rolling elements housed in the pedestal unit . The said base unit is provided with the receiving plate couple | bonded with the said holding plate, The said holding plate and the said receiving plate are couple | bonded in the state which accommodated the said rolling element in the said holding hole. A method for manufacturing an optical element. The method of manufacturing an optical element according to claim 6 , wherein the holding plate is fixed to the support base. The number of the holding holes is a number in which the total area of the plurality of holding holes satisfies less than half of the surface area of the holding plate.
The manufacturing method of the optical element of Claim 6 or 8 .

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